A kind of manufacturing method of depletion mode field effect transistor

Abstract

The invention discloses a manufacturing method of a depletion type field effect transistor and relates to the technical field of semiconductors, the method sequentially fabricates a block-shaped discrete thick oxide layer on the epitaxial layer, a gate oxide layer and a discrete step-type polysilicon gate. Then make the body area, a local thick oxide layer and a step formed by a polysilicon gate electrode are use for ion implantation, as that ion implantation has different ability to penetrate the barrier with different thicknesses, ion doping in the channel region and ion doping in the source-drain region can be for simultaneously in the ion implantation process, and the requirements for ion concentration of the channel region and the source region can be met, the photolithography level is saved, and the fabrication step is simplified; In addition, since the doping in the channel region is fabricated after the body region is driven in, the ion doping distribution in the channel regionis not affected by the driving heat process in the body region, and the threshold voltage stability of the fabricated field effect transistor can be ensured.

Description

technical field [0001] The invention relates to the technical field of semiconductors, in particular to a manufacturing method of a depletion type field effect transistor. Background technique [0002] Field effect transistors mainly include enhanced field effect transistors and depletion type field effect transistors. At present, the conventional manufacturing process of the active area of ​​depletion type field effect transistors is as follows: [0003] 1. An N-type epitaxial layer 2 is grown on the surface of the N-type substrate 1, and a gate oxide layer 3 is formed on the upper surface of the N-type epitaxial layer 2. Please refer to figure 1 . [0004] 2. The N-type region 4 is formed in the N-type epitaxial layer 2 by photolithography and implantation process, please refer to figure 2 . [0005] 3. Form the polysilicon gate 5 through deposition, photolithography and etching processes, please refer to image 3 . [0006] 4. The P-body region 6 is formed by ion im...

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Problems solved by technology

[0011] However, the above manufacturing method has the following disadvantages: (1), in order to realize the inversion of the channel, it is necessary to make a special N-type implantation region in the channel region, and photolithography is required, which is cumbersome

(2) Because the N-type implantation of the channel region is completed before the P-body region, the subsequent drive-in thermal process of the P-body region will affect the distribution of ions implanted in the channel region, and the lateral and vertical diffusion is relatively serious , the doping concentration of the channel region is difficult to precisely control

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