JPS637025B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Field of Application of the Invention The present invention relates to a method for manufacturing silicon single crystal wafers used for manufacturing semiconductor integrated circuits and the like.

(2) Conventional technology Conventionally, integrated circuits (abbreviated as IC) and large scale integration (Large Scale Integration)
(abbreviated as LSI) devices were mainly silicon single-crystal wafers grown by the pulling method (CZ method) with a residual oxygen content of approximately 5×10 ¹⁷ atoms·cm ^-3 or more. Single-crystal silicon wafers grown using the floating zone method (FZ method), which contain a small amount of oxygen (usually less than 1×10 ¹⁷ atoms cm ^-3 ), are not widely used as LSI device materials. The reason for this is that FZ silicon wafers are weak against heat treatment at temperatures above 1000℃ due to their low oxygen content, and as a result of the formation of lattice defects such as dislocations, it is difficult to improve LSI manufacturing yields. It is. However, even in CZ crystal wafers, since they contain a large amount of oxygen, heat treatment at temperatures of 1000°C or higher tends to generate micro defects that adversely affect the characteristics, making it difficult to improve LSI manufacturing yields.

Therefore, wafers of LSI element material have a high concentration of oxygen (approximately 3×
10 ¹⁷ atoms·cm ^-3 or higher), and silicon wafers that are less likely to generate micro defects even when subjected to high-temperature heat treatment are desirable. In other words, a wafer in which interstitial oxygen is difficult to precipitate is desirable as an LSI element material. However, at present, it is not easy to obtain silicon wafers that introduce fewer dislocations and are less likely to generate micro defects through high-temperature heat treatment. In other words, if the current wafers are used, even if CZ wafers are used, FZ
Even if wafers are used, it is not easy to increase the manufacturing yield of highly integrated LSIs.

(3) Purpose of the Invention The purpose of the present invention is to provide a method for manufacturing silicon single crystal wafers that can improve the problems of the prior art described above and effectively improve the manufacturing yield of highly integrated LSI devices. There is a particular thing.

(4) General description of the invention In order to achieve the above object, in the present invention, a silicon wafer is heat treated at a high temperature of 1300° C. or higher for a short period of time, and then rapidly cooled. This freezes the interstitial oxygen in the silicon single crystal to a metastable state and suppresses the growth of micro-defect nuclei, thereby preventing the precipitation of interstitial oxygen even during high-temperature heat treatment. can do. That is, it makes it difficult to generate lattice defects in the crystal, and also suppresses the generation of dislocations due to heat treatment.

The reason why CZ silicon wafers are more prone to micro defects due to high-temperature heat treatment than FZ silicon wafers is that CZ crystal wafers have a higher oxygen content than FZ crystal wafers based on the crystal growth conditions. This is because interstitial oxygen gathers at the microdefect nuclei, precipitates oxygen, and induces a large number of microdefects.

On the other hand, since the FZ silicon wafer contains low oxygen concentration, it cannot be expected to suppress the generation of dislocations and the movement of dislocations based on this. As a result, not only is the wafer likely to slip due to high-temperature heat treatment, but the wafer may also be warped.

Therefore, in the present invention, the oxygen concentration is maintained at the same level as in conventional CZ silicon wafers, and the interstitial oxygen within the crystal is not precipitated even during heat treatment. To achieve this, the grown crystals are heat-treated at a high temperature of 1300°C or higher for a short period of time to maintain the above properties in the silicon wafer.

(5) Examples Hereinafter, the present invention will be explained in detail with reference to examples.

As shown in FIG. 1, the interstitial oxygen in current silicon single crystal wafers is significantly reduced when heat treatment is performed at around 800° C. in a dry oxygen atmosphere.
Note that similar results can be obtained in a nitrogen atmosphere. It has also been found that wafers with a significant decrease in interstitial oxygen due to heat treatment at temperatures around 800°C are more likely to generate micro defects when subjected to high-temperature heat treatment at 1000°C or higher. Therefore, by performing heat treatment at around 800℃,
It is possible to determine whether interstitial oxygen within a wafer is likely to precipitate, and whether micro defects are likely to occur due to high-temperature heat treatment at 1000°C or higher. In the following examples, the present invention will be explained using this heat treatment at around 800°C as a determination method.

(100) CZ silicon single crystal wafer (3 inches, 450μm thickness) at 1300℃ for 16 minutes.
It was heat treated in a dry oxygen atmosphere and pulled out of the heat treatment furnace at varying speeds. When the interstitial oxygen concentration of these wafers was measured by infrared absorption method, the concentration was approximately 1×10 ¹⁸ atoms·cm ⁻³ in all cases.
After heat-treating these wafers at 800°C in a dry oxygen atmosphere for 64 hours, the interstitial oxygen concentration of these wafers was also measured using an infrared absorption method. As shown in FIG. 2, the amount of interstitial oxygen reduced by this 800°C heat treatment varied depending on the wafer withdrawal speed during the 1300°C heat treatment. When the drawing speed was 0.16 cm/sec or higher, no decrease in interstitial oxygen could be detected even after heat treatment at 800°C for 64 hours. In addition, after the above 1300℃ heat treatment,
After heat treatment for 64 hours at 1050℃ in a dry oxygen atmosphere, the X-ray intensity was measured, and as shown in Figure 3, the X-ray intensity also changed depending on the wafer withdrawal speed during the 1300℃ heat treatment. . When the drawing speed was 0.16 cm/sec or more, the X-ray intensity was almost the same as that of as-grown wafers even after this heat treatment. That is, when the drawing speed was 0.16 cm/sec or higher, almost no microdefects were generated in the wafer even if heat treatment was performed at 1050° C. for a long time. In addition, the wafer withdrawal speed during 1300℃ heat treatment is from 0.16cm/sec to
When the speed was up to 0.64 cm/sec, almost no dislocations occurred on the wafer, and no slips occurred.

Based on the above experimental results, the as-grown wafer was heat treated in a dry oxygen atmosphere at 1300℃ for 16 minutes.
Wafers are processed at a withdrawal speed of 0.32cm/sec,
When used in a bipolar LSI process, not only no stacking faults occurred near the surface of the wafer, but also almost no microdefects occurred inside the wafer. Further, no slip occurred on the wafer, and therefore, warping of the wafer due to heat treatment could hardly be detected. As a result,
Not only have the characteristics of LSI improved, but the manufacturing yield has also improved significantly compared to conventional methods. Similar effects were obtained even when the preheat treatment at 1300°C was performed in a dry oxygen atmosphere containing HCL gas.

The following effects can be expected from the present invention.
The silicon wafer according to the present invention is less likely to generate lattice defects during heat treatment, and is also less likely to generate dislocations that cause wafer warpage, so its properties will only improve when used as a semiconductor device material. Therefore, the manufacturing yield is significantly improved.

[Brief explanation of the drawing]

Figure 1 shows the interstitial oxygen concentration at various temperatures after heat treatment for 64 hours in a dry oxygen atmosphere, and Figure 2 shows the interstitial oxygen concentration at various temperatures after heat treatment in a dry oxygen atmosphere for 16 minutes at 1300°C. Dry oxygen atmosphere 800
℃, Figure 3 shows the amount of interstitial oxygen reduction in wafers heat-treated for 64 hours. Figure 3 is in a dry oxygen atmosphere.
FIG. 3 is a diagram showing the X-ray intensity of wafers that were heat-treated at 1300° C. for 16 minutes at different drawing speeds and then heat-treated at 1050° C. for 64 hours in a dry oxygen atmosphere.

Claims (1)

[Claims] 1 After heat treating a silicon single crystal wafer grown by the CZ method and having an interstitial oxygen content of approximately 3×10 ¹⁷ /cm ^{3 or more} in a heat treatment furnace at a temperature of 1300°C or higher, A method for producing a silicon single crystal wafer, comprising the step of drawing it out from the heat treatment furnace at a drawing speed of up to 0.64 cm/sec.