Manufacturable wafer-scale microstrip patch antennas

The antenna bandwidth depends on the thickness of the Si wafer on which it is fabricated. Unfortunately, increasing the thickness of the substrate, results in more power leaking to substrate modes and surface waves, therefore the efficiency of the antenna is reduced. By using deep-reactive- ion-etching (DRIE) the Si underneath the patch antennas can be very accurately etched, in order to form cavities with specific size and depth. However, achieving a uniform etch depth on multiple backside cavities located along a 4-inch wafer is challenging. As will be shown in the subsequent section even minor non-uniformities in the cavities depth can significantly de-tune the patch antennas and thus deteriorate the array performance. This paper presents a successful effort to improve the DRIE uniformity along a 4-inch Si wafer, and demonstrates consistent antenna performances.