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

General Process Information

Processing on Developer TMAH UV-lithography consists of the following steps:

• Post-exposure bake
• Puddle development
• Rinse

Features of Developer TMAH UV-lithography:

• Cassette-to-cassette wafer handling
• In-line hotplates
• In-line cool plate
• Puddle developer module with rinse and dry

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, is carried out on one of the two hotplates. After baking, the wafer is cooled for 20 seconds on the 20°C cool plate.

Puddle Development

Development on Developer TMAH UV-lithography is divided into the following steps:

• Pre-wet
• Puddle dispense
• Development
• Spin-off

Pre-wet may be done using developer or DI water, or it may be skipped. It consists of a short dispense at medium spin speed (2s @ 1200 rpm).

Puddle dispense is done by dispensing developer (AZ 726 MIF) to the center of the wafer in order to build up a puddle of developer on the wafer. During the dispense, the wafer may be stopped or rotating slowly (30 rpm). The developer is dispenced at a rate of approximately 225 ml/min. A dispense time of 3s, and 7s is used for 4", and 6" wafers, respectively, corresponding to a volume of 11 ml, and 26 ml, respectively.

Development is carried out by leaving the developer puddle on the wafer for the duration of the development time (puddle time). The rotation is stopped during the development, but the developer may be agitated by rotating the wafer a few turns at low speed, e.g. 2s @ 30 rpm halfway through the development time, in order to facilitate good uniformity.

Spin-off is designed to stop the development by removing the developer from the wafer before the rinse. It is usually carried out as a short spin at high speed (3s @ 4000 rpm), but may be omitted.

Processes are divided into single puddle (SP), double puddle (DP), and multiple puddle (MP).

Rinse

After development, the substrate is rinsed using DI water, and dried using nitrogen.

The standard rinse and dry procedure is 30s at 4000 rpm with DIW being administered from the top at the center of the substrate, followed by a 10-15s dry at 3000 rpm using nitrogen from the top at the center of the substrate. The top side rinse is at a rate of approximately 500 ml/min, corresponding to 250 ml DIW during the rinse. The flow rate of the nitrogen is 50 l/min, and the drying time is set according to the size of the substrate.

Process recommendations

Recommended parameters for development of different resists. Information about exposure dose can be found here: Information on UV exposure dose

• 2µm AZ nLOF 2020

PEB: 60s @ 110°C

Development: SP 30s. For lift-off, use SP 60s (sidewall angle ~15°)

• 1.5µm AZ MiR 701

PEB: 60s @ 110°C

Development: SP 60s

• 1.5µm AZ 5214E (positive process)

No PEB

Development: SP 60s

• 2.2µm AZ 5214E (image reversal)

Reversal bake: 120s @ 110°C

Flood exposure: ~200 mJ/cm²

Development: SP 60s

• 6.2µm AZ 4562

No PEB

Development: MP 3x60s

• 10µm AZ 4562

No PEB

Development: MP 4x60s or MP 5x60s

Standard Processes

Development

Development on Developer TMAH UV-lithography is divided into the following steps: Pre-wet, puddle dispense, development, spin-off, and finally rinse and dry.

Sequence names and process parameters (Sequence no. 1000-1999):

Single puddle:

• DCH 100mm SP 30s
• DCH 100mm SP 60s
• DCH 100mm SP 90s
• DCH 100mm SP 120s
• DCH 150mm SP 60s

Multiple puddle:

• DCH 100mm MP 3x60s
• DCH 100mm MP 4x60s
• DCH 100mm MP 5x60s

Each of these sequences start with a 2s pre-wet at 1200 rpm using developer. The puddle dispense is done at a rotation of 30rpm. The dispense time is 3s, and 7s, corresponding to a volume of 11 ml, and 26 ml, for 100mm, and 150mm, respectively. The development (puddle time) is split in two by an agitation step of 2s at 30rpm (one rotation). Spin-off is 3s at 4000rpm. Finally, the wafer is rinsed as described above. The multiple puddle sequences repeat the dispense, development, and spin off steps a number of times before the rinse.

• DCH 100mm SP 60s no spinoff

As DCH 100mm SP 60s except the spin-off step is omitted. The development is thus terminated by the rinse (30s @ 4000rpm). This may help in case of scumming problems.

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.

Sequence names and process parameters (Sequence no. 2000-2999):

• DCH PEB 110C 60s
• DCH PEB 110C 120s

Process parameters: Bake at 110°C. 20s cool at 20°C.

Combined PEB and development

For convenience, the PEB and development function of the machine may be combined in one sequence.

Sequence names and process parameters (Sequence no. 3000-3999):

• DCH 100mm PEB60s@110C+SP60s

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

• DCH 100mm PEB60s@110C+SP30s

A combination of the 'DCH PEB 110C 60s' post-exposure bake and the 'DCH 100mm SP 30s' development.

• DCH 150mm PEB60s@110C+SP60s

A combination of the 'DCH PEB 110C 60s' post-exposure bake and the 'DCH 150mm SP 60s' development.