Trench-gate semiconductor devices, and their manufacture
First Claim
1. A trench-gate semiconductor device comprising a gate trench that extends into a semiconductor body from a body surface, through a channel-accommodating region between a source region and an underlying drain region, wherein the gate, present in the trench, is capacitively coupled to the channel-accommodating region by an intermediate gate dielectric layer at a wall of the trench, the gate comprises a part of semiconductor material adjacent to the gate dielectric layer adjacent to the channel-accommodating region, the gate protrudes upwardly from the trench in the form of a silicide upstanding part which is of a metal silicide material between its top and sidewalls above the level of the body surface, and the gate dielectric layer at least adjacent to the channel-accommodating region is separated from the metal silicide material by at least the semiconductor part of the gate and by the protrusion of the silicide part upward above the level of the body surface.
4 Assignments
0 Petitions
Accused Products
Abstract
The trench-gate (11) of, for example, a cellular power MOSFET comprises doped poly-Si or other semiconductor material (11a) adjacent to the gate dielectric layer (17) adjacent to the channel-accommodating region (15) of the device. The gate (11) also comprises a sizeable silicide part (11b) that reduces gate resistance. This silicide part (11b) protrudes upwardly from the trench (20) over a distance (z) typically larger than the width (w) of the trench (20), so forming an upstanding part (11b) of a metal silicide material between its top and sidewalls above the level of the body surface (10a). The gate dielectric layer (17) at least adjacent to the channel-accommodating region (15) is protected from the metal silicide by at least the semiconductor part (11a) of the gate and by the protrusion (z) of the silicide part (11b) upwardly above the level of the body surface (10a). The height (z) of this silicide protrusion can be defined by a layer thickness of a mask (51,52; 510,520) with a window (51a, 510a) at which the trench (20) is etched. The silicide material may be deposited or grown in situ by alloying.
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Citations
16 Claims
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1. A trench-gate semiconductor device comprising a gate trench that extends into a semiconductor body from a body surface, through a channel-accommodating region between a source region and an underlying drain region, wherein
the gate, present in the trench, is capacitively coupled to the channel-accommodating region by an intermediate gate dielectric layer at a wall of the trench, the gate comprises a part of semiconductor material adjacent to the gate dielectric layer adjacent to the channel-accommodating region, the gate protrudes upwardly from the trench in the form of a silicide upstanding part which is of a metal silicide material between its top and sidewalls above the level of the body surface, and the gate dielectric layer at least adjacent to the channel-accommodating region is separated from the metal silicide material by at least the semiconductor part of the gate and by the protrusion of the silicide part upward above the level of the body surface.
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7. A method of manufacturing a trench-gate semiconductor device having source and drain regions which are separated by a channel-accommodating region adjacent to the trench-gate, including the following sequence of steps:
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(a) providing at a surface of a semiconductor body a masking pattern having therein a window that is used for self-aligning a gate trench and parts of the gate formed in the subsequent steps (b) to (d);
(b) etching the trench into the semiconductor body within the window, and forming a dielectric layer at the walls of the trench to provide a gate dielectric for capacitively coupling the gate to the channel-accommodating region, (c) depositing and then etching back semiconductor gate material to provide a semiconductor gate part on the dielectric layer in the trench without protruding above the masking pattern at the window, and (d) then providing at the window a thickness of metal silicide material at the top of the semiconductor gate part sufficient to form a silicide upstanding part of the gate having a top and sidewalls that protrude upward above the level of the body surface, the gate dielectric at least adjacent to the channel-accommodating region being protected from the metal silicide material by at least the semiconductor part of the gate and by the protrusion of its silicide part above the level of the body surface. - View Dependent Claims (8, 9, 10, 14, 15, 16)
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11. A method of manufacturing a trench-gate semiconductor device having source and drain regions which are separated by a channel-accommodating region adjacent to the trench-gate, including the following sequence of steps:
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(a) providing at a surface of a semiconductor body a masking pattern comprising upper and lower layers through which a window extends at an area of the body where the trench-gate is to be provided, (b) etching a trench for the gate into the body at the window, and forming a gate dielectric layer at the walls of the trench in the semiconductor body, (c) providing silicon gate material in the trench and in the window, and then removing the upper layer of the masking pattern such that the silicon gate material has an upstanding upper part that protrudes above the adjacent surface of the lower layer of the masking pattern, (d) depositing a silicide-forming metal over the silicon gate material and over the lower layer of the masking pattern, and heating at least the metal to grow a metal silicide into the silicon gate material from the top and side-walls of the upstanding upper part, and (e) removing the un-silicided metal so as to leave a partially-silicided trench-gate protruding from the semiconductor body. - View Dependent Claims (12, 13)
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Specification