Project Name: Sound-Assisted Low-Temperature (SALT) Spalling: Upscaling and Throughput
Funding Opportunity: PVRD2
SETO Subprogram: Photovoltaics
Location: Tempe, AZ
SETO Award Amount: $222,519
Awardee Cost Share: $25,112
Principal Investigator: Mariana Bertoni

Exfoliating a wafer from a silicon block, known as spalling, has been shown to be a promising kerfless, waste-saving technique in wafer production. This project is researching an early-stage, novel spalling process called sound-assisted low-temperature (SALT) spalling to address defects, wafer thickness, and surface planarity through the use of acoustic waves to sharpen and facilitate crack formation during the spalling process.


The research team is working to improve SALT spalling through modeling and experimental iterations in order to maintain total control of the surface roughness for the entire wafer. This improvement will help increase the number of wafers that can be produced from a single ingot. Once the technology is fine-tuned, the team will work on increasing the wafer size.


This project, which builds upon Arizona State University’s previous project, will apply energy along with acoustic waves in the wafer production process. By fine-tuning the crack propagation speed, the improved SALT spalling technology has the potential to spall larger wafers with the same surface quality as the initial parent substrate. This process will result in a wafering technology that is more efficient for manufacturing and eventually lead to a lower levelized cost of energy.