JP2008078394A - Electron-beam lithography method and electron-beam lithography device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a pattern-dimension error due to manufacturing variations in underlying layers. <P>SOLUTION: An electron-beam lithography method is used for exposing a resist formed on a layer to be processed in order to process the layer to be processed formed on the underlying layer having a pattern and a mark. The method includes a step (S403) of obtaining a reflected electronic signal by scanning an electron beam on the mark, steps (S404, S405) of correcting at least one of parameters that define an area density of the pattern and a relation between the area density of the pattern and an irradiation amount of the electron beam on the basis of the reflected electronic signal, a step (S407) of determining the irradiation amount of the electron beam on the basis of the area density of the pattern and the relation between the area density of the pattern and the irradiation amount of the electron beam after correction, and a step (S408) of exposing the resist with the determined irradiation amount of the electron beam. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electron beam exposure method and exposure apparatus for performing electron beam lithography on a resist layer on a base having a plurality of lower layer structures such as a wiring / hole structure made of a metal material.

  Conventionally, an optical lithography technique advantageous in terms of cost and throughput has been mainly used as a lithography tool in a large scale integrated circuit (LSI). However, higher mask costs associated with the recent miniaturization and higher integration of pattern sizes, and the increase in mask costs associated with increased design revisions are problems.

  Therefore, electron beam lithography having a pattern generation capability has attracted attention. In the electron beam lithography, when the pattern is changed due to the design correction, it is possible to easily cope with the change of the drawing data alone. For this reason, electron beam lithography is used in production sites as a lithography tool for early-stage engineering sample (ES) products that may undergo design changes and small-volume production lots.

  By the way, for example, when electron beam exposure is performed on a resist layer on a base having a plurality of lower layer structures such as a wiring / hole structure made of a metal material such as W, Al, and Cu, the electron beam incident on the resist Not only will it be scattered from the underlying layer.

  Therefore, the irradiated electron beam has a stored energy distribution due to “forward scattering” scattered by the constituent atoms of the resist and “backward scattering” transmitted through the resist and scattered from the underlying structure, and is drawn (processed). Depending on the environment of the surrounding pattern in the layer and the environment of the lower layer structure, a dimensional difference occurs between the patterns. This phenomenon is called “proximity effect” and causes a problem in dimensional accuracy.

  The energy stored in the resist is described by the following equation (1) as the sum of Gaussian distributions of forward scattered electrons and back scattered electrons.

f (r) = 1 / [π (1 + n)] * (exp [−r ² / β _f ² ] / β _f ² + η * exp [−r ² / β _b ] / β _b ² ) (1 )
Here, r, β _f, β _b and η are r: distance from the electron incident position, β _f : forward scattering diameter, β _b : back scattering diameter, and η: ratio of back scattering energy to forward scattering energy, respectively. To express.

In particular, in a high acceleration electron beam (several tens to several hundreds of keV), electrons incident on the resist pass through the resist, reach the base substrate, are reflected from the substrate, and are again exposed to the resist. Since the spread β _{b of the} reflected electrons reaches several μm to several tens of μm, the backscattered electrons from the base are exposed not only to the irradiated electron beam shot but also to the surrounding pattern, resulting from the backscattered electron intensity distribution With a resist pattern error distribution.

Furthermore, since β _{b and} η vary depending on the type, thickness, depth from the resist, etc. of the material constituting the underlayer, the proximity effect correction is performed by changing the coefficient for obtaining the backscattered electron intensity according to the underlayer structure. There is a need to do.

  Considering the case where electron beam lithography is applied to the LSI lithography process, a plurality of wiring layers and hole layers exist under the resist layer to be patterned. The electrons transmitted through the resist are scattered back to the resist by the wiring of the underlayer and the metal pattern of the hole layer, so that the electron intensity distribution in the resist is obtained with a simple Gaussian distribution as shown in Equation (1). I can't do that.

  Therefore, in order to increase the dimensional accuracy on a base substrate having a lower layer structure, “proximity effect correction” in consideration of the lower layer structure is required. For example, a method (corrected area density method) that takes into account the influence of backscattered electrons from a lower layer structure of a resist layer and one layer has been proposed (see, for example, Patent Document 1). Furthermore, a method that considers the influence from a plurality of underlayers has been proposed (see, for example, Patent Document 2).

For example, Patent Document 1 proposes that the influence of backscattered electrons from the underlayer of the W / SiO ₂ layer in which W (tungsten) holes are formed is obtained by the following equation (2) by the area density method. ing.

α (α _w · η _w + (1−α _w ) η _SiO2 ) (2)
Here, α is the drawing pattern density, α _{w is} the density of the W pattern in the underlayer, η _w is the η value in the W 100% base, and η _SiO2 is the η value in the SiO ₂ 100% base.

Patent Document 2 proposes obtaining the backscattered electrons from the underlayer on which the Al film is formed on the W / SiO ₂ layer in which the W holes are formed by the following equation (3).

r _w α _w + t _w ² α _w r _Si ² +2 t _w t _SiO 2 α _w (1-α _w ) r _Si + t _SiO ^{2 2} (1-α _w ) ² r _Si + r _SiO ² (1-α _w ) (3)
Where α _{w is} the density of the W pattern of the underlayer, t _w is the electron transmittance in the W layer, t _SiO2 is the electron transmittance in the SiO ₂ layer, r _w is the electron reflectivity in the W layer. , R _SiO2 : reflectivity of electrons in the SiO ₂ layer, r _Si : reflectivity of electrons in the Si layer. In this method, it is said that high accuracy can be achieved by considering reflection and transmission in each layer of the underlayer.

Although the methods of Patent Documents 1 and 2 shown above are different, the method of Patent Document 1 uses parameters such as α _w , η _w , and η _SiO 2, and the method of Patent Document 2 uses the reflectance and transmission in each layer. The parameters such as the rate are common in that values are determined in advance through experiments and simulations and used.

By the way, especially in metal materials with a relatively large number of atoms used for wiring and hole layers such as W and Cu, fluctuations in the “finished dimensions” of the pattern caused by variations in the manufacturing process between lots and wafers, The backscattered electron intensity varies greatly due to variations in the metal film thickness. Therefore, there has been a problem that an error in proximity effect correction occurs according to the structure of the actually formed base, thereby causing an error in pattern dimensions.
JP 2004-31836 A JP 2005-101501 A

  The present invention provides an electron beam exposure method and an electron beam exposure apparatus capable of reducing a pattern dimension error caused by manufacturing variations of an underlayer.

  In the electron beam exposure method according to the first aspect of the present invention, a resist formed on the processing layer is exposed in order to process the processing layer formed on the base layer having a pattern and a mark. An electron beam exposure method comprising: scanning a mark with an electron beam to obtain a reflected electron signal; and, based on the reflected electron signal, the area density of the pattern, and the area density of the pattern and the electron beam. Correcting at least one of the parameters for determining the relationship with the irradiation amount of the electron beam, and after the correction, based on the area density of the pattern and the relationship between the area density of the pattern and the irradiation amount of the electron beam A step of determining an irradiation amount of the beam, and a step of exposing the resist with the electron beam of the determined irradiation amount.

  An electron beam exposure method according to a second aspect of the present invention is a multilayer structure having a plurality of underlayers having patterns and marks, and the marks are formed on the multilayer structure so as not to overlap each other. An electron beam exposure method for exposing a resist formed on the processing layer to process the formed processing layer, wherein a reflected electron signal is emitted by irradiating the plurality of marks with an electron beam. And correcting at least one of an area density of the plurality of patterns and a parameter defining a relationship between the area density of the plurality of patterns and an irradiation amount of the electron beam based on the reflected electron signal; After the correction, the electron beam irradiation amount is determined based on the area density of the plurality of patterns and the relationship between the area density of the plurality of patterns and the electron beam irradiation amount. Including that a step, and a step of exposing the resist with an electron beam of the determined dose.

  An electron beam exposure apparatus according to a third aspect of the present invention exposes a resist formed on a processing layer in order to process the processing layer formed on a base layer having a pattern and a mark. An electron beam exposure apparatus that scans an electron beam on the mark to obtain a reflected electron signal, and based on the reflected electron signal, the area density of the pattern, and the area density of the pattern and the electron beam Means for correcting at least one of the parameters for determining the relationship with the irradiation amount of the electron beam, and after the correction, the area density of the pattern and the relationship between the area density of the pattern and the irradiation amount of the electron beam, Means for determining the irradiation amount of the beam, and means for exposing the resist with the electron beam of the determined irradiation amount.

  ADVANTAGE OF THE INVENTION According to this invention, the electron beam exposure method and electron beam exposure apparatus which can reduce the pattern dimension error resulting from manufacture dispersion | variation in a base layer can be provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of an electron beam exposure apparatus 10 according to an embodiment of the present invention. The electron beam exposure apparatus 10 uses the first and second shaping apertures 105 and 108 to perform exposure while variably controlling the size of the electron beam.

  The electron beam emitted from the electron gun 101 is adjusted in current density and Koehler illumination conditions by the first condenser lens 103 and the second condenser lens 104, and uniformly illuminates the first shaping aperture 105.

  The image of the first shaping aperture 105 is formed on the second shaping aperture 108 by the first projection lens 106 and the second projection lens 107. A plurality of openings for shaping the electron beam are provided on the second shaping aperture 108 and pass through a part of the openings in accordance with the dimensions defined in the drawing layer (processed layer) pattern data. The position is irradiated with an electron beam.

  The irradiation shape of the electron beam is controlled by controlling the beam irradiation position on the second shaping aperture 108 by deflecting the electron beam by the shaping deflection system. The shaping deflection system includes a shaping deflector 109, a shaping deflection amplifier 120, and a pattern decoder 119 that sends deflection data to the shaping deflection amplifier 120.

  The electron beam that has passed through the second shaping aperture 108 is reduced and projected by the reduction lens 110 and the objective lens 111 and is imaged on the semiconductor substrate 112. The irradiation position of the electron beam on the semiconductor substrate 112 is controlled by the objective deflector 113.

  The objective deflector 113 is controlled by an objective deflection amplifier 121 that applies a voltage to the objective deflector 113 based on the position data sent from the pattern data decoder 119. The semiconductor substrate 112 is placed on a movable stage 116 together with a Faraday cup 114 and an electron beam measurement mark table 115. By moving the movable stage 116, the semiconductor substrate 112, the Faraday cup 114, or the mark base 115 can be selected.

  When the position of the electron beam on the semiconductor substrate 112 is moved, the electron beam is deflected by the blanking electrode 130 and cut by the blanking aperture 131 so that unnecessary portions on the semiconductor substrate 112 are not exposed. Do not reach 112. The deflection voltage to the blanking electrode 130 is controlled by the blanking amplifier 122 based on the position data sent from the pattern data decoder 119.

  A proximity effect correction module 124 that corrects the proximity effect is installed between the pattern data decoder 119 and the blanking amplifier 122. Drawing control data such as a drawing layer (processed layer) pattern or underlayer pattern data is stored in the pattern data memory 118.

  FIG. 2 is a diagram showing a connection state between the proximity effect correction module 124 and the detector 126 omitted in FIG. 1 and a more detailed configuration of the proximity effect correction module 124.

  The proximity effect correction module 124 includes an area density calculation unit 140, an area density map memory 141, and a dose correction calculation unit 142 as shown in FIG. The proximity effect correction module 124 is further connected to a proximity effect correction parameter generation module 152.

  The signal from the detector 126 is processed by the signal waveform processing module 151, and information obtained there is provided to the proximity effect correction parameter generation module 152 connected to the signal waveform processing module 151. The proximity effect correction parameter generation module 152 includes a correspondence relationship between the mark signal intensity and the proximity effect correction parameter within the range of manufacturing variations of the assumed lower layer structure obtained in advance through experiments and simulations, for example. Yes.

  In the electron beam exposure apparatus 10, the electron beam exposure methods according to the first and second embodiments of the present invention described in detail below are executed.

(First embodiment)
An electron beam exposure method according to the first embodiment of the present invention will be described with reference to FIGS.

In this embodiment, as shown in FIG. 3, the layer to be processed is formed on the W / SiO ₂ layer (W plug layer) 31 which is a base layer in which W (tungsten) holes are formed on the silicon substrate 30. An Al film layer 32, an SiO ₂ layer 33, and a resist 34 are formed in this order. Here, a case where electron lithography is performed on the resist 34 and a wiring pattern is formed on the Al film layer 32 using the SiO ₂ layer 33 as a hard mask is considered as an example.

  FIG. 4 is a flowchart showing the electron beam exposure method according to the present embodiment.

  First, the design data is converted into EB drawing data and stored in the pattern data memory 118 (step S401).

  Next, the pattern decoder 119 reads the drawing layer (processed layer) pattern stored in the pattern data memory 118 and the pattern data of the underlying layer, and decomposes them into graphic dimensions and coordinates for each unit area to thereby produce a proximity effect. Provide to the correction module 124. The area density calculation unit 140 of the proximity effect correction module 124 calculates the area density of the pattern of the drawing layer and the underlayer based on the given data (step S402). The calculation result is stored in the area density map memory 141.

  A proximity effect correction mark as shown in the top view of FIG. 5 is formed on the underlying layer 31 of the semiconductor substrate 112 placed on the movable stage 116 so as not to overlap with the W plug pattern as shown in FIG. Patterns 501 to 503 are formed.

  FIG. 5 shows isolated line marks 501 (sparse pattern), line-and-space marks 502 (density 50% pattern), and isolated space marks 503 (dense pattern) having different area densities as proximity effect correction mark patterns. It is shown. Only one type of proximity effect correction mark may be formed, but the accuracy is improved by providing a plurality of proximity effect correction marks.

  Prior to EB drawing, these proximity effect correction mark patterns 501 to 503 are scanned with an electron beam, and a reflected electron signal is detected by the detector 126 (step S403). Since the resist 34 immediately above the proximity effect correction mark patterns 501 to 503 is exposed by this scan, the proximity effect correction mark patterns 501 to 503 need to be formed at positions that do not overlap the drawing area.

  By analyzing the reflected electron signal waveform detected by the detector 126 by the signal waveform processing module 151, the “finished dimension” of the mark pattern is obtained from information corresponding to the width of the proximity effect correcting mark pattern. Based on the obtained finished dimension information, the area density of the pattern data of the underlayer is corrected. That is, the area density map of the pattern data of the underlying layer stored in the area density map memory 141 is corrected in accordance with the actual finished dimensions (step S404).

  Further, by analyzing the reflected electron signal waveform detected by the detector 126 by the signal waveform processing module 151, the “reflected electron intensity” of the underlayer is obtained from the signal intensity of the reflected electron signal from the proximity effect correction mark. From the obtained reflected electron intensity, the proximity effect correction parameter generation module 152 generates a proximity effect correction parameter corresponding to the actual reflected electron intensity from the underlayer (step S405).

  For example, if it is known in advance that the amount of correction of the area density of the underlying layer pattern data is small, step S404 is omitted, that is, the area density of the underlying layer pattern data is not corrected. Only the proximity effect correction parameter may be generated based on the reflected electron signal. In some cases, conversely, step S405 may be omitted and only correction of the area density of the pattern data of the underlayer may be performed.

Here, the proximity effect correction parameter described above will be described. An appropriate irradiation amount (irradiation energy) D in the case of drawing an electron beam on a resist having a base structure is, for example, as shown in the correction formula (4) of Patent Document 1 (Japanese Patent Laid-Open No. 2004-31836).
D = C / {1/2 + η [α + (η ₁ / η−1) α · α ₁₀ ]} (4)
It is expressed. Here, C: constant, η: ratio of backscattering energy to irradiation energy, η ₁ : ratio of backscattering energy to incident energy of the underlayer material, α: drawing layer pattern area density, α ₁₀ : underlayer pattern area density It is.

The proximity effect correction parameter is, for example, η ₁ in this case. As shown in Expression (4), η ₁ is a parameter that determines the relationship between the area density α ₁₀ of the underlayer pattern and the electron beam irradiation amount D.

  A specific example of generating the proximity effect correction parameter corresponding to the reflected electron intensity from the underlayer will be described below.

Each parameter of Expression (4) when the film thickness of the underlayer is, for example, 400 nm and 600 nm is obtained in advance by experiment or simulation. In this case, the proximity effect correction parameter η ₁ takes different values depending on the film thickness at 400 nm and 600 nm.

  On the other hand, if the reflected electron signal waveform for a mark with a known film thickness is a waveform such as the reference waveform 602 in FIG. 6, for example, the signal intensity with the signal waveform 601 obtained for the actually created underlayer From this ratio, the film thickness of the actually created underlayer can be estimated. Here, it is known that the stronger the signal intensity, the thicker the film thickness.

Therefore, in order to obtain the proximity effect correction parameter η ₁ with respect to the actual film thickness, for example, using the value of the proximity effect correction parameter η ₁ when the film thickness of the underlayer is 400 nm and 600 nm, the estimated film thickness is used. What is necessary is just to obtain | require the proximity effect correction parameter value with respect to (for example, linear interpolation). By obtaining by interpolation, the conditions obtained by experiments or simulations can be reduced.

The proximity effect correction parameter is corrected by changing η ₁ to the value obtained here (step S405). The generated proximity effect correction parameter is stored in the dose correction calculation unit 142.

  In steps S404 and S405, by detecting reflected electron signals from a plurality of proximity effect correction mark patterns having different area densities, it is possible to evaluate manufacturing errors and reflected electron intensity differences caused by the area density differences. . Therefore, it is possible to obtain the proximity effect correction parameter with high accuracy.

In the steps so far, the underlayer pattern area density (α ₁₀ ) and the proximity effect correction parameter (η ₁ ) that change depending on the actually formed underlayer are corrected based on the actually measured information. Accordingly, the area density of the drawing layer and the corrected area density of the underlying layer pattern are read from the area density map memory 141, and the denominator of the right side of Equation (4), that is, the backscattering intensity in each unit section is calculated. Yes (step S406). This calculation may be executed by the dose correction calculation unit 142 or may be executed by another block (not shown) of the proximity effect correction module 124.

  Thereafter, the dose correction calculation unit 142 calculates the optimum dose D in each unit section using the backscattering intensity obtained in step S406 and the equation (4) (step S407), and blanking based on the calculated dose D. By controlling the amplifier 122, the figure in each unit section is exposed with an electron beam with the optimum dose D (step S408).

  In the present embodiment, the area density map of the underlayer pattern and the proximity effect correction parameters used when calculating the optimum dose D are corrected based on information from the actually completed lower layer structure. As a result, it is possible to reduce pattern dimension errors due to proximity effect correction errors caused by manufacturing variations of the underlayer.

(Second Embodiment)
In the electron beam exposure method according to the first embodiment, only one W / SiO ₂ layer is considered as the underlayer, but the electron beam exposure method according to the second embodiment is as shown in FIG. It is assumed that the resist is exposed when there are a plurality of underlayers.

That is, there are a plurality of base layers 71 to 73 made of the same material as or different from the W / SiO ₂ layer 31 shown in FIG. 3, and these form a multilayer structure. On top of this, an Al film layer 74 as a layer to be processed, an SiO ₂ layer 75 as a hard mask layer, and a resist 76 are sequentially formed. In this case, when the resist 76 is exposed with an electron beam, it is necessary to consider the influence of backscattering from the respective underlayers 71 to 73.

  In the present embodiment, a proximity effect correction mark as shown in FIG. 5 is not applied to each of the underlying layers 71 to 73 so as not to overlap when viewed from the beam irradiation direction when scanning with an electron beam. Create each. Here, one kind of proximity effect correction mark may be provided for each underlayer. However, by providing a plurality of proximity effect correction marks in each underlayer as shown in FIG.

  FIG. 8 is a flowchart showing the electron beam exposure method according to the present embodiment.

  First, design data is converted into EB drawing data and stored in the pattern data memory 118 (step S801).

  Next, the pattern decoder 119 reads the drawing layer (processed layer) pattern stored in the pattern data memory 118 and the pattern data of each of the plurality of underlying layers, and decomposes them into graphic dimensions and coordinates for each unit area. To the proximity effect correction module 124. The area density calculation unit 140 of the proximity effect correction module 124 calculates the area density of the pattern of the drawing layer and each underlayer based on the given data (step S802). The calculation result is stored in the area density map memory 141.

  Prior to the EB drawing, the proximity effect correction marks created on each of the plurality of underlayers are respectively scanned with the electron beams, and each reflected electron signal is detected by the detector 126 (step S803).

  Each reflected electron signal waveform corresponding to each underlayer detected by the detector 126 is analyzed by the signal waveform processing module 151, so that each underlayer mark pattern can be obtained from information corresponding to the width of each proximity effect correction mark pattern. Get the “finished dimensions”. Based on the obtained finished dimension information, the area density of the pattern data of each underlayer is corrected. That is, the area density map of the pattern data of each foundation layer stored in the area density map memory 141 is corrected in accordance with the actual finished dimensions of each foundation layer (step S804).

  Further, each reflected electron signal waveform corresponding to each underlayer detected by the detector 126 is analyzed by the signal waveform processing module 151, so that each reflected electron signal signal intensity from each proximity effect correction mark is analyzed. The “reflection electron intensity” of the underlayer is obtained. From the obtained reflected electron intensity, the proximity effect correction parameter generation module 152 generates a proximity effect correction parameter for each underlying layer corresponding to the actual reflected electron intensity from the underlying layer (step S805).

  For example, when it is known in advance that the correction amount of the area density of the pattern data of each underlying layer is small, step S804 is omitted, that is, the area density of the pattern data of each underlying layer is not corrected. Thus, only the proximity effect correction parameter for each underlayer may be generated based on the reflected electron signal. In some cases, conversely, step S805 may be omitted and only correction of the area density of the pattern data of each underlying layer may be performed.

The proximity effect correction parameter for each underlying layer described here will be described. An appropriate irradiation amount (irradiation energy) D in the case of drawing an electron beam on a resist having a plurality of (n layers) underlayers is shown, for example, in Equation (9) of Patent Document 1 (Japanese Patent Laid-Open No. 2004-31836). As

It is expressed. Here, C: constant, η: ratio of backscattering energy to irradiation energy, η _k : ratio of backscattering energy to irradiation energy for the kth (k = 1 to n) th underlayer pattern structure, α: drawing layer Pattern area density, α _k : Pattern area density of the kth (k = 1 to n) th overlapping drawing layer pattern.

  The kth overlapping drawing layer pattern is a pattern of a portion where the drawing layer pattern and the kth underlayer pattern overlap. Accordingly, the pattern area density of the kth overlapping drawing layer pattern is a function of the area density of the kth underlayer pattern.

In this case, the proximity effect correction parameter for each underlayer is, for example, η _k (k = 1 to n). As shown in the equation (5), η _k (k = 1 to n) is a parameter that determines the relationship between the pattern area density of the kth overlapping drawing layer pattern and the electron beam irradiation amount D. As a result, it is a parameter that determines the relationship between the area density of each underlying layer pattern and the electron beam dose D.

  The method for generating each proximity effect correction parameter corresponding to the reflected electron intensity from each underlayer is the same as that described in the first embodiment. Each generated proximity effect correction parameter is stored in the dose correction calculation unit 142.

  In steps S804 and S805, by detecting reflected electron signals from a plurality of proximity effect correction marks having different area densities that are present in each of the plurality of underlayers, manufacturing errors and The difference in reflected electron intensity can be evaluated. Therefore, it is possible to obtain the proximity effect correction parameter with high accuracy.

The area density of each underlayer pattern and each proximity effect correction parameter (η _k (k = 1 to n)) that change depending on each actually formed underlayer in the steps so far are based on the actually measured information. Have been corrected. Therefore, the area density of the drawing layer and the corrected area density of each underlayer pattern are read from the area density map memory 141, and the denominator of the right side of Equation (5), that is, the backscattering intensity in each unit section is obtained. It can be calculated (step S806). This calculation may be executed by the dose correction calculation unit 142 or may be executed by another block (not shown) of the proximity effect correction module 124.

  Thereafter, the irradiation amount calculation unit 142 calculates the optimum irradiation amount D in each unit section using the backscattering intensity obtained in step S806 and the equation (5) (step S807), and based on that, a blanking amplifier is calculated. By controlling 122, the figure in each unit section is exposed with an electron beam with the optimum dose D (step S808).

  In this embodiment, in step S803, each reflected electron signal is obtained by scanning the proximity effect correction mark with an electron beam for each of the plurality of underlayers. However, in actuality, when the underlying layers are formed one by one, the reflected electron signal of each underlying layer below is obtained, so the area density data of the pattern data of each underlying layer obtained therefrom In addition, the proximity effect correction parameter for each underlayer may be held and used for later drawing.

In that case, only the proximity effect correction mark of the underlying layer formed immediately before may be scanned with the electron beam to correct only the area density data of the pattern data of the underlying layer and the proximity effect correction parameter. However, each time a new layer is drawn, for example, backscattering from the underlayer under the condition in which the hard mask (SiO ₂ ) layer 75, the resist 76, etc. in FIG. As in the embodiment, the accuracy is improved by scanning the proximity effect correction marks with the electron beam for all of the plurality of underlying layers to obtain the respective reflected electron signals.

  Also in the present embodiment, the area density map of each underlayer pattern used when calculating the optimum dose D and the proximity effect correction parameter corresponding to each underlayer are based on information from the actually completed lower layer structure. The correction has been added. As a result, it is possible to reduce pattern dimension errors due to proximity effect correction errors caused by manufacturing variations of the underlayer.

  As described above, as described in the first and second embodiments, a proximity effect correction mark pattern is formed in advance in an underlayer composed of one or more lower layers, and an electron beam scan is performed prior to pattern drawing. To obtain a reflected electron signal. Information related to the proximity effect such as the finished dimension of the lower layer structure and the reflected electron intensity is obtained from the reflected electron signal, and the area density of the underlayer pattern and the proximity effect correction parameter are determined based on the information. Thereby, it is possible to reduce the dimensional error of the drawing pattern due to the proximity effect correction error caused by the manufacturing variation of the underlayer.

  In addition, the electron beam exposure method according to the above-described embodiment is preferably executed by creating a program for causing a computer to execute the steps of the flowcharts shown in FIGS. 4 and 8 as a procedure and using the program.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention in the implementation stage. Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the column of the effect of the invention Can be extracted as an invention.

The figure which showed the structure of the electron beam exposure apparatus which concerns on embodiment of this invention. The figure which showed the detailed structure of the proximity effect correction module periphery. Sectional drawing which shows the structure from a board | substrate to a resist in case the base layer is 1 layer based on 1st Embodiment. 5 is a flowchart showing an electron beam exposure method according to the first embodiment. The top view of the proximity effect correction mark with different drawing densities. The figure which shows a reflected electron signal waveform. Sectional drawing which shows the structure from a board | substrate to a resist in case there exist multiple base layers based on 2nd Embodiment. 9 is a flowchart showing an electron beam exposure method according to the second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Electron beam exposure apparatus, 101 ... Electron gun, 103 ... 1st condenser lens,
104 ... second condenser lens, 105 ... first molding aperture,
106 ... first projection lens, 107 ... second projection lens, 108 ... second molding aperture,
109 ... shaping deflector, 110 ... reduction lens, 111 ... objective lens, 112 ... semiconductor substrate,
113 ... Objective deflector, 114 ... Faraday cup, 115 ... Mark stand,
116 ... movable stage, 118 ... pattern data memory,
119 ... Pattern data decoder, 120 ... Molding deflection amplifier, 121 ... Objective deflection amplifier,
122 ... Blanking amplifier, 124 ... Proximity effect correction module, 126 ... Detector,
130 ... Blanking electrode, 131 ... Blanking aperture,
140 ... area density calculation unit, 141 ... area density map memory,
142 ... Irradiation amount correction calculation unit, 151 ... Signal waveform processing module,
152 ... Proximity effect correction parameter generation module, 30 ... Silicon substrate,
31 ... W / SiO ₂ layer (W plug layer), 32, 74 ... Al film layer, 33, 75 ... SiO ₂ layer,
34, 76 ... resist, 71-73 ... underlayer,
501, 711, 721, 731 ... isolated line marks,
502, 712, 722, 732 ... line and space marks,
503, 713, 723, 733 ... isolated space mark,
601 ... the obtained signal waveform, 602 ... the reference waveform,
S401-S408, S801-S808 ... step.

Claims (5)

An electron beam exposure method for exposing a resist formed on the processing layer in order to process the processing layer formed on the base layer having a pattern and a mark,
Scanning the electron beam on the mark to obtain a reflected electron signal;
Correcting at least one of the area density of the pattern and the parameter defining the area density of the pattern and the amount of electron beam irradiation based on the reflected electron signal;
After the correction, determining the electron beam irradiation amount based on the area density of the pattern and the relationship between the area density of the pattern and the electron beam irradiation amount;
Exposing the resist with the electron beam having the determined irradiation amount. An electron beam exposure method comprising: A multi-layer structure having a plurality of underlying layers having patterns and marks, wherein the marks are processed in order to process a work layer formed on the multi-layer structure formed so as not to overlap each other. An electron beam exposure method for exposing a resist formed on a layer, comprising:
Irradiating an electron beam onto the plurality of marks to obtain a reflected electron signal;
Correcting at least one of the area density of the plurality of patterns and the parameter defining the relationship between the area density of the plurality of patterns and the dose of the electron beam based on the reflected electron signal;
After the correction, determining the electron beam irradiation amount based on the area density of the plurality of patterns and the relationship between the area density of the plurality of patterns and the electron beam irradiation amount;
Exposing the resist with the electron beam having the determined irradiation amount. An electron beam exposure method comprising: The electron beam exposure method according to claim 1, wherein an area density of the pattern is corrected based on a width of the mark obtained from the reflected electron signal. The electron beam exposure method according to claim 1, wherein the parameter is corrected based on a signal intensity of the reflected electron signal. An electron beam exposure apparatus for exposing a resist formed on the processing layer in order to process the processing layer formed on the base layer having a pattern and a mark,
Means for scanning the electron beam on the mark to obtain a reflected electron signal;
Means for correcting at least one of parameters defining the area density of the pattern and the relationship between the area density of the pattern and the irradiation amount of the electron beam based on the reflected electron signal;
Means for determining the electron beam irradiation amount based on the area density of the pattern and the relationship between the area density of the pattern and the electron beam irradiation amount after the correction;
Means for exposing the resist with the electron beam of the determined irradiation amount.

Images