JP6951673B2 - Charged particle beam drawing device and its control method - Google Patents

Description

The present invention relates to a charged particle drawing device for forming a pattern on the surface of an irradiated object by using a charged particle beam in an exposure stage, and a control method thereof.

Multi-beam lithography using multi-beam has been developed conventionally. Multi-beam lithography is used to form a pattern on an irradiated object such as a silicon wafer or a photomask.

In order to realize multi-beam lithography, an electron beam drawing apparatus using multi-beam is used. This electron beam drawing device includes an electron beam generator that generates an electron beam, an aperture device that generates a multi-beam containing a plurality of minute beams from the electron beam, and a deflection device that deflects the multi-beam and irradiates the irradiated object. A blanking device is provided between the aperture device and the deflection device.

Of these, the blanking device emits a desired microbeam to the outside among the multi-beams generated by the aperture device and guides the other microbeams to the deflecting device. This blanking device causes the multi-beam blanking. The ranking density (on / off density of the minute beam) can be changed from 0% to 100%.

Here, as a result of intensive research, the inventor of the present application has made the absorption plate due to the Coulomb force generated between each minute beam and the fluctuation of the electromagnetic field caused by the minute beam absorbed by the absorption plate provided in the deflection device. It was discovered that the passing minute beam was distorted. Here, since the irradiation amount of the minute beam to the irradiated object fluctuates according to the drawing pattern on the irradiated object, it also fluctuates according to the blanking density of the multi-beam, and the Coulomb force generated between the minute beams and , The electromagnetic field caused by the absorption plate also fluctuates each time. Therefore, the distortion of the minute beam fluctuates for each shot of the charged particle beam during the irradiation process of the charged particle beam, whereby the charged particle beam having an appropriate dose amount is placed at an appropriate position with respect to the object to be irradiated. It was also newly discovered that it may not be possible to irradiate.

However, conventionally, a technique for adjusting the position of the multi-beam according to a change in the blanking density of the multi-beam during drawing by an electron beam drawing apparatus has not been developed.

JP-A-2010-123966

The present invention has been made in consideration of such a point, and when the blanking density of the multi-beam changes during drawing, the position of the multi-beam can be adjusted in response to the change. An object of the present invention is to provide a drawing device and a control method thereof.

The present invention includes a charged particle beam generator that generates a charged particle beam, an aperture device that passes the charged particle beam to generate a multi-beam including a plurality of minute beams, and includes an aperture having a plurality of openings. A deflecting device including an electronic lens that deflects the multi-beam and irradiates the irradiated body, and an intervening between the aperture device and the deflecting device, a predetermined minute beam is removed outward, and another minute beam is removed. The control device includes a blanking device for guiding the lens to the deflection device, an electron beam generator, an aperture device, the deflection device, and a control device for controlling the blanking device. A blanking density map including the distribution of the ranking density is acquired, and the drawing data of the drawing data is based on a parameter list showing the relationship between the blanking density map obtained in advance and the optimum control parameters of the electronic lens of the deflection device. It is a charged particle beam drawing apparatus characterized in that the optimum control parameter of the electronic lens is selected from a blanking density map to control the electronic lens.

The present invention is a charged particle beam drawing device, wherein the blanking density map is a map in which the multi-beam is divided into a plurality of regions and each region has an assigned blanking ratio.

The present invention is a charged particle beam drawing apparatus, characterized in that the electronic lens includes an electrostatic deflector having multiple poles, and the optimum control parameter is a deflection voltage applied to each pole.

The present invention is a control method for a charged particle beam drawing apparatus, wherein the electron lens includes an electrostatic deflector having multiple poles, and the optimum control parameter is a deflection voltage applied to each pole.

The present invention is a charged particle beam drawing apparatus characterized in that the electrode lens is controlled based on the control parameters of the electrode lens to correct a distorted multi-beam array in an ideal grid pattern.

The present invention is a charged particle beam drawing apparatus, wherein the parameter list includes a misalignment amount of a multi-beam corresponding to a blanking density map.

The present invention includes a charged particle beam generator that generates the charged particle beam, an aperture device that passes the charged particle beam to generate a multi-beam including a plurality of minute beams, and includes an aperture having a plurality of openings. A deflecting device including an electronic lens that deflects the multi-beam and irradiates the irradiated body, and an intervening between the aperture device and the deflecting device, a predetermined minute beam is removed outward, and another minute beam is removed. From the drawing data in the control method of the charged particle beam drawing device including the blanking device for guiding the lens to the deflection device, the electron beam generator, the aperture device, and the control device for controlling the deflection device and the blanking device. In the parameter list showing the relationship between the step of acquiring the blanking density map including the distribution of the blanking density of the multi-beam, the blanking density map obtained in advance, and the optimum control parameter of the electronic lens of the deflection device. Based on this, it is a control method of a charged particle beam drawing apparatus including a step of selecting an optimum control parameter of the electronic lens from a blanking density map of the drawing data and controlling the electronic lens.

The present invention is a control method for a charged particle beam drawing device, wherein the blanking density map is a map in which the multi-beam is divided into a plurality of regions and each region has an assigned blanking ratio. ..

The present invention is a control method for a charged particle beam drawing apparatus, wherein the electron lens includes an electrostatic deflector having multiple poles, and the optimum control parameter is a deflection voltage applied to each pole.

The present invention is a control method for a charged particle beam drawing apparatus, characterized in that the electronic lens is controlled based on the optimum control parameters of the electronic lens to correct a distorted multi-beam array in an ideal grid pattern.

The present invention is a control method of a charged particle beam drawing apparatus, wherein the parameter list includes a misalignment amount of a multi-beam corresponding to a blanking density map.

As described above, according to the present invention, the position of the multi-beam can be adjusted according to the blanking density of the multi-beam, whereby a desired charged particle beam drawing can be realized by using the multi-beam.

FIG. 1 is a schematic view showing a charged particle beam drawing apparatus according to the present invention. FIG. 2 is a cross-sectional view showing an aperture device and a blanking device. FIG. 3 is a plan view showing an aperture device. FIG. 4 is a flowchart showing a control method of the charged particle beam drawing device. FIG. 5 is a diagram showing a blanking density map of a multi-beam. FIG. 6 is a diagram showing the relationship between the blanking density map, the amount of misalignment, and the optimum control parameters of the electronic lens. 7 (a) and 7 (b) are diagrams showing the amount of misalignment of the multi-beam. 8 (a) and 8 (b) are views showing the position of the multi-beam before the correction and the position of the multi-beam after the correction. 9 (a), (b), (c), (d), and (e) are views showing the shape of the corrected multi-beam.

<Embodiment of the present invention>
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the charged particle beam drawing apparatus 1 according to the present invention is used for exposing an irradiated object such as a silicon wafer or a photomask to form a pattern, and is used for the illumination system 2 and PD. It includes a (Pattern Definition) system 3, a projection system 4, and a substrate station 5 including a substrate stage 14 that holds a substrate (illuminated body) 13. Then, the entire charged particle beam drawing apparatus 1 is held in a high vacuum housing (shown) so that the beams 1a, 1b, and 1c propagate reliably along the optical axis cx of the apparatus without being obstructed. It is housed in the vacuum.

Among the charged particle beam drawing devices 1, the illumination system 2 includes an electron gun (charged particle beam generator) 7 that generates a charged particle beam 1a such as an electron beam, an extraction system 8, and a condenser lens system 9. include. The charged particle beam drawing apparatus 1 may include a general blanking polarizing device 9a. However, as the charged particle beam, in general, other charged particles can be used as well instead of the electron beam. For example, in addition to electron beams, these may use, for example, hydrogen ions or heavy ions, charged atomic clusters, or charged molecules, where "heavy ions" are ionic elements heavier than C, such as O, N, or Ne, Ar. , Kr, Xe and other rare gases.

The charged particle beam 1b emitted from the illumination system 2 by the condenser lens system 9 is a wide, substantially telecentric particle beam. The charged particle beam 1b then enters the PD system 3.

FIG. 2 describes the details of the cross section of the PD system 3 in more detail. This shows a beam 1b structured into a patterning beam, but for simplification, only two beams 20 are described instead of the plurality of beams. The deflected beam 21 is indicated by a dotted line wherever possible the beam is deflected off its path.

The PD system 3 of FIG. 2 includes an aperture device 30 including a continuously arranged aperture plate 16 and a blanking device 17A including a blanking plate 17.

The aperture plate 16 has an optional protective layer 15 that protects the plate from colliding energy particles and a plurality of openings 22 and 23 (see FIG. 3).

The blanking plate 17 also has several openings 17a corresponding to the openings 22 and 23 of the aperture plate 16. Each opening 17a comprises a set of blanking means acting on the beamlet beyond the region. In FIG. 2, these blanking means include a set of electrodes, namely a ground electrode 18 and a deflection electrode 19. By energizing these electrodes 18 and 19, the opening 17a can be "switched off", which deflects the beam (the path indicated by the dotted arrow 21) and thus reaches the substrate 13. There is no such thing. When the electrodes are not energized, the opening 17a is "switched on" and the beam is not deflected from its path (arrow 20). Energization is performed by applying a voltage between electrodes 18 and 19 that is sufficiently different from the default voltage in the non-energized state, and the default voltage is usually zero, that is, the electrodes are at the same potential (energized). Within a small tolerance compared to the voltage). The energizing voltage is typically in the range of a few volts.

Then, the charged particle beam 1b that has passed through the PD system 3 becomes a multi-beam 1c including a plurality of minute beams by the aperture device 30 of the PD system 3, and a predetermined minute beam is removed outward by the blanking device 17A. The multi-beam 1c containing only other minute beams is applied to the illumination system 4. Here, by being turned on / off (ON / OFF) by the blanking device 17A, the multi-beam 1c has a desired blanking density. The blanking density of this multi-beam will be described later.

In the embodiment shown in FIG. 1, the projection system 4 is composed of a plurality of continuous particle-optical projection device stages consisting of an electrostatic or electronic lens, or other deflecting means. These lenses and means are shown only in symbolic form because their applications are well known from the prior art. The projection system 4 forms a reduced image formation by the crossovers c1 and c2. The reduction ratio for both stages is selected so that the overall reduction is in the hundreds, eg 200x (FIG. 1 is not scaled).

Measures are taken throughout the projection system 4 to extensively compensate the lens and / or deflection means for color and geometric aberrations. As a means for shifting the image as a whole in the lateral direction, that is, along a direction perpendicular to the optical axis cx, the projection system 4 is provided with deflection means 11 and 12 made of an electronic lens. The deflecting means is, for example, near the crossover as shown in FIG. 1 by the first deflecting means 11, or after the final lens of the projection device, as in the case of the second stage deflecting means 12 shown in FIG. It can be realized as a multi-pole electrode system arranged in any of them. In this device, the multi-pole electrodes shift the image in relation to the movement of the steps. Further, it is used as a deflection means for two purposes of correcting the imaging system together with the alignment system. Further, the projection system 4 has an absorption plate 10 provided between the first deflection means 11 and the second deflection means 12.

Further, the projection system 4 is provided between the PD system 3 and the deflection means 11, between the first polarizing means 11 and the absorbing plate 10, and between the absorbing plate 10 and the second polarizing means 12, respectively. The condenser lens 6 is included. Further, the substrate stage 14 holding the substrate 13 can be moved in the left-right direction (horizontal direction) in FIG.

The components constituting the charged particle beam drawing device 1, for example, the electron gun 7, the blanking device 17A, the first deflection means 11, the second deflection means 12, and the substrate stage 14 are all control devices 35. Is driven and controlled by.

Next, the operation of the present embodiment having such a configuration, that is, the control method of the charged particle beam drawing apparatus 1 will be described.

First, drawing data to be drawn on the substrate 13 is input to the control device 35, and this drawing data includes information on the blanking density of the multi-beam 1c irradiated on the substrate 13.

Here, the blanking density will be briefly described below. The blanking density is defined as, for example, as shown in FIG. 5, when the region corresponding to the aperture plate 16 of the multi-beam 1c is divided into four regions, the upper left portion, the upper right portion, the lower left portion, and the lower right portion. It refers to the density of the fine beams that exist for each. The blanking density of such a multi-beam 1c is such that a predetermined minute beam is removed outward from the multi-beam 1c including a plurality of minute beams generated by the aperture device 30, and the other minute beams are removed from the illumination system 4. It is generated by the blanking device 17A that leads to.

In FIG. 5, the blanking density of the upper left region A1 and the upper right region A2 of the multi-beam 1c is 100%, and most of the minute beams are guided to the illumination system 4.

On the other hand, the lower left region A3 of the multi-beam 1c has a blanking density of 20%, a large number of minute beams are removed outward, and the lower right region A4 has a blanking density of 0%. Most of the microbeams are removed outward. Here, the numerical values of the blanking density are set to 0%, 20%, 40%, 60%, 80%, and 100% for each 20% for convenience, and each numerical value has a certain range.

By the way, as a result of intensive research by the inventor of the present application, the multi-beam 1c containing a plurality of minute beams has a Coulomb force acting on each other between the minute beams, or a minute beam removed outward by the blanking device 17A. It was discovered that the direction of each minute beam changes according to the blanking density of the multi-beam 1c due to changes in the electromagnetic field generated by the current absorbed by the absorption plate. The blanking density of the multi-beam 1c fluctuates for each shot of the charged particle beam during the irradiation process of the charged particle beam, whereby the charged particle beam having an appropriate dose amount at an appropriate position with respect to the object to be irradiated. It may not be possible to irradiate.

For example, as shown in FIG. 7A, when the minute beams 1d are arranged in the entire area of the multi-beam 1c without being chipped in a substantially grid pattern, that is, when the multi-beam 1c has a blanking density of 100% in the entire area. , In the first deflection means 11, each minute beam 1d is arranged along a grid pattern.

In FIG. 7A, the first deflection means 11 comprises an electronic lens 11A having eight poles 11a.

On the other hand, as shown in FIG. 7B, when the minute beam 1d is missing in the upper left region of the multi-beam 1c, the blanking density is 0% in the upper left region and 100 in the other regions. It becomes%.

In this case, an imbalance occurs in the forces such as the Coulomb force acting between the minute beams 1d in the electronic lens 11A having eight poles 11a. Therefore, for example, the minute beams 1d arranged from the upper side to the lower side in the center. The line L1 connecting the above is not a straight line but a distorted line.

In such a case, as shown in FIGS. 8A and 8B, by setting the deflection voltage (parameter) of each pole 11a constituting the electronic lens 11A to an optimum value, the minute beam 1d of the multi-beam 1c is multi-layered. It can be arranged in a substantially grid pattern over the entire area of the beam 1c.

For example, when the minute beam 1d is missing in the upper left region of the multi-beam 1c, the blanking density is 0% in the upper left region, and when the blanking density is 100% in the other regions, the upper center is as described above. The line L1 connecting the minute beams 1d arranged downward from the to is a distorted line (FIG. 8 (a)).

Here, FIG. 8A shows the multi-beam 1c before correction. On the other hand, by setting (correcting) the deflection voltage (parameter) of each pole 11a constituting the electronic lens 11A to an optimum value, the corrected multi-beam 1c is arranged from the upper side to the lower side in the center. The line connecting the minute beams 1d is a straight line L2, and each of the minute beams 1d is aligned in a grid pattern (FIG. 8 (b)).

For example, when the deflection voltage is set to the optimum value, the deflection voltage applied to the pole X3 of each pole 11a is changed from X3 = -bVx-aVy to X3 =-(b + c) Vx-aVy. Here, Vx is a voltage for creating an electric field in the X direction, Vy is a voltage for creating an electric field in the Y direction, a and b are arbitrary coefficients for obtaining a uniform electric field, and c is a multi-beam 1c. It is an arbitrary coefficient that corrects the position.

Further, the deflection voltage applied to the pole Y2 is changed from Y2 = bVx-aVy to Y2 = bVx- (a + d) Vy. Here, d is an arbitrary coefficient for correcting the position of the multi-beam 1c.

In this way, the position of the multi-beam 1c can be corrected so that the minute beams 1d of the multi-beam 1c can be aligned in a grid pattern (see FIG. 8B).

As described above, in order to align each minute beam 1d of the multi-beam 1c in a grid pattern according to the blanking density of the multi-beam 1c, each pole 11a constituting the electronic lens 11A has an optimum value of the deflection voltage. ..

In the present embodiment, as shown in FIG. 4, the position of each minute beam of the multi-beam 1c is measured in advance according to the blanking density of the multi-beam 1c. Then, the deflection voltage of each pole 11a of the electronic lens 11A for correcting the minute beam 1d of the multi-beam 1c and correctly aligning in a grid pattern is obtained by actual measurement or simulation, and this deflection voltage is optimized for the electronic lens 11A. It is a parameter.

Next, the blanking density of the multi-beam 1c is variously changed, and the optimum parameters of the electronic lens 11A according to the blanking density are obtained.

In this case, the blanking density of the multi-beam 1c is changed for each of the regions A1, A2, A3, and A4 corresponding to the upper left, upper right, lower left, and lower right of the aperture plate 16, for example, the four regions A1, A2, and A3. , A4 is given a blanking density of 0%, 20%, 40%, 60%, 80%, or 100%.

In this way, different blanking density maps having their respective blanking densities are obtained for each of the four regions A1, A2, A3, and A4. Then, for each blanking density map 1, 2, 3, ..., The amount of misalignment (A, B, C, ...) Of the minute beam 1d of the multi-beam 1c is obtained, and the amount of misalignment is eliminated to eliminate the amount of misalignment of the multi-beam 1c. The optimum control parameters of the electronic lens for correctly aligning the minute beams 1d in a grid pattern are required.

In this way, a blanking density map, a parameter list showing the relationship between the amount of misalignment and the optimum control parameters of the electronic lens can be obtained (see FIG. 6). In this case, the optimum control parameters of the electronic lens include the optimum control parameters of the electronic lens 11A of the first deflection means 11 and the optimum control parameters of the electronic lens of the second deflection means 12.

In the present embodiment, when drawing data is input to the control device 35 as shown in FIG. 4, the control device 35 acquires the blanking density in the drawing data and displays the blanking density map of the drawing data. obtain.

Next, the control device 35 compares the blanking density map in the drawing data used for irradiation with the blanking density map in the parameter list, and the blanking density of the drawing data from the blanking density map in the parameter list. Select a blanking density map that is close to the map and optimal control parameters for the electronic lens.

Next, the control device 35 corrects the control parameters of the electronic lens 11A of the first deflection means 11 and the electronic lens of the second deflection means 12 to the above-mentioned optimum control parameters.

After that, the control device 35 executes the actual drawing operation. Specifically, a charged particle beam 1a is generated from the electron gun 7, and the charged particle beam 1a passes through the illuminating device 2 to become a beam 1b and enters the PD system 3. Next, the beam 1b becomes a multi-beam 1c including a plurality of minute beams 1d by the aperture device 30 of the PD system 3, and the multi-beam 1c has a desired blanking density by the blanking device 17A.

After that, the multi-beam 1c enters the projection system 4 from the PD system 3 and is then irradiated onto the substrate 13 held by the substrate stage 14 of the substrate station 5.

During this period, as described above, the control device 35 sets the electronic lens 11A of the first deflection means 11 and the electronic lens of the second deflection means 12 to the optimum values according to the blanking density map of the multi-beam 1c. Control using the optimum control parameter (deflection voltage). Therefore, the position of the multi-beam 1c can be adjusted on the substrate 13 to irradiate the multi-beam 1c including the minute beams 1d correctly arranged in a grid pattern.

In this case, the first deflection means 11 and the second deflection means 12 are translated and adjusted so that the distorted multi-beam array 11c can be arranged in an ideal grid pattern by using the optimum control parameter (deflection voltage). (Fig. 9 (a)), adjust to enlarge or reduce (Fig. 9 (b)), correct the rotational component (Fig. 9 (c)), or remove the translational component. The position of the multi-beam 1c can be adjusted by correcting it (FIG. 9 (d)) or by correcting it so as to remove the platform formation.

As described above, according to the present embodiment, the optimum control parameters defined to the optimum values are obtained according to the blanking density map of the multi-beam 1c, and the first deflection means 11 and the second are obtained by the optimum control parameters. The deflection means 12 of the above can be controlled. Therefore, it is possible to irradiate the multi-beam 1c in which the minute beams 1d are correctly aligned on the substrate 13.

1 Charged particle beam drawing device 1a Beam 1b Beam 1c Multi-beam 1d Micro beam 2 Illumination system 3 PD system 4 Projection system 5 Substrate station 6 Condensing lens 7 Electron gun 9 Condensing lens system 10 Absorption plate 11 First deflection means 12 Second deflection means 13 Substrate 14 Substrate stage 16 Aperture plate 17 Branking plate 17A Branking device 17a Apertures 22, 23 Aperture 30 Aperture device 35 Control device

Claims (6)

A charged particle beam generator that generates a charged particle beam,
An aperture device that passes through the charged particle beam to generate a multi-beam containing a plurality of minute beams, and also includes an aperture having a plurality of apertures.
A pair of deflection devices including an electronic lens that deflects the multi-beam and irradiates the irradiated body.
A blanking device, which is interposed between the aperture device and the pair of deflection devices, removes a predetermined minute beam outward, and guides another minute beam to the deflection device.
The electron beam generator, the aperture device, the pair of deflection devices, and the control device for controlling the blanking device are provided.
The control device acquires a blanking density map including the distribution of the blanking density of the multi-beam from the drawing data, and the relationship between the blanking density map obtained in advance and the optimum control parameter of the electronic lens of each deflection device. Based on the parameter list indicating, the optimum control parameter of the electronic lens is selected from the blanking density map of the drawing data to control the electronic lens of each deflection device.
The electronic lens of each deflector includes an electrostatic deflector with multiple poles, the optimum control parameter is the deflection voltage applied to each pole.
The parameter list includes the amount of misalignment of the multi-beam corresponding to the blanking density map.
The pair of deflectors use optimal control parameters to translate and adjust the multi-beam, or to correct the rotational component of the multi-beam, or to remove the orthogonal component of the multi-beam. A charged particle beam drawing apparatus, characterized in that the position of the multi-beam is adjusted so as to remove the platform-forming portion of the multi-beam. The charged particle beam drawing apparatus according to claim 1, wherein the blanking density map is a map in which the multi-beam is divided into a plurality of regions and each region has an assigned blanking ratio. The charged particle beam drawing apparatus according to claim 1 or 2, wherein the electronic lens is controlled based on the optimum control parameter of the electronic lens to correct a distorted multi-beam array in an ideal grid pattern. A charged particle beam generator that generates a charged particle beam,
An aperture device that passes through the charged particle beam to generate a multi-beam containing a plurality of minute beams, and also includes an aperture having a plurality of apertures.
A pair of deflection devices including an electronic lens that deflects the multi-beam and irradiates the irradiated body.
A blanking device, which is interposed between the aperture device and the pair of deflection devices, removes a predetermined minute beam outward, and guides another minute beam to the deflection device.
In the control method of the charged particle beam drawing device including the electron beam generator, the aperture device, the pair of deflection devices, and the control device for controlling the blanking device, the blanking density of the multi-beam is determined from the drawing data. The process of obtaining a blanking density map including the distribution, and
Optimal control parameters of the electronic lens from the blanking density map of the drawing data based on a parameter list showing the relationship between the blanking density map obtained in advance and the optimum control parameters of the electronic lens of the pair of deflection devices. To control the electronic lens of each deflector by selecting
The electronic lens of each deflector includes an electrostatic deflector with multiple poles, the optimum control parameter is the deflection voltage applied to each pole, and the parameter list is the multi-beam corresponding to the blanking density map. Including the amount of misalignment of
The pair of deflectors use optimal control parameters to translate and adjust the multi-beam, or to correct the rotational component of the multi-beam, or to remove the orthogonal component of the multi-beam. either, or the control method of a charged particle beam drawing apparatus characterized by adjusting the position of the multi-beam is corrected so as to eliminate the trapezoidal components of the multi-beam. The control method for a charged particle beam drawing apparatus according to claim 4, wherein the blanking density map is a map in which the multi-beam is divided into a plurality of regions and each region has an assigned blanking ratio. The control method for a charged particle beam drawing apparatus according to claim 4 or 5, wherein the electronic lens is controlled based on the optimum control parameters of the electronic lens to correct a distorted multi-beam array in an ideal grid pattern. ..

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