Patent ID: 7875230

Claim:
A method of forming a protective cap on a semiconductor wafer from a sheet of thermoplastic material, the method including: a) sandwiching the sheet of thermoplastic material between first and second molds formed from silicon or silicon alloy, the first and second molds having first and second molding surfaces respectively for molding the sheet of thermoplastic material placed therebetween which, when assembled, define at least one cavity therebetween, b) heating the sheet to a plastic state; c) urging the two molds together to plastically deform the sheet into the shape of the at least one cavity; d) drawing the first mold away from the sheet whilst maintaining the second mold in contact with the deformed sheet; e) placing the deformed sheet over microelectronic devices onto the semiconductor wafer; f) bonding the deformed sheet to the semiconductor wafer; and g) drawing the second mold away from the deformed sheet.