At SEMICON West, Avantor Performance Materials, the former Mallinckrodt Baker Inc., introduced a new selective etch product for FEOL poly gate strain engineering. The J.T.Baker SLCT 128 sigma etchant etches an exposed silicon area, creating a well-defined “sigma” shape for epitaxy, removes post-etch residue, and acts as a preclean, said Avantor director of electronics marketing, John Bubel.
The etchant is the first product in a new series of selective etch chemistries for FEOL poly-gate strain engineering. It under-etches the “sigma” shape of the gate layer to improve electrical performance on advanced nodes. The etchant does this by selectively etching doped silicon crystallographic planes <111> and <110> without affecting the surrounding materials, Bubel said.
J.T.Baker SLCT 128 was developed as a “self-cleaning” chemistry; no additional rinse is required for cleaning after the etch process. By creating well-defined crystallographic planes, it improves the lattice matching between the deposited SiGe and the existing silicon for better device performance, he said.
Applications include strained silicon channels, in which silicon germanium (SiGe) and silicon nitride (SiN) are deposited to induce strain on the silicon lattice under the gate region. It also is applicable to finFET structures where the semiconductor material is vertical rather than horizontal.
No pre-implant operations are required to tailor the initial etching, Bubel said. In some cases, plasma pre-etching can be eliminated or reduced. The SLCT 128 produces a clear, faceted sigma shape, with a highly controlled rate of etch, leading to increased line yield and die reliability, he said.
Avantor (in booth 1607) said it has entered into a joint development agreement (JDA) with Sachem Inc. to provide etch chemical solutions for the semiconductor manufacturing industry. The first product implemented under the agreement is the J.T.Baker SLCT 128 sigma etchant for FEOL poly gate structuring.
–David Lammers