Under Bump Metalization - UBM

Williams has emerged as the leading thin film deposition materials supplier for the Under Bump Metalization (UBM) layers that are critical to the performance of Chip Scale Packaging (CSP) processes. Still a leading supplier of traditional micro electronic packaging materials using bond wire technology, Williams has positioned itself with a full product offering as more designers integrate CSP to minimize cost and improve performance of their devices.

UBM, for most CSP processes, is the first step in bumping the integrated circuit (IC) bond pad and thus is critical to the overall success of the bump process. The three main functions of a UBM stack are:

1. Adhesion layer with a low contact resistance to the metal pads and surrounding IC passivation layer
2. Barrier layer to prevent the diffusion of the bump metals to the IC
3. Seed layers for subsequent plating or wetting layers for the solder of printed bumps

To provide the optimum ratio of superior performance to cost, Williams has designed a series of UBM Grade™ thin film deposition materials for each of the leading bump technologies:

Williams supports each of these technologies with a combination of products, including:

• Sputtering targets
• Evaporation materials
• Plating Anodes

Since the UBM process is nearly the last step in the production of a semiconductor device, the quality requirements are demanding any lost yield results in substantial loss of revenue. To meet the stringent demands of this industry, Williams has developed optimized UBM™ grade materials that display a uniform, fine grain size that improves overall thin film uniformity. Gaseous impurities have also been further reduced, resulting in extremely consistent thin film electrical properties. All of this adds up to enhanced device performance and greater wafer yield. The following table highlights some of the material properties of the Williams UBM Grade™ materials:

*Detailed data sheets available on web site.

Sputtering materials are produced in a wide array of shapes and sizes to meet the requirements of virtually any sputtering tool design. Williams has developed SFG™, a process to produce sputtering targets with optimal grain size of 100 microns or less. SFG™ ensures greater thin film yields (uniformity) and maximizes target utilization.

Thermal (resistive) and E- beam evaporation processes are enhanced with our EVAPro™ material. EVAPro™ is Williams' proprietary technology that causes ultra-low internal gas entrapments and ensures the lowest defect count per wafer, from the initial soaking time to the last evaporation run. Williams also offers a full array of backing plate designs and internal services, including the ability to replace, refurbish, repair and design backing plates using CAD/CAM. Our target bonding facilities are located throughout the world, supplying industry-leading bonding services while minimizing shipping logistics.

Our in-house precious metal refining and recycling program includes: spent targets, chamber scrapings, coated shield kit and parts cleaning. The utilization of this program results in lower cost and minimized precious metal inventory.