GB/T 43313-2023Test method for surface quality and micropipe density of polished silicon carbide wafers—Confocal and differential interferometry optics (English PDF)

Foreword

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

1 Scope

This document specifies the confocal differential interference test method for the surface quality and microtube density of 4H silicon carbide polished wafers.

This document is applicable to diameters of 50.8mm, 76.2mm, 100mm, 150mm, and 200mm, and thickness ranges from 300µm to 1000µm Testing of surface quality and microtube density of polished silicon carbide wafers.

2 Normative reference documents

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

GB/T 14264 Semiconductor material terminology

GB/T 25915.1-2021 Clean rooms and related controlled environments Part 1: Classification of air cleanliness levels according to particle concentration

GB/T 30656 Silicon carbide single crystal polished wafer

3 Terms and definitions

The terms and definitions defined in GB/T 14264 apply to this document.

4 Principles

Using a confocal differential interference optical system, the incident light passes through the Nomarski prism and objective lens and then hits the wafer surface, which is reflected by the wafer surface.

The light reaches the detector through the confocal optical system. Scan the entire surface of the wafer under test to obtain the true image of each position on the wafer surface.

The image is compared with the preset characteristic parameter information of various defects, the collected defects are classified and identified, and the number of defects is tallied.

Calculate, and then obtain the distribution map of various types of defects on the wafer surface, as well as the number of various types of defects.

5 Interference factors

5.1 The environment of the clean room will affect the statistics of particle data on the crystal surface and affect the accuracy of the test results.

5.2 The stability of the light source will affect the signal collection of various defects by the instrument, and misjudgments are prone to occur during image analysis.

5.3 The instrument parameter setting is mainly to define the defect categories, so the instrument parameter setting will also affect the accuracy of crystal surface defect classification. accuracy.

5.4 Contamination on the surface of the wafer will increase the number of sample defects, and will also affect the instrument's identification of scratches, pits, particles, and microtubes on the sample surface. and statistics, affecting the accuracy of test results.

5.5 The surface roughness of the wafer is too large, which affects the accuracy of the test results.