1. Field of the Invention
The present invention relates to a drawing apparatus, and a method of manufacturing an article.
2. Description of the Related Art
Along with micropatterning and high integration of circuit patterns in semiconductor devices, attention is paid to a drawing apparatus which draws a pattern on a substrate with a plurality of charged particle beams (electron beams). A semiconductor device is manufactured by overlaying a plurality of patterns on one substrate. It is therefore important for the drawing apparatus to draw a pattern at high precision in a shot region formed on a substrate.
However, a shot region formed on a substrate is sometimes formed in a shape different from a shape to be originally formed, that is, is deformed and formed. If a shot region is deformed and formed on a substrate, it may become difficult to draw a pattern in the shot region at high overlay precision. To solve this, Japanese Patent No. 3647128 has proposed a drawing apparatus in which, when the shape of a shot region formed on a substrate contains a magnification component, the interval between a plurality of charged particle beams irradiating the substrate is changed to correct the magnification component.
It is rare that the deformation component of a shot region formed on a substrate contains only a magnification component. In general, the deformation component may contain a component such as a rotation component. In this case, it is difficult to correct the rotation component in the shot region by only changing the interval between a plurality of charged particle beams irradiating a substrate, as in the drawing apparatus described in Japanese Patent No. 3647128.
The present invention provides, for example, a drawing apparatus advantageous in terms of overlay precision.
According to one aspect of the present invention, there is provided a drawing apparatus which performs drawing on a substrate with a plurality of charged particle beams, the apparatus comprising: a blanker array including a plurality of blankers and configured to individually blank the plurality of charged particle beams; a plurality of deflectors configured to individually deflect a plurality of charged particle beam groups constituting the plurality of charged particle beams; and a controller configured to individually control positions of the plurality of charged particle beam groups by the plurality of deflectors, and individually control blanking of the plurality of charged particle beams by the blanker array, based on information of a region on the substrate where a shot region exists.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Exemplary embodiments of the present invention will be described below with reference to the accompanying drawings. Note that the same reference numerals denote the same members throughout the drawings, and a repetitive description thereof will not be given.
A drawing apparatus 100 according to the first embodiment of the present invention will be explained with reference to
A charged particle source 201 uses, for example, a thermoelectron emitting electron source containing an electron emitting material such as LaB6. A condenser lens 203 changes a charged particle beam 202 emitted by the charged particle source 201 into a parallel beam, and the parallel beam enters an aperture array 204. The aperture array has a plurality of openings, and splits the charged particle beam 202 incident as the parallel beam into a plurality of charged particle beams. The charged particle beams split by the aperture array 204 enter a lens array 205. The lens array 205 is constituted by three electrode plates in which a plurality of openings are formed. By giving a potential difference between the central electrode plate, and the upper and lower electrode plates sandwiching it, the plurality of openings can function as lenses. Each charged particle beam having passed through the lens array 205 forms an intermediate image 209 of the crossover image of the charged particle source near a blanking aperture 208 by the action of the lens array 205. The position of the intermediate image 209 changes in the optical axis direction (Z direction) by changing a voltage applied to the lens array 205. A blanker array 207 having a plurality of blankers for individually blanking a plurality of split charged particle beams is interposed between the lens array 205 and the blanking aperture 208. Each blanker constituting the blanker array 207 is formed from, for example, two facing electrodes. The blanker generates an electric field by applying a voltage between the two electrodes, and can deflect a charged particle beam. The charged particle beam deflected by the blanker is blocked by the blanking aperture 208 and does not reach the substrate. To the contrary, a charged particle beam not deflected by the blanker passes through the opening formed in the blanking aperture 208, and reaches the substrate. That is, the blanker array 207 individually switches a charged particle beam between irradiation and no irradiation of the substrate 1.
A charged particle beam having passed through the blanking aperture 208 passes through a first projection lens 210 and second projection lens 214. Accordingly, the intermediate image 209 formed near the blanking aperture 208 is projected on the substrate. A lens control unit 222 (to be described later) controls the first projection lens 210 and second projection lens 214 so that a focus position at the rear stage of the first projection lens 210 and a focus position at the front stage of the second projection lens 214 coincide with each other. This arrangement of the first projection lens 210 and second projection lens 214 is called a symmetrical magnetic tablet lens configuration, and the intermediate image 209 can be projected on the substrate 1 with low aberration. A plurality of charged particle beams irradiating the substrate 1 are deflected at once by a main deflector 213 and sub-deflector 215 and can be scanned on the substrate. For example, an electromagnetic deflector is used as the main deflector 213, and an electrostatic deflector is used as the sub-deflector 215. The sub-deflector 215 is configured so that the amount by which a plurality of charged particle beams are deflected becomes smaller than that by the main deflector 213. The sub-deflector 215 can finely adjust deflection of a plurality of charged particle beams. A dynamic focus corrector 211 corrects a defocus caused by deflection aberration generated when the main deflector 213 and sub-deflector 215 deflect a plurality of charged particle beams. Similar to the dynamic focus corrector 211, a dynamic astigmatism corrector 212 corrects astigmatism generated by deflection of a plurality of charged particle beams. The dynamic focus corrector 211 and dynamic astigmatism corrector 212 can be constituted by, for example, coils.
The substrate stage 20 holds the substrate 1, and when drawing is performed on the substrate 1 with a plurality of charged particle beams, moves under the control of a substrate stage control unit 226. The substrate stage 20 includes a measurement unit 21 which measures the position of each charged particle beam emitted from the drawing system 10. The measurement unit 21 includes, for example, knife edges in the X and Y directions, and Faraday cups which detect charged particle beams having passed through the knife edges. While the substrate stage 20 is moved in the X and Y directions, the measurement unit 21 detects a charged particle beam by using the Faraday cups, and can measure the position of each charged particle beam emitted from the drawing system 10.
The control system 30 includes, for example, a lens array control unit 220, a blanking control unit 221, the lens control unit 222, a deflection control unit 223, an alignment control unit 224, a stage control unit 225, and the main control unit 226. The lens array control unit adjusts the position of the intermediate image 209 by giving a potential difference to three electrodes constituting the lens array 205. The blanking control unit 221 controls the blanker array 207 based on control data supplied from the main control unit 226. The lens control unit 222 controls the first projection lens 210 and second projection lens 214 so that a focus position at the rear stage of the first projection lens 210 and a focus position at the front stage of the second projection lens 214 coincide with each other. The deflection control unit 223 controls the main deflector 213 and sub-deflector 215 in each drawing unit 11 to individually deflect a plurality of charged particle beam groups. The deflection control unit 223 also controls the dynamic focus corrector 211 and dynamic astigmatism corrector 212. The alignment control unit 224 controls a detection unit 22 (to be described later). The stage control unit 225 controls movement of the substrate stage 20. The main control unit 226 includes a CPU and memory, and comprehensively controls the respective units in the control system 30 (controls drawing processing).
A method of measuring the shape of each of a plurality of shot regions 24 formed on the substrate 1 will be explained.
A method of performing drawing on the substrate 1 based on the shape of each shot region 24 obtained by global alignment measurement in the drawing apparatus 100 having the above-described arrangement will be explained. In the first embodiment, drawing is performed in parallel in two shot regions 24a and 24b surrounded by a dotted line in
x
ave=(xs24a+xs24b)/2
y
ave=(ys24a+ys24b)/2
Rotave=(Rots24a+Rots24b)/2 (1)
The thus-obtained average values (xave, yave, Rotave) of the respective components are used as the offset amount of the moving amount of the substrate stage 20 when the substrate 1 is arranged at a position at which drawing in the shot regions 24a and 24b starts. That is, when a plurality of deflectors individually control the positions of a plurality of charged particle beam groups, the position of the substrate stage 20 is controlled to decrease the maximum value of a deflection amount by which each charged particle beam group is deflected.
Next, a method of starting drawing on the substrate 1 with a plurality of charged particle beams after moving the substrate stage 20 in the above-described manner will be explained with reference to
Next, the adjustment amount in each charged particle beam group will be explained. For example, when the shot region 24 rotates at an angle θp, the adjustment amounts ΔSn_x and ΔSn_y of each charged particle beam group in the X and Y directions can be calculated by:
ΔSn—x=Ly×(my−1)×tan(θp)
ΔSn—y={Lx×(mx−1)+Lsx}×tan(θp) (2)
where Lx is the interval of the charged particle beam group in the X direction (interval of the region 30 in the X direction), Ly is the interval of the charged particle beam group in the Y direction (interval of the region 30 in the Y direction), Lsx is the width of the region 30 in the X direction, and mx and my are the coordinates of the region 30 in the X and Y directions, respectively, as described above.
For example, the adjustment amounts ΔS1—x and ΔS1—y of the charged particle beam group for performing drawing in the region s1 shown in
ΔS1—x=2b×(1−1)×tan θ1=0
ΔS1—y={2a×(1−1)+a}×tan θ1=a×tan θ1 (3)
Similarly, the adjustment amounts ΔS2—x and ΔS2—y of the charged particle beam group for performing drawing in the region s2 shown in
ΔS2—x=2b×(2−1)×tan θ1=2b×tan θ1
ΔS2—y={2a×(1−1)+a}×tan θ1=a×tan θ1 (4)
The adjustment amounts in each charged particle beam group are calculated in this fashion, respectively, and the main control unit 226 controls the deflectors (main deflector 213 and sub-deflector 215) of each drawing unit 11 based on the calculated adjustment amounts. In the drawing apparatus 100 according to the first embodiment, the reference position of each charged particle beam group can be adjusted in accordance with the shape of the shot region 24 formed on the substrate 1, as shown in
As described above, the drawing apparatus 100 according to the first embodiment adjusts the reference position of each charged particle beam group in accordance with the shape of the shot region 24 formed on the substrate 1 for each charged particle beam group by the deflectors of each drawing unit 11. Even when the shot region 24 formed on the substrate 1 contains a rotation component, a pattern can be drawn in the shot region 24 at high precision.
The drawing apparatus 100 according to the first embodiment includes the plurality of drawing units 11 each including the charged particle source 201, and a plurality of charged particle beams emitted from one drawing unit 11 constitute one charged particle beam group. However, the present invention is not limited to this. For example, a plurality of charged particle beam groups may be defined for a plurality of charged particle beams emitted from one drawing unit 11. In this case, the drawing unit 11 can include the deflectors (main deflector 213 and sub-deflector 215) in correspondence with each of the plurality of charged particle beam groups. In this case, the drawing apparatus 100 may be configured to include only one drawing unit 11.
The second embodiment will explain a method of controlling each of a plurality of charged particle beams included in each charged particle beam group when a shot region 24 formed on a substrate 1 contains a rotation component.
First, a step of performing drawing in the shot region 24e containing no deformation component will be explained with reference to
D(bn)=(ts—n, Lx—n, tstart—n, tfinish
The deflection start time ts_n represents the time when deflection by the deflectors starts. The deflection distance Lx represents the distance in the X direction by which a charged particle beam is scanned on the substrate. The irradiation start time tstart
Since the charged particle beams b1 to b5 are changed at once by the deflectors, the deflection start times ts_n of the charged particle beams b1 to b5 are the same (ts_n=t). Since the length of the line 31 is 5e, the deflection distance Lx_n for each charged particle beam is e. Since the shot region 24e does not contain a rotation component, as described above, the line 31 is not inclined. For this reason, the irradiation start times tstart
D(b1)=(t, e, tst, tfn)
D(b2)=(t, e, tst, tfn)
D(b3)=(t, e, tst, tfn)
D(b4)=(t, e, tst, tfn)
D(b5)=(t, e, tst, tfn) (6)
Next, a step of performing drawing in the shot region 24f containing a rotation component will be explained with reference to
D(b6)=(t, e, tst, tfn)
D(b7)=(t+ΔT, e, tst, tfn)
D(b8)=(t+2×ΔT, e, tst, tfn)
D(b9)=(t+3×ΔT, e, tst, tfn)
D(b10)=(t+4×ΔT, e, tst, tfn) (7)
Since the line 32 is inclined by the angle θ3, the deflection start times ts_n of the charged particle beams b6 to b10 are different, and a delay time ΔT is generated between two adjacent charged particle beams. Letting V be the moving speed of the substrate stage 20, ΔL in 81 of
As described above, when the line 32 to be drawn is inclined, control data for controlling the charged particle beams b6 to b10 are generated so that the deflection start time shifts between two adjacent charged particle beams in accordance with the inclination of the line 32. By controlling the blanker array 207 and deflectors based on the control data, the main control unit 226 can perform drawing at high precision in a shot region containing a rotation component.
In the second embodiment, the charged particle beams b6 to b10 have the same irradiation start time and the same irradiation finish time with respect to the deflection start time on the assumption that a pattern is drawn on the entire line 32. However, the present invention is not limited to this. For example, a pattern to be drawn may be scattered on the line 32. In this case, the irradiation start time and irradiation finish time with respect to the deflection start time may be different between the charged particle beams b6 to b10. In the second embodiment, control data is generated to contain the deflection start time, deflection distance, irradiation start time, and irradiation finish time. However, the present invention is not limited to this. For example, when all charged particle beams are deflected at once, control data may be generated to contain the coordinates (gx, gy) of a pattern to be drawn on a substrate, and the ON/OFF control timings ton and toff of the blanker array 207:
D(bn)=(gxn, gyn, tonn, toff n) (9)
The third embodiment will explain a method of controlling each of a plurality of charged particle beams included in each charged particle beam group when a shot region 24 formed on a substrate 1 contains a magnification component, that is, when the shot region 24 exists on the substrate at a magnification.
In this manner, when the shot region 24 contains a magnification component, and the line 37 to be drawn is expanded or contracted, the range where drawing is performed with each charged particle beam is changed in accordance with the shape of the shot region 24, and control data for controlling each charged particle beam is generated based on the changed range. By controlling a blanker array 207 and deflectors (main deflector 213 and sub-deflector 215) based on the control data, the main control unit 226 can perform drawing at high precision in the shot region 24 containing a magnification component.
The fourth embodiment will explain a case in which the reference position of each charged particle beam group shifts from a target position owing to, for example, a temporal change of a member used in a drawing unit 11.
In this way, when a position shift is generated in each charged particle beam group, the deflectors are controlled to correct the position shift, in addition to adjustment complying with the shape of the shot region 24 in each charged particle beam group. Even when the irradiation position of the charged particle beam group on the substrate 1 shifts, a pattern can be drawn at high precision in the shot region 24 formed on the substrate 1.
A method of manufacturing an article according to the embodiment of the present invention is suitable for manufacturing an article such as a microdevice (for example, a semiconductor device) or an element having a microstructure. The method of manufacturing an article according to the embodiment includes a step of forming, by using the above-described drawing apparatus, a latent image pattern on a photosensitive agent applied to a substrate (a step of performing drawing on a substrate), and a step of developing the substrate on which the latent image pattern has been formed in the preceding step. Further, this manufacturing method includes other well-known steps (for example, oxidization, deposition, vapor deposition, doping, planarization, etching, resist removal, dicing, bonding, and packaging). The method of manufacturing an article according to the embodiment is superior to a conventional method in at least one of the performance, quality, productivity, and production cost of the article.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2013-167842 filed on Aug. 12, 2013, which is hereby incorporated by reference herein in its entirety.
Number | Date | Country | Kind |
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2013-167842 | Aug 2013 | JP | national |