Impurity diffusion process in semiconductor device preparation process

Abstract

The invention discloses an impurity diffusion process in a semiconductor device preparation process, and belongs to the technical field of semiconductor device manufacturing. The process first performs an impurity pre-deposition process, and then a diffusion furnace is heated to a re-diffusion temperature T2 at a rate of 5 DEG C / min under a mixed atmosphere of nitrogen and oxygen; the impurities are re-diffused, and finally the diffusion furnace is placed under a nitrogen atmosphere of 5 slm to be cooled to below 600 DEG C at a rate of 3 DEG C / min, and a silicon wafer is taken put and then naturally cooled. The impurity pre-deposition and diffusion process in the furnace are completed at one time to avoid the influence of repeated lifting and lowering temperature on product parameters andperformance and shorten a large amount of process time.

Description

technical field [0001] The invention relates to the technical field of semiconductor device preparation, in particular to an impurity diffusion process in the semiconductor device preparation process. Background technique [0002] The diffusion process is to dope a certain amount of certain impurities into the semiconductor material (such as silicon crystal) to change its electrical properties, and make the amount, distribution and depth of the doped impurities meet the requirements, so as to form the device function. At present, the pre-deposition plus re-diffusion process is commonly used, which is also the most widely used preparation method in the semiconductor diffusion process. Pre-deposition is to pass the gas containing the required impurities through the surface of the silicon wafer at high temperature, so that the impurities are decomposed from the compound, and these impurities are concentrated in a thinner layer on the surface of the silicon surface. The specific...

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Problems solved by technology

But this method also has some deficiencies. There are three main points: First, the process time is long. Taking the base diffusion process as an example, the square resistance reaches 5Ω / □, and the junction depth is about 10 μm. The overall process time will reach more than ten hours. It will affect the production capacity and progress for a long time, and the process deviation will be relatively large; secondly, there are more temperature rises and falls. After the step, it stays outside for a long time, which is easy to introduce contamination problems. Even if the cleaning operation is performed, it will also cause problems such as surface leakage, which will affect the parameters and performance of the chip.

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