JP7106297B2 - Variable shaped charged particle beam irradiation device and variable shaped charged particle beam irradiation method - Google Patents

Description

The present invention relates to a variable-shaped charged particle beam irradiation apparatus and a variable-shaped charged particle beam irradiation method, and for example, to an electron beam writing apparatus or an electron beam inspection apparatus that irradiates a specimen with an electron beam that is variably shaped.

2. Description of the Related Art In recent years, as LSIs have become more highly integrated, circuit line widths of semiconductor devices have become even finer. Electron beam (EB) drawing technology with excellent resolution is used as a method of forming an exposure mask (also referred to as a reticle) for forming circuit patterns on these semiconductor devices.

FIG. 13 is a conceptual diagram for explaining the operation of the variable shaping electron beam lithography apparatus. The variable shaping electron beam lithography apparatus operates as follows. A rectangular opening 411 for shaping the electron beam 330 is formed in the first shaping aperture substrate 410 . A variable shaping aperture 421 is formed in the second shaping aperture substrate 420 to shape the electron beam 330 passing through the aperture 411 of the first shaping aperture substrate 410 into a desired rectangular shape. The electron beam 330 emitted from the charged particle source 430 and passed through the opening 411 of the first shaping aperture substrate 410 is deflected by the deflector and passes through a part of the variable shaping aperture 421 of the second shaping aperture substrate 420. Then, the sample 340 mounted on a stage that moves continuously or intermittently in one predetermined direction (for example, the X direction) is irradiated. That is, a rectangular shape that can pass through both the opening 411 of the first shaping aperture substrate 410 and the variable shaping opening 421 of the second shaping aperture substrate 420 is mounted on a stage that moves continuously or intermittently in the X direction. It is drawn in the drawing area of the sample 340 that has been drawn. A method of forming an arbitrary shape by passing through both the opening 411 of the first shaping aperture substrate 410 and the variable shaping opening 421 of the second shaping aperture substrate 420 is called a variable shaping method (VSB method).

Here, with the recent miniaturization of patterns, further improvement in the resolution of the shape of the shaped beam that irradiates the sample is required in the VSB system drawing apparatus. In order to improve the resolution of the optical system of the drawing apparatus of the VSB system, it is necessary to reduce aberration such as spherical aberration. For example, in a scanning electron microscope (SEM), use of an aberration corrector for correcting spherical aberration of an electron beam has been studied (see, for example, Patent Document 1). However, if an optical system that corrects spherical aberration is placed in the electron lens barrel, the optical path length from the beam forming position to the sample surface will become long, so that the so-called blur due to the Coulomb effect will increase, and the aberration correction will be difficult. There is a problem that not only the effect is not obtained, but also the resolution may be further lowered.

Such problems are not limited to electron beam writing of the VSB method. For example, in an inspection apparatus that picks up a secondary electron image and inspects a pattern, the same problem may occur with respect to the shape of the formed primary electron beam. .

JP 2004-303547 A

Accordingly, one aspect of the present invention provides an apparatus and method capable of improving the resolution of the shaped beam shape in VSB charged particle beam irradiation.

A variable-shaped charged particle beam irradiation apparatus according to one aspect of the present invention includes:
an emission source that emits a beam of charged particles;
a determination unit that determines, for each shot figure, whether the shot size of the shot figure is larger or smaller than the shot size of the branch point;
a first shaping aperture substrate in which an opening is formed, the entire opening is irradiated with a charged particle beam, and the charged particle beam is shaped to an opening size of the opening;
second and third shaping aperture substrates arranged switchably according to the size of the determined shot size, both of which variably shape the charged particle beam of the aperture size;
an aberration corrector disposed between the second shaping aperture substrate and the third shaping aperture substrate for correcting aberration of the passing charged particle beam;
a stage for arranging a substrate to be irradiated with a charged particle beam variably shaped by one of the second shaping aperture substrate and the third shaping aperture substrate;
characterized by comprising

Moreover, it is preferable to further include a deflection mechanism for switching between the second shaping aperture substrate and the third shaping aperture substrate used for variable shaping by deflecting the trajectory of the charged particle beam.

It is also preferred to further comprise a limiting aperture substrate positioned between the second shaping aperture substrate and the third shaping aperture substrate.

Further, it is preferable to further include an ammeter electrically connected to the final-stage shaping aperture substrate, out of the second shaping aperture substrate and the third shaping aperture substrate.

A variable shaped charged particle beam irradiation method according to one aspect of the present invention comprises:
irradiating the entire opening of a first shaping aperture substrate having an opening with a charged particle beam emitted from an emission source to shape the charged particle beam to the opening size of the opening;
a step of determining, for each shot figure, whether the shot size of the shot figure is larger or smaller than the shot size of the branch point;
variably shaping a charged particle beam having an aperture size using one of the second and third shaping aperture substrates switched according to the determined shot size;
correcting for aberrations in a passing charged particle beam using an aberration corrector positioned between the second shaping aperture substrate and the third shaping aperture substrate;
irradiating a substrate placed on a stage with a charged particle beam variably shaped by one of the second shaping aperture substrate and the third shaping aperture substrate;
characterized by comprising

According to one aspect of the present invention, it is possible to improve the resolution of the shape of a shaped beam in VSB charged particle beam irradiation.

1 is a conceptual diagram showing the configuration of a drawing apparatus according to Embodiment 1; FIG. 4 is a conceptual diagram for explaining each region in Embodiment 1. FIG. 4 is a diagram showing the relationship between resolution and shot size in Embodiment 1. FIG. 4 is a cross-sectional view for explaining the operation of the drawing mechanism according to Embodiment 1; FIG. FIG. 10 is a diagram showing an example of a third shaping aperture substrate having the same shape and size as the second shaping aperture substrate in Embodiment 1; 4 is a flow chart showing main steps of a drawing method according to Embodiment 1. FIG. FIG. 4 is a diagram for explaining an example of a beam profile of a threshold model of a resist applied to a sample according to Embodiment 1; 4A and 4B are diagrams showing an example of a pattern forming method according to Embodiment 1; FIG. FIG. 4 is a diagram showing part of the configuration of a modification of the first embodiment; FIG. 11 is a conceptual diagram showing the configuration of a drawing apparatus according to Embodiment 2; FIG. 12 is a conceptual diagram showing the configuration of a drawing apparatus according to Embodiment 3; FIG. 14 is a cross-sectional view for explaining the operation of the drawing mechanism in Embodiment 3; FIG. 3 is a conceptual diagram for explaining the operation of the variable shaping electron beam lithography apparatus;

In the following embodiments, a configuration using an electron beam as an example of a charged particle beam will be described. However, the charged particle beam is not limited to an electron beam, and may be a beam using charged particles such as an ion beam. Also, as an example of a charged particle beam irradiation apparatus, a variable shaping type drawing apparatus will be described.

Embodiment 1.
FIG. 1 is a conceptual diagram showing the configuration of a drawing apparatus according to Embodiment 1. FIG. In FIG. 1, the drawing apparatus 100 has a drawing mechanism 150 and a control system circuit 160 . The drawing apparatus 100 is an example of a charged particle beam drawing apparatus. In particular, it is an example of a variable shaping type (VSB type) drawing apparatus. The drawing mechanism 150 includes an electron lens barrel 102 and a drawing chamber 103 . Inside the electron lens barrel 102 (electron beam column) are an electron gun 201, an electron lens 218, an illumination lens 202, a blanking deflector 219, a first shaping aperture substrate 203, a projection lens 204, a shaping deflector 205, a second A shaping aperture substrate 206, an aberration corrector 210, a third shaping aperture substrate 211, an objective lens 207, a main deflector 208, a sub-deflector 209, and a third deflector 2091 are arranged. Further, in the electron lens barrel 102, a drive mechanism 230 for moving the shaping aperture of the second shaping aperture substrate 206 into and out of the electron trajectory, and a driving mechanism 230 for moving the shaping aperture of the third shaping aperture substrate 211 into the electron trajectory. A drive mechanism 232 is arranged to move the electrons in and out of the trajectory. The driving mechanism 230 and the driving mechanism 232 may drive the second shaping aperture substrate 206 or the third shaping aperture substrate 211 from outside the electron lens barrel 102 . An XY stage 105 is arranged in the writing chamber 103 . On the XY stage 105, a sample 101 such as a mask to be written is placed. The sample 101 includes an exposure mask for manufacturing a semiconductor device. The sample 101 also includes mask blanks coated with a resist and on which nothing has been drawn yet. A blanking deflector 219, for example a bipolar electrode group, is used. As the shaping deflector 205, for example, a 4-pole or 8-pole electrode group is used. As the main deflector 208, sub-deflector 209, and third deflector 2091, for example, an 8-pole electrode group is used.

Aberration corrector 210 is positioned between second shaping aperture substrate 206 and third shaping aperture substrate 211 . The aberration corrector 210 is configured by a combination of an input multipole lens 214 and an output multipole lens 224 . For example, it is configured by a combination of a hexapole entrance multipole lens 214 and a hexapole exit multipole lens 224 . Alternatively, for example, it is configured by a combination of a quadrupole input multipole lens 214 and an octupole output multipole lens 224 . The combination may be appropriately set according to the aberration to be corrected, such as spherical aberration and chromatic aberration. Also, an incident collimator lens 212 is arranged on the input side of the incident multipole lens 214 and makes a parallel beam incident on the incident multipole lens 214 . An input transfer lens 216 is arranged on the output side of the input multipole lens 214 . An output collimator lens 222 is arranged on the input side of the output multipole lens 224 to make a parallel beam incident on the output multipole lens 224 . An output transfer lens 226 is arranged on the output side of the output multipole lens 224 .

The control system circuit 160 has a control computer 110, a memory 112, a control circuit 120, and storage devices 140 and 142 such as magnetic disk devices. A memory 112, a control circuit 120, and storage devices 140 and 142 are connected to a control computer 110 that controls the entire drawing apparatus 100 via a bus (not shown).

A shot data generation unit 70 , a shot size determination unit 72 , an aperture setting unit 74 , a determination unit 76 and a drawing control unit 78 are arranged in the control computer 110 . Each of the shot data generation unit 70, shot size determination unit 72, aperture setting unit 74, determination unit 76, and drawing control unit 78 includes a processing circuit, and the processing circuit includes an electric circuit, a computer, Processors, circuit boards, quantum circuits, or semiconductor devices are included. Also, each of the "-units" may use a common processing circuit (same processing circuit). Alternatively, different processing circuits (separate processing circuits) may be used. Required input data or calculation results in the shot data generator 70, the shot size determination unit 72, the aperture setting unit 74, the determination unit 76, and the drawing control unit 78 are stored in the memory 112 each time.

In the control circuit 120, an aperture determining section 60 and a switching section 62 are arranged in addition to a control circuit for controlling and driving each component of the drawing mechanism 150 (not shown). Each "section" such as aperture determination section 60 and switching section 62 includes a processing circuit, such as an electrical circuit, computer, processor, circuit board, quantum circuit, or semiconductor device. Also, each of the "-units" may use a common processing circuit (same processing circuit). Alternatively, different processing circuits (separate processing circuits) may be used. Input data necessary for the aperture determining section 60 and the switching section 62 or results of calculation are stored in a memory (not shown) each time.

Drawing data defining at least one graphic pattern to be drawn is input from the outside of the drawing apparatus 100 and stored in the storage device 140 . The drawing data defines a graphic code indicating the type of graphic pattern to be drawn, layout coordinates, dimensions, and the like. In addition, dose information may be defined within the same data. Alternatively, the dose information may be input as separate data.

Here, FIG. 1 shows a configuration suitable for explaining the first embodiment. The drawing apparatus 100 may have other configurations that are normally required. For example, for position deflection, a three-stage deflector 2081 consisting of a main deflector 208, a sub-deflector 209, and a third deflector 2091 is used. position deflection may be performed by a multi-stage deflector. Input devices such as a mouse and a keyboard, a monitor device, and the like may be connected to the rendering device 100 .

FIG. 2 is a conceptual diagram for explaining each area in the first embodiment. In FIG. 2, the drawing area 10 of the sample 101 is virtually divided into, for example, a plurality of strip-shaped stripe areas 20 in the y-direction, which are the y-direction deflection width of the main deflector 208 . Also, each stripe region 20 is virtually divided into a plurality of sub-fields (SF) 30 (small regions) having a deflection size of the sub-deflector 209, for example, in the x-direction. Furthermore, it is virtually divided into a plurality of fields (TD) 301 (microscopic areas) that are the deflectable size of the third deflector 2091 . Shot figures 52 , 54 and 56 are drawn at each shot position of each SF 301 .

An electron beam 200 emitted from an electron gun 201 (emission source) is focused by an electron lens 218, for example, at a central height position (an example of a predetermined position) within a blanking deflector 219, and a focal point (crossover: C.O.). Then, the beam is turned on/off by the blanking deflector 219 when passing through the blanking deflector 219 arranged behind the electron lens 218 with respect to the beam trajectory central axis direction (optical axis direction). is controlled. In other words, the blanking deflector 219 deflects the electron beam 200 when performing blanking control to switch between beam ON and beam OFF. The electron beam deflected to the beam-off state by the first shaping aperture substrate 203 (also serving as the blanking aperture substrate) disposed behind the blanking deflector 219 with respect to the optical axis direction is shielded. That is, in the beam ON state, part of the electron beam 200 is controlled to pass through the first shaping aperture substrate 203 which also serves as the blanking aperture substrate, and in the beam OFF state, the entire beam passes through the first shaping aperture substrate. It is deflected so that it is shielded by the substrate 203 . The electron beam 200 passing through the first shaping aperture substrate 203 from the beam-OFF state to the beam-ON state and then to the beam-OFF state constitutes one electron beam shot. The blanking deflector 219 controls how the passing electron beam 200 travels to alternately produce a beam ON state and a beam OFF state. For example, a voltage of 0 V is applied (or no voltage is applied) when the beam is ON, and a voltage of several V is applied to the blanking deflector 219 when the beam is OFF. The dose per shot of the electron beam 200 with which the sample 101 is irradiated is adjusted at the irradiation time t of each shot.

The electron beam 200 that has passed through the blanking deflector 219 in the beam ON state illuminates the entire rectangular hole (first shaping aperture) formed in the first shaping aperture substrate 203 by the illumination lens 202 . Here, the electron beam 200 is first shaped into a rectangle of the aperture size of the aperture. Then, the electron beam 200 of the first aperture image that has passed through the first shaping aperture substrate 203 is changed in beam shape and size by the second shaping aperture substrate 206 or the third shaping aperture substrate 211 (variable shaping). ). Such variable shaping is performed on a shot-by-shot basis, and is usually shaped to a different beam shape and size for each shot. In other words, the second aperture image is formed by passing the electron beam 200 of the first aperture image through the second shaping aperture substrate 206 (or the third shaping aperture substrate 211). Then, the second aperture image electron beam 200 that has passed through the second shaping aperture substrate 206 (or the third shaping aperture substrate 211) is focused (imaged) on the sample 101 by the objective lens 207, The light is deflected by the main deflector 208, the sub-deflector 209, and the third deflector 2091, and is irradiated onto a desired position on the sample 101 placed on the XY stage 105 that moves continuously or intermittently. FIG. 1 shows a case where three-stage deflection is used for position deflection. In such a case, the main deflector 208 deflects the electron beam 200 of the corresponding shot to the reference position of the SF 30 while following the stage movement, and the sub-deflector 209 and the third deflector 2091 deflect each irradiation position in the TD. The beam of the corresponding shot should be deflected. By repeating this operation and connecting the shot figures of each shot, the figure pattern defined in the drawing data is drawn.

Here, in the conventional VSB type drawing apparatus, since the aberration corrector 210 and the third shaping aperture substrate 211 are not arranged, the electron beam 200 of the first aperture image is projected onto the second shaping aperture substrate 206. It was variably molded by Then, the surface of the sample 101 was irradiated with the electron beam 200 of the second aperture image. In order to improve the resolution of the beam irradiated onto the surface of the sample 101 in the optical system of the VSB drawing apparatus, it is necessary to reduce aberration such as spherical aberration. As shown in FIG. 1, by arranging the aberration corrector 210 downstream of the second shaping aperture substrate 206, the aberration of the second aperture image, which is the final beam shape, can be reduced. However, when the aberration corrector 210 is arranged, the optical path length L from the height position of the second shaping aperture substrate 206, which is the final beam shaping position, to the surface of the sample 101 becomes long. increases.

FIG. 3 is a diagram showing the relationship between resolution and shot size according to the first embodiment. In FIG. 3, the vertical axis represents the resolution of the beam shape (second aperture image) irradiated onto the sample 101 surface, and the horizontal axis represents the shot size of the beam irradiated onto the sample 101 surface. In FIG. 3 , an aberration corrector 210 is placed downstream of the second shaping aperture substrate 206 to correct the aberration of the second aperture image finally shaped by the second shaping aperture substrate 206 , and then the sample 101 surface is corrected. P is a graph of the relationship between resolution and shot size in the case of irradiation with . The optical path length L from the final shaping position of the beam to the surface of the sample 101 is shortened accordingly without arranging the aberration corrector 210 on the downstream side of the second shaping aperture substrate 206, and the final shaped second aperture image is obtained. Q represents a graph of the relationship between the resolution and the shot size when the surface of the sample 101 is irradiated with . In both relational graphs P and Q, as the shot size of the beam increases, the current amount of the beam increases. However, in the relational graph P, since the spherical aberration is corrected, the blur corresponding to the aberration can be reduced. As the size increases, the resolution deteriorates more sharply than in the relationship graph Q. Conversely, in the relationship graph Q, since the spherical aberration is not corrected for the third aperture image, the blur corresponding to the aberration remains without being reduced. Since L is short, the blur due to the Coulomb effect can be reduced, and the resolution deteriorates more moderately than in the relationship graph P as the shot size increases. Therefore, as shown in FIG. 3, when the shot size is small, the resolution is relatively improved by performing aberration correction even if the optical path length L is long. It can be seen that the resolution is relatively improved by shortening the optical path length L rather than correcting it. Also, it can be seen that there is a shot size Ls' that serves as a branching point.

Therefore, in Embodiment 1, there are cases 1 in which aberration correction is performed on the second aperture image even if the optical path length L is increased, and a case 1 in which aberration correction is not performed on the third aperture image and the optical path length L is increased. It is configured so that either Case 2, which is shortened, or Case 2, can be selected.

FIG. 4 is a cross-sectional view for explaining the operation of the drawing mechanism according to the first embodiment. FIG. 4A shows the configuration of case 1 in which aberration correction is performed even if the optical path length L is increased. In the example of FIG. 4A, the electron beam 200 of the first aperture image that has passed through the first shaping aperture substrate 203 is projected onto the second shaping aperture substrate 206 by the projection lens 204 . FIG. 5 is a diagram showing an example of a third shaping aperture substrate having the same shape and size as the second shaping aperture substrate in the first embodiment. The third shaping aperture substrate 211 is formed with, for example, a rectangular large aperture 43 and a beam shaping aperture 41 that is a combination of a rectangle and an octagon. The second shaping aperture substrate 206 and the third shaping aperture substrate 211 may have the same shape and size, but they may also differ. Deflection of the first aperture image on the second shaping aperture substrate 206 is controlled by the deflector 205, and the beam shape and size can be changed (variable shaping). Thus, final shaping of the beam irradiated onto the surface of the sample 101 is performed by the shaping apertures 40 of the second shaping aperture substrate 206 . Then, the electron beam 200 of the second aperture image that has passed through the second shaping aperture substrate 206 passes through the aberration corrector 210 and the spherical aberration is corrected. After passing through the aberration corrector 210, the electron beam 200 of the second aperture image passes through the large opening 43 of the third shaping aperture substrate 211, and is focused (imaged) on the sample 101 by the objective lens 207. ), the main deflector 208, the sub-deflector 209, and the third deflector 2091, and irradiate a desired position on the sample 101 placed on the XY stage 105 that moves continuously or intermittently. In the example of FIG. 4A, the optical path length L affecting the Coulomb effect is the optical path length L1 from the height position of the second shaping aperture substrate 206, which is the final beam shaping position A1, to the sample 101 surface.

On the other hand, FIG. 4B shows the configuration of case 2 in which the optical path length L is shortened without performing aberration correction on the third aperture image. In the example of FIG. 4(b), the electron beam 200 of the first aperture image that has passed through the first shaping aperture substrate 203 passes through the large aperture 42 of the second shaping aperture substrate 206 by the projection lens 204, and is aberration-corrected. Incident on corrector 210 . Although the electron beam 200 of the first aperture image is corrected for spherical aberration by the aberration corrector 210, the shape and size of the beam on the sample 101 are not determined because it is not in the final shaping stage. The electron beam 200 of the first aperture image that has passed through the aberration corrector 210 is projected onto the third shaping aperture substrate 211 . The deflection of the first aperture image on the third shaping aperture substrate 211 is controlled by the deflector 205, and the beam shape and size can be changed (variable shaping). Further, the deflection of the aperture image may be controlled by a deflector (not shown) installed between the third shaping aperture substrate 206 and the third shaping aperture substrate 211 (the same applies to the following embodiments). Therefore, the final shaping of the beam irradiated onto the surface of the sample 101 is performed by the shaping aperture 41 of the third shaping aperture substrate 211 . Then, the electron beam 200 of the second aperture image that has passed through the third shaping aperture substrate 211 is focused (imaged) on the sample 101 by the objective lens 207, and the main deflector 208, sub-deflector 209, and the third deflector 2091 to irradiate a desired position on the sample 101 placed on the XY stage 105 that moves continuously or intermittently. In the example of FIG. 4B, the optical path length L affecting the Coulomb effect is the optical path length L2 from the height position of the third shaping aperture substrate 211, which is the final beam shaping position A2, to the sample 101 surface.

In order to carry out Cases 1 and 2 described above, it is necessary to switch between the final shaping by the second shaping aperture substrate 206 and the final shaping by the third shaping aperture substrate 211 . Therefore, in Embodiment 1, the driving mechanism 230 mechanically moves the second shaping aperture substrate 206 in a direction perpendicular to the beam trajectory center axis direction (optical axis). In such a case, it is preferable to form two openings in the second shaping aperture substrate 206, namely, the beam shaping aperture 40 and the large aperture 42 which is sufficiently larger than the beam shaping aperture and allows all the beams to pass through. When the second shaping aperture substrate 206 is moved out of the electron trajectory by forming two openings, it is moved so that the large aperture 42 is positioned within the electron trajectory, and the second shaping aperture substrate 206 is moved. When moving 206 into the electron trajectory, it is also preferable to move it so that the beam shaping aperture 40 is located within the electron trajectory. With such a configuration, the amount of movement of the second shaping aperture substrate 206 can be made smaller than when the entire second shaping aperture substrate 206 is moved to the outside of the electron trajectory. However, the present invention is not limited to this, and the entire second shaping aperture substrate 206 may be moved to the outside of the electron trajectory.

Similarly, the drive mechanism 232 mechanically moves the third shaping aperture substrate 211 in a direction orthogonal to the beam trajectory central axis direction (optical axis). In such a case, it is preferable to form two openings in the third shaping aperture substrate 211, namely, a beam shaping aperture and a large aperture 43 which is sufficiently larger than the beam shaping aperture 41 and allows all the beams to pass through. By forming two openings, when the third shaping aperture substrate 211 is moved out of the electron trajectory, it is moved so that the large aperture 43 is positioned within the electron trajectory, and the third shaping aperture substrate When moving 211 into the electron trajectory, it is also suitable to move so that the beam shaping aperture 41 is positioned within the electron trajectory. With such a configuration, the amount of movement of the third shaping aperture substrate 211 can be made smaller than when the entire third shaping aperture substrate 211 is moved to the outside of the electron trajectory. However, the present invention is not limited to this, and the entire third shaping aperture substrate 211 may be moved to the outside of the electron trajectory.

As described above, in Case 1 where aberration correction is performed even if the optical path length L is increased, the second shaping aperture substrate 206 (beam shaping aperture) is moved into the electron trajectory, and the third shaping aperture substrate 211 ( beam shaping aperture) out of the electron trajectory. In Case 2, in which the optical path length L is shortened without performing aberration correction, conversely, the second shaping aperture substrate 206 (beam shaping aperture) is moved out of the electron trajectory, and the third shaping aperture substrate 211 (beam shaping Aperture 41) is moved into the electron trajectory. In this way, the shaping aperture substrate for the final shaping is determined by a mechanical mechanism that changes or switches the positional relationship between the second shaping aperture substrate 206 and the third shaping aperture substrate 211 .

FIG. 6 is a flow chart showing main steps of the drawing method according to the first embodiment. 6, the drawing method according to the first embodiment includes a shot dividing step (S202), a shot size determining step (S204), an aperture setting step (S206), an aperture determining step (S208), and an aperture switching step ( S210), a drawing step (S220), and a determination step (S222) are performed.

In the shot data generation step (S202), the shot data generation unit 70 reads drawing data from the storage device 140, performs multiple stages of data processing, and generates shot data ( 1) is generated. There is a limit to the size and shape that can be formed with a single beam shot by the writing apparatus 100 . Therefore, one shot figure having a size and shape that can be shot for the figure pattern is generated. Alternatively, the figure pattern is divided into a plurality of shot figures of sizes and shapes that can be shot. Shot data (1) defines a figure code indicating the figure type of the shot figure, arrangement coordinates, dimensions, and the like. In addition, dose information may be defined within the same data. Alternatively, the dose information may be input as separate data. The generated shot data (1) is temporarily stored in the storage device 142 . It is preferable to perform such processing in units of stripe regions 20 . Also, the shot data generation unit 70 rearranges the shot data in the order of the shots.

As the shot size determination step (S204), the shot size determination unit 72 determines the shot size of each shot figure.

In the aperture setting step (S206), the aperture setting unit 74 sets a shaping aperture corresponding to the determined shot size for each shot figure. Specifically, as shown in FIG. 3, when the shot size is smaller than the shot size Ls′ at the branch point, even if the optical path length L is long, the resolution is relatively low if the aberration correction is performed. substantially improve. Conversely, when the shot size is larger than the shot size Ls', shortening the optical path length L relatively improves the resolution rather than performing aberration correction. In other words, when the shot size is smaller than the shot size Ls', final shaping of the electron beam of the shot figure by the second shaping aperture substrate 206 relatively improves the resolution. Conversely, when the shot size is larger than the shot size Ls', final shaping of the electron beam of the shot pattern by the third shaping aperture substrate 211 relatively improves the resolution. Therefore, the aperture setting unit 74 selects the second shaping aperture substrate 206 (S21) and the third shaping aperture substrate 211 as the second shaping aperture substrate 206 (S21) and the third shaping aperture substrate 211 for each shot figure, the resolution of which is relatively improved according to the determined shot size. (S22). Then, the aperture setting unit 74 defines an identifier indicating the selected one of the second shaping aperture substrate 206 and the third shaping aperture substrate 211 as additional data to the shot data of the shot figure. If the shot size of the shot figure matches the shot size Ls' at the branch point, it is necessary to determine in advance which of the second shaping aperture substrate 206 and the third shaping aperture substrate 211 is to be used. good. Shot data (2) in which the shaping aperture of one of the second shaping aperture substrate 206 and the third shaping aperture substrate 211 is defined (set) is stored in the storage device 142 . It is preferable to perform such processing in units of stripe regions 20 . By executing such processing for each stripe region 20, the drawing processing can be executed in order from the stripe region 20 for which the processing has been completed. In other words, it is possible to perform data processing and drawing operations in parallel.

In the aperture determination step (S208), the aperture determination unit 60 reads the shot data in the order of the shots, and determines whether the shaping aperture defined in the shot data is the second shaping aperture substrate 206 or the third shaping aperture substrate 211. Determine which one. It can be determined from the identifier defined in the shot data.

In the aperture switching step (S210), the switching unit 62 switches the shaping aperture to be used for final shaping to one of the determined second shaping aperture substrate 206 and third shaping aperture substrate 211. FIG. Specifically, the switching unit 62 controls the drive mechanism 230 and the drive mechanism 232 so that the shaping aperture of the determined shaping aperture is placed within the beam trajectory, and the shaping aperture that was not determined is positioned within the beam trajectory. The second shaping aperture substrate 206 and the third shaping aperture substrate 211 are moved so that they are arranged in positions where they do not interfere. Needless to say, there is no need to move if the previous shot is positioned so that final shaping can be done with the shaping aperture that has already been determined.

As the drawing step (S220), the drawing mechanism 150 is driven by the control circuit 120 under the control of the drawing control section 78. FIG. The writing mechanism 150 irradiates the sample 101 placed on the XY stage 105 with the electron beam 200 variably shaped by one of the second shaping aperture substrate 206 and the third shaping aperture substrate 211 for each shot. . As a result, a shot figure corresponding to the variably shaped electron beam 200 is drawn on the sample 101 . As described above, when set to the configuration of Case 1 (for beam shots in which the shot size of the shot figure is smaller than the shot size Ls'), the shaping aperture of the second shaping aperture substrate 206 effects the final shaping of the beam. After passing through the aberration corrector 210 and spherical aberration is corrected, the beam is irradiated to a desired position of the sample 101 without being cut by the third shaping aperture substrate 211 . Conversely, when the configuration of Case 2 is set (in the case of a beam shot in which the shot size of the shot figure is larger than the shot size Ls'), the final shaping of the beam is performed by the shaping aperture of the third shaping aperture substrate 211. , the spherical aberration of the second aperture image is not corrected, but the desired position of the sample 101 is irradiated with the beam blurring reduced (or not increased) due to the Coulomb effect.

As a determination step (S222), the determination unit 76 determines whether or not all shots have been completed. End when all shots are finished. If all shots have not been completed, the process returns to the aperture determination step (S208), and each step from the aperture determination step (S208) to the determination step (S222) is performed until all shots are completed.

FIG. 7 is a diagram for explaining an example of the beam profile of the threshold model of the resist applied to the sample 101 according to the first embodiment. When the beam resolution is low, as shown in FIG. 7A, in the beam profile (dose distribution), the rising angle near the resolution threshold Th becomes gentle and exceeds the resolution threshold Th (that is, exposure ) The resolution of the shot figure was lowered. On the other hand, according to the first embodiment, especially for a beam shot whose shot size is smaller than the shot size Ls′ at the branch point, the beam profile (dose distribution) as shown in FIG. The angle of rise near the image threshold value Th can be steepened, and the resolution of the shot figure can be increased. For a beam shot whose shot size is larger than the shot size Ls' at the branch point, if the optical path length L2 shown in FIG. If the optical path length L2 can be made shorter than the conventional one, the blur caused by the Coulomb effect can be reduced, and the resolution can be increased as shown in FIG. 7B.

8A and 8B are diagrams showing an example of a pattern forming method according to Embodiment 1. FIG. As described above, in Case 2, if the optical path length L2 shown in FIG. 4B is the same as the conventional one, the resolution is not particularly improved. However, as shown in FIG. 8, by arranging side by side shot figures 13 with a small shot size for which the resolution can be improved by Case 1 on the edge of a shot figure 11 with a large shot size, the pattern dimension can be changed depending on the distance between the shot figures 13. You can control it. Therefore, even if the optical path length L2 shown in FIG. 4(b) is the same as the conventional one, the edge is defined by the shot figure 13 as shown in FIG. 8, thereby improving the resolution of the formed figure pattern. be able to.

FIG. 9 is a diagram showing part of the configuration of a modification of the first embodiment. 9 is the same as FIG. 1 except that deflectors 240 and 242 are arranged instead of the drive mechanisms 230 and 232. In FIG. In the example of FIG. 9, illustration of the configuration on the upstream side of the beam trajectory from the projection lens 204 is omitted. In the modification of the first embodiment, the second shaping aperture substrate 206 and the third shaping aperture substrate 211 used for variable shaping are switched by a deflection mechanism that switches by deflecting the trajectory of the charged particle beam. Specifically, it operates as follows. Two apertures, a beam shaping aperture 40 and a large aperture 42 which is sufficiently larger than the beam shaping aperture 40 and allows all beams to pass through, are formed in the second shaping aperture substrate 206 . Similarly, the third shaping aperture substrate 211 is formed with two openings, a beam shaping aperture 41 and a large aperture 43 which is sufficiently larger than the beam shaping aperture 41 and allows all beams to pass through. The arrangement positions of the second shaping aperture substrate 206 and the third shaping aperture substrate 211 are fixed. However, the large aperture 43 of the third shaping aperture substrate 211 is positioned downstream of the beam trajectory of the beam shaping aperture 40 of the second shaping aperture substrate 206, and the beam trajectory of the large aperture 42 of the second shaping aperture substrate 206 is located. The beam shaping aperture 41 of the third shaping aperture substrate 211 is positioned downstream. Then, the electron beam 200 of the first aperture image that has passed through the first shaping aperture substrate 203 is projected onto the second shaping aperture substrate 206 by the projection lens 204, and is projected onto the second shaping aperture substrate 206 by the deflector 205. Deflection is controlled to be variably shaped on the substrate 206 .

Here, when the configuration of case 1 is set (in the case of a beam shot in which the shot size of the shot figure is smaller than the shot size Ls'), the deflectors 240 and 242 do not perform beam deflection. Alternatively, if the position of the beam shaping aperture 40 of the second shaping aperture substrate 206 is misaligned with the deflection by the deflector 205, the deflector 240 is used for final shaping at the beam shaping aperture of the second shaping aperture substrate 206. , and deflector 242 swings back the angle of the beam trajectory so that it becomes a parallel beam. An electromagnetic scheme with the electric field created by such deflectors 240, 242 guides the beam to the location of the beam shaping aperture of the second shaping aperture substrate 206 where the beam is finally shaped. Then, the first aperture image on the second shaping aperture substrate 206 is subjected to deflection control so that the beam shape and size can be changed (variable shaping). Then, the electron beam 200 of the second aperture image that has passed through the second shaping aperture substrate 206 passes through the aberration corrector 210 and the spherical aberration is corrected. After passing through the aberration corrector 210, the electron beam 200 of the second aperture image passes through the large opening 43 of the third shaping aperture substrate 211, and is focused (imaged) on the sample 101 by the objective lens 207. ), the main deflector 208, the sub-deflector 209, and the third deflector 2091, and irradiate a desired position on the sample 101 placed on the XY stage 105 that moves continuously or intermittently. Although the electromagnetic system using an electric field has been described above, the beam may be deflected by a magnetic field (electromagnetic system using a magnetic field).

Conversely, when the configuration of case 2 is set (for beam shots in which the shot size of the shot figure is larger than the shot size Ls'), the deflector 240 is positioned at the beam shaping aperture 41 of the third shaping aperture substrate 211. Deflect the beam so that the final shaping takes place and the deflector 242 swings back the angle of the beam trajectory for a parallel beam. The beam is guided to the position of the beam shaping aperture 41 of the third shaping aperture substrate 211 where the beam is finally shaped by the electromagnetic method by the electric field formed by the deflectors 240 and 242 . Then, the electron beam 200 of the first aperture image passes through the large aperture 42 of the second shaping aperture substrate 206, and the spherical aberration is corrected by the aberration corrector 210, but since it is not the final shaping stage, the beam shape is and dimensions are not determined. The electron beam 200 of the first aperture image that has passed through the aberration corrector 210 is projected onto the third shaping aperture substrate 211 . The first aperture image on the third shaping aperture substrate 211 is subjected to deflection control so that the beam shape and size can be changed (variable shaping). Then, the electron beam 200 of the second aperture image that has passed through the third shaping aperture substrate 211 is focused (imaged) on the sample 101 by the objective lens 207, and the main deflector 208, sub-deflector 209, and the third deflector 2091 to irradiate a desired position on the sample 101 placed on the XY stage 105 that moves continuously or intermittently.

As described above, according to Embodiment 1, the resolution of the shape of the shaped beam can be improved in VSB electron beam irradiation.

Embodiment 2.
In the first embodiment, the case where the case 2 with a large shot size is configured and the first aperture image is projected onto the third shaping aperture substrate 211 has been described. In Embodiment 2, a configuration capable of improving the resolution even when the optical path length L2 is the same as the conventional case in case 2 will be described.

FIG. 10 is a conceptual diagram showing the configuration of the drawing apparatus according to the second embodiment. FIG. 10 is the same as FIG. 1 except that a limiting aperture substrate 250 is additionally arranged between the second shaping aperture substrate 206 and the third shaping aperture substrate 211 . A limiting aperture substrate 250 is preferably placed at the focal point of the beam. In the example of FIG. 10, the electron beam is focused between the entrance transfer lens 216 and the exit collimator lens 222 in the aberration corrector 210, and it is preferable to arrange such a focusing position.

Also, the flow chart showing the main steps of the drawing method in the second embodiment is the same as FIG. Contents other than those described below are the same as those of the first embodiment.

In the example of FIG. 10, since the first aperture image passes through the aperture of the limiting aperture substrate 250, part of the skirt portion forming the beam blur of the first aperture image can be cut. In other words, the aperture of the limiting aperture substrate 250 is formed in a size that allows cutting at least part of the skirt portion of the beam of the first aperture image. With such a configuration, even when configuring the case 2 with a large shot size in which the first aperture image is projected onto the third shaping aperture substrate 211, before the first aperture image is projected onto the third shaping aperture substrate 211, A portion of the skirt portion (bokeh) of the beam of the first aperture image can be shielded. Therefore, in the case of variable shaping, the blurring of the side where the edge is not formed at the shaping opening end portion of the third shaping aperture substrate 211 can be reduced. Alternatively, it is also possible to form an edge on a side that is not edged at the shaping opening end of the third shaping aperture substrate 211 . By forming the edge with the limiting aperture substrate 250 arranged between the second shaping aperture substrate 206 and the third shaping aperture substrate 211, the optical path length can be made longer than in the case of forming the edge with the second shaping aperture substrate 206. It can be shortened, and blurring due to the Coulomb effect can be reduced compared to the case where the edge is formed by the second shaping aperture substrate 206 . Further, even in case 1 in which aberration correction is performed, part of the beam skirt (bokeh) of the second aperture image can be shielded.

As described above, according to the second embodiment, the resolution can be further improved as compared with the first embodiment. In particular, when the case 2 is configured, the resolution can be improved even if the optical path length L2 is the same as the conventional one.

Embodiment 3.
As described in Embodiments 1 and 2, even if the optical path length L is increased, performing aberration correction shortens the optical path length L rather than performing aberration correction with a shot size that relatively improves resolution. However, there exists a shot size Ls′ that is a branching point with the shot size at which the resolution is relatively improved. Accurate measurement of the shot size Ls', which is the branching point, is desirable for improving the resolution. Therefore, in the third embodiment, a configuration is described in which a shot size Ls′, which is a branch point, can be searched for without actually drawing it on an evaluation substrate or the like.

FIG. 11 is a conceptual diagram showing the configuration of the drawing apparatus according to the third embodiment.
FIG. 12 is a cross-sectional view for explaining the operation of the drawing mechanism according to the third embodiment. In FIG. 11, of the second shaping aperture substrate 206 and the third shaping aperture substrate 211, the point where the ammeter 252 is electrically connected to the third shaping aperture substrate 211 which is the final stage shaping aperture substrate; The XY stage 105 is the same as in FIG. 1 except that the mark 107 is arranged, the Faraday cup 108 is arranged on the XY stage 105, and the measuring section 79 is arranged in the control computer 110. be. 12 is the same as FIG. 4 except that the ammeter 252 is electrically connected to the third shaping aperture substrate 211, which is the final shaping aperture substrate, and the secondary electrons 300 are added. be.

Each of the shot data generation unit 70, shot size determination unit 72, aperture setting unit 74, determination unit 76, drawing control unit 78, and measurement unit 79 includes a processing circuit. Circuits, computers, processors, circuit boards, quantum circuits, or semiconductor devices are included. Also, each of the "-units" may use a common processing circuit (same processing circuit). Alternatively, different processing circuits (separate processing circuits) may be used. Input data required for the shot data generation unit 70, shot size determination unit 72, aperture setting unit 74, determination unit 76, drawing control unit 78, and measurement unit 79 or results of calculations are stored in the memory 112 each time. .

Also, the surface height position of the mark 107 is arranged at the same height position as the surface of the sample 101 so as to be adjustable. One terminal of the ammeter 252 is electrically connected to the third shaping aperture substrate 211 . The other terminal is grounded. Then, the XY stage 105 is moved to a position where the electron beam 200 can scan the mark 107 .

In the configuration of case 1 in which aberration correction is performed even if the optical path length L is lengthened, the electron beam 200 is deflected by the three-stage deflector 2081 while varying the shot size. scan above. An ammeter 252 measures the current of the secondary electrons 300 emitted from the mark 107 and the periphery of the mark by the irradiation of the electron beam 200 and colliding with the third shaping aperture substrate 211 . The output of ammeter 252 is input to measuring section 79 . The measurement unit 79 uses the current waveform measured by the ammeter 252 to obtain a mark image, which is a two-dimensional electron image. The beam resolution can be measured by measuring the size of the skirt portion (bokeh) of the current waveform of the mark image. Graph P in FIG. 3 can be measured by such measurement. Note that the current of reflected electrons may be measured instead of the secondary electrons.

Similarly, with the configuration of case 2 in which the optical path length L is shortened without performing aberration correction, the electron beam 200 is deflected by the three-stage deflector 2081 while making the shot size variable. to scan the mark 107 with . An ammeter 252 measures the current of the secondary electrons 300 emitted from the mark 107 and the periphery of the mark by the irradiation of the electron beam 200 and colliding with the third shaping aperture substrate 211 . The output of ammeter 252 is input to measuring section 79 . The measurement unit 79 uses the current waveform measured by the ammeter 252 to acquire the mark image. The beam resolution can be measured by measuring the size of the skirt portion (bokeh) of the current waveform of the mark image. Graph Q in FIG. 3 can be measured by such measurements.

By calculating the shot size at which the graph P and the graph Q intersect, the measurement unit 79 can calculate the shot size Ls' that is the branch point.

Alternatively, the electron beam 200 is deflected by the three-stage deflector 2081 while making the shot size variable under the configuration of case 1 in which aberration correction is performed even if the optical path length L is increased. The Faraday cup 108 may be scanned. Then, the current of the electron beam 200 incident on the Faraday cup 108 is measured by the Faraday cup 108 . The output of the Faraday cup 108 is input to the measuring section 79 . A measurement unit 79 uses the current waveform measured by the Faraday cup 108 to obtain a mark image. The beam resolution can be measured by measuring the size of the skirt portion (bokeh) of the current waveform of the mark image. Graph P in FIG. 3 can be measured by such measurement.

Similarly, with the configuration of case 2 in which the optical path length L is shortened without performing aberration correction, the electron beam 200 is deflected by the three-stage deflector 2081 while making the shot size variable. The Faraday cup 108 may be scanned with . Then, the current of the electron beam 200 incident on the Faraday cup 108 is measured by the Faraday cup 108 . The output of the Faraday cup 108 is input to the measuring section 79 . A measurement unit 79 uses the current waveform measured by the Faraday cup 108 to obtain a mark image. The beam resolution can be measured by measuring the size of the skirt portion (bokeh) of the current waveform of the mark image. Graph Q in FIG. 3 can be measured by such measurements.

By calculating the shot size at which the graph P and the graph Q intersect, the measurement unit 79 can calculate the shot size Ls' that is the branch point.

Alternatively, a position sensor (SSD) may be arranged on the XY stage 105 instead of the Faraday cup 108 . Then, similarly to the measurement with the Faraday cup 108, the position sensor (SSD) may measure the current amount of the beam for each shot size.

As described above, according to the third embodiment, it is possible to search for the shot size Ls', which is the branching point, without actually irradiating the evaluation substrate coated with the resist with the electron beam for drawing. For example, a shot size Ls', which is a branch point, can be measured while writing a certain chip pattern. For example, after writing the stripe region 20, before writing the next stripe region 20, it is possible to measure the shot size Ls', which is the branch point. Alternatively, the shot size Ls', which is the branch point, may be measured before or after the drawing process.

The embodiments have been described above with reference to specific examples. However, the invention is not limited to these specific examples. For example, in the above example, an identifier indicating one of the second shaping aperture substrate 206 and the third shaping aperture substrate 211 selected in the aperture setting step (S206) is added to the shot data of the shot figure as additional data. Although the case of definition has been described, the present invention is not limited to this. Even if it is not defined as additional data, the aperture may be switched by directly judging from the shot size at the time of drawing.

In addition, descriptions of parts that are not directly necessary for the explanation of the present invention, such as the device configuration and control method, are omitted, but the required device configuration and control method can be appropriately selected and used. For example, although the description of the configuration of the control unit that controls the drawing apparatus 100 has been omitted, it goes without saying that the required configuration of the control unit can be appropriately selected and used.

In addition, all variable-shaped charged particle beam irradiation apparatuses and variable-shaped charged particle beam irradiation methods that have the elements of the present invention and that can be appropriately modified by those skilled in the art are included in the scope of the present invention.

10 drawing areas 11, 13 shot figure 20 stripe area 30 SF
40, 41 molding openings 42, 43 large openings 52, 54, 56 shot figure 60 aperture determination unit 62 switching unit 70 shot data generation unit 72 shot size determination unit 74 aperture setting unit 76 determination unit 78 drawing control unit 79 measurement unit 100 drawing Apparatus 101, 340 Sample 102 Electron column 103 Drawing chamber 105 XY stage 110 Control computer 112 Memory 120 Control circuit 140, 142 Storage device 150 Drawing mechanism 160 Control system circuit 200 Electron beam 201 Electron gun 202 Illumination lens 203, 410 First Shaping aperture substrate 204 Projection lens 205 Deflectors 206, 420 Second shaping aperture substrate 207 Objective lens 208 Main deflector 209 Sub-deflector 210 Aberration corrector 214, 224 Multipole lens 212, 222 Collimator lens 216, 226 Transfer lens 218 Electron lens 219 Blanking deflectors 230, 232 Drive mechanisms 240, 242 Deflector 250 Limiting aperture substrate 330 Electron beam 411 Aperture 421 Variable shaping aperture 430 Charged particle source

Claims (6)

an emission source that emits a beam of charged particles;
a determination unit that determines, for each shot figure, whether the shot size of the shot figure is larger or smaller than the shot size of the branch point;
a first shaping aperture substrate having an opening formed therein, receiving irradiation of the charged particle beam over the entire opening, and shaping the charged particle beam to an opening size of the opening;
second and third shaping aperture substrates arranged switchably according to the size of the determined shot size, both of which variably shape the charged particle beam of the aperture size;
an aberration corrector disposed between the second shaping aperture substrate and the third shaping aperture substrate for correcting aberration of the passing charged particle beam;
a stage for arranging a substrate to be irradiated with a charged particle beam variably shaped by one of the second shaping aperture substrate and the third shaping aperture substrate;
A variable shaped charged particle beam irradiation device comprising: 2. The variable according to claim 1, further comprising a deflection mechanism for switching between said second shaping aperture substrate and said third shaping aperture substrate used for variable shaping by deflecting the trajectory of said charged particle beam. Shaped charged particle beam irradiation equipment. a mechanical mechanism for switching between the second shaping aperture substrate and the third shaping aperture substrate used for variable shaping by changing the positional relationship between the second shaping aperture substrate and the third shaping aperture substrate; 2. The variable-shaped charged particle beam irradiation apparatus according to claim 1, comprising: 4. The variable shaped charged particle beam irradiation apparatus according to claim 1, further comprising a limiting aperture substrate disposed between said second shaping aperture substrate and said third shaping aperture substrate. . 5. An ammeter electrically connected to the last-stage shaping aperture substrate of said second shaping aperture substrate and said third shaping aperture substrate, further comprising an ammeter. A variable-shaped charged particle beam irradiation apparatus as described. irradiating the entire opening of a first shaping aperture substrate having an opening with a charged particle beam emitted from an emission source to shape the charged particle beam to the opening size of the opening;
a step of determining, for each shot figure, whether the shot size of the shot figure is larger or smaller than the shot size of the branch point;
variably shaping the charged particle beam having the aperture size using one of the second and third shaping aperture substrates switched according to the determined shot size;
correcting aberrations of the passing charged particle beam using an aberration corrector disposed between the second shaping aperture substrate and the third shaping aperture substrate;
irradiating a substrate placed on a stage with a charged particle beam variably shaped by one of the second shaping aperture substrate and the third shaping aperture substrate;
A variable shaped charged particle beam irradiation method comprising:

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