US-12620545-B2 - Blanking aperture array system and multi charged particle beam writing apparatus

US12620545B2US 12620545 B2US12620545 B2US 12620545B2US-12620545-B2

Abstract

In one embodiment, a blanking aperture array system includes a blanking aperture array substrate provided blankers corresponding to each beam of a multi beam, a first radiation shield, and a second radiation shield. A circuit section applying a voltage to the blankers is disposed closer to a peripheral edge than a cell section including the blankers. The first radiation shield includes a first plate covering over the circuit section, disposed on an upper surface of the blanking aperture array substrate, and extending from a peripheral edge of a first opening for passage of the multi beam. The second radiation shield covers under the circuit section, and includes a lower peripheral wall section that hangs down from a lower surface of the blanking aperture array substrate and surrounds the cell section, and a lower plate extending from a peripheral edge of a lower opening for passage of the multi beam.

Inventors

Shuji Yoshino

Assignees

NUFLARE TECHNOLOGY, INC.

Dates

Publication Date: 20260505
Application Date: 20231009
Priority Date: 20221201

Claims (14)

1 . A blanking aperture array system comprising: a blanking aperture array substrate including a plurality of beam passage holes, through which beams in a multi charged particle beam pass from upstream to downstream, the plurality of beam passage holes being provided with respective blankers that perform blanking deflection on the beams; a first radiation shield disposed upstream of the blanking aperture array substrate; and a second radiation shield disposed downstream of the blanking aperture array substrate, wherein a cell section including the beam passage holes and the blankers is provided in a central part of the blanking aperture array substrate, and a circuit section including a circuit element that applies a voltage to each of the blankers is disposed closer to a peripheral edge of the blanking aperture array substrate than the cell section, the first radiation shield includes a first plate covering over the circuit section, disposed on an upper surface of the blanking aperture array substrate, provided with a first opening for passage of the multi charged particle beam, and extending from a peripheral edge of the first opening, and the second radiation shield covers under the circuit section, and is provided with a lower opening for passage of the multi charged particle beam, the second radiation shield including a lower peripheral wall section that hangs down from a lower surface of the blanking aperture array substrate and surrounds the cell section, and a lower plate extending from a peripheral edge of the lower opening.
2 . The blanking aperture array system according to claim 1 , wherein the lower peripheral wall section surrounding the cell section is disposed in each of a region between the cell section and the circuit section of the blanking aperture array substrate, and a region between the cell section and an end of the blanking aperture array substrate, and the circuit section provided in a lower surface of the blanking aperture array substrate is located in a space formed by the lower peripheral wall section and the lower plate.
3 . The blanking aperture array system according to claim 1 , wherein the first radiation shield further includes a second plate that is disposed above the first plate, provided with a second opening for passage of the multi charged particle beam, and extends from a peripheral edge of the second opening, a first peripheral wall section stands upright from a peripheral edge of the first opening of the first plate, a second peripheral wall section hangs down from a peripheral edge of the second opening of the second plate, and an upper portion of the first peripheral wall section and a lower portion of the second peripheral wall section are connected in a fitting manner.
4 . The blanking aperture array system according to claim 1 , wherein the lower plate is continuous to a lower portion of the lower peripheral wall section, and disposed away from the lower surface of the blanking aperture array substrate.
5 . The blanking aperture array system according to claim 4 , wherein the lower peripheral wall section includes: a third peripheral wall section that hangs down from the lower surface of the blanking aperture array substrate, and surrounds the cell section; and a fourth peripheral wall section that stands upright from a peripheral edge of the lower opening of the lower plate, and a lower portion of the third peripheral wall section and an upper portion of the fourth peripheral wall section are connected in a fitting manner.
6 . The blanking aperture array system according to claim 5 , further comprising a cap member that is disposed in outer peripheral surfaces of the third peripheral wall section and the fourth peripheral wall section, and seals a gap between the lower portion of the third peripheral wall section and the upper portion of the fourth peripheral wall section.
7 . The blanking aperture array system according to claim 1 , wherein a lower surface of the first plate and the upper surface of the blanking aperture array substrate are in close contact with each other.
8 . The blanking aperture array system according to claim 5 , wherein a lower surface of the first plate and the upper surface of the blanking aperture array substrate are bonded with adhesives, and an upper surface of the third peripheral wall section and the lower surface of the blanking aperture array substrate are bonded with adhesives.
9 . The blanking aperture array system according to claim 3 , further comprising a mounting substrate disposed between the first plate and the second plate, wherein the circuit section is provided in the lower surface of the blanking aperture array substrate, and connected to the mounting substrate by wire bonding.
10 . The blanking aperture array system according to claim 3 , wherein a hanging-down piece that hangs down from a lower surface of the second plate outside the blanking aperture array substrate, and a standing-upright piece that stands upright from an upper surface of the lower plate seal between the second plate and the lower plate.
11 . The blanking aperture array system according to claim 10 , wherein a lower portion of the hanging-down piece and an upper portion of the standing-upright piece are connected in a fitting manner.
12 . The blanking aperture array system according to claim 3 , wherein a non-magnetic metal material is disposed between a lower surface of the second plate and an upper surface of the lower plate, and outside the blanking aperture array substrate.
13 . The blanking aperture array system according to claim 1 , wherein the first radiation shield and the second radiation shield are composed of heavy metal.
14 . A multi charged particle beam writing apparatus comprising: a charged particle beam source that emits a charged particle beam; a shaping aperture array substrate including a plurality of openings, and forming a multi charged particle beam by part of the charged particle beam passing through the plurality of openings from upstream to downstream; a blanking aperture array substrate including a plurality of beam passage holes, through which beams in the multi charged particle beam pass from upstream to downstream, the plurality of beam passage holes being provided with respective blankers that perform blanking deflection on the beams; a first radiation shield disposed upstream of the blanking aperture array substrate; and a second radiation shield disposed downstream of the blanking aperture array substrate, wherein a cell section including the beam passage holes and the blankers is provided in a central part of the blanking aperture array substrate, and a circuit section including a circuit element that applies a voltage to each of the blankers is disposed closer to a peripheral edge of the blanking aperture array substrate than the cell section, the first radiation shield includes a first plate covering over the circuit section, disposed on an upper surface of the blanking aperture array substrate, provided with a first opening for passage of the multi charged particle beam, and extending from a peripheral edge of the first opening, and the second radiation shield covers under the circuit section, and is provided with a lower opening for passage of the multi charged particle beam, the second radiation shield including a lower peripheral wall section that hangs down from a lower surface of the blanking aperture array substrate and surrounds the cell section, and a lower plate extending from a peripheral edge of the lower opening.

Description

CROSS REFERENCE TO RELATED APPLICATION This application is based upon and claims benefit of priority from the Japanese Patent Application No. 2022-192962, filed on Dec. 1, 2022, the entire contents of which are incorporated herein by reference. FIELD The present invention relates to a blanking aperture array system and a multi charged particle beam writing apparatus. BACKGROUND With high integration of semiconductor integrated circuits (LSI), the design dimensions of semiconductor device (MOSFET: metal-oxide semiconductor field-effect transistor) are still being miniaturized according to Moore's Law. Lithography to achieve the miniaturization is an extremely important technique to generate a pattern in a semiconductor manufacturing process. In order to form a desired LSI circuit pattern on a wafer, as a mainstream technique, a highly accurate original pattern (a mask, or also called reticle when particularly used in a stepper or a scanner) formed on a quartz is reduced and transferred onto a resist (photosensitive resin) coated on the wafer using a reduction projection exposure apparatus. Nowadays, in leading edge fine pattern formation, EUV scanners using extreme ultraviolet (EUV) rays as a light source are also being adopted. In EUV exposure, an EUV mask is used, which is obtained by patterning, on a quartz, a multi-layer film for reflecting EUV, and an absorber further formed over the multi-layer film. Either mask is manufactured using an electron beam writing apparatus that essentially applies an electron beam with a high resolution. A writing apparatus that uses a multi-beam can emit many beams at one time, as compared to when writing is performed with a single electron beam, thus the throughput can be significantly improved. In a multi-beam writing apparatus using a blanking aperture array substrate, as an embodiment of the multi-beam writing apparatus, an electron beam emitted from an electron source passes through a shaping aperture array substrate having a plurality of openings to form a multi-beam (a plurality of electron beams). The multi-beam passes through corresponding blankers of the blanking aperture array substrate. The blanking aperture array substrate has electrode pairs (blankers) each for independently deflecting a beam, and an opening for beam passage between each electrode pair, and blanking deflection is independently performed on a passing electron beam by fixing one of an electrode pair to the ground potential and switching the other electrode between the ground potential and another potential. An electron beam deflected by a blanker is blocked by the limiting aperture, and an electron beam not deflected by a blanker is emitted onto a sample. The blanking aperture array substrate is equipped with a circuit to independently control the electrode potential of each blanker. When an electron beam is emitted to a shaping aperture array substrate provided with openings to form a multi-beam, bremsstrahlung X-rays are generated. In addition, when a multi-beam is formed by a shaping aperture array substrate, part of the electron beams is scattered at the edges of openings, producing scattered electrons. When the bremsstrahlung X-rays and/or the scattered electrons are emitted to the blanking aperture array substrate, the electrical characteristics of MOSFETs included in a circuit device may deteriorate due to total ionizing dose (TID) effect, and improper functioning of the circuit device may be caused. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of a multi charged particle beam writing apparatus according to an embodiment of the present invention. FIG. 2 is a plan view of a shaping aperture array substrate. FIG. 3 is a schematic configuration view of a blanking aperture array system. FIG. 4 is a plan view of a blanking aperture array substrate. FIG. 5 is a cross-sectional perspective view of a first radiation shield. FIG. 6A, FIG. 6B, FIG. 6C are views illustrating examples of a fitting structure. FIG. 7 is a schematic configuration view of a blanking aperture array system according to a modification. FIG. 8 is a partially enlarged view of a blanking aperture array system. FIG. 9 is a partially enlarged view of a blanking aperture array system. FIG. 10 is a partially enlarged view of a blanking aperture array system. FIG. 11 is a schematic configuration view of a blanking aperture array system according to a modification. FIG. 12 is a cross-sectional perspective view of a second radiation shield. DETAILED DESCRIPTION In one embodiment, a blanking aperture array system includes a blanking aperture array substrate including a plurality of beam passage holes, through which beams in a multi charged particle beam pass from upstream to downstream, the plurality of beam passage holes being provided with respective blankers that perform blanking deflection on the beams, a first radiation shield disposed upstream of the blanking aperture array substrate, and a second radiation shie