For the processing of thin Si or GaAs wafers rigid carriers are needed – for example in TSV processes on thin Si wafers. Since the accuracy of the resulting device wafer is influenced by the accuracy of the used carriers the demand on ultra low TTV carriers is increasing.
These carriers need to fulfill various requirements such as mechanical robustness, high temperature and chemical resistance.
Low TTV Glass Carrier for TSV with holes for chemical release
Glass is the perfect material for carriers because of it's thermal stability and resistance against acids and other chemicals. Bonding to and de-bonding from a glass carrier can be monitored since glass is transparent. Furthermore glass carriers can be cleaned and re-used which makes a contribution to cost down and environmental protection.
Plan Optik's glass carriers are ground or polished to a very high accuracy by using the latest grinding and polishing technology. A total thickness variation (TTV) as low as 2 μm and a guaranteed thickness tolerance of down to ±3 μm over all carriers in the end leads to accurate semiconductor wafers.
Plan Optik's carrier wafers are clean room packed and ready for immediate use. They are coming either blank or with though holes for easier chemical release or with cavities which allow a better distribution of bond media.
The use of different glass types for these carriers allows an adaption of the coefficient of thermal expansion (CTE) of the carrier to the semiconductor wafer which has to be processed (e.g. Si or GaAs). This reduces or mostly even eliminates stress issues when heat is involved in the used semiconductor processes. For silicon wafers alkaline free types are available.
Different types of intermediate materials, e.g. thermo-plast adhesives, waxes, resists or tapes require different technologies to apply the semiconductor wafers to the carrier wafer.