US4272775A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Laser trim protection process and structure
Assignee: National Semiconductor Corp
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Filing: 1979-06-04
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Granted: 1981-06-09
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Expires: 1999-06-04
Abstract
Abstract An element of an integrated circuit, such as an ion implanted region or a metal layer, may be laser trimmed without exposing P-N junctions or other circuit elements not to be trimmed to damage by the laser through use of the present protection process and structure. In the process, an oxide through which the laser trimming is carried out is formed over a selected portion of the circuit to be trimmed by the laser. A bare layer of a metal reflective to the laser radiant energy beam, such as aluminum, gold or silver, is formed surrounding the selected portion of the circuit. The selected portion of the integrated circuit is then trimmed with the laser. The oxide promotes trimming in the selected area by absorbing the laser radiant energy beam. The bare metal layer protects the portion of the integrated circuit underlying it by reflecting most of its energy.
Inventors
- 👤 James B. Compton
- 👤 Robert A. Cometta
- 👤 Daniel D. Culmer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 13:00
CPC Classifications
H; H10; H10P; H10P34/00; H10P34/40; H10P34/42; H10P76/00; H10P76/40
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
148 words
An integrated circuit structure, which comprises: (a) a semiconductor substrate of a first conductivity type, (b) a first region of second conductivity type in said semiconductor substrate and forming a P-N junction therewith, (c) a second region contiguous with said first region and including a circuit element to be trimmed by use of a radiant energy beam, (d) a first oxide on said semiconductor substrate overlying said second region including said circuit element, (e) a layer of a metal reflective to the radiant energy beam on said first oxide at least the P-N junction formed between said first region and said semiconductor substrate, and (f) a second oxide layer on said reflective metal layer, said second oxide layer having an opening which exposes said reflective metal layer over the P-N junction at the surface of said semiconductor substrate where said P-N junction is contiguous with said second region.
Claim 2
Dependent Claim
148 words
An integrated circuit structure, which comprises: (a) a semiconductor substrate of a first conductivity type, (b) a first region of second conductivity type in said semiconductor substrate and forming a P-N junction therewith, (c) a second region contiguous with said first region and including a circuit element to be trimmed by use of a radiant energy beam, (d) a first oxide on said semiconductor substrate overlying said second region including said circuit element, (e) a layer of a metal reflective to the radiant energy beam on said first oxide at least the P-N junction formed between said first region and said semiconductor substrate, and (f) a second oxide layer on said reflective metal layer, said second oxide layer having an opening which exposes said reflective metal layer over the P-N junction at the surface of said semiconductor substrate where said P-N junction is contiguous with said second region.
Claim 3
Dependent Claim
32 words
The integrated circuit structure of claim 1 in which the circuit element to be trimmed is a portion of the semiconductor body forming a P-N junction with its immediately contiguous semiconductor material.
Claim 4
Dependent Claim
30 words
The integrated circuit structure of claim 1 in which the semiconductor substrate is silicon, the oxide is silicon oxide, and the metal is aluminum, gold, silver, or an alloy thereof.
Claim 5
Dependent Claim
104 words
An integrated circuit structure, which comprises: (a) a semiconductor substrate of a first conduitivity type, (b) a first region of a second conductivity type in said semiconductor substrate and forming a P-N junction therewith, (c) a circuit element to be trimmed by use of a radiant energy beam and contiguous with said first region, (d) an oxide layer on said semiconductor substrate overlying said circuit element and said first region, and (e) a bare layer of a metal reflective to the radiant energy beam on said oxide layer, overlying at least the P-N junction, and being free of ohmic contact to said first region.
Claim 6
Dependent Claim
104 words
An integrated circuit structure, which comprises: (a) a semiconductor substrate of a first conduitivity type, (b) a first region of a second conductivity type in said semiconductor substrate and forming a P-N junction therewith, (c) a circuit element to be trimmed by use of a radiant energy beam and contiguous with said first region, (d) an oxide layer on said semiconductor substrate overlying said circuit element and said first region, and (e) a bare layer of a metal reflective to the radiant energy beam on said oxide layer, overlying at least the P-N junction, and being free of ohmic contact to said first region.
Claim 7
Dependent Claim
32 words
The integrated circuit structure of claim 4 in which the circuit element to be trimmed is a portion of the semiconductor body forming a P-N junction with its immediately contiguous semiconductor material.
Claim 8
Dependent Claim
37 words
The integrated circuit structure of claim 4 in which the circuit element to be trimmed comprises a second metal layer over a second oxide layer, which second oxide layer separates the second metal layer and semiconductor substrate.
Claim 9
Dependent Claim
24 words
The integrated circuit structure of claim 4 in which the reflective metal layer and the second metal layer are aluminum or an aluminum-copper alloy.
Claim 10
Dependent Claim
30 words
The integrated circuit structure of claim 4 in which the semiconductor substrate is silicon, the oxide is silicon oxide, and the metal is aluminum, gold, silver or an alloy thereof.
Claim 11
Dependent Claim
26 words
The integrated circuit structure of claim 6 in which said second metal layer is aluminum, an aluminum copper alloy, or an alloy of silicon and chromium.
References Cited (Backward Citations)
US4172741A
Cited
US4190854A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-06-08 | 1984-12-08 | 1985-06-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-06-08 | 1988-12-08 | 1989-06-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-06-08 | 1992-12-08 | 1993-06-09 | $7700.00 | Window Closed / Lapsed |