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Trial Number 0

Trial Purpose:

To evaluate plasma cleaning for parts cleaning

Date Run:

03/21/2002

Experiment Procedure:

Chamber with a plate in it to put coupons on. The plate can be heated or left at ambient. We will run experiments at ambient. This technology is generally used to clean computer wafers and is done at approximately 250 C
The process is done in a vacuum with plasma that can consist of gases such as O2, NF3, CF4, N2H2 and Argon. We will use mainly O2 gas plasma. The plasma is pumped into the chamber and when it reacts with the organic contaminants a blue glow can be seen. When all the organics are oxidized the glow is purple (pure O2 plasma). Want to use or test organic contaminants that contain H, C, O etc. Things such as lipids and metals are hard to remove with this process. Their chemical structure would deter or inhibit cleaning.

Contaminants:
Company Product Composition
Solutia Inc. Gelva Multipolymer Resin Solution 2895 Resin solid: 50862-46-9
Ethyl Acetate: 141-78-6
Heptane: 142-82-5
Isopropyl Alcohol: 67-63-0
Ethanol: 64-17-5
Vinyl Acetate: 108-05-4
Bencyn, Inc. B-5186, Metal Working Compound Hydrotreated Heavy Napthenic Distillate: 64742-52-5
Polyisobutene: 9003-29-6
Aliphatic Alkyl Phosphate: 3946469-2
Acrylic Copolymer: 63197-48-8
The Valvoline Co. Tectyl 505, Petroleum Based Rust Preventative Aliphatic Hydrocarbon: 8052-41-3

Trial Results:

Trial 1. O2 plasma, Valvoline contaminant, steel coupons ( #’s 12, 13, 14)
Flow rate of O2 plasma was 300 cc/min
Temp on plate reading 18 C
Vp in chamber from contaminant was 0.04 T (0.03T when all valves open and 0.07 T when shut. Difference in Vp can be contributed to contaminant)
Pressure .19T
Power 300 Watts
Time 5 minutes
Stopped flow after 5 minutes. Opened valves and flushed out chamber (no vacuum). Temp on plate reading 21 C ( 2 degree increased in plate temp due to reaction and plasma flow)

2. Same coupons, same conditions for 5 more minutes.
Only difference end temperature after this 5 minutes was 25 C @ atmospheric pressure

3. O2 & N2H2 plasma, Valvoline contaminant, steel coupons (#’s 16, 17, 18)
Flow rate 500 cc/min O2, 70 cc/min N2H2
Pressure .26T
Power 500 Watts
Time 5 minutes
When stopped flow temperature at 30 C. Open valve and purge chamber and temp reads 33 C @ atmospheric pressure

4. O2 plasma, Solutia, Inc, Gelva Mulipolymer Resin 2815, stainless steel coupons (#’s 6,7,8)
Flow rate of O2 plasma was 300 cc/min
Pressure .19T
Power 300 Watts
Time 5 minutes
Stopped flow after 5 minutes. Opened valves and flushed out chamber (no vacuum). Temp on plate reading 27 C @ atmospheric pressure
This contaminant also visibly changed. Looks bubbly?

5. Same coupons as in 4 for another 5 minutes

6. O2 plasma, Bencyn, Inc B-5186, Stainless steel coupons (#’s 21, 22, 23)
Flow rate of O2 plasma was 300 cc/min
Pressure .19T
Power 300 Watts
Time 5 minutes
Stopped flow after 5 minutes. Opened valves and flushed out chamber (no vacuum). Temp on plate reading 31 C @ atmospheric pressure
This contaminant also visibly changed to a yellow color from a brown color

7. O2 plasma, one coupon of each contaminant, Stainless steel (#’s 15, 16, 27 )
Temperature 50 C
Power 500 Watts
Flow rate O2 plasma 500 cc/min
Pressure .19T
(Increase Temp, Pressure and Power)

8. O2, CF4 plasma, one coupon of each contaminant, (#’s 17, 11, 24)
Temperature 50 C
Power 500 Watts
Flow rate O2 plasma 500 cc/min, CF4 50 cc/min
Pressure .19T
(Increase Temp, Pressure, Power and change composition of plasma)

Table 1.  Cleaning Efficiencies              
Trial # 1 2 3 4 5 6 7
Plasma Type O2 O2 O2 & N2H2 O2 O2 O2 O2
Cleaner Valvoline 5 Valvoline 10 Valvoline 5 Gelva 5 Gelva 10 Bencyn 5 Bencyn 10
Coupon 1 42.16 27.56 59.86 18.45 4.16 7.50 1.69
Coupon 2 35.11 19.70 52.55 18.26 3.40 4.43 2.60
Coupon 3 30.86 15.91 56.03 16.72 3.38 2.97 1.84
Ave 36.04 21.06 56.15 17.81 3.65 4.96 2.04
Std Dev 5.71 5.94 3.65 0.95 0.45 2.31 0.49
               
Total 57.10     21.46   7.01  

Trial 8

  Valvoline Gelva Bencyn
Increase Flow & temp 38.97 22.28 9.33
Increase Flow & temp w CH4 27.72 21.89 8.09

Success Rating:

A follow up test, usually based on company input.

Conclusion:

Questions to answer:
Not very good cleaning efficiencies. Are we just baking the contaminant or removing? Evaluate back at lab. Fluorine may increase cleaning efficiencies. DO NOT WANT TO USE due to money and chemical issues.
Water addition to decrease ashing and lift more contaminant off? Decrease pressure not increase?

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