Patent Application
20080034575
The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings in which:
a) shows the population of the temporary silicon group handle wafer with quartz-based resonators using a pick-and-place system;
b) shows the temporary silicon group handle wafer fully populated with quartz-based resonators;
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.
In a preliminary step quartz-based devices are formed. In this detailed description of embodiments the quartz-based devices are quartz-based resonators 20 that are formed by methods such as by the methods taught in U.S. patent application publication 2004/0211052 and described above in the background section in connection with
In a second step (not shown) the resonators 20 are diced and electrically characterized and tuned while attached to their individual handle wafers 4. Known good dies are sorted and binned according to their resonant frequencies. At this point, the individual quartz-based resonators 20 are ready to be transferred to the large area electronics host wafer 30.
The next or third step is the attachment of the quartz-based resonators 20 to the electronics host wafer.
In a first embodiment of the method disclosed herein, quartz-based resonators of the desired frequencies are precisely placed and bonded to the electronics host wafer 30 serially to form the resonator array as shown in
In the step shown in
In the first embodiment of the method disclosed herein, once the electronics host wafer 30 is fully populated with the planned number of quartz-based resonators 20, the individual handle wafers 4 can be removed by a process such as a plasma dry etch to release the quartz-based resonators 20, as shown in
The method disclosed herein has the advantage of being able to build, for example, RF filter arrays with quartz-based resonators 20 of various frequencies that were necessarily fabricated on different wafers. It also enables the assembly of quartz-based resonators 20 of different thickness on the same electronics host wafer 30.
A second embodiment of the method provides variant steps for the assembly of the quartz resonators onto the electronics host wafer 30. A temporary group handle wafer 40, preferably made of silicon, has pre-etched receptacles 45. The receptacles 45 in the group handle wafer may be made using silicon deep reactive ion etching (DRIE).
The quartz-based resonators 20 are placed into the pre-etched receptacles 45 of the group handle wafer 40 using the pick-and-place tool 50 as shown in
The group handle wafer 40 with the attached quartz-based resonators 20 is aligned with the electronics host wafer 30. The quartz-based resonators 20 are then bonded to the electronics host wafer 30 using a wafer-to-wafer bond, as shown in
The group handle wafer 40 is then removed, as shown in
Finally, the individual handle wafers 4 on the individual quartz-based resonators 20 are removed, preferably by dry plasma etching, leaving only the quartz-based resonators 20 attached to the electronics host wafer 30 as shown in
The second embodiment has the advantage of bonding all of the quartz-based resonators 20 simultaneously to the electronics host wafer 30, to improve throughput. It also enables the bonding of the quartz-based resonators 20 in a controlled environment (a wafer bonder) when vacuum or backfilling of a process gas is required for the assembly. The disadvantage is that all the quartz-based resonators 20, with individual handle wafers 4 attached, must have the same overall thickness, so using well-known mesa design technology would be necessary to define the thickness of an active part of the quartz-based resonator 20 while allowing the bonding regions to have the same or uniform thickness.
While several illustrative embodiments of the invention have been shown and described in the above description, numerous variations and alternative embodiments will occur to those skilled in the art and it should be understood that, within the scope of the appended claims, the invention may be practised otherwise than as specifically described. Such variations and alternative embodiments are contemplated, and can be made, without departing from the scope of the invention as defined in the appended claims.
