Method for realizing stepped doping concentration distribution by multi-energy ion implantation

Abstract

The invention discloses a method for realizing stepped doping concentration distribution by multi-energy ion implantation. The method comprises: a normalization method is utilized to calculate a relation factor of a single-energy ion implantation concentration descent rate and departing from an average projection range as well as a relation factor for selecting single-energy ion implantation is determined according to needed doping concentration distribution and the employed energy combination number, thereby determining energy combination; a back-stepping method for an experience factor and an empirical equation is utilized to determine a dosage value of single energy in the energy combination as well as box type doping concentration distribution of all high and low concentration doping segments is formed by a dosage fine tuning mode; a design of masking sacrificial layer is introduced into the box type doping concentration distribution to realize a steep change at an inflection point of stepped doping concentration distribution, so that trailing before the box type implantation distribution is eliminated and steep box type doping concentration distribution at the inflection point is formed; and masking sacrificial layers of box type doping concentration distribution of all the doping segments are removed and then the box type doping concentration distribution of the high andlow concentration doping segments is linearly superposed, so that stepped doping concentration distribution is formed; and fine tuning is carried out on dosages at stepping positions of all the doping segments to complete the steep design of the stepped doping concentration distribution.

Description

technical field [0001] The invention relates to the field of ion implantation design, in particular to a method for realizing stepped doping concentration distribution by multi-energy ion implantation. Background technique [0002] Ion implantation is a key process for the preparation of semiconductor devices, especially for SiC materials, and ion implantation is the core process technology for forming SiC device doping. As a new generation of wide-bandgap semiconductor material, silicon carbide (SiC) has the advantages of high thermal conductivity, high electron saturation velocity, and high breakdown voltage. It is an ideal material for semiconductor devices such as high temperature, high power, and high frequency. However, due to the small diffusion system of impurities in SiC, ion implantation doping is the only feasible method other than epitaxial doping. A good solution to the ion implantation process will help the further promotion and application of SiC materials and...

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Problems solved by technology

[0007] However, these design methods have the following defects: first, there is a lot of randomness in the determination of the energy and dose combination of multiple injections, especially the determination of the energy combination. There is no definite parameter design method, which is all based on experience. This not only has poor repeatability, but also wastes energy, and cannot quickly and effectively obtain a precisely controlled, arbitrary doping concentration distribution; second, ion implantation is a key process that affects device performance, and some devices have very strict requirements on the doping concentration distribution of implanted ions. High, if the process design is inaccurate, it will lead to complex process, rework, or may lead to the decline of device performance; third, for similar step-like doping concentration distribution, the design of the steepness at the inflection point is very critical, such as the junction of SiC devices The terminal (JTE) is very sensitive to concentration. If the concentration distribution in the design area has a long tail, it will directly affect the breakdown characteristics of the device.

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