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Material Deposition and Device Fabrication in the Silicon Wafer Replacement Tool

This page provides additional details on materials deposition and device fabrication using the Silicon Wafer Replacement (SWR) Tool within the Process Development and Integration Laboratory (PDIL).

Hot-Wire Chemical Vapor Deposition

Hot-wire chemical vapor deposition (HWCVD) of silicon-based films has been pioneered at NREL. It allows for the deposition of amorphous, nanocrystalline, and epitaxial silicon films at high deposition rates and with high gas utilization. The SWR tool has two of these chambers designed to grow epitaxial silicon films with different doping concentrations to prevent dopant contamination of the low-doping chamber.

Applications (in separate chambers):

  • Depositing n+/p+ epitaxial silicon films
  • Depositing n-type epitaxial silicon films

Specific Features:

  • Base pressure of ~10-8 torr
  • Maximum substrate temperature: 700°–1,000°C, depending on material
  • Growth rates: up to 2 micrometer/minute
  • Typical process pressure: 1–30 mtorr
  • Gases available: SiH4, GeH4, H2, 5% PH3 in H2, 5% B2H6 in H2, 1000 ppm PH3 in SiH4, 1000 ppm B2H6 in H2
  • In-situ, real-time ellipsometry
  • Substrate is rotated to a vertical orientation in the tool for deposition

Plasma-Enhanced Chemical Vapor Deposition

Plasma-enhanced chemical vapor deposition (PECVD) of silicon-based films is a standard industrial process known for being robust and scalable. It allows for the deposition of amorphous and nanocrystalline silicon films. The SWR tool has two of these chambers designed to grow amorphous silicon films—one with dopant gases installed and the other without—to prevent dopant contamination of the i-layer chamber.

Applications (in separate chambers):

  • Depositing n+/p+ amorphous silicon films
  • Depositing intrinsic amorphous silicon films
  • Fabricating a-Si:H heterojunctions using the epitaxial layers grown in the HWCVD chambers of the SWR tool

Specific Features:

  • Base pressure of ~10-8 torr
  • Substrate temperatures: 100°–400°C
  • Typical process pressure: 100–1,000 mtorr
  • Gases available to i-layer chamber: SiH4, GeH4, and H2
  • Gases available to p+/n+ chamber: SiH4, GeH4, H2, 5% PH3 in H2, 5% B2H6 in H2

For more information, contact Charles Teplin.