JP2018148147A - Charged particle beam lithography method and charged particle beam lithography device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithography method capable of correcting positional deviation resultant from shot size change of a charged particle beam, without adding a lens for adjustment.SOLUTION: A charged particle beam lithography method includes a step (S102) of measuring the positional deviation amount of a beam dependent on the molding size at a specified irradiation surface height position while changing the molding size of a charged particle beam, a step (S106) of generating shot data, a step (S108) of calculating the positional deviation amount corresponding to the shot size defined in the shot data for each shot figure by using the information of the positional deviation amount of the charged particle beam dependent on the molding size, a step (S110) of correcting the shot position so as to correct the calculated positional deviation amount, and a step (S120) of plotting the shot figure at a corrected shot position on a specimen by using a charged particle beam subjected to variable molding to the shot size for each shot figure.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a charged particle beam drawing method and a charged particle beam drawing apparatus, and more particularly, to a method for correcting positional deviation of an electron beam in an electron beam drawing apparatus that irradiates a sample with an electron beam.

  In recent years, with the high integration of LSI, the circuit line width of a semiconductor device has been further miniaturized. As a method for forming an exposure mask (also referred to as a reticle) for forming a circuit pattern on these semiconductor devices, an electron beam (EB) drawing technique having excellent resolution is used.

  FIG. 14 is a conceptual diagram for explaining the operation of the variable shaped electron beam drawing apparatus. The variable shaping type electron beam drawing apparatus operates as follows. In the first aperture 410, a rectangular opening 411 for forming the electron beam 330 is formed. Further, the second aperture 420 is formed with a variable shaping opening 421 for shaping the electron beam 330 having passed through the opening 411 of the first aperture 410 into a desired rectangular shape. The electron beam 330 irradiated from the charged particle source 430 and passed through the opening 411 of the first aperture 410 is deflected by the deflector, passes through a part of the variable shaping opening 421 of the second aperture 420, and passes through a predetermined range. The sample 340 mounted on a stage that continuously moves in one direction (for example, the X direction) is irradiated. That is, the drawing area of the sample 340 mounted on the stage in which the rectangular shape that can pass through both the opening 411 of the first aperture 410 and the variable shaping opening 421 of the second aperture 420 is continuously moved in the X direction. Drawn on. A method of creating an arbitrary shape by passing both the opening 411 of the first aperture 410 and the variable shaping opening 421 of the second aperture 420 is referred to as a variable shaping method (VSB method).

  Here, in the electron beam drawing apparatus, the electron beam emitted from the electron gun is refracted by a plurality of electromagnetic lenses, and reaches the sample surface through a plurality of crossovers. At that time, excitation adjustment of a plurality of electromagnetic lenses is performed by using a beam having a predetermined shot size so that the position of the pattern irradiated on the sample surface does not shift. Specifically, for example, after an image is focused on the sample surface by an objective lens, a cross formed in the vicinity of the blanking deflector so that no positional deviation occurs even if a voltage variation of the blanking deflector occurs. The over height position is matched with the deflection fulcrum height of the blanking deflector (see, for example, Patent Document 1).

  Here, in the VSB electron beam drawing, the beam is variably shaped for each shot, so the beam size (shot size) is not constant. It has been found that if such a shot size is changed, a positional shift occurs. Such a positional deviation is likely to occur because the height position of the crossover formed in the vicinity of the shaping deflector is deviated from the deflection fulcrum of the shaping deflector. Ideally, by performing excitation adjustment of the plurality of electromagnetic lenses described above, each height position of the plurality of crossovers should be a designed height position. However, in actuality, there are cases where it deviates from the designed height position. If you try to solve the positional shift caused by the shot size change by adjusting the excitation of multiple electromagnetic lenses, the height position of the crossover formed near the blanking deflector and the height of the crossover formed near the objective lens Adjustment of other parameters such as the position will be lost. For this reason, it is difficult to solve all the positional deviations caused by the deviations in the height positions of the crossovers by excitation adjustment of a plurality of electromagnetic lenses. If a solution is to be made, it is necessary to add an adjustment lens.

JP 2014-138175 A

  Therefore, one embodiment of the present invention provides a drawing method and apparatus capable of correcting a positional shift caused by a change in shot size of a charged particle beam without adding an adjustment lens.

The charged particle beam drawing method of one embodiment of the present invention includes:
Measuring the amount of positional deviation of the charged particle beam depending on the molding size at a predetermined irradiation surface height position while varying the molding size for shaping the charged particle beam;
A shot that defines the shot position and shot size of each shot figure when the figure pattern is divided into multiple shot figures of a size that can be irradiated with charged particle beam shots using drawing data in which the figure pattern is defined Generating data; and
Using the information of the amount of positional deviation of the charged particle beam depending on the molding size, for each shot figure, calculating the amount of positional deviation according to the shot size defined in the shot data;
For each shot figure, correcting the shot position so as to correct the amount of displacement calculated according to the shot size;
For each shot figure, the charged particle beam is variably shaped to the shot size, and the shot figure is drawn at the corrected shot position on the sample using the variably shaped charged particle beam;
It is provided with.

  Further, when correcting the shot position, it is preferable to correct the shot data.

The method further includes a step of calculating a deflection amount for deflecting the charged particle beam according to the shot position defined in the shot data,
When correcting the shot position, it may be preferable to correct the calculated deflection amount.

A charged particle beam drawing apparatus according to one embodiment of the present invention includes:
A storage device for storing correlation information between a forming size for forming a charged particle beam and a displacement amount of the charged particle beam;
A shot that defines the shot position and shot size of each shot figure when the figure pattern is divided into multiple shot figures of a size that can be irradiated with charged particle beam shots using drawing data in which the figure pattern is defined A shot data generation unit for generating data;
Using the correlation information, for each shot figure, a displacement amount calculation unit that calculates a displacement amount corresponding to the shot size defined in the shot data,
For each shot figure, a correction unit that corrects the shot position so as to correct the positional deviation amount calculated according to the shot size;
A discharge source that emits a charged particle beam; first and second shaping aperture substrates that variably shape the charged particle beam; and a deflector that deflects the charged particle beam. A drawing mechanism that variably shapes the shot size and draws the shot figure at a corrected shot position on the sample using the variably shaped charged particle beam;
It is provided with.

  Further, the correction unit preferably corrects the shot data when correcting the shot position.

  According to one embodiment of the present invention, it is possible to correct a positional shift caused by a change in shot size of a charged particle beam without adding an adjustment lens.

1 is a conceptual diagram illustrating a configuration of a drawing apparatus according to Embodiment 1. FIG. FIG. 3 is a conceptual diagram for explaining each region in the first embodiment. 3 is a diagram illustrating an example of an outer diameter trajectory of a crossover electron beam in the first embodiment. FIG. It is a figure which shows an example of the irradiation position depending on shaping | molding size in case the crossover height position in Embodiment 1 turns into a design position. It is a figure which shows an example of the irradiation position depending on the shaping | molding size in case the crossover height position in Embodiment 1 shifts | deviates from a design position. FIG. 4 is a flowchart showing main steps of the drawing method according to Embodiment 1. 6 is a diagram showing an example of an evaluation pattern in Embodiment 1. FIG. 6 is a diagram illustrating an example of a relationship between a position error and a shot size in the first embodiment. FIG. FIG. 11 is a diagram for explaining a method for measuring a positional deviation amount depending on a shot size in a modification of the first embodiment. 6 is a graph showing a relationship between a shot size and a positional deviation amount coefficient in a modification of the first embodiment. 5 is a diagram illustrating an example of a positional deviation after correction in the first embodiment. FIG. 6 is a conceptual diagram illustrating a configuration of a drawing apparatus according to Embodiment 2. FIG. FIG. 10 is a flowchart showing main steps of a drawing method according to Embodiment 2. It is a conceptual diagram for demonstrating operation | movement of a variable shaping type | mold electron beam drawing apparatus.

  Hereinafter, in the embodiment, a configuration using an electron beam will be described as an example of a charged particle beam. However, the charged particle beam is not limited to an electron beam, and a beam using charged particles such as an ion beam may be used. Further, a variable shaping type drawing apparatus will be described as an example of a charged particle beam drawing apparatus. The charged particle beam drawing apparatus is not limited to the variable shaping die as long as the drawing size is changed.

Embodiment 1 FIG.
FIG. 1 is a conceptual diagram illustrating a configuration of a drawing apparatus according to the first embodiment. In FIG. 1, the drawing apparatus 100 includes 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 column 102 and a drawing chamber 103. In the electron column 102, an electron gun 201, an electromagnetic lens 211, a blanking deflector 212, an illumination lens 202 (electromagnetic lens), a first shaping aperture substrate 203, a projection lens 204, a shaping deflector 205, a second A shaping aperture substrate 206, an objective lens 207, a main deflector 208, a sub deflector 209, and a detector 210 are arranged. A stage 105 is disposed in the drawing chamber 103. On the stage 105, a sample 101 such as a mask to be drawn at the time of drawing is arranged. The sample 101 includes an exposure mask for manufacturing a semiconductor device. Further, the sample 101 includes mask blanks to which a resist is applied and nothing is drawn yet. A beam scanning mark 106 is disposed on the stage 105.

  The blanking deflector 212 is disposed between the electromagnetic lens 211 and the illumination lens 202 with respect to the optical axis direction. And the 1st shaping | molding aperture board | substrate 203 (molding aperture member) is arrange | positioned rather than the illumination lens 202 with respect to the optical axis direction. The shaping deflector 205 is disposed between the illumination lens 202 and the projection lens 204 with respect to the optical axis direction. The objective lens 207 is disposed behind the blanking deflector 212 and the shaping deflector 205 with respect to the optical axis direction.

  The control system circuit 160 includes a control computer 110, a memory 112, a lens control circuit 120, an amplifier 122, a deflection control circuit 130, DAC (digital / analog conversion) amplifiers 135, 136, 138, a stage drive mechanism 139, a magnetic disk device, and the like. Storage devices 140, 142, and 144. The control computer 110, the memory 112, the lens control circuit 120, the amplifier 122, the deflection control circuit 130, the stage drive mechanism 139, and the storage devices 140, 142, and 144 are connected by a bus (not shown).

  In the control computer 110, a size setting unit 50, a shot data generation unit 51, a positional deviation amount calculation unit 53, a coordinate correction unit 55, a drawing control unit 57, and a measurement unit 58 are arranged. Each “˜ unit” such as the size setting unit 50, the shot data generation unit 51, the positional deviation amount calculation unit 53, the coordinate correction unit 55, the drawing control unit 57, and the measurement unit 58 has a processing circuit. Such processing circuits include, for example, an electric circuit, a computer, a processor, a circuit board, a quantum circuit, or a semiconductor device. Each “˜unit” may use a common processing circuit (the same processing circuit), or may use different processing circuits (separate processing circuits). Information input / output to / from the size setting unit 50, shot data generation unit 51, misregistration amount calculation unit 53, coordinate correction unit 55, drawing control unit 57, and measurement unit 58 and information being calculated are stored in the memory 112 each time. Is done.

  A deflection amount calculation unit 132 is disposed in the deflection control circuit 130. The deflection amount calculation unit 132 includes a processing circuit. Such processing circuits include, for example, an electric circuit, a computer, a processor, a circuit board, a quantum circuit, or a semiconductor device. Information input / output to / from the deflection amount calculation unit 132 and information being calculated are stored in a memory (not shown) each time.

  Here, FIG. 1 shows a configuration necessary for explaining the first embodiment. The drawing apparatus 100 may normally have other necessary configurations. For example, the main deflector 208 and the sub-deflector 209, which are the main and sub two-stage multi-stage deflectors, are used for position deflection, but the position deflection is performed by one stage deflector or three or more stages of multi-stage deflectors. It may be the case. The drawing apparatus 100 may be connected to an input device such as a mouse and a keyboard, a monitor device, and the like.

  FIG. 2 is a conceptual diagram for explaining each region in the first embodiment. In FIG. 2, the drawing area 10 (chip area) of the sample 101 is virtually divided into a plurality of strip-shaped stripe areas 20 according to the size of the main deflector 208 that can be deflected in the Y direction. Each stripe region 20 is virtually divided into a plurality of subfields (SF) 30 (small regions) depending on the size by which the sub deflector 209 can be deflected. Then, shot figures 52, 54, and 56 are drawn at each shot position of each SF30.

  A digital signal for blanking control is output from the deflection control circuit 130 to a DAC amplifier (not shown). In the DAC amplifier for blanking control, the digital signal is converted into an analog signal, amplified, and then applied to the blanking deflector 212 as a deflection voltage. The electron beam 200 is deflected by the deflection voltage, and the irradiation time (irradiation amount) of each shot is controlled.

  A digital signal for shaping deflection control is output from the deflection control circuit 130 to the DAC amplifier 135. The shaping deflection control DAC amplifier 135 converts the digital signal into an analog signal, amplifies it, and applies it to the shaping deflector 205 as a deflection voltage. The electron beam 200 is deflected by such a deflection voltage, and the beam is variably shaped into a shot figure of a desired size.

  A digital signal for main deflection control is output from the deflection control circuit 130 to the DAC amplifier 138. The main deflection control DAC amplifier 138 converts the digital signal into an analog signal, amplifies it, and applies it to the main deflector 208 as a deflection voltage. The electron beam 200 is deflected by the deflection voltage, and the beam of each shot is deflected to the reference position of the target SF 30 which is virtually divided into a mesh shape.

  A digital signal for sub-deflection control is output from the deflection control circuit 130 to the DAC amplifier 136. The sub-deflection control DAC amplifier 136 converts the digital signal into an analog signal, amplifies it, and applies it to the sub-deflector 209 as a deflection voltage. The electron beam 200 is deflected by the deflection voltage, and the beam of each shot is deflected to each shot position in the target SF 30.

  In the drawing apparatus 100, drawing processing is performed for each stripe region 20 using a multistage deflector having a plurality of stages. Here, as an example, a two-stage deflector such as a main deflector 208 and a sub deflector 209 is used. While the stage 105 continuously moves in the −x direction, for example, the drawing is advanced in the x direction for the first stripe region 20. Then, after the drawing of the first stripe region 20 is finished, the drawing of the second stripe region 20 proceeds in the same manner or in the reverse direction. Thereafter, similarly, drawing of the third and subsequent stripe regions 20 proceeds. Then, the main deflector 208 sequentially deflects the electron beam 200 to the reference position of the SF 30 so as to follow the movement of the stage 105. Further, the sub deflector 209 deflects the electron beam 200 from the reference position of each SF 30 to each shot position of the beam irradiated into the SF 30. As described above, the main deflector 208 and the sub deflector 209 have deflection areas having different sizes. The SF 30 is a minimum deflection area among the deflection areas of the multi-stage deflector.

  FIG. 3 is a diagram showing an example of the outer diameter trajectory of the crossover electron beam in the first embodiment. In the electron gun 201, when a negative acceleration voltage is applied to a cathode (not shown) and a negative bias voltage is applied to a Wehnelt electrode (not shown), when the cathode is heated, electrons (electrons) are emitted from the cathode, The emitted electrons (electron group) form a convergence point (crossover: CO) 1. Then, it spreads after the crossover is formed (cathode crossover), and is accelerated by an acceleration voltage to become an electron beam and proceeds toward an anode electrode (not shown). Then, the electron beam passes through the opening provided in the anode electrode, and the electron beam 200 is emitted from the electron gun 201.

  The electron beam 200 emitted from the electron gun 201 (emission unit) is converged to, for example, a center height position (an example of a predetermined position) in the blanking deflector 212 by the electromagnetic lens 211, and a convergence point (crossover: C.O.) 2. Then, the electron beam 200 that has passed through the blanking deflector 212 disposed behind the electromagnetic lens 211 with respect to the optical axis direction is illuminated onto the first shaping aperture substrate 203 by the illumination lens 202. At this time, ideally, a convergence point (crossover: C.O.C.) is formed at the center height position (an example of a predetermined position) in the shaping deflector 205 on the rear stage side on the optical axis with respect to the first shaping aperture substrate 203. ) Focus the electron beam to form 3.

  Here, when passing through the blanking deflector 212, ON / OFF of the beam is controlled by the blanking deflector 212 which is controlled by a deflection signal from a DAC amplifier (not shown) for blanking. In other words, the blanking deflector 212 deflects the electron beam when performing blanking control for switching between beam ON and beam OFF. An electron beam deflected so as to be in a beam OFF state by a first shaping aperture substrate 203 (also serving as a blanking aperture substrate) disposed behind the blanking deflector 212 with respect to the optical axis direction is Shielded. In other words, in the beam ON state, the illumination lens 202 irradiates the entire beam including the entire shaping opening of the first shaping aperture substrate 203 having a rectangular hole. In other words, the electron beam 200 is refracted to illuminate a region including the entire opening of the first shaping aperture substrate 203. Then, the electron beam irradiated to the shaping opening is controlled so as to pass through the first shaping aperture substrate 203. On the other hand, in the beam OFF state, the entire beam is deflected so as to be shielded by the first shaping aperture substrate 203. The electron beam 200 that has passed through the first shaping aperture substrate 203 until the beam is turned off after the beam is turned off becomes one electron beam shot. The blanking deflector 212 controls the direction of the passing electron beam 200 to alternately generate a beam ON state and a beam OFF state. For example, a voltage of 0 V may be applied when the beam is on (or no voltage is applied), and a voltage of several volts may be applied to the blanking deflector 212 when the beam is off. The irradiation amount per shot of the electron beam 200 irradiated on the sample 101 is adjusted at the irradiation time t of each shot.

  Here, in the beam ON state, the electron beam 200 is first shaped into a rectangle by passing the first shaping aperture substrate 203 through a part of the electron beam 200.

  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 206 by the projection lens 204. At this time, ideally, a convergence point (crossover: C.O.) 4 at a height position (an example of a predetermined position) in the objective lens 207 on the rear stage side on the optical axis further than the second shaping aperture 206. The electron beam 200 is converged so as to form

  The shaping deflector 205 controls the deflection of the first aperture image on the second shaping aperture 206 and can change the beam shape and dimensions (variable shaping). Such variable shaping is performed for each shot, and is usually shaped into different beam shapes and dimensions for each shot. Then, the electron beam 200 of the second aperture image that has passed through the second shaping aperture 206 is focused on the sample surface by the objective lens 207, and is deflected by the main deflector 208 and the sub deflector 209, and continuously. The desired position of the sample 101 placed on the moving stage 105 is irradiated. FIG. 1 shows a case in which multi-stage deflection of main and sub two stages is used for position deflection. In such a case, the main deflector 208 deflects the electron beam 200 of the corresponding shot while following the stage movement to the reference position of the SF 30, and the sub deflector 209 deflects the beam of the corresponding shot applied to each irradiation position in the SF. do it. By repeating such an operation and connecting the shot figures of the respective shots, a figure pattern defined in the drawing data is drawn.

  As described above, in the electron beam optical system shown in the example of FIG. 1, the electron beam is irradiated onto the surface of the sample 101 while forming four crossovers 1 to 4. Here, in the first embodiment, first, excitation adjustment of a plurality of electromagnetic lenses (electromagnetic lens 211, illumination lens 202, projection lens 204, and objective lens 207) constituting the electron beam optical system shown in FIG. 1 is performed. . Each electromagnetic lens may be composed of a plurality of stages of lenses.

  First, the focus of the image of the electron beam 200 is adjusted to the height of the sample 101 surface. Focus adjustment is performed by exciting the objective lens 207. The excitation values of the electromagnetic lens 211, the illumination lens 202, and the projection lens 204 may be set as design values. The blanking deflector 212 is maintained at the beam ON voltage (there is no potential difference between the electrodes). The value of excitation of the objective lens 207 at this time is A. At the time of drawing, the stage 105 is moved in the Z direction by ΔZ so that the height of the surface of the sample 101 (drawing surface) and the surface of the fixed mark 106 coincide. For example, the height position of the surface of the sample 101 and the surface of the mark 106 may be measured by a Z sensor (not shown), and moved by the stage 105 so that the height position of the surface of the sample 101 matches the height position of the surface of the mark 106.

  Theoretically, in this state, the surface of the sample 101 and the height of the fixed mark 105 coincide with each other, so if the excitation of the objective lens 207 is A, the focus should be just on the surface of the sample 101. However, when drawing is performed by actually changing the excitation of the objective lens 207 and the drawn pattern is measured, the focus is not just when excitation = A, but just when variable excitation = A ′. Has been obtained experimentally.

  Therefore, when drawing the sample 101, a fixed value (A′−A) is added to the optimum objective lens adjustment value A obtained by the fixed mark 106. This (A'-A) is called a focus offset. It has been found from experimental results that the value of the focus offset is reproduced in the same manner if the material and thickness of the sample 101 are the same.

  Regarding the focus adjustment, first, the stage 105 is moved so that the position of the mark 106 is on the optical axis of the electron beam 200, and then the mark 106 is scanned using a beam having a predetermined shot size. Then, the secondary electrons including the mark 106 and the reflected electrons reflected from the periphery of the mark 106 generated by the irradiation of the electron beam 200 are detected by the detector 210, converted into digital data by the amplifier 122, and then output to the measurement unit 58. To do. The measuring unit 58 forms a mark image from the obtained data and measures the mark pattern dimension CD. This operation is repeated while changing the focus height variably, and the pattern dimension CD for each focus height is measured. The focus position may be adjusted to the inflection point at which the likelihood (Dose Latitude) is minimized. The likelihood may be defined as a parameter (coefficient) indicating the relationship between the pattern dimension CD (change) and the electron beam dose dose.

  Next, the height position of the crossover 4 is adjusted. A position where the height of the mark 106 is intentionally shifted from the focus position, the excitation of the objective lens 207 is adjusted so as to focus at the shifted height, and the pattern dimension CD of the mark image obtained at each focus height does not substantially change. The excitation values of the electromagnetic lens 211 and the illumination lens 202 are adjusted to (position where the change amount is within the threshold).

  Next, the height position of the crossover 2 is adjusted. In a state where no potential difference is generated between the electrodes constituting the blanking deflector 212 (beam ON), the above-described position deviation of the beam having the predetermined shot size does not occur. However, if the deflection voltage applied to the blanking deflector 212 fluctuates, a potential difference is generated between the electrodes, and beam deflection that does not occur until the beam is turned off occurs. In this case, if the height position of the crossover 2 coincides with the center height position of the blanking deflector 212, the position of the crossover 2 coincides with the deflection fulcrum where the blanking deflector 212 deflects the electron beam 200. Therefore, there is no change in the position of the crossovers 3 and 4 on the rear stage side. However, when the height position of the crossover 2 is deviated from the center height position of the blanking deflector 212, apparently the position of the crossover 2 is on the extension line between the beam trajectory after deflection and the deflection fulcrum. Become. Thus, since the position of the crossover 2 is shifted from the deflection fulcrum for deflecting the electron beam 200 by the blanking deflector 212, the position of the crossover 2 apparently changes in the horizontal direction from the optical axis. As a result, the positions of the crossovers 3 and 4 on the rear stage side are also displaced from the optical axis. Therefore, the irradiation position of the beam on the sample 101 is shifted. Therefore, a potential that does not reach the beam OFF is applied to the blanking deflector 212 to deflect the electron beam while the beam is on, and the mark 106 is scanned in this state. Then, a mark image is acquired by the measurement unit 58. Then, the excitation values of the electromagnetic lens 211 and the illumination lens 202 are readjusted so that the positional deviation of the mark image is eliminated (so that the positional deviation amount is equal to or less than the threshold). The beam deflection here may be performed using an alignment coil or the like in addition to the blanking deflector 212. Note that the position of the mark 106 may be obtained as a relative position from the stage position. The position of the stage 105 may be measured by a laser length measuring device (not shown).

  Furthermore, the resolution of the electron beam depends on the electron optical system aberration, and the electron optical system aberration is proportional to the power of the convergence half angle. The convergence half angle α depends on the crossover diameter (radius: r) of the electron beam. For this reason, the excitation of the illumination lens 202 is adjusted so that the convergence half angle α can obtain a desired resolution.

  As described above, the height adjustment of the crossovers 2 and 4 and the adjustment of the convergence half angle α are performed. When such adjustment is completed, each component device is arranged so that the height position of the crossover 3 is ideally the center height position of the shaping deflector 205.

  FIG. 4 is a diagram illustrating an example of an irradiation position depending on the molding size when the crossover height position in the first embodiment is the design position. As shown in FIG. 4, when the height position of the crossover 3 is at the center height position (one-dot chain line) of the shaping deflector 205, the deflection fulcrum for deflecting the electron beam 200 by the shaping deflector 205 and the crossover 3. Therefore, even if the molding size is changed, there is no change in the position of the crossover 4 on the rear stage side. Therefore, there is no change in the reference position A of the irradiation pattern (shot figure) irradiated on the sample 101. The reference position A of the irradiation pattern (shot figure) is a point on the side of the opening of the second shaping aperture substrate 206 and is set at the corner of the shot figure.

  However, in practice, the height position of the crossover 3 may deviate from the center height position of the shaping deflector 205 due to a manufacturing defect or a poor positioning accuracy.

  FIG. 5 is a diagram illustrating an example of an irradiation position depending on a molding size when the crossover height position in the first embodiment deviates from the design position. In the example of FIG. 5, a case where the height position of the crossover 3 is at a position (−z direction) lower than the center height position (one-dot chain line) of the shaping deflector 205 is shown. When the electron beam 200 is deflected for beam shaping in this state, the position of the crossover 3 apparently becomes the position of the crossover 3 'on the extension line between the trajectory of the deflected beam and the deflection fulcrum. Thus, the position of the crossover 3 is shifted from the deflection fulcrum for deflecting the electron beam 200 by the shaping deflector 205, so that the position of the crossover 3 changes in the horizontal direction (x, y direction) from the optical axis. To do. As a result, the position of the crossover 4 on the rear stage side is also shifted from the optical axis to the position of the crossover 4 '. Therefore, the reference position A of the irradiation pattern (shot figure) irradiated onto the sample 101 is shifted to the position A ′.

  If it is attempted to solve the positional shift caused by the shot size change by the shaping deflector 205 by excitation adjustment of a plurality of electromagnetic lenses (electromagnetic lens 211, illumination lens 202, projection lens 204, and objective lens 207), crossovers 2 and 4 Adjustment of other parameters such as the height position and the convergence half angle α will be lost. For this reason, it is difficult to solve all the positional deviations caused by the deviations in the height positions of the crossovers by excitation adjustment of a plurality of electromagnetic lenses. If it is going to be solved, it is necessary to raise the degree of freedom of adjustment further than the present situation. For this purpose, it is necessary to add an adjustment lens. However, it is difficult to further secure these installation spaces in the electron column 102. Therefore, in the first embodiment, the positional deviation depending on the shot size is eliminated by correcting the deflection position.

  FIG. 6 is a flowchart showing main steps of the drawing method according to the first embodiment. In FIG. 6, the drawing method according to the first embodiment includes a positional deviation amount measurement step (S102) for each molding size, a correlation data creation step (S104), a shot data generation step (S106), and a positional deviation amount calculation step. A series of steps of (S108), a coordinate correction step (S110), a deflection amount calculation step (S112), and a drawing step (S120) are performed.

  As the positional deviation amount measuring step (S102) for each molding size, the positional deviation amount of the electron beam 200 depending on the molding size at a predetermined irradiation surface height position is measured while varying the molding size for molding the electron beam 200. .

  FIG. 7 is a diagram illustrating an example of an evaluation pattern in the first embodiment. In FIG. 7, an evaluation pattern 11 includes a reference rectangular pattern 12 formed by connecting a shot graphic 13 having a reference shot size at the center, and a shot graphic having a shot size variably formed so as to surround the reference rectangular pattern 12. 15 is formed by a combination with an outer frame pattern 14 formed by connecting 15. In the first embodiment, the evaluation substrate 300 coated with a resist is placed on the stage 105, and the shot size of the shot graphic 15 is made variable. draw. Specifically, it operates as follows.

  First, chip data (evaluation chip data) of the evaluation pattern 11 is input from the outside of the drawing apparatus 100 and stored in the storage device 140.

  The size setting unit 50 sets the reference shot size of the shot graphic 13 and the shot size of the shot graphic 15. For example, 250 nm is set as the reference shot size. In the example of FIG. 7, a 250 nm square rectangle is set as the reference shot figure 13. As the shot figure 15, one of a plurality of preset shot sizes, for example, 50 nm, 100 nm, 150 nm, 200 nm, and 250 nm is selected and set as the shot figure 15 shot size. Here, for example, 50 nm is set. Therefore, in the example of FIG. 7, a 50 nm square rectangle is set as the shot figure 15.

  The shot data generation unit 51 reads the chip data of the evaluation pattern 11 from the storage device 140 and divides the reference rectangular pattern 12 into a plurality of shot figures 13 having a size that can be irradiated with one shot of the electron beam 200. Similarly, the outer frame pattern 14 is divided into a plurality of shot figures 15 having a size that can be irradiated with one shot of the electron beam 200. Then, shot data is generated for each shot figure 13. Similarly, shot data is generated for each shot figure 15. In the shot data, a graphic code for identifying a graphic type, the coordinates of the reference position A, and a shot size are defined. The generated shot data is stored in the storage device 144.

  The deflection control circuit 130 reads shot data in the order of shots, and a deflection amount calculation unit 132 calculates a shaping deflection amount, a main deflection amount, a sub deflection amount, and the like.

  Then, under the control of the drawing control unit 57, the drawing mechanism 150 draws the evaluation pattern 11 on the evaluation substrate 300 coated with a resist. The evaluation pattern 11 is drawn by shifting the drawing area position on the evaluation substrate 300 for each shot size of the shot graphic 15 while changing the shot size of the shot graphic 15. In other words, the beam deflection amount of the shaping deflector 205 at the time of shot differs for each shot size of the shot graphic 15. Therefore, when the height position of the crossover 3 is not at the center height of the shaping deflector 205, the shift amount of the crossover 3 differs for each shot size of the shot graphic 15.

  After drawing, the evaluation substrate 300 is taken out of the drawing apparatus 100 and developed to form a resist pattern of the evaluation pattern 11 for each shot size of the shot graphic 15 on the evaluation substrate 300.

  Next, the edge positions V and W at both ends of the reference rectangular pattern 12 in the x direction are measured using a position measuring device. Similarly, edge positions V ′ and W ′ at both ends in the x direction of the frame portion of the outer frame pattern 14 are measured using a position measuring device. Although not shown in the figure, the same measurement may be performed in the y direction.

  Although the edge position of the resist pattern is measured here, the present invention is not limited to this. For example, a light shielding film may be formed below the resist, and the light shielding film may be etched using the resist pattern as a mask. Then, after removing the resist by ashing, using a position measuring device, the edge positions V and W at both ends of the reference rectangular pattern 12 formed as the light shielding film pattern and the edge positions V ′ at both ends of the outer frame pattern 14 are used. , W ′ may be measured.

  The width dimension of the reference rectangular pattern 12 and the width dimension of the frame portion of the outer frame pattern 14 are set to sizes that can be measured by the position measuring device. In other words, the measurement limit of the position measuring device, for example, a size of 0.3 μm or more is set. Furthermore, it is preferable that the width dimension of the reference rectangular pattern 12 is an integral multiple of the shot size of the shot figure 13. Similarly, the width dimension of the frame portion of the outer frame pattern 14 is preferably a common multiple of each shot size that is variably set. Thereby, the reference rectangular pattern 12 can be drawn only by the shot figure 13. Similarly, the outer frame pattern 14 can be drawn only by the shot figure 15.

  Then, the center positions of the edge positions V and W at both ends in the x direction of the reference rectangular pattern 12 are calculated for each shot size that is variably set. Similarly, the center positions of the edge positions V ′ and W ′ at both ends in the x direction of the frame portion of the outer frame pattern 14 are calculated.

  Next, for each shot size that is variably set, the coordinates of the center positions of the edge positions V and W at both ends in the x direction of the reference rectangular pattern 12 and the edge positions V ′ at both ends in the x direction of the frame portion of the outer frame pattern 14 are set. , W ′ is calculated with respect to the center position coordinates.

  Next, on the basis of the distance between the centers of the reference rectangular pattern 12 and the outer frame pattern 14 when the outer frame pattern 14 is drawn with the same 250 nm shot graphic 15 as the reference rectangular pattern 12, the shot graphic 15 of another shot size is used as a reference. The amount of deviation (difference value) from the center-to-center distance when the outer frame pattern 14 is drawn is calculated.

  The calculation until obtaining the difference value for each shot size that is variably set may be performed within the drawing apparatus 100 or may be performed offline (externally).

  In the correlation data creation step (S104), correlation data (correlation) between the molding size (shot size) and the amount of positional deviation of the electron beam is created.

  FIG. 8 is a diagram showing an example of the relationship between the position error and the shot size in the first embodiment. In FIG. 8, the vertical axis indicates the position error, and the horizontal axis indicates the shot size. In the example of FIG. 8, since the shot size of 250 nm is set as the reference shot size, the position error is zero at a shot size of 0.25 μm. On the other hand, when the shot size of the shot figure 15 is changed, it can be seen that a position error occurs as shown in FIG.

  Therefore, the approximate expression is obtained by fitting the position error amount in each shot size. In the example of FIG. 8, the approximation is linear, but the present invention is not limited to this. You may approximate with a polynomial. If the coefficient of the approximate expression is determined, correlation data (correlation) between the molding size and the amount of positional deviation of the electron beam is obtained. The obtained correlation data between the molding size and the amount of positional deviation of the electron beam is stored in the storage device 142. The correlation data is not limited to the approximate expression. You may create as a correlation table which defined the correspondence by the point sequence.

  The processing until the correlation data between the molding size and the amount of positional deviation of the electron beam is stored in the storage device 142 is performed as preprocessing before drawing. Next, actual drawing processing will be described. First, the sample 101 to be drawn is placed on the stage 105.

  As the shot data generation step (S106), the shot data generation unit 51 reads out the drawing data from the storage device 140, and uses the drawing data in which the figure pattern is defined, so that the figure pattern can be irradiated with an electron beam shot. Shot data in which a shot position and a shot size of each shot figure when divided into a plurality of shot figures is defined is generated. In the shot data of each shot figure, a figure code for identifying a figure type, coordinates of the reference position A, and shot size are defined. The generated shot data is stored in the storage device 144.

  As the misregistration amount calculation step (S108), the misregistration amount calculation unit 53 uses the information on the misregistration amount of the electron beam depending on the molding size to respond to the shot size defined in the shot data for each shot figure. Calculate the amount of misalignment. Specifically, the misregistration amount calculation unit 53 reads, for example, shot data from the storage device 144 in the drawing order, similarly reads correlation data from the storage device 142, and refers to the correlation data for each shot figure, The amount of positional deviation corresponding to the shot size defined in the shot data is calculated.

  As the coordinate correction step (S110), the coordinate correction unit 55 (correction unit) corrects the shot position so as to correct the positional deviation amount calculated according to the shot size for each shot figure. Specifically, the coordinates defined in the shot data are corrected so as to correct the positional deviation amount. The correction may be performed by defining the shot data by the amount of the positional deviation in the direction opposite to the direction of positional deviation and shifting the coordinates. For example, when the position is shifted by 20 nm in the x direction, −20 nm may be added as a correction value to the x coordinate. The corrected shot data is stored in the storage device 144 again. In the first embodiment, shot data is corrected when the shot position is corrected.

  As the deflection amount calculation step (S112), the deflection amount calculation unit 132 reads the corrected shot data from the storage device 144, and controls the deflection amount for forming deflection, the main deflection amount for position deflection, and the position deflection. The sub deflection amount is calculated. For example, the correction of the shift amount of the shot position depending on the molding size affects the sub deflection amount.

  As the drawing step (S120), the drawing mechanism 150 variably shapes the electron beam 200 to the shot size for each shot figure, and uses the variably shaped electron beam 200 to the corrected shot position on the sample 101. Then, the shot figure is drawn. The drawing operation is as described above.

  In the above-described example, the correlation data is created using the positional deviation amount obtained by actually drawing the evaluation pattern on the evaluation board 300, but the present invention is not limited to this.

  FIG. 9 is a diagram for explaining a method of measuring a positional deviation amount depending on the shot size in the modification of the first embodiment. In the modification of the first embodiment, measurement is performed using the mark 106 for the evaluation substrate 300. The stage 105 is moved so that the mark 106 is positioned on the optical axis. Then, the height of the mark 106 is intentionally shifted from the focus position. In the example of FIG. 9, it is shifted + z upward. If the height position of the crossover 3 is deviated from the center height position of the shaping deflector 205, as described above, the position of the crossover 3 is apparently an extension of the trajectory of the deflected beam and the deflection fulcrum. This is the position of the crossover 3 'on the line. As a result, the position of the crossover 4 on the rear stage side is also shifted from the optical axis to the position of the crossover 4 '. Therefore, the reference position A of the irradiation pattern (shot figure) irradiated onto the sample 101 is shifted to the position A ′. Here, when the height of the mark 106 is changed up and down, the irradiation position changes with the height of each mark 106. Therefore, a reference shot size is determined (for example, 250 nm), and a deviation amount ΔX ′ from the irradiation position of the reference size shot is measured from an image obtained by scanning the mark 106. Similarly, the shift amount ΔX ′ from the irradiation position of the reference-size shot is measured while changing the height of the mark 106 variably. Thereby, the deviation amount ΔX ′ from the irradiation position of the shot of the reference size for each irradiation height z can be measured.

FIG. 10 is a graph showing the relationship between the shot size and the positional deviation amount coefficient in the modification of the first embodiment. In FIG. 10, the vertical axis indicates the positional deviation amount coefficient k, and the horizontal axis indicates the irradiation height z. The positional deviation amount coefficient k can be defined by the following equation (1) using the deviation amount ΔX ′ from the irradiation position of the reference size shot and the size difference ΔS from the reference size shot.
(1) k = ΔX ′ / ΔS

Then, the positional deviation amount coefficient k for each irradiation height z is fitted with an approximate expression to obtain the graph of FIG. In the example of FIG. 10, it is linear proportional, but is not limited to this. It is preferable to approximate with a polynomial. Such samples 101 Mendaka of the approximate expression (focus height) is obtained by calculating the positional deviation amount coefficient k ₀ in z _0. Then, the obtained positional deviation amount coefficient k ₀ is stored in the storage device 142 as correlation data.

Then, in the modification of the first embodiment, the positional deviation amount calculating section 53, using the position deviation amount coefficient k _0, for each shot figure, calculates the position deviation amount corresponding to the shot size defined in the shot data To do. Specifically, the position deviation amount calculating unit 53 from the storage device 144 for example reads the shot data to the drawing order, similarly reads out the positional deviation amount coefficient k ₀ as the correlation data from the storage device 142, each shot figure, With reference to the correlation data, the amount of displacement according to the shot size defined in the shot data is calculated. The actual positional deviation amount ΔL can be defined by the following equation (2) using the reference shot size S ₀ and the target shot size S.
(2) ΔL = k ₀ · S−k ₀ · S ₀

  The process after the positional deviation amount corresponding to the shot size is obtained is the same as described above. In this way, correlation data may be acquired using the mark 106.

  FIG. 11 is a diagram illustrating an example of the positional deviation after correction in the first embodiment. In FIG. 11, the vertical axis indicates the position error, and the horizontal axis indicates the shot size. It can be seen that by performing the correction according to the first embodiment, as shown in FIG. 11, it is possible to eliminate or reduce the positional deviation caused by the shot size change of the electron beam 200.

  As described above, according to the first embodiment, it is possible to correct the positional deviation caused by the shot size change of the electron beam 200 without adding an adjustment lens.

Embodiment 2. FIG.
In the first embodiment, the case where the coordinates of the shot data itself are corrected has been described, but the present invention is not limited to this. In the second embodiment, another correction method will be described.

  FIG. 12 is a conceptual diagram illustrating a configuration of a drawing apparatus according to the second embodiment. In FIG. 12, the position deviation amount calculation unit 53 and the coordinate correction unit 55 are deleted from the control computer 110, and the position deviation amount calculation unit 133 and the deflection amount correction unit 134 are added to the deflection control circuit 130. Except for the point, it is the same as FIG. In the first embodiment, the correction is performed by the coordinate correction unit 55, but in the second embodiment, the correction is performed using the deflection amount correction unit 134.

  Accordingly, the size setting unit 50, the shot data generation unit 51, the drawing control unit 57, and the measurement unit 58 are arranged in the control computer 110. Each “˜unit” such as the size setting unit 50, the shot data generation unit 51, the drawing control unit 57, and the measurement unit 58 has a processing circuit. Such processing circuits include, for example, an electric circuit, a computer, a processor, a circuit board, a quantum circuit, or a semiconductor device. Each “˜unit” may use a common processing circuit (the same processing circuit), or may use different processing circuits (separate processing circuits). Information input to and output from the size setting unit 50, shot data generation unit 51, drawing control unit 57, and measurement unit 58 and information being calculated are stored in the memory 112 each time.

  In the deflection control circuit 130, a deflection amount calculation unit 132, a positional deviation amount calculation unit 133, and a deflection amount correction unit 134 are arranged. Each “˜ unit” such as the deflection amount calculation unit 132, the positional deviation amount calculation unit 133, and the deflection amount correction unit 134 has a processing circuit. Such processing circuits include, for example, an electric circuit, a computer, a processor, a circuit board, a quantum circuit, or a semiconductor device. Each “˜unit” may use a common processing circuit (the same processing circuit), or may use different processing circuits (separate processing circuits). Information input / output to / from the deflection amount calculation unit 132, the positional deviation amount calculation unit 133, and the deflection amount correction unit 134 and information being calculated are stored in a memory (not shown) each time.

  FIG. 13 is a flowchart showing main steps of the drawing method according to the second embodiment. In FIG. 13, the drawing method according to the second embodiment includes a positional deviation amount measuring step (S102) for each molding size, a correlation data creating step (S105), a shot data generating step (S106), and a deflection amount calculating step ( A series of steps of S113), a displacement amount calculation step (S115), a deflection amount correction step (S116), and a drawing step (S120) are performed. In the following, the contents other than those specifically described are the same as those in the first embodiment.

  The contents of the positional deviation amount measuring step (S102) for each molding size are the same as those in the first embodiment.

  In the correlation data creation step (S105), correlation data (correlation) between the molding size (shot size) and the amount of positional deviation of the electron beam is created. In the second embodiment, a deflection amount for position deflection corresponding to the displacement amount is used as the displacement amount of the electron beam. Specifically, the amount of deviation of sub deflection is used. Therefore, the correlation data is created as correlation data between the forming size and the deflection amount corresponding to the positional deviation amount of the electron beam. The correlation data may be defined by an approximate expression as shown in the first embodiment, or may be defined as a correlation table. The obtained correlation data is stored in the storage device 142.

  The contents of the shot data generation step (S106) are the same as those in the first embodiment.

  In the deflection amount calculation step (S113), the deflection amount calculation unit 132 reads shot data (uncorrected shot data in the second embodiment) from the storage device 144, and sets the size and shot position defined in the shot data. In response, a deflection amount for deflecting the electron beam is calculated. Specifically, the deflection amount for shaping deflection, the main deflection amount for position deflection, and the sub deflection amount for position deflection are calculated.

  As the positional deviation amount calculation step (S115), the positional deviation amount calculation unit 133 uses the information on the positional deviation amount of the electron beam depending on the molding size to respond to the shot size defined in the shot data for each shot figure. Calculate the amount of misalignment. Specifically, the misregistration amount calculation unit 133 reads shot data from the storage device 144, for example, in the drawing order, similarly reads correlation data from the storage device 142, and refers to the correlation data for each shot figure, A sub-deflection deviation amount (deflection deviation amount) corresponding to a positional deviation amount corresponding to the shot size defined in the shot data is calculated. The calculated sub deflection deviation amount (deflection deviation amount) is stored in a memory (not shown) in the deflection control circuit 130 each time.

  In the deflection amount correction step (S116), the deflection amount correction unit 134 corrects the shot position so as to correct the positional deviation amount calculated according to the shot size for each shot figure. Specifically, the deflection correction unit 134 reads out the sub-deflection deviation amount (deflection deviation amount) of the shot figure from a memory (not shown) in the deflection control circuit 130, and adds the sub-deflection deviation amount ( A sub-deflection correction amount that deflects the amount of deflection deviation) in the reverse direction may be added. As described above, in the second embodiment, when the shot position is corrected, the calculated deflection amount is corrected. By correcting the deflection amount, the positional deviation depending on the shot size can be eliminated as in the first embodiment.

  As the drawing step (S120), the drawing mechanism 150 variably shapes the electron beam 200 to the shot size for each shot figure, and uses the variably shaped electron beam 200 to the corrected shot position on the sample 101. Then, the shot figure is drawn. The drawing operation is the same as in the first embodiment.

  As described above, according to the second embodiment, the positional deviation caused by the change in the shot size of the electron beam 200 without adding an adjustment lens by using a method for correcting the deflection amount, not the shot data itself. Can be corrected.

  The embodiments have been described above with reference to specific examples. However, the present invention is not limited to these specific examples.

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

  In addition, all charged particle beam writing apparatuses and charged particle beam writing methods that include 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 area 20 Stripe area 30 SF
50 Size setting unit 51 Shot data generating unit 52, 54, 56 Shot figure 53, 133 Position shift amount calculating unit 55 Coordinate correcting unit 57 Drawing control unit 58 Measuring unit 100 Drawing apparatus 101, 340 Sample 102 Electronic lens barrel 103 Drawing chamber 105 Stage 106 Mark 110 Control computer 112 Memory 120 Lens control circuit 122 Amplifier 130 Deflection control circuit 132 Deflection amount calculation unit 134 Deflection amount correction unit 135, 136, 138 DAC amplifier 139 Stage drive mechanism 140, 142, 144 Storage device 150 Drawing mechanism 160 Control system circuit 200 Electron beam 201 Electron gun 202 Illumination lens 203 First shaping aperture substrate 204 Projection lens 205 Molding deflector 206 Second shaping aperture substrate 207 Objective lens 208 Main deflector 209 Sub deflector 210 Detector 2 First electromagnetic lens 212 blanking deflector 410 first aperture 411 opening 420 second aperture 421 variable-shaped opening 430 a charged particle source

Claims (5)

Measuring a positional deviation amount of the charged particle beam depending on the molding size at a predetermined irradiation surface height position while varying a molding size for shaping the charged particle beam;
Using the drawing data in which the figure pattern is defined, the shot position and the shot size of each shot figure when the figure pattern is divided into a plurality of shot figures that can be irradiated with the charged particle beam shot are defined. Generating the shot data
Using the information of the positional deviation amount of the charged particle beam depending on the molding size, for each shot figure, calculating a positional deviation amount according to the shot size defined in the shot data;
For each shot figure, correcting the shot position so as to correct the amount of displacement calculated according to the shot size;
For each shot figure, the charged particle beam is variably shaped to the shot size, and the shot figure is drawn at the corrected shot position on the sample using the variably shaped charged particle beam;
A charged particle beam drawing method comprising:   The charged particle beam drawing method according to claim 1, wherein the shot data is corrected when the shot position is corrected. A step of calculating a deflection amount for deflecting the charged particle beam according to a shot position defined in the shot data;
The charged particle beam drawing method according to claim 1, wherein when the shot position is corrected, the calculated deflection amount is corrected. A storage device for storing correlation information between a forming size for forming a charged particle beam and a positional deviation amount of the charged particle beam;
Using the drawing data in which the figure pattern is defined, the shot position and the shot size of each shot figure when the figure pattern is divided into a plurality of shot figures that can be irradiated with the charged particle beam shot are defined. A shot data generation unit for generating the shot data;
Using the correlation information, for each shot figure, a displacement amount calculation unit that calculates a displacement amount corresponding to the shot size defined in the shot data;
For each shot figure, a correction unit that corrects the shot position so as to correct the positional deviation amount calculated according to the shot size;
A discharge source that emits a charged particle beam; first and second shaping aperture substrates that variably shape the charged particle beam; and a deflector that deflects the charged particle beam; A drawing mechanism that variably shapes the beam to the shot size and draws the shot figure at a corrected shot position on the sample using the variably shaped charged particle beam;
A charged particle beam drawing apparatus comprising:   The charged particle beam drawing apparatus according to claim 4, wherein the correction unit corrects the shot data when correcting the shot position.

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