# US 6,014,200 A · High throughput electron beam lithography system

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- Number: US 6,014,200 A
- Document ID: US6014200A
- Status: Granted
- Kind: A
- Application number: 09/028,721
- Filed: 1998-02-24
- Granted: 2000-01-11
- Earliest claimed: 1998-02-24
- Assignees: Nikon Corporation
- Inventors: Michael R. Sogard; John McCoy
- Web page: https://patentgrep.com/patent/US6014200A

## CPC

- H01J 37/3174: {Particle-beam lithography, e.g. electron beam lithography}
- 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 37/3177: {Multi-beam, e.g. fly's eye, comb probe}
- H01J 2237/31776: Shaped beam
- 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

An electron beam lithography system having a beamlet shaping section that includes a first multi-aperture array having m rows and n columns of apertures having a first shape and a second multi-aperture array with m rows and n columns of apertures having a second shape. Electron beamlets formed by the first multi-aperture array are deflected by a deflector unit before passing through the second multi-aperture array. The superposition of the electron beamlets on the second multi-aperture produces electron beamlets having a selected shape. Deflection logic on an active beam aperture array blank selected electron beamlets. The deflection logic can be updated with the next logic pattern as the current logic pattern is being executed. The unblanked electron beamlets are directed onto a surface to be exposed. The deflection logic on the active beam aperture array, and the multi-aperture arrays, are shielded from electrons and x-rays generated by the electrons striking surfaces within the electron beam lithography system. Sensitive deflection logic is radiation hardened to prevent degradation.

## Claims

### Claim 1

An electron-beam lithography system, comprising:
a source of electrons;
a stage supporting an object to be exposed by the electrons;
a beamlet shaping section disposed between the source of electrons and the object to be exposed by the electrons comprising a first multi-aperture array having m rows and n columns of apertures having a first shape and a second multi-aperture array having m rows and n columns of apertures having a second shape;
a beamlet blanking section disposed between the beamlet shaping section and the object;
a first electron lens group directing electrons emitted from the source of electrons into a collimated beam in an axial direction towards the first multi-aperture array;
a second electron lens group directing each electron beamlet in the array of electron beamlets formed by the first multi-aperture array towards the center of a corresponding aperture in the second multi-aperture array; and
an electron deflector disposed between the first multi-aperture array and the second multi-aperture array.

### Claim 2 (depends on 1)

The electron-beam lithography system of claim 1 wherein the beamlet blanking section comprises an active beam aperture array having m rows and n columns of apertures.

### Claim 3 (depends on 2)

The electron-beam lithography system of claim 2 wherein the system further comprises:
a third electron lens group to direct each electron beamlet in the array of electron beamlets having the selected shape towards a corresponding aperture in the active beam aperture array;
a logic circuit associated with each aperture in the active beam aperture array to deflect selected electron beamlets passing through the active beam aperture array;
a contrast aperture to absorb the selected electrons beamlets deflected by the active beam aperture array and to absorb x-rays generated by electrons striking surfaces in the electron-beam lithography system; and
a fourth electron lens group to focus the electron beamlets passing undeflected through the active beam aperture array onto the object to be exposed.

### Claim 4 (depends on 3)

The electron-beam lithography system of claim 3 wherein the system further comprises a first active beam aperture array shield having m rows and n columns of apertures corresponding to the apertures in the active beam aperture array and wherein the first active beam aperture array shield is disposed between the second multi-aperture array and the active beam aperture array.

### Claim 5 (depends on 4)

The electron-beam lithography system of claim 4 wherein the first active beam aperture array shield comprises a layer of a low atomic number material and a layer of a high atomic number material.

### Claim 6 (depends on 5)

The electron-beam lithography system of claim 5 wherein the system further comprises a second active beam aperture array shield having m rows and n columns of apertures corresponding to the apertures in the active beam aperture array and wherein the second active beam aperture array shield is disposed between the active beam aperture array and the object to be exposed.

### Claim 7 (depends on 6)

The electron-beam lithography system of claim 6 wherein the second active beam aperture array shield comprises a layer of a low atomic number material and a layer of a high atomic number material.

### Claim 8 (depends on 7)

The electron-beam lithography system of claim 7 wherein the system further comprises a first multi-aperture array shield having m rows and n columns corresponding to the apertures in the first multi-aperture array and wherein the first multi-aperture array shield is disposed between the source of electrons and the first multi-aperture array.

### Claim 9 (depends on 8)

The electron-beam lithography system of claim 8 wherein the first multi-aperture array shield comprises a layer of a low atomic number material and a layer of a high atomic number material.

### Claim 10 (depends on 9)

The electron-beam lithography system of claim 9 wherein the system further comprises a second multi-aperture array shield having m rows and n columns corresponding to the apertures in the second multi-aperture array and wherein the second multi-aperture array shield is disposed between the first multi-aperture array and the second multi-aperture array.

### Claim 11 (depends on 10)

The electron-beam lithography system of claim 10 wherein the second multi-aperture array shield comprises a layer of a low atomic number material and a layer of a high atomic number material.

### Claim 12 (depends on 11)

The electron-beam lithography system of claim 11 wherein the system further comprises at least one x-ray baffle.

### Claim 13 (depends on 12)

The electron-beam lithography system of claim 12 wherein the at least one x-ray baffle is disposed between the second multi-aperture array and the active beam aperture array.

### Claim 14 (depends on 13)

The electron-beam lithography system of claim 13 wherein the fourth electron lens group comprises:
a first symmetric magnetic doublet disposed between the active beam aperture array and the surface to be exposed; and
a second symmetric magnet doublet disposed between the first symmetric magnetic doublet and the object to be exposed.

### Claim 15 (depends on 14)

The electron-beam lithography system of claim 14 wherein the system further comprises a deflection system disposed in the second symmetric magnetic doublet to deflect each electron beamlet onto a portion of the object to be exposed.

### Claim 16 (depends on 15)

The electron-beam lithography system of claim 15 wherein the system further comprises a control unit coupled to:
the electron deflector;
each logic circuit associated with each aperture in the active beam aperture array;
the deflector system; and
the stage.

### Claim 17 (depends on 16)

The electron-beam lithography system of claim 16 wherein a contrast aperture is disposed at a crossover point of the first symmetric magnetic doublet.

### Claim 18 (depends on 17)

The electron-beam lithography system of claim 17 wherein the logic circuit associated with each aperture includes a memory unit to store a next pattern logic.

### Claim 19 (depends on 1)

The electron-beam lithography system of claim 1 wherein the source of electrons comprises an electron gun.

### Claim 20 (depends on 1)

The electron-beam lithography system of claim 1 wherein the source of electrons comprises an array of individual electron sources that produce an array of electron beamlets having m rows and n columns that correspond to the apertures of the first multi-beam aperture array.

### Claim 21

A method of exposing an object with electrons in an electron-beam lithography system, the method comprising:
generating electrons;
directing the electrons in a collimated beam in an axial direction towards the object to be exposed;
directing the collimated beam of electrons through a beamlet shaping section comprising a first multi-aperture array having m rows and n columns of apertures having a first shape, a second multi-aperture array having m rows and n columns of apertures having a second shape;
directing the electrons emerging from the beamlet shaping section through a beamlet blanking section;
directing electron beamlets having the first shape formed by the first multi-aperture array towards the center of corresponding apertures in the second multi-aperture array; and
deflecting each of the electron beamlets formed by the first multi-aperture array away from the center of the corresponding aperture in the second multi-aperture array.

### Claim 22 (depends on 21)

The method of claim 21 wherein directing the electrons through a beamlet blanking section comprises directing the electrons through an active beam aperture array having m rows and n columns of apertures.

### Claim 23 (depends on 22)

The method of claim 22 wherein the method further comprises:
directing each electron beamlet in the array of electron beamlets having the selected shape towards a corresponding aperture in the active beam aperture array;
deflecting selected electron beamlets passing through the active beam aperture array with logic circuits associated with each aperture in the active beam aperture array;
absorbing the selected electrons beamlets deflected by the active beam aperture array with a contrast aperture; and
focusing the electron beamlets passing undeflected through the active beam aperture array onto the object to be exposed.

### Claim 24 (depends on 23)

The method of claim 23 wherein the method further comprises directing the electron beamlets having the selected shape through a first active beam aperture array shield having m rows and n columns of apertures corresponding to the apertures in the active beam aperture array and wherein the first active beam aperture array shield is disposed between the second multi-aperture array and the active beam aperture array.

### Claim 25 (depends on 24)

The method of claim 24 wherein directing the electron beamlets having the selected shape through a first active beam aperture array shield comprises directing the electron beamlets through a first active beam aperture array shield comprising a layer of a low atomic number material and a layer of a high atomic number material.

### Claim 26 (depends on 25)

The method of claim 25 wherein the method further comprises directing the electron beamlets having the selected shape through a second active beam aperture array shield having m rows and n columns of apertures corresponding to the apertures in the active beam aperture array and wherein the second active beam aperture array shield is disposed between the active beam aperture array and the object to be exposed.

### Claim 27 (depends on 26)

The method of claim 26 wherein directing the electron beamlets having the selected shape through a second active beam aperture array shield comprises directing the electron beamlets through a second active beam aperture array shield comprising a layer of a low atomic number material and a layer of a high atomic number material.

### Claim 28 (depends on 27)

The method of claim 27 wherein the method further comprises directing the electron beamlets through a first multi-aperture array shield having m rows and n columns corresponding to the apertures in the first multi-aperture array and wherein the first multi-aperture array shield is disposed between the source of electrons and the first multi-aperture array.

### Claim 29 (depends on 28)

The method of claim 28 wherein directing the electron beamlets through a first multi-aperture array shield comprises directing the electron beamlets through a first multi-aperture array shield comprising a layer of a low atomic number material and a layer of a high atomic number material.

### Claim 30 (depends on 29)

The method of claim 29 wherein the method further comprises directing the electron beamlets through a second multi-aperture array shield having m rows and n columns corresponding to the apertures in the second multi-aperture array and wherein the second multi-aperture array shield is disposed between the first multi-aperture array and the second multi-aperture array.

### Claim 31 (depends on 30)

The method of claim 30 wherein directing the electron beamlets through a second multi-aperture array shield comprises directing the electron beamlets through a second multi-aperture array shield comprising a layer of a low atomic number material and a layer of a high atomic number material.

### Claim 32 (depends on 31)

The method of claim 31 wherein the method further comprises directing the electron beamlets through at least one x-ray baffle.

### Claim 33 (depends on 32)

The method of claim 32 wherein directing the electron beamlets through at least one x-ray baffle comprises directing the electron beamlets through at least one x-ray baffle disposed between the second multi-aperture array and the active beam aperture array.

### Claim 34 (depends on 33)

The method of claim 33 wherein the method further comprises:
directing the electron beamlets through a first symmetric magnetic doublet disposed between the active beam aperture array and the surface to be exposed; and
directing the electron beamlets through a second symmetric magnetic doublet disposed between the first symmetric magnetic doublet and the object to be exposed.

### Claim 35 (depends on 34)

The method of claim 34 wherein the method further comprises directing the electron beamlets through a deflection system disposed in the second symmetric magnetic doublet.

### Claim 36 (depends on 35)

The method of claim 35 wherein the method further comprises controlling the electron deflector, each logic circuit associated with each aperture in the active beam aperture array, the deflecting, and movement of a stage which supports the object with a control unit.

### Claim 37 (depends on 1)

The electron beam lithography system of claim 1, wherein the first multi-aperture array forms an array of electron beamlets having the first shape; and
wherein the electron deflector deflects each electron beamlet in the array of electron beamlets having the first shape away from the center of the corresponding aperture in the second multi-aperture array, whereby each electron beamlet in the array of electron beamlets having a first shape is superimposed into a portion of the corresponding aperture in the second multi-aperture array, and wherein each electron beamlet in the array of electron beamlets is formed into a selected shape determined by the superposition of the deflected electron beamlets having the first shape onto the second shape of the apertures of the second multi-aperture array.

### Claim 38 (depends on 21)

The method of claim 21, wherein each electron beamlet in the array of electron beamlets having a first shape is superimposed onto a portion on the corresponding aperture in the second multi-aperture array, and wherein each electron beamlet in the array of electron beamlets is formed into a selected shape determined by the superposition of the deflected electron beamlets having the first shape onto the second shape of the apertures of the second multi-aperture array.