Wire Bonds Having Pressure-Absorbing Balls

Abstract

A semiconductor device with a chip having at least one metallic bond pad ( 101 ) over weak insulating material ( 102 ). In contact with this bond pad is a flattened metal ball ( 104 ) made of at least 99.999% pure metal such as gold, copper, or silver. The diameter ( 104 a ) of the flattened ball is less than or equal to the diameter ( 103 a ) of the bond pad. A wire ( 110 ) is connected to the bond pad so that the wire has a thickened portion ( 111 ) conductively attached to the flattened metal ball. The wire is preferably made of composed metal such as gold alloy. The composition of the flattened ball is softer than the wire. This softness of the flattened ball protects the underlying insulator against damage caused by pressure or stress, when the composed ball is attached.

1 . A semiconductor device comprising:
 a semiconductor chip having a metallic bond pad over insulator material;   a flattened metallic free air ball having a first center line in contact with the bond pad; and   a contact ball at an end of a wire having a second center line misaligned to the first center line affixed on the flattened metallic free air ball.   
     
     
         2 . The device according to  claim 1  wherein the flattened metallic free air ball has a bottom area not greater than the bond pad. 
     
     
         3 . The device according to  claim 1  wherein the flattened metallic free air comprises a metal of at least 99.999% purity, the metal including gold, copper, or silver. 
     
     
         4 . The device according to  claim 1  wherein the wire comprises composed metal including gold alloy, copper alloy, or copper-coated gold. 
     
     
         5 . The device according to  claim 1  wherein the contact ball is a second flattened free air ball. 
     
     
         6 . The device according to  claim 1  further having an electrically conducting line spaced from the bond pad by a gap, and the wire is spanning the gap by means of a loop of controlled shape to connect the bond pad and the conducting line. 
     
     
         7 . The device according to  claim 1  wherein the insulator material comprises a low-k dielectric. 
     
     
         8 . The device according to  claim 1  wherein the flattened metallic free air ball is softer than the contact ball.