US5731047A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multiple frequency processing to improve electrical resistivity of blind micro-vias
Assignee: Gore Enterprise Holdings Inc
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Filing: 1996-11-08
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Granted: 1998-03-24
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Expires: 2016-11-08
Abstract
Abstract A method of forming a blind-via in a laminated substrate by forming a first conductive layer. A dielectric layer is then formed on the first conductive layer. An exposed second conductive layer is formed on the dielectric layer, with the second conductive layer having a preformed aperture. The dielectric layer is laser drilled through to the first conductive layer to form a blind-via at a location within the preformed aperture of the second conductive layer using a plurality of laser pulses. Each laser pulse has a first energy density per pulse that is greater than an ablation threshold of the dielectric layer and less than an ablation threshold of the first conductive layer. The first conductive layer is then laser drilled for a predetermined number of pulses. Each of the predetermined number of pulses has a second energy density per pulse that is greater than an ablation threshold of the first conductive layer. The predetermined number of pulses cause the surface of the first conductive layer exposed by the laser drilling to become molten.
Inventors
- 👤 David B. Noddin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 18:16
CPC Classifications
H; H05; H05K; H05K3/00; H05K3/0011; H05K3/0017; H05K3/0026; H05K3/0032; H05K3/0035; B; B23; B23K; B23K26/00; B23K26/0006; B23K2103/00; B23K2103/16; B23K2103/30; B23K2103/42; H05K2203/00; H05K2203/05; H05K2203/0548; H05K2203/0554; H05K2203/11; H05K2203/1105; H05K2203/12; H05K2203/128; H05K3/46; H05K3/4644; H05K3/4652; H10; H10W; H10W90/00; H10W90/701; H10W90/721; H10W90/724
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
171 words
A method of forming a blind-via in a laminated substrate, comprising the steps of: forming a first conductive layer; forming a dielectric layer on the first conductive layer; forming an exposed second conductive layer on the dielectric layer, the second conductive layer having a preformed aperture; laser drilling through the dielectric layer to the first conductive layer to form a blind-via at a location within the preformed aperture of the second conductive layer using a plurality of laser pulses each having a first energy density per pulse, the first energy density per pulse being greater than an ablation threshold of the dielectric layer and less than an ablation threshold of the first conductive layer; and laser drilling the first conductive layer for a predetermined number of pulses each having a second energy density per pulse, the second energy density being greater than an ablation threshold of the first conductive layer, the predetermined number of pulses causing a surface of the first conductive layer exposed by the laser drilling to become molten.
Claim 2
Independent Claim
171 words
A method of forming a blind-via in a laminated substrate, comprising the steps of: forming a first conductive layer; forming a dielectric layer on the first conductive layer; forming an exposed second conductive layer on the dielectric layer, the second conductive layer having a preformed aperture; laser drilling through the dielectric layer to the first conductive layer to form a blind-via at a location within the preformed aperture of the second conductive layer using a plurality of laser pulses each having a first energy density per pulse, the first energy density per pulse being greater than an ablation threshold of the dielectric layer and less than an ablation threshold of the first conductive layer; and laser drilling the first conductive layer for a predetermined number of pulses each having a second energy density per pulse, the second energy density being greater than an ablation threshold of the first conductive layer, the predetermined number of pulses causing a surface of the first conductive layer exposed by the laser drilling to become molten.
Claim 3
Dependent Claim
16 words
The method according to claim 1, wherein an entrance width of the blind-via is <75 μm.
Claim 4
Dependent Claim
15 words
The method according to claim 2, wherein an aspect ratio of the blind-via is >1:1.
Claim 5
Dependent Claim
37 words
The method according to claim 3, further comprising the step of filling the blind-via with a conductive material, wherein an average resistance of a connection through the blind-via to the first conductive layer being about 2 mΩ.
Claim 6
Dependent Claim
29 words
The method according to claim 4, wherein a variance of the resistance of the connection through the blind-via to the first conductive layer is about 0.25 mΩ 2 .
Claim 7
Dependent Claim
34 words
The method according to claim 5, wherein the laser emits at a wavelength of 355 nm, and wherein the first energy density per pulse is between 0.5 J/cm 2 and 11 J/cm 2 inclusive.
Claim 8
Dependent Claim
19 words
The method according to claim 6, wherein the first energy density per pulse is nominally 5 J/cm 2 .
Claim 9
Dependent Claim
15 words
The method according to claim 7, wherein each pulse has a pulse width ≦100 ns.
Claim 10
Dependent Claim
34 words
The method according to claim 5, wherein the laser emits at a wavelength of 266 nm, and wherein the first energy density per pulse is between 0.5 J/cm 2 and 3 J/cm 2 inclusive.
Claim 11
Dependent Claim
19 words
The method according to claim 9, wherein the first energy density per pulse is nominally 2 J/cm 2 .
Claim 12
Dependent Claim
15 words
The method according to claim 10, wherein each pulse has a pulse width ≦100 ns.
Claim 13
Dependent Claim
18 words
The method according to claim 5, wherein the predetermined number of pulses is between 1 and 10 inclusive.
Claim 14
Dependent Claim
31 words
The method according to claim 12, wherein the laser emits at a wavelength of 355 nm, and wherein the second energy density per pulse is greater than 5 J/cm 2 .
Claim 15
Dependent Claim
19 words
The method according to claim 13, wherein the second energy density per pulse is nominally 11 J/cm 2 .
Claim 16
Dependent Claim
15 words
The method according to claim 14, wherein each pulse has a pulse width ≦100 ns.
Claim 17
Dependent Claim
31 words
The method according to claim 12, wherein the laser emits at a wavelength of 266 nm, and wherein the second energy density per pulse is greater than 1.5 J/cm 2 .
Claim 18
Dependent Claim
19 words
The method according to claim 16, wherein the second energy density per pulse is nominally 5 J/cm 2 .
Claim 19
Dependent Claim
15 words
The method according to claim 17, wherein each pulse has a pulse width ≦100 ns.
Claim 20
Dependent Claim
28 words
The method according to claim 5, wherein the steps of laser drilling through the dielectric layer and of laser drilling the first conductive layer are performed in situ.
Claim 21
Dependent Claim
79 words
The method according to claim 19, wherein the second conductive layer has a plurality of preformed apertures, and the method further comprises the step of forming a plurality of blind-vias by performing the step of laser drilling through the dielectric layer to the first conductive layer to form a blind-via at a location within at least two preformed apertures of the second conductive layer and the step of laser drilling the first conductive layer at each blind-via in situ.
Claim 22
Dependent Claim
29 words
The method according to claim 20, further comprising the step of laser drilling at least one through-via in the substrate using a plurality of laser pulses for each through-via.
Claim 23
Dependent Claim
49 words
The method according to claim 21, wherein the step of laser drilling the at least one through-via in the substrate includes the step of applying an energy density per pulse to the substrate for each through-via that is greater than an ablation energy density threshold of each conductive layer.
Claim 24
Dependent Claim
16 words
The method according to claim 22 wherein an entrance width of each through-via is ≦75 μm.
Claim 25
Dependent Claim
48 words
The method according to claim 23, wherein the step of laser drilling the plurality of through-vias in the substrate includes the step of applying an energy density per pulse to the substrate for each through-via that is greater than an ablation energy density threshold of each conductive layer.
Claim 26
Dependent Claim
39 words
The method according to claim 24, wherein the laser emits at a wavelength of 355 nm; and wherein the energy density per pulse applied to the substrate for laser drilling each through-via is greater than 5 J/cm 2 .
Claim 27
Dependent Claim
27 words
The method according to claim 25, wherein the energy density per pulse applied to the substrate for laser drilling each through-via is nominally 11 J/cm 2 .
Claim 28
Dependent Claim
15 words
The method according to claim 26, wherein each pulse has a pulse width ≦100 ns.
Claim 29
Dependent Claim
38 words
The method according to claim 24, wherein the laser emits at a wavelength of 266 nm; and wherein the energy density per pulse applied to the substrate for drilling each through-via is greater than 1.5 J/cm 2 .
Claim 30
Dependent Claim
26 words
The method according to claim 28, wherein the energy density per pulse applied to the substrate for drilling each through-via is nominally 5 J/cm 2 .
Claim 31
Dependent Claim
15 words
The method according to claim 29, wherein each pulse has a pulse width ≦100 ns.
References Cited (Backward Citations)
US3319317A
Cited
US3953566A
Cited
US3999004A
Cited
US4482516A
Cited
US4705762A
Cited
US4985296A
Cited
US5316803A
Cited
US5593606A
Cited
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