Increasing Die Strength by Etching During or After Dicing
A semiconductor wafer having an active layer is mounted on a carrier with the active layer away from the carrier and at least partially diced on the carrier from a major surface of the semiconductor wafer. The at least partially diced semiconductor wafer is etched on the carrier from the said major surface with a spontaneous etchant to remove sufficient semiconductor material from a die produced from the at least partially diced semiconductor wafer to improve flexural bend strength of the die by removing at least some defects caused by dicing.
1 . A method of dicing a semiconductor wafer having an active layer comprising the steps of:
a. mounting the semiconductor wafer on a carrier with the active layer away from the carrier;
b. at least partially dicing the semiconductor wafer on the carrier from a major surface of the semiconductor wafer to form an at least partially diced semiconductor wafer; and
c. etching the at least partially diced semiconductor wafer on the carrier from the said major surface with a spontaneous etchant to remove sufficient semiconductor material from a die produced from the at least partially diced semiconductor wafer to improve flexural bend strength of the die.
2 . A method as claimed in claim 1 , wherein the step of at least partially dicing the semiconductor wafer comprises dicing the semiconductor wafer completely through the semiconductor wafer; and the step of etching the semiconductor wafer comprises etching sidewalls of the die, remaining portions of the die being masked from the spontaneous etchant by portions of the active layer on the die.
3 . A method as claimed in claim 1 , wherein the step of at least partially dicing the semiconductor wafer comprises partially dicing the semiconductor wafer along dicing lanes to leave portions of semiconductor material bridging the dicing lanes; and the step of etching the semiconductor wafer comprises etching sidewalls of the dicing lanes and etching away the portions of semiconductor material bridging the dicing lanes to singulate the die.
4 . A method as claimed in claim 1 , wherein the semiconductor wafer is a silicon wafer.
5 . A method as claimed in claim 1 , wherein the step of etching with a spontaneous etchant comprises etching with xenon difluoride.
6 . A method as claimed in claim 1 , wherein the step of etching with a spontaneous etchant comprises providing an etching chamber and etching the semiconductor wafer within the etching chamber.
7 . A method as claimed in claim 6 , wherein the step of etching with a spontaneous etchant within the etching chamber comprises cyclically supplying the chamber with spontaneous etchant and purging the etching chamber of spontaneous etchant for a plurality of cycles.
8 . A dicing apparatus for dicing a semiconductor wafer having an active layer comprising:
a. carrier means on which the semiconductor wafer is mountable with the active layer away from the carrier;
b. laser or mechanical sawing means arranged for at least partially dicing the semiconductor wafer on the carrier from a major surface of the semiconductor wafer to form an at least partially diced semiconductor wafer; and
c. etching means arranged to etch the at least partially diced semiconductor wafer on the carrier from the said major surface with a spontaneous etchant to remove sufficient semiconductor material from a die produced from the at least partially diced semiconductor wafer to improve flexural bend strength of the die.
9 . A dicing apparatus as claimed in claim 8 , wherein the dicing apparatus is arranged to dice a silicon wafer.
10 . A dicing apparatus as claimed in claim 8 , wherein the etching means is arranged to etch with xenon difluoride.
11 . A dicing apparatus as claimed in claim 8 , wherein the dicing apparatus further comprises an etching chamber arranged for etching the semiconductor wafer mounted on the carrier means within the etching chamber.
12 . A dicing apparatus as claimed in claim 8 , wherein the etching chamber is arranged cyclically to supply the chamber with spontaneous etchant and to purge the etching chamber of spontaneous etchant for a plurality of cycles.