Patent US4404658A successfully refreshed from Google Patents.
US4404658A
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Mesa bipolar memory cell and method of fabrication
Assignee: Harris Corp
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Filing: 1981-05-21
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Granted: 1983-09-13
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Expires: 2001-05-21
Abstract
Abstract A memory cell having two mesa bipolar transistors separated by a valley in which two doped polycrystalline load resistors are formed. Doped polycrystalline conductors connect the resistors to a respective backside metallic collector contact which is between a support structure and a transistor and to a respective base. The cell is fabricated by removing a substrate upon which was formed an epitaxial layer and top support, applying a backside metallic layer, forming a bottom support, removing the top support, etching the epitaxial layer to form mesas, etching the backside metal to form discrete contacts, and forming multi-level resistors and conductors in the valley between the mesa transistors separated by insulative material.
Inventors
- 👤 Kenneth A. Ports
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 13:14
CPC Classifications
H; H10; H10D; H10D1/00; H10D1/40; H10D1/47; H10P; H10P90/00; H10P90/19; H10P90/1904; H10P90/1906; H10W; H10W10/00; H10W10/01; H10W10/021; H10W10/061; H10W10/10; H10W10/181; H10W10/20; H10W20/00; H10W20/01; H10W20/021; H10W20/40; H10W10/011; H10W10/014; H10W10/17
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
164 words
In a memory cell having a pair of bipolar transistors cross-coupled by their bases and collectors and an individual load resistor connected to the collectors of each transistor, the improvement comprising: support means; first and second metallic collector contact on said support means; first mesa bipolar transistor on said first collector contact and second mesa bipolar transistor on said second collector contact, said first and second mesa bipolar transistors being separated by a valley and each having a collector, base and emitter; a first resistor in said valley, connected at one end thereof to the collector of said first transistor and the base of said second transistor through apertures in an insulating material; a second resistor in said valley, connected at one end thereof to the collector of said second transistor and the base of said first transistor through apertures on an insulating material; said first and second resistors being connected at their other ends through an aperture in an insulating material there between.
Claim 2
Dependent Claim
164 words
In a memory cell having a pair of bipolar transistors cross-coupled by their bases and collectors and an individual load resistor connected to the collectors of each transistor, the improvement comprising: support means; first and second metallic collector contact on said support means; first mesa bipolar transistor on said first collector contact and second mesa bipolar transistor on said second collector contact, said first and second mesa bipolar transistors being separated by a valley and each having a collector, base and emitter; a first resistor in said valley, connected at one end thereof to the collector of said first transistor and the base of said second transistor through apertures in an insulating material; a second resistor in said valley, connected at one end thereof to the collector of said second transistor and the base of said first transistor through apertures on an insulating material; said first and second resistors being connected at their other ends through an aperture in an insulating material there between.
Claim 3
Dependent Claim
30 words
The memory cell according to claim 1 wherein said first and second resistors are doped polycrystalline resistors and are connected to said first and second transistors by doped polycrystalline conductors.
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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) | 1986-09-12 | 1987-03-14 | 1987-09-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-09-12 | 1991-03-14 | 1991-09-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-09-12 | 1995-03-14 | 1995-09-13 | $7700.00 | Window Closed / Lapsed |