JPS6139728B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron beam exposure apparatus capable of adjusting exposure pattern dimensions in fine pitches.

2. Description of the Related Art When a pattern of a semiconductor integrated circuit is formed by exposure by irradiating an electron beam, this is conventionally done using a mask created using photophotography. For example 0.1
A plurality of aperture masks of about 2.0 μm formed with a dimensional difference of μm were prepared, and these masks were selected and used. This is to improve the yield of integrated circuits (LSI) by making the mask correspond to the state of the semiconductor substrate.

By the way, using masks alternatively as described above is extremely troublesome in terms of the manufacturing process. Therefore, an electron beam exposure apparatus was devised that forms a pattern by electrically deflecting and scanning the electron beam of the exposure apparatus.
However, this type of electron beam exposure apparatus has a major drawback in that it is not possible to finely change the minimum pattern size corresponding to the size of the mask. For this reason, this electron beam exposure apparatus has a problem in that it cannot be expected to improve the production yield.

The present invention has been made in consideration of these circumstances, and its purpose is to finely control the minimum pattern dimension of a pattern when the pattern is formed by electrically deflecting and scanning an electron beam. An object of the present invention is to provide an electron beam exposure apparatus that can improve the yield of patterns formed by exposure.

First, an overview of the present invention will be explained.

In a hybrid raster scanning type electron beam exposure system, a table on which a sample is placed is continuously moved in one direction, and an electron beam is deflected and scanned in a direction perpendicular to this moving direction. At this time, the scanning pitch of the electron beam is It is uniquely defined by the moving speed of the table, the time for one deflection scan of the electron beam, etc. Therefore, the scanning pitch of the electron beam cannot be changed unnecessarily, and it has therefore been impossible to finely control the minimum pattern size.

In the present invention, the deflection scanning distance and the scanning pitch are varied while maintaining a constant relationship between the deflection scanning distance and the scanning pitch of the electron beam. Furthermore, the starting point of deflection scanning of the electron beam is determined based on the moving distance of the table, which is the detection information of the laser length measurement system. Therefore, the scan pitch of the electron beam can be varied without requiring operations such as changing the table movement speed, and the size of the minimum pattern can be precisely controlled. Moreover, since the starting point of the deflection scan is determined based on the table movement distance, even if the table movement speed changes, the scanning pitch of the electron beam irradiated onto the sample does not change.

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

Figure 1 is a schematic system diagram of the present invention apparatus, which is a hybrid raster scanning type electron beam system that continuously moves a sample to be subjected to electron beam exposure in one direction and deflects and scans the electron beam in a direction perpendicular to this moving direction. It is a line exposure device. In the figure, 1 is an electron gun made of a tungsten cathode or the like, which outputs an electron beam. This electron beam passes between the blanking plates 2 and 2, is subjected to planking control, and then is passed through the condenser lens 3.
is focused through. This focused electron beam is deflected and controlled by passing between electrostatic deflection plates 4, 4, and then irradiated onto an object (sample) 6, such as a semiconductor element, through an objective lens 5. The object 6 to be exposed is an X-Y table 7 in a sample chamber (not shown).
It is moved by the table drive mechanism 8 in directions perpendicular to the irradiation direction of the electron beam and the scanning direction of the electron beam by the electrostatic deflection plates 4, 4, and is set in position. There is. The table drive mechanism 8 operates based on a movement control signal from the table movement control device 9.
Further, a laser reference mirror 10 is disposed on the side of the XY table 7, and a laser beam 11a is irradiated from the laser length measurement system 11. The laser beam 11a reflected by the laser reference mirror 10 is input to the laser length measurement system 11, and the moving distance of the XY table 7 is measured from the irradiation of the laser beam 11a and the reflected light.

On the other hand, the result of length measurement by the laser length measurement system 11 is supplied to a pulse generation circuit 12 and also to an operation control circuit (interface) 13. The pulse generating circuit 12 is configured to generate the laser beam 1.
When the wavelength of 1a is λ, a pulse signal is output every time the XY table 7 moves by m/n·λ. However, m and n are natural numbers, and these will be described later. This pulse signal acts as a synchronization signal for each section, which will be described later, and is input to the operation control circuit (interface) 13. This operation control circuit (interface) 1
3 operates the deflection control circuit 14 based on the synchronization signal, and supplies pattern information input from the pattern generator 15 to the drawing circuit 16. The table movement control device 9 is also supplied with synchronization signals, table movement command signals, and the like. Deflection control circuit 14 operated by a signal supplied from this operation control circuit (interface) 13
The electron beam is deflected by applying a deflection bias voltage between the electrostatic deflection plates 4, 4. Further, the drawing circuit 16 includes the blanking board 2,
A blanking voltage is applied between the electron beam and the electron beam to control blanking of the electron beam.

The device configured in this manner operates as follows. This effect will be explained with reference to FIG. By the operation of the table drive mechanism 8, the XY table 7
When the (exposed object 6) is moved, the moving distance is measured by the laser beam 11a from the laser length measuring system 11. This measurement result is input to the pulse generation circuit 12, and 1/n of the wavelength λ of the laser beam 11a is measured as a reference movement distance of the object 6, that is, a unit of movement distance. For example, a pulse signal is emitted every time the object 6 to be exposed moves a distance λ/n. This pulse signal is input to an m-bit counter (not shown) provided in the pulse generating circuit 12, and is counted m times. A synchronizing signal is output when the pulse signal is counted m times, that is, when the object 6 to be exposed moves a distance m/n·λ (unit movement distance). Note that the count number m is set via the operation control circuit (interface) 13. On the other hand, this synchronization signal causes the deflection control circuit 14 to control the electrostatic deflection plates 4 and 4.
A lamp voltage that is swept over time is applied as a deflection bias signal. The maximum signal level of this lamp voltage is proportional to the value of the set count number m. Therefore, the variation width of the deflection bias signal is proportional to the count number m, and the scanning deflection width of the electron beam is also proportional. Therefore, when the object 6 to be exposed moves a distance m/n·λ, the electron beam emitted from the electron gun 1 moves a distance K·m/n·λ in a direction perpendicular to the direction of movement of the object 6 to be exposed. Deflection scanned. However, K is a proportionality constant. That is, the set m is
When m ₁ , electron beam scanning is performed at a distance K·m ₁ /n·λ with respect to a scanning pitch m ₁ /n·λ, as shown in FIG. 2a. Further, when the number m ₂ <m ₁ is set, scanning with the electron beam of K·m ₂ /n·λ is performed with respect to the scanning pitch m ₂ /n·λ, as shown in FIG. As shown in this figure, by appropriately setting m, both the scanning pitch interval and the scanning width of the electron beam change proportionally.

On the other hand, the drawing circuit 16 also operates based on the synchronization signal. For example, every time the object 6 to be exposed moves a distance m/n·λ, a pattern generation signal from the pattern generator 15 is converted into a serial signal, shaped and power amplified, and applied to the blanking plates 2, 2. ing. This serial pattern signal has a time width corresponding to the deflection time by the electrostatic deflection plates 4, 4. Then, the voltage applied between the blanking plates 2, 2 is turned off and on, and the passage of the electron beam is turned off and on. In other words, when the information signal of the pattern signal is input, the blanking plates 2, 2
Stop applying voltage between the two and allow the electron beam to pass through. When a non-information signal of the pattern signal is input, a voltage is applied between the blanking plates 2, 2 to prevent the electron beam from passing through. Therefore, by operating the drawing circuit 16, a pattern signal, that is, a pattern, issued from the pattern generator 15 is formed on the object 6 to be exposed.

As described above, according to the present apparatus, the exposure irradiation range of the electron beam is set depending on the value of m that is set. The scanning width of the electron beam also changes in proportion to the change in the moving distance of the object 6 to be exposed. In other words, the range scanned and exposed by the electron beam changes while maintaining the aspect ratio (ratio of moving distance to scanning width). Therefore, it is possible to perform exposure by varying the electron beam scanning pitch without changing the moving speed of the table 7. Further, the rate at which the scanning pitch changes can be changed by 1/nλ with reference to the wavelength λ of the laser beam 11a. For example, the laser length measurement system 11 measures the length using a laser beam 11a with a wavelength λ of 6328 Å, and has a length measurement accuracy of n=48.
(For example, when using YHP's laser length measurement system), by changing m one by one,
The pattern dimensions can be changed by 6328/48≒132Å. In the case of such a system, if one pattern is formed by four electron beam scans, the width of approximately 500 Å in the direction of movement of the exposed object 6 is
A pattern can be formed by changing the .

However, according to this apparatus, if a pattern with a pattern size of 2 μm is formed on a semiconductor substrate and the yield is poor, the pattern size can be changed by resetting the value of m set above. It can be easily reduced to 1.9 μm. This reduction of 0.1 μm reduces the pattern formation area of the semiconductor substrate to approximately 10 μm.
% will also be reduced. By reducing the pattern formation area by approximately 10%, the degree of occurrence of defective patterns, such as defects due to pinholes, etc., is extremely reduced. Therefore, the yield in manufacturing is significantly improved. For example, it works extremely effectively for patterning ultra-highly integrated semiconductors (LSI).

In addition, since the moving distance of the table 7, that is, the ratio of the scanning pitch of the electron beam to the deflection scanning distance can be kept constant and proportionally reduced, there is almost no need to change the exposure data software. , it is possible to proportionally reduce the exposure pattern. Furthermore, since the deflection scanning of the electron beam is performed based on the moving distance of the table 7, which is the detection information of the laser length measurement system 11, even if the moving speed of the table 7 changes for some reason, the scanning pitch will not change. Inconvenience can be avoided. Therefore, highly accurate exposure can be performed regardless of fluctuations in the moving speed of the table 7. Furthermore, since the scanning pitch can be easily varied, it is possible to eliminate exposure unevenness determined by the relationship between the beam width of the electron beam and the scanning pitch.

Note that the present invention is not limited to the above embodiments. In the above embodiment, the laser length measurement system 11 is used as the length measurement system, but a length measurement system using a moiré pattern may also be used. In addition, the stable laser wavelength λ was used as the standard moving distance unit, but
Others may be used. Furthermore, the rate of change in the exposure pattern, the pattern range, etc. may of course be set as appropriate depending on the specifications and usage. As described above, the present invention can be implemented with various modifications without departing from the spirit thereof.

As detailed above, according to the present invention, each time the table on which the sample is placed moves a unit movement distance,
Since the electron beam is deflected and scanned by a distance proportional to the unit movement distance in a direction perpendicular to the movement direction, by finely changing the unit movement distance, the dimensions of the pattern to be exposed can be adjusted. It can be changed in minute units. Therefore, for example, it is possible to expose a pattern with optimum pattern dimensions for the state of the semiconductor substrate to which the pattern is exposed, and the yield can be significantly improved. In addition, the moving distance of the table is detected by a laser length meter, and the deflection scanning and deflection scanning distance of the electron beam are determined by comparing this detected moving distance with the set unit moving distance, so exposure accuracy is This has effects such as being able to improve performance.

[Brief explanation of the drawing]

FIG. 1 is a schematic system diagram showing one embodiment of the apparatus of the present invention, and FIG. 2 is a diagram for explaining the operation of the same embodiment. 6... Object to be exposed, 7... X-Y table, 8... Table drive mechanism, 11... Laser length measurement system, 12... Pulse generation circuit, 14... Deflection control circuit.

Claims (1)

[Scope of Claims] 1. In an electron beam exposure apparatus that moves a table on which a sample to be subjected to electron beam exposure is placed in one direction, and deflects and scans an electron beam in a direction perpendicular to the direction of movement of the table, a laser length measuring system for detecting a moving distance of the table; a means for variably setting a unit moving distance of the table; and a means for variably setting a unit moving distance of the table, each time the moving distance detected by the laser length measuring system matches the set unit moving distance. a pulse signal generating circuit that generates a pulse signal, a means for deflecting and scanning the electron beam in synchronization with the pulse signal, and a means for varying the polarization scanning distance of the electron beam in proportion to the set unit movement distance. and means for controlling the blanking timing of the electron beam in synchronization with the pulse signal. 2. The electron beam according to claim 1, wherein the deflection scanning distance of the electron beam is proportional to the unit movement distance with reference to the laser beam wavelength of the laser length measurement system. Exposure equipment. 3 When the laser beam wavelength of the laser length measurement system is λ, the unit moving distance of the table is m/n・λ (where m and n are natural numbers), and the deflection scanning distance of the electron beam is K・m/ 3. The electron beam exposure apparatus according to claim 2, wherein the electron beam exposure apparatus is set to n·n (where K is a constant).