Optical inspection in lithography
In strive for ever more capable electronics, advanced processes led to an increase in complicated 3D structures (i.e. FinFET and others). To keep manufacturing yield up it is absolutely necessary to tightly control all processes, such as overlay and critical dimensions of the features. With feature sizes well below the wavelength of light (currently down to 7 nm), optical inspection is challenging.
Scatterometry is a key process to measure the overlay of different lithography steps and thus ensure high yield rates. The measurement accuracy of scatterometry is well below 1 nm and suited to judge and correct for overlay errors.
Lasers for scatterometry measurements must be highly stable in their power output. At the same time, a wide emission spectrum is helpful to prevent speckle effects. Of course, a good and stable beam shape is required as with most measurement techniques.
This unique set of requirements is provided by TOPTICA's lasers that are superior to most other diode lasers on the market.