Photomask

About: Photomask is a research topic. Over the lifetime, 7917 publications have been published within this topic receiving 54524 citations. The topic is also known as: photoreticle & reticle.

Mechanized retractable pellicles and methods of use

Abstract: Apparatus and methods to protect a photomask that is used for semiconductor photolithography at wavelengths outside the visible spectrum include a pellicle that is readily retracted during exposure or to provide access to the photomask. The pellicle can be transparent at an inspection wavelength and opaque at an exposure wavelength. In various embodiments, the pellicle is slid, retracted, or pivoted relative to a base aligned with the photomask, thus uncovering the photomask. When overlying the photomask, the pellicle can be secured with magnetic elements, such as magnets or electromagnets. In another embodiment, the pellicle includes a diaphragm having a plurality of shutter leaves that can be opened or closed. Methods of using a pellicle are also described.

Transmittance modulation photomask, process for producing the same, and process for producing diffraction gratings using the same

Abstract: The present invention provides a process for producing a blazed diffraction grating by using a transmission modulation diffraction grating as a photomask in photolithography. The photomask is composed of a relief modulation diffraction grating (A) made of a transparent material and a blazed diffraction grating (B) made of a material containing a ray absorbing agent. The diffraction grating (A) and the diffraction grating (B) are mated with each other through their grating surfaces.

MOEMS-based lithography for the fabrication of micro-optical components

Abstract: We present a new method for the fabrication of diffractive and refractive micro-optical components. The method is suitable for high-quality rapid prototyping of optical components and allows the fast experimental test of designs for computer-generated holograms or refractive microstructures. Our method is based on employing a digital-multimirror device (DMD) as a switchable projection mask. The DMD is imaged into a photoresist layer using a Carl Zeiss lithography objective with a demagnification of 10:1 and a numerical aperture of 0.32 on the image side. The resulting pixel size is 1.368×1.368 µm. In comparison with laser direct writing with a single spot, our method is a parallel processing of nearly 800,000 pixels (1024×768 pixels). This fabrication method can be applied to all MOEMS components. The method adds a new dimension in MOEMS processing, reducing the fabrication complexity, and improves the flexibility of process simulation and design.

Issues and method of designing lenses for optical lithography

Abstract: A variety of technologies to improve optical performance in photolithography are surveyed. The technologies are classified according to which component of the optics they work on: the source, the mask, the pupil, or the image. Emphasis is put on, first, the advantages and disadvantages of annular illumination, which are studied by lithography simulation. Second, a polarized mask is proposed. The effect of polarization on imaging, which has not been explored yet, is studied and the result is that TE polarization produces images of the best quality. Third, as a part of pupil function, aberration optimization is discussed. The conclusion is that positive spherical aberration is suitable for projection optics.