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.

Method of preparing optically imaged high performance photomasks

Abstract: One principal embodiment of the disclosure pertains to a method of optically fabricating a photomask using a direct write continuous wave laser, comprising a series of steps including: applying an organic antireflection coating over a surface of a photomask which includes a chrome-containing layer; applying a chemically-amplified DUV photoresist over the organic antireflection coating; post apply baking the DUV photoresist over a specific temperature range; exposing a surface of the DUV photoresist to the direct write continuous wave laser; and, post exposure baking the imaged DUV photoresist over a specific temperature range. The direct write continuous wave laser preferably operates at a wavelength of 244 nm or 257 nm. In an alternative embodiment, the organic antireflection coating may be applied over an inorganic antireflection coating which overlies the chrome containing layer.

Fabrication of half-pitch 32nm resist patterns using near-field lithography with a-Si mask

Abstract: We evaluated the performances of Cr and amorphous Si (a-Si) films as light absorber materials for photomasks of near-field lithography on the basis of numerical studies using finite-difference time domain method and experimental results of fabrication process. With exposure experiments using both a Cr mask and an a-Si mask, fine performance of an a-Si near-field mask was demonstrated with respect to resolution. A half-pitch 32nm resist pattern of 120nm high was fabricated through the near-field lithography using the a-Si mask and a subsequent trilayer resist process.

Device for the fine adjustment of photomasks with respect to semiconductor elements

Abstract: In the manufacture of semiconductor devices with the aid of photomasks, the correct position of the photomask with respect to the semiconductor body to be processed is adjusted by the use of rod-shaped electromechanical transducers which are connected to the photomask and which, when energized vary their length and so displace the photomask in relation to the semiconductor body.

Layout design methodologies for sub-wavelength manufacturing

Abstract: In this paper, we describe new types of layout design constraints needed to effectively leverage advanced optical wafer lithography techniques. Most of these constraints are dictated by the physics of advanced lithography processes, while other constraints are imposed by new photomask techniques. Among the methods discussed are (1) phase shift mask (PSM) lithography in which phase information is placed on the photomask in combination with conventional clear and dark information; (2) optical proximity correction (OPC) where predictable distortions in feature geometry are corrected by putting an inverse distortion on the mask; (3) off-axis illumination optics that improve resolution of some configurations at the expense of others; and (4) use of non-resolving assist features that improve neighboring structures.

High-numerical aperture extreme ultraviolet scanner for 8-nm lithography and beyond

Abstract: Current extreme ultraviolet (EUV) projection lithography systems exploit a projection lens with a numerical aperture (NA) of 0.33. It is expected that these will be used in mass production in the 2018/2019 timeframe. By then, the most difficult layers at the 7-nm logic and the mid-10-nm DRAM nodes will be exposed. These systems are a more economical alternative to multiple-exposure by 193 argon fluoride immersion scanners. To enable cost-effective shrink by EUV lithography down to 8-nm half pitch, a considerably larger NA is needed. As a result of the increased NA, the incidence angles of the light rays at the mask increase significantly. Consequently, the shadowing and the variation of the multilayer reflectivity deteriorate the aerial image contrast to unacceptably low values at the current 4× magnification. The only solution to reduce the angular range at the mask is to increase the magnification. Simulations show that the magnification has to be doubled to 8× to overcome the shadowing effects. Assuming that the mask infrastructure will not change the mask form factor, this would inevitably lead to a field size that is a quarter of the field size of the current 0.33-NA step and scan systems and reduce the throughput (TPT) of the high-NA scanner to a value below 100 wafers per hour unless additional measures are taken. This paper presents an anamorphic step and scan system capable of printing fields that are half the field size of the current full field. The anamorphic system has the potential to achieve a TPT in excess of 150 wafers per hour by increasing the transmission of the optics, as well as increasing the acceleration of the wafer stage and mask stage. This makes it an economically viable lithography solution.