Technology for Polarization Measurement

PV-Si Birefringence Measurement System

During the production of Si solar panels, stress in Si crystals often remains undetected long into the fabrication process. Hinds Instruments has developed a stress birefringence instrument for measuring Si ingots, either squared or as-grown, before they are sawed into wafers. When this instrument is used as a QC tool, low quality Si ingots or segments can be identified before subsequent processing costs are incurred. In addition, this instrument provides growers of Si crystals a tool with which to improve the quality of Si ingots so they can produce thinner wafers with low mechanical yield loss.

Hinds Instruments’ Near Infrared Exicor® Birefringence Measurement System 500 Si Ingot is an extension of the workhorse platform of the Exicor birefringence measurement system family of products. This system employs high quality, symmetrical photoelastic modulators, a 1550 nm laser, and a Ge avalanche photodiode detector to enable high accuracy birefringence measurements for Si materials used in both the photovoltaic and semiconductor industries. In addition to Si, materials such as sapphire, silicon carbide, zinc selenide, cadmium sulfide can also be measured with this system. The 500 Si Ingot model is robust and versatile, built to hold and measure a 500mm length of raw ingot up to diameters of 8 inches. The system design and intuitive automated scanning software make this product the best choice for material improvement, R&D efforts and day-in-day-out evaluation of raw Si ingots as well as other high tech materials.

Features:

  • Unprecedented sensitivity in low-level birefringence measurement
  • Simultaneous measurement of birefringence magnitude and angle
  • Precision repeatability
  • High-speed measurement
  • Automatic mapping of variable-sized optical elements
  • Photoelastic modulator technology
  • Simple, user-friendly operation

Figure 1: Exicor scan of a silicon ingot.

SPECIFICATIONS

Extended Range
1/2 Wave Systems
Retardation Range 0.1 to 775 nm
Resolution / Repeatability:
Retardation1 0.1 nm
     Fast Axis Angle 0.01º at >10 nm
Measurement up to 100 pps
Spot Size ~2 mm typical
Sample Size 500 mm x 150 mm for squared ingots /
500 mm x 210 mm for as-grown ingots

1Up to 10 nm, 1% thereafter.

Contact us for more information about the Exicor PV-Si and to see how Hinds Instruments works with our customers to provide unsurpassed birefringence measurement metrology.