Shield gate trench MOSFET and manufacture method

Abstract

The invention discloses a shield gate trench MOSFET. The gate trench includes a top trench and a bottom trench. A polysilicon gate is formed on both sides of the top trench. Source polysilicon is located in the middle of the gate trench and extends longitudinally through the entire gate trench. Channel regions are formed on semiconductor substrate surfaces between gate structures and source regions are formed on the surfaces of the channel regions. A polysilicon gate on one side of the top trench is connected to a gate formed by a front metal layer. A polysilicon gate on the other side of the top trench and the source regions are connected to a source through a second contact hole to form a structure for reducing the gate-drain capacitance of a device. The second contact hole reduces the distance between the gate trenches and reduces the on-resistance of the device and form an on-resistance compensation structure. The invention also discloses a method for manufacturing the shield gate trench MOSFET. The shield gate trench MOSFET can reduce the gate-drain capacitance, can increase the switching speed of the device, and can reduce the size of a unit device and improve an integration level.

Description

technical field [0001] The invention relates to the field of semiconductor integrated circuit manufacturing, in particular to a shield gate (Shield Gate Trench, SGT) trench MOSFET; the invention also relates to a manufacturing method of the shield gate trench MOSFET. Background technique [0002] Such as Figure 1A to Figure 1I Shown is a schematic diagram of the device structure in each step of the existing method; the manufacturing method of the existing shielded gate trench MOSFET includes the following steps: [0003] Step 1, such as Figure 1A As shown, a semiconductor substrate such as a silicon substrate 101 is provided, and a formation region of a gate trench is defined by a photolithography process, and the gate trench includes a plurality of gate trenches. [0004] The step of forming a hard mask layer 201 on the surface of the semiconductor substrate 101 is included before the photolithography process, and the hard mask layer 201 is etched and formed after the fo...

AI Technical Summary

Problems solved by technology

[0020] like Figure 1I The existing shielded gate trench MOSFET shown has the advantage of low on-resistance. When the device is turned on, all channels are turned on, and its gate-to-drain capacitance is large, which limits the use of the device in high switching speed applications.

How to reduce the gate charge of the device to reduce the gate-to-drain capacitance becomes a challenge in process and design

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