Patent US4641173A successfully refreshed from Google Patents.
US4641173A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Integrated circuit load device
Assignee: Texas Instruments Inc
•
Filing: 1985-11-20
•
Granted: 1987-02-03
•
Expires: 2005-11-20
Abstract
Abstract One embodiment of the present invention provides a polycrystalline silicon loading device occupying a minimum of surface area in an integrated circuit. A very thin layer of silicon nitride is formed on the surface of a heavily doped contact point in the integrated circuit. An undoped layer of polycrystalline silicon is then formed on the surface of this thin layer of silicon nitride. A thin layer of silicon nitride is then formed on the surface of the undoped polycrystalline silicon layer. Finally a heavily doped polycrystalline silicon layer for making contact to the loading device is formed on the surface of the second thin silicon nitride layer. Because the two thin silicon nitride layers are very thin, tunneling current through the silicon nitride layers begins at a fairly low threshold level. After tunneling occurs, the main resistance element of the load device is the undoped polycrystalline silicon. The silicon nitride layers prevent the diffusion of dopants into the undoped polycrystalline silicon layer thereby maintaining the integrity of the resistive characteristics of the undoped polycrystalline silicon. Using this technique a load approximately 1 micron squared using present lithographic techniques may be fabricated.
Inventors
- 👤 Satwinder Malhi
- 👤 David A. Baglee
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 07:06
CPC Classifications
H; H10; H10B; H10B10/00; H10B10/15; H10D; H10D1/00; H10D1/40; H10D1/43; H10D88/00
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
120 words
A resistive load device comprising: a first layer of conductive material serving as one terminal of said load device; a first layer of insulating material capable of tunneling electrons directly overlying said first layer of conductive material; a layer of resistive material overlying said first insulating layer; a second layer of insulating material overlying said resistive material; a second layer of conductive material overlying said second layer of insulating material, said second layer of conductive material being connected to serve as another terminal of said resistive load device; wherein, at voltages above the tunneling threshold of said first layer of insulating material, the resistance of said layer of resistive material dominates the resistance of said first layer of insulating material.
Claim 2
Dependent Claim
120 words
A resistive load device comprising: a first layer of conductive material serving as one terminal of said load device; a first layer of insulating material capable of tunneling electrons directly overlying said first layer of conductive material; a layer of resistive material overlying said first insulating layer; a second layer of insulating material overlying said resistive material; a second layer of conductive material overlying said second layer of insulating material, said second layer of conductive material being connected to serve as another terminal of said resistive load device; wherein, at voltages above the tunneling threshold of said first layer of insulating material, the resistance of said layer of resistive material dominates the resistance of said first layer of insulating material.
Claim 3
Dependent Claim
20 words
A resistive load device as in claim 1, wherein said first and second layers of insulating material comprise silicon nitride.
Claim 4
Dependent Claim
98 words
A resistive load device comprising: a first layer of insulating material capable of tunneling electrons; a layer of resistive material formed adjacent to said first insulating layer; a second layer of said insulating material formed adjacent to said resistive material oppositely disposed from said first layer of insulating material; a first terminal connected to said first layer; and a second terminal connected to said second layer; wherein, at voltages above the tunneling threshold of said first layer of insulating material, the resistance of said layer of resistive material dominates the resistance of said first layer of insulating material.
Claim 5
Dependent Claim
98 words
A resistive load device comprising: a first layer of insulating material capable of tunneling electrons; a layer of resistive material formed adjacent to said first insulating layer; a second layer of said insulating material formed adjacent to said resistive material oppositely disposed from said first layer of insulating material; a first terminal connected to said first layer; and a second terminal connected to said second layer; wherein, at voltages above the tunneling threshold of said first layer of insulating material, the resistance of said layer of resistive material dominates the resistance of said first layer of insulating material.
Claim 6
Dependent Claim
112 words
A resistive load device comprising: a first layer of insulating material capable of tunneling electrons; a layer of resistive material formed adjacent to said first insulating layer; a second layer of said insulating material formed adjacent to said resistive material oppositely disposed from said first layer of insulating material; a first terminal connected to said first layer and oppositely disposed from said resistive material; and a second terminal connected to said second layer and oppositely disposed from said resistive material; wherein, at voltages above the tunneling threshold of said first layer of insulating material, the resistance of said layer of resistive material dominates the resistance of said first layer of insulating material.
Claim 7
Dependent Claim
112 words
A resistive load device comprising: a first layer of insulating material capable of tunneling electrons; a layer of resistive material formed adjacent to said first insulating layer; a second layer of said insulating material formed adjacent to said resistive material oppositely disposed from said first layer of insulating material; a first terminal connected to said first layer and oppositely disposed from said resistive material; and a second terminal connected to said second layer and oppositely disposed from said resistive material; wherein, at voltages above the tunneling threshold of said first layer of insulating material, the resistance of said layer of resistive material dominates the resistance of said first layer of insulating material.
Claim 8
Dependent Claim
14 words
A resistive load as in claim 1 wherein said insulating material is silicon nitride.
Claim 9
Dependent Claim
14 words
A resistive load as in claim 1 wherein said resistive material is polycrystalline silicon.
Claim 10
Dependent Claim
116 words
An integrated circuit having a resistive load device comprising: a first layer of insulating material capable of tunneling electrons; a layer of resistive material formed adjacent to said first insulating layer; a second layer of said insulating material formed adjacent to said resistive material oppositely disposed from said first layer of insulating material; a first terminal connected to said first layer and oppositely disposed from said resistive material; and a second terminal connected to said second layer and oppositely disposed from said resistive material; wherein, at voltages above the tunneling threshold of said first layer of insulating material, the resistance of said layer of resistive material dominates the resistance of said first layer of insulating material.
Claim 11
Dependent Claim
116 words
An integrated circuit having a resistive load device comprising: a first layer of insulating material capable of tunneling electrons; a layer of resistive material formed adjacent to said first insulating layer; a second layer of said insulating material formed adjacent to said resistive material oppositely disposed from said first layer of insulating material; a first terminal connected to said first layer and oppositely disposed from said resistive material; and a second terminal connected to said second layer and oppositely disposed from said resistive material; wherein, at voltages above the tunneling threshold of said first layer of insulating material, the resistance of said layer of resistive material dominates the resistance of said first layer of insulating material.
Claim 12
Dependent Claim
14 words
An integrated circuit as in claim 4 wherein said insulating material is silicon nitride.
Claim 13
Dependent Claim
14 words
An integrated circuit as in claim 4 wherein said resistive material is polycrystalline silicon.
Claim 14
Dependent Claim
111 words
A resistive load device comprising: a first layer of silicon nitride; a layer of polycrystalline silicon formed adjacent to said first insulating layer; a second layer of said silicon nitride adjacent to said polycrystalline silicon oppositely disposed from said first layer of insulating material; a first terminal connected to said first layer and oppositely disposed from said layer of polycrystalline silicon; and a second terminal connected to said second layer and oppositely disposed from said layer of polycrystalline silicon; wherein, at voltages above the tunneling threshold of said first layer of insulating material, the resistance of said layer of resistive material dominates the resistance of said first layer of insulating material.
Claim 15
Dependent Claim
111 words
A resistive load device comprising: a first layer of silicon nitride; a layer of polycrystalline silicon formed adjacent to said first insulating layer; a second layer of said silicon nitride adjacent to said polycrystalline silicon oppositely disposed from said first layer of insulating material; a first terminal connected to said first layer and oppositely disposed from said layer of polycrystalline silicon; and a second terminal connected to said second layer and oppositely disposed from said layer of polycrystalline silicon; wherein, at voltages above the tunneling threshold of said first layer of insulating material, the resistance of said layer of resistive material dominates the resistance of said first layer of insulating material.
Claim 16
Dependent Claim
115 words
An integrated circuit having a resistive load device comprising: a first layer of silicon nitride; a layer of polycrystalline silicon formed adjacent to said first insulating layer; a second layer of said silicon nitride adjacent to said polycrystalline silicon oppositely disposed from said first layer of insulating material; a first terminal connected to said first layer and oppositely disposed from said layer of polycrystalline silicon; and a second terminal connected to said second layer and oppositely disposed from said layer of polycrystalline silicon; wherein, at voltages above the tunneling threshold of said first layer of insulating material, the resistance of said layer of resistive material dominates the resistance of said first layer of insulating material.
Claim 17
Dependent Claim
115 words
An integrated circuit having a resistive load device comprising: a first layer of silicon nitride; a layer of polycrystalline silicon formed adjacent to said first insulating layer; a second layer of said silicon nitride adjacent to said polycrystalline silicon oppositely disposed from said first layer of insulating material; a first terminal connected to said first layer and oppositely disposed from said layer of polycrystalline silicon; and a second terminal connected to said second layer and oppositely disposed from said layer of polycrystalline silicon; wherein, at voltages above the tunneling threshold of said first layer of insulating material, the resistance of said layer of resistive material dominates the resistance of said first layer of insulating material.
Claim 18
Dependent Claim
110 words
A static random access memory cell comprising: first and second cross coupled transistors; first and second load devices regulating the current flow through said transistors, each load device including: (a) a first layer of insulating material capable of tunneling electrons; (b) a layer of resistive material formed adjacent to said first insulating layer; and (c) a second layer of said insulating material formed adjacent to said resistive material oppositely disposed from said first layer of insulating material; (d) wherein, at voltages above the tunneling threshold of said first layer of insulating material, the resistance of said layer of resistive material dominates the resistance of said first layer of insulating material.
Claim 19
Dependent Claim
110 words
A static random access memory cell comprising: first and second cross coupled transistors; first and second load devices regulating the current flow through said transistors, each load device including: (a) a first layer of insulating material capable of tunneling electrons; (b) a layer of resistive material formed adjacent to said first insulating layer; and (c) a second layer of said insulating material formed adjacent to said resistive material oppositely disposed from said first layer of insulating material; (d) wherein, at voltages above the tunneling threshold of said first layer of insulating material, the resistance of said layer of resistive material dominates the resistance of said first layer of insulating material.
Claim 20
Dependent Claim
18 words
The device of claim 7, wherein said second layer of insulating material is also capable of tunneling electrons.
Claim 21
Dependent Claim
24 words
The device of claim 7, wherein said second layer of insulating material has substantially the same composition as said first layer of insulating material.
Claim 22
Dependent Claim
29 words
The device of claim 7, wherein said first layer of insulating material is capable of tunneling electrons at a tunneling threshold voltage level of approximately 2 volts or less.
Claim 23
Dependent Claim
18 words
The device of claim 7, wherein said first layer of insulating material is less than 100 Angstroms thick.
Claim 24
Dependent Claim
18 words
The device of claim 7, wherein said second layer of insulating material is less than 100 Angstroms thick.
Claim 25
Dependent Claim
12 words
The device of claim 6, wherein said polycrystalline silicon is substantially intrinsic.
Claim 26
Dependent Claim
23 words
The device of claim 6, wherein said polycrystalline silicon is substantially intrinsic, and said first layer of insulating material comprises a diffusion barrier.
Claim 27
Dependent Claim
15 words
The device of claim 1, wherein said first layer of conductive material comprises doped silicon.
Claim 28
Dependent Claim
33 words
The device of claim 6, wherein said polycrystalline silicon is substantially intrinsic, and said first layer of insulating material comprises a diffusion barrier, and said first layer of conductive material comprises doped silicon.
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) | 1990-02-02 | 1990-08-04 | 1991-02-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-02-02 | 1994-08-04 | 1995-02-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-02-02 | 1998-08-04 | 1999-02-03 | $7700.00 | Window Closed / Lapsed |