Plasma planarization for sensor applications |
| |
Authors: | Li Y.X. French P.J. Wolffenbuttel R.F. |
| |
Affiliation: | Lab. for Electron. Instrum., Delft Univ. of Technol.; |
| |
Abstract: | Filling trenches in silicon using phosphosilicate glass (PSG) provides many possibilities for novel device structures for sensors and actuators. This paper describes a plasma planarization technique that provides fully planarized PSG filled silicon trenches for sensor applications. The technique consists of planarizing the substrate using two photoresist layers and plasma etching-back. The lower resist layer is the AZ5214 image reversal resist, which is patterned and then thermally cured. The upper resist layer is a global HPR204 coating. The plasma etching-back is carried out using CHF3/C2F 6 gas mixture with an O2 addition. It is shown that by using the image reversal photoresist approach, fully planarized surface coating can be obtained without resorting to an additional mask. By adding 25 sccm (14%) O2 into the 137 sccm CHF3+18 sccm C2F6 gas mixture, the etch rates for the photoresist and PSG can be matched. Process optimization for the two layer resist coating and plasma etching is discussed |
| |
Keywords: | |
|
|