JPS59138344A - Method for detecting strain of semiconductor material - Google Patents

Abstract

PURPOSE:To enable to detect the strain a semiconductor material with good accuracy by a method wherein the strain of the semiconductor material is detected by measuring the warp of a thin plate after working the semiconductor material into the thin plate of less than a specific thickness. CONSTITUTION:The strain of the semiconductor material is detected by measuring the warp of the thin plate sample after working the semiconductor material into the thin plate whose thickness is 300mum or less. By this detecting method, the warp due to strain, etc. sharply appears because of the thin sample, and therefore quality control of a high accuracy can be performed. Besides, it is sufficient that the thickness of the sample is 300mum or less.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a method for detecting crystal strain in semiconductor materials.

[Technical Background of the Invention and Problems thereof] Generally, integrated circuits are fabricated on a semiconductor substrate, and this semiconductor substrate must be free of dislocations and distortions in its crystal structure. Therefore, if there are dislocations, problems such as an increase in leakage current and a decrease in breakdown voltage will occur in the manufactured integrated circuit.
Further, if there is distortion, it becomes difficult to carry out the desired integrated circuit manufacturing process. Furthermore, strain can also cause dislocations.

Dislocations and strains can be roughly divided into three types depending on when they are formed. The first is what occurs within the crystal when a semiconductor single crystal ingot is made.

The second step is when a wafer is produced from an ingot, that is, when the wafer is cut out using a diamond blade, and when it is wrapped. At this point, distortions mainly occur in the surface layer, and most of them can be removed by subsequent etching, but the distortions that occur inside remain as they are. The third type is generated during the manufacturing process of integrated circuits, and is mainly generated due to non-uniform temperature during heat treatment.

In this way, the manufacturing process of integrated circuits involves many steps that cause distortion and dislocation in semiconductor materials, so in order to obtain integrated circuits with the desired performance, it is necessary to evaluate the quality of ingots and wafers and to evaluate the integrated circuit manufacturing process. evaluation is essential. Since dislocations are often generated by strain, these evaluations are generally performed by detecting strain. Since distortion is often accompanied by warpage, these evaluations are actually performed by detecting warpage of the wafer. However, even if warpage cannot be detected, the distortion and dislocations contained in the semiconductor material can cause defects in the manufactured integrated circuits, and conventional methods have had problems in terms of product yield. . Furthermore, as the diameter of the wafer increases, the thickness of the wafer also tends to increase. As wafers become thicker, distortion becomes less likely to appear as warpage, making it increasingly difficult to detect distortion during chipping.

[Purpose of the invention] The present invention has been made in view of the above circumstances.

The purpose of this invention is to provide a highly accurate strain detection method for semiconductor materials.

[Summary of the invention] The strain in the semiconductor material is reduced by processing the semiconductor material to a thickness of 30%.
After cutting into a thin plate of 0 μm or less, the warpage of the thin plate sample is measured and detected. Since the thickness of the sample is thin, cracks caused by distortion etc. appear sharply, allowing highly accurate quality control.

[Embodiments of the invention] Example 1 P type, (1
00) orientation is subjected to various steps to form a bipolar IC on a silicon wafer. During the process, the temperature is
A heat treatment step at 000 to 1200'C is also included. Then, when the Ueno-〇 warpage was measured, the warpage value was within 1 μm. However, those ueno・
The yield of products obtained from - was low. There was no clear correlation between the amount of waste and the quality of the product, and it was not possible to determine which process was causing the problem.

Therefore, we wrapped the back side of the Ueno that had been subjected to various processes, and then etched it to remove the distortion on the surface caused by the wrapping. When measured, the value was 50
It was ~150 μm. The initial increase in the value of μm is not due to distortion, but is also caused by uneven cutting when cutting out the wafer, but the increase in the value of μm in this case is due to distortion of the wafer, etc. This is considered to be due to the amount of distortion, and the magnitude of this increase can be considered to indicate the magnitude of the amount of distortion. When the process was improved so that the value of the anti-reflection value was within 30 μm, the yield of the product was improved by about 20q6.

Example 2 P type, (1
When silicon mirror wafers with the 00) orientation were purchased from several manufacturers and their warpage was measured, the warpage of the wafers from all manufacturers was within 10 μm.

Next, wafers from each manufacturer were lapped and etched to a thickness of 250μmKL, and the warpage was measured.The wafers from a certain company (Company A) had a warpage of 80μm, and the warpage of wafers from other companies It is within 20 μm. When we conducted a detailed material evaluation of Company A's wafers, we found that there were microscopic defects in the crystal structure, and that the wafers were unsuitable for use as semiconductor substrates.

In addition, in the above two examples, when measuring the resistance,
The thickness of the semiconductor material was processed to 150 and 250 μm, respectively, but it is sufficient that the thickness is 300 μITI or less, which is the thickness at which warping due to strain etc. begins to appear sharply.
It is not limited to 0.250 μm, etc.

[Effects of the Invention] The present invention detects distortion of the semiconductor material by processing the semiconductor material into a thin plate with a thickness of 300 μm or less and measuring the warpage of the thin plate, and is useful for evaluating the quality of ingots and wafers and for integrated circuits. It is possible to easily and accurately evaluate manufacturing processes.

Claims (2)

[Claims] (1) A method for detecting strain in a semiconductor material, characterized in that crystal strain in an ingot is detected by measuring warpage of a thin plate cut out from the ingot and having a thickness of 300 μm or less. (2) A method for detecting strain in a semiconductor material, characterized in that crystal strain in a semiconductor wafer is detected by processing the wafer into a thin plate with a thickness of 300 μm or less and measuring the warp of the thin plate.