Method for the fabrication of electrostatic microswitches
AssigneeUnited Microelectronics Corp.
InventorsZhijian Li, Xiqing Sun, Litian Liu, Xinyu Zheng
Life of this patent
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Abstract
A method for fabricating an electrostatic microswitch has the steps of depositing a silicon nitride layer over a silicon substrate with an opening therethrough to expose the planned sacrificial layer region; oxidation to form a silicon dioxide sacrificial layer; phosphorus ion implantation into the sacrificial layer; forming a phosphorus-doped polysilicon microbeam of the microswitch and its electrode contacts; lateral etching all of the silicon dioxide sacrificial layer in buffered hydrofluoric acid to form an air gap between the microbeam and the substrate; rinsing the structure in DI water, and then in methanol; and drying the structure by a warm nitrogen flow.
Claims8
A method for fabricating an electrostatic microswitch comprising the steps of:
- (a) providing a silicon substrate having a certain conductivity type;
- (b) depositing a silicon nitride layer over said silicon substrate with an opening therethrough to expose a portion of said silicon substrate;
- (c) oxidizing said exposed silicon substrate surface to form a silicon dioxide sacrificial layer;
- (d) ion implantation of a dopant into said silicon dioxide sacrificial layer to increase its lateral etch rate;
- (e) depositing a layer of phosphorus-doped polysilicon over said silicon nitride and said silicon dioxide sacrificial layer;
- (f) patterning said phosphorus-doped polysilicon layer by lithography and etching to form a polysilicon microbeam of said electrostatic microswitch;
- (g) forming at least one electrode contact on said polysilicon microbeam;
- (h) forming a resist mask over said electrode contact to protect the electrode contact pattern from etching during a lateral etching step;
- (i) laterally etching all of said silicon dioxide sacrificial layer in buffered hydrofluoric acid to form an air gap between said polysilicon microbeam and said silicon substrate;
- (j) rinsing said microswitch structure in DI water, and then in methanol;
- and
- (k) drying said microswitch structure by a warm nitrogen flow.
Dependencies are inferred from the claim text.