SJ 20635-1997 Micro-area test method for residual impurity concentration in semi-insulating gallium arsenide
Some standard content:
Military Standard of the Electronic Industry of the People's Republic of China FL5971
SJ 20635-97
Test method for residual inmpurities concentration inmicrozone of semi-insulating gallium arsenide
Test method for residual impurities concentration inmicrozone of semi-insulating gallium arsenidePublished on June 17, 1997
Implementation on October 1, 1997Approved by the Ministry of Electronics Industry of the People's Republic of China Military Standard of the Electronic Industry of the People's Republic of China Test method for residual impurities concentration inmicrozone of semi-insulatinggailium arsenide1 Scope
1.1 Subject Content
SJ20635-97
This standard specifies the micro-area measurement method for the concentrations of carbon, EL2, chromium and silicon in semi-insulating gallium arsenide wafers with a thickness of 0.4~2.0mm.
1.2 Scope of application
This standard applies to the determination of the concentration of the main residual impurities EI2, chromium and silicon in semi-insulating GaAs wafers. 2 Referenced documents
SJ3249.2-89 Infrared absorption test method for carbon concentration in semi-insulating GaAs single crystals 3 Definitions
3.1 EL2 concentration EL2 concentration is an intrinsic defect in GaAs. EI2 concentration is the concentration of this defect in GaAs. 3.2 Carbon acceptor concentration is the most important electroactive center in GaAs. Carbon exists mainly in the form of acceptors occupying the valence position in GaAs. The energy level caused is above the valence band. 0.026 eV. 3.3 Difference method
A test method that puts a wafer that is basically free of the impurities being measured and has the same thickness of the matrix material as the sample being tested into the reference optical path of the spectrometer to eliminate interference caused by selective addition, reflection and scattering losses. 3.4 Air reference method When there is no addition band interfering with the absorption band of the impurity being analyzed, a reference method using air in the reference optical path of the spectrometer. 3.5 Calibration factor When calculating the concentration of the impurity being measured, it is necessary to determine the factor of the conversion relationship between the impurity concentration and the absorption intensity of the local vibration mode. 4 General requirements
4.1 Standard atmospheric conditions for measurement
The Ministry of Electronics Industry of the People's Republic of China issued on June 17, 1997 and implemented on October 1, 1997
TTTKAca-
a. Environmental source temperature: 15~35℃;
b. Relative degree: ≤60%.
4.2 Measurement environment conditions
SI20635-97
The measurement laboratory is not allowed to have mechanical shock and vibration, nor is it allowed to have electromagnetic interference, and there is no corrosive gas. A certain clean condition is required to ensure the measurement accuracy. Detailed requirements
This standard adopts an independent numbering method and lists four test methods as follows: a: Method 101 Micro-area microscopic infrared test of carbon concentration in semi-insulating gallium arsenide wafers; b. Method 102 Micro-area infrared test of EL2 concentration in semi-insulating gallium arsenide wafers; Method 103 Micro-area infrared test of chromium concentration in semi-insulating gallium arsenide wafers; c.
d. Method 104 Micro-area secondary ion mass spectrometry test of silicon concentration in semi-insulating gallium arsenide wafers. 2
1 Method Summary
SI 20635-97
Method 101
Microscopic infrared test of carbon concentration in semi-insulating gallium arsenide wafers Carbon is the main shallow acceptor impurity in semi-insulating gallium arsenide. Its local mode vibration band (frequency position of the room temperature band is 579.8cm~1.78k and the frequency position of the band is 582.5cm-11) has a corresponding relationship with the substitutional carbon concentration. The carbon concentration is calculated according to the empirical formula based on the absorption coefficient of the carbon peak in the measured infrared absorption spectrum. This standard is applicable to the determination of carbon concentration in non-doped semi-insulating gallium arsenide wafers, and its minimum detection limit is 4.0×101cni3
2 Measuring instruments
2.1 Infrared spectrophotometer or Fourier transform infrared spectrometer, the minimum resolution of the instrument The rate should be better than 1.0cm-\. 2.2 Infrared microscope, which is equipped with a mechanical stage that can move precisely in the X-Y direction and an adjustable measuring aperture. 2.378K low-temperature microscopic measurement device.
2.4 Micrometer, with an accuracy better than 0.01mm.
3 Sample preparation
3.1 Measuring sample
3.1.1 The sample is cut from a single crystal ingot with a thickness of 0.4~2.0mmc3.1.2 Use the cleavage method to cleave the sample in parallel into a narrow strip. The width of the narrow strip is the thickness required for the measuring sample, and the thickness is 2~4mm (see Figure 101-1). The cleavage surface is mirror-like and should meet the measurement requirements. Rain
3.2 The reference standard
(a) is 0.4~2.0uin Semi-insulating arsenide film; (b) is the cut strip sample,
E and S——two parallel cleavage planes;
d-original sample purity;
L—sample thickness.
Figure 1011 Narrow strip sample section diagram
3.2.1 The reference standard is cut from a non-doped carbon-free (carbon concentration is less than 3×1014cm-3) single crystal grown by the horizontal method. 3.2.2 The reference standard is prepared according to 4.3.2 of SI3249.2. 3.2.3 The final thickness difference between the reference standard and the sample measured by the differential method does not exceed 10μm. 4 Test procedure
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4.1 Method selection
SJ 20635-97
When the carbon concentration of the sample is greater than or equal to 1×1015cm-3, the room temperature differential method can be used for measurement. When the carbon concentration of the sample is less than 1×1015cm23, the 78K low temperature air reference method can be used for measurement. 4.2 Room Leakage Differential Method
4.2.1 Set the instrument parameters so that the spectrometer resolution is 0.5cm-1 or 1rm-14.2.2 Use nitrogen or dry air to fully purge the instrument optical path so that the relative humidity inside the instrument is not greater than 20%. 4.2.3 With the help of the microscope, adjust the measurement light beam to 250mm×250μmg4.2.4 Put the sample to be tested into the sample rack, and then place it on the microscope stage together. Use the hand wheel to adjust the stage. With the help of the illumination light path, observe the focus through the national mirror, accurately select the sample measurement position, and make the energy of the light beam passing through the narrow strip sample and the reference standard as large as possible. The measurement light path diagram is shown in Figure 101-2. Incident light
Destination light
Figure 101-2 Narrow strip test measurement optical path diagram
4.2.5 Scan multiple times, generally not less than 300 times. 4.2.5 Under the above conditions, measure the absorption spectra of the sample and the reference standard in the wavelength range of 574cm-1 to 590cm-1.
4.2.7 Calculate the subtraction factor and differential spectrum according to formulas (101-1) and (101-2) respectively. FCR=T/TR.
D=S- FCRX R...
Where: rs sample thickness, cm;
Tr reference standard thickness, cml
FCR——subtraction factor;
D——differential spectrum;
S sample absorption spectrum;
R--reference standard absorption spectrum.
(101 -1)
...(101 - 2)
The differential spectrum of a typical sample is shown in Figure 101-3. The carbon absorption peak at room temperature is located at 579.8cm-1, and its half width is 1.2cm10.40#
SJ20635-97
580 2579
Figure 101-3 The method for determining the half width of the absorption spectrum of a typical semi-insulating arsenide sample is shown in Figure 101-3. Determine the baseline absorbance A. And the peak absorbance A, let A=（A，+A）/2, draw a parallel line of the baseline through point A, and intersect with the two sides of the absorption band at M and N. Draw a perpendicular line to the horizontal axis through MN, and intersect with the horizontal axis at 1U2.Au=-2(cm1) is the half width. 4.378K Air Reference Method
4.3.1 Set the instrument parameters so that the spectrometer resolution is 0.5cm-1. Place the sample in the sample chamber of the low temperature accessory and cool it to 78K. In the wave number range of 574cm-1590cm~1, obtain the sample 78K absorption spectrum, and the operation procedure is the same as 4.2.2~~4.2.5. The carbon absorption peak at 78K is located at 582.5cm-1 and its half width is 0.73cm-1. 4.4 Repeat the measurement three times according to the selected method and calculate the average value of the absorbance. 5 Result calculation
5.1 The absorption coefficient α is calculated by formula (101-3). A-An
Where; α~—absorption coefficient, cm-1;
L sample thickness, cm;
A and A. —are the absorbance values at the absorption peak apex and baseline, respectively. 5.2 Carbon concentration NC) is calculated by formula (101-4). N[Cl-F×α
Where: N[C]----Carbon concentration, cm--;
（101.3)
+(101- 4)
F——Calibration factor, cm~2. When the resolution of the spectrometer is 0.5cm-1, for 300K, F=1.92×101, for 78K, F=0.803×10l6. When the resolution is 1cm-1, at 300K, F-2.34×1016. 6 Report
The measurement report should include the following:
Test date;
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Operator and test unit;
Sample source and number:
d. Diagram of sample cleavage and measurement position;
Absorption coefficient and carbon concentration;
SJ 20635-97
f. Test instrument model, selected parameters and measurement aperture, 7 Precision
The relative standard deviation of this method is 10%.
8 Notes
8.1 Regarding the calibration factor for calculating carbon concentration, it is usually (5.84~8.03)×1015cm-2 at 78K. Since low-temperature measurement is more troublesome, the carbon concentration measurement is carried out at room temperature. F is a function of temperature. The ratio of F value at room temperature to F value at 78K is in the range of 1.06 to 1.60, and F value is in the range of (1.02 to 2.11)×1015cm-2. Therefore, due to the uncertainty of F, the determination of carbon concentration is related to the selection of calibration factor F. This method selects 1.92×101°cm-2 at room temperature for calibration. B.2 usually uses 0.5c1m-1 spectral resolution for measuring carbon concentration. For microscopic infrared measurement, 1cm1-1 resolution can also be used. After a large number of experiments, it was measured that a1em~1/ag.5m=1=0.82. Therefore, when the calibration factor of 0.5cm-1 resolution at room temperature is 1.92x10lcm-2, the calibration factor of 1cm-1 resolution is 2.34×10lcm-2. Method 102
Micro-area infrared test of EL2 concentration in semi-insulating gallium arsenide wafers 1 Method Summary
The deep electron trapping light absorption coefficient of EL2 concentration in semi-insulating gallium arsenide has a corresponding relationship with its concentration. The absorption coefficient at 1.0972um can be measured and the F1.2 concentration can be calculated by the empirical calibration formula. This standard is applicable to the determination of EL2 concentration in non-doped semi-insulating gallium arsenide wafers, and is not applicable to the measurement of EL2 concentration in chromium-doped semi-insulating gallium arsenide samples.
2 Ink measuring instrument
2.1 Spectrophotometer. It can scan in the range of 0.8~2.5um and the zero line absorbance fluctuation is not large ±0.002. 2.2 Sample holder, with adjustable function, the optical size is (U.3~0.5)mm×6mmcc2.3, with a ruler, and the accuracy is better than 0.01mm
3 Sample preparation
3.1 The sample is cut from a single crystal ingot with a thickness of 0.4~2.0mm. 3.2 Use the cleavage method to cleave the sample into a narrow strip in parallel. The width of the narrow strip is the thickness required for the measurement sample, the thickness is 2~4mm, and the length is greater than 6mm (see Figure 1t1-1 in Method 101). The cleavage surface should be mirror-like and meet the measurement requirements. 4 Test Procedure
4.1 Place an empty adjustable sample holder in the sample optical path so that the energy of the light beam passing through the sample holder is not less than 15% of the energy of the aperture when no aperture is added.
SI 20635-97
4.2 Scan and calibrate the zero line by absorption method, and carefully adjust the instrument so that the fluctuation of the zero line absorbance in the range of 0.8~2.5um is not greater than ±0.002.
4.3 Place the cleaved narrow strip sample in the adjustable sample holder and place it in the sample optical path so that the light beam is aligned with the desired measurement position. The measurement optical path is shown in Figure 101-2 of Method 101. 4.4 Record the sample absorption spectrum in the wavelength range of 0.82.5μm to obtain the absorbance A-wavelength input curve. The absorption spectrum of a typical semi-insulating gallium arsenide sample is shown in Figure 102-1. .69
Sample measurement 0.386cm
Figure 102-1
5 Result calculation
Wavelength n
Absorption spectrum of typical semi-insulating sample 5.1 According to Figure 102-1, calculate the EL2 concentration NEl2 = 1.25 × 1016α**
In the formula (102-1): N12-EL2 concentration, cm3
-EL2 absorption coefficient, cm-1.
α Calculate by formula (102-2):
A, - A2
In the formula: L-sample thickness, cm;
A, and Az——the absorbance values corresponding to 1.0972um and 2.000μm in the spectrum. 5.2 Calculation of EL.2 concentration of typical semi-insulating sample 5.2.1 The known sample thickness (the width of the narrow strip sample after cleavage) is 0.386 cm. 5.2.2 From Figure 102-1, A, and A, are 0.487 and 0.293, respectively. 5,2.3α is calculated by the following formula:
5.2.4 The sample EL2 concentration is:
0.487-0.293 ×1n10
=1.16(cm-1)
-(102 -1)
-(102 - 2)
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6 Report
S.I20635-97
NeL2 = 1.25 ×1016 ×1. 16
= 1.45×1016(cm -3)
The measurement report should include the following contents:
Test date:
Operator and test unit;
Sample source and number:
Graphic sample cleavage and measurement position;
Absorption coefficient and EL2 concentration;
f, test instrument model, selected parameters and measurement aperture. 7 Precision
The relative standard deviation of this method is 10%.
8 Notes
Research shows that the near-infrared absorption band of gallium arsenide is completely caused by EL.2 photoionization. Therefore, the infrared absorption coefficient () at a wavelength of η can be expressed as:
-()= Net2lf,b,(a)+(1 - f.)Br(A)] .·(102 -3
Where N2 is the EL2 concentration, f, is the electron occupancy rate, (a) and (a) are the electron and hole photoionization cross sections of EI2 at the wavelength respectively. For N-type gallium arsenide, the Fermi level is above the FI2 energy level, and most of EI2 is occupied by electrons, that is, 1, so the above formula can be simplified to:
r(a)=NeL20,(a).
(102- 4)
Therefore, measuring α) and N12 can obtain the calibration factor (α) for the conversion between NLz and α(α). This method uses Martin n(1.0972μm)=(1.25 ×1016cm-2)-1. The premise of using this calibration factor is: (1)/n =1; (2) α(λ) is completely caused by E1.2 photoionization. According to the analysis results, the fn of most N-type semi-insulating GaAs is in the range of 0.78~0.98: at 1.0972μm, the EL2 electron and hole photoionization cross sections are different, (1.0972μm)=3, (1.0972un), so n is small, and the simplification of formula (102-3) to formula (102-4) is not valid. As the electron occupancy rate decreases, the reliability of this method decreases.
Method 103
Micro-area infrared measurement of chromium concentration in semi-insulating gallium arsenide wafer 1 Method Summary
The absorption band caused by the transition from positive trivalent chromium to positive divalent chromium in chromium-doped semi-insulating gallium arsenide has a corresponding relationship between the absorption coefficient and the chromium concentration. It is measured that 1,The absorption coefficient at 350um is calculated by the empirical formula for the chromium concentration. This standard is applicable to the determination of chromium concentration in semi-insulating arsenide grown by the non-chromium-doped horizontal method, and is not applicable to samples with a chromium concentration greater than 1.5×1017cm-3.
2 Measuring instruments
SJ20635-97
2.1 The spectrophotometer can scan in the range of 0.8 to 2.5μm and the zero line absorbance fluctuation is no more than ±0.002. 2.2 Sample holder, with adjustable function, the aperture size is (0.3~0.5)mm×6mme2.3 Micrometer, the accuracy is better than 0.01mm
3 Sample preparation
3.1 The sample is cut from a single crystal ingot with a thickness of 0.4~2.0mm. 3.2 Use the cleavage method to cleave the sample into a narrow strip in parallel. The width of the narrow strip is the required thickness of the sample, which is 2 to 4 mm and the length is greater than 6 mm (see Figure 101-1 in Method 101). The cleavage surface should be a mirror surface and meet the measurement requirements. 4 Test Procedure
4.1 Place an empty adjustable sample holder in the sample light path so that the energy of the light beam passing through the sample holder is not less than 15% of the energy without an aperture.
4.2 Perform zero line calibration by scanning using the absorption method and carefully adjust the instrument so that the zero line absorbance fluctuation in the range of 0.82.5mml is no more than 0.002
4.3 Place the cleaved narrow strip sample in the adjustable sample holder and place it in the sample light path so that the light beam is aligned with the required measurement position. The measurement light path is shown in Figure 101-2 in Method 101. 4.4 The sample absorption spectrum is recorded in the wavelength range of 0.8 to 2.5 mm to obtain the absorbance A-wavelength^ curve. The absorption spectrum of a typical semi-insulating gallium sample is shown in Figure 103-1. 1.5
Sample limit.214cm
1.5001.8002.0002.20m
Wavelength ( )
Range 103-1 Absorption spectrum of a typical semi-insulating gallium sample 5 Result calculation
5.1 According to Figure 103-1, the chromium concentration Nr is calculated by formula (103-1) = (2.6a-0.46)×1016,
Where: Ne
chromium concentration, cm\3,
-(103 - 1)
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-chromium absorption coefficient, cm-1.
α is calculated by formula (103~2):
Where: L-sample thickness, cm:
SJ20635-97
A and A,——the absorbance values corresponding to 1.350gm and 2.0um in the spectrum. 5.2 Calculation of chromium concentration of typical semi-insulating gallium sample. 5.2.1 The known sample thickness (the width of the narrow strip sample after cleavage) is 0.204cm. 5.2.2 As shown in Figure 103-1, A1 and A2 are 0.608 and 0.297 respectively. 5.,2.3 α is calculated by the following formula:
5.2.4 The chromium concentration of the sample is:
6 Report
α= 0-608=0.297 × 1n10
=3.51(cm )
Nc. =(2.60 ×3.51 - 0.46) × 1016=8.66x 10l°(cm-3)
The measurement report should include the following contents:
a. Test date;
b. Operator and testing unit;
c. Try to select the source and number;
Figure sample cleavage and measurement position;
Absorption coefficient and chromium concentration;
f. Test instrument model, selection parameters and measurement light aperture. 7 Precision
This method has a 10% deviation from the standard.
8 Notes
(103 - 2)
8.1 This standard is not applicable to chromium-doped semi-insulating gallium arsenide single crystals grown by the LEC method, because for the gallium arsenide single crystal process grown by the LEC method, boron trioxide capping agent is used, so there is a problem of contamination by poor boron and oxygen. The boron and oxygen complexes formed by these contaminations will affect the accurate determination of the absorption coefficient. Therefore, this standard is only applicable to chromium-doped semi-insulating gallium arsenide single products grown by the horizontal method.
8.2 The saturated solubility of chromium in gallium arsenide is about 1.5×1017cm\3. When the chromium concentration is greater than this value, chromium precipitation will occur. The chromium precipitated on the surface is in a different state from the dissolved chromium (Cr*3), and its contribution to the absorption at 1.35um is also different. When the chromium concentration in gallium arsenide exceeds the saturated solubility, it will not be accurately measured. Therefore, when this standard is used to determine the chromium concentration, the upper limit is set to 1.5×101°cm-3
1 Method Summary
SI20635-97
Method 104
Micro-area secondary ion mass spectrometry test of silicon concentration in semi-insulating gallium arsenide wafers. The positive or negative secondary ions generated by the ionization are generated by the interaction between the high-energy ions and the solid, causing the matrix atoms and molecules to be emitted in two states, neutral and charged. The generated charged particles (secondary ions) can be detected by highly sensitive mass spectrometry technology. The silicon secondary ion signal in semi-insulating gallium arsenide has a corresponding relationship with the silicon concentration. The silicon concentration can be calculated from the measured silicon secondary ion signal and calibrated according to the experimental standard. This standard is applicable to the determination of silicon concentration in semi-insulating gallium arsenide grown by the chromium-doped horizontal method. In order to obtain a better detection limit, the chromium in the semi-insulating gallium arsenide material is generally analyzed by using a saturated primary ion source and detecting negative secondary ion mass spectrometry. In this way, the minimum detection limit of silicon in the semi-insulating gallium arsenide is 5.0×1014at.cm-3. 2 Measuring instrument
A secondary ion mass spectrometer with a saturated ion source is used, and its mass resolution should be able to distinguish silicon ions from interfering molecular ions. 3 Sample preparation
3.1 Measurement sample
3.1.1 The sample is cut from a single ingot with a thickness of 0.5~2.0mm3.1.2 The sample is polished, and then the sample is divided into small square pieces of 5mm×5mm. 3.1.3 After ultrasonic cleaning with analytical pure acetone or anhydrous ethanol, it is cooled and dried for use. 3.2 Standard reference sample
GaAs sample with known energy and dose injected into the sample. 4 Test procedure
4.1 Color inspection
Before the experiment, check the secondary ion mass spectrometer and ensure that each part of it is free of abnormality. 4.2 Pre-injection
Put the test sample and the standard reference sample on the sample holder at the same time and put them into the transition chamber. Evacuate the sample to make it close to the vacuum required by the sample chamber, then open the injection chamber valve, push the sample holder into the sample chamber, and finally close the access door. 4.3 Instrument adjustment
Adjust according to the instrument manual. Generally, the primary ion optical system is adjusted first, and then the secondary ion optical path is adjusted. Keep the instrument in the best working state and ensure the stability of the primary beam. 4.4 Experimental parameter setting
Use the same experimental conditions and parameters to measure the test sample and the standard reference sample, and the sampling area is 5um×5μm to 500μm×500μm.
4.4.1 Determine the relative sensitivity factor (RSF) with the standard reference sample as reference. 4.4.2 The test sample should be measured three times, that is, measure three points on the test sample, and store the results in the computer. 5 Result calculation
HKAONTKAca-214cm
1.5001.8002.0002.20m
wave ( )
around 103-1 Absorption spectrum of typical semi-insulating gallium sample 5 Result calculation
5.1 According to Figure 103-1, the chromium concentration Nr is calculated by formula (103-1) = (2.6a-0.46)×1016,
where: Ne
chromium concentration, cm\3,
-(103 - 1)
KAONKAca-
-chromium absorption coefficient, cm-1.
α is calculated by formula (103~2):
Where: L-sample thickness, cm: bzxz.net
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A and A,——the absorbance values corresponding to 1.350gm and 2.0um in the spectrum. 5.2 Calculation of chromium concentration of typical semi-insulating gallium sample. 5.2.1 The known sample thickness (the width of the narrow strip sample after cleavage) is 0.204cm. 5.2.2 As shown in Figure 103-1, A1 and A2 are 0.608 and 0.297 respectively. 5.,2.3 α is calculated by the following formula:
5.2.4 The chromium concentration of the sample is:
6 Report
α= 0-608=0.297 × 1n10
=3.51(cm )
Nc. =(2.60 ×3.51 - 0.46) × 1016=8.66x 10l°(cm-3)
The measurement report should include the following contents:
a. Test date;
b. Operator and testing unit;
c. Try to select the source and number;
Figure sample cleavage and measurement position;
Absorption coefficient and chromium concentration;
f. Test instrument model, selection parameters and measurement light aperture. 7 Precision
This method has a 10% deviation from the standard.
8 Notes
(103 - 2)
8.1 This standard is not applicable to chromium-doped semi-insulating gallium arsenide single crystals grown by the LEC method, because for the gallium arsenide single crystal process grown by the LEC method, boron trioxide capping agent is used, so there is a problem of contamination by poor boron and oxygen. The boron and oxygen complexes formed by these contaminations will affect the accurate determination of the absorption coefficient. Therefore, this standard is only applicable to chromium-doped semi-insulating gallium arsenide single products grown by the horizontal method.
8.2 The saturated solubility of chromium in gallium arsenide is about 1.5×1017cm\3. When the chromium concentration is greater than this value, chromium precipitation will occur. The chromium precipitated on the surface is in a different state from the dissolved chromium (Cr*3), and its contribution to the absorption at 1.35um is also different. When the chromium concentration in gallium arsenide exceeds the saturated solubility, it will not be accurately measured. Therefore, when this standard is used to determine the chromium concentration, the upper limit is set to 1.5×101°cm-3
1 Method Summary
SI20635-97
Method 104
Micro-area secondary ion mass spectrometry test of silicon concentration in semi-insulating gallium arsenide wafers. The positive or negative secondary ions generated by the ionization are generated by the interaction between the high-energy ions and the solid, causing the matrix atoms and molecules to be emitted in two states, neutral and charged. The generated charged particles (secondary ions) can be detected by highly sensitive mass spectrometry technology. The silicon secondary ion signal in semi-insulating gallium arsenide has a corresponding relationship with the silicon concentration. The silicon concentration can be calculated from the measured silicon secondary ion signal and calibrated according to the experimental standard. This standard is applicable to the determination of silicon concentration in semi-insulating gallium arsenide grown by the chromium-doped horizontal method. In order to obtain a better detection limit, the chromium in the semi-insulating gallium arsenide material is generally analyzed by using a saturated primary ion source and detecting negative secondary ion mass spectrometry. In this way, the minimum detection limit of silicon in the semi-insulating gallium arsenide is 5.0×1014at.cm-3. 2 Measuring instrument
A secondary ion mass spectrometer with a saturated ion source is used, and its mass resolution should be able to distinguish silicon ions from interfering molecular ions. 3 Sample preparation
3.1 Measurement sample
3.1.1 The sample is cut from a single ingot with a thickness of 0.5~2.0mm3.1.2 The sample is polished, and then the sample is divided into small square pieces of 5mm×5mm. 3.1.3 After ultrasonic cleaning with analytical pure acetone or anhydrous ethanol, it is cooled and dried for use. 3.2 Standard reference sample
GaAs sample with known energy and dose injected into the sample. 4 Test procedure
4.1 Color inspection
Before the experiment, check the secondary ion mass spectrometer and ensure that each part of it is free of abnormality. 4.2 Pre-injection
Put the test sample and the standard reference sample on the sample holder at the same time and put them into the transition chamber. Evacuate the sample to make it close to the vacuum required by the sample chamber, then open the injection chamber valve, push the sample holder into the sample chamber, and finally close the access door. 4.3 Instrument adjustment
Adjust according to the instrument manual. Generally, the primary ion optical system is adjusted first, and then the secondary ion optical path is adjusted. Keep the instrument in the best working state and ensure the stability of the primary beam. 4.4 Experimental parameter setting
Use the same experimental conditions and parameters to measure the test sample and the standard reference sample, and the sampling area is 5um×5μm to 500μm×500μm.
4.4.1 Determine the relative sensitivity factor (RSF) with the standard reference sample as reference. 4.4.2 The test sample should be measured three times, that is, measure three points on the test sample, and store the results in the computer. 5 Result calculation
HKAONTKAca-214cm
1.5001.8002.0002.20m
wave ( )
around 103-1 Absorption spectrum of typical semi-insulating gallium sample 5 Result calculation
5.1 According to Figure 103-1, the chromium concentration Nr is calculated by formula (103-1) = (2.6a-0.46)×1016,
where: Ne
chromium concentration, cm\3,
-(103 - 1)
KAONKAca-
-chromium absorption coefficient, cm-1.
α is calculated by formula (103~2):
Where: L-sample thickness, cm:
SJ20635-97
A and A,——the absorbance values corresponding to 1.350gm and 2.0um in the spectrum. 5.2 Calculation of chromium concentration of typical semi-insulating gallium sample. 5.2.1 The known sample thickness (the width of the narrow strip sample after cleavage) is 0.204cm. 5.2.2 As shown in Figure 103-1, A1 and A2 are 0.608 and 0.297 respectively. 5.,2.3 α is calculated by the following formula:
5.2.4 The chromium concentration of the sample is:
6 Report
α= 0-608=0.297 × 1n10
=3.51(cm )
Nc. =(2.60 ×3.51 - 0.46) × 1016=8.66x 10l°(cm-3)
The measurement report should include the following contents:
a. Test date;
b. Operator and testing unit;
c. Try to select the source and number;
Figure sample cleavage and measurement position;
Absorption coefficient and chromium concentration;
f. Test instrument model, selection parameters and measurement light aperture. 7 Precision
This method has a 10% deviation from the standard.
8 Notes
(103 - 2)
8.1 This standard is not applicable to chromium-doped semi-insulating gallium arsenide single crystals grown by the LEC method, because for the gallium arsenide single crystal process grown by the LEC method, boron trioxide capping agent is used, so there is a problem of contamination by poor boron and oxygen. The boron and oxygen complexes formed by these contaminations will affect the accurate determination of the absorption coefficient. Therefore, this standard is only applicable to chromium-doped semi-insulating gallium arsenide single products grown by the horizontal method.
8.2 The saturated solubility of chromium in gallium arsenide is about 1.5×1017cm\3. When the chromium concentration is greater than this value, chromium precipitation will occur. The chromium precipitated on the surface is in a different state from the dissolved chromium (Cr*3), and its contribution to the absorption at 1.35um is also different. When the chromium concentration in gallium arsenide exceeds the saturated solubility, it will not be accurately measured. Therefore, when this standard is used to determine the chromium concentration, the upper limit is set to 1.5×101°cm-3
1 Method Summary
SI20635-97
Method 104
Micro-area secondary ion mass spectrometry test of silicon concentration in semi-insulating gallium arsenide wafers. The positive or negative secondary ions generated by the ionization are generated by the interaction between the high-energy ions and the solid, causing the matrix atoms and molecules to be emitted in two states, neutral and charged. The generated charged particles (secondary ions) can be detected by highly sensitive mass spectrometry technology. The silicon secondary ion signal in semi-insulating gallium arsenide has a corresponding relationship with the silicon concentration. The silicon concentration can be calculated from the measured silicon secondary ion signal and calibrated according to the experimental standard. This standard is applicable to the determination of silicon concentration in semi-insulating gallium arsenide grown by the chromium-doped horizontal method. In order to obtain a better detection limit, the chromium in the semi-insulating gallium arsenide material is generally analyzed by using a saturated primary ion source and detecting negative secondary ion mass spectrometry. In this way, the minimum detection limit of silicon in the semi-insulating gallium arsenide is 5.0×1014at.cm-3. 2 Measuring instrument
A secondary ion mass spectrometer with a saturated ion source is used, and its mass resolution should be able to distinguish silicon ions from interfering molecular ions. 3 Sample preparation
3.1 Measurement sample
3.1.1 The sample is cut from a single ingot with a thickness of 0.5~2.0mm3.1.2 The sample is polished, and then the sample is divided into small square pieces of 5mm×5mm. 3.1.3 After ultrasonic cleaning with analytical pure acetone or anhydrous ethanol, it is cooled and dried for use. 3.2 Standard reference sample
GaAs sample with known energy and dose injected into the sample. 4 Test procedure
4.1 Color inspection
Before the experiment, check the secondary ion mass spectrometer and ensure that each part of it is free of abnormality. 4.2 Pre-injection
Put the test sample and the standard reference sample on the sample holder at the same time and put them into the transition chamber. Evacuate the sample to make it close to the vacuum required by the sample chamber, then open the injection chamber valve, push the sample holder into the sample chamber, and finally close the access door. 4.3 Instrument adjustment
Adjust according to the instrument manual. Generally, the primary ion optical system is adjusted first, and then the secondary ion optical path is adjusted. Keep the instrument in the best working state and ensure the stability of the primary beam. 4.4 Experimental parameter setting
Use the same experimental conditions and parameters to measure the test sample and the standard reference sample, and the sampling area is 5um×5μm to 500μm×500μm.
4.4.1 Determine the relative sensitivity factor (RSF) with the standard reference sample as reference. 4.4.2 The test sample should be measured three times, that is, measure three points on the test sample, and store the results in the computer. 5 Result calculation
HKAONTKAca-5×101°cm-3
1Method Summary
SI20635-97
Method 104
Micro-area secondary ion mass spectrometry test of silicon concentration in semi-insulating gallium arsenide wafers The positive or negative secondary ions generated by the shallow ion impact the sample surface, that is, the interaction between the high-energy ions and the solid, causing the matrix atoms and molecules to be emitted in two states, neutral and charged. The generated charged particles (secondary ions) can be detected by highly sensitive mass spectrometry technology. The silicon secondary ion signal in semi-insulating gallium arsenide has a corresponding relationship with the silicon concentration. The silicon concentration can be calculated by calibrating the measured silicon secondary ion signal with the experimental standard sample. This standard is applicable to the determination of silicon concentration in semi-insulating gallium arsenide grown by chromium-doped horizontal method. In order to obtain a better detection limit, the chromium in semi-insulating gallium arsenide materials is generally analyzed by using a saturated primary ion source and detecting negative secondary ion mass spectrometry. In this way, the minimum detection limit of silicon in semi-insulating gallium arsenide is 5.0×1014at.cm-3. 2 Measuring instrument
A secondary ion mass spectrometer with a saturated ion source is used, and its mass resolution should be able to distinguish silicon ions from interfering molecular ions. 3 Sample preparation
3.1 Measurement sample
3.1.1 The sample is cut from a single ingot with a thickness of 0.5~2.0mm3.1.2 The sample is polished and then divided into small square pieces of 5mm×5mm. 3.1.3 After ultrasonic cleaning with analytical pure acetone or anhydrous ethanol, it is cooled and dried for use. 3.2 Standard reference sample
GaAs sample with known silicon injection energy and dose. 4 Test Procedure
4.1 Color Check
Before the experiment, check the secondary ion mass spectrometer and ensure that each part of it is free of abnormalities. 4.2 Pre-injection
Put the test sample and the standard reference sample on the sample rack at the same time and put them into the transition chamber. Evacuate the sample to make it close to the vacuum required by the sample chamber, then open the injection chamber valve, push the sample rack into the sample chamber, and finally close the access door. 4.3 Instrument Adjustment
Adjust according to the instrument manual. Generally, the primary ion optical system is adjusted first, and then the secondary ion optical path is adjusted. Keep the instrument in the best working state and ensure the stability of the primary beam. 4.4 Experimental Parameter Setting
Use the same experimental conditions and parameters to measure the test sample and the standard reference sample, and the sampling area is 5um×5μm to 500μm×500μm.
4.4.1 Determine the relative sensitivity factor (RSF) with the standard reference sample as the reference. 4.4.2 The sample to be tested should be measured three times, that is, three points should be measured on the sample to be tested, and the results should be stored in the computer. 5 Result calculation
HKAONTKAca-5×101°cm-3
1Method Summary
SI20635-97
Method 104
Micro-area secondary ion mass spectrometry test of silicon concentration in semi-insulating gallium arsenide wafers The positive or negative secondary ions generated by the shallow ion impact the sample surface, that is, the interaction between the high-energy ions and the solid, causing the matrix atoms and molecules to be emitted in two states, neutral and charged. The generated charged particles (secondary ions) can be detected by highly sensitive mass spectrometry technology. The silicon secondary ion signal in semi-insulating gallium arsenide has a corresponding relationship with the silicon concentration. The silicon concentration can be calculated by calibrating the measured silicon secondary ion signal with the experimental standard sample. This standard is applicable to the determination of silicon concentration in semi-insulating gallium arsenide grown by chromium-doped horizontal method. In order to obtain a better detection limit, the chromium in semi-insulating gallium arsenide materials is generally analyzed by using a saturated primary ion source and detecting negative secondary ion mass spectrometry. In this way, the minimum detection limit of silicon in semi-insulating gallium arsenide is 5.0×1014at.cm-3. 2 Measuring instrument
A secondary ion mass spectrometer with a saturated ion source is used, and its mass resolution should be able to distinguish silicon ions from interfering molecular ions. 3 Sample preparation
3.1 Measurement sample
3.1.1 The sample is cut from a single ingot with a thickness of 0.5~2.0mm3.1.2 The sample is polished and then divided into small square pieces of 5mm×5mm. 3.1.3 After ultrasonic cleaning with analytical pure acetone or anhydrous ethanol, it is cooled and dried for use. 3.2 Standard reference sample
GaAs sample with known silicon injection energy and dose. 4 Test Procedure
4.1 Color Check
Before the experiment, check the secondary ion mass spectrometer and ensure that each part of it is free of abnormalities. 4.2 Pre-injection
Put the test sample and the standard reference sample on the sample rack at the same time and put them into the transition chamber. Evacuate the sample to make it close to the vacuum required by the sample chamber, then open the injection chamber valve, push the sample rack into the sample chamber, and finally close the access door. 4.3 Instrument Adjustment
Adjust according to the instrument manual. Generally, the primary ion optical system is adjusted first, and then the secondary ion optical path is adjusted. Keep the instrument in the best working state and ensure the stability of the primary beam. 4.4 Experimental Parameter Setting
Use the same experimental conditions and parameters to measure the test sample and the standard reference sample, and the sampling area is 5um×5μm to 500μm×500μm.
4.4.1 Determine the relative sensitivity factor (RSF) with the standard reference sample as the reference. 4.4.2 The sample to be tested should be measured three times, that is, three points should be measured on the sample to be tested, and the results should be stored in the computer. 5 Result calculation
HKAONTKAca-
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