Methods of forming metallization patterns on beam lead semiconductor devices

Claim 3

A method according to claim 1, wherein the first layer of metal is electroplated to a greater thickness than the second layer of metal.

Claim 4

A method according to claim 2, wherein in the steps of selectively electroplating a first layer of metal and electroplating a second layer of metal the electroplated metal is gold.

Claim 5

A method according to claim 3, wherein depositing a conductive film on the surface of the wafer comprises depositing a titanium film and then a platinum film.

Claim 6

A method according to claim 4, wherein defining a pattern of the paths comprises selectively masking the platinum film to protect the platinum in areas of the film for forming the desired pattern, and then etching portions of the platinum film not masked in aqua regia.

Claim 7

A method according to claim 3, wherein the pattern is electrically coupled through selected portions of the wafer into the metal deposition circuit.

Claim 8

A method according to claim 6, wherein the pattern is comprised of repetitive distinct pattern portions, each pattern portion overlying a region of the wafer which forms a distinct semiconductor device to be separated from the wafer, wherein the connecting elements are beam leads extending beyond each device in the wafer, and wherein electrically coupling the pattern through selected portions of the wafer comprises protecting a surface of the wafer opposite the surface with the pattern defined thereon from physical access of electrolyte during plating, contacting the insulated surface of the wafer with a cathode plating electrode, and establishing continuity with the beam leads through such portions of the wafer which do not form the distinct semiconductor devices.

Claim 9

A method according to claim 6, wherein selectively electroplating a first layer of gold on portions of the pattern comprises: uniformly masking the entire surface of the deposited film on the wafer with an electrically insulating material; selectively opening windows in the mask to expose areas of the pattern where the supporting elements are to be deposited; connecting the conductive film to a cathode of a plating circuit; and plating the supporting elements onto the exposed areas of the pattern.

Claim 10

In a method of making beam lead semiconductor devices, wherein a first layer of titanium and a second layer of platinum are deposited on a surface of a semiconductor wafer, wherein the second layer is selectively etched to eliminate the platinum except for a pattern onto which conductors and beam leads are electrolytically gold plated, and wherein portions of the first layer not covered by the pattern are removed prior to gold plating the pattern, the improvement comprising: prior to gold plating the entire pattern 1. forming a masking layer over the entire surface of the wafer; 2. opening portions of the masking layer to expose portions of the pattern to accommodate the beam leads of the devices; 3. gold plating the beam leads to a desired thickness; and 4. removing the remaining masking layer from the surface of the wafer.

Claim 11

In a method of making beam lead semiconductor devices, wherein a first layer of titanium and a second layer of platinum are deposited on a surface of a semiconductor wafer, wherein the second layer is selectively etched to eliminate the platinum except for a pattern onto which conductors and beam leads are electrolytically gold plated, and wherein portions of the first layer not covered by the pattern are removed prior to gold plating the pattern, the improvement comprising: prior to gold plating the entire pattern 1. forming a masking layer over the entire surface of the wafer; 2. opening portions of the masking layer to expose portions of the pattern to accommodate the beam leads of the devices; 3. gold plating the beam leads to a desired thickness; and 4. removing the remaining masking layer from the surface of the wafer.