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US 5,444,008 AGranted
High-performance punchthrough implant method for MOS/VLSI
AssigneeVLSI Technology, Inc.
InventorsYu P. Han, Samuel J. S. Nagalingam
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Abstract
A method of making high performance MOSFETs uses image reversal lithography to make punchthrough implants.
Claims11
A method of making a high performance metal-oxide-semiconductor field-effect transistor device comprising the steps of:
- a) providing a p-doped silicon substrate for the device;
- b) forming a patterned layer of silicon dioxide on the surface of said substrate to serve as gate oxide;
- c) placing a positive photoresist layer on the surface of the device
- d) by means of image reversal photolithography opening an aperture in said photoresist, said aperture defining a gate region, wherein the step of opening the aperture comprises the steps of:
- (i) placing a reverse gate mask over said photoresist;
- (ii) exposing said photoresist to UV light;
- (iii) neutralizing the photoproducts in the exposed region of said photoresist;
- (iv) flooding entirely said photoresist with UV light;
- and
- (v) developing said photoresist to remove the portion of the photoresist exposed in step (iv);
- e) implanting a p-type dopant in said substrate below said oxide layer in said gate region;
- and
- f) removing residual photoresist.
10 more elements
A method of making a high performance metal-oxide-semiconductor field-effect transistor device comprising the steps of:
- a) providing a n-doped silicon substrate for the device;
- b) forming a patterned layer of silicon dioxide on the surface of said substrate to serve as gate oxide;
- c) placing a positive photoresist layer on the surface of the device;
- d) by means of image reversal photolithography opening an aperture in said photoresist, said aperture defining a gate region, wherein the step of opening the aperture comprising the steps of:
- (i) placing a reverse gate mask over said photoresist;
- (ii) exposing said photoresist to UV light;
- (iii) neutralizing the photoproducts in the exposed region of said photoresist;
- (iv) flooding entirely said photoresist with UV light;
- and
- (v) developing said photoresist to remove the portion of the photoresist exposed in step (iv);
- and
- e) implanting a n-type dopant in said substrate below said oxide layer in said gate region;
- f) removing residual photoresist.
10 more elements
Dependencies are inferred from the claim text.