Thin beam bulk micromachining based on RIE and xenon difluoride silicon etching

A new process for fabricating thin mechanical beam structures from single crystal silicon is developed. Lateral and vertical dimensions 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 structure is made of uniformly doped single crystal silicon. This thin beam process offers significantly expanded design freedom to bulk silicon micromachining. Additionally, a very high aspect ratio silicon dioxide structure can be fabricated with a similar technique.