Ashing of Microchem SU-8 type Resists
TePla is an experienced manufacturer of Microwave Plasma Process Batch Tools for Photoresist Stripping, Descum and Isotropic Etch for the Semiconductor Industry. They have developed process solutions for many difficult implanted and thick resists including Microchem’s SU-8 series.
MICROCHEM’s SU-8 was developed by IBM as a special resist with excellent properties for high profile geometries, deep etches and aggressive chemistries. In general, it is an epoxy like material, which allows very thick resists (Up to 500 microns or more.) to be coated and developed on various wafer surfaces. It has a variety of specific properties (See www.microchem.com) which make it ideal for a variety of MEMS, MOEM’s BioMEMS and other related devices.
The difficulties encountered with SU-8 have been to be able to remove this resist material with standard dry ashing or wet stripping processes. It is often ideal to use dry ashing where possible to achieve higher quality devices, to eliminate stiction effects and avoid wet chemistries. Tepla has developed a process, which successfully removes the SU-8 material using its unique Microwave Technology. This processing typically removes the SU-8 with rates from .5 to 5 microns per minute depending on the resist parameters including thickness, coverage, temperature limits and batch load. An example of processing results is processing of a 4” wafer with 50 microns of SU-8 2000 resist with 100% coverage which was ashed in about 20 minutes.
It must be stated that these processes are not fully characterized and therefore should be carefully evaluated for particular applications. The chemistry used with the Microwave Plasma includes O2 and CF4 gases, which may not be compatible with some substrate materials. Temperatures typically range from maximums of 200C to 300C. Significantly lower temperatures and reduced amounts of CF4 chemistry are achievable with tradeoffs of slower etch rates.
Our Model 200 and 300 series offer very low cost systems with simple manual loading, recipe control, easy operation and maintenance free use. These TePla Microwave Plasma tools offer uniquely high value in that they are Fast Processing, Damage free, Low Temperature, Accommodates all substrate sizes, is highly reliable (German built) and Very Low in cost. These factors make it an ideal tool for MEMS, MOEMS, BioMEMS, and other small manufacturing applications.
Contact Steve Wilson at firstname.lastname@example.org or view www.tepla.com for further information.