APS

The SPTS APS is an inductively coupled plasma (ICP) etching system. The system was optimized for etching dielectric materials such as silicon dioxide, silicon nitride, silicon carbide, aluminum oxide, and various glasses. The SPTS APS is used for etching dielectrics that are difficult to etch using conventional RIE or ICP sources.^[1]

In semiconductor fabrication, dielectric etch tools such as the SPTS APS are used to transfer patterns into dielectric layers after photolithographic patterning. The etched dielectrics may then serve as insulating layers, passivation layers, or sacrificial layers. In MEMS and photonics fabrication, the system can be used to etch thick dielectric substrates such as fused silica or Pyrex.

The SPTS APS is used for etching a variety of dielectric materials. For silicon dioxide etching, recipes using C4F8/He or C4F8/H2/He yield etch rates from 170 to 440 nm/min with selectivity to photoresist from 2.8:1 to over 25:1. For silicon nitride, a CHF3/SF6 recipe provides etch rates of 160-220 nm/min with selectivity of 2:1 against photoresist. Polyimide is etched using oxygen with etch rates up to 1300 nm/min. Fused silica and Pyrex are etched with C4F8/O2 using aluminum masks, with etch rates of 760 nm/min and 580 nm/min respectively. Lithium niobate wafers are etched with CHF3/Ar using a chromium mask with an etch rate of 90 nm/min.^[1]