Direct Writing on the Microscale

Maskless Photolithography

Traditional photolithography calls for the fabrication or purchase of a photomask and the use of a stepper or mask aligner to transfer the CAD-pattern onto the resist-covered wafer or plate. At this point in time, the well-established photomask process is indeed the only feasible way for high volume manufacturing of sub-micron sized design features and Heidelberg Instruments offers systems for the production of photomasks in semiconductor, electronics, and display industry (VPG+, ULTRA).

There is, however, another photolithography technique available which constitutes the perfect tool for many other applications: Maskless photolithography. This state-of-the-art, fast, highly precise, and exceptionally versatile technology is ideal for the use either in Research & Development or in a prototyping environment that involves designs with features of over one micron. If that describes your area of work and you are familiar with the disadvantages of the photomask process, there is a technique that enables you to transfer your design straight to the wafer, forming the pattern, while eliminating the mask aligner and photomask process altogether.

In maskless photolithography the pattern is exposed directly onto the substrate surface with the help of a spatial light modulator (SLM) – which serves essentially as a programmable mask. The system takes your design file and simply “writes” the pattern onto the resist-covered substrate. This direct-write process puts you in a position to skip the entire time-consuming and expensive photomask process and all it involves: Instead, you can redesign your CAD-drawing (again and again, if necessary) and immediately re-expose the pattern. – Discover our Maskless Aligner (MLA) and Direct-Writing (DWL) series of laser lithography tools.

The Spatial Light Modulator (SLM)

A spatial Light Modulator (SLM) (essentially a “dynamic mask”) – is used to project the design directly onto the wafer. The full image may consist of many individual images (in stripe form). Typical types of “dynamic” or “programmable” masks are AOM, GLV, and DMD.

The Photolithography Process

Direct-write lithography uses a laser with light modulator to “write” the feature onto the surface. Any type of photolithographic process and resist can be used, opening up the entire world of photolithographic micro-structuring to the Maskless Lithography approach.

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