Semiconductor wafer fabrication relies upon microscopes for nearly all steps of the manufacturing process to provide feedback to the individual process module and for inspection of the finished product as it moves to the packaging process.

 Even in the most automated factories, microscopes are used to analyze layer deposition and etch with such techniques as Brightfield, Darkfield and Differential Interference Contrast (DIC). The deposition of materials is critical for successful circuits construction and the composition of the metal deposited must be carefully analyzed to ensure a proper circuit. The DIC technique in particular allows the engineer to visualize the three dimensionality of the circuit under examination.

Photolithography is another critical process in semiconductor manufacturing that requires microscopic examination. As photo-resist removal demands increased precision etching, a wafer inspection microscope such as one of Olympus’ MX 51/61 Series provides an efficient way to confirm removal of residual resist, found through the use of a technique known as fluorescence – a simple method of using the inherent characteristics of the photo resist in combination with a special illumination filtration system that allows the residual resist to light up on a dark background. A fast and simple microscope inspection can also confirm the use and alignment of the correct layer.

 Microscopes are vital to the semiconductor manufacturing process in a wide range of roles. As the increasing demands of the industry have pushed white light optics to the limit, Olympus continues to pursue non-visible techniques such as Deep Ultra Violet (DUV) where the current .30 micron limit is being pushed to the ~0.08 micron range with our MX Series of wafer inspection systems combined with our new U-UVF248 module.  The module is easily retrofitable to new or existing Olympus microscope systems.

Confocal laser microscopes are becoming increasingly popular semiconductor inspection tools. Our LEXT OLS3000 laser confocals bridge the gap between standard white light microscopes and scanning electron microscope (SEM), featuring fast, easy operation with no destructive sample preparation required.

 

 

 

 

 

Al pattern viewed through an Olympus LEXT OLS3000 laser confocal microscope

 

Every time a wafer is handled the risk of contamination is increased – that’s why Olympus has developed some of the world’s safest automated wafer loading systems for microscopic inspection. Our new AL110 provides semiconductor manufacturers with the most advanced wafer inspection possible, including front and back macro and micro viewing for complete and thorough inspection.

The availability of fluorescence observation allows the identification of residual organic contaminants.  Through the careful choice of the proper mirror cube, specific contaminants can be identified after processing.  For example, remaining photoresist after stripping can easily be pinpointed and, with another cube choice, dust and particulates are visible.

Dust particle highlighted by fluorescent observation

Chart showing excitation and emission energies for one of the Olympus mirror cubes.

Olympus offers different filter combinations to precisely match the excitation energy with the contaminant in question.  Empty mirror cubes are also available, allowing the use of custom made, third-party configurations to exactly match your requirement.