JPS6313337B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an electron beam exposure apparatus that variably controls the size and shape of an electron beam to perform drawing exposure on a sample.

Various types of electron beam exposure equipment are used for microfabrication of semiconductor elements, mask substrates, etc., but recently a deflection system for beam shaping has been placed between two aperture masks, and the electron beam An apparatus that can perform more effective drawing exposure by variably controlling dimensions and shapes has been developed.

Incidentally, in such an electron beam exposure apparatus, in order to set the dimensions and shape of the electron beam with high precision, it is necessary that the parallelism between each aperture mask and the deflection system be matched. .
Conventionally, in order to adjust the parallelism, the aperture mask and deflection system are made to have a rotatable structure, and the dimensions are actually changed by forming an electron beam.If the parallelism is poor at that time, the aperture mask and deflection system are made to be rotatable, and if the parallelism is poor at that time, they are disassembled and rotated to adjust. After completing the above steps and assembling it, the electron beam is generated again. Furthermore, the aperture mask and deflection system are designed to be rotatable from outside the vacuum, so that they can be manually adjusted while observing the dimensions and shape of the electron beam. However, such a method requires a high degree of skill and is very troublesome. Furthermore, it takes a long time to perform highly accurate adjustment, resulting in problems such as a decrease in the operating rate of the apparatus.

The present invention was made in consideration of the above circumstances, and
The object is to provide an electron beam exposure apparatus that can automatically adjust the parallelism between an aperture mask and a deflection system in a short time, with high precision.

That is, the present invention is based on a target obtained by irradiating an electron beam onto a target formed by adhering fine particles with a large backscattered electron emission rate or secondary electron emission rate on a region with a small backscattered electron emission rate or secondary electron emission rate. An electron detector is provided to detect the reflected electrons or secondary electrons of The beam widths of each of the electron beams in the other direction are measured, and the parallelism between the aperture mask and the deflection system is determined from the relationship between the measured beam widths in the other direction and the set beam widths in one direction. This objective is achieved by determining the deviation θ, and feeding back this deviation θ to the deflection system to correct the same deviation θ.

Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

FIG. 1 is a schematic diagram showing an embodiment of the present invention. Electrons emitted from the electron gun 1 are irradiated onto a first aperture mask 2, shaped into a rectangle via an aperture mask 2a of the same mask 2, and deflected by a first deflection system 3 for beam shaping. irradiated onto the second aperture mask 4. The deflection system 3 consists of an X deflection plate 3a that deflects in the X direction and a Y deflection plate 3b that deflects in the Y direction, and each deflection plate 3a, 3b has a coordinate conversion circuit that applies each setting voltage given to the CPU 5. 6, respectively. The coordinate conversion circuit 6 converts each of the above-mentioned set voltages into appropriate voltages based on the deviation θ which will be described later.

Now, the electron beam irradiated onto the second aperture mask 4 is transmitted through the aperture 4a of the second aperture mask 4.
radiates downward through the The dimensions and shape of the electron beam are controlled by the effects of the aperture masks 2, 4 and the deflection system 3, as shown, for example, in the shaded area in FIG. The electron beam passing through the aperture 4a of the second aperture mask 4 is scanned and deflected by a second deflection system 8 for field scanning to which a deflection voltage is applied by a deflection voltage scanning circuit 7. (not shown)
The target 9 is irradiated through the beam. The target 9 is formed by adhering fine particles 9b having a high reflection electron emission rate, such as Au, on a substrate 9a having a low reflection electron emission rate, such as Be.

On the other hand, an electron detector 10 is disposed below the second deflection system 8. This electronic detector 10
The device detects reflected electrons from the target 9 obtained by irradiating the target 9 with an electron beam, and the detection signal is supplied to a wave memory 12 via an amplifier 11. wave memory 1
Reference numeral 2 captures the detection signal at regular sampling times and stores the distribution of the reflected electrons. Data acquisition into the wave memory 12 is performed in synchronization with voltage scanning by the deflection voltage scanning circuit 7 controlled by the CPU 5. Here, the detection signal of the electron detector 10 obtained by scanning the electron beam in the -X direction is the same as when the target 9 is moved in the X direction. Therefore, when each deflection voltage of the second deflection system 3 is kept constant and the electron beam is scanned in the -X direction, the distribution of reflected electrons as shown in FIG. 3 is stored in the wave memory 12. and,
The beam width Lx of the electron beam in the X direction in this case is measured from the distribution of the reflected electrons. In addition, if the S/N ratio of the detection signal obtained by scanning the target 9 once is poor,
Repeat beam scanning 100 times Wave memory 12
The required S/N ratio is obtained by averaging within the range.

The operation of this device configured in this way will be explained.

First, a constant voltage is applied to the X deflection plate 3a of the first deflection system 3, and a deflection voltage V _Y 4 that makes the beam width in the Y direction 4 μm is applied to the Y deflection plate 3b. Then, when the electron beam is scanned in the -X direction as described above, the beam width L _x 4 in the X direction is measured by the electron detector 11, wave memory 12, and CPU 5. Note that the dimensions and shape of the electron beam at this time are shown in FIG. 2 above.

Next, the beam width in the Y direction is set to 1μ on the Y deflection plate 3b.
When a deflection voltage V _Y 1 of m is applied and the electron beam is scanned in the −X direction, the beam width L _X 1 in the X direction is measured in the same manner as before. At this time, if the parallelism between the aperture masks 2 and 4 and the deflection system 3 is matched, the Y of the electron beam is as shown in FIG.
Only the beam width in the direction differs, and the beam width in the X direction does not change. In other words, L _X (4)=L _X (1).
In addition, each of the aperture masks 2 and 4 and the deflection system 3
If the parallelism between the beam and the beam is not matched, the beam width in the X direction will also differ (L _x (4)≠L _x (1)) as shown in FIG. The parallelism deviation θ _Y between the aperture masks 2, 4 and the Y deflection plate 3b at this time is given by the following equation, as is clear from FIG. 6, which is an enlarged view of FIG.

θ _Y =L _X (4) _−L
By applying the deflection voltages V _X 4 and V _X 1 that make the beam width in the
The parallelism deviation _θX with respect to the deflection plate 3a is given by the following equation.

_{θ _ _ _ _} X
This is the measured beam width of the electron beam in the Y direction for a beam width of 1 μm in the Y direction. Here, assuming that the degree of orthogonality between the X deflection plate 3a and the Y deflection plate 3b is determined with high precision, θ _Y =θ _X =θ. and,
_Based on this deviation _{θ , the voltages V}・cos θ−V _x・sin θ} The deviation θ will be corrected. Furthermore, if θ≪1, {V _X ′=V _X +V _Y θ ……(4) V _Y ′=V _Y −V _X θ}. Then, the transformation shown in equation (4) above is performed in the coordinate transformation circuit 6, and the voltages V _X ′ and V _Y ′ are applied to the deflection system 3, thereby correcting the deviation θ. become.

In this way, in this device, the beam width in one direction (X direction or Y direction) of the electron beam is set to different lengths, and the electron beam obtained by scanning the electron beam in the other direction (Y direction or X direction) is Detector 1
Each beam width in the other direction is measured from the backscattered electron detection signal of 0, and the aperture masks 2, 4 and Determine the deviation θ in the degree of flatness between the deflection system 3 and the deviation θ.
The coordinate conversion circuit 6 converts the voltage applied to the voltage as shown in equation (4) above to correct the deviation θ. Therefore, the aperture masks 2 and 4 can be used without requiring a high degree of skill or troublesome operation.
The parallelism between the deflection system 3 and the deflection system 3 can be automatically adjusted in a short time, with high precision, and automatically. For this reason,
The dimensions and shape of the electron beam can be controlled with high precision without reducing equipment operation rate.
This is extremely effective in forming fine patterns.

FIG. 7 is a schematic configuration diagram showing the main parts of another embodiment. Note that the same parts as in FIG. 1 are given the same reference numerals, and detailed explanation thereof will be omitted. This embodiment differs from the previously described embodiments in that the deviation θ is mechanically corrected. That is, the second deflection system 3 for beam shaping is fixed to the rotating body 13 and is rotatably provided. Furthermore, the rotating body 13 is a piezoelectric element 1 such as a bimorph element.
It is designed to be rotated by the expansion and contraction of 4. Then, the correction voltage based on the previous shift θ is applied to the piezoelectric element 1.
4, the deflection system 3 is rotated, and the deviation θ is corrected. In this case, the deflection voltage set by the CPU 5 is directly applied to the deflection system 3.

Even with such a configuration, the same effects as in the previous embodiment can be achieved.

Note that this invention is not limited to each of the embodiments described above. For example, the substrate constituting the target is not limited to Be, but may be any material with a low reflection electron emission rate. Further, the fine particles constituting the target are not limited to Au, but may be any fine particles having a high reflection electron emission rate. Further, a target can be formed by attaching fine particles having a high secondary electron emission rate to a substrate having a low secondary electron emission rate. In this case, the first electron detector may be one that detects secondary electrons. Furthermore, instead of the substrate constituting the target, the backscattered electron emission rate or
Any material having a planar region with a small secondary electron emission rate can be used instead. Further, the correction of the deviation θ may be performed separately using the X deflection plate and the Y deflection plate for each of the deviations θ _X and θ _Y in the X direction and the Y direction. Furthermore, the piezoelectric element is not limited to a bimorph element, and may be any element whose length can be varied depending on the applied voltage. Further, the deviation θ may be corrected only after disassembling the lens barrel, only after replacing the electronic mirror, or every time one sample is drawn. In addition, various modifications can be made without departing from the gist of the invention.

As described in detail above, according to the present invention, it is possible to provide an electron beam exposure apparatus that can automatically adjust the parallelism between an aperture mask and a deflection system in a short time, with high precision, and automatically.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram showing one embodiment of the present invention, Figs. 2 to 6 are diagrams for explaining the operation of the above embodiment, respectively, and Fig. 7 shows the main part of another embodiment. FIG. 1... Electron gun, 2... First aperture mask, 3... First deflection system (deflection system for beam shaping), 4... Second aperture mask, 5...
CPU, 6... Coordinate conversion circuit, 7... Deflection voltage scanning circuit, 8... Second deflection system (deflection system for field scanning), 9... Target, 10... Electronic detector, 12... Wave Memory, 14...piezoelectric element.

Claims (1)

[Claims] 1. An electron beam exposure apparatus in which a deflection system for beam shaping is arranged between first and second aperture masks having polygonal apertures to variably control the size and shape of the electron beam. An electron detector detects reflected electrons or secondary electrons obtained by irradiating a predetermined target with an electron beam, and a beam width in one direction of the electron beam is set to a different length, and means for measuring each beam width in the other direction of the electron beam based on each detection signal of the electron detector obtained by deflection scanning in the direction; and means for determining the deviation θ in parallelism between each aperture mask and the deflection system from the relationship with each beam width in one direction, and feeding back this deviation θ to the deflection system to correct the deviation θ. An electron beam exposure apparatus characterized by: 2 The target has a backscattered electron emission rate or 2
Backscattered electrons or two
2. The electron beam exposure apparatus according to claim 1, wherein the electron beam exposure apparatus is formed by attaching fine particles having a high secondary electron emission rate. 3. The correcting means is configured to rotate the deflection thread by expansion and contraction of a piezoelectric element, and applies a voltage based on the deviation θ to the piezoelectric element. term or second
The electron beam exposure apparatus described in . 4. The correction means converts the deflection signals Vx and Vy given from the CPU into the following coordinates: Vx′=Vx・cosθ+Vy・sinθ Vy′=Vy・cosθ−Vx・sinθ and supplies them to the deflection system. An electron beam exposure apparatus according to claim 1 or 2, characterized in that: