LAYERS 9 – SOLARIS® increases throughput for thick aluminum layers
Evatec has a long track record in delivering metallization solutions using both evaporation and sputter technologies. While evaporation remains the preferred method for many lift off processes, increasing production volumes and larger wafer sizes are driving interest in automated cassette to cassette systems that reduce manual handling and improve yield. In this context, SOLARIS® has been evaluated as a high throughput solution for sputtering thick aluminum layers in power device applications.
Many power device processes require aluminum layers with thicknesses ranging from 1 to 18 micrometers on frontside and backside surfaces. At the same time, substrate temperatures must typically remain below 300 degrees Celsius. To meet these requirements, Evatec conducted detailed temperature simulations to determine the optimal SOLARIS® configuration. The results showed that a setup with four PVD chambers and two cooling stations provides the right balance between deposition speed and thermal control.
The SOLARIS® tool uses a synchronous indexer with parallel carrier transfer, allowing multiple substrates to be processed simultaneously. In the evaluated configuration, aluminum is deposited in two consecutive PVD chambers until the temperature limit is reached, followed by a cooling step. This sequence can be repeated within a single indexer rotation, enabling thicker layers to be built up through multiple cycles.
Simulation results indicate a theoretical throughput of almost 60 wafers per hour for 2 micrometer aluminum layers and more than 16 wafers per hour for layers up to 18 micrometers on 8 inch substrates. Experimental measurements confirmed acceptable uniformity results for thick aluminum films, including an 18 micrometer layer deposited on 6 inch silicon wafers.
Compared to traditional evaporation systems, SOLARIS® shows a clear throughput advantage when moving from 6 inch to 8 inch wafers. Fully automated handling, flexible carrier concepts, and support for double sided processing make SOLARIS® a scalable solution for modern power device manufacturing.
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