Nitride Deposition SOP Page 1 of 14 Revision

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1 Nitride Deposition SOP Nitride Deposition SOP Page 1 of 14 1 Scope 1.1 This document provides the procedures and requirements to deposit silicon nitride films, using the Canary LPCVD furnace. 2 Table of Contents 1 Scope Table of Contents Reference Documents Referenced within this Document External Documents Equipment and/or Materials Safety Setup Procedures Enable Furnace Turn on Burn Box Vent Furnace Remove Boat Select Program and Temperature Set Gas Flows Set Pressure Load Program Set Deposition Time Load Sample Wafers Film Deposition Procedures Load Furnace Start Program/Verify Door Closure Leak Check Verify Burn Box Deposition Pressure Check Unload Process Measurement Burn Box Off Place System in Standby Disable Furnace Process Notes and Characterization Typical Film Characteristics Gas Flow Setpoint Conversions Pressure Controller Setpoints Auto-Sequencer Output Assignments Temperature Controller Recipes Auto-Sequencer Programs Revision History... 14

2 Nitride Deposition SOP Page 2 of 14 Figure 1, Nitride Gas Controller... 4 Figure 2, Pressure Controller... 4 Figure 3, Nitride Boat Loading Diagrams... 5 Figure 4, Push Rod Alignment... 6 Figure 5, Furnace DMM Switch... 6 Table 1, Nitride Programs... 3 Table 2, Nitride Gas Flow Setpoint Conversions Table 3, Nitride Pressure Controller Setpoint Table 4, Nitride Auto-Sequencer Output Assignments Table 5, Nitride Temperature Controller Setup Table 6, Nitride Auto-Sequence Controller Setup Reference Documents 3.1 Referenced within this Document Ecosys Burn Box SOP Canary Furnace SOP 3.2 External Documents None 4 Equipment and/or Materials 4.1 Ammonia (NH 3 ), 99.9% or better 4.2 Dichlorosilane (SiCl 2 H 2 ), Electronic Grade 2 (99.9%) or better Dichlorosilane is often identified as DCS. 4.3 Canary LPCVD Furnace 4.4 Nitride quartz boat 4.5 Quartz push rod with mark at 26 from hook 4.6 Heat-resistant gloves 4.7 Monitor wafers (bare silicon <100>) 5 Safety 5.1 Follow all Nanofab safety procedures. 5.2 Do NOT open the element door (danger of high voltage). 5.3 This system uses hazardous gases, specifically Dichlorosilane (SiCl 2 H 2 ) and Ammonia (NH 3 ). Refer to MSDS for more detail Do NOT adjust any regulators or valves for any gases. 5.4 Do NOT store flammable solvents (e.g., squeeze bottles, etc.) near the furnace or loading station.

3 Nitride Deposition SOP Page 3 of Do NOT touch quartz boats with your hands. They may be hot. Use only a clean quartz boat holder or high temperature gloves. 5.6 Do NOT touch quartz or wafers with wipes, gloves, teflon, plastic, etc. 5.7 Place quartz only on dedicated quartz carriers, quartz surfaces, or stainless steel surfaces. 6 Setup Procedures 6.1 Enable Furnace In Coral, enable the furnace and complete all required data entry. 6.2 Turn on Burn Box Enabling the furnace will release the interlock and provide access to the keypad Follow the procedures in the Ecosys Burn Box SOP to ensure the burn box is on Write your name, date, and equipment name on the Burn Box User white board. 6.3 Vent Furnace Following the procedures in Canary Furnace SOP, load and start the Vent program (see Table 1, Nitride Programs). Table 1, Nitride Programs Loop Counter Setpoint Approx. Run Time (min) Program Description Step for Deposition Time NH3 (V) DCS (V) Press Pre-Dep Deposition Post-Dep 0 Low-Stress Nitride (825 C) User defined 21 1 Stoichiometric Nitride (780 C) User defined 21 2 Custom, written as needed n/a n/a n/a 3 Custom, written as needed n/a n/a n/a 4 Custom, written as needed n/a n/a n/a 5 Pump Down/Idle n/a n/a n/a 6 Vent n/a n/a n/a Wait for the program to finish and the auto-sequencer to advance to step Remove Boat Using the high temperature gloves, open the furnace door Using the high temperature gloves or the quartz handle, remove the boat from the furnace and place on the quartzware rack Using the high temperature gloves, close the furnace door Allow the boat and wafers to cool at least 5 minutes. 6.5 Select Program and Temperature Review the pre-defined programs shown in Table 1, Nitride Programs.

4 6.5.1 Identify the desired program If the desired conditions (temperature, gas flows, or pressure) are NOT shown in Table 1, Nitride Programs, contact the Lab Staff before proceeding. The Lab Staff can create custom programs, as needed. 6.6 Set Gas Flows Using Table 1, Nitride Programs, find the voltage setpoints for each of the gases On the Silicon Nitride LPCVD Sys. gas controller located in the gas jungle (see Figure 1, Silicon Nitride LPCVD Sys. Gas Controller), rotate the selection knob on the gas controller to select the desired gas. Nitride Deposition SOP Page 4 of 14 Setpoint Dials Set/Read Switch Selection Knob While holding the toggle switch on SET, adjust the setpoint dial until the MFC Voltage Display shows the correct value Repeat through for each process gas Rotate the selection knob to PRESSURE. 6.7 Set Pressure Using Table 1, Nitride Programs, find the pressure control setpoint Adjust the dial on the controller (see Figure 2, Pressure Controller) to the desired setpoint setting. MFC Voltage Display Figure 1, Silicon Nitride LPCVD Sys. Gas Controller Setpoint Control Dial Figure 2, Pressure Controller!! WARNING!! 6.8 Load Program Following the procedures in Canary Furnace SOP, load the desired program. Do not change any other dial or switch on the controller.!! WARNING!! The controller will change to the first step of the program and immediately go on hold with 10 seconds on the time display. The READY light will be on.

5 Nitride Deposition SOP Page 5 of Verify the number of the desired program is shown in the Program Display field of the Auto- Sequence Controller If the correct number is NOT displayed, repeat through Following the procedures in Canary Furnace SOP, release the hold. The RUN light will be on. The program will count down to 0 on the time display and go on hold. The READY light will be on again. 6.9 Set Deposition Time Following the procedures in Canary Furnace SOP, set the value of the applicable loop counter step to the desired number. (Refer to Table 1, Nitride Programs to find the correct loop counter step for the program being used.) One loop is one minute of deposition. For example, to get 45 minutes of deposition, set the loop counter to If you need a deposition step longer than 360 minutes, contact lab staff for approval before proceeding Load Sample Wafers Ensure all wafers are completely clean, dry, and free of any surface contamination.!! WARNING!! No photoresist, kapton tape, metals, or other foreign material are allowed in the furnace. Only quartz, silicon, oxide, nitride, and/or Polysilicon are allowed without lab staff approval.!! WARNING!! Using the vacuum wand, load the wafers as shown in Figure 3, Nitride Boat Loading Diagrams The polished side of the wafers are to face away from the handle end of the boat Ensure there are five (5) dummy wafers loaded in consectutive slots at each end of the boat Include a monitor wafer at the center of the boat. Monitor wafers are provided in a labeled box located on the storage rack. Sample wafers that are bare silicon may also be used as monitor wafers Load sample wafers from the center of the boat. Dummy Wafer Monitor Wafer Sample Wafer \ \ / / Test Run Polished Side Handle \ \ / / Sample Run Figure 3, Nitride Boat Loading Diagrams

6 7 Film Deposition Procedures 7.1 Load Furnace Using the high temperature gloves, open the furnace door Place the boat at the end of the furnace tube Samples should face the rear (pump) end of the furnace Using the quartz push rod, push the boat into the furnace at 1 inch every 5 seconds (12 inches per minute) Align the mark on the push rod to the front face of the furnace scavenger (see Figure 4, Push Rod Alignment) Remove the push rod and place in the storage cylinder Using the high temperature gloves, close the furnace door. Nitride Deposition SOP Page 6 of Start Program/Verify Door Closure Using the high temperature gloves, hold the furnace door closed Following the procedures in Canary Furnace SOP, release the hold. The READY light will turn off and the RUN light will turn on. The controller will automatically execute the necessary steps to complete the nitride deposition process. A summary of the programs, steps, and outputs is given in Table 6, Nitride Auto-Sequence Controller Setup Hold the door closed for 30 seconds Gently pull on the door to ensure it is sealed If the door opens, hold the door securely closed for 60 seconds If the door still does not seal, hold the program and contact the lab staff for assistance. 7.3 Leak Check The program will automatically go on hold at the end of the pump down step (step *2) Record the Start Pressure as the value shown on the Nitride Pressure Display (see Figure 5, Nitride Pressure Display). The display is shown in millivolts. Figure 4, Push Rod Alignment Push Rod Mark Align Mark to Scavenger Face Figure 5, Nitride Pressure Display Scavenger Face

7 Nitride Deposition SOP Page 7 of Following the procedures in Canary Furnace SOP, release the hold. The duration of the leak check step is 1 minute. At the end of the step the program will again go on hold. It is important to be at the controller when the time expires Record the End Pressure as the value shown on the Nitride Pressure Display If the Leak Rate is greater than 10 mv/min, do the following: Following the procedures in Canary Furnace SOP, abort the program Vent the furnace as per paragraph Using a clean room wipe, clean the surfaces of the door and the door flange Repeat If the Leak Check still fails, contact the lab staff for assistance Following the procedures in Canary Furnace SOP, release the hold. 7.4 Verify Burn Box The program will continue until complete Ensure the temperature on the burn box is between C If it is not, following the procedures in Canary Furnace SOP, place the program on hold Contact the lab staff for assistance. 7.5 Deposition Pressure Check During deposition verify the voltage readout on the Nitride Pressure Display. This should be done between 3-10 minutes after the start of deposition If it is not stable, contact the lab staff If it is not the desired value, adjust the Controller Setpoint as necessary Record the deposition pressure. 7.6 Unload Verify the program is complete. The controller will be on step Using the high temperature gloves, open the furnace door Using the quartz push rod, pull the boat to the door of the furnace at 1 inch every 5 seconds (12 inches per minute) Place the push rod in the storage cylinder Allow the boat to cool a minimum of 2 minutes at the door of the furnace Using the high temperature gloves or the quartz handle, remove the boat from the furnace and place on the quartzware rack Allow the boat and wafers to cool at least 5 minutes.

8 Nitride Deposition SOP Page 8 of Using the vacuum wand, remove the sample and monitor wafers from the quartz boat. 7.7 Process Measurement Complete all post-processing measurements of the monitor wafers or samples Place used monitor wafers in the labeled storage box located on the storage rack. 7.8 Burn Box Off If no other lab user is using the burn box, follow the procedures in the Ecosys Burn Box SOP to turn the burn box off Erase your name from the Burn Box User white board. 7.9 Place System in Standby This section is only necessary if the furnace will be idle for more than 1 hour Using the high temperature gloves, open the furnace door Place the boat at the end of the furnace tube Using the high temperature gloves, hold the furnace door closed Follow the procedures in Canary Furnace SOP to load and start the Pump Down/Idle program (see Table 1, Nitride Programs) Hold the door closed for 30 seconds Gently pull on the door to ensure it is sealed If the door opens, hold the door securely closed for 60 seconds If the door still does not seal, hold the program and contact the lab staff for assistance Disable Furnace In Coral, disable the furnace and complete all data entry, including process measurement data. Disabling the furnace will activate the interlock and prevent access to the keypad. 8 Process Notes and Characterization 8.1 Typical Film Characteristics Film deposition parameters DCS flow: 60 sccm (3V) Ammonia flow: 10 sccm (0.25 V) DCS:Ammonia ratio: 6:1 Temperature: 825 C Deposition Pressure 332 mt (166 mv) Deposition Rate: Approximately 6.5nm/min (65Å/min) The silicon-rich LPCVD silicon nitride film was analyzed in the XPS on 10 May 2007 (Loren). Results of XPS analysis: Si: 48.3% and N: 51.7% Si1.0N1.07

9 Nitride Deposition SOP Page 9 of The silicon-rich LPCVD silicon nitride film was analyzed in the Woollam ellipsometer on 9 May 2007 (Mickey). Wavelength (nm) Index of Refraction (n) The stress of the silicon-rich LPCVD silicon nitride film was measured using the wafer bow technique on (Divesh) Results of stress analysis: Film has a residual tensile stress of 300 MPa KOH Etch Mask You need at least 100 nm of Silicon-rich nitride for a good KOH mask layer This nitride film is an excellent free-standing membrane layer.

10 8.2 Gas Flow Setpoint Conversions Nitride Deposition SOP Page 10 of Table 2, Nitride Gas Flow Setpoint Conversions shows the voltage settings needed to obtain the desired gas flows. Table 2, Nitride Gas Flow Setpoint Conversions Setpoint Display Setpoint Display Setpoint Display NH3 (sccm) DCS (sccm) Volts (V) NH3 (sccm) DCS (sccm) Volts (V) NH3 (sccm) DCS (sccm) Volts (V) Max flow NH3: V = 5*sccm/200 DCS: V = 5*sccm/ Pressure Controller Setpoints Table 3, Nitride Pressure Controller Setpoint shows the approximate settings needed to obtain the desired pressure. Table 3, Nitride Pressure Controller Setpoint mtorr mv Setpoint mtorr mv Setpoint mtorr mv Setpoint mtorr mv Setpoint The values for Setpoint are only approximate. Adjust the setpoint as necessary to obtain the mv value for the desired pressure. For values not included in the table, the following formulas can be used: Setpoint = * mtorr mv = * mtorr

11 8.4 Auto-Sequencer Output Assignments Nitride Deposition SOP Page 11 of Table 4, Nitride Auto-Sequencer Output Assignments shows the assignments of the output connections for the auto-sequencer. Table 4, Nitride Auto-Sequencer Output Assignments Output Description Output Description 1 N2 (0.020 orifice) 9 Temperature Control Bit1 2 NH3 Upstream Valve 10 Temperature Control Bit2 3 NH3 Downstream Valve 11 Temperature Control Bit3 4 DCS Upstream Valve 12 Temperature Control Bit4 5 DCS Downstream Valve 13 Throttle Control Full Open 6 DCS Bypass Valve (capped) 14 Vacuum Soft Start 7 N2 (0.040 orifice) 15 Slow Pump Valve 8 Not used 16 Hard Pump Valve 8.5 Temperature Controller Recipes Table 5, Nitride Temperature Controller Setup shows the setup of the temperature controller. Table 5, Nitride Temperature Controller Setup Recipe Setpoint Auto-Sequencer Outputs variable* n/a n/a n/a n/a *Maximum Allowed Temperature: 825 C Ramp Rate (Slope) for all recipes and zones: 10.00

12 Nitride Deposition SOP Page 12 of Auto-Sequencer Programs Table 6, Nitride Auto-Sequence Controller Setup shows the defined program steps. Table 6, Nitride Auto-Sequence Controller Setup Output LED s Step Instruction Program Alarm Change Branch Temp Program # Function # Description Start Enable Enable Step ( C) Time Push Load/Close Door 6 HOLD AT END YES Slow Pump/Ramp Up 4 HOLD WITH OUTPUTS Hard Pump/Ramp Up 6 HOLD AT END Leak Check 6 HOLD AT END Ramp and Stabilize 4 HOLD WITH OUTPUTS NH3 Presoak 4 HOLD WITH OUTPUTS Start Loop 1 SET LOOP Counter YES *** 0 7 Deposition 4 HOLD WITH OUTPUTS End Loop 2 LOOP BACK Purge and Vent 7 BRANCH AT END Push Load/Close Door 6 HOLD AT END YES Slow Pump/Ramp Up 4 HOLD WITH OUTPUTS Hard Pump/Ramp Up 6 HOLD AT END Leak Check 6 HOLD AT END Ramp and Stabilize 4 HOLD WITH OUTPUTS NH3 Presoak 4 HOLD WITH OUTPUTS Start Loop 1 SET LOOP Counter YES *** 1 17 Deposition 4 HOLD WITH OUTPUTS End Loop 2 LOOP BACK Purge and Vent 7 BRANCH AT END none 0 No operation YES none 0 No operation none 0 No operation none 0 No operation none 0 No operation none 0 No operation none 0 No operation none 0 No operation none 0 No operation none 0 No operation none 0 No operation YES none 0 No operation none 0 No operation none 0 No operation none 0 No operation none 0 No operation none 0 No operation none 0 No operation none 0 No operation none 0 No operation 0.0

13 Nitride Deposition SOP Page 13 of 14 Table 6, Nitride Auto-Sequence Controller Setup Output LED s Step Instruction Program Alarm Change Branch Temp Program # Function # Description Start Enable Enable Step ( C) Time none 0 No operation YES none 0 No operation none 0 No operation none 0 No operation none 0 No operation none 0 No operation none 0 No operation none 0 No operation none 0 No operation none 0 No operation none 0 No operation none 0 No operation none 0 No operation none 0 No operation none 0 No operation none 0 No operation Post Dep NH3 Purge 4 HOLD WITH OUTPUTS NH3 Evacuation 4 HOLD WITH OUTPUTS N2 Post Purge 4 HOLD WITH OUTPUTS N2 Evacuation 4 HOLD WITH OUTPUTS Vent 7 BRANCH AT END Slow Pump/Ramp Up 4 HOLD WITH OUTPUTS YES Hard Pump/Ramp Up 6 HOLD AT END Vent 7 BRANCH AT END YES Power out Program 0 6 HOLD AT END YES Power out Program 1 6 HOLD AT END YES Power out Program 2 6 HOLD AT END YES Power out Program HOLD AT END YES Abort 6 HOLD AT END YES Idle Step 6 HOLD AT END *** This value is adjusted as necessary between Time values with a decimal are in minutes; values without a decimal are in seconds.

14 Nitride Deposition SOP Page 14 of 14 9 Revision History Rev Date Orginator Description of Changes 7 12 May 2011 T. Olsen Update gas flow setting, leak check, and deposition pressure check instructions (sections 6.6, 7.3, and 7.5) to reflect the replacement of portable multi-meters with a permanently mounted voltage display, including Figure 1, Figure 5, and Table Mar 2011 T. Olsen Replace references to log sheets with Enable/Disable in Coral and required data entry. Clarify use and availability of monitor wafers. Update Figure 3, Nitride Boat Loading Diagrams to match the new nitride boat style Jul 2010 T. Olsen Change length of push rod mark from 30 to 26. Update Table 2, Nitride Programs to include gas flows (move table to Table 1). Update Loading Diagram and instructions include dummy wafers and wafer spacing. Updated Table 1, Nitride Programs and Table 6, Nitride Auto-Sequence Controller Setup to remove unused programs. Add instructions to store boat in furnace when not in use Mar 2010 T. Olsen Clarified some autosequence terminology. Added Pre- Post-Dep times to Table 3. Added polished side to boat loading diagram Feb 2010 T. Olsen Updated procedures to change from Manual operation of controller to Auto mode with pre-defined programs Sep 2009 T. Olsen Updated some cross-references for temperature setpoint entry and added an approximate deposition rate for standard process Aug 2009 T. Olsen Conversion of original document to Word. Updated most procedures for better usability and process control.