This standard specifies the infrared reflection measurement method for the thickness of lightly doped silicon epitaxial layers on heavily doped substrates. This standard is applicable to the measurement of the thickness of silicon epitaxial layers with a substrate room temperature resistivity of less than 0.02Ω·cm and an epitaxial layer room temperature resistivity greater than 0.1Ω·cm and an epitaxial layer thickness greater than 2μm. GB/T 14847-1993 Infrared reflection measurement method for the thickness of lightly doped silicon epitaxial layers on heavily doped substrates GB/T14847-1993 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Test method for thickness of lightly dopedsilicon epitaxial layers on heavily dopedsilicon substrates by infrared reflectance1 Subject content and scope of application
This standard specifies the infrared reflectance measurement method for the thickness of lightly dopedsilicon epitaxial layers on heavily dopedsilicon substrates. GB/T 14847--93
This standard is applicable to the measurement of the thickness of silicon epitaxial layers with a substrate room temperature resistivity of less than 0.02α·cm and an epitaxial layer room temperature resistivity of greater than 0.10·cm and an epitaxial layer thickness greater than 2um. 2 Reference Standards
GB6379 Precision of the test method Repeatability and reproducibility of the standard test method are determined by inter-laboratory tests 3 Principle of the method
The difference in optical constants between the substrate and the epitaxial layer leads to continuous maximum and minimum optical interference in the reflection spectrum of the sample. The thickness of the epitaxial layer is calculated based on the extreme wavelength, the optical constants of the epitaxial layer and the substrate, and the incident angle. 4 Measuring instruments
4.1 Infrared spectrometer
4.1.1 Fourier transform infrared spectrometer or double-beam infrared spectrophotometer. 4.1.2 Wavelength range 2~50μm, the commonly used wavelength range of this method is 6~25μm. 4.1.3 Wavelength repeatability is not greater than 0.05μm. 4.1.4 Wavelength accuracy is ±0.05μm.
4.2 Instrument accessories
4.2.1 Reflection accessories matching the instrument, the incident angle is not greater than 30°. 4.2.2 The mask is made of non-reflective material, and the light-transmitting aperture is not larger than 8mm. 5 Sample requirements
The conductivity type of the substrate and epitaxial layer and the substrate resistivity should be known. 5.2 The sample should have a good optical surface to ensure high reflectivity, and should not have a large area of ​​passivation layer. 5.3 Samples deposited by normal process do not require special treatment. 6 Measurement Procedure
6.1 Spectrometer Calibration
Approved by the State Administration of Technical Supervision on December 24, 1993 544
Implemented on September 1, 1994
GB/T 14847--93
6.1.1 Use a polystyrene film with a thickness of 300~~500μm as a standard sample, and use the 1601.6cm- or 648.9cm-peak of the standard sample as the measurement reference peak. The instrument wavelength repeatability and accuracy determined by GB6379 should meet the requirements of 4.1.3 and 4.1.4 respectively. 6.1.2 Place the reflection accessory in the light path and measure the 100% line. Its peak-to-valley value should be less than 8%. 6.2 Selection of Measurement Conditions
6.2.1 For a grating infrared spectrophotometer, refer to the following steps to select the optimal scanning speed. 6.2.1.1 Select a sample with an epitaxial layer thickness close to 10 μm and record the minimum wavelength greater than 10 μm at the slowest scanning speed of the instrument. 6.2.1.2 Increase the scanning speed step by step and record the corresponding minimum wavelength each time. 6.2.1.3 The difference between the extreme wavelength recorded by the last selected scanning speed and the slowest scanning speed should be within ±0.1 μm. 6.2.2 The resolution used for the Fourier transform infrared spectrometer should be not less than 4 cm-. 6.3 Measurement
6.3.1 Place the sample on the mask hole of the reflection accessory and align the measurement position with the light beam. 6. 3. 2
Obtain a reflection spectrum similar to Figure 1. If the ratio of the peak-to-valley amplitude to the noise amplitude is less than 5, the epitaxial layer thickness cannot be calculated. 40
Wave number (cm-\)
Figure 1 Infrared reflection spectrum of a typical n/nt-Si sample 400
6.3.3 Draw a horizontal line and the reflection spectrum intersecting at two points below the maximum value or above the minimum value at 3% of the full scale. The average value of the corresponding wavelengths of the two points is the extreme wavelength.
7 Calculation of measurement results
7.1 Method 1
7.1.1 Determine the order of each maximum and minimum value by formula (1): P,=
Where: P-
A, A,
-the order corresponding to the extreme value at λ,
extreme wavelength (>>A), μm
z1/2 element-22/2 element in A2
-（1)
m--the order difference between λ and λ;
GB/T 14847-93
21, 22--the phase shift corresponding to λ and λ respectively (see Table 1 and Table 2). 7.1.1.1 If λ2 is a maximum value, the calculated value of P. is an integer, otherwise it is a half integer. The order corresponding to other extreme values ​​can be determined according to the principle of decreasing order with increasing wavelength as shown in Figure 1.
Table 1n/nt-Si phase shift (Φ2n/2 element)
Substrate resistivity (n·cm)bzxz.net
0. 001 0. 002 0. 003 0. 004 0. 005 0. 006 0. 007 0. 008 0. 009 0. 010 0. 012 0. 014 0. 016 0. 018 0. 0200. 033 0. 029 0. 028 0. 027 0. 027 0. 026 0. 025 0. 024 0. 023 0. 022 0. 020 0. 019 0. 017 0. 016 0. 0160. 061 0. 050 0. 047 0. 046 0. 045 0. 043 0. 041 0. 039 0. 038 0. 036 0. 034 0. 031 0. 029 0. 027 0. 0250. 105 0. 072 0. 064 0. 062 0. 060 0. 057 0. 055 0. 052 0. 050 0. 048 0. 044 0. 042 0. 039 0. 036 0. 0330.182 0. 099 0. 083 0. 078 0. 075 0. 071 0. 067 0. 064 0. 061 0. 059 0. 054 0. 051 0. 047 0. 043 0. 0400. 247 0. 137 0. 105 0. 095 0. 090 0. 084 0. 079 0. 075 0. 071 0. 069 0. 063 0. 059 0. 055 0. 051 0. 0470.289 0.1830.132 0.115 0.106 0. 098 0.091 0. 084 0.081 0.078 0.072 0.067 0. 062 0.057 0.0530.318 0.225 0.1640.137 0.124 0.113 0.104 0.097 0.092 0. 0870.080 0. 074 0.069 0. 064 0. 0590. 339 0. 258 0.197 0.163 0.144 0.129 0.117 0.109 0.102 0. 097 0. 088 0. 082 0. 075 0. 070 0. 0650. 335 0. 283 0. 226 0. 189 0.166 0.146 0. 131 0. 121 0. 113 0. 107 0. 096 0. 089 0. 082 0. 076 0. 0700. 368 0. 303 0. 251 0. 214 0.188 0. 165 0. 147 0. 134 0. 124 0. 117 0.105 0. 096 0. 088 0. 081 0. 0750. 378 0. 319 0. 272 ​​0. 236 0. 209 0.183 0.163 0.148 0.136 0. 127 0. 113 0.104 0. 095 0. 087 0. 0810. 387 0. 333 0. 289 0. 255 0. 229 0. 202 0.179 0.162 0.148 0.138 0.122 0.111 0.101 0. 093 0. 0860. 397 0.344 0. 303 0. 272 ​​0. 246 0. 219 0.196 0.177 0.161 0. 150 0.131 0.119 0. 108 0. 099 0. 0910.401 0.353 0.3160.286 0.261 0.235 0.211 0.191 0.175 0.1610.141 0.127 0.1150.1040.0960.406 0.362 0.326 0.298 0.2750.250 0.2260.206 0.188 0.173 0.150 0.135 0.1210.110 0.1010. 411 0. 369 0. 336 0. 309 0. 287 0. 263 0.240 0. 219 0. 201 0. 185 0. 160 0.143 0. 128 0. 116 0. 1060. 4150.375 0. 344 0. 319 0.297 0.274 0.252 0.232 0. 2130.197 0.170 0.151 0.135 0.122 0.1120. 419 0. 381 0. 351 0. 327 0. 307 0. 285 0. 263 0. 243 0. 225 0. 209 0. 180 0. 160 0. 143 0. 129 0. 1170. 422 0.386 0.357 0.335 0.315 0.294 0.273 0.254 0.236 0.220 0.191 0.167 0.150 0.135 0.1230. 425 0. 391 0. 363 0. 341 0. 323 0. 302 0. 285 0. 264 0. 246 0. 230 0. 200 0. 178 0. 158 0. 141 0. 128 Table 2P/P+-Si phase shift (Φ2m/2 yuan)
Substrate resistivity (α-cm)
0. 001 0. 002 0. 003 0 . 004 0. 005 0. 006 0. 007 0. 008 0. 009 0. 010 0. 012 0. 014 0. 016 0. 018 0. 020 0. 036 0. 035 0. 034 0. 034 0. 033 0.033 0.033 0.032 0.031 0.030 0.028 0.027 0. 025 0.024 0. 0240. 067 0. 057 0. 055 0. 055 0. 055 0. 055 0. 054 0. 052 0. 050 0. 049 0. 045 0. 043 0. 040 0. 038 0. 0370. 119 0. 080 0. 076 0. 074 0. 073 0. 072 0. 071 0. 068 0. 066 0. 064 0. 059 0. 056 0.053 0. 050 0. 0490. 200 0. 114 0. 099 0. 094 0. 091 0. 089 0, 086 0. 083 0. 080 0. 077 0. 072 0. 067 0. 064 0. 060 0. 0590.261 0.158 0.127 0.115 0.110 0.105 0.102 0.097 0.093 0.089 0.083 0. 078 0. 073 0. 070 0.0680. 300 0. 205 0. 160 0. 140 0. 130 0. 123 0. 117 0. 111 0. 106 0. 101 0. 094 0. 088 0. 083 0. 078 0. 076 Wavelength
GB/T 14847—93
Continued Table 2
Substrate resistivity (2-cm)| |tt||0. 001 0. 002 0. 003 0. 004 0. 005 0. 006 0. 007 0. 008 0. 009 0. 010 0. 012 0. 014 0. 016 0. 018 0. 0200.327 0.244 0.194 0.167 0.152 0.141 0.133 0.126 0.119 0.113 0.104 0. 097 0.091 0. 087 0. 0840. 346 0. 274 0. 226 0. 195 0.175 0.161 0. 151 0. 141 0. 132 0. 126 0.115 0. 106 0. 100 0. 094 0. 0910, 361 0.297 0.253 0.211 0.198 0.182 0.168 0.157 0,146 0.138 0.125 0.116 0.108 0. 102 0. 0990. 373 0. 315 0. 274 0. 243 0. 220 0.202 0. 186 0. 173 0. 160 0. 151 0. 136 0. 125 0. 117 0. 110 0. 1060. 383 0. 330 0. 292 0. 263 0. 240 0. 220 0. 204 0. 188 0. 175 0. 164 0. 147 0. 134 0. 125 0. 117 0. 1130.3910.3420.3070.2970.2570.2380.2200.2040.1890.1770.1580.1440.1330.1250.1200. 398 0. 352 0. 320 0. 294 0. 272 ​​0. 253 0.236 0. 219 0. 203 0. 190 0. 169 0. 153 0. 142 0.132 0. 1270. 404 0. 361 0. 331 0. 306 0. 285 0. 267 0. 250 0. 233 0. 217 0. 203 0. 180 0. 163 0. 150 0. 140 0. 1340. 409 0. 369 0. 340 0. 316 0. 297 0. 279 0. 262 0. 245 0. 229 0. 215 0. 191 0. 173 0.159 0. 148 0. 1410.414 0.376 0.348 0.326 0.307 0.290 0.2730.257 0.241 0.227 0.202 0.182 0.1670.155 0.1480. 418 0. 381 0. 355 0. 334 0. 316 0. 299 0. 284 0. 268 0. 252 0. 238 0. 213 0. 192 0. 176 0. 163 0. 1550,421 0.387 0.362 0.341 0.324 0.308 0.293 0.277 0,262 0.248 0.223 0.201 0.185 0.171 0.1620. 425 0. 391 0. 368 0. 348 0. 331 0, 316 0. 301 0. 286 0. 271 0. 258 0. 232 0. 211 0. 193 0. 178 0. 1690. 428 0. 396 0. 373 0. 354 0. 338 0. 323 0. 309 0. 294 0.280 0. 266 0.241 0. 219 0. 201 0. 186 0. 176 The thickness of the epitaxial layer is calculated by formula (2):
T = (P. - 0. 5 + pa/2n) 2(n -sin*0) Wherein: T, the calculated thickness corresponding to the nth extreme wavelength, um; P.-the order corresponding to the nth extreme wavelength; n-the nth extreme wavelength, μm
n-the refractive index of the silicon epitaxial layer (nl=3.42); 0-the incident angle of the reflection attachment,);
The meanings of other symbols are the same as those in formula (1).
7.1.3 The reflectance spectrum data of the typical n/n+-Si sample shown in Figure 1 are calculated as follows: (2)
7.1.3.1 Take ^ and λ2 as 15.66μum and 10.30±m respectively, m=3.5, substrate resistivity eg-=0.0052·cm, θ=30°. 7.1.3.2 From λ and λ and θ and Table 1, we know that 2/2 π=0.141, 22/2 π=0.092, and calculate P2=10.5, 72=15.36um. 7.1.3.3 Similarly, the relevant data corresponding to other extreme values ​​can be obtained, as shown in Table 3. 7.1.4 This calculation method should be used during arbitration. Table 3 Calculation results of epitaxial layer thickness of typical n/n+-Si sample
Extreme value number
g2n/2 element
Extreme value number
Average thickness, um
7.2 Method 2 (empirical calculation method)
Aa, μum
GB/T 14847--93
Continued Table 3
pzm/2 element
Th-μm
7.2.1 The epitaxial layer thickness can be obtained by calculating the extreme value number of the sample reflection spectrum in the range of 1100～500cm~1. The calculation formula is: T = 1. 20 n
Wherein: T—epitaxial layer thickness, um;
-The extreme value number in the range of 1100～500cm-1. (3)
7.2.2 When the thickness of the epitaxial layer is greater than 20um, the thickness can also be calculated using the extreme value number in the range of 700~500cm-1. The calculation formula is: T= 3.64n
7.2.3 As shown in Figure 2, calculate the extreme value number n according to the following steps: (%)
Wave number (cm)
Figure 2 Schematic diagram of the empirical calculation method
Draw two straight lines AB and CI perpendicular to the wave number axis at 1100cm-1 and 500cm-1 in the reflection spectrum. 7.2.3.1
GB/T14847-93
7.2.3.2 Take the reflectivity R1 and R from the extreme values ​​on both sides closest to AB and CD respectively: R1 = (Rmin1 + Rmax)/2
R2 = (Rmin2 + Rinax2)/2
7.2.3.3 Draw two horizontal lines EF and NM through R1 and R, and intersect AB and CD at O ​​and P respectively. 7.2.3.4 The number of extreme values ​​n is calculated by formula (7): n = K + EO / EF + NP / NM
Where: K is the number of complete extreme values ​​between AB and CD. 7.2.3.5 From K=12, EO/EF=2/7, NP/NM-1/2, we get n=12.79. 7.2.4 Substituting n12.79 into formula (3), we get T15.35μm. 8 Precision
·(5)
8.1 When the thickness of the n-type silicon epitaxial layer is greater than 2um, the precision of multiple laboratory measurements is ±(0.171μm+0.0026T)(3s). This result is obtained by 8 samples measured in 7 laboratories. 8.2 When the thickness of the p-type silicon epitaxial layer is greater than 2μm, the precision of multiple laboratory measurements is ±(0.211μm+0.0015T)(3s). This result is obtained by 9 samples measured in 7 laboratories. 9 Test report
9.1 The test report shall include the following contents:
Standard number:
Measuring instruments used;
Specimen name, source and number;
Conductivity type of substrate and epitaxial layer and substrate resistivity; Diagram of specimen measurement position;
Calculated thickness Th corresponding to each extreme value; Average thickness.
Additional remarks:
This standard was proposed by China Nonferrous Metals Industry Corporation. This standard was drafted by the 46th Institute of the Ministry of Machinery and Electronics and Shanghai No. 2 Smelter. The main drafters of this standard are He Xiukun, Li Guangping, Ye Yuzong, Yan Shiquan, Wang Qin, Zhang Zhigang and Qian Guosheng. 5491 The test report should include the following:
Standard number:
Measurement instrument used;
Sample name, source and number;
Conductivity type of substrate and epitaxial layer and substrate resistivity; Diagram of sample measurement position;
Calculated thickness Th corresponding to each extreme value; Average thickness.
Additional remarks:
This standard was proposed by China Nonferrous Metals Industry Corporation. This standard was drafted by the 46th Institute of the Ministry of Machinery and Electronics and Shanghai No. 2 Smelter. The main drafters of this standard are He Xiukun, Li Guangping, Ye Yuzong, Yan Shiquan, Wang Qin, Zhang Zhigang and Qian Guosheng. 5491 The test report should include the following:
Standard number:
Measurement instrument used;
Sample name, source and number;
Conductivity type of substrate and epitaxial layer and substrate resistivity; Diagram of sample measurement position;
Calculated thickness Th corresponding to each extreme value; Average thickness.
Additional remarks:
This standard was proposed by China Nonferrous Metals Industry Corporation. This standard was drafted by the 46th Institute of the Ministry of Machinery and Electronics and Shanghai No. 2 Smelter. The main drafters of this standard are He Xiukun, Li Guangping, Ye Yuzong, Yan Shiquan, Wang Qin, Zhang Zhigang and Qian Guosheng. 549
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