AML Wafer Bonder Procedure

NTS, 08/04/2016, from notes during training. Updated NTS 20170414.

[Note: There is both AML Configuration software and Control software.]

There are multiple times we record the separation numbers (platen, separation, micrometer): Pre-zero-set platen, Pre-zero-set separation, Pre-zero-set micrometer, Zero-ref platen, Zero-ref separation, Zero-ref micrometer, Set-Zero platen, Set-Zero separation, Set-Zero micrometer, Set force bonder platen, Set force bonder separation, Set force bonder micrometer. Record numbers if weird: post SZ separation, pre SFB app (when returning to Zero ref before applying force)

Prep

Raise up keyboard, 0 doesn’t work so use 1 or 9 and arrows
Open Config software
- If it doesn’t work, restart the computer
- Password is AML
Look through Config tabs to ensure proper settings are in use
Test Communication > Click this
- Need all green lights, except for grayed out items; OK
Open Control software
Select Manual
Set Process Parameters
- Must enter run ID, 4 numbers minimum, don’t matter which
- Wafers enter thickness, account for films
  - Account for graphite thickness (Which is?)? I don’t think so.
- Set values as default
- Click OK, now at main control window

For small samples, use bubble level, we want the bubble in the center ring (centered is better)
- Check level at center and directly over screws and across from screws, seven times total
- Adjust as needed as you go, and repeat as needed
For wafers, use leveling tool
- Need to do three positions, each near a leveling screw
- Make sure it is in tool properly
- Put micrometer in position 1
- Contact to platen
- Zero micrometer (push and hold red button)
- Move to position 2 and measure height
- Adjust screw til it reads 0
- Repeat at position 3
- Repeat again and again til all positions read 0

Make sure samples and graphite sheet are properly layered (stack scheme), oriented (face up or down and rotation), and aligned (over each other properly)
- Metalized sample on bottom facing up if one sample is metalized (likely carrier), otherwise carrier on bottom facing up (two samples metalized)
- Center samples on stage and on each other
- Repeat carefully with graphite sheet while watching samples, they must stay aligned
Close Lid
- Use remote, need to hold down both white button and black close button
- If you let go of one it will auto-open fully, so hold for extra 3 seconds
Engage lid bolts, be sure washers are on top
Tighten bolts til snug, not super tight

Click Start on Control Software, starts (Use 260 C, 1600 N, 11 minutes for example)
Open isolation valve, turns green
Turn on pump
- Can’t control chamber pressure of bond, constant pump and let it pump
- Pump spins up til rotor speed is at 1500
Set temperature parameters, e.g. 260 C
- Heat up stage (while tool pumps down)
- Start controlled heating
- Green means platens are heating, platens are separated right now
- Bottom platen heats faster, can increase bottom in two to five steps of 40-70 C.
Record pre Zero-set (PZS) stage values
Set Zero on tool
- We don’t now exact wafer and film thickness
- Raise black Z wheel til separation turns red; if already red, use force at ~0-14 N
Record Zero-ref (ZR) stage values
Click Zero
- Enter thickness, e.g. “.5” for two stack (Si+GaAs), “1” for three stack (Si+GaAs+graphite)
- That’s now our Zero. Will remain good while we use tool with same stack
Record Set-Zero (SZ) stage values
Separate platens while they heat (record stage values if weird, post SZ)
Set timer, e.g. 11 minutes

Think about target force, if not yet sure of what force you want to use
Wait til platens are within 5 C of target temperature and pump is at 1500 Hz
Raise sample (turn black wheel) til separation turns red (record stage values if weird, pre SFB)
Raise sample til at ~target platen force, e.g. 1600 N
Start Timer
Record Set force bonder (SFB) stage values
Record the approximate temperature, range the force varies over, and time
Stay at tool to monitor platen force and keep it at target value (suggested)
- Vacuum is being pulled constantly and will change force (not really if in the -5s)
Our example: 220 C, 1200 N, 11 minutes
- Record the approximate temperature range, force range, time, and the under-stage gauge and computer micrometer distance before platens are in contact and again when at target force

When timer is done, lower platen to separate them
Press Stop button
Turn pump off
Click start slow cooling
Lower platen temps to 49 C between samples, or to minimum, 3 C when done
- Can open tool when platens are under 200 C, but can wait too
Wait for rotor speed to go to 0 Hz
Close isolation valve
Open N2 valve, will hear it start
Wait for temp under 200 C
Click Stop Process, popup Click OK
Can repeat run, or finish, or if you undo a lid bolt, it auto shutdowns, popup Click OK
Undo a lid bolt to turn off N2, popup Click OK
Click Finish, popup Click OK
Swap samples and repeat as needed, or unload final sample and quit program

Test generator before use (Platens heating and separate)
Go up in steps of 100 V
Enter 100 V and 1.5-2 mA for small samples, 5 mA for wafer
Click Enable
Graphing starts
- White line is voltage; red line is current
- Short circuit means error, sample may have broken
When in contact, currents starts at what you set
During bonding it will decrease, e.g. 2.5  2 mA

System has optics (for glass bonding)
XYZ knobs and second Z knob
Has wafer clamp for 4” wafers, skipped over
Tool does multiple bonding types
- Thermal: metal/metal
- Adhesion: film (PR?)/metal?
- Enotic: Pristine samples bonded with electricity
Johnny says gold is 100-200 N, sounds low, Nish uses closer to 3000 N