US 7,387,229 B2
Method of forming bumps on a wafer utilizing a post-heating operation, and an apparatus therefore
Makoto Imanishi, Neyagawa (Japan); Shoriki Narita, Hirakata (Japan); Masahiko Ikeya, Neyagawa (Japan); Shinji Kanayama, Kashihara (Japan); and Takaharu Mae, Hirakata (Japan)
Assigned to Matsushita Electric Industrial Co., Ltd., Osaka (Japan)
Filed on Jan. 22, 2004, as Appl. No. 10/761,412.
Application 10/761412 is a division of application No. 09/719768, filed on Dec. 18, 2000, granted, now 6,787,391.
Prior Publication US 2004/0149803 A1, Aug. 05, 2004
Int. Cl. B23K 37/04 (2006.01)
U.S. Cl. 228—8  [228/49.5; 438/108] 7 Claims
OG exemplary drawing
 
1. A bump forming apparatus comprising:
a bonding stage for supporting a semiconductor wafer and for heating the semiconductor wafer to a temperature for forming bumps on electrodes on a circuit of the semiconductor wafer;
a bump forming head for forming the bumps on the electrodes of the semiconductor wafer;
a load and transfer device for placing the semiconductor wafer on and removing the semiconductor wafer from said bonding stage;
a controller programmed to operate said bonding stage and said load and transfer device so as to perform a post-heating operation on the semiconductor wafer after the bumps are formed on the semiconductor wafer to thereby control a temperature drop of the semiconductor wafer, said controller being operable to control the post-heating operation on the semiconductor wafer by controlling said load and transfer device and said bonding stage so that the semiconductor wafer is positioned by said load and transfer device at a cooling position above said bonding stage while said bonding stage is heated to the temperature for forming the bumps such that the semiconductor wafer does not contact said bonding stage when in the cooling position; and
a wafer temperature control device programmed to operate a temperature difference between a temperature at a bonding stage-contact face of the semiconductor wafer and a temperature at a circuit formation face of the semiconductor wafer opposite to the bonding stage-contact face before the bump formation is performed and after the semiconductor wafer is positioned on said bonding stage, said wafer temperature control device being operable to control the temperature difference to be within a warpage non-generation temperature difference range so that a warpage of the semiconductor wafer is restricted to a level not obstructing the bump formation.