Patent Application
20240395493
This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2023-085390 filed on May 24, 2023 in Japan, the entire contents of which are incorporated herein by reference.
Embodiments of the present invention relate to a blanking aperture array mechanism and a writing apparatus, and for example, to a method of cancelling out the magnetic field which affects the trajectory of multiple beams.
The lithography technique which advances miniaturization of semiconductor devices is extremely important as a unique process whereby patterns are formed in semiconductor manufacturing. In recent years, with high integration of LSI, the line width (critical dimension) required for semiconductor device circuits is becoming increasingly finer year by year. The electron beam writing technique, which intrinsically has excellent resolution, is used for writing or “drawing” on a wafer and the like with electron beams.
For example, as a known example of employing the electron beam writing technique, there is a writing apparatus using multiple beams. Since it is possible for multiple beam writing to apply multiple beams at a time, the writing throughput can be greatly increased in comparison with single electron beam writing. For example, a writing apparatus employing the multiple beam system forms multiple beams by letting an electron beam emitted from an electron gun pass through a mask having a plurality of holes, performs blanking control for each beam, reduces each unblocked beam by an optical system, and deflects it by a deflector to irradiate a desired position on a target object or “sample”.
In the multiple beam writing, a pattern is formed by individually controlling the irradiation time of electron beams entering a target object. Accordingly, in the writing apparatus, there is installed a mounting substrate (board) where a blanking aperture array chip is arrayed having a plurality of blanker functions for controlling a beam to be OFF whose irradiation time is zero or desired irradiation time has passed.
It has turned out that positional deviation of an electron beam passing through a blanking aperture array chip occurs due to a magnetic field generated by circuit currents flowing in the mounting substrate. The writing accuracy is degraded if such positional deviation occurs.
Although not relating to a magnetic field generated by a mounting substrate in an electron optical column, there is disclosed a technique in which cancel coils are disposed around an electron optical column in order to measure a disturbing magnetic field outside the electron optical column, and then, the disturbing magnetic field is cancelled out by generating a reverse magnetic field by the cancel coils (e.g., refer to Japanese Patent Application Laid-open (JP-A) No. 2003-173755).
According to one aspect of the present invention, a blanking aperture array mechanism includes
According to another aspect of the present invention, a blanking aperture array mechanism includes
According to yet another aspect of the present invention, a writing apparatus includes
Embodiments below provide an apparatus which can cancel out a magnetic field generated by circuit currents flowing in a mounting substrate where a blanking aperture array chip through which multiple beams pass is disposed. Further, embodiments provide an apparatus which can correct positional deviation of an electron beam resulting from the magnetic field.
Embodiments below describe a configuration in which an electron beam is used as an example of a charged particle beam. The charged particle beam is not limited to the electron beam, and other charged particle beam such as an ion beam may also be used.
The blanking aperture array mechanism 204 includes a mounting substrate 211 and a blanking aperture array chip 212. Openings through which all of multiple beams 20 can pass are formed in the central portion of the mounting substrate 211. The blanking aperture array chip 212 is hung from the mounting substrate 211 such that it occludes the opening. In other words, the outer peripheral part of the blanking aperture array chip 212 is arranged being supported by the mounting substrate 211. The blanking aperture array chip 212 may be arranged on the mounting substrate 211.
In the writing chamber 103, an XY stage 105 is disposed. On the XY stage 105, there is placed a target object or “sample” 101 such as a mask serving as a writing target substrate when writing (exposure) is performed. The target object 101 is, for example, an exposure mask used when fabricating semiconductor devices, or a semiconductor substrate (silicon wafer) for fabricating semiconductor devices. The target object 101 may be, for example, a mask blank on which resist has been applied and nothing has yet been written.
On the XY stage 105, a mirror 210 for measuring the position of the XY stage 105 is placed.
The control system circuit 160 includes a control computer 110, a memory 112, a deflection control circuit 130, digital-analog converter (DAC) amplifier units 132 and 134, a lens control circuit 136, a stage control mechanism 138, a stage position measuring instrument 139, and storage devices 140 and 142 such as magnetic disk drives. The control computer 110, the memory 112, the deflection control circuit 130, the lens control circuit 136, the stage control mechanism 138, the stage position measuring instrument 139, and the storage devices 140 and 142 are connected to each other through a bus (not shown). The DAC amplifier units 132 and 134 and the blanking aperture array mechanism 204 are connected to the deflection control circuit 130. The deflector 209 is composed of at least four electrodes (or “four poles”), and controlled by the deflection control circuit 130 through the DAC amplifier unit 132 disposed for each electrode. The deflector 208 is composed of at least four electrodes (or “four poles”), and controlled by the deflection control circuit 130 through the DAC amplifier unit 134 disposed for each electrode. Electromagnetic lenses such as the illumination lens 202, the reducing lens 205, and the objective lens 207 are controlled by the lens control circuit 136.
The position of the XY stage 105 is controlled by the drive of each axis motor (not shown) which is controlled by the stage control mechanism 138. Based on the principle of laser interferometry, the stage position measuring instrument 139 measures the position of the XY stage 105 by receiving a reflected light from the mirror 210.
In the control computer 110, there are arranged a shot data generation unit 70, a data processing unit 72, a transmission processing unit 74, and a writing control unit 76. Each of the “ . . . units” such as the shot data generation unit 70, the data processing unit 72, the transmission processing unit 74, and the writing control unit 76 includes processing circuitry. The processing circuitry includes, for example, an electric circuit, computer, processor, circuit board, quantum circuit, semiconductor device, or the like. Each “ . . . unit” may use common processing circuitry (the same processing circuitry), or different processing circuitry (separate processing circuitry). Information input/output to/from the shot data generation unit 70, the data processing unit 72, the transmission processing unit 74, and the writing control unit 76, and information being operated are stored in the memory 112 each time.
In the deflection control circuit 130, there are arranged a deflection control unit 50, a current measurement unit 52, and a cancel circuit control unit 54 are arranged. Each of the “ . . . units” such as the deflection control unit 50, the current measurement unit 52, and the cancel circuit control unit 54 includes processing circuitry. The processing circuitry includes, for example, an electric circuit, computer, processor, circuit board, quantum circuit, semiconductor device, or the like. Each “ . . . unit” may use common processing circuitry (the same processing circuitry), or different processing circuitry (separate processing circuitry). Information input/output to/from the deflection control unit 50, the current measurement unit 52, and the cancel circuit control unit 54, and information being operated are stored in a memory (not shown) in the deflection control circuit 130 each time.
Writing operations of the writing apparatus 100 are controlled by the writing control unit 76. Processing of transmitting irradiation time data of each shot to the deflection control circuit 130 is controlled by the transmission control unit 74.
Writing data (chip data) is input from the outside of the writing apparatus 100, and stored in the storage device 140. Chip data defines information on a plurality of figure patterns configuring a chip pattern. Specifically, for example, a figure code, coordinates, a size, and the like are defined for each figure pattern.
The blanking aperture array chip 212 includes a plurality of blankers which, at incidence of the multiple beams 20, individually switch the state between “beam ON” and “beam OFF” of the multiple beams 20. Specifically, it is configured as follows: The blanking aperture array chip 212 includes a blanking aperture substrate 31 being a semiconductor substrate made of silicon, etc. At the central part of the blanking aperture array substrate 31, a thin membrane region 330 is formed. In the membrane region 330, passage holes 25 (openings) through each of which a corresponding one of the multiple beams 20 passes are formed at positions each corresponding to each hole 22 in the shaping aperture array substrate 203 shown in
Further, on the blanking aperture array substrate 31 or in it, control circuits 44 are arranged in the x direction to be opposite to each other on the sides across the membrane region 330.
As shown in
Signals for each row output from the deflection control circuit 130 to the blanking aperture array mechanism 204 are divided through a circuit in the mounting substrate 211 or the control circuit 44 in the blanking aperture array chip 212, and transmitted in parallel to each group. Then, the signal for each group is transmitted to the control circuits 41 connected in series in the group concerned. Specifically, a shift register 11 is disposed in each control circuit 41, and shift registers 11 in the control circuits 41 in the same group are connected in series. In the case of
Based on an irradiation time control signal transmitted to the shift register 11 for each beam, each individual blanking mechanism 47 individually controls, for each beam, the irradiation time of the shot concerned using a counter circuit (not shown). Alternatively, a maximum irradiation time Tmax for one shot is divided into a plurality of sub-shots having different irradiation time. Then, based on the irradiation time control signal transmitted to the shift register 11 for each beam, each blanking mechanism 47 selects a combination of sub-shots from the plurality of sub-shots in order that the combination may become the irradiation time for one shot. It is also preferable to control the irradiation time for one shot for each beam by continuously applying irradiation to pixels whose combinations of selected sub-shots are the same as each other. In the case of dividing one shot into a plurality of sub-shots, since the irradiation time of each sub-shot has been determined beforehand, the accuracy of irradiation time can be increased by controlling the irradiation time of each sub-shot by using a common blanking deflector controlled by a logic circuit (not shown) compared with the case of controlling by using only each individual blanking mechanism 47. In the case of individually controlling, for each beam, the irradiation time of the shot concerned by using a counter circuit, since it is not usually performed to collectively control all the beams to be beam OFF, the logic circuit and the common blanking deflector may be omitted. In the case of dividing one shot into a plurality of sub-shots, the number of irradiation time control signals to be transmitted is the same as the number of the plurality of sub-shots. At the same time, since the irradiation time control signal transmitted to the shift register 11 for each beam can be used as a signal just for selecting ON or OFF of a plurality of sub-shots, the number of bits of data used for one transmission can be reduced.
Next, an example of a concrete operation of the writing mechanism 150 will be described. The electron beam 200 emitted from the electron gun 201 (emission source) almost perpendicularly (e.g., vertically) illuminates the whole of the shaping aperture array substrate 203 by the illumination lens 202. A plurality of rectangular (including square) holes 22 (openings) are formed in the shaping aperture array substrate 203. The region including all of the plurality of holes 22 is irradiated with the electron beam 200. For example, rectangular multiple beams (a plurality of electron beams) 20 are formed by letting portions of the electron beam 200 applied to the positions of the plurality of holes 22 individually pass through a corresponding one of the plurality of holes 22 in the shaping aperture array substrate 203. The multiple beams 20 individually pass through corresponding blankers in the blanking aperture array chip 212. The blanker provides blanking control such that a corresponding beam individually passing becomes in an ON condition during a set writing time (irradiation time).
The multiple beams 20 having passed through the blanking aperture array chip 212 are reduced by the reducing lens 205, and travel toward the hole in the center of the limiting aperture substrate 206. Then, the electron beam which was deflected by the blanker of the blanking aperture array chip 212 deviates (shifts) from the hole in the center of the limiting aperture substrate 206 and is blocked by the limiting aperture substrate 206. In contrast, electron beams which were not deflected by the blankers of the blanking aperture array chip 212 pass through the hole in the center of the limiting aperture substrate 206 as shown in
As described above, a plurality of control circuits 41 arranged in an array in the membrane region 330 in the blanking aperture array chip 212 are divided into right and left halves in the x direction to be controlled. At the left half, a plurality of control circuits 41 in the same row are grouped into a plurality of groups. Similarly, at the right half, a plurality of control circuits 41 in the same row are grouped into a plurality of groups. In the blanking aperture array chip 212, the control circuit 44 which controls a plurality of groups in the left half and an interface circuit 13 are disposed outside of and near the peripheral part of the membrane region 330. Similarly, in the blanking aperture array chip 212, the control circuit 44 which controls a plurality of groups in the right half and the interface circuit 13 are disposed outside of and near the peripheral part of the membrane region 330.
In the mounting substrate 211, a power supply plane 216, a cancelling layer 218, and other signal circuits are formed. The power supply plane 216 supplies power to the blanking aperture array chip 212. The power supply plane 216 serves as the power source of a transistor of each logic circuit of voltage Vdd, for example. The cancelling layer 218 is arranged at the upper layer side or lower layer side of the power supply plane 216 in a manner overlapping with the power supply plane 216. It is specifically described below.
On the left side in the x direction of the blanking aperture array chip 212 in the mounting substrate 211, there are formed the layer of a power supply plane (planar power supply) 216a which supplies power to a plurality of groups at the left half of the blanking aperture array chip 212, the circuit layer of signal lines (not shown), and an interface circuit 217a. The power supply plane 216a is connected to the left-side control circuit 44 through the left-side interface circuit 13. The power supply plane 216a functions as a power source of the control circuit 44. That is, the power supply plane 216a sends a current to the control circuit 44. The circuit layer of signal lines (not shown) is connected to the left-side control circuit 44 through the left-side interface circuit 13. The circuit layer of signal lines outputs a control signal to the control circuit 44. Power and signals are supplied to the layer of the power supply plane 216a and the circuit layer of signal lines from the deflection control unit 50 of the deflection control circuit 130 through the interface circuit 217a.
Similarly, on the right side in the x direction of the blanking aperture array chip 212 in the mounting substrate 211, there are formed the layer of a power supply plane 216b which supplies power to a plurality of groups at the right half of the blanking aperture array chip 212, the circuit layer of signal lines (not shown), and an interface circuit 217b. The power supply plane 216b is connected to the right-side control circuit 44 through the right-side interface circuit 13. The power supply plane 216b functions as a power source of the control circuit 44. That is, the power supply plane 216b sends a current to the control circuit 44. The circuit layer of signal lines (not shown) is connected to the right-side control circuit 44 through the right-side interface circuit 13. The circuit layer of signal lines outputs a control signal to the control circuit 44. Power and signals are supplied to the layer of the power supply plane 216b and the circuit layer of signal lines from the deflection control unit 50 of the deflection control circuit 130 through the interface circuit 217b.
As described above, shift registers are driven to transmit data to respective control circuits 41 in the blanking aperture array chip 212. Power is consumed to drive the shift registers. When beam ON or OFF is performed, current flows in the amplifier 46 in each control circuit 41. For performing these controls at a high speed, a large amount of current may flow at a time. Accordingly, the power supply plane 216 is formed in the mounting substrate 211. At this time, a magnetic field B is generated due to circuit currents flowing in the mounting substrate 211. Thereby, positional deviation of the multiple beams 20 occurs.
As described above, if a current flows in the power supply plane 216 of the mounting substrate 211, the magnetic field B is generated. Then, depending on the amount of the current flowing in the power supply plane 216, the size of the generated magnetic field B changes. Depending on the size of the magnetic field B, the positional deviation of a beam passing through the blanking aperture array chip 212 changes. Then, according to the first embodiment, a cancelling plane (cancelling layer) which cancels out the magnetic field B generated by the power supply plane 216 is formed in the mounting substrate 211.
A current (reverse current) which is in a reverse direction and of the same amount as the current flowing in the power supply plane 216a (216b) is supplied to the cancelling layer 218a (218b) from the deflection control circuit 130 (example of a control circuit) of the writing apparatus 100. Specifically, the current measurement unit 52 measures the current flowing to the power supply plane 216a (216b) from the deflection control unit 50. The current measurement unit 52 inputs an operation result operated in the deflection control unit 50, and calculates the number of beams to be beam ON in the left-side (right-side) beam array, for example. Then, based on the number of beams calculated, a current flowing from the deflection control unit 50 to the power supply plane 216a (216b) is estimated (calculated). The cancel circuit control unit 54 controls to flow a reverse current, being reverse to the estimated (calculated) current, in the cancelling layer 218a (218b). By this, the magnetic field B generated by the current flowing in the power supply plane 216a (216b), and the reverse magnetic field B′ generated by the reverse current flowing in the cancelling layer 218a (218b) become the same intensity magnetic fields in reverse directions. Thereby, the reverse magnetic field B′ generated by the reverse current flowing in the cancelling layer 218a (218b) cancels out the magnetic field B generated by the current flowing in the power supply plane 216a (216b).
The current to flow in the cancelling layer 218a (218b) may be, for example, a fluctuating current (active current) which fluctuates per shot, or a fixed current (static current) which is set per stripe region to be described later.
In the case of controlling using a fluctuating current, since its current value fluctuates depending on a writing pattern, it is desirable to flow a reverse current to be corresponding to a current flowing in the power supply plane 216a (216b) in each shot as described above.
In the case of controlling using a fixed current, for example, it is preferable to obtain a statistic value (e.g., average value) of a current flowing in the power supply plane 216a (216b) for each stripe region by previously performing a non-irradiation writing process before writing onto the target object 101, and to flow, in actual writing processing, a reverse current, which is reverse to the current of the obtained statistic value, in the cancelling layer 218a (218b).
Preferably, the cancelling layer 218a (218b) is formed to have the same shape and area as those of the power supply plane 216a (216b). By this, the magnetic field B and the reverse magnetic field B′ can be completely coincident with reverse directions. In the case of
In the case where the power supply plane 216a (216b) and the cancelling layer 218a (218b) are rectangularly formed, in the power supply plane 216a on the left side shown in
If, because of the configuration of the layer of the mounting substrate 211, it is difficult to form the cancelling layer 218a (218b) to have the same shape as that of the power supply plane 216a (216b), a plurality of linear or tabular shape, whose length is longer than width, cancelling layers 218a (218b) may be arranged in parallel.
Since the current flowing in the power supply plane 216 is consumed in the blanking aperture array chip 212, it is preferable to arrange a resistance 17, having the same load as the blanking aperture array chip 212, between the cancelling layer 218 and a corresponding GND layer. Preferably, the resistance 17 is disposed on the mounting substrate 211, for example. In that case, since the degree of freedom of the size is increased, the resistance 17 can be easily formed compared with formed in the layer or between layers. Conductive contact wiring extending perpendicularly to each layer may be used for connecting between the resistance 17 and the cancelling layer 218 or GND layer. Thereby, it becomes possible to flow a current, equivalent to the current flowing in the power supply plane 216, in a reverse direction in the cancelling layer 218.
In the above each example, two power supply layers, namely, the layer of the power supply plane 216 serving as a power source of the transistor of each logic circuit of voltage Vdd, and the power supply plane layer serving as a power source of the I/O circuit are described, but it is not limited thereto. Three or more power supply plane layers may be formed. Further, each power supply plane may be formed by use, and a different voltage may be supplied to each of them.
As described above, it is preferable that the cancelling layers are formed according to the number of the power supply planes 216 each used as a power source of the transistor of each logic circuit of voltage Vdd, and the number of the power supply planes each serving as a power source of the I/O circuit. In other words, cancelling layers for the layers of the power supply planes 216 used as the power source of the transistors, in respective logic circuits, of voltage Vdd, and cancelling layers for the power supply plane layers used as the power source of the I/O circuits are formed. However, it is not limited thereto. It is also acceptable to form only the cancelling layer 218 for the power supply plane 216 serving as a power source of the transistor of each logic circuit of voltage Vdd which greatly influences on the magnetic field B.
In the examples described above, a conductive layer of a rectangular planar shape is used as the power supply plane 216, for example, but, it is not limited thereto.
In
In the case where the power supply plane 216a (216b) and the cancelling layer 218a (218b) are formed extending long while changing the direction on the way, for example, in the upper power supply plane 216a of the two power supply planes 216a on the left side shown in
First, the XY stage 105 is moved to make an adjustment such that the irradiation region 34 of the multiple beams 20 is located at the left end, or at a position further left than the left end, of the first stripe region 32, and then writing of the first stripe region 32 is performed. When writing the first stripe region 32, the XY stage 105 is moved, for example, in the −x direction, so that the writing may relatively proceed in the x direction. The XY stage 105 is moved, for example, continuously at a constant speed. After writing the first stripe region 32, the stage position is moved in the −y direction by the width of the stripe region 32.
Next, an adjustment is made such that the irradiation region 34 of the multiple beams 20 is located at the left end, or at a position further left than the left end, of the second stripe region 32. Then, writing of the second stripe region 32 is performed by moving the XY stage 105, for example, in the −x direction to proceed the writing relatively in the x direction.
Although
In the shot data generation step, first, the shot data generation unit 70 generates shot data for each pixel 36. Specifically, it operates as follows: First, the shot data generation unit 70 reads writing data from the storage device 140, and calculates, for each pixel 36, a pattern area density p′ in the pixel 36 concerned. This processing is performed for each stripe region 32, for example.
Next, the shot data generation unit 70, first, virtually divides the writing region (here, for example, stripe region 32) into a plurality of proximity mesh regions (mesh regions for proximity effect correction calculation) by a predetermined size. The size of the proximity mesh region is preferably about 1/10 of the influence range of the proximity effect, such as about 1 μm. The shot data generation unit 70 reads writing data from the storage device 140, and calculates, for each proximity mesh region, a pattern area density ρ″ of a pattern arranged in the proximity mesh region concerned.
Next, the shot data generation unit 70 calculates, for each proximity mesh region, a proximity effect correction irradiation coefficient Dp(x) (correction dose) for correcting a proximity effect. An unknown proximity effect correction irradiation coefficient Dp(x) can be defined by a threshold value model for proximity effect correction, which is the same as the one used in a conventional method, where a backscatter coefficient η, a dose threshold value Dth of a threshold value model, a pattern area density ρ″, and a distribution function g(x) are used.
Next, the shot data generation unit 70 calculates, for each pixel 36, an incident dose D(x) (amount of dose) with which the pixel 36 concerned is irradiated. The incident dose D(x) can be calculated, for example, by multiplying a base dose Dbase by a proximity effect correction irradiation coefficient Dp and a pattern area density ρ′. The base dose Dbase can be defined by Dth/(½+η), for example. Thereby, it is possible to obtain an incident dose D(x) for each pixel 36, for which a proximity effect has been corrected, based on layout of a plurality of figure patterns defined by the writing data.
Next, the shot data generation unit 70 calculates an irradiation time for each pixel 36. The irradiation time for each pixel 36 can be obtained by diving an incident dose D(x) of the pixel concerned by a current density J.
In the data processing step, the data processing unit 72 rearranges obtained irradiation time data for each pixel 36 in order of shot, and stores it in the storage device 142. The transmission processing unit 74 transmits, in order of shot, the irradiation time data to the deflection control circuit 130.
In the writing step (S140), under the control of the writing control unit 76, the writing mechanism 150 writes, with the multiple beams 20, a pattern on the target object 101 on the XY stage 105 while moving the XY stage 105. In the multiple beam writing, in parallel with performing the writing processing, the writing mechanism 150 generates shot data for a region in which later writing processing is to be performed. For example, while writing the k-th stripe region 32, shot data for the (k+2) th stripe region 32 is generated in parallel. Repeating this operation, all the stripe regions 32 are written.
In the writing operation shown in
During the writing processing, a reverse current controlled for each shot or each stripe flows in the cancelling layer 218a (218b). By this, the multiple beams 20 can pass through the blanking aperture array chip 212, in the state where the magnetic field B generated by circuit currents flowing in the mounting substrate 211 has been canceled out.
As described above, according to the first embodiment, it is possible to cancel out the magnetic field B generated by circuit currents flowing in the mounting substrate 212 where the blanking aperture array chip 212 through which multiple beams 20 pass is disposed. Accordingly, positional deviation of an electron beam resulting from the magnetic field B can be suppressed or reduced.
Although the first embodiment describes the configuration where a magnetic field itself is cancelled out by generating a current reverse to the current flowing in a power supply plane, the configuration for suppressing positional deviation of an electron beam occurring due to a magnetic field generated by a circuit current is not limited to the one described in the first embodiment.
The configuration of the writing apparatus according to the second embodiment is the same as that of
In the case where the blanking aperture array chip 212 is surrounded by the four correction coils 19a, 19b, 19c, and 19d, it is preferable that wiring of each coil is individually arranged along one of the four peripheral sides of the blanking aperture array chip 212. Thereby, a fixed magnetic field can be acted on each peripheral side.
The plurality of correction coils 19a, 19b, 19c, and 19d are independently controlled by the cancel circuit control unit 54.
The power supply plane 216 and the cancelling layer 218 are formed in the mounting substrate 211. The power supply plane 216 supplies power to the blanking aperture array chip 212. As described above, the magnetic field B is generated by a circuit current flowing in the mounting substrate 211. Therefore, positional deviation of the multiple beams 20 occurs.
According to the second embodiment, instead of cancelling out the magnetic field B itself, positional deviation of the multiple beams 20 is directly corrected by a magnetic field generated due to currents to flow in the plurality of correction coils 19a, 19b, 19c, and 19d.
In order that the position of the multiple beams 20 may not deviate by a magnetic field generated due to a current flowing in the power supply plane 216a (216b), the deflection control circuit 130 (an example of a control circuit) of the writing apparatus 100 supplies a current to the plurality of correction coils 19a, 19b, 19c, and 19d.
Specifically, the current measurement unit 52 measures a current flowing from the deflection control unit 50 to the power supply plane 216a (216b). The current measurement unit 52 inputs a calculation result calculated by the deflection control unit 50, and calculates the number of beams which are to be ON in the beam array at the left side (or right side). Based on the calculated number of beams, the current measurement unit 52 estimates (calculates) a current to flow from the deflection control unit 50 to the power supply plane 216a (216b). Then, the cancel circuit control unit 54 controls to individually flow, in each correction coil 19, a current for correcting positional deviation of the multiple beams 20 which occurs by the magnetic field B generated by the estimated (calculated) current. By this, the positional deviation of the multiple beams 20 which occurs by the magnetic field B generated by the current flowing in the power supply plane 216a (216b) is corrected by the magnetic field B′ generated by the currents flowing in the plurality of correction coils 19a, 19b, 19c, and 19d. A relational equation or a relational table for the size of a current flowing in the power supply plane 216a (216b), the amount of a positional deviation of the multiple beams 20, and the direction and size of a current to flow in each correction coil 19 for correcting the positional deviation is obtained in advance by an experiment or simulation.
The current to flow in the plurality of correction coils 19a, 19b, 19c, and 19d is variably controlled for each shot or each stripe region 32. In the case of performing the control for each stripe region 32, as described above, for example, it is acceptable to obtain a statistic value (e.g., average value) of a current flowing in the power supply plane 216a (216b) for each stripe region by previously executing a non-irradiation writing process before writing onto the target object 101, and to control, in actual writing processing, each correction coil 19 by a current in direction and size to flow in each correction coil 19 for correcting a positional deviation amount which corresponds to the current of the obtained statistic value.
Then, as writing processing similar to the first embodiment, the shot data generation step, the data processing step and the writing step described above are performed. In the writing step, a current individually controlled for each shot or each stripe is made to flow in each correction coil 19. Thereby, the multiple beams 20 can pass through the blanking aperture array chip 212 in the state where positional deviation has been corrected.
As described above, according to the second embodiment, it is possible to correct positional deviation of an electron beam (multiple beams 20) resulting from a magnetic field generated by a circuit current flowing in the mounting substrate 211 where a blanking aperture array chip 212 through which the multiple beams 20 pass is arranged.
Embodiments have been explained referring to specific examples described above. However, the present invention is not limited to these specific examples. In the above Embodiments, it is designed that, at the upper and lower sides of the power supply layer, GND layers are arranged serving as current return paths to cancel out an electromagnetic noise generated by the power supply layer. Since the electromagnetic noise cannot be completely cancelled out, it is intended to further reduce the electromagnetic noise by arranging a cancelling layer for exclusive use for magnetic field cancellation, and a magnetic field cancelling coil, and therefore, beam positional deviation can be suppressed.
While the apparatus configuration, control method, and others not directly necessary for explaining the present invention are not described, some or all of them can be appropriately selected and used on a case-by-case basis when needed. For example, although description of the configuration of the control unit for controlling the writing apparatus 100 is omitted, it should be understood that some or all of the configuration of the control unit can be selected and used appropriately when necessary.
Further, any blanking aperture array mechanism and writing apparatus that include elements of the present invention and that can be appropriately modified by those skilled in the art are included within the scope of the present invention.
Additional advantages and modification will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-085390 | May 2023 | JP | national |
