JP3908294B2 - Electron beam exposure apparatus and electron beam exposure method for reducing current amount of electron beam - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electron beam exposure method and apparatus, and more particularly to an electron beam exposure method and apparatus that require a high acceleration voltage for the electron beam.
[0002]
[Prior art]
An electron beam exposure method using an electron beam for exposure of a sample has been realized as a semiconductor microfabrication technique for improving the degree of integration of ICs. As an electron beam exposure method capable of processing with high throughput and high accuracy, there are a variable rectangular exposure method, a block exposure method, a blanking aperture array (BAA) exposure method, and the like.
[0003]
FIG. 7 shows an exposure column portion (optical system) 110 of a conventional block exposure type electron beam exposure apparatus. The exposure column unit 110 includes an electron beam generation source (electron gun) 114 having a cathode electrode 111, a Wehnelt 112 and an anode 113. The exposure column unit 110 further includes a first slit 115 that shapes the electron beam into, for example, a rectangular shape, and a first electron lens 116 that converges the shaped beam. The exposure column section 110 further includes second and third lenses 118 and 119 provided opposite to each other, and a block mask 120 mounted between the second lens and the third lens so as to be movable in the horizontal direction. . On the block mask 120, transmission holes of various patterns are provided. One of them is selected, the electron beam is deflected using the first to fourth deflectors 121, 122, 123, and 124, and the electron beam is irradiated to the transmission holes of the selected pattern. As a result, an electron beam having the shape of the selected pattern is formed. The exposure column unit 110 further includes a blanking 125 for blocking or passing the beam according to a blanking signal, a fourth lens 126 for reducing the beam, a round aperture 127, and a fifth lens 129. The exposure column unit 110 further includes a main deflector 133 and a sub deflector 134 for positioning the beam on the sample W, and a sixth objective lens 132 for projecting the beam onto the sample W placed on the sample stage 135. Including.
[0004]
In the BAA exposure method, a blanking aperture array (BAA) having a large number of apertures for forming a group of fine beams to be irradiated on the sample is arranged at the position of the block mask 120 instead of the block mask 120. . In the variable rectangular method, a second slit for shaping the electron beam into a variable rectangular shape is arranged instead of the block mask 120.
[0005]
[Problems to be solved by the invention]
In the conventional electron beam exposure apparatus, components that limit the current value of the electron beam emitted from the electron gun 114 include 1) the first slit 115, 2) the block mask 120 (or BAA or second). There are three components: a slit, hereinafter referred to as an exposure pattern forming opening), and 3) a round aperture 127.
[0006]
When the electron beam is emitted from the electron gun 114, the electron beam having a current value of several hundred μA is cut by the first slit 115, and the current value of the passed electron beam is reduced to several tens μA. The electron beam having a current value of several tens of μA is applied to the block mask 120 (exposure pattern forming opening). For example, if the applied voltage is 50 kV and the current value is 20 μA, the block mask 120 (exposure pattern forming opening) may generate heat at 1.0 W.
[0007]
Of the three components that limit the current value of the electron beam, the first slit 115 and the round aperture 127 are made of a metal such as molybdenum or tungsten, so there is almost no risk of melting due to heat generation. However, the block mask 120 (exposure pattern formation opening) needs to be finely processed by semiconductor technology and is made of silicon. The melting point of silicon is 1440 degrees, and there is a risk of melting due to heat generated by electron beam irradiation.
[0008]
Therefore, as a problem of the conventional electron beam exposure apparatus, there is a risk of melting a block mask or the like due to a large current value of the electron beam.
The electron beam is also partially cut by the round aperture 127. Here, the round aperture 127 functions to cut the crossover image in order to limit the half angle of incidence of the electron beam on the sample. The crossover image is an image of the electron beam generation source 114. Even if the electron beam is cut at the position where the crossover image is formed, the image of the block mask 120 is not affected.
[0009]
The round aperture 127 is also used to completely cut (blanking) the electron beam. When the electron beam is blanked, the electron beam is deflected by the blanking 125, and the electron beam is completely cut off by removing the electron beam from the opening of the round aperture 127. However, since the electron beam has a spatially large Gaussian distribution, it is necessary to largely deflect the electron beam by the blanking 125 in order to completely remove the electron beam from the opening of the round aperture 127. Therefore, it is necessary to apply a large voltage to the blanking 125, and high-speed blanking operation is difficult.
[0010]
Since the electron beam partially cut by the round aperture 127 is not used for the sample exposure, it is an unnecessary portion that is not originally required. Moreover, because of this extra electron beam, high-speed blanking operation is hindered.
[0011]
Therefore, as a problem of the conventional electron beam exposure apparatus, there is an inhibition of a high-speed blanking operation due to an extra electron beam.
Further, the problem of contamination is further cited as an adverse effect of the electron beam containing an excess current. When the current value of the electron beam is large, there is a high possibility that contamination (such as dust floating in the exposure column part 110) is repelled by the electron beam and adheres to the components of the exposure column part 110. Furthermore, charges are likely to be accumulated in the contamination adhered to the constituent elements. The charges accumulated in this way are not preferable because the trajectory of the electron beam is distorted.
[0012]
Accordingly, an object of the present invention is to eliminate the risk of melting due to heat generation of components by cutting an extra electron beam in an electron beam exposure apparatus, enabling high-speed blanking operation, and further contamination. It is to reduce the possibility of Nation adhesion and charge accumulation.
[0013]
[Means for Solving the Problems]
According to the first aspect of the present invention, the electron beam emitted from the electron beam generation source is shaped by irradiating and passing through the exposure pattern forming aperture, and the sample is irradiated with the shaped electron beam for exposure. An electron beam exposure apparatus that performs the first has an electromagnetic lens that forms a crossover image, and a circular opening that shapes the electron beam by cutting a peripheral portion of the crossover image formed by the electromagnetic lens. An exposure pattern forming aperture that includes a plate and a second plate having an aperture that reduces the amount of current of the electron beam upstream from the first plate with respect to the flow of the electron beam. Irradiate.
[0014]
According to a second aspect of the present invention, there is provided an apparatus according to the first aspect, wherein a blanking electrode for deflecting the electron beam shaped by the exposure pattern forming opening for blanking and a deflected electron beam are provided. A round aperture for blocking and blanking, wherein the size of the circular aperture is such that the size of the electron beam shaped by the circular aperture at the position of the round aperture is approximately equal to the size of the round aperture. It is such a size.
[0015]
According to a third aspect of the present invention, in the apparatus according to the first or second aspect, the size of the opening of the second plate is larger than the circular opening of the first plate. The size of the electron beam emitted at an emission angle depending on the size of the opening satisfies the condition for uniformly irradiating the entire surface of the exposure pattern forming opening.
[0016]
According to a fourth aspect of the present invention, in the apparatus according to the third aspect, the opening of the second plate is circular.
According to a fifth aspect of the present invention, in the apparatus of the first aspect, the first plate and the second plate are made of molybdenum.
[0017]
According to a sixth aspect of the present invention, in the apparatus of the first aspect, a first deflecting means for passing the electron beam through the circular opening of the first plate, and the electron beam Further included is a second deflecting means for passing through the opening of the second plate.
According to a seventh aspect of the present invention, the apparatus according to the first aspect further includes a cooling means for cooling the second plate.
[0018]
According to an eighth aspect of the present invention, in the apparatus according to the first aspect, the first chamber including the electron beam generator, the first chamber and the second plate are separated by the second plate. A second chamber connected by the opening of the first plate, and a third chamber separated by the first plate and separated by the second chamber and connected by the circular opening of the first plate, The first chamber including the electron beam generator is maintained at a higher degree of vacuum than the second chamber and the third chamber.
[0019]
In a ninth aspect of the present invention, in the apparatus of the eighth aspect, the degree of vacuum in the second chamber is higher than the degree of vacuum in the third chamber.
According to a tenth aspect of the present invention, in the apparatus according to the ninth aspect, the third chamber is O _Three Is injected.
[0020]
According to the eleventh aspect of the present invention, the electron beam emitted from the electron beam generating source is irradiated and passed through the exposure pattern forming opening, and the sample is irradiated with the passed electron beam to perform exposure. The method includes a) partially cutting the electron beam directly under the electron beam generation source to reduce the amount of current, b) forming a crossover image of the cut electron beam, and c) forming the crossover. The exposure pattern forming aperture is irradiated with the shaped electron beam including steps for cutting the peripheral portion of the image and shaping the electron beam.
[0021]
According to a twelfth aspect of the present invention, in the method of the eleventh aspect, the step c) includes a diameter of a round aperture for blocking and blanking when the electron beam is deflected; The electron beam is shaped by cutting the periphery of the crossover image so that the size of the shaped electron beam at the position of the round aperture is substantially equal.
[0022]
According to a thirteenth aspect of the present invention, in the method according to the eleventh or twelfth aspect, the step b) satisfies the condition that the shaped electron beam uniformly irradiates the entire exposure pattern forming opening. The electron beam is partially cut to a large size to reduce the amount of current.
[0023]
In the first aspect of the invention, the circular aperture cuts the periphery of the crossover image to shape the electron beam, and the first plate having the circular aperture is not melted by the heat generated by the electron beam. The amount of electron beam current is reduced by the opening provided in the second plate upstream of the first plate. Since the electron beam crossover image is cut around the periphery of the electron beam and shaped, the mask having the exposure pattern formation opening is used when the exposure pattern formation opening is irradiated using the electron beam emitted from the circular opening. The risk of dissolution can be eliminated. Furthermore, the possibility of contamination and charge accumulation can be reduced.
[0024]
In the invention of claim 2, the size of the circular aperture is set such that the size of the electron beam shaped by the circular aperture at the position of the round aperture is substantially equal to the size of the round aperture. Is done. Therefore, when blanking is performed by blocking the deflected electron beam with a round aperture, a high-speed blanking operation can be realized.
[0025]
In the invention of claim 3, the size of the opening of the second plate is such that the electron beam emitted from the circular opening of the first plate satisfies the condition for uniformly irradiating the entire surface of the exposure pattern forming opening. Is set to a large size. Therefore, even if the electron beam is partially cut by the opening of the second plate, the exposure process for the sample is not adversely affected.
[0026]
In the invention of claim 4, the opening of the second plate is circular. Therefore, isotropic beam reduction can be performed.
In the invention of claim 5, the first plate and the second plate are made of molybdenum. Therefore, the first plate or the second plate is not melted by the heat generated by the electron beam irradiation.
[0027]
According to the sixth aspect of the present invention, the first deflecting means and the second deflecting means are provided for passing the electron beam through the circular opening of the first plate and the opening of the second plate. Therefore, by adjusting the first and second deflecting means, the electron beam can be easily aligned with the circular opening of the first plate and the opening of the second plate.
[0028]
In the invention of claim 7, a cooling means for cooling the second plate is provided. Thereby, the heat rise of a 2nd board and a peripheral part can be prevented. Therefore, it is possible to reduce the heat rise in the exposure column portion of the electron beam exposure apparatus, and it is possible to suppress the change in the operating characteristics due to the heat to the minimum.
[0029]
In the invention of claim 8, the third chamber for exposing the specimen to the electron beam and the first chamber including the electron beam generator are the second plate formed by the first plate and the second plate. Are connected by a circular opening in the first plate and an opening in the second plate. With such a configuration, the inside of the first chamber including the electron beam generator can be kept at a higher degree of vacuum than the inside of the third chamber.
[0030]
In the invention of claim 9, the degree of vacuum in the second chamber is higher than the degree of vacuum in the third chamber. By performing differential evacuation in this way, a high degree of vacuum can be realized in the first chamber.
In the invention of claim 10, the third chamber has O. _Three Is injected. Owing to the differential exhaust described above, O in the third chamber. _Three Even if it inject | pours, it does not have a bad influence on the electron beam generation part in a 1st chamber.
[0031]
According to the eleventh aspect of the invention, the periphery of the crossover image is cut to shape the electron beam, and the exposure pattern forming opening is irradiated using the shaped electron beam. Accordingly, it is possible to eliminate the risk that the mask having the exposed exposure pattern forming opening is dissolved. Furthermore, the possibility of contamination and charge accumulation can be reduced.
[0032]
In the invention of claim 12, the diameter of the round aperture for blocking and blanking when the electron beam is deflected is substantially equal to the size of the shaped electron beam at the position of the round aperture. Cut the periphery of the crossover image so that Therefore, when blanking is performed by blocking the deflected electron beam with a round aperture, a high-speed blanking operation can be realized.
[0033]
According to the thirteenth aspect of the present invention, the electron beam is partially cut to a size that satisfies the condition that the shaped electron beam uniformly irradiates the entire exposure pattern forming opening, thereby reducing the amount of current. Therefore, even if the electron beam is partially cut, the exposure process for the sample is not adversely affected.
[0034]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 shows an optical system 10 of an electron beam exposure apparatus according to a first embodiment of the present invention. 1, the same components as those in FIG. 7 are referred to by the same symbols, and a description thereof will be omitted.
[0035]
The optical system 10 of the present invention is positioned further upstream than the first slit 115 positioned at the most upstream of the electron beam flow in the conventional optical system. At this position, the optical system 10 cuts a useless electron beam by forming a crossover image and shaping (partially cut). As shown in FIG. 1, an optical system 10 according to the first embodiment of the present invention includes a beam reduction aperture 11 made of metal such as molybdenum, a crossover imaging lens 12, and a shaping round aperture 13 made of metal such as molybdenum. , First alignment coil 14, and second alignment coil 15.
[0036]
The electron beam emitted from the electron gun 114 is reduced in the amount of current by the beam reduction aperture 11, and a crossover image is formed by the crossover imaging lens 12. A shaping round aperture 13 is arranged at the crossover image formation position, and shapes (partially cuts) the crossover image.
[0037]
FIG. 2 shows an enlarged view of the optical system 10 according to the first embodiment of the present invention. The numerical value indicating the size of each component shown in FIG. 2 is an example corresponding to an actual electron beam exposure apparatus. In FIG. 2, a first crossover image C1 having a diameter of 50 μm is formed immediately below the electron gun. A second crossover image C2 of 50 μm is formed by the crossover imaging lens 12, and at this position, a shaping round aperture 13 which is a circular aperture having a diameter of 30 μm cuts and shapes the peripheral portion of the crossover image C2. . The shaped electron beam whose current value has been reduced is applied to the first slit 115 of the conventional optical system.
[0038]
Here, the shaping round aperture 13 is arranged at the imaging position of the crossover image C2, that is, the focal position where the electron beam is most converged. At this focal position, even metals such as molybdenum and tungsten are at risk of melting due to heat generated by the energy of the electron beam. In particular, the shaping round aperture 13 needs to be a thin film having a thickness of about 100 μm in order to process a small opening of about 30 μm, and there is a possibility that the shaping round aperture 13 is melted and damaged by heat generated by electron beam irradiation. Therefore, it is necessary to partially cut the electron beam emitted from the electron gun 114 in advance by the beam reduction aperture 11 (diameter: 200 μm) arranged at a position other than the focal position to reduce the current value.
[0039]
The electron beam passing through the beam reduction aperture 11 and the shaping round aperture 13 is reduced from a current value of about 500 μA to a current value of about 30 μA.
Therefore, dissolution of the block mask 120 (exposure pattern formation opening) due to heat generation can be avoided, and contamination adhesion and charge accumulation can be reduced.
[0040]
The size of the shaping round aperture 13 is determined according to the size of the round aperture 127 downstream of the electron beam. That is, the shaped round aperture 13 is formed so that the diameter of the electron beam is substantially equal to the diameter of the round aperture 127 when the electron beam whose beam shape and thickness are determined by the shaped round aperture 13 reaches the round aperture 127.
[0041]
Therefore, the amount of deflection of the electron beam necessary for completely blocking the electron beam by the round aperture 127 during blanking is suppressed to a minimum. As a result, the voltage to be applied to the blanking 125 is reduced, so that a high-speed blanking operation can be achieved.
[0042]
In FIG. 2, the beam reduction aperture 11 is a circular opening, and its diameter is 200 μm. As described above, the beam reduction aperture 11 has a function of reducing the current value by partially cutting the electron beam emitted from the electron gun 114 in advance so that the shaping round aperture 13 located at the focal point does not melt. Have Further, the beam reduction aperture 11 defines an incident angle of the electron beam with respect to the shaping round aperture 13 and an emission angle of the electron beam from the shaping round aperture 13.
[0043]
As shown in FIG. 3, when the beam reduction aperture 11 has a large aperture, the incident angle φ to the shaping round aperture 13 _in And the output angle φ from the shaping round aperture 13 _out Will be small. In this case, a sufficiently wide range is irradiated at the position of the first slit 115, and the irradiation of the electron beam to the first slit 115 is not lost. Therefore, the entire surface of the block mask 120 (exposure pattern forming opening) downstream of the electron beam is irradiated uniformly. Conversely, as shown in FIG. 4, when the beam reduction aperture 11 is too small, the incident angle φ to the shaping round aperture 13 _in And the output angle φ from the shaping round aperture 13 _out Becomes large, and the irradiation of the electron beam to the first slit 115 is lost. In this case, there is a possibility that the block mask 120 (exposure pattern formation opening) downstream of the electron beam is not sufficiently evenly irradiated on the entire surface, and the image by the first slit 115 and the image of the beam reduction aperture 11 are misidentified. .
[0044]
Therefore, the beam reduction aperture 11 must satisfy the condition that there is no omission in the irradiation of the electron beam to the first slit, and the block mask 120 (exposure pattern formation opening) downstream of the electron beam is sufficiently uniformly irradiated. .
Referring back to FIG. 1, the first alignment coil 14 and the second alignment coil 15 are provided for aligning the electron beam and passing it through the beam reduction aperture 11 and the shaping round aperture 13. That is, the first alignment coil 14 is used to adjust the optical axis position of the electron beam and pass it through the beam reduction aperture 11. Next, the electron beam is further passed through the shaping round aperture 13 by adjustment using the second alignment coil. By arranging the alignment coils (deflectors) above and below the beam reduction aperture 11 in this way, the electron beam can be aligned with the beam reduction aperture 11 and the shaping round aperture 13.
[0045]
As described above, in the first embodiment of the present invention, the electron beam emitted from the electron gun 114 is reduced in the amount of current by the beam reduction aperture 11 and is shaped at the crossover image formation position. The crossover image is shaped by the round aperture 13. This cuts off excess current downstream of the electron beam, avoids melting of the block mask 120 (exposure pattern formation opening) due to heat generation, and reduces contamination and charge accumulation. I can do it. Further, by setting the shaping round aperture 13 to a size corresponding to the round aperture 127 downstream of the electron beam, the amount of deflection of the electron beam necessary for blanking can be minimized. As a result, a high-speed blanking operation can be achieved.
[0046]
In the first embodiment of the present invention, since the current amount of the electron beam is reduced, an effect of reducing the Coulomb interaction in which the electron beam is blurred at the focal point due to the repulsive force of the electrons can be expected. Coulomb interaction is a phenomenon in which an electron beam spreads at a focal point where the electron beam concentrates due to repulsion of electrons having negative charges. The magnitude of this Coulomb interaction is approximately proportional to the product of the current density of the electron beam and the area of the electron beam, that is, the total current amount of the electron beam. Accordingly, the Coulomb interaction can be reduced by reducing the current amount of the electron beam according to the first embodiment of the present invention.
[0047]
FIG. 5 shows an electron beam exposure apparatus according to a second embodiment of the present invention.
Generally, ozone O in the exposure column 110 of an electron beam exposure apparatus _Three Has been injected. Since it is difficult to generate only pure ozone, gas other than ozone is actually mixed. At this time, if these gases are ionized and have a positive charge, ions collide with the electron gun 114 at high speed, and the shape of the electron emission surface of the electron gun 114 is distorted by the impact of the ion collision. If the shape of the electron beam is distorted by this, it will hinder the exposure of the sample. Therefore, it is desirable to maintain the vicinity of the electron gun 114 in a high vacuum state. In the electron beam exposure apparatus according to the second embodiment of the present invention, the degree of vacuum in the space around the electron gun 114 can be increased by using the beam reduction aperture 11 and the shaping round aperture 13 of FIG. .
[0048]
5, the electron beam exposure apparatus generally includes a first chamber 21 including an electron gun 114 and a first alignment coil 14, a second chamber including a crossover imaging lens 12 and a second alignment coil 15. 22 and a third chamber 25 for performing electron beam exposure on the sample W on the sample stage 135 as in the conventional electron beam optical system. The electron beam exposure apparatus of FIG. 5 further includes an ion pump 23 for discharging ions from the first chamber 21 and a turbo pump 24 for exhausting from the second chamber 22. In addition, a turbo pump 26 is provided in the third chamber 25, and air is exhausted from the inside of the third chamber 25 to approach a vacuum state, and ozone is injected from the ozone inlet 27.
[0049]
The space of the first chamber 21 and the space of the second chamber 22 are combined by the beam reduction aperture 11. The space of the second chamber 22 and the space of the third chamber 25 are connected by the shaping round aperture 13.
[0050]
Since the shaping round aperture 13 between the second chamber 22 and the third chamber 25 is a small opening of about 30 μm, the degree of vacuum in the second chamber 22 is set in the third chamber 25 by exhausting the turbo pump 24. The degree of vacuum can be increased. The ion pump 23 discharges ions harmful to the electron gun 114 and keeps the first chamber 21 at a higher degree of vacuum than the second chamber 22.
[0051]
As described above, in the second embodiment of the present invention, by using the beam reduction aperture 11 and the shaping round aperture 13, the chamber is differentially evacuated by the ion pump 23 and the turbo pump 24. The space around the electron gun 114 can be kept at a high degree of vacuum. Accordingly, it is possible to prevent the electron gun 114 from being damaged by the collision of ions and distorting the electron beam.
[0052]
FIG. 6 shows an electron beam exposure apparatus according to a third embodiment of the present invention. In FIG. 6, the same components as those in FIG. 5 are referred to by the same symbols, and a description thereof will be omitted. In the electron beam exposure apparatus of FIG. 6, only the cooling mechanism 30 provided in the beam reduction aperture 11 is different from the electron beam exposure apparatus according to the second embodiment of the present invention of FIG.
[0053]
The cooling mechanism 30 is preferably a water-cooling system, which can prevent a heat increase in the beam reduction aperture 11 and the peripheral portion. As a result, the heat rise in the exposure column portion of the electron beam exposure apparatus can be reduced, and the change in operating characteristics due to heat can be minimized.
[0054]
【The invention's effect】
In the first aspect of the invention, the circular aperture cuts the periphery of the crossover image to shape the electron beam, and the first plate having the circular aperture is not melted by the heat generated by the electron beam. The amount of electron beam current is reduced by the opening provided in the second plate upstream of the first plate. Since the electron beam crossover image is cut around the periphery of the electron beam and shaped, the mask having the exposure pattern formation opening is used when the exposure pattern formation opening is irradiated using the electron beam emitted from the circular opening. The risk of dissolution can be eliminated. Furthermore, the possibility of contamination and charge accumulation can be reduced.
[0055]
In the invention of claim 2, the size of the circular aperture is set such that the size of the electron beam shaped by the circular aperture at the position of the round aperture is substantially equal to the size of the round aperture. Is done. Therefore, when blanking is performed by blocking the deflected electron beam with a round aperture, a high-speed blanking operation can be realized.
[0056]
In the invention of claim 3, the size of the opening of the second plate is such that the electron beam emitted from the circular opening of the first plate satisfies the condition for uniformly irradiating the entire surface of the exposure pattern forming opening. Is set to a large size. Therefore, even if the electron beam is partially cut by the opening of the second plate, the exposure process for the sample is not adversely affected.
[0057]
In the invention of claim 4, the opening of the second plate is circular. Therefore, isotropic beam reduction can be performed.
In the invention of claim 5, the first plate and the second plate are made of molybdenum. Therefore, the first plate or the second plate is not melted by the heat generated by the electron beam irradiation.
[0058]
According to the sixth aspect of the present invention, the first deflecting means and the second deflecting means are provided for passing the electron beam through the circular opening of the first plate and the opening of the second plate. Therefore, by adjusting the first and second deflecting means, the electron beam can be easily aligned with the circular opening of the first plate and the opening of the second plate.
[0059]
In the invention of claim 7, a cooling means for cooling the second plate is provided. Thereby, the heat rise of a 2nd board and a peripheral part can be prevented. Therefore, it is possible to reduce the heat rise in the exposure column portion of the electron beam exposure apparatus, and it is possible to suppress the change in the operating characteristics due to the heat to the minimum.
[0060]
In the invention of claim 8, the third chamber for exposing the specimen to the electron beam and the first chamber including the electron beam generator are the second plate formed by the first plate and the second plate. Are connected by a circular opening in the first plate and an opening in the second plate. With such a configuration, the inside of the first chamber including the electron beam generator can be kept at a higher degree of vacuum than the inside of the third chamber.
[0061]
In the invention of claim 9, the degree of vacuum in the second chamber is higher than the degree of vacuum in the third chamber. By performing differential evacuation in this way, a high degree of vacuum can be realized in the first chamber.
In the invention of claim 10, the third chamber has O. _Three Is injected. Owing to the differential exhaust described above, O in the third chamber. _Three Even if it inject | pours, it does not have a bad influence on the electron beam generation part in a 1st chamber.
[0062]
According to the eleventh aspect of the invention, the periphery of the crossover image is cut to shape the electron beam, and the exposure pattern forming opening is irradiated using the shaped electron beam. Accordingly, it is possible to eliminate the risk that the mask having the exposed exposure pattern forming opening is dissolved. Furthermore, the possibility of contamination and charge accumulation can be reduced.
[0063]
In the invention of claim 12, the diameter of the round aperture for blocking and blanking when the electron beam is deflected is substantially equal to the size of the shaped electron beam at the position of the round aperture. Cut the periphery of the crossover image so that Therefore, when blanking is performed by blocking the deflected electron beam with a round aperture, a high-speed blanking operation can be realized.
[0064]
According to the thirteenth aspect of the present invention, the electron beam is partially cut to a size that satisfies the condition that the shaped electron beam uniformly irradiates the entire exposure pattern forming opening, thereby reducing the amount of current. Therefore, even if the electron beam is partially cut, the exposure process for the sample is not adversely affected.
[Brief description of the drawings]
FIG. 1 is a block diagram of an exposure column portion of an electron beam exposure apparatus showing an optical system according to a first embodiment of the present invention.
FIG. 2 is an enlarged view of the optical system according to the first embodiment of the present invention.
FIG. 3 is a diagram showing a beam shape when the aperture of the beam reduction aperture is sufficiently large in the optical system according to the first embodiment of the present invention.
FIG. 4 is a diagram showing a beam shape when the aperture of the beam reduction aperture is small in the optical system according to the first embodiment of the present invention.
FIG. 5 is a block diagram of an electron beam exposure apparatus according to a second embodiment of the present invention.
FIG. 6 is a block diagram of an electron beam exposure apparatus according to a third embodiment of the present invention.
FIG. 7 is a block diagram of an exposure column portion showing an optical system of a conventional electron beam exposure apparatus.
[Explanation of symbols]
10 Optical system
11 Beam reduction aperture
12 Crossover imaging lens
13 Shaping round aperture
14 First alignment coil
15 Second alignment coil
21 First chamber
22 Second chamber
23 Ion pump
24 turbo pump
25 Third chamber
26 Turbo pump
27 Ozone inlet
30 Cooling mechanism
110 Exposure column
111 Cathode electrode
112 Wehnelt
113 anode
114 Electron Beam Source
115 first slit
116 1st electron lens
118 second lens
119 Third lens
120 block mask
121 First deflector
122 Second deflector
123 Third deflector
124 fourth deflector
125 Blanking
126 Fourth lens
127 round aperture
128 Refocus coil
129 Fifth lens
132 Sixth objective lens
133 Main deflector
134 Deflector
135 Sample stage

Claims (13)

An electron beam exposure apparatus for performing exposure by irradiating an electron beam emitted from an electron beam generation source by irradiating an exposure pattern forming opening and passing the sample, and irradiating the sample with the shaped electron beam,
An electromagnetic lens that forms a crossover image;
A first plate having a circular aperture which is provided at an imaging position of the crossover image and which cuts a peripheral portion of the crossover image formed by the electromagnetic lens to shape the electron beam;
The exposure pattern forming opening is irradiated with an electron beam shaped by the circular opening including a second plate having an opening for reducing the amount of current of the electron beam upstream from the first plate with respect to the flow of the electron beam. An electron beam exposure apparatus.   A blanking electrode for deflecting the electron beam shaped by the exposure pattern forming aperture for blanking; and a round aperture for blocking and blanking the deflected electron beam. 2. The apparatus according to claim 1, wherein the size of the electron beam shaped by the circular aperture at the position of the round aperture is approximately equal to the size of the round aperture.   The size of the opening of the second plate is such that the electron beam emitted from the circular opening of the first plate at an emission angle depending on the size of the opening of the second plate is the exposure pattern. 3. The apparatus according to claim 1, wherein the size is such that a condition for uniformly irradiating the entire surface of the formation opening is satisfied.   4. The apparatus of claim 3, wherein the opening in the second plate is circular.   The apparatus of claim 1, wherein the first plate and the second plate are made of molybdenum.   A first deflecting unit for passing the electron beam through the circular opening of the first plate; and a second deflecting unit for passing the electron beam through the opening of the second plate. The apparatus according to claim 1.   2. The apparatus of claim 1, further comprising cooling means for cooling the second plate. A first chamber including the electron beam generator;
A second chamber separated by the second plate and connected by the opening of the second plate;
And further comprising a third chamber separated from the second chamber by the first plate and connected by the circular opening of the first plate, and the interior of the first chamber including the electron beam generator is included in the first chamber. 2. The apparatus according to claim 1, wherein a higher degree of vacuum is maintained than in the second chamber and the third chamber.   9. The apparatus according to claim 8, wherein the degree of vacuum in the second chamber is higher than the degree of vacuum in the third chamber. The apparatus of claim 9, wherein O ₃ is injected into the third chamber. An electron beam exposure method in which an electron beam emitted from an electron beam generation source is irradiated and passed through an exposure pattern forming opening, and the sample is irradiated with the passed electron beam to perform exposure.
a) The electron beam is partially cut directly under the electron beam generation source to reduce the amount of current;
b) forming a crossover image of the cut electron beam;
and c) irradiating the exposure pattern forming aperture with the shaped electron beam including the steps of shaping the electron beam by cutting a peripheral portion of the crossover image at the imaging position of the crossover. An electron beam exposure method.   In step c), the diameter of the round aperture for blocking and blanking when the electron beam is deflected is substantially equal to the size of the shaped electron beam at the position of the round aperture. The method according to claim 11, wherein the electron beam is shaped by cutting a peripheral portion of the crossover image in such a size.   The step b) includes reducing the amount of current by partially cutting the electron beam to a size such that the shaped electron beam satisfies a condition for uniformly irradiating the entire exposure pattern forming opening. 13. A method according to claim 11 or 12, characterized in that

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