What is Microengineering ?

The two constructional technologies of microengineering are microelectronics and micromachining. Microelectronics, producing electronic circuitry on silicon chips, is a very well developed technology. Micromachining is the name for the techniques used to produce the structures and moving parts of microengineered devices.

One of the main goals of Microengineering is to be able to integrate microelectronic circuitry into micromachined structures, to produce completely integrated systems (microsystems). Such systems could have have the same advantages of low cost, reliability and small size as silicon chips produced in the microelectronics industry.

When considering such small devices, a number of physical effects have different significance on the micrometer scale compared to macroscopic scales. Interest in microengineering has spawned or renewed interest in a number of areas dealing with the study of these effects on microscopic scales. This includes such topics as micromechanics, which deals with the moving parts of microengineered devices, and microfluidics, etc.

The remainder of this document introduces three of the micromachining techniques that are in use / under development.

Silicon micromachining is given most prominence, since this is one of the better developed micromachining techniques. Silicon is the primary substrate material used in the production microelectronic circuitry (ie, bettersilicon chips), and so is the most suitable candidate for the eventual production of microsystems.

The Excimer laser is an ultraviolet laser which can be used to micromachine a number of materials without heating them, unlike many other lasers which remove material by burning or vaporising it. The Excimer laser lends itself particularly to the machining of organic materials (polymers, etc).

LIGA is a technique that can be used to produce moulds for the fabrication of micromachined components. Microengineered components can be made from a variety of materials using this technique, however it does suffer the disadvantage that currently the technique requires X-rays from a synchrotron source.

A quick introduction to mask design is provided following discussion of techniques and structures, rather than directly following the photolithography section. This is so that the reader is able to become acquainted with the concept of creating structures by sequential photolithography and machining steps first, which hopefully makes it easier to understand what mask design software is trying to achieve.