Transition and diffusion method for aluminum impurity source

Abstract

The invention discloses an aluminum impurity source diffusion method providing a vacuum diffusion furnace and a half-sealed diffusion pipe with a plug; firstly, processing saturated diffusion doping for silicon co-chip and inner wall of the diffusion pipeline, then processing diffusion doping for test chip for t1 time by the silicon co-chip and inner wall of the diffusion pipeline, measuring thinlayer resistance of the test chip, calculating time t2 that needed by normal chip diffusion according to experience formula, finally processing diffusion doping that is accurately controlled for the normal chip for t2 time by the silicon co-chip and inner wall of the diffusion pipeline after saturated diffusion doping. Therefore, manufacturing cost is reduced and potential safety hazard that useshydrogen is eliminated, providing even, stable, controllable chip surface doping concentration.

Description

technical field [0001] The invention relates to the technical field of semiconductor manufacturing, in particular to an aluminum impurity source transfer diffusion method for a power semiconductor device chip. Background technique [0002] With the development of power semiconductor devices towards high voltage, high current, and high conversion power, it is required to make a PN junction with a high breakdown voltage on the power semiconductor device chip. For this reason, a low-concentration aluminum diffusion doping method is usually used to form PN P region of the junction. [0003] At present, manufacturers at home and abroad generally adopt the method of "closed tube expansion aluminum" for aluminum doping. Figure 1 to Figure 4 For the process schematic diagram of this prior art, the main method of this technology is: with reference to figure 1 As shown, put the cleaned official device chip 7 and high-purity aluminum source 1 into the semi-closed quartz tube 2, refe...

AI Technical Summary

Problems solved by technology

[0005] 1. Since it is necessary to break the quartz tube to take the chip after each diffusion doping, the quartz tube must be discarded every time it is used, thus increasing the production cost. At the same time, the glass powder produced when the quartz tube is broken may also causing contamination of the chip

[0006] 2. In order to maintain a high vacuum state in the quartz tube during diffusion, use a vacuum pump to evacuate the tube to a high vacuum and seal the quartz tube mouth with a hydrogen-oxygen flame. Hydrogen is a flammable and explosive gas, so there are potential safety hazards that endanger production and personal safety

[0007] 3. Since the official chip is directly doped with a high-purity aluminum source, the relative standard deviation of the doping concentration on the chip surface is usually 6-10%, so the error is large, and the doping effect is not ideal, which affects the stability of the product and pass rate

[0008] 4. Since the official chip is directly doped with a high-purity aluminum source, although the saturated diffusion is performed for a long time, the relationship between the diffusion doping time and the doping concentration on the chip surface cannot be determined, so the diffusion time and the control of the chip surface concentration cannot be accurately calculated.

Images