JP2004111955A - Alignment adjustment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alignment adjusting device which facilitates arrangement of an observation optical system.
A processing target substrate (50) having a plurality of wafer marks (W1 to W3) formed around a unit processing region, a stage (201) for mounting the processing target substrate, and a unit processing region ( A mask (50) having a mask pattern at a position corresponding to 41), a plurality of mask marks (M1 to M3) formed around the mask pattern corresponding to the plurality of wafer marks, and a mask corresponding to each wafer mark. A plurality of light sources (L1 to L3) for illuminating the arranged wafer mark and the mask mark, and a plurality of light sources (L1 to L3) for observing the wafer mark and the mask mark which are respectively positioned in the extending direction of each wafer mark and illuminated by the light source A camera, and a control unit (205) for adjusting a relative position between the substrate to be processed and the mask based on the observation result, wherein the two cameras are on an imaginary line connecting any two of the plurality of mask marks. Position each camera so that it is not located.
[Selection diagram] FIG.

Description

The present invention relates to an alignment adjustment apparatus for performing alignment between a substrate to be processed and a mask when performing pattern exposure, ion implantation, or the like in a semiconductor device manufacturing process.

(4) When exposing a pattern to a substrate using a mask or performing partial ion implantation, alignment between the substrate and the mask is indispensable. One method of performing such alignment between the mask and the substrate is a combination of a camera and an image processing system. In this method, an alignment mark formed on a substrate for alignment and a mask mark (for example, a window) formed on a mask for alignment are observed with a camera, and the read image is processed to correct the positional deviation. Based on the detection result, the substrate and the mask are relatively moved so that the marks of the substrate and the mask coincide with each other to perform alignment (alignment adjustment).

In this detection, there are cases where the alignment mark of the substrate is observed from a direction perpendicular to the mask and cases where the alignment mark is observed from an oblique direction. Region), it is necessary to retract the optical system during exposure or ion implantation. In the latter case, the optical system of the camera can be arranged so that the optical axis is oblique to the mask surface, so that the optical system can be arranged so as not to block the exposure light. Therefore, it is not necessary to evacuate the optical system (camera) during the exposure, and the alignment mark can be observed even during the exposure.

However, as shown in FIG. 5 described later, in order to observe each mark of the mask, it is necessary to arrange the illumination light source so that bright reflected light reflected by each mark is generated in the optical axis direction of the camera. In this case, the angle of incidence α of the optical axis of the illumination light source on the reflecting surface is the same as the angle of incidence α of the optical axis of the camera on this reflecting surface. That is, the optical axis of the light beam of the illumination light source and the optical axis of the camera are symmetrical with respect to the normal to the reflecting surface. In order to accurately perform alignment adjustment, a plurality of, for example, three or more alignment marks and mask marks are provided. Although it is necessary to arrange a camera and an illumination light source in each of these pairs, as shown in FIG. 8 described later, the illumination light source and the observation optical system of the camera are arranged in a narrow space without blocking the exposure light. It is difficult to arrange a plurality.

In order to perform accurate position adjustment, it is desirable to use a lens with a high resolution and a large numerical aperture. However, as shown in FIG. 7, the objective lens of a large-diameter camera interferes with the exposure area. At the time of exposure, it is necessary to retract the objective lens. In this case, as in the case of observation from the vertical direction, the throughput is disadvantageously reduced.

Accordingly, it is an object of the present invention to provide an alignment adjustment device that facilitates arrangement of an observation optical system for observing an alignment mark (substrate mark) of a substrate and an alignment mark (mask mark) of a mask.

In order to achieve the above object, an alignment adjustment apparatus according to the present invention includes a substrate to be processed in which a plurality of alignment marks (substrate marks) for position adjustment are formed around a unit processing region, and a stage for mounting the substrate to be processed. A mask having a mask pattern for transferring a predetermined pattern to a unit processing area of the substrate to be processed, and a plurality of mask marks formed around the mask pattern corresponding to the plurality of alignment marks; and A mask holder that is held on the substrate to be processed, a plurality of illumination light sources that illuminate the alignment mark and the mask mark that are provided corresponding to the alignment marks, and an illumination light source that corresponds to each alignment mark. A plurality of cameras for observing the alignment mark and the mask mark illuminated by A control unit that adjusts a relative position between the substrate to be processed and the mask based on the observation result, and a virtual line connecting any two of the plurality of mask marks and two on the extension of the virtual line. Each camera is arranged so that the camera is not located.

With this configuration, it is possible to prevent the arrangement area of one set of camera and illumination light source (observation optical system) from overlapping or being too close to the arrangement area of another set of camera and illumination light source. Become.

Preferably, the plurality of alignment marks are formed such that the extending directions of the plurality of alignment marks are different from each other. By determining the viewpoint (optical axis) of the camera in the direction in which the alignment mark extends, it is possible to set the direction of each camera in a different direction, and arrange the observation optical system (illumination light source, camera) in different regions. Easier to do.

Preferably, the extending direction of each alignment mark is set such that the line segment of both alignment marks does not extend in the same direction as the virtual line on a virtual line connecting any two of the plurality of alignment marks. This prevents the two cameras from being arranged opposite to each other.

Preferably, the stage is capable of stepping in the X-axis and Y-axis directions orthogonal to each other. This causes the device to function as a so-called stepper.

Preferably, at least three alignment marks are formed, and a direction of a line segment of each alignment mark is 0 degree, 45 degrees, and 90 degrees, respectively, at an angle formed between each line segment and the X axis or the Y axis. .

Preferably, the substrate to be processed is a wafer, and the alignment mark is a wafer mark formed on the wafer.

Preferably, the mask is formed by etching the mask pattern and a plurality of mask marks on a crystalline substrate, and the direction of an edge of the mask mark used as a reference for observation is a specific crystal of the crystalline substrate. It is formed using a specific plane orientation among a plurality of plane orientations so as to match the direction. As a result, an important portion serving as a reference for observation among mask marks is formed on a crystal surface where an etching rate is different depending on a crystal plane orientation of a crystalline substrate (crystal anisotropy) and deformation of an etching pattern (etching failure) is unlikely to occur. To reduce the mask defect rate.

Preferably, when a substrate such as silicon is used as the crystalline substrate, the specific plane orientation is a crystal represented by (100), (010), (001), or the like when represented by a plane index of a mirror. Any of the crystal planes of the set of crystal planes including the plane {100} is used. In the case of silicon, when wet etching is performed, the etching rate of a crystal plane having a plane orientation of {110} is lower than that of the other plane orientations. To In terms of crystal orientation, it is preferable to avoid <110> and set <100>.

露 光 The exposure apparatus of the present invention uses the above-described alignment adjustment apparatus.

イ オ ン The ion implantation apparatus of the present invention uses the above-described alignment adjustment apparatus.

ス パ ッ タ Further, the sputtering apparatus of the present invention uses the above-described alignment adjusting apparatus.

As described above, according to the alignment adjustment apparatus of the present invention, a plurality of observation optical systems for observing the alignment mark and the mask mark of the substrate to be processed are placed in a narrow place for positioning the substrate and the mask. It is preferable because they can be arranged without interfering with each other.

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

FIG. 1 shows an example of a semiconductor manufacturing apparatus 1 in which the alignment adjusting device of the present invention is used.

The semiconductor manufacturing apparatus 1 generally includes a work chamber 11 for storing a plurality of wafers (substrates to be processed) to be processed, a mask chamber 12 for storing a plurality of masks used in a process, and the directions of the wafer and the mask. A pre-alignment chamber 13 for aligning with reference to a notch provided on a peripheral edge, a process chamber 14 for performing wafer exposure and ion implantation, a loader chamber 15 for arranging a robot arm and transferring a wafer between the chambers, and a loader chamber 15. The manufacturing apparatus 1 includes a gate valve 16 and the like for shielding the chambers from each other to maintain the degree of vacuum in the manufacturing apparatus 1. In the process chamber 14, a processing apparatus 20 for exposing a photosensitive film applied to a wafer, implanting ions into the wafer, performing dry etching, and the like is arranged.

FIG. 2 shows an exposure apparatus as an example of the process apparatus 20. The exposure apparatus 20 includes a wafer stage 201 on which the wafer 40 is placed, an electrostatic chuck 202 for holding the mask 50 by electrostatic force, a plurality of measurement units 203 for observing wafer marks and mask marks on the wafer 40, and generates an exposure light beam. The exposure light generation unit 204 includes a control unit 205 that performs alignment adjustment and exposure control.

The wafer stage 201 is capable of performing a step feed in the illustrated X-axis and Y-axis directions, fine adjustment in the X-axis, Y-axis and Z-axis directions, fine adjustment around each axis, and coarse adjustment in the Z-axis direction. The mounting table is driven by the control unit 205 to determine a relative position between the wafer 40 and the mask 50.

FIG. 3 shows an example of an alignment mark formed on the wafer 40. For example, a large number of pattern areas 41 of, for example, about 30 mm × 30 mm are arranged in a matrix on the surface of a silicon substrate wafer. Between each pattern area 41, for example, an isolation area 42 having a width of several tens of microns is formed in a lattice shape for cutting out chips later. Three wafer marks W1 to W3 per area are formed in advance at appropriate positions in the isolation area 42 by a silicon oxide film. In the illustrated example, the wafer marks W1 and W2 are generated in the Y-axis direction, and the wafer mark W3 is generated in the X-axis direction. In the figure, only the wafer marks corresponding to the hatched central pattern area are shown, but wafer marks W1, W2, and W3 are similarly arranged around all the patterns. The silicon oxide film increases in volume during oxidation and slightly protrudes from the wafer surface, and the wafer marks W1 to W3 are observable.

Incidentally, the wafer marks W1, W2, W3 can be obtained by making the linear silicon oxide film flush with the surrounding portion or in a slightly raised state. It is good also as a pattern which makes a shape pattern project. Alternatively, the wafer marks W1, W2, and W3 may be made of silicon and the periphery thereof may be surrounded by a silicon oxide film.

FIG. 4 is an explanatory view for explaining the mask 50. FIG. 4A is a plan view, and FIG. 4B is a cross-sectional view in the AA direction of FIG.

The mask 50 is a stencil mask having a circular outer shape, a relatively thick peripheral portion 51, a relatively thin membrane portion 52 in an inner area thereof, a central mask pattern portion 53, and a periphery of the mask pattern portion 53. Mask marks (through holes) M1 to M3 respectively formed at positions corresponding to the wafer marks W1 to W3 of the wafer, notches for pre-alignment formed in the peripheral portion 51, and global for coarse adjustment in the process chamber. It has an alignment mark 57.

The mask 50 is, for example, silicon and has a diameter of 4 inches, a thickness of the peripheral portion 51 of 0.5 mm, and a thickness of the membrane portion 52 in the central region of 10 μm.

FIG. 5 shows a configuration example of the measurement unit 203. The measurement unit 203 includes, for example, an illumination light source L such as a halogen lamp or an LED, and a camera C. The optical axis of the illumination light source L and the optical axis of the camera C are arranged symmetrically with respect to the normal to the surface of the wafer mark W1, and the illumination light emitted from the illumination light source L is reflected by the wafer mark W1. The light is incident on the camera C.

The camera C is composed of, for example, an imaging optical system and a CCD. Although not shown, the control unit 205 coarsely adjusts the position of the mask by a positioning mechanism (not shown) by observing the global alignment mark 57, and further coarsely adjusts the position of the stage using a predetermined reference on the wafer 40. . Thereby, when the mask pattern portion 53 is positioned so as to face the position where the pattern of the wafer 40 is transferred by the step feed, the adjustment is performed so that the wafer mark W1 of the wafer 40 is positioned within the mask mark M1. Further, with the pattern section 53 of the mask 50 facing one pattern area 41 on the wafer 40, the control section 205 simultaneously observes the mask window (mask mark) M1 and the wafer mark by the camera C, and The stage 201 is finely adjusted so that the wafer mark W1 of the wafer 40 exists at the center of the stage 201.

FIG. 6 is an explanatory diagram illustrating an example of fine adjustment of the alignment. The control unit 205 observes the width ΔZ of the shadow S of the edge of the mask mark M1 generated on the wafer 40 by the illumination light source L when the camera C is viewed from the direction directly opposite to the camera C. Is calculated. The interval g is determined by g = ΔZ / 2 sin α. Further, the deviation ΔX between the wafer mark W1 and the center of the mask mark M1 is observed. The same measurement is performed for the other wafer mark W2 and mask mark M2, and for the other wafer mark W3 and mask mark M3. The stage 201 is finely adjusted based on each measurement result, the distance between the wafer 40 and the mask 50 is set to an equal predetermined value, and the pattern positions of the wafer 40 and the mask 50 are accurately adjusted. Thereafter, the exposure device 204 is operated to form an exposure latent image on the wafer 40 (to which the photosensitive material has been applied). After such alignment and exposure are performed for all the pattern regions 41 on the wafer 40, the wafer 40 is carried out of the exposure apparatus, and is subjected to development, etching, and the like to form a desired pattern on the wafer 40. Also in the case of ion implantation, alignment adjustment between the wafer 40 and the mask 50 can be performed by a similar process.

By the way, in order to observe a fine pattern such as a wafer mark and read a pixel without blur, it is desirable that the resolution of the camera is high. In order to improve the resolution of the camera, it is preferable to increase the numerical aperture NA of the objective lens of the imaging optical system.

FIG. 7 shows a case where an objective lens having a large numerical aperture NA is used for imaging optics. As shown in the figure, an objective lens having a large numerical aperture NA has a large lens diameter and approaches an exposure area.

FIG. 8 shows the state of the cameras C1 to C3 arranged on the mask 50 on which the mask marks M1 to M3 are formed and the illumination light sources L1 to L3 provided corresponding to the cameras C1 to C3. As shown in FIG. 5, the optical axis of the camera (the optical axis of the objective lens) and the optical axis of the light emitted from the illumination light source in the XZ plane and the YZ plane are, as shown in FIG. Although indicated by a two-dot chain line of a “V” shape having the line as the axis of symmetry, the optical axes of the camera and the irradiation light source projected on the XY plane shown in FIG. 8 are indicated by a straight two-dot chain line. Since the pair of the camera Cn and the exposure light source Ln is arranged on the two-dot chain line for each mask mark, the space on the mask 50 is crowded. In particular, it is difficult to dispose the cameras C1 and C2 and the light sources L1 and L2 for the mask marks M1 and M2 in which the positions of the two-dot chain lines are the same on the X coordinate. Further, arranging a camera having a large-aperture objective lens as shown in FIG. 7 makes it more difficult to arrange an observation optical system. Further, with the increase in the density of the pattern, the size of the chip has been reduced, which also makes the arrangement of the observation optical system more difficult.

FIGS. 9 to 12 show an embodiment of the present invention. In this embodiment, in order to avoid as close as possible a plurality of sets of the observation optical system including the illumination light source and the camera described above, two observation optical systems are provided on a line connecting the two wafer marks. Each observation optical system is arranged so as not to exist. Therefore, first, the arrangement of the wafer mark (alignment mark) and the mask mark is devised.

FIG. 9 shows an example of a wafer mark formed on the wafer of the embodiment, and the same reference numerals in FIG. 9 denote parts corresponding to those in FIG.

Also in this example, similarly to FIG. 3, the wafer marks W1 to W3, which are alignment marks formed on the wafer 40, are formed in the isolated area 42 around the pattern area 41. The extending direction of the mark W1 is the illustrated Y-axis direction, the extending direction of the wafer mark W2 is the X-axis direction, and the extending direction of the wafer mark W3 is a 45 ° counterclockwise direction from the X-axis (or (Direction of 45 degrees clockwise from the Y axis). The wafer mark W3 is formed at a portion where the vertical and horizontal isolation regions at the upper right of the pattern region intersect. In this way, the extending directions of the plurality of wafer marks are different from each other. As will be described later, observation is performed by arranging an observation optical system on a virtual line that passes over each wafer mark and indicates the extending direction of each wafer mark.

FIG. 10 shows a mask used in the embodiment, and portions corresponding to FIG. 4 are denoted by the same reference numerals.

Square mask marks (opening windows) M1 to M3 for alignment of the mask 50 are formed at positions corresponding to the wafer marks W1 to W3, respectively, and the mask pattern M3 is located at the upper right corner of the region 53 from the X axis shown in the figure. It is formed inclined at 45 degrees.

FIG. 11 shows an example in which the mask 50 is overlaid on the wafer 40 and viewed from above. The wafer marks W1 to W3 can be seen in the windows of the mask marks M1 to M3, respectively. As described above, the coarse adjustment of the alignment of the mask 50 and the wafer 40 is performed, and the coarse adjustment is performed so that the wafer marks W1 to W3 are positioned within the mask marks M1 to M3.

FIG. 12 shows a first observation optical system (camera C1, illumination light source L1) for observing wafer mark W1 and mask mark M1, and a second observation optical system (camera C2, illumination) for observing wafer mark W2 and mask mark M2. An example of the arrangement of a third observation optical system (camera C3, illumination light source L3) for observing the light source L2), the wafer mark W3 and the mask mark M3 is shown. A virtual line indicated by a two-dot chain line in FIG. 5 indicates the extending direction of each wafer mark, and the observation optical system corresponding to a plane including the virtual lines (a vertical plane in the present embodiment). Arrange the optical axis. The wafer marks W1 and W2 located at the same position on the X axis are arranged so that the extending directions of the marks are different from each other. Therefore, unlike the case shown in FIG. 8, it is possible to avoid an arrangement in which the cameras C1 and C2 face each other. Although not shown in this embodiment, even when there are two wafer marks located at the same position on the Y axis, the extending directions of the respective wafer marks are arranged to be different from each other. The position of the stage 201 is finely adjusted by the control unit 205 based on the observation result by each camera, and the alignment of the position of the wafer 40 with the position of the mask 50 is completed. Thereafter, the exposure light generation unit 204 is activated to irradiate the pattern light at the center of the mask with exposure light, thereby performing pattern exposure.

When the mask 50 side is fixed and the wafer 40 side is moved by the stage 201 to align the position of the wafer mark with respect to the mask mark, the observation optical system determines the arrangement position in advance with respect to the fixed mask mark. It is good to put it. Therefore, when the observation optical systems are arranged such that the two observation optical systems are not positioned on a virtual line connecting any two of the plurality of mask marks in a plan view and the extension line, the arrangement positions of the observation optical systems overlap. This is convenient because it is possible to avoid as much as possible or too close. In other words, the virtual line projected on the XY plane, which is the direction of the optical axis of the observation optical system, is an extension of the line segment of one wafer mark, so that one wafer mark and another wafer mark are In the virtual line to be connected, the extending direction of each wafer mark may be set so that the line segment of another wafer mark does not extend in the same direction as the virtual line.

Further, it is only necessary that the directions of the optical axes projected on the XY plane of the respective observation optical systems are different so that the cameras and the illumination light sources do not interfere with each other. Each of the mask marks M1 to M3 and the wafer mark W1 may be used. The positions of W3 to W3 on the isolation region are not limited to those in the above embodiment. For example, W1 may be disposed at the center of the upper side, and W2 may be disposed at the center of the left side. Further, the shapes of the mask mark and the wafer mark can be changed.

Here, an example of a method of correcting a shift between the wafer 40 and the mask 50 based on the detection results of the mask marks M1 to M3 and the wafer marks W1 to W3 as described above will be described.

When the wafer stage is moved and the mask pattern portion 53 is opposed to one pattern region 41 on the wafer 40, the global alignment has been performed in advance, so that the three mask marks M1, M2, and M3 correspond to the openings. The wafer marks W1, W2, and W3 to be observed can be observed. The shift amounts of the wafer marks W1 to W3 with respect to the mask marks M1 to M3 at this time are d1, d2, and d3, respectively.

Assuming that the position of the wafer stage 201 is adjusted so as to eliminate the deviations d1 and d2 of the wafer marks W1, W2 and W3 from this state, the deviation amount of the wafer marks W1 and W2 changes to zero and the wafer mark W3 The deviation amount d3 also changes. Assuming that the shift amount after this change is d3 ', d3' is geometrically obtained based on d1d2, d3 and the inclination angle of the wafer mark W3 with respect to the X axis (45 degrees in FIG. 12).

In this state, the intersection of a straight line passing through the center of the mask mark M1 and extending in the X-axis direction and a straight line passing through the center of the mask mark M2 and extending in the Y-axis direction is defined as a rotation reference. Assuming that the wafer 40 is rotated around this rotation reference in this state, the shift amounts of the wafer marks W1 and W2 do not change and only the wafer mark W3 changes the shift amount. Therefore, in this state, if the wafer 40 is rotated around the rotation reference so as to eliminate the shift amount d3 ', the shift amounts of the wafer marks W1, W2, and W3 become zero. That is, the mask pattern portion 53 and the corresponding pattern region 41 of the wafer 40 are aligned.

Based on the above, if the shift amounts d1, d2, and d3 in the initial state can be known, the shift amounts d1, d2, and d3 are determined based on these values and the XY coordinates of the positions of the mask marks M1 to M3. , The amount of movement of the wafer stage in the X-axis direction, the amount of movement in the Y-axis direction, and the angle of rotation required to correct the above. The control unit 205 incorporates a program for calculating the amount of movement and rotation angle to be adjusted based on the detected deviation amounts d1, d2, and d3, and performs alignment based on the calculation results.

FIGS. 13 to 18 are explanatory views for explaining an improved example in which a crystal pattern is used as a mask substrate and a mask pattern and a mask mark are formed by wet etching suitable for mass production.

The mask 50 of the crystal substrate is, for example, a silicon wafer substrate, and has a diameter of 4 inches, a thickness of the peripheral portion 51 of 0.5 mm, and a thickness of the membrane portion 52 in the central region of 10 μm. In this example of the wafer, the end face of the orientation flat 54 has a plane index (100) of the mirror, the wafer plane has a plane index (001), and the crystal orientation [010] corresponds to a 90-degree direction (left-right direction in the drawing) with respect to the crystal orientation [100]. It has become. In this case, as compared with a crystal orientation <100> which is a set of crystallographically equivalent crystal orientation [001], crystal orientation [010], crystal orientation [100], etc., an orientation <110 inclined at 45 ° with respect to this orientation. In <2>, the wet etching using KOH, EDP or the like has a low etching rate, and is a crystal anisotropic etching. Therefore, as shown in FIGS. 10 and 12, when the direction of the edge used for the alignment detection of the mask mark M3 is set oblique to the X axis ([010]) or the Y axis ([100]), Will be affected by the anisotropy of

FIG. 14 shows an example in which poor etching has occurred in a mask mark (through hole) of a wafer due to crystal anisotropic etching. A defect is likely to occur in a portion where the crystal plane {110} of the wafer is exposed. Although there is an etching method that does not cause crystal anisotropy due to the crystal plane {110}, wet etching has an advantage that etching can be performed easily at a low cost and mass production is relatively easy.

FIG. 15 shows an example in which the mask mark M3 arranged obliquely to the crystal orientation <100> is formed by a mask pattern in consideration of the crystal anisotropy. In this example, sides ab and af serving as reference portions used for observation in the mask pattern are formed along the crystal orientations [100] and [010], respectively. The sides cd and de are also formed along the crystal orientations [100] and [010], respectively. Thereby, the side ab and the side af, the side cd and the side de are accurately patterned (etched) without being affected by the crystal anisotropy.

As shown in FIG. 16, when the wafer mark W3 of the wafer to be processed is included in the opening of the mask mark M3, for example, a vertex a of the pattern and a shadow S (a reflection image of the mask edge baf from the substrate 40 to be processed) ) Corresponds to ΔZ shown in FIG. Further, a deviation Δα between the line segment connecting the vertices a and d and the wafer mark W3 is observed by the camera C3. Specifically, the horizontal position of the line segment ad is obtained by detecting the positions of the side ab and the side af on a specific detection line that intersects the side ab and the side af in FIG. Further, the horizontal position of W3 is obtained on a specific horizontal detection line corresponding to a bright portion in the opening. If the difference between the brightness of the shadow portion and the brightness of W3 is sufficient, the detection lines of the sides ab and af and the detection line of W3 can be shared. Therefore, similarly to the case shown in FIG. 6, the distance between the processing target substrate 40 and the mask 50 can be adjusted, and the position of the mask mark M3 and the position of the wafer mark W3 can be adjusted. Also, there is little etching failure in the reference portion baf to be compared with the mask pattern. ,
FIG. 17 shows another example (diamond) in which the mask mark M3 arranged obliquely to the crystal orientation <100> is formed by a mask pattern in consideration of the crystal anisotropy. Also in this example, sides ab and ad serving as reference portions used for observation in the mask pattern are formed along the crystal orientations [100] and [010], respectively. The sides bc and cd are also formed along the crystal orientations [010] and [100], respectively. Thereby, the sides ab and ad, and the sides bc and cd are accurately patterned without being affected by the crystal anisotropy.

As shown in FIG. 18, when the wafer mark W3 of the processing target wafer is in the opening of the mask mark M3 shown in FIG. 17, for example, the vertex a of the pattern and the shadow S (the processing target substrate of the mask edge bad) The distance from the vertex of the reflected image (from 40) corresponds to ΔZ shown in FIG. Further, a deviation Δα between the line segment connecting the vertices a and c and the wafer mark W3 is observed by the camera C3. Therefore, similarly to the case shown in FIG. 6, the distance between the processing target substrate 40 and the mask 50 can be adjusted, and the position of the mask mark M3 and the position of the wafer mark W3 can be adjusted. Further, there are few etching defects in the reference portion bac to be compared with the mask pattern.

(4) By determining the shape of the alignment mark W3 of the mask 50 in consideration of the existing direction of the crystal plane orientation of the substrate, it is possible to reduce the etching failure rate due to the crystal anisotropic etching.

In the above-described embodiment, the example of the alignment apparatus used for the exposure apparatus has been described. However, similarly, the present invention can also be used for an ion implantation apparatus and a sputtering apparatus which require alignment between a processing target substrate and a mask. .

As described above, according to the present embodiment, the observation optical systems do not face each other and can be arranged as far as possible from the adjacent observation optical systems. Becomes easier. Thereby, the optical axes of the illumination system and the imaging system are made to coincide with each other, and it becomes easy to sufficiently secure the light amount.

Also, it is possible to use a large-diameter lens with high detection resolution that achieves high alignment accuracy. In the case of exposure, ion implantation, or the like, there is no need for a structure or a step of retreating a large-diameter lens each time to prevent interference, which is advantageous in terms of throughput.

Further, in the embodiment, the example in which the crystal orientation of the main surface of the mask wafer 50 is [001] and the crystal orientation [100] is present in the direction of the orientation flat 54 is described, but the crystal orientations [100], [010], Since [001] has the same property due to symmetry, a combination in another crystal orientation is also substantially the same as the embodiment.

FIG. 2 is an explanatory diagram illustrating an outline of a semiconductor manufacturing apparatus. FIG. 3 is an explanatory diagram illustrating an outline of a process device. FIG. 3 is an explanatory diagram illustrating an example of an alignment mark (wafer mark) formed on a substrate to be processed (wafer). It is explanatory drawing explaining the example of a mask. FIG. 3 is an explanatory diagram illustrating a mutual positional relationship between a mask mark, a wafer mark, an illumination light source, and a camera. FIG. 4 is an explanatory diagram illustrating an example in which a mask mark and a wafer mark are read by a camera and image processing is performed. FIG. 3 is an explanatory diagram illustrating a relationship between an exposure region and a large-diameter (high numerical aperture) lens. FIG. 3 is an explanatory diagram illustrating an arrangement relationship between a wafer mark, a mask mark, an illumination light source, and a camera. FIG. 4 is an explanatory diagram illustrating an example of an alignment mark (wafer mark) formed on a substrate to be processed (wafer) according to the present invention. FIG. 4 is an explanatory diagram which states an example of a mask according to the present invention. FIG. 4 is an explanatory diagram illustrating a state in which a wafer mark is viewed through a mask mark (opening). FIG. 3 is an explanatory diagram illustrating an arrangement relationship between a wafer mark, a mask mark, an illumination light source, and a camera according to the present invention. FIG. 13 is an explanatory diagram illustrating crystal anisotropy. FIG. 14 is an explanatory diagram illustrating an example of occurrence of defective burn due to crystal anisotropic etching. FIG. 15 is an explanatory diagram illustrating an example (arrow blade shape) of a mask mark in consideration of crystal anisotropic etching. FIG. 16 is an explanatory diagram illustrating an example in which the wafer mark W3 of the substrate to be processed is visible within the mask mark M3 in consideration of the crystal anisotropic etching. FIG. 17 is an explanatory diagram illustrating another example (diamond) of a mask mark in consideration of crystal anisotropic etching. FIG. 18 is an explanatory diagram illustrating an example in which the wafer mark W3 of the substrate to be processed is visible within the diamond-shaped mask mark M3 in consideration of the crystal anisotropic etching illustrated in FIG.

Explanation of reference numerals

50 stage, 40 wafer (substrate to be processed), 50 mask, 203 observation unit (illumination light source, camera), 204 exposure light generation unit, 205 control unit, L1 to L3 illumination light source, M1 to M3 mask mark, W1 to W3 wafer mark

Claims (11)

A substrate to be processed in which a plurality of alignment marks for position adjustment are formed around the unit processing region,
A stage for mounting the substrate to be processed,
A mask having a mask pattern for transferring a predetermined pattern to a unit processing region of the substrate to be processed, and a plurality of mask marks formed around the mask pattern corresponding to the plurality of alignment marks;
A mask holder for holding the mask on the substrate to be processed,
A plurality of illumination light sources that illuminate the alignment mark and the mask mark provided corresponding to each of the alignment marks,
A plurality of cameras respectively corresponding to each alignment mark and observing the alignment mark and the mask mark illuminated by the illumination light source,
A control unit that adjusts a relative position between the processing target substrate and the mask based on the observation result,
An alignment adjustment device, wherein each camera is arranged such that no two cameras are located on an imaginary line connecting any two of the plurality of mask marks and an extension of the virtual line. The alignment adjusting device according to claim 1, wherein the extending directions of the plurality of alignment marks are different from each other. The extending direction of each alignment mark is set so that a line segment of both alignment marks does not extend in the same direction as the virtual line on a virtual line connecting any two of the plurality of alignment marks. Or the alignment adjusting device according to 2. 4. The alignment adjusting device according to claim 1, wherein the stage is configured to be movable in steps in the X-axis and Y-axis directions orthogonal to each other. The at least three alignment marks are formed, and a direction of a line segment of each alignment mark is 0 degree, 45 degrees, and 90 degrees, respectively, at an angle formed between each line segment and the X axis or the Y axis. 5. The alignment adjusting device according to 4. 6. The alignment adjustment device according to claim 1, wherein the substrate to be processed is a wafer, and the alignment mark is a wafer mark formed on the wafer. The mask is formed by etching the mask pattern and a plurality of mask marks on a crystalline substrate, and an edge direction of the mask marks used as a reference for observation matches a specific crystal direction of the crystalline substrate. The alignment adjustment device according to claim 1, wherein the alignment adjustment device is formed using a specific plane orientation among the plurality of plane orientations. The alignment adjusting device according to claim 7, wherein the {crystalline substrate is a silicon substrate, and the specific plane orientation is {100}. An exposure apparatus using the alignment adjustment device according to any one of claims 1 to 8. An ion implantation device using the alignment adjustment device according to any one of claims 1 to 8. A sputtering apparatus using the alignment adjusting device according to any one of claims 1 to 8.