Preparation method capable of adjusting roughness of silicon wafer

Abstract

The invention relates to the technical field of semiconductor manufacturing, in particular to an adjustable silicon wafer roughness preparation method, which comprises the following steps of: annealing a silicon wafer with a low haze requirement in an inert atmosphere of less than or equal to 750 DEG C, and keeping the surface of the silicon wafer smooth; for a silicon wafer with a high haze requirement, heat treatment is carried out at the temperature of 1000-1300 DEG C in a hydrogen atmosphere, and the roughness is accurately controlled by adjusting the temperature, the hydrogen proportion, the hydrogen flow and the time. For a silicon wafer with a high haze requirement, the haze value is increased along with the increase of the hydrogen proportion and the flow under the condition that the temperature is kept unchanged; and when the hydrogen flow is not changed, the haze value is increased along with the increase of the heat treatment temperature or / and the increase of the time.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and in particular to a method for preparing adjustable silicon wafer roughness. Background Technology

[0002] During the back-end fabrication of silicon wafers, the haze, one of the micro-roughness parameters, significantly affects the electrical performance of the gate oxide layer in MOS (Metal-Oxide-Semiconductor) devices, such as the gate oxide dielectric breakdown field strength, breakdown charge density, channel carrier mobility, and transconductance. Its importance has become increasingly recognized within the industry. The roughness of silicon wafers used in the fabrication of discrete devices is typically adjusted by modifying parameters such as the polishing cloth / slurry through chemical mechanical polishing (CMP), or by wet etching to obtain different roughness morphologies. Traditional CMP or wet etching methods result in significant environmental pollution, high energy consumption, and poor uniformity of the obtained haze. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing adjustable silicon wafer roughness.

[0004] The technical objective of this invention is achieved as follows: a method for preparing adjustable silicon wafer roughness, comprising: For silicon wafers with low haze requirements, annealing is performed in an inert atmosphere at ≤750℃ to maintain a smooth silicon wafer surface. For silicon wafers with high haze requirements: heat treatment at 1000–1300°C in a hydrogen atmosphere, with roughness precisely controlled by adjusting temperature, hydrogen ratio, hydrogen flow rate, and time.

[0005] In a further proposed approach, for silicon wafers with high haze requirements: with a constant temperature, the haze value increases with the increase of hydrogen ratio and flow rate; when the hydrogen flow rate is constant, the haze value increases with the increase of heat treatment temperature and / or time.

[0006] The beneficial effects of this invention are: This invention enables the rapid acquisition of a uniformly distributed silicon wafer surface with adjustable Haze by adjusting the temperature, time, gas ratio, and flow rate during RTP rapid thermal processing. It has low energy consumption and is environmentally friendly.

[0007] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Detailed Implementation

[0008] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below.

[0009] This embodiment utilizes RTP (Rapid Thermal Processing) to obtain silicon wafers with different haze roughnesses using different gas atmospheres and temperatures, which is simple and convenient.

[0010] Referring to Table 1, at a temperature of 750°C, regardless of the duration, the haze of the silicon wafer remains essentially unchanged. At this temperature, surface reconstruction or gas reaction kinetics are insufficient to cause significant roughening. In this embodiment, the requirement for low haze (less than 0.05 ppm) of the silicon wafer is achieved under this environment: annealing is performed in an inert atmosphere (such as N2 / Ar) at ≤750°C to keep the silicon wafer surface smooth.

[0011] Table 1:

[0012] This embodiment addresses silicon wafers requiring high haze (greater than 0.05 ppm) by combining high temperature (1000–1300°C) with a hydrogen atmosphere. Roughness is precisely controlled by adjusting the hydrogen flow rate, proportion, and time, resulting in energy savings, reduced consumption, and environmental friendliness. With constant temperature and time, the haze value increases with increasing hydrogen proportion and flow rate in the mixed atmosphere; conversely, with constant hydrogen flow rate and mixed atmosphere proportion, the haze value increases with increasing heat treatment temperature and / or time.

[0013] Referring to Table 2, when the temperature reaches 1000℃, the haze value increases with the increase of hydrogen ratio and flow rate; the presence of hydrogen promotes silicon surface etching or atomic rearrangement, the mechanism of which includes: hydrogen reducing the surface oxide layer, exposing the silicon lattice; and hydrogen terminating silicon dangling bonds, enhancing surface mobility, resulting in increased roughness.

[0014] With constant hydrogen gas flow rate and mixing ratio, as the heat treatment temperature and time increase, from 750℃ to 1300℃, the haze increases exponentially from 0.05ppm to 0.3ppm. At high temperatures (>1000℃), thermodynamic driving forces minimize surface energy, forming step or island structures through silicon atom diffusion; the etching effect of hydrogen at high temperatures intensifies, forming deeper surface morphologies.

[0015] Table 2:

[0016] The above description is merely a preferred embodiment of the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing adjustable silicon wafer roughness, characterized in that, include: For silicon wafers with low haze requirements, annealing is performed in an inert atmosphere at ≤750℃ to maintain a smooth silicon wafer surface. For silicon wafers with high haze requirements: heat treatment at 1000–1300°C in a hydrogen-containing mixed atmosphere, with roughness precisely controlled by adjusting temperature, hydrogen ratio, hydrogen flow rate, and time.

2. The method for preparing an adjustable silicon wafer roughness according to claim 1, characterized in that, For silicon wafers with high haze requirements: with constant temperature and time, the haze value increases with increasing hydrogen ratio and flow rate in the mixed atmosphere; when the hydrogen flow rate and mixed ratio remain constant, the haze value increases with increasing heat treatment temperature and / or time.

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