The manufacturing complexity of Gate-All-Around (GAA) nanosheet transistors hinges heavily on the precise removal of sacrificial epitaxial layers during the channel release sequence. Semiconductor equipment engineers have perfected specialized atomic layer etching (ALE) systems that achieve absolute chemical selectivity between silicon nanosheets and sacrificial silicon-germanium layers without inducing plasma-induced physical damage to the active channel surfaces.
During GAA fabrication, vertical stacks of alternating
During GAA fabrication, vertical stacks of alternating silicon and silicon-germanium layers are grown on the substrate. To create suspended nanosheet channels that allow the gate electrode to wrap completely around the wire, the silicon-germanium layers must be selectively etched away while leaving the pristine silicon channels untouched. Conventional wet chemical etching methods often suffer from high lateral undercut rates and surface roughness, degrading carrier mobility within the transistor channel.
Lam Research: The newly optimized ALE tool utilizes
The newly optimized ALE tool utilizes cyclical, self-limiting gas-surface reactions that modify the target atomic layer chemically before applying a low-energy directional sputter removal step. This two-step atomic precision approach ensures that the sacrificial material is stripped away cleanly even within deep, high-aspect-ratio channel gaps.
Foundry process engineers utilizing the advanced?
Foundry process engineers utilizing the advanced etch systems report smoother channel sidewalls and superior sub-threshold leakage characteristics on early production runs. These microstructural improvements translate directly into higher drive currents and better energy efficiency for advanced computing processors.
"Equipment innovators have refined selective atomic layer etching systems to remove sacrificial silicon-germanium layers cleanly during gate-all-around nanosheet channel release without sidewall damage." — Tom's Hardware