Optimization of a BEOL Aluminum Deposition Process Enabling Wafer Level Al-Al Thermo-Compression Bonding
| Autor: | Mehmet Kaynak, Helmut Kurz, Peter Kerepesi, Sebastian Schulze, Matthias Wietstruck, Mirko Fraschke, Bernhard Rebhan |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
010302 applied physics
Materials science Wafer bonding chemistry.chemical_element 02 engineering and technology Surface finish 021001 nanoscience & nanotechnology 01 natural sciences Characterization (materials science) chemistry Transmission electron microscopy Aluminium 0103 physical sciences Surface roughness Cluster (physics) Wafer Composite material 0210 nano-technology |
| Zdroj: | 2019 IEEE 69th Electronic Components and Technology Conference (ECTC). |
| DOI: | 10.1109/ectc.2019.00040 |
| Popis: | The main challenges for Al-Al wafer bonding are the fast oxidation and the high roughness of the Al surface. This paper describes an optimized Al sputter-deposition process reducing the surface roughness to values below 2 nm. Based on this, a wafer level Al-Al thermo-compression bonding process is presented, where a surface treatment and the subsequent bonding are both performed in a high vacuum cluster. The patterned wafers were bonded with temperatures between 300 and 500 °C for 1 h using a bonding force of 60 kN. Scanning acoustic microscopy and transmission electron microscopy studies revealed a reliable bonding, an accurate alignment and a high uniformity for 200 mm wafers. The electrical characterization of contact chains with Al bonding pad sizes of 20×20 µm2 showed resistances lower than 50 mΩ per contact, which might indicate areas of oxide-free bonding. |
| Databáze: | OpenAIRE |
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