Patent ID: 6660643
Filing Date: 2003-12-09
Classification: H01L,Y02E,Y02P

Abstract:
Method of etching the edges of a plurality of like semiconductor wafers of rectangular configuration for the purpose of removing micro-cracks at said edges, said method comprising assembling said plurality of wafers face-to-face in contact with each other so as to form a coin stack with the wafers having their edges in mutual alignment, providing a reaction chamber containing a plasma generator characterized by at least a pair of hollow gas discharge electrodes that are disposed adjacent one another and arranged so that gas streams discharged therefrom will converge on one another, forming a reactive plasma comprising reactive halogen ions by discharging converging gas streams from said electrodes and energizing said electrodes so as to create an electric discharge between said converging gas streams while the pressure within said chamber is at the level of atmospheric pressure, said reactive plasma comprising a first zone above and spaced from the region of said electrodes and said electric discharge that is characterized by a temperature in the order of 500Â° C. and a second zone below said first zone and proximate the region of said electrodes and said electric discharge that is characterized by a temperature substantially greater than the temperature of said first zone, positioning said coin stack in said chamber above said electrodes so that said wafers extend vertically and first edges of said wafers face down and extend to the level of said first zone but short of the level of said second zone, continuously moving said coin stack so that said first edges move in and out of said first zone repetitively and continuously with the time duration of each transit of said first edges in said first zone being limited so that said first edges are etched incrementally by reaction with said halogen ions, terminating movement of said coin stack, removing said coin stack from said chamber, reorienting said coin stack and repositioning said coin stack in said chamber above said electrodes so that said wafers still extend vertically but other edges of said wafers face down, continuously moving said coin stack so that said other edges move in and out of said first zone repetitively and continuously with the time duration of said other edges in said first zone being limited so that said other edges are etched incrementally by reaction with said halogen ions, and then terminating movement of said coin stack and removing said coin stack from said chamber.