JPH03232217A - Exposure condition detecting and investigating method in charged particle exposing device - Google Patents

Abstract

PURPOSE:To set optimum and desired conditions of exposure by a method wherein the information of computed positional relation is compared with the mutual positional relation of the mask pattern formed on a stencil mask, and the percentage of contraction of the image on the surface of sample irradiation or the angle of rotation of the image is calculated. CONSTITUTION:Two mark patterns, which are provided on a stencil mask and their mutual positional relation is known, are projected onto the surface of a sample from a stencil mask part 6 by driving the deflector located on the side of an electron gun, namely, the mask deflector 56b and 57a under the condition wherein, among the deflectors 55 to be used for selection of an aperture pattern, the deflector on the side of sample surface from a stencil mask part 6 are not driven. The relative positional relation of the image of the mark pattern on the surface of the transferred sample and the relative positional relation of the mark pattern on the stencil mask are computed, and the reducing power of the magnetic field lense on the wafer side from the mask and the rotating angle of the image are obtained accurately. Utilizing the above, the desired optimum condition on each member of the device can be set easily by conducting the calibration of the deflector itself in an exposing device and an irradiation optical system.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to a charged particle exposure apparatus, which aims to accurately form a fine pattern on a substrate, and which includes at least an electron current, an irradiation optical system, an incident mask deflector, and a stencil. A charged particle exposure apparatus comprising a mask, a reduction optical system, and a stage, wherein at least two mark patterns are additionally provided on a stencil mask on which a regular pattern group is formed. In the apparatus, a step of activating an incident mask deflector to irradiate each mark pattern of the stencil mask with a charged electron beam emitted from an electron gun, and directing the beam that has passed through the mark pattern to the stage via a reduction optical system. a step of projecting onto the sample irradiation surface; a step of calculating the mutual positional relationship of the images of the respective mark patterns projected onto the sample irradiation surface; The method is comprised of a step of comparing the mutual positional relationships of the mark patterns and calculating the reduction ratio of the image or the rotation angle of the image on the sample irradiation surface.

[Industrial application field]

The present invention relates to a method C2 for detecting and adjusting exposure conditions in a charged particle device for forming a fine pattern on a substrate using an electron beam.

3. Prior Art] In recent years, with the increase in the density of integrated circuits, new exposure methods using electron beams have been studied and are now being used in place of photolithography, which has been the mainstream method for forming fine patterns for many years. It's here.

A conventional electron beam exposure apparatus is a drawing apparatus that uses a variable rectangular beam to deflect an electron beam onto a sample wafer to draw a pattern. This type of device has a pattern generation function that creates a hardware pattern from pattern data, which is software. However, since the pattern is drawn by connecting rectangular shots, the smaller the pattern size, the smaller the unit. There was a problem in that the number of exposure shots per area increased and the throughput decreased. In order to deal with this problem and obtain a realistic throughput even in the exposure of ultra-fine patterns, a block exposure method has been proposed.

Semiconductor devices that require ultra-fine patterns, such as 64M DRAMs, are often fine, but most of the exposed area is a repetition of a certain basic pattern.

If a basic pattern, which is a unit of a repeating pattern, can be generated in one shot regardless of its complexity, it becomes possible to expose such a pattern at a constant throughput regardless of its fineness. Therefore, the block exposure method is a method in which the basic pattern as described above is held on a transmission mask and irradiated with an electron beam to generate the basic pattern in one shot, and then the basic pattern is connected to repeatedly expose the pattern.

An example of such an exposure method is IEEE TRANS, ON
ELECTRON DEVICES vol, ED-
26 (1979) 663, and has a basic structure as shown in FIG.

That is, an electron gun 3a, for example, an irradiation optical system 1 consisting of a first rectangular aperture 2 and a lens 3, and after passing through the irradiation optical system, it is deflected by a pattern selection deflector 4 placed at the image point of the crossover to form a stencil mask. An arbitrary pattern portion 5 on the portion 6 is irradiated. The electron beam whose cross section has been patterned is returned to the optical axis by the convergence effect of the lens 9, and the cross section is further reduced by the reduction lens 14, and then the electron beam is passed through the projection lens 2.
4. The wafer is exposed to light by the deflection system 2L 23. In this method, the electrons deflected from the optical axis are returned to the optical axis only by the converging action of the lens 9, so the electrons travel through different trajectories within the magnetic field lens 9 depending on which pattern is selected. Furthermore, in order to arrange as many patterns as possible on the master, the electron trajectory needs to pass as far away from the optical axis of the lens as possible. At this time, the influence of lens aberration appearing on the transferred image may become large. In order to deal with this problem, the present inventors proposed an electron beam exposure apparatus as shown in FIG.

That is, the electron gun 3a, for example, the irradiation optical system 1 consisting of the first rectangular aperture 2, the second lens 3, the deflector 4, and the second lens 58a, directs the electron beam to the necessary pattern group provided on the stencil portion 6. A mask deflector 56 placed on the incident side to scan and deflect the electron beam to the position of the pattern 7, and a mask deflector 57 placed on the output side to return the electron beam that has passed through the stencil portion 6 to the original optical axis. A deflector 55, for example, a reduction optical system 10 consisting of a second lens 58b, a reduction lens 14, a projection lens 24, a deflector 23, etc., and an irradiation surface on which a substrate such as a wafer is placed and the beam is irradiated thereon are formed. The deflector 55 is driven based on data processing results by an appropriate mask deflector drive device 59.

In such a structure, the electron beam is a nearly parallel beam between the lenses 58a and 58b, and the electron beam is swung above the stencil mask by the open-lobe pattern selection deflectors 56a, 56b, 57a, and 57b, and is deflected below the stencil mask. The mask pattern is selected under the condition that the beam passes through the center of the lenses 58a and 58b by swinging back. An example of a stencil mask is shown in FIG. The portion where the 9 turns are formed is made into a thin film, as shown in the side view. A punching pattern is formed on this using an etching technique. For the mask substrate 6, a semiconductor such as Si, a metal plate, or the like is used. Further, on the stencil mask, there are provided pattern groups in which a plurality of patterns of a plurality of types, each of which is a collection of patterns selectable by the opening pattern selection deflector 55, are assembled, and each set of patterns is a set of patterns on the mask. can be moved near the electron optical axis by an X and Y stage supporting the electron beam. In order to load a mask onto this stage, a sub-chamber for mask loading is provided which can be separated from the column body with a gate valve.

[Problem to be solved by the invention]

In such a block pattern transfer type electron beam exposure apparatus, the reduction optical system 10, which is composed of a reduction lens 14, a projection lens 24, etc., is capable of forming a pattern on a mask by combining conditions such as the lens strength of each lens. It determines the reduction ratio (magnification) and optimal projection conditions for reducing and transferring onto a wafer. Also, in the case of reduction results using magnetic lenses, image rotation is usually involved, but this also depends on the conditions of each lens. It can be adjusted. Therefore, in the process of connecting multiple identical or different patterns while continuously irradiating them to form the required pattern, it is necessary to form each pattern accurately and consecutively. When images of a pattern are formed on each image, the reduction ratio and rotation angle of each image must be the same. Therefore, in order to accurately determine the shot size of the transferred image on the wafer and to improve the shot accuracy, it is necessary to determine the rotation angle with high precision for this reduction ratio as well. Normally, to determine the reduction ratio and rotation angle, a rectangular beam is generated, and the beam size and beam edge direction of the rectangular beam on the wafer are measured using the sample stage length measurement coordinate system. However, the rectangular beam size that can be generated on a wafer is usually 3~
It is less than 4 μm2, and there is a limit to the accuracy in measuring its size and direction because it is affected by beam edge roughness and other factors.

The purpose of the present invention is to more accurately determine the exposure conditions such as the reduction ratio and rotation angle when the pattern on the mask surface is transferred onto the wafer in such an apparatus, and to determine the optimal exposure conditions from the detected exposure conditions. Moreover, it is an object of the present invention to provide a method for adjusting exposure conditions in a charged particle exposure apparatus that can set desired exposure conditions.

[Means to solve the problem]

The electron beam exposure condition adjustment method according to the present invention basically employs the following technical configuration in order to achieve the above object.

In other words, it is a charged particle exposure apparatus consisting of at least an electron gun, an irradiation optical system, an incident mask deflector, a stencil mask, a reduction optical system, and a stage, and at least a stencil mask on which a regular pattern group is formed. In a charged particle exposure apparatus additionally provided with two mark patterns, a step of activating an incident mask deflector to irradiate each mark pattern of the stencil mask with a charged electron beam emitted from an electron gun; a step of projecting the beam through which the mark pattern has passed onto the sample irradiation surface of the stage via a reduction optical system; a step of calculating the mutual positional relationship of the images of the respective mask patterns projected onto the sample irradiation surface; is a step of comparing the positional relationship information calculated in the above process with the mutual positional relationship of the mark patterns formed on the stencil mask to calculate the reduction ratio of the image or the rotation angle of the image on the sample irradiation surface. and a step of calibrating the operating conditions of the reduction optical system from the reduction ratio or rotation angle information obtained in the above step to obtain a predetermined reduction ratio or rotation angle. This is an exposure condition adjustment method.

That is, in the present invention, the opening lever pattern selection deflector 55
Of these, the deflectors located closer to the electron gun than the stencil mask section 6, that is, the incident-side mask deflectors 57a and 56b, are driven under the condition that the deflectors located closer to the sample surface than the stencil mask section 6 are not driven. By doing this, the relative positional relationship between each other on the stencil mask is known2.
The relative positional relationship of the transferred mark pattern images on the sample surface by irradiating the sample surface with two mark patterns,
By calculating the relative positional relationship of the mark patterns on the stencil mask, it becomes possible to accurately determine the reduction ratio and the rotation angle of the image by the magnetic field lens located closer to the wafer than the mask.

Further, the deflector itself and the irradiation optical system in the exposure apparatus can be calibrated using the detected reduction ratio and rotation angle, and the desired optimum conditions for each member of the apparatus can be easily set.

〔Example〕

Conventionally, as described above, it was necessary to adjust the reduction ratio of the reduction lens and the amount of rotation of the image to the designed values before performing electron beam exposure. In the case of variable rectangular beam exposure, the reduction ratio and rotation N(7)M of the reduction lens do not need to be adjusted directly to the reduction lens, just by adjusting the size and orientation of the variable rectangular pattern on the mask. it was good. However, in the block exposure method using a stencil mask, the size of the mask pattern is already determined, so unlike the variable rectangle method, it is necessary to directly correct the reduction ratio and rotation amount for the reduction lens system. be.

Conventionally, one pattern on a mask is irradiated with an electron beam, the image reflected on the upper surface of the sample stage of the stage is compared with a theoretical pattern, and the amount of correction is determined from the difference.

However, as the reduction ratio of the exposure pattern increases and as the shape of the mask pattern becomes more complex, it becomes difficult to make a determination using a direct measurement method, and the measurement error increases.

The present invention was made against this background, and it is possible to accurately and easily determine the reduction ratio and rotation angle of an image even for a fine exposure pattern and a pattern having a complicated mask shape. It can be done.

A specific example of the exposure condition detection method and adjustment method for charged particle exposure according to the present invention C2 will be described below with reference to the drawings.

FIG. 1 is a diagram showing a specific example of an apparatus suitable for implementing the method for detecting and adjusting exposure conditions for charged particle exposure according to the present invention, and explaining the principle thereof.

As mentioned above, in the process of successively shooting a plurality of patterns, the present invention must ensure that the reduction ratio and image rotation angle of each pattern accurately and always show the same value. Calibration is the process of calibrating the lens conditions of the magnetic field lenses of the irradiation optical system 1, the deflector 55, and the reduction optical system 10, the amplitude of deflection during deflection, the amplitude of swing back, etc., so that they are always optimal. It is necessary to. In such charged particle exposure equipment, the relationship between the image size, rotation angle, and current flowing through the magnetic field lens has been clarified to some extent through simulation, but the results of the simulation do not always match the results of the actually manufactured equipment. It doesn't match exactly.

Therefore, it is actually necessary to actually irradiate the electron beam and make measurements.

To this end, in the present invention, at least two mark patterns M l, M z , M 3 . . . as shown in FIG. is stored in an appropriate calculation means. These mark patterns need to be provided within a range where the electron beam can be deflected.

In the second invention, the deflector 55 includes an incident side deflector 56a on the upper surface of the stencil mask section 6;
56b, and its deflector is configured to be driven by a mask deflector driving means 59.

When performing calibration by measuring the reduction rate of the pattern and the rotation angle of the image, at least two of the mark patterns M, M2, M3, etc. of the stencil mask section 6 are used. The measurement is carried out by using the input side deflator 56a and 5'6b. That is, as shown in FIG. 1(A), the charged particle exposure device is operated to emit an electron beam from the electron gun, and the incident side deflectors 56a and 56b are first operated to deflect the lens based on appropriate address information. 58
The electron beam that has passed through a is deflected to irradiate a mark pattern M provided on a part of the stencil mask section 6, and the beam that has passed through this is directed to the stage 1 through a lens 58b.
Mark pattern M1 is placed at points M and I on the sample irradiation surface of No.1.
form an image. In this case, the optical path of the electron beam is as shown by the solid line. Also, at this time, the position information of point M+' is read using known means and recorded in an appropriate memory. Next, input another address information to enter the incident side deflector 56a.

56b is activated to deflect the electron beam that has passed through the lens 58a to irradiate another mark pattern M2 provided in a part of the stencil mask section 6, and the beam that has passed through this deflects the electron beam that has passed through the lens 58a to irradiate the sample on the stage 11 through the lens 58b. An image of the mark pattern M2 is formed at a point M2' on the surface. At this time, the optical path of the electron beam becomes L2 (indicated by a dotted line). Also, in the same way as above, the position information of point MZ' is recorded in an appropriate memory. Each point M in the above
The positional information of 1' and M2' can be obtained, for example, by moving a predetermined reference point provided on the stage to the respective positions of points M+' and M2' and recording the positions as a χ-Y coordinate system. It can be done. Such measurement G can be performed with high precision by using, for example, a laser interferometer.

As is clear from FIG. 1(B), this data is then input to an appropriate arithmetic processing means to calculate the distance Ml' between both points Ml' and M2' and the turning angle θ' from a predetermined reference line. calculate. - Since the distance 2 between the mark patterns M and M2 provided on the cast stencil mask part 6 is known, the distance between them! The reduction ratio of the reduction optical system IO can be easily calculated by comparing . Also, if the turning angle is the same for both data, the turning angle of the reduction optical system 10 can be immediately determined from the value of θ', and the straight-line distance between M and M2 and the straight-line distance between Ml' and M2' It may also be to find the angle between the two. In a specific example of the invention, the distance between the mark patterns M 1 and M z on the mask is
For example 2. Omm and Ueno\-upper image M +
' + M z distance is about 20 μm, which is more accurate than when determining the reduction ratio and rotation angle rather than the size of a single rectangular beam or beam angle direction, and the magnetic field lens is closer to the wafer than the mask. The reduction ratio and rotation angle of the image can be determined.

Next, in the present invention, by the method described above,
Taking advantage of the ability to accurately detect the reduction ratio and rotation angle in the exposure equipment, adjustments can be made to set the desired optimal reduction ratio and rotation angle required for the exposure equipment in the actual pattern manufacturing process. It can be done.

That is, if the reduction ratio and image rotation angle obtained in this way differ from the respective target setting values, at least some or all of the lens conditions of each element constituting the reduction optical system described above should be changed. Calibration can be performed by correcting the value to match the desired setting value.

In a charged particle exposure apparatus such as the present invention, as described above, when a pattern is reduced using an electron lens (magnetic lens), the image rotates as the pattern is reduced. When placing the pattern, it is necessary to check in advance how much image rotation will occur in the reduction optical system and place the pattern at an angle so that it matches. It is also possible to easily and accurately determine the angle. In this case, the stencil mask portion may be rotated by the necessary amount, or the stage itself may be rotated.

Furthermore, by adjusting the amount of current flowing through the electron lens, it is possible to reduce the size of the electron lens so that rotation does not occur.

In other words, the above-mentioned calibration becomes possible by configuring an optical system by arranging a plurality of electron lenses.

That is, the reduction ratio is determined as a combination of the functions of each lens, and if completely opposite currents are applied to two electron lenses, they will be reduced but will not rotate. In other words, the amount of image rotation is generally proportional to the first power of the current flowing through the coil. Or, since the reduction rate is generally proportional to the square of the current value, the current direction C2 is related (
It is determined by determining the current value. In other words, the rotation is determined by the first power of the current value, and the reduction rate is determined by the square term, so by changing the amount of current, it is possible to set conditions such that the reduction rate remains constant but no turning occurs. It becomes possible. For example, if two electron lenses are arranged in series and the current is applied to each lens the same, but the directions are reversed, the image will not rotate (although the reduction ratio will be the square of each current). It is determined as the sum of the values.Also, by varying the current value flowing through each mold lens, it is possible to obtain an arbitrary reduction ratio and rotation angle.

Therefore, it is possible to set the reduction ratio and rotation angle value of the reduction optical system to predetermined values by adjusting the value of the current flowing through each electron lens based on the above-mentioned measurement results.

The reduction ratio used in the present invention is not particularly specified, but is typically about 1/100.

Next, in a charged particle exposure apparatus, when an image is actually formed by irradiating a pattern onto a substrate such as a wafer, the image is formed by focusing on a point χ at a specific position on the stage. In other words, images of all patterns of the stencil mask used need to be formed at the position of point X. If this is out of alignment, it will be impossible to draw a complex pattern in a continuous manner.

Therefore, even if the reduction ratio and rotation angle of the exposure apparatus are set to predetermined optimal conditions according to the method of the present invention described above, when actually printing a pattern onto a wafer, etc., the beam of the stencil mask cannot be used. If the conditions of the beam deflector provided on the emission side are not properly set, the beam will not be transferred to a predetermined position. Therefore, it is necessary to measure in advance whether the irradiation optical system, reduction optical system, and deflection deflector of the apparatus satisfy the optical conditions that meet the above purpose. In other words, in order to make the exposure condition adjustment method according to the present invention effective in the production process, it is necessary to accurately position the wafer at a predetermined position on the wafer, with the reduction ratio and rotation angle set to the optimum values by the method described above. It is preferable to carry out a method of checking whether the image is being adjusted to form an image. An example of the confirmation method will be explained below. That is, as shown in FIG. 2, a stencil mask having mark patterns M, M2, . . . is used as in FIG.
, 56b, and exit side deflectors 57a, 57b, and both of them are operated simultaneously to form a mark pattern M.
The images of L and Mz are alternately projected onto the point The conditions of the deflector 57a57b are adjusted so that the images of both patterns are projected onto the same -X portion.

Specifically, as described in FIG. 1, appropriate address information is input into the mask deflector that activates the incident deflector, and the electron beam is applied to the stencil mask to form one mark pattern M, 4. The electron beam that has been deflected to be irradiated and then passed through the pattern M is driven by the five mask deflector drive means (see FIG. 4), which are similarly input with appropriate address information, on the emission side. The beam is returned to the original optical axis by the deflectors 57a and 57b, and a pattern image is formed at X on the sample irradiation surface of the stage 11 via the lens 58b. The optical path of the electron beam in this case is shown as a solid line L3.

Next, similar operations are performed for another mark pattern M2. The optical path of the electron beam in that case is represented by a dotted line L4.

Next, if the images of both patterns completely overlap on the point Run on optics and deflector to set correct conditions.

As described above, in the present invention, before using the charged particle exposure apparatus to actually form an arbitrary pattern on a substrate such as Ueno, at least two mark patterns are used. Measure in advance at least the reduction ratio of the reduction optical system 10 and the rotation angle of the image, and use the results to calibrate at least the reduction optical system to determine the reduction ratio and rotation angle of the image; The reduction ratio and rotation angle thus obtained can be determined in advance.

An example of the basic procedure of the exposure condition detection and adjustment method of the present invention described above is as follows.

(1) First step: Setting up the system of the charged particle exposure apparatus, (2) Second step (3) Third step (4) Fourth step (5) Fifth step (6) Sixth step ( 7) Seventh step: A process of passing the exposure beam straight through (a process of passing the beam without driving the mask deflector) The beam is deflected by the incident deflector so that the beam hits one of the specific mark patterns on the stencil mask. a step of waving the beam so that it passes through the beam, a step of memorizing the position where the mark pattern by the beam is transferred to the sample surface on the sample stage, and a step of waving the beam so that it passes through a specific other mark pattern as in the third step. Step of swinging the beam; Step of memorizing the position where the beam is transferred onto the sample surface; From the positional information of each mark pattern image obtained in the fourth and sixth steps, the linear distance 2' between both images and a predetermined value are determined. Angle with respect to the reference line (8) 8th process (9) 9th process (10) 1st O process (11) 11th process Step of determining θ', relative position between two mark patterns provided on the stencil mask A step of determining the distance i between both mark patterns found from [and the angle θ with respect to a predetermined reference line] Distance information obtained by each of the seventh and eighth steps above! , l' and angle information θ, θ' to calculate the reduction ratio (j2'#2) and rotary pot (θ' θ). The step of adjusting the reduction optical system or the deflection lens system, and the step of operating the exit-side deflector (57a, 57b) in the exposure device to determine whether each mark pattern is transferred to the same point on the test surface. , If the images are not transferred to the same point, adjust the deflector (57a, 57b) to the B circumference; (12) Twelfth step: Start the exposure operation; Next, the above exposure condition detection/adjustment method according to the present invention; An example of an adjustment method for adjusting the exposure conditions of the reduction optical system in the exposure apparatus to a predetermined value, shown in the 10th step, will be described.

That is, a block pattern transfer type charged particle exposure apparatus as shown in FIG. 1 is provided with a reduction optical system 10 composed of a reduction lens 14 and a projection lens 24 as shown in FIG. 3 or 4. . In such a charged particle exposure apparatus, the cross section of the beam transmitted through the stencil section is reduced by the reduction lens 14, and then the projection lens 24
Reduced electron optical system 1 so that the image is formed on the sample surface by
0 is set. When a certain block pattern is selected, the pattern size on the sample surface depends on the reduction ratio of the reduction lens 14 and the imaging conditions of the projection lens. The reduction ratio can be changed according to a certain predetermined function by changing the magnitude of the current flowing through the reduction lens 14, that is, the lens strength. At this time, as shown in FIG. The transferred image (2) is rotated and the shot direction changes depending on the magnitude of the current flowing through the reduction lens, that is, the magnitude of the lens strength. To adjust the size (reduction ratio) and rotation direction of the transferred image, use the reduction lens 1.
It is known that the lens 4 may be constructed from at least two lenses 14a, 14b, . . . each consisting of an excitation section whose lens strength can be adjusted independently, and the strength of each lens may be appropriately applied. However, in general, when either intensity is changed, the size and rotational direction of the transferred image change in relation to each other, and it is not possible to independently adjust the size and rotational direction of the transferred image. Immediately, when the lens strength is set to a certain value, if the conditions for the reduction ratio and rotation direction of the transferred image deviate from the predetermined values, if the lens strength becomes greater than that value, the reduction ratio will increase and the image will become blurred. rotates in a fixed direction. - As the lens strength is reduced in the traditional way, the reduction ratio also becomes smaller, and the image In shows a deflection rotating in the opposite direction to that described above.

Accordingly, in the present invention, the reduction lens 14 is formed by combining two lenses 14a and 14b each composed of an excitation section whose lens strength can be adjusted independently, as shown in FIG. That is, it is composed of a reduction lens 14b having a first excitation part and a reduction lens 14a having a second excitation part.

The reduction lens 14b having the first excitation part is configured to be controlled by a predetermined function, for example, data DCI, which is configured to mainly change the reduction rate of the transferred image, and the reduction lens 14b has a second excitation part. The reduction lens 14a is configured to be controlled by a predetermined function, such as data Dβ, which is configured to mainly change the direction of rotation of the transferred image. Specifically, for example, the lens 14a is
, 14b, the overall intensity may be changed, and the intensity ratio of the excitation parts of the lenses 14a and 14b may be changed based on the data Dp4. At this time, as shown in FIG.
/l--・Standing ladder 5'-near When +1/g is changed, 5 is the dotted line data 4'D/+~[;β,': As shown, the reduction/circle does not change much, but it rotates. This shows that the angle can change significantly, and on the other hand, if the data r) is changed while keeping the data D/ constant, ζ will rotate as shown by the solid line data D〆1 to [)〆3. Even if there is a change in the angle, the reduction of 7] can be greatly changed.

Assume that there is an initial transfer condition at point Pi c2 in FIG. 9, in which the rotation angle of the image and the reduction rate of the image are taken along the horizontal axis as in FIG. 8. Consider bringing this to the target transfer condition P. First, change the data Dρ and bring the rotation direction of the transferred image to a desired angle. By scanning, the size of the transferred image can be determined.By changing the data D, the size of the transferred image can be determined as transfer line 1"+:
After approaching the size of Pf, change the data Dβ again,
The rotation direction of the transferred image is brought to a desired angle, and the size of the transferred image is determined. By repeating this several times (a finite number of times), the reduction lenses 14a, 14
Conditions b can be set.

At the end of each of the above operations, the reduction ratio and rotation angle of the transferred image at that time are always measured using the method described above, and compared with the desired condition values.

The specific structure and means of the above exposure condition adjustment method are shown below. That is, the reduction optical system is configured to include at least the first and second excitation parts that can change the lens strength independently of each other, and the first excitation part 14b mainly controls the relative excitation strength between the two excitation parts. It is configured to change the reduction ratio of the transferred image by changing the overall lens strength without changing the ratio, and the second excitation (part 6 mainly changes the relative excitation intensity ratio between both excitation parts). The rotation angle of the transferred image is changed so that the rotation angle of the transferred image can be changed, and the actual measurement of the reduction ratio and the rotation angle (based on the information about the difference between 1α and the desired value of 1α) is performed. The first step is to operate the second mEu section to change the intensity ratio (the first step is to change the intensity ratio). Step 2, and the first step
The third step is to change the overall lens strength without changing the relative excitation intensity ratio by operating the excitation fn part of the beam size or h,l! on the sample surface. The adjustment cycle consisting of the fourth step of measuring the 7-tot interval and determining the difference from the predetermined value is carried out once or twice. ji & is configured to be executed repeatedly twice.

Therefore, by carrying out the above steps, it becomes possible to adjust the magnification and rotation direction of the transferred image in bronc exposure with a simple lens configuration and adjustment fence.

(Effects) As described above, the present invention allows the stencil mask to be created with higher precision than the conventional method of determining the size of a single rectangular beam, reduction from the beam 1, edge direction, and rotation angle. It becomes possible to determine the reduction ratio and image rotation angle of the reduction optical system including the fa field lens located closer to the wafer.
By calibrating independently of the incident side deflectors 56a and 56b, the exposure conditions in the reduction optical system can be adjusted accurately and easily.

[Brief explanation of drawings]

FIG. 1(A) is a diagram illustrating a specific example of a charged particle exposure apparatus used in the present invention and its principle. FIG. 1(B) is a diagram showing the positional relationship between a mark pattern and a reduced image of the mark pattern. FIG. 2 is a diagram showing an example of a method for checking the exposure situation after executing the exposure condition detection and adjustment method according to the present invention. FIG. 3 is a schematic diagram showing an example of a conventional charged particle exposure apparatus. FIG. 4 is a schematic diagram showing another example of a conventional charged particle exposure apparatus. FIG. 5 is a plan view showing one specific example of a stencil mask. FIG. 6 is a diagram showing the relationship between the transfer image reduction ratio and the rotation angle depending on the magnitude of the current flowing through the reduction lens (lens strength) in a charged particle exposure apparatus. FIG. 7 is a diagram showing an example of the configuration of a reduction lens, FIG. 8 is a diagram showing the relationship between the reduction ratio of a transferred image and a change in rotation angle when the lens strength is changed, and FIG. 9 is a diagram showing a transferred image in the present invention. The figure which shows the procedure of adjusting the reduction rate and rotation angle of. l... Irradiation optical system, 2... First rectangular aperture, 3... Lens, 3a... Electron gun, 4...
... Deflector for aperture selection - 6 ... Stencil mask part, 7 ... Basic pattern, 8 ... Aperture for variable rectangle, IO ... - Reduction optical system, 11 ... Stage, 1
2... Wafer (substrate), 13... Sample irradiation surface, 1
4... Reduction lens, 23... Deflector (deflector), 24... Projection lens, 55... Deflector (deflector), 56a, 56b - One incident side deflector - 57a, 57b
... Output side deflector 58a, 58b... Lens, 59... Mask deflector driving means, 14a...
2nd excitation part, 14b... 1st excitation part.

Claims (1)

[Scope of Claims] 1. A charged particle exposure apparatus comprising at least a charged electron current, an irradiation optical system, an incident mask deflector, a stencil mask, a reduction optical system, and a stage, wherein a regular pattern group is formed. At least 2 stencil masks
In a charged particle exposure apparatus in which mark patterns are additionally provided, a step of activating an incident mask deflector to irradiate each mark pattern of the stencil mask with a charged electron beam emitted from an electron gun; a step of projecting the beam that has passed through a reduction optical system onto the sample irradiation surface of the stage; a step of calculating the mutual positional relationship of the images of the respective mark patterns projected onto the sample irradiation surface; calculation by the above steps; The positional relationship information obtained by the stencil mask is compared with the mutual positional relationship of the mark patterns formed on the stencil mask, and the reduction ratio of the image or the rotation angle of the image by the valence electron optical system from the stencil mask to the sample surface is calculated. 1. A method for detecting exposure conditions in a charged particle exposure apparatus, comprising the steps of: calculating. 2. A charged particle exposure apparatus consisting of an electron stream, an irradiation optical system, an incident mask deflector, a stencil mask, a reduction optical system, and a stage, in which at least two of the stencil masks on which a regular pattern group is formed are used. in a charged particle exposure apparatus additionally provided with a mark pattern, a step of irradiating each mark pattern of the stencil mask with a charged electron beam emitted from an electron gun by activating an incident mask deflector; a step of projecting the passed beam onto the sample irradiation surface of the stage via a reduction optical system; a step of calculating the mutual positional relationship of the images of the respective mark patterns projected onto the sample irradiation surface; Compare the positional relationship information formed on the stencil mask with the mutual positional relationship of the mark patterns formed on the stencil mask to calculate the image reduction rate or image rotation angle by the valence electron optical system from the stencil mask to the sample surface. and a step of adjusting the operating conditions of the reduction optical system from the reduction ratio or rotation angle information obtained in the above step to obtain a predetermined reduction ratio or rotation angle. A method for adjusting exposure conditions in a charged particle exposure device. 3. The reduction optical system is configured to include at least a first and a second excitation part that can change the lens strength independently of each other, and the first excitation part mainly controls the relative excitation intensity ratio between the two excitation parts. The second excitation section is configured so that the relative excitation intensity ratio between the two excitation sections can be changed, and the reduction ratio and the rotation A first step of changing the relative excitation intensity ratio by operating the second excitation unit based on information regarding the difference between the actual measured value and the desired value regarding the angle, a rotation of the image on the sample surface; a second step of measuring the angle and determining the difference from a predetermined value of the turning angle; and a third step of operating the first excitation unit to change the overall lens strength without changing the relative excitation intensity ratio. A fourth step of measuring the beam size or shot interval on the sample surface and determining the difference between the beam size or the shot interval and a predetermined value is repeated once or multiple times. A method for adjusting exposure conditions in a charged particle exposure apparatus according to claim 2.