JP2719009B2 - Electron beam exposure method and electron beam irradiation device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam irradiation apparatus and an electron beam exposure method capable of obtaining a highly uniform resist pattern with good uniformity and significantly increasing the exposure processing speed in the semiconductor manufacturing field. About.

2. Description of the Related Art Generally, in the manufacture of an integrated circuit, exposure with an electron beam is used to form a highly accurate resist pattern.

In electron beam exposure, one of the causes of reducing the resolution of a resist pattern is a phenomenon in which an electron beam incident on a sample is scattered, and the dimensional accuracy of a fine pattern is reduced or the pattern is distorted due to the scattering. , Proximity effect. As a method for preventing such a proximity effect, there is a method (hereinafter, referred to as a ghost exposure method) of weakly exposing the inverted pattern portion with the same acceleration voltage as that of pattern exposure, but with a smaller dose. After performing normal pattern exposure on this kind of ghost exposure method,
There is a method of uniformly exposing the entire surface of the sample with the same irradiation means at a value of 30 to 50% of the exposure amount of the pattern portion (hereinafter referred to as a fog exposure method).

6 (a) to 6 (c) are process (cross-sectional) views showing a conventional resist pattern forming process, that is, a fog exposure method in the order of processes. The resist is a positive electron beam resist (hereinafter, simply referred to as a resist).

In FIG. 6, reference numerals 61, 61, 62, 63, 64, and 65 denote components, 61, 62, 63, and 64, respectively.

Next, the formation process of the above-mentioned conventional example will be described with reference to FIG.
This will be described with reference to the process charts of FIGS.

First, as shown in FIG.
Is used to expose the pattern portion 62a of the resist 62. Next, as shown in FIG. 6B, the entire surface of the resist 62 is irradiated with the electron beam 64 for full surface irradiation. The entire-surface irradiation electron beam 64 is a beam having a larger size than the writing electron beam 63, but cannot irradiate the entire surface of the sample at one time. The accelerating voltage of the entire-surface irradiation electron beam 64 is the same as that of the drawing electron beam 63, and the exposure amount is 30%. Irradiation of the whole-area irradiation electron beam 64 causes a non-drawing portion of the resist 62, a so-called inverted pattern portion 62b (an inverted pattern portion after fogging exposure)
Is very weakly exposed. Next, as shown in FIG. 6C, when the resist 62 is developed with a weak developing solution, a pattern 65 of openings corresponding to the exposed portions of the pattern portion 62a is formed.

However, in the above-described conventional method of forming a resist pattern, the exposure of the pattern portion and the exposure of the entire surface of the sample must be performed sequentially by changing the exposure amount with the same exposure apparatus. There is a problem that it takes a long time to expose one sample.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide an exposure method and apparatus capable of greatly reducing an exposure time required for forming a resist pattern and reducing a proximity effect.

Means for Solving the Problems In order to achieve the above object, the present invention divides exposure into a first step of irradiating a predetermined portion of a resist with an electron beam and a second step of irradiating the entire surface with an electron beam. In the second step of irradiating the entire surface with an electron beam, the plasma generating unit and the grid formed by arranging the stripe-shaped conductors so as to intersect with each other and connecting a power source to each of the stripe-shaped conductors And applying a voltage to a power supply to form a voltage distribution on a grid, and exposing the resist by an electron beam irradiation apparatus capable of controlling the amount of electrons separated from plasma passing through the grid.

Therefore, according to the present invention, normal pattern drawing is performed in the first step of irradiating a predetermined portion of the resist with an electron beam, and then pattern drawing is performed in the second step of irradiating the entire surface with an electron beam. Therefore, the time required for exposure is shortened accordingly. And according to the present invention,
In the electron beam irradiation apparatus used in the second step, the amount of electrons separated from the plasma that passes through the grid can be locally controlled by providing the grid with a voltage distribution. , A uniform electron beam can be obtained. Therefore, the entire surface of the substrate can be uniformly exposed to the electron beam, and a highly accurate pattern with little variation in pattern dimensions can be obtained.

Embodiment FIGS. 1A to 1C are process diagrams of forming a resist pattern according to an embodiment of the present invention. In FIG.
Reference numerals 11 indicate a substrate, 12 indicates a resist,
13 is an electron beam for drawing, A is an electron beam for whole surface irradiation, 15
Indicates a pattern portion.

Next, examples will be described with reference to process drawings. First
As shown in FIG. 1A, using the drawing electron beam 13,
The pattern portion 12a is exposed to the resist 12. Next, as shown in FIG. 1 (b), the collective irradiation electron beam A
Pattern, the reverse pattern portion 12b
Is very weakly exposed. The collective irradiation electron beam A may have the same acceleration voltage as the drawing electron beam 13 or may be higher or lower, and the exposure amount is 30 to 40% of the drawing electron beam 13. If the accelerating voltage of the collective irradiation electron beam A is too low, a portion of the resist 12 close to the substrate 11 may not be exposed. Next, when the resist 12 is developed with a weak developing solution, as shown in FIG.
Is formed.

Table 1 shows an example of comparing the exposure time according to the present invention with the exposure time according to the conventional method.

As is evident from Table 1, the present invention achieves a significant reduction in the time required for exposure.

FIGS. 2 (a) and 2 (b) and FIGS. 3 (a) and 3 (b) are cross-sectional views of a resist pattern formed by an electron beam exposure method according to an embodiment of the present invention and accumulation of electrons in an inverted pattern portion. The distributions of the energy are shown in (a) and (b) in correspondence with each other.

FIG. 2 shows a case where the exposure method of the present invention is applied to a positive resist by increasing the accelerating voltage of the entire-surface irradiation electron beam from the drawing electron beam. FIG. 2 (a) is a cross-sectional view of the resist. FIG. 2 (b) is a distribution diagram of the stored energy of electrons in the resist. In FIG. 2, reference numeral 21 denotes a portion where the stored energy is small, and 22 denotes a portion where the stored energy is large. Is promoted, so that the side surface of the pattern portion becomes nearly vertical.

As a method for obtaining the distribution of the stored energy of electrons as shown in FIG. 2 (b), the application of the resist is divided into two times, and after the first application, the entire surface is irradiated with an electron beam. The resist may be applied a second time, and then the pattern may be drawn with an electron beam. In this case, the acceleration voltage of the electron beam for full-surface irradiation may be lower than the acceleration voltage of the electron beam for pattern writing.

FIG. 3 shows the case where the exposure method of the present invention is applied to a negative resist by lowering the acceleration voltage of the electron beam for full-surface irradiation than the electron beam for writing. FIG. 3 (a) is a sectional view of the resist. FIG. 3B shows the distribution of the stored energy of electrons in the resist. In FIG. 3 (a), reference numeral 31 denotes a portion having a large amount of stored energy, and 32 denotes a portion having a small amount of stored energy. Since the dissolution of the resist is suppressed, the side surface of the pattern portion becomes nearly vertical.

As described in the description of FIGS. 2 and 3, according to the method of the present invention, since the side surface of the resist pattern is nearly vertical, the pattern dimensional accuracy is improved.

The electron beam exposure method according to the present invention can be applied to ion beam exposure and light exposure without changing the gist of the present invention.

FIG. 4 is a sectional view of an electron beam irradiation apparatus for irradiating the entire surface according to one embodiment of the present invention, and FIG. 5 is a partially cutaway perspective view showing a grid structure of the embodiment shown in FIG.
In FIG. 4, each of the components denoted by reference numerals is 41
Is a plasma generating portion having a pair of electrodes 41a and 41b, 42 is a grid, a stripe electrode group 42a in the X direction, a stripe electrode group 42b in the Y direction, and a hole group 4 provided in the grid 42.
2c, 43 is an anode 43a and a hole 43a _{1 of the} anode 43a.
A high-acceleration section consisting of 44, a sample, 45 a gas inlet, 46 a power supply for plasma generation, 47 a power supply for grid voltage application, X
A power supply 47a for controlling the direction electrode group 42a, and a Y direction electrode group
A power supply 47b for controlling 42b, a power supply for anode 48,
49 denotes an exhaust port, and 50 denotes a sample stage.

Next, the operation of the electron beam irradiation apparatus of the above embodiment will be described. In the above embodiment, plasma is generated by introducing an inert gas such as argon (Ar) from the gas inlet 45 and applying a voltage (either DC or AC) between the electrodes 41a and 41b with the power supply 46. Let it.

A suitable positive voltage for the electrode 42a with respect to the electrode 41a, for example, 20 V
Is applied by the power supply 47a, and then the electrode is applied to the electrode 42a.
When an appropriate positive voltage, for example, 10 V, is applied to 42b by power supply 47b, electrons pass through hole 42c in an amount corresponding to the voltage determined by power supplies 47a and 47b.

Electrons extracted from the plasma are accelerated by a power supply 48 at a suitable positive voltage applied to the grid 42 and the anode 43a, for example, 4 to 5 kV. The anode 43a is a mesh-like net or a plate in the form of a hole, whereby electrons are irradiated on the sample 44 as a parallel beam with the grid 42.

In FIG. 5, at reference numeral, 52a stripe electrodes in the X _{direction, 52a 1, 52a 2, ......} 52a N individual stripes, 52
b is the Y direction of the stripe _{electrodes, 52b 1, 52b 2, ......} 52b N
Individual stripes, 52c grid of holes, 52c _11, 52c
₁₂ ,... 52c _1N indicate each hole. Stripe 52a
_1, 52a _2, ...... 52a _N power 57a _1, 57a _2, leads to ...... 57a _N, stripes _{52b 1, 52b 2, ...... 52b} N power 57a _1, 57
a ₂ ,... 57a _N , and by these, holes 52c ₁₁ , 5
2c ₁₂ ,..., 52c _1N ,..., 57c Controls the amount of electrons passing through the _NN .

By inserting an insulator 52d between the X-direction stripe electrode group 52a and the Y-direction stripe electrode group 52b, the mechanical strength of the electrode groups 52a and 52b can be increased.

Exhaust resistance can be adjusted by the size and number of holes 52c formed in the insulating layer 52d.
The difference in the degree of vacuum between 41 and the high acceleration section 43 can be maintained.

As is clear from the above embodiment, the electron beam irradiation apparatus according to the present invention takes out only electrons from the plasma and controls the voltage necessary for taking out the electrons for each place, so that the electron beam irradiation apparatus with a large area and good uniformity is obtained. Since a beam is obtained and a filament is not used, there is an effect that local thermal deformation is not caused in the sample.

Although the present invention has been described as an electron beam irradiation device, it can be used as an ion beam irradiation device by changing the polarity of a power supply.

Further, in the apparatus configuration of the present invention, an electron optical system is provided between the anode and the sample, and a control signal is applied to the grids in the X and Y directions, so that the electron beam irradiation apparatus of the present invention can be used as an electron beam batch exposure apparatus. It has the effect that it can be used as.

Further, if the sample stage in the above embodiment is revolved around itself, the uniformity of the electron beam with respect to the sample is further improved.

Effects of the Invention As is apparent from the above-described embodiment, the present invention has an effect that the exposure time can be reduced by performing the electron beam exposure for pattern drawing and the electron beam exposure for overall irradiation. In addition, a large-area plasma is used as an electron beam source, and a voltage distribution is created on a grid from which the electron beam is extracted, whereby the amount of the electron beam passing through the grid is locally adjusted to irradiate the substrate with a uniform electron beam. This has the effect that a uniform and high dimensional accuracy resist pattern can be formed.

[Brief description of the drawings]

FIG. 1 is a process chart of forming a resist pattern by an electron beam exposure method according to one embodiment of the present invention.
(B), FIGS. 3 (a) and 3 (b) are cross-sectional views of the corresponding resist patterns and distribution diagrams of stored energy according to each embodiment of the present invention, and FIG. 4 is electron beam irradiation in one embodiment of the present invention. FIG. 5 is a partially cutaway perspective view showing the structure of a grid in one embodiment of the present invention, and FIG. 6 is a process diagram of resist pattern formation by a conventional electron beam exposure method. 13,63 ... Electron beam for drawing, A, 64 ... Electron beam for whole surface irradiation, 15,65 ... Pattern part, 21,32 ... Part where stored energy is small, 22,31 ... Part where stored energy is large 41, plasma generator, 42 grid, 43 high accelerating section, 43a anode, 44 sample, 45 gas inlet, 46, 47, 48 power supply, 49 exhaust Mouth, 50 ... Sample stage, 52a, 52b ... X, Y direction stripe electrode group, 57a, 57b ...
… X, Y direction stripe electrode group control power supply, 52c …… Hole, 52d
...... Support.

Claims (2)

(57) [Claims] A first step of irradiating a predetermined portion of the substrate with an electron beam; and a second step of irradiating the entire surface of the substrate with an electron beam. In the second step, a plurality of first stripe-shaped conductive layers are formed. The body group and the plurality of second stripe-shaped conductor groups are arranged and arranged so as to cross each other to form a grid, and the voltage applied to the first and second stripe-shaped conductor groups is An electron beam exposure method, wherein the amount of electrons passing through the grid is controlled by controlling the location of the grid, and a uniform electron beam is applied to the entire surface of the substrate. 2. A plasma generating section, a plurality of first stripe-shaped conductor groups and a plurality of second stripe-shaped conductor groups are arranged side by side so as to intersect with each other.
And a grid in which each of the second striped conductors is connected to a corresponding power supply, and applying a voltage from the respective power supply to the first and second striped conductors, Means for controlling the amount of electrons separated from the plasma generator and passing through the grid by controlling the position of the grid for each location, and uniformly irradiating the substrate with an electron beam. Electron beam irradiation device.