US5871888A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of forming multiple-layer microlenses and use thereof
Assignee: Imec
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Filing: 1996-07-11
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Granted: 1999-02-16
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Expires: 2016-07-11
Abstract
Abstract A method of forming refractive microlenses which includes the steps of depositing or growing a first transparent layer on a substrate; depositing or growing a second transparent layer on the first transparent layer; forming a columnar structure in the second transparent layer; forming a pillar in the first transparent layer using the columnar structure as a mask, whereby the pillar is self-aligned under the columnar structure and the pillar has a cross-sectional area smaller than or equal to the cross-sectional area of the columnar structure; thereafter reflowing the second transparent layer of the columnar structure while the pillar remains essentially unaltered, whereby a structure is formed on top of the pillar, the structure having a ground plane with an area smaller than or equal to the original cross-sectional area of the columnar structure; and solidifying said structure. Due to the surface tension, the pillar underneath the microlens confines the reflow of the microlens to an area smaller or equal to the original cross-sectional area of the lens-forming columnar structure. A major effect of this is that the microlens has a strong curvature, and hence, a large numerical aperture.
Inventors
- 👤 Paul Heremans
- 👤 Gustaaf Borghs
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 01:22
CPC Classifications
G; G02; G02B; G02B3/00; G02B3/0006; G02B3/0012; G02B3/0018; G03; G03F; G03F7/00; G03F7/0005; G03F7/001; G02B3/0037; G02B3/0056
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
135 words
A method of forming a refractive microlens, comprising the steps of: forming one or more first transparent layers on a substrate; forming one or more second transparent layers on said first transparent layer; forming a columnar structure in said second transparent layer; forming a pillar in said first transparent layer using said columnar structure as a mask; said pillar having a cross-sectional area at an interface bewtween said pillar and said columnar structure smaller than or equal to the cross-sectional area of said columnar structure at said interface; reflowing said second transparent layer of said columnar structure while said pillar remains essentially unaltered, thereby forming a structure on top of said pillar, said microlens structure having a cross-sectional area not greater than the original cross-sectional area of said columnar structure; and solidifying said microlens structure.
Claim 2
Independent Claim
135 words
A method of forming a refractive microlens, comprising the steps of: forming one or more first transparent layers on a substrate; forming one or more second transparent layers on said first transparent layer; forming a columnar structure in said second transparent layer; forming a pillar in said first transparent layer using said columnar structure as a mask; said pillar having a cross-sectional area at an interface bewtween said pillar and said columnar structure smaller than or equal to the cross-sectional area of said columnar structure at said interface; reflowing said second transparent layer of said columnar structure while said pillar remains essentially unaltered, thereby forming a structure on top of said pillar, said microlens structure having a cross-sectional area not greater than the original cross-sectional area of said columnar structure; and solidifying said microlens structure.
Claim 3
Dependent Claim
24 words
The method of claim 1, wherein said first transparent layer is SiO 2 or Si 3 N 4 or ZnSe or InSnO x .
Claim 4
Dependent Claim
13 words
The method of claim 1, wherein said first transparent layer is a resin.
Claim 5
Dependent Claim
15 words
The method of claim 1, wherein said first transparent layer is a photoresist or polyimide.
Claim 6
Dependent Claim
31 words
The method of claim 4, wherein said pillar is formed in said photoresist by a sequence of a photolithographic step and a removal step using said columnar structure as a mask.
Claim 7
Dependent Claim
14 words
The method of claim 1, wherein said second transparent layer is a thermoplastic material.
Claim 8
Dependent Claim
13 words
The method of claim 6, wherein said thermoplastic material is a thermoplastic resin.
Claim 9
Dependent Claim
12 words
The method of claim 7, wherein said thermoplastic resin is a photoresist.
Claim 10
Dependent Claim
25 words
The method of claim 8, wherein said columnar structure is formed in said photoresist by a sequence of a photolithographic step and a removal step.
Claim 11
Dependent Claim
28 words
The method of claim 1, wherein during said formation of said columnar structure, said columnar structure is aligned with respect to an optoelectronic device formed in said substrate.
Claim 12
Dependent Claim
43 words
The method of claim 10, wherein the height of said pillar is adjusted with respect to the position of the active layer of said optoelectronic device in order to match the focus distance of said microlens with said position of said active layer.
Claim 13
Dependent Claim
20 words
The method of claim 10, wherein said microlens is one of a plurality of microlenses aligned on said optoelectronic device.
Claim 14
Dependent Claim
13 words
The method of claim 1, wherein the microlens has a large numerical aperture.
Claim 15
Dependent Claim
15 words
The method of claim 1, wherein the microlens shapes the output beam of optoelectronic emitters.
Claim 16
Dependent Claim
13 words
The method of claim 1, wherein said first transparent layer planarizes the substrate.
Claim 17
Dependent Claim
57 words
The method of claim 1, wherein: said step of forming one or more first transparent layers is performed by depositing the one or more first transparent layers on said substrate; and said step of forming one or more second transparent layers is performed by depositing the one or more second transparent layers on the first transparent layer.
Claim 18
Dependent Claim
26 words
The method of claim 16, further comprising the step of flooding said first photoresist layer with light prior to said deposition of said second photoresist layer.
Claim 19
Dependent Claim
57 words
The method of claim 1, wherein said step of forming one or more first transparent layers is performed by growing the one or more first transparent layers on said substrate; and said step of forming one or more second transparent layers is performed by growing the one or more second transparent layers on the first transparent layer.
Claim 20
Dependent Claim
20 words
The method of claim 1, wherein said microlens structure formed on top of said pillar is of an ellipsoidal shape.
Claim 21
Dependent Claim
11 words
The method of claim 1, wherein said substrate is a semiconductor.
Claim 22
Dependent Claim
30 words
The method of claim 1, wherein during said reflow said microlens structure is formed to have a shape which is at least half of either an ellipsoid or a sphere.
Claim 23
Independent Claim
126 words
A method of forming a refractive microlens comprising the steps of: forming one or more first photoresist layers on a substrate; forming one or more second photoresist layers on said first transparent layer; patterning by photolithogrtaphic techniques a columnar structure in said second photoresist layer; patterning by photolithographyic techniques a pillar in said first photoresist layer using said columnar structure as a mask, thereby self-aligning said pillar under said columnar structure; reflowing said second photoresist layer of said columnar structure while said pillar remains essentially unaltered, thereby forming a microlens structure on top of said pillar, said microlens structure having a ground plane with an area smaller than or equal to the original cross-sectional ground plane area of said columnar structure; and solidifying said microlens structure.
Claim 24
Independent Claim
126 words
A method of forming a refractive microlens comprising the steps of: forming one or more first photoresist layers on a substrate; forming one or more second photoresist layers on said first transparent layer; patterning by photolithogrtaphic techniques a columnar structure in said second photoresist layer; patterning by photolithographyic techniques a pillar in said first photoresist layer using said columnar structure as a mask, thereby self-aligning said pillar under said columnar structure; reflowing said second photoresist layer of said columnar structure while said pillar remains essentially unaltered, thereby forming a microlens structure on top of said pillar, said microlens structure having a ground plane with an area smaller than or equal to the original cross-sectional ground plane area of said columnar structure; and solidifying said microlens structure.
Claim 25
Dependent Claim
11 words
The method of claim 22, wherein said substrate is a semiconductor.
Claim 26
Dependent Claim
13 words
The method of claim 22, wherein said microlens structure has an ellipsoidal shape.
Claim 27
Dependent Claim
57 words
The method of claim 22, wherein: said step of forming one or more first photoresist layers is performed by depositing the one or more first photoresist layers on said substrate; and said step of forming one or more second photoresist layers is performed by depositing the one or more second photoresist layers on the first photoresist layer.
Claim 28
Independent Claim
66 words
A method of forming a refractive microlens, comprising the steps of: spinning a layer of positive pillar-forming photoresist on a substrate; heating the pillar-forming layer; flooding the pillar-forming layer uniformly with light; spinning a layer of positive lens-forming photoresist on the pillar-forming layer; heating the lens-forming layer; illuminating the lens-forming layer through a pattern mask; developing the total photoresist layer structure; reflowing the positive lens-forming photoresist.
Claim 29
Independent Claim
66 words
A method of forming a refractive microlens, comprising the steps of: spinning a layer of positive pillar-forming photoresist on a substrate; heating the pillar-forming layer; flooding the pillar-forming layer uniformly with light; spinning a layer of positive lens-forming photoresist on the pillar-forming layer; heating the lens-forming layer; illuminating the lens-forming layer through a pattern mask; developing the total photoresist layer structure; reflowing the positive lens-forming photoresist.
Claim 30
Independent Claim
139 words
A method of forming a refractive microlens, comprising the steps of: forming one or more first transparent layers on a substrate; forming one or more second transparent layers on said first transparent layer; thereafter, a forming a columnar structure in said second transparent layer; forming a pillar in said first transparent layer using said columnar structure as a mask, said pillar having a cross-sectional area at an interface between said pillar and said columnar structure smaller than or equal to the cross-sectional area of said columnar structure at said interface; thereafter, reflowing said second transparent layer of said columnar structure while said pillar remains essentially unaltered, thereby forming a microlens structure on top of said pillar, said microlens structure having a cross-sectional area not greater than the original cross-sectional area of said columnar structure; and solidifying said microlens structure.
Claim 31
Independent Claim
139 words
A method of forming a refractive microlens, comprising the steps of: forming one or more first transparent layers on a substrate; forming one or more second transparent layers on said first transparent layer; thereafter, a forming a columnar structure in said second transparent layer; forming a pillar in said first transparent layer using said columnar structure as a mask, said pillar having a cross-sectional area at an interface between said pillar and said columnar structure smaller than or equal to the cross-sectional area of said columnar structure at said interface; thereafter, reflowing said second transparent layer of said columnar structure while said pillar remains essentially unaltered, thereby forming a microlens structure on top of said pillar, said microlens structure having a cross-sectional area not greater than the original cross-sectional area of said columnar structure; and solidifying said microlens structure.
References Cited (Backward Citations)
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