Patent US5582939A successfully refreshed from Google Patents.
US5582939A
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US
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Method for fabricating and using defect-free phase shifting masks
Assignee: Micron Technology Inc
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Filing: 1995-07-10
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Granted: 1996-12-10
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Expires: 2015-07-10
Abstract
Abstract A method for forming a defect-free phase shift mask includes forming a mask blank having a substrate, an etch stop layer, a phase shift layer and an opaque layer. The etch stop layer and phase shift layer are formed of chemically different materials to allow selective etching and end point detection. Initially the opaque layer is patterned and etched using a process such as e-beam lithography. Then the phase shift layer is patterned and etched using the etch stop layer as an end point. Bump defects formed in phase shift areas are then removed by exposing a resist layer to leave the phase shifters, or alternately just the defects, unprotected. During defect etching, the etch stop layer can again be used to endpoint the etch process. The etch stop layer can also be formed as a phase shift layer to permit removal of indentation defects using a process such as ion milling.
Inventors
- 👤 Christophe Pierrat
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 11:53
CPC Classifications
G; G03; G03F; G03F1/00; G03F1/26; G03F1/30
Claims Analysis
Total Claims: 39
Claim 1
Independent Claim
117 words
A method for forming a phase shift mask comprising: providing a transparent substrate; forming a first layer on the substrate; forming a phase shift layer on the first layer out of a material that is chemically different than a material of the first layer; forming a pattern of opaque light blockers on the phase shift layer; etching the phase shift layer to form a pattern of phase shifters; depositing a layer of resist on the phase shift layer and exposing and developing the resist to form a mask having openings aligned with the phase shifters; and etching through the openings in the mask to the first layer to remove a bump defect on the phase shift layer.
Claim 2
Independent Claim
117 words
A method for forming a phase shift mask comprising: providing a transparent substrate; forming a first layer on the substrate; forming a phase shift layer on the first layer out of a material that is chemically different than a material of the first layer; forming a pattern of opaque light blockers on the phase shift layer; etching the phase shift layer to form a pattern of phase shifters; depositing a layer of resist on the phase shift layer and exposing and developing the resist to form a mask having openings aligned with the phase shifters; and etching through the openings in the mask to the first layer to remove a bump defect on the phase shift layer.
Claim 3
Dependent Claim
31 words
The method as claimed in claim 1 and wherein the mask is exposed using a same mask pattern as used for etching the phase shift layer to form the phase shifters.
Claim 4
Dependent Claim
34 words
The method as claimed in claim 1 and wherein the first layer is a thin film having a thickness that is not selected to provide a desired phase shift for light passing there through.
Claim 5
Dependent Claim
38 words
The method as claimed in claim 1 and further comprising forming the first layer as a second phase shift layer and removing an indentation defect by removing the first layer subjacent to the indentation defect to the substrate.
Claim 6
Dependent Claim
37 words
The method as claimed in claim 1 and wherein the first layer and phase shift layer are formed with indexes of refraction and thicknesses to provide a combined phase shift of 2pπ where p is an integer.
Claim 7
Dependent Claim
20 words
The method as claimed in claim 1 and wherein the first layer has a thickness of less than 500 Å.
Claim 8
Dependent Claim
27 words
The method as claimed in claim 1 and wherein the first layer is formed of a fluoride and the phase shift layer is formed of an oxide.
Claim 9
Dependent Claim
53 words
The method as claimed in claim 7 and wherein the substrate is formed of quartz and the phase shift layer is formed of SiO 2 and the first layer is formed of a material selected from the group consisting of MgF 2 , CaF 2 , YF 3 , and LaF 3 .
Claim 10
Dependent Claim
22 words
The method as claimed in claim 1 and wherein the etching step for removing the defects is an anisotropic dry etch process.
Claim 11
Dependent Claim
29 words
The method as claimed in claim 9 and wherein the defect is etched to an endpoint of the first layer by detecting by-product species present in an etch plasma.
Claim 12
Dependent Claim
24 words
The method as claimed in claim 1 and wherein the layer of resist is exposed and developed to leave the phase shifters substantially exposed.
Claim 13
Dependent Claim
24 words
The method as claimed in claim 1 and wherein the layer of resist is exposed and developed to leave just the defect substantially exposed.
Claim 14
Dependent Claim
25 words
The method as claimed in claim 1 and further comprising using the mask to expose a second layer of resist formed on a semiconductor wafer.
Claim 15
Dependent Claim
28 words
The method as claimed in claim 1 and wherein the mask is selected from the group consisting of alternating aperture phase shift masks and rim phase shift masks.
Claim 16
Independent Claim
113 words
A method for forming a phase shifting mask comprising: providing a transparent substrate; forming an etch stop layer and a phase shift layer on the substrate; depositing, exposing, and developing a first layer of resist to form a first mask for etching the phase shift layer to an endpoint of the etch stop layer to form phase shifters; depositing a second layer of resist over the phase shifters; exposing and developing the second layer of resist to form a second mask with openings aligned with the phase shifters; and removing bump defects on the phase shifters by etching through the openings in the second mask to an endpoint of the etch stop layer.
Claim 17
Independent Claim
113 words
A method for forming a phase shifting mask comprising: providing a transparent substrate; forming an etch stop layer and a phase shift layer on the substrate; depositing, exposing, and developing a first layer of resist to form a first mask for etching the phase shift layer to an endpoint of the etch stop layer to form phase shifters; depositing a second layer of resist over the phase shifters; exposing and developing the second layer of resist to form a second mask with openings aligned with the phase shifters; and removing bump defects on the phase shifters by etching through the openings in the second mask to an endpoint of the etch stop layer.
Claim 18
Dependent Claim
51 words
The method as claimed in claim 15 and wherein the etch stop layer and the phase shift layer are each formed with a thickness and index of refraction to provide a phase shift of π or odd multiple thereof, and a combined phase shift of 2pπ where p is an integer.
Claim 19
Dependent Claim
37 words
The method as claimed in claim 16 and further comprising removing indentation defects from the mask by removing the phase shift layer and the etch stop layer in an area surrounding the indentation defect to the substrate.
Claim 20
Dependent Claim
52 words
The method as claimed in claim 17 and wherein the substrate is formed of quartz, the phase shift layer is formed of SiO 2 and the etch stop layer is formed of a material selected from the group consisting of MgF 2 , CaF 2 , YF 3 , LaF 3 .
Claim 21
Dependent Claim
17 words
The method as claimed in claim 15 and wherein the mask is a chromeless phase shift mask.
Claim 22
Dependent Claim
29 words
The method as claimed in claim 15 and further comprising forming an opaque layer on the phase shift layer and patterning the opaque layer to form opaque light blockers.
Claim 23
Dependent Claim
26 words
The method as claimed in claim 20 and wherein the opaque layer and phase shift layer are patterned to form an alternating aperture phase shifting mask.
Claim 24
Dependent Claim
25 words
The method as claimed in claim 20 and wherein the opaque layer and phase shift layer are patterned to form a rim phase shifting mask.
Claim 25
Independent Claim
144 words
A method for forming a phase shift mask comprising: providing a transparent substrate; forming an etch stop layer on the substrate out of a first material; forming a phase shift layer on the etch stop layer out of a second material that is chemically different than the first material; patterning the opaque layer by exposing and developing a first layer of resist to form a first mask for etching the opaque layer to form opaque light blockers; patterning the phase shift layer by exposing and developing a second layer of resist to form a second mask for etching the opaque layer to the etch stop layer to form phase shifters; removing bump defects on the phase shifters by exposing and developing a third layer of resist using a same pattern as the second mask to form a third mask for etching the bump defects.
Claim 26
Independent Claim
144 words
A method for forming a phase shift mask comprising: providing a transparent substrate; forming an etch stop layer on the substrate out of a first material; forming a phase shift layer on the etch stop layer out of a second material that is chemically different than the first material; patterning the opaque layer by exposing and developing a first layer of resist to form a first mask for etching the opaque layer to form opaque light blockers; patterning the phase shift layer by exposing and developing a second layer of resist to form a second mask for etching the opaque layer to the etch stop layer to form phase shifters; removing bump defects on the phase shifters by exposing and developing a third layer of resist using a same pattern as the second mask to form a third mask for etching the bump defects.
Claim 27
Dependent Claim
22 words
The method as claimed in claim 23 and wherein etching the bump defects is performed anisotropically to avoid undercutting the phase shifters.
Claim 28
Dependent Claim
46 words
The method as claimed in claim 23 and wherein the phase shift layer is formed of SiO 2 and the etch stop layer is formed of a material selected from the group consisting of MgF 2 , CaF 2 , YF 3 , LaF 3 .
Claim 29
Dependent Claim
29 words
The method as claimed in claim 23 and wherein the substrate is formed of a material selected from the group consisting of quartz and Al 2 O 3 .
Claim 30
Dependent Claim
22 words
The method as claimed in claim 23 and wherein the first and second layers of resist are exposed using electron beam lithography.
Claim 31
Dependent Claim
21 words
The method as claimed in claim 27 and wherein the third layer of resist is exposed using a mask repair tool.
Claim 32
Dependent Claim
38 words
The method as claimed in claim 23 and further comprising removing an indentation defect from the mask by removing the phase shift layer and the etch stop layer in an area surrounding the indentation defect to the substrate.
Claim 33
Dependent Claim
38 words
The method as claimed in claim 23 and wherein the etch stop layer and phase shift layer are formed with indexes of refraction and thicknesses to provide a combined phase shift of 2pπ where p is an integer.
Claim 34
Dependent Claim
25 words
The method as claimed in claim 23 and further comprising using the mask to pattern a semiconductor wafer coated with a fourth layer of resist.
Claim 35
Independent Claim
104 words
A method for forming a phase shift mask comprising: providing a transparent substrate; forming an etch stop layer and a phase shift layer on the substrate; forming a pattern of opaque light blockers on the phase shift layer; etching the phase shift layer to the etch stop layer to form a pattern of phase shifters; locating bump defects on the phase shifters; depositing a layer of resist on the phase shift layer; exposing and developing the resist to form a mask having openings aligned with the defects; and etching through the openings in the mask to the etch stop layer to remove the defects.
Claim 36
Independent Claim
104 words
A method for forming a phase shift mask comprising: providing a transparent substrate; forming an etch stop layer and a phase shift layer on the substrate; forming a pattern of opaque light blockers on the phase shift layer; etching the phase shift layer to the etch stop layer to form a pattern of phase shifters; locating bump defects on the phase shifters; depositing a layer of resist on the phase shift layer; exposing and developing the resist to form a mask having openings aligned with the defects; and etching through the openings in the mask to the etch stop layer to remove the defects.
Claim 37
Dependent Claim
18 words
The method as claimed in claim 32 and wherein exposing the resist is with an e-beam mask writer.
Claim 38
Dependent Claim
18 words
The method as claimed in claim 32 and wherein exposing the resist is with a mask writing tool.
Claim 39
Dependent Claim
18 words
The method as claimed in claim 32 and wherein locating the defects is with a scanning electron microscope.
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) | 1999-12-10 | 2000-06-10 | 2000-12-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-12-10 | 2004-06-10 | 2004-12-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-12-10 | 2008-06-10 | 2008-12-10 | $7700.00 | Window Closed / Lapsed |