MTL Fabrication

Sts1 - Standard Operating Procedure

CORAL Name: sts1
Model Number: --
Location: TRL
What it does: etching
Introduction: The ST Systems Multiplex ICP tool is a Deep Reactive Ion Etch (DRIE) tool. It provides high aspect ratio etching and deep/through wafer anisotropic etching capabilities. The tool uses two independent 13.56MHz Radio Frequency (RF) power supplies - a 100W supply for a single-turn coil around the etch chamber and a 300W supply connected to the wafer electrode to vary the RF bias potential of the wafer with respect to the plasma. The efficient inductive power coupling of the coil to the plasma allows high density plasmas to be maintained. The tool uses the Bosch process of time multiplexed deep etching (TMDE) to achieve high aspect ratio etches. This process utilises an etch cycle flowing only SF6 and then switching to a sidewall passivation cycle Using only C4F8. During the subsequent etch cycle, the passivating film is preferentially removed from the bottom of the trenches Using ion bombardment.

Due to the toxic nature of the process gases, the supply cylinders are turned on and off by qualified technical staff only. All tank changes are performed by qualified technical staff only.

Do not try to defeat any interlock on the system. Keep your hands away from all moving parts and be sure that all covers are in place when you are processing. If you encounter any equipment problems while operating the system, contact the technical staff in charge of the system. Do not try repairs on your own.


NOTE: It is mandatory to reserve the system prior to use and to ENGAGE MACHINE prior to starting your process in CORAL.

Venting and Loading a Wafer:

The system monitor should display the Loadlock Control screen. This screen can be reached from the Process Parameters screen by pressing the F3 (Load/Unload) key.

To vent the loadlock, press the ?V? key. The loadlock will run a purge cycle three times before venting to atmosphere. When the loadlock is at atmosphere, a blue LED on the front of the tool will light and the loadlock cover may be opened. Using tweezers load the wafer onto the centre of the robot blade. Closing the lid will cause the loadlock to begin pumping down to 80mT. To load the wafer into the etch chamber, press the ?L? key. Processing the Wafer: Press F3 to go to the Process Parameters screen. At the bottom right of the screen are several options:

  • F1 - Etch Begins running currently loaded recipe
  • F2 - New Process Load a new recipe
  • F3 - Load/Unload Return to Loadlock Control screen
  • F4 - Shut Down Exits the software ? DO NOT PRESS THIS KEY

    At the bottom left of the screen are two more options:
  • F6 - Main Menu Text screen for entering DOS commands
  • F7 ? Mimic Process Monitor screen

Before beginning the etch, the correct recipe must be loaded? Press F2 to access the Recipe screen. All the available recipes are listed, use the cursor keys to highlight the desired recipe, then press enter to load it. The screen will return to the Process Parameters screen and the chamber will go through a pump routine to reach base pressure.

NOTE: If the system gives a ?Cannot reach Base Pressure? error, look at the front of the tool and check if the Ion Gauge control box is flashing ?OVP?. If it is, press the EMIS button to reset the gauge.

Once the recipe has been loaded a message will appear on the bottom right of the screen and the F1 key can be pressed to begin the process.

If you are going to adjust the recipe time or any other process parameters, follow this procedure carefully:

  • During the ?Gas Stabilisation? step, press the F2 key to Hold the process.
  • Use the arrow keys to move to the parameter being adjusted ? enter the new setting and press Enter.
  • If you are adjusting the time, use the format 00:00:00, be sure to enter the colons and press Enter.
  • Press F2 again to resume the process.

When the process has completed, the message ?Process ________ ended OK? will appear on the lower right of the screen.

Press F3 to go to the Loadlock Control screen to unload the wafer.

Press ?U? to unload the wafer and then ?V? to vent the loadlock and retrieve your wafer.

Do not leave wafers in the machine overnight ? this wastes a lot of Helium.

If there are any issues with the tool post a comment in CORAL and contact Donal 2-2983.

Author: Donal Jamieson