Chapter 5.11

Tystar11 MOS Clean LTO LPCVD Furnace (4” and 6”)

(tystar11)

1.0 Title

Tystar11 MOS Clean LTO LPCVD Furnace (4” and 6”)

2.0 Purpose

Tystar11 is a 6” LPCVD tube, which is maintained for MOS-clean LTO / PSG processes. This tube is capable of processing both 4” and 6” wafers

3.0 Scope

This document has specific information about LPCVD Tystar11 furnace. This is our 6” MOS-clean tube dedicated to undoped low temperature oxide (LTO) or phosphorous-doped low temperature oxide (PSG) processes. For general information on LPCVD furnaces, please refer to Chapter 5.0 of the lab manual, operation and pertinent information.

4.0 Applicable Documents

Revision History

Chapter 5.0 of the lab manual (Tystar/Tylan LPCVD Furnaces - Overview)

5.0 Definitions & Process Terminology

5.1 MOS tube: Tystar11 is a MOS clean tube dedicated to IC type fabrication (MOS clean).

5.2 LPCVD: Low pressure chemical vapor deposition

5.3 LTO: Low temperature silicon dioxide.

5.4 PSG: Phospho-silicate glass

5.5 Silane (SiH₄): A gas used in our LTO (doped & undoped) processes.

5.6 Phosphine (PH₃): A gas used in our doped LTO process (PSG).

5.7 Oxygen: A gas used in LTO (doped & undoped) processes.

5.8 ROP: Remote-operation panel.

5.9 ALMACK: Alarm Acknowledge is a button used to proceed to next step in recipe.

5.10 ABORT: This key can be used to abort the process. This is commonly used for unloading the wafers, where users invoke the recipe again, after run has been completed and properly vented. The tube will open for the users to unload their wafers followed by abort to load the standby recipe, and before leaving the area.

Machine interlock messages

5.11 ANTLK: Above atmosphere interlock, no process gas can flow (including N₂).

5.12 BNTLK: Below process pressure interlock, no process gas can flow.

5.13 DNTLK: Door interlock, door is not closed; no process gas can flow.

5.14 GNTLK: Gate valve interlock, gate valve is not open, no process gas can flow.

5.15 VNTLK: Vacuum interlock, pump problem, no process gas can flow.

6.0 Safety

Follow general safety guidelines in the lab as well as the specific safety rules as per follows:

6.1 Tystar11 utilizes potentially hazardous gases and high electric power (high amperages to heat its elements). Do not open the front or the back panels, as it can expose you to high power circuitry.

6.2 Special care must be taken when the tube is aborted and while in deposition step. The toxic process gases present will need to be properly vented. This can be accomplished by acknowledging out of flush and hold steps of the standard recipes. In an emergency situation (Earthquake, fire) the process can be aborted. Make sure toxic gases are properly vented by a series of pump and purges and by running the 11purge recipe. Ask process staff if you need help or if you have any questions in this regard. Do not alter any of the standard processes and specially do no skip any important purge or vent step in your recipes.

6.3 All new recipes have to be checked off by process staff.

6.4 Do not run Tystar11 at temperatures above 500ºC. This furnace is calibrated for Low Temperature oxide process, typically at 450ºC, should not be used at elevated temperatures. Also, accumulated film (deposited film) on the furnace wall can easily stress and crack the quartz tube.

7.0 Statistical/Process Data

Pertinent information can be found on the following sites:

7.1 Process monitoring test section of the Microlab’s home page.

7.2 Problem and comments section under equipment section of the wand.

7.3 Enable message for Tystar11.

8.0 Available Processes, Gases, Process Notes

Tystar11 tube is assigned to LTO/PSG processes (undoped and Phosphorous doped, respectively). There are three main recipes available on the tool. This includes standard doped and undoped LTO as well as a variable doped recipe. The latter allows for the user to change the value of phosphine gas used in the recipe. These recipes have an additional step (70), which sets the proper K value to speed up the temp stabilization process.

8.1 Standard undoped LTO process: The standard 11sultoa recipe uses fixed amount of Silane and Oxygen, no Phosphine to deposit low temperature silicon dioxide film at around 450ºC.

8.2 Standard fixed doped LTO process (PSG): The standard 11sdltoa recipe uses fixed amount of Silane, Oxygen and Phosphine to deposit phospho-silicate glass film (PSG) at 450ºC.

8.3 Variable PSG process: The variable 11vdltoa recipe provides the flexibility to change the amount of phosphine, silane and oxygen gases in the recipe, therefore, varying the amount of phosphorous in the final film (PSG).

8.4 Deposited PSG film is porous, therefore it is highly recommended to immediately anneal the film, after deposition. This should prevent moisture absorption and possible crystallization.

8.5 This tube is calibrated at 450ºC. Do not attempt to run any processes above 500ºC.

8.6 Available gases on this tube are Silane (SiH₄), Phosphine (PH₃), Oxygen (O₂), Nitrogen (N₂) and Nitrogen (N₂) VAC.

9.0 Furnace Operation

9.1 Control Key description: Many of the operational commands can be executed from ROP. Function keys such as Recipe, Run, Hold, Clock, Status and more are also available. Appendix 1 at the end of this chapter displays all these function keys. There are two ALMACK keys available on the ROP. The one on the far right side just above the ABORT key is the main one to use.

9.2 Operational procedure/guidelines: Recipes can be loaded from TYSTAR11 recipe diskette and Tycom terminal. Run your process as per operational guidelines outlined below, then unload your wafers. Note, you will need to wait for the boat to completely go back in, before you can load the standby recipe. This means, once you find your run completed, ALMACK twice out of the flush & hold step, then run the recipe again, get your wafers out (This takes about 12 minutes). Then, ALMACK through the unload step to send the boat in and make sure the door is completely closed, before you ABORT the process. Finally, load the standby recipe. Please note, aborting the tube before the boat-loading step is completed, stops the boat loader in its track with the door open.

9.2.1 Recipes: Tystar11 recipes are residing on a dedicated diskette marked as Tystar11 recipes. These recipes have a standard format with three pump and purge cycles before and after the deposition step. This is designed to better control the film particles by keeping the tube cleaner. There is also an additional temperature stabilization step incorporated into these recipes, which is designed to optimize the ramp up time towards the target deposition temperature. Six recipes are available on this furnace which are: standard undoped LTO; standard doped LTO (PSG); standard variable LTO; standby; vent and purge recipes. The vent and purge recipes are designed to speed up recovery process.

See Appendix 2 for more details on the available recipes.

11sultoa recipe

11sdltoa recipe

11vdltoa recipe

11lto400

11stnbya recipe

11purge recipe

11Vent recipe

Standard undoped LTO, fixed SiH₄ and O₂.

Standard doped LTO (PSG), fixed SiH₄, O₂ and PH₃.

Variable doped LTO (PSG), variable PH₃ , SiH₄ and O₂gases.

Undoped LTO, fixed temperature at 400 ºC.

Standby recipe should be loaded after you are done.

Additional recipe available to purge and vent the tube.*

Additional recipe available to vent the tube.*

Note (*): The vent and purge recipes can be used for quick vent or pump/purge cycles. The abort as you know, takes the recipe back to its first step. This may take a long time for the tube to vent. This is because the initial step bleeds only about one liter of nitrogen into the tube, in which case it takes a long time to bring the tube to atmosphere. This can be accomplished much faster by loading one of the two recipes noted above, however take extreme care and make sure that you do not use the vent recipe when harmful gases are present (abort at deposition step), load the purge recipe instead. This can come handy when the abort has occurred, while still in deposition step or if the origin of the abort sequence is not known. (Did it abort at deposition step?)

9.2.2 Recipe modification and new recipe generation: As always, modification to standard recipes is not allowed. Talk to process staff if you need to develop special application recipes.

9.2.3 Check standby recipe is running. Press ALMACK twice and wait 12 minutes for the tube to vent.

9.2.4 Recipe Loading: Type LO followed by recipe name and 11 to load the recipe onto the tube from Tycom terminal. e.g. LO 11sultoa 11

9.2.5 Running recipe: Once the recipe is loaded you can type RU followed by tube number 11 or simply press run button on the ROC terminal.

9.2.6 Wafer Loading: Once the boat is out, replace dummy wafers with your work wafers. There is a 20 minutes window available for this task. Once the 20 minutes elapses, the boat loader will automatically go in. Do not worry, simply ALMACK through, cycle back to boat unload step and wait for the boat to come out. You have another 20 minutes to load your wafers.

9.2.7 Unloading wafers. Once the process is completed the furnace will wait in flush and hold step. You will need to ALMACK twice out of this step to vent the tube. You will need to run the recipe again, so that the boat loader will bring the tube out. You will then need to ALMACK to send the boat in and wait for the door to completely close. You can then abort the process and load the standby recipe, before signing off.

9.2.8 Standby recipe (finishing up): Once your run is completed and your work wafers are out, you will need to load and run the standby recipe 11stnbya.

10.0 Troubleshooting Guidelines

10.1 Failed Leak Check

10.1.1 Check the machine status screen on the Tycom terminal (type in DI ST 11).

10.1.1.1 If GNTLK or VNTLK is ON, stop and report it as fault.

10.1.1.2 If DNTLK is ON, vent the tube. Run the process again. Try this a couple of times, if necessary. Report as fault, if still fails. There may be door sensor problems.

10.1.1.3 If no interlock is ON, vent the tube wipe the door and the o-ring. Run the process again. If it still fails, report it as fault.

10.2 No Process Gas Flow

10.2.1 Check the machine status screen on the Tycom terminal (type in DI ST 11).

10.2.1.1 If any interlock is ON, report it as fault.

10.2.1.2 Check the appropriate gas cylinder, if empty report as fault.

Appendix 1

Appendix 2

Recipes

11sultoa 11sdltoa

Step

---------

100

105

110

115

120

125

130

135

140

145

150

155

160

Description

--------------------------------------

Initialize & system check

Unload alarm

Unload Boat

Load on almack

Load alarm

Load boat

Check door closed

Pump1

Purge1

Pump2

Purge2

Pump3

Leak check

Ramp to temp

Set K Variable

Temp stabilize

Temp check

Pump4

Process gas flows

Pressure set (300 mTorr)

Deposition step (PH₃= 0)

Pump1

Purge1

Pump2

Purge2

Pump3

Purge3

Flush and hold

Branch to backfill

Loop back to flush & hold

Backfill-1

Backfill-2

End

Time

-----------

N/A

3 sec

10 min

20 min

3 sec

10 min

2 min

5 min

2 min

1 min

30 min

1 min

5 min

2 min

1 min

Variable

2 min

1 hr

5 sec

1 sec

5 min

7 min

N/A

Step

---------

100

105

110

115

120

125

130

135

140

145

150

155

160

Description

----------------------------------------

Initialize & system check

Unload alarm

Unload Boat

Load on almack

Load alarm

Load boat

Check door closed

Pump1

Purge1

Pump2

Purge2

Pump3

Leak check

Ramp to temp

Set K Variable

Temp stabilize

Temp check

Pump4

Process gas flows

Pressure set (300 mTorr)

Deposition step (PH₃= fix)

Pump1

Purge1

Pump2

Purge2

Pump3

Purge3

Flush and hold

Branch to backfill

Loop back to flush & hold

Backfill-1

Backfill-2

End

Time

-----------

N/A

3 sec

10 min

20 min

3 sec

10 min

2 min

5 min

2 min

1 min

30 min

1 min

5 min

2 min

1 min

Variable

2 min

1 hr

5 sec

1 sec

5 min

7 min

N/A

11vdltoa 11stnbya

Step

---------

100

105

110

115

120

125

130

135

140

145

150

155

160

Description

---------------------------------------------

Initialize & system check

Unload alarm

Unload Boat

Load on almack

Load alarm

Load boat

Check door closed

Pump1

Purge1

Pump2

Purge2

Pump3

Leak check

Ramp to temp

Set K Variable

Temp stabilize

Temp check

Pump4

Process gas flows

Pressure set (300 mTorr)

Deposition step (PH₃ = variable)

Pump1

Purge1

Pump2

Purge2

Pump3

Purge3

Flush and hold

Branch to backfill

Loop back to flush & hold

Backfill-1

Backfill-2

End

Time

-----------

N/A

3 sec

10 min

20 min

3 sec

10 min

2 min

5 min

2 min

1 min

30 min

1 min

5 min

2 min

1 min

Variable

2 min

1 hr

5 sec

1 sec

5 min

7 min

N/A

Step

-------

Description

-------------------------------

Initialize

Load

Check door closed

Short pump

De-gas pump

Hard pump

Leak check

Standby

Branch to backfill-1

Loop back to standby

Backfill-1

Backfill-2

end

Time

------------

N/A

10 min

2 min

10 min

2 min

1 min

1 hr

5 sec

1 sec

5 min

7 min

N/A

Tystar 11-12 Study Guide

Be sure to know…

1. Tystar 11 is MOS-clean; Tystar 12 is non-MOS clean.

2. Unloading wafers and leaving the tube in standby.

3. The meaning of the interlocks: DNTLK, GNTLK, VNTLK.

4. Safety concerns if process is aborted in deposition step.

5. Difference between recipes: 11SULTOA, 11SDLTOA, and 11VLTOA.

6. How to set up a new recipe.

7. If you ABORT before boat loading is complete.

8. Unloading wafers after deposition.

9. The meaning and purpose of pump and purge.

10. Loading wafers: time limits and extending loading time.

11. If the tube fails leak check.

12. If there is no process gas flow.