# US 5,830,533 A · Selective patterning of metallization on a dielectric substrate > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,830,533 A - Document ID: US5830533A - Status: Granted - Kind: A - Application number: 07/985,663 - Filed: 1992-12-04 - Granted: 1998-11-03 - Earliest claimed: 1991-05-28 - Assignees: Microelectronics and Computer Technology Corporation - Inventors: Charles W. C. Lin; Randy L. German - Web page: https://patentgrep.com/patent/US5830533A ## CPC - H05K 3/182: {characterised by the patterning method} - H10W 70/60: Insulating or insulated package substrates; Interposers; Redistribution layers (leadframes H10W70/40) - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS - H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10 ## Abstract A method of selectively fabricating metallization on a dielectric substrate is disclosed. A seed layer is sputtered on a polymer dielectric, a patterned photoresist mask is disposed over the seed layer, exposed portions of the seed layer are etched, the photoresist is stripped, and copper is deposited without a mask by electroless plating on the unetched seed layer to form well-adhering high density copper lines without exposing the photoresist to the electroless bath. ## Claims ### Claim 1 A method of selectively patterning metal on a dielectric substrate, comprising the following steps in the sequence set forth: depositing a seed layer on a dielectric substrate wherein the seed layer is autocatalytic to an electrically conductive metal whereas the dielectric substrate is non-autocatalytic to the metal; overlaying a resist mask on the seed layer wherein the resist mask has a pattern which covers portions of the seed layer whereas a plurality of openings in the resist mask expose other portions of the seed layer; etching the exposed portions of the seed layer; removing the resist mask thereby exposing the unetched portions of the seed layer which correspond to the pattern of the resist mask; and depositing the metal on the unetched portions of the seed layer without depositing the metal on the dielectric substrate and without using a mask wherein the deposited metal corresponds to the pattern and the seed layer provides adhesion between the dielectric substrate and the deposited metal. ### Claim 2 (depends on 1) The method of claim 1 wherein the electrically conductive metal is deposited by electroless deposition and is selected from the group consisting of copper, nickel, gold, silver, palladium and platinum. ### Claim 3 (depends on 1) The method of claim 1 wherein the electrically conductive metal is deposited by chemical vapor deposition and is selected from the group consisting of tungsten, aluminum, and copper. ### Claim 4 (depends on 1) The method of claim 1 wherein the seed layer comprises a lower layer of titanium, chromium or aluminum. ### Claim 5 (depends on 1) The method of claim 1 wherein the seed layer is deposited by sputtering. ### Claim 6 (depends on 1) The method of claim 1 wherein the seed layer is a metal selected from the group consisting of chromium, aluminum, copper, ceranium, nickel, gold, and titanium. ### Claim 7 (depends on 1) The method of claim 1 wherein the seed layer is a conductive polymer or a conductive powder. ### Claim 8 (depends on 1) The method of claim 1 wherein the resist mask is positive working photoresist. ### Claim 9 (depends on 1) The method of claim 1 wherein the resist mask is approximately 0.1 to 8 microns thick. ### Claim 10 (depends on 1) The method of claim 1, wherein between the steps of removing the resist mask and depositing the metal, an initiator material is coated over the unetched portions of the seed layer without contacting the dielectric substrate. ### Claim 11 (depends on 1) The method of claim 1 wherein the etch is a dry etch. ### Claim 12 (depends on 1) The method of claim 1 wherein the etch is a wet chemical etch. ### Claim 13 (depends on 1) The method of claim 1 wherein the dielectric substrate is a polymer. ### Claim 14 A method of selectively fabricating metallization on a polymer substrate, comprising the following steps in the sequence set forth: depositing an adhesive seed layer on a polymer substrate wherein the seed layer is autocatalytic to an electrically conductive metal whereas the polymer substrate is non-autocatalytic to the metal; overlaying a photoresist mask at least 0.1 microns thick on the seed layer; forming a pattern in the photoresist mask which covers portions of the seed layer wherein a plurality of openings in the photoresist mask expose other portions of the seed layer; etching the exposed portions of the seed layer; removing the photoresist mask thereby exposing the unetched portions of the seed layer which correspond to the pattern of the photoresist mask; and depositing the metal on the unetched portions of the seed layer without depositing the metal on the polymer substrate and without using a mask wherein the deposited metal corresponds to the pattern and the unetched seed layer provides adhesion between the deposited metal and the polymer substrate. ### Claim 15 (depends on 14) The method of claim 14 wherein the electrically conductive metal is deposited by electroless deposition, and the electrically conductive metal is selected from the group consisting of copper, nickel, gold, silver, palladium and platinum. ### Claim 16 (depends on 14) The method of claim 14 wherein the electrically conductive metal is deposited by chemical vapor deposition, and the electrically conductive metal is selected from the group consisting of tungsten, aluminum, and copper. ### Claim 17 (depends on 14) The method of claim 14 wherein the seed layer is copper and the deposited metal is electrolessly deposited copper. ### Claim 18 (depends on 14) The method of claim 14, further comprising applying an initiator to the unetched seed layer but not the polymer substrate after removing the photoresist but before depositing the metal. ### Claim 19 (depends on 18) The method of claim 18 wherein the initiator is deposited by immersion coating and is selected from the group consisting of palladium, gold, silver, zinc, platinum, copper and nickel. ### Claim 20 A method of electrolessly depositing copper in a pattern on a polymer layer, comprising the following steps in the sequence set forth: sputtering a seed layer on a planar polymer layer, the seed layer being autocatalytic to copper and comprising an adhesive bottom layer of titanium or chromium and a copper layer over the bottom layer whereas the polymer layer is non-autocatalytic to copper; overlaying a layer of positive working photoresist on the seed layer; patterning the photoresist to form a pattern which covers portions of the seed layer wherein a plurality of openings in the photoresist expose other portions of the seed layer; etching the exposed seed layer portions; stripping the photoresist thereby exposing the unetched portions of the seed layer which correspond to the pattern of the photoresist; and electrolessly depositing copper on the unetched seed layer without depositing the copper on the polymer layer wherein the copper is at least 5 microns thick and corresponds to the pattern with a line density of at least 300 lines per inch, and the seed layer provides adhesion between the deposited copper and the polymer layer. ### Claim 21 A method of selectively patterning metal on a dielectric substrate, comprising the following steps in the sequence set forth: depositing a seed layer on a dielectric substrate wherein the seed layer and the dielectric substrate are non-autocatalytic to an electrically conductive metal; overlaying a resist mask on the seed layer wherein the resist mask has a pattern which covers portions of the seed layer whereas a plurality of openings in the resist mask expose other portions of the seed layer; etching the exposed portions of the seed layer; removing the resist mask thereby exposing the unetched portions of the seed layer which correspond to the pattern of the resist mask; rendering the unetched portions of the seed layer catalytic to the metal; and depositing the metal on the unetched portions of the seed layer without depositing the metal on the dielectric substrate and without using a mask wherein the deposited metal corresponds to the pattern and the seed layer provides adhesion between the dielectric substrate and the deposited metal. ### Claim 22 (depends on 21) The method of claim 21 wherein the unetched portions of the seed layer are rendered catalytic to the metal by coating the unetched portions of the seed layer with an initiator material. ### Claim 23 (depends on 22) The method of claim 22 wherein the initiator material is coated over the unetched portions of the seed layer without being deposited on the dielectric substrate. ### Claim 24 (depends on 23) The method of claim 23 wherein the initiator material is coated by immersion coating. ### Claim 25 (depends on 21, 24) The method of claims 21 or 24 wherein the electrically conductive metal is deposited by electroless deposition. ### Claim 26 (depends on 25) The method of claim 25 wherein the resist mask is a positive working photoresist. ### Claim 27 (depends on 25) The method of claim 25 wherein the electrically conductive metal is copper and the initiator material is palladium.