Method and structure of MEMS WLCSP fabrication

#The present invention is directed to MEMS (Micro-Electro-Mechanical-Systems). More specifically, embodiments of the invention provide methods and structure for improving integrated MEMS devices, including inertial sensors and the like.

#Research and development in integrated microelectronics have continued to produce astounding progress in CMOS and MEMS. CMOS technology has become the predominant fabrication technology for integrated circuits (IC). MEMS, however, continues to rely upon conventional process technologies. In layman's terms, microelectronic ICs are the “brains” of an integrated device which provides decision-making capabilities, whereas MEMS are the “eyes” and “arms” that provide the ability to sense and control the environment. Some examples of the widespread application of these technologies are the switches in radio frequency (RF) antenna systems, such as those in the iPhone™ device by Apple, Inc. of Cupertino, Calif., and the Blackberry™ phone by Research In Motion Limited of Waterloo, Ontario, Canada, and accelerometers in sensor-equipped game devices, such as those in the Wii™ controller manufactured by Nintendo Company Limited of Japan. Though they are not always easily identifiable, these technologies are becoming ever more prevalent in society every day.

#Beyond consumer electronics, use of IC and MEMS has limitless applications through modular measurement devices such as accelerometers, gyroscopes, actuators, and sensors. In conventional vehicles, accelerometers and gyroscopes are used to deploy airbags and trigger dynamic stability control functions, respectively. MEMS gyroscopes can also be used for image stabilization systems in video and still cameras, and automatic steering systems in airplanes and torpedoes. Biological MEMS (Bio-MEMS) implement biosensors and chemical sensors for Lab-On-Chip applications, which integrate one or more laboratory functions on a single millimeter-sized chip only. Other applications include Internet and telephone networks, security and financial applications, and health care and medical systems. As described previously, ICs and MEMS can be used to practically engage in various type of environmental interaction.

#In order to more fully understand the present invention, reference is made to the accompanying drawings. Understanding that these drawings are not to be considered limitations in the scope of the invention, the presently described embodiments and the presently understood best mode of the invention are described with additional detail through use of the accompanying drawings in which:

#FIGS. 1A-1F are simplified diagrams illustrating a method for fabricating a MEMS-IC device according to an embodiment of the present invention.

#FIGS. 2A-2F are simplified diagrams illustrating a method for fabricating a MEMS-IC device according to an embodiment of the present invention.

#The present invention is directed to integrated MEMS (Micro-Electro-Mechanical-Systems) IC (Integrated Circuit) devices. More specifically, embodiments of the invention provide a method and structure for a MEMS WLCSP (Wafer Level Chip Scale Package) fabrication, including one or more discrete MEMS devices. Merely by way of example, the MEMS device can include at least an accelerometer, a gyroscope, a magnetic sensor, a pressure sensor, a microphone, a humidity sensor, a temperature sensor, a chemical sensor, a biosensor, an inertial sensor, and others. But it will be recognized that the invention has a much greater range of applicability.

#The present application also incorporates by reference, for all purposes, the following pending patent applications: U.S. patent application Ser. No. 12/945,087, filed Nov. 12, 2010, and U.S. patent application Ser. No. 13/788,503, filed Mar. 7, 2013.

#FIGS. 1A-1F are simplified diagrams illustrating a method for fabricating a MEMS-IC device according to an embodiment of the present invention. The method illustrated here depicts a MEMS-IC device undergoing a WLCSP process using wire bonding. Device 101 of FIG. 1A shows a wafer level wire bonding step in fabrication. A CMOS MEMS wafer 110 is shown with an encapsulation 120 or cap wafer formed overlying. A wire 111 is bonded to a contact point on the CMOS MEMS wafer 110 and a contact point on the upper surface of the cap wafer 120. Device 102 of FIG. 1B shows a wafer level molding step. A molding material 130 is formed overlying the CMOS MEMS wafer 110 and the cap wafer 120. Device 103 of FIG. 1C shows a step in which a portion of the molding 130 is removed to reveal the wire bond 111.