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EP-4095600-B1 - PELLICLE FRAME, PELLICLE, EXPOSURE ORIGINAL PLATE WITH PELLICLE, EXPOSURE METHOD, AND SEMICONDUCTOR OR LIQUID-CRYSTAL-DISPLAY MANUFACTURING METHOD

EP4095600B1EP 4095600 B1EP4095600 B1EP 4095600B1EP-4095600-B1

Inventors

  • NISHIMURA, AKINORI

Dates

Publication Date
20260506
Application Date
20210115

Claims (13)

  1. A pellicle frame (10) in a rectangular shape having straight sides (10a) and corners (10b), having an outer peripheral surface portion (10c), which is in entirety or in part streamline shaped, wherein the streamline shape is a curvilinear or bowed shape in a cross-section perpendicular to a length direction of the straight side, wherein the outer peripheral surface portion (10c) is shaped such that its width (b) gradually decreases from one side adapted to be mounted on an exposure original plate to the other side adapted to bear a pellicle film, and the width (b) of the outer peripheral surface portion (10c) of a streamline shape, which is a curvilinear or bowed shape, is at least 50% of the height of the pellicle frame (H), and wherein a width (w) of the pellicle frame on the one side is greater than a width (B) of the pellicle frame on the other side.
  2. A pellicle frame (10) of claim 1 which constructs a photolithography pellicle.
  3. The pellicle frame (10) of claim 1 or 2 wherein the streamline shape is arcuate.
  4. The pellicle frame (10) of claim 1 or 2 wherein the width (B) of the pellicle frame on the other side is up to 60% of the width (w) of the pellicle frame on the one side.
  5. A pellicle comprising the pellicle frame of claim 1 or 2 and a pellicle film.
  6. The pellicle of claim 5 wherein the pellicle film has a thickness of up to 500 nm.
  7. A pellicle-covered exposure original plate comprising an exposure original plate and the pellicle of claim 5 mounted thereon.
  8. An exposure method comprising a step of exposing a substrate to radiation through the pellicle-covered exposure original plate of claim 7.
  9. The exposure method of claim 8 wherein the substrate is exposed at a scanning speed of at least 300 mm/s.
  10. A method for manufacturing a semiconductor device comprising a step of exposing a substrate to radiation through the pellicle-covered exposure original plate of claim 7.
  11. The method of claim 10 wherein in the exposure step, the substrate is exposed at a scanning speed of at least 300 mm/s.
  12. A method for manufacturing a liquid crystal display comprising a step of exposing a substrate to radiation through the pellicle-covered exposure original plate of claim 7.
  13. The method of claim 12 wherein in the exposure step, the substrate is exposed at a scanning speed of at least 300 mm/s.

Description

TECHNICAL FIELD This invention relates to a pellicle frame, pellicle, pellicle-covered exposure original plate and exposure method, and method for manufacturing a semiconductor device or liquid crystal (LC) display. BACKGROUND ART The method for manufacturing semiconductor devices or LC displays includes the photolithography step of irradiating light to resist-coated semiconductor wafers or LC matrices to print patterns. If dust is deposited on photomasks and reticles (referred to as photomask, hereinafter) used herein, the dust absorbs or deflects light, raising such problems that the transferred pattern can be deformed or roughened at the edge, and the background be stained black, detracting from size, quality, appearance and other factors. Although these photolithography steps are generally performed in a cleanroom, it is yet difficult to always maintain the exposure original plate clean. It is thus a common practice to attach a dust cover, known as pellicle, to the exposure original plate before exposure. The pellicle is basically constructed as comprising a frame-shaped pellicle frame, a pellicle film extended on the upper end surface of the pellicle frame, and a gas-tight gasket formed on the lower end surface of the pellicle frame. The pellicle film is composed of a material having a high transmittance to exposure radiation. A pressure-sensitive adhesive (PSA) is used as the gas-tight gasket. When the pellicle is placed on the photomask, contaminants do not deposit directly on the photomask, but on the pellicle. If a focus is set on the pattern of the photomask during photolithography transfer, the contaminants on the pellicle do not participate in the transfer, avoiding such problems as pattern deformation. The photolithography technology encounters an advance to modify the exposure light source toward shorter wavelength as the means for enhancing resolution. Until the present, the exposure light source makes a transition from g-line (436 nm) and i-line (365 nm) of mercury lamps to KrF excimer laser (248 nm). In recent years, the ArF excimer laser (193 nm) is most often used when micropatterning is necessary. In the recent efforts for implementing further microprocessing using ArF excimer laser, an immersion exposure tool is used. The exposure tool is given a higher numerical aperture (NA) by filling a liquid between the objective lens and a silicon wafer in the tool whereby a higher resolution is achieved. With such an increase of NA of the exposure tool, the light transmitted by the pellicle has an increased angle of oblique incidence in a peripheral portion. The transmittance of the pellicle is generally set such that a maximum transmittance is available with respect to perpendicular incident light. There is observed a phenomenon that the transmittance lowers as the incident angle becomes larger. The extent of transmittance lowering becomes more outstanding as the pellicle film becomes thicker. For obtaining a high transmittance relative to oblique incident light, it is a common practice to reduce the thickness of a pellicle film. However, reducing the thickness of a pellicle film raises the problem that the strength of the film is concomitantly lowered. Specifically, since the photomask unit assembled by attaching a pellicle to a photomask substrate undergoes high-speed scanning motion in the exposure step, a pellicle film having a low strength is susceptible to vibration under the influence of turbulent flow during high-speed scanning motion. That is, as the pellicle film vibrates, the exposure light tends to be disturbed upon passage through the pellicle film. The pattern is shifted from the original plately intended position, with a possibility that the positional accuracy or overlay of the pattern is aggravated. Of the prior art technology associated with the overlay improving process, the following patent documents are exemplary. PRIOR ART DOCUMENTS PATENT DOCUMENTS Patent Document 1: JP-A 2018-508048Patent Document 2: WO 2012/080008Pellicle frames are disclosed in JP 2010 102357 A, US 2018/0180991 A1, JP 2005 308901 A, US 2005/0140949 A1 and JP 2001 109135 A. The latter document shows a rectangular pellicle frame with different shapes of the frame in cross-section. SUMMARY OF INVENTION TECHNICAL PROBLEM An object of the invention, which has been made under the above-mentioned circumstances, is to provide a pellicle frame which can suppress turbulent flow which is likely to occur upon high-speed scanning motion, mitigate the vibration of a pellicle film upon high-speed scanning motion during exposure, and restrain any overlay aggravation; a pellicle using the same, pellicle-covered exposure original plate and exposure method, and method for manufacturing a semiconductor device or LC display. SOLUTION TO PROBLEM Making extensive investigations to solve the outstanding problems, the inventor has found that by tailoring an outer peripheral portion of a pellicle frame to a specific streamline s