Wetting Behavior of Electrolyte in Fine Pitch Cu/Sn Bumping Process by Electroplating
This work reports on the wetting behavior of electrolyte in fine pitch Cu/Sn bumping process by electroplating. Three methods containing adding complex wetting agent to electrolyte, plasma treatment to photo-resist and ultrasonic vibration were taken to improve the wettability between electrolyte and related materials. Contact angles of electrolyte containing different amount of complex wetting agent with sputtered copper and photo-resist, before and after plasma treatment, were measured respectively. Certain amount of wetting agent can decrease the contact angles of photo-resist with electrolyte by nearly 20°, and wettability of photo-resist was further enhanced by plasma treatment that makes the contact angles decrease by about 40°. The contact angle of sputtered copper and electrolyte can be decreased by nearly 10°. SEM observations of cross sections and top view of bumps revealed that complex wetting agent help electrolyte get to the bottom of patterned figure quickly. In tin bumping process, this is the last step of wetting behavior for the bubbles in patterned figure would be discharged in electroplating process. While in copper bumping process, ultrasonic vibration was used to help remove the bubbles for the bubbles cannot be small enough by surface tension to overcome the adhesion effect of sidewall. Copper and tin bumps with a diameter of 60μm, height of 60μm and pitch of 180μm were fabricated by rational use of methods above.
Jin Jiang Jinglin Bi Zhuo Chen Ming Li Dali Mao Tadatomo Suga
Lab of Microelectronic Materials & Technology, State Key Laboratory of Metal Matrix CompositesSchool Department of Precision Engineering, School of Engineering, the University of Tokyo
国际会议
北京
英文
847-850
2009-08-10（万方平台首次上网日期，不代表论文的发表时间）