US5693548A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for making T-gate of field effect transistor
Assignee: Pendragon Electronics and Telecommunications Research LLC
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Filing: 1994-12-19
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Granted: 1997-12-02
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Expires: 2014-12-19
Abstract
Abstract A method for making a T-shaped gate of a field effect transistor is disclosed. The method includes the steps of sequentially depositing first and second photoresist layers on a semiconductor substrate and performing an exposure using electron beams having different energy, one of the electron beams having a first energy to lightly expose only the second photoresist layer and the other of the electron beams having a second energy to lightly expose all of the first and second layers. The invention reduces gate resistance and parasitic capacitance of the T-shaped gate.
Inventors
- 👤 Jin-Hee Lee
- 👤 Sang-Soo Choi
- 👤 Hyung-Sup Youn
- 👤 Chul-Soon Park
- 👤 Hyung-Jun Yoo
- 👤 Hyung-Moo Park
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 02:01
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/01; H10D30/015; G; G03; G03F; G03F7/00; G03F7/004; G03F7/09; G03F7/095; G03F7/20; G03F7/2051; G03F7/2059; H10D64/00; H10D64/01; H10D64/012; H10D64/0124; H10D64/0125; H10P; H10P76/00; H10P76/20; H10P76/204; H10P76/2045; Y; Y10; Y10S; Y10S148/00; Y10S148/10; Y10S148/14; Y10S438/00; Y10S438/942; Y10S438/948; Y10S438/949
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
130 words
A method for making a T-shaped gate of a field effect transistor, the method comprising the steps: sequentially depositing first and second photoresist layers on a semiconductor substrate to form multiple layers comprising the first layer disposed on top of the semiconductor substrate and the second layer disposed on top of the first layer; performing only a single electron beam exposure of portions of the first and second layers of the multiple layers using electron beams having different energy levels with one of the energy levels exposing only a portion of the second layer and another of the energy levels exposing another portion of the first and second layers; and wherein the electron beams are spatially separated from each other during imaging of the electron beams upon the second layer.
Claim 2
Independent Claim
130 words
A method for making a T-shaped gate of a field effect transistor, the method comprising the steps: sequentially depositing first and second photoresist layers on a semiconductor substrate to form multiple layers comprising the first layer disposed on top of the semiconductor substrate and the second layer disposed on top of the first layer; performing only a single electron beam exposure of portions of the first and second layers of the multiple layers using electron beams having different energy levels with one of the energy levels exposing only a portion of the second layer and another of the energy levels exposing another portion of the first and second layers; and wherein the electron beams are spatially separated from each other during imaging of the electron beams upon the second layer.
Claim 3
Dependent Claim
82 words
A method in accordance with claim 1 wherein: the T-shaped gate has a base extending upward from the substrate and a top extending parallel to the substrate with the top having sides which are sloped outward from a top surface of the top to a bottom surface of the top which is longer than the top surface of the top; and the exposing of the first and second layers with the electron beams of different energy produces the sides which are sloped.
Claim 4
Dependent Claim
19 words
A method in accordance with claim 1 wherein: the first photoresist layer has a thickness of about 2000 Å.
Claim 5
Dependent Claim
19 words
A method in accordance with claim 2 wherein: the first photoresist layer has a thickness of about 2000 Å.
Claim 6
Independent Claim
185 words
A method for making a T-shaped gate of a field effect transistor, the method comprising the steps sequentially forming a two-dimensional election gas layer, an AlGaAs layer and a cap layer on a semiconductor substrate; forming an ohmic layer on the cap layer; sequentially depositing first and second photoresist layers over a semiconductor substrate to form multiple layers comprising the first layer disposed on top of the semiconductor substrate and the second layer disposed on top of the first layer; performing only a single electron beam exposure of portions of the first and second layers of the multiple layers using electron beams having different energy levels with one of the energy levels exposing only a portion of the second layer and another of the energy levels exposing another portion of the first and second layers with the electron beams being spatially separated from each other during imaging of the electron beams upon the second layer; developing the first and second photoresist layers to form a T-shaped pattern; coating a metal gate layer; and removing the first and second photoresist layers to form the T-shaped gate.
Claim 7
Independent Claim
185 words
A method for making a T-shaped gate of a field effect transistor, the method comprising the steps sequentially forming a two-dimensional election gas layer, an AlGaAs layer and a cap layer on a semiconductor substrate; forming an ohmic layer on the cap layer; sequentially depositing first and second photoresist layers over a semiconductor substrate to form multiple layers comprising the first layer disposed on top of the semiconductor substrate and the second layer disposed on top of the first layer; performing only a single electron beam exposure of portions of the first and second layers of the multiple layers using electron beams having different energy levels with one of the energy levels exposing only a portion of the second layer and another of the energy levels exposing another portion of the first and second layers with the electron beams being spatially separated from each other during imaging of the electron beams upon the second layer; developing the first and second photoresist layers to form a T-shaped pattern; coating a metal gate layer; and removing the first and second photoresist layers to form the T-shaped gate.
Claim 8
Dependent Claim
82 words
A method in accordance with claim 5 wherein: the T-shaped gate has a base extending upward from the substrate and a top extending parallel to the substrate with the top having sides which are sloped outward from a top surface of the top to a bottom surface of the top which is longer than the top surface of the top; and the exposing of the first and second layers with the electron beams of different energy produces the sides which are sloped.
Claim 9
Dependent Claim
19 words
A method in accordance with claim 5 wherein: the first photoresist layer has a thickness of about 2000 Å.
Claim 10
Dependent Claim
19 words
A method in accordance with claim 6 wherein: the first photoresist layer has a thickness of about 2000 Å.
Claim 11
Dependent Claim
21 words
A method in accordance with claim 1 wherein: a portion of the multiple layers is not exposed to either electron beams.
Claim 12
Dependent Claim
23 words
A method in accordance with claim 1 wherein: the electron beams of energy levels respectively lightly expose the first and second photoresist layers.
Claim 13
Dependent Claim
21 words
A method in accordance with claim 2 wherein: a portion of the multiple layers is not exposed to either electron beams.
Claim 14
Dependent Claim
23 words
A method in accordance with claim 2 wherein: the electron beams of energy levels respectively lightly expose the first and second photoresist layers.
Claim 15
Dependent Claim
21 words
A method in accordance with claim 3 wherein: a portion of the multiple layers is not exposed to either electron beams.
Claim 16
Dependent Claim
23 words
A method in accordance with claim 3 wherein: the electron beams of energy levels respectively lightly expose the first and second photoresist layers.
Claim 17
Dependent Claim
21 words
A method in accordance with claim 4 wherein: a portion of the multiple layers is not exposed to either electron beams.
Claim 18
Dependent Claim
23 words
A method in accordance with claim 4 wherein: the electron beams of energy levels respectively lightly expose the first and second photoresist layers.
Claim 19
Dependent Claim
21 words
A method in accordance with claim 5 wherein: a portion of the multiple layers is not exposed to either electron beams.
Claim 20
Dependent Claim
23 words
A method in accordance with claim 5 wherein: the electron beams of energy levels respectively lightly expose the first and second photoresist layers.
Claim 21
Dependent Claim
21 words
A method in accordance with claim 6 wherein: a portion of the multiple layers is not exposed to either electron beams.
Claim 22
Dependent Claim
23 words
A method in accordance with claim 6 wherein: the electron beams of energy levels respectively lightly expose the first and second photoresist layers.
Claim 23
Dependent Claim
21 words
A method in accordance with claim 7 wherein: a portion of the multiple layers is not exposed to either electron beams.
Claim 24
Dependent Claim
23 words
A method in accordance with claim 7 wherein: the electron beams of energy levels respectively lightly expose the first and second photoresist layers.
Claim 25
Dependent Claim
21 words
A method in accordance with claim 8 wherein: a portion of the multiple layers is not exposed to either electron beams.
Claim 26
Dependent Claim
23 words
A method in accordance with claim 8 wherein: the electron beams of energy levels respectively lightly expose the first and second photoresist layers.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-12-01 | 2001-06-02 | 2001-12-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-12-01 | 2005-06-02 | 2005-12-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-12-01 | 2009-06-02 | 2009-12-02 | $7700.00 | Window Closed / Lapsed |