WLT

Fast non-contact thickness, TTV and resistivity characterization.

Thickness and resistivity are primary quality control parameters for silicon wafers in PV applications.

The WLT models, WLT-1, -3 & -5 In-Line Thickness and Resistivity Testers allow measurement of thickness at 1 to 5 points and resistivity at 1 point with the high throughput that meets the requirements of in-line quality control in fully automated wafer production lines.

The WMT models, WMT-1 & -3, Thickness and Resistivity Testers allow measurement of wafers “on the fly”, i.e., conveyor belt does not stop during measurement. Therefore, they have the high throughput that meets the requirements of in-line quality control in fully automated wafer production lines.

Description

Features and System specifications:

  • Meas. technique: capacitive thickness and eddy current resistivity
  • Sample size: 125 to 156 mm (210 mm option)
  • Distance between top and bottom sensors: 2 mm (4mm option for WLT)
  • Thickness range: 100 to 500 µm
  • Resistivity range: 0.3-15 Ωcm
  • Wafer vertical position tolerance: <300 μm
  • Sample support: on belt
  • Calibration: by wafers verified with mechanical gauge and four point probe

Options:

  • Measurement module (incl. 1-5 sheet resistance measurement heads)
  • Industrial PC (Windows operation system) and peripherals
  • P/N conductivity type tester
  • Temperature sensor
  • Warp & Bow calculation
  • Wafer presence sensor (WMT only)

Wide variety of  available interfaces to automation and MES:

  • 24V optically isolated I/O, Ethernet interface
  • Profibus
  • OPC DA
  • TCP/IP protocol, content can be XML or ASCII
  • SQL database
  • SECS/GEM