GB/T 24581-2022Test method for III and V impurities content in single crystal silicon—Low temperature FT-IR analysis method (English PDF)

Foreword

This document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for Standardization Work Part 1: Structure and Drafting Rules of Standardization Documents" drafted.

This document replaces GB/T 24581-2009 "Low-temperature Fourier Transform Infrared Spectrometry Determination of the Content of Group III and V Impurities in Silicon Single Crystals" Compared with GB/T 24581-2009, in addition to structural adjustment and editorial changes, the main technical changes are as follows.

a) Deleted "Purpose" (see Chapter 1 of the.2009 edition);

b) Changed the measurement range of boron (B), phosphorus (P), arsenic (As), aluminum (Al), antimony (Sb), gallium (Ga), and increased the measurement of indium (In) content (see Chapter 1, Chapter 2 of the.2009 edition);

c) Changed terms and definitions (see Chapter 3, Chapter 5 of the.2009 edition);

d) The measurement conditions for samples with impurity content less than 5.0x10^11 cm-3 are added (see 5.6);

e) The second strong absorption band P (275cm-1) is used to calculate the content of phosphorus (P) element (see 5.8);

f) Added the effect of doped silicon single crystal on the measurement (see 5.9);

g) Changed the method of polycrystalline transformation into single crystal (see 5.12, 8.1 of the.2009 edition);

h) Changed the requirements for Fourier transform infrared spectrometers (see 7.4, 7.4 of the.2009 edition);

i) Added micrometer and its accuracy requirements (see 7.5);

j) Changed the spectral range of non-zero response values (see 9.2, 10.2 of the.2009 edition);

k) Changed the number of scans of the background spectrum (see 9.7, 11.5 of the.2009 edition);

l) Changed the number of scans for samples (see 9.10, 11.8 of the.2009 edition);

m) The peak position, baseline and integration range and calibration factor corresponding to P(275cm-1) are added in Table 1 (see 10.1);

n) The unit of impurity content has been changed, and the calculation formula has been revised accordingly (see 10.4, 13.1 and 13.2 of the.2009 edition);

o) Changed the precision of the measurement results (see Chapter 11, Chapter 15 of the.2009 edition);

p) Changed the content of the test report (see Chapter 12, Chapter 14 of the.2009 edition);

q) Deletion of deviations and keywords (see Chapters 16 and 17 of the.2009 edition).

1 Scope

This document describes a method for the determination of group III and V impurities in silicon single crystals by low temperature Fourier transform infrared spectroscopy.

This document applies to group III and V impurities containing aluminum (Al), antimony (Sb), arsenic (As), boron (B), gallium (Ga), indium (In) and phosphorus (P) in silicon single crystals.

The measurement range of each element (in terms of atomic number) is 1.0x10^10 cm-3 ~ 4.1x10^14 cm-3.

2 Normative references

The contents of the following documents constitute essential provisions of this document through normative references in the text. Among them, dated citations documents, only the version corresponding to that date applies to this document; for undated references, the latest edition (including all amendments) applies to this document.

GB/T 8322 Molecular Absorption Spectroscopy Terminology

GB/T 14264 Terms of Semiconductor Materials

GB/T 29057 Procedures for evaluating polycrystalline silicon rods by zone melting method and spectroscopic analysis

3 Terms and Definitions

Terms and definitions defined in GB/T 8322 and GB/T 14264 apply to this document.

4 Principles of the method

When the silicon single crystal sample is cooled to below 15K, the infrared spectrum is mainly a series of absorption bands caused by impurity elements. use one A continuous white light source illuminates the sample so that the light energy is greater than the energy band of the compensating impurity. The infrared beam is directly transmitted through the sample, and the transmitted light is collected The spectrum is converted into an absorption spectrum after subtracting the background spectrum. Establish baselines on characteristic absorption bands of impurity elements and calculate their absorption bands area. The content of group III and V impurity elements is calculated according to the general absorption law and the calibration factors for group III and V impurity elements given in this document.

5 Interfering factors

5.1 In order to eliminate the influence of free carriers, the sample should be cooled to below 15K to measure group III and V impurity elements. Fix the sample on the cold head When the sample is in contact with the cold head, good contact should be maintained to obtain a high heat transfer efficiency. Oxygen absorption at 1136cm-1 and 1128cm-1 The collected band is very sensitive to temperature and can be used to judge the sample temperature. When the sample temperature is higher than 15K, the absorption intensity of oxygen at 1136cm-1 is 3 times the absorption intensity of 1128cm-1; while below 15K, the ratio will be greater than 3.

5.2 If there is not enough continuous white light, the donor and acceptor of compensation will not produce absorption, so there should be enough intensity of white light to completely cancel.

Compensation for all donors and recipients. The area or height of the absorption peaks of group III and V impurities can be determined by gradually increasing the white light intensity of the instrument. Optimal white light intensity affected by increased light intensity.