AN ENHANCED METHOD FOR DEVELOPING MULTI-LEVEL HIGH-ASPECT RATIO CHIPS

摘要

Micro-electromechanical systems (MEMS) have become the heart of many miniaturized devices and have penetrated into diverse industries. The MEMS chips are widely used in microsensors, microactuators, microinstruments, microoptics, digital light projectors, and so on. Most of MEMS manufacturing technology tends to fall into the two broad categories of bulk manufacturing and surface manufacturing. Bulk micromachining creates structures by selectively etching inside a substrate (that is, silicon wafer). Anisotropic wet etch has been a typical etch in silicon. Surface micromachining involves the deposition of thin films and selective etching of different structural layers on top of the silicon substrate. Polysilicon is often used as one of the layers while silicon dioxide can be used as a sacrificial layer. In addition, high-aspect ratio micromachining allows for creating high-aspect ratio microstructures. LIGA, which is a German acronym for 'Lithographic Galvanoformung Adformung,' is primarily a non-silicon-based technology for creating high-aspect ratio microstructures. The two main LIGA-fabrication technologies are X-ray LIGA and UV LIGA. While X-ray LIGA uses X-rays produced by a synchrotron to create high-aspect ratio structures, UV LIGA is a less costly method that uses ultraviolet light to create structures with relatively low-aspect ratios.