Phosphorus Diffusion is used in the manufacture of solar cells to create the emitter. Silicon wafers are coated with phosphoric acid fired at temperatures between 800^oC and 1000^oC to drive the phosphorus into the silicon creating the emitter.

BTU’s integrated Meridian™ In-Line Diffusion System was first introduced in 2008. The Meridian™ can be configured to process up to 1,500 wafers per hour. Excellent thermal uniformity of ± 2 °C or better produces very predictable and repeatable sheet resistance values, configurable from 40 to 100 ohms/sq and higher. Quartz lining insures tight atmosphere control required to maintain proper phosphorus drive-in. The Meridian™ Phosphorus coater features highly reliable, repeatable and uniform nozzle-less spray technology. This new coater includes key features such as back-side and top-side coating and an integrated dryer. The Meridian™ in-line system offers reduced wafer handling, very low breakage rates, improved yield and lower Cost of Ownership than traditional batch diffusion tools.

In 2009 the Meridian™ was awarded the ‘Industry Choice’ International Solar Technology Award during a ceremony at the Intersolar Munich show in Germany. The International Solar Technology Awards are designed to acknowledge and recognize achievements in the creation and development of solar technology. Emphasis is placed on real-world technical advancements required throughout the supply chain to push solar power toward grid-parity without government subsidies. Each award category was judged by a panel of industry experts and the industry public, through online voting. For the ‘Industry Choice’ award, the definitive category for solar applications, the popular voting is double-weighted.