Product Briefing Outline: SierraTherm Production Furnaces has introduced its new 5500 Series APCVD system with a 660mm deposition width. This tool is capable of depositing a combination of up to five layers of doped (BSG, PSG) and undoped SiO2 films in a single pass. Its throughput capacity of 1875 WPH for 156mm wafers or 2300 WPH of 125mm wafers make it compatible with today’s high production cell lines. Films with thicknesses of up to 300nm can be deposited at this process speed.
Problem: Depositing doped and undoped SiO2 films onto crystalline silicon solar cells has been problematic due to the unavailability of high throughput deposition equipment. Atmospheric pressure chemical vapor deposition (APCVD) systems transport wafers on a conveyor belt and deposit films at elevated temperatures as the wafers pass beneath chemical injector heads. While in-line APCVD systems have existed for some time, the production capacity of these tools has been only a fraction of requirements due to limitations on film deposition width across the conveyor belt used to transport the cells.
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Solution: The 5500 Series APCVD conveyor furnace is well suited for continuous high volume processing of substrates requiring single as well as multi-layer thin films. SierraTherm’s in-line system design assures that each substrate receives the same process treatment. Distinctly unlike other furnaces, the SierraTherm 5500 Series is claimed to be an energy efficient precision thermal processing system with the required high-performance.
Applications: SnO2:F. Transparent conductive oxide for sheet glass. Other conductive film applications include SiO2, undoped; Diffusion barrier or insulating layer for silicon wafers or soda-lime sheet glass; SiO2, boron or phosphorous doped (BSG or PSG)
TiO2: Antireflective layer for silicon solar cells.
Platform: Maintenance conscious design allows chemical injectors and exhaust ducting to be cleaned in-situ. Multiple injector heads can be used in series within a single furnace, maximizing process throughput, uniformity, and flexibility while minimizing cost. Modular chemical vapor injector head assemblies allow quick and easy installation and removal from the coating chamber.
Availability: July 2008 onwards.