SUSS MicroTec LithoPack300: 300 mm Lithography Cluster for Wafer Level Packaging

SUSS MicroTec's newest product offering is a 300 mm lithography cluster which consists of an MA300 mask aligner module linked to an ACS300 spin-coating system. The tool, called the LithoPack300 (LP300) is specifically designed for wafer bumping and wafer level packaging applications on 300 mm wafers. The LP300 allows quick change over from 300 mm to 200 mm wafers and is an attractive solution not only to mass manufacturers of 300 mm wafers but also to wafer bumping service providers with only limited volumes of 300 mm wafers.

The LithoPack300 addresses the specific requirements for wafer bumping and wafer level packaging. Wafer level back end technology requires very thick photo resist layers of up to 100 microns and BCB or Polyimide processing. The spin coating modules, therefore, include Suss' patented GYRSET technique that allows important material savings. Other packaging specific features like edge bead removal and backside rinsing have been integrated. Together with modules for resist bake and resist developing, the cluster can be configured for any thick resist process.

The spin-coater's architecture and process modules are specifically adapted to the needs of the advanced packaging industry. The ACS300 is especially well suited for high volume 300 mm and/or 200 mm production environments but can also be configured as a compact system with incredible flexibility for 300 mm process development applications, and pilot production, and mixed 200 mm production with 300 mm process development.

The exposure unit is a 300 mm full-field proximity mask aligner that enables wafers to be exposed in a single step, offering a maximum throughput of more than 100 wafers per hour. Compared to steppers, mask aligners do not only offer lower capital spending and higher throughput but also a significant technical advantages because the tool offers 100 percent flexibility in edge processing. Mask aligners can print any feature at the edge of a wafer while a stepper has to expose the wafer edge with the reticle layout used for each step. This is an important advantage for mask aligner technology especially when subsequent metallization of bumps or redistribution traces is done by electroplating.

In 1999 and 2000 Suss' sales of 8-inch mask aligners for wafer bumping and wafer level packaging applications doubled each year. The company's systems are particularly successful in solder bumping and wafer level redistribution processes which will be the dominating wafer level back end technologies on 300 mm. Offering full-field mask aligners for 300 mm was a natural progression for the company. Although a 300 mm mask aligner will generate higher mask costs compared to a stepper, the fundamental advantages of mask aligners such as lower capital cosst, higher throughput, full-field exposure, easier operation and maintenance as well as higher uptime more than compensate for the mask costs.

The 300 mm mask aligner will require 14-inch photomasks to expose a 300 mm wafer in one step. Early this year, SUSS MicroTec acquired Image Technology, a key supplier of precision photomasks based in Palo Alto, which specializes in large area photomasks. With this acquisition, Suss has taken another step towards offering a total system solution to its customers. The company plans to start shipping large area14-inch masks starting from late summer this year.

Besides the LithoPack300 lithography cluster, the stand-alone coat and develop clusters as well as a stand-alone mask aligner are also available.