CHA 1
CHA#1 Procedure
Written by NTS, Jan 2013 from notes in my notebook. Last modified by AFB 20160930
Standard Operating Procedures (MERTech) for CHA 1
Loading
Have clean samples or clean while venting
Note: If someone is before you, ask them to leave it vented for your load. Be ready to load when they are done.
Check Xtal life before loading sources and samples
Check Power is off
IG’s off
Power sources off
Vent, takes about 12 minutes
Go to acid hood, prepare and use surface cleaning solution
HCL:DI (1:10, 40:120 mL)
Note: Never approach acid bench w/out gear on. Can drop in wipes.
Suit up with inspected apron, mask, and proper sized gloves
Setup wipes now and put sample in basket
Pour DI into rinse beaker (400 ml)
Pour 120 ml DI into 400 ml etch beaker (want a ~1:10 ratio)
Pour 40 ml HCl into 100ml beaker (HCl is already 1:3 in bottles)
Pour acid into DI and quadruple rinse 100 ml beaker
Dip samples for 15 sec in solution (precision is not needed here)
Cascade rinse for 30 sec in DI
Blow dry with N2
Clean beakers and workspace
Our acid solution is dilute so you don’t need aspirator
This part takes about fifteen minutes, so start it once you vent CHA #1
Note: This takes 20-45 minutes depending on number of samples
Carefully take off acid gloves, mask, and apron
Take samples immediately to CHA #1
Mount clean samples on holders. There is a clip set for the Bank group.
Prep chamber
Inspect bottom of shutter and hearth
Look for scraps on hearth or flaking on shutter bottom
To clean shutter, double glove, wipe with hand, and vacuum hearth; reglove
Clean (vacuum) chamber and rim where bell jar seals if needed
Load samples
Open shutter and load sources
Make sure you can see source both ways
Using all Si wafer mirrors
Using just back mirror
Close shutter when done
Check rotation with samples loaded before you pump down
Pump down, takes about 30 minutes
Don’t leave machine til pump crossover
Turn on IG (IG2) after crossover, when P < 1e-3/4 T
Check LN2 level using straw
Add LN2 if needed
Acquired in back chase
Evaporation Prep
Dep controller
Should be on the main screen
Press menu, go to general parameter, press menu again
Set process number by material (chart on breaker box)
Move cursor, press menu, go to operate, and press menu
Check that process loaded
Zero the thickness
Note: If the controller seems stuck, or can’t get to process number slot, press reset
Wait until chamber gets to < 5e-6 or < 6e-6
Choose first crucible
Make sure you have enough time on LabAccess before activating power for large stacks
If your stack needs more than 2 or 3 hours, consider LabAccess time before each run.
Turn on main breaker
Turn on Gun control
Turn on HV control
Hold up until breaker clicks twice, about a full second
Turn on rotation
If it makes a clicking sound in the chamber, it is not working right so turn it off
Evaporation
Press start. Tool auto ramps to 25%, Soak 1.
At Soak 1, you can take it to manual power. Press manual power (5)
Note: When you can see the ebeam, make sure it is not hitting the hearth or crucible, ever!
Ramp up to desired power at < 0.1% per sec
Note: Controller is finicky
Desired power level is determined by you
From other users, papers, past runs, etc.
When within a few percent open the shutter so you can guide the ebeam
Use beam sweep control 1
Ampl knobs: CW increases
Freq knobs: CCW increases
Metals other than gold need some motion
It’ll start depositing, so control dep rate.
At first, keep the dep rate under 0.5 A/s
Don’t ever exceed 1 A/s, metals can sputter, especially Ge
When done, or nearly so, always lower dep rate to 0.5 A/s or lower, I suggest ~0.1 A/s
0.5 A/s can still cause as 4x spike in dep rate for a second
Ricardo suggests ramping down power/dep rate rate towards the end of your run, to avoid splashing material on shutter (and to get nice, slow layer)
Close shutter when done
We must now use an automated ramp down Idle Ramp that takes 5 minutes except for Al and Cr
Press Manual Power to start Idle Ramp down, will go down to 0%
Old way: Ramp down at < 0.1% per second. When you get to < 20%, can go much faster
When done, displays Idle and End of Process on controller at 0%
This will be checked, it can’t be left in manual
(Push in stop when power is at 0.0%. Not ever otherwise!)?
Controller must be left in Idle and End of Process or Ready state for next user, not manual
Turn off GC and HV
Switch Source
Switch pocket (source)
Chamber ready when interlock at hearth control goes on
Press reset on dep controller
See “Evaporation Prep” and “Evaporation”
Finishing
When done with GC and HV off
Press reset and zero on the dep controller
Turn off rotation
Turn off power
Turn off circuit breaker
Turn off IGs
Press Standby, wait for gate valve, press Vent, takes about 12 minutes
Remove samples and source
Can log off labaccess for pump down if no one is after you
If there is someone after you, you may not have to pump down chamber after use.
To pump down after use
Push switch to lower and wait for bell to lower and chamber to pump to mT range.
The pump might start to cross over. That’s when you set the system to standby.
Change switch to standby
Fill out log
Beam Sweep Notes
Ampl knobs: CW increases
Freq knobs: CCW increases
Beam sweeping skill takes some practice.
The beam when it is centered will be a little circle. If it is too high it will be ovalish. If it is too low it will look like a v thing (upside or sideways maybe).
It is good to raster a little bit of gold in center of source, but not too small a spot.
Other metals need rastering over most of surface
Stacks
Laser Top: Ti/Pt/Au : 100/100-300/2000 || Ti/Au : 100/1000
Laser Bottom: Au/Sn/Ni/Au : 100/100/100/1000