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.

Actinic imaging of native and programmed defects on a full-field mask

Abstract: Actinic imaging of native and programmed defects on a full-field mask 1. Mochi*a, K. A. Goldberg a, B. La Fontaine b , A. Tchikoulaeva b , C. Holfeld c aLawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA, 94720, USA. bGlobal Foundries, 1050 Arques Avenue, Sunnyvale, CA, 94085, USA cGlobal Foundries Dresden Module One. KG Wilschdorfer Landstr. 101,0 1109 Dresden, Germany. ABSTRACT We describe the imaging and characterization of native defects on a full field extreme ultraviolet (EUV) mask, using several reticle and wafer inspection modes. Mask defect images recorded with the SEMA TECH Berkeley Actinic Inspection Tool (AIT), an EUV-wavelength (13.4 nm) actinic microscope, are compared with mask and printed-wafer images collected with scanning electron microscopy (SEM) and deep ultraviolet (DUV) inspection tools. We observed that defects that appear to be opaque in the SEM can be highly transparent to EUV light, and inversely, defects that are mostly transparent to the SEM can be highly opaque to EUV. The nature and composition of these defects, whether they appear on the top surface, within the multilayer coating, or on the substrate as buried bumps or pits, influences both their significance when printed, and their detectability with the available techniques. Actinic inspection quantitatively predicts the characteristics of printed defect images in ways that may not be possible with non- EUV techniques. As a quantitative example, we investigate the main structural characteristics of a buried pit defect based on EUV through- focus imaging. Keywords: Mask inspection, defects, extreme ultraviolet, EUV, actinic, lithography, microscopy 1. INTRODUCTION Mask defectivity is one of the main issues for advanced lithography in any future technology node. This is especially true for EUV lithography where the mask, the absorber pattern, and the various types of defects can have wavelength- specific optical properties. Developing reliable and accurate methods for defect inspection and imaging is an essential step towards the deployment ofEUV lithography. While DUV microscopy and SEM provide valuable information at high resolutions, their sensitivity to defects can be remarkably different from EUV-wavelength imaging, and they cannot guarantee measurements that predict EUV printing performance. Our research shows that some defects that are strongly evident in an SEM will not actually print, while others, which are faintly detected with SEM or DUV inspection, can clearly appear on the wafer. Aside from printing in photoresist, EUV aerial imaging is the only technique that provides quantitative information on the interaction between the EUV light and the blank or patterned mask surface. Following exposure in the ASML Alpha Demo Tool (ADT) at CNSE in Albany [I], New York, the reticle and its printed wafers were inspected using SEM and two KLA tools: the 2800 Series broadband and brightfield DUV/uVIVIS inspection platform and the TeraScanHR 587 reticle defect inspection system [2]. A classification system presented previously [3] separated the defects into the following categories: cleaning residue, particle, pattern defect, blank defects, and nuisance defects. In this paper we describe the imaging of native defects on a EUV mask from Global Foundries, carried out using the AIT [4], an EUV Fresnel zoneplate microscope dedicated to photomask research [5]. EUV imaging, performed with the AlT, adds new information about the optical properties of these reticle defects. Our goal was to investigate the relationship between the appearance of various defects in the different defect-imaging tools. Our observations show that it is difficult to predict the EUV response from the SEM or DUV appearance. By studying the through focus evolution of a defect's aerial image, with quantitative comparison to simulated defect images, it is possible to investigate physical characteristics (such as the apparent defect height and three-dimensional

Method for repairing photomask by removing residual defect in said photomask

Abstract: A method for repairing a photomask by removing a residual defect in the photomask is provided which can solve problems, involved in repair of the photomask by the conventional laser beam irradiation, such as various types of maladjustments, limitation of focusing of a laser beam, creation of roughening in the repaired area, and problems, involved in repair of the photomask by focused ion beam irradiation, such as damage to a transparent substrate and a gallium stain. The method comprises the steps of: (a) applying actinic radiation to the residual defect area to remove the residual defect except for a defect edge region having a predetermined width from the periphery of the residual defect area over the whole periphery of the residual defect area; and (b) removing the defect edge region, remaining unremoved by the physical means, having a predetermined width from the periphery of the residual defect area over the whole periphery of the residual defect area by chemical etching with a chemical, the predetermined width being such that the influence of the actinic radiation does not extend over the outside of the residual defect area and, at the same time, the etching time can be set so that the region having a predetermined width from the periphery is removed by the chemical etching without any substantial influence on other layers including a light-shielding layer.

Fabrication techniques of high aspect ratio vertical lightpipes using a dielectric photomask

Abstract: We report the development of new fabrication techniques for creating high aspect ratio optical lightpipes in SiO 2 layers of 10μm thickness and above. A dielectric photo mask was used for deep reactive ion etching. Our experiments show that CF 4 -based reaction gases were best for deep etching with high selectivity and etch rate. Trenches with diameters or width of 1.5μm were demonstrated, with an aspect ratio of 7.2:1 and a sidewall angle of 87.4 degrees. We also present the lift-off process of the etch masks and the via-filling procedures for the lightpipes. These structures are useful for image sensors, vertical interconnect and waveguiding applications.

Apparatus for inspecting mask used for manufacturing integrated circuits

Abstract: @ A mask inspection apparatus is arranged to compare a measured data signal obtained by optically measuring a photomask with a design data signal representing an integrated circuit pattern so as to inspect defects of the photomask on which the integrated circuit pattern is drawn. To inspect the pattern area and its peripheral area of the mask in one step, a reference signal generator (48) in the mask inspection apparatus is arranged to generate a reference signal containing a predetermined additional data signal representing the peripheral area of the integrated circuit pattern, in addition to the design data signal representing the integrated circuit pattern. The reference signal is compared with the measured data signal of the pattern area and its peripheral area from a signal detector (43) by a defect detector (47).

Photomask blank and photomask

Abstract: PROBLEM TO BE SOLVED: To provide a photomask blank excellent in chemical resistance that can suppress changes in the optical characteristics of a chromium-based antireflection film by chemical cleaning. SOLUTION: The photomask blank has a light-shielding film1 3 and an antireflection film 14, consisting mainly of chromium, on a transparent substrate 11. The composition in the surface region of the antireflection film 14 comprises 3 to 30 atom% of nitrogen content, and 50 to 65 atom% of total content of nitrogen and oxygen, and the surface region is specified to a depth of 3 nm or larger, preferably 5, nm or larger. In the surface region of the antireflection film 14, appropriate amount of oxygen and nitrogen is contained, thereby the film has functions as an antireflection film. By controlling the nitrogen content to the aforementioned range and controlling the total content of nitrogen and oxygen to be 50 atom% or higher, chemical resistance of the surface of the antireflection film 14 is improved. The content of nitrogen and oxygen is controlled to be 65% or lower so as to suppress degradation in the cross-sectional profile, at patterning. COPYRIGHT: (C)2007,JPO&INPIT