JP4091263B2 - Focus monitor method and exposure apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a focus monitoring method suitable for setting focus control in a projection exposure apparatus when manufacturing a semiconductor element, a liquid crystal display element, or the like. Exposure using this focus monitor method Equipment Related.
[0002]
[Prior art]
With the recent miniaturization of device patterns, it has become difficult to obtain a sufficient process margin such as exposure latitude and depth of focus. Therefore, in order to effectively use a small process margin and prevent a decrease in yield, a technique for monitoring the exposure amount and focus with higher accuracy is required.
[0003]
In the conventional method for managing focus, a QC mask on which rhombus marks 101 as shown in FIG. 1A are formed, exposure is performed by changing the focus value, and a wafer as shown in FIG. The focus point at which the pattern length L of the rhombus mark 102 transferred to the longest was the longest was set as the best focus. In this case, the relationship between the pattern length L and the defocus is as shown in FIG. 2 (Japanese Patent Laid-Open No. 10-335208).
[0004]
The rhombus mark is resolved to a fine portion at the optimum focus point, but the resolution for the fine portion is reduced as it is defocused. For this reason, the pattern length L of the rhombus marks transferred onto the wafer has a maximum value at the best focus position, and exhibits substantially symmetric characteristics with respect to plus / minus defocus. This mark can be used for obtaining the best focus by changing the defocus prior to flowing the lot and exposing.
[0005]
However, this type of method has the following problems. That is, when trying to manage the focus condition of a lot exposed under the same exposure condition using a rhombus mark, just by monitoring the pattern length L of the rhombus mark after transfer,
(1) I do not know the direction of focus shift
(2) It will be affected by fluctuations in exposure.
There was a problem.
[0006]
As another focus monitoring method, a method of detecting a focus variation amount as a pattern displacement amount without being influenced by the exposure amount has been proposed (Phase shift focus monitor applications to lithography tool control, D. Wheeler). et.al., SPIE vol.3051, pp225-233). However, the focus detection sensitivity by the mark in this method greatly depends on the light source shape (σ shape), and although sufficient sensitivity can be obtained under a relatively low σ exposure condition, a relatively large σ which is a conventionally used condition is obtained. There was a problem that sufficient sensitivity was not obtained under the condition or the annular illumination condition. Furthermore, in the above method, since it is necessary to form a phase shift film in creating a mark, the burden on manufacturing the mask increases, and although there is a possibility of application to a QC mask, it is difficult to apply to an actual device mask. Met.
[0007]
[Problems to be solved by the invention]
Thus, conventionally, in order to monitor the focus by the projection optical system, it is necessary to use a special focus monitor mask provided with a rhombus mark and a phase shift film in addition to the exposure mask. Further, the method using rhombus marks has a problem that the direction of focus shift is not known and is influenced by fluctuations in exposure amount. Furthermore, in the method using the phase shift film, there is a problem that sufficient sensitivity cannot be obtained under a relatively large σ condition or annular illumination condition in addition to an increase in the burden on mask manufacturing.
[0008]
The present invention has been made in consideration of the above circumstances, and the object of the present invention is to measure the focus by the projection optical system with high sensitivity and high accuracy without using a special mask for the focus monitor. An object of the present invention is to provide a focus monitor method capable of performing the above.
[0009]
Another object of the present invention is to perform exposure using the focus monitor method described above. Equipment It is to provide.
[0010]
[Means for Solving the Problems]
(Constitution)
In order to solve the above problems, the present invention adopts the following configuration.
[0012]
That is In the present invention, a focus monitor pattern on a mask illuminated by an electromagnetic wave or an electron beam is transferred onto an exposed substrate by a projection optical system, and an effective focus is monitored by measuring the pattern on the substrate. In the monitoring method, the focus monitor pattern includes at least two types of pattern groups, the pattern group A is disposed at an arbitrary position of a dicing region surrounding the semiconductor device pattern region on the mask, and the pattern group B is: The mask is placed on the substrate by the projection optical system by sequentially stepping the stage on which the substrate is mounted, which is disposed at a position in the dicing region that is substantially opposed to the arrangement position of the pattern group A across the semiconductor device pattern region. Putter for a distance approximately equivalent to the amount of stepping when transferring to the top The pattern group A is arranged away from the group A, and the pattern group A is illuminated with illumination light in a state where the center of gravity of the illumination light source is off-axis, and the pattern group B in the normal illumination state where the center of gravity of the illumination light source exists on the axis Under the condition of illuminating with illumination light, a stage on which the substrate is mounted is sequentially stepped, the mask is transferred onto the substrate by the projection optical system, and the substrate is stepped N times (N is a positive integer). The relative position between the pattern group A transferred above and the pattern group B transferred onto the substrate after stepping N + 1 times is measured.
[0013]
The present invention also monitors the effective focus by transferring a focus monitor pattern on a mask illuminated by an electromagnetic wave or an electron beam onto a substrate to be exposed by a projection optical system, and measuring the pattern on the substrate. In the focus monitoring method, the focus monitor pattern is composed of at least four types of pattern groups, and the pattern group A and the pattern group C are close to an arbitrary portion of a dicing region surrounding the semiconductor device pattern region on the mask. The pattern group B and the pattern group D are arranged at a position in the dicing area that is substantially opposite to the arrangement position of the pattern group A and the pattern group C across the semiconductor device pattern area, and mounted with the substrate. The stage is sequentially stepped and the mask is placed on the substrate by the projection optical system. The pattern groups A and C are arranged away from the pattern groups A and C by a distance substantially corresponding to the stepping amount at the time of copying, and the pattern groups A are illuminated with illumination light with the center of gravity of the illumination light source off-axis. , D under the condition of illuminating with illumination light in a normal illumination state where the center of gravity of the illumination light source exists on the axis, the stage on which the substrate is mounted is sequentially stepped, and the mask is moved by the projection optical system. Relative displacement between pattern group A transferred onto the substrate after stepping N times (N is a positive integer) and pattern group B transferred onto the substrate after N + 1 times stepping α is measured, and the relative positional deviation amount β between the pattern group C transferred onto the substrate after stepping N times and the pattern group D transferred onto the substrate after stepping N + 1 times Measured, characterized by monitoring the effective focus by removing the contribution of β from alpha.
[0014]
Here, preferred embodiments of the present invention include the following.
[0015]
(1) The combination of the pattern group A and the pattern group B and the combination of the pattern group C and the pattern group D are combinations of the outer box pattern and the inner box pattern in the box-in-box pattern used in the misalignment inspection.
[0016]
(2) The combination of the pattern group A and the pattern group B and the combination of the pattern group C and the pattern group D are combinations of the outer bar pattern and the inner bar pattern in the burn-in bar pattern used in the misalignment inspection.
[0017]
(3) As a means for causing the center of gravity of the illumination light source to be off-axis, a part of the illumination light that illuminates the pattern group A by arranging a light shielding body at or near the plane position on the back surface of the mask corresponding to the pattern group A Shield from light.
[0018]
(4) As a means for causing the center of gravity of the illumination light source to be off-axis, an optical element for deflecting the optical path in one direction is disposed at or near the plane position on the back surface of the mask corresponding to the pattern group A.
[0019]
(5) As a means for causing the center of gravity of the illumination light source to be off-axis, a light shielding body is disposed at or near the plane position corresponding to the pattern group A and optically conjugate with the mask back surface. Blocking part of the illumination light that illuminates group A.
[0020]
(6) As a means for causing the center of gravity of the illumination light source to be off-axis, the optical path is deflected in one direction at or near the plane position corresponding to the pattern group A and optically conjugate with the mask surface. Place optical elements.
[0021]
(7) The optically conjugate position must be a blind position in the illumination optical system.
[0022]
(8) A wedge-shaped transmission member or diffraction grating is used as an optical element that deflects the optical path in one direction.
[0023]
Further, the present invention provides a focus monitor for monitoring an effective focus by transferring a focus monitor pattern on a mask illuminated by an electromagnetic wave or an electron beam onto the substrate by a projection optical system, and measuring the pattern on the substrate. In the monitoring method, the focus monitor pattern includes at least four types of pattern groups, and the pattern group A and the pattern group C are arranged close to an arbitrary portion of a dicing region surrounding the semiconductor device pattern region on the mask. The pattern group B and the pattern group D are arranged at a position in the dicing area that is substantially opposite to the arrangement position of the pattern group A and the pattern group C across the semiconductor device pattern area, and on which the substrate is mounted. Are sequentially stepped to transfer the mask onto the substrate by the projection optical system. The pattern groups A and C are arranged apart from the pattern groups A and C by a distance substantially corresponding to the stepping amount at the time of illuminating, and the pattern groups A are illuminated with illumination light with the center of gravity of the illumination light source off-axis. The stage on which the substrate is mounted is sequentially stepped under a condition in which D is illuminated with illumination light in a normal illumination state where the center of gravity of the illumination light source exists on the axis, and the mask is moved by the projection optical system to the substrate. Formed by double exposure of pattern group A transferred onto the substrate after stepping N times (N is a positive integer) and pattern group B transferred onto the substrate after stepping N + 1 times The pattern dimension C on the substrate is measured, the pattern group C transferred onto the substrate after stepping N times, and the pattern transferred onto the substrate after stepping N + 1 times. In this case, the dimension β of the pattern on the substrate formed by double exposure with the lens group D is measured, and the effective focus is monitored by removing the contribution of β from α.
[0024]
The present invention also monitors the effective focus by transferring a focus monitor pattern on a mask illuminated by an electromagnetic wave or an electron beam onto a substrate to be exposed by a projection optical system, and measuring the pattern on the substrate. In the focus monitoring method, the focus monitor pattern is composed of at least four types of pattern groups, and the pattern group A and the pattern group C are close to an arbitrary portion of a dicing region surrounding the semiconductor device pattern region on the mask. The pattern group B and the pattern group D are arranged at a position in a dicing area that is substantially opposed to the arrangement position of the pattern group A and the pattern group C across the semiconductor device pattern area, and a stage on which the substrate is mounted Are sequentially stepped, and the mask is transferred onto the substrate by the projection optical system. The pattern groups A and C are arranged apart from the pattern groups A and C by a distance substantially corresponding to the stepping amount at the time of illuminating, and the pattern groups A are illuminated with illumination light with the center of gravity of the illumination light source off-axis. The stage on which the substrate is mounted is sequentially stepped under a condition in which D is illuminated with illumination light in a normal illumination state where the center of gravity of the illumination light source exists on the axis, and the mask is moved by the projection optical system to the substrate. The distance α between the pattern group A transferred onto the substrate after stepping N times (N is a positive integer) and the pattern group B transferred onto the substrate after stepping N + 1 times is measured, and N Measure the distance β between the pattern group C transferred onto the substrate after stepping and the pattern group D transferred onto the substrate after stepping N + 1 times, and remove the contribution of α to β. It is characterized by monitoring effective focus.
[0025]
Here, preferred embodiments of the present invention include the following.
[0026]
(1) As a means for causing the center of gravity of the illumination light source to be off-axis, a part of the illumination light that illuminates the pattern group A by arranging a light shield at or near the plane position on the mask back surface corresponding to the pattern group A Shield from light.
[0027]
(2) As a means for causing the center of gravity of the illumination light source to be off-axis, an optical element that deflects the optical path in one direction is disposed at or near the planar position on the back surface of the mask corresponding to the pattern group A.
[0028]
(3) As a means for causing the center of gravity of the illumination light source to be off-axis, a light-shielding body is disposed at or near the plane position corresponding to the pattern group A and optically conjugate with the mask back surface. Blocking part of the illumination light that illuminates group A.
[0029]
(4) As a means for causing the center of gravity of the illumination light source to be off-axis, the optical path is deflected in one direction at or near the plane position corresponding to the pattern group A and optically conjugate with the mask surface. Place optical elements.
[0030]
(5) The optically conjugate position must be a blind position in the illumination optical system.
[0031]
(6) A wedge-type transmission member or diffraction grating is used as an optical element that deflects the optical path in one direction.
[0032]
Further, the present invention monitors the effective focus by transferring a pattern on a focus monitor mask illuminated by an electromagnetic wave or an electron beam onto a substrate to be exposed by a projection optical system, and measuring the pattern on the substrate. An exposure apparatus comprising a focus monitor means, wherein the focus monitor pattern comprises at least two types of pattern groups, The pattern group A is disposed at an arbitrary position of the dicing region surrounding the semiconductor device pattern region on the mask, and the pattern group B is a dicing region that substantially faces the arrangement position of the pattern group A across the semiconductor device pattern region. The stage on which the substrate is mounted is sequentially stepped and separated from the pattern group A by a distance substantially corresponding to the stepping amount when the mask is transferred onto the substrate by the projection optical system. Has been placed, The pattern group A is illuminated by illumination light with the center of gravity of the illumination light source off-axis. And The pattern group B is illuminated by illumination light in a normal illumination state where the center of gravity of the illumination light source is on the axis. Means for sequentially stepping the stage on which the substrate is mounted under the conditions to transfer the mask onto the substrate by the projection optical system, and on the substrate after stepping N times (N is a positive integer) Means for measuring a relative position between the transferred pattern group A and the pattern group B transferred onto the substrate after stepping N + 1 times; It is characterized by having.
[0033]
Here, preferred embodiments of the present invention include the following.
[0034]
(1) As a means for causing the center of gravity of the illumination light source to be off-axis, a light-shielding body is disposed at or near the plane position corresponding to the pattern group A and optically conjugate with the mask back surface. Blocking part of the illumination light that illuminates group A.
[0035]
(2) As a means for causing the center of gravity of the illumination light source to be off-axis, the optical path is deflected in one direction at or near the plane position corresponding to the pattern group A and optically conjugate with the mask surface. Place optical elements.
[0036]
(3) The optically conjugate position must be a blind position in the illumination optical system.
[0037]
(4) The optical element that deflects the optical path in one direction is a wedge-shaped transmission member or diffraction grating.
[0043]
(Function)
When the monitor pattern is illuminated with illumination light in a state where the center of gravity of the illumination light source is off-axis, the pattern formed on the sample is displaced due to focus shift. On the other hand, if the monitor pattern is illuminated with illumination light in a normal illumination state where the center of gravity of the illumination light source is on the axis, the pattern formed on the sample is not displaced due to focus displacement. Therefore, the pattern group A is illuminated with illumination light with the center of gravity of the illumination light source off-axis, and the pattern group B is illuminated with illumination light in a normal illumination state where the center of gravity of the illumination light source is on the axis. The focus shift can be measured by measuring the relative positions of the pattern group A and the pattern group B formed on the substrate.
[0044]
In the present invention, a box-in-box pattern used for a normal misalignment inspection can be used as the focus monitor pattern. If a part of the mask of the box-in-box pattern is covered with the mask, a so-called telecentric shift in which the ratio of the diffracted light is different under the annular illumination conditions most often used as the exposure conditions can be caused. Therefore, the position of the box-in-box pattern transferred with defocusing is shifted. If this misalignment is measured by a misalignment inspection apparatus or the like, the focus value at the time of exposure can be easily monitored. As a result, the focus fluctuation amount can be measured with high accuracy without using a special pattern such as a phase shift.
[0045]
DETAILED DESCRIPTION OF THE INVENTION
The details of the present invention will be described below with reference to the illustrated embodiments.
[0046]
(First embodiment)
The focus monitoring method according to the first embodiment of the present invention will be described with reference to FIGS. The present embodiment is intended to measure the focus fluctuation amount generated during the exposure process with high accuracy without using a special pattern such as a phase shift.
[0047]
As a basic configuration of the focus monitor pattern, two or more sets of patterns existing on the same mask are used. As shown in FIG. 3, the configuration in this embodiment uses a box-in-box pattern widely used in alignment inspection and the like, and either one of the outer box pattern 301 or the inner box pattern 302 is used. On the other hand, it has means for shielding part of the illumination light to be illuminated.
[0048]
FIG. 4 shows a state in which the mask 407 is illuminated by illumination (annular illumination) 401 and the pattern of this mask 407 is transferred to the chip 409 on the wafer 408 via a projection optical system (not shown). As the focus monitor pattern, as shown in the figure, two inner box patterns 403 (pattern group A) and 406 (pattern group C) and two outer box patterns 402 (pattern group B) and 405 (pattern group D) are masked. 407 on both ends.
[0049]
More specifically, each box pattern is arranged in a dicing line outside the device pattern area of the mask 407. Further, the inner box patterns 403 and 406 are arranged on the dicing line on the right side of the device pattern area, and the outer box patterns 402 and 405 are arranged on the dicing line on the left side of the device pattern area. However, with respect to the inner box pattern 403, the light shielding body 404 is disposed so as to shield part of the illumination light that illuminates this pattern. Specifically, the light shielding body 404 is disposed on the mask back surface corresponding to the position of the inner box pattern 403.
[0050]
The pattern is transferred onto the wafer using such a mask. The specific procedure is as follows. First, the mask 407 is loaded into an optical exposure apparatus, the resist-coated wafer 408 is introduced into the exposure apparatus, and the mask pattern is transferred onto the wafer 408 while step-and-repeat as shown in FIG. To do. This pattern transfer may be either a stepper that exposes the mask pattern area in a batch or a scanner that scans and exposes the mask pattern area. The stepping amount at that time is determined by how the device pattern is laid out on the wafer 408.
[0051]
When the exposure is performed as described above, the exposure is performed so that the design centers of the inner box patterns 403 and 406 and the outer box patterns 402 and 405 coincide. That is, when laying out the two box patterns on the mask 408, it is important that the center positions of the two box patterns on the wafer match when the exposure is performed by ideally stepping in the assumed stepping. In other words, the positions of both box patterns are determined so as to be exposed.
[0052]
FIG. 5 is a schematic diagram of a chip exposed on a wafer. Reference numerals 502, 503, 505, and 506 in the figure respectively denote transfer patterns of the box patterns 402, 403, 405, and 406 in FIG. On the left side, the chip area is transferred by the Nth exposure, and the right chip area is transferred by the N + 1 circuit exposure.
[0053]
The pattern 503 exposed with partially shielded illumination shifts the position of the transferred pattern with a focus shift for the reason described later. If there is no focus shift, it should be located at 503 ′ in the figure, overlapping the center of the outer box pattern 502. Therefore, the focus can be monitored by measuring the positional deviation of the box-in-box patterns 502 and 503 formed on the wafer 408 by the patterns 402 and 403 on the mask 407. However, since a box-in-box pattern is formed by exposure across two chips, the positional deviation between 502 and 503 is due to the positional accuracy when the exposure apparatus exposes each chip, that is, the stepping distortion of the projection lens. It contains an error.
[0054]
Therefore, the box-in-box patterns 505 and 506 formed without using a light shield are used. This pattern does not cause a positional shift with respect to the focus. If it deviates, it is due to stepping distortion. Therefore, the positional deviation of the box-in-box patterns 505 and 506 is measured, and the value is subtracted from the positional deviation values 502 and 503, so that the positional deviation is purely caused by the focus.
[0055]
The effects will be described below using an example of annular illumination that is often used in actual device pattern exposure. FIG. 6A shows the positional relationship of diffracted light on the pupil plane when the focus monitor pattern is illuminated with a so-called normal illumination in a state where there is no light shielding body in the illumination. If the focus monitor pattern used in this embodiment has a relatively large pitch, the proportion of the 0th-order diffracted light in the diffracted light is very high, so it can be considered that it is represented by the orbit of the 0th-order diffracted light. . When the focus monitor pattern has the same size as the device pattern, the ± first-order light also contributes to the resolution, but in principle the same. For the sake of explanation, FIG. 6 schematically shows only the strongest portion of the annular illumination light that contributes to resolution, but this intensity has a distribution in nature.
[0056]
In FIG. 6A, it can be seen that the light intensity is symmetrical with respect to the wafer surface. In other words, the position of the transferred pattern cannot be displaced with respect to the focus position. On the other hand, as shown in FIG. 6B, when a part of the illumination (here, a half example) is shielded by the light shield, the light intensity is not symmetric with respect to the wafer surface. . For this reason, the position of the transferred pattern is deviated from the focus position. As described above, if two sets of patterns having different behaviors with respect to the focus are transferred onto the wafer and the relative positional deviation amount can be measured, an accurate focus monitor can be performed.
[0057]
FIG. 7 shows the result in this embodiment. The horizontal axis is defocused, and the vertical axis is a value obtained by subtracting the relative positional deviation between the patterns 505 and 506 from the relative positional deviation between the pattern 502 not covered with the light shielding body and the pattern 503 covered with the light shielding half. ing. From this figure, it can be seen that a position shift amount of about 20 nm is measured with respect to a defocus of 0.1 μm, and a focus shift can be sufficiently detected.
[0058]
In the present embodiment, the annular illumination is used as the illumination shape, but the present invention is not limited to this, and the same effect can be obtained with other illumination shapes. In the present embodiment, the light shielding body 404 for the illumination light is disposed at a position corresponding to the inner box pattern. However, the present invention is not limited to this, and the light shielding for shielding a part of the illumination light with respect to the outer box pattern. You may place your body.
[0059]
As described above, according to the present embodiment, the focus monitor on the wafer at the time of exposure can be performed with high accuracy. There has been a method of performing focus monitoring so far, but there is a limitation that a special pattern or a phase transmission film must be used for that purpose. In the present embodiment, a high-precision focus monitor can be performed by using an existing mask without using such a special mask and adding a slight improvement thereto. In the measurement, since an existing alignment accuracy measuring device can be used, it is not necessary to use a new device for this purpose.
[0060]
Further, in order to perform focus monitoring, a part of the illumination is blocked by the alignment accuracy measurement pattern and the light shielding body, thereby making it possible to cause a positional shift with respect to the focus. If this misalignment is read by the alignment inspection apparatus, this measurement becomes the focus monitor of the wafer surface as it is. According to the present embodiment, it becomes possible to perform focus monitoring with a lot link, and it becomes possible to always perform exposure with an appropriate focus, and as a result, an improvement in yield can be expected.
[0061]
(Second Embodiment)
FIG. 8 is a diagram showing a system configuration example for realizing the focus monitoring method according to the second embodiment of the present invention. Note that reference numerals 801, 802, 803, 807, 808, and 809 in the figure correspond to 401, 402, 403, 407, 408, and 409 in FIG.
[0062]
In this embodiment, as a basic configuration of the focus monitor pattern, two or more sets of pattern groups A (803) and B (802) existing adjacently on the same mask are used. The distance p between the pattern groups A and B is measured on the mask 807 in advance. The pattern group B is exposed in a normal state. However, when the pattern group A is exposed, a light shielding body 804 as shown in the figure is arranged for the illumination light, and the exposure is performed with the illumination light source off-axis. Do. At this time, when the focus is shifted on the wafer surface, the behaviors of the pattern groups A and B are different for the reason described later. Specifically, the pattern group A does not cause a position shift due to the focus shift due to the focus shift, but the position of the pattern group B is transferred due to the focus shift on the wafer.
[0063]
FIG. 9 shows a transfer pattern on a wafer exposed using this method. On the chip 909, reference numeral 903 denotes a pattern in which the pattern group A (803) is exposed. Reference numeral 903 ′ denotes a position to be transferred when there is no focus shift, but in this embodiment, the pattern group A causes a position shift due to a focus shift on the wafer surface. Reference numeral 902 denotes a pattern in which the pattern group B (802) is exposed. Since the illumination light that illuminates the pattern group B does not cause an axis shift, the position of the pattern 902 does not shift even if a focus shift occurs.
[0064]
Therefore, the distance between the transfer patterns 902 and 903 on the wafer is measured, and the distance p originally separated on the mask from this value is subtracted by a value converted to a value on the wafer, thereby causing a focus shift. The positional deviation amount of the pattern group A to be measured is measured. Then, the focus monitor can be performed by obtaining this positional deviation amount. Therefore, the same effect as the first embodiment can be obtained.
[0065]
(Third embodiment)
FIG. 10 is a diagram showing a system configuration example for realizing the focus monitoring method according to the third embodiment of the present invention. Note that reference numerals 1001,..., 1009 in the figure correspond to 401,..., 409 in FIG.
[0066]
This embodiment is different from the first embodiment in that a line pattern is used instead of the box-in-box pattern. That is, as shown in FIG. 10, two sets of line patterns 1002, 1003, 1005, and 1006 are arranged at both ends on the same mask 1007, and only one of the patterns 1003 is shielded at the corresponding position of the pattern. A body 1004 is placed. These patterns are exposed by step-and-repeat so that 1002 and 1003 and 1005 and 1006 overlap each other.
[0067]
Among these, the line pattern 1003 causes a positional shift when a focus shift occurs, as in the first embodiment. When the misalignment occurs, the position of one side of the pattern that should have just overlapped will be misaligned, so that the line width exposed by overlapping two lines will become thicker. FIG. 11 shows an example of a pattern exposed on each chip on the wafer. 1102, 1103, 1105, and 1106 in the figure indicate transfer patterns of the patterns 902, 903, 905, and 906 in FIG. 9, respectively. Reference numeral 1103 ′ denotes a position where the pattern 1103 is formed when there is no focus shift.
[0068]
Here, as a factor of changing the line width when two patterns are overlapped, not only the focus shift but also the position shift due to the stepping of the exposure apparatus is included as in the first embodiment. Therefore, it is necessary to monitor a change in line width only by the stepping accuracy using two line-in patterns 1005 and 1006. Of course, these line patterns 1005 and 1006 have no light shielding body. Two line widths are measured at the overlapped and exposed portions.
[0069]
There is a possibility that the line width may change due to stepping on one side, and in addition, there is a possibility that the line width may change due to the focus, so by subtracting the former line width from the latter line width, focus only Line width fluctuations depending on can be observed. After that, if the relationship between the line width and the focus is obtained in advance, the focus monitor can be performed directly from the line width value.
[0070]
(Fourth embodiment)
FIG. 12 is a view for explaining a fourth embodiment of the present invention, and shows a pattern exposed on a wafer. Note that 1202, 1203, 1205, and 1206 in FIG. 12 correspond to 1102, 1103, 1105, and 1106 in FIG.
[0071]
In the present embodiment, the same exposure apparatus system as in FIG. 10 of the third embodiment is used, but the patterns arranged at both ends of the mask are not overlapped so as to be in the vicinity of adjacent chip patterns as shown in FIG. The difference is in the exposure. As a monitoring method, the distance between the patterns 1202 and 1203 is obtained. This distance includes both the position shift due to the focus and the position shift due to the stepping of the exposure apparatus. Therefore, the focus monitor can be performed by obtaining the amount of the stepping from the distance between 1205 and 1206 and subtracting it.
[0072]
According to this embodiment, focus monitoring can be performed in the same manner as in the third embodiment, and since the distance between patterns is measured instead of the dimension of the pattern, the direction of focus deviation can also be detected. it can.
[0073]
(Fifth embodiment)
FIG. 13 is a cross-sectional view of a mask used in the focus monitoring method of the present invention, in which 1301 is a light shield, 1302 is a focus monitor pattern, and 1303 is a transparent substrate.
[0074]
In the first to fourth embodiments, the means for shielding the illumination light is to arrange a light shielding body 1301 for shielding a part of the illumination light on the back surface of the mask corresponding to the focus monitor pattern or in the vicinity thereof. If the light shielding body 1301 is arranged on the back surface of the mask in this way, part of the illumination light that should be used for exposure of the monitor pattern is shielded, the illumination light beam 1304 in FIG. 13 is shielded, and only the illumination light beam 1305 is this. Used for pattern exposure. As a result, the center of gravity of the illumination light source deviates from the optical axis, and the focus monitor as described in the first to fourth embodiments becomes possible.
[0075]
(Sixth embodiment)
Instead of blocking a part of the illumination light as in the fifth embodiment, an optical element that gives an angle to the illumination light may be arranged on the mask rear surface corresponding to the focus monitor pattern or in the vicinity thereof. FIG. 14A is a cross-sectional view of a mask in the present embodiment, where 1401 is an optical element, 1402 is a focus monitor pattern, and 1403 is a transparent substrate.
[0076]
In the mask of this embodiment, the illumination light incident from directly above becomes light 1404 that illuminates the focus monitor pattern 1402 on the reticle from the oblique direction by the optical element 1401. That is, since the focus monitor pattern 1402 can be illuminated obliquely by using the optical element 1401, the same effect as in the fifth embodiment can be obtained, and focus monitoring is possible.
[0077]
Although a wedge-type optical element is used in FIG. 14A, the present invention is not limited to this, and a grating-type optical element as shown in FIG. 14B may be used.
[0078]
(Seventh embodiment)
In the fifth embodiment, the light shield used for the focus monitor pattern is arranged on the back surface of the mask. The same effect as this can be obtained even if the light-shielding body is arranged in another place.
[0079]
FIG. 15 shows a schematic diagram of this embodiment. In the figure, reference numeral 1501 denotes a light shield, 1502 denotes a blind surface, 1503 denotes a projection lens, 1504 denotes a mask, 1505 denotes a focus monitor pattern, 1506 denotes a projection lens, 1507 denotes a wafer surface, and 1508 denotes illumination light.
[0080]
A light shield 1501 is arranged in the vicinity of a blind surface 1502 that is optically substantially conjugate with the back surface of the mask 1504, and illuminates the box pattern 1505 described in the first embodiment or the focus monitor pattern described in the third embodiment. As a result, the same effect as in the sixth embodiment can be obtained, and focus monitoring can be performed. In the present embodiment, the light shielding member is disposed near the blind surface. However, the present invention is not limited to this, and any position that is optically conjugated can be used.
(Eighth embodiment)
In the seventh embodiment, the focus monitor is made possible by arranging a light shielding body in the vicinity of the blind surface. However, the focus monitor can also be arranged by arranging an optical element similar to that used in the sixth embodiment on the blind surface. Is possible.
[0081]
FIG. 16A shows a schematic diagram of this embodiment. 1601 to 1608 in the figure correspond to 1601 to 1608 in FIG. 15, respectively, and 1609 denotes illumination light tilted by the optical element 1601. The illumination light corresponding to the focus monitor pattern 1605 is tilted by the optical element 1601 provided in the vicinity of the blind surface 1602 that is optically substantially conjugate with the back surface of the mask 1604, thereby producing the same effect as in the seventh embodiment. It becomes possible.
[0082]
FIG. 16B shows the positional relationship of the illumination light on the pupil plane. The figure shows the case of annular illumination. Reference numeral 1610 denotes the NA of the projection lens. By shifting the center position of the illumination light from the center position of the projection lens NA as shown in 1612 with respect to the position 1611 of the illumination light that should be originally transmitted on the pupil plane, the wafer surface is asymmetric as shown in FIG. A light intensity distribution can be formed, and the monitor pattern is displaced with respect to the focus, so that focus monitoring is possible.
[0083]
Although a wedge type optical element is used in FIG. 16A, the present invention is not limited to this, and a grating type optical element as shown in FIG. 17 may be used. 1701 to 1709 in FIG. 17 correspond to 1601 to 1609 in FIG. 16, respectively. In this embodiment, the optical element is disposed near the blind surface. However, the present invention is not limited to this, and any optically conjugate position may be used.
(Ninth embodiment)
In the first embodiment, a light shield is provided on the back surface of the mask to shield part of the illumination light on the focus monitor pattern. In this case, it is necessary to consider the influence on the device pattern existing on the same mask. That is, if the light to be used for exposure of the device pattern is blocked, the device pattern that should be normally exposed may be greatly affected. Therefore, this focus monitoring method must be performed while avoiding the influence on the device pattern.
[0084]
FIG. 18A shows an example of a mask cross-sectional view. In the figure, reference numeral 1801 denotes a light shield, 1802 denotes a focus monitor pattern, 1803 denotes a transparent substrate, and 1806 denotes a device pattern existing on the mask. The positional relationship between the light shield 1801, the focus monitor pattern 1802, and the device pattern 1806 is as shown in the figure, and the edge of the light shield 1801 corresponds to the center position of the focus monitor pattern 1802.
[0085]
In order to prevent the illumination light that should expose the device pattern from being blocked by the light shield 1801, the focus monitor pattern 1802 needs to be arranged at a position satisfying the following expression (1) from the end of the device pattern. is there.
[0086]
L> w × tan θ (1)
Here, L is the distance from the device pattern to the box-in-box pattern, W is the thickness of the mask, and θ is the illumination angle in the mask material. The numerical aperture on the wafer side of the projection lens is NA, and the mask material (usually SiO ₂ ) Is an angle determined by sin θ = NA / nM where n is the refractive index of the exposure light and M is the mask magnification.
[0087]
When this condition is not satisfied, as shown in FIG. 18B, the illumination light that should expose the device pattern is also shielded by the light shield 1801 on the back of the box pattern. Therefore, if the expression (1) is satisfied, the focus monitor can be performed without affecting the device pattern.
[0088]
(Tenth embodiment)
In the fifth embodiment, a light shielding body is disposed on the back surface of the mask to shield the box pattern. However, in order not to affect the device pattern at all, it is necessary to satisfy the expression (1). (FIG. 18A). However, since the mask thickness is determined, the focus monitor pattern needs to be separated from the device pattern region by at least W × tan θ, which leads to an increase in chip area. In order to reduce the chip area, this distance should be as small as possible.
[0089]
FIG. 19 shows a cross section of a mask according to this embodiment. In the figure, reference numeral 1901 denotes a light shield, 1902 denotes a focus monitor pattern, 1903 denotes a transparent substrate, and 1906 denotes a device pattern existing on the mask. As shown in this figure, if the light shield 1901 can be embedded in the transparent substrate 1903 or the light shield 1901 can be formed inside the substrate, the W in the above formula (1) becomes small, and the focus monitor pattern can be used as much as the device. It can be arranged near the pattern area.
[0090]
By using such a mask, focus monitoring can be performed with the distance L between the device pattern and the focus monitor pattern being made smaller, leading to a reduction in chip area.
[0091]
The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention.
[0092]
【The invention's effect】
As described above in detail, according to the present invention, the focus monitor pattern group A formed on the mask is illuminated with illumination light in a state where the center of gravity of the illumination light source is off-axis, and another pattern group B is illuminated with the illumination light source. The focus deviation is measured by illuminating with illumination light in a normal illumination state where the center of gravity of the lens is on the axis and measuring the relative positions of the pattern group A and the pattern group B formed on the substrate. Is possible. In this case, the focus by the projection optical system can be accurately measured with high sensitivity without using a special mask for focus monitoring.
[Brief description of the drawings]
FIG. 1 is a diagram showing a rhombus monitor pattern used in a conventional focus monitor and a resist pattern obtained by transferring the rhombus pattern.
FIG. 2 is a diagram showing the relationship between the length when a rhombus monitor pattern is transferred and the focus at that time in the conventional focus monitor technology.
FIG. 3 is a diagram showing an example of a box-in-box pattern used in the first embodiment.
FIG. 4 is a diagram showing an example of a system configuration for realizing the focus monitoring method according to the first embodiment.
FIG. 5 is a view showing two chips exposed in the first embodiment and a focus monitor pattern therein.
FIG. 6 is a diagram showing a relationship (a) between light intensity and focus in non-light-shielded annular illumination and a relationship (b) between light intensity and focus in half-shielded annular illumination.
FIG. 7 is a diagram illustrating a relationship between a focus shift and a position shift in the first embodiment.
FIG. 8 is a diagram showing a system configuration example for realizing a focus monitoring method according to a second embodiment.
FIG. 9 is a diagram illustrating a focus monitor pattern exposed on a wafer for explaining a second embodiment;
FIG. 10 is a diagram showing a system configuration example for realizing a focus monitoring method according to a third embodiment.
FIG. 11 is a view showing two chips exposed in the third embodiment and a focus monitor pattern therein.
FIG. 12 is a diagram illustrating a focus monitor pattern exposed on a wafer for explaining a fourth embodiment;
FIG. 13 is a cross-sectional view showing a configuration of a mask according to a fifth embodiment.
FIG. 14 is a cross-sectional view showing a configuration of a mask according to a sixth embodiment.
FIG. 15 is a diagram showing a system configuration example for realizing a focus monitoring method according to a seventh embodiment.
FIG. 16 is a diagram showing an example of a system configuration for realizing a focus monitoring method according to an eighth embodiment.
FIG. 17 is a diagram showing another example of the system configuration in the eighth embodiment.
FIG. 18 is a sectional view showing the structure of a mask according to the ninth embodiment.
FIG. 19 is a sectional view showing the structure of a mask according to the tenth embodiment.
[Explanation of symbols]
401, 801, 1001 ... annular illumination
402: Outside box pattern (pattern group B)
403 ... Inner box pattern (pattern group A)
404, 804, 1004 ... Shading body
405 ... Outer box pattern (pattern group D)
406 ... Inner box pattern (pattern group C)
407, 807, 1007 ... mask
408, 808, 1008 ... wafer
409, 809, 1009 ... chip
502, 503, 505, 506, 1102, 1103, 1105, 1106, 1202, 1203, 1205, 1206 ... transfer pattern on the wafer
503 ′: the position where the pattern 503 should be originally transferred
802, 1002 ... Line pattern (pattern group B)
803, 1003 ... line pattern (pattern group A),
902, 903 ... Transfer pattern on wafer
903 ', 1003' ... position where the pattern should be originally transferred
1005 ... Line pattern (pattern group D)
1006 ... Line pattern (pattern group C)
1301, 1801, 1901 ... Shading body
1302, 1402, 1802, 1902 ... Focus monitor pattern
1303, 1403, 1803, 1903 ... Transparent substrate
1304, 1305 ... Illumination rays
1401... Optical element
1404 ... A part of illumination light
1501 ... Shading body
1502, 1602, 1702 ... Blind surface
1503, 1603, 1703 ... projection lens
1504, 1604, 1704 ... Mask
1505, 1605, 1705 ... Focus monitor pattern
1506, 1606, 1706 ... projection lens
1507, 1607, 1707 ... wafer surface
1508, 1608, 1708 ... Illumination light
1601, 1701 ... Optical element
1609, 1709 ... Illumination light tilted by optical elements
1610: NA in the projection lens
1611 ... Position where the illumination light 1608 is transmitted
1612 ... Position where the illumination light 1609 is transmitted

Claims (20)

A focus monitoring method for monitoring an effective focus by transferring a focus monitor pattern on a mask illuminated by an electromagnetic wave or an electron beam onto a substrate to be exposed by a projection optical system and measuring the pattern on the substrate. And
The focus monitor pattern is composed of at least two types of pattern groups,
The pattern group A is disposed at an arbitrary position of a dicing region surrounding the semiconductor device pattern region on the mask,
The pattern group B is arranged at a position in a dicing area that is substantially opposite to the arrangement position of the pattern group A across the semiconductor device pattern area, and the stage on which the substrate is mounted is sequentially stepped to project the mask. The optical system is arranged away from the pattern group A by a distance substantially corresponding to the stepping amount when transferring onto the substrate.
The pattern group A is illuminated with illumination light with the center of gravity of the illumination light source off-axis, and the pattern group B is illuminated with illumination light in a normal illumination state where the center of gravity of the illumination light source is on the axis. , Sequentially stepping the stage on which the substrate is mounted, and transferring the mask onto the substrate by the projection optical system;
Relative positions of the pattern group A transferred onto the substrate after N times (N is a positive integer) and the pattern group B transferred onto the substrate after N + 1 steps are measured. Focus monitor method. A focus monitoring method for monitoring an effective focus by transferring a focus monitor pattern on a mask illuminated by an electromagnetic wave or an electron beam onto a substrate to be exposed by a projection optical system and measuring the pattern on the substrate. And
The focus monitor pattern is composed of at least four types of patterns.
The pattern group A and the pattern group C are disposed close to an arbitrary portion of a dicing region surrounding the semiconductor device pattern region on the mask,
The pattern group B and the pattern group D are arranged at positions in the dicing area that are substantially opposed to the arrangement positions of the pattern group A and the pattern group C across the semiconductor device pattern area, and the stages on which the substrates are mounted are sequentially arranged. Stepped and arranged away from the pattern groups A and C by a distance substantially corresponding to the stepping amount when the mask is transferred onto the substrate by the projection optical system,
The pattern group A is illuminated with illumination light when the center of gravity of the illumination light source is off-axis, and the pattern groups B, C, and D are illuminated with illumination light in a normal illumination state where the center of gravity of the illumination light source is on the axis. Under the conditions, the stage on which the substrate is mounted is sequentially stepped, and the mask is transferred onto the substrate by the projection optical system,
The relative positional deviation amount α between the pattern group A transferred onto the substrate after N times (N is a positive integer) and the pattern group B transferred onto the substrate after N + 1 times stepping is measured, and N By measuring the relative displacement β between the pattern group C transferred onto the substrate after stepping and the pattern group D transferred onto the substrate after N + 1 steps, and removing the contribution of α to β A focus monitoring method characterized by monitoring effective focus. The combination of the pattern group A and the pattern group B and the combination of the pattern group C and the pattern group D are combinations of the outer box pattern and the inner box pattern in the box-in-box pattern used in the misalignment inspection. The focus monitoring method according to claim 2 . Combinations combinations and pattern groups C and pattern group D of the pattern group A and the pattern group B, according to claim 2, characterized in that the combination of the outer Batan and inner bar pattern in a bar Invar pattern used in misalignment inspection Focus monitor method. A focus monitor method for monitoring an effective focus by transferring a focus monitor pattern on a mask illuminated by an electromagnetic wave or an electron beam onto the substrate by a projection optical system, and measuring the pattern on the substrate. ,
The focus monitor pattern is composed of at least four types of patterns.
The pattern group A and the pattern group C are disposed close to an arbitrary portion of a dicing region surrounding the semiconductor device pattern region on the mask,
The pattern group B and the pattern group D are arranged at positions in the dicing area that are substantially opposed to the arrangement positions of the pattern group A and the pattern group C across the semiconductor device pattern area, and the stages on which the substrates are mounted are sequentially arranged. Stepped and arranged away from the pattern groups A and C by a distance substantially corresponding to the stepping amount when the mask is transferred onto the substrate by the projection optical system,
The pattern group A is illuminated with illumination light when the center of gravity of the illumination light source is off-axis, and the pattern groups B, C, and D are illuminated with illumination light in a normal illumination state where the center of gravity of the illumination light source is on the axis. Under the conditions, the stage on which the substrate is mounted is sequentially stepped, and the mask is transferred onto the substrate by the projection optical system,
The pattern on the substrate formed by double exposure of the pattern group A transferred onto the substrate after N times (N is a positive integer) and the pattern group B transferred onto the substrate after N + 1 times stepping The pattern on the substrate formed by double exposure of the pattern group C transferred onto the substrate after stepping N times and the pattern group D transferred onto the substrate after stepping N + 1 times A focus monitoring method characterized in that the effective focus is monitored by measuring the dimension β of the lens and removing the contribution of β from α. A focus monitoring method for monitoring an effective focus by transferring a focus monitor pattern on a mask illuminated by an electromagnetic wave or an electron beam onto a substrate to be exposed by a projection optical system and measuring the pattern on the substrate. And
The focus monitor pattern is composed of at least four types of patterns.
The pattern group A and the pattern group C are disposed close to an arbitrary portion of a dicing region surrounding the semiconductor device pattern region on the mask,
The pattern group B and the pattern group D are arranged at positions in the dicing area that are substantially opposed to the arrangement positions of the pattern group A and the pattern group C across the device pattern area, and sequentially step the stage on which the substrate is mounted. The mask is disposed away from the pattern groups A and C by a distance substantially corresponding to the stepping amount when the mask is transferred onto the substrate by the projection optical system.
The pattern group A is illuminated with illumination light when the center of gravity of the illumination light source is off-axis, and the pattern groups B, C, and D are illuminated with illumination light in a normal illumination state where the center of gravity of the illumination light source is on the axis. Under the conditions, the stage on which the substrate is mounted is sequentially stepped, and the mask is transferred onto the substrate by the projection optical system,
The distance α between the pattern group A transferred onto the substrate after stepping N times (N is a positive integer) and the pattern group B transferred onto the substrate after stepping N + 1 times is measured, and the substrate after stepping N times The effective focus is monitored by measuring the distance β between the pattern group C transferred above and the pattern group D transferred onto the substrate after stepping N + 1 times, and removing the contribution of β from α. Focus monitor method. As means for causing the center of gravity of the illumination light source to be off-axis, a light-shielding body is disposed at or near the planar position on the back surface of the mask corresponding to the pattern group A, and part of the illumination light that illuminates the pattern group A is shielded. The focus monitor method according to claim 1 , wherein the focus monitor method is a focus monitor. An optical element for deflecting the optical path in one direction is disposed at or near the plane position on the back surface of the mask corresponding to the pattern group A as means for causing the center of gravity of the illumination light source to be off-axis. Item 7. The focus monitoring method according to any one of Items 1 , 2 , 5 , and 6 . As a means for causing the center of gravity of the illumination light source to be off-axis, a light shielding body is disposed at or near a plane position corresponding to the pattern group A and optically conjugate with the mask back surface, and the pattern group A focus monitoring method according to any of claims 1, 2, 5, 6, characterized in that the shielding part of the illumination light illuminating the. An optical element that deflects the optical path in one direction at or near a plane position corresponding to the pattern group A and optically conjugate with the mask surface as means for causing the center of gravity of the illumination light source to be off-axis. The focus monitoring method according to claim 1 , wherein the focus monitoring method is arranged. 11. The focus monitoring method according to claim 9, wherein the optically conjugate position is a blind position in an illumination optical system. 11. The focus monitoring method according to claim 8 , wherein a wedge-type transmission member or a diffraction grating is used as an optical element that deflects the optical path in one direction. Focus monitor means for transferring the pattern on the focus monitor mask illuminated by the electromagnetic wave or the electron beam onto the substrate to be exposed by the projection optical system and monitoring the effective focus by measuring the pattern on the substrate. Exposure apparatus,
The focus monitor pattern is composed of at least two types of pattern groups. The pattern group A is arranged at an arbitrary position of a dicing area surrounding the semiconductor device pattern area on the mask, and the pattern group B is an arrangement position of the pattern group A. When the mask is transferred onto the substrate by the projection optical system by sequentially stepping the stage on which the substrate is mounted and positioned in a position in the dicing region substantially opposite to the semiconductor device pattern region. It is arranged away from the pattern group A by a distance substantially corresponding to the amount of stepping,
The pattern group A is illuminated by illumination light in a state where the center of gravity of the illumination light source is off-axis , and the pattern group B is illuminated by illumination light in a normal illumination state where the center of gravity of the illumination light source exists on the axis. Means for sequentially stepping a stage on which the substrate is mounted under conditions for illuminating , and transferring the mask onto the substrate by the projection optical system;
Means for measuring a relative position of the pattern group A transferred onto the substrate after N times (N is a positive integer) and the pattern group B transferred onto the substrate after N + 1 times stepping. An exposure apparatus characterized by the above. Focus monitor means for transferring the pattern on the focus monitor mask illuminated by the electromagnetic wave or the electron beam onto the substrate to be exposed by the projection optical system and monitoring the effective focus by measuring the pattern on the substrate. Exposure apparatus,
The focus monitor pattern is composed of at least four types of pattern groups, and the pattern group A and the pattern group C are arranged close to an arbitrary portion of a dicing region surrounding the semiconductor device pattern region on the mask,
The pattern group B and the pattern group D are arranged at positions in the dicing area that are substantially opposed to the arrangement positions of the pattern group A and the pattern group C across the semiconductor device pattern area, and the stages on which the substrates are mounted are sequentially arranged. Stepped and arranged to be separated from the pattern groups A and C by a distance substantially corresponding to the stepping amount when the mask is transferred onto the substrate by the projection optical system,
The pattern group A is illuminated with illumination light with the center of gravity of the illumination light source off-axis , and the pattern groups B, C, and D are in a normal illumination state in which the center of gravity of the illumination light source exists on the axis. Means for sequentially stepping a stage on which the substrate is mounted under the condition of illuminating with the illumination light, and transferring the mask onto the substrate by the projection optical system;
Means for measuring a relative positional shift amount α between the pattern group A transferred onto the substrate after N times (N is a positive integer) and the pattern group B transferred onto the substrate after N + 1 times stepping; ,
Means for measuring a relative positional shift amount β between the pattern group C transferred onto the substrate after stepping N times and the pattern group D transferred onto the substrate after stepping N + 1 times;
An exposure apparatus comprising: means for monitoring effective focus by removing the contribution of β from α . Focus monitor means for transferring the pattern on the focus monitor mask illuminated by the electromagnetic wave or the electron beam onto the substrate to be exposed by the projection optical system and monitoring the effective focus by measuring the pattern on the substrate. Exposure apparatus,
The focus monitor pattern is composed of at least four types of pattern groups, and the pattern group A and the pattern group C are arranged close to an arbitrary portion of a dicing region surrounding the semiconductor device pattern region on the mask,
The pattern group B and the pattern group D are arranged at positions in the dicing area that are substantially opposed to the arrangement positions of the pattern group A and the pattern group C across the semiconductor device pattern area, and the stages on which the substrates are mounted are sequentially arranged. Stepped and arranged to be separated from the pattern groups A and C by a distance substantially corresponding to the stepping amount when the mask is transferred onto the substrate by the projection optical system,
The pattern group A is illuminated with illumination light with the center of gravity of the illumination light source off-axis , and the pattern groups B, C, and D are in a normal illumination state in which the center of gravity of the illumination light source exists on the axis. Means for sequentially stepping the stage on which the substrate is mounted under the condition of illuminating with the illumination light, and transferring the mask onto the substrate by the projection optical system;
The pattern on the substrate formed by double exposure of the pattern group A transferred onto the substrate after N times (N is a positive integer) and the pattern group B transferred onto the substrate after N + 1 times stepping Means for measuring the dimension α of
Means for measuring the dimension β of the pattern on the substrate formed by double exposure of the pattern group C transferred onto the substrate after stepping N times and the pattern group D transferred onto the substrate after stepping N + 1 times When,
An exposure apparatus comprising: means for monitoring effective focus by removing the contribution of β from α . Focus monitor means for transferring the pattern on the focus monitor mask illuminated by the electromagnetic wave or the electron beam onto the substrate to be exposed by the projection optical system and monitoring the effective focus by measuring the pattern on the substrate. Exposure apparatus,
The focus monitor pattern is composed of at least four types of pattern groups, and the pattern group A and the pattern group C are arranged close to an arbitrary portion of a dicing region surrounding the semiconductor device pattern region on the mask,
The pattern group B and the pattern group D are arranged at positions in the dicing area that are substantially opposed to the arrangement positions of the pattern group A and the pattern group C across the device pattern area, and sequentially step the stage on which the substrate is mounted. The mask is disposed away from the pattern groups A and C by a distance substantially corresponding to the stepping amount when the mask is transferred onto the substrate by the projection optical system.
The pattern group A is illuminated with illumination light with the center of gravity of the illumination light source off-axis , and the pattern groups B, C, and D are in a normal illumination state in which the center of gravity of the illumination light source exists on the axis. Means for sequentially stepping the stage on which the substrate is mounted under the condition of illuminating with the illumination light, and transferring the mask onto the substrate by the projection optical system;
Means for measuring the distance α between the pattern group A transferred onto the substrate after stepping N times (N is a positive integer) and the pattern group B transferred onto the substrate after stepping N + 1 times;
Means for measuring a distance β between the pattern group C transferred onto the substrate after stepping N times and the pattern group D transferred onto the substrate after stepping N + 1 times;
An exposure apparatus comprising: means for monitoring effective focus by removing the contribution of β from α . As a means for causing the center of gravity of the illumination light source to be off-axis, a light shielding body is disposed at or near a plane position corresponding to the pattern group A and optically conjugate with the mask back surface, and the pattern group A The exposure apparatus according to claim 13, wherein a part of the illumination light that illuminates the light is shielded. An optical element that deflects the optical path in one direction at or near a plane position corresponding to the pattern group A and optically conjugate with the mask surface as means for causing the center of gravity of the illumination light source to be off-axis. The exposure apparatus according to claim 13, wherein the exposure apparatus is arranged. The exposure apparatus according to claim 17 or 18, wherein the optically conjugate position is a blind position in an illumination optical system. 19. The exposure apparatus according to claim 18, wherein the optical element that deflects the optical path in one direction is a wedge-shaped transmission member or a diffraction grating.

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