Application of CMOS-Compatible Micro-Hotplates for In-situ Process Monitors

A CMOS-compatible micromechanical structure that can be used as an in-situ sensor for monitoring and controlling the deposition of films is reported. This micro-hotplate structure is fabricated by the micromachining of commercial CMOS-technology wafers or chips and the deposition of additional films. This device is comprised of a polysilicon resistor for heating, an aluminum plate for temperature sensing, and four top aluminum contacts that provide electrical connection to sensing materials or to films that are being deposited. Arrays of micro-hotplates have been fabricated and used to study film growth at several substrate temperatures. A matrix of experiments can be performed during one deposition cycle using such an array of structures. Examples will be presented using the microhotplate: to monitor substrate temperature during aluminum sputtering, to monitor film resistivity during deposition, and to sense the presence of gas species.