US5698349A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Sub-resolution phase shift mask
Assignee: United Microelectronics Corp
•
Filing: 1996-06-21
•
Granted: 1997-12-16
•
Expires: 2016-06-21
Abstract
Abstract The invention describes the fabrication and use of a sub-resolution phase shift mask. The mask is formed using a single alignment step with all other alignment steps being accomplished by self alignment. This self alignment is made possible by using vertical anisotropic etching of an opaque material layer to form opaque spacers at the pattern edges of phase shifting material. The opaque spacers combine with phase shifting and other opaque regions of the mask to provide improved image resolution and depth of focus tolerance at the surface of an integrated circuit wafer.
Inventors
- 👤 Ming-Tzong Yang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 06:02
CPC Classifications
G; G03; G03F; G03F1/00; G03F1/26; G03F1/29
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
81 words
A phase shift mask, comprising: a transparent substrate; a patterned layer of first opaque material formed on said transparent substrate; a patterned layer of phase shifting material formed on said patterned layer of first opaque material to cover and extend beyond the edge of said patterned layer of first opaque material; and a patterned layer of second opaque material formed on said transparent substrate wherein said second opaque material forms spacers at said patterned layer of phase shifting material pattern edges.
Claim 2
Dependent Claim
81 words
A phase shift mask, comprising: a transparent substrate; a patterned layer of first opaque material formed on said transparent substrate; a patterned layer of phase shifting material formed on said patterned layer of first opaque material to cover and extend beyond the edge of said patterned layer of first opaque material; and a patterned layer of second opaque material formed on said transparent substrate wherein said second opaque material forms spacers at said patterned layer of phase shifting material pattern edges.
Claim 3
Dependent Claim
23 words
The phase shift mask of claim 1 wherein said transparent substrate is quartz with a thickness of between about 1 and 10 millimeters.
Claim 4
Dependent Claim
24 words
The phase shift mask of claim 1 wherein said first opaque material is chromium with a thickness of between about 1000 and 10,000 Angstroms.
Claim 5
Dependent Claim
15 words
The phase shift mask of claim 1 wherein said phase shifting material is silicon dioxide.
Claim 6
Dependent Claim
22 words
The phase shift mask of claim 1 wherein said phase shifting material has a thickness of between about 1000 and 5000 Angstroms.
Claim 7
Dependent Claim
32 words
The phase shift mask of claim 1 wherein said phase shifting material has a thickness, t, given by t=0.5 L/(n-1) (L=wavelength of light used, n=index of refraction of said phase shifting material).
Claim 8
Dependent Claim
26 words
The phase shift mask of claim 1 wherein said second opaque material spacers are sputtered chromium with a thickness of between about 300 and 3000 Angstroms.
Claim 9
Dependent Claim
34 words
The phase shift mask of claim 1 wherein said patterned layer of phase shifting material extends beyond the edge of said patterned layer of first opaque material by between about 500 and 5000 Angsttoms.
Claim 10
Dependent Claim
32 words
The phase shift mask of claim 1, wherein said patterned layer of phase shifting material is spaced from said transparent substrate between said patterned layer of first opaque material and said spacers.
Claim 11
Dependent Claim
31 words
The phase shift mask of claim 9, wherein upper surfaces of said spacers are closer to said transparent substrate than an upper surface of said patterned layer of phase shifting material.
Claim 12
Dependent Claim
26 words
The phase shift mask of claim 9, wherein the transparent substrate has a planar surface over a width of an opening in said phase shift mask.
Claim 13
Dependent Claim
20 words
The phase shift mask of claim 1, wherein said opaque spacers have a width between about 300 and 3000 Angstroms.
Claim 14
Dependent Claim
13 words
The phase shift mask of claim 12, wherein said opaque spacers are chromium.
References Cited (Backward Citations)
US5045417A
Cited
US5288568A
Cited
US5382483A
Cited
US5300379A
Cited
US5532089A
Cited
US5455131A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-12-15 | 2001-06-16 | 2001-12-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-12-15 | 2005-06-16 | 2005-12-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-12-15 | 2009-06-16 | 2009-12-16 | $7700.00 | Window Closed / Lapsed |