JPS6224621A - Charged particle lithography equipment - Google Patents

Abstract

PURPOSE:To improve productivity by forming a structure so that the focal point of charged particle beam to a sample may be adjusted to the optimum condition in accordance with change in size of sectional view of charged particle beam to be directed to an sample. CONSTITUTION:A lens intensity controller 15 which controls intensity of an objective lens 10 and a focal point correction lens 11 is connected to a pattern data controller 14 with a beam forming stop 13 and is connected to a focal point distance calculator 16 which calculates optimum focal point distance in accordance with the sectional area of the electron beam E determined by the pattern data controller 14. Intensity of objective lens 10 and focal point correction lens 11 may be adjusted in accordance with change in sectional area of the electron beam E and the focal point is always matched on the flat surface of a wafer 2. Thereby, the sectional area of electron beam E may be set to a comparatively large value and a number of times of irradiation with electron beam E can be reduced without reduction of size accuracy of pattern to be exposed on the wafer 2 and moreover productivity may be improved through increase of exposure processing area per unit time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a lithography technique, and particularly to a technique that is effective when applied to an electron beam lithography technique in the manufacture of semiconductor devices.

[Background Art] In recent years, in the manufacturing of semiconductor devices, the patterns of semiconductor elements formed on wafers have become smaller and smaller due to demands for smaller size, higher integration, and high-mix low-volume production of semiconductor devices. The process of transferring images onto wafers is also becoming more complex.

For this reason, in order to create masks and reticles that serve as master plates for transferring patterns onto wafers with higher precision, and to simplify the lithography process by drawing patterns directly onto wafers, it is possible to use conventional light beams. In place of exposure technology, an electron beam lithography device with higher resolution may be used.

As this electron beam lithography apparatus, the following can be considered.

In other words, it is a so-called variable-shaped beam electron beam that directly irradiates a sample such as a wafer with the photoelectronic surface image of a beam with a rectangular cross section whose dimensions and area are variable, and exposes the target pattern by dividing it into predetermined rectangles. It is a drawing device.

In this case, in order to improve the throughput per unit time, it is conceivable to increase the area of the rectangular photoelectronic surface and perform the predetermined pattern with fewer divisions, that is, with fewer irradiation times. When the area of the photoelectron surface increases, the electron beam expands due to the Coulomb repulsion generated between electrons in the electron beam, which changes the focal position of the beam on the sample surface, resulting in a pattern drawn on the sample surface. The inventors have discovered that there is a drawback that the dimensional accuracy of the dimensional accuracy is reduced.

In addition, as a document explaining the electron beam lithography technique, there is "Electronic Materials 41983 Betsukuda, P105-P110, published by Kogyo Research Association Co., Ltd., November 15, 1980.

[Object of the Invention] An object of the present invention is to provide a charged particle drawing technique that can improve productivity without reducing the dimensional accuracy of a pattern drawn on a sample.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Summary of the Invention] A brief overview of typical inventions disclosed in this application is as follows.

In other words, by adopting a structure in which the focal position of the charged particle beam with respect to the sample is adjusted to be optimal according to a change in the cross-sectional dimension of the charged particle beam irradiated onto the sample, for example, the beam cross-sectional area can be made relatively small. This prevents the dimensional accuracy of the pattern drawn on the sample from being degraded due to focal position changes caused by the repulsion between charged particles generated when the charged particles become large. By using a charged particle beam with a relatively large cross-sectional area, it is possible to reduce the number of charged particle beam irradiations, that is, to improve the drawing speed, without reducing the image quality, thereby improving productivity.

[Example] FIG. 1 is an explanatory diagram showing a main part of an electron beam exposure apparatus which is an example of the present invention.

A wafer 2 whose surface is uniformly coated with a resist that is sensitive to electron beams is placed on a horizontally arranged XY table l.
is removably placed in a predetermined positional relationship with the XY table l.

Further, above the XY table 1, there is provided an electron gun 3 that emits an electron beam E in a direction substantially perpendicular to the plane of the XY table 1, and below the electron gun 3, the electron beam E is provided. An irradiation lens 5 is provided which focuses the light and guides it to a first aperture 4 having an opening of a predetermined shape.

Below the first aperture 4, a molded deflector 6 and a molded lens 7 are provided, which are composed of a plurality of electrode plates and the like, which are positioned facing each other in directions perpendicular to each other.
llll! The electron beam E, which is shaped into a predetermined rectangular cross section by the The shape of the portion where the cross-sectional shape of the electron beam E formed by passing through the aperture 4 and the opening of the second aperture 8 overlap is the shape of the electron beam E.
The structure is such that the electron beam E is shaped to have a new cross-sectional shape.

The electron beam E, which is shaped into a predetermined shape by passing through the second aperture 8, passes through the second aperture 8.
The wafer is adjusted to a predetermined cross-sectional area by the reduction lens 9 provided below, passes through the objective lens IO, the focus correction lens 11, and the positioning deflector 12, and is placed on the XY table. It is configured so that the irradiation is focused on two predetermined areas.

The XY table l and the series of electron optical systems installed above it are housed in a predetermined vacuum container (not shown), and are used for drawing on the wafer 2 under a predetermined degree of vacuum. will be implemented.

In this case, e-bee 1. The shaping deflector 6, the shaping lens 7, the reduction lens 9, etc. that are related to determining the cross-sectional shape and area of H are connected to the beam shaping aperture control section 13, and the beam shaping aperture section 13 is connected to the pattern data control section 14. It is connected to the.

Then, in the pattern data control section 14, beam cross-sectional dimensions, area, etc. are determined based on pattern information to be formed on the wafer 2 given from an external storage section (not shown), etc., and the beam shaping aperture control section 13 is Through,
The shaping deflector 6, the shaping lens 7, and the reduction lens 9 are appropriately controlled so that an electron beam E having a predetermined cross-sectional area and shape is output.

On the other hand, the objective lens 10 and the wafer 2 of the objective lens 10
The focus correction lens 11 that corrects the focal position relative to the object lens 11 is connected to a lens strength control section 15 that controls the strength of the magnetic field generated in the objective lens lO and the focus correction lens 11.

Furthermore, the lens strength control section 15 is connected to a focal length calculation section 16 which is connected to the pattern data control section 14 and calculates an optimal focal length according to the cross-sectional area of the electron beam E determined by the pattern data control section I4. The objective lens I is connected in synchronization with the change in the cross-sectional area of the electron beam E.
The intensity is adjusted in O and focus correction lens +1, and the focus is always on the plane of wafer 2 without being affected by the phenomenon of expansion of the cross-sectional area of the electron beam E caused by changes in the cross-sectional area of the electron beam E. is configured to be

The operation of this embodiment will be explained below.

First, the wafer 2 is placed on the XY table 1, and
A predetermined degree of vacuum is maintained in a vacuum container in which an electron optical system and the like provided above the table 1 and the XY table 1 are housed.

Next, the electron gun 3 emits an electron beam E with a predetermined intensity, and the pattern data control unit 14 generates a pattern based on the pattern shape to be formed on the wafer 2 placed on the XY table 1. The number of divisions, the cross-sectional shape and area of the electron beam E, etc. are determined, and the shaping deflector 6 and the shaping lens 7, as well as the reduction lens 9, are appropriately controlled via the beam shaping aperture section 13, and the electron beam E is shaped into a predetermined shape. After being molded to have the shape and cross-sectional area,
The light passes through an objective lens 10, a focus correction lens 11, and a positioning deflector 12, and is irradiated so as to focus on a predetermined portion of the wafer 2.

Then, the positioning deflector 12 sequentially moves the arrival position of the electron beam E on the wafer 2 to an adjacent position in a predetermined direction, so that the pattern in a predetermined area is divided by the electron beam E having a predetermined shape and cross-sectional area. exposed to light.

After the exposure of the pattern in a predetermined area of the wafer 2 within the movable range of the electron beam E by the positioning deflector 12 is completed, the XY table l on which the wafer 2 is placed is moved at a predetermined pitch in a predetermined direction. , and the same operation is repeated.

Here, by setting the cross-sectional area of the electron beam E to be relatively large and reducing the number of irradiations with the electron beam E required to expose a pattern of a predetermined shape, the area to be exposed per unit time can be increased and productivity can be increased. When improving the wafer 2, a phenomenon occurs in which the electron beam E expands from a predetermined shape due to an increase in repulsion caused by the Coulomb force between electrons within the electron beam E, and the focal position of the electron beam E on the wafer 2 changes. There is a problem in that the dimensional accuracy of the pattern exposed on the wafer 2 is reduced.

However, in this embodiment, the lens strength control section 15 that controls the strength of the objective lens 10 and the focus correction lens 11 is connected to the pattern data control section 14 together with the beam shaping aperture section 13, and the pattern data control section 14 determines the strength of the objective lens 10 and the focus correction lens 11. The objective lens IO
The intensity of the focus correction lens 11 is adjusted so that the focus is always accurately aligned with the plane of the wafer 2 without being affected by changes in the cross-sectional area of the electron beam E.

Therefore, without reducing the dimensional accuracy of the pattern exposed on the wafer 2, the cross-sectional area of the electron beam E is set to be relatively large, reducing the number of times the electron beam E is irradiated to expose a pattern of a predetermined shape. This makes it possible to improve productivity by increasing the exposed area per unit time.

In addition, although the above explanation describes the case where both the objective lens 10 and the focus correction lens 11 are controlled by the lens strength control unit 15, it is possible to control only one of the objective lens 10 and the focus correction lens 11. It is also possible to configure it so that

[Effects] (1) A charged particle drawing device in which the cross-sectional shape and area of the charged particle beam irradiated onto the sample is variable, through a beam shaping aperture control unit that controls the cross-sectional shape and area of the charged particle beam, a pattern data control section that determines a beam cross-sectional shape and area based on pattern information to be formed on the sample; and a focal length calculation that calculates an optimal focal length according to the beam cross-sectional area determined by the pattern data control section. and a lens intensity control section that is connected to the focal length calculation section and controls the intensity of at least one of the objective lens and the focus correction lens. Because the structure controls the focal position with respect to the sample, the cross-sectional area of the charged particle beam can be set relatively large and a predetermined size can be applied to the sample without reducing the dimensional accuracy of the pattern drawn on the sample. The number of times of charged particle beam irradiation required to draw a pattern can be reduced, and productivity in drawing patterns on a sample can be improved.

(2) As a result of (11) above, productivity in the wafer processing step of manufacturing semiconductor devices is improved.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, the sample on which a predetermined pattern is drawn is not limited to a wafer, but may also be a photomask, a reticle, or the like.

[Field of Application] In the above explanation, the invention made by the present inventor was mainly applied to electron beam exposure technology, which is the field of application that formed the background of the invention, but the invention is not limited thereto. It can be widely applied to technologies that utilize energy.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a main part of an electron beam exposure apparatus which is an embodiment of the present invention. 1...XY table, 2...wafer (sample), 3...
...electron gun, 4...first aperture, 5...irradiation lens, 6...molding deflector, 7...molding lens, 8...
...Second aperture, 9...Reducing lens, 10...
Objective lens, 11... Focus correction lens, 12... Positioning deflector, 13... Beam shaping aperture control unit, 14
. . . pattern data control unit, 15 . . . lens strength control unit, 16 . . . focal length calculation unit.

Claims (1)

[Claims] 1. A charged particle drawing device in which the cross-sectional shape and area of a charged particle beam irradiated onto a sample can be varied, comprising a beam shaping aperture control section that controls the cross-sectional shape and area of the charged particle beam. a pattern data control unit that determines the cross-sectional shape and area of the charged particle beam based on pattern information to be formed on the sample; It consists of a focal length calculation section that calculates the focal length of the charged particle beam, and a lens strength control section that is connected to the focal length calculation section and controls the intensity of at least one of the objective lens and the focus correction lens. A charged particle drawing device characterized in that a focal position of a charged particle beam irradiated onto a sample with respect to the sample is controlled according to changes. 2. The charged particle drawing apparatus according to claim 1, wherein the charged particle beam is an electron beam. 3. The charged particle drawing apparatus according to claim 1, wherein the sample is a wafer.