| 20100032812 | Method for forming silicon germanium layers at low temperatures, layers formed therewith and structures comprising such layers - A method is provided for controlling the average stress and the strain gradient in structural silicon germanium layers as used in micromachined devices. The method comprises depositing a single silicon germanium layer on a substrate and annealing a predetermined part of the deposited silicon germanium layer. The process parameters of the depositing and/or annealing steps are selected such that a predetermined average stress and a predetermined strain gradient are obtained in the predetermined part of the silicon germanium layer. Preferably a plasma assisted deposition technique is used for depositing the silicon germanium layer, and a pulsed excimer laser is used for local annealing, with a limited thermal penetration depth. Structural silicon germanium layers for surface micromachined structures can be formed at temperatures substantially below 400° C., which offers the possibility of post-processing micromachined structures on top of a substrate comprising electronic circuitry such as CMOS circuitry. Such structural silicon germanium layers may be also be formed at temperatures not exceeding 210° C., which allows the integration of silicon germanium based micromachined structures on substrates such as polymer films. | 02-11-2010 |
