This standard specifies the inspection method for oxidation-induced defects of silicon polished wafers. This standard is applicable to the detection of crystal defects induced or enhanced in the surface area of ​​silicon polished wafers during the oxidation process of simulated devices. GB/T 4058-1995 Inspection method for oxidation-induced defects of silicon polished wafers GB/T4058-1995 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Test method for detection of oxidatinninduced defects in polished silicon wafers1 Subject content and scope of application
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GB/T 4058—1995
Replaces GB 4058--83
GB 6622
GR 6623
This standard specifies the test method for oxidation-induced defects in polished silicon wafers. This standard is applicable to the detection of body defects induced or enhanced in the surface area of ​​silicon polished wafers during the oxidation process of simulated devices. 2 Reference standards
GB/T1554 Chemical selective etching test method for silicon product integrity YS/T209 Spectrum of native defects of silicon materials
3 Method summary
Simulate the packaging conditions of the device process, use oxidation to decorate or expand the defects in the silicon wafer, or both, then use selective etching solution to display the defects, and observe them by microscopy. 4 Reagents and materials
4.1 Chromium trioxide.
4.2 Hydrofluoric acid (42%), high-grade purity.
4.3 Nitric acid (p1.4 g/ml.), high-grade purity. 4.4 Ammonia (p0.90g/mL) high-grade purity
Hydrochloric acid (ol.18g/mL), high-grade purity.
4.6 Acetic acid (pl.05R/mL). High-grade purity. Hydrogen peroxide (30%), high-grade purity.
4.8 High-purity water, resistivity at 25°C is greater than 10Mo·cm. 4.9 Cleaning solution 1#:
Water: ammonia (4.4): hydrogen peroxide (4.7) - 4: 1: 1 (V/V). 4.10 Cleaning solution 2″:
Water hydrochloric acid (4.5): ammonia peroxide (4.7) = 4: 1: 1 (V/V). 4.11 Chemical polishing solution adopts one of the formulas in Table 1 Approved by the State Administration of Technical Supervision on April 18, 1995 and implemented on December 1, 1995
GB/T 4058—1995
Table 1 Formulas of four commonly used chemical polishing solutions
Nitric acid (4.3)
Aminoacid (4.2)
Acetic acid (4.6)
4.12 Acid solution B: Weigh 75g of chromium trioxide (4.1) in a beaker, add water to dissolve, transfer to a 1000mL volumetric flask, dilute with water to the scale, and mix.
4.13 Schimmel etching solution A:
Chromic acid solution B (4.12): Hydrofluoric acid (4.2) = 112 (V/V) Prepare before use. 4. 14 Schimmel Etching solution B:
Chromic acid solution B (4.12): hydrofluoric acid (4.2) water - 1:2:1.5 (V/V) Prepare before use.
4.15 Abrasive materials, use W20, W10 silicon carbide or aluminum oxide corundum. 5 Equipment and instruments
5.1 Gold microscope: with XY mechanical stage and stage micrometer, magnification not less than 100 times. 5.2 Parallel light source, illumination 00 ~ 150Ix, observation background is matte black. 5.3 Oxidation furnace, meet the requirements of the thermal cycle energy required by Table 2, with a central part of the furnace tube of not less than 30 0mm long constant temperature zone, and maintain the temperature of 1000~|200℃ in the constant temperature zone, and the temperature control error is ±10℃. 5.4 Gas source: can provide sufficient dry oxygen, wet oxygen or water vapor. 5.5 Sample boat: quartz boat or silicon boat.
5.6 Push-pull hazel, quartz rod with a small hook. 5.7 Fluoroplastic flower basket:
5.8 Silicon wafer holder made of non-metal such as fluoroplastic or quartz. 6 Sample preparation
6.1 For silicon single crystal ingots, the samples used for testing should be taken from the retained crystals near the head and tail cut-off parts, or the samples should be cut from the parts specified by the supply and demand parties, with a thickness of 1~3 mm.
6.2 The cut sample is ground by diamond secret grinding, and polished with chemical polishing liquid (4.11) or mechanical polishing to fully remove the cutting damage. If the silicon wafer mouth is polished, the sample can be cleaned according to 7.2.1. 6.3 The surface of the sample to be tested should be mirror-like, and the surface should be free of shallow pits, oxidation, and scratches. 7 Testing procedures
7.1 Testing environment
The cleanliness of the kitchen environment for sample decontamination and oxidation should reach Class 1.000. 7.2 Decontamination and cleaning of samples and oxidation systems
7.2.1 Sample cleaning steps:
7.2.1.1 Put the samples into fluoroplastic baskets to separate the samples from each other. 7.2.1.2 Boil in sufficient cleaning solution 1*4.9) at 80~90℃ for 10~15min, and rinse with water until neutral. 7.2.1.3 Soak in hydrofluoric acid (1.2) for 2 min, rinse with water until neutral. 234
GB/T 4058—1995
7.2.1.4 Boil in sufficient cleaning solution 2\ (4.10) at 80~90℃ for 10~15min, rinse with water until neutral. 7.2.1.5 Blow dry the cleaned sample with nitrogen that has been dried and filtered, or dry the sample by appropriate methods. 7.2.2 Cleaning steps for oxidation system and device III: 7.2.2.1 Soak the furnace tube, sample boat, gas source device, etc. in a mixture of 1 volume of hydrofluoric acid (4.2) and 10 volumes of water for 2 h, and rinse with water.
7.2-2-2 Pretreat the oxidation system at 1000~1200℃ for 5~10 h. 7.3 Oxidation method
7.3.1 Load the cleaned and dried sample into the sample boat and place it at the furnace mouth. According to the procedure in Table 2, push the boat to the center of the constant temperature zone. 7.3.2 After the sample completes the thermal cycle of the procedure in Table 2, move the sample boat to a clean ventilated room and cool it to room temperature. Table 2 Oxidation operation steps
Oxidation steps
Final temperature
Final temperature
7.4 Corrosion indication of defects
1 (Bipolar)
203mm/min
5'C/min
1100℃
60 min
3.5℃/min
203mm/min
7.4.1 Move the sample to the fluoroplastic flower basket. 7.4.2 Soak the sample in sufficient amount of hydrofluoric acid for 2~3min. 2(MOS)
1000℃
203 mtm/min
1000℃
1000℃
203mm/min
3(CMOS)
900'℃
203mm/min
Br/min
1200℃
120 min
3. 5℃/min
900℃
203mm/min
7.4.3 After cleaning, the defect etching liquid is used for corrosion display. For the sample with resistivity not less than 0.2·cm, Schirntnel etching solution A (4.13) is used; for the sample with resistivity less than 0.2Ω·cm, Schimml etching solution B (4.14) is used. 7.4.4 Make the etching liquid level 4 cm above the top of the sample in the basket. The basket should be kept away from movement during the etching process. The etching time is 2 to 5 min.
7.4.5 Clean the sample thoroughly and dry it according to the method in 7.2.1.5. 235
7.5 Defect observation
GB/T 4058-1995
7.5.1 Observe the macroscopic characteristics of the defects on the sample with naked eyes under parallel light against a matte black background. 7.5.2 Observe the microscopic features of defects under a metallographic microscope. 7.5.3 Select nine measuring points on two mutually perpendicular diameters that do not intersect the main reference surface. The point selection is shown in Figure 1, that is, 4 points are selected at the edge (see Table 3), 4 points are selected at R/2, and one point is selected at the center, a total of 9 points, and the number is reported as the average value of the 9 points. [011] Reference surface or mark
(a)(100) Silicon wafer
Figure 1 Point selection position
Table 3 Edge point selection position table
[1La] Reference surface or mark
(b)(111) Silicon wafer
Distance from edge (on mutually perpendicular diameters)
7.5.4 Selection of microscope field of view area: When the defect density is not more than 1×10/cm2, take 1mm; when the defect density is more than 1×10t/cm2, take 0.2 mm2.
7.6 Defect characteristics
7.6.1 Slip
The dislocation pit pattern is composed of multiple dislocation pits arranged in a straight line and not necessarily in contact with each other (see Figure 2). 7.6.2 fog
Figure 3).
GB/T4058—1995
(a) Slip on the <111> crystal plane
(b) Slip on the 100 fret plane
Figure 2 Slip
After thermal oxidation and chemical etching, a cloud-like appearance formed by high-density shallow etch pits appears on the surface of the silicon wafer (see 237
GB/T4058—1995
Figure 3 fog
7.6.3 Oxidation stacking faults-macroscopically, it may form concentric circles, vortex shapes and other graphics, and microscopically, it may form boat-shaped, bow-shaped, oval and rod-shaped etch pits of varying sizes (see Figure 4).
(a) Volumetric oxidation stacking fault on the (111) crystal plane
Figure 4 Volumetric oxidation stacking fault
GB/T 4058—1995
(b)(100) Bulk Oxidation Stacking Fault on Crystal Plane
Continued Figure 4
7.6.4 Stripes—A series of concentric ring or spiral corrosion patterns on a macro scale (see Figure 6 of GB/T1554). At a magnification of 100 times or more, it appears as continuous surface convex stripes. 7.6.5 Vortex—A concentric circle, spiral, wave and arc-shaped pattern on a macro scale (see Figure 5). At a magnification of 100 times or more, it appears as a discontinuous butterfly-shaped (shallow) pit.
Figure 5 Vortex
7.6.6 For other related defect corrosion characteristics, see the corresponding pictures in YS/T209. 7.7 Interference Factors
7.7.1 Caused by surface damage caused by machining The pits of the oxide stacking fault are generally trapezoidal or arched, with the same size (see Figure 6).
GB/T4058—1995
Figure 6 Oxidation stacking fault caused by mechanical damage
7.7.2: Distribution of pit edge damage caused by tweezers pinching and scratching (see Figure 7) Figure 7 Pinch scratch
7.7.3 The pits or hillocks caused by the precipitation of the corrosive liquid have no obvious crystal orientation characteristics (see Figure 8) 210
8 Calculation of test results
8.1 Defect density is calculated using formula (1):
Where: N-
9 Precision
-Defect density, pieces/cm*bzxz.net
Number of defect pits in the field of view, pieces;
Field of view area, c m.
Precision is determined by cycle testing.
Test report
The test report should include the following:
Silicon wafer conductivity type, crystal orientation, resistivity
Corrosion liquid and corrosion time;
Name of defect:
Average density of defect,
Number of this standard:
Testing unit and tester;
Testing date.
Additional remarks:
GB/T4058-1995
Figure 8 Corrosion liquid precipitation
This standard was proposed by China Nonferrous Metals Industry Corporation. This standard was drafted by Emei Semiconductor Materials Factory. The main drafters of this standard are Wu Daorong, Wang Xiangdong, Hu Zheng and Liu Wenkui. 241
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