US3573573A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Memory cell with buried load impedances
Assignee: International Business Machines Corp
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Filing: 1968-12-23
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Granted: 1971-04-06
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Expires: 1988-12-23
Abstract
Abstract This specification describes semiconductor storage cells for use in monolithic memories. These cells each have two planar transistors formed on a single surface of a monolithic chip. The planar transistors are coupled together to form a bistable circuit and are supplied power from a voltage distribution layer of the chip under the planar transistors so that the load elements for the storage cells are formed vertically through the monolithic chip between the voltage distribution layer and the planar transistors.
Inventors
- 👤 Richard L Moore
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 23:37
CPC Classifications
H; H10; H10D; H10D1/00; H10D1/40; H10D1/43; H10D62/00; H10D62/10; H10D62/13; H10D62/137; H10D84/00; H10D84/60; H10D84/611; H10D84/613; H10D99/00; Y; Y10; Y10S; Y10S148/00; Y10S148/037; Y10S148/085; Y10S148/145
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
126 words
A monolithic storage cell comprising: a. a silicon substrate; b. an epitaxially grown layer on the substrate forming a rectifying junction between the substrate and the epitaxially grown layer; c. two low-impedance subcollector diffusions in the epitaxially grown layer; d. base diffusions in the surface of the epitaxially grown layer over the subcollector diffusions; e. emitter diffusions in the base diffusions; f. means electrically coupling each of the subcollector diffusions to the base diffusions over the other subcollector diffusion to form two crosscoupled transistors; g. means electrically connecting the emitter diffusions to addressing means for the storage cell; and h. means for supplying collector potential to the silicon substrate so that collector load impedances for the transistors are formed between the substrate and the subcollector diffusions.
Claim 2
Dependent Claim
126 words
A monolithic storage cell comprising: a. a silicon substrate; b. an epitaxially grown layer on the substrate forming a rectifying junction between the substrate and the epitaxially grown layer; c. two low-impedance subcollector diffusions in the epitaxially grown layer; d. base diffusions in the surface of the epitaxially grown layer over the subcollector diffusions; e. emitter diffusions in the base diffusions; f. means electrically coupling each of the subcollector diffusions to the base diffusions over the other subcollector diffusion to form two crosscoupled transistors; g. means electrically connecting the emitter diffusions to addressing means for the storage cell; and h. means for supplying collector potential to the silicon substrate so that collector load impedances for the transistors are formed between the substrate and the subcollector diffusions.
Claim 3
Dependent Claim
26 words
The storage cell of claim 1 wherein the substrate contains greater concentrations of doping impurities than the base diffusions to assure bistability of the storage cell.
Claim 4
Dependent Claim
16 words
The storage cell of claim 2 wherein there are two emitter diffusions in each base diffusion.
Claim 5
Dependent Claim
36 words
The storage cell of claim 3 including word line means coupled to one of the emitter diffusions in each base diffusion and separate bit line means coupled to the other emitter diffusion in each base diffusion.
Claim 6
Dependent Claim
39 words
The storage cell of claim 4 wherein the potential supplied between the work and bit line means and the silicon substrate is sufficient to heavily forward-bias only the collector load impedance for one of the crosscoupled transistors biased conductive.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-04-05 | 1974-10-05 | 1975-04-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-04-05 | 1978-10-05 | 1979-04-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-04-05 | 1982-10-05 | 1983-04-06 | $7700.00 | Window Closed / Lapsed |