Configuration and manufacturing method of low-resistance gate structures for semiconductor devices and circuits
OwnerIshiang Shih, Chunong Qiu +2inventors
InventorsIshiang Shih, Chunong Qiu, Cindy X. Qiu, Yi-Chi Shih
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Abstract
The present invention provides methods for fabricating devices with low resistance structures involving a lift-off process. A radiation blocking layer is introduced between two resist layers in order to prevent intermixing of the photoresists. Cavities suitable for the formation of low resistance T-gates or L-gates can be obtained by a first exposure, developing, selective etching of blocking layer and a second exposure and developing. In another embodiment, a low resistance gate structure with pillars to enhance mechanical stability or strength is provided.
Claims11
A process for fabricating a low-resistance gate structure, comprising the steps of
- (a) providing a semiconductor layer structure having a semiconductor structure surface;
- (b) forming a first resist layer having a first resist thickness on top of said semiconductor structure surface;
- (c) forming a radiation blocking layer having a radiation blocking layer thickness on top of said first resist layer;
- (d) forming a second resist layer having a second resist thickness on top of said radiation blocking layer to obtain a bi-layer resist structure sandwiching said radiation blocking layer;
- (e) exposing selectively a first region of said bi-layer resist structure to a first radiation beam having a first radiation beam length and a first radiation beam width and developing said bi-layer resist structure to form a second cavity having a second cavity length and a second central axis in said second resist layer, causing exposure of a portion of said radiation blocking layer,
- (f) etching said exposed portion of radiation blocking layer not covered by said second resist to form a radiation blocking layer cavity;
- (g) exposing selectively a second region of said bi-layer resist structure to a second radiation beam having a second radiation beam length and second radiation beam width and developing said bi-layer resist structure to form a first cavity having a first cavity length and a first central axis in said first resist layer and an enlarged second cavity in said second resist layer, said second radiation beam length is substantially greater than said first radiation beam length, causing an increase in said second cavity length so that length of said enlarged second cavity is substantially larger than said first cavity length after step (g);
- (h) etching exposed radiation blocking layer caused by said increase in said length of said enlarged second cavity to form an enlarged radiation blocking layer cavity;
- wherein said first cavity, said enlarged radiation blocking layer cavity and said enlarged second cavity combined to form a gate opening;
- (i) depositing an electrically conductive gate material assembly to substantially fill said-gate opening;
- and
- (j) removing the first resist layer, radiation blocking layer, second resist layer and a portion of electrically conductive gate material assembly on said second resist layer to complete the fabrication of a free-standing low resistance structure having a stem portion with a stem height defined by said first resist thickness and a stem length, a head portion with a head height and a head length, a first overhang space between said stem and a first side of said head, and a second overhang space between said stem and a second side of said head.
Dependencies are inferred from the claim text.