mikromaskering

Mikromaskering is a technique used in photolithography, a crucial process in semiconductor manufacturing. It refers to the practice of incorporating deliberately designed, small features into a photomask's layout. These features, often referred to as "assist features" or "sub-resolution features," are typically smaller than the critical dimensions of the circuit pattern being printed. Their purpose is to improve the fidelity of the lithographic process, particularly when printing very small or complex patterns that would otherwise be difficult to resolve accurately.

The primary benefit of mikromaskering is to enhance the process window, which is the range of exposure and focus conditions under which a satisfactory print is achieved. These assist features work by influencing the diffraction and interference patterns of the light passing through the photomask. They can help to sharpen the edges of the main pattern, reduce optical proximity effects (where the spacing between features affects their printed size), and improve the overall imaging performance. This can lead to higher yields and more reliable device performance.

Common examples of mikromaskering include the use of scattering bars, which are small, isolated lines placed near critical features, and shaded features, which are small, opaque squares or rectangles placed within clear areas of the mask. The design and placement of these mikromasking features require sophisticated optical modeling and simulation to optimize their effectiveness. While they do not print themselves onto the wafer, their presence on the mask significantly impacts the quality of the final printed image.