US6165910A
Expired / Lapsed
US
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Self-aligned contacts for semiconductor device
Assignee: Lam Research Corp
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Filing: 1997-12-29
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Granted: 2000-12-26
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Expires: 2017-12-29
Abstract
Abstract In a plasma processing chamber, a method for etching through a selected portion of an oxide layer of a wafer's layer stack to create a self-aligned contact opening is described. The wafer stack includes a substrate, a polysilicon layer disposed above the substrate, a nitride layer disposed above said polysilicon layer and the oxide layer disposed above the nitride layer. The method for etching includes etching through the oxide layer of the layer stack with a chemistry and a set of process parameters. The chemistry essentially includes C2HF5 and CH2F2 and the set of process parameters facilitate etching through the oxide layer without creating a spiked etch and etching the oxide layer through to the substrate without substantially damaging the nitride layer.
Inventors
- 👤 Janet M. Flanner
- 👤 Linda N. Marquez
- 👤 Joel M. Cook
- 👤 Ian J. Morey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 03:36
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/28; H10W; H10W20/00; H10W20/01; H10W20/031; H10W20/069; H10P50/282; H10P50/283
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
123 words
In a plasma processing chamber, a method for etching through a selected portion of an oxide layer of a wafer's layer stack to create a self-aligned contact opening, said wafer stack comprising a substrate, a polysilicon layer disposed above said substrate, a nitride layer disposed above said polysilicon layer, said oxide layer being disposed above said nitride layer, said method comprising: etching through said oxide layer of said layer stack with a chemistry and a set of process parameters, said chemistry comprising C 2 HF 5 and CH 2 F 2 , said set of process parameters facilitate etching through said oxide layer without creating a spiked etch and etching said oxide layer through to said substrate without substantially damaging said nitride layer.
Claim 2
Dependent Claim
123 words
In a plasma processing chamber, a method for etching through a selected portion of an oxide layer of a wafer's layer stack to create a self-aligned contact opening, said wafer stack comprising a substrate, a polysilicon layer disposed above said substrate, a nitride layer disposed above said polysilicon layer, said oxide layer being disposed above said nitride layer, said method comprising: etching through said oxide layer of said layer stack with a chemistry and a set of process parameters, said chemistry comprising C 2 HF 5 and CH 2 F 2 , said set of process parameters facilitate etching through said oxide layer without creating a spiked etch and etching said oxide layer through to said substrate without substantially damaging said nitride layer.
Claim 3
Dependent Claim
21 words
The method of claim 1, wherein the self-aligned contact opening has an aspect ratio of between about 1:1 and about 4:1.
Claim 4
Dependent Claim
23 words
The method of claim 1, wherein the self-aligned contact opening has a depth that is less than or equal to about 1 micron.
Claim 5
Dependent Claim
23 words
The method of claim 3, wherein the self-aligned contact opening has a depth that is less than or equal to about 7500 Angstroms.
Claim 6
Dependent Claim
23 words
The method of claim 3, wherein a top plane of the nitride layer is disposed at most about 5000 Angstroms above the substrate.
Claim 7
Dependent Claim
23 words
The method of claim 5, wherein the top plane of the nitride layer is disposed at most about 2500 Angstroms above the substrate.
Claim 8
Dependent Claim
29 words
The method of claim 1, wherein the plasma processing chamber is a transformer coupled plasma etch system, which strikes a plasma by inductive coupling action of a top electrode.
Claim 9
Dependent Claim
22 words
The method of claim 7, wherein the temperature of the top electrode is controlled by circulating a coolant through the top electrode.
Claim 10
Dependent Claim
18 words
The method of claim 1, wherein an interior of the plasma processing chamber is made from anodized aluminum.
Claim 11
Dependent Claim
15 words
The method of claim 1, wherein the gas distribution plate is made from silicon nitride.
Claim 12
Dependent Claim
22 words
The method of claim 1, wherein the chemistry includes at least one of CF 4 , C 2 F 6 and argon.
Claim 13
Dependent Claim
28 words
The method of claim 11, wherein a bottom electrode of the plasma chamber includes a focus ring that is made from one of silicon nitride and silicon carbide.
Claim 14
Dependent Claim
18 words
The method of claim 11, wherein the substrate is secured above a bottom electrode using an electrostatic clamp.
Claim 15
Dependent Claim
196 words
In a plasma processing chamber, a method for etching through a selected portion of an oxide layer of a wafer's layer stack to create a self-aligned contact opening, said wafer stack comprising a substrate, a polysilicon layer disposed above said substrate, a nitride layer disposed above said polysilicon layer, said oxide layer being disposed above said nitride layer, said method comprising: a first etching step for etching partially through said oxide layer of said layer stack with a first chemistry and a first set of process parameters, said first chemistry consisting essentially of CHF 3 and C 2 HF 5 , said first set of process parameters represents a set of parameters for etching through said oxide layer without creating a spiked etch; and a second etching step for etching said oxide layer through to said substrate with a second chemistry consisting essentially of C 2 HF 5 and CH 2 F 2 and a second set of process parameters, said second set of process parameters being different from said first set of process parameters and representing a set of parameters for etching said oxide layer through to said substrate without substantially damaging said nitride layer.
Claim 16
Dependent Claim
196 words
In a plasma processing chamber, a method for etching through a selected portion of an oxide layer of a wafer's layer stack to create a self-aligned contact opening, said wafer stack comprising a substrate, a polysilicon layer disposed above said substrate, a nitride layer disposed above said polysilicon layer, said oxide layer being disposed above said nitride layer, said method comprising: a first etching step for etching partially through said oxide layer of said layer stack with a first chemistry and a first set of process parameters, said first chemistry consisting essentially of CHF 3 and C 2 HF 5 , said first set of process parameters represents a set of parameters for etching through said oxide layer without creating a spiked etch; and a second etching step for etching said oxide layer through to said substrate with a second chemistry consisting essentially of C 2 HF 5 and CH 2 F 2 and a second set of process parameters, said second set of process parameters being different from said first set of process parameters and representing a set of parameters for etching said oxide layer through to said substrate without substantially damaging said nitride layer.
Claim 17
Dependent Claim
24 words
The method of claim 14, wherein said second chemistry further includes at least one of CF 4 , C 2 F 6 and argon.
Claim 18
Dependent Claim
34 words
The method of claim 14, wherein the plasma processing chamber strikes a plasma using a top electrode and a temperature of the top electrode is controlled by circulating a coolant through the top electrode.
Claim 19
Dependent Claim
38 words
The method of claim 14, wherein said first set of process parameters results in a lower oxide-to-nitride selectivity in said first etching step than an oxide-to-nitride selectivity achieved in said second etching step using said second process parameters.
Claim 20
Dependent Claim
51 words
The method of claim 14, wherein said first etching step terminates upon reaching a predefined position, said predefined position being in the range of about 1,000 angstroms above a plane defined by a top surface of said nitride layer to a position that substantially equals a midpoint of said nitride layer.
Claim 21
Dependent Claim
51 words
The method of claim 18, wherein said first etching step terminates upon reaching a predefined position, said predefined position being in the range of about 250 angstroms above a plane defined by a top surface of said nitride layer to a position that substantially equals a midpoint of said nitride layer.
Claim 22
Dependent Claim
25 words
The method of claim 19, wherein said first etching step terminates upon substantially reaching a plane defined by a top surface of said nitride layer.
Claim 23
Dependent Claim
40 words
The method of claim 14, wherein said first set of process parameters comprises a first chamber etch pressure and said second set of process parameters comprises a second chamber etch pressure, which is lower than said first chamber etch pressure.
Claim 24
Dependent Claim
22 words
The method of claim 14 wherein said plasma processing chamber represents a plasma processing chamber in a high density plasma etch system.
Claim 25
Dependent Claim
19 words
The method of claim 22, wherein said high density plasma etch system represents a transformer coupled plasma etch system.
Claim 26
Dependent Claim
21 words
The method of claim 14, wherein the self-aligned contact opening has an aspect ratio greater than or equal to about 3:1.
Claim 27
Dependent Claim
20 words
The method of claim 14, wherein the self-aligned contact opening has a depth that is more than about 0.75 micron.
Claim 28
Dependent Claim
19 words
The method of claim 25, wherein the nitride layer is disposed at most about 5000 Angstroms above the substrate.
References Cited (Backward Citations)
US4412902A
Cited
US5155331A
Cited
US4987099A
Cited
US4980304A
Cited
US5374332A
Cited
US5271788A
Cited
US5286344A
Cited
US5286667A
Cited
US5683537A
Cited
US5637237A
Cited
US5643394A
Cited
EP0797250A2
Cited
US5783496A
Cited
EP0805485A2
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2003-12-26 | 2004-06-26 | 2004-12-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-12-26 | 2008-06-26 | 2008-12-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-12-26 | 2012-06-26 | 2012-12-26 | $7700.00 | Window Closed / Lapsed |