JP2012094614A - Automatic adjusting method of charged particle beam drawing device, and charged particle beam drawing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide means capable of improving line width linearity by optimizing current density uniformity of a figure 8 having restricted dimensions, as to an automatic adjusting method of a charged particle beam drawing device and the charged particle beam drawing device.SOLUTION: An automatic adjusting system of a charged particle beam drawing device includes beam alignment means 29 for adjusting a position of a charged particle beam to irradiate a first molded opening plate with respect to an opening position of the opening plate in the foregoing part of the first molded opening plate 3, means for measuring a current density distribution of the charged particle beam passing through the opening of a second molded opening plate 7 at a height position of the opening plate and means for extracting a linear component from the current density distribution obtained by the measuring means, and is configured so as to adjust an irradiation position of the first molded opening plate 3 by the beam alignment means 29 so that inclined components obtained by the measuring means and the extracting means are removed.

Description

  The present invention relates to an automatic adjustment method for a charged particle beam drawing apparatus and a charged particle beam drawing apparatus, and more particularly to an automatic adjustment method for a charged particle beam drawing apparatus and a charged particle beam drawing apparatus with improved current density uniformity.

  FIG. 7 is a diagram showing a configuration example of a conventional variable shaped electron beam drawing apparatus (see, for example, Non-Patent Document 1). The principle of the variable shaped electron beam drawing apparatus will be described below with reference to this figure.

  As shown in FIG. 7, the electron beam 1 is irradiated to the 1st shaping | molding aperture plate 3 through the 1st lens 2 (irradiation lens). In general, the light source 4 may be a crossover formed immediately after the electron gun. The image 5 of the first light source is tied under the first shaping aperture plate 3. Next, the image 3 ′ of the opening of the first molded aperture plate 3 is projected onto the second molded aperture plate 7 by the second lens (molded lens) 6, and the image 3 of the aperture of the first molded aperture plate 3. The figure 8 determined by the overlap between the 'and the opening of the second molded aperture plate 7 is projected through the reduction lens 9 and the objective lens 10 onto the material 11 coated with resist (photosensitive material). As a result, the resist is exposed. That is, the projected figure 12 is transferred to the material 11.

  FIG. 8 is an explanatory diagram of a figure composed of a first molded aperture plate and a second molded aperture plate. An image 3 ′ of the opening of the first shaping aperture plate 3 is overlapped on the opening of the second shaping aperture plate 7 to form a figure 8.

  A desired pattern can be drawn on the material 11 by controlling the shape, size, and position of the projected figure 12. The shape, size, and position of the projected figure 12 are controlled by the arithmetic / control device 13 based on the pattern information stored in the storage device 14.

  A shaping deflector 15 is used to control the shape and dimensions of the projected figure 12. That is, the electron beam 1 is deflected by the shaping deflector 15, the image 3 ′ of the opening of the first shaping aperture plate 3 is moved with respect to the opening of the second shaping aperture plate 7, and the shape and size of the figure 8 are changed. Change. The shaping deflector 15 is controlled by the arithmetic / control device 13 via the shaping deflector drive amplifier 16.

  In order to control the position of the projection figure 12, the objective deflector 17 and the material stage 18 are used in combination. Since the deflectable region (deflection field) of the objective deflector 17 is limited, first, the material stage 18 is used to perform positioning with a large step, and then the positioning with a smaller step than the objective deflector 17 is performed. The objective deflector 17 and the material stage 18 are controlled by the arithmetic / control device 13 via an objective deflector drive amplifier 19 and a stage drive device 28, respectively.

  If the projected figure 12 is always projected onto the material 11, only a one-stroke figure can be drawn, so that a general figure drawing requires means control (blanking) of the electron beam 1. In the optical system of FIG. 7, this blocking control is performed by the blankers 21 and 22. The blankers 21 and 22 are controlled by the arithmetic / control device 13 via the blanker driving amplifier 23.

  More specifically, the blankers 21 and 22 are first actuated, the electron beam 1 is interrupted, the shaping deflector 15 and the objective deflector 17 are actuated, and after determining the shape, size and position of the projection figure 12, the blankers 21 and 22 The blocking of the electron beam 1 by 22 is released, and the projected figure 12 is projected onto the material 11. When exposure is performed for a predetermined time, the electron beam 1 is again interrupted. This exposure for a predetermined time is usually called a shot.

  The electron beam 1 is blocked by blanking because the image 24 of the second light source and the image 24 of the second light source are moved in the direction perpendicular to the optical axis as shown in FIG. 1 (second light source image 24) is received by the blanking aperture plate 25. Here, the image 24 of the second light source is an image of the image 5 of the first light source formed at the height position of the blanking aperture plate 25 by the second lens 6.

  The blankers 21 and 22 have a two-stage configuration as shown in FIG. 7 because, as shown in FIG. 10, the height position of the deflection fulcrum 26 of the electron beam 1 at the time of blanking is set to the first shaping aperture plate. This is to prevent the irradiation region of the first shaping aperture plate 3 from moving at the time of blanking by matching with the height position of 3. The height position of the deflection fulcrum 26 can be adjusted by making the blanker into a two-stage configuration and selecting the interlocking ratio of the blankers 21 and 22 (see Patent Document 1).

The exposure time (shot time) per shot is the required exposure [μC / cm ² ] (the exposure required to obtain the desired line width), and the current density [A / cm ² ] of the projected figure 12. It is determined by dividing by. That is, the shot time is inversely proportional to the current density of the projected figure 12. The current density is determined by dividing the beam current flowing into the material 11 by the area of the projection figure 12.

  These calculations are performed by the arithmetic / control device 13. The beam current flowing into the material 11 can be detected by moving the stage 18 and flowing the electron beam 1 into the current detector 27. The detected beam current is digitized by the signal processing device 28 and input to the arithmetic / control device 13.

  From the relationship between the shot time and the current density, the shot time is shortened when the current density of the projection figure 12 is increased. That is, the drawing throughput is improved. With the miniaturization of semiconductor devices, the number of patterns drawn on the material 11 is increasing year by year. Therefore, improvement of the drawing throughput by improving the current density is an important issue for the future of the variable shaped electron beam drawing apparatus.

  In order to increase the current density of the projection figure 12, the magnification of the reduction lens 9 or the objective lens 10 may be lowered and the projection magnification of the projection figure 12 may be reduced. Alternatively, the intensity of the first lens 2 may be increased, and the irradiation area of the first shaping aperture plate 3 by the electron beam 1 may be narrowed down.

  However, in the case of the former method, as the size of the projected figure 12 becomes smaller, the number of shots necessary for drawing a desired pattern increases and the drawing time increases. That is, the drawing throughput is reduced. In order to secure the dimension of the figure while reducing the projection magnification of the projection figure 12, it is necessary to increase the opening of the first shaping aperture plate 3 and the second shaping aperture plate 7, that is, to increase the dimension of the figure 8. . On the other hand, in the latter method, if the first lens 2 is a single lens, its intensity changes and the height position of the light source image 5 changes. In order to maintain the height position of the light source image 5 regardless of the intensity of the first lens 2, the first lens 2 is preferably a zoom lens (see Patent Document 1).

The current density of the projected figure 12 is not only high, but is also required to be stable over time. This is because the line width of the resist pattern depends on the exposure amount. FIG. 11 shows the relationship between the exposure amount and the line width of the resist pattern. The horizontal axis x is the position on the material 11, and the vertical axis is the exposure dose [μC / cm ² ]. Since the exposure amount is the product of the current density and the shot time, the shape of the exposure amount distribution in FIG. 11 can be regarded as the shape of the current density distribution of the projected figure 12 as it is.

In FIG. 11, the intersection (two points) between the curve indicating the exposure distribution and the straight line indicating the resist resolution threshold [μC / cm ² ] corresponds to the edge of the resist pattern, from one intersection to the other intersection. This distance corresponds to the line width CD _x of the resist pattern. Therefore, it is the exposure amount at the edge of the projected figure 12 that determines the line width of the resist pattern. As can be seen from Figure 11, the exposure amount increases (the exposure distribution curve is shifted from the solid line to the broken line), the line width of the resist pattern changes in CD _x 'from CD _x.

  If the current density of the projected figure 12 varies with time, the exposure amount varies as shown in FIG. 11, and as a result, the line width varies. That is, the line width uniformity decreases. Actually, since the current density of the projection figure 12 slightly changes over time, some means for compensating for the fluctuation of the current density is necessary to prevent such fluctuation of the line width. For this purpose, it is a common practice to determine the appropriate shot time each time the current density is measured by appropriately interrupting the pattern drawing.

  The exposure amount of the projected figure 12 can also be changed by changing the size of the projected figure 12 by the shaping deflector 15, that is, changing the dimension of the figure 8. Such a change in exposure amount occurs when the current density of the graphic 8 is not uniform, that is, when the current density of the image 3 'of the opening of the first shaped aperture plate 3 is not uniform. That is, the exposure amount at the edge of the resist pattern (see FIG. 11) reflects the current density of the image 3 ′ of the opening of the first shaping aperture plate 3, and therefore, if the current density is not uniform, the exposure is performed. The quantity varies with the dimensions of the figure 8, i.e. with the movement of the image 3 'of the opening of the first shaping aperture plate 3.

  When such a change in exposure occurs, the linearity of the line width (the linearity of the line width of the resist pattern with respect to the design value or command value of the line width) decreases. Accordingly, it is necessary to make the current density of the image 3 'of the opening of the first shaping aperture plate 3 as uniform as possible. That is, it is required to make the current density in the opening of the first molded aperture plate 3 as uniform as possible.

  For this purpose, it is desirable that the current density of the electron beam 1 that irradiates the first shaped aperture plate 3 is uniform. However, the current density is not actually uniform and is usually maximum in the central axis of the electron beam 1 and attenuates with the distance from the central axis. Therefore, a realistic solution for satisfying the above requirements is to match a local region having the same current density with high uniformity with the opening of the first shaped aperture plate 3.

  As such a technique, the electron beam 1 is deflected by a deflector provided upstream of the first shaping aperture plate 3 to scan the shaping aperture plate and pass through the opening of the first shaping aperture plate 3. A technique for finding a condition for maximizing the current of the electron beam 1 is known (see, for example, Patent Document 2). For simplicity, assuming that the current density distribution of the electron beam 1 on the first shaped aperture plate 3 is axisymmetric, when the central axis of the electron beam 1 coincides with the center of the aperture, the electron beam passing through the aperture It can easily be seen that the current of 1 is maximized, and at the same time, the current density uniformity in the same opening is the best.

  FIG. 12 is a diagram showing a current density distribution of the electron beam 1 on the first shaped aperture plate 3. The horizontal axis is the position on the first shaping aperture plate 3, and the vertical axis is the current density. It can be seen that when the central axis of the electron beam 1 coincides with the center of the aperture, the current of the electron beam 1 passing through the aperture becomes maximum.

JP 2007-67192 A (paragraphs 0030 to 0036, FIG. 1) Japanese Patent Laying-Open No. 2006-93462 (paragraphs 0009 to 0015, FIGS. 2 to 4)

K. Komagata, Y. Nakagawa, and N. Gotoh, Proc. SPIE. Vol. 3096, pp. 125-136 (1997)

  However, even if the current density uniformity in the opening of the first shaped aperture plate 3 is optimized by such a technique, in order to increase the current density of the projected figure 12, as described above, If the size of the opening of the first molded aperture plate 3 and the second molded aperture plate 7 is increased in order to reduce the projection magnification and secure the dimension of the projected figure 12, the inside of the opening of the first molded aperture plate 3 is increased. Current density uniformity decreases, and as a result, line width linearity decreases. This is because the current density on the first shaping aperture plate 3 attenuates with the distance from the central axis.

  Or when the irradiation area | region of the 1st shaping | molding aperture plate 3 is narrowed down similarly as mentioned above, current density uniformity falls and line width linearity falls. In other words, this problem becomes more prominent when the relative dimensions of the openings of the first molded aperture plate 3 and the second molded aperture plate 7 with respect to the irradiation region of the first molded aperture plate 3 are increased.

  In addition, when the current density of the projected figure 12 is increased in this way, the Coulomb effect (a phenomenon in which beam blur increases due to repulsion between electrons) becomes stronger, resulting in a problem that the resolution is lowered.

  In order to suppress these problems as much as possible, it is effective not to increase the dimension of the projected figure 12 more than necessary, that is, to limit the maximum dimension. Such a countermeasure has already been generally implemented in the operation of an actual variable shaped electron beam drawing apparatus. However, if the size of the projected figure 12 is reduced, the drawing throughput is lowered. Therefore, the maximum dimension of the projected figure 12 is determined according to the required line width linearity and resolution.

  In order to limit the maximum dimension of the projected figure 12 in actual operation of the apparatus, it is preferable to limit the maximum dimension of the figure 8 (FIG. 8). However, if the maximum dimension of the figure 8 is reduced, even if the current density uniformity in the opening of the first molded aperture plate 3 is optimized by the technique described in Patent Document 2, the current density uniformity of the figure 8 Is not the best. That is, the line width linearity is not the best. This can be seen from the fact that the center axis of the electron beam 1 passes through the center of the first shaping aperture plate 3 (see FIG. 12) but does not pass through the center of the figure 8 (maximum dimension) (FIG. 13). .

  The present invention has been made in view of such problems, and it is an object of the present invention to provide means capable of optimizing the current density uniformity of the figure 8 having a limited size and improving the line width linearity. It is said. Another object of the present invention is to provide a means for quantifying and managing the current density unevenness. Managing linewidth linearity requires not only that the current density is best under uniform conditions, but also a means of ensuring that it meets certain criteria.

  In order to solve the above problem, the present invention has the following configuration.

  (1) The invention according to claim 1 comprises a charged particle beam source, a first lens, a first molded aperture plate, a second lens and a second molded aperture plate, and A shaping deflector is provided between the first shaping aperture plate and the second shaping aperture plate, and an image of the opening of the first shaping aperture plate is transferred to the second shaping aperture plate by the second lens. A charged particle beam drawing apparatus for projecting and forming a figure having a variable size and shape by superimposing on the opening of the same opening plate, and projecting the same figure on a drawing surface in a reduced size, wherein the first shaping opening plate In the automatic adjustment method of the charged particle beam drawing apparatus, which includes beam alignment means for adjusting the position of the charged particle beam irradiating the first shaping aperture plate with respect to the aperture position of the aperture plate before the first stage, The aperture plate of charged particle beam that passes through the aperture of the shaped aperture plate A step of measuring a current density distribution at a height position, and a step of extracting the slope component from the current density distribution obtained by the measurement step, wherein the slope component obtained by the measurement step and the extraction step is removed. As described above, the irradiation position of the first shaping aperture plate is adjusted by the beam alignment means.

  (2) The invention according to claim 2 is the step of extracting the curve component from the current density distribution, the step of comparing the size of the curve component obtained by the extraction step with a predetermined value, and the size of the curve component. A warning is issued when the value exceeds the predetermined value.

  (3) The invention described in claim 3 includes a charged particle beam source, a first lens, a first molded aperture plate, a second lens, and a second molded aperture plate, and A shaping deflector is provided between the first shaping aperture plate and the second shaping aperture plate, and an image of the opening of the first shaping aperture plate is projected onto the second shaping aperture plate by the second lens. And a charged particle beam drawing apparatus that forms a figure having a variable size and shape by overlapping the opening of the opening plate, and projects the reduced figure onto a drawing surface. In a charged particle beam drawing apparatus including a beam alignment means for adjusting the position of the charged particle beam that irradiates the first shaped aperture plate with respect to the aperture position of the aperture plate in the previous stage, the second shaped aperture plate The charged particle beam passing through the aperture is positioned at the height of the aperture plate. A means for measuring the current density distribution; and an extracting means for extracting the slope component from the current density distribution obtained by the measuring means, so that the slope component obtained by the measuring means and the extracting means is removed. The irradiation position of the first shaping aperture plate is adjusted by the beam alignment means.

  The present invention has the following effects.

  (1) According to the invention of claim 1, the current density uniformity of the charged particle beam passing through the opening of the second shaped aperture plate at the height position of the aperture plate is improved, and as a result The current density uniformity of the figure projected on the material is improved, and the line width linearity is improved.

  (2) According to the invention described in claim 2, since an alarm is issued when the curve component extracted from the current density distribution exceeds a predetermined value, it can be recognized that an abnormality has occurred.

  (3) According to the invention described in claim 3, the current density uniformity of the charged particle beam passing through the opening of the second shaped aperture plate at the height position of the aperture plate is improved, and as a result The current density uniformity of the figure projected on the material is improved, and the line width linearity is improved.

It is a block diagram which shows one Example of this invention. It is a flowchart which shows an example of operation | movement of this invention. It is a figure which shows the inflow state of a beam current. It is a figure which shows the inflow state of a beam current. Is a diagram showing an approximate function J _xa and the straight line components L _x of the current density distribution. It is an illustration of calculation of Delta] s _xk. It is a figure which shows the example of a conventional structure. It is explanatory drawing of the figure comprised by the image of the opening of a 1st shaping | molding opening board, and the opening of a 2nd shaping | molding opening board. It is explanatory drawing of blanking. It is a figure which shows the state which made the height position of the deflection fulcrum of the electron beam at the time of blanking correspond to the height position of the 1st shaping | molding aperture plate. It is a figure which shows the relationship between the exposure amount and the line | wire width of a resist pattern. FIG. 3 is a diagram showing a current density distribution of an electron beam 1 on a first shaped aperture plate 3. It is a figure which shows the current density distribution of the electron beam 1 on the 2nd shaping | molding aperture plate.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[Example 1]
FIG. 1 is a block diagram showing an embodiment of the present invention. Those given the same symbols as those used in FIG. 7 indicate the same components. In the first embodiment, aligners (optical axis aligning deflectors or beam position adjusting means) 29 and 30, an aligner driving amplifier 31, and a monitor 32 are added to the configuration shown in FIG.

  The aligners 29 and 30 are each composed of an X-direction deflector and a Y-direction deflector. As a result, the position of the electron beam 1 with respect to the opening of the first shaping aperture plate 3 is adjusted. The directions of the X-direction deflector and the Y-direction deflector are determined so that the deflection direction of the electron beam 1 in the first shaped aperture plate 3 coincides with the X and Y directions of the aperture plate.

  However, the shape of the opening of the first shaping aperture plate 3 and the second shaping aperture plate 7 is rectangular, and the sides of the openings are parallel to the X or Y axis on each aperture plate. The X and Y axes of the second shaping aperture plate 7 are parallel to the mapping of the X and Y axes on the first shaping aperture plate 3 to the second shaping aperture plate 7, respectively.

The aligners 29 and 30 are controlled by the arithmetic / control device 13 via the aligner driving amplifier 31. At that time, inputs to the aligners 29 and 30 are determined based on a predetermined interlocking ratio. The interlock ratio is expressed as a deflection angle ratio 1: r of the aligners 29 and 30, and the deflection sensitivity (beam deflection angle per unit deflection signal) of the aligners 29 and 30 is D _u and D _l , and the X of the aligners 29 and 30 is X. If the deflection signal input to the direction deflector is s _xu and s _xl and the deflection signal input to the Y direction deflector is s _yu and s _yl , s _xl is between s _xu and s _xl. / S _xu = r · D _u / D _l , and a relationship of s _yl / s _yu = r · D _u / D _l holds between s _yu and s _yl .

  The interlock ratio is selected so that the height position of the deflection fulcrum of the electron beam 1 by the aligners 29 and 30 coincides with the height position of the blanking aperture plate 25 (for example, r = −1). Therefore, even when the aligner is operated, the electron beam 1 is not blocked by the blanking aperture plate 25.

  FIG. 2 is a flowchart showing an example of the operation of the present invention. This operation is automatically performed by the arithmetic / control device 13. Each process will be described below.

After exchanging with a new electron gun and before drawing with an electron beam, first, an instruction for starting the automatic adjustment system of the present invention is sent to the arithmetic and control unit 13 by an operating device (not shown). Then, as shown in FIG. 2, processing S1 is executed in the arithmetic and control unit 13, and the shaping deflector 15 is operated by the technique shown in Japanese Patent Application No. 2009-103550 (hereinafter referred to as prior art), 8 (FIGS. 8 and 13), that is, while expanding the dimension of the projection figure 12, the current detector 7 causes the beam currents I (x _i , y _n ) and I (x _m , y _j ) (1 ≦ i ≦ m, 1 ≦ j ≦ n) are measured. Here, since the figure 8 and the figure 12 are in an optically conjugate relationship, there is no problem in the subsequent processing even if x _i and y _j are the dimensions of the figure 8 and the dimensions of the projected figure 12. However, x ₀ = y ₀ = 0, and x _m and y _n are the maximum dimensions of the figure 8 or the projected figure 12 in the X and Y directions.

In FIG. 3, when the beam current I (x _i , y _n ) is measured by the current detector 27, the dimension of the figure 8 is changed to a strip shape in the X direction, that is, the dimension of the projected figure 12 is expanded in the X direction. Indicates. As can be seen from FIG. 3, the beam current I (x _i , y _n ) is a beam current that flows into a rectangular region having a short side x _i and a long side y _n .

In FIG. 3, x represents the X coordinate on the second shaping aperture plate 7 or the material 11. The straight lines x = x ₀ = 0 and x = x _i are respectively the image of the edge of the opening of the first shaping aperture plate 3 at the height position of the second shaping aperture plate 7 or its projection image onto the material 11; And the projection image onto the edge of the opening of the second shaped aperture plate 7 or the material 11.

Of the two straight lines, when the dimension of the figure 8 is changed by the shaping deflector 15, that is, when the dimension of the projected figure 12 is changed, the former (x = 0) moves. However, since the current density in the former does not depend on the dimensions of the figure 8 or the projected figure 12, the following explanation will be simplified if the former is regarded as a reference for the X coordinate. Therefore, hereinafter, the former is the reference for the X coordinate, and the latter (x = x _i ) is considered to move with the dimensions of the figure 8 or the projected figure 12.

The measurement of the beam currents I (x _i , y _n ) and I (x _m , y _j ) may be performed together with the measurement of the current density by the current detector 27 periodically as in the past. In such a case, it is not necessary to newly provide time for moving the current detection unit 27 by the material stage 18. Further, the height position of the deflection fulcrum of the electron beam 1 by the shaping deflector 15 at the time of measuring I (x _i , y _n ) and I (x _m , y _j ), the shaping deflector 15 has a two-stage configuration. For example, the height of the blanking aperture plate 25 may be selected. In this case, when the shaping deflector 15 is operated, the electron beam 1 is not deflected to the blanking aperture plate 25, so that I (x _i , y _n ) and I (x _m , y _j ) are accurate. Can be measured. The description so far is the beam current measurement process of the process S1.

Next, in the current density value calculation process of the process S2 in the signal processing device 20, I (x _i , y _n ) to I (x _i−1 , y _n ) are similarly calculated by the technique shown in the prior art. By subtracting, the beam current is obtained for each divided region flowing into a rectangular region (hatched portion in FIG. 4) having a short side x _i −x _i−1 and a long side y _n by dividing the divided region. _i −x _i-1 ) · y _n , the current density in the rectangular region of the short side x _i −x _i-1 and the long side y _n is J _x (x _i ),
J _x (x _i ) = [I (x _i , y _n ) −I (x _i−1 , y _n )] / {(x _i −x _i−1 ) · y _n } is obtained. This is determined for each different x _i . Similar processing is performed by changing the dimension of the projected figure 12 in the y direction to obtain J _y (y _j ).

Subsequently, in the current density distribution function creating step of the process S3 in the calculation / control device 13, J _x (x _i ) and J _y (y _j ) are smoothed by an approximate curve, thereby measuring errors (for example, The error due to the resolution of the command value relating to the dimension of the projected figure 12 is reduced. In this way, approximate functions J _xa (x) and J _ya (y) of the current density distribution are obtained. J _xa (x) and J _ya (y) may be, for example, quadratic functions of x and y, respectively.

Next, in the linear component value calculation step of the straight line / curve component value calculation step of process S4, L _x = J _xa (x _m ) −J _xa (0) (see FIG. 5) and L _y = J _ya (y _n ) −J _ya (0) is obtained. Further, C _x and C _y are also obtained. C _x and C _y are as described below, it is a curve component of each J _xa (x) and J _ya (y).

Subsequently, in the linear component determination step of process S5, it is determined whether | L _xk | ≦ ε and | L _yk | ≦ ε. If it is not determined that | L _xk | ≦ ε and | L _yk | ≦ ε, the process proceeds to step S6, and the beam position adjustment step in step S6 is performed. Here, L _xk and L _yk are L _x and L _y determined respectively for k (≧ 1) times, and ε (> 0) is an allowable value for | L _xk | and | L _yk |. If it is determined that | L _xk | ≦ ε and | L _yk | ≦ ε, the process proceeds to Step 7.

In the beam position adjustment process of process S6, s _xk and s _yk are _changed to s _{xk + 1} = s _xk + Δs _xk and s _{yk + 1} = s _yk + Δs _yk , respectively. Thereafter, the value of k is incremented by 1 (S21), and the processes S1 to S5 are executed again. However, if it is determined that | L _xk | ≦ ε and | L _yk |> ε, or | L _xk |> ε and | L _yk | ≦ ε in the linear component determination step of process S5, the calculation is simplified. Therefore, Δs _xk = 0 or Δs _yk = 0 respectively.

Here, s _xk and s _yk are respectively s _x and s _y when L _xk and L _yk are determined, and s _x and s _y are input to the X-direction deflector and the Y-direction deflector. Deflection signal. If the inputs of the aligner 29 to the X-direction deflector and Y-direction deflector are s _xu = s _x and s _yu = s _y , respectively, the aligner 30 is supplied to the X-direction deflector and the Y-direction deflector. The inputs are s _xl = (r · D _u / D _l ) · s _x and s _yl = (r · D _u / D _l ) · s _y , respectively, based on the relationship described above.

Δs _xk and Δs _yk are obtained from equations (1) and (2) (see FIG. 6). In the equations (1) and (2), L _xk (s _xk ) and L _yk (s _yk ) indicate L _xk and L _yk obtained when the deflection signals are s _xk and s _yk , respectively.

However, L _x0 , L _y0 , s _x0, and s _y0 are L _x , L _y , s _x, and s _y obtained in the past, respectively. Alternatively, set a new appropriate s _x and s _y, these regarded as s _x0 and s _y0, respectively, determine the linear component L _x and L _y running processes S1 to S4, _x0 and their respective L _Consider L _y0 .

If the above processing is _repeated until it is determined that | L _xk | ≦ ε and | L _yk | ≦ ε in the linear component determination step of step S5, the linear component (gradient component) of the current density distribution is removed. In other words, the difference between the maximum value and the minimum value of the current density becomes minimum within the range of 0 ≦ x ≦ x _m and 0 ≦ y ≦ y _n. By such automatic adjustment, the apparatus administrator can maintain good linewidth linearity without having special knowledge about the variable shaped electron beam drawing apparatus.

After the linear component is removed from the current density distribution, the curve components _Cx and _Cy remain. This component is a component that depends on the state of the electron gun, for example, a component that is generated when the electron emission intensity distribution is changed as the emitter is consumed. Therefore, the same component does not decrease unless the setting of the electron gun is changed or the electron gun is replaced.

Accordingly, in the linear component determination step of process S5, after it is determined that | L _xk | ≦ ε and | L _yk | ≦ ε, the process proceeds to process S7. In step S7, it is determined whether or not | C _xk | ≦ η and | C _yk | ≦ η in the curve component determination step. Here, C _xk and C _yk are curve components C _x and C _y determined as the k-th time, and η (> 0) is an allowable value for | C _xk | and | C _yk |. Of C _x and C _y are each J _xa and J _ya, the difference between the maximum value and the minimum value in the range of 0 ≦ x ≦ x _m and 0 ≦ y ≦ y _n, straight-curve of step S4 as described above In the linear component value calculation step of the component value calculation step, it is _obtained together with the linear component values L _xk and L _yk .

If it is determined that | C _xk | ≦ η and | C _yk | ≦ η in the curve component determination step of step S7, the current density unevenness is within the allowable value. In that case, it progresses to process S8. In the adjustment time determination step of process S8, it is determined by referring to the date and time from the clock provided in the arithmetic / control device 13 whether the current date is the adjustment time. If it is determined that the current date and time is the adjustment time, the value of k is incremented by one (S21), and the processes S1 to S5 are executed again. Returning again to step S1, step S1 (beam current measurement step), step S2 (current density value creation step), step S3 (current density distribution function creation step), step S4 (line / curve component value calculation step), step S5 (Linear component determination step) is executed in order.

  If it is determined that the current date / time has not reached the set adjustment time (date / time), time management is performed until the current date / time matches the set date / time. Thereafter, when the current date and time coincides with the set date and time, the value of k is incremented by one (S21), and the process returns to step S1 again, step S1 (beam current measuring step), step S2 (current density value creating step) ), Processing S3 (current density distribution function creating step), processing S4 (straight line / curve component value calculating step), and processing S5 (straight line segment determination step) are executed in this order. The adjustment cycle is, for example, one week to several weeks.

On the other hand, if it is not determined that | C _xk | ≦ η and | C _yk | ≦ η in the curve component determination step of process S7, the process proceeds to process S9. In the display step of process S9, a message is sent to the monitor 32 informing that it is necessary to change or replace the setting of the electron gun. Alternatively, an alarm may be output. Thus, the device user or the administrator can know the necessity of resetting the electron gun or replacing the emitter without having special knowledge about the electron gun. Alternatively, if the apparatus has a function of automatically adjusting the electron gun, if it is determined that | C _xk | ≦ η and | C _yk | ≦ η in the curve component determination step of step S7, The electron gun can be adjusted automatically.

Once the automatic adjustment system is activated, the alignment of the aligners 29 and 30 is automatically executed for a period until a display notifying the setting change or replacement time of the electron gun is displayed.
[Example 2]
In the second embodiment, the configuration of FIG. 1 is used as it is. However, the orientations of the X-direction deflector and the Y-direction deflector of the aligners 29 and 30 are different from those of the first embodiment, and the deflection direction of the electron beam 1 in the first shaping aperture plate 3 is different from that of the aperture plate X and X. Does not match the Y direction.

The operation of the second embodiment is basically the same as that of the first embodiment, but the method for obtaining _{Δs xk} and Δs _yk in the beam position adjustment step (see FIG. 2) in step S6 is different. In the second embodiment, the change amounts ΔL _xk and ΔL _yk of L _xk and L _yk due to the change amounts Δs _xk and Δs _yk of the deflection signal are:

From the formula (3)

Is obtained. However,

It is.

believed to counteract by L _xk and L _yk determined for the k-th, replacing the [Delta] L _xk and [Delta] L _yk to -L _xk and -L _yk, further _{∂L xk / ∂s yk, ∂L xk} / ∂s yk, _{∂L yk} / ∂s _xk , _{∂L yk} / ∂s _yk , _{∂L xk-1} / ∂s _xk-1 , ∂L _xk-1 / ∂s _yk-1 , _{∂L yk-1} / s _{xk- 1} ,
_{Substituting for ∂L yk-1} / ∂s _yk-1 , equation (4) becomes

It becomes.

If Δs _xk and Δs _yk determined by the equation (5) are used instead of Δs _xk and Δs _yk in the process S6 of the first embodiment, as in the first embodiment, | L _xk | ≦ ε and | L _yk | It can be set as ≦ ε. _{Alternatively,} it is possible to reduce the number of processes to be repeated until | L _xk | ≦ ε and | L _yk | ≦ ε.

_{However, ∂L xk-1 / ∂s xk} -1, ∂L xk-1 / ∂s xk-1, ∂L yk-1 / ∂s xk-1, the _{∂L yk-1 / ∂s yk-} 1 When determining, the deflection signals in the X and Y directions are changed separately based on the principle of partial differentiation. That is, the deflection signal in the X direction is changed by Δs _xk-1, and the process of determining the _{∂L xk-1 / ∂s xk-} 1 and _{∂L yk-1 / ∂s xk-} 1, the deflection signal in the Y direction Only Δs _{yk-1 is} changed, and the process of determining ∂L _xk-1 / _∂yk-1 and _{∂L yk-1} / ∂s _yk-1 is executed separately.
[Example 3]
The basic operation is the same as in the first and second embodiments, and the current density distribution created in the current density distribution function creating step in step S3 by a method different from that in the first embodiment in the straight line / curve component value calculating step in step S4. A straight line component value and a curve component value can also be obtained from the function. That is, the variables x and y of J _xa (x) and J _ya (y) are converted into x ′ + (x _m / 2) and y ′ + (y _n / 2), respectively.
K _xa (x ′) = J _xa (x ′ + (x _m / 2)) = a ₀ + a ₁ x ′ + a ₂ x ′ ² +...
And K _ya (y ′) = J _ya (y ′ + (y _n / 2)) = b ₀ + b ₁ y ′ + b ₂ y ′ ² +.
Ask for. Then, the coefficients of the first-order terms of x ′ and y ′ of K _xa (x ′) and K _ya (y ′), that is, a ₁ and b ₁ are set as linear component values L _x and L _y . Further, the coefficients of the quadratic terms of x ′ and y ′ of K _xa (x ′) and K _ya (y ′), that is, a ₂ and b ₂ are set as curve component values C _x and C _y . Alternatively, instead of _obtaining K _xa (x ′) and K _ya (y ′), the positions of x = x _m / 2 and y = y _n / 2 are changed to the origins of x and y, respectively, at the time of processing S3. , Approximate functions J _xa (x) and J _ya (y) may be defined.
[Example 4]
In the above-described embodiment, the case where an electron beam is used as the particle beam is taken as an example. However, the present invention is not limited to this, and an ion beam can be used instead of the electron beam. For example, an ion beam using argon can be used.

  In addition, although the said Example was used using the process, you may replace each said process with a means or an apparatus.

In the present invention, the following adjustment is automatically performed on a charged particle beam drawing apparatus typified by a variable shaped electron beam drawing apparatus.
The current density distribution (current density distribution of the figure 8) of the charged particle beam passing through the opening of the second shaped aperture plate at the height position of the aperture plate is obtained. Then, the position of the charged particle beam with respect to the opening of the first shaping aperture plate is adjusted so that the linear component (gradient component) is removed.

as a result,
The current density uniformity of the figure projected onto the drawing material (projected figure 12) can be improved. Thereby, the line width linearity of the resist pattern is improved.
The apparatus user or administrator can improve and maintain the line width linearity without having special knowledge about the charged particle beam drawing apparatus.

Furthermore,
-When calculating the linear component of the current density distribution, the curve component is also calculated. When the size of the curve component exceeds the permissible range, a message indicating that the charged particle beam source needs to be readjusted or replaced is output.

  Thereby, the current density unevenness remaining after the automatic adjustment is quantified. The user or manager of the apparatus can know the necessity of adjustment or replacement of the charged particle beam source as part of the line width linearity management without having special knowledge about the charged particle beam source.

DESCRIPTION OF SYMBOLS 1 Electron beam 2 1st lens 3 1st shaping | molding aperture plate 4 Light source 5 of 1st light source 5 Image 6 2nd lens 7 2nd shaping | molding aperture plate 9 Reduction lens 10 Objective lens 11 Material 12 Projection figure 13 Control device 14 Storage device 15 Shaping deflector 16 Shaping deflector drive amplifier 17 Objective deflector 18 Material stage 19 Objective deflector drive amplifier 20 Stage drive device 21 Blanker 22 Blanker 23 Blanker drive amplifier 24 Second light source image 25 Blanking Aperture plate 26 Deflection fulcrum 27 Current detector 28 Signal processor 29 Aligner 30 Aligner 31 Aligner drive amplifier 32 Monitor

Claims (3)

A charged particle beam source, a first lens, a first shaping aperture plate, a second lens and a second shaping aperture plate, and the first shaping aperture plate and the second shaping plate. A shaping deflector is provided between the aperture plate and an image of the aperture of the first aperture plate is projected onto the second aperture plate by the second lens and is superimposed on the aperture of the aperture plate. A charged particle beam drawing apparatus for forming a figure with variable dimensions and shape, and projecting the figure on the drawing surface in a reduced scale,
An automatic charged particle beam writing apparatus comprising beam alignment means for adjusting the position of the charged particle beam that irradiates the first shaped aperture plate with respect to the aperture position of the aperture plate before the first shaped aperture plate. In the adjustment method,
A step of measuring a current density distribution of the charged particle beam passing through the opening of the second shaped aperture plate at a height position of the aperture plate, and extracting the gradient component from the current density distribution obtained by the measurement step And the irradiation position of the first shaping aperture plate is adjusted by the beam alignment means so that the gradient component obtained by the measurement step and the extraction step is removed. A method for automatically adjusting a charged particle beam drawing apparatus.   Extracting the curve component from the current density distribution, comparing the magnitude of the curve component obtained by the extraction step with a predetermined value, and an alarm when the magnitude of the curve component exceeds the predetermined value The method for automatically adjusting a charged particle beam drawing apparatus according to claim 1, further comprising the step of: A charged particle beam source, a first lens, a first molded aperture plate, a second lens and a second molded aperture plate, and the first molded aperture plate and the second molded aperture A shaping deflector is provided between the plate and the image of the opening of the first shaping aperture plate is projected onto the second shaping aperture plate by the second lens and superimposed on the aperture of the aperture plate; A charged particle beam drawing apparatus for forming a figure having a variable size and shape, and projecting the figure on a drawing surface in a reduced scale,
In the charged particle beam drawing apparatus provided with beam alignment means for adjusting the position of the charged particle beam that irradiates the first shaping aperture plate with respect to the opening position of the aperture plate in the preceding stage of the first shaping aperture plate,
Means for measuring the current density distribution of the charged particle beam passing through the opening of the second shaped aperture plate at the height position of the aperture plate, and extracting the gradient component from the current density distribution obtained by the measurement means And an extraction unit that adjusts the irradiation position of the first shaping aperture plate by the beam alignment unit so that the gradient component obtained by the measurement unit and the extraction unit is removed. An automatic adjustment system for a charged particle beam lithography system.

Images