Our solutions boost your productivity Broad range of mask solutions enables flawless production of high-end photomasks

A photomask is a template used in semiconductor production, especially in photolithography. It consists of a transparent material, e.g. glass or quartz, and has very special structures on its surface. These structures form the blueprint of the microchip. They are projected onto a silicon wafer in several layers with the help of light, which creates the three-dimensional structure of the later microchip.
Finally, several chips can be cut out per wafer.
 

The blueprint of the chip structures on a photomask is extremely fine - individual structures are only five or seven nanometres in size. Small defects therefore always occur during the manufacturing process of a photomask. If a photomask has a defect and this is not corrected, it is projected onto the wafer many times during the exposure process, rendering the microchip unusable. As many thousands of chips are produced with a single photomask, such so-called critical defects must be repaired before the photomask is used again.

Depending on the type and size of the defect on a photomask, there are different ways to repair it.
A common method of repairing a defect on a photomask in the low-end segment are tools based on Focused Ion Beam (FiB) technology. Here, the defective area is identified first and then the defect is corrected by removing materials on the mask. A more flexible method, which is standardly used for mask repair in the high-end segment, is based on the interaction of a focused electron beam with added precursor molecules. The defective area of the mask is corrected either by localized application or removal of material, thus repairing the defect.
 

Typically, the following steps are taken:

a) Define the features to be measured (line widths, positioning and height of structures on the mask, etc.)
b) Set up measurement equipment like a microscope or photomask inspection system
c) Place the photomask under the microscope or inspection system
d) Focus and adjust the magnification for clear visualization
e) Taking well-lit, high-resolution images of the features
f) Analyse the images using suitable analyses software
g) Record and document the measurement and the measurement results for reference and quality control
 

Registration metrology is a technique used in semiconductor manufacturing to measure and verify the exact alignment of components or patterns. Special measuring devices and imaging techniques can be used, for example, to detect alignment problems or deviations during the manufacturing process of a microchip. This is the only way to ensure that the individual layers interact with each other and that a microchip thus functions.