JP2006003419A - Exposure method and device, and photomask - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exposure device which does not require mask replacement and is free of lowering of throughput, an exposure method and a photomask used in the same. <P>SOLUTION: The exposure device includes a light source 1 which emits light having a predetermined wavelength, a photomask 3 which has a pattern comprising at least two patterns alternately arranged at predetermined pitches and through which light from the light source passes, an optical system 5 which is disposed between the photomask and an object to be exposed and forms the image of the pattern of the photomask on the object to be exposed, and a mask moving mechanism 4 for moving the photomask only by a predetermined pitch with respect to a first position at the point of time when the object to be exposed is exposed through the pattern of the photomask at the first position. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exposure method, an exposure apparatus, and a photomask, and more particularly, to a method for manufacturing a member for a display device including a regular set of pixels having the same shape, and a photomask.

  For example, a liquid crystal display device is generally thin, lightweight, has low power consumption, and is easy to perform color display, and is widely used as a display for personal computers and various portable information terminals. When the liquid crystal display device is an active matrix type, a thin film transistor is provided as a pixel switching element.

  A glass substrate used for a semiconductor substrate or a liquid crystal display has a structure in which a plurality of materials such as a semiconductor layer and an insulator layer are patterned and laminated. For this patterning, a photolithography technique is used.

  In lithography technology, a photoresist layer is formed on a material to be processed, a photoresist layer is formed, a predetermined pattern is exposed on the resist layer, and development is performed. It is widely used to obtain various patterns.

However, in lithography technology, a resolution that requires the resolution of an exposed pattern due to the depth of focus (DOF) of an imaging optical system incorporated in an exposure apparatus used for pattern exposure is required. May not be reached. In addition, the relationship between the resolution of the image on the resist layer in exposure and the DOF is
DOF = k · R ² / λ
λ: Light source wavelength, R: Line width (resolution), k: Proportional coefficient (value of about 1 depending on the process).

Against this background, a technique called double exposure has been proposed (see Non-Patent Document 1, for example).
Resolution Enhancement Techniques in Optical Lithography, AKWong, 172-175, SPIE Press.

Non-Patent Document 1 includes
1) Improve the depth of focus of the contact hole pattern by multiple exposure: Improve the depth of focus by multiple exposure of the contact hole pattern while shifting the focal position in the optical axis direction.
2) Forming sharp contact holes by double exposure: Contact holes are rounded due to the resolution limit of the optical system. Forming a hole, and
3) Double exposure using phase shift mask and trimming exposure: Shibuya-Levenson type phase shift mask (Alternating PSM) can form fine L (line) and S (space), but synchronous L Since it is difficult to form patterns other than S and S, a pattern having fine lines is freely generated by double exposure using a Shibuya-Levenson type phase shift mask and a trimming mask.
This is described.

  However, double exposure or multiple exposure requires the production of two types of photomasks, resulting in an increase in cost and / or delivery time (time required to obtain the photomask).

  In the exposure process, at least the mask needs to be replaced. For this reason, there is a problem that throughput decreases.

  An object of the present invention is to provide an exposure apparatus, an exposure method, and a photomask used therefor that do not require a plurality of masks and that do not require mask replacement.

  The present invention relates to an exposure method in which a pattern of a photomask is imaged and exposed on a surface to be exposed, using a photomask having a pattern in which at least two types of patterns are arranged in the same plane at a predetermined pitch A step of performing a first exposure and a second time in a state where the at least two types of patterns are overlapped on the exposed surface by relatively moving the photomask and the exposed surface by a distance corresponding to the predetermined pitch. The exposure method characterized by including the process of performing these exposures.

  The present invention is also an exposure method in which a pattern of a photomask is imaged on an exposed surface for exposure, and the photomask has a pattern in which at least two types of patterns are arranged at a predetermined pitch, It is an object of the present invention to provide an exposure method characterized in that the two types of patterns are exposed in a non-interfering manner on the exposed surface using an optical system.

  The present invention also provides that at least two types of patterns which can complement each other in shape or optical characteristics by movement at a predetermined interval in a predetermined direction are alternately arranged in a single plane at a predetermined pitch associated with the movement at a predetermined interval. The present invention provides a photomask that is characterized by the above.

  The present invention also includes a light source, a photomask that has a pattern in which at least two types of patterns are arranged at a predetermined pitch, and modulates light from the light source, and between the photomask and an object to be exposed. An optical system for imaging the pattern of the photomask on the object to be exposed, and a second pattern of the photomask after the first pattern of the photomask is exposed to a predetermined region of the object to be exposed. And a mask moving mechanism for exposing the pattern to a predetermined area of the object to be exposed.

  The present invention also includes a light source, a photomask having a pattern in which at least two types of patterns are arranged at a predetermined pitch, and a light mask from which light from the light source is transmitted, and between the photomask and an object to be exposed. An optical system that forms an image of the pattern of the photomask at a predetermined position of the object to be exposed; and a predetermined position between the photomask and the object to be exposed; An exposure apparatus comprising: a multi-exposure optical element capable of irradiating the object to be exposed in a state where two types of patterns are overlapped in a non-interfering manner.

  The present invention is also a photomask that has a pattern in which at least two types of patterns are arranged at a predetermined pitch and modulates light from a light source.

  According to the pattern exposure method and the exposure apparatus of the present invention, only one mask needs to be manufactured, mask replacement is unnecessary, and as a result, it is possible to suppress an undesired decrease in throughput.

  Further, according to the pattern exposure method and the exposure apparatus of the present invention, since two types of patterns are exposed in a non-interfering manner on the surface to be exposed, there is no need to move the mask and the number of exposures As a result, throughput is improved.

  Furthermore, by using the pattern exposure method and the exposure apparatus of the present invention, the number of pattern exposure (pattern formation) steps among the steps of manufacturing a semiconductor active element, a liquid crystal display device and the like is reduced.

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

  FIG. 1 schematically shows an example of an exposure apparatus to which the embodiment of the present invention can be applied.

  The exposure apparatus shown in FIG. 1 has a light source 1 that outputs light of a predetermined wavelength for exposure processing. The light flux from the light source 1 is approximately uniformized in light intensity in a plane orthogonal to the traveling direction of the light flux through the illumination optical system 2 and is irradiated to the photomask 3 provided at the illumination position of the illumination optical system 2. . In addition, as will be described below with reference to FIG. 2, the photomask 3 includes first and second patterns in which two patterns that can provide a single pattern by being overlapped with each other are alternately arranged in a predetermined direction. Consists of patterns. The photomask 3 is held by a mask holder 4 formed so as to be able to reciprocate in a predetermined direction, for example, a direction indicated by an arrow F in FIG. The illumination optical system 2 is moved to the illumination position.

  The light that has passed through one of the patterns of the photomask 3 is selectively given a light intensity distribution according to the pattern and is incident on the imaging optical system 5.

  The light incident on the imaging optical system 5 forms an image on the substrate 7 to be exposed held on the stage 6. That is, the pattern of the photomask 3 is optically transferred to a predetermined exposed surface of the substrate 7 held on the stage 6.

  The stage 6 can arbitrarily move the substrate 7 along the image forming plane (hereinafter referred to as an exposure surface) by the image forming optical system 5 under the control of the XY controller 8, for example. The XY controller 8 moves the movement amount and movement timing of a movement mechanism (not shown) of the mask holder 4 in association with the movement of the stage 6 in a predetermined direction. Therefore, an arbitrary position on the substrate 7 is irradiated at predetermined intervals according to the pitch of at least two patterns formed on the photomask 3.

  As shown in FIG. 2, the photomask 3 is exposed to the substrate 7 by combining, for example, a transparent glass substrate 3a with a first pattern SA that modulates light passing through the glass substrate 3a and the first pattern SA. The second pattern SB for providing a predetermined pattern to be formed is alternately formed at a predetermined pitch. Although the photomask 3 will be described in detail later, it may be a phase shift mask that gives a phase difference for each arbitrary region with respect to light transmitted through the photomask 3.

  Note that quartz glass or the like is used as a substrate material that can be used for the substrate 3 a of the photomask 3.

  Next, the basic principle of the present invention will be described with reference to FIG. For example, when the pattern formed on the exposure object, that is, the substrate 7 is a pattern for a display such as an LCD (Liquid Crystal Display), the pattern is a repetitive pattern in units of one pixel. In this case, the resolution on the surface to be exposed, that is, the substrate 7 can be increased or the depth of focus can be improved by using the well-known double exposure.

  That is, the photomask 3 to which the first and second phase shift patterns SA and SB are given is, for example, “SB-SA-SB” as shown in FIG. These three regions are positioned at a first position which is a positional relationship such that the substrate 7 is exposed. In this state, a first pattern is formed on the substrate 7 by exposure light from the light source 1 shown in FIG.

  Next, as shown in FIG. 2B, the two-direction photomask 3 indicated by the arrow F is moved so that the pattern of the three areas “SA-SB-SA” is exposed on the substrate 7. The photomask 3 is positioned at a second position that is a positional relationship, and a second pattern is formed on the substrate 7.

  As described above, the repetition cycle (pitch) [d] is used as a repeating unit, and the two patterns (double exposure of two patterns) are used as a final pattern. By using the photomask 3 in which the patterns SA and SB are alternately arranged, as shown in FIG. 2C, only one photomask 3 is used, and a plurality of optical elements can be further replaced without mask replacement (process). A pattern having a predetermined resolution can be formed on the substrate 7 without configuring the system.

  More specifically, the pattern to be finally formed is a repeating unit of the pitch d, and the first pattern (SA) and the second pattern (SB) are formed, for example, on the same surface of the single photomask 3. That is, considering the double exposure suitable for setting the repeating unit to [d], the first pattern SA and the second pattern SB suitable for it are formed. Accordingly, the first pattern SA and the second pattern SB are alternately arranged on the photomask 3 (FIGS. 2A and 2B). Note that the repeating unit [d] is defined as one line of pixels in either the row direction or the column direction or an integer multiple thereof when the substrate 7 is for a display device.

  As a result, as shown in FIG. 2C, the exposed surface of the substrate 7 is double-exposed with the first pattern SA and the second pattern SB, and the target pattern is formed on the entire surface of the substrate 7. (SA + SB) is formed.

  Thus, by producing only one photomask 3, a predetermined resolution or DOF pattern can be formed on the substrate 7. Further, although it is necessary to move the photomask 3, it is not necessary to replace the photomask 3. Therefore, there is little decrease in throughput. Further, the exposure apparatus can be simplified and simplified without providing an optical system through two masks for double exposure.

  FIG. 3 is a schematic diagram illustrating an example of a combination of the two patterns illustrated in FIG. 2 and features unique to the pattern.

  For example, consider a case where a line and space pattern close to the resolution limit is exposed using the exposure apparatus shown in FIG. The line and space pattern is an opening having a predetermined width, that is, a region where the exposure amount is 100% (line region), and a light shielding portion formed with a width equal to the opening, that is, a region where the exposure amount is 0%. This is a mask pattern in which (space) regions are alternately arranged.

  As shown in FIGS. 3A and 3B, a first pattern 301 and a pattern 310 are prepared by extracting every other line portion from the line and space pattern.

  In exposure using each pattern, as shown in the aerial image diagrams of FIGS. 4A and 4B, the influence (proximity effect) from adjacent lines is reduced, and as a result, FIG. As shown in c), the magnitude (relative value) of the light intensity in the space portion decreases. 4A and 4B show the results (light intensity) obtained at a wavelength of 0.365 nm, NA = 0.15, and σ value (coherence factor) = 0.5, respectively.

  On the other hand, when a line-and-space pattern is formed by one exposure using a pattern provided with all the required spaces (indicated by 311 in FIG. 3C), as shown in FIG. In addition, unnecessary light intensity in the space portion increases (contrast decreases). Note that FIG. 5 shows the result (light) obtained under the same conditions as in FIGS. 4A and 4B, that is, with a wavelength of 0.365 nm, NA = 0.15, and σ value (coherence factor) = 0.5. Strength).

  As described above, by using the double exposure shown in FIGS. 4A and 4B, a high contrast, that is, a high resolution and a deep depth of focus can be realized.

  Note that the two patterns 301 and 310 shown in FIGS. 3A and 3B are, in other words, patterns in which an exposure area based on the second pattern is located between exposure areas based on the first pattern. is there.

  FIG. 6 is a schematic diagram illustrating an example of a combination of two patterns illustrated in FIG. 2 and an example of another embodiment of features unique to the pattern. The pattern shown in FIG. 6 is assumed to be a pattern that can be used as a gate pattern of a TFT, for example. Accordingly, in the thin line portion, it is required that the thin line width secures the range of the focal depth.

  For example, as illustrated in FIG. 6A, a 180 ° phase difference is provided on both sides of the light shielding unit 610 in the first pattern 601 in which the shielding unit 610 is formed at a predetermined position. Therefore, in the example shown in FIG. 6A, by using a positive resist, for example, the phase difference between the vicinity of the center and the peripheral portion is 180 ° (the phase near the center is 180 ° and the phase of the peripheral portion is 0 °. ) However, in this state, an undesired phase difference boundary 613 is generated, and the light intensity at that portion becomes “0”, so that a resist residue is generated. In order to remove this, unnecessary resist remaining portions are trimmed using the second pattern 602 shown in FIG.

  As a result, as shown in the resist pattern diagram of FIG. 6C, the phase difference boundary portion 613 generated in the region connecting the two shielding portions 610 is removed, and only the pattern corresponding to the two shielding portions 610 is obtained. Obtainable.

  The two patterns shown in FIGS. 6A and 6B are patterns in which the first pattern 601 has a first phase region and a second phase region, and the second pattern 602 is This is a pattern capable of trimming (exposing) an unnecessary portion generated when the first pattern alone is used.

  FIG. 7 shows a pattern assuming a TFT gate pattern as shown in FIG.

  As shown in FIG. 7A, the first pattern 701 is a pattern having a first phase, for example, a 0 ° region and a second phase, for example, a 180 ° region, and each region is independent. And it has the structure arranged in series. Note that the first and second phase regions are divided by a light shielding portion 710 similar to the pattern shown in FIG. Further, both end portions of the light shielding part 710 are connected by a large continuous light shielding part 711 (two places).

  On the other hand, as shown in FIG. 7B, the second pattern 702 includes both the first and second regions in which the phase difference divided by the two light shielding portions 710 in the first pattern 701 is 180 °. It is formed in the shape of a belt that covers. Accordingly, the second pattern 702 provides a continuous exposure portion in the edge region of the mask that was not exposed in the first pattern 701. At this time, the resist residue corresponding to the boundary portion of the phase difference as described with reference to FIG. 6A does not occur at the boundary of the exposure region of the pattern 702.

  Thereby, a pattern portion 731 including two shielding portions 710 as shown in FIG. 7C is obtained.

  The two patterns shown in FIGS. 7A and 7B are patterns in which the first pattern has the first phase region and the second phase region, and the second pattern has the first pattern. It is a pattern that generates an exposure region that connects the first phase region and the second phase region of one pattern.

  FIG. 8 is a pattern assuming a TFT gate pattern as described above with reference to FIGS. 6 and 7.

  As shown in FIG. 8A, a fine line portion is formed by a pattern 801 in which a plurality of fine lines having a phase difference of 180 ° are formed. It should be noted that the intensity of the light transmitted through each pattern, that is, the exposure amount, is the same in any part. At this time, the exposure amount is approximately “½” of the necessary exposure amount specific to the resist material.

  Subsequently, as shown in FIG. 8B, when the exposure amount provided by the pattern 801 shown in FIG. 8A is “1”, the exposure amount is approximately double, that is, necessary exposure inherent to the resist material. Trimming is performed using a pattern including a plurality of block patterns of a predetermined shape defined to be a quantity and a pattern 802 including a band-like pattern connecting the respective block patterns to each other. In FIG. 8B, the pattern 802 uses, for example, a gray tone. In addition, the exposure amount of the band-shaped pattern portion is at least the same because light having a light intensity of approximately “½” of the required exposure amount of the resist material has already been irradiated by the pattern 801 shown in FIG. Any light intensity may be used.

  As a result, since the exposure amount reaches the required exposure amount of the resist material, a pattern 841 having a target shape as shown in FIG. 8C is obtained.

  Note that the two patterns shown in FIGS. 8A and 8B are patterns in which transmission regions having a phase difference of 180 ° are alternately arranged through the shielding regions. The target shape is, for example, a rectangle or a square, and the first pattern and the second pattern are, for example, a rectangle. That is, the common part of the exposure area by the first pattern and the exposure area by the second pattern is the target shape.

  FIG. 9 can be used when, for example, a contact hole pattern is formed.

  For example, a pattern used to form a contact hole is not shown, but generally, the transmittance of the opening is 100% and the phase difference from the peripheral shielding part is 0 °.

  On the other hand, as shown in FIG. 9A, when a pattern 901 in which the peripheral portion (shielding portion) is partially transmissive, the transmittance is set to about 7%, and the phase difference is set to about 30 ° is used, the depth of focus is used. 909 changes, and the position of the center value moves to the side away from the optical system 910 (downward in FIG. 9B). Similarly, as shown in FIG. 9C, a pattern 902 is used in which the transmittance of the peripheral portion (shielding portion) is the same as that of the pattern 901 and the phase difference is the reverse sign (in this example, about −30 °). Then, the center value of the depth of focus 909 moves to the side closer to the optical system 910 as shown in FIG.

  Therefore, as shown in FIG. 9E, in the state where the exposure with the pattern 901 and the pattern 902 is overlapped by two exposures, the DOF (depth of focus) is expanded as shown in FIG. 9F. A state is obtained.

  That is, as shown in FIG. 9, by using two patterns whose target shapes are the same and whose phase differences are opposite to each other due to the combination of the transmission area and the partial transmission area, an area where a predetermined depth of focus can be obtained is expanded. The

  FIG. 10 is a schematic diagram for explaining an example of another embodiment of the exposure apparatus shown in FIG. In FIG. 10, the light source and the stage are the same as those in FIG.

  The exposure apparatus shown in FIG. 10 is characterized in that a birefringent material 11 is provided at an arbitrary position between the photomask 3 and the substrate 7 (the imaging optical system 5 is omitted in shape). .

  Specifically, if the two patterns SA and SB shown in FIGS. 2A and 2B can be superimposed on the exposed surface in a non-interfering manner, the exposure process is completed once. In that case, it is not necessary to consider the reduction in throughput caused by moving the photomask.

  More specifically, for example, immediately after the photomask 3 (on the substrate 7 side), a parallel plate 11 in which a birefringent material is formed in a plate shape with a predetermined thickness is provided.

  For example, as shown in FIG. 10B, the parallel plate (birefringent material) 11 cuts the birefringent material so that the extraordinary ray e is at an angle θ with respect to the ordinary ray o in consideration of the crystal axis. This can be easily obtained. That is, the light from the light source that has passed through the parallel plate 11 is separated by a predetermined separation width d based on the direction of polarization, and then is collimated.

  As for the light intensity at the exposure position (image plane) of the substrate 7, the two light beams are translated by a lateral shift amount with respect to the separation width d and are superimposed again. If the incident light is random polarized light or isotropic polarized light, the intensity ratio of the separated light is 1: 1. Further, as shown in FIG. 10C, since the two light beams do not interfere with each other, the light intensity on the substrate 7 is simply the sum of the two light beam intensities. The lateral shift amount is determined by a value obtained by multiplying the separation width d of the parallel plate 11 by the magnification (m) of the imaging optical system 5.

The separation width d can be adjusted by the type of the birefringent material (parallel plate) 11, how to cut out crystal axes (direction), and the thickness of the birefringent material. As an example, when the birefringent material is a uniaxial crystal parallel plate, and as shown in FIGS. 2B and 2C, the separation width d when a light beam is incident perpendicularly to the surface of the plate is:
d = tanφ × t,
tanφ = {(no ² −ne ² ) sin θ · cos θ} / {ne ² cos ² θ + no ² sin ² θ}
φ is the angle between the extraordinary ray and the normal of the incident interface,
θ is the angle between the optical axis and the normal of the incident interface,
ne is the refractive index of extraordinary rays,
no is the refractive index of ordinary light,
t indicates the thickness of the birefringent material, respectively (1)
It can ask for.

  For example, a necessary thickness t for giving a separation width d = 25 μm to light having a wavelength of 248 nm using a crystal having a refractive index of no = 1.016, ne = 1.6124, θ = 45 ° is obtained from the equation (1). T = 3697 μm.

  The birefringent material (parallel plate) 11 is provided at any position between the photomask 3 and the substrate 7, that is, between the photomask 3 and the imaging optical system 5, as shown in FIG. Or between the imaging optical system 5 and the substrate 7 (exposed surface).

  By the way, when the number of the birefringent material (parallel plate) 11 is one, a difference in optical path length occurs between the ordinary ray o and the extraordinary ray e, resulting in a phase difference, and imaging of two light beams in the optical axis direction. The problem is that the positions are different. To avoid this, as a birefringent material 11, as shown in FIG. 12, a pair of calcite plates of the same thickness cut along the cleavage plane and bonded so that the corresponding surfaces are perpendicular to each other. A certain Savart plate (two parallel plane plates of equal thickness cut out from a uniaxial crystal so that the optical axis forms about 45 °) may be used. That is, by using the Savart plate, the optical path lengths of the two light beams (ordinary ray o and extraordinary ray e) become equal, so the above-described phase difference does not occur.

  Further, as shown in FIG. 13, a special Savart plate proposed by Francon, in which a half-wave plate 121 is inserted between parallel plates of equal thickness polished at 45 ° with respect to the optical axis. It is also possible to use 111.

Further, as shown in FIG. 14A, an optical element capable of separating different polarized light at different angles as the birefringent material 11 may be used in the vicinity of the pupil (aperture) 51 of the imaging optical system 5. it can. For example, a Wollaston prism can be used as the birefringent material 11 shown in FIG. In this case, the separation angle θ (see FIG. 14B) at which the two light beams are separated is
Sinθ = 2 (ne-no) tanθ ·
(1 - {(ne-no ) 2/2} tan 2 θ
^{+ {(Ne-no) 3} /3} tan 3 θ
^{- {(ne-no) 4} /4} tan 4 θ + ···)
... (2)
Can be obtained.

  10 to 14, the direction of the light from the light source, that is, the polarization direction of the light beam is random (or isotropic) as indicated by the symbol f in FIG. 15A (see FIG. 15A). However, if the polarization direction is biased (representative example: linearly polarized light as indicated by the symbol g in FIG. 15B), the exposure amount in double exposure is shown in FIG. 15B. So that it becomes non-uniform. In such a case, it is desirable to provide an optical element, such as a retarder, for correcting the polarization direction between the light source and the birefringent material 11 as shown in FIG.

  Referring to FIG. 15 (c), the retarder (polarization correction element) even when the polarization direction of the light from the light source is biased (representative example: linearly polarized light as indicated by symbol h in FIG. 15 (c)). ) A half-wave plate functioning as 131 is provided at a predetermined position in the optical path, and the direction of polarization is rotated by 45 ° as indicated by reference numeral h ′ in FIG. The component ratio can be 1: 1. Therefore, even if the birefringent material 11 is a parallel plate made of a uniaxial crystal whose polarization direction cannot be corrected, for example, as shown in FIG. 2B, the two lights reaching the substrate 7, that is, the exposure target, The light intensities of the two light beams can be made substantially equal. Although not shown, a quarter wave plate may be used as the polarization correction element, and the polarization of each light beam may be circularly polarized to eliminate the directionality of the polarization.

  16 shows, for example, an electronic device (semiconductor active element) on a surface to be processed on the substrate 7 by using an imaging pattern formed on the substrate 7 by any of the exposure apparatuses shown in FIG. 1, FIG. 10, or FIG. It is process sectional drawing which shows the process of producing ().

As shown in FIG. 16A, a base film 71 (for example, SiN having a thickness of 50 nm and a SiO ₂ layer having a thickness of 100 nm is laminated on an insulating substrate 70 (for example, alkali glass, quartz glass, plastic, polyimide, etc.). A substrate 4 to be processed on which an amorphous semiconductor film 72 (e.g., Si, Ge, SiGe, etc. having a film thickness of about 50 nm to 200 nm) is formed using a chemical vapor deposition method, a sputtering method, or the like. To do. Next, for example, the first pattern (SA) portion of the photomask 3 described above with reference to FIGS. 2A and 2B is aligned, and part or all of the surface of the amorphous semiconductor film 72 is aligned. For example, a predetermined region is irradiated with laser light 73 (for example, KrF excimer laser light or XeCl excimer laser light) to perform exposure with the first pattern (SA).

  Subsequently, the photomask 3 is moved by a predetermined amount, and the second pattern (SB) portion is aligned. Thereafter, similarly, a part or all of the surface of the amorphous semiconductor film 72, for example, a predetermined region is irradiated with a laser beam 73 (for example, a KrF excimer laser beam or a XeCl excimer laser beam), and the second region is irradiated. Overlay exposure is performed using the pattern (SB). In each step, the various patterns described above with reference to FIGS. 2, 3, and 6 to 9 are combined, and the irradiation position (exposure position) of the target to be processed is exposed twice. It is.

  By irradiating the substrate 70 with the laser beam 73, a predetermined pattern is exposed on the semiconductor film 72 of the substrate 70 as shown in FIG.

Thereafter, as shown in FIG. 16C, the polycrystalline semiconductor film or the single crystallized semiconductor film 74 is processed into an island-shaped semiconductor film 75 that becomes a region for forming a thin film transistor, for example, by photolithography. Subsequently, a SiO ₂ film having a thickness of 20 nm to 100 nm is formed as a gate insulating film 76 on the surface of the semiconductor film 75 by using a chemical vapor deposition method or a sputtering method.

  Next, as shown in FIG. 16D, for example, a gate electrode 77 is formed on the gate insulating film by silicide, MoW, or the like. Further, using the gate electrode 77 as a mask, impurity ions 78 such as P (phosphorus) in the case of an N channel transistor and B (boron) in the case of a P channel transistor are implanted. Thereafter, although not shown, annealing is performed in a nitrogen atmosphere (for example, at 450 ° C. for 1 hour) to activate the impurities and form the source region 81 and the drain region 82 in the island-shaped semiconductor film 75.

  Thereafter, as shown in FIG. 16E, for example, an interlayer insulating film 79 is formed to form a contact hole, and a source electrode 83 and a drain electrode 84 connected to a source 81 and a drain 82 connected by a channel 80 are formed. .

  Subsequently, the channel 80 is formed in accordance with the position of the large grain crystal of the polycrystalline semiconductor film or the single crystallized semiconductor film 74 generated in the steps shown in FIGS. 16A and 16B.

  Through the above process, a thin film transistor (TFT) can be formed in a polycrystalline transistor or a single crystal semiconductor.

  Note that the polycrystalline transistor or the single crystal transistor manufactured by the process shown in FIGS. 16A and 16B is a driving circuit such as a liquid crystal display device (display) or an EL (electroluminescence) display, The present invention can be applied to an integrated circuit such as a memory (SRAM or DRAM) or a CPU.

  As described above, according to the pattern exposure method of the present invention, only one mask needs to be manufactured, mask replacement is unnecessary, and as a result, it is possible to suppress an undesired decrease in throughput.

  Further, according to the exposure method in which two types of patterns are exposed in a non-interfering manner on the exposed surface using the predetermined optical system of the present invention, it is not necessary to move the mask, and the exposure is performed once. Good.

  Furthermore, by using the pattern exposure method of the present invention, the number of pattern exposure (pattern formation) steps among the steps of manufacturing a semiconductor active element, a liquid crystal display device, and the like can be reduced.

  The present invention is not limited to the above-described embodiments, and various modifications or changes can be made without departing from the scope of the invention when it is implemented. Moreover, each embodiment may be implemented in combination as appropriate as possible, and in that case, the effect of the combination can be obtained.

1 is a schematic diagram illustrating an example of an exposure apparatus to which an embodiment of the present invention can be applied. FIG. 2 is a schematic diagram illustrating the principle of the exposure apparatus shown in FIG. 1 and the characteristics of a photomask used in the exposure apparatus. Schematic explaining an example of the pattern of the photomask shown in FIG. Schematic explaining the light intensity distribution obtained by the pattern shown in FIG. Schematic explaining light intensity distribution obtained using a well-known single mask. Schematic explaining another example of the pattern of the photomask shown in FIG. Schematic explaining further another example of the pattern of the photomask shown in FIG. Schematic explaining yet another example of the pattern of the photomask shown in FIG. Schematic explaining yet another example of the pattern of the photomask shown in FIG. Schematic explaining an example of another embodiment of the exposure apparatus shown in FIG. FIG. 11 is a schematic diagram for explaining an example of a modification of the exposure apparatus shown in FIG. 10. Schematic explaining an example of the birefringent material incorporated in the exposure apparatus shown in FIG. Schematic explaining another example of a birefringent material incorporated in the exposure apparatus shown in FIG. Schematic explaining further another example of the embodiment of the exposure apparatus shown in FIG. FIG. 11 is a schematic diagram for explaining the relationship between a birefringent material and polarized light incorporated in the exposure apparatus shown in FIG. 10. Schematic which shows the process of producing an electronic device on the board | substrate by which the pattern was exposed with the exposure apparatus of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Light source, 2 ... Illumination optical system, 3 ... Photomask (phase modulation element), 4 ... Mask holder, 5,50 ... Mask holder, 6 ... Stage, 7 ... Substrate, 8 ... XY controller, 11, 111 131 ... Birefringent material, 51 ... Pupil (aperture).

Claims (18)

An exposure method in which a pattern of a photomask is imaged on an exposed surface and exposed,
Performing a first exposure using a photomask having a pattern in which at least two types of patterns are arranged in the same plane at a predetermined pitch; and
Performing a second exposure in a state where the at least two types of patterns overlap on the exposed surface by relatively moving the photomask and the exposed surface by a distance corresponding to the predetermined pitch;
An exposure method comprising: An exposure method in which a pattern of a photomask is imaged on an exposed surface and exposed,
The photomask has a pattern in which at least two types of patterns are arranged at a predetermined pitch,
An exposure method comprising exposing the two types of patterns in a non-interfering manner on the exposed surface using a predetermined optical system.   At least two types of patterns that can complement each other in shape or optical characteristics by movement at a predetermined interval in a predetermined direction are alternately arranged in a single plane at a predetermined pitch associated with the movement at a predetermined interval. A photomask. A light source;
A photomask having a pattern in which at least two kinds of patterns are arranged at a predetermined pitch, and modulating light from the light source;
An optical system that is provided between the photomask and the object to be exposed and forms an image of the pattern of the photomask on the object to be exposed;
A mask moving mechanism for exposing the second pattern of the photomask to the predetermined area of the exposure target after the first pattern of the photomask is exposed to the predetermined area of the exposure target When,
An exposure apparatus comprising: A light source;
A photomask having a pattern in which at least two kinds of patterns are arranged at a predetermined pitch, and transmitting light from the light source;
An optical system that is provided between the photomask and the object to be exposed, and forms an image of the pattern of the photomask at a predetermined position of the object to be exposed;
A multi-exposure optical element provided at a predetermined position between the photomask and the object to be exposed, and capable of irradiating the object to be exposed with the two types of patterns of the photomask superimposed in a non-interfering manner; ,
An exposure apparatus comprising:   6. The exposure apparatus according to claim 4, wherein the multiple exposure optical element is a birefringent element.   7. The exposure apparatus according to claim 6, wherein the birefringent element is a plane-parallel plate made of a birefringent material cut so that the optical axis maintains a predetermined angle from the optical axis.   3. The exposure method according to claim 2, wherein the birefringent element is a plane-parallel plate made of a birefringent material cut so that the optical axis is kept at a predetermined angle from the optical axis.   8. The exposure apparatus according to claim 7, wherein the birefringent element is at least one of a Savart plate or a birefringent prism.   The two types of patterns of the photomask include a first pattern having a first phase region and a second phase region, and a first pattern for trimming unnecessary portions of a shape generated in the case of the first pattern alone. 6. The exposure apparatus according to claim 4, wherein the exposure apparatus includes a second pattern.   The two types of patterns of the photomask connect a first pattern having a first phase region and a second phase region, and a first phase region and a second phase region of the first pattern. 6. An exposure apparatus according to claim 4, further comprising a second pattern for generating such an exposure area.   6. The two types of patterns of the photomask include first and second patterns having the same target shape and different focus ranges provided by the respective patterns. Exposure device.   6. The exposure apparatus according to claim 4, wherein a pitch of the two types of patterns of the photomask is an integral multiple of a pixel pitch of the exposure target.   A photomask that has a pattern in which at least two types of patterns are arranged at a predetermined pitch and modulates light from a light source.   The two types of patterns of the photomask include a first pattern having a first phase region and a second phase region, and a first pattern for trimming unnecessary portions of a shape generated in the case of the first pattern alone. 15. The photomask according to claim 14, further comprising: a second pattern.   The two types of patterns of the photomask connect a first pattern having a first phase region and a second phase region, and a first phase region and a second phase region of the first pattern. 15. The photomask according to claim 14, further comprising a second pattern for generating such an exposure area.   The photomask according to claim 14, wherein the two types of patterns of the photomask include first and second patterns having the same target shape and different focus ranges provided by the respective patterns. .   15. The photomask according to claim 14, wherein a pitch of the two types of patterns of the photomask is an integral multiple of a pixel pitch of the exposure target.

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