JP2732967B2 - Method for manufacturing high-resistance silicon wafer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a high-resistance silicon wafer.
In particular, the present invention relates to a method for manufacturing a large-diameter silicon wafer having a resistivity of 10,000 Ωcm or more at low cost.

[0002]

2. Description of the Related Art A silicon single crystal is produced by zone melting a polycrystalline silicon rod from the upper and lower parts to form a single crystal.
In the FZ method, polycrystalline silicon is melted in a quartz crucible, a seed crystal is immersed in this melt, and a single crystal is pulled while rotating.In this CZ method, a magnetic field is applied to the melt to melt the silicon. Method of pulling single crystal by controlling convection of liquid (MC
These methods are abbreviated as Z method), and each of these methods has characteristics in the pulled single crystal.

For example, in the CZ method, a large amount of oxygen can be taken into a single crystal, so that an intrinsic gettering (IG) effect can be expected in a highly integrated circuit manufacturing process. In the MCZ method, the intensity of a magnetic field must be changed. It is possible to control the amount of oxygen dissolved in the single crystal by the method.Since the crucible is not used in the FZ method, a very high-resistance silicon wafer containing no oxygen can be obtained. However, there is a negative aspect in terms of cost in growing and increasing the diameter of the polycrystalline silicon rod.

[0004]

However, when a silicon single crystal is manufactured by the MCZ method and sliced to form a silicon wafer, the silicon wafer has a resistivity of 10,000 due to impurities dissolved from the crucible. The resistance cannot be as high as Ωcm or more, and this countermeasure is regarded as a problem.

[0005]

SUMMARY OF THE INVENTION The present invention relates to method for producing a high resistivity silicon wafer which solves such a disadvantage, which the silicon polycrystal, the content of impurities
Is melted in a synthetic quartz glass crucible with a small amount , a magnetic field is applied to the melt, a silicon seed crystal is immersed and pulled up to form a silicon single crystal, and the silicon single crystal is sliced to have a resistivity of 10,000Ωcm or more Characterized by obtaining a silicon wafer of

That is, the present inventors have a resistivity of 10,000Ω.
As a result of various studies on the method of making a silicon wafer having a diameter of more than 1 cm by the MCZ method, a high-resistance silicon wafer could not be obtained in the conventional method because a metal impurity was contained in a crucible used for pulling a silicon single crystal. This is because the crucible conventionally used contains a large amount of Al, which is a trivalent impurity, which is incorporated into the silicon single crystal when the silicon single crystal is pulled. Accordingly, it has been found that a silicon wafer having a high resistance can be obtained if the crucible is made of such synthetic quartz glass having a small amount of impurities, and the research on this synthetic quartz glass crucible has been advanced to complete the present invention. Was.
This will be described in more detail below.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a method for manufacturing a high-resistance silicon wafer .
Melt in a synthetic quartz glass crucible with low content, pull up a silicon single crystal from this melt by the MCZ method, and slice this silicon single crystal to produce a high-resistance silicon wafer with a resistivity of 10,000 Ωcm or more Things.

In the production of a high-resistance silicon wafer according to the present invention, a high-purity polycrystalline silicon is melted in a synthetic quartz glass crucible, and a silicon single crystal is pulled up from this melt by the MCZ method and thus obtained. This is performed by slicing a silicon single crystal. The synthetic quartz glass crucible used here was obtained by a so-called sol-gel method of hydrolyzing and polycondensing an alkoxysilane such as methyl silicate with ammonia, drying, closing and vitrifying. What is necessary is just to make the thing made from synthetic quartz glass with few impurities, and this synthetic quartz glass is an amorphous thing which consists of a sintered body of colloidal silica.

For the production of this synthetic quartz glass, there is a method in which conventionally known silicon tetrachloride is flame-hydrolyzed with an oxyhydrogen flame to produce silica fine particles, which are then fused to produce synthetic quartz glass. The synthetic quartz glass obtained by the method has an OH group content of 1,000 ppm or more and has a low viscosity at high temperature, and has a disadvantage that it deforms and foams at a high temperature in a vacuum, and is used in the present invention. When the silica is gelled even in the case of the above-mentioned sol-gel method, the silica has small pores and is closed at a low temperature, so that it contains gas and water. Although degassing and dehydration are performed by crystallization, impurities cannot be mixed in this crystallization step, so that this cannot be used in the present invention.

However, if this silica is made of colloidal silica, it has large pores and can be easily dehydrated and degassed by heating, so that crystallization is unnecessary and no impurities are introduced. If the amount of Al as an impurity can be reduced to 100 ppb or less by sufficiently purifying the alkoxysilane as a raw material, and the viscosity can be increased to 10 ¹⁰ poise or more at 1,400 ° C. It can be advantageously used for crucible production in the present invention.

In this synthetic quartz glass crucible, a synthetic quartz glass powder comprising an amorphous sintered body of colloidal silica obtained by the sol-gel method is supplied to a molding die to form a powder layer in the mold. After that, it can be manufactured by melting this by arc discharge to form a transparent layer made of synthetic quartz glass in a mold, which is formed on the inner surface of a known natural quartz glass crucible. may be Tsu der those obtained by forming a layer.

However, when the synthetic quartz glass crucible has a synthetic quartz glass layer formed on the inner surface of a natural quartz glass crucible, the silicon single crystal is formed if the natural quartz glass layer is partially exposed. Since it is contaminated by contact with natural quartz glass, it is necessary that this synthetic quartz glass layer be formed with a thickness of 0.5 mm or more from the inner surface, but this remains about 0.3 mm after the silicon single crystal is pulled. Preferably, the whole crucible is made of synthetic quartz glass.

The synthetic quartz glass crucible thus produced has a small amount of metal impurities contained in the synthetic quartz glass as described above. But
If this contains 100 ppb or more of Al, the silicon wafer obtained by slicing this silicon single crystal will have a low resistivity, so that it is necessary that Al be 100 ppb or less.

In the production of a high-resistance silicon wafer according to the present invention, a silicon polycrystal is melted in such a synthetic quartz glass crucible, a magnetic field is applied to the melting, and a silicon single crystal is pulled up by the MCZ method. This is performed by slicing the crystal. The magnitude of the magnetic field for performing the MCZ method may be 1,000 to 3,000 G. According to this, since there is no change in the molten metal surface, a continuous charge is possible. Since long-time pulling is possible and the in-plane residual oxygen concentration is adjusted, the silicon wafer obtained by slicing this silicon single crystal has the advantage of having a high resistivity of 10,000 Ωcm or more. Given.

[0015]

Next, examples of the present invention and comparative examples will be described. Example 1) Production of a synthetic quartz glass crucible In a reactor in which the inner surface of a 5 liter round continuous flask made of SUS was coated with tetrafluoroethylene resin, 27 liters / hour of aqueous ammonia and 24.5 liters / hour of methyl silicate were used. Was added dropwise to produce colloidal silica, which was dehydrated with a centrifugal dehydrator and then washed four times with ultrapure water.

Then, the silica was placed in a quartz crucible, and the temperature was raised from room temperature in an electric furnace.
Time, 1,000 ° C for 3 hours, heating time to each temperature as 0.5, 4, 2 respectively, after heat treatment in air,
This was put into a carbon mold, and the temperature was raised from room temperature under reduced pressure to 1,200 ° C. for 2 hours, 1,500 ° C. for 3 hours, 1,750 ° C.
C. 1 hour, the temperature was raised to each temperature for 2, 2, and 2 hours, respectively, to raise the temperature to obtain a synthetic quartz glass. The obtained ingot was washed with 20% by weight of HF for 1 hour, dried and then jaw crusher. And crushed with a desk mill, sieved and 45
６０60 mesh, acid-washed with 20 % by weight of HCl, floated with pine oil, and then 5% by weight of HF
For 15 minutes, heat-treated at 1,050 ° C., and subjected to a magnetic separation machine to obtain a synthetic quartz glass powder.

Next, the synthetic quartz glass powder is supplied into a rotating molding die to form a powder layer having a thickness of 14 mm.
After 15 minutes, synthetic quartz glass powder was supplied into the mold to form a transparent layer having a thickness of 1 mm on the inner surface to form a 18-inch diameter crucible. The synthetic quartz glass crucible was made by removing and removing the same height by cutting, and the analysis results of each metal in this crucible were as shown in Table 1.

[0018]

[Table 1]

2) Production of silicon single crystal The 18-inch synthetic quartz glass crucible obtained as described above was washed with an ammonia - hydrogen peroxide solution and a hydrofluoric acid aqueous solution, and then sufficiently washed with ultrapure water. Installed in a pulling machine, 60 kg of high-purity polycrystalline silicon as a raw material for pulling a silicon single crystal was charged into this crucible, and this polycrystalline silicon was melted under normal pressure in an argon gas atmosphere. A silicon seed single crystal is brought into contact with a magnetic field of 3,000 G to pull up a non-doped <100> 6 "φ silicon single crystal, and the obtained silicon single crystal is sliced to a thickness of 0.5 mm to form a silicon wafer. measurement of the amount of metal impurities in the wafer, results of as shown in Table 1 were obtained, was examined resistivity of the silicon wafer by four probe method, which Table 2 Unit:
Was 16,000 ~56,000 Ωcm as shown in Ωcm).

Comparative Example An N-type silicon single crystal was prepared in the same manner as in the example, except that the synthetic quartz glass crucible used in the example was a natural quartz glass crucible whose metal content was as shown in Table 1. performs pulling, was investigated metal components of the wafer by slicing a future silicon wafer, which is as shown in Table 1, was examined resistivity of the wafer, which is Table 2 (unit : Ωcm)
It was 950 ~3,500 Ωcm as shown in.

[0021]

[Table 2]

[0022]

According to the present onset Akira, according to the present invention, pulling of silicon single crystal
Quartz glass crucible that are used to raise is synthetic quartz glass crucible content is less of Al as metal impurities,
And this silicon single crystal is pulled by MCZ method.
Therefore, the obtained silicon single crystal, and further, the silicon wafer obtained by slicing the silicon single crystal has a low Al content , and the silicon wafer has a resistivity of 10,000.
The advantage of high resistance of Ωcm or more is provided.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Masatoshi Takita 28-1, Nishifukushima, Oaza, Kushiro-mura, Nakatsukujo-gun, Niigata Prefecture Synthetic Technology Research Laboratory, Shin-Etsu Chemical Co., Ltd. (72) Inventor Mitsuo Matsumura 2-chome Kitafu, Takefu City, Fukui Prefecture No. 13-60 Shin-Etsu Quartz Co., Ltd., Takefu Plant (72) Inventor Hiroshi Matsui 2-13-13, Kitafu, Takefu-shi, Fukui Prefecture Shin-Etsu Quartz Co., Ltd., Takefu Plant (72) Inventor Shinichi Furuse Nishigo-mura, Nishishirakawa-gun, Fukushima Prefecture 150 Odakura Ohira Shin-Etsu Semiconductor Shirakawa Plant (56) References JP-A-2-6382 (JP, A)

Claims (2)

(57) [Claims] 1. The method of claim 1 , wherein the polycrystalline silicon is prepared by adding alkoxysilane.
Amorphous colloidal silica obtained by hydrolytic polycondensation
Is melted in a synthetic quartz glass crucible composed of porous sintered material, a magnetic field is applied to this melt, a silicon seed crystal is immersed and pulled up to form a silicon single crystal, and this silicon single crystal is sliced. A method for producing a high-resistance silicon wafer, wherein a silicon wafer having a resistivity of 10,000 Ωcm or more is obtained. 2. Polysilicon is applied to the surface and the synthetic layer.
The content of Al as metal impurities
The thickness of the synthetic quartz glass layer is at least
Melting in a synthetic quartz glass crucible measuring 0.5 mm
A magnetic field is applied to the melt, and a silicon seed crystal is immersed in the magnetic field.
Dipped and pulled up to make a silicon single crystal, this silicon single crystal
Silicon with a resistivity of 10,000Ωcm or more by slicing a crystal
High resistance silicon wafer characterized by obtaining a wafer
Manufacturing method.