EP0369336A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Process for fabricating bipolar and CMOS transistors on a common substrate
Assignee: National Semiconductor Corp
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Filing: 1989-11-10
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Granted: —
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Expires: 2009-11-10
Abstract
Abstract An intercontact dielectric layer includes an underlying layer of undoped silicon dicxide overlaid by a relatively thicker layer of boron- and phosphorus-doped silicon dioxide. The difference in etching rates between the doped and undoped layers allows the use of both wet and dry etches to form contact openings having improved cross-sectional profiles to enhance step coverage of subsequently formed layers.
Inventors
- 👤 Bami Bastani
- 👤 Craig Lage
- 👤 Larry Wong
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 18:33
CPC Classifications
H; H10; H10D; H10D84/00; H10D84/01; H10D84/0107; H10D84/0109; H10W; H10W20/00; H10W20/01; H10W20/071; H10W20/081; H10W20/082; H10W20/40; H10W20/45; H10W20/48
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
88 words
A method of forming contact openings in a semiconductor structure comprising: depositing on an underlying structure a first layer of undoped silicon dioxide; depositing on the first layer a second layer of doped silicon dioxide; forming a mask over the second layer to define locations for contact openings in the second layer; anisotropically etching openings through both the first and second layers to the underlying structure; and isotropically etching the first and second layer with a substance which selectively attacks the second layer more than the first layer.
Claim 2
Independent Claim
88 words
A method of forming contact openings in a semiconductor structure comprising: depositing on an underlying structure a first layer of undoped silicon dioxide; depositing on the first layer a second layer of doped silicon dioxide; forming a mask over the second layer to define locations for contact openings in the second layer; anisotropically etching openings through both the first and second layers to the underlying structure; and isotropically etching the first and second layer with a substance which selectively attacks the second layer more than the first layer.
Claim 3
Dependent Claim
14 words
A method as in Claim 1 wherein the second layer is doped with boron.
Claim 4
Dependent Claim
14 words
A method as in Claim 1 wherein the second layer is doped with phosphorus.
Claim 5
Dependent Claim
17 words
A method as in Claim 1 wherein the second layer is doped with both boron and phosphorus.
Claim 6
Dependent Claim
18 words
A method as in Claim 4 wherein the second layer is doped with between 2-4% boron by weight.
Claim 7
Dependent Claim
18 words
A method as in Claim 4 wherein the second layer is doped with between 5-7% phosphorus by weight.
Claim 8
Dependent Claim
24 words
A method as in Claim 4 wherein the second layer is doped with about 2% boron by weight and about 6.5% phosphorus by weight.
Claim 9
Dependent Claim
16 words
A method as in Claim 1 wherein the first layer is thinner than the second layer.
Claim 10
Dependent Claim
24 words
A method as in Claim 8 wherein the second layer is approximately 9000 Å thick and the first layer is approximately 1000 Å thick.
Claim 11
Dependent Claim
19 words
A method as in Claim 1 wherein the step of depositing a first layer comprises using chemical vapor deposition.
Claim 12
Dependent Claim
17 words
A method as in Claim 1 wherein the step of anisotropically etching comprises etching in hydro-fluoric acid.
Claim 13
Dependent Claim
24 words
A method as in Claim 1 wherein prior to the step of forming a mask a step is performed comprising heating the second layer.
Claim 14
Dependent Claim
21 words
A method as in Claim 11 wherein the step of heating comprises heating the second layer in steam to about 920°C.
Claim 15
Dependent Claim
16 words
A method as in Claim 1 wherein the step of isotropically etching comprises reactive ion etching.
Claim 16
Independent Claim
104 words
A method of forming contact openings in a semiconductor comprising: depositing on an underlying semiconductor structure a first layer of undoped silicon dioxide; depositing on the first layer a second layer of silicon dioxide doped with both phosphorus and boron; heating at least the second layer to a temperature to cause it to become flatter; forming a mask over the second layer to define locations for contact openings in the second layer; etching openings through both the first and second layers using reactive ion etching to thereby expose portions of the underlying structure; and isotropically etching the first and second layers with hydrofluoric acid.
Claim 17
Independent Claim
104 words
A method of forming contact openings in a semiconductor comprising: depositing on an underlying semiconductor structure a first layer of undoped silicon dioxide; depositing on the first layer a second layer of silicon dioxide doped with both phosphorus and boron; heating at least the second layer to a temperature to cause it to become flatter; forming a mask over the second layer to define locations for contact openings in the second layer; etching openings through both the first and second layers using reactive ion etching to thereby expose portions of the underlying structure; and isotropically etching the first and second layers with hydrofluoric acid.
Claim 18
Dependent Claim
54 words
A contact opening for a semiconductor structure comprising: an underlying region to which an ohmic contact is desired; a first layer of undoped silicon dioxide having a first opening over the region; and a second layer of doped silicon dioxide disposed on the first layer and having a second opening over the first opening.
Claim 19
Dependent Claim
54 words
A contact opening for a semiconductor structure comprising: an underlying region to which an ohmic contact is desired; a first layer of undoped silicon dioxide having a first opening over the region; and a second layer of doped silicon dioxide disposed on the first layer and having a second opening over the first opening.
Claim 20
Dependent Claim
24 words
A contact opening as in Claim 15 wherein the second opening is larger than the first opening and encompasses all of the first opening.
Claim 21
Dependent Claim
25 words
A contact opening as in Claim 16 wherein the first opening extends through the first layer to create substantially vertical sidewalls in the first layer.
Claim 22
Dependent Claim
27 words
A contact opening as in Claim 17 wherein the second opening extends through the first layer to create sidewalls in the second layer which are not vertical.
Claim 23
Dependent Claim
15 words
A contact opening as in Claim 15 wherein the second layer comprises boron-doped silicon dioxide.
Claim 24
Dependent Claim
15 words
A contact opening as in Claim 15 wherein the second layer comprises phosphorus-doped silicon dioxide.
Claim 25
Dependent Claim
20 words
A contact opening as in Claim 15 wherein the second layer comprises silicon dioxide doped with both boron and phosphorus.
Claim 26
Dependent Claim
26 words
A contact opening as in Claim 22 wherein the boron comprises about 2-4% by weight and the phosphorus about 5-7% by weight of the silicon dioxide.
Claim 27
Independent Claim
72 words
A method of forming a coplanar P-well and N-well in a semiconductor structure comprising: masking a semiconductor substrate to define a first masked region and a second unmasked region; introducing a first conductivity-type impurity into the unmasked region; oxidizing the unmasked region; masking the semiconductor substrate to cover the second unmasked region and thereby leave the first region unmasked; introducing opposite conductivity-type impurity into the first region; and oxidizing the first region.
Claim 28
Independent Claim
72 words
A method of forming a coplanar P-well and N-well in a semiconductor structure comprising: masking a semiconductor substrate to define a first masked region and a second unmasked region; introducing a first conductivity-type impurity into the unmasked region; oxidizing the unmasked region; masking the semiconductor substrate to cover the second unmasked region and thereby leave the first region unmasked; introducing opposite conductivity-type impurity into the first region; and oxidizing the first region.
References Cited (Backward Citations)
No citation records indexed.
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