Post-CMOS processing

The starting material for the sensor fabrication are fully processed wafers of a 2-poly 2-metal 0.8 pm industrial CMOS process provided by austriamfcrosystems (Unterprem-statten, Austria). In the following, the main post-CMOS processing steps (schematically summarized in Fig. 4.2) are discussed. 

The first device was a circular-shape microhotplate, which essentially consisted of CMOS-process materials (Sect. 4.1). The fabrication of this microhotplate required a minimum of post-CMOS processing steps. The electrochemical etching process used for the membrane release and the formation of the circular-shape Si island was optimized and can now be routinely apphed on wafer-level. 

In another report, a DNA sensor array of 16 x 8 sensor elements with pitch size of 250 pm has been fabricated using a 0.5—pm CMOS process [50, 51, 55]. The DNA h34>ridization is measured through the change of interfacial capacitance and then converted to a digital output signal by the integrated electronics. The chip was post-processed with a gold layer to facilitate the attachment of probe DNA... 

The primary benefit of using CMOS-type photodetectors is the ability to include them on-chip with post-detection processing circuitry to create compact, lower power systems. The current from the photodetector can be converted to a voltage, amplified, stored, combined with other signals, or converted to a digital signal. All of these can occur on the same chip as the detector. 

As a change to another CMO will take about three years (as post-approval change), it is important to select a CMO which will not only supply the material for clinical Phase III but is willing to dehver product for the initial three years of marketing requirements. Typically, that will require scale-up of the process to larger bio-reactor(s) and purification unit operations. 

The dielectric membrane of the micro-hotplates will be composed of CMOS dielectric films. It can be formed through a silicon micromachining post-process either on the back or the front. 

Multi-Project Wafer (MPW) for Prototyping on DALSA Semiconductor High Voltage CMOS/DMOS Technologies with MEMS Post-Processing option [23]... 

---