Specific Process Knowledge/Lithography/Development/Developer TMAH UV-lithography processing

General Process Information

Processing using Spin Track 1 + 2 is divided into three parts:

• HMDS priming
• Spin coating
• Soft baking

As part of the processing of negative tone resists and chemically amplified positive tone resists, Spin Track 2 may also be used for:

• Post-exposure baking (at 110°C)

Features of Spin Track 1 + 2:

• Cassette-to-cassette wafer handling
• In-line HMDS priming
• Temperature controlled resist lines

The resist lines are temperature controlled using 25°C water from a chiller. The priming module coolplate is cooled by the same chiller. If the process flow has been properly designed, the wafer and resist should have the same temperature during spin coating, ensuring good coating reproducibility.

Puddle Development

The process of development

Post-exposure baking

Chemically amplified resists and cross-linking negative resists must be baked after exposure in order to finish the process initiated by the exposure light. Post-exposure bake, or PEB, can be carried out as a contact bake or a proximity bake. In a contact bake, the wafer is held in close contact to the hotplate surface by vacuum during the bake. In a proximity bake, the wafer is first moved into close proximity, e.g. 1mm, of the hotplate surface, then held there for the duration of the bake. Since the hotplate temperatures of Spin Track 1 + 2 are fixed, PEB is only possible at 90°C or 110°C. In practice, only 110°C (Spin Track 2) is used. After baking, the wafer is cooled for 5 seconds on the coolplate.

Standard Processes

Puddle development

Spin coating of AZ MiR 701 (29cps) on Spin Track 1 is divided into two or three steps: HMDS priming (optional), spin coating, and soft baking. At the moment, the HMDS priming is equal to the standard priming, but this may be subject to change as our process knowledge grows. Spin coating uses dynamic dispence of 4 ml resist at 800 rpm, followed by spin-off at a thickness dependent spin speed for a thickness dependent time. The wafer is deaccelerated at 1000 rpm/s for 5 seconds before stopping. Soft baking is done at 90°C for 60s. As MiR 701 has a tendency to produce "cotton candy" on the edges, soft baking is performed in 1 mm proximity.

Flow names, process parameters, and test results:

• T1 MiR 701 1um no HMDS
• T1 MiR 701 1um with HMDS

Spin-off: 60 s at 9990 rpm.

Substrate	Thickness	Uniformity (+/-)	Test date	Tester initials	Comments
Silicon with native oxide	1.053	0.33%	5/9 2013	taran	with HMDS. Average of 3 wafers

Post-exposure baking (PEB)

Chemically amplified resists and cross-linking negative resists must be baked after exposure in order to finish the process initiated by the exposure light.

Flow names and process parameters:

• DCH PEB 110C 60s

Process parameters: 60s bake at 110°C.

Combined PEB and development

...

Flow names and process parameters:

• DCH 100mm PEB60s@110C+SP60s

A combination of the 'DCH PEB 110C 60s' post-exposure bake and the 'DCH 100mm SP 60s' development.