Methods for manufacturing superjunction structure and superjunction semiconductor device

Abstract

The invention discloses methods for manufacturing a superjunction structure and a superjunction semiconductor device. A novel semiconductor superjunction and a superjunction device are formed by the key process steps of etching a trench, performing ion implantation at a small inclination angle, filling an insulating dielectric and planarizing, forming an active layer and an electrode and the like. Compared with the prior art, the methods have the advantages that: firstly, a method of forming the superjunction by using a plurality of epitaxy processes and a plurality of implantation processes is prevented from being used; secondly, the bottom of a trench gate can be guaranteed to be flush with or slightly lower than the lower boundary of a body region, so that withstand voltage of the device is improved, and gate-source capacitance and gate-drain capacitance are reduced; thirdly, since the depth of the trench is reduced, the process difficulty of the small-angle implantation is reduced, the process tolerance is increased, and the dielectric in the extended trench is easier to fill and planarize; fourthly, a complex mask is not required, so that the influence of small-angle implantation on a trench region is avoided; and fifthly, the adverse effects of the filling and the planarizing of the extended trench and the manufacturing and the planarizing of the trench gate on the formed body region, body contact region and source region are avoided.

Description

[0001] technical field [0002] The invention relates to a manufacturing method of a super junction structure and a manufacturing method of a super junction semiconductor device. Background technique [0003] Power MOSFET is a multi-subconduction device, which has many advantages such as high input impedance, high frequency, and positive temperature coefficient of on-resistance. These advantages make it widely used in the field of power electronics, greatly improving the efficiency of electronic systems. [0004] The high voltage resistance of the device requires a long drift region and a low doping concentration in the drift region. However, as the length of the drift region increases and the doping concentration decreases, the on-resistance ( ) of the device increases, the on-state power consumption increases, and the on-resistance of the device R on There is the following relationship with the breakdown voltage BV: ie . [0005] With the advancement of the manufacturi...

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Problems solved by technology

However, after the active region (including body region, body contact region and source region) is formed, the process steps of small-tilt ion implantation, oxide filling and expanding trenches, and trench gate formation have the following main disadvantages: (1) process It is difficult to accurately control the height of silicon dioxide in the extended trench

On the one hand, the trench gate must span the body region in the vertical direction (that is, the upper surface of the oxide in the extended trench cannot be higher than the lower surface of the body region); on the other hand, the longer the trench gate overlaps with the drift region, the greater the gate-drain capacitance. The larger the is, and the withstand voltage of the device decreases with the decrease of the height of silicon dioxide in the extended trench, so it is necessary to accurately control the height of silicon dioxide in the extended trench to ensure the electrical performance of the device; (2) the higher the withstand voltage of the device, The deeper the extended trench, the more difficult the implantation, and the smaller the process tolerance; (3) In order to ensure that the ions implanted at a small inclination angle cover all areas below the active layer on both sides of the trench, and do not cover the active layer on both sides of the trench. layer, the mask for ion implantation is difficult to make, which increases the complexity of the process

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