Surface emitting laser package having integrated optical element and alignment post
View Patent ↗A package for a surface-emitting laser encloses the die between a sub-mount and a cap. The sub-mount and the cap can be formed using wafer processing techniques that permit a wafer level packaging process which attaches multiple die to a sub-mount wafer, attaches caps either separated or as part of a cap wafer to the sub-mount wafer, and cuts the structure to separate individual packages. The cap includes a transparent plate that can be processed to incorporate an optical element such as a lens. An alignment post attached to the cap indicates the position of an optical signal from the laser and fits snugly into one end of a sleeve while an optical fiber connector fits into the other end.
1. A packaging method, comprising:
electrically connecting a plurality of devices respectively to a plurality of sub-mount areas of a first wafer, wherein each device emits an optical signal from a top surface of the device;
fabricating a plurality of caps, each cap including a spacer having a hole therethrough, a plate that is transparent to the optical signals, and an optical element, wherein fabricating the plurality of caps comprises:
forming an etch stop layer top surface on a substrate;
forming a plurality of optical elements overlying the etch stop layer; and
forming holes through the substrate respectively beneath the optical elements;
bonding the caps to the first wafer, wherein the devices are enclosed in respective cavities between the first wafer and the respective caps, and for each of the devices, the optical element in the corresponding cap is positioned to receive the optical signal from the device; and
dividing the first wafer to separate a plurality of packages containing the devices.
2. The method of claim 1 , wherein forming the holes comprises etching a back surface of the substrate.
3. The method of claim 1 , further comprising attaching a transparent plate overlying the optical elements.
4. The method of claim 1 , wherein the substrate is made of a semiconductor.
5. The method of claim 1 , further comprising fixing alignment posts to the caps.
6. The method of claim 1 , wherein the caps comprise respective areas of a second wafer, and bonding the caps to the first wafer comprises bonding the second wafer to the first wafer.