JP2005129915A - Crystallization apparatus, crystallization method, device, and phase modulation element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a crystallized semiconductor film having a large grain size by realizing sufficient lateral-crystal-growth from crystalline nuclei with avoiding influence of ablation in the semiconductor film. <P>SOLUTION: The apparatus has a light modulation optical-system having a first element (1) for forming desired light-intensity gradient distribution in injection light, and a second element (2) for forming desired light-intensity minimum distribution in a reverse peak pattern in the injection light; and an imaging optical-system (4) provided between the light modulation optical-system and a substrate (5) having a polycrystalline semiconductor film or amorphous semiconductor film. A crystallized semiconductor film is formed by radiating the incidence light, forming the light-intensity gradient distribution and the light-intensity minimum distribution, to the polycrystalline semiconductor film or the amorphous semiconductor film via the imaging optical-system. A pattern of the first element is opposed to a pattern of the second element. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a crystallization apparatus that generates a crystallized semiconductor film by irradiating a polycrystalline semiconductor film or an amorphous semiconductor film with a laser beam, a phase modulation element used in the crystallization apparatus, a crystallization method, and a device And about. In particular, the present invention relates to a crystallization apparatus for generating a crystallized semiconductor film by irradiating a polycrystalline semiconductor film or an amorphous semiconductor film with laser light having a predetermined light intensity distribution that is phase-modulated using a phase modulation element. And a phase modulation element used in the crystallization apparatus, a crystallization method, and a device.

  Conventionally, for example, a thin-film-transistor (TFT) is used as a switching element for controlling a voltage applied to a pixel of a liquid crystal display (LCD). This thin film transistor is formed in an amorphous silicon (polymorphic silicon) layer or a polycrystalline silicon (poly-Silicon) layer.

  The polycrystalline silicon layer has higher electron or hole mobility than the amorphous silicon layer. Therefore, when the transistor is formed on the polycrystalline silicon layer, the switching speed is faster than when the transistor is formed on the amorphous silicon layer. And the response of the display becomes faster. 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. In addition, peripheral circuits such as a driver circuit and a DAC can be operated at a higher speed by being incorporated in a display.

  Polycrystalline silicon consists of a collection of crystal grains, but has a lower mobility of electrons or holes than single crystal silicon. In addition, a large number of thin film transistors formed in polycrystalline silicon has a problem of variations in the number of crystal grain boundaries in the channel portion. 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 crystallization method for generating crystallized silicon having a large grain size has been proposed.

  Conventionally, as this kind of crystallization method, “phase control ELA (Excimer Laser Laser) is used to generate a crystallized semiconductor film by irradiating an excimer laser beam onto a phase shifter close to a polycrystalline semiconductor film or an amorphous semiconductor film in parallel. Annealing) method is known. Details of the phase control ELA method are disclosed in, for example, “Surface Science (English: Journal of the Surface Science Society of Japan) Vol. 21, No. 5, pp. 278-287, 2000”.

  In the phase control ELA method, first, an inverse peak pattern in which the light intensity is lower than that of the periphery at a point corresponding to the phase shift portion of the phase shifter (a pattern in which the light intensity is the lowest at the center and the light intensity rapidly increases toward the periphery). A light intensity distribution is generated. Then, the polycrystalline semiconductor film or the amorphous semiconductor film is irradiated with light having the light intensity distribution of the reverse peak pattern. As a result, a temperature gradient is generated in the melting region according to the light intensity distribution. Corresponding to the point with the lowest light intensity, crystal nuclei are formed in the first solidified or non-melted part. A crystal grows laterally from the crystal nucleus toward the periphery (hereinafter referred to as “lateral growth” or “lateral growth”), thereby generating a single crystal grain having a large grain size.

Conventionally, in “Electrochemical Society Proceeding Volume 2000-31, pages 148-154, 261-268”, for example, an element (referred to as mask # 2) having a pattern that forms a V-shaped light intensity gradient distribution, and reverse peak light An element having a pattern that forms a minimum intensity distribution (referred to as mask # 1) is realized by providing a phase step on the SiO ₂ substrate. The two elements are irradiated with excimer laser light in a state of being close to the substrate to be processed, thereby generating a crystallized semiconductor film on the substrate to be processed.

  Therefore, in the crystallization process, when an ablation phenomenon occurs from the substrate to be processed, the evaporated material adheres to the facing surface of the mask # 1 facing the substrate to be processed. In the next step in which the evaporated material is attached, the light intensity distribution formed by the masks # 1 and # 2 is disturbed, and the crystallization area and the crystallization shape are disturbed. Further, the irradiation of the laser beam in which the masks # 1 and # 2 and the substrate to be processed are close to each other is performed by constantly maintaining the distance of the order of μm between the mask # 1 and the substrate to be processed at the time of each laser beam irradiation. This operation time requires a long time, and the tact time becomes relatively slow.

In addition, in “The Institute of Electronics, Information and Communication (IEICE) Transactions) Vol. J85-C, No. 8, p. 624-629, August 2002” An element having a pattern forming a V-shaped light intensity gradient distribution is realized by the thickness distribution of the light absorbing material SiONx, and an element having a pattern forming an inverse peak light intensity minimum distribution is realized by the phase step of SiO ₂ doing. However, these two elements are stacked on a single substrate. Then, the crystallized semiconductor film is generated on the substrate to be processed by irradiating the excimer laser light with the substrate to be processed being brought close to this one element substrate.

  In Japanese Patent Laid-Open No. 2000-306859, an imaging optical system is arranged between a phase shifter having a line and space pattern with a phase difference of 180 degrees and a substrate to be processed. Then, the crystallized semiconductor film is generated on the substrate to be processed by irradiating the substrate to be processed with the light having the light intensity distribution of the reverse peak pattern generated through the phase shifter through the imaging optical system. .

M. NAKATA and M. MATSUMURA, "Two-Dimensionally Position-Controlled Ultra-Large Grain Growth Based on Phase-Modulated Excimer-Laser Annealing Method", Electrochemical Society Proceeding Volume 2000-31, page 148-154 Inoue, Nakata, Matsumura, “Amplitude / Phase Controlled Excimer Laser Melting Recrystallization Method of Silicon Thin Films—New 2-D Position Controlled Large Grain Formation Method”, IEICE Transactions, The Institute of Electronics, Information and Communication Engineers, August 2002, Vol. J85-C, No. 8, p. 624-629 JP 2000-306859 A

  However, in the conventional technique (proximity method or proxy method) in which the substrate to be processed is brought close to the element, there is a problem that the element is contaminated due to ablation in the semiconductor film, and thus good crystallization is prevented. Further, it is necessary to separate the substrate to be processed and the element each time the step moves to another processing region on the substrate to be processed, which disadvantageously increases the processing time. Further, since the interval to be set between the element and the substrate to be processed is very small, it is difficult to introduce detection light for position detection in this narrow optical path, and it is difficult to adjust the interval. There was an inconvenience.

  On the other hand, in the prior art using a phase shifter having a line-and-space pattern with a phase difference of 180 degrees, the valley portion in the light intensity distribution of the reverse peak pattern formed becomes too deep. In this case, since the crystal does not grow unless the light intensity is equal to or higher than a predetermined threshold value, there is a disadvantage that a crystallized semiconductor film having a large grain size cannot be generated because a region that is not crystallized becomes too large. Furthermore, it was not possible to obtain a large gradient in the light intensity distribution of the reverse peak pattern for crystallization with a large particle size.

  The present invention has been made in view of the above-mentioned problems, and can obtain a light intensity distribution having a desired gradient for crystallization with a large grain size, and sufficient lateral crystal growth from a crystal nucleus. It is an object of the present invention to provide a crystallization apparatus and a crystallization method capable of generating a crystallized semiconductor film having a large grain size by realizing the above.

In order to solve the above-mentioned problem, in the first embodiment of the present invention, the first element (1) that forms a desired light intensity gradient distribution and the desired reverse peak light intensity minimum distribution are formed in incident light. A light modulation optical system having two elements (2);
An imaging optical system (4) provided between the light modulation optical system and a substrate (5) having a polycrystalline semiconductor film or an amorphous semiconductor film,
Crystallization for generating a crystallized semiconductor film by irradiating the polycrystalline semiconductor film or the amorphous semiconductor film with incident light on which the light intensity gradient distribution and the minimum light intensity distribution are formed via the imaging optical system Providing equipment. In this case, it is preferable that the pattern of the first element and the pattern of the second element face each other.

  In the first embodiment of the present invention, the combined light intensity distribution of the light intensity gradient distribution formed through the first element and the inverse peak-shaped light intensity minimum distribution formed through the second element is formed on the substrate surface. It is formed. As a result, the formation position of crystal nuclei, that is, the starting point of crystal growth can be made as close as possible to the position where the light intensity is the smallest in the inverse peak light intensity minimum distribution. Then, sufficient lateral crystal growth from the crystal nuclei can be realized along the light intensity gradient direction in the intensity gradient distribution, and a crystallized semiconductor film having a large grain size can be generated. At this time, in the first embodiment of the present invention, unlike the proximity method, the imaging optical system is interposed between the first element or the second element and the substrate, and the distance between the substrate and the imaging optical system is also increased. Since it is relatively large, good crystallization can be realized without the first and second elements and the imaging optical system receiving adhesion due to ablation on the substrate. In addition, since the distance between the substrate and the imaging optical system is relatively large, there is no need to separate the substrate and the imaging optical system when stepping to another processing area on the substrate, and high throughput is achieved. Can be realized. In addition, since the distance between the substrate and the imaging optical system is relatively large, detection light for position detection is introduced into the optical path between them to adjust the positional relationship between the substrate and the imaging optical system. Easy to do.

In the second embodiment of the present invention, an element (7) having a combined pattern in which a first pattern that forms a desired light intensity gradient distribution and a second pattern that forms a desired minimum light intensity distribution are combined;
An imaging optical system (4) provided between the element and a substrate having a polycrystalline semiconductor film or an amorphous semiconductor film,
A crystallized semiconductor film is irradiated by irradiating the polycrystalline semiconductor film or the amorphous semiconductor film through the imaging optical system with incident light in which the light intensity gradient distribution and the light intensity minimum distribution are formed by the composite pattern. A crystallizing apparatus is provided. In this case, the pattern forming the light intensity gradient distribution and the pattern forming the minimum light intensity distribution are both phase modulation patterns, and the phase modulation amount of the composite pattern is the phase modulation of the pattern forming the light intensity gradient distribution. It preferably corresponds to the sum of the amount and the pattern phase modulation amount forming the minimum light intensity distribution.

  In the second embodiment of the present invention, instead of the first element and the second element in the first embodiment, there is a composite pattern of a pattern that forms a light intensity gradient distribution and a pattern that forms an inverse peak light intensity minimum distribution. One element is used. As a result, the second embodiment of the present invention has the advantage that not only the effects of the first embodiment as described above can be obtained, but also the number of alignment can be reduced only by alignment of one element.

  According to a preferred aspect of the first form and the second form, the first pattern forming the light intensity gradient distribution has a minimum dimension optically smaller than the radius of the point image distribution range of the imaging optical system and the first pattern. The occupation area ratio of the first region having the phase value of 1 and the second region having the second phase value has a phase distribution that varies depending on the position. With this configuration, it is possible to generate a light intensity distribution in a free form.

  In this case, the light intensity gradient distribution is a V-shaped light having a three-dimensional shape in which a V shape having a gradient in a certain one-dimensional direction (for example, the X direction) is formed along a predetermined direction (for example, the Y direction). Intensity distribution. The first pattern forming the light intensity gradient distribution is a linear region extending along a direction parallel to the bottom in a portion corresponding to the bottom of the V-shaped light intensity distribution (it is not necessary to be a complete straight line). It is preferable that the portion has a substantially linear shape), and an isolated region is provided in a portion away from a portion corresponding to the bottom of the V-shaped light intensity distribution. In this configuration, uniform optical characteristics can be obtained along the bottom of the light intensity gradient distribution by the action of the linear region, so that the alignment between the first element and the second element is displaced in a predetermined direction. However, there is an advantage that the optical characteristics of the resultant synthesized light intensity distribution are hardly changed.

  Further, according to a preferred aspect of the first form and the second form, the second pattern forming the minimum light intensity distribution has a plurality of band-like regions extending along the light intensity gradient direction in the light intensity gradient distribution. In addition, adjacent band-like regions have different phase values. In this case, the plurality of belt-shaped regions have three or more types of belt-shaped regions having different phase values, and the difference between the phase values of two adjacent belt-shaped regions is substantially the same value including the sign in one direction. It is preferable to have. In this configuration, even when the surface of the substrate is defocused with respect to the second pattern surface of the second element, the peak points in the reverse peak-shaped minimum light intensity distribution are maintained at regular intervals. As a result, the intervals between the center positions of the generated crystal grains become uniform, and as a result, crystal grains having the same shape are arranged along the Y direction, which is advantageous when a thin film transistor (TFT) is formed on the crystal grains. is there.

  Further, according to a preferred aspect of the first form and the second form, the second pattern forming the minimum light intensity distribution has a form in which three or more regions having different phase values are adjacent to each other at a predetermined point. . In this configuration, a point-reversed peak-shaped light intensity minimum distribution is generated according to a desired form only at the bottom of the light intensity gradient distribution, and the ideal light intensity for positioning the starting point of crystal growth. Distribution is obtained. In the first and second embodiments, it is preferable that the pupil function of the imaging optical system is smaller in the periphery than in the center. This configuration can reduce or eliminate unnecessary peaks that occur in the vicinity of the reverse peak-shaped light intensity minimum distribution obtained in the defocused state, and the symmetry of the light intensity minimum distribution in the defocused state is also considerably broken. Alleviated.

According to a third aspect of the present invention, there is provided a light modulation element having a first element (1) that forms a light intensity gradient distribution and a second element (2) that forms a light intensity gradient minimum distribution with incident light. Illuminate and
The light intensity gradient distribution and the light intensity minimum distribution are formed via an imaging optical system (4) provided between the light modulation optical system and a substrate having a polycrystalline semiconductor film or an amorphous semiconductor film. There is provided a crystallization method for generating a crystallized semiconductor film by irradiating the polycrystalline semiconductor film or the amorphous semiconductor film with the incident light.

In the fourth embodiment of the present invention, the element (7) having a combined pattern of the first pattern that forms the light intensity gradient distribution and the second pattern that forms the minimum light intensity distribution is illuminated by incident light,
Incidence in which the light intensity gradient distribution and the light intensity minimum distribution are formed via an imaging optical system (4) provided between the element and a substrate having a polycrystalline semiconductor film or an amorphous semiconductor film. Provided is a crystallization method for generating a crystallized semiconductor film by irradiating the polycrystalline semiconductor film or the amorphous semiconductor film with light.

  According to a fifth aspect of the present invention, there is provided a device manufactured using the crystallization apparatus of the first or second form or the crystallization method of the third or fourth form. In this case, a good semiconductor device, liquid crystal display device, or the like can be manufactured based on a crystallized semiconductor film having a large grain size obtained by realizing sufficient lateral growth from a crystal nucleus.

According to a sixth embodiment of the present invention, there is provided a phase modulation element having a pattern that forms a light intensity minimum distribution having an inverse peak shape in incident light,
The pattern includes three or more types of band-like regions having different phase values, and a phase modulation element having a difference in phase value between two adjacent band-like regions having substantially the same value including a sign in one direction. provide.

According to a seventh aspect of the present invention, there is provided a phase modulation element having a pattern that forms a V-shaped light intensity distribution in incident light,
An area ratio occupied by the first region and the second region, the first region having a first phase value having a minimum dimension smaller than a predetermined size and a second region having a second phase value; Has a phase distribution that varies with position,
The pattern has a linear region extending along a direction parallel to the bottom in a portion corresponding to the bottom of the V-shaped light intensity distribution, and a portion corresponding to the bottom of the V-shaped light intensity distribution A phase modulation element having an isolated region is provided at a portion away from the region.

  In the present invention, a combined light intensity distribution of the light intensity gradient distribution formed through the first element and the inverse peak light intensity minimum distribution formed through the second element is formed on the substrate surface. As a result, a light intensity distribution having a desired gradient can be obtained, and crystallization with a large particle diameter can be performed. Further, according to the present invention, the formation position of crystal nuclei, that is, the starting point of crystal growth can be made as close as possible to the position where the light intensity is the smallest in the reverse peak light intensity minimum distribution, and the light intensity in the light intensity gradient distribution A sufficient lateral crystal growth from the crystal nucleus along the gradient direction can be realized, and a crystallized semiconductor film having a large grain size can be generated.

  In the present invention, unlike the proximity method, the imaging optical system is interposed between the first element or the second element and the substrate, and the distance between the substrate and the imaging optical system is relatively large. Therefore, good crystallization can be realized without the first element and the second element being affected by ablation in the substrate. In addition, since the distance between the substrate and the imaging optical system is relatively large, there is no need to separate the substrate and the imaging optical system when stepping to another processing area on the substrate, and high throughput is achieved. Can be realized. In addition, since the distance between the substrate and the imaging optical system is relatively large, detection light for position detection is introduced into the optical path between them to adjust the positional relationship between the substrate and the imaging optical system. Easy to do.

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 a first embodiment of the present invention. FIG. 2 is a diagram schematically showing the internal configuration of the illumination system of FIG. This will be described with reference to FIGS. The crystallization apparatus of the first embodiment includes a first phase modulation element 1 that forms an optical pattern of a desired light intensity gradient distribution in incident light, and a second pattern that has a pattern that forms a light intensity minimum distribution having an inverse peak shape. And a phase modulation element 2. The pattern configurations of the first phase modulation element 1 and the second phase modulation element 2 will be described later.

  In addition, the 1st phase modulation element 1 and the 2nd phase modulation element 2 are arrange | positioned adjacently so that a pattern may face. The crystallization apparatus of the first embodiment includes an illumination system 3 for illuminating the first phase modulation element 1 and the second phase modulation element 2 whose optical axes are coaxially arranged. The illumination system 3 is an optical system shown in FIG. 2, for example, and includes a KrF excimer laser light source 3a that supplies light having a wavelength of 248 nm. As the light source 3a, another appropriate light source such as a XeCl excimer laser light source or a YAG laser light source can be used. The laser light supplied from the light source 3a is expanded through the beam expander 3b and then enters the first fly's eye lens 3c.

  Thus, a plurality of light sources are formed on the rear focal plane of the first fly-eye lens 3c, and light beams from these plurality of light sources are incident on the incident surface of the second fly-eye lens 3e via the first condenser optical system 3d. Are illuminated in a superimposed manner. As a result, more light sources are formed on the rear focal plane of the second fly-eye lens 3e than on the rear focal plane of the first fly-eye lens 3c. Light beams from a plurality of light sources formed on the rear focal plane of the second fly's eye lens 3e are superimposed on the first phase modulation element 1 and the second phase modulation element 2 via the second condenser optical system 3f. Illuminate.

  Here, the first fly-eye lens 3c and the first condenser optical system 3d constitute a first homogenizer, and the first phase modulation element 1 and the second phase modulation for the laser light supplied from the light source 3a by the first homogenizer. Uniformity regarding the incident angle on the element 2 is achieved. The second fly-eye lens 3e and the second condenser optical system 3f constitute a second homogenizer, and the first phase modulation element 1 and the laser beam whose incident angles from the first homogenizer are uniformized by the second homogenizer The light intensity at each position in the surface on the second phase modulation element 2 is made uniform. Thus, the illumination system 3 irradiates the first phase modulation element 1 and the second phase modulation element 2 with the laser light having a substantially uniform light intensity distribution. In other words, the illumination system 3 illuminates the first phase modulation element 1, and transmitted light that has passed through the first phase modulation element 1 enters the second phase modulation element 2.

  The laser light phase-modulated by the first phase modulation element 1 and the second phase modulation element 2 is incident on the substrate 5 to be processed via the imaging optical system 4. Here, the imaging optical system 4 optically conjugates the intermediate surface between the pattern surface of the first phase modulation element 1 and the pattern surface of the second phase modulation element 2 and the substrate 5 to be processed. In other words, the substrate to be processed 5 is set to a surface optically conjugate with the intermediate surface (image surface of the imaging optical system 4). The imaging optical system 4 includes an aperture stop 4c between the positive lens group 4a and the positive lens group 4b.

  The aperture stop 4c may include a plurality of aperture stops having different sizes of openings (light transmission portions), and the plurality of aperture stops 4c may be configured to be interchangeable with respect to the optical path. Alternatively, the aperture stop 4c may have an iris stop that can continuously change the size of the opening. In any case, the size of the aperture of the aperture stop 4c (and consequently the image-side numerical aperture NA of the imaging optical system 4) has a required light intensity distribution on the semiconductor film of the substrate 5 to be processed, as will be described later. It is set to generate.

The imaging optical system 4 may be a refractive optical system, a reflective optical system, or a refractive / reflective optical system. Further, the substrate to be processed 5 is obtained by sequentially forming a base film and an amorphous silicon film on a plate glass for a liquid crystal display, for example, by chemical vapor deposition (CVD). The base film is an insulating film such as SiO ₂ , and the amorphous silicon and the glass substrate are in direct contact with each other to prevent foreign substances such as Na from entering the amorphous silicon. Prevents heat transfer to the glass substrate. The substrate 5 to be processed is positioned and held at a predetermined position on the substrate stage 6 by a vacuum chuck or an electrostatic chuck.

3A to 3F are diagrams for explaining the basic principle of the first phase modulation element. 3A to 3F, the same parts as those in FIGS. 1 and 2 are denoted by the same reference numerals, and detailed description thereof will be omitted because it is redundant. In general, the light amplitude distribution U (x, y) of the image formed by the first phase modulation element 1 is expressed by the following equation (1). In Equation (1), T (x, y) is the complex amplitude transmittance distribution of the first phase modulation element 1, * is convolution (convolution integration), and ASF (x, y) is imaging optics. The point spread function of the system 4 is shown. Here, the point spread function is defined as the amplitude distribution of the point image by the imaging optical system.
U (x, y) = T (x, y) * ASF (x, y) (1)

The complex amplitude transmittance distribution T of the first phase modulation element 1 is expressed by the following equation (2) because the amplitude is uniform. In Equation (2), T ₀ is a constant value, and φ (x, y) indicates a phase distribution.
T = T ₀ e ^{iφ (x, y)} (2)

When the imaging optical system 4 has a uniform circular pupil and has no aberration, the relationship shown in the following formula (3) is established with respect to the point spread function ASF (x, y). In equation (3), J ₁ represents a Bessel function, λ represents the wavelength of light, and NA represents the image-side numerical aperture of the imaging optical system 4 as described above.
ASF (x, y) ∝ 2J ₁ (2π / λ · NA · r) / (2π / λ · NA · r) (3)
However, r = (x ² + y ² ) ^1/2

  The point spread function of the imaging optical system 4 shown in FIG. 3A is shown in FIG. 3B. When approximated by a cylindrical shape 4e having a diameter R (shown by a broken line in FIG. 3B), the first phase modulation shown in FIG. An integral of the complex amplitude distribution in the circle of the diameter R ′ on the element 1 (R = M × R ′, where M is the magnification of the imaging optical system) is on the image plane 4f. Determine the complex amplitude of. As described above, the light amplitude, that is, the light intensity of the image formed on the image plane 4f is given by the convolution of the complex amplitude transmittance distribution of the first phase modulation element 1 and the point spread function. When the point spread function is approximated by a cylinder 4e, the result of integrating the complex amplitude transmittance of the phase modulation element 1 with a uniform weight within the circular point spread range R shown in FIG. 3C is the image of FIG. 3A. The complex amplitude at the surface 4f is obtained, and the square of the absolute value is the light intensity. The point image distribution range R in the imaging optical system 4 refers to a range within the intersection 4j with the 0 point 4i of the curve of FIG. 3B drawn by the point image distribution function.

Therefore, the light intensity increases as the phase change in the point image distribution range R decreases, and conversely, the light intensity decreases as the phase change increases. This point can be easily understood by considering the sum of the phase vectors 4h in the unit circle 4g as shown in FIG. 3D. When the image plane 4f is an object such as a semiconductor film, the point spread function of FIG. 3B is a point spread function as shown in FIG. 3F. FIG. 3E shows one point of the image plane 4f, and the light intensity at this point is determined by the above process. 4A to 4C are diagrams showing a typical relationship between the phase change within the point spread range R and the light intensity. The hatching in FIG. 4B and FIG. 4C is given to clarify the portion where the phase value is different. FIG. 4A is a diagram showing a case where the phase values of the four regions obtained by dividing the surface of the phase modulation element 1 into four are all 0 degrees, and the sum of the four phase vectors 4k in the 0 degree direction corresponds to the amplitude 4E. The square corresponds to the light intensity 16I. Here, E is a value indicating the radius of the dotted circle in the lower diagram of FIG. 4A, and I is defined as E ² = I.

FIG. 4B is a diagram illustrating a case where the phase values of two regions separated in the above four regions are 0 degrees and the phase values of the other two separated regions are 90 degrees, The sum of the phase vector 4m and the two phase vectors 4n in the 90-degree direction is the amplitude, and its value corresponds to the square root of 8E ² (because 4E ² + 4E ² = 8E ² ), and its light intensity is the square of the amplitude This corresponds to 8I. FIG. 4C is a diagram showing the phase modulation elements 1 and 2 when the phase value is 0 degree, the phase value is 90 degrees, the phase value is 180 degrees, and the phase value is 270 degrees. The sum of the phase vector 4s in the 0 degree direction, the phase vector 4t in the 90 degree direction, the phase vector 4u in the 180 degree direction, and the phase vector 4v in the 270 degree direction corresponds to the amplitude 0E, and the square thereof corresponds to the light intensity 0I. It will be.

  5A and 5B are diagrams showing the relationship between the pupil function and the point spread function in the imaging optical system 4. In general, the point spread function is given by the Fourier transform of the pupil function. Specifically, when the imaging optical system 4 has a uniform circular pupil and has no aberration, the point spread function ASF (x, y) is expressed by the above-described equation (3). However, this is not the case when there is aberration in the imaging optical system 4 or when there is a pupil function other than the uniform circular pupil.

In the case of a uniform circular pupil and no aberration, as shown in FIG. 5B, the radius R / 2 of the central region (ie, Airy disk) until the point spread function first becomes 0 is expressed by the following equation (4). It is known that
R / 2 = 0.61λ / NA (4)

  In this specification, the point image distribution range R means a circular central region until the point image distribution function ASF (x, 0) first becomes 0, as shown in FIGS. 3B and 5B. . As is apparent with reference to FIGS. 4A to 4C, there are a plurality of (four in FIGS. 4A to 4C) phase modulation units in a circle optically corresponding to the point spread range R of the imaging optical system. If included, it is possible to control the amplitude of light by the sum of a plurality of phase vectors (4k, 4m, 4n, 4s-4v), and consequently the intensity of the light analytically and according to a simple calculation. . As a result, it is possible to relatively easily obtain a light intensity distribution for crystallization with a large particle diameter, which is generally difficult to realize.

  Therefore, in the present invention, the phase modulation unit of the first phase modulation element 1 is optically smaller than the radius R / 2 of the point image distribution range R of the imaging optical system 4 in order to freely control the light intensity. It is necessary. In other words, the size of the phase modulation unit of the first phase modulation element 1 on the image side of the imaging optical system 4 needs to be smaller than the radius R / 2 of the point image distribution range R of the imaging optical system 4. It is. Hereinafter, the configuration and operation of the first phase modulation element 1 in the first embodiment will be described.

  6A and 6B are diagrams schematically showing the overall configuration of the first phase modulation element in the first embodiment. The hatching in FIGS. 6A and 7A is given to clarify the portion of the first region 1b. 7A and 7B are diagrams schematically showing the configuration of the basic pattern in the first phase modulation element of FIG. 6A. The pattern of the first phase modulation element 1 shown in FIG. 6A includes the basic pattern shown in FIG. 7A. Referring to FIG. 7A, the basic pattern of the first phase modulation element 1 includes a plurality of cells (rectangular shapes in the figure) having a size optically smaller than the radius R / 2 of the point image distribution range R of the imaging optical system 4. 1c) (shown by a broken line).

  Each cell 1c has, for example, a first region (shown by a hatched portion in the figure) 1b having a phase value (first phase value) of 90 degrees and a phase value (second phase value) of 0 degrees, for example. A second region (indicated by a blank portion in the figure) 1a is formed. As shown in FIG. 7A, the occupation area ratio of the first region 1b and the second region 1a in each cell 1c changes for each cell. In other words, it has a phase distribution in which the occupation area ratio of the first region 1b having a phase value of 90 degrees and the second region 1a having a phase value of 0 degrees varies depending on the position in the X direction. More specifically, the occupation area ratio of the second region 1a in the cell is closest to 50% in the left cell in the drawing, is closest to 100% in the right cell in the drawing, and along the X direction therebetween. It is changing monotonously.

  As described above, the first phase modulation element 1 has a phase distribution based on the phase modulation unit (cell) 1c having a size optically smaller than the radius R / 2 of the point image distribution range R of the imaging optical system 4. . Therefore, the light intensity distribution formed on the substrate 5 to be processed by appropriately changing the occupied area ratio of the first region 1b and the second region 1a in each phase modulation unit 1c, that is, the sum of the two phase vectors. Can be controlled analytically and according to simple calculations.

  Specifically, as shown in FIG. 6B, the light intensity is highest at both side positions where the occupied area ratio of the second region 1a is closest to 100%, and the occupied area ratio of the second region 1a is the center closest to 50%. A V-shaped light intensity gradient distribution having a gradient in the one-dimensional direction having the smallest light intensity at the position (having a gradient in the X direction) is obtained. Here, the V-shape does not mean only a complete V-shape. For example, as shown in FIG. 6B, a concept including a valley shape that is almost V-shaped as shown in FIG. It is. Further, the V-shaped shape is not limited to one, and it is sufficient that a part of the V-shaped shape is included. For example, the number of the first phase modulation elements 1 shown in FIG. 6A is not necessarily one, and a plurality of V-shaped light intensity distributions corresponding to the first phase modulation elements 1 may be provided. The first phase modulation element 1 can be manufactured, for example, by forming a thickness distribution corresponding to a required phase step on a quartz glass substrate. The change in the thickness of the quartz glass substrate can be formed by selective etching or FIB (Focused Ion Beam) processing.

  8A and 8B are diagrams schematically showing the configuration of the second phase modulation element in the first embodiment. Referring to FIG. 8A, the pattern of the second phase modulation element 2 has a plurality of strip regions (only four are shown) extending in the vertical direction in the drawing, and the strip regions adjacent to each other have different phase values. Specifically, the second phase modulation element 2 is a phase shifter having a line-and-space pattern with a phase difference of 90 degrees, and a rectangular first belt-shaped area 2a having a phase value of 0 degrees It has a pattern in which rectangular second band-like regions 2b having a phase value of 90 degrees are alternately formed. The hatching in FIG. 8A is given to clarify the portion of the second belt-like region 2b.

  In this case, as shown in FIG. 8B, the light intensity is the smallest in the phase shift line, which is the boundary line between the first strip region 2a and the second strip region 2b, toward the periphery (along the Y direction which is the pitch direction). An inverse peak light intensity minimum distribution in which the light intensity increases rapidly (on both sides) is obtained. Similarly to the first phase modulation element 1, the second phase modulation element 2 can be manufactured, for example, by forming a thickness distribution corresponding to a required phase step on a quartz glass substrate. The change in the thickness of the quartz glass substrate can be formed by selective etching or FIB.

  In the first embodiment, the direction in which the occupied area ratio of the first region 1b and the second region 1a changes in the first phase modulation element 1 (the direction indicated by the broken line 1d in FIG. 6A) and the second phase modulation element 2 The direction of the phase shift line (the direction indicated by the solid line 2c in FIG. 8A) is matched. In other words, the pattern of the second phase modulation element 2 has a plurality of band-like regions extending along the light intensity gradient direction (X direction) in the light intensity gradient distribution formed via the first phase modulation element 1. .

  As a result, as a first embodiment, FIG. 9A shows a perspective view of a V-shaped light intensity gradient distribution 1e formed via the first phase modulation element 1, and FIG. 9B shows the second phase modulation element 2 The perspective view with reverse peak-shaped light intensity minimum distribution 2d formed via is shown. The hatching in FIG. 9A, FIG. 9B and FIG. 10 is given to clarify the portions of the first region 1b and the second belt-like region 2b. In the second phase modulation element 2 shown in FIG. 9B, the first band region 2a and the second band region 2b are configured to include three reverse peaks of the minimum light intensity minimum distribution. Therefore, in comparison with the second phase modulation element 2 that forms five reverse peaks shown in FIG. 8A, the second phase modulation element 2 in FIGS. 9B and 10 is the width of the first band region 2a and the second band region 2b at both ends. Is half.

  FIG. 10 shows a V-shaped light intensity gradient distribution 1e formed via the first phase modulation element 1, and an inverse peak light intensity minimum distribution 2d formed via the second phase modulation element 2. The combined light intensity distribution is shown.

  For easier understanding, FIG. 11 is a perspective view of the combined light intensity distribution in the case where only one reverse peak of the light intensity minimum distribution formed via the second phase modulation element 2 is included. The figure is shown. That is, a combined light intensity distribution 5 a having a V-shaped pattern + 1 reverse peak pattern is formed on the surface of the substrate 5 to be processed. In the light intensity distribution 5a of the V-shaped pattern + one reverse peak pattern, the crystal nucleus formation position, that is, the starting point of crystal growth is made as close as possible to the position where the light intensity is the smallest in the reverse peak light intensity minimum distribution 2d. A sufficient lateral crystal growth from the crystal nucleus along the light intensity gradient direction (X direction) in the V-shaped light intensity gradient distribution 1e is realized, and a large-grain crystallized semiconductor film is formed. Can be generated.

  In the first embodiment, unlike the proximity method, the imaging optical system 4 is interposed between the second phase modulation element 2 and the substrate to be processed 5 and the substrate to be processed 5 and the imaging optical system 4 are. Is relatively large, so that the first phase modulation element 1, the second phase modulation element 2, and the imaging optical system 4 do not adhere to the product due to ablation from the substrate 5 to be processed. Crystallization can be realized. In the first embodiment, unlike the proximity method, a relatively large distance is ensured between the substrate 5 to be processed and the imaging optical system 4. Even when moving stepwise, it is not necessary to separate the substrate 5 and the imaging optical system 4, and high-throughput processing can be realized.

  In the first embodiment, unlike the proximity method, the distance between the substrate 5 to be processed and the imaging optical system 4 is relatively large, so that detection for position detection in the optical path between them is possible. It is easy to adjust the positional relationship between the substrate 5 to be processed and the imaging optical system 4 by introducing light. As described above, the crystallization apparatus and the crystallization method of the first embodiment realize sufficient crystal growth in the lateral direction from the crystal nucleus while avoiding the influence of ablation in the semiconductor film, thereby increasing the grain size. A crystallized semiconductor film can be generated.

  12A and 12B are diagrams schematically illustrating an overall configuration of a first phase modulation element according to a first modification of the first embodiment. The hatching in FIG. 12A is given to clarify the portion of the first region 11b. The first phase modulation element 11 according to the first modification has a configuration similar to that of the first phase modulation element 1 of the first embodiment. However, in the first phase modulation element 1 of the first embodiment, all the first regions 1b having a phase value of 90 degrees have the form of isolated regions and are discretely arranged over the whole. The first phase modulation element 11 according to the modification is different in that the first region 11b having a phase value of 90 degrees has a mixed form of a linear region and an isolated region.

  Specifically, as shown in FIG. 12A, the pattern of the first phase modulation element 11 according to the first modification is a direction parallel to the bottom (Y) in the portion corresponding to the bottom of the V-shaped light intensity gradient distribution. Three linear regions 11bs extending along (direction), and a large number of isolated regions 11bi in the other portion, that is, the portion away from the bottom of the V-shaped light intensity gradient distribution along the X direction. Here, the width (dimension in the X direction) of the linear region 11bs is such that the occupied area ratio between the first region 11b and the second region 11a is the second region 1b and the second region 1b in the first phase modulation element 1 of the first embodiment. It is set so as to correspond to the occupation area ratio with the region 1a.

  Thus, by using the first phase modulation element 11 according to the first modification, as in the case of the first phase modulation element 1 of the first embodiment, a one-dimensional gradient as shown in FIG. In 12B, a V-shaped light intensity gradient distribution having a gradient in the X direction is obtained. Then, in the first phase modulation element 11, the direction in which the occupation area ratio of the first region 11b and the second region 11a changes (the direction indicated by the broken line 11c in FIG. 12A) and the phase shift line in the second phase modulation element 2 By matching the direction (the direction indicated by the solid line 2c in FIG. 8A), the light intensity distribution 5a of the V-shaped pattern + reverse peak pattern as shown in FIGS. 10 and 11 is formed on the surface of the substrate 5 to be processed. It is formed.

  Since the first phase modulation element 1 of the first embodiment has the isolated regions 1b discretely arranged along the Y direction in the portion corresponding to the bottom of the V-shaped light intensity gradient distribution, the V-shaped A completely uniform optical characteristic cannot be obtained along the bottom of the light intensity gradient distribution. Although it can be made uniform by increasing the number of divisions of the isolated region, it cannot be made completely uniform. As a result, in the first phase modulation element 1 of the first embodiment, the occupying area ratio of the first region 1b and the second region 1a changes (the direction indicated by the broken line 1d in FIG. 6A) and the second phase modulation. The optical characteristics of the combined light intensity distribution obtained when the direction of the phase shift line in the element 2 (the direction indicated by the solid line 2c in FIG. 8A) is displaced in the Y direction are likely to vary.

  On the other hand, in the first phase modulation element 11 according to the first modification example, the linear region 11bs extending along the Y direction is provided in a portion corresponding to the bottom of the V-shaped light intensity gradient distribution. A completely uniform optical characteristic can be obtained along the bottom of the V-shaped light intensity gradient distribution. As a result, in the first phase modulation element 11 according to the first modification, the direction in which the occupied area ratio of the first region 11b and the second region 11a changes (the direction indicated by the broken line 11c in FIG. 12A) and the second phase Even if the direction of the phase shift line in the modulation element 2 (the direction indicated by the solid line 2c in FIG. 8A) is displaced in the Y direction, there is an advantage that the optical characteristics of the resultant combined light intensity distribution are hardly changed.

  FIG. 13 is a diagram schematically showing a configuration of a crystallization apparatus according to the second embodiment of the present invention. FIG. 14A is a diagram schematically showing an overall configuration of a third phase modulation element in the second embodiment. The hatching in FIG. 14A is given to clarify the portions of the first regions 7b and 7b '. FIG. 14B is a diagram showing a cross section of FIG. 14A. An arrow means irradiation of incident light. The crystallization apparatus according to the second embodiment has a configuration similar to that of the crystallization apparatus according to the first embodiment. However, the first embodiment includes the first phase modulation element 1 and the second phase modulation element 2, whereas the second embodiment replaces the first phase modulation element 1 and the second phase modulation element 2. The difference is that the third phase modulation element 7 is composed of one sheet. Hereinafter, the second embodiment will be described by focusing on the differences from the first embodiment.

  In the second embodiment, as shown in FIG. 13, instead of the first phase modulation element 1 and the second phase modulation element 2 of the first embodiment, the light intensity having an inverse peak shape with the pattern forming the light intensity gradient distribution is used. One third phase modulation element 7 having a combined pattern with the pattern forming the minimum distribution is provided. Here, the pattern surface of the third phase modulation element 7 is set to face the imaging optical system 4. Further, the phase modulation amount of the combined pattern of the third phase modulation element 7 is the phase modulation amount of the pattern forming the light intensity gradient distribution in the first phase modulation element 1 of the first embodiment and the second phase modulation amount of the first embodiment. This corresponds to the sum of the phase modulation amount of the pattern forming the inverse peak light intensity minimum distribution in the phase modulation element 2.

  Specifically, as shown in FIG. 14A, the third phase modulation element 7 is divided into a lower region and an upper region by a boundary line 7c along the X direction. In the lower region, a first region 7b and a second region 7a are provided so as to correspond to the first region 1b and the second region 1a in the pattern of the first phase modulation element 1 of the first embodiment. And the phase value of the 1st field 7b and the 2nd field 7a is the phase value of the 1st field 2a of the 2nd phase modulation element 2 of a 1st embodiment to the phase value of the 1st field 1b and the 2nd field 1a. It is a value with 0 degrees added. That is, the phase value of the first region 7b is 90 degrees corresponding to the phase value of the first region 1b, and the phase value of the second region 7a is 0 degree corresponding to the phase value of the second region 1a. Here, the phase angle is positive when the phase is delayed.

  On the other hand, in the upper region, the first region 7b ′ and the second region 7a ′ are provided so as to correspond to the first region 1b and the second region 1a in the pattern of the first phase modulation element 1 of the first embodiment. . The phase values of the first region 7b ′ and the second region 7a ′ are the same as the phase values of the first region 1b and the second region 1a, and the phase value of the second region 2b of the second phase modulation element 2 of the first embodiment. It is a value obtained by adding 90 degrees respectively. That is, the phase value of the first region 7b ′ is 180 degrees which is 90 degrees larger than the phase value of the first region 1b, and the phase value of the second region 7a ′ is 90 degrees larger than the phase value of the second region 1a. Degree. A cross-sectional view crossing the upper region and the lower region is shown in FIG. 14B. The positional relationships of 7a (0 degrees), 7b (90 degrees), boundary lines 7c, 7a '(90 degrees), and 7b' (180 degrees) can be clearly understood.

  As described above, the phase modulation amount of the combined pattern of the third phase modulation element 7 according to the second embodiment is the phase modulation amount of the pattern forming the light intensity gradient distribution in the first phase modulation element 1 of the first embodiment. And the sum of the phase modulation amount of the pattern forming the inverse peak light intensity minimum distribution in the second phase modulation element 2 of the first embodiment. Therefore, also in the second embodiment, similarly to the first embodiment, the light intensity distribution 5a of the V-shaped pattern + reverse peak pattern as shown in FIGS. It can be formed on the surface of the substrate 5 to be processed. In addition, unlike the first embodiment, the second embodiment has an advantage that it is not necessary to align the two phase modulation elements.

  FIG. 15 is a diagram schematically showing an overall configuration of a third phase modulation element according to the first modification of the second embodiment. The hatching in FIG. 15 is given to clarify the portions of the first regions 17b and 17b '. The phase modulation amount of the combined pattern of the third phase modulation element 17 according to the first modification shown in FIG. 15 forms a light intensity gradient distribution in the first phase modulation element 11 according to the first modification of the first embodiment. This corresponds to the sum of the phase modulation amount of the pattern and the phase modulation amount of the pattern that forms the reverse peak light intensity minimum distribution in the second phase modulation element 2 of the first embodiment.

  Specifically, as shown in FIG. 15, the third phase modulation element 17 is divided into a lower region and an upper region by a boundary line 17c along the X direction. In the lower region, the first region 11b (11bs, 11bi) and the second region 11a in the pattern of the first phase modulation element 11 (FIG. 12A) according to the first modification of the first embodiment correspond to the first region 11a. A region 17b (17bs, 17bi) and a second region 17a are provided. And the phase value of the 1st field 17b and the 2nd field 17a is the phase value of the 1st field 2a of the 2nd phase modulation element 2 of a 1st embodiment to the phase value of the 1st field 11b and the 2nd field 11a. It is a value with 0 degrees added. That is, the phase value of the first region 17b is 90 degrees corresponding to the phase value of the first region 11b, and the phase value of the second region 17a is 0 degree corresponding to the phase value of the second region 11a.

  On the other hand, in the upper region, the first region 17b ′ corresponds to the first region 11b (11bs, 11bi) and the second region 11a in the pattern of the first phase modulation element 11 according to the first modification of the first embodiment. (17bs ′, 17bi ′) and a second region 17a ′ are provided. The phase values of the first region 17b ′ and the second region 17a ′ are set to the phase values of the first region 11b and the second region 11a, and the phase values of the second region 2b of the second phase modulation element 2 of the first embodiment. It is a value obtained by adding 90 degrees respectively. That is, the phase value of the first region 17b ′ is 180 degrees which is 90 degrees larger than the phase value of the first region 11b, and the phase value of the second region 17a ′ is 90 degrees larger than the phase value of the second region 11a. Degree.

  As described above, the phase modulation amount of the combined pattern of the third phase modulation element 17 according to the first modification forms a light intensity gradient distribution in the first phase modulation element 11 according to the first modification of the first embodiment. This corresponds to the sum of the phase modulation amount of the pattern to be formed and the phase modulation amount of the pattern that forms the inverse peak-shaped minimum light intensity distribution in the second phase modulation element 2 of the first embodiment. Therefore, in this case as well, as in the second embodiment, the light intensity distribution 5a of the V-shaped pattern + reverse peak pattern can be formed on the surface of the substrate 5 to be processed, and unlike the first embodiment. There is an advantage that it is not necessary to align the two phase modulation elements.

  FIGS. 16A to 16D are diagrams schematically illustrating the influence of defocusing on the inverse peak-shaped light intensity minimum distribution formed on the substrate to be processed via the second phase modulation element of the first embodiment. . The hatching in FIG. 16A is given to clarify the portion of the second band-like region 2b. When the pattern surface of the second phase modulation element 2 and the surface of the substrate 5 to be processed as shown in FIG. 16A are optically conjugate via the imaging optical system 4, that is, the second phase modulation element 2 When the surface of the substrate to be processed 5 is set to the focus position with respect to the pattern surface, the light of the reverse peak shape as shown in FIG. A minimum intensity distribution is formed.

  In this case, if the first belt-like region 2a and the second belt-like region 2b of the second phase modulation element 2 are of equal pitch, the peak point with the smallest light intensity in the reverse peak light intensity minimum distribution is along the Y direction. Appears at regular intervals. However, when the surface of the substrate 5 to be processed is set to a defocus position that is out of the focus position with respect to the pattern surface of the second phase modulation element 2, the peak points are alternately shown in FIGS. 16B and 16D. In other words, the peak points are not evenly spaced and the symmetry of each pitch is lost.

  As a result, the interval between the center positions of the generated crystal grains becomes uneven, and as a result, crystal grains having two different shapes are alternately arranged along the Y direction. Incidentally, a thickness deviation that inevitably causes defocusing is unavoidably present in the substrate 5 to be processed, and its cycle is about several centimeters. On the other hand, the size of the crystal grains is several μm, which is much smaller than the period of the plate thickness deviation. Accordingly, when viewed in the range of adjacent crystal grains, the defocus amount can be considered to be substantially uniform.

  17A to 17D schematically illustrate the influence of defocusing on the inverse peak light intensity minimum distribution formed on the substrate to be processed via the second phase modulation element according to the first modification of the first embodiment. FIG. The hatching in FIG. 17A is given in order to clarify a portion having a different phase. Referring to FIG. 17A, the second phase modulation element 12 according to the first modification includes a rectangular first strip region 12a having a phase value of 0 degrees and a rectangular second strip having a phase value of 90 degrees. A region 12b, a rectangular third strip region 12c having a phase value of 180 degrees, and a rectangular fourth strip region 12d having a phase value of 270 degrees are repeatedly formed along one direction (Y direction). Have a different pattern.

  In the first modification, when the surface of the substrate to be processed 5 is set to the focus position with respect to the pattern surface of the second phase modulation element 12, the surface of the substrate to be processed 5 is interposed via the second phase modulation element 12. Thus, an inverse peak-shaped light intensity minimum distribution as shown in FIG. 17C is formed. In this case, if the first belt-like region 12a, the second belt-like region 12b, the third belt-like region 12c, and the fourth belt-like region 12d of the second phase modulation element 2 have the same pitch, the light in the reverse peak light intensity minimum distribution is obtained. Peak points with the smallest intensity appear at equal intervals along the Y direction.

  On the other hand, when the surface of the substrate to be processed 5 is set to a defocus position that is out of the focus position with respect to the pattern surface of the second phase modulation element 12, as shown in FIGS. Will shift by the same amount in the same direction. However, the equidistant state is maintained at the peak points in the inverse peak-shaped light intensity minimum distribution. As a result, the intervals between the center positions of the generated crystal grains become uniform (symmetry is maintained for each pitch), and the same shape of crystal grains is arranged along the Y direction. This is advantageous when forming a thin film transistor (TFT).

  In the modification of FIG. 17A, the second phase modulation element 12 has four types of belt-like regions 12a to 12d having different phase values, and the difference between the phase values of two adjacent belt-like regions is directed to the + Y direction. The configuration is +90 degrees. However, the present invention is not limited to this, and there are three or more types of belt-like regions having different phase values, and the difference between the phase values of two belt-like regions adjacent to each other is substantially the same value including the sign in one direction. It is also possible to have a configuration having

  By the way, in the second embodiment described above, the third phase modulation having a combined pattern of the pattern of the first phase modulation element 1 according to the first embodiment and the pattern of the second phase modulation element 2 according to the first embodiment. The third phase modulation element having a combined pattern of the pattern of the element 7 and the first phase modulation element 11 according to the first modification of the first embodiment and the pattern of the second phase modulation element 2 according to the first embodiment 17 is used. However, a third phase modulation element having a combined pattern of the pattern of the first phase modulation element 1 or the pattern of the first phase modulation element 11 and the pattern of the second phase modulation element 12 according to the modification of FIG. 17A is used. You can also.

  18A to 18D show the imaging optical system for the inverse peak-shaped light intensity minimum distribution formed on the substrate to be processed via the second phase modulation element according to the first modification of the first embodiment. It is a figure which shows typically the influence which a pupil function gives. FIG. 18A shows the pupil function of the imaging optical system 4. When the pupil function of the imaging optical system 4 is constant from the center to the periphery as shown by the broken line 100 in FIG. 18A, the inverse peak-shaped light intensity minimum obtained in the defocused state is obtained as shown in FIGS. 17B and 17D. An unnecessary peak as indicated by a broken-line circle 8a is generated in the distribution, resulting in an asymmetric minimum light intensity distribution. Moreover, this kind of relatively large unnecessary peak 8a also causes ablation.

  On the other hand, when the pupil function of the imaging optical system 4 has a form smaller in the periphery than the center as shown by a solid line 101 in FIG. 18A, for example, a pupil function having a Gaussian distribution with the periphery being 60% and the center being 100%. 18B and 18D, the reverse peak-shaped light intensity minimum distribution obtained in the defocused state generates only a small unnecessary peak as shown by the broken-line circle 8b, and the light intensity in the defocused state Since the collapse of symmetry in the minimum distribution is considerably relaxed, it is preferable. Note that the pupil function of the Gaussian distribution as shown by the solid line 101 is realized by inserting a transmission filter having a predetermined transmittance distribution in the vicinity of the exit surface of the second fly's eye lens 3e in the illumination system 3 of FIG. The

  FIG. 19A is a diagram schematically showing an overall configuration of a second phase modulation element according to the second modification of the first embodiment. The hatching in FIG. 19A is given in order to clarify a portion having a different phase. FIG. 19B is a diagram schematically showing an overall configuration of the first phase modulation element in the first embodiment corresponding to the second phase modulation element according to the second modification of the first embodiment shown in FIG. 19A. The hatching in FIG. 19B is given to clarify the portion of the first region 1b. Referring to FIG. 19A, the second phase modulation element 22 according to the second modification has a form in which four types of rectangular regions 22a, 22b, 22c, and 22d having different phase values are adjacent to each other in a predetermined point region 22e. Have. Specifically, the second phase modulation element 22 includes, for example, a first rectangular area 22a having a phase value of 0 degree, a second rectangular area 22b having a phase value of 90 degrees, and a third rectangular area having a phase value of 180 degrees. It has a rectangular region 22c and a fourth rectangular region 22d having a phase value of 270 degrees.

  The four straight lines intersecting in a cross shape in the point area 22e are the boundary lines between the first rectangular area 22a and the second rectangular area 22b, the second rectangular area 22b, and the third rectangular area 22c. Corresponding to the boundary line between the third rectangular region 22c and the fourth rectangular region 22d, and the boundary line between the fourth rectangular region 22d and the first rectangular region 22a. It is configured. In this case, the point area 22e constitutes a shift portion, and as shown in FIG. 20, the point reverse peak in which the light intensity is the smallest in the point area 22e and the light intensity rapidly increases in all surrounding directions. The light intensity minimum distribution 22f is obtained.

  Therefore, when the second phase modulation element 22 according to the second modification is used together with the first phase modulation element 1, a gradient is formed in one dimension formed via the first phase modulation element 1 as shown in FIG. The combined light intensity distribution of the V-shaped light intensity gradient distribution 1e and the point inverse peak-shaped light intensity minimum distribution 22f formed via the second phase modulation element 22, that is, V-shaped pattern + point inverse peak A light intensity distribution 5b having a pattern is formed on the surface of the substrate 5 to be processed. Here, referring to the combined light intensity distribution 5a of FIGS. 10 and 11 obtained in the first embodiment, a relatively high light intensity portion of the V-shaped light intensity gradient distribution 1e having a one-dimensional gradient is shown. Thus, it can be seen that the reverse peak-shaped light intensity minimum distribution 2d has an influence, and an ideal light intensity distribution is not necessarily obtained.

  On the other hand, referring to the combined light intensity distribution 5b of FIG. 20 obtained by using the second phase modulation element 22 according to the second modification in combination with the first phase modulation element 1, the light intensity minimum in a point-reversed peak shape is obtained. It can be seen that the distribution 22f affects only the bottom portion of the V-shaped light intensity gradient distribution 1e having a one-dimensional gradient according to a desired form, and an ideal light intensity distribution is obtained. In this case, the formation position of crystal nuclei, that is, the starting point of crystal growth can be defined as the position of the light intensity minimum distribution 22f having a point-reversed peak shape, and in the V-shaped light intensity gradient distribution 1e having a one-dimensional gradient. A sufficient lateral crystal growth from the crystal nucleus along the light intensity gradient direction (X direction) can be realized, and a crystallized semiconductor film having a large grain size can be generated.

  19A has a configuration in which four types of rectangular regions 22a, 22b, 22c, and 22d having different phase values are adjacent to each other in a predetermined point region 22e. Adopted. However, the present invention is not limited to this, and a configuration in which three or more types of regions having different phase values are adjacent to each other at a predetermined point is also possible.

  In each of the embodiments described above, the light intensity distribution can be calculated even at the design stage, but it is desirable to observe and confirm the light intensity distribution on the actual surface to be processed. For this purpose, the surface to be processed of the substrate 5 to be processed may be enlarged by an optical system and input by an imaging device such as a CCD. When the used light is ultraviolet light, the optical system is restricted, so that a fluorescent plate may be provided on the surface to be processed and converted into visible light.

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 each embodiment. As shown in FIG. 21A, on an insulating substrate 80 (for example, alkali glass, quartz glass, plastic, polyimide, etc.), a base film 81 (for example, SiN having a thickness of 50 nm and a SiO ₂ laminated film having a thickness of 100 nm). The substrate 5 to be processed is prepared by forming an amorphous semiconductor film 82 (for example, Si, Ge, SiGe having a film thickness of about 50 nm to 200 nm) using a chemical vapor deposition method or a sputtering method. Then, using a crystallization apparatus according to each embodiment, a predetermined region on the surface of the amorphous semiconductor film 82 is irradiated with a laser beam 83 (for example, a KrF excimer laser beam or a XeCl excimer laser beam). .

In this way, as shown in FIG. 21B, a polycrystalline semiconductor film or a single crystallized semiconductor film 84 having crystals with a large grain size is generated. Next, as illustrated in FIG. 21C, the polycrystalline semiconductor film or the single crystallized semiconductor film 84 is processed into an island-shaped semiconductor film 85 that serves as a region for forming a thin film transistor, for example, using a photolithography technique. An SiO ₂ film having a thickness of 20 nm to 100 nm is formed as the gate insulating film 86 by using a chemical vapor deposition method, a sputtering method, or the like. Further, as shown in FIG. 21D, a gate electrode 87 (for example, silicide or MoW) is formed on the gate insulating film, and impurity ions 88 (phosphorus, P in the case of an N channel transistor) are formed using the gate electrode 87 as a mask. Boron) is ion-implanted in the case of a channel transistor. Thereafter, 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 in the island-shaped semiconductor film 85. Next, as shown in FIG. 21E, an interlayer insulating film 89 is formed to make contact holes, and a source electrode 93 and a drain electrode 94 connected to a source 91 and a drain 92 connected by a channel 90 are formed.

  In the above process, the channel 90 is formed in accordance with the position of the large grain crystal of the polycrystalline semiconductor film or the single crystallized semiconductor film 84 generated in the process shown in FIGS. 21A and 21B. 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 embodiment, the phase modulation element 2 may be provided on the light incident side of the first phase modulation element 1. Further, the first and second phase modulation elements may be provided integrally.

  The crystallization apparatus configured as described above has the following characteristics because the imaging optical system 4 is provided between the phase modulation elements 1 and 2 and the substrate 5 to be processed. During each crystallization step, the distance between the phase modulation elements 1 and 2 and the substrate to be processed 5 can be always met at a constant high speed. The takt time of the crystallization process is increased. Since the imaging optical system 4 is provided between the phase modulation elements 1 and 2 and the substrate to be processed 5, even if an ablation phenomenon occurs in the crystallization process from the substrate to be processed 5, it adheres to the phase modulation element. There is no.

It is a figure which shows roughly the structure of the crystallization apparatus concerning 1st Embodiment of this invention. It is a figure which shows schematically the internal structure of the illumination system of FIG. It is a figure explaining the basic principle of a 1st phase modulation element. It is a figure which shows the typical relationship between the change of the phase in a point image distribution range, and light intensity. It is a figure which shows the relationship between the pupil function and point spread function in an imaging optical system. It is a figure which shows schematically the whole structure of the 1st phase modulation element in 1st Embodiment. It is a figure which shows schematically the structure of the basic pattern in the 1st phase modulation element of FIG. 6A. It is a figure which shows schematically the structure of the 2nd phase modulation element in 1st Embodiment. (A) is a perspective view schematically showing a form of a V-shaped light intensity gradient distribution formed via a first phase modulation element, and (B) is formed via a second phase modulation element. It is a perspective view which shows roughly the form of reverse peak-shaped light intensity minimum distribution. The form of the combined light intensity distribution of the V-shaped light intensity gradient distribution formed via the first phase modulation element and the inverse peak light intensity minimum distribution formed via the second phase modulation element is schematically shown. It is a perspective view shown in FIG. The form of the combined light intensity distribution of the V-shaped light intensity gradient distribution formed via the first phase modulation element and the inverse peak light intensity minimum distribution formed via the second phase modulation element is schematically shown. It is a perspective view shown in FIG. It is a figure which shows roughly the whole structure of the 1st phase modulation element concerning the 1st modification of 1st Embodiment. It is a figure which shows roughly the structure of the crystallization apparatus concerning 2nd Embodiment of this invention. (A) is a figure which shows roughly the whole structure of the 3rd phase modulation element in 2nd Embodiment, (B) is a figure which shows schematically sectional drawing of the 3rd phase modulation element in 2nd Embodiment. is there. It is a figure which shows schematically the whole structure of the 3rd phase modulation element concerning the 1st modification of 2nd Embodiment. It is a figure which shows typically the influence which reverse peak-shaped light intensity minimum distribution formed on a to-be-processed substrate via the 2nd phase modulation element of 1st Embodiment receives by defocusing. It is a figure which shows typically the influence which the reverse peak-shaped light intensity minimum distribution formed on a to-be-processed substrate via the 2nd phase modulation element concerning the 1st modification of 1st Embodiment receives by defocusing. Schematic illustration of the influence of the pupil function of the imaging optical system on the inverse peak-shaped light intensity minimum distribution formed on the substrate to be processed via the second phase modulation element according to the first modification of the first embodiment. FIG. (A) is a figure which shows roughly the whole structure of the 2nd phase modulation element concerning the 2nd modification of 1st Embodiment, (B) is the 2nd modification of 1st Embodiment shown to (A). It is a figure which shows roughly the whole structure of the 1st phase modulation element in 1st Embodiment corresponding to the 2nd phase modulation element concerning. The combined light intensity of the V-shaped light intensity gradient distribution formed through the first phase modulation element and the reverse peak light intensity minimum distribution formed through the second phase modulation element according to the second modification. It is a perspective view which shows the form of distribution roughly. It is process sectional drawing which shows the process of producing an electronic device using the crystallization apparatus of each embodiment.

Explanation of symbols

1, 11 First phase modulation element 2, 12, 22 Second phase modulation element 3 Illumination system 3a KrF excimer laser light source 3b Beam expander 3c, 3e Fly eye lens 3d, 3f Condenser optical system 4 Imaging optical system 4c Aperture stop 5 Substrate 6 Substrate stages 7 and 17 Third phase modulation element

Claims (16)

A light modulation optical system having a first element (1) for forming a desired light intensity gradient distribution and a second element (2) for forming a desired reverse peak light intensity minimum distribution in incident light;
An imaging optical system (4) provided between the light modulation optical system and a substrate (5) having a polycrystalline semiconductor film or an amorphous semiconductor film,
Crystallization for generating a crystallized semiconductor film by irradiating the polycrystalline semiconductor film or the amorphous semiconductor film with incident light on which the light intensity gradient distribution and the minimum light intensity distribution are formed via the imaging optical system apparatus. The first element (1) has a first pattern forming the light intensity gradient distribution, and the second element (2) has a second pattern forming the light intensity minimum distribution, The crystallization apparatus according to claim 1, wherein the patterns face each other. An element (7) having a combined pattern in which a first pattern forming a desired light intensity gradient distribution and a second pattern forming a desired light intensity minimum distribution are combined;
An imaging optical system (4) provided between the element and a substrate having a polycrystalline semiconductor film or an amorphous semiconductor film,
A crystallized semiconductor film is irradiated by irradiating the polycrystalline semiconductor film or the amorphous semiconductor film through the imaging optical system with incident light in which the light intensity gradient distribution and the light intensity minimum distribution are formed by the composite pattern. Crystallizer to produce. Each of the first and second patterns is a phase modulation pattern, and the phase modulation amount of the combined pattern is the phase modulation amount of the pattern forming the light intensity gradient distribution and the phase modulation of the pattern forming the light intensity minimum distribution. The crystallization apparatus according to claim 3, which corresponds to the sum of the quantity. The first pattern forming the light intensity gradient distribution includes a first region having a first dimension optically smaller than a radius of a point image distribution range of the imaging optical system, and a second phase. 5. The crystallization according to claim 2, further comprising: a second region having a phase value, and having a phase distribution in which an occupied area ratio of the first region and the second region varies depending on a position. apparatus. The light intensity gradient distribution has a V-shaped light intensity distribution at least in part.
The first pattern forming the light intensity gradient distribution has a linear region extending along a direction parallel to the bottom in a portion corresponding to the bottom of the V-shaped light intensity distribution. 6. The crystallization apparatus according to claim 5, wherein an isolated region is provided in a portion away from a portion corresponding to the bottom of the light intensity distribution. The second pattern forming the minimum light intensity distribution has a plurality of band-like regions extending along a light intensity gradient direction in the light intensity gradient distribution, and adjacent band-like regions have mutually different phase values. The crystallization apparatus according to any one of 2 to 6. The plurality of belt-like regions have three or more types of belt-like regions having different phase values, and a difference in phase value between two adjacent belt-like regions has a substantially equal value including a sign in one direction. Item 8. The crystallization apparatus according to Item 7. 7. The second pattern forming the minimum light intensity distribution has three or more types of regions having different phase values, and these regions are adjacent to each other at a predetermined point. The crystallization apparatus according to 1. The crystallization apparatus according to claim 1, wherein the imaging optical system has a smaller pupil function in the periphery than in the center. Illuminating a light modulation element having a first element (1) that forms a light intensity gradient distribution and a second element (2) that forms a minimum light intensity distribution having an inverse peak shape by incident light,
The light intensity gradient distribution and the light intensity minimum distribution are formed via an imaging optical system (4) provided between the light modulation optical system and a substrate having a polycrystalline semiconductor film or an amorphous semiconductor film. A crystallization method for generating a crystallized semiconductor film by irradiating the polycrystalline semiconductor film or the amorphous semiconductor film with the incident light. Incident light illuminates the element (7) having a combined pattern of a first pattern that forms a light intensity gradient distribution and a second pattern that forms a minimum light intensity distribution;
Incidence in which the light intensity gradient distribution and the light intensity minimum distribution are formed via an imaging optical system (4) provided between the element and a substrate having a polycrystalline semiconductor film or an amorphous semiconductor film. A crystallization method for generating a crystallized semiconductor film by irradiating the polycrystalline semiconductor film or the amorphous semiconductor film with light. A device manufactured using the crystallization apparatus according to claim 1 or the crystallization method according to claim 11 or 12. A phase modulation element having a pattern that forms a reverse light intensity minimum distribution in incident light,
The pattern has three or more types of belt-like regions having different phase values, and the phase value difference between two belt-like regions adjacent to each other has a substantially equal value including a sign in one direction. A phase modulation element having a pattern that forms a V-shaped light intensity distribution on incident light,
An area ratio occupied by the first region and the second region, the first region having a first phase value having a minimum dimension smaller than a predetermined size and a second region having a second phase value; Has a phase distribution that varies with position,
The pattern has a linear region extending along a direction parallel to the bottom in a portion corresponding to the bottom of the V-shaped light intensity distribution, and a portion corresponding to the bottom of the V-shaped light intensity distribution A phase modulation element having an isolated region in a part away from the element. An optical element that forms a reverse light intensity minimum distribution in incident light; and
An imaging optical system provided between the optical element and a substrate having a polycrystalline semiconductor film or an amorphous semiconductor film and having a pupil function smaller in the periphery than in the center;
A crystallization apparatus for generating a crystallized semiconductor film by irradiating the polycrystalline semiconductor film or the amorphous semiconductor film with incident light having the minimum light intensity distribution.

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