US5217830A
Expired / Lapsed
US
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Method of fabricating phase shifting reticles using ion implantation
Assignee: Micron Technology Inc
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Filing: 1991-03-26
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Granted: 1993-06-08
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Expires: 2011-03-26
Abstract
Abstract A method of fabricating a phase shifting reticle that can be used as a mask in photolithographic processes such as semiconductor wafer patterning. A transparent quartz substrate is first coated with a patterned resist. The quartz substrate is then subjected to high voltage ion bombardment to produce a pattern of ion implant areas on the substrate. The ion implantation is closely controlled to produce areas on the substrate having an index of refraction different than the quartz substrate and selected to achieve a 180° phase shift. An opaque film is then deposited over the substrate and patterned with openings. This produces a repetitive pattern of alternating light transmission openings and phase shifters having opaque light blockers on either side.
Inventors
- 👤 Tyler Lowrey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 11:10
CPC Classifications
G; G03; G03F; G03F1/00; G03F1/26; G03F1/30
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
127 words
A method of forming a phase shifting reticle comprising: forming a pattern of ion implant areas on a transparent substrate by ion bombardment of the substrate with an ion dopant selected to change an index of refraction of the substrate to produce a phase of light and form a phase shifter in each ion impact area; depositing an opaque film on the transparent substrate; and forming openings through the opaque film to the substrate in a repetitive pattern to form a pattern of opaque light blockers with the opaque light blockers self aligned with the ion implant phase shifters and with light transmission openings so that light passed through an ion implant phase shifter is shifted out of phase with light passed through a light transmission opening.
Claim 2
Independent Claim
127 words
A method of forming a phase shifting reticle comprising: forming a pattern of ion implant areas on a transparent substrate by ion bombardment of the substrate with an ion dopant selected to change an index of refraction of the substrate to produce a phase of light and form a phase shifter in each ion impact area; depositing an opaque film on the transparent substrate; and forming openings through the opaque film to the substrate in a repetitive pattern to form a pattern of opaque light blockers with the opaque light blockers self aligned with the ion implant phase shifters and with light transmission openings so that light passed through an ion implant phase shifter is shifted out of phase with light passed through a light transmission opening.
Claim 3
Dependent Claim
39 words
The method as recited in claim 1 and wherein: the phase shifters are ion implanted with an ion dopant to change the index of refraction of the substrate in the ion implant areas to achieve a 180° phase shift.
Claim 4
Dependent Claim
19 words
The method as recited in claim 1 and wherein: ion implantation is by ion bombardment with electrostatic beam scanning.
Claim 5
Dependent Claim
41 words
The method as recited in claim 1 and wherein: forming a pattern of ion implant areas is by a first photolithographic process in which the substrate is coated with a patterned resist having openings for forming phase shifters on the substrate.
Claim 6
Dependent Claim
48 words
The method as recited in claim 1 and wherein: forming a pattern of light transmission openings in the opaque film is by a second photolithographic process in which the opaque film is patterned with a resist, etched to form the light transmission openings and the resist is stripped.
Claim 7
Dependent Claim
17 words
The method as recited in claim 1 and wherein: the ion dopant is a species of boron.
Claim 8
Dependent Claim
17 words
The method as recited in claim 1 and wherein: the ion dopant is a species of phosphorous.
Claim 9
Independent Claim
181 words
A method of forming a phase shifting reticle for use in semiconductor photolithography comprising: coating a patterned film layer on a transparent substrate to form blocks to an ion beam and to form openings to the substrate; ion bombarding the substrate such that ion implant areas are formed on the substrate adjacent to the openings phase shifters having an index of refraction different than an index of refraction of the substrate to produce a phase shift of light; depositing an opaque film over the substrate and ion implant areas to define an image; coating a layer of photoresist over the opaque film, patterning the layer of photoresist with openings, with an opening located on each phase shifter and in an area between each phase shifter; and etching the opaque film to form light transmission openings through the opaque film to the substrate in an alternating repetitive pattern of self aligned phase shifters and light transmission openings having opaque light blockers on either side with each opaque light blocker located partially over a phase shifter and partially over a light transmission openings.
Claim 10
Independent Claim
181 words
A method of forming a phase shifting reticle for use in semiconductor photolithography comprising: coating a patterned film layer on a transparent substrate to form blocks to an ion beam and to form openings to the substrate; ion bombarding the substrate such that ion implant areas are formed on the substrate adjacent to the openings phase shifters having an index of refraction different than an index of refraction of the substrate to produce a phase shift of light; depositing an opaque film over the substrate and ion implant areas to define an image; coating a layer of photoresist over the opaque film, patterning the layer of photoresist with openings, with an opening located on each phase shifter and in an area between each phase shifter; and etching the opaque film to form light transmission openings through the opaque film to the substrate in an alternating repetitive pattern of self aligned phase shifters and light transmission openings having opaque light blockers on either side with each opaque light blocker located partially over a phase shifter and partially over a light transmission openings.
Claim 11
Dependent Claim
34 words
The method as recited in claim 8 and wherein: the reticle is formed with a repetitive pattern including an opaque light blocker, a phase shifter, an opaque light blocker and a light transmission opening.
Claim 12
Dependent Claim
37 words
The method as recited in claim 9 and wherein: the ion implant phase shifters are implanted with a dopant selected and concentrated to change the index of refraction of the substrate to provide a 180° phase shift.
Claim 13
Dependent Claim
14 words
The method as recited in claim 10 and wherein: the substrate is quartz (QZ).
Claim 14
Independent Claim
159 words
A method of forming a phase shifting reticle for use in semiconductor photolithography comprising: coating a layer of photoresist onto a quartz (QZ) substrate and patterning the resist by a first photolithographic process to form openings through the resist to the substrate; ion implanting a selected ion dopant in the openings by means of high voltage ion bombardment to form ion implant phase shifters on the substrate with the phase shifters having an index of refraction different than an index of refraction of the quartz substrate to produce a phase shift of light; depositing an opaque film over the substrate; forming openings through the opaque film by a second photolithographic process in a repetitive pattern with each opening located partially over a phase shifter and partially over an area between each phase shifter to form a self aligning repetitive pattern of an opaque light blocker, a light transmission opening, an opaque light blocker, and an ion implanted phase shifter.
Claim 15
Independent Claim
159 words
A method of forming a phase shifting reticle for use in semiconductor photolithography comprising: coating a layer of photoresist onto a quartz (QZ) substrate and patterning the resist by a first photolithographic process to form openings through the resist to the substrate; ion implanting a selected ion dopant in the openings by means of high voltage ion bombardment to form ion implant phase shifters on the substrate with the phase shifters having an index of refraction different than an index of refraction of the quartz substrate to produce a phase shift of light; depositing an opaque film over the substrate; forming openings through the opaque film by a second photolithographic process in a repetitive pattern with each opening located partially over a phase shifter and partially over an area between each phase shifter to form a self aligning repetitive pattern of an opaque light blocker, a light transmission opening, an opaque light blocker, and an ion implanted phase shifter.
Claim 16
Dependent Claim
37 words
The method as recited in claim 12 and wherein: ion implanting is controlled to achieve phase shift areas having an index of refraction that produces a 180° phase shift relative to light passed through the quartz substrate.
Claim 17
Dependent Claim
25 words
The method as recited in claim 13 and wherein: the ion dopant is selected from a class consisting of a species of boron or phosphorous.
Claim 18
Dependent Claim
62 words
The method as recited in claim 14 and further comprising: directing an incident light through the phase shift reticle onto a target wafer in a photolithography process to produce alternating dark areas by diffraction of light waves between a light transmission opening and an ion implant phase shifter in order to improve the resolution and depth of field of the photolithography process.
Claim 19
Dependent Claim
23 words
The method as recited in claim 15 and wherein: a reduction lens is placed between the reticle and a wafer to be photopatterned.
Claim 20
Dependent Claim
26 words
The method as recited in claim 16 and wherein: the wafer is stepped under the lens to expose the reticle pattern over the entire wafer surface.
Claim 21
Independent Claim
236 words
A method of forming a phase shifting reticle for semiconductor manufacture, comprising: coating a transparent substrate with an ion block material; patterning the ion block material with openings; ion bombarding through the openings, to the substrate to form ion implant areas in the substrate as phase shifters having an index of refraction different than an index of refraction of the transparent substrate with the ion bombarding controlled to achieve a predetermined phase shift of light; stripping the ion block; depositing an opaque film on the substrate and over the phase shifters; patterning the photoresist with opening with an opening over each phase shifter and an opening between each phase shifter; etching the opaque film through the openings to form openings through the opaque film to the phase shifters and to an area between each phase shifter such that an alternating pattern is formed of light transmission openings having opaque light blockers on either side alternating with self aligned phase shifters having opaque light blockers on either side; stripping the photo resist such that an opaque light blocker, a light transmission opening, an opaque light blocker, and a phase shifter are formed in a repetitive pattern; whereby incident light directed through a phase shifter is shifted 180° out of phase from light directed through an adjacent light transmission opening to produce a destructive interference for improving a resolution of an image defined by an opaque light blocker.
Claim 22
Independent Claim
236 words
A method of forming a phase shifting reticle for semiconductor manufacture, comprising: coating a transparent substrate with an ion block material; patterning the ion block material with openings; ion bombarding through the openings, to the substrate to form ion implant areas in the substrate as phase shifters having an index of refraction different than an index of refraction of the transparent substrate with the ion bombarding controlled to achieve a predetermined phase shift of light; stripping the ion block; depositing an opaque film on the substrate and over the phase shifters; patterning the photoresist with opening with an opening over each phase shifter and an opening between each phase shifter; etching the opaque film through the openings to form openings through the opaque film to the phase shifters and to an area between each phase shifter such that an alternating pattern is formed of light transmission openings having opaque light blockers on either side alternating with self aligned phase shifters having opaque light blockers on either side; stripping the photo resist such that an opaque light blocker, a light transmission opening, an opaque light blocker, and a phase shifter are formed in a repetitive pattern; whereby incident light directed through a phase shifter is shifted 180° out of phase from light directed through an adjacent light transmission opening to produce a destructive interference for improving a resolution of an image defined by an opaque light blocker.
Claim 23
Dependent Claim
35 words
The method as recited in claim 18 and wherein: the substrate is quartz; the opaque layer is chromium; and the ion dopant is selected from the group consisting of a species of boron or phosphorus.
Claim 24
Independent Claim
126 words
A method of forming a phase shifting reticle comprising: forming a first pattern of ion implant areas on a transparent substrate by ion bombardment of the substrate with an ion dopant selected to change an index of refraction of the substrate to form phase shifters for producing a phase shift of light; forming a second pattern of opaque light blockers on the transparent substrate with the opaque light blockers defining a predetermined image; and forming a third pattern of light transmission areas on the substrate with the first, second and third patterns self aligned such that light passed through the phase shifters is phase shifted relative to light passed through the light transmission areas for improving the image defined by the opaque light blockers during photopatterning.
Claim 25
Independent Claim
126 words
A method of forming a phase shifting reticle comprising: forming a first pattern of ion implant areas on a transparent substrate by ion bombardment of the substrate with an ion dopant selected to change an index of refraction of the substrate to form phase shifters for producing a phase shift of light; forming a second pattern of opaque light blockers on the transparent substrate with the opaque light blockers defining a predetermined image; and forming a third pattern of light transmission areas on the substrate with the first, second and third patterns self aligned such that light passed through the phase shifters is phase shifted relative to light passed through the light transmission areas for improving the image defined by the opaque light blockers during photopatterning.
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) | 1996-06-07 | 1996-12-07 | 1997-06-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-06-07 | 2000-12-07 | 2001-06-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-06-07 | 2004-12-07 | 2005-06-08 | $7700.00 | Window Closed / Lapsed |