JP2835769B2 - Crucible for Si single crystal production - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a crucible for producing a Si single crystal having a low carbon concentration.

[Prior Art] A conventional crucible for producing a Si single crystal is formed by fitting a quartz crucible 1 to a graphite crucible 2 as shown in FIG. The center of the bottom of the crucible 3 for Si single crystal is supported by a rotating shaft 4, and is housed in a chamber 7 together with a heater 5 and a heat shield 6.

In the production of a Si single crystal, polycrystalline Si charged as a raw material in the crucible 3 is heated and melted by a heater 5, an atmospheric gas is introduced from a supply port 8 provided in a chamber 7, and discharged from a discharge port 9. After heating by the heater 5 to sufficiently melt the polycrystalline Si, the seed crystal 11 held at the lower end of the pulling rod 10 is immersed in the melt 12 and pulled up to grow the Si single crystal 13.

[Problems to be Solved by the Invention] By the way, in the production of the above-mentioned Si single crystal, a reaction product (SiO) generated from the surface of the melt when heating and melting polycrystalline Si.
CO is generated by the reaction between the graphite and graphite, a part of which is mixed into the melt 12, and carbon is mixed into the crystal. The carbon mixed into this crystal interacts with oxygen also present in the crystal, and as a result, the precipitate of oxygen in the wafer obtained by cutting out the grown Si single crystal 13 becomes non-uniform, This has an adverse effect on the device manufacturing process.

For this reason, a fourth crucible is placed on the upper end of the cylindrical liquid side wall of the quartz crucible 1.
As shown in the figure, a crucible 15 for producing a Si single crystal in which an outer flange 14 is integrally provided has been proposed. (Japanese Patent Laid-Open No. 63-319288 is a prior art document.) However, the crucible 15 for producing a Si single crystal has an outer flange.
Since 14 is integrally provided on the quartz crucible 1, the cost increases,
If the outer flange 14 has a corner, the air flow is disturbed, which adversely affects single crystal growth.

Therefore, the present invention aims to provide a crucible for producing a Si single crystal, which can reduce the carbon concentration in the production of a Si single crystal, can evenly deposit oxygen in the wafer, and can be produced at a low cost. is there.

[Means for Solving the Problems] A crucible for producing an SI single crystal according to the present invention for solving the above-mentioned problems is a crucible for producing a Si single crystal, which is formed by fitting a quartz crucible to a graphite crucible. A quartz ring is provided at the upper end of the cylindrical side wall to cover the upper end of the cylindrical side wall and the upper end of the cylindrical side wall of the graphite crucible.

[Function] In the crucible for producing a Si single crystal of the present invention having the above-described structure, almost no SiO vapor enters between the quartz crucible and the graphite crucible by the quartz ring when the polycrystalline Si is heated and melted. The reaction of SiO + 2C → SiC + CO is minimized. Therefore, the carbon concentration of the manufactured Si single crystal can be reduced, and
The amount of oxygen precipitated in a wafer obtained by cutting out a single crystal can be made uniform. Moreover, the use of SiC in graphite crucibles decreased,
The life is prolonged. The quartz ring may be a slotted ring in order to prevent the quartz ring from breaking due to expansion during solidification.

[Embodiment] An embodiment of the crucible for producing a Si single crystal according to the present invention will be described with reference to Fig. 1. A quartz crucible 1 having an outer diameter of 406mm, a height of 305mm, and a thickness of 8mm is replaced with graphite having an inner diameter of 407mm and a height of 275mm. In the crucible for producing a Si single crystal, which is fitted to the crucible 2, a height of 15 to 20 mm covering the upper end of the cylindrical side wall of the quartz crucible 1 and the upper end of the cylindrical side wall of the graphite crucible 2 The quartz crucible 1 and the graphite crucible 2 are fitted by fitting a quartz ring 16 having a width of 25 to 27 mm and a wall thickness of 3 to 4 mm and having an inverted C-shaped cross section.
It is closing between. The slit of this quartz ring 16
When the Si single crystal is pulled up and solidified, the expansion force is released to prevent the quartz ring 15 from breaking even if the quartz crucible 1 breaks due to the expansion of Si. As shown in FIG. 2, the gap is usually 1 mm or less. 17 are formed.

The relative positions of the quartz crucible 1 and the graphite crucible 2 are higher for the quartz crucible 1 20 to 25 mm before melting the polycrystalline Si, and 5 mm after the melting.
It is preferable that the quartz crucible 1 is in a high state of about 15 mm.
Is deposited, and even if the quartz crucible 1 is lower than the graphite crucible 2, SiO or SiC is similarly precipitated.

The crucible 18 for producing a Si single crystal of the embodiment configured as described above, the crucible 3 for producing a Si single crystal of the prior art 1 shown in FIG. 45 kg of polycrystalline Si was charged to each of the crucibles 15 for producing a Si single crystal of the prior art 2 shown in FIG. 4 having the same dimensions as the embodiment in which the outer flange 14 having a width of 10 mm was integrally provided at the upper end of the crucible 1.
As shown in FIG. 3, the gas was used as an atmospheric gas through the supply port 8 provided in the chamber 7 at a pressure of 60 / min and pressure of 20 Torr.
r, discharged from the outlet 9 and heated by the heater 5 to sufficiently melt the polycrystalline Si.
Seed crystal 11 held at the lower end of 10 was immersed in melt 12 and pulled up to grow Si single crystal 13.

The wafer obtained by cutting out each Si single crystal 13 produced using the crucible for producing a Si single crystal of Examples and Conventional Examples 1 and 2 was measured for carbon concentration by SIMS, and the infrared spectrometer (FT)
Inspection of the distribution of oxygen precipitation by IR) yielded the results shown in the table below.

As is clear from the above table, the Si single crystal produced by using the crucible for producing a Si single crystal of Conventional Example 1 has a high carbon concentration, non-uniform oxygen precipitation distribution, and the production of the Si single crystal of Conventional Example 2. While the silicon single crystal produced using the crucible for use had a low carbon concentration but a slightly non-uniform oxygen precipitation distribution,
It can be seen that a Si single crystal produced using a crucible for producing a Si single crystal has a low carbon concentration, a uniform oxygen precipitation distribution, and a high quality wafer.

[Effects of the Invention] As can be seen from the above description, the crucible for producing a Si single crystal of the present invention covers the upper end of the cylindrical side wall of the quartz crucible fitted to the graphite crucible and the upper end of the cylindrical side wall of the graphite crucible. Since a quartz ring is provided, when heating and melting polycrystalline Si,
SiO between quartz crucible and graphite crucible by quartz ring
Almost no steam enters and therefore the Si produced
The carbon concentration of the single crystal can be reduced, the distribution of oxygen precipitation can be made uniform, and the formation of SiC in the graphite crucible decreases, and the life increases. Furthermore, the crucible for producing a Si single crystal of the present invention can be obtained simply by putting a quartz ring on the upper end of the cylindrical side wall of a normal crucible, so that the cost is low, and the crucible itself is discarded only once. The quartz ring can be used multiple times as long as the crucible has the same diameter.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a crucible for producing a Si single crystal of the present invention,
2 is a plan view, FIG. 3 is a cross-sectional view showing a pulling apparatus using a conventional crucible for producing a Si single crystal, and FIG. 4 is a cross-sectional view showing a conventional crucible for producing a Si single crystal. 1 ... Quartz crucible, 2 ... Graphite crucible, 18 ... Crucible for Si single crystal production, 16 ... Quartz ring

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-42387 (JP, A) JP-A-64-76992 (JP, A) Jikai Sho 49-98446 (JP, U) (58) Field (Int.Cl. ⁶ , DB name) C30B 15/10-15/12 C30B 28/00-35/00

Claims (1)

(57) [Claims] A quartz crucible is fitted to a graphite crucible.
A crucible for producing a single crystal, wherein a quartz ring covering the upper end of the cylindrical side wall of the quartz crucible and the upper end of the cylindrical side wall of the graphite crucible is provided. .