MTL Fabrication

HMDS - Standard Operating Procedure

Model Number: --
Location: ICL
What it does: Si/nitride dry etcher

The ICL machine HMDS is a batch oven system for vapor phase application of HMDS to silicon wafers. It has a capacity of fifty 4" or twenty-five 6" wafers.

Hexamethyldisilazane (HMDS) is widely used in the semiconductor industry to improve photoresist adhesion to silicon and to oxides. HMDS reacts with the oxide surface in a process known as silylation, forming a strong bond to the surface. The methyls, meanwhile, will bond with the photoresist, enhancing the photoresist adhesion.

The process works not only on silicon dioxide, but other oxides e.g. Al203) as well. We have found it has beneficial effect on silicon nitride also.


The oven is set for operation at 150 oC. Use caution when handling hot cassettes; do not touch the cassettes with gloved hands. Always use the boat handles.

The YES HMDS system combines vapor priming and vacuum dehydration baking. Do not attempt to defeat the vacuum seal on the door once the cycle has commenced. You must wait until the cycle has completed, the HMDS vapor has been evacuated from the oven, and the oven has backfilled to atmosphere before the safety interlock will allow you to open the door.

HMDS is a suspected carcinogen. Do not attempt to refill the flask. Contact the staff if the level falls below the fill line. If the flask is broken leave the area immediately and contact a staff member.


NOTE: It is MANDATORY to RESERVE the system prior to use. It is mandatory to OPERATE MACHINE prior to starting your process in CAFE.

  1. Check Equipment Reservations in CAFE to insure that you reserved the correct machine in the correct facility for the correct date.

  2. Operate machine for the equipment that you are Using. Insure that the correct facility is set (ICL or TRL) and that your lot name is entered correctly.

  3. Transfer your wafers into the dedicated (brown) cassette.

  4. Place the cassette into the chamber and latch the door.

  5. Press the START button. The system will now begin the automatic pump/purge/prime sequence. The entire process takes about 25 min.

  6. When the cycle is complete, the COMPLETE light will flash and the system will audibly alarm. Press the RESET button to silence the alarm.

  7. Open the door, use boat handle to remove the cassette, and close door.

  8. End Operate Machine in CAFE.

Process Program


To enter the programming mode, press reset button next to the key. Turn the key. Press the red RST keypad on the Micromaster controller. Press the yellow PGM keypad to engage programming mode. Use the STEP key to advance through the program. Use the FUNC, DATA and O1-O4 (output) keys to enter the program.

The following is the current program (11/28/01):

01 IF A >   O3 O0 = complete light
02 GOTO 01   O1 = N2 valve
03 IF E> 06   O2 = Vacuum valve
04 IF C> 47   O3 = HMDS
05 GOTO 07    
06 IF C> 52   A = start switch
        B = vacuum gauge P > 500T
07 L= 0003   C = program 2 or 3
08 M 01:20 02 D = vacuum gauge P > 10 T
09 IF B> 27   E = program 1 or 3
10 M 02:30 01 L = loop
11 IF B> 13   M = time in minutes
12 GOTO 30   S = time in seconds
13 L> 08    
14 M 03:00 02 * In order to call up
15 IF D> 33   "if A>" or "if B>"
16 F E> 45   or "if C>" go to the
17 L= 0300   "IF D>" function and
18 S 01.00 03 then use the adjacent
19 IF D> 36 03 data down key to find
20 L> 18 03 the function you need.
21 M 1:00 02  
22 M 1:00 01  
23 M 1:00 02  
24 M 3:00 01  
25 M 10:00 O0  
26 GOTO   O0  
27 S 00.10 01  
28 S 00.10 O0 O1  
29 GOTO 27 O1  
30 S 00.10 01  
31 S 00.10 O0 O1  
32 GOTO 30 O1  
33 S 00.10 O1  
34 S 00.10 O0 O1  
35 GOTO 33 O1  
36 L= 0006    
37 M 01:00 O2  
38 S 01.00 O1  
39 IF D> 4 O1  
40 GOTO 38 O1  
41 L> 37    
42 S 00.10 01  
43 S 00.10 O0 O1  
44 GOTO 42 O1  
45 L= 0060    
46 GOTO 18    
47 M 00:30 O2  
48 M 00:30 O1  
49 M 01:30 O2  
50 M 00:30 O2 O3  
51 GOTO 22    

Press Reset and turn key back. You are now ready to operate.

Author: Paul Tierney, 11/01 <>