JPH02188488A - Quartz crucible for pulling up high-quality silicon single crystal - Google Patents

Abstract

PURPOSE:To increase the oxygen content of a silicon single crystal and to improve the quality of the single crystal by cutting the inner surface of the quartz crucible to provide a recess, and further smoothing the peripheral edge of the recess. CONSTITUTION:The inner surface of the quartz crucible is cut to provided a recess for increasing the contact area with the molten silicon. Consequently, the oxygen content of the silicon single crystal is increased from the conventional 10<17>atoms/cc level to the 1-2X10<18>atoms/cc level close to the saturation point. The inner surface of the crucible can be cut regularly or irregularly to form the recess. The recesses can be spotted, or the filamentary recesses are arranged in parallel. In addition, the recesses can be formed over the whole inner surface of the quartz crucible, or partially formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a quartz crucible used when manufacturing silicon single crystals by melting polycrystalline silicon. More specifically, the present invention relates to a quartz crucible for producing high quality silicon single crystals by increasing the concentration of oxygen contained in the silicon single crystals.

[Conventional technology and key points]

Silicon single crystals for semiconductor device production are currently mainly produced by the Czochralski method (CC7, method).

In the C2 method, polycrystalline silicon is filled in a quartz crucible,
The silicon single crystal is pulled out from the molten silicon by heating and melting it to about 1450°C. In this method, oxygen is taken into the silicon single crystal by melting in a quartz crucible during pulling of the silicon single crystal. Silicon wafers that contain oxygen at a relatively high concentration have the advantage of having a gettering effect that eliminates impurities such as heavy metals and microscopic defects, and that there is little yield loss due to deformation during processing steps.

Therefore, there has been a demand for a quartz crucible that can increase the concentration of oxygen contained in silicon single crystals, and various efforts have been made. A method for increasing the oxygen concentration in silicon single crystals produced by
4574), or a crucible in which coarse quartz powder, quartz glass plates or rods are welded to the inner surface of the crucible (JP-A-6L-
44793), etc. have been proposed. However, the former method has a serious defect that impurities contained in the sand remain during sand blasting and are easily mixed into the single crystal, and furthermore, although it is expected to be effective in the first single crystal pulling, the second and subsequent Pulling has almost no effect; in the case of the latter type of crucible, quartz powder, quartz glass plates, rods, etc. welded inside the crucible peel off during single crystal pulling, resulting in foreign matter contamination, which lowers the single crystallization yield. It is unavoidable that production is complicated and costs are high.

[Knowledge related to problem solving]

As a result of various research into solving the above-mentioned problems, the present inventors found that a quartz crucible in which the inner surface of the crucible is provided with a recess with a cut mark to increase the surface area of the inner surface of the crucible is capable of absorbing silicon during pulling of a silicon single crystal. It has been found that by increasing the resistance between the melt and the surface of the crucible, the concentration of oxygen taken into the single crystal from the crucible increases. This crucible is easier to manufacture than the above-mentioned rerubo, which has coarse quartz powder welded to its inner surface, and is less likely to cause peeling problems.Also, by providing many scraping marks in the recesses, it is easier to pull the single crystal from the second time onwards. It was found to be effective.

〔Effect of the invention〕

The present invention provides a silicon single crystal characterized by providing a recessed portion with regular or irregular scraping marks on the inner surface of the crucible, and further smoothing the periphery of the recessed portion to increase the oxygen concentration contained in the silicon single crystal. We provide quartz crucibles for pulling.

A quartz crucible for pulling a silicon single crystal according to the present invention.

The purpose is to manufacture silicon single crystals containing high oxygen concentration in order to obtain silicon wafers with less stacking faults and deformation during processing steps. When pulling a silicon single crystal, the oxygen taken into the single crystal is taken in the form of SiO, which is produced when 5in2 contained in the quartz crucible used for pulling reacts with Si in the silicon melt. The saturation point of the oxygen content in the
It is said to be ordered by EC.

The quartz crucible of the present invention has a concavity formed by cutting marks on its inner surface to increase the contact area with the silicon melt, thereby lowering the oxygen concentration in the silicon single crystal from the conventional Io17.
1~2XlO”J close to the saturation point from the level of atoms/cc
) It is a quartz crucible that can be raised to the level of i/CC. The concave portions of the scraping marks carved on the inner surface of the crucible may be regular or irregular. Further, the shape of the recesses may be spot-like, or they may be in the form of lines arranged in parallel.Furthermore, the recesses may be carved over the entire inner surface of the quartz crucible, or may be carved in one portion. In other words, in the present invention, the shape, pattern, and number of the recesses carved on the inner surface of the quartz crucible are not particularly limited. The oxygen concentration in the silicon single crystal can be controlled relatively easily.

To carve a recess on the inner surface of a quartz crucible, the inner surface of the crucible is scraped with, for example, a diamond tool to form a scraping mark. Thereafter, it is necessary to heat-treat the scraped area with, for example, an arc flame, oxyhydrogen flame, or the like, or to etch it with hydrofluoric acid or the like to smooth the periphery of the recess formed in the scraped area. If the periphery of the shaving mark is not smooth, quartz pieces will easily separate from the periphery of the shaving mark during pulling of the silicon single crystal, and if these quartz pieces adhere to the silicon single crystal, they will cause dislocations, which will prevent the silicon from becoming a single crystal. This causes a decrease in yield. When heat treating the peripheral edge of the scraped area with an arc flame, it is desirable to use a graphite electrode of high purity (ash content of 5 ppra or less) to prevent contamination of the inner surface of the crucible due to adhesion of ash, etc.

The inner surface of the quartz crucible is eroded by about 0.2 to 0.5 cm by one pulling of a silicon single crystal, so when pulling a single crystal for the second time or later using the quartz crucible of the present invention, it is necessary to It is best to increase the depth of the scraping marks in advance to make the recesses on the inner surface of the crucible larger. However, if the recesses are made too deep, the crucible may be damaged when pulling the single crystal, so the thickness of the crucible peripheral wall should be about 8 mm. In this case, the depth of the recess is 0.5 to 3. This depth, which is preferably about O1, can be freely selected depending on the conditions under which the crucible is used.

〔Effect of the invention〕

The silicon single crystal produced using the quartz crucible of the present invention has a significantly higher oxygen concentration in the single crystal than the silicon single crystal produced using the conventional quartz crucible, As for the silicon single crystals pulled for the second and third times using this method, single crystals containing high oxygen concentrations were obtained like the single crystals for the first time, and the single crystallization yield was also good.

[Examples and comparative examples]

Lines with a depth of 2.5 mm were evenly carved at 3 mm intervals on the inner surface of a quartz crucible made by the rotary molding method, and the peripheral edges of the scraped marks were heated with an arc flame using a high-purity lead electrode. (Example 1) and the same method! On the inner surface of the quartz crucible manufactured by Ill. ). Next, concentric grooves with a width of 51 Ill and a depth of 2 weight were carved on the inner bottom surface of a quartz crucible manufactured in the same manner (Example 3). In addition, as a comparative example, we used the above five types of quartz crucibles: a conventional quartz crucible without recesses (Comparative Example 1), and a quartz crucible whose entire inner surface was sandblasted (Comparative Example 2). A silicon single crystal was produced, and the average oxygen concentration and single crystallization yield in the single crystal were measured. The results are shown in a table for comparison.

Oxygen concentration was measured by infrared absorption spectrophotometry.

Example 1 Comparative Example 1 ■, 85 1.75 1.75 0.90 1.50 1.80 1.70 1.70 0.80 0.90 ■, 85 1.70 1.70 0.80 0. 80 Procedural amendment April 1999 1311 Yoshi, Commissioner of the Japan Patent Office 1) Takeshi Moon 1, Display of case 1999 Patent Application No. 006237 2, Title of invention Quartz crucible for pulling high quality silicon single crystals 3, Amendment Relationship with the case of a person who does the following Patent applicant name (526) Mitsubishi Kinkutsu Co., Ltd. 4, agent (164) Address City Heim Cosmo Room 1003, 1-31-4 Honmachi, Nakano-ku, Tokyo

Claims (1)

[Claims] A quartz crucible for pulling a silicon single crystal, characterized in that the inner surface of the crucible is provided with a recess with regular or irregular scraping marks, and the periphery of the recess is smoothed to increase the oxygen concentration contained in the silicon single crystal. .