JPS6230321A - Method and apparatus for exposure by electron beam - Google Patents

Abstract

PURPOSE:To enable the easy realization of reduction of a proximity effect, by utilizing a ghost effect without causing reduction of a throughput in a beam exposure process. CONSTITUTION:Exposure pattern data are converted into pattern data expressed in dots, and a converged beam B1 is applied in the form of a dot to a desired address unit position, while the irradiation by a non-converged beam B2 is conducted simultaneously. Thereby an area of exposure by the non-converged beam B2 thicker than the converged beam B1 turns to exist around a desired area (e.g. a rectangular pattern indicated by a solid line) of exposure by the converged beam. By this method, the outer side of the desired area of exposure is exposed uniformly by the non-converged beam B2, and a proximity effect is reduced by a ghost effect.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to an electron beam exposure method and an electron beam exposure method used for exposing an electron beam sensitive resist to draw a pattern, for example, in the manufacture of semiconductor devices. Regarding equipment.

[Technical background of the invention]

In general, when producing a photomask for semiconductor device manufacturing, a pattern is drawn by electron beam exposure on a mask glass substrate coated with an electron beam sensitive resist. When drawing patterns on a wafer using electron beam exposure, a proximity effect occurs in which areas close to the original exposure pattern area are exposed due to the effects of reflected electrons, etc. that occur during exposure, and the desired design rules are not met. pattern cannot be obtained.

As a method of correcting to reduce such a proximity effect, the following techniques have been announced.

(1) Prior to exposure, each exposure pattern is analyzed by computer simulation, and exposure/? For turns, pattern division is performed, and exposure is performed by changing the dose amount for each division pattern.

(2) First, a region other than the pattern region to be exposed is exposed with a non-convergent beam at a dose less than a desired amount, and then the exposed pattern region is exposed with a convergent beam to utilize the so-called ghost effect.

(3) After performing a computer simulation in the same manner as in the above (1), pattern size adjustment is performed for exposure patterns that are likely to cause a proximity effect, and each pattern is exposed at the same dose.

[Problems with background technology]

However, each of the above-described proximity effect correction methods (1) to (3) has the following problems. In general, electron beam exposure equipment for semiconductor device manufacturing requires the required exposure/'
Since the number of P-turn figures is currently on the order of hundreds of thousands to millions, it is necessary to process the simulation in method (1) at high speed on a mainframe computer.
Equipment becomes expensive. Furthermore, exposing divided patterns at different doses as in method (1) requires additional control of the parameters of the electron optical column system in the electron beam exposure device during exposure, and vector scanning is required. A type exposure device is not subject to any major restrictions, but a raster scan type exposure device, which is found in many commercial machines, requires an extremely long exposure time, which is extremely disadvantageous in terms of the throughput of the exposure process. In addition, in method (2) above, it is necessary to perform exposure twice, so the exposure time is 2 times.
In the middle of the first and second exposure, is the electron optical lens barrel system connected? Since parameter control is added, a configuration is required to control the exposure position with high accuracy on the order of 0.01 μm. In addition, the method (3) above is
Similar to method (1) above, it requires a mainframe computer, and when processing the pattern size, it must be done in address units, so if high precision is to be achieved, addresses in finer units are required. need to be converted into units. However, as the throughput decreases with miniaturization of the address unit, adjustment must be made between miniaturization of the address unit for proximity effect correction and throughput.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and includes an electron beam exposure method and an electron beam exposure method that can easily reduce the proximity effect by utilizing the ghost effect without causing a drop in nurp in the beam exposure process. A beam exposure device is provided.

[Summary of the invention]

That is, in the electron beam exposure method of the present invention, a focused electron beam is irradiated onto a desired address unit position on an electron beam sensitive resist surface, and at the same time, an unfocused electron beam is irradiated around the address unit. It is characterized by this. ``Thus, the proximity effect is reduced due to the ghost effect outside the exposure pattern area, and the throughput of the exposure process is not reduced.

Further, in the electron beam exposure apparatus of the present invention, a plurality of non-converging electron beam passing holes are formed around the converging electron beam passing hole of the objective aperture, and the non-converging electron beam passing through the non-converging electron beam passing holes is A control electrode for controlling the trajectory is provided below the objective armature/4'-cha.

Therefore, the effects of the electron beam exposure method of the present invention can be obtained even though the configuration of the conventional electron beam exposure apparatus is only slightly changed.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

Figure 1 shows a part of the inside of an electron optical column in an electron beam exposure system, where 1 is a coil for forming an objective lens, 2 is an objective aperture, and 3 is a sample on a sample stage (on which an electron beam sensitive resist is coated). semiconductor wafers, mask substrates for semiconductor device manufacturing, etc.). For example, as shown in FIG.
．． (Center hole, main hole) 210 and multiple (for example, 4 to 8) non-converging electron beam passing holes (sub-holes) 2! ... is formed. Further, an objective aperture J is provided between the objective aperture 2 and the sample 3.
? A control electrode 4 is provided for controlling the irradiation position of the non-convergent beams B, . . . by bending the trajectory of the non-convergent beams B, .

This control electrode 4 is connected to the convergent beam B! that has passed through the center hole 21 of the objective aperture 2! A non-convergent beam B2 is placed around the irradiated position (address unit).
A control voltage input is applied to irradiate. This applied potential changes depending on, for example, the beam acceleration voltage and beam blanking speed in the electron optical column system. Therefore, as shown in FIG. 3, for example, a data table regarding the control voltage input is stored in, for example, a boron disk device 31, and a central processing unit (CPU) 32 of the control section for the electron beam exposure position performs the exposure. The optimum value is selected from the above data table according to the conditions, and the optimum value data is converted into a digital-to-analog (D/A) converter into an analog voltage and applied to the control electrode 4. There is.

Next, an electron beam exposure method using the electron beam exposure apparatus having the above configuration will be explained. Electron beam exposure equipment is the best for exposure! Turn data is expressed in dots/I
The data is converted into P-turn data (dot data), and as shown in FIG. 4, a focused beam B is irradiated to a desired address unit position in the form of a dot, and at the same time, irradiation is performed by a non-focused beam B2. As a result, around the desired exposure area (for example, a rectangular pattern shown by a solid line) by the convergent beam B1, there is an exposure area by the non-convergent beam B2 which is thicker than the convergent beam. Therefore, the area outside the desired exposure area is By being uniformly exposed to the non-convergent beam B2, the influence of the proximity effect is reduced due to the ghost effect.

In addition, the above-mentioned electron beam exposure method uses computer simulations related to the proximity effect on exposure pattern data. It does not require turn division or pattern size processing, it does not require control to change the dose amount during exposure, it does not require two exposures, it only requires one exposure, and it is similar to the conventional proximity effect correction method. It can be easily executed compared to the above.

Further, in the above-mentioned electron beam exposure apparatus, a plurality of non-convergent electron beam passage holes 2 are provided around the convergent electron beam passage hole 21 for the existing objective aperture 2. , this objective a! - A control electrode 4 is provided for bending the trajectory of the unfocused electron beam so that the unfocused electron beam that has passed through the chamber 2 is irradiated around the position (address unit) irradiated by the focused electron beam. It requires only a few modifications to the conventional electron beam exposure apparatus, and can be realized easily and inexpensively.

FIG. 5 shows the measurement results (solid lines A and B) of pattern dimension exchange differences for each pattern dimension of patterns drawn using the two types of electron beam exposure apparatus according to the present invention, and those drawn using the conventional electron beam exposure apparatus. Measurement results when drawn (solid line A).

B') is shown in comparison. Here, conventionally, the distance between a pattern of 5 μm or more and a pattern of 2 μm is ~0.1 μm.
While a dimensional conversion difference of m (mainly due to the intra-pattern proximity effect due to the contribution of reflected electrons) occurs, in the device of the present invention, the above dimensional conversion difference is ~0.03μ due to the ghost effect.
It can be seen that the improvement was achieved within m.

〔Effect of the invention〕

As described above, the present invention provides an electron beam exposure method and an electron beam exposure apparatus that can easily reduce the proximity effect by using the ghost effect without reducing throughput in the beam exposure process i. It is possible to provide

[Brief explanation of drawings]

FIG. 1 is a configuration explanatory diagram showing essential parts of an embodiment of an electron beam exposure apparatus of the present invention, FIG. 2 is a plan view showing an example of the objective aperture in FIG. 1, and FIG. 3 is a diagram showing an example of the objective aperture in FIG. 4 is a diagram showing the irradiation locus of beam exposure according to the method of the present invention, and FIG. 5 is a diagram showing actual measurement data regarding the reduction of the proximity effect by the apparatus of the present invention. FIG. 2... Objective aperture, 21... Convergent electron beam passage hole, 22... Non-convergent electron beam passage hole, 3... Sample, 4... Control electrode. Tagani's agent Patent attorney Takehiko Suzue Figure 3 Figure 4

Claims (2)

[Claims] (1) When drawing a pattern by electron beam exposure on a sample surface coated with electron beam sensitive resist, a focused electron beam is irradiated onto the desired address unit position and at the same time is not focused around the address unit. An electron beam exposure method characterized by irradiating with an electron beam of a state. (2) In an electron beam exposure device that draws a pattern by electron beam exposure on a sample surface coated with an electron beam sensitive resist, a plurality of non-convergent electron beam passage holes are formed around the convergent electron beam passage hole of the objective aperture. An electron beam exposure apparatus characterized in that a control electrode is provided below the objective aperture for controlling the trajectory of the unfocused electron beam that has passed through these unfocused electron beam passage holes.