Manz AG has launched new equipment to address the wet-chemical processing of crystalline silicon solar cells. The IPSG CEI 4800 removes the highly doped layer from the backside and the edges of a wafer and thereby produce chemical edge isolation (CEI). In a second process step the remaining phosphor silicate glass (PSG) layer on the front side of the wafer that was created during the previous diffusion process step, is removed.
Cost reduction strategies within c-Si processes remains a critical focus of PV manufacturers. Attention to wafer throughput while offering a lower cost tool is essential, which can be met by integrating multiple process steps in a single tool. However, a balance between high-throughput and yield also need to be considered.
IPSG CEI 4800 removes the highly doped layer from the backside and the edges of a wafer and thereby produces a chemical edge isolation (CEI). In a second process step the remaining phosphor silicate glass (PSG) layer on the front side of the wafer that was created during the previous diffusion process step, is removed. The newly developed soft sponge roller process concept enables faster inline transportation speeds and ensures at the same time higher process stability combined with gentle wafer handling. As the name of the new tool implies, throughput will be high at up to 4800 w/h. In tests the new wet-chemical tool operated with a breakage rate of no more than 0.1 percent, including automation. Due to a magnetic coupling system the gear wheels and drives are completely separated from the wet chemical bath. The new IPSG CEI 4800 is built following a modular concept which allows easy maintainability and accessibility to all modules and components. The company claims that as a results, higher uptime and an outstanding process performance-to-price ratio is achieved .The tool will also be sold as a bundle with the Manz SpeedPicker for loading and unloading requirements.
Phosphor silicate glass removal and edge isolation.
The IPSG CEI 4800 footprint is approximately 12,200 x 2,150 x 2,200 mm in non-automated configuration and 16,250 x 3,050 x 2,600 mm with automation. Throughput is claimed to be 4,800 wafer / h (with optimization up to 5,000 wafer / h). Performance uptime is said to be 95% and delivers a wafer breakage rate of < 0.1% including the use of automation. The system can handle mono and multicrystalline wafers with thickness of 250μm to 120μm.
May 2012 onwards.
Manz launched its first wet-chemical processing tool at SNEC 2012. Head of Product Development Wet Chemistry cSi Solar at Manz, Kari Raudasoja talked to PV-Tech about the IPSG CEI 4800, see left.