JP5145532B2 - Light irradiation apparatus, light irradiation method, crystallization apparatus, and crystallization method - Google Patents

Description

  The present invention relates to a light irradiation apparatus, a light irradiation method, a crystallization apparatus, a crystallization method, and a semiconductor device, for example, a non-single crystal semiconductor film irradiated with a laser beam having a predetermined light intensity distribution. It relates to the technology to generate.

  Conventionally, for example, a thin-film-transistor (TFT) used as a switching element for selecting a display pixel of a liquid-crystal display (LCD) is, for example, amorphous silicon or amorphous silicon. It is formed using crystalline silicon (poly-Silicon). Polycrystalline silicon has higher electron or hole mobility than amorphous silicon.

  Therefore, when the transistor is formed using polycrystalline silicon, the switching speed is faster and the response of the display is faster than when the transistor is formed using amorphous silicon. In addition, it is possible to configure the peripheral LSI with thin film transistors. Furthermore, there is an advantage that the design margin of other parts can be reduced. Further, when peripheral circuits such as a driver circuit and a DAC are incorporated in the display, the peripheral circuits can be operated at higher speed.

  Since polycrystalline silicon consists of a collection of crystal grains, for example, when a TFT transistor is formed, a crystal grain boundary is formed in the channel region, and this crystal grain boundary serves as a barrier and mobility of electrons or holes compared to single crystal silicon. Becomes lower. In addition, in many thin film transistors formed using polycrystalline silicon, the number of crystal grain boundaries formed in the channel portion is different among the respective thin film transistors. Become. Therefore, recently, in order to improve the mobility of electrons or holes and to reduce the variation in the number of crystal grain boundaries in the channel portion, a large-grained crystallized silicon having a size capable of forming at least one channel region has been developed. Producing crystallization methods have been proposed.

  Conventionally, as this type of crystallization method, an optical modulation element (phase shifter) having a phase pattern in which the ratio of the area occupied by the phase modulation region in the unit region changes one-dimensionally along a predetermined direction is used. A non-single crystal semiconductor film (polycrystalline semiconductor film or non-single crystal semiconductor film) is irradiated with laser light having a V-shaped light intensity distribution that changes one-dimensionally along a predetermined direction, and the predetermined direction is followed. A technique for generating a crystallized semiconductor film by crystal growth is proposed (see, for example, Patent Document 1 and Non-Patent Document 1).

JP 2004-343073 A Y. Taniguchi, etc., “A Novel Phase-modulator for ELA-Based Lateral Growth of Si”, The Electrochemical Society's 206th Meeting, Thin Film Transistor Technologies VII (Honolulu, Hawaii)

  In the conventional crystallization technique proposed in Patent Document 1 and Non-Patent Document 1, as shown in FIG. 22A, the ratio of the area occupied by the phase modulation region in the unit region is a predetermined direction (FIG. 22A). The light modulation element 101 having a phase pattern that changes one-dimensionally along the horizontal direction is used. The laser light modulated via the light modulation element 101 generates a V-shaped light intensity distribution that changes one-dimensionally on the image plane via the imaging optical system. Specifically, when the phase modulation amount in the phase modulation region of the light modulation element 101 is 60 degrees, a V-shaped light intensity distribution 102 indicated by a thick solid line in FIG. 22B is theoretically generated.

  Further, when the phase modulation amount in the phase modulation region of the light modulation element 101 is 180 degrees, a V-shaped light intensity distribution 103 indicated by a thick solid line in FIG. 22B is theoretically generated, and FIG. ), A V-shaped light intensity distribution 104 indicated by a thin solid line is actually generated. Thus, when a non-single crystal semiconductor film is irradiated with laser light having a V-shaped light intensity distribution, a crystal grows along the gradient direction of the light intensity distribution, and as shown in FIG. A “needle crystal” 105 extending along the line is generated.

  In the conventional crystallization technique, when the coherence factor, that is, the σ value (the exit-side numerical aperture of the illumination system / the object-side numerical aperture of the imaging optical system) is set to a relatively small value (for example, 0.5 or less), a desired value is obtained. A light intensity distribution can be generated. However, when the σ value is set to a relatively large value (for example, 0.6 or more), for example, wavy undulation occurs in the contour line indicating the light intensity, and a desired light intensity distribution cannot be generated. As a result, the crystal growth becomes uneven, and crystal grains having a desired shape cannot be generated. As a result, variations in the electrical characteristics of the manufactured TFTs occur.

  The present invention has been made in view of the above-described problems, and can generate a desired light intensity distribution even if the coherence factor is set to a relatively large value, thereby generating crystal grains having a desired shape. It is an object of the present invention to provide a crystallization apparatus and a crystallization method capable of performing the above-mentioned.

In order to solve the above-mentioned problem, according to the first aspect of the present invention, there is provided a light irradiation apparatus that irradiates an irradiated surface with light having a predetermined light intensity distribution,
A light modulation element having a light modulation pattern of a periodic structure represented by a basic translation vector (a1, a2);
An illumination system for illuminating the light modulation element with light;
An imaging optical system disposed between the light modulation element and the irradiated surface to form the predetermined light intensity distribution obtained by the light modulation pattern on the irradiated surface;
The shape of the exit pupil of the illumination system is similar to the Wigner-Sites cell of the basic reciprocal lattice vector (b1, b2) obtained from the basic translation vector (a1, a2) by the following formula. To do.
b1 = 2π (a2 × a3) / (a1 · (a2 × a3))
b2 = 2π (a3 × a1) / (a1 · (a2 × a3))
In the above equation, a3 is a vector having an arbitrary size in the normal direction of the plane of the light modulation pattern of the light modulation element, “·” represents an inner product of the vectors, and “×” represents an outer product. .

In the second embodiment of the present invention, in the light irradiation apparatus for irradiating the irradiated surface with light having a predetermined light intensity distribution,
A light modulation element having a light modulation pattern of a periodic structure represented by a basic translation vector (a1, a2);
An illumination system for illuminating the light modulation element;
An imaging optical system disposed between the light modulation element and the irradiated surface to form the predetermined light intensity distribution corresponding to the light modulation pattern on the irradiated surface;
The shape of the exit pupil of the illumination system provides a light irradiation device that is not convex with respect to the direction of the basic reciprocal lattice vector (b1, b2) obtained from the basic translation vector (a1, a2) by the following equation. .
b1 = 2π (a2 × a3) / (a1 · (a2 × a3))
b2 = 2π (a3 × a1) / (a1 · (a2 × a3))
In the above formula, a3 is a vector having an arbitrary size in the normal direction of the light modulation pattern surface of the light modulation element, “·” represents an inner product of the vectors, and “×” represents an outer product.

According to a third aspect of the present invention, there is provided a light irradiation device that irradiates an irradiated surface with light having a predetermined light intensity distribution,
A light modulation element for modulating the incident light and emitting the modulated light;
An illumination system for illuminating the light modulation element;
An imaging optical system disposed between the light modulation element and the irradiated surface to form the predetermined light intensity distribution corresponding to the modulated light on the irradiated surface;
The shape of the exit pupil of the illumination system is set to a shape other than a circular shape that allows the 0th-order diffracted light from the light modulation element to pass through and the first-order diffracted light does not substantially pass through the aperture of the pupil plane of the imaging optical system. There is provided a light irradiating device including an exit pupil shape setting unit for the purpose.

In the fourth embodiment of the present invention, a predetermined light intensity distribution is obtained by using a light modulation element that modulates incident light and an imaging optical system disposed between the light modulation element and the irradiated surface. A light irradiation method for irradiating the irradiated surface with light,
The shape of the exit pupil of the illumination system that illuminates the light modulation element is a shape other than a circular shape in which the first-order diffracted light component of the light from the light modulation element does not substantially pass through the aperture of the pupil plane of the imaging optical system A light irradiation method set to be provided.

  According to a fifth embodiment of the present invention, the light irradiation apparatus according to the first, second, or third embodiment and a stage for holding a non-single-crystal semiconductor film on the irradiated surface are provided, and the irradiated surface is disposed on the irradiated surface. A crystallized semiconductor film comprising a stage for holding a non-single crystal semiconductor film, and irradiating at least part of the non-single crystal semiconductor film held on the irradiated surface with light having the predetermined light intensity distribution A crystallization apparatus is provided.

  In the sixth embodiment of the present invention, the non-single crystal held on the irradiated surface using the light irradiation device of the first, second, or third embodiment or the light irradiation method of the fourth to sixth embodiments. There is provided a crystallization method in which at least part of a semiconductor film is irradiated with light having the predetermined light intensity distribution to form a crystallized semiconductor film.

  In a seventh embodiment of the present invention, a semiconductor device manufactured using the crystallization apparatus of the fifth embodiment is provided.

  In the present invention, the shape of the exit pupil of the illumination system is a shape other than a circular shape in which the first-order diffracted light from the light modulation element does not substantially pass through the aperture of the pupil plane of the imaging optical system (for example, Wigner-Site cell shape) Therefore, in the light intensity distribution generated on the image plane of the imaging optical system, wave-like undulations are not substantially generated in the contour lines of the light intensity. As a result, in the crystallization apparatus of the present invention, a desired light intensity distribution can be generated even when the σ value (coherence factor) is set to a relatively large value, and as a result, crystal grains having a desired shape can be generated. it can.

  Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram schematically showing a configuration of a crystallization apparatus according to an embodiment of the present invention. FIG. 2 is a diagram schematically showing the internal configuration of the illumination system of FIG. Referring to FIGS. 1 and 2, the crystallization apparatus of the present embodiment includes a light modulation element 1 such as a phase shifter for phase-modulating an incident light beam to form a light beam having a predetermined light intensity distribution, An illumination system 2 for illuminating the modulation element 1, an imaging optical system 3, and a substrate stage 5 for holding a substrate to be processed 4 are provided.

  The configuration and operation of the light modulation element 1 will be described later. The illumination system 2 includes a XeCl excimer laser light source 2a that supplies laser light having a wavelength of, for example, 308 nm. As the light source 2a, other suitable light sources having a capability of emitting energy light for melting the object to be crystallized, such as a KrF excimer laser light source and a YAG laser light source, can be used. The laser light supplied from the light source 2a is expanded through the beam expander 2b and then enters the first fly's eye lens 2c.

  Thus, a plurality of small light sources are formed on the rear focal plane of the first fly-eye lens 2c, and light beams from the plurality of small light sources are transmitted through the first condenser optical system 2d to the second fly-eye lens 2e. The incident surface is illuminated in a superimposed manner. As a result, a larger number of small light sources are formed on the rear focal plane of the second fly-eye lens 2e than on the rear focal plane of the first fly-eye lens 2c. Light beams from a plurality of small light sources formed on the rear focal plane of the second fly-eye lens 2e illuminate the light modulation element 1 in a superimposed manner via the second condenser optical system 2f.

  The first fly-eye lens 2c and the first condenser optical system 2d constitute a first homogenizer. With this first homogenizer, the laser beam emitted from the light source 2a is made uniform with respect to the incident angle on the light modulation element 1. The second fly-eye lens 2e and the second condenser optical system 2f constitute a second homogenizer. By this second homogenizer, the light intensity at each position in the plane on the light modulation element 1 is made uniform with respect to the laser light whose incident angle from the first homogenizer is made uniform.

  Thus, the illumination system 2 irradiates the light modulation element 1 with the laser light having a substantially uniform light intensity distribution. An aperture stop 2g for limiting the cross section of the light beam from the second fly eye lens 2e to a predetermined cross section is disposed near the exit surface of the second fly eye lens 2e. That is, the aperture stop 2g defines the shape of the exit pupil of the illumination system 2, and in turn functions to set the coherence factor, that is, the σ value (the exit side numerical aperture of the illumination system 2 / the object side numerical aperture of the imaging optical system 3). Have The shape of the exit pupil of the illumination system 2 means the outer shape of the light beam passing through the illumination pupil of the illumination system 2.

  The laser light that is light-modulated (phase-modulated) by the light modulation element 1 is incident on the substrate 4 to be processed via the imaging optical system 3. Here, the imaging optical system 3 optically conjugates the phase pattern surface of the light modulation element 1 and the substrate 4 to be processed. In other words, the irradiated surface of the substrate to be processed 4 is set to a surface optically conjugate with the phase pattern surface of the light modulation element 1 (image surface of the imaging optical system 3).

  The imaging optical system 3 includes a positive lens group 3a, a positive lens group 3b, and an aperture stop 3c disposed between these lens groups. The size of the aperture (light transmitting portion) of the aperture stop 3c (and consequently the image-side numerical aperture of the imaging optical system 3) has a required light intensity distribution on the semiconductor film (irradiated surface) of the substrate 4 to be processed. It is set to generate. The imaging optical system 3 may be a refractive optical system, a reflective optical system, or a refractive / reflective optical system.

Further, the substrate to be processed 4 is formed by forming a lower insulating film, a semiconductor thin film, and an upper insulating film in this order on the substrate. The substrate 4 is a substrate in which a base insulating film, a non-single crystal film such as an amorphous silicon film, and a cap film are sequentially formed on a glass plate for a liquid crystal display, for example, by chemical vapor deposition (CVD). is there. The base insulating film and the cap film are insulating films such as SiO ₂ . The base insulating film directly contacts the amorphous silicon film and the glass substrate to prevent foreign substances such as Na in the glass substrate from entering the amorphous silicon film, and the heat of the amorphous silicon film directly Prevents heat transfer to the glass substrate.

  An amorphous silicon film is a semiconductor film to be crystallized. The cap film is heated by a part of the light beam incident on the amorphous silicon film, and stores the heated temperature. This heat storage effect is that when the incidence of the light beam is interrupted, the high temperature portion of the irradiated surface of the amorphous silicon film cools relatively rapidly, but this temperature gradient is relaxed and the large grain size is reduced in the lateral direction. Promotes crystal growth. The substrate 4 to be processed is positioned and held at a predetermined position on the substrate stage 5 by a vacuum chuck or an electrostatic chuck.

  FIG. 3 is a plan view schematically showing an enlarged main part of a configuration example of the light modulation element of the crystallization apparatus shown in FIG. As shown in FIG. 3, the light modulation element 1 has unit areas (unit areas in a range indicated by reference numeral 1d) having a phase modulation pattern in which area-modulated patterns are arranged in the X direction densely arranged in the X direction. They are arranged and repeated. Each repetitive unit region 1d is composed of square unit cells 1c arranged vertically and horizontally and densely as indicated by broken lines in the figure. The unit cell 1c includes a reference phase region (indicated by a blank portion in the figure) 1a having a reference phase value of 0 degrees and a rectangular phase modulation region (indicated by a hatched portion in the figure) having a modulation phase value of 90 degrees, for example. ) 1b. This is formed, for example, in a concavo-convex pattern in quartz glass.

  The occupied area ratio (duty) D of the phase modulation region 1b with respect to the unit cell 1c varies between 0% and 50% along the X direction. Specifically, the occupied area rate D of the phase modulation region 1b at the center of the repeating unit region 1d of the phase pattern is 50%, and the occupied area rate D of the phase modulation region 1b on both sides of the repeated unit region 1d is 0%. In the meantime, the occupied area ratio D of the phase modulation region 1b changes monotonously. Here, the occupied area ratio D is the ratio of the occupied area of the phase modulation region 1b in the unit cell 1c, and the ratio of the occupied area of the reference phase region (phase modulation region whose phase modulation amount is 0 degree) 1a in the unit cell 1c. Is defined as the smaller value. The unit cell 1c has a dimension that is not greater than the point image distribution range of the imaging optical system 3 (for example, 1 μm × 1 μm in terms of the image plane of the imaging optical system 3).

The light intensity I generated on the image plane of the imaging optical system 3 by the 0th-order light transmitted through the duty modulation type light modulation element 1 is expressed by the following equation (1). In Expression (1), D is the occupied area ratio of the phase modulation region 1b in the unit cell 1c (that is, 0 to 0.5), θ is the phase modulation amount (for example, 90 degrees) of the phase modulation region 1b, and U Is the complex amplitude of light on the image plane of the imaging optical system 3.
I = | U | ² = (2-2 cos θ) D ² − (2-2 cos θ) D + 1 (1)

  In the present embodiment, the phase modulation amount θ is defined as positive when the wavefront jumps out in the light traveling direction. In addition, it is assumed that the illumination system 2 side of the light modulation element 1 is formed in a planar shape, and the imaging optical system 3 side of the light modulation element 1 is formed in an uneven shape. Referring to equation (1), it can be seen that the light intensity I generated at the corresponding position on the image plane of the imaging optical system 3 decreases as the occupation area ratio D of the phase modulation region 1b increases. In other words, a required light intensity distribution can be generated on the image plane of the imaging optical system 3 by appropriately setting the change form of the occupation area ratio D of the phase modulation region 1b.

  4A and 4B show a light modulation element similar to the light modulation element shown in FIG. 3 when the exit pupil of the illumination system is set to a circular shape and the σ value is set to 0.5. 4A and 4B are diagrams for explaining the light intensity distribution formed on the substrate to be processed, in which FIG. 4A schematically shows the light modulation element, and FIG. 4B schematically shows the light intensity distribution. FIG. In FIG. 4B, the light intensity distribution theoretically generated on the image plane of the imaging optical system 3 corresponding to one repetitive unit region 1d in the light modulation element 1 is represented by the light intensity (in the case of no modulation). Is shown in the form of contour lines). Hereinafter, also in FIG. 5B, FIG. 15, FIG. 18 and FIG. 20, the same notation as in FIG. 4B is used.

  When calculating the light intensity distribution shown in FIG. 4B, the shape of the exit pupil of the illumination system 2 (that is, the shape of the light transmission part of the aperture stop 2g) is set to a circular shape, and the wavelength of the light is set to 308 nm. The object-side numerical aperture of the image optical system 3 is set to 0.2, the exit-side numerical aperture of the illumination system 2 is set to 0.1, and the σ value is set to 0.5 (0.1 / 0.2). In the case of FIG. 4B, since the σ value is set to be relatively small, the image plane of the imaging optical system 3 moves from a position corresponding to the center of the repeating unit region 1d to a position corresponding to both ends. An almost ideal V-shaped light intensity distribution in which the light intensity I changes linearly in the X direction is generated.

  In the crystallization apparatus, in the light irradiation region on the substrate 4 to be processed, a temperature gradient is generated in the melting region in accordance with the almost ideal V-shaped light intensity distribution, and the lowest light intensity, that is, the lower end of the V shape. In the region in the vicinity thereof, crystal nuclei, that is, crystal seeds are formed in a portion that first solidifies or a portion that does not melt. Then, the crystal grows laterally from the crystal nucleus toward the periphery along the X direction that changes so that the light intensity increases in the V-shaped light intensity distribution, so that a desired shape without unevenness in crystal growth is obtained. Crystal grains are produced.

  5A and 5B show a light modulation element similar to the light modulation element shown in FIG. 3 when the exit pupil of the illumination system is set to a circular shape and the σ value is set to 0.6. 5A and 5B are diagrams for explaining the light intensity distribution formed on the substrate to be processed, in which FIG. 5A schematically shows the light modulation element, and FIG. 5B schematically shows the light intensity distribution. FIG. In the calculation of the light intensity distribution shown in FIG. 5B, as in the case of FIG. 4B, the exit pupil of the illumination system 2 is set to a circular shape, the wavelength of light is set to 308 nm, and the imaging optical system 3 is set to 0.2. However, unlike the case of FIG. 4B, in order to set the σ value to 0.6, the exit-side numerical aperture of the illumination system 2 is set to 0.12. Hereinafter, in the present embodiment, the light wavelength is 308 nm and the object-side numerical aperture of the imaging optical system 3 is 0.2.

  In the case of FIG. 5B, a V-shaped light intensity distribution is generated in a region on the image plane of the imaging optical system 3 corresponding to the center of the repeating unit region 1d, but the σ value is set to be relatively large. Therefore, wave-like undulation occurs in the contour lines of light intensity. In particular, a relatively large wave-like undulation appears in a contour line having a light intensity of 0.7 and in some contour lines having a light intensity of 0.8. It has been recognized that this wavy undulation increases as the σ value increases. If such wave-like undulations occur in the contour lines of light intensity in the V-shaped light intensity distribution, the crystal growth is uneven due to the wave-like undulations, and as a result, crystal grains having a desired shape can be generated. Can not.

  That is, in the wavy contour line, the temperature is lower in the concave bottom part toward the contour line having the light intensity of 0.5, and the crystal part grows in the lower temperature part before the peripheral part with the higher temperature. As a result, a crystal grain that is thicker than the original is formed in the low temperature portion, and as a result, a thick crystal grain and a thin crystal grain are mixedly generated as a whole. When a TFT is manufactured in a region where thick crystal grains and thin crystal grains are mixed, variations in electrical characteristics occur.

  As described above, when the exit pupil of the illumination system 2 is circular, if the σ value is set to a relatively large value (for example, 0.6 or more), a desired light intensity distribution cannot be generated. On the other hand, in the crystallization apparatus, it is preferable to set the σ value as large as possible. This is because the fly-eye lens 2e in the illumination system 2 is configured by arranging minute lens elements vertically and horizontally and densely. If the cross-sectional sizes of the minute lens elements are the same, it is better to set the σ value larger. Since light that has passed through a larger number of microlens elements can be used, and a secondary light source is configured by a larger number of small light sources, the uniformity of the light intensity distribution of the illumination light to the light modulation element 1 is increased. It is.

  In other words, when the number of small light sources constituting the secondary light source is the same, the fly-eye lens 2e can be configured using larger microlens elements by setting a larger σ value. The eye lens 2e can be easily manufactured. Further, focusing attention on the optical systems 2b to 2d that guide the light from the light source 2a to the fly-eye lens 2e, the light incident efficiency to the fly-eye lens 2e becomes larger when the σ value is set larger, so that the light use efficiency is improved. (Condensing light over a wide area can more effectively guide light than condensing it over a narrow area).

  Hereinafter, referring to FIG. 6, an object having a periodic structure (corresponding to the light modulation element 1 in FIG. 1) O is generated on the pupil plane P of the imaging optical system (corresponding to the imaging optical system 3 in FIG. 1). The light distribution will be described. When the complex amplitude transmittance of the object O such as the duty modulation type light modulation element 1 is f (r), the complex amplitude transmittance f (r) is also a periodic function, and therefore, the Fourier transform represented by the following equation (2): Are in a relationship.

In Expression (2), r is an in-plane coordinate vector of the object O, and q is called a phase gradient vector. e ^iqr represents a component in which the phase component of the transmittance (that is, the amount of phase modulation) changes linearly in the plane of the object O, and e ^iqr is called a phase gradient. g (q) is a coefficient of the phase gradient e ^iqr . Here, considering the contribution of the phase gradient vector q when a plane wave having a wave number vector of k1 is incident on the object O, the phase gradient is added to this plane wave, and a new plane wave whose direction is changed is generated.

At this time, in order to add a phase gradient to the plane wave and generate a new plane wave, the phase gradient must be equal between adjacent unit cells. This is because, when the phase gradients are not equal between adjacent unit cells, the phase is advanced or delayed, and a plane wave is not generated. The condition that the phase gradients are equal between adjacent unit cells is to satisfy the following equation (3) and to satisfy the following equation (4), where R is the basic translation vector (there are multiple). .
g (q) e ^iqr = g (q) e ^{iq (r + R)} (3)
g (q) = g (q) e ^iqR (4)

In order for g (q) to have a solution other than 0, e ^iqR = 1 needs to be satisfied for all Rs, and thus the relationship shown in the following equation (5) needs to be satisfied. The phase gradient vector q satisfying the equation (5) is a basic reciprocal lattice vector (a plurality of basic translation vectors R) of the basic translation vector R.
qR = 2nπ (n is an integer) (5)

Next, consider the direction of a plane wave generated by one phase gradient vector q. The light distribution I ₁ (r) generated immediately before the object O by the plane wave having the wave vector k1 is expressed by the following equation (6). The light distribution I ₂ (r) generated immediately after the object O is obtained by ^multiplying the light distribution I ₁ (r) by the phase gradient e ^iqr and is expressed by the following equation (7).
I ₁ (r) = e ^ik1r (6)
I ₂ (r) = I ₁ (r) e ^iqr = e ^{i (k1 + q) r} (7)

Therefore, it can be seen that the direction cosine vector (in the plane of the object O) of the wave number vector of the wavefront generated by the light distribution I ₂ (r) is k1xy + q. However, k1xy is a direction cosine vector of k1. The direction cosine vector k2xy of the wave vector k2 representing the newly generated wavefront is expressed by the following equation (8).
k2xy = k1xy + q (8)

  From this, the light intensity distribution on the pupil plane P of the imaging optical system is based on the basic translation vector of the periodic structure of the object O like the duty modulation type light modulation element 1 and the shape of the exit pupil of the illumination system. You can see that it is decided. That is, the light intensity distribution on the pupil plane P of the imaging optical system 3 in the present embodiment is at the lattice point determined by the reciprocal lattice of the basic translation vector of the periodic structure of the duty modulation type light modulation element 1. The distribution is obtained by overlapping the shapes of the two exit pupils. This is shown in FIGS.

  That is, in FIG. 7, in the case of coherent illumination, the light intensity distribution on the pupil plane P of the imaging optical system 3 is determined by the basic reciprocal lattice vectors q1 and q2 of the basic translation vector R of the periodic structure of the light modulation element 1. It shows that it becomes a lattice structure. FIG. 8 shows the shape of the exit pupil of the illumination system 2 (in this case, the lattice point in FIG. 7 as a result of the integration of the light intensity distribution on the pupil plane P of the imaging optical system 3 in the case of partial coherent illumination. (Circular shape). The points shown in FIGS. 7 and 8 will be described below based on specific examples.

FIG. 9 schematically shows the calculation result of the light intensity distribution obtained on the pupil plane of the imaging optical system using the light modulation element of FIG. 3 under the condition of FIG. 4B (σ value = 0.5). FIG. FIG. 10 schematically shows the calculation result of the light intensity distribution obtained on the pupil plane of the imaging optical system using the light modulation element of FIG. 3 under the condition of FIG. 5B (σ value = 0.6). FIG. First, when the x axis and the y axis (corresponding to the X axis and the Y axis in FIG. 3) are set in the plane of the duty modulation type light modulation element 1, and the optical axis of the imaging optical system 3 is the z axis, The basic translation vectors a1 and a2 of the periodic structure of the modulation element 1 are represented by the following expressions (9a) and (9b), respectively.
a1 = (1.0, 0.0, 0.0) μm (9a)
a2 = (0.0, 1.0, 0.0) μm (9b)

Basic reciprocal lattice vectors b1 and b2 obtained from basic translation vectors a1 and a2 are defined by the following equations (10a) and (10b), respectively. At this time, as a3, a vector having an arbitrary size parallel to the z-axis, for example, (0, 0, 1) may be used. In Expressions (10a) and (10b), “×” represents an outer product of vectors, and “·” represents an inner product of vectors.
b1 = 2π (a2 × a3) / (a1 · (a2 × a3)) (10a)
b2 = 2π (a3 × a1) / (a1 · (a2 × a3)) (10b)

Substituting the basic translation vectors a1 and a2 represented by the equations (9a) and (9b) into the equations (10a) and (10b), the basic reciprocal lattice vectors b1 and b2 are expressed by the following equations (11a) And the formula (11b).
b1 = 2π (1.0, 0.0, 0.0) μm ⁻¹ (11a)
b2 = 2π (0.0, 1.0, 0.0) μm ⁻¹ (11b)

Dividing these basic reciprocal lattice vectors b1 and b2 by the wave number k (= 2π / λ; λ is the wavelength of light), and extracting the x component and the y component, the vectors b1 ′ and b2 ′ are the imaging optical system 3 The lattice structure on the pupil plane is determined. Since λ = 0.308 μm, the vectors b1 ′ and b2 ′ are expressed by the following equations (12a) and (12b), respectively. However, in the formulas (12a) and (12b), “x” represents an ordinary multiplication, not an outer product of vectors.
b1 ′ = (1 / k) × b1 = (0.0,308,0.0) (11a)
b2 ′ = (1 / k) × b2 = (0.0, 0.0, 308) (11b)

  Further, in the case of partial coherent illumination, the light distribution pattern on the pupil plane of the imaging optical system 3 has a structure in which the shape of the exit pupil of the illumination system 2 is overlapped around each lattice point. In the light intensity distributions of FIGS. 9 and 10, the central light beams 9 a and 10 a centering on the optical axis AX correspond to the zero-order light from the light modulation element 1, and the eight peripheral light beams surrounding the central light beams 9 a and 10 a Light beams 9ba, 9bb and 10ba, 10bb correspond to the first-order diffracted light from the light modulation element 1. In some cases, a peripheral light beam due to the second-order diffracted light may further be generated outside the peripheral light beams 9ba, 9bb and 10ba, 10bb due to the first-order diffracted light.

  Specifically, in the light intensity distribution of FIG. 9, the radius of the hatched circular portion 9aa of the central light beam 9a is 0. 0 corresponding to the exit side numerical aperture of the illumination system 2 under the conditions of FIG. 1. Of the eight peripheral luminous fluxes 9ba and 9bb, the radius of the four circular peripheral luminous fluxes 9ba on the upper and lower sides and the left and right of the central luminous flux 9a in the drawing is 0.1 as well as the circular portion 9aa of the central luminous flux 9a. The other four circular peripheral luminous fluxes 9bb have radii smaller than the radius 0.1 of the circular portion 9aa of the central luminous flux 9a.

  On the other hand, in the light intensity distribution of FIG. 10, the radius of the hatched circular portion 10aa of the central light beam 10a is 0.12 corresponding to the exit side numerical aperture of the illumination system 2 under the conditions of FIG. is there. Of the eight peripheral light beams 10ba and 10bb, the radius of the four circular peripheral light beams 10ba at the top and bottom and the left and right of the central light beam 10a in the drawing is also 0.12, similar to the circular portion 10aa of the central light beam 10a. The radius of the other four circular peripheral luminous fluxes 10bb has a radius smaller than the radius 0.12 of the circular portion 10aa of the central luminous flux 10a.

  The distance between the center of the circular portion 9aa (10aa) of the central light beam 9a (10a) and the center of the left and right peripheral light beams 9ba (10ba) in the figure is the x-direction component of the vector b1 ′ corresponding to the basic reciprocal lattice vector b1. Correspondingly, it is 0.308. The distance between the center of the circular portion 9aa (10aa) of the central light beam 9a (10a) and the center of the upper and lower peripheral light beams 9ba (10ba) in the figure is the y-direction component of the vector b2 ′ corresponding to the basic reciprocal lattice vector b2. Correspondingly, it is 0.308. The light intensity of the circular portion 9aa (10aa) of the central light beam 9a (10a) (the light intensity when the unmodulated intensity is normalized to 1; the same applies hereinafter) is 0.7 to 0.8. The light intensity of the peripheral portion 9ab (10ab) of 9a (10a) and the peripheral light beams 9ba (10ba) and 9bb (10bb) is 0.1 to 0.2. Circles 9c and 10c indicated by broken lines in FIGS. 9 and 10 are apertures of the imaging optical system 3 represented by circles centered on the optical axis, and correspond to the object-side numerical aperture of the imaging optical system 3. It has a radius of 0.2.

  Referring to the calculation results (simulation results) in FIGS. 9 and 10, the peripheral portions 9ab and 10ab are represented around the circular portions 9aa and 10aa of the central light beams 9a and 10a corresponding to the zero-order light from the light modulation element 1. There is a blur of weak light. The weak light blurs 9ab and 10ab are modulation components due to a change in the occupation area ratio (duty ratio) D in the duty modulation type light modulation element 1. Since this modulation component realizes an intensity gradient, it is necessary to determine the object-side numerical aperture of the imaging optical system 3 so that this light is taken into the apertures 9c and 10c (in the pupil) of the imaging optical system 3. .

  Next, the cause of the occurrence of wavy undulations in the contour lines of the light intensity in the V-shaped light intensity distribution shown in FIG. 5B will be described. FIG. 9 showing the calculation result of the light intensity distribution obtained on the pupil plane of the imaging optical system 3 under the condition of FIG. 4B (σ value = 0.5) shows the first-order diffracted light from the light modulation element 1. All of the peripheral luminous fluxes 9ba and 9bb corresponding to are outside the aperture 9c of the imaging optical system 3 and are not taken into the pupil of the imaging optical system 3. On the other hand, in FIG. 10 showing the calculation result of the light intensity distribution obtained on the pupil plane of the imaging optical system 3 under the condition (σ value = 0.6) in FIG. Part of the peripheral light beams 10ba and 10bb corresponding to the first-order diffracted light passes through the inside of the aperture 10c of the imaging optical system 3 and is taken into the pupil of the imaging optical system 3. The first-order diffracted light component captured in the pupil of the imaging optical system 3 is pattern information of the phase modulation area on the light modulation element 1. For this reason, in the light intensity distribution on the image plane shown in FIG. 5B, a pattern of the light modulation region on the light modulation element 1 appears, and this becomes a wave-like undulation in the contour line of the light intensity.

  From the above, while maintaining the area of the exit pupil of the illumination system 2 to a required size, the shape of the exit pupil is changed from a circular shape to another appropriate shape, and the primary diffracted light from the light modulation element 1 is converted. If a part of the corresponding light flux does not pass through the aperture of the imaging optical system 3 (does not overlap with the aperture), for example, a wavy wave in the contour line of the light intensity is maintained while maintaining a σ value of 0.6 or more. Occurrence can be substantially avoided. That is, the shape of the exit pupil of the illumination system 2 that illuminates the light modulation element 1 is a shape other than the circular shape in which the first-order diffracted light from the light modulation element 1 does not substantially pass through the aperture of the pupil plane of the imaging optical system 3. If this is set, it is possible to substantially avoid the occurrence of wavy undulations in the contour lines of the light intensity while maintaining a relatively large σ value. If the area of the exit pupil of the illumination system 2 is not changed, the effect of making the light intensity of the incident light beam to the light modulation element 1 uniform is not changed. In this way, the inventor pays attention to the relationship between the periodic structure of the duty modulation type light modulation element and the shape of the exit pupil of the illumination system, and optimizes the shape of the exit pupil of the illumination system according to the periodic structure of the light modulation element. As a result, it has been conceived that a desired light intensity distribution without wavy undulation can be obtained even when a relatively large σ value is set.

  One solution that satisfies the condition that a part of the light beam corresponding to the first-order diffracted light from the light modulation element 1 does not overlap the aperture of the imaging optical system 3 is to change the shape of the exit pupil of the illumination system 2 to the basic reciprocal lattice vector. Do not make it convex in the direction of (b1, b2). That is, in order to satisfy the condition that a part of the light beam corresponding to the first-order diffracted light from the light modulation element 1 does not overlap with the aperture of the imaging optical system 3, the shape of the exit pupil of the illumination system 2 is the basic translation vector ( It is important that the shape is not convex with respect to the direction of the basic reciprocal lattice vector (b1, b2) obtained from a1, a2). The shape according to this specific solution is the Wigner-Site cell shape of the basic reciprocal lattice vector (b1, b2). Hereinafter, with reference to FIG. 11, a method for generating a Wigner site cell will be described. FIG. 11 shows a general example in which the basic translation vectors a1 and a2 are not orthogonal to each other.

  In order to generate a Wigner-Site cell, first, a straight line segment 11a connecting adjacent lattice points (indicated by black circles in the figure) is drawn. Next, a new straight line 11b passing through the midpoint of each line segment 11a and perpendicular to the line segment 11a is drawn. A Wigner site cell 11c is obtained as a minimum area portion surrounded by the straight line 11b. For details of Wigner Sites Cell, refer to Kittel, “Introduction to Solid State Physics (above)”, 7th edition, Maruzen Publishing, p8.

  FIGS. 12A and 12B show the effects obtained when the shape of the exit pupil of the illumination system is changed to the Wigner-Site cell shape (similar to the Wigner-Sites cell). In FIG. 12A, since the shape of the exit pupil of the illumination system 2 is set to be circular according to the prior art, a part of the circular peripheral luminous flux 12a corresponding to the first-order diffracted light from the light modulation element 1 is used. Is taken into the pupil of the imaging optical system 3 through the inside of the aperture (shown by a broken line) 12c of the imaging optical system 3. On the other hand, in FIG. 12B, since the shape of the exit pupil of the illumination system 2 is set to be similar to the Wigner-Sites cell according to the present invention, it corresponds to the first-order diffracted light from the light modulation element 1. All of the Wigner-Site-cell-shaped (specifically, parallelogram-shaped) peripheral luminous flux 12b is outside the aperture 12c (shown by a broken line in the drawing) 12c of the imaging optical system 3. It is not captured in the pupil.

  That is, in the example shown in FIG. 12B, the outer shape of the peripheral light beam (first-order diffracted light region) 12b of the Wigner-Site cell shape is flat at the portion facing the circular opening 12c of the imaging optical system 3. Unlike the case of the circular peripheral light beam 12a, it does not protrude convexly toward the circular opening 12c of the imaging optical system 3. In this way, the circular peripheral light beam 12a (FIG. 12A) and the Wigner-Sites cell peripheral light beam 12b have the same area, but a part of the circular peripheral light beam 12a is part of the imaging optical system 3. In contrast to being taken into the pupil, the Wigner-Site-cell peripheral light beam 12b (FIG. 12B) is not taken into the pupil of the imaging optical system 3 at all.

  Therefore, in the present embodiment, even if the σ value is set to be as large as 0.6, for example, a part of the light beam corresponding to the first-order diffracted light from the light modulation element 1 does not pass through the aperture of the imaging optical system 3. The shape of the exit pupil of the illumination system 2 was set to the Wigner-Sites cell shape. In this embodiment, since the basic reciprocal lattice vectors b1 and b2 of the light modulation element 1 are orthogonal to each other and have the same size, the shape of the exit pupil of the illumination system 2 is set to the Wigner-Site cell shape. Is nothing but setting the shape of the exit pupil of the illumination system 2 to a square shape.

  In this embodiment, in order to set the shape of the exit pupil of the illumination system 2 to a square shape, as shown in FIG. 13, it is arranged near the exit surface of the second fly-eye lens 2e (not shown in FIG. 13). The shape of the aperture (light transmitting portion) 2ga of the aperture stop 2g (not shown in FIG. 13) was set to a square shape instead of a normal circular shape. In FIG. 13, a rectangular cross section 2ea of each microlens element constituting the second fly's eye lens 2e is indicated by a broken line.

  The shape and size of the rectangular cross section 2ea of each microlens element constituting the second fly's eye lens 2e do not have to be the same, and the shape is not limited to a square, For example, it may be a triangle or a polygon. As a result, the shape of the aperture (light transmitting portion) 2ga of the aperture stop 2g also allows the 0th-order diffracted light from the light modulation element to pass, and the first-order diffracted light substantially passes through the aperture of the pupil plane of the imaging optical system. Any shape other than the circular shape that is not performed may be used, and for example, it may be a triangle or a polygon.

  When the shape of the exit pupil of the illumination system 2 is circular, in order to ensure a σ value of 0.6, it is necessary to set the exit-side numerical aperture of the illumination system 2 to 0.12. At this time, the circular area of the exit pupil of the illumination system 2 is Sc = 0.045 (= 3.14 × 0.12 × 0.12). Then, if the shape of the exit pupil is set to the Wigner-Sites cell shape so as to keep the exit pupil area of the illumination system 2, that is, 0.214 × 0.214 (= 0.045) in this embodiment. If it is set to a square shape, an exit pupil area corresponding to a σ value of 0.6 can be secured. Here, σ value equivalent to 0.6 means having the same exit pupil area as a circular exit pupil having a σ value of 0.6.

  FIG. 14 shows the pupil plane of the imaging optical system using the light modulation element of FIG. 3 when the shape of the exit pupil of the illumination system is set to the Wigner-Site cell shape and the σ value is set to be equivalent to 0.6. It is a figure which shows roughly the calculation result of the light intensity distribution obtained by (3). In the light intensity distribution of FIG. 14, the central light beam 14a centered on the optical axis AX corresponds to the zero-order light from the light modulation element 1, and the eight peripheral light beams 14ba and 14bb surrounding the central light beam 14a are optically modulated. This corresponds to the first-order diffracted light from the element 1. The length of one side of the hatched square portion 14aa of the central light beam 14a is 0.214 corresponding to the above-described 0.214 × 0.214 square exit pupil. Of the eight peripheral luminous fluxes 14ba and 14bb, the length of one side of the four square peripheral luminous fluxes 14ba at the top and bottom and the left and right of the central luminous flux 14a in the drawing is 0.214, similarly to the square portion 14aa of the central luminous flux 14a. . The length of one side of the other four square-shaped peripheral light beams 14bb is smaller than the square portion 14aa of the central light beam 14a.

  The distance between the center of the square portion 14aa of the central light beam 14a and the center of the left and right peripheral light beams 14ba in the figure is 0.308 corresponding to the x-direction component of the vector b1 'corresponding to the basic reciprocal lattice vector b1. The distance between the center of the square portion 14aa of the central light beam 14a and the center of the upper and lower peripheral light beams 14ba in the figure is 0.308 corresponding to the y-direction component of the vector b2 'corresponding to the basic reciprocal lattice vector b2. The light intensity of the square portion 14aa of the central light beam 14a is 0.7 to 0.8, and the light intensity of the peripheral portion 14ab and the peripheral light beams 14ba and 14bb of the central light beam 14a is 0.1 to 0.2. A circle 14c indicated by a broken line in FIG. 14 is an aperture of the imaging optical system 3 represented by a circle centered on the optical axis, and has a radius of 0.2 corresponding to the object-side numerical aperture of the imaging optical system 3. Have

  Referring to the calculation result (simulation result) in FIG. 14, a weak light blur represented as a peripheral portion 14 ab is observed around the square portion 14 aa of the central light beam 14 a corresponding to the zero-order light from the light modulation element 1. It is done. As described above, the weak light bleed portion 14ab is a modulation component due to a change in the occupied area ratio (duty ratio) D in the duty modulation type light modulation element 1, and this light is reflected in the imaging optical system 3. The object-side numerical aperture of the imaging optical system 3 is determined so as to be taken into the opening 14c.

  FIGS. 15A and 15B show the light modulation element shown in FIG. 3 when the shape of the exit pupil of the illumination system is set to the Wigner-Site cell shape and the σ value is set to be equivalent to 0.6. FIG. 15A is a diagram for explaining a light intensity distribution formed on a substrate to be processed using the same light modulation element as FIG. 15A, FIG. 15A shows a light modulation element, and FIG. It is a figure which shows light intensity distribution roughly, respectively. In the present embodiment, as described above, since the shape of the exit pupil of the illumination system 2 is set to a square as a Wigner-Site cell shape, a relatively large σ value of 0.6 is secured. Nevertheless, a part of the light beam corresponding to the first-order diffracted light from the light modulation element 1 does not pass through the aperture of the imaging optical system 3.

  Therefore, as shown in FIG. 15B, the image plane of the imaging optical system 3 is arranged in the X direction from a position corresponding to the center of the repeating unit region 1d of the light modulation element 1 to a position corresponding to both ends. A substantially ideal V-shaped light intensity distribution in which the light intensity changes linearly is generated, and the occurrence of wavy undulations in the contour lines of the light intensity is substantially avoided. In the light intensity distribution of FIG. 15 (b), wave-like undulations appear in the contour line where the light intensity is 0.8, but it can be seen that it is much smaller than the wave-like undulations shown in FIG. 5 (b). . As a result, in the crystallization apparatus of the present embodiment, a desired light intensity distribution can be generated even when the σ value (coherence factor) is set to a relatively large value, and thus a crystal grain having a desired shape can be generated. Can do.

  In the light modulation element 1 used in the above-described embodiment, the arrangement direction of the repeating unit region 1d of the phase pattern coincides with the change direction of the occupation area ratio D of the phase modulation region 1b with respect to the unit cell 1c. Hereinafter, a description will be given of a modification using the light modulation element 1A having a configuration in which the arrangement direction of the phase pattern repetition unit region and the change direction of the occupation area ratio D of the phase modulation region with respect to the unit cell form 45 degrees.

  FIG. 16 is a diagram schematically illustrating a configuration of a light modulation element according to a modification. The light modulation element 1A of the modification shown in FIG. 16 is configured by repeating unit areas (unit areas in a range indicated by reference numeral 1Ad) of phase patterns arranged in the X direction. Each repeating unit region 1Ad is two-dimensionally and densely arranged along a direction forming 45 degrees with respect to the X-axis and the Y-axis (hereinafter referred to as “45-degree oblique direction”), as indicated by broken lines in the figure. The unit cell 1Ac has a square shape.

  The unit cell 1Ac includes a reference phase region (indicated by a blank portion in the drawing) 1Aa having a reference phase value of 0 degrees and a rectangular phase modulation region (indicated by a hatched portion in the drawing) having a modulation phase value of 90 degrees, for example. ) 1 Ab. The occupied area ratio D of the phase modulation region 1Ab with respect to the unit cell 1Ac varies between 0% and 50% along the 45 ° oblique direction. Specifically, the occupied area rate D of the phase modulation region 1Ab at the center of the repeating unit region 1Ad of the phase pattern is 50%, and the occupied area rate D of the phase modulation region 1Ab on both sides of the repeated unit region 1Ad is 0%. In the meantime, the occupied area ratio D of the phase modulation region 1Ab changes monotonously along a 45 ° oblique direction.

  FIG. 17 shows the light intensity obtained on the pupil plane of the imaging optical system using the light modulation element of FIG. 16 when the shape of the exit pupil of the illumination system is set to a circular shape and the σ value is set to 0.6. It is a figure which shows the calculation result of distribution roughly. In the light intensity distribution of FIG. 17, the central light beam 17a centered on the optical axis AX corresponds to the zero-order light from the imaging optical system that has passed through the light modulation element 1A, and eight peripheral light beams surrounding the central light beam 17a. Corresponds to the first-order diffracted light from the imaging optical system. The radius of the hatched circular portion 17aa of the central light beam 17a is 0.12 corresponding to the exit side numerical aperture of the illumination system 2. Of the eight peripheral light fluxes, the radius of the four circular peripheral light fluxes 17b positioned at an angle of 45 degrees with respect to the central light flux 17a is also 0.12, similar to the circular portion 17aa of the central light flux 17a.

  The distance between the center of the circular portion 17aa of the central light beam 17a and the center of the peripheral light beam 17b is 0.308 corresponding to the direction component of the basic reciprocal lattice vector of the light modulation element 1A, as in the above-described embodiment. is there. The light intensity of the circular portion 17aa of the central light beam 17a (the light intensity when the unmodulated intensity is normalized to 1; the same applies hereinafter) is 0.7 to 0.8, and the peripheral portion 17ab of the central light beam 17a and The light intensity of the peripheral light beam 17b is 0.1 to 0.2. A circle 17c indicated by a broken line in FIG. 17 is an aperture of the imaging optical system 3 represented by a circle centered on the optical axis, and has a radius of 0.2 corresponding to the object-side numerical aperture of the imaging optical system 3. Have Referring to FIG. 17, a part of the peripheral light beam 17 b corresponding to the first-order diffracted light from the light modulation element 1 </ b> A passes through the inside of the opening 17 c of the imaging optical system 3 and is taken into the pupil of the imaging optical system 3. ing.

  18 shows the light intensity distribution formed on the substrate to be processed using the light modulation element of FIG. 16 when the shape of the exit pupil of the illumination system is set to a circular shape and the σ value is set to 0.6. It is a figure shown roughly. Referring to FIG. 18, a V-shaped light intensity distribution is generated in a region on the image plane of the imaging optical system 3 corresponding to the repetitive unit region 1Ad of the light modulation element 1A. Since a part of the peripheral light beam 17b corresponding to the first-order diffracted light is taken into the opening 17c of the imaging optical system 3, a wave-like undulation occurs in the contour line of the light intensity. In particular, relatively large wave-like undulations appear in the contour line having a light intensity of 0.7, the contour line of 0.8, and the contour line of 0.9.

  FIG. 19 shows the pupil plane of the imaging optical system using the light modulation element of FIG. 16 when the shape of the exit pupil of the illumination system is set to the Wigner-Site cell shape and the σ value is set to be equivalent to 0.6. It is a figure which shows roughly the calculation result of the light intensity distribution obtained by (3). In the modification using the light modulation element 1A of FIG. 16 as well, the basic reciprocal lattice vectors of the light modulation element 1A are orthogonal to each other and have the same magnitude as in the case of the above-described embodiment. Setting the shape of the exit pupil to the Wigner-Site cell shape is nothing but setting the shape of the exit pupil of the illumination system 2 to a square shape.

  In the light intensity distribution of FIG. 19, the central light beam 19a centered on the optical axis AX corresponds to the zero-order light from the light modulation element 1A, and the eight peripheral light beams surrounding the central light beam 19a are from the light modulation element 1A. Corresponds to first-order diffracted light. The length of one side of the hatched square portion 19aa in the central light beam 19a is 0.214 corresponding to the above-described square exit pupil of 0.214 × 0.214. Of the eight peripheral light beams, the length of one side of the four square peripheral light beams 19b positioned obliquely to the central light beam 19a by 45 degrees is 0.214, similar to the square portion 19aa of the central light beam 19a.

  Further, the distance between the center of the square portion 19aa of the central light beam 19a and the center of the peripheral light beam 19b is 0. 0 corresponding to the direction component of the basic reciprocal lattice vector of the light modulation element 1A, as in the above-described embodiment. 308. The light intensity of the square portion 19aa of the central light beam 19a is 0.7 to 0.8, and the light intensity of the peripheral portion 19ab and the peripheral light beam 19b of the central light beam 19a is 0.1 to 0.2. A circle 19c indicated by a broken line in FIG. 19 is an aperture of the imaging optical system 3 represented by a circle centered on the optical axis, and has a radius of 0.2 corresponding to the object-side numerical aperture of the imaging optical system 3. Have Referring to FIG. 19, all of the central light beam 19a corresponding to the zero-order light from the light modulation element 1A is taken into the opening 19c of the imaging optical system 3, but corresponds to the first-order diffracted light from the light modulation element 1A. It can be seen that the peripheral light beam 19b is not taken into the opening 19c of the imaging optical system 3 at all.

  20 is formed on the substrate to be processed using the light modulation element of FIG. 16 when the shape of the exit pupil of the illumination system is set to the Wigner-Site cell shape and the σ value is set to 0.6 or equivalent. It is a figure which shows roughly the light intensity distribution. Referring to FIG. 20, the peripheral light beam 19b corresponding to the first-order diffracted light from the light modulation element 1A is not taken into the aperture 19c of the imaging optical system 3 at all. A substantially ideal V-shaped light intensity distribution is generated in which the light intensity linearly changes in the X direction from the position corresponding to the center of the unit region 1Ad toward the positions corresponding to both ends. In the light intensity distribution of FIG. 20, a wave-like undulation appears in a contour line with a light intensity of 0.9, but it can be seen that it is much smaller than the wave-like undulation shown in FIG.

21A to 21E are process cross-sectional views showing a process of manufacturing an electronic device in a region crystallized using the crystallization apparatus of this embodiment. As shown in FIG. 21A, a base film 81 (for example, SiN having a film thickness of 50 nm is formed on a transparent insulating substrate 80 (for example, formed of alkali glass, quartz glass, plastic, polyimide, or the like). A film such as a laminated film of SiO ₂ with a thickness of 100 nm) and an amorphous semiconductor film 82 (for example, a film of a semiconductor such as Si, Ge, SiGe with a thickness of about 50 nm to 200 nm) and a cap film 82a (not shown). For example, the substrate 5 to be processed is prepared by forming a 30 nm to 300 nm thick SiO ₂ film or the like by using a chemical vapor deposition method or a sputtering method. Then, a laser beam 83 (for example, a KrF excimer laser beam or a XeCl excimer laser beam) is irradiated onto a predetermined region on the surface of the amorphous semiconductor film 82 using the crystallization apparatus according to the present embodiment. .

Thus, as shown in FIG. 21B, a polycrystalline semiconductor film or a single crystallized semiconductor film 84 having a crystal with a large grain size is formed in the amorphous semiconductor film 82. Next, after the cap film 82a is removed from the semiconductor film 84 by etching, as shown in FIG. 21C, a polycrystalline semiconductor film or a single crystallized semiconductor film 84 is formed using a photolithography technique, for example, a thin film transistor. An island-shaped semiconductor film 85 to be a region for processing is processed, and a SiO ₂ film having a thickness of 20 nm to 100 nm is formed as a gate insulating film 86 on the surface by chemical vapor deposition or sputtering. Further, as shown in FIG. 21D, a gate electrode 87 (eg, silicide, MoW, etc.) is formed on a part of the gate insulating film, and impurity ions 88 (N channel transistor) are formed using the gate electrode 87 as a mask. In the case of phosphorus, boron in the case of a P-channel transistor is ion-implanted into the semiconductor film 85. After that, annealing is performed in a nitrogen atmosphere (for example, at 450 ° C. for 1 hour) to activate the impurities and form the source region 91 and the drain region 92 on both sides of the channel region 90 in the island-shaped semiconductor film 85. . Next, as shown in FIG. 21E, an interlayer insulating film 89 covering the whole is formed, contact holes are made in the interlayer insulating film 89 and the gate insulating film 86, and the source region 91 and the drain region 92 are formed. A source electrode 93 and a drain electrode 94 to be connected to each other are formed.

  In the above process, the gate electrode 87 is formed in accordance with the position in the planar direction of the large grain crystal of the polycrystalline semiconductor film or the single crystallized semiconductor film 84 generated in the process shown in FIGS. By forming, the channel 90 is formed under the gate electrode 87. Through the above steps, a thin film transistor (TFT) can be formed in a polycrystalline transistor or a single crystal semiconductor. Polycrystalline transistors or single crystal transistors thus manufactured can be applied to driving circuits such as liquid crystal display devices (displays) and EL (electroluminescence) displays, and integrated circuits such as memories (SRAM and DRAM) and CPUs. is there.

  In the above description, the present invention is applied to a crystallization apparatus and a crystallization method in which a non-single crystal semiconductor film is irradiated with light having a predetermined light intensity distribution to generate a crystallized semiconductor film. However, the present invention is not limited to this, and the present invention is generally applicable to a light irradiation apparatus that forms a predetermined light intensity distribution on a predetermined surface via an imaging optical system.

It is a figure which shows roughly the structure of the crystallization apparatus concerning one Embodiment of this invention. It is a figure which shows schematically the internal structure of the illumination system of the crystallization apparatus of FIG. It is a figure which shows roughly the structure of a part of light modulation element of the crystallization apparatus shown in FIG. Light intensity distribution formed on the substrate to be processed using a light modulation element similar to the light modulation element shown in FIG. 3 when the exit pupil of the illumination system is set to a circular shape and the σ value is set to 0.5 4A is a diagram schematically illustrating the light modulation element, and FIG. 4B is a diagram schematically illustrating the light intensity distribution. Light intensity distribution formed on the substrate to be processed using a light modulation element similar to the light modulation element shown in FIG. 3 when the exit pupil of the illumination system is set to a circular shape and the σ value is set to 0.6 FIG. 5A is a diagram schematically showing a light modulation element, and FIG. 5B is a diagram schematically showing a light intensity distribution. It is a figure explaining the light distribution produced | generated on the pupil plane of an imaging optical system with the object which has a periodic structure, Comprising: In this figure, the pupil plane P is shown by both the side surface and the plane. It is a figure which shows that the light intensity distribution in the pupil plane of an imaging optical system becomes a grating | lattice structure in the case of coherent illumination, Comprising: In this figure, the pupil plane P is shown by both a side surface and a plane . In the case of partial coherent illumination, the light intensity distribution on the pupil plane of the imaging optical system becomes a distribution in which the shape of the exit pupil of the illumination system is superimposed on the lattice points in FIG. The pupil plane P is shown on both the side and the plane. FIG. 5 is a diagram schematically showing a calculation result of a light intensity distribution obtained on the pupil plane of the imaging optical system using the light modulation element of FIG. 3 under the condition of FIG. 4 (σ value = 0.5). FIG. 6 is a diagram schematically showing a calculation result of a light intensity distribution obtained on the pupil plane of the imaging optical system using the light modulation element of FIG. 3 under the condition of FIG. 5 (σ value = 0.6). It is a figure explaining the production | generation method of a Wigner site cell. FIG. 12A is a diagram illustrating an effect obtained when the shape of the exit pupil of the illumination system is changed to a Wigner-Site cell shape, and FIG. 12A shows a case where the shape of the exit pupil is set to a circular shape. (B) shows a case where the shape of the exit pupil is set to the Wigner-Site-Cell shape. It is a figure which shows a mode that the shape of the opening part of the aperture stop in an illumination system was set to the square shape as a Wigner site cell shape. Light obtained on the pupil plane of the imaging optical system using the light modulation element of FIG. 3 when the shape of the exit pupil of the illumination system is set to the Wigner-Site cell shape and the σ value is set to 0.6 or equivalent It is a figure which shows roughly the calculation result of intensity distribution. When the shape of the exit pupil of the illumination system is set to the Wigner-Site cell shape and the σ value is set to be equivalent to 0.6, the light modulation element similar to the light modulation element shown in FIG. FIG. 15A is a diagram schematically illustrating the light modulation element, and FIG. 15B is a diagram schematically illustrating the light intensity distribution. It is a figure which shows roughly the structure of the light modulation element concerning a modification. Calculation results of light intensity distribution obtained on the pupil plane of the imaging optical system using the light modulation element of FIG. 16 when the shape of the exit pupil of the illumination system is set to a circular shape and the σ value is set to 0.6 FIG. 16 schematically shows the light intensity distribution formed on the substrate to be processed using the light modulation element of FIG. 16 when the shape of the exit pupil of the illumination system is set to a circular shape and the σ value is set to 0.6. FIG. Light obtained on the pupil plane of the imaging optical system using the light modulation element of FIG. 16 when the shape of the exit pupil of the illumination system is set to the Wigner-Site cell shape and the σ value is set to be equivalent to 0.6 It is a figure which shows roughly the calculation result of intensity distribution. Light intensity distribution formed on the substrate to be processed using the light modulation element of FIG. 16 when the shape of the exit pupil of the illumination system is set to the Wigner-Site cell shape and the σ value is set to 0.6 or equivalent. FIG. (A) thru | or (e) are process sectional drawings which show the process of producing an electronic device using the crystallization apparatus of this embodiment. It is a figure which illustrates the conventional crystallization technique roughly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light modulation element 2 Illumination system 2a Light source 2b Beam expander 2c, 2e Fly eye lens 2d, 2f Condenser optical system 2g Aperture stop 3 Imaging optical system 4 Substrate 5 Substrate stage

Claims (7)

A light irradiation device for irradiating a surface to be irradiated with light having a predetermined light intensity distribution,
A light modulation element having a light modulation pattern of a periodic structure represented by a basic translation vector (a1, a2);
An illumination system for illuminating the light modulation element with light;
An imaging optical system disposed between the light modulation element and the irradiated surface to form the predetermined light intensity distribution obtained by the light modulation pattern on the irradiated surface;
The shape of the exit pupil of the illumination system is similar to the Wigner-Sites cell of the basic reciprocal lattice vector (b1, b2) obtained from the basic translation vector (a1, a2) by the following equation.
b1 = 2π (a2 × a3) / (a1 · (a2 × a3))
b2 = 2π (a3 × a1) / (a1 · (a2 × a3))
In the above equation, a3 is a vector having an arbitrary size in the normal direction of the plane of the light modulation pattern of the light modulation element, “·” represents an inner product of the vectors, and “×” represents an outer product. . In the light irradiation device for irradiating the irradiated surface with light having a predetermined light intensity distribution,
A light modulation element having a light modulation pattern of a periodic structure represented by a basic translation vector (a1, a2);
An illumination system for illuminating the light modulation element;
An imaging optical system disposed between the light modulation element and the irradiated surface to form the predetermined light intensity distribution corresponding to the light modulation pattern on the irradiated surface;
The shape of the exit pupil of the illumination system is a light irradiation device that is not convex with respect to the direction of the basic reciprocal lattice vector (b1, b2) obtained from the basic translation vector (a1, a2) by the following equation.
b1 = 2π (a2 × a3) / (a1 · (a2 × a3))
b2 = 2π (a3 × a1) / (a1 · (a2 × a3))
In the above formula, a3 is a vector having an arbitrary size in the normal direction of the light modulation pattern surface of the light modulation element, “·” represents an inner product of the vectors, and “×” represents an outer product. The light irradiation apparatus according to claim 1 or 2, wherein the basic translation vectors a1 and a2 are orthogonal to each other. A light irradiation device for irradiating a surface to be irradiated with light having a predetermined light intensity distribution,
A light modulation element for modulating the incident light and emitting the modulated light;
An illumination system for illuminating the light modulation element;
An imaging optical system disposed between the light modulation element and the irradiated surface to form the predetermined light intensity distribution corresponding to the modulated light on the irradiated surface;
The shape of the exit pupil of the illumination system is set to a shape other than a circular shape that allows the 0th-order diffracted light from the light modulation element to pass through and the first-order diffracted light does not substantially pass through the aperture of the pupil plane of the imaging optical system. The light irradiation apparatus provided with the exit pupil shape setting part for doing. Using a light modulation element that modulates incident light and an imaging optical system disposed between the light modulation element and the irradiated surface, the irradiated surface is irradiated with light having a predetermined light intensity distribution. A light irradiation method for
The shape of the exit pupil of the illumination system that illuminates the light modulation element is a shape other than a circular shape in which the first-order diffracted light component of the light from the light modulation element does not substantially pass through the aperture of the pupil plane of the imaging optical system Light irradiation method to set to. 5. A non-single crystal semiconductor, comprising: the light irradiation apparatus according to claim 1; and a stage for holding a non-single crystal semiconductor film on the irradiated surface, the non-single crystal semiconductor held on the irradiated surface A crystallization apparatus for forming a crystallized semiconductor film by irradiating at least a part of the film with light having the predetermined light intensity distribution. The light irradiation apparatus according to any one of claims 1 to 4 or the light irradiation method according to claim 5, wherein the predetermined portion is applied to at least a part of the non-single-crystal semiconductor film held on the irradiated surface. A crystallization method in which a crystallized semiconductor film is irradiated with light having a light intensity distribution of

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