On wafer calibration for pressure sensors

The continuing demand for higher performance products with light weight and small dimensions is requiring levels of package performance of microelectronic devices unattainable by the molded plastic and ceramic packages of the past decade. These factors have driven a variety of major innovations in packaging technology (e.g. Organic Land Grid Array - OLGA; Flip Chip Pn Grid Array - FCPGA; µ-PGA; Chip Scale Packaging - CSP). Such packages have been introduced to combine flip chip interconnect with a very small form factor (physical outline) and socketability for compact and portable systems. Portability is expected to continue as a strong driver of new packaging approaches and the saved area on a PWB make new product features possible that will be used for sales promotion. For example altimeters and barometers appear already today in clocks and pocket knifes. So there is a need for fully linearized pressure sensor systems with little temperature shift and small form factor, i.e. calibrated pressure sensors ideally as CSP. Since the handling of chip scale packaged pressure sensors is quite complicated new calibration strategies have to be developed. FhG-IMS Duisburg has set up a method for on-wafer calibration of integrated pressure sensors, which is presented in the following.