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.

Plasma etching apparatus

Abstract: PURPOSE:To prevent the irregularity of a dimension, by a method wherein the resist surface of a photomask is irradiated with monochromatic light during discomposition and the decrease of the resist film by discomposition is measured from the amount of reflected light. CONSTITUTION:A photomask 2 provided with a resist pattern is placed to the center of the treating tank for discomposition and plasma is generated from a high frequency power source 3. The resist film of the photomask is irradiated with light 5 at an arbitrary angle theta from a monochromatic light source 4 such as He-Ne laser. Reflected light is received by a light receiving element 7 such as photomultiplier to be converted to an electric signal. By this method, the irregularity of a dimension by discomposition is prevented.

Simple multi-level microchannel fabrication by pseudo-grayscale backside diffused light lithography

Abstract: Photolithography of multi-level channel features in microfluidics is laborious and/or costly. Grayscale photolithography is mostly used with positive photoresists and conventional front side exposure, but the grayscale masks needed are generally costly and positive photoresists are not commonly used in microfluidic rapid prototyping. Here we introduce a simple and inexpensive alternative that uses pseudo-grayscale (pGS) photomasks in combination with backside diffused light lithography (BDLL) and the commonly used negative photoresist, SU-8. BDLL can produce smooth multi-level channels of gradually changing heights without use of true grayscale masks because of the use of diffused light. Since the exposure is done through a glass slide, the photoresist is cross-linked from the substrate side up enabling well-defined and stable structures to be fabricated from even unspun photoresist layers. In addition to providing unique structures and capabilities, the method is compatible with the “garage microfluidics” concept of creating useful tools at low cost since pGS BDLL can be performed with the use of only hot plates and a UV transilluminator: equipment commonly found in biology labs. Expensive spin coaters or collimated UV aligners are not needed. To demonstrate the applicability of pGS BDLL, a variety of weir-type cell traps were constructed with a single UV exposure to separate cancer cells (MDA-MB-231, 10–15 μm in size) from red blood cells (RBCs, 2–8 μm in size) as well as follicle clusters (40–50 μm in size) from cancer cells (MDA-MB-231, 10–15 μm in size).

Photomask, photoresist and photolithography for a monolithic IC

Abstract: A method for making a three dimensional structure of the aperture in a photoresist layer on a semiconductor substrate by differentiating dose of exposure light between parts of a photoresist layer. One example of the three dimensional structure is an overhang-platform structure; that is, one side wall of a narrow aperture has an overhang and the opposite side wall has a platform. By separately forming one photoresist layer segment having the overhang wall and the other photoresist layer segment having the platform wall, the distance between the edges of the overhang and the platform can be made smaller than the resolution limit of the photoresist material, which enables making a path line on a substrate whose width is smaller than the resolution limit. Many types of photoresist layers and photomasks for producing such photoresist layers are disclosed.

Patterned mask inspection technology with projection electron microscope technique on extreme ultraviolet masks

Abstract: High-sensitivity extreme ultraviolet (EUV) mask pattern defect detection is one of the major issues remaining to be addressed in device fabrication using extreme ultraviolet lithography. In order to achieve inspection sensitivity and suitability for the 1× nm node, a projection electron microscope (PEM) system is employed that enables high-speed/high-resolution inspection, which is not possible using conventional deep ultraviolet or electron beam inspection systems. By employing higher electron energy in the electron optics (EO) exposure system and by improving the PEM design, we have minimized the aberration that occurs when working with EO systems and we have improved the transmittance of the system. Experimental results showing the improved transmittance were obtained by making electron throughput measurements. To guarantee the tool’s aptness for 16-nm node EUV mask inspection, corresponding sized programmed defects on masks were designed, and the defect detection sensitivity of the EO system was evaluated. Improvements in image resolution and electron throughput have enabled us to detect 16-nm sized defects. The PEM system was integrated into a pattern inspection system for defect detection sensitivity evaluation.

Investigation of reticle defect formation at DUV lithography

Abstract: Defect formation on advanced photomasks used for DUV lithography has introduced new challenges at low k 1 processesindustry wide. Especially at 193-nm scanner exposure, the mask pattern surface, pellicle film and the enclosed spacebetween the pellicle and pattern surface can create a highly reactive environment. This environment can becomesusceptible to defect growth during repetitive exposure of a mask on DUV lithography systems due to the flow of highenergy through the mask. Due to increased number of fields on the wafer, a reticle used at a 300-mm wafer fab receivesroughly double the number of exposures without any cool down period, as compared to the reticles in a 200-mm waferfab. Therefore, 193-nm lithography processes at a 300-mm wafer fab put lithographers and defect engineers into an areaof untested mask behavior. During the scope of this investigation, an attenuated phase shift mask (attPSM) wasperiodically exposed on a 193-nm scanner and the relationship between the number of exposures (i.e., energy passedthrough the mask during exposures) versus defect growth was developed. Finally, chemical analysis of these defectswas performed in order to understand the mechanism of this “growth”.Keywords : DUV, PSM, mask contamination, mask, crystal-growth, Cyanuric acid, pellicle, 193nm, scanner, STARlight