Thermal Atomic Layer Etching Using Metal Precursor and Halogen Gas

The patent replaces ion-enhanced and energetic noble gas atom-enhanced methods (mechanical/physical bombardment) with purely thermal chemical reactions. The etching process uses sequential exposure to metal precursor and halogen-containing gas at elevated temperatures to form volatile products, eliminating the need for ion or energetic atom bombardment that causes substrate damage.

The patent changes the fundamental operating parameters from low-temperature plasma/ion-based processes to elevated temperature thermal processes. By operating at temperatures sufficient to drive thermal化学反应 (but below damage thresholds), the process achieves etching through thermally activated chemical reactions rather than physical bombardment, thereby eliminating substrate damage while maintaining etching capability.

The patent segments the etching process into two distinct sequential steps: (1) exposure to metal precursor to form a metal compound layer, and (2) exposure to halogen-containing gas to form volatile etch products. Each step is self-limiting and can be independently optimized, allowing the process to be applied to various materials while maintaining precise control through the segmented approach.

The patent employs self-limiting reactions where the chemistry inherently stops after forming a monolayer or controlled thickness of reaction product. The metal precursor self-limits to forming a complete monolayer of metal compound, and the halogen gas self-limits to forming volatile products only from the metal compound layer. This self-service mechanism eliminates the need for complex real-time monitoring and control systems, reducing process complexity while maintaining precision across different materials.