JPH046197A - Graphite crucible for pulling-up of silicone single crystal - Google Patents

Abstract

PURPOSE:To compensate the wettability of the surface of outer wall of the graphite crucible of high density and of high strength with the coaseness of the surface and to extend the life of the graphite crucible by providing the horizontal type ruggedness directed to the peripheral direction all over the outer peripheral surface of the side wall of the graphite crucible. CONSTITUTION:The horizontal groove-shaped ruggedness directed to the peripheral direction is provided all over the outer peripheral surface 3a of the side wall of the graphite crucible 1. The depth of the groove-shaped ruggedness Rmax is set to 50-150mum, preferably to 100-150mum as regulated surface coaseness in JIS B-0601. In this structure, the vapor-deposited Si is difficult to aggregate, which results in so called delayed generation of Si, and the Si-liquid drops 4 generated by aggregation and growth are caught and extended by the recessed surface of horizontal groove, which makes them difficult to drop down and gives so-called dam effect.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a graphite crucible for pulling silicon single crystals, and more specifically, a graphite crucible for pulling silicon tsi) by the Czochralski method (hereinafter referred to as 02 method). The present invention relates to a graphite crucible for pulling Si single crystals, which has effects such as extending the life of the Si single crystal.

Conventional Techniques The C2 method has been commonly used as a method for manufacturing 5iil crystals. This CZ method uses an apparatus in which a quartz crucible is housed in a graphite crucible surrounded by a graphite heating element, and the crucible is placed in a storage case with an inert gas atmosphere.

In recent years, in order to obtain silicon single crystals with high yield, large-sized crucibles with large diameters have been manufactured, and the graphite crucibles that are part of the manufacturing equipment have also become larger. Materials with high density and high strength are now being used.

By the way, as the capacity of a graphite crucible increases, thermal strain increases, there is a high probability that breakage will occur, and the life span of the crucible becomes shorter, so there is a need for a way to extend the life span of the crucible. As a solution to this problem, for example, dividing the graphite crucible into multiple parts, and
As described in Publication No. 0892, the outer peripheral surface of a graphite crucible and! Alternatively, it has been proposed to provide a cutting horse on the inner peripheral surface.

These methods have the advantage of absorbing stress to some extent and having a certain effect.

However, the following problems remain with this method. In other words, (1) The graphite crucible has a high density and high strength due to its large size, and the finished surface of the outer wall surface is good, so silicon droplets form on the outer wall surface of the graphite crucible faster.
(2) The grown 81 drops drip down and seep into the crucible's face and into the gap between the graphite crucible and its tray. (3) This seeped Sl is absorbed by the graphite crucible. The receiver reacts with the graphite in the plate to generate SiC and changes its dimensions. (4) The above phenomenon is repeated each time it is used, and 5iCl
As i increases, the surface area of the graphite crucible and the gap formed between the graphite crucible and the plate become larger, and the cracking caused by oxidative consumption of graphite is accelerated. There was a problem that the product could no longer be used (in other words, it would reach the end of its life).

Problems to be Solved by the Invention The present invention aims to solve the above-mentioned problems.In terms of installation, the wettability of the outer wall surface of a high-density, high-strength graphite crucible is compensated for by surface roughness, thereby extending the life of the graphite crucible. The purpose of this study is to propose an effective graphite crucible for pulling silicon single crystals.

Means for Solving the Problems and Their Effects, namely, the present invention is characterized in that horizontal groove-like irregularities are provided on the entire outer circumferential surface of the side wall of a graphite crucible, oriented in the circumferential direction.

Hereinafter, the configuration and operation of the means of the present invention will be explained in detail with reference to the drawings.

18) and till respectively indicate one embodiment of the graphite crucible of the present invention, (al is a vertical sectional view, (bl is a partially enlarged sectional view of the side wall portion thereof, and FIG. al, (b) and fcl respectively indicate the adhesion state of 51 debris on the outer wall of the side wall of the graphite crucible of the example of the present invention and the comparative example, ta) is the comparative example, (bl and IcI are each an example of the example) It is a partially enlarged vertical cross-sectional view of the third
Figure (a), tb+ and (C1 are respectively shown in Figure 2 (a)
1, (bl and tc), and FIG.
l, (b) and (C1 are respectively shown in Fig. 2 (al, (
5(a), tb] and tel.
are respectively front views of FIGS. 4 tal, till and (C1), and FIG. 6 is a perspective view showing a conventional graphite crucible.

1 is the graphite crucible body, 2 is the tray, 3a is the outer wall, 3
b indicates the inner wall, and 4 indicates 81 drops.

First, as shown in Figure 1 (al and (b)), a graphite crucible is composed of a graphite crucible body 1 and a tray 2 that is in contact with the lower part of this crucible body 1. The outer circumferential surface of the side wall of this graphite crucible body 1 is not cut 1/46 as in the conventional example shown in FIG. The inner circumferential surface of the inner 13b was finished in substantially the same manner as in the conventional example.

The finishing of the inner and outer walls of the side walls of the graphite crucible body 1 can be carried out in the same manner as thread cutting, for example, by machining with a cutting tool on a lathe so that horizontal spiral irregularities are formed in a direction perpendicular to the upper surface of the crucible. The depth of the horizontal spiral unevenness of 3a is the surface roughness RIlaX specified in JIS B 0601.
50 to 150μI, preferably 100 to 150μI, and the surface roughness of the inner peripheral surface of inner 13b is Rmax25 to 30
Let it be μm.

With this configuration, the deposited Sl aggregates with a delay in the so-called 81 generation, and the Sl droplets that aggregate and grow are caught by the concave surface of the horizontal spiral and spread downward, It becomes droopy and gives a so-called dam effect.

In addition, since the graphite crucible body 1 is large, if it is configured to have high density and high strength by blending fine particles, it is possible to make the surface rough even though it is a high density, high strength graphite product that contains fine particles. This has the effect of combining the advantages of a coarse particle formulation.For example, when blending fine particles, the average porosity of only the graphite openings measured by a mercury porosimeter is 3μ or less. It is preferable to use one with a certain degree.

Note that the graphite crucible of the present invention may be a split crucible, a crucible with cut grooves, or any other conventionally used crucible, but the entire outer peripheral surface of the side wall of the graphite crucible of the present invention is provided with horizontal grooves. If the unevenness is oriented in the circumferential direction, a graphite crucible having the above-mentioned excellent effects can be obtained.

Example 1 A cutting tool depth similar to thread cutting was used to form horizontal groove-like unevenness oriented in the circumferential direction on the entire outer peripheral surface of the side wall of a high-density graphite crucible with an inner diameter of 3) 0 g as shown in Fig. 1, 181 and fbl. Finish processing was performed using a lathe as shown in Table 1.

Next, silicon single crystals were repeatedly produced using each graphite crucible using a C7 method silicon crystal production apparatus. For comparison, the same graphite crucible as in the example was used except that the graphite crucible having the outer peripheral surface of the outer wall shown in Table 1 was used. The results under these conditions are shown in Table 1.

Table 1 (Sho I RIlaX was measured in accordance with JIS B 0601 using a method of measuring roughness.

When using the graphite crucible of the comparative example, see Figure 2 (ta)
As shown in Fig. 3, the outer circumferential surface of the outer wall has a Rmax of 20 μm, so the deposited S+ immediately drips down, and as shown in Fig. It was used 18 times.

When the graphite crucible shown in Example 1 is used, the depth of the horizontal groove-like unevenness on the outer wall surface is R×50μ and the comparison example as shown in FIG. 2(b) and FIG. 3(b). Since it is rougher than that of 81%, the generation of Si droplets is slow, and the evaporated 81%
As shown in Figures 4(b) and 5+b), as time passes, the droplets spread into the horizontal groove-shaped concave surface formed along the entire outer circumferential surface and become difficult to drip downward, and the number of times the droplets can be used repeatedly is 20 batches. there were. As shown in FIG. 2 tcl and FIG. 3 (C), the crucible using the graphite crucible of Example 2 had a rough depth of 100 μm of horizontal grooves on the outer wall surface, so the crucible of Example 1 was used. The generation of SiJ is slow compared to It was 25 batches.

<Effects of the Invention> As explained in detail above, the present invention is characterized in that horizontal groove-like irregularities are provided on the entire outer circumferential surface of the graphite crucible side wall so as to be oriented in the circumferential direction.

According to the present invention, horizontal groove-like unevenness is provided on the entire outer peripheral surface of the side wall of the graphite crucible, oriented in the circumferential direction.
When used to pull an 81 single crystal in a single crystal manufacturing device, it prevents the deposited Si from agglomerating (retards the generation and growth of 81 debris, and prevents the formation of Si particles formed by agglomerated growth on the surface). The life of the graphite crucible is significantly superior to that of the conventional method because it is caught by the horizontal groove-like concave surface of the graphite crucible, preventing it from spreading and falling downward. This has the advantage that it can be easily performed using a turning tool on a lathe.

[Brief explanation of drawings]

FIG.
) is a partially enlarged sectional view of the side wall part, Figure 2 ial, fb
1 and tel indicate the adhesion state of 5iW4 on the outer wall of the side wall of the graphite crucible of the example of the present invention and the comparative example, respectively, +al is the comparative example, and fbl and +C1 are partially enlarged vertical cross-sectional views of an example of the example, respectively. , Figure 3(a), Fbl
and tc+ are the front view of Figure 2 tal, (bl and (C1), Figure 4 fat, tbl and (C
1 is a partially enlarged vertical cross-sectional view showing the state after the lapse of time in FIG. 2 (aJ, (b) tC), and FIG. 5 (al
, (bl and t, C1 are respectively Fig. 4 tal, F
bl and tc+ are front views, and FIG. 6 is a perspective view showing a conventional graphite crucible. Code 1... Graphite crucible body 2... Receiver is plate 3a... Outer wall 3
b...inside! 14... Si droplet patent applicant Representative of Nippon Carbon Co., Ltd. Patent attorney Matsushita l! Katsu Attorney Fumio Soejima Figure 4 (&,) (C) (Shin (Q) (L) Figure 3 81! 6

Claims (1)

[Scope of Claims] 1) A graphite crucible for pulling a silicon single crystal, characterized in that horizontal groove-like unevenness is provided on the entire outer peripheral surface of the side wall of the graphite crucible, oriented in the circumferential direction. 2) The graphite crucible for pulling a silicon single crystal according to claim 1, wherein the depth of the horizontal groove-like unevenness is Rmax 50 to 150 μm as defined by JISB0601. 3) The graphite crucible for pulling a silicon single crystal according to claim 1, wherein the depth of the horizontal groove-like unevenness is Rmax 100 to 150 μm as defined by JISB0601.