Source flow control system for negative-pressure diffusion furnace

Abstract

The invention relates to a source flow control system for a negative-pressure diffusion furnace. The source flow control system comprises a source flow supply unit, a carrier gas supply unit and a pressure control unit, wherein the carrier gas supply unit is connected with the gas input end of the source flow supply unit through a first control valve; the pressure control unit is connected between the output end of the source flow supply unit and the reaction cavity of the negative-pressure diffusion furnace, can sense the pressure values of the two ends of the source flow supply unit or the pressure value of the output end of the source flow supply unit, and enables the process gas pressure in the inlet of the pressure control unit to achieve the predetermined value through controlling the interval valve, wherein the predetermined value of the process gas pressure is lower than or equal to the atmospheric pressure. Therefore, the source flow control system enables the source flow, introduced in the reaction cavity, to meet the demands of silicon chip sheet resistance and junction depth through precisely controlling the source flow of the diffusion furnace, so that the interference factors of the source flow are largely decreased; in addition, the invention further provides effective and rigorous anti-explosion protective measures.

Description

technical field [0001] The invention relates to the field of semiconductor devices and processing and manufacturing, and more specifically relates to a source flow control system for a negative pressure diffusion furnace. Background technique [0002] The negative pressure diffusion furnace is the most important process equipment in the front process of semiconductor and photovoltaic production lines, and it can also be said to be the most critical equipment in the semiconductor and solar energy industries. It can be used in diffusion, oxidation, annealing, alloying and sintering processes in industries such as large-scale integrated circuits, discrete devices, power electronics, optoelectronic devices and optical fibers. The main purpose of the negative pressure diffusion process is to dope the semiconductor wafer under high temperature conditions, that is, to diffuse the elements phosphorus and boron into the silicon wafer, so as to change and control the type, concentrati...

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Problems solved by technology

However, the negative pressure required in the reaction chamber of the negative pressure diffusion equipment is sometimes very small. If the source flow is under atmospheric pressure for process gas and carrier gas input, due to the difference between the source flow of the negative pressure diffusion equipment and the atmospheric pressure Larger, the source flow rate will increase significantly, and the pressure of the source bottle will increase significantly, and there is a risk of bursting. In this way, many interference factors affecting the phosphorus source or boron source will be generated and it is difficult to control

[0006] In addition, the overload protection design of the flow rate, temperature and pressure of the carrier gas of the negative pressure diffusion equipment is not perfect, which not only directly leads to the difficulty in the safe production of silicon wafers with high square resistance and high uniformity, but also the danger of explosion

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