Investigation of a unified LTCC-based micromachining and packaging platform for high density/multifunctional microsystem integration

Abstract

3D system-in-package has recently been considered a major enabler for high density and heterogeneous microsystem integration. We hereby proposed the concept of a unified micromachining and packaging platform based on LTCC (low temperature cofired ceramic) material system and process, which is implemented by first enhancing an existing LTCC hybrid IC fabrication line and then integrating different LTCC micromachining process modules one by one. Hence, the unified process flow can be accomplished within just one single package-test house. The platform has been capable of micromachining basic 3D MEMS (micro electromechanical system) microstructures into LTCC laminates and using them as a packaging substrate for mounting IC/MEMS from other process platforms, realizing self-contained and versatile microsystems of high density. The 3D microstructures formation process consisting of green tape machining, lamination and cofiring are demonstrated. The designing, analysis and fabricated samples of various micro functional structure enabled by the platform are illustrated, including embedded cooling microchannels (capable of lowering substrate temperature by more than 50K), microaccelerometer for harsh environment, micro Pirani gauge for in-situ vacuum level monitoring and THz (tera hertz) vacuum microelectronic devices. Samples of overall packaged MEMS and IC chips with micromachined LTCC substrate are displayed, showing ultra-low leakage ( < 5×10 -11 Pa·m 3 /s) vacuum packaging capability and significantly enhanced device performance. In addition, the platform has demonstrated the potential of stacking several laminates with mounted chips into a 3D frame-like microsystem. In comparison, 3D integration purely based on Si micromachining, e.g. anodic-bonding based insitu wafer encapsulation, may only support a very limited spectrum of devices/materials and integration density and is somehow too expensive for many MEMS researchers. I IntroductionThree dimensional (3D) system-in-package (SIP) has recently been well accepted a major enabler for high density and heterogeneous microsystem integration [1-2]. Lately, various efforts for such a hybrid integration can be approximately categorized as following: a) hybrid of micromachining of different natures [2], b) micromachining micro mechanical structures over packaging or semiconductor substrate [3], c) micromachining of material traditionally for electronic packaging, like LTCC[4] and d) the diverse methodology of 3D stacking of various device planes and corresponding interconnect [5,6].We hereby propose the concept of a unified packaging and micromachining platform based on LTCC (low temperature cofired ceramic) material system and process. This platform is intended for facilitating a three dimensional, high density, agile and inexpensive integration and packaging of microstructures and ICs from various process lines. The authors modify an existing LTCC hybrid IC fabrication and packaging line into one capable of both packaging and 3D micromachining. With the LTCC micromachinin...

LTCC Flow Sensor with RFID Interface

“…The low temperature co-fired ceramic technology is frequently used for fabricating hybrid microelectronic devices [13,29,30]. The main advantage of LTCC-based hybrids is high environmental resistance.…”

Research on Processability and Transmission Performance of Low Temperature Co-Fired Ceramic Ball Grid Array Packaging Based on Electroless Plating Surface Modification for Microwave Transceiver Circuits

“…Consequently, for highreliability applications when considering LTCC as a packaging substrate, its reliability needs to be carefully assessed [21]. Specifically, as one of the crucial factors affecting long-term stability, research on the hermeticity of LTCC exhibits significant discrepancies, ranging from 10 −6 Pa/(m 3 •s) to 10 −11 Pa/(m 3 •s) [22,23]. On the other hand, HTCC has gained widespread recognition for its hermeticity, which can achieve levels ranging from 10 −9 Pa/(m 3 •s) to 10 −10 Pa/(m 3 •s) [17,24].…”