JP2010183004A - Charged particle beam drawing method and charged particle beam drawing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charged particle beam drawing device and a charged particle beam drawing method which can automatically adjust the current density distribution during drawing. <P>SOLUTION: In the charged particle beam drawing method, a charged particle beam is emitted from a charged particle gun; the charged particle beam is subjected to first shaping through a first aperture; the charged particle beam subjected to the first shaping is emitted to one of the edges of a second aperture with a predetermined area to conduct second shaping; the current value of the charged particle beam subjected to the second shaping is measured; displacement information on the center position of the charged particle beam is obtained from current values determined; by conducting the second shaping and the measurement of current values similarly on the multiple edges; and then alignment is adjusted, based on the displacement information. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a charged particle beam drawing method and a charged particle beam drawing apparatus used for forming a mask pattern, for example.

  In recent years, with the miniaturization of semiconductor devices, miniaturization of mask patterns such as LSIs has been required. A charged particle beam drawing apparatus having an excellent resolution is used for forming this fine mask pattern. In such a charged particle beam drawing apparatus, for example, a thermionic emission type electron gun using a cathode filament as a charged particle gun is used. In this case, electrons are emitted by heating the cathode with filament power using a thermionic emission electron gun. Then, the emitted electrons are focused by a bias voltage and accelerated by an acceleration voltage. Thus, an electron beam is formed, irradiated onto the sample through an optical system such as an aperture and a deflector, and a pattern is drawn at a predetermined current density (see, for example, Patent Document 1).

  In such an electron beam, fluctuations in the current density distribution contribute to deterioration of the drawing accuracy. Therefore, a method is usually employed in which the current density distribution is periodically measured, a warning is issued when the uniformity deteriorates, and correction is performed.

Japanese Patent Laid-Open No. 5-166481

  With further miniaturization of semiconductor devices, it is necessary to further suppress fluctuations in current density distribution. Alternatively, even when the distance of the optical system of the drawing apparatus is shortened, the variation in the irradiation distribution becomes a large variation in the current density distribution on the sample. In such a case, it is necessary to increase the adjustment frequency of the current density distribution. However, to measure the current density distribution, it is necessary to measure current values at a large number of points in a matrix through minute holes separately formed in the aperture while moving the irradiation position of the electron beam. Therefore, it is difficult to measure and adjust the current density distribution during drawing.

  Accordingly, the present invention provides a charged particle beam drawing method capable of performing drawing while automatically adjusting the current density distribution, and a charged particle beam drawing apparatus capable of automatically adjusting the current density distribution during drawing. With the goal.

  In the charged particle beam drawing method of one embodiment of the present invention, a charged particle beam is irradiated from a charged particle gun, the charged particle beam is subjected to a first shaping with a first aperture, and the charged particle beam subjected to the first shaping. The second shaping is performed by irradiating any one of the edges of the second aperture with a predetermined area, and the current value of the charged particle beam subjected to the second shaping is measured. The deviation information of the center position of the charged particle beam is obtained from each current value obtained by performing the shaping and the current value measurement similarly for a plurality of edges, and the alignment adjustment of the charged particle beam is performed based on the deviation information. It is characterized by performing.

  In the charged particle beam writing method of one embodiment of the present invention, it is preferable to perform alignment adjustment of the charged particle beam so that the current values are equal.

  In the charged particle beam drawing method of one embodiment of the present invention, in the second shaping, the charged particle beam is scanned in two axial directions, a current value corresponding to the scan position is measured, and each measured current value is measured. It is preferable to acquire deviation information from fluctuation. At this time, it is preferable to further calculate the alignment adjustment amount based on the deviation information.

  A charged particle beam drawing apparatus according to one embodiment of the present invention includes a charged particle gun that irradiates a charged particle beam, an aligner that performs alignment adjustment of the charged particle beam, a deflector that deflects the charged particle beam, and a charged particle beam. A first aperture that shapes the second particle, a second aperture that shapes the charged particle beam shaped by the first aperture, and the charged particle beam is irradiated so as to hit one of the edges of the second aperture A detector that measures each current value of the charged particle beam formed by the above, a deviation information acquisition mechanism that acquires deviation information of the center position of the charged particle beam from each measured current value, and alignment adjustment based on the deviation information And an adjustment amount calculation mechanism for calculating the amount.

  According to the present invention, in the charged particle beam drawing apparatus and the charged particle beam drawing method, the current density distribution during drawing can be automatically adjusted.

It is a conceptual diagram of the electron beam drawing apparatus of 1 aspect of this invention. It is a flowchart of alignment adjustment in one mode of the present invention. It is a figure which shows the shape and irradiation position of the aperture in 1 aspect of this invention. FIG. 6 is a diagram illustrating an example of a current value depending on an irradiation position in one embodiment of the present invention. FIG. 6 is a diagram illustrating an example of a current value depending on an irradiation position in one embodiment of the present invention. It is a figure which shows the shift | offset | difference of the center position of the electron beam in 1 aspect of this invention. It is a flowchart of alignment adjustment in one mode of the present invention. It is a figure which shows the shape and irradiation position of the aperture in 1 aspect of this invention. FIG. 10 shows current values with respect to scan amounts in one embodiment of the present invention. FIG. 10 shows current values with respect to scan amounts in one embodiment of the present invention. 6 is a diagram illustrating a relationship between a change amount of a current value and a scan position in one embodiment of the present invention. It is a figure which shows the shift | offset | difference of the center position of the electron beam in 1 aspect of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 shows a conceptual diagram of an electron beam drawing apparatus which is a charged particle beam drawing apparatus of the present embodiment. As shown in FIG. 1, an aligner 12 that adjusts the alignment of the electron beam and a deflector 13 that deflects the electron beam 10 are arranged below the electron gun 11 that irradiates the electron beam 10 as a control system that controls the electron beam 10. Apertures 14a and 14b for shaping the electron beam 10 are arranged.

  The aligner 12 controls this and is connected to an aligner driver 22a having a power source, an amplifier, and the like, and the deflector 13 is connected to a deflector driver 23 that controls the aligner driver 22a.

  Here, a square opening is formed in the upper aperture 14a. The lower aperture 14b has two sets of parallel edges, and further, an opening having a pair of parallel edges having an angle of 45 ° with these edges and an edge perpendicular thereto is formed.

  A stage 16 on which a sample 15 to be used for drawing is further placed is placed below the control system composed of these. Below the stage 15, an electron beam 10 shaped through two apertures 14a and 14b is irradiated, and a Faraday cup 17a for measuring current and a detector 17 having an ammeter 17b are installed.

  Such a detector 17 is connected to a deviation information acquisition mechanism 18 that acquires deviation information of the center position of the electron beam 10. Further, it is connected to an adjustment amount calculation mechanism 19 that calculates the adjustment amount of the aligner based on the acquired deviation information. The adjustment amount calculation mechanism 19 is connected to the aligner driver 22.

  Drawing is performed on the sample 15 using such an electron beam drawing apparatus. First, in the electron gun 11, electrons are emitted from a cathode (not shown), and are controlled and accelerated to irradiate the electron beam 10.

  The alignment of the irradiated electron beam 10 is initially adjusted in the XY direction in the aligner 12. Then, after being shaped by the apertures 14a and 14b and adjusted in position by the polarizer 13, the stage 16 is scanned in the X and Y directions and irradiated to a desired position on the placed sample 15, thereby drawing. Is done.

  While drawing is performed, for example, alignment adjustment is performed every predetermined time.

  As shown in the flowchart in FIG. 2, the electron gun 10 emits the electron beam 10 (Step 1-1). At this time, initial alignment adjustment is performed in the XY directions by the aligner 12 controlled by the aligner driver 22. Then, the electron beam 10 that has undergone the alignment adjustment is irradiated onto the aperture 14a. In the aperture 14a, the electron beam 10 formed into a square is centered on two parallel edges of the aperture 14b by the deflector 13 controlled by the deflector driver 23, as shown in FIG. , A, b, c, and d are irradiated to form a measurement shape (Step 1-2).

  The electron beams irradiated and shaped at the respective positions a, b, c, and d are collected by the Faraday cup 17a by the detector 17, and the respective current values are measured by the ammeter 17b (Step1- 3). At this time, when the center position of the electron beam is at the center (correct position) of the square formed in the aperture 14a, these current values are substantially equal as shown in FIG.

  However, when the current value deviates from the center, these current values vary. For example, when a is large and c is small as shown in FIG. 5, the center position 10c of the electron beam is shifted in the square formed in the aperture 14a as shown in FIG. 6 (10c ′ ) Therefore, it is necessary to correct this for the arrow.

  Therefore, it is determined whether or not the difference between the measured current values is within the specifications (Step 1-4). If it is within the specification, alignment adjustment is not performed. On the other hand, when the specification is exceeded, the shift information acquisition mechanism 18 acquires shift information such as the shift direction and the approximate shift amount (Step 1-5).

  Based on the deviation information, the adjustment amount calculation mechanism 19 calculates the adjustment amount of the current for XY control in the aligner 12 (Step 1-6). Further, the aligner driver 22 controls the aligner 12 based on the calculated adjustment amount, and alignment adjustment is performed (Step 1-7).

  The electron beam thus adjusted in alignment is again irradiated so as to be applied to the edge of the aperture 14b (Step 1-2). Similarly, when the difference in current value is suppressed within the specification, the process ends.

  In this way, the electron beam is shaped into four shapes by the aperture, and each current value is measured, so that it is possible to easily detect the deviation without measuring the current values at many points as in the past. In addition to being able to detect, it is possible to acquire deviation information. Therefore, as described above, the alignment adjustment of the electron beam can be performed every predetermined time during drawing.

  In the present embodiment, the edge of the aperture 14b is shaped so that the diagonal line of the electron beam shaped by the aperture 14a is applied, but it may be shaped in the state of being rotated to the same angle at each position. For example, it may be formed to be a rectangle by rotating 45 °. Further, the two sets of parallel edges in the aperture 14b do not necessarily have to be vertical as long as they are formed in two axial directions.

(Embodiment 2)
In the present embodiment, the deviation of the center position of the electron beam is similarly adjusted during drawing by the same apparatus as in the first embodiment, but the current value is measured by scanning the electron beam formed by the upper aperture. Is different.

  Similar to the first embodiment, alignment adjustment is performed every predetermined time during drawing.

  As shown in the flowchart of FIG. 7, the electron beam 10 is irradiated from the electron gun 11 (Step 2-1). Similarly, the initial alignment adjustment was performed, and the electron beam 10 irradiated to the aperture 14a and formed into a square was controlled by the deflector driver 23 at positions a and d of the aperture 14b as shown in FIG. Scanning irradiation is performed by the deflector 13 in the direction in which the angle with the edge of the aperture 14 becomes 45 ° (in the direction of the arrow) (Step 2-2).

  Similarly, each of the irradiated electron beams is measured at the detector 17 (Step 2-3). For example, the current value in the scan direction at the position a is as shown in FIG. 9, and the current value with respect to the scan amount at the position d is as shown in FIG.

  At this time, when the center position of the electron beam is at the center (correct position) of the square formed in the aperture 14a, the peak of the change amount (current differential waveform) of each current value becomes the center position.

  However, when it deviates from the center, at least one of the peak positions deviates from the center. For example, as shown in FIG. 11 showing the relationship between the change amount of the current value and the scan position, when the peak at the position a is not shifted but the peak at the position d is shifted, the center position 10c of the electron beam is as shown in FIG. Therefore, it is necessary to correct this by the amount of the arrow.

  Thus, the shift information acquisition mechanism 18 acquires shift information such as the shift amount and the shift direction from each measured current value (Step 2-4). Then, it is determined whether or not the amount of deviation is within the specification (Step 2-5). If it is within the specification, alignment adjustment is not performed. On the other hand, when the spec is exceeded, the adjustment amount calculation mechanism 19 calculates the adjustment amount of the current for XY control in the aligner 12 (Step 2-6) based on the deviation information, and the alignment adjustment is performed (Step 2-7). ).

  In this way, the shaped electron beam is scanned in two axial directions so as to be applied to the edge of the aperture, and each current value corresponding to the scan position is measured. Without measuring the current value, it is possible to easily acquire misalignment information and adjust the alignment. Therefore, as described above, alignment adjustment can be performed at predetermined time intervals during drawing.

  In the present embodiment, scanning is performed so that the angle with the edge of the aperture 14b is 45 °, but the scanning direction is not particularly limited and may be any biaxial direction.

  In these embodiments, the alignment adjustment is performed every predetermined time during drawing. However, the alignment adjustment may be performed when drawing is completed or before drawing, or may be performed in accordance with a positional deviation warning.

  In these embodiments, the electron beam is used as the charged particle beam. However, the present invention is not limited to the electron beam, and other charged particle beams such as an ion beam can be used. In the case of using an ion beam, Ar + ions are formed by collision of thermoelectrons generated at the cathode with Ar gas or the like introduced into the ion gun. The formed Ar + ions are accelerated in the same manner as the electron beam, irradiated onto the sample, and a predetermined pattern is drawn. At that time, alignment adjustment can be performed in the same manner.

  In addition, this invention is not limited to embodiment mentioned above. Various other modifications can be made without departing from the scope of the invention.

DESCRIPTION OF SYMBOLS 10 ... Electron beam 11 ... Electron gun 12 ... Aligner 13 ... Deflector 14a, 14b ... Aperture 15 ... Sample 16 ... Stage 17 ... Detector 17a ... Faraday cup 17b ... Ammeter 18 ... Deviation information acquisition mechanism 19 ... Adjustment amount calculation mechanism 22 ... aligner driver 23 ... deflector driver

Claims (5)

Irradiate a charged particle beam from a charged particle gun,
A first shaping of the charged particle beam with a first aperture;
Performing the second shaping by irradiating one of the edges of the second aperture with the charged particle beam having undergone the first shaping so as to have a predetermined area;
A current value of the charged particle beam subjected to the second shaping is measured;
From each of the current values obtained by performing the second shaping and the measurement of the current value in the same manner for a plurality of the edges, obtaining deviation information of the center position of the charged particle beam,
A charged particle beam drawing method, wherein alignment adjustment of the charged particle beam is performed based on the deviation information.   The charged particle beam drawing method according to claim 1, wherein alignment adjustment of the charged particle beam is performed so that each of the current values becomes equal. In the second shaping, the charged particle beam is scanned in two axial directions,
Measure the current value corresponding to the scan position,
The charged particle beam drawing method according to claim 1, wherein the deviation information is acquired from fluctuations of the measured current values.   The charged particle beam drawing method according to claim 3, wherein an alignment adjustment amount is calculated based on the deviation information. A charged particle gun for irradiating a charged particle beam;
An aligner for adjusting the alignment of the charged particle beam;
A deflector for deflecting the charged particle beam;
A first aperture for shaping the charged particle beam;
A second aperture for shaping the charged particle beam shaped by the first aperture;
A detector for measuring each current value of the charged particle beam formed by irradiating the charged particle beam so as to be applied to any edge of the second aperture;
A deviation information acquisition mechanism for acquiring deviation information of the center position of the charged particle beam from the measured current values;
A charged particle beam drawing apparatus comprising: an adjustment amount calculation mechanism that calculates an adjustment amount of the aligner based on the deviation information.

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