THIN-BEAM BULK MICROMACHINING BASED ON RIE AND XENON DIFLUORIDE SILICON ETCHING

A new process for fabricating thin mechanical beam structures from sin gle-crystal silicon has been developed. Lateral and vertical dimension s of the beam can be precisely defined. The beam is positioned in the middle of a silicon wafer at exactly equal distances from both sides. The beam design is not limited by crystal orientations of silicon. The silicon beam structure is essentially stress free because the whole s tructure is made of uniformly doped single-crystal silicon. This thin- beam process offers significantly expanded design freedom to bulk sili con micromachining. Additionally,a silicon dioxide structure with very high aspect ratio has been fabricated with a similar technique. (C) 1 998 Elsevier Science S.A. All rights reserved.