Development of Assembly Techniques for Connection of AlGaN/GaN/Si Chips to DBC substrate
Ryszard Kisiel , Marek Guziewicz , A. Taube , Mariusz Sochacki
AbstractUtilizing full possibilities of power semiconductors based on GaN or SiC requires development of new assembly techniques. One of critical element of these techniques is elaborate proper assembly technology of chip to substrate which permit on effective removing of the heat from the chip. By decreasing junction temperature it is possible to extend working time and device reliability. Power chips are frequently assembled in metal packages or on ceramic substrates. In such solutions assembly metallization is done by Au, Ag, Cu on ceramic or on Au- as well as Ni-platted metallic packages. On the other hand assembly layer on semiconductor chips are required, it can be Au, Ag or even Cu. To joint both mentioned elements it is possible to apply the following technologies: soldering, sintering or SLID (Solid Liquid Intediffusion bonding) [1, 2]. In case of soldering technology, the connection is done by solder layer. Typical PbSn solder was used here, or currently eutectics of AuSn [3, 4] or GeSn are applied. In such case soldering temperature significantly exceed 350 ⁰ C, the joints are even thicker than 100 µm, their thermal conductivity are 40-60 W/mK and maximum working temperature is 200 o C. Sintering technology bases mainly on Ag powders. By applying Ag nanopowders it is possible to decrease joining temperature up to 200 o C without losing thermal and mechanical properties of the joints. To use Ag micro powders it is necessary to increase joining temperature to 300 o C or higher. Such joints are characterized by very good thermal parameters (thermal conductivity 100-200 W/mK), low thickness (near 20 µm) without losing maximum operating temperature (up to 500 o C). SLID technology require thin Sn layer (1-2 µm) which should be deposited on substrate metallization. Joint made by this technology is extremely thin (up to 5 µm), it has thermal conductivity in range of 60-80 W/mK and acceptable operating working temperature up to 400 ⁰ C. The assembly temperature must exceed Sn melting point so joints are formulated at temperature near 250 o C. It means practically that joining temperature is the same as for SAC solders (245-250 o C). Taking into account the advantages of these technologies e.g. high working temperature and good thermal conductivity, we investigate here sintering as well as SLID assembly technology to attach AlGaN/GaN/Si chips to DBC (Direct Bond Copper) substrate.
|Publication size in sheets||0.3|
|Book||Walczak Rafał, Malecha Karol (eds.): Technical Digest of Conferences ELTE IMAPS 2019 , 2019, International Microelectronics and Packaging Society Poland Chapter, ISBN 978-83-932464-3-4, 205 p.|
|Keywords in English||assembly, SLID technology, DBC, AlGaN/GaN/Si, HEMT transistor|
|Score||= 0.0, 16-12-2019, ChapterFromConference|
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