US5747381A
Expired / Lapsed
US
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Technique for the removal of residual spin-on-glass (SOG) after full SOG etchback
Assignee: Taiwan Semiconductor Manufacturing Co TSMC Ltd
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Filing: 1996-02-12
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Granted: 1998-05-05
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Expires: 2016-02-12
Abstract
Abstract This invention relates to a method for removing residual spin-on-glass (SOG) during a planarization processing step wherein the SOG is used as a sacrificial planarization medium and subjected to a full etchback to an underlying interlevel dielectric (ILD) layer. The SOG is applied over the ILD layer, and etched back into the ILD layer by reactive-ion-etching under conditions of comparable etch rates for both SOG and ILD. At endpoint there some residual pockets of SOG can be present as well as a region of SOG along the edges of the wafer where it is clamped in the etchback tool. The residual SOG must be removed completely to avoid SOG cracking after thermal processing and SOG outgassing during subsequent metal deposition. For this purpose an aqueous etch consisting of hydrofluoric acid buffered with ammonium fluoride is used. The etchant composition chosen exhibits a selectivity for SOG over the ILD glass of greater than 40 making it suitable for removing considerable SOG residues with minimal attack of the ILD.
Inventors
- 👤 Lin-June Wu
- 👤 Chen-Hua Douglas Yu
- 👤 Jin-Yuan Lee
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 05:06
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/28; H10P50/286; H10P50/287; H10W; H10W20/00; H10W20/01; H10W20/071; H10W20/092
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
58 words
A method for removing residual spin-on-glass (SOG) from a layer of dielectric material deposited on a substrate comprising: providing a substrate covered with a layer of dielectric material having residual areas of SOG on its surface said residual areas of SOG resulting from an anisotropic etch of said SOG; and etching said residual areas with an aqueous etchant.
Claim 2
Independent Claim
58 words
A method for removing residual spin-on-glass (SOG) from a layer of dielectric material deposited on a substrate comprising: providing a substrate covered with a layer of dielectric material having residual areas of SOG on its surface said residual areas of SOG resulting from an anisotropic etch of said SOG; and etching said residual areas with an aqueous etchant.
Claim 3
Dependent Claim
25 words
The method of claim 1 wherein said dielectric material is chosen from the group consisting of silicon oxide, a phosphosilicate glass, and a borophosphosilicate glass.
Claim 4
Dependent Claim
20 words
The method of claim 1 wherein said SOG is selected from the group consisting of a silicate, and a siloxane.
Claim 5
Dependent Claim
17 words
The method of claim 1 wherein said selective aqueous etchant is hydrofluoric acid buffered with ammonium fluoride.
Claim 6
Dependent Claim
45 words
The method of claim 4 wherein the composition of said hydrofluoric acid buffered with ammonium fluoride is 10 parts or thereabout by volume of 40% (12.75 molar) ammonium fluoride and 1 part or thereabout by volume of concentrated (49 wt. %, 28.3 molar) hydrofluoric acid.
Claim 7
Dependent Claim
33 words
The method of claim 4 wherein the selectivity of said hydrofluoric acid buffered with ammonium fluoride for SOG over ILD is determined by the concentration of HF 2 - in said aqueous etchant.
Claim 8
Independent Claim
170 words
A method for removal of residual spin-on-glass (SOG) following a full SOG etchback planarization processing step used in the manufacture of MOSFET integrated circuit devices comprising: providing a semiconductor wafer having MOSFET integrated circuit devices formed within its surface; depositing a first interlevel dielectric (ILD) layer over said semiconductor wafer; depositing a second ILD layer over said first ILD layer; depositing a spin-on-glass (SOG) precursor layer over said second ILD layer; removing a portion of said SOG precursor layer from the edge of said semiconductor wafer with an organic solvent; curing said SOG precursor layer to form a SOG layer; etching said SOG layer into said second ILD layer except for a residual area of SOG using an anisotropic etching; etching said residual SOG layer from said wafer with an aqueous etchant after said anisotropic etching; depositing a photoresist layer over said wafer; patterning said photoresist layer to define contact openings to said semiconductor devices; and etching said first ILD layer and said second ILD layer to form contact openings.
Claim 9
Independent Claim
170 words
A method for removal of residual spin-on-glass (SOG) following a full SOG etchback planarization processing step used in the manufacture of MOSFET integrated circuit devices comprising: providing a semiconductor wafer having MOSFET integrated circuit devices formed within its surface; depositing a first interlevel dielectric (ILD) layer over said semiconductor wafer; depositing a second ILD layer over said first ILD layer; depositing a spin-on-glass (SOG) precursor layer over said second ILD layer; removing a portion of said SOG precursor layer from the edge of said semiconductor wafer with an organic solvent; curing said SOG precursor layer to form a SOG layer; etching said SOG layer into said second ILD layer except for a residual area of SOG using an anisotropic etching; etching said residual SOG layer from said wafer with an aqueous etchant after said anisotropic etching; depositing a photoresist layer over said wafer; patterning said photoresist layer to define contact openings to said semiconductor devices; and etching said first ILD layer and said second ILD layer to form contact openings.
Claim 10
Dependent Claim
27 words
The method of claim 7 wherein said first ILD layer is silicon oxide deposited by APCVD at a temperature of between about 400° C. to 450° C.
Claim 11
Dependent Claim
29 words
The method of claim 7 wherein said second ILD layer is a borophosphosilicate glass formed from silane and nitrous oxide, in the presence of n- and p-type dopant sources.
Claim 12
Dependent Claim
31 words
The method of claim 7 wherein said second ILD layer is a borophosphosilicate glass formed from the thermal decomposition of tetraethyl orthosilicate in the presence of n- and p-type dopant sources.
Claim 13
Dependent Claim
25 words
The method of claim 10 wherein said second ILD layer is deposited using APCVD at a temperature of between about 400° C. to 450° C.
Claim 14
Dependent Claim
24 words
The method of claim 7 wherein the material for the SOG layer is selected from the group consisting of a silicate, and a siloxane.
Claim 15
Dependent Claim
31 words
The method of claim 7 wherein said SOG layer is cured by annealing in a furnace at a temperature of between about 380° C. to 460° C. in a nitrogen ambient.
Claim 16
Dependent Claim
29 words
The method of claim 7 wherein said SOG layer is cured by radiation of the type selected from the group consisting of UV, deep UV, X-ray, and electron beam.
Claim 17
Dependent Claim
12 words
The method of claim 7 wherein the organic solvent is isopropyl alcohol.
Claim 18
Dependent Claim
44 words
The method of claim 7 wherein said anisotropic etching is reactive-ion-etching using an etchant gas and conditions to provide comparable etch rates for the SOG layer and the second ILD layer and with a method of end-point-detection to determine when etching should be halted.
Claim 19
Dependent Claim
11 words
The method of claim 16 wherein said etchant gas contains tetrafluoromethane.
Claim 20
Dependent Claim
30 words
The method of claim 16 wherein the method of endpoint-detection is optical emission spectroscopy using the magnitude of the carbon monoxide signal at 482.5 nm as an indicator of endpoint.
Claim 21
Dependent Claim
23 words
The method of claim 7 wherein said aqueous etchant for the removal of said SOG layer is hydrofluoric acid buffered with ammonium fluoride.
Claim 22
Dependent Claim
45 words
The method of claim 19 wherein the composition of said hydrofluoric acid buffered with ammonium fluoride is 10 parts or thereabout by volume of 40% (12.75 molar) ammonium fluoride to 1 part or thereabout by volume of concentrated (49 wt. %, 28.3 molar) hydrofluoric acid.
Claim 23
Dependent Claim
33 words
The method of claim 19 wherein the selectivity of said hydrofluoric acid buffered with ammonium fluoride for SOG over ILD is determined by the concentration of HF 2 - in said aqueous etchant.
References Cited (Backward Citations)
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 2001-05-04 | 2001-11-03 | 2002-05-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-05-04 | 2005-11-03 | 2006-05-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-05-04 | 2009-11-03 | 2010-05-05 | $7700.00 | Window Closed / Lapsed |