Chapter 5.9

Tystar9 MOS Clean Silicon Nitride (Si₃N₄)

LPCVD Furnace (4” and 6”)

(tystar9)

1.0 Title

Tystar9 MOS Clean Silicon Nitride (Si₃N₄) LPCVD Furnace (4” and 6”)

2.0 Purpose

Tystar9 is our new 6” LPCVD silicon nitride tube, which is maintained for MOS-clean processes. This tube is capable of processing both 4” and 6” wafers.

3.0 Scope

This document has specific information about Tystar9, our 6” LPCVD silicon nitride deposition tool. 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 lab manual (Tystar/Tylan Furnaces - Overview)

5.0 Definitions and Process Terminology

5.1 MOS tube: Tystar9 is a MOS clean tube dedicated to IC type of fabrication.

5.2 HTO: High temperature oxide deposition process available in the Tystar9 LPCVD tube.

5.3 Dichlorosilane (SiCl₂H₂) commonly referred to as DCS: A gas used in our nitride and HTO processes.

5.4 Ammonia (NH₃): A gas used in our nitride process.

5.5 Nitrous oxide (N₂O): A gas used in our HTO.

5.6 ROP: Remote-operation panel.

5.7 ALMACK : alarm acknowledge is a button used to proceed to next step in recipe.

5.8 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

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

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

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

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

5.13 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 Tystar9 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 & 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 9purge 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 by process staff, before they can be used on any of our Tylan or Tystar furnaces.

6.4 Do not run the tube at temperatures above 800ºC. The furnace will be at its maximum power while maintaining the temperature at 800ºC. This is limited by the design of the heater element and voltage/power rating available on this furnace.

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 Tystar9.

8.0 Available Processes and Gases

Tystar9 tube is assigned to standard nitride processing. HTO is also available for special application.

8.1 Silicon Nitride processes. The standard 9snita recipe uses DCS and NH3 to deposit silicon nitride at 800ºC.

8.2 High temperature oxide (HTO) process: There is a recipe available for this process that can deposit relatively good quality oxide by reacting N₂O and DCS at elevated temperatures. This process however creates high amounts of byproducts and should not be frequently used, as it can clog up the system.

8.3 This tube is calibrated in the 500ºC –800ºC range. Do not attempt to run any processes outside of this temperature range, especially process temperatures above 800ºC are not allowed. This could damage the heating element.

8.4 Available gases on this tube are DCS, NH₃, N₂O, N₂ and 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 TYSTAR9 recipe diskette and Tycom terminal. Run your process. Take your wafers out, after your process is completed. 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: Tystar9 recipes are residing on a dedicated diskette marked as Tystar9 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 are standard nitride and HTO recipes available on Tystar9 disk, as well as 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.

9snita: Standard nitride process, fixed NH3 and DCS.

9vnita: Variable nitride recipe, variable NH3 and DCS.

9VHTOA: Variable high temp oxide recipe, variable N2O and DCS.

9STNBYA: Standby recipe to be used post nitride deposition run.

9PURGE: Additional recipe available to purge and vent the tube.*

9VENT: Additional recipe available to vent the tube.*

Note (*): The vent and purge recipes can be used to 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. There are HTO and variable nitride recipes available on the TYSTAR9 diskette. Talk to process staff if you need to develop other recipes.

9.2.3 Recipe Loading: Type LO followed by recipe name and 9 to load the recipe onto the tube from Tycom terminal. e.g. LO 9snita 9

9.2.4 Running recipe: Once the recipe is loaded you can type RU followed by tube number (9) or simply press run button on the ROC terminal.

9.2.5 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 to cycle back to boat unload step and wait for the boat to come out. You have another 20 minutes to load your wafers.

9.2.6 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 proper standby recipe, before signing off. For a completed nitride recipes, load 9stnbya and press run.

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 9).

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 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 9).

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

9snita			9vnita
Step ------- 01 05 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150 155 160 165	Description --------------------------------------- Initialize & system check Unload Boat Load alarm Load on almack Load boat Check door closed Pump1 Purge1 Pump2 Purge2 Pump3 Leak check Ramp to temp Temp stabilize Temp check Pump4 NH3 flow (75 sccm) Pressure set (300 mTorr) Pressure stabilization DCS flow (25 sccm) Deposition step NH3 purge 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 10 min 5 sec 20 min 10 min 2 min 5 min 2 min 2 min 2 min 2 min 1 min 1 hr 2 min 5 min 2 min 1 min 1 min 1 min 1 min Variable 5 min 2 min 2 min 2 min 2 min 2 min 2 min 1 hr 5 sec 1 sec 5 min 7 min	Step ------- 01 05 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150 155 160	Description ----------------------------------------- Initialize & system check Unload Boat Load alarm Load on almack Load boat Check door closed Pump1 Purge1 Pump2 Purge2 Pump3 Leak check Ramp to variable temp. Temp stabilize Temp check Pump4 NH3 flow (STD 75 sccm) Pressure set (300 mTorr) DCS flow (25 sccm) Deposition step NH3 purge Pump1 Purge1 Pump2 Purge2 Pump3 Purge3 Flush and hold Branch to back fill Loop back to flush & hold Backfill-1 Backfill-2 End	Time ----------- N/A 10 min 5 sec 20 min 10 min 2 min 5 min 2 min 2 min 2 min 2 min 1 min Variable 2 min 5 min 2 min Variable 30 sec 1 min Variable Variable 2 min 2 min 2 min 2 min 2 min 2 min 1 hr 5 sec 1 sec 5 min 7 min

9vhtog				9stnbya
Step -------- 01 05 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150 155 160	Description ------------------------------------------------------- Initialize & system check Unload Boat Load alarm Load on almack Load boat Check door closed Pump1 Purge1 Pump2 Purge2 Pump3 Leak check Ramp to temp Temp stabilize Temp check Pump4 N2O flow (Variable, STD 100 sccm) Pressure set (variable, STD 300 mTorr) DCS flow (Variable, STD 20 sccm) Deposition step N2O purge Pump1 Purge1 Pump2 Purge2 Pump3 Purge3 Flush and hold Prepare to back fill Loop back to flush & hold Backfill-1 Backfill-2 End	Time ----------- N/A 10 min 5 sec 20 min 10 min 2 min 5 min 2 min 2 min 2 min 2 min 1 min Variable 2 min 5 min 2 min Variable 1 min 1 min Variable Variable 2 min 2 min 2 min 2 min 2 min 2 min 1 hr 5 sec 1 sec 5 min 7 min	Step ------- 01 05 10 15 20 25 30 35 40 45 50 55 60	Description ---------------------------------- Initialize Load Check door closed Short pump Degas pump Hard pump Leak check Standby Branch to soft vent Loop back to standby Backfill-1 Backfill-2 End	Time ---------- N/A 10 min 2 min 2 min 10 min 2 min 1 min 1 hr 5 sec 1 sec 5 min 7 min

Tystar 9 Study Guide

Be sure to know…

1. MOS-clean vs. non-NOS-clean rules

2. Gases used for nitride and HTO deposition

3. Loading and unloading wafers

4. What each interlock message means

5. 9purge vs. 9vent recipes and safety concerns

6. Procedure for writing a new recipe

7. Maximum temperature allowed

8. Venting the tube

9. Additional pump and purge cycles

10. Which standby recipe to use after n`*itride and HTO

11. Wafer loading time

12. Leak check failure and troubleshooting

13. Control panel button function

14. Checking tube status