DUAL STRUCTURAL POLYSILICON BIFET-COMPATIBLE SURFACE MICROMACHINING MODULE

A double structural polysilicon layer surface micromachining process c ompatible with a standard BiFET process has been designed and fully ch aracterized. This process is to be used as a post-microelectronic proc ess module and the overall process requires 17 masking steps. The thic kness of the structural polysilicon is adjustable and the default valu es are a 3000 Angstrom lower polysilicon layer and a 3000 Angstrom nit ride/3000 Angstrom polysilicon upper structural layer. Special techniq ues are implemented to maintain the integrity of the microelectronic p assivation and the interconnect during sacrificial etching. The layers are spaced 4000 Angstrom apart using a PSG layer. High-performance mi crostructures have been fabricated after completion of the microelectr onic process without degradation of the microelectronic devices.