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Silicon Wafer Replacement Cluster Tool Capabilities

The silicon wafer replacement (SWR) tool can handle sample sizes up to 157 mm square in the standard 7"x7" platen for the Process Development and Integration Laboratory (PDIL). Silicon deposition can generally be done on any sample smaller than this. Automated hydrofluoric (HF) oxide etching requires either using one of our standard sample sizes or fabrication of custom holders.

The SWRT consists of a main robot with space for eight process or handling chambers. One space is reserved for a removable load lock or transfer pod. The transfer pod allows samples to be exchanged in vacuum with other tools in the PDIL. A unique feature of this cluster tool is the ability to queue samples within the central chamber housing the robot.

Current wafer silicon technologies involve multiple high-temperature steps, as well as sawing, to produce wafers that are about 10 times thicker than they need to be to be a solar cell. The purpose of this SWR tool is to produce just the amount of high-quality crystalline silicon, right where it is needed (read more on the rationale for developing the SWR cluster tool).

Applications include the following:

  1. Advancing epitaxial silicon growth technologies on foreign substrates
  2. Developing seed layers for epitaxial silicon growth
  3. Improving the understanding of seed layer / silicon film interface characteristics
  4. Developing novel epitaxial silicon device structures
  5. Advancing the understanding of epitaxial silicon growth kinetics and chemistry
  6. Improving predictive models by studying materials actually used in devices

Basic Cluster Tool Capabilities

Sample Handling

  1. Central robot, with integral sample queuing
  2. Load lock with 6-platen cassette
  3. Transfer pod capability for vacuum access to all PDIL tools
  4. Port for exchanging samples to an industrial collaborator

Material Deposition/Device Fabrication

  1. Hot-wire chemical vapor deposition (HWCVD) of n+/p+ epitaxial silicon
  2. HWCVD of n-type epitaxial silicon
  3. Plasma-enhanced chemical vapor deposition (PECVD) of n+/p+ amorphous silicon [planned]
  4. PECVD of intrinsic amorphous silicon [planned]

Processing

  1. Oxide etch tool, atmospheric pressure with liquid HF
  2. Sub-atmospheric hydrogenation tool

The figure shows where chambers—numbered in the list above—are located on the eight ports around the central chamber. A robotic arm moves samples from one chamber to another within the cluster tool.

Simplified illustration of the PDIL with yellow circle in the center and rectangles surrounding it.

This schematic of the Silicon Wafer replacement cluster tool indicates the tools connected to the eight ports. The color bar is a key to the basic class of each capability.

Other Support Capabilities

The SWR tool contains many capabilities for silicon research. But additional capabilities for processing, integrated measurements and characterization, and stand-alone measurements and characterization are available elsewhere in the Process Development and Integration Laboratory.

Samples from the SWR tool can be transported to the other tools using the mobile transport pod, which can keep samples under vacuum conditions.

For more information, contact Charles Teplin.