CN112779601B

CN112779601B - Growth method of heavily arsenic-doped extremely-low-resistance silicon single crystal

Info

Publication number: CN112779601B
Application number: CN202011542745.2A
Authority: CN
Inventors: 李英涛; 王万华; 皮小争; 崔彬; 吴志强; 刘斌
Original assignee: Shandong Youyan Semiconductor Materials Co ltd; Youyan Semiconductor Silicon Materials Co ltd
Current assignee: Shandong Youyan Semiconductor Materials Co ltd; Youyan Semiconductor Silicon Materials Co ltd
Priority date: 2020-12-23
Filing date: 2020-12-23
Publication date: 2022-08-05
Anticipated expiration: 2040-12-23
Also published as: CN112779601A

Abstract

The invention discloses a growth method of heavily arsenic-doped extremely-low-resistance silicon single crystal. Adopting a CZ Czochralski method, comprising the working procedures of vacuumizing, leak detection, material melting, doping, stabilizing, seeding, shouldering, isometric diameter and ending; the method is characterized in that argon is adopted to purge the surface of the shoulder part of the monocrystalline silicon in the shouldering stage, a plurality of argon pipelines are arranged around the monocrystalline rod, the included angle between the blowing direction of the argon and the axial direction of the monocrystalline rod is 20-25 degrees, and the gas outlet of each argon pipeline is positioned at the position 100-120 mm below a water cooling body; and closing the argon from the argon pipeline after the shouldering is finished. The device required by the invention has simple structure, simple and convenient operation and easy realization, the shoulder-laying success rate can reach more than 90 percent, and the extremely-low resistance ratio is more than or equal to 91.3 percent.

Description

Growth method of heavily arsenic-doped extremely-low-resistance silicon single crystal

Technical Field

The invention relates to a growth method of heavily arsenic-doped ultra-low resistance silicon single crystal, belonging to the technical field of growth of czochralski silicon single crystal.

Background

Heavily arsenic (As) -doped silicon single crystal wafers are ideal epitaxial substrate materials. The resistivity value of the arsenic-doped silicon single crystal is determined by the doping amount of the doping element arsenic, and the resistivity of the silicon single crystal is lower as the doping amount of arsenic is larger.

The current market demands more and more for Czochralski heavily arsenic doped very low resistance silicon single crystals with resistivity lower than 0.003 omega cm. However, the production of the arsenic-heavily doped czochralski silicon single crystal having an extremely low resistivity is extremely difficult, and one of the reasons is that when the arsenic-heavily doped czochralski silicon single crystal having an extremely low resistivity is produced, the concentration of arsenic in the silicon melt is high, the high concentration of arsenic causes a strong volatilization phenomenon on the surface of the molten silicon, and the arsenic particles generated by volatilization easily fall back into the silicon melt to terminate the dislocation-free growth process, resulting in a reduction in the crystal yield of the silicon single crystal.

The CZ single crystal furnace for pulling the CZ heavily arsenic-doped silicon single crystal mainly comprises four parts: 1. a furnace body: including quartz crucibles, graphite crucibles (for supporting quartz crucibles), heating and heat insulating members, furnace walls, etc. 2. Single crystal/crucible pulling rotation mechanism: comprises a seed crystal chuck, a steel wire rope and a lifting rotating device; 3. atmosphere and pressure control system: comprises argon flow control, a vacuum system, a pressure automatic control valve and the like; 4. the control system comprises: sensors, computer control systems. At present, the industry grows heavily arsenic-doped low-resistance silicon single crystals by using argon and flow direction of an auxiliary chamber as main crystal pulling conditions and taking the flow rate as a process window.

Disclosure of Invention

The invention aims to provide a growth method of heavily arsenic-doped extremely-low-resistance silicon single crystal, which can effectively improve the success rate of shouldering to obtain the extremely-low-resistance silicon single crystal.

In order to achieve the purpose, the invention adopts the following technical scheme:

a growth method of heavily arsenic-doped ultra-low resistance silicon single crystal adopts CZ Czochralski method, and comprises the working procedures of vacuumizing, leak detection, material melting, doping, stabilizing, seeding, shouldering, diameter equalizing and ending; wherein, argon is adopted to purge the surface of the shoulder part of the monocrystalline silicon in the shouldering stage, a plurality of argon pipelines are arranged around the monocrystalline rod, the included angle between the blowing direction of the argon and the axial direction of the monocrystalline rod is 20-25 degrees, and the gas outlet of each argon pipeline is positioned at the position 100-120 mm below the water cooling body; and closing the argon from the argon pipeline after the shouldering is finished.

Preferably, the number of the argon gas pipelines is 2-6, and the argon gas pipelines are symmetrically distributed around the single crystal rod.

Preferably, the argon flow of the argon pipeline is 5-20 slpm. When the flow of the argon gas is too small, high-concentration arsenic and SiO volatile matters on the surface of the shoulder part of the monocrystalline silicon cannot be taken away in time, and when the flow of the argon gas is too large, crystals can shake. The flow of argon gas in the argon gas pipeline is preferably 5-15 slpm, and more preferably 5-10 slpm.

Preferably, the distance from the gas outlet of the argon pipeline to the shoulder position is 200-300mm, and the distance range is more favorable for achieving a better purging effect.

The invention has the advantages that:

the growth method of the heavily arsenic-doped extremely-low-resistance silicon single crystal provided by the invention has the advantages that the argon purging function is added in the conventional shouldering stage, high-concentration volatile matters of arsenic and SiO can be carried away in time, and the shouldering success rate is improved, so that the extremely-low-resistance silicon single crystal is obtained. The device required by the invention has simple structure, simple and convenient operation and easy realization, the shoulder-laying success rate can reach more than 90 percent, and the extremely-low resistance ratio is more than or equal to 91.3 percent.

Drawings

FIG. 1 is a schematic structural diagram of a Czochralski crystal growing furnace.

FIG. 2 is a schematic diagram of argon gas pipeline distribution.

Detailed Description

The present invention is further illustrated with reference to the following figures and examples, which are not meant to limit the scope of the invention.

As shown in FIG. 1, the structure of a Czochralski crystal growing furnace is schematically shown, and in the growing method of the invention, an argon pipeline is additionally arranged in the Czochralski crystal growing furnace. As shown in the figure, an arrow A indicates the flow direction of argon gas, the argon gas flows into an argon gas pipeline 3 from a throat 1 of the furnace body, the argon gas pipeline can extend along the inner wall of the water cooling body 2 to a distance from the lower end of the water cooling body, and the distance H from an outlet of the argon gas pipeline to the lower end of the water cooling body 2 is 100-120 mm. And the blowing direction of the argon gas and the axial included angle of the silicon single crystal are 20-25 degrees, namely the included angle alpha between two argon gas pipelines symmetrically distributed on two sides of the silicon single crystal rod is 40-50 degrees in the figure. And in the shouldering stage, argon is blown to the shoulder part 4 of the monocrystalline silicon, and the argon pipeline is closed after the shouldering is finished. Thus, a heavily arsenic-doped silicon single crystal having a resistivity of less than 0.003. omega. cm and a crystal orientation of <100> is grown.

In the following examples, SR/CR (12-16)/(8-12) was controlled in a single crystal furnace during single crystal pulling, where SR represents the single crystal rotation speed and CR represents the crucible rotation speed.

Examples

The method comprises the steps of using a Czochralski crystal growing furnace, installing a 22inch thermal field, filling 110kg of primary polycrystalline silicon material, adding arsenic powder according to the doping amount g/feeding amount kg of 7/1, and obtaining the heavily-doped arsenic silicon single crystal with the crystal orientation of <100> and the resistivity of less than or equal to 3m omega cm through the working procedures of evacuation, leakage detection, melting, doping, stabilization, seeding, shouldering, diameter equalization and ending, wherein the diameter of the silicon single crystal to be drawn is 8 inches. Two argon gas pipelines (same alpha angle; 4 equispaced, as shown in figure 2; H is different) were made separately and tested at different flow rates L:

the first set of test data shows that the shoulder-off success rate can reach 100% when H is 100mm, α is 45 ° and L is 10slpm, but the seed crystal is slightly shaken.

The second set of test data shows that the shoulder-off success rate can reach 100% when H is 120mm, α is 45 ° and L is 10slpm, and no other abnormality exists.

Summarized by two sets of experimental data, the most preferred conditions are H120 mm, α 45 °, and L10 slpm.

Comparative example

The method comprises the steps of using a Czochralski crystal growing furnace, installing a 22inch thermal field, filling 110kg of primary polycrystalline silicon material, adding arsenic powder according to the doping amount g/feeding amount kg of 7/1, and obtaining the heavily-doped arsenic silicon single crystal with the crystal orientation of <100> and the resistivity of less than or equal to 3m omega cm through the working procedures of evacuation, leakage detection, melting, doping, stabilization, seeding, shouldering, diameter equalization and ending, wherein the diameter of the silicon single crystal to be drawn is 8 inches. The control in the single crystal furnace during the single crystal pulling was the same as in the examples, and the control of the parameters of the argon gas line was different from those in the examples, as shown in the following table.

And (4) conclusion: the method is simple and low in cost, and obviously improves the success rate of shouldering heavily-doped silicon single crystals. The shoulder-laying rate of the conventional method is about 33 percent, and the extremely-low resistance proportion is about 55 percent, wherein the extremely-low resistance proportion is the ratio of the crystal length of which the resistivity is less than 0.003 omega cm to the total length of the crystal; the method has the advantages that the total times of shoulder-laying tests are 326 times, the success times are 295 times, the success rate is about 90.5%, the extremely-low resistance ratio is about 91.3%, and the shoulder-laying success rate and the low resistance ratio of the heavily arsenic-doped silicon single crystal are greatly improved in practical production.

Claims

1. A growth method of heavily arsenic-doped ultra-low resistance silicon single crystal adopts CZ Czochralski method, which comprises the working procedures of vacuum pumping, leak detection, material melting, doping, stabilization, seeding, shouldering, diameter equalization and ending; the method is characterized in that the resistivity of the heavily arsenic-doped silicon single crystal is less than or equal to 3m omega cm; in the shouldering stage, argon is adopted to purge the surface of the shoulder of the monocrystalline silicon, a plurality of argon pipelines are arranged around the monocrystalline rod, and the number of the argon pipelines is 2-6 and the argon pipelines are symmetrically distributed around the monocrystalline rod; an included angle between the blowing direction of the argon and the axial direction of the single crystal rod is 20-25 degrees, and an air outlet of the argon pipeline is positioned at a position 100-120 mm below the water cooling body; the argon flow of the argon pipeline is 5-20 slpm; and closing the argon from the argon pipeline after the shouldering is finished.

2. The method for growing the heavily arsenic-doped extremely low-resistance silicon single crystal as claimed in claim 1, wherein the argon gas flow of the argon gas pipe is 5 to 15 slpm.

3. The method as claimed in claim 1, wherein the distance from the outlet of the argon pipe to the shoulder is 200-300 mm.