# US 2001/0023926 A1 · Method of forming a quadrupole device for projection lithography by means of charged particles

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- Number: US 2001/0023926 A1
- Document ID: US20010023926A1
- Status: Published application
- Kind: A1
- Application number: 09/824,620
- Filed: 2001-04-02
- Published: 2001-09-27
- Earliest claimed: 1998-09-09
- Assignees: Philips Corporation
- Inventors: Marcellinus P.C.M. Krijn
- Web page: https://patentgrep.com/patent/US20010023926A1

## CPC

- H01J 37/3175: {Projection methods, i.e. transfer substantially complete pattern to substrate}
- B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
- B82Y 40/00: Manufacture or treatment of nanostructures
- H01J 37/3007: {Electron or ion-optical systems}
- H01J 2237/04928: Telecentric systems
- H01J 2237/31788: through mask
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES

## Abstract

According to a known projection lithography method an object is imaged on an imaging surface by means of a telescopic system of rotationally symmetrical electron lenses. The throughput during the production of integrated circuits by means of projection lithography is determined by the amount of current in the imaging electron beam; this current is limited by the resolution-limiting interaction of the electrons (Coulomb interaction). The invention allows for a larger beam current in that areas with a high current concentration are avoided. To this end, the imaging system includes five mutually perpendicular quadrupoles, so that the electrons are concentrated in line-shaped focal spots instead of a (small) circular cross-over. The system is telescopic and the imaging is stigmatic with equal magnifications in the x-z plane and the y-z plane.

## Claims

### Claim 1

A lithography device for carrying out projection lithography by means of charged particles, which device includes an imaging particle-optical system for imaging a lithographic object structure (14) on a lithographic imaging surface (16), characterized in that
the particle-optical system includes at least five quadrupoles (32, 34, 36, 38, 40),
neighboring quadrupoles of said quadrupoles each time extending perpendicularly to one another,
the strength and the location of said quadrupoles being such that the imaging of the lithographic object structure (14) on the lithographic imaging surface (16) is stigmatic, and that the system is telescopic in the x-z plane as well as in the y-z plane.

### Claim 2 (depends on 1)

A lithography device as claimed in claim 1, in which the x magnification Mx from the lithographic object structure to the lithographic imaging surface equals the y magnification My.

### Claim 3 (depends on 2)

A lithography device as claimed in claim 2, in which the following four relations exist between the various dimensional parameters (A, a, b, c, d, D) of the particle-optical system: 4 A = - 2 ⁢ DM 2 ⁡ ( 1 + M ) + b ⁡ ( 1 + 4 ⁢ M + M 2 - C ) 2 ⁢ ( 1 + M ) ( 1 ) a = b ⁢ - 2 ⁢ M + C 2 ⁢ ( 1 + M ) ( 2 ) c = b M ( 3 ) d = b ⁢ - 2 ⁢ M + C 2 ⁢ M 2 ⁡ ( 1 + M ) ( 4 )
in which:
M=the angular magnification by the imaging particle-optical system from the lithographic object structure (14) to the lithographic imaging surface (16),
C={square root}(M+6M2+M3),
A=the distance between the lithographic object structure (14) and the first quadrupole (32),
a=the distance between the first quadrupole (32) and the second quadrupole (34),
b=the distance between the second quadrupole (34) and the third quadrupole (36),
c=the distance between the third quadrupole (36) and the fourth quadrupole (38),
d=the distance between the fourth quadrupole (38) and the fifth quadrupole (40), and
D=the distance between the fifth quadrupole (40) and the lithographic imaging surface (16).

### Claim 4

A method of manufacturing an integrated electronic circuit, in which a projection lithographic image of a lithographic object structure (14) is formed on a lithographic imaging surface (16), forming part of the integrated electronic circuit, by means of a beam of charged particles, which image is realized by means of an imaging particle optical system, characterized in that
the imaging beam is subjected to the effects of a first up to and including a fifth quadrupole field forming part of the particle-optical system, neighboring quadrupole fields of said quadrupole fields extending each time perpendicularly to one another,
the strength and the location of said quadrupole fields being chosen to be such that the imaging of the lithographic object structure (14) on the lithographic imaging surface (16) is stigmatic, and that the system is telescopic in the x-z plane as well as in the y-z plane.

### Claim 5 (depends on 4)

A method as claimed in claim 4, in which the strength and the location of the quadrupole fields are chosen to be such that the x magnification Mx from the lithographic object structure to the lithographic imaging surface equals the y magnification My.

### Claim 6 (depends on 5)

A method as claimed in claim 5, in which the various dimensional parameters (A, a, b, c, d, D) of the particle-optical system are chosen to be such that the following four relations exist between these dimensional parameters: 5 A = - 2 ⁢ DM 2 ⁡ ( 1 + M ) + b ⁡ ( 1 + 4 ⁢ M + M 2 - C ) 2 ⁢ ( 1 + M ) ( 1 ) a = b ⁢ - 2 , + C 2 ⁢ ( 1 + M ) ( 2 ) c = b M ( 3 ) d = b ⁢ - 2 ⁢ M + C 2 ⁢ M 2 ⁡ ( 1 + M ) ( 4 )
in which:
M=the angular magnification by the imaging particle-optical system from the lithographic object structure (14) to the lithographic imaging plane (16),
C={square root}(M+6M2+M3),
A=the distance between the lithographic object structure (14) and the center of the first quadrupole field,
a=the distance between the center of the first quadrupole field and the center of the second quadrupole field,
b=the distance between the center of the second quadrupole field and the center of the third quadrupole field,
c=the distance between the center of the third quadrupole field and the center of the fourth quadrupole field,
d=the distance between the center of the fourth quadrupole field and the center of the fifth quadrupole field, and
D=the distance between the center of the fifth quadrupole field and the lithographic imaging plane (16). According to a known projection lithography method an object (14) is imaged on an imaging surface (16) by means of a telescopic system of rotationally symmetrical electron lenses (10, 12). The throughput during the production of integrated circuits by means of projection lithography is determined by the amount of current in the imaging electron beam; this current is limited by the resolution-limiting interaction of the electrons (Coulomb interaction).
The invention allows for a larger beam current in that areas (18) with a high current concentration are avoided. To this end, the imaging system includes five mutually perpendicular quadrupoles (32, 34, 36, 38, 40), so that the electrons are concentrated in line-shaped focal spots instead of a (small) circular cross-over (18). The system is telescopic and the imaging is stigmatic with equal magnifications in the x-z plane and the y-z plane.