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US4674176A
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Planarization of metal films for multilevel interconnects by pulsed laser heating
Assignee: United States Department of Energy
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Filing: 1985-06-24
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Granted: 1987-06-23
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Expires: 2005-06-24
Abstract
Abstract In the fabrication of multilevel integrated circuits, each metal layer is planarized by heating to momentarily melt the layer. The layer is melted by sweeping laser pulses of suitable width, typically about 1 microsecond duration, over the layer in small increments. The planarization of each metal layer eliminates irregular and discontinuous conditions between successive layers. The planarization method is particularly applicable to circuits having ground or power planes and allows for multilevel interconnects. Dielectric layers can also be planarized to produce a fully planar multilevel interconnect structure. The method is useful for the fabrication of VLSI circuits, particularly for wafer-scale integration.
Inventors
- 👤 David B. Tuckerman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 15:10
CPC Classifications
H; H10; H10P; H10P34/00; H10P34/40; H10P34/42; Y; Y10; Y10S; Y10S148/00; Y10S148/093
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
84 words
In a method of fabricating an integrated circuit structure having a thin metal layer deposited on an insulating layer or substrate, the step of planarizing the metal layer by heating the metal layer to momentarily melt the layer for a time sufficient to substantially eliminate topographic variations of less than a preselected spatial period to produce a flat surface on the metal layer without reacting or alloying the metal layer with the insulating layer or substrate, the planarizing occuring prior to patterning the layer.
Claim 2
Dependent Claim
84 words
In a method of fabricating an integrated circuit structure having a thin metal layer deposited on an insulating layer or substrate, the step of planarizing the metal layer by heating the metal layer to momentarily melt the layer for a time sufficient to substantially eliminate topographic variations of less than a preselected spatial period to produce a flat surface on the metal layer without reacting or alloying the metal layer with the insulating layer or substrate, the planarizing occuring prior to patterning the layer.
Claim 3
Dependent Claim
14 words
The method of claim 1 for the fabrication of a multilevel integrated circuit structure.
Claim 4
Dependent Claim
33 words
The method of claim 1 wherein the duration of the melt is sufficient to melt the metal without vaporization, allow metal flow over a preselected area, and prevent damage to any underlying layer.
Claim 5
Dependent Claim
23 words
The method of claim 1 wherein heating the metal layer is performed by applying pulsed laser radiation to the surface of the layer.
Claim 6
Dependent Claim
17 words
The method of claim 3 wherein the duration of the melt is less than about 1 millisecond.
Claim 7
Dependent Claim
20 words
The method of claim 4 wherein the pulsed laser radiation has a pulse duration of less than about one millisecond.
Claim 8
Dependent Claim
24 words
The method of claim 4 further including stepping the pulsed laser radiation over the surface of tne metal in a series of incremental steps.
Claim 9
Dependent Claim
22 words
The method of claim 4 for a gold layer wherein the laser radiation has a wavelength of less than about 650 nm.
Claim 10
Dependent Claim
31 words
The method of claim 6 for a gold layer of about 1 micron in thickness wherein the pulse duration is in the range of about 10 nanoseconds to about 1 microsecond.
Claim 11
Dependent Claim
18 words
The method of claim 7 wherein a single pulse of laser radiation is applied at each incremental step.
Claim 12
Dependent Claim
19 words
The method of claim 7 wherein a plurality of pulses of laser radiation are applied at each incremental step.
Claim 13
Independent Claim
61 words
A method of fabricating an electrical interconnection network, comprising: forming in sequence a plurality of alternating layers of metals and dielectric materials; planarizing each metal layer to produce a flat surface prior to patterning the layer and prior to forming an additional dielectric layer; patterning each metal layer and dielectric layer in a preselected pattern prior to forming an additional layer.
Claim 14
Independent Claim
61 words
A method of fabricating an electrical interconnection network, comprising: forming in sequence a plurality of alternating layers of metals and dielectric materials; planarizing each metal layer to produce a flat surface prior to patterning the layer and prior to forming an additional dielectric layer; patterning each metal layer and dielectric layer in a preselected pattern prior to forming an additional layer.
Claim 15
Dependent Claim
30 words
The method of claim 12 wherein the step of planarizing each metal layer is performed by heating the metal layer to momentarily melt the layer to produce a flat surface.
Claim 16
Dependent Claim
28 words
The method of claim 12 further including: forming the metal layers of a low melting point metal; forming the dielectric layers of a high temperature refractory dielectric material.
Claim 17
Dependent Claim
49 words
The method of claim 12 further including forming the metal layers of gold; forming the dielectric layers of SiO 2 or glass; and forming an adhesion layer of an oxygen active metal alloy between the gold and dielectric layers which is much thinner than the gold or dielectric layers.
Claim 18
Dependent Claim
23 words
The method of claim 12 further including planarizing each dielectric layer prior to pattering the dielectric layer or forming an additional metal layer.
Claim 19
Dependent Claim
36 words
The method of claim 13 wherein the duration of the melt is sufficient to melt the metal layer without vaporizing the layer or damaging any underlying layer and to allow metal flow over a preselected area.
Claim 20
Dependent Claim
21 words
The method of claim 13 wherein the step of planarization is performed by irradiating the layer with pulses of laser radiation.
Claim 21
Dependent Claim
29 words
The method of claim 15 wherein the step of planarization is performed by irradiating the gold layers with laser pulses having a wavelength of less tnan about 650 nm.
Claim 22
Dependent Claim
17 words
The method of claim 17 wherein the duration of the melt is less than about 1 millisecond.
Claim 23
Dependent Claim
35 words
The method of claim 17 for a gold layer of the order of 1 micron in thickness wherein the duration of the melt is in tne range of about 10 nanoseconds to about 1 microsecond.
Claim 24
Dependent Claim
26 words
The method of claim 18 wherein the step of planarization is performed by irradiating the layer with laser pulses of less than about 1 millisecond duration.
Claim 25
Dependent Claim
23 words
The method of claim 18 further including stepping the pulses of laser radiation over the metal layer in a series of incremental steps.
Claim 26
Dependent Claim
32 words
The method of claim 22 for a gold layer of the order of 1 micron thickness, wherein the pulse duration is in the range of about 10 nanoseconds to about 1 microsecond.
Claim 27
Dependent Claim
15 words
The method of claim 23 wherein a single pulse is applied at each incremental step.
Claim 28
Dependent Claim
16 words
The method of claim 23 wherein a plurality of pulses are applied at each incremental step.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-06-22 | 1990-12-22 | 1991-06-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-06-22 | 1994-12-22 | 1995-06-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-06-22 | 1998-12-22 | 1999-06-23 | $7700.00 | Window Closed / Lapsed |