Optical proximity correction (OPC) and assist feature rules are generated using a process window (PW) analysis. A reference pitch is chosen and the mask bias is found that optimizes the process window. This can be done using standard process window analysis or through a weighted process window (WPW) analysis which accounts for focus and dose distributions that are expected in a real process. The WPW analysis gives not only the optimum mask bias, but also the center focus and dose conditions for the optimum process centering. A series of other pitches and mask biases are then analyzed by finding the common process window with the reference pitch. For the standard PW analysis, a common process window is found. For the WPW analysis, the WPW is computed at the center focus and dose conditions found for the reference pitch. If mask or lens errors are to be accounted for, then multiple structures can be included in the analysis. Once the common process windows for the mask features of interest have been computed, functional fits to the data can be found. Once the functional forms have been found for each of the OPC parameters, the rules table can be determined by solving for the spacings of interest in the design.

Method to determine optical proximity correction and assist feature rules which account for variations in mask dimensions

Masks can be repaired by creating a structure that is different from the original design, but that produces the same aerial image. For example, missing opaque material can be replaced by implanting gallium atoms to reduce transmission and quartz can be etched to an appropriate depth to produce the proper phase. In another aspect, a laser or other means can be used to remove an area of a mask around a defect, and then mask structures, either the intended design structures or alternate structures that produce the same aerial image, can be constructed using charged particle beam deposition and etching. For example, an electron beam can be used to deposit quartz to alter the phase of transmitted light. An electron beam can also be used with a gas to etch quartz to remove a layer including implanted gallium atoms. Gallium staining can also be reduced or eliminated by providing a sacrificial layer that can be removed, along with the implanted gallium atoms, using, for example, a broad ion beam. In another aspect, a charged particle beam can be programmed to etch a defect using three-dimensional information derived from two charged particle beams images of the defect from different angle.

Photolithography mask repair

A reticle inspection system for inspecting reticles can be used as an incoming inspection tool, and as a periodic and pre-exposure inspection tool. Mask shops can use it as an inspection tool compatible to their customers, and as a printable error detection tool. The inventive system detects two kinds of defects: (1) line width errors in the printed image; (2) surface defects. The line width errors are detected on the die area. The detection is performed by acquiring the image of the reticle under the same optical conditions as the exposure conditions, (i.e. wavelength, numerical aperture, sigma, and illumination aperture type) and by comparing multiple dies to find errors in the line width. Surface defects are detected all over the reticle. The detection of surface defects is performed by acquiring transmission and dark-field reflection images of the reticle and using the combined information to detect particles, and other surface defects.

Method and apparatus for reticle inspection using aerial imaging

A reticle inspection system and method for complete and fast inspection of phase shift mask reticles, both for incoming inspection and for periodic and pre-exposure inspection tool, is employable by facilities such as mask shops as an inspection tool compatible to the mask shop's customers. The inventive system and method detect phase errors in an aerial image by acquiring the image of the phase shift mask under the same optical conditions as the exposure conditions (i.e. wavelength, numerical aperture, sigma, and illumination aperture type). Images are acquired at a positive out-of-focus and a negative out-of-focus, and are compared in order to enhance possible phase error. The term “phase error” refers to the acceptable range of the phase deviation from the programmed 180° on the phase shift mask, by using the exposure system to achieve the image on the photoresist, satisfying the requirements of the wafer specification.

Alternating phase-shift mask inspection method and apparatus

An inspection apparatus comprising, a Rochon prism configured to branch the light transmitted through a half-wave plate, a first sensor and a second sensor for acquiring an optical image of a pattern of the sample, the branched light being incident to the first sensor and the second sensor, a light quantity acquisition unit configured to acquire a light quantity ratio (1:A) of the second sensor to the first sensor using the optical image, and to obtain an angle θ of the half-wave plate such that the light quantity ratio becomes A:1, an angle controller configured to receive information on the angle θ from the light quantity acquisition unit to control an angle of the half-wave plate, a light source controller configured to control a light quantity of the light source such that each of the light quantity values becomes a target value.

Inspection apparatus and inspection method

A new method for repairing pattern defect on a photo mask is provided. The method includes the steps of: (a) determining the irradiation area of the focused ion beam (FIB) directed towards a defect, by narrowing the irradiation area by a predetermined distance inwardly from the edge of the defect; (b) focusing the FIB onto its irradiation area to remove a part of the pattern film material of the defect from its top surface and thus leave a thin layer on a mask substrate; and (c) removing the thin layer by using a laser beam. The defect may be an isolated pattern or a pattern extended continuously from an edge of the normal pattern. Further, the photo mask repaired by the method, and a manufacturing method of semiconductor devices employing the repaired photo mask are proposed. The photo mask may include a phase shift mask.

Method for repairing pattern defect, photo mask using the method, and semiconductor device manufacturing method employing the photo mask

PROBLEM TO BE SOLVED: To provide the method for correcting defects in a mask by which a small amt. of ions is injected from focused ion beams to a light-transmitting substrate under a projection defect formed on a mask, the light-transmitting substrate around the projection defect is little etched, little damages are added on the mask by laser irradiation, changes in the image intensity caused by correction of the mask can be suppressed, and enough latitude for the wafer process can be obtd. SOLUTION: In the process for correcting a projection defect of a mask pattern film 3 on a mask 1 in this method for correcting mask defects, first, the projection defect is etched by converged ion beam gas assist etching or converged ion beam sputtering. In this process, all of the pattern film material in the part of the projection defect in contact with the pattern edge is removed, while the region of the projection defect in contact with the light-transmitting quartz substrate 2 is irradiated with a beam in such a manner that the irradiation region of the beam is controlled to be not larger than the projection defect region and that the pattern film is made to remain by controlling the focused ion beam not to reach just under the projection defect or the light transmitting substrate around the projection defect. Thus, a projection defect thin film 9 is formed and then the thin film 9 is removed by irradiation of laser light.

Asano Mitsuyo

Papers

Method for repairing pattern defect, photo mask using the method, and semiconductor device manufacturing method employing the photo mask

Method for correcting mask defect