PDMS/glass, Si wafer, or pnc-Si bonding

Hi All, Recently we have good results showing that we can bond PDMS to both glass and Si-wafer with UV Ozone treatment. We can even bond the PDMS to pnc-Si directly, although it is not clear whether the sealing is perfect. However, the success rate is not always 100% (either no bonding or partial bonding is observed for some sample, be it glass or pnc-Si).

In the past few days Mike and i tried variation of the procedure posted by Dave, and it seems the original protocol is still perhaps the best.

Method 1 (original): 5 min Primary Ozone treatment at 25 C/room tempt, 10 min Secondary Ozone Treatment with O2 gas supply off, 10 min of vacuum (Secondary Ozone treatment still on).

Method 2: 5 min Primary Ozone treatment at 80 C, 0 min Secondary Ozone Treatment with O2 gas supply off, 10 min of vacuum (Secondary Ozone treatment off).

Method 3: 5 min Primary Ozone treatment at 80 C, 0 min Secondary Ozone Treatment with O2 gas supply off, 10 min of vacuum (Secondary Ozone treatment off).

Method 4: 5 min Primary Ozone treatment at 25 C/room tempt, 3 min Secondary Ozone Treatment with O2 gas supply on, then 7 min with O2 gas supply off, 10 min of vacuum (Secondary Ozone treatment still on).

After the treatment, the samples are left overnight for bonding.

The results are as followed: (Name) denotes the operator.

Method 1 (Mike and Henry): Out of the 3 times we tried, 2 of them yielded 100% bonding. (the 1 time that failed, 3 out of the 4 fully bonded to glass, the remaining one partially bonded; 2 out of the 4 bonded to Si-wafer)

Method 2 (Mike): Out of the 1 time that we tried, not all bonded: none bind to glass, some bound to Si-wafe (forgot the statistics). Interestingly, just today i checked it again all 4 bonded to glass, but only 2 out of the 4 bonded to the Si-wafer.

Method 3 (Mike): Out of the 1 time that we tried: 2 out of the 4 bounded to glass, all 4 bonded to Si-wafer

Method 4 (Henry): Out of the 1 time that we tried, 100 % bonding (glass: n = 8, Si-wafer: n = 5).

Our latest trials (Method 1 and Method 4 on Jul/03/2008) yielded 100 % bonding… we still don’t know what are the key parameters that influence the success rate.

PS: we will check the humidity from now and so on since humidity measurer is now in place. The two latest trails are conducted under a humidity of 52%.

PS: Fruit for thought: the literature posted by Dave mentioned that the PDMS and glass is reactive within 10 min after ozone treatment, i think technically we are always at the 10 min mark, since the step with vacuum is 10 min. The questionable part is that we have a secondary ozone treatment of 10 min for Method 1 and 4, but they fared pretty well so far.