Quasi-Monolithic Integration Technology for Microwave & Millimeter Wave Applications

1. Microwave 소자 기말 발표 Quasi-Monolithic Integration Technology for Microwave & Millimeter Wave Applications 2005. 6. 16 박 재 홍 2004-30328

2. Contents • Introduction • The Earlier Concept of QMIT • Fabrication Process of Earlier QMIT • Fabrication Results • Advantage & Shortcoming of Earlier QMIT • The Enhanced QMIT • Fabrication Process and Results for the Microstrip Circuit • Fabrication Process and Results for the Coplanar Circuit • Electrical Characteristics of an Embedded p-HEMT • Advantages of Enhanced QMIT • Summary • Reference

3. Introduction • RF, microwave and millimeter wave packaging is becoming more and more important • Affects of packaging: performance, cost, reliability, life time • There are tremendous improvements of electronic devices • The development of III-V compound semiconductor • SiGe-based BiCMOS technology  key technology for RFIC • RF micromachining and MEMS devices are developed  Integrated and packaged without hindering their performance Concept of a RF-MEMS-SiP based on the hybrid integration of the MEMS.

4. Introduction • RF and microwave packaging technology • First assemble technology (device to package) • Wire bonding, Tape automated bonding, Flip-chip bonding • Single chip packaging • Multi chip module (MCM technology) • Laminate MCM, Ceramic MCM, Deposited MCM  QMIT overcomes the limitation of earlier packaging process Cross-section of wire bond Side-view of the bump configuration in flip-chip tech.

5. The Earlier Concept of QMIT • Requirements of new packaging technology • Developments of the III-V compounds semiconductor for high frequency semiconductor • Development of the silicon micomachining for microwave and millimeterwave passive components • The appearance of earlier QMIT (1997) • Alternative monolithic circuit fabrication of microwave and millimeter wave integrated circuits • Commercial devices are embedded in a micromachined Si substrate on which the passive circuit is fabricated  allows the fabrication of planar high frequency circuits • Interconnection: thin-film technology  low parasitic inductance and capacitance

6. Fabrication Process of Earlier QMIT Fabrication process for embedding the chip into the wet-etched holes in Si-wafer Fabrication process for the earlier concept of QMIT after embedding the chips in the holes

7. Fabrication Results • Fabricated microtest-fixture with on-wafer probe compatible coplanar contacts for accurate GaAs-FET characterization in the earlier concept of QMIT SEM view of whole device SEM view of air bridge

8. Advantage & Shortcoming of Earlier QMIT • Advantage of earlier QMIT • Using active devices based on different materials • Smaller size and weight hybrid technology • Reproducible interconnections • Broader frequency performance than hybrid technology • Large area passive elements on a low cost Si-substrate • Shortcoming of earlier QMIT • The thermally conductive epoxy glue has a low glass temperature  limits the working temperature • The thermally conductive epoxy glue has a large thermal expansion coefficient  high thermo-mechanical stress • Considering the difficulties in removing the baked epoxy • Critical dimension of air bridge

9. The Enhanced QMIT • The enhanced QMIT for micro & millimeter wave applications (2003) • Overcome two major shortcoming of earlier concept • High thermal resistance of the structure • High induces thermo-mechanical stress • Also, minimize the parasitics and enable the realization of the passive elements • Two fabrication processes developed • Coplanar circuit realization  using low R silicon • Without grounding scheme • Microstrip circuit realization  using high R silicon • Normally the power chips have via hole grounding

10. Fabrication Process for the Microstrip Circuit

11. Fabrication Results of the Microstrip Circuit Embedded Ka-band power GaAs-MESFET Backside view of the microstrip circuit realization of the enhanced QMIT Front side view of the microstrip circuit realization of the enhanced QMIT

12. Fabrication Process for the Coplanar Circuit

13. Fabrication Results of the Coplanar Circuit Embedded Ka-band low noise p-HEMT The coplanar circuit realization in the new QMIT The transistor fixed with LOR

14. Electrical Characteristics of an Embedded p-HEMT (1) • Embedded Ka-band low noise p-HEMT from Alpha industries in the coplanar circuit realization of the enhanced QMIT • The transistor fixed by an 8 um thick amorphous Si layer I-V curves of the Ka-band lownoise p-HEMT in coplanar realization in the new generation QMIT

15. Electrical Characteristics of an Embedded p-HEMT (2) • On-wafer S-parameter measurements • For different bias points for the same sample have been made for the frequency range of 0.1 to 40 GHz using network analyzer • To access the embedded device for the on-wafer small signal measurements, 2 thick copper coplanar waveguides are used S-parameter magnitude and phase plots of the Ka-band low noise p-HEMT with coplanar realization in the new generation QMIT

16. Advantages of Enhanced QMIT • Active devices are fixed using low temperature PECVD amorphous silicon (for coplanar) or an electroplated gold layer (for microstrip)  low temperature process • The better geometrical construction and smaller differences in the thermal expansion coefficients  lower thermo-mechanical stress • A thick layer of polymide or other spin-on dielectrics gives proper planarisation for front process • The diamond-filled polymide or thick backside electroplated gold provides an excellent thermal resistance • It is possible to measure the microwave parameters of the embedded transistor and then fabricate the rest of the circuit  This provides very accurate microwave and millimeter designs. • No air bridges

17. Summary • A successful approach for integrating III-V semiconductor compound-based active devices in a silicon substrate has been presented • The advantages have been described and two fabrication processes for coplanar and microstrip circuit realizations in this novel technology introduced • From the technology point of view, the next steps include the fabrication of passive elements and integrating higher power active devices in the substrate • GaN based devices are an extremely attractive choice • Electromagnetic modeling and simulations, heat transfer analysis and management, active device modeling and reliability studies are required

18. Refernces • M. Joodaki, T. Senyildiz, G. Kompa, H. Hillmer, and R. Kassing, “Quasi-Monolithic Integration Technology (QMIT) for power applications,” in Proc. Eur. Microwave Week, London, U.K., Sept. 2001, pp. 175–178. • M. Joodaki, G. Kompa, T. Leinhos, R. Kassing, and H. Hillmer, “Simulation and measurement of thermal stress in Quasi-Monolithic Integration Technology (QMIT),” in Proc. IEEE 51st Electron. Comp. Technol. Conf., May 29–June 1 2001, pp. 715–720. • M. Joodaki, T. Senyildiz, and G. Kompa, “Heat transfer and thermal stress analysis in the newgeneration of quasimonolithic integration technology,” in Proc. IEEE 52nd Electron. Comp. Technol. Conf., May 2002, pp. 590–596. • L. P. B. Kathehi, J. F. Harvey, and E. Brown, “MEMS and Si micromachined circuits for high frequency applications,” IEEE Trans. Microwave Theory Tech., vol. MTT-50, pp. 858–866, Mar. 2002. E. Wasige, G. Kompa, F. van Raay, W. Scholz, I. W. Rangelow, R. • Kassing, S. Bertram, and P. Hudek, “12 GHz Coplanar quasimonolithic oscillator,” in Proc. IEEE MTT-S Int. Microwave Symp. Dig., vol. 1, 1999, pp. 227–228. • E.Wasige, G. Kompa, F. van Raay, I.W. Rangelow,W. Scholz, F. Shi, R. Kassing, R. Meyer, and M.-C. Amann, “Air-bridge based planar hybrid technology for microwave and millimeterwave applications,” in Proc. IEEE MTT-S Int. Microwave Symp. Dig., 1997, pp. 925–928. • E. Wasige, G. Kompa, F. van Raay, W. Scholz, I. W. Rangelow, R. Kassing, S. Bertram, and P. Hudek, “GaAs FET characterization in a quasimonolithic Si environment,” in Proc. IEEE MTT-S Int. Microwave Symp. Dig., vol. 4, 1999, pp. 1889–1891. • M. Joodaki, G. Kompa, H. Hillmer, and R. Kassing, “Optimization of thermal resistance in Quasi-Monolithic Integration Technology (QMIT) structure,” in Proc. 17th Annu. IEEE Semicond. Thermal Meas. Manag. Symp. SEMI-THERM XVII, Mar. 2001, pp. 12–17. • M. Joodaki, T. Senyildiz, and G. Kompa, “An Enhanced Quasi-Monolithic Integration Technology for Microwave and Millimeter Wave Applications,” IEEE Trans. Advansed Packaging, vol. 26, pp. 402–409, Nov. 2003