JPH02215119A - Charged particle beam exposing device - Google Patents

Abstract

PURPOSE:To facilitate the positioning and handling of a mask by a method wherein a transmission mask is formed by closely adhering a transmission mask substrate, on which a pattern group is formed, to a mask supporting plate, on which a heater wiring for heating and an electrode are formed and also a pattern group is formed on a shape-standardized mask supporting plate. CONSTITUTION:A transmission mask, on which a pattern group consisting of an aggregate of designed pattern with which the cross section of a beam will be shaped up is formed, is provided on the position where a charged particle beam passes, and a light exposing operation is conducted using the charged particle beam which passed through the transmission mask. A heater wiring 22, to be used for heating of the transmission mask, and the electrode 24, to be used to conduct electricity to the heater wiring 22, are formed on the transmission mask, and also the transmission mask is composed of a mask supporting plate 21, the shape of which is standardized in advance, and a transmission mask substrate 28 on which a stencil part 27 is formed. A transmission mask substrate 28 is attached in such a manner that it is closely adhered to the supporting plate 24. Through these procedures, the positioning of mask when an exposing operation is conducted can be facilitated, and the handling of the mask can also be conducted easily. Also, the contamination of the transmission mask substrate can be lessened.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to a charged particle beam exposure device, particularly a charged particle beam exposure device using an electron beam using a stencil-type transmission mask, which facilitates mask alignment and prevents the transmission mask from becoming dirty. The purpose of this invention is to provide a charged particle beam exposure device that is easy to handle, and includes a transmission mask in which a pattern group consisting of a collection of several design patterns that shapes the cross-sectional shape of the beam is formed at a position through which the charged particle beam passes. In a charged particle beam exposure apparatus that performs exposure with a charged particle beam transmitted through the transmission mask, the transmission mask is formed with a heater wiring for heating the transmission mask and an electrode for conducting electricity to the heater wiring, The mask support plate is composed of a mask support plate whose shape is standardized in advance, and a transmission mask substrate on which the pattern group is formed, and the transmission mask substrate is attached to the mask support plate.

[Industrial Application Field] The present invention relates to a charged particle beam exposure apparatus, and particularly to a charged particle beam exposure apparatus using an electron beam using a stencil-type transmission mask. In recent years, with the increase in the density of integrated circuits, new exposure methods using electron beams have been studied and are now being used in place of photolithography, which has been the mainstream method for forming fine patterns for many years.

[Conventional technology]

In conventional charged particle beam exposure, such as electron beam exposure, a pattern is formed with an electron beam.

This exposure can form fine patterns of about 1/2 micron or smaller, which could not be formed with photolithography, and can expose designed pattern data using only computer processing means without creating a reticle or mask. Because it is data, it has a quick turnaround. This exposure method is suitable for producing a wide variety of semiconductors in small quantities, such as ASICs.

However, because the pattern is divided based on a huge amount of pattern data, shots are generated, each shot is deflected, and the pattern is drawn on the sample wafer. There was a problem in that high throughput could not be obtained for manufacturing the required semiconductors. Incidentally, in recent semiconductor devices that require ultra-fine patterns, such as 16M-DRAM, the pattern drawn is ultra-fine, but most of the exposed area is a repeated pattern.

In this way, we focused on the fact that in semiconductor devices formed with ultra-fine patterns, repetitive patterns account for the majority of the total desired exposure pattern, and from the entire desired pattern, basic cells, etc., which are the source of the repetitive pattern, are Extract a pattern that is used many times and hold it as a special pattern on the mask as a transparent hole.

When performing exposure, the pattern that is used repeatedly is exposed onto the sample wafer after irradiating the electron beam onto the region where the transmission hole pattern is made up, the so-called block part, and shaping the electron beam. A method of performing exposure using a variable rectangle, a so-called transmission mask reduction transfer exposure method using charged particles, has been proposed.

FIG. 6 shows a schematic configuration diagram of a transmission mask reduction transfer exposure apparatus. Note that the description will be made assuming that electrons are used as charged particles. 13 is a transmission mask substrate (stencil mask). Electrons 1 emitted from an electron gun (not shown) are formed into a rectangular shape by a first rectangular aperture 2, and are irradiated onto an arbitrary block portion (repetitive basic pattern portion) on a transmission mask by a pattern selection deflector 3. do. after that,
The electrons patterned by the transmission hole pattern of the block part are reduced by the reduction lens 11"i?, and then the projection lens 1
2, and after the irradiation position is selected by the deflection system, the wafer 10
exposed to light.

FIG. 7 shows an example of the transmission mask substrate 13. The mask substrate 13 is made of Sl, and the wide part at the center is about Io.
The film is made as thin as pm. - electrons are irradiated at
Block portions 4, which are units to be exposed, are arranged in alignment with this portion.

Further, the block portion 4 is composed of a plurality of transmission holes 14.

Further, on the mask substrate 13, for a non-repeating pattern,
A variable rectangular aperture 5 (a quadrilateral-shaped transmission hole without a pattern) is also provided. Reference numeral 6 on the transmission mask in FIG. 6 is an adjustment mark pattern for adjusting the pattern selection deflector 3.

Although this conventional example shows an example in which the transmission mask 13 is made of a semiconductor such as Si, for example, a plurality of transmission hole pattern parts may be formed in a metal plate or the like.

[Problem to be solved by the invention]

In this exposure method, a pattern is shaped using a transmission mask 13. Therefore, the block portion 4 of the transmission mask is constantly irradiated with the charged particle beam during exposure. As a result, the carbon components of the residual gas in the vacuum and the organic components volatilized from the grease used for vacuum sealing, etc., are deposited in a form that burns onto the areas where the charged particles are irradiated. It ends up.

After that, the vapor-deposited contaminants on the transmission mask part cause charge-up, which causes the charged particle beam to waver on the mask. As a result, problems have arisen in that the exposed position on the wafer is shifted and the exposed pattern is deformed.

Further, as shown in FIG. 7, since the pattern is formed in a thinned pattern forming area, there is a problem in that the strength is weak. A mask using a metal plate or the like will not be damaged in terms of strength, but it has the problem of being easily bent because it is used in a thin film due to the pattern to be formed. Furthermore, since the mask is thin, it is inconvenient to handle.

SUMMARY OF THE INVENTION An object of the present invention is to provide a charged particle beam exposure apparatus that facilitates mask alignment and that does not stain a transmission mask and is easy to handle.

[Means to solve the problem]

The present invention provides a transmission mask in which a pattern group consisting of a collection of several design patterns for shaping the cross-sectional shape of the beam is provided at a position through which the charged particle beam passes, and is exposed by the charged particle beam transmitted through the transmission mask. In the charged particle beam exposure apparatus, the transmission mask includes a mask support plate on which heater wires for heating the transmission mask and electrodes for conducting electricity to the heater wires are formed, and whose shape is standardized in advance, and the pattern. The problem is solved by a charged particle beam exposure apparatus comprising a transmission mask substrate in which groups are formed, and the transmission mask substrate is attached to the mask support plate in close contact with the mask support plate.

[For production]

According to the present invention, since the size and shape of the mask support plate are standardized, the mask substrate attached to it can be easily handled, such as positioning during exposure. This reduces the amount of dirt on the transmission mask substrate caused by the charged particle beam.
Furthermore, the generation of a magnetic field due to the current applied to the heater for heating can be made negligible. As a result, a stable pattern with stable reliability can be exposed.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a perspective view of a mask support plate for explaining a transmission mask according to the present invention.

As shown in FIG. 1A, the support plate of the transmission mask used in the present invention has a structure in which the ε-ter wiring 22 is embedded in, for example, a ceramic plate whose width a-b and thickness h are standardized. An opening is provided in the center of the support plate through which charged particles shaped by a mask pass. The heater wire is wired around the opening so as to surround the opening. Further, an electrode 24 for supplying current to the wiring is formed around the support plate. Further, if necessary, wiring for a thermocouple for measuring the mask temperature and electrodes 25 and 26 for the thermocouple for measuring the potential difference are provided on the mask support plate.

By the way, the current applied to the heater wiring for heating heats the transmission mask portion and at the same time generates a magnetic field on the transmission mask. As a result, the charged particles irradiated onto the transmission mask portion may be irregularly bent and may no longer follow a normal trajectory. In order to avoid this situation, it is better to wire the heater wiring so that the two wires going back and forth across the support plate are lined up as closely as possible to cancel out the generation of the magnetic field, as shown in Figure 1B. 0 with a line about 1mm wide
．． It is effective to wire at a pitch of about 5 m.

Furthermore, as shown in FIGS. 3A and 2B, the heater wiring for heating the transmission mask formed on the support plate consists of an upper layer wiring and a lower layer wiring arranged in two different planes, and the current flowing through the upper and lower wirings. has an inverted structure. Such a structure in which currents are directed in opposite directions can prevent generation of a magnetic field. This structure can be created by forming two thin films patterned with heater wiring, sandwiching a thin ceramic plate between the films, and sintering them. When a heater wire with a thickness of 100 mm was sandwiched between ceramic plates with a thickness of about 50 mm, the magnetic field generated by the heater wire was almost zero, and there was no effect on charged particles.

A mask having a transparent hole pattern shown in FIG. 7 is attached to this support plate so that the pattern forming area substantially overlaps with the opening on the support plate. Usually, the mask plate is attached to the support plate by adhering it tightly to the support plate in order to improve the heating efficiency of the heater. However, if this point is taken into consideration, such as by attaching it through a heat-conducting supplementary material, or if it is used at a low temperature, it can be attached using a holding plate or screws. good.

During charged particle beam exposure, the transmission mask is used in a heated state. The best temperature is about 300 to 600°C. The higher the temperature, the greater the effect of preventing contamination. However, the temperature of the part originally irradiated with charged particles is 40℃ due to the irradiation.
Since it is heated to about 0 to 700 degrees, if it is heated above 600 degrees, there is a possibility that the thinned mask part will be damaged (melted). Furthermore, if the temperature is below 300 degrees, the effect of preventing contamination will be reduced. This temperature is controlled using a thermocouple or the like. This thermocouple may be patterned on the mask support plate for detection, or may be brought into contact with the mask from the outside. When patterning a thermocouple, it is preferable to form the thermocouple so that its junction is in contact with the transmission mask in order to accurately measure the temperature of the transmission mask. Otherwise, the temperature of only a portion of the heater will be measured, making temperature control difficult.Since the heater is wired to surround the area around the opening, the area where the pattern is formed is the deflection area. The entire area is heated almost uniformly. Therefore, the transmission pattern can be selected as before using the pattern selection deflector 3 without worrying about the deflection position 1.

By doing this, carbon components of residual gas and organic components volatilized from grease used for vacuum sealing are difficult to be deposited on the transmission mask.

By the way, since the temperature of the mask is 300 to 600°C, the heat spreads to the mask placement mechanism that holds the mask support plate, and as a result, the mask placement mechanism becomes a movable stage. If this occurs, heat may be transmitted to the stage and interfere with operation.

Therefore, it is desirable that a heat insulating mechanism be provided on the mask support plate.

That is, in FIGS. 4A and 4B, a plurality of holes 30 are provided around the mask support plate 21 where the mask is installed, so that the heat from the mask heating section is spread over the entire mask support plate. As a result, it becomes difficult for heat to be transferred to the mask mounting mechanism.

Further, as shown in FIGS. 5A and 5B, the ceramic material surrounding the mask installation area may be made of two types of materials: a ceramic material surrounding the mask installation area and a material having a different thermal conductivity. For example, it is preferable to use zirconia or the like.Furthermore, as shown in the figure, if the ceramic material of the heater part and the ceramic material of the peripheral part are brought into point contact, an even more heat insulating effect can be obtained.

In this embodiment, holes are made on all sides surrounding the mask position, but holes may be made only on specific sides. For example, such a heat insulating mechanism may be provided only in the direction where the mask placement mechanism is installed, and the other areas may be left open.
A heat dissipating part may be installed to dissipate heat.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to heat the mask substrate through the mask support plate, thereby reducing contamination of the transmission hole pattern portion. Furthermore, since it is now possible to use a heated mask for exposure while controlling the temperature, beam fluctuations caused by dirt are eliminated, making it possible to draw reliable and stable patterns. Ta.

Furthermore, we were able to realize a system that does not have any effect on the mask mounting mechanism even if the mask is heated. In addition, the mask support plate has been standardized, and the transparent mask substrate is installed and used on the support plate, making it easier to handle.

[Brief explanation of the drawing]

1A, 1B, and 2 are perspective views of a semiconductor wafer on which a mask support plate and a stencil portion are made, respectively, for explaining a stencil transmission type mask according to the present invention; FIGS. 3A and 3B 4A, 4B and 5A, 5B are plan side views for explaining other embodiments of the mask support plate according to the present invention, and FIG. 6 is a conventional transmission mask. FIG. 7 is a schematic configuration diagram for explaining a reduction transfer exposure apparatus, and FIG. 7 is a perspective view showing an example of a substrate of a conventional transmission mask. DESCRIPTION OF SYMBOLS 1... Electron, 2... First rectangular forming aperture, 3... Deflector for aperture selection 4... Basic pattern for repetition, 5... Variable rectangular aperture, 8.9... - Irradiation optical system lens, 10... Wafer, 11... Reduction lens, 1
2... Projection lens, ■3... Transmission mask MM, (stencil mask), 1
4... Hole, 21... Mask support plate, 2
2... Wiring for heater, 23... Opening, 24, 26... Electrode, 2
5... Thermocouple wiring, 3o... Hole, 31... Vacuum, 32... SiN plate, 33... A 1 z
Ch board. Fig. 2 Fig. 3A Fig. 3B Fig. 28... Wafer Fig. 4B Fig. 5A Fig. 5B Fig.

Claims (1)

[Claims] 1. A transmission mask is provided at a position through which the charged particle beam passes, in which a pattern group consisting of a collection of several design patterns for shaping the cross-sectional shape of the beam is formed, and the beam is transmitted through the transmission mask. In a charged particle beam exposure apparatus that performs exposure using a charged particle beam, the transmission mask has a mask support formed with heater wires for heating the transmission mask and electrodes for conducting electricity to the heater wires, and whose shape is standardized in advance. A charged particle beam exposure apparatus comprising a plate and a transmission mask substrate on which the pattern group is formed, the transmission mask substrate being attached to the mask support plate so as to be in close contact with the mask support plate. 2. The heater wiring for heating the transmission mask is characterized in that it consists of an upper layer wiring and a lower layer wiring formed in two different planes so as to overlap one another, and the currents flowing through the upper layer wiring and the lower layer wiring are respectively reversed. A charged particle beam exposure apparatus according to claim 1. 3. The charged particle beam exposure apparatus according to claim 1, further comprising a heat insulating mechanism provided near the mask on the mask support plate.