JPS63297211A - Si-b alloy dopant material for production of si single crystal by pulling up method - Google Patents

Abstract

PURPOSE:To extremely reduce segregation of B dope in an obtained Si single crystal rod and to uniform electric characteristics of wafer in production of Si single crystal by pulling method, by using a Si-B alloy dopant made of specific B. CONSTITUTION:In producing Si single crystal, a Si-B alloy for dopant material is constituted by using B comprising >=95wt.% <11>B, an isotope and <=5wt.% <10>B.

Description

Detailed Description of the Invention [Industrial Application Field] This invention provides a Si-B alloy dopant material (- It is related to

[Conventional technology]

General (-1Si single crystal rods are produced by melting polycrystalline St and a Si-B alloy as a dopant material into a melt in a quartz crucible, and then inserting the tip of a seed crystal with a predetermined crystal orientation into the melt. It is produced by pulling up the seed crystal at a predetermined speed while rotating the crucible and the seed crystal at predetermined rotational speeds.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional S1 single crystal rod, the dope B segregates, so that, for example, the upper part, the middle part of the rod,
and the B concentration at the bottom (nivaracchi occurs, and in a wafer sliced from a rod with two local variations like this, the electric properties of the wafers, especially the resistance value (-
If variations occur, not only will the yield decrease, but there will also be problems in terms of quality control.

[Means for solving problems]

Therefore, the inventors of the present invention, from the above-mentioned viewpoint.

In order to manufacture Si single crystal rods without segregation of dope B,
In particular, Si-B alloy dopant materials (second focus and research have shown that B in conventional Si-B alloy dopant materials consists of natural B, and this natural B is 11B in a weight ratio of approximately 80:20). It is composed of two types of isotopes, B and IOB, and the ratio of these isotopes B and IOB is 11
B accounts for 95% or more, while 10B accounts for 5% or less (weight% above, below % indicates weight%):
It was discovered that the segregation of dope B in Si single crystal rods produced by the pulling method was eliminated, and wells with uniform properties could be obtained.

This invention was made based on the above knowledge (= the proportion of the isotope B accounts for 95% or more,
On the other hand, it was composed of B in which the proportion of 10 B was 5% or less.

This is a characteristic feature of the Si-B alloy dopant material for producing S1 single crystals by the pulling method.

In addition, in the B component (:) consisting of two isotopes, 11B and 10B, if the proportion of 11B is less than 95%, the proportion of IOB will inevitably increase to more than 5%, and such a proportion In the B-containing Si-B dopant material composed of 11B and IOB, the segregation of dope B cannot be effectively suppressed as described above. The ratio of 11B and IOB was set as 95% or more for 11B and 5% or less for 10B.

〔Example〕

Next, the dopant material of the present invention will be specifically explained using Examples.

First, boron trifluoride consisting of 11B and IOB in the proportions shown in Table 1 (-) was produced by isotope separation method of chemical exchange distillation of boron trifluoride using anisole. Dopant materials 1 to 3 of the present invention and comparative dopant materials 1 to 3 are prepared by forming metal B from boron trifluoride by conventional chemical means and alloying it with Si at a ratio of 0.1%. 3 were produced respectively.

In addition, comparative dopant materials 1 to 3 all have a ratio of 11'H that is lower than the range of the present invention, and among these, comparative dopant material 1 corresponds to the conventional dopant material. It is.

Table 1 Next, the various dopant materials obtained as a result were placed in a quartz crucible with an inner diameter of about 350 M (two people placed it in an Ar atmosphere) at a ratio of polycrystalline Si: 30Kf and dopant material: 0.49. The crucible was heated to a temperature of 1420° C. to form a melt, and the crucible was rotated at l Q r pm, while the seed crystal attached to the melt was rotated at 2 Orpm, and the seed crystal was heated for 1.s. By pulling at a speed of mm 7 minutes, diameter: approximately 130 ran x length:
Si single crystal rods with dimensions of 900+w were each manufactured.

Next, for the various Si single crystal rods obtained as a result, B at the upper part (50 m inside from the upper end), the center part, and the lower part (50 mm + inside from the lower end)
Concentration and specific resistance were measured respectively.

The results of these measurements are shown in Table 1.

〔Effect of the invention〕

From the results shown in Table 1, the dopant materials 1 to 3 of the present invention
In the Si single crystal rod manufactured using 11B, the segregation of B concentration is extremely small and the resistivity is almost constant throughout the rod, whereas the proportion of 11B is 95%.
It is clear that when comparative dopant materials 1 to 3 of less than

As mentioned above, the 5L-B alloy dopant material (
According to 2, it is possible to manufacture St single crystal rods with extremely low B concentration segregation, and therefore wafers sliced from this rod have homogeneous electrical properties, resulting in improved yield and easier quality control. Industrially useful effects such as these are brought about.

Claims (1)

[Claims] A pulling method characterized in that the Si-B alloy is composed of B in which the proportion of the isotope ^1^1B is 95% by weight or more, while the proportion of the isotope ^1^0B is 5% by weight or less. Si-B alloy dopant material for Si single crystal production.