Integrated circuits form the bedrock of the Information Age. Silicon wafer sizes are increasing while the device feature sizes decrease, reflecting Moore’s Law and driving a need for more precise metrological and inspection sources.
Lasers for Semiconductor Inspection
As the complexity on the wafer surfaces grows, it is essential that these fabricated devices are monitored for optimisation and quality control, both during and after processing.
Critical parameters - such as thin film thickness or non-uniformity in deposition, defects, holes and scratches, overall flatness, deviations in the crystal structure or consistency of doping - can be detected and optimised using several interferometric techniques.
Laser interferometry, and the monitoring of an interference pattern from the wafer surface, is essential for controlling a number of these parameters, as well as laser ellipsometry, which allows sub-wavelength resolution of these features, below the diffraction limit of light. Controlling the accuracy and uniformity of layer thickness optimises the material use, improves performance and reduces the number of in-process failures - thereby making the manufacturing process more efficient and lowering the cost per unit.
These same techniques can also be applied to other high precision industries - such as optics and precision tooling.
Laser sources used in these applications must be single frequency to ensure a precise interference pattern, where narrow linewidths increase the signal to noise ratio. These lasers also require exceptional spectral and power stability, as well as long coherence lengths, in order to eliminate errors in prolonged measurement and ensure stable operation. Beam quality, such as pointing stability or ellipticity, are also vital for high quality interferometry measurements.
UniKLasers design and manufacture high power, single frequency laser sources with unrivalled wavelength stability, narrow linewidths and long coherence lengths over a range of wavelengths within a small footprint. We currently offer single frequency lasers in the red and green areas of the visible spectrum with our Solo 640 Series and Duetto 532 Series respectively; to complement our development of a range of UV sources, to facilitate metrology at decreasing feature sizes.