JP2000294485A - Method for regulating electric charged particle beam projection aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly simply regulate the illuminance distribution in an opening of a forming aperture with high precision by a method wherein electron beams are scanned in an exposing opening, and an electron source, an electron lens system, and a deflector system are regulated based on measuring results of this illuminance distribution. SOLUTION: A movable Faraday cup 9 is moved to between a second electronic lens 3 and a mask stage, and is moved on a central axis. A forming aperture 5a and the mask stage have a positional relationship serving in common with a plane electronic source 1. An exposing opening 7 and a current density distribution measuring opening 8 are respectively provided in the forming aperture 5a, and each opening is exchangeable by a revolver type. The aperture 5a is installed so that electron beams pass through the exposing opening 7 at the time of exposure. In order to evaluate uniformity within an illuminance face of the opening in the aperture 5a, when a current density distribution is measured, the aperture 5a is rotated, and a current density distribution measuring opening 8 is switched so as to come to a center through which the electron beams pass. The electron beams are scanned in the current density distribution measuring opening 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for adjusting a charged particle beam projection exposure apparatus.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of semiconductor integrated circuit elements, charged particle beams (hereinafter, referred to as X-rays, electron beams, ion beams, etc.) have been developed in order to improve the resolution of an optical system limited by the diffraction limit of light. An exposure method (lithography technique) using a charged particle beam (hereinafter simply referred to as a charged particle beam) has been developed. Among them, electron beam exposure, in which a pattern is formed using an electron beam, is characterized in that a fine pattern of 1 μm or less can be formed because the electron beam itself can be reduced to several Å (angstrom). is there.

However, since the conventional electron beam exposure method is a one-stroke writing method, the finer the pattern, the more the electron beam must be drawn with a narrower electron beam, the longer the drawing time, and the cost of device production. It was not used for exposure of mass-produced wafers. Therefore, there has been proposed a charged particle beam reduction transfer apparatus which irradiates a transfer mask having a predetermined pattern with an electron beam and reduces and transfers a pattern in the irradiation range to a wafer by a projection lens.

FIGS. 4A and 4B are schematic diagrams of an electron source, an illumination system, and the like in an electron beam reduction transfer apparatus. In order to project a circuit pattern, a transfer mask on which the circuit pattern is drawn is required. As a transfer mask, FIG.
As shown in FIG. 7, a scattered transmission mask 11 having no through holes and a scatterer pattern 14 formed on a membrane 12
As shown in FIG. 5B, a scattering stencil mask 21 in which a through-hole pattern 24 is formed on a membrane 22 having a thickness enough to scatter an electron beam is known.

[0005] In these, a large number of small regions 12a and 22a provided with patterns to be transferred to the sensitive substrate on the membranes 12 and 22 are divided by a boundary region where no pattern exists, and a support 13 is provided at a portion corresponding to the boundary region. , 23
Is provided. Such a small area is about 1 mm square, and the area to be illuminated is wider than in the related art, and a uniform aperture is formed by using a tip having a conical tip as an electron source, except for a part having a non-uniform illuminance distribution by a shaping aperture. It is not possible to cope with the method of using a line, the current density distribution in this small area is uniform, that is, using a planar electron source to make the illumination uniform,
A method has been considered in which the in-plane uniformity is ensured by forming the electron source image on a mask.

[0006]

However, this method has a problem that the state of the electron source or the electron lens of the illumination system is directly reflected on the in-plane illumination uniformity. In order to compensate for this, the current density distribution in each plane (within a small area) on the mask and the shaping aperture which is in a conjugate positional relationship with the electron source is measured, and based on the result, it is arranged above the shaping aperture. It is necessary to adjust the adjusted electron lens, deflector, electron source, and the like, and adjust the electron lens, deflector, and the like disposed between the shaping aperture and the mask.

That is, when the illuminance distribution in the entire illumination system is measured and the whole illumination system is to be adjusted collectively, aberrations and the like are complicatedly intertwined, and the electron lens, deflector system, and electron source to be adjusted are specified. Since it is difficult to perform appropriate adjustment, it is necessary to perform adjustment by dividing each part. The in-plane uniformity of the illuminance of the shaping aperture is determined by measuring the current density distribution by scanning an electron beam over the shaping aperture located in a conjugate positional relationship with the electron source. Since the diameter of the electron beam is about several millimeters, while it is about 1 mm square, only a broad profile can be obtained, and it is difficult to determine.

Further, since it is difficult to determine the in-plane uniformity of the illuminance of the shaping aperture, it is impossible to adjust the electron source and the electron lens system. Therefore, the present invention has been made in view of such a conventional problem, and provides a method of adjusting a charged particle beam projection exposure apparatus for simply and accurately adjusting an illuminance distribution at an opening of a forming aperture. The purpose is to provide.

[0009]

According to the present invention, there is provided an electron optical system having an electron source, an electron lens system, and a deflector system, and having a shaping aperture and a mask stage arranged in a conjugate relationship with the electron source. In the adjusting method of the charged particle beam projection exposure apparatus, the shaping aperture has an opening having an extremely small diameter with respect to the diameter of the electron beam other than the opening for exposure, and the electron beam is scanned over the opening. An adjustment method for a charged particle beam projection exposure apparatus that measures an illuminance distribution (current density distribution) of an electron beam and adjusts the electron source, the electron lens system, and the deflector system based on the measurement result (claim Item 1) ”is provided.

Further, the present invention provides an electron source, an electron lens system,
A method for adjusting a charged particle beam projection exposure apparatus having a deflector system, a shaping aperture in a positional relationship conjugate with the electron source, and an electron optical system in which a mask stage is disposed, wherein the mask stage has a diameter of an electron beam. The electron beam is scanned over the opening to measure the illuminance distribution (current density distribution) of the electron beam, and based on the measurement result, the electron source and the electron Lens system,
A method for adjusting a charged particle beam projection exposure apparatus by adjusting the deflector system (claim 2) "is provided.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A measurement of an illuminance distribution (current density distribution) on an opening of a shaping aperture according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a state of measuring an illuminance distribution (current density distribution) on an opening of a forming aperture according to the first embodiment of the present invention.

The illumination system and the like according to the first embodiment include a plane electron source 1, a first electron lens 2, a deflector system (axis deflectors 4a and 4c, a shaping aperture deflector 4b, a mask deflector 4b). 4 d), a shaping aperture 5 a, and a second electron lens 3. A movable Faraday cup 9 is provided between the second electron lens 3 and the mask stage 6.
The Faraday cup 9 is moved and brought to the center axis by moving the Faraday cup 9 at the off-axis standby at the time of exposure and at the time of measuring the current density distribution.

Forming aperture 5a and mask stage 6
Has a conjugate positional relationship with the plane electron source 1. The shaping aperture 5a is provided with an opening 7 for exposure and an opening 8 for measuring current density distribution, and each opening is replaceable by a revolver method. The opening 7 for exposure is about 1 mm square because the diameter of the electron beam is about several mm.
The opening 8 for measuring the current density distribution is about $ 10 μm.

At the time of exposure, a shaping aperture 5a is provided so that an electron beam passes through the exposure opening 7, and a current density distribution is measured to evaluate the in-plane uniformity of the illuminance of the opening of the shaping aperture. In this case, by rotating the forming aperture 5a, the current density distribution measuring opening 8 is switched to the center through which the electron beam passes, and the electron beam is scanned on the current density distribution measuring opening 8.

Since the aperture 8 for measuring the current density distribution is sufficiently smaller than the diameter of the electron beam, the current density distribution of the electron beam can be accurately measured, and the profile shown in FIG. 1 is obtained. The Faraday cup 9 is connected to a CRT, and the CRT is connected to a computer (not shown). The computer includes a plane electron source 1, a first electron lens 2, a second electron lens 3, and a deflector system 4. Connected to each other.

The image of the CRT image is processed and the contents calculated from the processing result are sent directly to the computer to control the above-mentioned flat electron source 1, first electron lens 2 and the like. The factors that deteriorate the in-plane uniformity on the mask and the shaping aperture are mainly caused by (1) insufficient curvature adjustment of the center axis of the electron lens of the illumination system, which causes curvature of field and spherical aberration. That the plane electron source image does not form an image on the mask and the shaping aperture. (2) The influence of the in-plane non-uniformity of the surface state of the flat electron source is directly reflected on the mask and the shaping aperture. . The profile of the current density distribution is analyzed, and the electron lens 2, the deflector system 4, and the electron source 1 are adjusted based on the information.

This operation is repeated until the in-plane uniformity of the illuminance of the opening of the predetermined forming aperture is obtained. FIG. 2 is a schematic diagram showing a state of measurement of the illuminance distribution (current density distribution) on the opening of the forming aperture according to the second embodiment of the present invention. The configurations of the electron beam source, the illumination system, and the like according to the second embodiment are the same as those described in the first embodiment.

However, since the forming aperture 5b is not provided with a rotating mechanism, when measuring the current density distribution in order to evaluate the uniformity within the mask surface, an electron beam is placed on the forming aperture 5b. It is deflected by using the formed aperture-on-aperture deflector 4b, and the current density distribution measurement opening 8 is deflected.
Scan on top. The profile of the current density distribution obtained in the same manner as in the first embodiment is analyzed, and the electron lens 2, the deflector system 4, and the electron source 1 are adjusted based on the information.

FIG. 3 is a schematic diagram showing a state of measurement of an illuminance distribution (current density distribution) on an opening of a forming aperture according to a third embodiment of the present invention. The configuration of the electron beam source, the illumination system, and the like of the third embodiment is such that the shaping aperture 5c has no opening for measuring the current density distribution, the Faraday cup 9 is arranged below the mask stage 6, and the mask stage 6 has Has the same configuration as the electron beam source, the illumination system, and the like of the first embodiment except that a current density distribution measurement opening 10 is formed.

When the electron beam is scanned over the exposure opening 7 of the shaping aperture 5c by the shaping aperture deflector 4b, the electron beam on the mask stage 6 having a conjugate positional relationship with the shaping aperture 5c is automatically masked. Stage 6
It is possible to scan over the current density distribution measurement opening 10 formed thereon. Since the diameter of the electron beam on the mask stage 6 is about 1 mm square, an accurate current density distribution profile of the electron beam can be obtained by setting the aperture 10 for current density distribution measurement to about Φ10 μm. ,
The profile of the current density distribution obtained in the same manner as in the first embodiment is analyzed, and the electron lens 2, the deflector system 4, and the electron source 1 are adjusted based on the information.

[0021]

As described above, according to the method for adjusting the charged particle beam projection exposure apparatus of the present invention, the illuminance distribution on the opening of the shaping aperture, that is, the current density distribution, can be measured with high accuracy, and the measurement profile is obtained. The electron lens, the deflector system, and the electron source disposed above the shaping aperture can be adjusted based on the above, and in-plane uniformity over the opening of the shaping aperture can be ensured.

Further, when the in-plane uniformity of the illuminance on the mask is improved by adjusting the electron lens and the deflector system between the shaping aperture and the mask, the line width control (resolution) is improved. Thus, highly integrated devices can be produced with high yield.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a state of measuring an illuminance distribution (current density distribution) on an opening of a forming aperture according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a state of measuring an illuminance distribution (current density distribution) on an opening of a forming aperture according to a second embodiment of the present invention.

FIG. 3 is a schematic diagram showing a state of measuring an illuminance distribution (current density distribution) on an opening of a forming aperture according to a third embodiment of the present invention.

4A and 4B are schematic diagrams of an electron beam source, an illumination system, and the like in the electron beam reduction transfer device.

FIGS. 5A and 5B are schematic diagrams of a scattering transmission mask, a scattering stencil mask, and a pattern transfer method using an electron beam, respectively. It is a schematic perspective view shown.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electron source 2 ... 1st electron lens 3 ... 2nd electron lens 4 ... Deflector system 5 ... Molding aperture 6 ... Mask stage 7 ... Exposure opening 8, DESCRIPTION OF SYMBOLS 10 ... Aperture for electron beam current density distribution measurement 9 ... Faraday cup 11 ... Scattering transmission mask 12,22 ... Membrane 13,23 ... Post 14 ... Scatterer pattern 17 ... Photosensitive substrate 21: scattering stencil mask 24: through-hole pattern

Claims (2)

[Claims] An electron source, an electron lens system, and a deflector system;
In the method of adjusting a charged particle beam projection exposure apparatus including an electron optical system in which a shaping aperture and a mask stage are arranged in a conjugate positional relationship with the electron source, the shaping aperture may have a diameter corresponding to an electron beam diameter other than an exposure opening. An aperture having an extremely small diameter with respect to the electron beam, an illuminance distribution (current density distribution) of the electron beam is measured by scanning the electron beam over the aperture, and based on the measurement result, the electron source and the electron lens And a method of adjusting a charged particle beam projection exposure apparatus by adjusting the deflector system. 2. An electron source, an electron lens system, and a deflector system,
A method for adjusting a charged particle beam projection exposure apparatus including an electron optical system in which a shaping aperture and a mask stage are arranged in a conjugate positional relationship with the electron source, wherein the mask stage has an extremely small diameter with respect to the diameter of the electron beam. An aperture is provided, the illuminance distribution (current density distribution) of the electron beam is measured by scanning the electron beam over the opening, and based on the measurement result, the electron source, the electron lens system, and the deflector system Of adjusting the charged particle beam projection exposure apparatus by adjusting the distance.