JPH09312246A - Detecting noise in pattern forming apparatus, noise detecting mark, and method and apparatus for forming pattern having them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-reliability noise detecting method, a noise detecting mark, and pattern forming apparatus having them which efficiently and accurately specifies for a short time the frequency of the noise, variation of the beam size, positional deviation of the beam in the pattern forming apparatus. SOLUTION: The noise detecting process used in the noise detecting method comprises irradiating a beam at specified frequency on a noise detecting mark prepared for the apparatus, monitoring and storing signals of a reflected beam thereof, and repeating the detecting step several times at changed beam frequencies. The analysis results with a beam at frequency 0 (blanking off) and high frequency beam shown in Figs. a and b are compared to judge whether peaks are due to beat of the high frequency noise with the beam or only low frequency noise. The beat frequency is low and hence it can be caught. The latent high frequency noise can be obtained from the shift width and direction of the peak from the high frequency value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drawing device in an LSI manufacturing device. In particular, the present invention relates to a noise detection method and a noise detection mark in a beam drawing apparatus, and a drawing apparatus and a drawing method having these marks.

[0002]

2. Description of the Related Art As the degree of integration of semiconductors is improved, the miniaturization of patterns is rapidly progressing. A high-precision mask, a high-resolution stepper, etc. are required for the formation of this fine pattern, and particularly for the mask, there is a great demand for high-precision pattern formation. For such mask fabrication, increasing the accuracy of the drawing device is also an important issue.

In the above drawing apparatus, there are various error generation factors that hinder accuracy. One of them is noise. This is caused by characteristics of digital and analog electric circuits, performance deterioration of each component, mechanical vibration, and the like. This noise causes, for example, fluctuations in beam size and fluctuations in beam position, resulting in dimensional fluctuations in the pattern to be formed, which in turn greatly deteriorates the quality of the mask. In order to maintain and improve the performance of the device, it is first necessary to detect and analyze this noise.

The following method is used for noise analysis due to the above mechanical vibration. For example, the beam in the drawing apparatus is set to the blanking off state, and FIG.
A beam is applied (dotted line) to the Au atom in (a) or the edge (part) of the beam intensity detection pattern as shown by the mark in FIG. 21 (b). The beam reflected or transmitted by the pattern is monitored for beam intensity using a detector. By performing a Fourier transform on the intensity distribution, frequency analysis of noise can be performed.

In the above noise detection method, for example, the beam is blanked off in the drawing device, is irradiated to the noise detection mark, and the noise of relative vibration between the beam and the sample is measured while moving the sample stage. Is the way. However, at most 100 can be detected by this method.
Up to a noise component on the order of kHz. This is because the reflected beam detector has its own time constant, for example 2 μs, and the corresponding noise above 500 kHz cannot be detected.

The noise of the drawing apparatus includes noise of the MHz order, and the physical error component may reach 0.05 μm depending on the cause. Therefore, the accuracy of noise detection by the above-described reflected beam detector is insufficient.

Therefore, with respect to such high frequency noise, a resist pattern is formed on a mask, and its position and size are observed with an SEM (scanning electron microscope), a laser microscope, etc., and its image or I had to do from analyzing the photos. However, this method requires a very long time and a great deal of trouble such as pattern formation by a drawing device, development, observation and analysis. As a result, it has also been a cause of increased costs for the reticle and the semiconductor itself.

[0008]

As described above, a method for efficiently analyzing high frequency noise in a drawing apparatus has not yet been obtained in the past. Therefore, there is a problem in that the throughput (production efficiency) of the drawing apparatus is hindered from being improved.

The present invention has been made in consideration of the above circumstances, and an object thereof is to identify the frequency of noise generated in a drawing apparatus, the amount of change in beam size, the amount of beam displacement, etc. in a short time. The present invention provides a noise detection method and a noise detection mark in a drawing device that can perform stable drawing efficiently and accurately, and a drawing device and a drawing method having the same.

[0010]

The most typical feature of the noise detecting method in the drawing apparatus of the present invention is to irradiate a beam to a noise detecting mark prepared in the beam drawing apparatus at a predetermined frequency and reflect or reflect the beam. It comprises a detection step of memorizing the signal of the transmitted beam by monitor, and a step of performing the detection step in which the predetermined frequency is changed, and the frequency of noise and its frequency using information obtained by frequency analysis of the monitoring result of each of the detection steps. It is characterized in that the performance of the beam drawing apparatus is managed by identifying the size.

Further features of the noise detecting method in the drawing apparatus of the present invention are shown in (1) to (6). (1) A detection step of irradiating two kinds of noise detection marks prepared in the beam drawing apparatus with a beam at a predetermined frequency and storing the signal of the beam reflected or transmitted by the monitor in the measurement range of the detection step. The detection step is performed for two or more kinds of the predetermined frequencies so as to include at least one frequency that does not exceed the frequency, and the frequency of the noise is obtained by performing frequency analysis and comparison from the monitor results of each of the detection steps and the magnitude of the noise. It is characterized in that the performance of the beam drawing apparatus is managed by analyzing the height.

(2) A detection step of irradiating the two types of noise detection marks prepared in the beam drawing apparatus with a beam at a predetermined frequency and storing the signal of the beam reflected or transmitted through the monitor in the monitor step. The frequency of noise by performing the detection step for two or more kinds of the predetermined frequencies that include at least one frequency that does not reach the measurement range, and performing frequency analysis from the monitor results of each of the detection steps and comparing with reference data. And by analyzing the noise magnitude,
It is characterized by managing the performance of the beam drawing apparatus.

(3) In the noise detecting method in the drawing apparatus according to any one of (1) and (2) above, the magnitude of the analyzed noise includes at least one of the size variation amount and the positional displacement amount in the beam. It is characterized by

(4) In the noise detecting method in the drawing apparatus according to any one of (1) and (2) above, the beam irradiation is performed by a function generator whose frequency can be changed.

(5) In the noise detecting method in the drawing apparatus described in (2) above, the reference data is irradiated with the beam over the mark by a unit area at a frequency sufficiently smaller than the frequency of the noise, and the reflection or It is characterized in that the detection step is executed by the amount of the transmitted beam and is obtained by frequency analysis.

(6) The detection step of irradiating the noise detection mark prepared in the beam drawing apparatus with a beam at a predetermined frequency and storing the signal of the beam reflected or transmitted through the monitor, and the measurement range of the detection step. Irradiating the beam with the beam over the unit area at a frequency lower than the frequency of the target noise, the step of performing the detecting step for two or more kinds of the predetermined frequencies including at least one non-existing frequency. And a step of preliminarily holding reference data obtained by frequency-analyzing the monitoring result of the detecting step performed by performing frequency analysis from the monitoring result of performing the detecting step for one of the predetermined frequencies, By comparing with the reference data, while specifying the frequency of noise,
Further, another example of the predetermined frequency is characterized in that the magnitude of noise is analyzed by performing frequency analysis from the monitoring result obtained by performing the detection step and comparing the intensities with each other.

The most representative feature of the noise detection mark in the drawing apparatus of the present invention is two line-symmetrical patterns provided on the substrate and spaced apart to the extent that a beam is applied to each part of the two. It is characterized in that it has the same pattern as one of the two patterns provided on the substrate.

Further features of the noise detection mark in the drawing apparatus of the present invention are shown in (1) to (4). (1) The noise detection mark is provided in a drawing apparatus that uses a charged particle beam or an electromagnetic wave beam, and the atoms of the mark are different from the atoms that form the substrate or the support on which the mark is provided. . (2) Each pattern of the noise detection mark has X
It is characterized in that it is provided separately for each noise detection in the direction and for each noise detection in the Y direction. (3) In the noise detection mark provided in the drawing apparatus using the charged particle beam, the pattern is made of a substance having a property of not magnetizing. (4) In the noise detection mark provided in the drawing device using the beam of electromagnetic waves, the patterns are W, Au, Ag
One of the atoms is included.

As a typical first characteristic, the drawing apparatus of the present invention has means for providing a noise detection mark for use in noise detection in the beam drawing apparatus, and the mark is repeatedly irradiated with a beam at a predetermined frequency. Irradiation means, monitor means for taking in the signal of the beam reflected or transmitted by the irradiation means according to the mark at a predetermined cycle, and frequency analysis of the signal taken in by the monitor means. Or a calculation means for recognizing only the peak frequency,
Control means for changing a predetermined frequency of the beam so as to include at least a frequency equal to or higher than a measurement limit with respect to a predetermined period of the monitor means, and the calculation is performed for beams having two or more kinds of frequencies using the control means. The means is executed and the recognized data are compared with each other to obtain the type of noise generated in the device, the frequency of the noise and its magnitude, or the frequency of the noise.

As a further feature of the drawing apparatus described above, the peak of the frequency analysis result obtained by the calculation means corresponding to the control means by the beam having the incident frequency fe above the measurement limit is the noise and the incident beam. Further, a calculation mechanism for recognizing whether or not a beat is generated by performing a frequency calculation is provided, and when the generated peak is a beat, the frequency of the noise is calculated from the frequency of the peak and the incident frequency fe. It is characterized in that a value or its approximate value is obtained.

The drawing apparatus of the present invention has, as a second typical feature, means for providing a noise detection mark for use in noise detection in the beam drawing apparatus, and repeatedly irradiating the mark with a beam at a predetermined frequency. Irradiation means, monitor means for taking in the signal of the beam reflected or transmitted by the irradiation means according to the mark at a predetermined cycle, and frequency analysis of the signal taken in by the monitor means. Or a calculation means for recognizing only the peak frequency,
Control means for changing a predetermined frequency of the beam so as to include at least one frequency equal to or higher than a measurement limit with respect to a predetermined cycle of the monitor means, and the beam for a unit area at a frequency lower than the frequency of the target noise. And a means for previously retaining as a reference data a result of the arithmetic means when the mark is irradiated over the mark, the arithmetic means is executed for one of the predetermined frequencies, and by comparing with the reference data,
It is characterized in that the frequency of noise is specified, and the calculating means for another example of the predetermined frequency is executed, and the magnitude of noise is analyzed by comparing the intensities with each other.

A further feature of the above-mentioned drawing apparatus is that it further comprises means for providing a reference pattern for use in detecting reference data in the beam drawing apparatus.

The drawing method of the drawing apparatus according to the present invention has, as a first typical feature, means for providing a noise detection mark for use in noise detection in the beam drawing apparatus, and a beam at a predetermined frequency for the mark. Irradiating means for repeatedly irradiating, monitor means for taking in a signal of a beam reflected or transmitted by the irradiating means in accordance with the mark at a predetermined cycle, and at least one frequency higher than the measurement limit for the predetermined cycle of the monitor means. The control means for changing the predetermined frequency of the beam included, and the frequency signals of the signals captured by the monitor means for the beams of two or more kinds of frequencies are analyzed by the control means, and the peak frequency and its peak are obtained from the result. Is recognized by the device by recognizing the size of each The frequency of the noise, the type of the noise, and the magnitude of the noise are detected. As a result of the arithmetic means, 1 / υ, which is an integer multiple of the cycle of the noise having the maximum noise, / Υ, 3
/ Ν, ... N / υ is calculated, and at least a frequency having a period larger than the time constant of the circuit controlling the deflector used in the drawing apparatus is set to the period 1 / υ, 2 / υ, 3 / υ ,. n
Frequency υ, υ / 2, υ / 3, ...
It is characterized by selecting from υ / n and drawing at that frequency.

Further features of the drawing method of the drawing apparatus are shown in (1) to (3). (1) When performing multiple drawing, the frequencies υ, υ / 2, υ
It is characterized in that at least one frequency is selected from / 3, ... And υ / n, and drawing is performed at that frequency. (2) Drawing frequency is υ, υ / 2, υ / 3, ... υ / n
When determining from among the above, the drawing is performed by selecting a frequency within a range that cannot be detected by a detector such as an electron beam reflection detector. (3) When the drawing frequency is determined, the frequencies are υ, υ / 2, υ / 3, ... υ / n so that the total noise component generated in the drawing device is minimized from the result of the calculation means.
It is characterized in that it is selected from among and drawn.

The drawing method of the drawing apparatus of the present invention has, as a second typical feature, a secondary characteristic corresponding to the beam obtained by irradiating the mark on the sample with the beam in the beam drawing apparatus and scanning the mark a plurality of times. In the method of positioning and drawing with respect to the sample by detecting the mark position using such a signal, the timing to start the beam scanning for the k-th mark detection is t _k , the total number of beam scanning times is n times,
When one frequency disturbance for varying the beam position is f, defines t _k such that Σ exp (i (2πft k) ) is approximately 0, relative to the sample at a frequency having the timing of this t _k The feature is that the beam position is determined by drawing and drawing.

Further features of the drawing method of the drawing apparatus are shown in (1) and (2). (1) The frequency f is the fundamental frequency of the power supply of the drawing apparatus,
Alternatively, it is a multiple thereof. (2) For each of two or more types of disturbances having two different types of frequencies that change the beam position, set each frequency to f
_{When m} (m = 1,2,3 ...), Σ exp (i (2πf _m
t _k)) determined a t _k such that approximately 0, determines the beam position relative to the specimen at a frequency having the timing of this t _k, characterized by drawing.

According to the present invention, the following actions are involved. When the beam is applied to the noise detection mark at a predetermined frequency, a beat occurs between the noise component of the beam and the incident beam. Since the frequency of this beat is low, even high-frequency noise that was originally undetectable can be detected in the form of a beat using the same detector. What is detected here includes two types of components, a beat and a low-frequency noise that originally exists. These two components can be separated by monitoring at least two types of incident frequency components. It is also possible to know the magnitude of noise from the reflected beam intensity.

Two types of noise detection marks are used to know the magnitude of noise. With respect to the beams applied to the two line-symmetrical patterns, the positional deviation variation is canceled out, and the size variation can be extracted, and the beam applied to one pattern is equal to
Variations in misalignment are included. If the magnitude variation amount is subtracted from the variation amount in one pattern, the positional deviation variation is extracted.

According to the first typical feature of the drawing method of the present invention, the type of the noise (beam size fluctuation or beam position deviation fluctuation) can be specified for noise. Therefore, noise removal is selected at the time of drawing. Control becomes possible. In the second typical feature, the error of the beam position is removed from the coordinates at the time of detecting the mark, and the position variation is not given as much as possible at the time of drawing.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION A noise detecting method in a drawing apparatus according to the present invention will be described. In the following, taking EB (electron beam) as an example, the noise of beam size and beam position shift will be considered, and this will be described with reference to figures and formulas.

As a first embodiment, the case of one noise will be described. For simplicity, a certain device state (beam size S) has noise, and the noise N is one frequency (M
It is assumed to be represented by a sine function having a (Hz order). One noise detection mark (also called a pattern) is a shot represented by the time change of a sine wave as shown in the following formula (1).
Suppose you hit. Then, the beam size S is expressed as S = S _o (1 + Asin _{ω n} t) (1) A, S _o : constant ω _n : noise angular frequency.

It is assumed that the beam is applied to the pattern at a certain frequency ω _s . Then, the beam intensity I _s is _{I s = I o (1 +} αsinω s t) ... (2) ω s: beam angular frequency α of, I _o: is represented by a constant.

The amount of reflected electrons O _{s at} this time is O _s = O _o (1 + A sin ω _n t) (1 + α sin ω _s t) (3) O _s : constant.

Here, when ω _s = 0, that is, when the beam is in the blanking off state, O _s = constant effectively due to the characteristics of the reflected beam detector, and noise cannot be detected.
However, if the beam irradiation is performed with ω _s sufficiently close to ω _n , the beat frequency can be detected. Equation (3)
When the Fourier transform is performed on the backscattered electron intensity obtained in step (4), equation (4) is obtained. F {O _s } = f (ω) = Bδ (ω _s −ω _n ) + C δ (ω _n ) + D δ (ω _s ) + E δ (ω _s + ω _n ) ... (4) B, C, D, E: constant here Therefore, ω _n , ω _s , and ω _s + ω _n having high frequencies are not detected from the time constant of the reflected beam detector. It can be seen that the spectrum obtained as a result of the frequency analysis is only one of ω _s −ω _n , and this value represents the angular frequency of the beat. Let that value be ω _u . Then, the noise frequency ω _n
Is expressed by equation (5). ω _n = ω _s ± ω _u (5) At this stage, the noise frequency has not been specified yet. In order to identify the noise frequency, the angular frequency ω _{s of the} shot is further changed, and the shot is shot again in the pattern with ω _s ^* (the range where the difference from ω _s is smaller than the time constant of the detector).
Similar to the above, the amount of reflected beam is monitored by the detector, and as a result of the frequency analysis, the angular frequency ω _{u of the} obtained beat is obtained.
^{If *} , then ω _n = ω _s ± ω _u ^* (6)

As can be seen from the equations (5) and (6), since the peak positions are displaced, it is conversely understood that this noise is not caused by the original noise but caused by the beat. Further, the frequency of the original high frequency noise can be specified from the shift direction and the shift amount. Among the two candidates of the formula (5) and the two candidates of the formula (6), the coincident one is the angular frequency of noise.

In the above, the discussion has been advanced on the premise that the noise is high frequency noise. However, this assumption is not necessary. For example, the pattern of the noise detection mark is irradiated with the incident beam at a frequency of 0 (blanking off), and the frequency of the measurement result is analyzed. The results are shown in FIG. 1 (a) (I (au) is the beam intensity and the unit is arbitrary). Fig. 1 (b) showing the analysis result and the analysis result by the high frequency beam.
If you compare with, you can see whether the observed peak is due to high frequency noise and the beat of the beam, or just low frequency noise. For example, there is no peak in FIG.
If there is a peak in (b), this is high frequency noise.
On the contrary, if there is a peak at the same position in FIGS. 1A and 1B, this indicates low frequency noise.

When it is desired to know only the presence or absence of high frequency noise and a guideline of noise frequency, it is sufficient to perform the measurement of frequency 0 once, the measurement of high frequency once, and a total of two times. .

As a second embodiment, the case of plural noises will be described. Similar to the first embodiment, there is no change in the basic principle and method. The only difference is that each frequency analysis result has two or more peaks. The discussion in the first embodiment may be applied to the individual peaks of each frequency analysis result. That is, the peaks that were present in the zero frequency or low frequency beam measurement were low frequency noise, and the peaks that were not present were high frequency noise. In order to increase the measurement accuracy of the noise frequency, the incident frequency is slightly changed as in the first embodiment, and the equation (5) and the equation (6) are changed.
The frequency can be obtained from

More preferably, two or more types of incident frequencies above the measurement limit may be used. This is because some frequencies cannot be observed with only one incident beam frequency. Let f _u be the measurement limit frequency of the backscattered electron detector. If the frequency of the incident beam is f _s, measurable high frequency noise is _{f s -f u ~f s + f} u. for that reason,
If the measurement is performed randomly, the frequencies f _s1 , f _s2, ... Of the incident beam may be set as shown in FIG. In the figure, a is a margin for leaving no unmeasurable points. Needless to say, the beam frequencies are f _s1 , f _s2, ... To improve the measurement accuracy as described in the first embodiment, and f _s1 , f _s2, ... If observed, the frequency of noise can be specified almost completely.

Although the electron beam intensity is changed by the trigonometric function in the above description, another modulation method may be used. This is because the repeated intensity modulation can be expressed by addition of trigonometric functions. For example, as shown in FIG. 3, the modulation may be rectangular.
For simplicity, it is assumed that there is only one high frequency noise. When the angular frequency of repetition of a rectangular wave as shown in FIG. 3 is W _o , the observed reflected beam intensity I _rec is expressed as I _rec = A _o + ΣA _i sin (ω _i t + λ / 2) (7) It Where ω _i = W _o × n (n = 1,2 ...)
It is.

In the above formula (7), A _o represents a zero frequency,
Generally not 0. That is, angular frequency 0, W _o , 2
W _o, the superposition of the triangular relationship with a 4W _o. Both the noise frequency W _n and the incident frequency W _o are the measurement limit frequency W _u
Above. It is also assumed that W _n and W _o have close values.
The peaks observed at this time are only the W _n component and the beat of noise. This is a W _n -W _o. The beat with the component of frequency 0 cannot be observed at W _n , and the frequency mW _m (m
= 2,3 ...) The beat is mW _m −W _o >, which is not observed.

The above-described noise shape related to the shape of the incident beam also applies. That is, although the noise shape is limited to the trigonometric function in the above, the present invention is not limited to this. This is because all iterative functions are represented by trigonometric additions. For example, consider a case where the noise has a rectangular shape for some reason and repeatedly oscillates at an angular frequency ω. This noise is represented by reflected beam intensity I = A _o + ΣA (n) sin (nωt) (8) (n = 1, 2 ...). That is, angular frequency 0, ω,
It is a superposition of triangular relationships having periods of 2ω and 3ω.

The presence of this noise can be recognized by observing the noise of the angular frequency ω. For simplification, the beam size variation will be taken as an example of noise and its principle will be described. The following is the third embodiment.

FIG. 4 is a pattern plan view showing one of the noise detection marks according to the present invention. The noise detection mark 4 is provided on, for example, a support (substrate) provided on the stage of the apparatus, and has two line-symmetric patterns that are apart from each other such that a beam is applied to a part of each of them. For example, only one pattern has been used for the noise detection up to the above.

As shown in FIG. 4, the beam is X-marked on one mark.
Only (for example, 0.5 μm) is irradiated on the mark. The Fourier transform of the reflected beam amount is taken, and the size of the peak corresponding to the frequency of beam irradiation is obtained. Let this peak intensity be A, for example. ON / OFF of the above high frequency
Perform noise analysis by beam. At this time, when the intensity of the peak due to the beat of the obtained beam and noise is n _p , the variation of the beam size is 2Xn _p / A (9). The reason for this will be described below.

The beam size is _{L = L o + Lsinω n t} ... (10) ω n: high-angle the intensity of the beam frequency incident is approximated as follows. I = I _o (1 + sin ω _e t) (11) The reflected beam amount R is expressed as follows. R = K ₁ LI + K ₂ (12) K ₁ , K ₂ : constant The first term represents the reflection by the noise detection mark, and the second term
The term represents the other part and the part due to stray electrons, which approximates to be almost constant.

The measurement amount M by the reflected beam detector is expressed by M = C _a F (R) + C _b (13) C _a and C _b are constants determined by the measuring device and the measuring state. F means to ignore the high frequency components in the amount in parentheses. By modifying the equation (13), M = D ₁ F (LI) + D ₂ (14) is obtained. In procedure 1, M is as follows. M = D ₁ F {(L _o + L sinω _n t) I _o (1 + sinω _e t) / 2} + D ₂ = D ₁ F {L _o I _o (1 + sinω _e t)} + D ₂ (15) Fourier transform If the amount is M ^* , then M ^* = Z ₁ δ (ω−0) + D _{1 Lo Io} δ (ω−ω _e ) / 4 (16) where Z ₁ = FD _{1 Lo Io} / 2 + D _o It becomes (17).

On the other hand, M in procedure 2 is obtained as follows. M = D ₁ F {(L _o + Lsin ω _n t) I _o (1 + sin ω _e t) / 2} + D ₂ = D ₁ F {L _o I _o / 2 + L _o I _o / 2sin ω _e t + LI _o × sin ω _n t / 2 + LI _o × sin ω _n t × sin ω _e t / 2} + D ₂ (18) The second and third terms in parentheses are high-frequency components and are ignored. Therefore, M = D ₁ F [L _o I _o / 2 + LI _o {cos (ω _n + ω _e ) t −cos (ω _n −ω _e ) t} / 4] + D ₂ (19) The second term in parentheses Is also a high-frequency component, so if it is ignored, the result will be as follows. M = D ₁ F [ _{Lo Io} / 2- {LI _o cos (ω _n −ω _e ) t} / 4] + D ₂ (20) When Fourier transform of the equation (20) is performed, M ^* = Z ₁ δ ( ω−0) + D ₁ LI _o δ {ω− (ω _n −ω _e )} / 4 (21) Here, Z ₁ = D ₁ L _{o Io} / 2 + D ₂ (22).

Therefore, the peak intensity when the beam is turned on and off when the beam is applied to both the upper and lower patterns is A = D ₁ L _o I _o / 4 (23) n _p = D ₁ LI _o / 8 ( 24) Therefore, from the proportional relationship, the fluctuation amplitude L of the noise is obtained by L = X × n _p / 2A (25).

According to each of the above-described embodiments, the following sequence of noise detection methods in the drawing device is summarized. (I) Use of two types of noise detection marks (patterns), one mark produced for detecting noise in the drawing apparatus and a mark which is line symmetrical with the same mark as the mark. (Ii) The pattern of (i) above is irradiated with a beam or the like shaped and modulated at a predetermined frequency, and the beam signal transmitted through the pattern or reflected by the pattern is stored in a memory as a monitor. (iii) At least two types of frequencies (ii)
(For each of the two types of noise detection marks). (Iv) The frequency of noise is calculated by performing frequency analysis such as Fourier transform on the above-mentioned various monitor results and comparing the results. In addition, (v) Regarding the size (variation) of noise, the beam is applied to the pattern by a unit area at a frequency that is considered to be sufficiently smaller than the frequency of the noise, and reference data (for noise detection) related to the amount of the transmitted or reflected beam is emitted. The intensity of the transmitted / reflected beam per unit area of the mark) and the monitor results obtained in (ii), (iii), and (iv) are compared, and noise is compared with the variation in beam size and the beam. Separate into position shifts and obtain the amount of variation for each.

Next, as a fourth embodiment, an electron beam drawing apparatus will be described. FIG. 5 is a schematic configuration diagram showing an electron beam drawing apparatus to which the present invention is applied. 10 in the figure
Is a sample chamber, 11 is a target, 12 is a sample stand, 13 is a mark support, 14 is a noise detection mark (pattern), 15 is a backscattered electron detector, 16 is a reference pattern, 20 is an electron optical lens barrel, 21 Is an electron gun, 22a to 22e are various lens systems, and 23 to
Reference numeral 26 is various deflection systems, 27a is a blanking plate, and 27b and 27c are beam forming aperture masks. Also, 31
Is a sample stage drive circuit unit, 32 is a laser length measurement system, 33 is a deflection control circuit unit, 34 is a variable shaped beam size control circuit unit, 36 is a buffer memory and control circuit, 37 is a control computer, 38 is a data conversion computer. , 39 shows a CAD system.

The sample table drive circuit 31 can move the table according to an instruction from the control computer 37. Electron gun 21
The electron beam emitted from is turned on and off by the blanking deflector 23. In this device, the irradiation time can be adjusted by adjusting the ON time of the blanking deflector 23, and the irradiation waiting time (settling time) can be adjusted by adjusting the OFF time. By adjusting these, the irradiation frequency of the beam is variable. Each ON (and OFF) time can be set in the blanking control circuit unit 34 of FIG. These times are set from the control computer 37 through the control circuit 36.
In addition, the beam is turned on and off repeatedly, irradiation is started,
Frequency multiple calculation, selection of frequency according to time constant of condenser lens that controls drawing throughput and deflection,
The start and end of irradiation are also performed from the control computer 37.

The beam passing through the blanking plate 27a is deflected by the beam forming deflector 24 and the beam forming aperture mask.
The beam is shaped into a rectangular beam by 27b and 27c, and the size of the rectangle is changed. Then, the shaped beam is deflected and scanned on the target 11 by the scanning deflectors 25 and 26, and the target 11 is drawn in a desired pattern by this beam scanning. The standard acceleration voltage of the electron beam in this device is 50 kV, and the maximum size of the variable shaped beam that can be generated is 2 μm in height,
It is a rectangle with a width of 2 μm.

The apparatus is also provided with a reflected beam detector 15, which detects the electrons reflected by the pattern (noise detection mark or the like). Where the reflected beam detector
The measurement limit angular frequency of 15 is 500 kHz. Monitor and control circuit 40 acquires data from the reflected beam detector. This is performed at predetermined time intervals, and after the predetermined number of times N times, the operation is finished. The N pieces of data thus stored are collectively fetched by the control computer 37. The control computer 37 controls the circuit and sets the detection interval.

A mark support base 13 is mounted on the sample base 12, and various marks for noise detection are mounted on the mark support base 13. This mark is a W (tungsten) pattern formed on a silicon wafer. These marks are used to determine the type of noise according to their shapes.
There are two types of noise, shot size fluctuation and shot position shift. Here, for simplicity, only noise in the Y direction will be considered.

Examples of noise detection marks are shown in FIGS. 6 (a), 6 (b), 6 (c) and 6 (d). Mark 4-1 for simplicity
, 4-2, 5-1, and 5-2 are unified to 1 μm. FIG.
The dotted lines in (a) and (b) are examples of beam irradiation. Irradiate to the edge of the mark (a part of the pattern). In the pattern shapes shown in FIGS. 6A and 6B, the variation amount of backscattered electrons due to the displacement of the shot is offset by the upper and lower patterns, so that the total backscattered electron amount does not vary due to the displacement of the shot position. Therefore, only the shot size variation amount is detected in this pattern.

The amount of backscattered electrons according to the patterns shown in FIGS. 6C and 6D has a backscattered electron intensity in which the effects of the shot size variation amount and the shot position shift amount are mixed. Therefore, by comparing with the frequency analysis result of the backscattered electrons obtained in the patterns of FIGS. 6A and 6B, it is possible to separate the noise of the shot displacement amount and the shot size variation amount.

Noise analysis is performed as follows by such an apparatus. In FIG. 5, first, the control computer 37
Sends a command to the sample stage drive circuit section 31 so that the target noise detection mark is set at a position directly below the beam. Next, the ON / OFF time of the beam is set in the blanking control circuit unit 34 from the control computer. Further, the monitor, the control circuit unit 40, and the monitor time and interval are set. Next, a repeat command of beam ON / OFF irradiation is sent to the blanking control circuit unit 34, and then a comment to start monitoring is sent to the control circuit unit 40. All of these are also performed from the control computer 37. After a lapse of a predetermined time, the control computer 37 sends an end command to the blanking control circuit unit 34, fetches the detection data from the monitor and control circuit unit 40, and saves it in the hard disk.

The above operation is performed for several incident beam frequencies. Further, such an operation is performed for each noise detection pattern. After that, the data is analyzed. The above operation is performed by the control computer 37 in accordance with a sequence previously incorporated in the control computer 37. An example of data analysis will be shown later, so only the rough flow will be described here.

First, with respect to each frequency data of the incident beam, the control computer 37 analyzes the frequency and obtains the peak position and intensity thereof. Next, the results are compared, the frequency of the noise is obtained from the peak position, and the magnitude of the noise is obtained from the intensity. Here, the frequency analysis is carried out by executing a sequence of fast Fourier transforms that are incorporated in advance. The analysis of peak positions and intensities is performed in the following order. That is, (1) peak recognition,
(2) Recognition of peak frequency, and (3) Recognition of peak intensity. Here, the intensity of (3) may be obtained instead of the peak area.

Next, as the fifth embodiment, specific noise detection using the fourth embodiment (for example, noise according to the beam size in the Y direction) will be described. The noise here outputs a frequency of 0.7 MHz and an amplitude of 20 nm, for example. Using a 1.5 μm square beam,
This was turned on and off to modulate the beam intensity.
The intensity changes with the repetition of the rectangle. The angular frequency f _e of the incident beam at this time is 0 Hz, 900 kHz, 1.8 MHz
And As a result, 0 Hz to 2.3 MHz (1.8
Noise up to +0.5 MHz can be monitored.

An example of analyzing the beam size and the beam position in the Y direction will be described below. The beam was repeatedly irradiated at the position indicated by the dotted line in FIG. 6A, and the noise of the beam size in the Y direction was examined. The frequency analysis results are shown in Figs. 7 (a), (b), (c).
Shown in In the figure, peaks A1 to A3 indicate the presence of low-frequency noise of 50 kHz. On the other hand, the peak B1 is 1.1 MHz (0.9 + 0.2 MHz) or 0.7
It shows the presence of noise of MHz (0.9-0.2 MHz) (result [1]). The peak C1 is 2.2 MHz (1.
8 + 0.4 MHz) or 1.4 MHz (1.8-
It shows the presence of noise of 0.4 MHz (result [2]
). From this, it can be seen that there is some problem in the circuit portion related to the beam size in the Y direction and causes noise. Moreover, it is of the MHz order.

In order to identify the frequency, the control computer re-measures at f _e = 0.8 MHz and 2.2 MHz according to the sequence. The frequency analysis result is shown in FIG.
(B). From the frequency of peak B2, the frequency of this noise is 0.9 MHz (0.8 + 0.1) or 0.
It can be seen that the frequency is 7 MHz (0.8-0.1). The noise frequency is determined to be 0.7 MHz together with the result [1] described above (result [3]).

The noise frequency of the peak C1 in FIG. 7C and the peak C2 in FIG. 8B are 1.4M in the same manner.
Hz is determined. This value 0.7MHz is (result [3])
Therefore, it is considered to be the harmonic component of the noise detected in the result [3]. As a result, it can be seen that the noise generated in the circuit section related to the n-beam size in the Y direction is 0.7 MHz or 1.4 MHz, and the control computer outputs this result.

Next, the noise is measured by using one of the noise detection marks shown in FIG. 6 (c). As described above, this mark can be used to measure both the beam size variation noise and the beam position variation variation noise. The frequency f _e is 0 MHz and 0.8 MH as in the above example.
z, 0.9 MHz, 1.6 MHz and 1.8 MHz. The frequency analysis results are shown in FIGS. 9 (a), (b), (c), and FIGS. 10 (a), (b). Peaks A1 'to A5', C
1'and C2 'are also visible when the mark in FIG. 6 (a) is used. Peaks P1 and P2 have newly appeared. From these peak positions of 300 kHz and 400 kHz, it can be seen that the frequency of this noise is 1.2 MHz. From this, it can be seen that there is some problem in the electric circuit system that controls the beam position in the Y direction, and its frequency is 1.2 MHz.

Next, the noise intensity is obtained from the frequency analysis data. A beam of 1.5 μm square was applied to the mark as shown by the dotted line in FIG.
N and OFF, and the corresponding peak magnitudes k ₁ and k ₂ of ₁ kHz are obtained. On the other hand, 0.7 MH related to the above dimensional variation
The beat intensity of z was 0.01 k ₁ . From this, the amplitude of noise is 0.01 × 2 × 1 μm = 0.02 μm
Is calculated. The control computer, as the type of noise, the beam size in the Y direction, the frequency of the noise (0.7 MHz),
The size (20 nm) is output.

Next, the noise relating to the position is examined from the result of the mark experiment conducted above. First, f _e = 0.9 MH
200kHz beat at z (noise frequency is 0.7M
Hz). As the size of the peak,
As shown in FIG. 11B, 0.011 k ₂ is obtained. From this result, the fluctuation amount due to this noise is calculated as ± 0.011 × 2 × 1 μm = ± 0.022 μm. Of this variation, the variation of ± 0.02 is due to the variation of the beam size, and the remaining ± 0.02.
A fluctuation of 02 μm is considered as position fluctuation noise. Therefore, the control computer outputs (1) noise type (beam position in Y direction, beam size fluctuation) (2) noise frequency (0.7 MHz) (3) noise magnitude (20 nm, 2 nm).

Next, 300 kHz at f _e = 0.9 MHz
A beat (noise frequency is 1.2 MHz) is processed. The magnitude of this peak is 0.0015 k ₂ . The amplitude of this noise is 0.0015 × 2 × 1 μm =
It is calculated to be 0.003 μm. The control computer outputs as follows. (1) Kind of noise (beam position in Y direction) (2) Frequency of noise (1.2 MHz) (3) Magnitude of noise (3 nm) Dealing with noise related to beam size in Y direction from the output of the above control computer I knew what to do.

In the above-mentioned embodiment, the relationship between the peak size and the noise size is performed at the same time as the noise analysis, but it does not have to be the same. I asked for the above relationship in advance,
It can also be used repeatedly during noise analysis.

In the above embodiment, the noise analysis method for the electron beam writing apparatus is shown, but the present invention is not limited to the electron beam writing apparatus. It is effective for all those that use charged particles to draw patterns,
For example, the present invention is effective for an ion beam drawing device.

Next, as a sixth embodiment, a description will be given based on a laser drawing apparatus as an example of drawing using electromagnetic waves. FIG. 12 is a schematic configuration diagram showing a laser drawing apparatus to which the present invention is applied. In the figure, the optical system has the same basic configuration as that shown in FIG. 5, so the laser optical system is simplified. 101 is the sample chamber, 11 is the target, 12
Is a sample stand, 13 is a mark support stand, 14 is a noise detection mark (pattern), 31 is a sample stand drive circuit unit, 44 is a photomultiplier, 401 is a monitor and control circuit, 37 is a control computer, 41 is a power supply and A control circuit, 45 is a laser mechanism, 36 is a buffer memory and control circuit, 42 is a function generator, 43 is various control circuits, and 46 is various optical systems.

In this laser drawing apparatus, φ = 0.3
The function generator 42 is used for the μm laser beam to shape the waveform of the beam and modulate the frequency of the beam.
Here, the frequency was 0.86 MHz and 0.80 MHz, and the beam intensity was sinusoidal with time.

The noise here also means a beam size variation and a beam position shift. The beam is applied to the noise detection mark (pattern) at the above two frequencies.
In this case, the pattern is preferably Au in consideration of the reflectance and resistance to the laser light. The intensity of reflected light from the pattern is monitored while adjusting the sensitivity of the photomultiplier 44, the data is stored, and the Fourier transform is performed.
The analysis results as shown in 3 (a) and 3 (b) were obtained. As a result, 4 for the frequency of 0.86MHz in the high frequency range
Since a peak shifted by 20 kHz is obtained with respect to 0 kHz and 0.80 MHz, the frequency of the positional deviation noise in the Y direction is (0.86 ± 0.04) MHz, (0.
80 ± 0.02) MHz is given as a candidate, and it is understood from both results that 0.82 MHz is the desired noise frequency. The noise intensity obtained from this result was 0.001 k ₁ , as shown in FIG. As a result, the amplitude of the beam fluctuation of noise is 0.00
It is calculated that 1 × 2 × 1 = 0.002 μm.

Next, on the noise detection mark shown in FIG. 6C, the same frequencies as above, 0.86 MHz and 0.80 M, are added.
The beam is emitted at two frequencies of Hz. If this mark is used, as described above, both the amount of the reflected beam, the displacement of the beam, and the variation of the beam size can be measured. This mark is exactly the same as the case where only one of the upper and lower sides exists in FIG. Set it at exactly the same place as the point where the mark in FIG. 6 (c) was set. Data of the reflected beam amount at that time is stored in the same manner as above, Fourier transform is performed, and frequency analysis is performed.
The analysis results of (c) and (d) were obtained. The noise intensity obtained from this result was 0.046 k ₂ . As a result, the total fluctuation amplitude of the noise beam size fluctuation and the beam position deviation fluctuation is 0.046 × 2 × 1 = 0.092 μm.
Is calculated. From this result, it was found that the beam size variation was 0.002 μm and the positional deviation variation was 0.09 μm.

From the above results, it was found that even with the noise frequency of 0.82 MHz in the laser drawing apparatus of this embodiment, there is a cause of noise in the circuit for determining the beam width and position of the laser inside the apparatus.

Incidentally, in the laser drawing apparatus, if evaluation is carried out at the conventional resist stage in order to calculate the above result, it takes about 3 months. However, by applying the present invention, the period for calculating the above result can be shortened to about ⅕ of the conventional period.

Next, as a seventh embodiment, another example of the beam intensity modulation method will be described. In the above-described embodiments, beats are generated by repeating ON / OFF of the beam. This may be done in other ways.

For example, there is also a method of changing and scanning the beam position as shown in FIGS. This can be realized by changing the voltage applied to the deflector at a high frequency while the beam is on.

The noise detection mark used in the present invention is constructed not only by using atoms different from the substrate on which the mark is provided for monitoring, but also by the pattern material depending on the type of beam. You may use them properly. For example, in an electron beam drawing apparatus, not only W but any metal that does not magnetize and has a large scattering cross-section and a relatively large atomic weight may be used. W-Si is also listed as a candidate.

The laser drawing apparatus is not limited to Au. The present invention is also effective for a metal (eg, Ag, W) having a high reflectance and resistance depending on the laser power and wavelength, or a metal having a normal pattern coated to increase the reflectance and resistance.

Regarding the shape of the pattern, as shown in FIG.
Other than the shapes shown in (b), (c), and (d), the shape is not particularly limited as long as the reflected electron intensity greatly changes due to noise on the shot.

The beam waveform is not limited to a sine wave or a rectangular wave because a frequency analysis similar to the above can be performed as long as it has a specific period, and a sawtooth beam or the like may be used. In addition, various modifications can be made without departing from the scope of the present invention.

Next, as an eighth embodiment, a drawing method in the above-described drawing apparatus will be described. Even if the frequency and magnitude of noise are known, the cause of noise cannot be clearly identified if the cause of the noise in the deflection system or its control system cannot be found in the circuit or the like. As a result, noise at the time of drawing cannot be removed,
It is also possible that the variations in the mask and wafer planes are not improved.

Therefore, the frequency of noise generated in the drawing apparatus, the amount of change in beam size, the amount of beam positional deviation, etc. are specified accurately and efficiently as described in the above embodiment, and the result is shown in the drawing apparatus. By feeding back, high-frequency noise in drawing is reduced, and dimensional variations in the mask and wafer are significantly reduced.

The noise frequency ν obtained in (iv) above,
A description will be given below of a drawing method in which noise is eliminated based on the fluctuation amounts of the beam size fluctuation amount and the beam position deviation fluctuation amount obtained in (v) above.

By drawing with 1 / υ, 2 / υ, 3 / υ, ... N / υ, which are integer multiples of the reciprocal of the frequency υ of the noise obtained in (iv) above, it is always possible to obtain the previous shot. The next shot will be drawn with or without the same noise, and variations due to noise in the mask and wafer can be reduced.

In order to perform drawing with all noise components removed, all frequencies υ detected as noise are
The least common multiple of an integral multiple of the reciprocal of _{1 to} υ _n must be taken as the frequency, which is considered difficult in practice. Therefore, first, the one having the largest deviation amount as noise is extracted. Then, by drawing at the frequency of the noise, the main component that determines the total size of the noise is eliminated. The noise elimination effect is expressed by the following equation. The in-plane variation of the mask or wafer is Disp, and the beam size fluctuation amount at each of the above frequencies ν _{1 to} υ _n detected as noise is S
dp1 to Sdpn, the beam position deviation variation amount is set to Pdp1 to Pdp
When n, Disp = {(Sdp1) 2 + (Sdp2) 2 + ... (Sdpn) 2 + (Pdp1) 2 + (Pdp2) 2 + ... (Pdpn) 2} 1/2 ... (26) Here, for example, If the beam size variation Sdp1 is the largest, its noise elimination effect depends on the beam size variation and other values, but the larger the difference, the higher the effectiveness.

Further, the drawing frequency is set to υ, υ / 2, υ /
3. When determining from .nu. / N, it becomes possible to remove high frequency noise by selecting a frequency in an undetectable range by the capability of the equipped reflection detector and performing drawing.

Further, depending on the frequency of each noise, from the monitoring results of the amount of reflected, transmitted or absorbed beams, the frequencies such that the total noise becomes the smallest are υ and υ.
At least 1 out of frequencies of / 2, υ / 3, ... υ / n
By selecting one or more and performing drawing, not only high frequency but also low frequency noise can be efficiently removed.

According to each embodiment, the following drawing method sequences are summarized. (I) Use of two types of noise detection marks (patterns), one mark produced for detecting noise in the drawing apparatus and a mark which is line symmetrical with the same mark as the mark. (Ii) The pattern of (i) above is irradiated with a beam or the like shaped and modulated at a predetermined frequency, and the beam signal transmitted through the pattern or reflected by the pattern is stored in a memory as a monitor. (iii) At least two types of frequencies (ii)
(For each of the two types of noise detection marks). (Iv) The frequency of noise is calculated by performing frequency analysis such as Fourier transform on the above-mentioned various monitor results and comparing the results. In addition, (v) Regarding the size (variation) of noise, the beam is applied to the pattern by a unit area at a frequency that is considered to be sufficiently smaller than the frequency of noise, and reference data (for noise detection) related to the amount of transmitted or reflected beam is emitted. The intensity of the transmitted / reflected beam per unit area of the mark) and the monitor results obtained in (ii), (iii), and (iv) are compared, and noise is compared with the variation in beam size and the beam. Separate into position shifts and obtain the amount of variation for each. (Vi) For the obtained noise, select the one with the largest fluctuation amount, and 1 / which is an integer multiple of the reciprocal of the frequency υ.
Calculate ν, 2 / υ, 3 / υ, ... N / υ.

(Vii) On the other hand, the optimum frequency for drawing in consideration of the time constant and throughput of the deflector such as the condenser and lens of the drawing device, and the frequency that cannot be detected due to the unique time constant of the reflected beam detector. In addition, when performing multiple drawing, the frequency that minimizes the total noise component is υ, υ / 2, based on the results of monitoring the reflected beam amount.
At least one or more is selected from the frequencies υ / 3, ... υ / n. (viii) Drawing is performed by setting the drawing time and drawing waiting time (settling time) according to the frequency obtained in (vii) above.

Next, as a ninth embodiment, a drawing method according to specific noise detection will be described. Here, the noise according to the beam size in the Y direction obtained in the fifth embodiment will be described. At the noise frequency of 0.7 MHz obtained in the fifth embodiment, the detection accuracy is several tens of kHz.
z. In order to improve the detection accuracy, beats are repeatedly measured at a frequency around 0.7 MHz, for example, 701 kHz and 702 kHz, and a more accurate noise frequency is obtained. This operation is performed until the beat is no longer detected, for example, on the order of 0.001 Hz. Through such steps, it is possible to know the exact value of the noise frequency.

Hereinafter, an example of the analysis result of the beam size and the beam position in the Y direction will be described. As a result of noise frequency analysis,
0.702159216MHz, 0.82000031
There are two types of noise frequencies of 2 MHz. The respective fluctuation amounts are shown in FIG.

The results as described above are stored in the control computer 37 of FIG. 5, for example. Next, the control computer 37 selects the noise frequency (here, 0.702 MHz) that shows the largest value of the beam position deviation variation and the beam size variation (here, 90 nm of the beam position variation). .

After that, a cycle (1.4282465) which is an integral multiple of the reciprocal of the frequency of the noise selected in the control computer 37.
The irradiation time and irradiation waiting time (settling time) corresponding to 72 ns, 2.856493144 ns, ... At that time, the settling time is set to be the minimum condenser lens time constant (here, 250 ns) or more, and in consideration of the throughput, the settling time is set to the most condenser lens time constant among the selected noise frequencies. Close things (1.4282465472 × 176 = 251.3
713967 ns) to set the sequence of the control computer. By setting such a value as the settling time, it is possible to perform drawing with good drawing efficiency and at a frequency synchronized with an integer fraction of the noise frequency.

A clock is mounted on the drawing apparatus as described above. This is because, when the time from one shot to the next shot is rate-controlled by the movement of the stage, it is conceivable that the settling time set above and the timing of drawing start are deviated. However, the accurate frequency of the noise detected above is monitored by the clock from the start of drawing, and even if there is stage movement, it is controlled so that shots are only made at the set frequency. Therefore, it is possible to suppress the dimensional variation within the wafer surface.

When a 6-inch mask was drawn in the above sequence, the in-plane variation was greatly reduced to 0.84 μm (3σ) in the conventional case and 0.24 μm in the drawing method.

The drawing method described above is not limited to the removal of one noise component. Basically, high-frequency noise is mainly removed, but for example, when a plurality of noise components are present in the drawing device, or when the drawing start time is the same in the first drawing, the second drawing ... In the case of applying the multiple drawing method of monitoring the clock so as to have a phase state and adjusting the shot to the frequency of the noise obtained from the analysis result to the present invention, in any case, it is generated in the drawing device from the obtained monitor result. It is also possible to select and draw at least one frequency from among the frequencies of υ, υ / 2, υ / 3, ... υ / n that minimizes the total noise component.

Further, in order to remove high frequency noise, when the frequency for drawing is determined from υ, υ / 2, υ / 3, ... υ / n, for example, here, an electron beam reflection detector, etc. 0.1MH when the time constant is 100kHz
It is also effective to draw by selecting a value that does not fall below z.

By the drawing method described above, it is possible to eliminate high-frequency noise that has a great influence on dimensional variations, and reduce dimensional variations and edge roughness in the mask and wafer planes.

That is, regarding the noise generated in the pattern drawing device, the mark is irradiated with a beam at two or more types of frequencies using two types of noise detection marks, and the reflected or transmitted beam intensity is detected to determine the type of noise. Specify the magnitude and frequency, select the frequency of the noise component with the largest fluctuation amount from the detected noise, select an appropriate frequency from the integer multiples of the reciprocal of that frequency, and draw at that frequency. As a result, the settling time can be adjusted, and it becomes possible to perform drawing while removing high-frequency noise generated in the drawing apparatus, and it is possible to reduce edge roughness and dimensional variation of the mask and wafer. Further, depending on the frequency selection method, not only high-frequency noise but also low-frequency noise can be efficiently removed and drawing can be performed.

Next, as a tenth embodiment, detection of mark positions according to the drawing method of the drawing apparatus as described above will be described. A pattern forming technique using an electron beam drawing apparatus needs to precisely control a forming position as a semiconductor device pattern is miniaturized. Usually, a registration mark for determining a beam position is formed around a region for drawing a desired pattern, and the beam position is determined with reference to the mark coordinates to form a pattern.

With the miniaturization of semiconductor device patterns,
Beam position repeatability requirements are approaching the angstrom region. In order to perform beam positioning with high accuracy, the detection reproducibility of the mark position and at the same time higher accuracy are required.

FIG. 17 is a block diagram showing a mark detecting method. Mark detection is performed by the reflection signal obtained when the beam is scanned over the mark. In the figure, the reflection signal obtained when the beam 52 is scanned in the direction of the arrow 53 on the mark 51 on the wafer 50 is as shown in FIG. When such signals are added up for the number of scanning times and averaged, and further differentiated, a waveform as shown in FIG. 18B is obtained. The points X ₁ and X _{2 at} which the waveform passes the apex are obtained, and the average value Xc is determined as the X coordinate of the mark. Alternatively, FIG. 18 (a)
The X coordinate of the center of gravity on the I-x plane may be defined as the X coordinate of the mark.

By the way, in the drawing apparatus, as described in the related art, there are various error generation factors that hinder the accuracy.
One of the causes is that it is placed in the environment of external magnetic field fluctuations and floor vibrations, and there is also fluctuation of the control signal due to power supply noise and signal system noise. Therefore, the beam vibrates with a certain amplitude with respect to the sample.

Now, as an example, the vibration of disturbance (noise) is 25
Consider 0 Hz. On the other hand, if the frequency of the trigger for scanning the beam is 250 Hz, the coordinates of the mark to be obtained are offset depending on the beam scanning start time. This situation will be described with reference to FIG. For the sake of simplicity, it is assumed that the time for one beam scan is sufficiently shorter than the period of vibration considered.

In FIG. 19, the vibration amplitude is Δ.
When the scanning is started at the times indicated by A and D for the vibration waveform, the scanning is started in the same phase with respect to the vibration thereafter, so that the vibration is not affected. On the other hand, when the scanning is started at the times indicated by B and C, the mark coordinates deviated by nΔ and −nΔ are given. Therefore, the maximum mark detection error is 2nΔ. If the trigger frequency is, for example, 249.9 Hz, a mark detection error will occur if the average of 2500 times is not obtained. That is, the error increases in proportion to the number of scans.

Typical disturbances include the fundamental frequency of commercial power used for the power supply of the system of the drawing apparatus, that is, 50 Hz, 60 Hz or their harmonics.

As described above, when the trigger timing of beam scanning for mark detection coincides with or is close to the period of disturbance, there is a problem that an error occurs in the obtained mark coordinates, and a countermeasure is required. Therefore, in this embodiment, the timing of triggering the beam scanning for mark detection is set so that the influence of the disturbance is canceled out evenly. This will be described below with reference to the drawings.

FIG. 20 is a sine waveform diagram showing a disturbance in the drawing apparatus. The waveform of the disturbance is separated into sine waves, and the components of different frequencies can be regarded as different disturbances. As shown in the figure, one type of disturbance is a problem for simplicity, and its frequency is f. Further, the number of beam scans is two, and the respective scan start times are t ₁ and t ₂ (t ₂ > t ₁ ). At this time, t ₁ and t ₂ are determined so that the following expression exp (i (2πft ₁ )) + exp (i (2πft ₂ )) = 0 (27). To satisfy this condition, t ₂ = t ₁ + (n + 1/2) T (28) In formula (28), n is 0 or a natural number,
T = 1 / f.

FIG. 20 shows the case where n = 0, 1 (1/2
When shifting the cycle). A, B, C, D represent the first scan start time in different phases for each vibration,
A ', B', C'and D'represent the second scanning start time when n = 0 corresponding to each. A ″, B ″,
C ″ and D ″ represent the second scanning start time when n = 1. In either case, averaging the results of the two scans
The effects of disturbance are eliminated.

Similarly, when scanning is performed n times, when the start time of the k-th scanning is t _k , Σ exp (i (2πft _k )) = 0 (29) so that t _k Should be set. As a solution, for example, t
_{It is possible to set k 1} = kτ + T0 and τ = (N / M) (1 / f). However, N and M are relatively prime natural numbers and M is 1.
is not. There is-taking of Additional t _k is omitted can be easily understood.

Next, a case will be described in which there are two types of disturbances to be problematic and the frequencies are given by f ₁ and f ₂ . Conditions t _k satisfies in this case is of the formula. Σ exp (i (2πf ₁ t _k )) = Σ exp (i (2πf ₂ t _k )) = 0 (30) In this case, the condition that τ must satisfy is t _k = kτ + T0, and (M ′ / N ') (1 / f ₁ ) = (M ° / N °) (1 / f ₂ ) ... (31) However, N ′ and N ° are not divisors of N, N ′ and M ′, and N ° and M ° are pairs of natural numbers that are relatively prime. Assuming that p and q are natural numbers that are relatively prime to each other, if f ₁ = (p / q) f ₂ is satisfied, M ′, M ° and N ′ are set so that pM ° N ′ = qM′N °. , N ° should be set.

If the ratio of f ₁ and f ₂ cannot be expressed by a fraction, it cannot be strictly expressed by the above condition, but even in that case, it can be approximated by the irreducible fraction with the required accuracy. For example, when τ = ((s / o) + Δ) / f2 (32), Δ << s / o may be satisfied.

As an example, f ₁ = 50 Hz, f ₂ = 75H
The case of z will be described. f ₁ = (2/3) f ₂ . The condition to be obtained is 2M ° N ′ = 3M′N °. N ° =
2, N ′ = 3, M ′ = 5, M ° = 5 satisfy this condition.

Further, a general case will be described.
The frequencies of the m types of disturbances in question are f ₁ , f ₂ , f ₃ ,
... and _{f m.} Similar to the discussion so far, they are irreducible fractions s ₁ , s ₂ , s ₃ , ... S _{m with} respect to the reference frequency f ₀ .
Are represented as s ₁ f ₀ , s ₂ f ₀ , s ₃ f ₀ , ... S _m f ₀ . Strictly speaking, some things cannot be represented by irreducible fractions, but similar to the above discussion, irreducible fractions provide the required accuracy.

The condition that sufficient accuracy can be obtained by detecting n times is as follows: i = 1,2,3, ... m when the detection interval is t _0, and s _i · f ₀ · t ₀ = q _i / p _i (33) (p _i and q _i are mutually prime natural numbers, where p _i ≠ 1 and n · s _i · f ₀ · t ₀ = k (k is a natural number)).

Here, it is desirable that r + 1/2 <q _i / p _i <r + 3/2 (34), where r is a natural number.

Therefore, by setting the beam scanning trigger time for mark detection as defined in the present invention, it is possible to substantially eliminate the mark position detection error due to periodic disturbance without increasing the number of detection times.

In the tenth embodiment, when drawing is performed by the drawing apparatus, the mark position is detected particularly to reduce the fluctuation of the beam position, and the influence of disturbance, that is, noise, is averaged over the entire drawing. Since it acts so as to cancel, it is effective for multiple drawing. As the method of measuring the frequency of the disturbance (noise), the noise detection method of the present invention described above may be used. However, the method of measuring the noise frequency is not limited. In addition, it is also possible to know the frequency of noise by actually exposing a straight line to a resist-coated sample and measuring the fluctuation of the finished resist pattern from the straight line. Further, even when the stage is moved at the time of drawing, if the deflector is controlled so that the beam can follow the movement of the mark in response to the movement of the stage, the noise can be easily detected by using the noise detecting method of the present invention.

The drawing apparatus according to the tenth embodiment also provides a drawing method for removing disturbance (noise) as much as possible for various drawing apparatuses such as an electron beam drawing apparatus and a laser drawing apparatus.

[0122]

As described above, according to the present invention,
Irradiate the pattern of the noise detection mark with an electron beam,
The reflected electron intensity causes a beat between the shot frequency and the shot noise frequency. The noise detection method that changes the frequency of the electron beam and analyzes the frequency of the electron beam is effective for identifying the frequencies of a plurality of noises generated in the drawing device, and can detect high-frequency noises that could not be detected until now. It has become possible to perform with high precision and speed.

Depending on the frequency, it is easy to identify the cause of noise and the place of occurrence. In addition, it is possible to estimate the amount of change in shot size and the amount of positional deviation of shots. These can be reduced by making various adjustments to the drawing device and by examining the drawing method, thus improving the stability of the drawing device. Contribute.

That is, since the type of the noise (variation of beam size or variation of beam position deviation) can be specified for the noise, it is possible to selectively control the noise removal at the time of drawing, and stable control of the drawing apparatus is possible. Becomes
Further, it is possible to realize an accurate drawing apparatus that removes an error from the coordinates at the time of detecting a mark and does not give a positional variation as much as possible at the time of drawing.

[Brief description of drawings]

FIG. 1A and FIG. 1B are respectively the first of the present invention.
FIG. 6 is a characteristic diagram showing beam intensities as a result of frequency analysis according to incident beams having different frequencies in the embodiment of FIG.

FIG. 2 is a diagram showing an example of setting a frequency of an incident beam for improving a measurement accuracy of a noise frequency according to the second embodiment.

FIG. 3 is a characteristic diagram showing an example of modulation of electron beam intensity.

FIG. 4 is a pattern plan view showing one of the noise detection marks according to the present invention regarding the third embodiment.

FIG. 5 is a schematic configuration diagram showing an electron beam drawing apparatus to which the present invention is applied in relation to the fourth embodiment.

FIG. 6A, FIG. 6B, FIG. 6C, and FIG. 6D are pattern plan views showing examples of the noise detection mark of the present invention related to the respective embodiments.

7 (a), (b), and (c) are characteristic diagrams showing beam intensities of respective frequency analysis results according to incident beams having different frequencies, respectively, regarding the fifth embodiment.

8A and 8B are characteristic diagrams showing beam intensities as a result of frequency analysis according to incident beams having different frequencies, respectively, according to the fifth embodiment.

9A, 9B, and 9C are characteristic diagrams showing beam intensities of respective frequency analysis results according to incident beams having different frequencies in the fifth embodiment.

10A and 10B are characteristic diagrams showing beam intensities as a result of frequency analysis according to incident beams having different frequencies, respectively, relating to the fifth embodiment.

11A and 11B are diagrams for explaining an analysis procedure for specifying the type and magnitude (variation amount) of noise, respectively, according to the fifth embodiment.

FIG. 12 is a schematic configuration diagram showing a laser drawing apparatus to which the invention is applied in relation to the sixth embodiment.

13 (a), (b), (c), and (d) are characteristic diagrams showing beam intensities of respective frequency analysis results according to incident beams having different frequencies in the sixth embodiment. .

FIG. 14A and FIG. 14B are characteristic diagrams showing noise intensity for specifying the type and magnitude (variation amount) of noise, respectively, according to the sixth embodiment.

FIGS. 15 (a) and 15 (b) are views showing an example of beam irradiation to a detection mark for explaining another example of the beam intensity modulation method according to the seventh embodiment.

FIG. 16 is a diagram showing, as a specific example, an analysis result example of noise in the beam size and beam position in the Y direction as a ninth embodiment.

FIG. 17 is a configuration diagram showing a mark detection method in the drawing device.

18 (a) is a waveform diagram showing a reflection signal at the time of beam scanning by the mark detection of FIG. 17, FIG. 18 (b).
Is a waveform diagram when an average of the total number of scans by mark detection is taken and further differentiated.

FIG. 19 is a waveform diagram showing a trigger timing when a beam is scanned for vibration of disturbance (noise).

FIG. 20 is a waveform chart showing a disturbance in the drawing apparatus for explaining the timing of the trigger when scanning the beam according to the tenth embodiment.

21A and 21B are plan views showing beam intensity detection patterns in a conventional drawing apparatus, respectively.

[Explanation of symbols]

4, 4-1, 4-2, 5-1, 5-2, 14 ... Noise detection mark (pattern) 10 ... Sample chamber 11 ... Target 12 ... Sample stand 13 ... Mark support stand 15 ... Backscattered electron detector 16 Reference pattern 20 Electron optical column 21 Electron gun 22a to 22e Various lens systems 23 to 26 Various deflection systems 27a Blanking plates 27b and 27c Beam shaping aperture mask 31 Sample stage drive circuit 32 Laser measurement system 33 Deflection control circuit 34 Variable beam size control circuit 36 Buffer memory and control circuit 37 Control computer 38 Data conversion computer 39 CAD system 40 Monitor and control circuit 42 Function Generator 44 ... Photomultiplier

Continued Front Page (72) Inventor Hitoshi Sunao, 33 Shin-isogo-cho, Isogo-ku, Yokohama-shi, Kanagawa, Ltd.Inside Toshiba Industrial Technology Research Institute, Inc. (72) Inventor Kenichi Murooka, 72, Horikawa-cho, Kawasaki-shi, Kanagawa Toshiba Kawasaki Plant (72) Inventor Munehiro Ogasawara 72 Horikawa-cho, Sachi-ku, Kawasaki-shi, Kanagawa Stock Company Toshiba Kawasaki Plant (72) Inventor Shinsuke Nishimura Komukai-Toshiba, Kawasaki-shi, Kanagawa 1-share company Toshiba Research and Development Center (72) Inventor Yuji Fukudome, 1 Komukai Toshiba Town, Saiwai-ku, Kawasaki City, Kanagawa Prefecture Corporate Research and Development Center, Toshiba Corporation (72) Inventor Noriaki Nakayamada Komukai Toshiba Town, Kawasaki City, Kanagawa Prefecture No. 1 in the Corporate Research & Development Center of Toshiba Corporation (72) Iwa Higashikawa No. 1 in Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa In the Corporate Research & Development Center of Toshiba

Claims (8)

[Claims] 1. A detection step of irradiating a noise detection mark prepared in a beam drawing apparatus with a beam at a predetermined frequency and storing a signal of a beam reflected or transmitted through the monitor, and the detection step in which the predetermined frequency is changed. And a step of performing a step of performing the following, and managing the performance of the beam drawing apparatus by identifying the frequency of noise and its magnitude by using the monitoring result of each detection step and the information obtained by frequency analysis. Noise detection method in device. 2. A detection step of irradiating two types of noise detection marks prepared in a beam drawing apparatus with a beam at a predetermined frequency and storing the signal of the beam reflected or transmitted by the monitor in the monitor step. The detection step is performed for two or more kinds of the predetermined frequencies that include at least one frequency that does not fall within the measurement range, and the frequency of noise is obtained by performing frequency analysis and comparison from the monitor results of each of the detection steps and the noise. A method for detecting noise in a drawing apparatus, characterized in that the performance of the beam drawing apparatus is managed by analyzing the size of the beam drawing apparatus. 3. A line-symmetrical two pattern provided on the substrate and spaced so that a beam is applied to each part of the two, and the same shape as one of the two patterns provided on the substrate. And a noise detection mark in a drawing apparatus. 4. A support table provided in a drawing apparatus using a beam, two line-symmetrical patterns provided on the support table and spaced so that the beam is applied to a part of each of the two, and the support table. And a pattern having the same shape as one of the two patterns, wherein atoms forming the support base and atoms forming the pattern are different from each other. mark. 5. A means provided with a noise detection mark for use in noise detection in a beam drawing apparatus, an irradiation means for repeatedly irradiating the mark with a beam at a predetermined frequency, and reflection by the irradiation means according to the mark. Alternatively, monitor means for capturing the signal of the transmitted beam at a predetermined cycle, and arithmetic means for recognizing the peak frequency and its peak size from the result of frequency analysis of the signal captured by the monitor means, or only the peak frequency, Control means for changing a predetermined frequency of the beam so as to include at least one frequency higher than a measurement limit with respect to a predetermined period of the monitor means, and using the control means for a beam having two or more kinds of frequencies. By executing the arithmetic means and comparing each recognized data, Drawing apparatus and obtaining the frequency of the noise type and noise generated in the location and its size, or the frequency of the noise. 6. A means provided with a noise detection mark for use in noise detection in a beam drawing apparatus, an irradiation means for repeatedly irradiating the mark with a beam at a predetermined frequency, and reflection by the irradiation means according to the mark. Alternatively, monitor means for capturing the signal of the transmitted beam at a predetermined cycle, and arithmetic means for recognizing the peak frequency and its peak size from the result of frequency analysis of the signal captured by the monitor means, or only the peak frequency, Control means for changing a predetermined frequency of the beam so as to include at least one frequency equal to or higher than a measurement limit with respect to a predetermined cycle of the monitor means; The reference result is the result of the calculation means when the mark is irradiated onto the mark. And means for pre-held as data, wherein the calculating means for one of the predetermined frequency is performed by comparing with the reference data, as well as identifying the frequency of the noise,
Further, the drawing device is characterized in that the calculation means for another example of the predetermined frequency is executed, and the magnitudes of noises are analyzed by comparing intensities with each other. 7. A means having a noise detection mark for use in noise detection in a beam drawing apparatus, an irradiation means for repeatedly irradiating the mark with a beam at a predetermined frequency, and a reflection means for reflecting the mark by the irradiation means. Alternatively, monitor means for taking in the signal of the transmitted beam at a predetermined cycle, control means for changing the predetermined frequency of the beam so as to include at least one frequency higher than the measurement limit for the predetermined cycle of the monitor means, Frequency analysis is performed on each of the signals captured by the monitor for the beams of two or more types of frequencies using the control means, the peak frequency and the magnitude of the peak are recognized from the results, and each recognized data is compared. Depending on the frequency of noise generated in the device, the type of noise and the magnitude of noise. 1 / υ, 2 / υ, 3 / which is an integer multiple of the cycle of the noise having the maximum noise level as a result of the calculation means.
ν, ... N / υ is calculated, and a frequency having a period larger than at least the time constant of the circuit controlling the deflector used in the drawing device is set to the period 1 / υ, 2 / υ, 3 / υ, ... N. /
Frequency determined according to υ, υ / 2, υ / 3, ... υ
A drawing method of a drawing apparatus, characterized by selecting from / n and drawing at that frequency. 8. A mark on a sample is detected by irradiating a beam on a sample with a beam in a beam drawing apparatus and detecting a mark position using a secondary signal corresponding to the beam obtained by scanning a plurality of times. In the method of positioning and drawing, when the timing for starting the beam scanning for the k-th mark detection is t _k , the total number of beam scanning times is n, and one frequency of the disturbance that changes the beam position is f, so that exp (i (2πft _k )) becomes almost 0, t _k
And a beam position is determined for the sample at a frequency having the timing of t _k , and the sample is drawn.