A high-robust fast-recovery super-junction power semiconductor transistor and its preparation method

Abstract

A high-robust fast-recovery super-junction power semiconductor transistor and a preparation method thereof. The transistor includes an N-type drain, an N-type epitaxial layer is arranged on the N-type drain, and first and second strip-shaped P-type body regions and a first P-type body region are arranged, and at least 2 A trench gate, a heavily doped N-type source and a second P-type body region, a first field oxide layer is provided on the upper end of the trench gate, and a heavily doped N-type source is located on the upper part of the first P-type body region And confined between the trench gates, the second P-type body region is located under the heavily doped N-type source and connected to the source metal layer through the first contact metal. The method is to grow an N-type epitaxial layer on the substrate, etch a deep trench, make the first and second strip-shaped P-type body regions, and then make the trench gate, the first P-type body region, and the heavily doped N-type source , and then deposit aluminum to form the source metal layer and the first contact metal, and finally make the N-type drain. The invention can effectively improve the reverse recovery characteristic of the body diode and improve the reliability of the device.

Description

technical field [0001] The invention mainly relates to the technical field of power semiconductor devices, in particular to a high-robust fast-recovery super-junction power semiconductor transistor and a preparation method thereof, which are especially suitable for mobile phone chargers and various power supply systems. Background technique [0002] Metal oxide semiconductor field effect transistors (Metal Oxide Semiconductor Field Effect Transistor, MOSFET) are widely used in the field of power semiconductor devices. In order to broaden its application in the high-voltage field, it is necessary to improve its withstand voltage capability, so it is necessary to reduce the doping concentration of the MOSFET drift region, or increase its thickness, but this will bring the disadvantage of high on-resistance. In order to improve the above shortcomings, people have proposed a super junction (Super Junction) MOSFET, which uses alternating p-columns and n-columns to form the drift ...

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Problems solved by technology

However, when the body diode of the traditional trench super MOSFET works in the reverse recovery state, a large reverse recovery current will generate a built-in potential when flowing through the pn junction formed by the P-type body region and the N-type source region, which is easy to Lead to the turn-on of the parasitic triode, damage the transistor

In order to suppress the turn-on of the parasitic triode, it is necessary to perform high-concentration P-type injection on the upper part of the p-column to form an ohmic contact, but this will increase the hole injection efficiency of the body diode during forward conduction, thereby storing a large amount of carriers. It increases the storage carriers that need to be extracted during the reverse recovery process, the reverse recovery process takes a long time, and increases the loss of reverse recovery, which needs further improvement

In addition, during the manufacturing process, the traditional super junction trench structure is extremely vulnerable, for example, in the subsequent thermal process, the diffusion of impurity ions between the p-column and n-column and the diffusion of impurity ions in the p-column and n-column These factors will cause the unbalanced charge distribution in the super junction trench MOSFET device, which will cause great damage to the performance of the super junction trench MOSFET device

Therefore, the pitch of the p-columns in the structure of the super-junction trench MOSFET device should be as small as possible in theory, so as to better realize the charge compensation. However, in the actual manufacturing process, the pitch of the p-columns is limited, so that this part of the area cannot be obtained more effectively. land use

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