Automated Design for Micromachining: Suspension, Bistable

Introduction

A suspension is like a spring, designed to be compliant. However, they are also designed to be stiff in the perpendicular direction. This suspension has two stable resting points.

Figure 1: Layout of a bistable suspension.

Theory

Nothing yet.

Parameters

Any parameter may be modified, if necessary, to meet design rules. Typically, this involves increasing parameters that specify distances, so that minimum line width and minimum line spacing rules will not be violated. This has been extended to the convention of specifying a zero for some parameters to obtain an instance of the minimum size.

In addition to the parameters listed below, several technology parameters also influence the implementation of parameterized cells. This data must be present in the technology library.

Table 1: Parameters for the 'suspension_bistable' parameterized cell.
Name	Description	Range	Units
layer	Control the layer.	P1,P2,DT	-
length	The length of all of the compliant beams.	[0,∞)	um	+	+
width	The width of the compliant beams.	[0,∞)	um	+	+
deflection	The deflection of the beams from the center line. The total displacement from one state to the other will be twice this distance.	[0,∞)	um	+	+
shuttle_width	The width of the shuttle	[0,∞)	um	+	+
shuttle_length	The length of the shuttle.	[0,∞)	um	+	+
anchor width	The length of the compliant beams.	[0,∞)	um	+	+
include_poly0	If true, a POLY0 ground plane will be included in the cell. The POLY0 ground plane can eliminate most electrostatic attraction between the suspension and the substrate bulk.	true/false	-	+	+

References

[1] Y.-J. Yang, B.-T. Liao, and W.-C. Kuo. "A novel 2x2 MEMS optical switch using the split cross-bar design," Journal of Micromechanics and Microengineering. vol. 17, no. 2, pp. 872-882 (2007).