Specific Process Knowledge/Lithography/Coaters: Difference between revisions
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'''HMDS priming:''' | '''HMDS priming:''' | ||
Contact bake | The process of HMDS priming on Spin Track 1 + 2 consists of five steps: | ||
*Contact bake | |||
*Vacuum bake | |||
*Priming | |||
*Pump-purge | |||
*Cooling | |||
The wafer is first baked in contact with the hotplate in order to heat the wafer to the hotplate temperature. The hotplates of the priming modules are set to 50°C. Then the wafer is baked under a low vacuum (~0.5 bar) in order to dehydrate the wafer before HMDS application. The HMDS is applied to the wafer using nitrogen as a carrier gas. 15 liters per minute of dry nitrogen is bubbled through liquid HMDS before flowing across the wafer surface. After the priming, the chamber is pump-purged twice, using a 7s pump to ~0.5 bar and a 10s nitrogen purge at 40 liters per minute. Finally, the wafer is cooled on the priming module coolplate. | |||
The contact angle after HMDS priming is a function of the priming temperature, the priming time, and the surface condition of the wafer. Tests have shown the contact angle to decrease with increasing hotplate temperature, while it increases as a function of priming time at constant temperature. At a priming temperature of 50°C, the contact angle resulting from priming an oxidized silicon wafer for t = 30 - 300s may be approximated by | |||
<math>\theta = 95 - 119.2 * t^{-0.51}</math> | |||
The condition of the substrate surface is again a function of the substrate type, the substrate history, and the vacuum baking temperature and time. Since the vapor pressure of water at 50°C (0.123 bar) is lower than the vacuum bake pressure of 0.5 bar, the degree of dehydration will be a function of the vacuum baking time. Thus, for thick oxides, the standard of 30s vacuum bake may not be enough to dehydrate the surface sufficiently. | |||
'''Spin coating:''' | '''Spin coating:''' | ||
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''Flow names, process parameters, and test results:'' | ''Flow names, process parameters, and test results:'' | ||
*T1 T2 HMDS Standard | *T1 T2 HMDS Standard | ||
Process: 10s contact bake, 30s vacuum bake, 72s HMDS priming. | Process: 10s contact bake, 30s vacuum bake, 72s HMDS priming, 5s cooling. | ||
Tested | Tested 7/5 2013 on 110nm oxide: 81.4°. Tested 12/6 2013 on 3µm oxide: 81.8°. Tested 20/6 on 15µm oxide: 68-70°. | ||
====AZ MiR 701 (29cps) coating==== | ====AZ MiR 701 (29cps) coating==== | ||