Cooke Evaporator

Cooke Evaporator
Equipment Details
Technology	PVD
Materials Restriction	Metals
Material Processed	Ni, NiCr, Au, Ag, Cu, In, Pd, Sn, Zn
Sample Size	4", 3" and 2" wafers, pieces
Equipment Manual
Overview	System Overview
Operating Procedure	SOP
Supported Processes	Supported Processes
Maintenance	Maintenance

The Cooke Evaporator is an electron beam evaporator used to deposit Ni, NiCr, Au, Ag, Cu, In, Pd, Sn and Zn. It is hoist-lifted domed coater with a single-wafer holder.

All the e-beam evaporators in the LNF are setup using small point sources and long throw distances that lead to very directional deposition with minimal heat transfer. The is means that evaporated films have poor gap fill but make the tool ideal to use for lift off applications. The evaporators in the LNF use thin films controllers with quartz crystal monitor feedback to pre-heat the source materials with the shutter closed and then control power to maintain a preset deposition rate and to determine the total evaporation thickness.

Capabilities

• Single wafer lift-off evaporator
  • Higher deposition rate (5-10 Å/sec) metal films on a 4" wafer holder
  • Designed for low heat transfer and minimal sidewall coverage for liftoff applications
  • Stacks of multiple films can be run

System Overview

Hardware Details

• Cryo-pumped dome coater capable of low 10^-6 Torr base pressure in 1 hr of pumping
• No reactive gasses or heating run on this tool
• 4x7cc pocket E-beam gun to allow 4 different materials to be deposited in one run
• Large distance from source and flat sample holder for liftoff applications

Substrate Requirements

• 2”, 3” and 4” wafer holders available as well as clip fixtures for smaller pieces
• Tool holds 1x4” or fixtures.

Material Restrictions

The Cooke Evaporator is designated as a Metals class tool. Below is a list of approved materials for the tool. Approved means the material is allowed in the tool under normal circumstances. If a material is not listed, please create a helpdesk ticket or email info@lnf.umich.edu for any material requests or questions.

Approved materials

Supported Processes

• Nine films are available:
  • Zinc (Zn) (2000 Å MAX, 10 Å/sec)
  • Gold (Au) (4000 Å MAX, 12 Å/sec)
  • Nickel (Ni) (2000 Å MAX, 10 Å/sec)
  • Palladium (Pd) (1000 Å MAX, 6 Å/sec)
  • Tin (Sn) (2 µm MAX, 15 Å/sec)
  • Indium (In) (2 µm MAX, 10 Å/sec)
  • Silver (Ag) (2 µm MAX, 15 Å/sec)
  • Nickel-Chromium (NiCr) (2000 Å MAX, 5 Å/sec)
  • Copper (Cu) (1 µm MAX, 10 Å/sec)

• Some combinations of these films can be run. They are programmed 3 at a time in the thin films controller

• In the evaporators, maximum thickness numbers are total thickness of that material per run and are determined by stress or material availible. If you run multiple layers of the same material, the total sum thickness of those layers must be below the maximum.

Each of the 9 metals has a standard XTC film program outlined on the Standard Processes page. Combinations of films can be run in any order by programming them 3 at a time in the XTC controller.

Depositing other Materials

• This tool only supports these 9 materials. If you have a material deposition need that is not listed, check to see if this material is deposited on another PVD tool or see more about options for running your own private material on the LNF PVD Films page.

Standard Operating Procedure

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Checkout Procedure

How to get access to this evaporator:

1. Complete the online PVD Rise Training (this only needs to completed once so if you are authorized on another PVD tool or evaporator, you do not need to do it again.)
2. Read through this Wiki page and the Operating Procedure above.
3. Create a Helpdesk Ticket requesting training
4. A tool engineer or user services member will contact you for a training session.
5. Practice with another authorized user until you are comfortable with tool operation.
6. Schedule a checkout session with a tool engineer via the helpdesk ticket system. If this checkout is successful, the engineer will authorize you on the tool.

Maintenance

The Cooke is opened for scheduled maintenance:

• Once a week and the gun area is cleaned and shutter is scraped.
• The substrate mounting plate, sidewalls, shutters and covers are cleaned as needed (approximately once every 2-4 months.)
• Tool leak checks, pumping speeds and film characterization are done periodically or when major tool changes are done.
• Rough pump oils is changed once every 3 months. Cryo absorbers are replaced annually.

Tool Pumping Performance

Pumping speeds and Leak-up rates vary based on chamber sidewall deposition and outside conditions such as humidity and time tool was open.

Cooke pumping speed - tool crosses over to hi-vac in 7.5-9minutes

Process Characterization

9 Films are standard in the Cooke

Power Bump Recovery

The only maintenance that users are allowed to perform is power interruption recovery.

• In the event of a power interruption, try to get the tool powered back on within 10-15 minutes. This will save 8-12 hours of down time lost to a cryo regen.
• Follow the power bump part of the Cooke Startup and Shutdown Procedure
• If recovery cannot be done in time this procedure will refer you to the Cooke Cryo Regen Procedure