Precision sensor supplier Micro-Epsilon has extended its interferoMETER range of white light interferometers to include a sensor with a 90° beam path that enables stable thickness measurement of silicon and silicon carbide semiconductor wafers.
With an IP68 protection rating and integrated air purge device, the new robust interferoMETER IMP-NIR-TH3/90/IP68 is specially designed for demanding production environments.
The sensor enables precise thickness measurements of semiconductor wafers during production even when high particle loads occur, such as in the slurry grinding process. The sensor has a small working distance of just 3mm, making it suited to applications with very limited installation space.
Within slurry grinding, the sensor’s IP68 housing allows it to be used directly in the machine, even with high humidity and high particle loads. In grinding and lapping processes, a clean appearance is achieved via the integrated air purge device, which keeps the optics permanently free of particles and enables stable measurement.
A key feature of the sensor is the 90° optical beam path, which enables integration in very tight installation spaces. The working distance (3mm) and very small light point diameter (15μm) create the basis for high precision inline measurements directly in the machine.
The IMP-NIR-TH3/90/IP68 sensor is operated using the IMS5420 controller, providing a compact, reliable solution for the measurement of highly doped wafers, where high signal quality is critical.
The interferoMETER IMS5420 system incorporates a broadband superluminscent diode (SLED) with a wavelength range of 1,100nm, allowing thickness measurements of undoped, doped and highly doped silicon wafers using only one measuring system.
Thicknesses from 50 to 1050µm can be measured with a doping of up to 5mΩcm from a distance of 24mm, and signal stabilities (z-axis resolution) of less than 1nm can be achieved. Even for highly doped wafers with a specific resistance of 0.005Ωcm, thicknesses from 0.05mm to 0.85mm can be measured.
With a measuring rate of up to 6kHz, the interferoMETER IMS5420 is suitable for in-line and at-line thickness measurements, such as after and during grinding and lapping, as well as during quality control. Other applications for the measurement system include thickness measurement of glass and film.
The interferoMETER IMS5420 is available either as a thickness measuring system or as a multi-peak (MP) version for thickness measurement of up to five layers (e.g. wafer thickness, air gap, film and coatings >50µm) with silicon thicknesses from 0.05 to 1.05mm. The measurable thickness of air gaps is up to 4mm.
For easy set up and configuration, a modern, intuitive web interface is provided. In addition, various interfaces (EtherCAT, Ethernet, Profinet, EtherNet/IP, RS422, analogue) offer numerous integration options.
