Patent EP0720225A2 successfully refreshed from Google Patents.
EP0720225A2
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EP
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Lateral power MOSFET having metal strap layer to reduce distributed resistance and method of fabricating the same
Assignee: Vishay Siliconix Inc
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Filing: 1995-12-29
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Granted: —
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Expires: 2015-12-29
Abstract
Abstract To reduce the distributed resistance in an integrated circuit die, a relatively thick metal strap layer is deposited on a bus or other conductive path in the top metal layer. The metal strap layer is formed by etching a longitudinal channel in the passivation layer over the bus and plating a thick metal layer, preferably nickel, in the channel. The metal strap layer dramatically reduces the resistance of the bus. <IMAGE> <IMAGE> <IMAGE>
Inventors
- 👤 Richard K. Williams
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 21:33
CPC Classifications
H; H10; H10D; H10D64/00; H10D64/20; H10D64/23; H10D64/251; H10D64/252; H10D30/00; H10D30/60; H10D30/601; H10D30/603; H10D30/64; H10D30/66; H10D30/663; H10D62/00; H10D62/10; H10D62/17; H10D62/213; H10D62/221; H10D62/235; H10D62/299; H10D62/307; H10D64/257; H10W; H10W20/00; H10W20/40; H10W20/482; H10W20/484; H10W72/00; H10W72/01; H10W72/019; H10D30/65; H10W72/071; H10W72/075; H10W72/50; H10W72/531; H10W72/536; H10W72/541; H10W72/5445; H10W72/551; H10W72/552; H10W72/5522; H10W72/5524; H10W72/59; H10W72/90; H10W72/921; H10W72/923; H10W72/926; H10W72/931; H10W72/932; H10W72/934; H10W72/951; H10W72/952; H10W90/00; H10W90/701; H10W90/751; H10W90/754
Claims Analysis
Total Claims: 48
Claim 1
Independent Claim
73 words
An integrated circuit die comprising: a first metal conductive path; a first metal strap layer formed on a surface of said first metal conductive path, said first metal conductive path and said first metal strap layer being for conducting a current flow primarily in a lateral direction with respect to said die; and a passivation layer extending laterally over a surface of said die, said first metal strap layer transecting said passivation layer.
Claim 2
Dependent Claim
44 words
The integrated circuit die of claim 1, wherein a side edge of said first metal conductive path extends laterally beyond a side edge of said first metal strap layer said passivation layer covering a portion of said surface of said first metal conductive path.
Claim 3
Dependent Claim
24 words
The integrated circuit die of claim 2, wherein said passivation layer abuts a portion of said side edge of said first metal strap layer.
Claim 4
Dependent Claim
21 words
The integrated circuit die of claim 1, 2 or 3, wherein said first metal strap layer comprises a layer of nickel.
Claim 5
Dependent Claim
29 words
The integrated circuit die of claim 1, 2, 3 or 4, wherein said first metal strap layer comprises an adhesion layer in contact with said first metal conductive path.
Claim 6
Dependent Claim
27 words
The integrated circuit die of claim 1, wherein said first metal strap layer comprises a surface layer covering a top surface of said first metal strap layer.
Claim 7
Dependent Claim
13 words
The integrated circuit die of claim 6, wherein said surface layer comprises gold.
Claim 8
Dependent Claim
68 words
The integrated circuit die of claim 1, wherein said first metal conductive path is included in a top metal layer, said die further comprising a lower metal layer which includes at least a second metal conductive path and a via extending between said first metal conductive and said second metal conductive path so as to form an electrically conductive connection between said first and second metal conductive paths.
Claim 9
Dependent Claim
71 words
The integrated circuit die of claim 8, wherein said top metal layer further comprises a third metal conductive path and said lower metal layer further comprises a fourth metal conductive path substantially parallel to said second metal conductive path, a second via extending between said third metal conductive path and said fourth metal conductive path so as to form an electrically conductive connection between said third and fourth metal conductive paths.
Claim 10
Dependent Claim
28 words
The integrated circuit die of claim 9, wherein said second and fourth metal conductive paths are disposed diagonally with respect to said first and second metal conductive paths.
Claim 11
Dependent Claim
12 words
The integrated circuit die of any preceding claim further comprising a MOSFET.
Claim 12
Dependent Claim
14 words
The integrated circuit die of claim 11, wherein said MOSFET is a lateral device.
Claim 13
Dependent Claim
17 words
The integrated circuit die of claim 11 or 12, wherein said die comprises a quasi-vertical double-diffused MOSFET.
Claim 14
Dependent Claim
14 words
The integrated circuit die of claim 11, wherein said MOSFET is an N-channel device.
Claim 15
Dependent Claim
18 words
The integrated circuit die of claim 14, wherein said MOSFET is formed in a P-well in said die.
Claim 16
Dependent Claim
20 words
The integrated circuit die of claim 11 or 14, wherein a drain region in said MOSFET includes a lightly-doped region.
Claim 17
Dependent Claim
25 words
The integrated circuit die of claim 11, wherein said MOSFET includes a body contact region which is shorted to a source region of said MOSFET.
Claim 18
Dependent Claim
14 words
The integrated circuit die of claim 11, wherein said MOSFET is a P-channel device.
Claim 19
Dependent Claim
18 words
The integrated circuit die of claim 18, wherein said MOSFET is formed in an N-well in said die.
Claim 20
Dependent Claim
32 words
The integrated circuit die of any preceding claim further comprising a second metal conductive path, each metal conductive path having fingers that are interdigitated with fingers of the other metal conductive path.
Claim 21
Dependent Claim
17 words
The integrated circuit die of any preceding claim, wherein said strap layer is formed in longitudinal segments.
Claim 22
Dependent Claim
18 words
The integrated circuit die of any one of claims 5 to 21, wherein said adhesion layer comprises zinc.
Claim 23
Dependent Claim
15 words
The integrated circuit die of claim6, further comprising a wire bonded to said surface layer.
Claim 24
Dependent Claim
12 words
The integrated circuit die of claim 23, wherein said wire comprises gold.
Claim 25
Dependent Claim
12 words
The integrated circuit die of claim 23, wherein said wire comprises aluminium.
Claim 26
Dependent Claim
29 words
The integrated circuit die of any preceding claim, wherein said metal strap is located only in areas of said die where there is an opening in said passivation layer.
Claim 27
Dependent Claim
63 words
The integrated circuit die of any preceding claim further comprising a second metal conductive path and a second metal strap layer formed on a surface of said second metal conductive path, said first metal conductive path and said first metal strap layer forming a ground bus and said second metal conductive path and said second metal strap layer forming a supply voltage bus.
Claim 28
Dependent Claim
90 words
A process of fabricating an integrated circuit die comprising the following steps: forming a semiconductor device in a semiconductor substrate; forming an insulating layer over said substrate; forming a conductive path over said insulating layer for making electrical contact with said semiconductor device; forming a passivation layer over said insulating layer and said conductive path; etching said passivation layer so as to form a longitudinal channel over said conductive path and thereby create an exposed surface of said conductive path; and depositing a metal strap layer on said exposed surface.
Claim 29
Dependent Claim
19 words
The process of claim 28, wherein the step of etching the passivation layer is performed with a wet etchant.
Claim 30
Dependent Claim
19 words
The process of claim 28, wherein the step of etching the passivation layer is performed with a dry etchant.
Claim 31
Dependent Claim
20 words
The process of claim 28, wherein the step of etching the passivation layer is performed with a reactive ion etch.
Claim 32
Dependent Claim
24 words
The process of any one of claims 28 to 31, wherein the step of depositing said metal strap layer includes plating a nickel layer.
Claim 33
Dependent Claim
24 words
The process of claim 32, wherein the step of depositing said metal strap layer includes plating a layer of zinc on said conductive path.
Claim 34
Dependent Claim
28 words
The process of any one of claims 28 to 31, wherein the step of depositing said metal strap layer includes plating a gold layer on said nickel layer.
Claim 35
Dependent Claim
25 words
The process of claim 28, wherein the step of etching the passivation layer includes etching a pad for attaching the bonding wire to said die.
Claim 36
Dependent Claim
27 words
The process of claim 28, wherein the step of depositing said metal strap layer includes depositing an adhesion layer which overlaps an edge of said passivation layer.
Claim 37
Dependent Claim
41 words
The process of claim 36, wherein the step of depositing the adhesion layer includes depositing a metal layer on said exposed surface and on said passivation layer and then etching said metal layer to a size larger than said longitudinal channel.
Claim 38
Dependent Claim
17 words
The process of claim 37, or the die of claim 5, wherein said adhesion layer comprises titanium.
Claim 39
Dependent Claim
11 words
The process of claim 37, wherein said adhesion layer comprises zinc.
Claim 40
Dependent Claim
49 words
An integrated circuit die comprising a conductive path for conducting a current flow primarily in a lateral direction with respect to said die and a first metal strap layer formed on a surface of said metal conductive path, said first metal strap layer being more than 12 µm thick.
Claim 41
Dependent Claim
27 words
The integrated circuit die of any one of claims 1 to 27 or claim 40, wherein said first metal strap layer is less than 25 µm thick.
Claim 42
Dependent Claim
27 words
The integrated circuit die of any one of claims 1 to 27 or claim 40, wherein said first metal strap layer is more than 20 µm thick.
Claim 43
Dependent Claim
27 words
The integrated circuit die of any one of claims 1 to 27 or claim 42, wherein said first metal strap layer is less than 30 µm thick.
Claim 44
Dependent Claim
69 words
An integrated circuit die comprising a bus for carrying a current in a lateral direction across said die and a passivation layer which overlies electronic components within said die, said bus having a bottom surface which is located at a level below an upper surface of said passivation layer and a top surface which is located at a level which is above said upper surface of said passivation layer.
Claim 45
Dependent Claim
59 words
The integrated circuit die of claim 44, wherein said bus comprises a relatively thin lower layer which is located below said upper surface of said passivation layer and a relatively thick upper layer having a bottom surface located below said upper surface of said passivation layer and a top surface located above said upper surface of said passivation layer.
Claim 46
Dependent Claim
22 words
The integrated circuit die of claim 45, wherein said bus further comprises an adhesion layer located between said lower and upper layers.
Claim 47
Dependent Claim
20 words
The integrated circuit die of claim 45, wherein said bus further comprises a bonding layer located above said upper layer.
Claim 48
Dependent Claim
21 words
The integrated circuit die of claim 44, wherein a vertical dimension of said bus is equal to 12 µm or more.
References Cited (Backward Citations)
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