MRL2 Wet Dry Oxidation Procedure- 1 - 11/3/15

Wisconsin Center for Applied Microelectronics

1550 Engineering DrivePhone: 608/262-6877

Madison, WI 53706

Rev. 11/3/15

MRL2 Wet Dry oxidation procedure- 1 - 11/3/15

OPERATING PROCEDURE

MRL2 Oxidation Furnace

Safety:

1) Impact resistant eye protection required

2) Read SDS for tool process chemicals

3) Training and tool access required

4) Know lab evacuation procedures

5) Know location and use of eye/body showers

MRL2 Wet Dry oxidation procedure- 1 - 11/3/15

Material Restrictions:

All materials in/on your sample must be on the “allowed materials list” for this tool before using it. NO EXCEPTIONS. It is the user’s responsibility to make sure that the material(s) they are putting in a tool is on the allowed materials list for that tool. Here is how to check the Allowed Materials list for WCAM tools:

1. Go to WCAM’s website at:

2. Click on the “Chemicals in the Lab” link.

3. Click on the link at the top of the page “LIST OF APPROVED MATERIALS”.

4. Scroll thru the document to find the tool you want to check the materials list for or hit Ctrl + F to bring up a search bar for the document and type in the tool’s name that you want to check the materials list for.

5. If the material(s) that you want to use in a tool are not on the approved list for that tool you may not put your sample in the tool. If you have no other way to process your sample and think it makes sense to use a particular material in a tool you may request that it be added to that tool’s material list by filling out the form on the “Chemicals in the Lab” webpage listed as “New Material Request Form”. Then email your material request form along with a SDS for the material to the WCAM lab manager. The request will be reviewed by the WCAM advisory committee and you will get an email back from the lab manager approving or denying your material request for a particular tool.

Tool Purpose & Restrictions:

The MRL2 oxidation furnace is a steam furnace that uses DI water to produce wet oxidation of silicon samples or just a gas cylinder of O2 to produce dry oxidation growth on silicon. Just clean silicon with no history of metal processing that has gone thru the pre-furnace clean bench in its entirety is allowed in this tool. Cleanliness and no metal ion contamination are very important in this furnace for the growth of oxides, which is why the sample restrictions and rules are so strict. Pre-furnace clean is required of all samples with the only exception being samples with spin-on-dopants (see staff for this procedure). Because the furnace uses DI water to produce the wet oxidation, wet oxidation times can be much longer as compared to the Tystar oxidation furnace.

Tool Safety:

1. If there is an emergency related to the tool the best thing to do is to press the Emergency Shut Off (ESO) button. Located on the front and is a big red button. This button will immediately power down the whole tool.

2. This tool has an interlock controlled by the CRESS system. This is to restrict use of the tool to only users that have gone thru the training process for the tool and have access to it. The CRESS interlock for this tool is the furnace cantilever will not come out when a recipe is started if the user is not logged into the tool via CRESS.

3. Do not burn yourself. A hot glove must be worn on the hand opposite holding the furnace fork when loading and unloading quartz boats. Cool time coming out of the furnace for samples and the quartz boat is 2 minutes on the cantilever and 15 minutes once removed from the furnace cantilever and placed on the quartz staging plate. Do not touch your sample or quartz boat with anything except the furnace fork and quartz staging plate until these cool times have finished.

4. Do not load or unload quartz boats while the furnace cantilever is moving.

User Responsibilities:

1. Filling out the run log after loading sample and when finished is required for this tool.

2. Clean up the area after you are done using the tool.

3. Check the materials allowed list. Samples must not have a metal processing history prior to this tool.

4. No tweezers with a metal tip.

5. A full pre-furnace clean of sample is required before putting it into the furnace. The only exception to this rule are samples with spin-on-dopants on them, see the staff for this procedure.

6. Do not leave the lab until the furnace cantilever is back in the tube and moves onto the next step.

7. The user must be back within 2 hours of the furnace being done during staffed hours or once staff hours start.

8. Only the designated quartz boats stored in the furnace can be used in this furnace.

9. Do not have the furnace open any longer than it needs to be. Once the furnace is open be ready to load your sample.

Operating Procedure:

The individual tube computers are located on the panel in front of the tubes.
The computer for the entire MRL system is located on the computer shelf.
The EVENT button is located at the end of the tube and will be used during a processing recipe.

Pre-Run Check – CRESS, Tube Temperature & Gas Flow

Log into CRESS
Click on MRL 2 for general purpose oxidations.

TUBE 1 – High temperature annealing

TUBE 2 – Silicon oxidation, high temp oxidation

TUBE 3 – III-V oxidation, low temp oxidation

TUBE 4 – Low temperatureannealing

On the MRL system computer, maximize the GMI Cell Manager screen.
The GMI Cell Manager screen shows active system tubes as WHITE. If the tube you are trying to use is greyed out contact the staff to re-establish communication with the tube.
On the Tube 2 computer check thetube temperature.

Press TEMP and the Tube computer screen will display:

S1=xxx S2 = yyy S3=zzz

These are the spike temperatures and not the tube temperature.

Press the , you will see:

P1=xxx P2 = yyy P3=zzz

These are the profile thermocouple temperatures of the three tube zones: load, center, and source.

750C is the idle temperature of the tube.

Check gas flows in the tube.

Press GASand the tube computer screen will display the gas flows.
4.00 l/min is the idle nitrogen flow.

Loading Your Recipe & Oxidation Time

On the tube computer, press RECIPE. See posted recipe list by the tool.
The tube computer displays:

LOAD RECIPE [ ]

Key in the three digit recipe number that you want: [2XX].
Press ENTER/ACK.
The tube computer screen will display:

WAITING FOR DOWNLOAD

Once the download is complete the tube computer screen will display:

RECIPE XXX IS WAITING TO START

Press START/HOLD to start the recipe
The Tube Computer screen will display:

ENTER TIMES? YES

Press ENTER/ACK
The Tube Computer screen will display:

RECIPE XXX, STEP YYY TIME[00:00:00] MIN=00:10:00 MAX=21:00:00

Key in your oxidation time in Hr:Min:Sec. Key only the numbers. Press ENTER/ACK.

The Tube Computer screen will display:

START RECIPE? YES

Press ENTER/ACK
The Tube Computer screen will display:
BOAT UNSTORE ACTIVE

The tube will begin to unload the furnace cantilever. The boats for the MRL tube are stored in the tube on the cantilever.

At the end of the cantilever unload the tube computer will blink the alert light to tell you to load your samples. Remove the quartz boat needed with the furnace fork and place on the quartz staging plate on the furnace table. Let the quartz boat cool for 15 minutes before placing your sample(s) in it.

Loading Your Sample(s)

Load your samples into the cooled quartz boat using the vacuum wand or polymer tipped tweezers.
Use the furnace fork to place the quartz boat with sample(s) carefully so that the legs are balanced on both sides of the furnace cantilever evenly.
Press the EVENT button to the right of the tube after loading the quartz boat and sample(s).
The Tube Computer will say:

BOAT STORE ACTIVE

The tube will begin to load the furnace cantilever.

Your oxidation recipe will continue automatically.
Do not leave the lab until the furnace has completely closed and the recipe moves onto the next step. Fill out the run log before leaving the lab.
Remember to look at the end time of your furnace run so you know when to be back to take your samples out. During staff hours or once staff hour’s start you should be back within 1 hourafter your sample(s) are done to remove them, 2 hours maximum.

Monitoring the Furnace Steps During Processing

On the tube computer you can monitor various conditions:
Press STEP it says “STEP X will end in approx XX:XX:XX”
Press TEMP it says: “S1=xxx S2 = yyy S3=zzz”

These are the spike temperatures and not your process temperature.

Press the arrow key  , you will see: “P1=xxx P2 = yyy P3=zzz”

These are the profile thermocouple temperatures or the temperature where your samples are.

Press GASit says:

G1=XX.X G2=YY.Y G3=ZZ.Z

These are your gas flows in SLPM

Press BOAT it says:

BOAT is In

Press RECIPE it says:

“RECIPE #XXX will end in approx YY:YY:YY”

Unloading Your Sample(s)

When your sample(s) are ready to be unloadedthe tube computer panel will have a solid ALERT light.
Press the EVENT button to the right of the tube when you are ready to unload your sample(s).
The Tube Computer will say:

BOAT UNSTORE ACTIVE

The tube will begin to unload the furnace cantilever.

At the end of the cantilever unload travel, press ENTER/ACK.
When the cantilever is out let your sample(s) and quartz boat cool on the cantilever for a couple of minutes and then use the quartz fork to move your sample(s) and quartz boat to the quartz staging plate. Let your sample(s) and quartz boat cool there for 15 minutes before touching your sample(s) with the vacuum wand or polymer tipped tweezers.
Return the empty quartz boat to the cantilever using the quartz fork.
Press the EVENT button to the right of the tube after putting the quartz boat back.
The Tube Computer will say :

BOAT STORE ACTIVE

The tube will begin to load the cantilever.

Ending Tube Use

When the cantilever is completely reinserted into the tube the process recipe has completed.
The tube panel will have a blinking ALERT light to tell you the recipe is complete.
Press ENTER/ACK.
The tube computer screen will reset for the next process and display:

RECIPE XXX IS WAITING TO START

Finish filling out the run log and clean up the area.
Log out of CRESS.

Troubleshooting:

If you have problems with the furnace talk to a staff member.
The thermal oxide growth calculator does not account for the dry oxidation steps before and after the wet oxidation during wet oxidation recipes, which unaccounted for will cause a higher thickness than expected.

Appendix:

*For thermal oxide growth thickness predictions see the online thermal oxide growth calculator.

*The thermal oxide growth calculator does not account for the 10 minute dry oxidation before and after the wet oxidation during the wet oxidation recipes.

EXAMPLE OF WET OXIDATION RECIPE

STEP # / STEP NAME / STEP TIME (HH:MM:SS)
0 / Idle / 00:00:00
1 / CRESS OK / 00:00:20
2 / Boat Out / 00:07:00
3 / Load Wafer / 00:01:00
4 / Boat In / 00:07:00
5 / Temperature Stabilization / 00:10:00
6 / Ramp Up Temperature / XX:XX:XX
7 / Dry O2 /

00:08:00

8 / Dry O2 + DI Flush /

00:02:00

9 / Wet Oxidation Time /

YOUR TIME

10 / Post Wet Oxide Anneal /

00:10:00

11 / Ramp Down Temperature /

XX:XX:XX

12 / Unload Hold /

00:00:10

13 / Boat Out / 00:07:00
14 / Unload Wafer / 00:01:00
15 / Boat In / 00:07:00
16 / End of Recipe / 00:00:20

EXAMPLE OF DRY OXIDATION RECIPE

YOUR TIME

8 / Ramp Down Temperature / XX:XX:XX
9 / Unload Hold / 00:00:10
10 / Boat Out / 00:07:00
11 / Unload Wafer / 00:01:00
12 / Boat In / 00:07:00
13 / End of Recipe / 00:00:20

EXAMPLE OF ANNEAL PROCESS RECIPE

YOUR TIME

8 / Ramp Down Temperature / XX:XX:XX
9 / Unload Hold / 00:00:10
10 / Boat Out / 00:07:00
11 / Unload Wafer / 00:01:00
12 / Boat In / 00:07:00
13 / End of Recipe / 00:00:20

MRL2 Wet Dry oxidation procedure- 1 - 11/3/15