JPH0451438A - Electron beam exposure device and method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] Regarding an electron beam exposure apparatus and exposure method having a cathode electrode formed of LaB6 or the like, the present invention aims to form an electron beam with high lung intensity and uniform electron irradiation distribution. A cathode electrode comprising a single crystal body provided with a protrusion having a flat surface at its tip, and a conductive protective film provided around the protrusion and having a surface substantially flush with the tip surface of the protrusion. Configure including.

C. Field of Industrial Application] The present invention relates to an electron beam exposure apparatus and an exposure method, and more particularly to an electron beam exposure apparatus and an exposure method equipped with a cathode electrode formed of lanthanum hexaborite or the like.

[Prior Art] Various electron beam exposure apparatuses have been proposed in which various patterns are formed on a transmission mask to shorten the exposure time.

In such a device, as shown in FIG. 7, electrons emitted from a cathode electrode K are passed through a grid G, an anode A, a converging lens L1, etc., and then patterned by a transmission mask M. through lenses L2, L3, aperture AP, etc.
It is configured to irradiate the area and form a latent image pattern thereon.

By the way, when the aperture pattern p provided in the transmission mask M is large, it is necessary to irradiate a uniform high-intensity electron beam over a wide area, but the more uneven the electron beam becomes, the lower the contrast becomes. The pattern accuracy of the latent image formed on the photo lens l-R will be reduced.

On the other hand, in order to improve the throughput, a photoresist is used, for example, a rectangular pattern of 3 x 3 μm2 and 1
Approximately 10M5h to expose for 1 second per crl
If an exposure rate of ot/sec is required and a photoresist with a sensitivity of 10 IC/cry is used, approximately 10
A current density of about 0 A/cm is required.

Here, if α is the electron beam convergence half angle and 8 is the brightness, then
The current density J is 1, J-πα2β, and if α is made too large, spherical aberration, chromatic aberration, and coma aberration, which cannot be dynamically corrected, will increase, so α cannot be set to 7 mrad or more.

Here, α is 8 mrad, and the current density J is 1.00
If A/CI is to be achieved, β should be 5X1015A.
/cJsteradian 2, for example I X 10
“It needs to be about A/cfflsteradian.

As a device for obtaining such conditions, a device using lanthanum hexaborite (1, aB6) for the quad electrodes has been proposed.

Note that polycrystalline LaB6 is unstable and quality control is difficult, so single crystalline LaB6 is used.

[Problem to be solved by the invention]

By the way, as shown in Figure 8, when a cathode electrode made of single crystal 1,aBb is made to have a sharp tip, the charge density at the tip becomes extremely high and electrons are distributed uniformly over a wide area. It becomes almost impossible to irradiate.

In addition, as shown in Fig. 9, the tip of the cathode electrode 2 has an opening angle of about 120° to 60°, and the tip is rounded.
Those with a radius of curvature of about 100 μm have relatively good uniformity of energy distribution, but with this type, the tip evaporates and the curvature changes over time, so exposure becomes less stable. In this case, if used at low temperatures, changes in curvature can be suppressed, but there is a disadvantage that brightness cannot be increased.

Furthermore, as shown in Fig. 10, a cylindrical shape with a flat tip,
3 has a prismatic cathode with a relatively uniform strength difference, and there is no need to take curvature into account. However, when this is used at high temperatures and high brightness, 1 and aB6 emanate from the side of the column and the tip Problems include a reduction in flat area and a change in electron distribution.

In contrast, as shown in FIG. 11, the periphery of the cylindrical or prismatic LaRb is covered with graphite C, and an opening H is provided in the center of the cylindrical or prismatic LaRb. 4 on the cathode electrode that prevented evaporation from.

However, due to the thickness of graph eye 1C, a step is created near the opening 11, so the electric field at the edge becomes non-uniform, and the electric field E formed in front of the cathode electrode 4 is disturbed. However, it is not possible to obtain a uniform electron distribution. In addition, since the opening I (is formed by etching the graphite C with oxygen plasma, the surface of LaB6 is oxidized by the oxygen plasma, reducing the electron generation efficiency. Furthermore, the oxidized L
When removing aB6, its surface is mechanically polished, but there is a problem that polishing is impossible because it is covered with graphite C.

By the way, the cathode electrodes 1 to 4 made of LaB6 constitute a three-electrode charged particle generation source with the grid G placed in front of them and the anode 8, and the electrons emitted from 4 to the cathode electrodes are The structure is such that the total amount of is controlled to be below a certain value by the grid G.

According to such a control method, a voltage is applied to the grid G to generate an electric field to form an electrostatic lens, and the electrons emitted only from the vicinity of the tip of the cathode electrode are temporarily focused as a crossover, but the electrostatic lens The spherical aberration coefficient is very large, and the brightness generally decreases to 1/3 or less. Furthermore, since electrons emitted from the surroundings are suppressed by the non-uniform electric field of the grid G, there is a problem in that it is difficult to emit uniform electrons.

The present invention has been made in view of these problems, and an object of the present invention is to provide an electron beam exposure apparatus that can form an electron beam with high brightness and uniform electron irradiation distribution.

[Means to solve the problem]

As illustrated in FIG. 1, the above-mentioned problem is solved by a single crystal body 2 provided with a protrusion 3 having a flat surface at the tip, and a single crystal body 2 provided around the protrusion 3 and approximately parallel to the tip surface of the protrusion 3. An electron beam exposure apparatus having a cathode electrode 1 and a conductive protective film 5 having surfaces that are coplanar; or, as illustrated in FIG. 3. A protective film 5 is provided on the four parts around the periphery, and electrons are emitted from the cathode electrode 1 formed by making the protective film 5 and the tip surface of the electron emitting part 3 substantially on the same plane, and pass through the slit of the anode electrode 7 as they are. This is achieved by an electron beam exposure method characterized by irradiating the transmission mask 16 and the photoresist R with the electrons.

[For production]

According to the present invention, the electron emitting portion 3 of the cathode electrode 1 is formed to protrude, and the protective film 5 is formed around it, and the protective film 5 and the tip surface of the electron emitting portion 3 are formed on substantially the same plane. I made it so that

Therefore, as shown in FIG. 3, an equipotential surface is formed in front of the surface from which electrons are emitted and the surfaces surrounding it, so the electric field is formed perpendicularly to the electron emitting surface without being disturbed. A substantially uniform electron beam without electron scattering is formed over a wide area.

Therefore, there is no need to particularly provide a grid for electron focusing between the cathode electrode 1 and the anode electrode, and there is no reduction in brightness due to the grid, and high brightness and uniform electrons are emitted from the anode.

As a result, the electron beam that has passed through the large-area aperture pattern provided in the transmission mask 16 has a uniform electron distribution with high brightness, as shown in FIG. 4(b), and the electron beam irradiates the photoresist R. It becomes possible to form fine patterns by increasing the contrast.

Furthermore, since the electron emitting surface of the cathode electrode 1 is flush with the protective film 5, even if LaB6 or the like constituting the electron emitting portion 3 is oxidized, the oxide can be easily removed by polishing. Moreover, since the protective film 5 is also removed during polishing, the flatness of the tip of the cathode electrode 1 is always maintained, and no disturbance of the electric field occurs.

[Example] The details of the present invention will be explained below based on the drawings.

FIG. 1 is a perspective sectional view showing the main parts of an apparatus according to an embodiment of the present invention, in which reference numeral 1 denotes a charged particle generation source 1, which will be described later.
The cathode electrode constituting 0 has a cylindrical single crystal body 2 made of LaB6, and a cylindrical electron emitting part 3 with a flat end is formed protruding from the center of one end of this single crystal body 2. Further, the surrounding area is covered with a conductive protective film 5 provided with an opening 4 through which the electron emitting section 3 is inserted.

This protective film 5 is formed of a material that causes a chemical reaction with the single crystal body 2 at the electron emission temperature and does not diffuse into it, such as graphite, diamond-like carbon, or carbon. The thickness is such that it forms almost the same plane as the end face of the.

6 is a conductive film that covers the side surface of the cathode electrode ■, and a protective film 5
, or a material that does not react with the protective film 5 and the single crystal 2 and does not diffuse into them.

FIG. 2 is a schematic diagram of an electron beam exposure apparatus, and this electron beam exposure apparatus consists of a charged particle generation source electrode 10 equipped with a quad electrode 1 shown in "1" and an anode electrode 7 attached in front of the quad electrode 1. have.

Further, in front of the charged particle generator rA10, there is a silicon slit 1-11 that shapes the electron beam irradiated from the electron emission part 3 of the cathode electrode 1 into a predetermined rectangular shape, and a silicon slit 1-11 that converges the shaped electron beam. One electronic lens 12
, a slit deflector 13 for correcting and deflecting the electron beam position, second and third electron lenses 14.15 provided opposite to each other, and the second and third electron lenses 14.15.
A transmission mask 16 is mounted so as to be movable in the horizontal direction between the
and first to third electron lenses arranged in the vertical direction of the transmission mask 16 to deflect the beam between the second and third electron lenses according to the respective position information and select a plurality of transmission patterns p in the transmission mask. 4 deflectors 17 to 20, a blanking 21 that blocks or passes the electron beam according to a blanking signal, a fourth electron lens 22, and an aperture 23.
It has a fifth electron lens 24, a sixth electron lens 25, a main differential coil 2G for positioning the electron beam 1 irradiated onto the substrate W, and a sub-deflector 27,
These are controlled by a control circuit (not shown) and are configured to irradiate the resist IR on the surface of the substrate W placed on the substrate mounting table 28 with an electron beam.

Next, the operation of the above embodiment will be explained.

First, for example, -
While applying a negative voltage of about 30 kV, a positive electrode is applied to the anode electrode 7 to emit electrons from the end face of the electron emitting part 3 at the tip of the cathode electrode 1. After passing through the slit of the anode electrode 7, electron beam to silicon slit 1
The beam is transmitted through one rectangular slit, then converged by the first electron lens 12, and its trajectory corrected by the deflector 13.

Then, the electron beam 1 that has passed through the second electron lens 14 is passed through the flowering pattern p of the transmission mask 1G to be shaped, and then moved to a desired position via the third electron lens 15, blacking 21, etc. By adjusting the timing and focus, the resist R is irradiated with an electron beam shaped by the transmission mask 16.

In this case, in the charged particle generation source 10, as shown in FIG. 3, an equipotential surface is formed that is parallel to the electron emitting portion 3 of the single crystal body 2 and the end surface of the protective film 2 around it. Since the electric field formed in front of the cathode electrode 1 is formed perpendicularly to the end surface of the electron emission part 3, the electron distribution is almost uniform over a wide area without scattering, as shown in FIG. 4(a). A high brightness electron beam can be obtained.

Therefore, there is no need to particularly provide a grid for electron convergence between the cathode electrode 1 and the anode electrode 7, and there is no reduction in brightness due to the grid, and high brightness and uniform electron emission can be obtained.

Moreover, since the periphery of the electron emitting section 3 is covered with the conductive protective film 5, the area does not decrease due to evaporation, and electrons are stably emitted.

Therefore, for example, a 3×3
The electron beam passing through the aperture p having an area of about .mu.m2 has a substantially uniform electron distribution as shown in FIG. 4(b), making it possible to expose the resist R with high contrast.

Next, a method for forming the above cathode electrode 1 will be briefly explained.

FIG. 5 is a sectional view showing a first example of the method for forming the cathode electrode 1. First, as shown in <a> of the same figure, La
After forming a circular resist mask 20 with a diameter of 1100 II at the center of one end surface of a columnar single crystal body 2 made of B6, the single crystal body 2 was etched by sputtering until a depth of 30 μm was reached, and then, The resist mask 20 is removed (FIG. 5(b)). As a result, a protrusion is formed at one end of the single crystal body 2, and this is used as an electron emitting part 3.

Next, a carbon film 21 of about 50 μm is deposited on the entire end of the single crystal body 2 by sputtering (FIG. 5(C)).
After this, the carbon film 21 is polished to expose the tip of the electron emitting part 3, and then further polished by about 10 μm to form pure i, a
Expose Ba. As a result, the tip area is approximately 7800
An electron emitting region of 11 m2 is formed, and its surroundings are covered with a protective film 5 made of carbon (Fig. 5(d)).
).

Although not particularly shown, this single crystal body 2 is penetrated by a conductor such as graphite in advance, and a conductive film 6 is formed around it.

FIG. 6 is a cross-sectional view showing a second example of the method for forming a cathode electrode, in which, as shown in FIG. An electron emitting portion 3 having a diameter of 10071 m and a height of 100 μm is formed protruding from the center thereof.

Further, a graphite plate having a thickness of 100 μm is processed and used as a protective film 5, and an opening 4 having a diameter of 110 μm is formed in the center thereof.

In this state, the electron emitting part 3 of the single crystal body 2 and the opening part 4 of the protective film 5 are aligned and pasted together using a machine adhesive, and then the electron emitting part 3 and the protective film 5 are polished. Flatten it (Fig. 6(b)).

In this way, a cathode electrode having a single crystal body made of LaB6 is prepared by applying a voltage of, for example, -3Q kV, heating it to 1600'C, and increasing the current density to 10A/cTM.
Electrons are emitted from the end face of the electron emitting portion 3, but when the electron emitting area of the single crystal is approximately 10100×10011, the emission current becomes 1 mA.

Therefore, the second
Although the silicon slit 11 shown in the figure is easily dissolved, in this embodiment, since the end area of the electron emitting portion is set to 10000 μm 2 or less, the silicon slit 11 is difficult to dissolve, and stable exposure can be performed.

Furthermore, since the end surface of the electron emitting portion 3 of the cathode electrode 1 is on the same plane as the protective film 5, even if 1, aB6 is oxidized, the oxide can be easily removed by polishing. Moreover, since the protective film 5 is also removed during polishing, the flatness of the tip of the cathode electrode 1 is always maintained, and no disturbance of the electric field occurs.

G In the above-described embodiment, both the cathode electrode 1 and the electron emitting section 3 are formed in a cylindrical shape, but they may also be formed in a prismatic or other shape.

Furthermore, in the above embodiment, the case where no grid is provided between the cathode electrode 1 and the anode electrode 7 has been described, but by providing a grid between them, the brightness can be increased to a certain degree and the electron distribution can be made uniform. It can be done.

[Effects of the Invention] As described above, according to the present invention, the electron emitting surface of the cathode electrode is formed to protrude, a protective film is formed around the electron emitting surface, and the protective film and the electron emitting surface are substantially the same. Since it is made flat, an equipotential surface is formed in front of the surface where electrons are emitted and the surrounding surfaces, so the electric field is formed perpendicularly to the electron emitting surface without being disturbed, so it can be applied over a wide area. It is possible to form a nearly uniform electron distribution without electron scattering and a high brightness electron beam, making it possible to form a large image with high contrast on the photoresist.

Moreover, since the electron emitting surface of the cathode electrode is on the same plane as the protective film, 1, ++ If + forming the electron emitting part
Even if + etc. are oxidized, the oxide can be removed into the cylinder by polishing, and since the protective film is also removed during polishing, the tip of the cathode electrode can always be kept flat.

[Brief explanation of drawings]

FIG. 1 is a perspective sectional view showing a cathode electrode of a device according to an embodiment of the present invention, FIG. 2 is a schematic configuration diagram showing a device according to an embodiment of the present invention, and FIG. 3 is a schematic diagram showing a device according to an embodiment of the present invention. FIG. 4 is an explanatory diagram of the operation of the device. FIG. 4 is an electron distribution diagram before and after the transmission mask of the device according to one embodiment of the present invention. FIG. 6 is a sectional view showing a second example of the method of forming a cathode electrode applied to the present invention, FIG. 7 is a schematic configuration diagram showing an example of the conventional device η, and FIG. 8 is a schematic diagram showing an example of the conventional device η. FIG. 9 is a cross-sectional view showing a first example of a charged particle generation source and its electron distribution diagram; FIG. 9 is a cross-sectional view showing a second example of a charged particle generation source of a conventional device and its electron distribution diagram; FIG. , a cross-sectional view showing a third example of a charged particle generation source of a conventional device and its electron distribution diagram, and FIG. 11 is a cross-sectional view showing a fourth example of a charged particle generation source of a conventional device and its electron distribution diagram. be. (Explanation of symbols) ■... Cathode electrode, 2... Single crystal, 3... Electron emission part, 4... Opening part, 5... Protective film, 6... Conductive film, 7 ...Anode electrode, 11...Silicon slit 1-1 16...Transmission mask, W...Substrate, R...Resist. One severance party

Claims (2)

[Claims] (1) A single crystal body provided with a protrusion (3) having a flat surface at the tip; (2) a single crystal body provided around the protrusion (3);
) An electron beam exposure apparatus having a cathode electrode (1) and a conductive protective film (5) having a surface substantially coplanar with the tip surface of the electrode. (2) Protrude the electron emitting part (3) and
) A protective film (5) is provided in the surrounding concave portion, and electrons are emitted from the cathode electrode (1) formed with the protective film (5) and the tip surface of the electron emitting portion (3) substantially on the same plane; The electrons are passed through the slit of the anode electrode (7) as it is, and the electrons are transferred to the transmission mask (16) and the photoresist (R).
) is an electron beam exposure method characterized by irradiating toward the target.