Modern UV-lithography is searching for new highly parallel writing concepts. Spatial light modulation (SLM) offers such possibilities but special emphasis must be put on the ability of SLM devices to handle ultraviolet light (UV). We designed and fabricated micromirror arrays which fulfill these requirements. Possible applications for such UV-SLMs are direct writing systems for semiconductor and printing, and UV-stimulated biochemistry. For deep UV laser pattern generation (248 nm) e.g. we designed and fabricated a 2048x512 pixel UV-SLM with individually addressable aluminum micromirrors. They are illuminated by an excimer laser pulse and imaged onto a photomask substrate. A complete pattern is stitched together at a rate of 1 kHz. The minimum feature size is 320 nm and analog modulation of the pixels allows to realize an address grid of only 1.6 nm. The design of the array is modular so that other array sizes can be tailor made to customers needs. Design and fabrication aspects for a CMOS compatible realization of these micromirror arrays are addressed as well as their performance in lithography applications.

The Fraunhofer Institute for Photonic Microsystems (IPMS) has been developing and manufacturing micromirror arrays for more than 20 years. While originally focusing on applications related to microlithography and therefore mainly for light in the deep ultraviolet range, the range of applications has been expanded since, including applications in the visible and near-infrared range. This paper gives an overview of the devices and their designs, fabrication, and characterization.

We describe charging effects on spatial light modulators (SLM). These light modulators consist of up to one million mirrors that can be addressed individually and are operated at a frame rate of up to $2kHz$. They are used for deep ultraviolet (DUV) mask writing where they have to meet very high requirements with respect to accuracy. To be usable in a mask-writing tool, the chips have to be able to work under DUV light and maintain their performance with high accuracy over a long period of time. Charging effects are a problem frequently encountered with MEMS, especially when they are operated in an analog mode. In this work, the issue of charging effects in SLMs used for microlithography, their causes and methods of their reduction or elimination, by means of addressing methods as well as technological changes, is discussed. The first method deals with the way charges can accumulate within the actuator. It is a simple method that requires no technological changes but cannot always be implemented. The second involves the removal of the materials within the actuator where charges can accumulate.

Nowadays, virtual, augmented and mixed reality applications are becoming more and more widespread. With this, the requirements for image quality are getting more demanding, leaving room for improvement of the user experience of the existing systems. While many research groups and companies try to improve on fixed-focus stereo image systems, we propose to make use of real holography as the best possible solution providing all depth cues automatically in a consistent way. Within such holographic display systems, a spatial light modulator (SLM) is re-shaping the incident light generating the desired images. As SLMs with the required properties are not commercially available today, a novel device is being developed within the Horizon 2020 ’REALHOLO’ project funded by the European Union: a MEMS micromirror Array (MMA) with 8 million phase-shifting pixels based on a novel comb drive micro actuator concept. Earlier theoretical work and simulations had showed clear perspectives for a superior performance in comparison to other SLM technologies allowing high frame rates and high precision wave front modulation. By now the first samples of proof-of-concept MMA chips have been fabricated and in this paper we present experimental characterization results: microscope and SEM images, quasi-static response curves measured by white light interferometry (WLI) as well as the dynamic properties like resonance frequency and damping measured by laser doppler vibrometry (LDV). In addition an addressing approach for a minimum mirror settling time is also investigated. We discuss the impact of fabrication tolerances on the overall precision together with the response curve dependency on design parameters and compare the experimental results to simulations.

Increased spatial resolution and revisit time of payloads operating in the infrared spectral region can offer unprecedented advantages to Earth Observation. This, however, poses several technological challenges, such as large array detector availability and data bandwidth. In this paper, we present a super-resolved demonstrator—based on a compressive sensing architecture—which is being developed to address enhanced performance in terms of at-ground spatial resolution, on-board data processing and encryption functionalities for Earth Observation payloads. The demonstrator’s architecture is here presented, together with its working principle, main features and the approach used for image reconstruction.

We discuss the process integration to manufacture a spatial light modulator (SLM) device for application in mixed and augmented reality. The MEMS-part of the device is integrated on an external 180nm CMOS. The SLM consists of an 8MPixel micro mirror array with a pixel size of 4μm x 6μm. To provide the vertical strokes necessary for RGB color image generation, a comb-drive actuator concept was developed. Besides the yoke and the stator of the comb-drive, the actuator uses a double spring structure to reduce tilting of the mirror and other stress-induced effects. At the beginning of the product development we used iLine-lithography only, while later for the final device we switched to KrF-lithography to provide the necessary feature size down to 200nm as well as better CD-uniformity and overlay specification. We describe the process development, with focus on the lithography and etching processes for the actuator. Especially the different processes for patterning the Titanium-Aluminum structures of ultra-thin springs as well as the yoke and the stator with their high aspect ratios, which are specific for MEMS processing. Finally we achieved post-etch CD-uniformity <10nm per wafer for all metal structures as well on-product-overlay accuracy <15nm.