SEMI PV32 - Specification for Marking of PV Silicon Brick Face and PV Wafer Edge
The high volumes of silicon (Si) wafers manufactured for photovoltaic solar cells exert continuous pressure on manufacturing cost and yield. This requires continuous improvement of quality control throughout the entire process chain for producing c-Si based PV solar cell modules. A prerequisite for this is a means for uniquely identifying the individual wafers regarding their origin. This can be achieved by providing PV wafers with a unique, unmistakable mark that relates to both the parent brick and the individual wafer. This will benefit the entire PV industry ranging from suppliers of silicon wafers to module manufacturers.
The mark applied to the wafers must be capable of containing all relevant information, has to be stable and remain readable throughout the manufacturing process steps of solar cells and cell modules and their entire life. It also must not decrease the efficiency of the solar cells nor impact the cell/module manufacturing cost negatively.
This Specification defines a mark that can easily be applied and read, and that is designed for stability throughout all solar cell manufacturing steps. It is described as brick slice code (BSC). The BSC consists of a pattern of grooves applied to the polished side surface of a silicon brick by a fast laser scribe process. This pattern then appears as a mark on the individual wafers outside of the active area of solar cells after the brick is sliced. This mark is readable from both the top and bottom sides of the wafer and is independent of the positional orientation of the wafer.
Marks are widely used for identifying tracking and tracing wafers in the semiconductor industry. Therefore equipment for applying and reading marks is easily available.
An additional advantage of a unique wafer mark is product security for producers and users of wafers and solar cells with respect to fraud, theft and counterfeiting.
Referenced SEMI Standards
SEMI MF728 — Practice for Preparing an Optical Microscope for Dimensional Measurements