Dow Corning Electronics has introduced two new product families of low-stress, patternable, silicon-based products. The WL-3000 and WL-5000 series of products are low-modulus, low-cure-temperature materials designed to enable the production of packages processed at the wafer level.
These new product lines aim to safeguard the performance and yields of packaged microelectronic devices, while giving users a choice in the patterning process.
According to Dow Corning Electronics, stress is becoming an issue of critical importance in selecting materials for packaging today’s microelectronic devices. Excessive stresses during thermal cycling can arise from a mismatch in the coefficient of thermal expansion (CTE) between the package materials, potentially causing catastrophic device failure.
Additionally, tensile or compressive stresses created by the materials themselves upon cure can contribute to wafer warping, particularly in thinned wafers. These issues have driven device manufacturers to look for materials that offer a low-stress film after processing and provide stress relief to increase device reliability.
The low-stress WL-3000 and WL-5000 product families from Dow Corning Electronics can be used in forming pads, vias, as well as redistribution, stress buffer, and protective layers in flip chip designs, multichip modules, MEMS devices, biochips, and ICs that incorporate low-k dielectric layers.
The WL-3010 material, the first product in the WL-3000 series, is patterned using standard printing processes currently used by leading packaging houses. The WL-5000 product family is patterned using standard photolithography equipment, the approach used by semiconductor device manufacturers.
The number of devices to be packaged at the wafer level is estimated to grow by 40 percent per year from 2002 to 2007, resulting in over three billion die packaged by wafer-level process in 2007.
The WL-5000 family is comprised of three products: WL-5150, WL-5350 and WL-5351. These materials span a range of viscosities, final film moduli and thicknesses, while exhibiting a final tensile stress of less than 7 MPa.
These three materials are in evaluation trials as stress buffer layers for sensors, wafer-level packages for memory ICs, backside coating applications and redistribution layers. The WL-3010 product is in final testing as a stress buffer layer for memory packaging.