Heidelberg Mask Writer
DWL66 Laser Pattern Generator and Direct Writer
Backup: John Treichler
The DWL 66 is a high-resolution imaging system capable of achieving over 500,000 dpi using a 40-nanometer writeable address grid. A 442 nm He-Cd laser is used to perform the imaging and is capable of producing a minimum feature size of 500 nm. A variety of substrates are compatible with the DWL 66 including silicon, glass, III-V semiconductors, and photomasks. Substrates up to 170 mm x 185mm in size can be loaded into the system with minimal hardware changes.
The writing is performed using a combination of raster and scanning techniques. Substrates are mechanically moved beneath the writing lens in one axis while the beam is scanned in the transverse direction. The resolution of the tool and the width of the scan are determined by the final lens. CNF has 10 mm working distance lens that produces a 2.4 um diameter spot.
Due to the writing strategy, exposures are independent of the complexity of the patterned features. Shapes that have been traditionally difficult to pattern at the CNF-circles, curves, spirals and arcs-can be written efficiently and accurately using the DWL 66. This capability should be of great benefit to research in microfluidics and integrated optical devices. An example result is shown in the following figures.
The DWL 66 also provides a comprehensive set of metrology functions including line width, overlay, stitching and pattern placement measurements. Front to backside alignment is also possible for direct write applications using a video backside alignment system.
When should I use the DWL 66 or the GCA PG 3600F?
The answer is it depends on what you are doing. In general, this will be a function of which tool has the faster write time. The PG 3600F writes at a rate of 3000 flashes/hour, where 1 flash is 1 primitive shape. Consequently, the amount of exposed area in your pattern will determine the length of write time. The number of flashes is given to you following conversion of GDSII data to PG format.
Write time on the DWL 66 is governed by the extent of the patterned data, not the actual exposed area. A filled 500 µm square box and four 10 µm square boxes placed in a 2x2 array separated by 500 µm will take the exact same amount of write time. To get a rough estimate of the write time, use the following information:
10 mm working distance lens: writes a 1 in² area in ~22 minutes.
Three general guidelines:
If you convert a contact mask for the PG and it has more than 30,000 flashes you should consider using the DWL 66.
If you convert a stepper mask for the PG and it has more than 15,000 flashes you should consider using the DWL 66.
If you have a lot of sparse features and not much exposed area you should probably use the PG.
- Write lens 10mm - 2.4um nominal spot sizes
- Stage 8
- Laser Source He-Cd laser: 442 nm
- Active write area: 170mm x 185mm
- Input Format GDS-II only
- Metrology and alignment system for multi-layer exposures and metrology measurements, including front to backside alignment for direct write applications. The backside alignment uses a third camera for image recognition and registration on the substrate backside.
- Grey-scale Exposure Mode: This mode enables the system to perform grey-scale exposures into photoresist. The intensity of the laser beam can be varied per pixel to achieve different exposure depth. Number of grey scale levels: 32
DWL 66 GSTB files (for 10 mm grayscale mode)
DWL66 Grayscale Test CAD
Curved grating created on the Heidelberg DWL.
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