- General Information and Usage
- The Bruce Furnace is a tube furnace capable of temperatures reaching (at least 1550°C).
The Bruce is used for annealing, diffusion, and oxidation. It has four available tubes, each utilized exclusively for a different process. Up to two tubes can be used simultaneously (because we only have two controllers). The Bruce can be programmed to allow for multistep processes requiring various gasses at different concentrations.
- Equipment Specifications
- Available gases: O2 (wet and dry),
- H2N2 (forming gas), Argon, N2
- Ability to process up to (about 100) 4" wafers simultaneously
- Max Temp: >1550° C
- Max # of process steps: 9
- Operating Instructions
- CAUTION: Only use the tubes for their specific labeled uses. (Tube 1: Diffusion. Tube 2: Annealing. Tube 3: oxidation. Tube 4: SIM Group ONLY (special permission required).
- Start Up
- Turn on any necessary gases. (Hydrogen, argon in the back room and behind the Bruce, H2N2 and oxygen behind the Bruce) There are valves on the Bruce that must also be opened and checked for proper settings.
- Flip the main power breaker. An alarm will go off. On the control panel hit the reset switch.
- Flip the power breaker of the desired tube furnace.
- Programming the Bruce
- Only two tubes can be programmed at once. If the control panel on the tube you need is not illuminated, you will have to switch some cables in the back. (see below for instructions)
The following parameters must be set to program the Bruce:
|Parameter ||Symbol |
|Heat/Temperature ||B |
|Duration-time duration of each step ||D |
|Function-which gases will be used for a given step ||F |
|Gas-flow control for the gases ||shift-B |
|Boat-rate ate which the door will open and close ||shift-D |
|Control ||C |
There are three sections of each furnace. Each must be set to the desired temperature.
To check the current temperature of any section of the tube, in the root menu hit B-enter-01 or 02 or 03-enter.
- In root menu, hit B-enter-11-enter-[desired temperature for section 1].
- Hit enter-B-[desired temperature for section 2]. (Display will read 12).
- Hit enter-B-[desired temperature for section 3]. (Display will read 13).
- Hit enter-enter.
- Hit C-enter-0-enter-d-1-d-1-enter-enter. (The tube lights should come on indicating that there is now power going to the tube heaters. If they don't, check the breaker for the tube.)
- In root menu, hit D-enter-1-enter-4-0-0. This sets step 1 at 4 minutes zero seconds. As this is the first step, it is the step during which the door will be closing.
- Hit enter-D. This shortcut skips directly to step two. If you mess up, hit D-enter-2-enter. Enter the hours, then minutes, then seconds of your process. Repeat for each step in your process.
- The last step must also be four minutes long. (enter-D-4-0-0)
- Hit enter-enter. This always takes you to the root menu - good to know if you mess up and need to start over.
- To calculate the duration use this: Time Given a Desired Thickness
The key to this step is to treat it like a shift register: 0 right shifts the register; 1 right shifts the register and lights the number one spot light. Also, if spot number 11 is lit, the door will be closed (pushed); if spot 12 is lit, the door will be opened (pulled). Thus the first and last steps, in addition to which gases are used, must have respectively 11 or 12 lit. To the right of each control panel, there is a key assigning for each tube numbers to gases connected to the tube.
Eg.: three step process. Step 1: nitrogen and push; step 2: oxygen; step 3: pull. Tube 3: Gas# 1. Hydrogen; 2. Oxygen; 3. H2N2; 4. Wet oxygen.
- In root menu, hit F-enter-1-enter. (Now you're programming step 1)
- Hit 1-0-0-0-0-0-0-0-0-0-1. The one and eleven spot lights should be lit. (nitrogen and push).
- Hit enter-F. (Now you're programming step two.)
- Hit 1-0. The number two light should be lit. (oxygen).
- Hit enter-F. (Now you're programming step three.)
- Hit 1-0-0-0-0-0-0-0-0-0-0-0. The number twelve light should be lit (pull).
- Hit enter-enter. (root menu).
Make sure the shift button is pressed (shift light will be on). For each step, the flow rate must be set for each gas used in the step. In the example above, where the flow rate for nitrogen is 35% and the flow rate for oxygen is 10%, the gas would be encoded as follows.
In this example there aren't any gases in step three. But, if there were, you would follow the pattern above, entering 3-[the number of the gas]-enter before entering each gas in step three.
- In the root menu, hit B-enter-1-1-enter. (Here the first 1 indicates that you are programming step one; the second 1 indicates that you are going to program the flow rate for gas one, or nitrogen in this example.)
- Hit 3-5-0-0-enter-enter. (this is 35.00%, the flow rate for nitrogen. As this is the only gas used in step one, we go to the gases used in step 2.)
- Hit B-enter-2-3-enter. (step 2, gas 3 - oxygen).
- Hit 1-0-0-0-enter-enter. (10.00%, the flow rate for oxygen.)
Make sure the shift button is pressed (shift light will be on). Programming as described below will ensure that the rate at which the door moves is such that the door will open and close in four minutes exactly.
- In root menu, hit D-enter-1-1-enter-1-5-9-9-enter-enter.
- Hit D-enter-3-1-enter-1-5-0-0-enter-enter. (Always enter 3-1 regardless of the number of steps in the heating process.)
Each step must be activated. The activation code is d1d1.
- In root menu, hit C-enter-1-enter-d-1-d-1.
- Hit enter-C-d-1-d-1. Repeat this for each step in your process, including push and pull steps.
- Hit enter-enter.
- Manually open the door, load your wafers and wait for the tubes to reach the desired temperature (see the section on Heat for how to check current temperature).
- Press the Start button. The tube will go into default ("inhibit") - press the acknowledge button and press the start button again.
- Shut Down
- Unload your wafers and the boats.
- Close the furnace door.
- Turn off the tube circuit breaker and then the main circuit breaker.
- Turn off any gases that you used.
- Trouble Shooting
- Control panel for desired tube doesn't light up.
- There may not be controllers hooked up to the tube. Contact Phil or Jeff for questions on how to switch them over.
- Changing the wet oxide solution.
- 10:1 water to HCL solution.
- Nonsense characters on display.
- Shut off main power breaker, wait 3 seconds, and flip it on again.
- No gas flow/no pressure on indicators at top of furnace.
- Check gas gauges in back of furnace.
- Start button doesn't work.
- Press Acknowledge button and press start again
- Door won't close (tube 1)
- Make sure speed dial is not at zero.
- Wet oxide is not heating up
- Flip switch on heater
Comments or suggestions? Submit them here.