Packaging micromechanical devices

DETAILED DESCRIPTION Referring to FIG.
1, a 3.
times.
3 micromechanical mirror array is shown by way of example of a MEMS device array that is advantageously packaged according to the invention.
The 3.
times.
3 array of micromechanical devices comprises nine micromechanical mirrors, shown as 11a-11i, mounted on silicon substrate 12.
The individual mirror devices in the array comprise mirror surface 14, with four way tilt capability, and drive electrodes 15-18, shown in phantom.
Control of the tilt is effected electrostatically by application of voltages selectively to electrodes 15-18.
This normally requires that each of the four electrodes be independently addressable.
Runners 21 interconnect the four electrodes for each device 11a-11i to bond pads 23.
An array of n devices, requires 4n independent electrical interconnections.
In principle, fewer electrical connections can be used but the preferred choice is that shown.
This interconnection requires a total of 36 individual runners and bond pads for the 3.
times.
3 array.
In an optical cross connect, the mirrors in the array communicate with optical beams in optical waveguides.
The waveguides, and the overall system architecture, are not part of the invention and for simplicity in presenting the invention are not shown.
However, it is well known that optical cross connects in the form of mirror arrays require compact mirror arrays, i.
e.
, close packing of the mirrors, for efficient design of the overall system.
The size, 3.
times.
3, of the array is chosen here for convenience in illustrating the complexity and critical alignment needs for large micromechanical device arrays.
Device arrays in current development may have hundreds or even thousands of micromechanical mirrors on a single silicon platform.
As the number of micromechanical devices is multiplied, the potential for alignment problems and other mechanical defects rises dramatically.
The micromechanical mirror device is given by way of example only of a wide variety of electrically driven micromechanical elements that may be fabricated in large arrays on a common substrate