JP4327434B2 - Electron beam apparatus and electron beam writing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electron beam drawing technique for drawing a desired circuit pattern on a sample with an electron beam.
[0002]
[Prior art]
In the electron beam drawing technique, another new pattern is often drawn in accordance with the position of a pattern already formed on a sample (for example, a wafer). In order to perform such alignment drawing, the position of the alignment mark formed on the wafer is detected in advance, and a new pattern is drawn based on the position.
[0003]
In the production of devices, it is expected that wafers will become larger and patterns will become finer. In lithography technology for producing such a device, an electron beam lithography apparatus is used for a layer that requires high resolution in pattern formation, and another lithography apparatus with a high throughput (for example, an i-line stepper) is used for the other layers. The so-called mix-and-match usage is becoming mainstream.
[0004]
When using an electron beam lithography system in a mix-and-match method with another lithography apparatus, in order to use a common mark for interlayer alignment, the alignment mark used as standard in other lithography apparatuses is electronic It is necessary to detect even the beam drawing apparatus. By making the alignment mark for electron beam writing common to marks used in other lithography apparatuses, it is possible to apply the electron beam drawing technique without changing the reticle design of an existing process. In addition, with the miniaturization of patterns, alignment drawing with higher accuracy has been required for electron beam drawing.
[0005]
In the conventional electron beam drawing apparatus, the deflector for displacing the electron beam at the time of drawing is two stages of a main deflector and a sub deflector, or three stages including a sub sub deflector. In the case of three-stage deflection, the deflection amount of each deflector is about 5 mm, 500 μm, and 50 μm, respectively. An electromagnetic deflector may be used for the main deflection having the largest deflection amount, and the deflection speed is slower than the electrostatic deflector due to physical properties. In order to increase the deflection amount in the electrostatic type, it is necessary to make the deflector slender or increase the output of the drive power supply. When the deflector is thinned, there may be problems such as the risk of discharge due to the proximity of the electrodes, restrictions on optical characteristics / mounting, and high output of the power source, such as a decrease in driving speed.
[0006]
For each deflector, the deflection resolution suitable for the deflection amount is determined in comparison with the stability of the drive power supply and the number of bits held in the control system. When drawing, high resolution and high speed driving are required, and the lowest deflector is usually used. For example, in the case of the three-stage deflection, the sub-sub deflector corresponds to this, and the drawing area is about 50 μm square. The upper deflector plays a role of moving the lower deflection area.
[0007]
In order to improve throughput, that is, to shorten the total drawing time, it is necessary to perform measurement at high speed and high accuracy in mark position detection as well as drawing. Therefore, it is common to use the lowest-order drawing deflector when displacing the electron beam when detecting the mark position.
[0008]
Conventionally, the mark used in the electron beam drawing apparatus is, for example, a mark 11 ′ as shown in FIG. 2A, and the size is about 30 μm, which is set smaller than the drawing area. On the other hand, the mark used for the alignment of the stepper is a mark 11 as shown in FIG. 2B, for example, and has a size exceeding the drawing area of, for example, a width of 100 μm. The entire mark cannot be covered by scanning with the instrument. In this case, a drawing deflector for scanning a certain range on the mark, and an upper deflector (for example, a sub-deflector) capable of large-angle deflection for designating the center position of the scanning range by the deflector. It is used in combination to scan a wide area.
[0009]
The necessity and advantage of using a mark larger than the drawing distance in the background as described above are as follows: (1) The electron beam can be mixed and matched with other lithography, and (2) Mark production is easy. (3) The mark shape and position can be calibrated by light, and (4) the amount of detected current can be increased.
[0010]
In conventional electron beam drawing, low throughput is an issue, but a multi-electron beam drawing method in which a plurality of electron beams are used has been proposed to improve the throughput (for example, see Non-Patent Document 1).
[0011]
In the multi-electron beam drawing method, in order to perform drawing at high speed and high accuracy, the deflection amount of the drawing deflector is set to about the interval (several μm) between adjacent electron beams. Since the area where the plurality of electron beam arrays is drawn is about 100 μm, the amount of displacement of the upper deflector that moves the drawing area is set to about several mm. That is, in the multi-electron beam drawing apparatus, the deflection amount between the drawing deflector and the upper deflector is significantly different from that of the conventional electron beam drawing apparatus. Further, in order to detect the mark position using only the drawing deflector, a mark smaller than several μm is required.
[0012]
[Non-Patent Document 1]
"Journal of Vacuum Science and Technology, B18 (6), November / December 2000, 3061-3066"
[0013]
[Problems to be solved by the invention]
As described above, in the case of the multi-electron beam drawing apparatus, there is a large difference in the deflection amount between the drawing deflector and the upper deflector. If a higher-order deflector is used at the time of mark position detection, the deflection speed and accuracy are significantly reduced. Therefore, only the drawing deflector can perform mark detection at substantially high speed and high accuracy. Since the deflection amount of the drawing deflector is set to the interval between adjacent electron beams, it is possible to detect a mark smaller than this deflection amount by the conventional method, but it is impossible to detect a mark larger than the deflection amount. This is possible, and the conventional electron beam marks and other lithography marks described above cannot be detected, and there is a problem that the usable marks can be restricted.
[0014]
Further, if the electron beam diameter is reduced to draw a fine pattern, the current amount of each electron beam is reduced. Therefore, when mark detection is performed with one electron beam, there is a concern that the detection current amount with respect to noise at the time of detection is small and the detection accuracy is low.
[0015]
SUMMARY OF THE INVENTION An object of the present invention is to provide a mark position detection method capable of measuring a pattern larger than a drawing deflection distance in a multi-electron beam drawing apparatus, and to provide an electron beam drawing technique using the mark position detection method.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, an embodiment of a multi-electron beam drawing apparatus according to the present invention comprises: means for irradiating a plurality of electron beams to different positions at predetermined intervals on an object (sample); A selecting unit capable of selecting an electron beam to be irradiated to the object from the electron beam; a displacing unit configured to displace the plurality of electron beams by substantially the same amount of displacement in the scanning direction relative to the object; and the plurality of electrons by the displacing unit. Electron detection means for detecting reflected electrons, secondary electrons or transmitted electrons corresponding to each electron beam from the pattern when the beam is displaced in the scanning direction, the displacement amount of the displacement means, and the detection result of the electron detection means And determining means for determining the position of the pattern based on the relationship between
[0017]
The plurality of electron beams are arranged in a direction substantially perpendicular to the scanning direction and the scanning direction.
[0018]
The displacement means is a means different from that at the time of drawing at the time of pattern measurement (here, the displacement means at the time of drawing is referred to as displacement means 1, and the displacement means at the time of pattern measurement is referred to as displacement means 2). The means 2 measures a pattern having a length equal to or longer than the amount of displacement by the displacement means 1 (this displacement method is referred to as a displacement method 1).
[0019]
The displacement means 1 measures a pattern having a length longer than the displacement amount of the displacement means 1 alone by sequentially scanning a plurality of electron beams in the scanning direction while shifting the scanning start time. This displacement method is referred to as displacement method 2).
[0020]
The displacement means 2 measures a pattern having a length equal to or longer than the displacement amount by the displacement means 1 by sequentially scanning a plurality of electron beams in the scanning direction while shifting the scanning start time. This displacement method is referred to as displacement method 3). At this time, a combination of the number of electron beams sequentially scanned by the displacement method 1 and the displacement amount of the displacement means 2 is selected so that the measurement can be performed at high speed and with high accuracy.
[0021]
The displacement methods 2 and 3 select the plurality of electron beams in the scanning direction in accordance with the shape of the pattern to be measured when sequentially scanning at different scanning start times, thereby reducing the measurement time. And
[0022]
The electron detection means increases the detection current amount of the electron beam by selecting and using the plurality of electron beams in a direction substantially orthogonal to the scanning direction according to the shape of the pattern. .
[0023]
The electron detection means and the determination means select and use the plurality of electron beams in a direction substantially orthogonal to the scanning direction in accordance with the shape of the mark, whereby the edge roughness (pattern edge nonuniformity) of the pattern is selected. )) Is averaged by one measurement.
[0024]
The displacement methods 1 to 3 are characterized in that a pattern having a length equal to or longer than the plurality of electron beam intervals is measured.
[0025]
In this way, according to the present invention, it is possible to detect a pattern (alignment mark) larger than the drawing distance. As a result, mixing and matching with other lithography becomes possible. In addition, it is possible to verify the mark position and mark shape by light. In addition, the mark can be easily manufactured. Further, by selecting a plurality of electron beams to be scanned according to the shape of the mark, it is possible to realize high-accuracy alignment drawing.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0027]
FIG. 1 is a schematic view of a main part of an electron beam exposure apparatus according to the present invention. In FIG. 1, reference numeral 1 denotes an electron gun including a cathode 1a, a grid 1b, and an anode 1c. Electrons radiated from the cathode 1a form a crossover image between the grid 1b and the anode 1c (hereinafter referred to as this cross). Over image is referred to as light source).
[0028]
The electrons emitted from the light source become a substantially parallel electron beam by the irradiation lens 2 whose front focal position is at the light source position. The substantially parallel electron beam is incident on the element electron optical system array 3. The element electron optical system array 3 is formed by arranging a plurality of element electron optical systems each including an aperture 3a, an electron lens 3b, and a blanking electrode 3c in a direction substantially perpendicular to the optical axis AX. Details of the element electron optical system array 3 will be described later.
[0029]
The element electron optical system array 3 forms a plurality of intermediate images of the light source at the position of the blanking electrode 3 c, and each intermediate image is reduced and projected by a reduction electron optical system 4 (to be described later). Form an image.
[0030]
The reduction electron optical system 4 includes a symmetric magnetic doublet including a set of a first projection lens 41 and a second projection lens 42, and a set of a first projection lens 43 and a second projection lens 44. When the focal length of the first projection lens 41 (43) is f1, and the focal length of the second projection lens 42 (44) is f2, the distance between the two lenses is f1 + f2. The object point on the optical axis AX is at the focal position of the first projection lens 41 (43), and the image point is connected to the focal point of the second projection lens 42 (44). This image is reduced to -f2 / f1. Since the two lens magnetic fields are set so as to act in opposite directions, theoretically, except for the five aberrations of spherical aberration, isotropic coma aberration, curvature of field aberration, and axial chromatic aberration Seidel aberrations and chromatic aberrations related to rotation and magnification are canceled out.
[0031]
A drawing deflector (6) deflects a plurality of electron beams from the element electron optical system array 3 and displaces a plurality of light source images on the object (wafer) 5 by substantially the same amount of displacement in the X and Y directions. A sub-deflector) 7 is a main deflector for displacing a region scanned by the sub-deflector 6. Both the main deflector and the sub deflector are electrostatic deflectors.
[0032]
Reference numeral 8 denotes a dynamic focus electrode that corrects the deviation of the focus position of the light source image by the deflection aberration generated when the deflectors 6 and 7 are operated. Reference numeral 9 denotes the same as the dynamic focus electrode 8 that is generated by deflection. This is a dynamic stig electrode that corrects astigmatism of deflection aberration. An electric field may be superimposed on the deflector 6 or 7 instead of the dynamic stig electrode 9.
[0033]
10 and 10 ′ are reflected electrons generated when the electron beam from the element electron optical system array 3 irradiates an object (wafer) 5 or a pattern for alignment formed on the object 5, that is, an alignment mark 11, or A detector for detecting secondary electrons or transmitted electrons, 10 is a reflection / secondary electron detector, and 10 ′ is a transmission electron detector.
[0034]
Reference numeral 12 denotes a stage on which the object (wafer) 5 is placed and can move in the XY direction substantially orthogonal to the optical axis AX (Z axis) and the rotation direction around the Z axis and the optical axis AX (Z axis).
[0035]
Next, each element electron optical system will be described.
[0036]
In the element electron optical system array 3, reference numeral 3 a denotes a substrate having an aperture that defines the shape of the transmitted electron beam. Reference numeral 3b denotes an electron lens using a unipotential lens having a convergence function, which is composed of three aperture electrodes, the upper and lower electrodes are made the same as the acceleration potential VO, and the intermediate electrode is kept at another potential. Reference numeral 3c denotes a blanking electrode composed of a pair of electrodes and having a deflection function.
[0037]
The upper and lower electrodes 310a and 310c of the unipotential lens are set to a common potential in all element electron optical systems by a focus / astigmatism control circuit 1 (15) described later.
[0038]
Since the potential of the intermediate electrode 310b of the unipotential lens can be set for each element electron optical system by the focus / astigmatism control circuit 1 (15), the focal length of the unipotential lens 3b can be set for each element electron optical system. As a result, the electron optical characteristics (intermediate image forming position, astigmatism) of the element electron optical system can be controlled.
[0039]
The electron beam made substantially parallel by the irradiation lens 2 forms an intermediate image of the light source at the position of the blanking electrode 3c by the electron lens 3b through the opening 3a. At this time, if the electric field is not applied between the blanking electrodes 3c (off state), the electron beam 31 is not deflected. On the other hand, when an electric field is applied between the blanking electrodes 3c (on state), they are deflected like electron beams 32 and 33 (the optical paths before being deflected are indicated by dotted lines 32 'and 33'). . Since the electron beam 31 and the electron beams 32 and 33 have different angular distributions on the object plane of the reduction electron optical system 4, the electron beam 31 and the electron beam are at the pupil position (on the P plane in FIG. 1) of the reduction optical system 4. 32 and 33 are incident on different regions. On the object (wafer) 5, a reduced image of the multi-light source formed by the element electron optical system array 3 is formed. A blanking aperture BA is provided at the pupil position (on the P plane in FIG. 1) of the reduction electron optical system to block the electron beam whose blanking electrode 3c is on. In the example of FIG. Only the object (wafer) 5 is irradiated, and the other electron beams 32 and 33 are not irradiated.
[0040]
Next, the system configuration of the present embodiment will be described.
[0041]
The irradiation electron optical system control circuit 13 is a control circuit that adjusts the irradiation condition of the electron beam to the element electron optical array 3 by changing the excitation current of the irradiation lens 2.
[0042]
The blanking control circuit 14 is a control circuit for individually turning on / off the blanking electrode 3c of each element electron optical system of the element electron optical array 3, and the focus / astigmatism control circuit 1 (15) is the element electron optical array 3 2 is a control circuit that individually controls the electro-optical characteristics (intermediate image forming position, astigmatism) of each of the element electron optical systems.
[0043]
The focus / astigmatism control circuit 2 (16) is a control circuit for controlling the dynamic stig coil 8 and the dynamic focus coil 9 to control the focus position and astigmatism of the reduction electron optical system 4, and the deflection control circuit 17 is for deflecting. The magnification adjustment circuit 18 is a control circuit that adjusts the magnification of the reduction electron optical system 4, and the optical characteristic circuit 19 is a component of the reduction electron optical system 4. This is a control circuit for adjusting the rotational aberration and the optical axis by changing the excitation current of the electromagnetic lens.
[0044]
The stage drive control circuit 20 is a control circuit that drives and controls the XY stage in cooperation with the laser interference system 21 that drives and controls the θ-Z stage and detects the position of the XY stage.
[0045]
The control system 22 controls the plurality of control circuits and the detector 10 in synchronization for exposure and alignment based on data from the memory 23 in which information related to the drawing pattern is stored. The control system 22 is controlled by a CPU 25 that controls the entire electron beam exposure apparatus via an interface 24.
[0046]
Next, a method for displacing the electron beam during writing will be described with reference to FIG. Here, an electron beam array formed by 9 × 9 square lattice element electron optical system array will be described as an example.
[0047]
Reference numeral 300 denotes an area in which an electron beam array on an object (wafer) is scanned by a drawing deflector (sub-deflector), which is called a subfield (SF). The displacement range of the drawing deflector is set to the interval between individual electron beams (dotted circles in the figure), and is about several μm square. Reference numeral 301 denotes a displacement region of each electron beam by the drawing deflector. The SF (304) is formed by several tens of several tens of electron beams and has a size of about 100 μm square (in this example, the number of electron beams is reduced for ease of explanation).
[0048]
The SF is deflected by the main deflector 7. The displacement range is indicated by 302. This displacement area is called a main field (MF) (303) and is about several mm square.
[0049]
Further, the MF is displaced by the stage movement 304 to cover the drawing pattern on the object (wafer).
[0050]
Next, an example of pattern measurement, particularly a mark detection method, in which a deflector for pattern measurement is separately provided will be described with reference to FIG.
[0051]
On the object (wafer) 5, a reduced image of the multi-light source formed by the element electron optical system array 3 is formed. If all of the blanking electrodes 3c are on, all electron beams are blocked by the blanking aperture BA, so that no electron beam is irradiated onto the object (wafer). When detecting the mark position, the control system 22 drives the stage so that the electron beam is not irradiated onto the object (wafer) 5 in advance and the stage 12 is driven so that the mark 11 is positioned substantially on the optical axis AX. A command is sent to the control circuit 20.
[0052]
In this detection method, the electron beam closest to the optical axis is used in the measurement direction (electron beam 402 in FIG. 4). Of all the electron beams that have been blanked until then, only the blanking electrode 3c of the electron beam 402 used for mark detection is turned off, and the control system 22 blocks the electron beam 402 so that the electron beam 402 reaches the object (wafer) 5. A blanking release signal is sent to the ranking control circuit 15. At this time, the other beams 401 and 403 are blocked by the blanking aperture BA and do not reach the object (wafer) 5. The amount of displacement of the electron beam 402 on the object (wafer) 5 by the drawing deflector 6 is indicated by an arrow 410. The displacement amount 410 of the electron beam is smaller than the width of the mark 11.
[0053]
In this detection method, a deflector 400 is added for pattern measurement. An electron beam deflection signal is sent from the control system 22 to the deflection control circuit 17, and the electron beam 402 is scanned on the object (wafer) 5. At this time, when the pattern measuring deflector 400 is used, the object (wafer) 5 is scanned from 402a to 402a ′.
[0054]
The amount of reflected electrons, secondary electrons, or transmitted electrons when the electron beam 402a-402a 'is scanned on the mark 11 is detected by a detector, and the obtained detection signal is offset and gain adjusted by the gain adjusting circuit 26. After that, it is converted into a digital signal by the A / D converter 27 and used as a mark signal (FIG. 4 illustrates the transmission electron detector 10 ′). This mark signal reflects the cross-sectional shape of the mark. In the signal processing circuit 28, signal processing for detecting the mark center position is performed based on the mark signal converted into the digital signal.
[0055]
The beam selection according to the pattern shape in this embodiment, especially the alignment mark shape, will be described with reference to FIGS. Here, 18 × 18 square lattice electron beam rows (X, Y) (X = 1 to 18, Y = 1 to 18) will be described as an example.
[0056]
In FIG. 5, since the electron beam close to the optical axis in the measurement direction is X = 9 or 10, X = 9 is used here.
[0057]
FIG. 6 schematically shows temporal changes of the deflection signal and the blanking signal when the bar-shaped mark 11 shown in FIG. 5 is scanned. The deflection signal to the deflector 400 is one time, and the blanking signal is off only for X = 9, and is otherwise on.
[0058]
A mark used for position detection is generally formed by providing a step or a groove on an object (wafer) or using a different substance. The step at this time or the boundary between different substances is called the mark edge. In mark detection, an object of normal measurement is a mark edge substantially perpendicular to the scanning direction. If a plurality of electron beams in a direction substantially orthogonal to the scanning direction are at the same position in the scanning direction, it is possible to scan substantially simultaneously within a range that does not protrude an edge used for the measurement (scanned edge). .
[0059]
In the bar-shaped mark 11 of FIG. 5, it is possible to perform mark detection using a plurality of electron beams Y = 4-15. All the reflected electrons, secondary electrons, or transmitted electrons generated by the plurality of electron beams are added and detected. As a result, the amount of detected current increases and the detection efficiency increases.
[0060]
Generally, the edge of a mark is not a straight line but is non-uniform (edge roughness). Since this edge roughness becomes uncertain in the mark position detection, conventionally, an average of a plurality of scans in which the location is changed little by little is taken. By simultaneously scanning a plurality of electron beams substantially parallel to the scanned edge as in the present invention, the edge roughness can be averaged by a single scan, and the measurement time for mark detection can be shortened. Become.
[0061]
In the cross mark 11 ′ in FIG. 7, the electron beams of Y = 6 to 8, 11 to 13 are in the range where the scanned edge does not protrude. By detecting all the reflected electrons, secondary electrons, or transmitted electrons by the plurality of electron beams, the amount of detected current increases, and the edge roughness can be averaged by one measurement.
[0062]
Next, an example of a pattern measuring method for sequentially scanning by shifting the scanning start times of a plurality of electron beams, particularly an alignment mark detecting method, will be described with reference to FIG. The amount of displacement of the electron beam on the object (wafer) 5 by the drawing deflector 6 is indicated by an arrow 600. The mark 11 on the object (wafer) 5 used for alignment drawing has a width in the scanning direction larger than the displacement amount (arrow 600) by the deflector 6.
[0063]
When detecting the mark position, all the blanking electrodes 3c are turned on in advance so that the electron beam is not irradiated onto the object (wafer) 5, and the stage 12 is driven so that the mark 11 is positioned substantially on the optical axis AX. .
[0064]
Next, of all the electron beams that have been blanked until then, only the blanking electrode 3c of the electron beam 601 used for mark detection is turned off first, and control is performed so that the electron beam 601 reaches the object (wafer) 5. A blanking release signal is sent from the system 22 to the blanking control circuit 15. At this time, the other beams 602 and 603 are blocked by the blanking aperture BA and do not reach the object (wafer). When an electron beam deflection signal is sent from the control system 22 to the deflection control circuit 17, the deflector 6 scans the electron beam 601 on the object (wafer) 5 as shown in 6010-6011 shown in FIG.
[0065]
At the same time when the scanning of the electron beam 601 is completed, only the blanking electrode 3c of the beam 602 is turned off as shown in FIG. 8B, and the next scanning is performed. As a result, the beam moves from 6020 to 6021. Thereafter, only the blanking electrode 3c of the beam 603 is turned off, and the beam is moved from 6030 to 6031 as shown in FIG. In this way, by changing the scanning start time and changing the electron beam to be sequentially scanned, it is possible to scan the region from 6010 to 6031.
[0066]
Reflected electrons, secondary electrons, or transmitted electrons when the mark 11 is scanned with the electron beam 6010-6031 are detected by a detector, and the obtained detection signal is offset and the gain adjustment circuit 26 performs offset and gain adjustment. Thereafter, it is converted into a digital signal by the A / D converter 27 and used as a mark signal (in FIG. 8, the reflection / secondary electron detector 10 is illustrated). This mark signal reflects the cross-sectional shape of the mark. In the signal processing circuit 28, signal processing for detecting the mark center position is performed based on the mark signal converted into the digital signal.
[0067]
9 to 13 show beam selection according to the pattern shape, particularly the alignment mark shape. Here, a description will be given by taking 18 × 18 square lattice electron beam rows as an example.
[0068]
In the mark detection, all the electron beams with the blanking electrode 3c turned off are scanned substantially simultaneously. When there is one detector, the reflected electrons or the reflected electrons by all the electron beams with the blanking electrode 3c turned off or Secondary electrons or transmitted electrons are added and detected.
[0069]
If a plurality of electron beams in a direction substantially orthogonal to the scanning direction are at the same position in the scanning direction, they can be scanned almost simultaneously within a range that does not protrude an edge used for measurement (scanned edge).
[0070]
In the rod-shaped mark 11 of FIG. 9, the range that is substantially orthogonal to the scanning direction (X) and does not protrude from the plurality of electron beams (X, Y) (X = 1 to 18, Y = 1 to 18). The electron beam of Y = 4-15. For each X value, Y = 4-15 electron beams are scanned simultaneously. X is sequentially scanned by shifting the start time from 1 to 18. FIG. 10 schematically shows temporal changes of the deflection signal and the blanking signal at this time. In order to scan X = 1 to 18 in FIG. 9, the deflection signal to the deflector 6 is issued 18 times. In synchronization with the deflection signal, the blanking signal is turned off one by one in order from X = 1 to 18 (on otherwise).
[0071]
All reflected electrons, secondary electrons, or transmitted electrons by the electron beam of Y = 4 to 15 that are simultaneously scanned for each X are added and detected. By adding a plurality of electron beams, the amount of detection current increases and the detection efficiency increases.
[0072]
In the cross mark 11 ′ in FIG. 11, the electron beams of Y = 6 to 8, 11 to 13 are electron beams in a range that does not protrude the scanned edge. By detecting all the reflected electrons, secondary electrons, or transmitted electrons by the plurality of electron beams, the amount of detected current increases, and the edge roughness can be averaged by one measurement.
[0073]
In the method of sequentially scanning a plurality of electron beams in the present invention, the scanning time of the mark can be shortened by selecting the electron beam according to the pattern, that is, the shape of the mark in the scanning direction. In this case, it is desirable to select so that the scanning area of the electron beam is the minimum number including the mark.
[0074]
In the case of the bar-shaped mark 11 in FIG. 12, if the blanking electrode 3c is turned off in the order of X = 1 to 2, 4 to 5, 7 to 8, 10 to 11, 13 to 14, and 16 to 17, X = Scanning in 2/3 time when all of 1 to 18 are sequentially turned off is possible.
[0075]
In FIG. 8, a pattern measurement deflector 400 can be used in place of the drawing deflector 6 to detect the position of a mark having a length equal to or greater than the displacement amount of the drawing deflector 6. At this time, a combination of the displacement amount of the pattern measurement deflector 400 and the number of electron beams to be sequentially scanned is selected, and considering the number of electron beams to be used and the power supply voltage / holding bit number of the pattern measurement deflector 400 control circuit, Select conditions for measuring with high accuracy.
[0076]
In FIG. 13, when the displacement amount of the deflector 400 is an arrow 700, the blanking electrode 3c is turned off in the order of X = 2, 5, 8, 11, and 14, and mark detection can be performed.
[0077]
As described above in detail, in the present invention, by adding a displacement means for pattern measurement different from the electron beam displacement means used at the time of drawing, pattern measurement having a length longer than the amount of displacement by the electron beam displacement means used at the time of drawing. Can be done. This makes it possible to mix and match with other lithography, and to verify the shape and position of the mark by light, facilitating mark manufacture.
[0078]
Further, by sequentially scanning a plurality of electron beams arranged in the scanning direction at the time of pattern measurement while shifting the scanning start time, it is possible to measure a pattern having a length longer than the amount of displacement by the electron beam displacement means used at the time of drawing. This makes it possible to mix and match with other lithography, and to verify the shape and position of the mark by light, facilitating mark manufacture.
[0079]
Also, by using the pattern measurement displacement means and sequentially scanning a plurality of electron beams arranged in the scanning direction at the time of pattern measurement while shifting the scanning start time, the length of the electron beam displacement amount used at the time of drawing or more Pattern measurement can be performed. This makes it possible to mix and match with other lithography, and to verify the shape and position of the mark by light, facilitating mark manufacture. Further, a combination of the displacement amount of the pattern measuring displacement means and the number of electron beams to be sequentially scanned can be selected so that the measurement can be performed at high speed and with high accuracy.
[0080]
In addition, by selecting and scanning the plurality of electron beams arranged in the scanning direction according to the shape of the pattern to be measured and performing pattern measurement, the measurement time can be shortened as compared with the case of scanning the whole.
[0081]
In addition, by selecting and scanning a plurality of electron beams arranged in the same position in the scanning direction and in a direction substantially orthogonal to the scanning direction according to the pattern shape, the amount of detected current is increased and the pattern edge is reduced. Uniformity can be averaged by a single measurement, enabling high-speed and high-precision measurement.
[0082]
In all the embodiments described above, a system in which an electron beam emitted from one electron source is divided into a plurality of electron beams by an element optical system has been described, but the same applies to a multi-beam system using a plurality of light sources.
[0083]
【The invention's effect】
According to the present invention, in a multi-electron beam drawing apparatus, it is possible to realize a mark position detection method that enables pattern measurement larger than the drawing deflection distance, and to provide an electron beam drawing technique using the mark position detection method.
[Brief description of the drawings]
FIG. 1 is a diagram showing an outline and a system configuration of an essential part of an electron beam exposure apparatus according to the present invention.
FIG. 2 is a diagram showing an example of a mark shape to be detected in the present invention.
FIG. 3 is a diagram for explaining a method of displacing an electron beam during writing.
FIG. 4 is a view for explaining a method of separately providing a pattern measuring deflector and detecting a pattern (mark) larger than each scanning distance.
FIG. 5 is a view for explaining an example of beam selection according to a mark shape when pattern measurement (mark detection) is performed by separately providing a deflector for pattern measurement.
6 is a diagram showing temporal changes of a deflection signal and a blanking signal when the mark shown in FIG. 5 is scanned. FIG.
FIG. 7 is a diagram for explaining another example of beam selection according to the mark shape in FIG.
FIG. 8 is a diagram for explaining a method of sequentially scanning by shifting the scanning start times of a plurality of electron beams and performing pattern measurement (mark detection) larger than each scanning distance.
FIG. 9 is a diagram for explaining an example of beam selection according to a pattern (mark) shape when pattern measurement (mark detection) is performed by sequentially scanning a plurality of electron beams.
10 is a diagram showing temporal changes of a deflection signal and a blanking signal when the mark shown in FIG. 9 is scanned. FIG.
FIG. 11 is a diagram for explaining another example of beam selection according to the mark shape in FIG. 9;
12 is a diagram for explaining still another example of beam selection according to the mark shape in FIG. 9. FIG.
13 is a diagram for explaining still another example of beam selection according to the mark shape in FIG. 9;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Electron gun, 1a ... Cathode, 1b ... Grid, 1c ... Anode, 2 ... Irradiation lens, 3 ... Element electron optical system array, 3a ... Electron beam division | segmentation aperture substrate, 3b ... Electron lens, 310a ... Upper electrode, 310b ... Intermediate electrode, 310c ... lower electrode, 3c ... blanking electricity, 4 ... reduction electron optical system, 41 ... first reduction system first projection lens, 42 ... first reduction system second projection lens, 43 ... second reduction system first 1 projection lens, 44 ... second reduction system second projection lens, 5 ... object (wafer), 6 ... sub-deflector, 7 ... main deflector, 8 ... dynamic focus electrode, 9 ... dynamic stig electrode, 10 ... reflector Secondary electron detector, 10 '... transmission electron detector, 11, 11' ... mark, 12 ... sample stage, 13 ... irradiation electron optical system control circuit, 14 ... blanking control circuit, 15 ... focus / astigmatism control circuit 1, 16 ... Focus / Non Control circuit 2, 17 ... Deflection control circuit, 18 ... Magnification control circuit, 19 ... Optical characteristic control circuit, 20 ... Stage drive control circuit, 21 ... Laser interferometer, 22 ... Control system, 23 ... Memory, 24 ... Interface, 25 ... CPU, 26 ... offset, gain adjustment circuit, 27 ... A / D converter, 28 ... signal processing circuit, 31 ... electron beam not blanked, 32 ... blanked electron beam, 32 '... 32 blanked , 33... Blanked electron beam, 33 ′... 33 before trajectory, AX... Optical axis, BA... Blanking aperture, P. ... Subfield (SF) 301. Region where one electron beam is scanned by the drawing deflector (deflector 6) 302. Displacement region due to the main deflector 303. Field: MF, 304: Stage movement area, 400: Pattern measurement deflector, 401: Electron beam not used for pattern measurement (mark detection), 402: Electron beam used for pattern measurement (mark detection), 402a: Pattern Displacement start position by measurement deflector, 402a '... Displacement end position by pattern measurement deflector, 403 ... Electron beam not used for pattern measurement (mark detection), 410 ... Displacement range by deflector 6, 600 ... Deflector 6 601 ... electron beam scanned first, 6010 ... 601 displacement start position by deflector 6, 601 ... 601 displacement end position by deflector 6, 602 ... second scanned electron beam, 6020 ... displacement start position by deflector 6 of 602, displacement end position by deflector 6 of 6021 ... 602, 6 03 ... Electron beam scanned third, 6030 ... 603 displacement start position by deflector 6, 6031 ... 603 displacement end position by deflector 6, 700 ... Displacement range by deflector 400.

Claims (6)

Means for irradiating a pattern formed on a sample using a plurality of electron beams arranged at predetermined intervals;
A selection means capable of selecting an electron beam to be applied to the sample from the plurality of electron beams;
A displacement means for displacing the plurality of electron beams selected from the plurality of electron beams by substantially the same amount of displacement in the scanning direction with respect to the sample;
Electron detection means for detecting reflected electrons, secondary electrons or transmitted electrons emitted from the pattern when the electron beam is displaced in the scanning direction by the displacement means;
The displacement means includes a first electron beam displacement means used when performing a desired scan on the sample, and a second electron beam displacement means different from the first electron beam displacement means,
The plurality of electron beams are arranged in the scanning direction and a direction substantially orthogonal to the scanning direction,
According to the shape of the pattern, an electron beam is selected from the plurality of electron beams,
The second electron beam displacing means is used to scan the selected electron beam, thereby measuring the position of a pattern having a magnitude greater than or equal to the amount of displacement by the first electron beam displacing means. An electron beam apparatus characterized by that. Means for irradiating a pattern formed on a sample using a plurality of electron beams arranged at predetermined intervals;
A selection means capable of selecting an electron beam to be applied to the sample from the plurality of electron beams;
A displacement means for displacing the plurality of electron beams selected from the plurality of electron beams by substantially the same amount of displacement in the scanning direction with respect to the sample;
Electron detection means for detecting reflected electrons, secondary electrons or transmitted electrons emitted from the pattern when the electron beam is displaced in the scanning direction by the displacement means;
The plurality of electron beams arranged in the scanning direction at the time of measuring the position of the pattern are sequentially scanned while shifting the scanning start time so that the position of the pattern having a magnitude larger than the displacement amount by the displacement means is measured. An electron beam apparatus characterized by comprising. The electron beam apparatus according to claim 1 or 2,
An electron beam apparatus comprising: a plurality of the electron beams arranged in the scanning direction that are selected and scanned in accordance with the shape of the pattern to be measured to measure the position of the pattern. Electrons that draw a desired pattern by irradiating a sample with a plurality of electron beams arranged at predetermined intervals while being displaced by substantially the same amount of displacement using the first electron beam displacement means. In the line drawing method,
From the plurality of electron beams arranged in the scanning direction and a direction substantially orthogonal to the scanning direction, an electron beam radiated to the alignment drawing pattern formed on the sample is formed in the shape of the drawing pattern. Select according to
Displace the selected electron beam using a second electron beam displacing means different from the first electron beam displacing means and irradiate the pattern for alignment drawing,
By detecting secondary electrons or transmitted electrons radiated from the alignment drawing pattern by the irradiation, position measurement of the alignment drawing pattern having a magnitude larger than the displacement amount by the first electron beam displacing means is performed. An electron beam drawing method comprising: Irradiating a plurality of electron beams arranged in the scanning direction when measuring the position of the alignment drawing pattern formed on the sample by using the electron beam displacing means to be displaced by substantially the same amount of displacement in the scanning direction of the electron beam. In the electron beam drawing method for drawing a desired pattern by
From the plurality of electron beams, select an electron beam to irradiate the pattern for alignment drawing formed on the sample,
By sequentially scanning the plurality of electron beams while shifting the scanning start time, the position of the alignment drawing pattern formed on the sample having a magnitude greater than or equal to the amount of displacement by the electron beam displacement means is measured. An electron beam drawing method. The electron beam writing method according to claim 5.
Position measurement of the drawing pattern by selecting and scanning a plurality of electron beams arranged in the scanning direction and a direction substantially orthogonal to the scanning direction according to the shape of the alignment drawing pattern formed on the sample An electron beam drawing method characterized in that:

Images