Made From the Same Source Material as the Wafers
SiFusion polysilicon furnaceware is made from the same source material as the wafers, thus significantly improving defect rates at the front end.
Thermal processes subject wafers to a series of extreme conditions. If a fixture in the furnace cannot withstand these conditions without compromising its physical integrity, defects on the wafer can result.
The properties inherent to traditional quartz or silicon carbide furnace consumables are the source of the majority of particle defects in front-end processes.
As device geometries become smaller, the range of acceptable contamination narrows. Defect density, therefore, becomes a significant barrier to sub-100 nanometer targets.
Product Material Comparison
|Silicon carbide||Moderate to low||Moderate to high||Moderate to high|
|SiFusion||Low||None to low||Very low|
Reduce Particle Defectivity
Pure poly silicon SiFusion furnaceware has a unique surface treatment that virtually eliminates flaking and peeling, and thus reduces particle generation. This special surface finish provides a strong mechanical adherence between the deposited film and the poly silicon fixture surface.
In high-temperature deposition processes, thermal stress between the films and the fixtures leads to fractures in the film. The resulting particle generation from these fractures is a major contributor to defect density and has a negative impact on yield.
After repeated heating, quartz releases particulates into the furnace, thus damaging the wafer and requiring frequent replacement.
Lower Trace Metal Contamination
SiFusion technology significantly reduces trace metal contamination. SiFusion products have two to four orders of magnitude less metal contamination than high-purity quartz or silicon carbide products. Because SiFusion furnaceware is made from the same material as the wafer, it can have holes, chips and cracks without contributing impurities.
In contrast, during high-temperature annealing, the metallic impurities in both quartz and silicon carbide become quite mobile and contaminate the wafers.
SiFusion furnaceware matches the wafer s Coefficient of Thermal Expansion, eliminating slip and improving yield.
Crystal damage or slip occurs due to differences in thermal expansion rates between the wafer carrier and the silicon wafer itself, damaging the chip through friction. Slip in high-temperature processes is particularly problematic with quartz consumables, which can warp or sag in vertical furnace applications.