Endeavor M1 AlN Sputter Tool

Sputter deposition

Endeavor M1 AlN Sputter Tool
Equipment Details
Technology	PVD
Materials Restriction	Metals
Material Processed	Al, AIN
Sample Size	4" or 6" wafers only
Equipment Manual
Overview	Endeavor M1 AlN Sputter ToolSystem Overview
Supported Processes	Supported Processes
Maintenance	Maintenance

The Endeavor M1 is dedicated for sputter-deposition of high quality piezoelectric Aluminum Nitride (AIN) films. Piezoelectric AlN is deposited using reactive sputtering of a pure Al target with a combination of nitrogen and argon as the sputtering gasses. Piezoelectric AlN is difficult to sputter because of the insulating nature of the film, stress issues in the film and it’s sensitivity to O₂. As a result, it requires a dedicated system which uses dual AC target technology, extensive Al pasting routines, substrate bias to prep surfaces and a loadlock to minimize pumping times while still allowing mid-10^-7 Torr pressures.

Announcements

• New Endeavor Tool being installed - Target Release April 22.

Capabilities

• Piezoelectric AlN films 0.5-2.5 µm thick
• Variable gas flows and adjustable substrate resistance/capacitance to allow for stress control

System Overview

Hardware Details

• Turbo-pumped/Water-pumped (high temp cryo that acts as a water trap,) loadlocked sputtering tool.
• 10 KW AC power supply that runs 5-7KW power across a dual Al target source
• RF bias on wafer holding platen to control surface characteristics.
• 100 sccm N₂ and Ar flow meters.
• Handler for 6" wafers, carrier for 4" wafers.

Substrate Requirements

• 4” and 6" wafers only
• The process heats the wafer considerably (~500°C or more) with heavy ion bombardment so no organics or low temperature films are allowed in the tool.
• The process only produces piezoelectric AlN films on certain materials (specifically blanket undoped or low-doped Si, SiO₂ and patterned Mo, Pt, Al.)

Material Restrictions

The Endeavor M1 AlN Sputter Tool 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

The Endeavor

• Aluminum Nitride (AlN) deposition.
  • AlN is a 3-step process:
    • A condition recipe which pastes a dummy 6" wafer with Al and then preps it for AlN deposition. The dummy wafer is then unloaded in the chamber
    • An etch recipe which runs an RF Ar etch on the process wafer and then runs an Ar/N₂ flow to prep the surface.
    • Deposition recipes are designated by thickness and the the deposition time is set by a target file which is a mapping of dep rate per KWhr
      • Users must work with staff to change steps of the deposition recipes.

Recipe layout, recipe steps and editing rules are outlined in the DOP

Process Characterization

AlN Thickness

• AlN thickness is set in the recipe and the tool uses the target file data to determine the deposition rate.
  • The Target file adjusts the deposition rate depending on the wear/age (KWhrs) of the target.
  • Thickness data collected by users and staff in the logbook will be used to adjust and improve the accuracy of the target file.

Stress Adjustment Unit

• The stress adjustment unit is used to adjust a capacitance/resistance path to ground of the chamber.
  • Users can adjust the dial before their runs.
  • Typically adjustments below 25 will lead to plasma instability issues so the vendor does not recommend going below that point.

AlN Hysteresis:

• Hysteresis is mapped to look at the N₂/Ar ratios that produce a poisoned AlN state
  • Users will want to run in the lower target voltage regime (AlN poisoned mode.)
  • Since the condition recipe and the beginning of the deposition recipe run the target to a high N₂ flow state (20-21 sccm) the deposition steps are operating on the N₂ "going down" (orange) curve.

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Detailed Operating Procedure

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Checkout Procedure

• Read through this page and the Standard Operating Procedure above.
• Create a Helpdesk Ticket requesting training.
• A tool engineer will schedule a time for initial training.
• Practice with your mentor or another authorized user until you are comfortable with tool operation.
• 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

Power Bump Recovery

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

• Follow the power bump part of the AMS 2003 AlN Startup and Shutdown Procedure