Wafer-level glass-caps for advanced optical applications

Abstract

A novel process flow to manufacture miniaturized optical windows on wafer-level is presented. Those windows can be used for miniaturized optical products like high-brightness LEDs (HB-LED) and digital projection (DLP) as well as more complex optical data-communication, since integrated optical functions can be implemented with low tolerances. We explain the fabrication of cap-wafers having a shallow cavity with a depth of typically 10m used in photo sensors and a unique manufacturing process for cap-wafers with a deep cavity of e.g. 300m used in LED packaging. Those cap-wafers are used in wafer-level integration of advanced, miniaturized optical products. We discuss two options for wafer bonding i.e. bonding using adhesive as well as anodic bonding. As an example on product level a miniaturized photo sensor package, a pressure sensor package as well as a LED package is discussed

Low-Temperature Bonding for Silicon-Based Micro-Optical Systems

“…They may oxidize the electrical interconnect metals, resulting in high resistance. In the integration of micro light-emitting diodes (LEDs) or optical detectors, anodic bonding was used to form hermetic optical caps [79] (Figure 8). First, cavities were etched in a Si substrate, followed by mounting optical components such as detectors or LEDs inside the cavities.…”