Method for fabricating locally reinforced metallic microfeature

DETAILED DESCRIPTION The exemplary methods described herein are differentiated from one another by the type and number of process steps, the materials used, as well as by the number of masks required for the photopatterning process.
The following basic process steps are used to implement a micro-reflector: cleaning and passivating the substrate (wafer) 10; forming pattern delineations of electrodes or producing a CMOS-driving circuit; pattern delineation of the recesses in a sacrificial layer; sputter-deposition of a metal layer (Al,Ni,Au), if indicated, galvanic electrodeposition (Ni), pattern delineation of a reflector and removal of the sacrificial layer.
The method according to the present invention is described beginning with the fabrication of the sacrificial layer 12 (FIG.
1a, method 1).
The sacrificial layer of positive photo-sensitive resist, for example AZ 4562 from the firm HOECHST, is deposited in a spin-coating process using a resist centrifuge.
For a 10E switching angle, micro-reflectors having, for example, a 50 .
mu.
m.
times.
50 .
mu.
m reflector plate require a theoretical sacrificial-layer thickness of 4.
35 .
mu.
m.
The thickness of the sacrificial layer is selected to achieve the particular desired angle of tilt.
The resist is subsequently exposed, e.
g.
, using a Hg-HD lamp, (irradiated) through a UV-transparent mask 17, preferably a mask of quartz or green glass, whose bottom side is patterned out of a chromium--chromium oxide layer, and developed.
First metal layer 14 of aluminum is then sputter-deposited onto sacrificial layer 12, i.
e.
, the aluminum layer is deposited by cathode sputtering, e.
g.
using a magnetron sputtering apparatus, with a pressure of 10.
sup.
-3 -10.
sup.
-2 mbar, a power of 350-450 W, and at an argon flow rate of 20-100 sccm.
The thickness (0.
1 .
mu.
m up to several .
mu.
m) of sputter-deposited aluminum layer 14 corresponds to the later thickness of the torsion webs.
During the sputtering process, the temperature of the substrate must remain below the maximum curing temperature of the photoresist of sacrificial layer 12, in order to avoid wrinkles and bubbles in the resist layer