JP2000294484A - Method and device for exposing semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make allowable adhesion of such dust that deteriorates the flatness of samples placed on a stage. SOLUTION: In a method for exposing semiconductor, the semiconductor is exposed while the height of the exposing position is controlled by measuring the surface height of a flat sample 1 fixed on the surface of a stage 2. At the time of successively exposing a plurality of flat samples 1, a measuring step of measuring the surface heights of the samples by changing the measuring position 5 for at least part of each sample; a distribution calculating step of calculating the surface height distribution of the stage 2 from the height measured results at measuring positions, the number of which is larger than that of the height measuring positions for one flat sample by accumulating surface measured results of a plurality of samples 1 at different positions; and a height distribution managing process of managing the height distribution of the samples based on the surface height distribution of the stage 2; are performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor exposure apparatus including an optical exposure apparatus such as a stepper and a charged particle beam exposure apparatus such as an electron beam exposure apparatus, and more particularly to a semiconductor wafer (hereinafter simply referred to as a wafer). The present invention relates to a semiconductor exposure apparatus that measures the height of a surface when a planar sample is fixed on a stage and feeds back the measurement result.

2. Description of the Related Art In recent years, semiconductor technology has been increasingly developed, and the degree of integration and functions of semiconductor integrated circuits (ICs) have been improved, and computers,
Its role is expected as a core technology for technological progress across a wide range of industries such as communication machine control. IC is 3 years from 2 years
It achieves four times higher integration per year. For example, dynamic random access memory (DRAM: DynamicRadar)
ndom Access Memory), the storage capacity is 1
M, 4M, 16M, 256M, and 1G. Such high integration of ICs largely depends on the progress of fine processing technology in semiconductor manufacturing technology, particularly, exposure technology. The present invention relates to a semiconductor exposure apparatus.

It is expected that the light exposure technology used in steppers and the like conventionally used is limited, and charged particle beam exposure technology such as electron beam exposure technology will take the next generation of fine processing in place of light exposure technology. This is a highly promising technology. In the following description, an electron beam exposure apparatus will be described as an example, but the present invention is not limited to this.
Any semiconductor exposure apparatus is applicable.

[0004]

2. Description of the Related Art Electron beam exposure systems include a variable rectangular exposure system, a block exposure system, and a multi-beam exposure system. Here, the block exposure method will be described as an example, but the present invention is not limited to this. The block exposure method is a method in which a pattern serving as a unit of a repeated figure is held on a transmission mask, an electron beam is transmitted through the mask to generate a unit pattern at a time, and the pattern is connected to expose the figure repeatedly.

FIG. 1 is a diagram showing the configuration of a beam irradiation system in a block exposure type electron beam exposure apparatus. In FIG. 1, reference numeral 11 denotes an electron gun that generates an electron beam, 12 denotes a first converging lens that converts the electron beam from the electron gun 11 into a parallel beam, and 13 denotes a shaped parallel beam that passes therethrough. Aperture, 14 a second converging lens for narrowing the shaped beam, 15 a shaping deflector, 16 a first mask deflector, 17 a dynamic correction of astigmatism due to the mask. 18 is the second deflector.
19 is a mask converging coil, and 20 is a mask converging coil.
Denotes a first shaping lens, 21 denotes a block mask moved by the stage 21A, 22 denotes a second shaping lens, 23 denotes a third mask deflector, and 24 controls on / off of a beam. A blanking deflector, 25 a fourth Max deflector, 26 a third lens, 27 a circular aperture, 28 a reduction lens, 29 a dynamic focus coil, and 30 a projection lens. , 31 indicate an electromagnetic main deflector, 32 indicates an electrostatic sub deflector,
Reference numeral 33 denotes a backscattered electron detector for detecting backscattered electrons of the electron beam applied to the sample 1 and outputting a backscattered electron signal. The sample (wafer) 1 on which the electron beam 10 is mounted on the stage 2 by the projection lens 30 Converges. The stage moves the wafer 1 two-dimensionally in a plane perpendicular to the electron beam 10. The above parts are accommodated in a housing called an electron optical column (column), and the inside of the column is evacuated to perform exposure. The electron beam exposure apparatus further has an exposure control unit for controlling each part of the column so as to expose a desired pattern, but the description is omitted here.

As described above, the shaped electron beam is converged on the wafer 1 by the projection lens 30 and is moved to a desired position on the wafer 1 by the deflecting means including the main deflector 31 and the sub deflector 32. It is deflected and exposed. In this case, the surface of the wafer 1 needs to be at a predetermined height. FIG. 2 is a diagram illustrating a problem when the height position of the surface of the wafer 1 is shifted. When the surface of the wafer 1 is at the regular height, the electron beam 10 is focused on the surface as shown in FIG. At this time, the converged spot is a spot having a minimum diameter D that is not completely converged to one point due to diffraction or the like. This minimum diameter determines the resolution. Wafer 1 'with shifted surface height
In the case of (1), the beam diameter on the wafer surface becomes D 'as shown in FIG. D ′ is approximately proportional to the deviation ΔT and the convergence angle of the beam, respectively. In the case of an electron beam, the influence of diffraction is small and the minimum diameter of the spot can be made very small even if the convergence angle of the beam converged at one point is relatively small. On the other hand, in the case of an optical exposure apparatus, the beam convergence angle has become very large in recent years because the beam convergence angle directly affects the minimum diameter of the spot. Therefore, the influence of the shift in the height position of the surface is larger in the optical exposure apparatus than in the electron beam exposure apparatus.

In the electron beam exposure apparatus, a deflection means is realized by combining a main deflector 31 and a sub deflector 32 in order to deflect a wide range at a high speed. As shown in FIG. 1, the main deflector 31 is configured by combining four electromagnetic deflectors in four stages. By turning back the electron beam once deflected, the electron beam is applied to the wafer regardless of the deflection amount. It is designed to be incident vertically. As the sub deflector 32, an electrostatic deflector having a high response speed is used. As shown in FIG. 2B, the electron beam 10 deflected by the sub deflector 32 enters the wafer 1 at an angle corresponding to the amount of deflection. Therefore, in the case of the wafer 1 'whose height position is shifted, the exposure position is shifted by ΔP as shown in the figure, thereby deteriorating the exposure pattern. In the case of an optical exposure apparatus, the use of a telecentric optical system prevents such a shift of the exposure position even if the height position of the surface of the wafer shifts.

In any case, it is necessary to accurately align the surface position of the wafer with the exposure surface, or to perform correction according to the deviation. Therefore, in the optical exposure apparatus, the exposure is performed after the stage is automatically moved up and down so that the wafer surface becomes the focal plane before the exposure of each chip (die) by providing an auto-focus mechanism. . In electron beam exposure equipment,
Before exposure, the height distribution at a plurality of points on the wafer is measured and stored, and correction is performed according to the height of the position during exposure. The correction can be performed by changing the height of the stage. However, since the response speed of the stage movement is slow, when the height deviation is small, the defocus of (1) in FIG. The adjustment of the dynamic focus coil 29 provided for the purpose of correcting the Coulomb interaction is performed, and the shift of the exposure position in FIG. 2B is performed by adjusting the deflection amount of the sub deflector.

In the manufacturing process of a semiconductor device, a resist is applied on a wafer, and the wafer is fixed on a stage to perform exposure. In the case of an optical exposure apparatus, vacuum suction is used to fix the wafer to the stage.However, in an electron beam exposure apparatus, vacuum suction cannot be used because the inside of the column is evacuated, and electrostatic suction is used. You. When measuring the height position of the wafer surface, fix the wafer on the stage,
Measure the position of the surface.

As a method of measuring the height position of the surface of the wafer, there are a method using an optical height measuring device similar to the autofocus mechanism of the optical exposure apparatus, and a method using an electron beam. The optical height measuring device focuses the light beam on the wafer surface and measures the convergence of the spot on the wafer surface by detecting the reflected light, or irradiates the light beam obliquely to the surface, There is a method of measuring the amount of deviation of the reflected light beam. In addition, as a method of using an electron beam, a mark is created in advance on the surface of a wafer with a substance or structure having a different electron reflectivity, and the reflected electron is detected when the mark is scanned by the electron beam, and the reflected electron is detected. Searching for the state where the signal changes most rapidly, or operating the mark so that the electron beam is incident on the wafer at an incident angle, and measuring the deviation from the reference position from the amount of deflection when the mark is detected There are methods.

The stage is processed so that the surface has a high degree of flatness, and the change in the height position due to the movement of the stage is small. On the other hand, the wafer is also processed to have a high degree of flatness, and when fixed to the stage, has a surface height according to the height distribution of the surface of the stage. However, since it is inevitable that the thickness of the wafer varies to some extent, it is necessary to measure the height at least once for each wafer. In practice, the height of a plurality of predetermined points is measured. . That is, conventionally, the height at the same position was measured. Also, when it is necessary to know the height position with higher accuracy, the height distribution of the surface position and the change in height due to movement are measured and stored in advance, and the value is read and corrected according to the exposure position. are doing. in any case,
It can be said that the height distribution of the surface of the wafer when fixed to the stage was obtained by relying on the flatness of the stage (or the repeatability of the measured height position) and the flatness of the wafer.

[0012]

The wafer exposure process is performed in a very clean clean room. However, there is a case where dust or the like is attached to the wafer supplied to the exposure apparatus, and the dust is attached to the exposure apparatus. In particular, if a wafer having dust adhered to the back surface is mounted on the stage and fixed, the dust may adhere to the surface of the stage as it is even after the wafer is collected. FIG. 3 is a diagram illustrating a state where dust 9 adheres between the wafer 1 and the stage 2. Actually, the dust 9 is very fine, but is greatly illustrated here for the sake of explanation. In the state where there is no dust 9, as shown in FIG. 3A, the surface of the wafer 1 has a good flatness along the surface of the flat stage 2, but in the state where the dust 9 is in between. As shown in FIG. 3 (2), the surface of the wafer 1 has a high level of dust and a reduced flatness. FIG. 4 is a diagram showing a height distribution in a state as shown in FIG. 3 (2). As shown, the height of a part with dust 9 is higher than the other parts,
Contour lines having a height distribution are generated as if there is a mountain having the position of the dust 9 as a vertex.

In practice, there are various types, shapes, and sizes of dust, which randomly adhere to the surface of the stage, and the height distribution becomes very complicated. As described above, conventionally, such adhesion of dust has not been assumed, and a change in the height distribution due to such adhesion of dust is measured simply by measuring the height of a plurality of points on the conventional wafer. could not. For this reason, there has been a problem that the convergence state changes depending on the exposure position or the exposure position shifts to deteriorate the exposure pattern. Such deterioration of the exposure pattern due to the adhesion of dust is only known after developing the exposed resist, and a situation may occur in which all the exposure patterns of the wafers processed up to that time become defective.

Therefore, it is necessary to measure the change in the height distribution on the wafer surface due to the adhesion of dust to the stage surface, and to control the dust adhesion state. For example, when the flatness deteriorates to a certain degree or more, management such as cleaning the surface of the stage, correcting a principal point shift for each exposure position according to the height distribution of the wafer surface, and correcting the exposure position is performed. is necessary. However, simply measuring the heights of a plurality of points on a conventional wafer cannot sufficiently measure the state of adhesion of dust, and such management cannot be performed.

Therefore, it is conceivable to increase the number of positions where the height of the wafer is measured before exposure and measure the height of the entire surface of the wafer to obtain the height distribution of the wafer surface in more detail. However, when measuring the height position of the surface of the wafer fixed to the stage, increasing the number of measurement points causes a problem that the time required for the measurement increases and the throughput decreases.

SUMMARY OF THE INVENTION An object of the present invention is to solve such a problem and to obtain the height distribution of the wafer surface in more detail without lowering the throughput, and to control the adhesion of dust to the stage surface. An object of the present invention is to realize a semiconductor exposure method and an exposure apparatus.

[0017]

In order to achieve the above object, in the semiconductor exposure method and the exposure apparatus of the present invention, the number of height measurement points of one sample (wafer) is small as before, but the number of measurement points is small. If the results of measuring the heights of a plurality of samples are combined, the height over the entire surface of the sample is measured.

That is, the semiconductor exposure method of the present invention measures the height of the surface of a planar sample fixed on the surface of a stage, controls the height of an exposure position, and performs exposure. When sequentially exposing a plurality of the planar samples, at least a part for each planar sample, a measurement step of performing height measurement at a different position, and the height measurement results at different positions of the plurality of planar samples A distribution calculating step of accumulating and calculating a height distribution of the surface of the stage from height measurement results at a number of measurement positions greater than the number of height measurement positions of one planar sample; And a height distribution management step of performing management based on the height distribution.

Further, the semiconductor exposure apparatus of the present invention comprises an exposure means, a stage for fixing the planar sample, a height measuring means for measuring the height of the surface of the planar sample fixed to the stage, In a semiconductor exposure apparatus including a correction unit that feeds back a height measurement result of a sample surface to an exposure unit or a stage, when sequentially exposing a plurality of planar samples, the height measurement unit includes at least each planar sample. Some measure the height at different positions, accumulate the height measurement results at different positions on multiple planar samples, and measure more than the number of height measurement positions on one planar sample And a height distribution managing means for calculating a height distribution of the surface of the stage from a height measurement result at the position and performing management based on the height distribution of the surface of the stage.

According to the present invention, since the number of height measurement points on one sample is small as before, the throughput does not decrease.
Since the measurement points are different, the height of the entire surface of the sample can be measured by combining the results of measuring the heights of a plurality of samples, and the adhesion of dust to the surface of the stage can be managed. In managing height distribution,
It is determined whether the height distribution of the surface of the stage is within a predetermined flatness allowable range. If the height distribution is not within the allowable range, a predetermined recovery process such as cleaning of the stage surface is instructed.

In the management based on the height distribution, for example, the height of the stage, the focal point, and the exposure position are adjusted according to the height distribution of the surface of the stage. It is desirable to calculate the height distribution of the surface of the stage after normalizing the height measurement result with the measurement result of the common reference position with at least a part of the measurement position as the common reference position.

The measurement is repeatedly performed at the same height measurement position with a predetermined number of units at which the height measurement position over substantially the entire surface of the planar sample is obtained as one unit, and the previous measurement result is sequentially updated with the new measurement result. Alternatively, the height distribution of the surface of the stage is calculated based on the measurement result for each unit.

[0023]

FIG. 5 is a block diagram showing a configuration of an electron beam exposure apparatus according to an embodiment of the present invention. Column 1
Numeral 0 denotes a portion for accommodating the beam irradiation system shown in FIG. 1. A part thereof is omitted, and convergent lenses, deflectors for mask shaping, and the like are collectively indicated by reference numerals 51 to 54. As described with reference to FIG. 1, the electron beam emitted from the electron gun 11 is shaped by the lens systems 51 to 53 and the deflectors 54 and 24, and is controlled on and off by the deflector 24. The shaped electron beam is applied to the wafer 1 by the main deflector 31, the sub-deflection 32, and the projection lens 30.
It is converged (imaged) at the upper deflection position. The dynamic focus coil 29 adjusts the image forming position of the electron beam. Reference numeral 56 denotes a backscattered electron detector for detecting backscattered electrons of the electron beam applied to the wafer 1,
An optical height measuring device 57 optically measures the height of the surface of the wafer 1. Reference numeral 3 denotes a stage moving mechanism for moving the stage 2, and reference numeral 58 denotes a loader wafer box for accommodating a wafer supplied and collected for exposure, and a loader wafer box 58 provided by a loader mechanism (not shown). Is placed on the stage 2, and the exposed wafer is returned from the stage 2 into the loader wafer box 58. When transferring the wafer, the stage 2 moves to the left end of the stage moving mechanism 3.

Reference numerals 61 to 72 are portions for generating a signal for controlling each section of the column 10 from pattern data indicating a pattern to be exposed, and a CPU for performing overall control.
61, a magnetic disk 63 storing pattern data indicating a pattern to be exposed, a pattern data memory 64 for expanding pattern data of a portion to be exposed, and an interface circuit 65 for outputting a control signal and inputting a detection signal. They are connected by a bus 62. The data developed in the pattern data memory 64 is sequentially read out and supplied to the control circuit of each unit. The on / off control circuit 66 controls the on / off deflector 24 so that the beam is turned off until the electron beam is settled at the deflection position, and the beam is turned on for a predetermined time after the settling. The pattern selection circuit 67 controls the deflector 54 so as to select a block mask to be exposed.
The dynamic focus control circuit 68 controls the dynamic focus coil 29 so as to correct the focal position shift due to Coulomb interaction. The deflection control circuit 69 controls the main deflector 31 and the sub deflector 32 so as to irradiate the shaped electron beam to a predetermined position. The stage 70 controls the stage moving mechanism 3. The output of the backscattered electron detector 56 is processed by a backscattered electron detection circuit 71. Signals from the dynamic focus control circuit 68 and the deflection control circuit 69 are input to the backscattered electron detection circuit 71, and the position of a mark on the wafer is detected. These detection results are sent to the CP via the interface circuit 65.
It is sent to U61. The output of the optical height measuring device 57 is processed by the surface height detecting circuit 72 and sent to the CPU 61 via the interface circuit 65. Each control circuit is connected to the CPU via the interface circuit 65.
61, but is not shown here.

The above configuration is the same in the conventional electron beam exposure apparatus, and further description is omitted. FIG.
FIG. 3 is a diagram for explaining a measurement principle of the optical height measuring device 57, and is a diagram for explaining a system called a so-called astigmatism method. A half mirror is provided between the lenses 41 and 42 to guide the light beam from the light source (laser) into the optical path,
1 and converge on the surface of the wafer 1. This light beam is applied to the surface of the wafer 1 in the form of a spot when the focus is coincident, and the reflected light is emitted from the spot on the surface of the wafer 1. This reflected light is transmitted through the lens 41
And 42, and converges to the point P. Since the cylindrical lens 43 is provided on the way, the light beam converges to the point Q only in the direction having the power of the cylindrical lens, and converges to the point P in the direction perpendicular thereto. Therefore, the light beam changes as shown in the figure, and its cross section becomes circular at an intermediate point, and becomes elliptical before and after it in different long axis directions. At this intermediate point, a four-division light receiving element 44 as shown is arranged.

When the focus is deviated, the light beam reflected on the surface of the wafer 1 is output from a spot located at a position deviated from the surface of the wafer 1, and the light beams are converged by the lenses 41 and 42 and the cylindrical lens 43. The position also shifts, and the light beam on the four-divided light receiving element 44 becomes elliptical as shown by the dotted line. The direction of the major axis of the ellipse differs depending on which of the focal positions is shifted.
After calculating the sum of the outputs of the elements facing each other, the differential amplifier 45 calculates the AF signals as two sets of difference signals.
The signal changes as shown in FIG. 6 (2) according to the focal position.

If it is within the range indicated by R in FIG. 6 (2), it is possible to uniquely determine the focal point displacement from the AF signal. Note that the entire optical height measuring device 57 or the lens 41 is movably supported by a voice coil, feedback control is performed so that the focal point is always on the surface of the wafer 1, and a signal of the voice coil at that time is detected. Alternatively, the shift of the focal position may be detected.

Although the astigmatism method has been described as an example of the optical height measuring device, the surface is irradiated with a light beam obliquely.
There are various other methods such as a method of measuring the amount of deviation of the reflected light beam. Alternatively, the mark formed on the wafer 1 may be scanned with an electron beam, and the changed electrons at that time may be detected by the reflected electron detector 56 to measure the height position of the wafer surface.

FIG. 7 is a view for explaining the height measuring points in the first embodiment of the present invention. As shown in the figure, 25 chips (dies) are formed on one wafer 1, and when exposing one wafer, the heights of the five chip portions indicated by oblique lines in the figure are changed. The positions of the chips to be measured are sequentially changed as shown in (1) to (5). The part to be measured may be inside the chip or a part adjacent to the chip. As shown in the figure, the positions of the chips whose heights are measured are different for all five wafers, and when the heights are measured for the five wafers, the height measurement is performed at all the chip positions. Conventionally, the height of one or a plurality of predetermined chips has been measured.

When the measurement results of each wafer are stored and the measurement results of five wafers are combined, a height distribution over the entire surface of the wafer is obtained. As described above, since the wafer thickness is inevitable to some extent, the height distribution (flat data) of the stage is obtained after correcting with the separately measured wafer thickness.
In this way, a flat distribution over the entire surface of the stage is obtained, so that if a certain location is higher than other locations, it can be determined that dust has adhered to that location.

FIG. 8 is a flowchart showing a process for obtaining a flat distribution in the first embodiment. Here, the measurement position is determined according to the order within one unit so that when one unit of wafer is measured with a certain number N as one unit, a flat distribution over the entire surface of the stage is obtained. Step 101
Then, the remainder is obtained by dividing the wafer order by N. Since this remainder indicates the order within one unit, step 10
In 2, the measurement is performed at the measurement position corresponding to the remainder, and the measurement value is stored. In step 103, flatness data is generated and stored by correcting the separately measured wafer thickness. The mean value of the remaining measured values is calculated except for greatly different values among the measured values, and this average value is calculated. In step 104, a flat distribution is generated by combining the flat data calculated in step 103 with the previous flat data.If one unit of measurement has been completed, the previously measured flatness is calculated. Although the data remains, it is rewritten with the newly measured flat data.In step 105, it is determined whether or not the flat distribution generated in step 104 is within a predetermined allowable range. If the value exceeds the allowable range, the process proceeds to step 106, in which the cleaning of the stage surface is instructed, and the process ends. After cleaning of the surface is completed, performs the same processing from step 101 to clear the flattened data.

The flat data may be cleared each time a unit of wafer is measured. When the allowable range of the flat data is reduced, the flatness of the stage is maintained satisfactorily, but the stage needs to be cleaned frequently, which causes a problem that the throughput is reduced accordingly. Therefore, if the degree of flatness degradation is within a certain range, the distribution of the wafer height is calculated based on the flatness distribution,
The focus and the deflection position are corrected according to the height at the exposure position. This allows you to set a large tolerance range,
Eliminates the need for frequent cleaning. FIG. 9 is a flowchart showing an exposure process when the focus and the deflection position are corrected according to the height distribution calculated based on the flat distribution. The correction based on the height of the wafer surface may be performed for each chip. However, if the inside of the chip is divided into a plurality of regions, and the processing is performed for each region, more precise correction can be performed.

In step 201, the stage is moved to move the exposure position to the irradiation range of the electron beam. In step 202, the height of the exposure position is calculated from the flat distribution and the measured height. As described above, since the flat data is updated with the measurement result, the same height is calculated for the position where the height is measured. In step 203, correction data of the focal point and the deflection position is generated according to the calculated height. Here, the focus correction is performed by a dynamic focus coil that corrects the Coulomb interaction, and the dynamic focus control circuit 68 adds the correction amount.
To generate the correction data to be output. The deflection position is corrected by the sub deflector, and the deflection amount for the correction is added to the deflection position by the sub deflector to generate sub deflection data, which is output to the deflection control circuit 69. In step 204, exposure is performed based on the corrected data. In step 205,
It is determined whether all exposures have been completed, and steps 201 to 205 are repeated until all exposures have been completed.

In the first embodiment, the height of the wafer surface is measured at different positions for each wafer, and the measured values are corrected based on the separately measured wafer thickness and the wafer thickness calculated from the measured values to obtain flat data. In the second embodiment, at least one common measurement position is set for each wafer, and the measured values for each wafer are normalized based on the measurement result at the common position to generate flat data.

FIG. 10 is a view for explaining the height measuring points in the second embodiment of the present invention. As shown, 37 chips (dies) are formed on one wafer 1, and when exposing one wafer, the heights of the 7 chip portions indicated by oblique lines in the figure are changed. The positions of the chips to be measured are sequentially changed as shown in (1) to (6). As shown in the figure, the positions of the chips whose heights are measured are all different for the six wafers. When the heights are measured for the six wafers, the height measurement is performed at all the chip positions.

FIG. 11 is a flowchart showing a process for obtaining a height distribution in the second embodiment. Step 30
In step 1, similarly to the first embodiment, the remainder is obtained by dividing the order of wafers by N. Since this remainder indicates the order within one unit, in step 302, measurement is performed at the measurement position corresponding to the remainder, and the measured value is stored. At this time, as shown in FIG. 10, one center is set as a common reference position, and the height at this position is measured in all measurements. Other measurement positions are
Everything is different for each wafer. In step 303, the difference from the first measurement value at the reference position is calculated, and in step 304, other measurement position values are corrected by the difference from the first measurement value at the reference position to generate flat data. Steps 305 and thereafter are the same as in the first embodiment, and generate a flat distribution.

FIG. 12 is a flowchart showing a process for correcting the exposure process using the flat distribution obtained as described above. In step 401, the wafer is moved to the exposure position. In step 402, it is determined whether the height of the wafer to be exposed at that position has been measured. If the height has been measured, the height data is stored. If height measurement has not been performed at that position, in step 403,
The height at that position is calculated from the height of the common reference position measured on the wafer and the flat distribution. In step 404,
The stage is moved up and down according to the height at that position to adjust the surface of the wafer to the exposure position, and exposure processing is performed in step 405.

[0038]

As described above, according to the present invention,
Since the height measurement position of one sample is one place or a small number of places as in the past, the throughput does not decrease, and in order to change the measurement position for each sample, it is necessary to measure a plurality of samples. Data on the flatness over the entire surface of the sample can be obtained, and it becomes possible to detect and manage the attachment of dust to the stage.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration example of a beam irradiation system of an electron beam exposure apparatus.

FIG. 2 is a diagram for explaining an influence when a surface position of a sample (wafer) is shifted.

FIG. 3 is a diagram illustrating a problem when dust is present between a stage and a sample.

FIG. 4 is a diagram illustrating an example of a height distribution when dust is present between a stage and a sample.

FIG. 5 is a diagram illustrating a configuration of an electron beam exposure apparatus according to an embodiment.

FIG. 6 is a diagram illustrating the principle of an optical height detector used in the embodiment.

FIG. 7 is a diagram showing a change in a height measurement position in the first embodiment of the present invention.

FIG. 8 is a flowchart illustrating height measurement and flat distribution calculation processing according to the first embodiment.

FIG. 9 is a flowchart illustrating a process in a case where exposure is performed by correcting the height of a sample in the first embodiment.

FIG. 10 is a diagram showing a change in a height measurement position in the second embodiment of the present invention.

FIG. 11 is a flowchart illustrating height measurement and flat distribution calculation processing according to the second embodiment.

FIG. 12 is a flowchart showing a process in a case where exposure is performed by correcting the height of a sample in the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Sample (wafer) 2 ... Stage 10 ... Column of electron beam exposure apparatus 56 ... Backscattered electron detector 57 ... Optical height detector

Claims (16)

[Claims] 1. A semiconductor exposure method for measuring the height of the surface of a planar sample fixed to the surface of a stage, controlling the height of an exposure position, and performing exposure, comprising the steps of: When sequentially exposing, at least a part of the planar sample is subjected to a height measurement at a different position, and a plurality of the planar samples are accumulated at different positions to collect a height measurement result. A distribution calculation step of calculating a height distribution of the surface of the stage from height measurement results at a number of measurement positions greater than the number of height measurement positions of the planar sample, and a height distribution of the surface of the stage. A height distribution management step of performing management based on the semiconductor exposure method. 2. The semiconductor exposure method according to claim 1, wherein in the height distribution managing step, it is determined whether a height distribution of a surface of the stage is within a predetermined flatness tolerance. A semiconductor exposure method for performing a predetermined recovery process when the value is not within the allowable range. 3. The semiconductor exposure method according to claim 1, wherein in the height distribution managing step, the height of the stage is adjusted according to a height distribution of a surface of the stage. 4. The semiconductor exposure method according to claim 1, wherein in the height distribution management step, a focus of exposure is adjusted according to a height distribution on a surface of the stage. 5. The semiconductor exposure method according to claim 1, wherein, in the height distribution management step, an exposure position is adjusted according to a height distribution of a surface of the stage. 6. The semiconductor exposure method according to claim 1, wherein at least a part of the height measurement positions of the plurality of planar samples in the measurement step is the same common reference position. A semiconductor exposure method for calculating a height distribution of the surface of the stage after normalizing a height measurement result of each of the planar samples with a measurement result of the common reference position. 7. The semiconductor exposure method according to claim 1, wherein, in the measuring step, a predetermined number of height measurement positions over substantially the entire surface of the planar sample are obtained as one unit, and the same height measurement position is defined as one unit. A semiconductor exposure method for calculating the height distribution of the surface of the stage by sequentially updating previous measurement results with new measurement results in the distribution calculation step. 8. The semiconductor exposure method according to claim 1, wherein, in the measuring step, the predetermined height at which the height measurement positions over substantially the entire surface of the planar sample are obtained is defined as one unit. A semiconductor exposure method for calculating a height distribution of the surface of the stage based on a measurement result of each unit in the distribution calculating step. 9. Exposure means, a stage for fixing a planar sample, height measuring means for measuring the height of the surface of the planar sample fixed to the stage, and height of the surface of the planar sample. In a semiconductor exposure apparatus including a correction unit that feeds back a measurement result to the exposure unit or the stage, when sequentially exposing a plurality of the planar samples, the height measuring unit includes at least each of the planar samples. Some measure the height at different positions, accumulate the height measurement results at different positions of the plurality of planar samples, and count the number of height measurement positions greater than the number of height measurement positions of one planar sample. A height distribution management means for calculating a height distribution of the surface of the stage from a height measurement result at the measurement position, and performing management based on the height distribution of the surface of the stage. Exposure equipment . 10. The semiconductor exposure apparatus according to claim 9, wherein the height distribution management means determines whether a height distribution of the surface of the stage is within a predetermined flatness tolerance.
A semiconductor exposure apparatus that performs a predetermined recovery process when the value is not within the allowable range; 11. The semiconductor exposure apparatus according to claim 9, wherein the height distribution management means outputs a height distribution of a surface of the stage to the correction means, and wherein the correction means outputs a height distribution of the surface of the stage. A semiconductor exposure apparatus that adjusts the height of the stage based on a height distribution. 12. The semiconductor exposure apparatus according to claim 9, wherein the height distribution management unit outputs a height distribution on the surface of the stage to the correction unit, and the correction unit outputs the height distribution on the surface of the stage. A semiconductor exposure apparatus that adjusts a focus of the exposure unit based on a height distribution. 13. The semiconductor exposure apparatus according to claim 9, wherein the height distribution management means outputs a height distribution of the surface of the stage to the correction means, and wherein the correction means outputs the height distribution of the surface of the stage. A semiconductor exposure apparatus that adjusts an exposure position of the exposure unit based on a height distribution. 14. The semiconductor exposure apparatus according to claim 9, wherein at least a part of the height measurement positions of the plurality of planar samples measured by the height measurement means is the same common reference position, The height distribution management means, after normalizing the height measurement result for each of the planar samples with the measurement result of the common reference position,
A semiconductor exposure apparatus for calculating a height distribution of the surface of the stage; 15. The semiconductor exposure apparatus according to claim 9, wherein the measuring unit performs the measurement at the same height measurement position with a predetermined number of units at which the height measurement positions over substantially the entire surface of the planar sample are obtained as one unit. A semiconductor exposure apparatus that repeatedly performs measurement, and wherein the height distribution management unit sequentially updates a previous measurement result with a new measurement result to calculate a height distribution on the surface of the stage. 16. The semiconductor exposure apparatus according to claim 9, wherein the measuring means sets the predetermined height at which the height measurement positions over substantially the entire surface of the planar sample are obtained as one unit at the same height measurement position. A semiconductor exposure apparatus that repeatedly performs measurement, and wherein the height distribution management unit calculates a height distribution of the surface of the stage based on a measurement result for each unit.