Low Temperature Probe Station (LTPS) Assembly and Disassembly Procedures I. Introduction This is a new document detailing with pictures the procedure to disassemble, prep and clean, and reassemble the LTPS for testing device. For more information to properly maintain and operate the LTPS, refer to B. Cheek's Low Temperature Probe Station (LTPS) Operating Procedures document. II. Procedure Methods and Materials. NOTE: It is required to wear gloves during the disassembly and assembly of the LTPS! Must also use safety glasses when handling any chemicals, i.e. vacuum grease, thermal Ngrease, IPA, methanol Disassembly of the LTPS 1. Use the silver screws with rings and screw them down in the two open holes on the outer top shield to make transporting it later much easier. Don t tighten screws as this will damage probe station. The lid is heavy. 2. Remove each screw one by one on the top shield and place the screws somewhere secure and clean. (For step 1 & 2, see Fig. 1) Silver screws Outer top shield Fig. 1 Silver screws with rings and removing the screws 1
3. Place the outer shield on a clean and secured area, such as the wafer handling station. 4. Before removing the screws on the inner radiation shield (lid w/ Mylar tape), place the shield ring (RIFAD) down to help prevent screws from falling to the chamber. DO NOT DROP SCREWS INTO CHAMBER! They cannot be recovered easily and can damage the system! (For step 4 see Fig. 2) Shield ring Inner radiation shield Fig. 2 Placing the shield ring in. NOTE: Remember to wear gloves! 5. The screw handle for the inner radiation shield can be attached to the inner radiation shield now. (Fig. 3) Do not tighten the handle screw as this will cause damage to the radiation shield. 6. Remove each screw one by one and place in a safe and secured area. After the screws have been safely removed, the shield ring can be removed. Make sure all screws have been removed properly! (Fig. 4) 7. Remove the inner radiation shield and carefully place it in a safe and clean area. Be careful not to tear the Mylar tape! 2
Screw handle Fig. 3 Handle for inner shield Fig. 4 Removing screws 8. You are now at the inner chamber of the LTPS. (Fig. 5) Fig. 5 Inner chamber of LTPS Loading a sample 1. Loosen the screws to the sample holders (need at least 2 hold down spots per sample) 2. Place the sample on the center of the stage, or between the desired probes 3. Tighten the screws, not too tightly or sample may be damaged 4. Verify the condition of the probes is good and each will make contact to the sample a. Maneuver the optics and physically check the probes using the camera system. Once the system is reassembled it will be too late--must disassemble and start over! b. Check that all devices can be reached by the probes, otherwise reposition the sample. c. At final inspection, make sure that the probes are at least ¼ off the sample before closing the system. Once vacuum is applied, the probes 3
will dive towards the sample surface and potentially damage the probes or the sample. Cleaning 9. To clean the station, you will need Isopropanol, Vacuum grease, Ngrease/Thermal Grease, and TechniCloth wipers. (Fig. 6) Remember to wear gloves and protective eyewear! TechniCloth Wipe Vacuum Grease Isopropanol Ngrease Fig. 6 Supplies for cleaning Fig. 7 Step 10 Fig. 8 Step 10 cont. 4
Fig. 9 Step 11 Fig. 10 Step 12 10. Apply the isopropanol to a TechniCloth wipe and clean the excess Ngrease from the outer edge where the inner radiation shield used to sit. Also wipe down any part that may have been touched earlier to remove fingerprints and debris. (Fig. 7 & 8) 11. If needed apply more isopropanol on the wipe and clean the excess vacuum grease from the outer ring where the outer shield used to sit. (Fig. 9) 12. Remove the black O-ring from the outer rim and again using isopropanol and a wipe, clean the ring and place it back in the outer rim. (Fig. 10) 13. Wipe down the inside of the inner radiation shield (the non-mylar side) and the edge of the lid using a wipe and isopropanol. (Fig. 11 & 12 next page) 14. Do the same for the outer shield, though both sides can be cleaned with the isopropanol. Be careful not to SCRATH THE WINDOW. (Fig. 13 next page) Fig. 11 Step 13 Fig. 12 Step 13 cont. Mylar 5
Fig. 13 Step 14 NOTE: Compressed air can be used to dry the shields, BUT DO NOT USE COMPRESSED AIR ON THE MYLAR SIDE! Assembly 15. After the sample has been loaded and everything has been cleaned, take the Ngrease and apply a small amount around the screw holes on the inner rim where the inner radiation shield sits to make a good thermal seal. (Fig 14 & 15) Fig. 14 Small amount of Ngrease Fig. 15 Application of Ngrease 16. Place the inner radiation shield back on with Mylar-side up. Replace the shield ring RIFAD (to prevent the screws and washers from falling into the VTPS) and remove replace the screws one-by-one. Remove the screw handle before tightening in a criss-cross pattern. (Fig. 16) 6
Fig. 16 Step 16 17. Now it is time to replace the outer shield. Remove the shield ring and using a small amount of vacuum grease, apply some around each of the screw holes and on the outer ring. This will help ensure a good vacuum seal. Also remember to apply some vacuum grease around the O-ring. (Fig. 17 & 18). Fig. 17 Vacuum grease on screw holes Fig. 18 Vacuum grease outer ring 18. Place the outer radiation shield back on and replace the all the screws one-by-one and remove the screw with handles before tightening in a criss-cross pattern. (Fig. 19 & 20). 19. You have (hopefully) successfully disassembled and reassembled the Low Temperature Probe Station. 7
Fig. 19 Placing outer radiation shield back Fig. 20 Screwing in place outer shield 8
Fig. 21 Fully assembled Low Temperature Probe Station 9
D. Lakeshore 340 Temperature Controller 1. Check that system temperature is controlled from sensor A, display reads Loop: A 2. Change sensor by pressing menu key Control Channel (use up/down arrows) 3. Press Enter to set and Cancel Screen to exit. Note: System will not heat unless the Heat display reads ON. Forced cooling/heating START: 1. Press menu key Setpoint and enter the desired temperature 2. Press Enter to set and Cancel Screen to exit 3. Press menu key Heater Range and set power to 100 W, use up/down arrows 4. Press Enter to set then Escape to exit screen 5. Display Heat should read 100 W STOP: Press the menu key Heater Off Quick warm up to release vacuum, change sample, or shut down LTPS 1. Press the menu key Setpoint to 300 K on sensor A 2. Press Enter to set then Escape to exit screen, display Setp should read 300 K 3. Press menu key Heater Range and set power to 100 W, use up/down arrows 4. Press Enter to set then Escape to exit screen, display Heat should read 100 W 5. Wait for system to reach 300 K on sensors A and B 6. Press the menu key Heater Off to stop further heating 7. Unplug the heater and relay connections (labeled H/T HTR) from the Heater Output port (rear-panel) 8. Plug in #1 heater block (labeled #1 HTR BLK) into the Heater Output ports 9. Press the menu key Control Channel to change to sensor C, use up/down arrow 10. Press the menu key Setpoint to 295 K on sensor C 11. Press menu key Heater Range and set to power to 100 W, use up/down arrows 12. Shut OFF the main power to the compressor (See section III. E) DO NOT open the system until all 4 sensors read room temperature (~294 K) NOTE: To increase warm up time Argon can be added to the chamber. Only very experienced users should do this. As the temperature increases the pressure increases and must periodically be released or damage can occur. E. BOC Edwards Pump 10
Start up: Make sure the turbo flex-line (hose) is connected between the feedthrough port on the LTPS chamber and the pump. The black knob on the LTPS chamber should be fully open, if not turn the knob counterclockwise. 1. Turn the main system power ON (power switch located on the backside) 2. From the CYCLE menu, turn the backing pump ON 3. Let the system evacuate to ~ 1x10-3 Torr 4. From the CYCLE menu, turn the turbo pump ON. The progress bar on the main menu indicates that the turbo pump is winding up. 5. System should evacuate to final pressure of ~ 1x10-6 Torr 6. Close off the feedthrough port on the LTPS by turning black knob clockwise *Special case: Noise in measurement system may be related to vibrations in flex-line connected to the pump. 1. Close off the black valve to the chamber by rotating clockwise 2. Remove the flex-line and measure 3. Optional: Reconnect flex-line and continue pumping 4. Replace plastic cap on the hose. 7. Shut down the main system power (see next section) DO NOT turn full system ON before step 3, may wear out the turbo pump Shut down: Make sure the feedthrough port on the LTPS chamber is closed-off. May disconnect the turbo flex-line (hose) connected to the feedthrough port for easier access to the manipulators and to reduce vibrations in the measurement. 1. From the CYCLE menu, turn the backing and turbo pumps OFF 2. Let the turbo pump completely wind down (watch progress bar) 3. Turn the system power OFF (power switch located on the backside) DO NOT turn main system power off before step 2, turbo pump will wear out Pressurize chamber: Connect Argon to chamber. Watch and make sure to not over pressurize chamber. This can be done by watching the probe bellows. Add argon until bellows start to sag slightly. Immediately turn off Argon and release some pressure. F. Sumitomo Compressor/ Chiller Start up: Make sure that the wall mounted switch in ET 109 is in the OFF position and the chiller in the back room has been plugged in at least 12 hours (should be powered on at all times). The green light indicates the main power to the system is ON. For chilling, flip the toggle switch located on the front of the chiller to ON. Always check chiller water level before use. 11
1. Press the wall mounted switch in ET 109 to the ON position. a. If the system is not running, check that the toggle switch on the chiller itself is in the ON position. b. The switch to chiller should remain in the ON position. The toggle switch in ET 109 is used to control the chiller. c. Check the chiller water pressure and level gauge. The water pressure should be 60 psi. 2. Check the pressure gauge on backside of the compressor (~ 1.6 MPa) 3. Turn the main system power on the sumitomo compressor ON. The VTPS should have a vacuum pressure of less than 10-4 torr. 4. Monitor the cooling lines coming from the chiller a. Incoming is cold b. Outgoing is warm 5. After a few minutes, check the sumitomo compressor gauge again (~ 2.5-2.6 MPa) 6. Monitor compressor gauge periodically throughout measurements Final system shut down order Compressor then chiller Shut down: If the pump is still running, follow the shut down procedures outlined in section III. E before proceeding. 1. Bring system up to room temperature (~294 K) 2. Turn the main system power OFF to the compressor 3. Turn the main system power OFF to the chiller (wall mounted switch) Specific Information: Never lose vacuum on LTPS unless all 4 sensors read room temperature (~294 K) Must continually pump (compressor ON) on to the LTPS above 300 K At T > 300 K, NEVER run the system MORE than 15 minutes without cooling!!!!! Probes move significantly during temperature ramping (up or down), watch the monitor closely and/or lift probes between Setpoints (T > 100 K) Materials Acetone (used to clean cables, shields, system components ) Clean wipes (used with Acetone to clean) Ngrease (thermal conductivity/contact grease) Used on the inner radiation shield (brass w/mylar covering) Vacuum grease (light convalescent grease) Used on outer shield (silver) and to seal all O-rings Maintenance: Keep the system and general area clean 12
Wipe down system with alcohol and clean wipes each time it is assembled/disassembled to keep the grease and dirt from building up want to control contaminants entering the system Make sure ground leads to each mat are always connected to protect devices Reference Sources: System manuals and related information located in: Cabinet or Y:\Low Temp Probe Station\Equip_Data_Sheets Contacts: Bill Knowlton x65705 Greg Collison x65729 Janis Research Company, INC. (978) 657-8750 2 Jewel Drive, Wilmington, MA 01887 Elizabeth Taylor (Technician) cell: (978) 618-4618 Scott Azer (Sales) 978-657-8750 x120 Zuyu Zhao (Design) Updates: 13