JP2006309207A - Beam homogenizer and laser irradiation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a beam homogenizer for homogenizing energy distribution by making the distance between lenses small to shorten the optical path length with the use of an array lens of an optical path shortened type, and a laser irradiation apparatus using the same. <P>SOLUTION: The beam homogenizer is equipped with a front side array lens of an optical path shortened type whose second principal point is positioned ahead on a beam incidence side, a back side array lens of an optical path shortened type whose first principal point is positioned behind on a beam emission side, and a condensing lens, wherein the distance between the second principal point of the front side array lens and the first principal point of the back side array lens is equal to the focal length of the back side array lens. A cylindrical lens array constituted of two or more array lenses, a combined array lens, such as a fly-eye lens, a cylindrical lens array having curved surfaces on its front and back sides, a fly-eye lens, and an array lens, such as a crossed cylindrical lens, having curved surfaces on its front and back sides, can be used as the array lens of the optical path shortened type. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a beam homogenizer using a more compact optical system that makes the energy distribution of a beam spot on an irradiation surface uniform, and a laser irradiation apparatus using the beam homogenizer.
More specifically, a beam homogenizer that reduces the distance between lenses and shortens the optical path length, thereby uniformizing the energy distribution of the beam spot on the irradiated surface using a more compact optical system, and a laser using the beam homogenizer The present invention relates to an irradiation apparatus.

In recent years, there has been a technique for performing laser annealing on a non-single-crystal semiconductor film (a semiconductor film having crystallinity such as polycrystalline or microcrystalline or an amorphous semiconductor, not a single crystal) formed over an insulating substrate such as glass. Has been extensively studied.
The laser annealing here means a technique for recrystallizing a damaged layer or an amorphous layer formed on a semiconductor substrate or semiconductor film, or a technique for crystallizing a non-single-crystal semiconductor film formed on the substrate. Pointing.
Furthermore, a technique applied to planarization or surface modification of a semiconductor substrate or semiconductor film, a technique of performing laser irradiation after introducing an element that promotes crystallization, such as nickel, into an amorphous semiconductor film, a semiconductor having crystallinity A technique for irradiating a film with a laser is also included.

The reason why laser annealing is used for crystallization is that a glass substrate has a low melting point, and therefore deforms when the substrate temperature is high during annealing.
The laser can give high energy only to the non-single-crystal semiconductor film without significantly changing the temperature of the substrate.
A beam oscillation type laser beam with high output such as an excimer laser is processed with an optical system so that a square spot of several centimeters square or a rectangular shape with a length of 10 cm or more in the long side direction is formed on the irradiated surface. A method of performing laser annealing by scanning the irradiation position of the spot relative to the irradiation surface is preferable because it is excellent in mass productivity and industrially excellent.
A rectangular beam spot having a particularly high aspect ratio is referred to as a linear beam spot.

In particular, when a linear beam spot is used, scanning is performed only in a direction perpendicular to the direction in which the beam width of the linear beam spot is long, unlike the case of using a dotted beam spot that requires scanning in front, rear, left, and right. Since a laser beam can be irradiated onto a large-area irradiation surface, high mass productivity can be obtained.
At this time, the reason why the linear beam is scanned in a direction (hereinafter referred to as the short side direction) perpendicular to the direction in which the beam width is long (hereinafter referred to as the long side direction) is that it is the most efficient scanning direction.
Due to this high mass productivity, the current laser annealing is using a linear beam spot obtained by processing a beam spot of a pulsed excimer laser with an appropriate optical system.

FIG. 6 shows an example of an optical system for processing the cross-sectional shape of the beam spot into a linear shape on the irradiation surface.
The optical system shown in FIG. 6 is very general.
This optical system not only converts the cross-sectional shape of the beam spot into a linear shape, but also at the same time makes the energy distribution of the beam spot uniform on the irradiated surface.
In general, an optical system that makes the energy distribution of a beam spot uniform is called a beam homogenizer.

The optical system shown in FIG. 6 is also a beam homogenizer.
When a XeCl excimer laser (wavelength 308 nm) is used as a light source, it is preferable to use quartz as the base material of the optical system.
When another excimer laser having a shorter wavelength is used as a light source, it is preferable to use a base material such as florite or MgF _{2 in} order to obtain high transmittance.

FIG. 6A is a side view of a beam homogenizer that forms a linear beam spot.
The side view includes the short side direction of the linear beam spot formed by the beam homogenizer on the paper surface.
A laser beam emitted from a laser oscillator 601 which is a XeCl excimer laser is divided into one direction by a cylindrical lens array 602a and 602b.
The short side direction is bent in the direction of light bent by the mirror when the mirror enters the middle of the optical system.

In this configuration, there are four divisions.
These divided spots are once combined into one spot by the cylindrical lens 604.
The spot separated again is reflected by the mirror 606 and then condensed again into one spot on the irradiation surface 608 by the doublet cylindrical lens 607.
The doublet cylindrical lens refers to a lens composed of two cylindrical lenses.
Thereby, the energy in the short side direction of the linear beam spot is made uniform, and the length in the short side direction is determined.

FIG. 6B is a plan view of a beam homogenizer that forms a linear beam spot.
The plan view includes the long side direction of the linear beam spot formed by the beam homogenizer on the paper surface.
The laser beam emitted from the laser oscillator 601 is split by a cylindrical lens array 603 in a direction perpendicular to the long side direction.
The long side direction is bent in the direction of the light bent by the mirror when the mirror enters in the middle of the optical system.

In this lens array 603 configuration, there are seven divisions.
Thereafter, the seven spots divided by the cylindrical lens 605 are combined into one at the irradiation surface 608.
The mirror 606 and subsequent lines are indicated by broken lines. The broken line indicates the exact optical path and the position of the irradiation surface when the mirror 606 is not disposed.
Thereby, the energy in the long side direction of the linear beam spot is made uniform, and the length in the long side direction is determined.

As described above, the cylindrical lens array 602a, the cylindrical lens array 602b, and the cylindrical lens array 603 are lenses that divide the laser beam spot.
The uniformity of the energy distribution of the obtained linear beam spot is determined by the number of divisions.

The shape of the laser beam generated by the excimer laser is generally rectangular and falls within the range of 1 to 5 when expressed in terms of aspect ratio.
The intensity of the laser beam spot shows a Gaussian distribution that is stronger toward the center of the laser beam spot.
The spot size of the laser beam is converted into a linear beam spot having a uniform spot shape of 320 mm and 0.4 mm by the optical system shown in FIG.

JP, 2001-216881, A The linear beam spot processed by the above-mentioned composition is irradiated in piles, gradually shifting in the short side direction of the beam spot. Then, laser annealing can be performed on the entire surface of the non-single crystal semiconductor film to crystallize or improve crystallinity. Currently, laser annealing of a semiconductor film is performed in a mass production factory using a beam spot processed into a long line by the optical system as described above. Some beam homogenizers use a reflecting mirror (see, for example, Patent Document 1).

In recent years, in the semiconductor device manufacturing process, in order to improve the mass productivity by forming more semiconductor devices in one substrate, the glass substrate has been rapidly increased in size.
With the increase in the size of the glass substrate, an improvement in the processing capability of laser annealing by increasing the length of the linear beam in the long side direction has been strongly demanded.
However, if the length of the linear beam in the long side direction is increased, the optical system for forming the linear beam becomes large with the length in the long side direction, and the area occupied by the optical system increases. The problem occurs.

In view of the above problems, the present invention has been intensively researched and developed to provide a small beam homogenizer for forming a rectangular beam, particularly a linear beam, and as a result has been successfully developed.
Therefore, the present invention provides a beam homogenizer that uses a more compact optical system, that is, an optical system that reduces the distance between lenses and shortens the optical path length, and uniformizes the energy distribution of the beam spot on the irradiation surface, and uses the same. It is an object of the present invention to provide a conventional laser irradiation apparatus, that is, an object.

As described above, the present invention provides a small beam homogenizer for forming a rectangular beam, particularly a linear beam, and a laser irradiation apparatus using the beam homogenizer.
The invention of the beam homogenizer uses an optical path shortening type array lens in which the optical path can be shortened at the principal point, and can be roughly divided into three types depending on the usage.
That is, a first form in which an optical path shortening type array lens is used for both the front and rear array lenses, a second form in which only the front array lens is used, and a third form in which only the rear array lens is used. First, the invention can be broadly divided into three inventions.

The array lens used in the present invention is an assembly of lenses that concatenate a plurality of small lenses, and the beams that have passed through the small lenses converge at the same position by passing through the condenser lens. , It is used as a general term for cylindrical lens arrays, fly-eye lenses, crossed cylindrical lens arrays, and the like.
In addition, the cylindrical lens array may be referred to as a cylindrical array lens.

The invention of each beam homogenizer is specifically shown as follows.
The invention of the beam homogenizer of the first aspect includes an optical path shortening type front array lens in which the second principal point is located in front of the beam incident side, and an optical path shortening type rear array lens in which the first principal point is located in the rear of the beam emitting side. A condenser lens, and the distance between the second principal point of the front array lens and the first principal point of the rear array lens is the focal length of the rear array lens. .

  In the above description, when the distance between the second principal point of the front array lens and the first principal point of the rear array lens is the focal distance of the rear array lens, the distance between the former and the focal distance of the latter coincide. However, in the case of a lens system with a long focal length, it is possible to perform homogenization sufficiently even in a somewhat ambiguous state due to the effect of increasing the focal depth, etc. If it is within the range, the former distance is the focal length of the latter.

  The invention of the beam homogenizer of the second aspect comprises an optical path shortening type front array lens whose second principal point is located in front of the beam incident side, an optical path non-shortening type rear array lens, and a condenser lens, and further comprising the front array The distance between the second principal point of the lens and the first principal point of the rear array lens is the focal length of the rear array lens, and the invention of the beam homogenizer of the third aspect is An optical path non-shortening type front array lens, an optical path shortening type rear array lens whose first principal point is located on the rear side of the beam exit side, and a condensing lens, and further, a second principal point of the front array lens and the rear array The distance from the first principal point of the lens is the focal length of the rear array lens.

In the beam homogenizer of the present invention roughly classified into the three, a plurality of types, that is, a composite array lens or an array lens having curved surfaces on both sides can be used for the front array lens and the rear array lens.
As the synthetic array lens, a plurality of types, that is, two or more cylindrical lens arrays or fly-eye lenses can be used.
Further, a plurality of types of array lenses having curved surfaces on both sides, that is, any of a cylindrical lens array, a fly-eye lens, or a crossed cylindrical lens array having curved surfaces on both the front and rear sides can be used.

Also, regarding the curved surface shape of each lens, both convex and concave shapes can be used.
In this case, the same type of array lens having curved surfaces on both sides used for the front array lens and the rear array lens may be used.
For example, when a cylindrical lens array is used for the front lens of the optical path shortening type front array lens, it is preferable to use the same type of cylindrical lens array for the rear lens and the front and rear lenses of the rear array lens. .
Further, as the condensing lens, any of a cylindrical lens, a toric lens, or a crossed cylindrical lens can be used.

As described above, many forms can be adopted for the beam homogenizer of the present invention.
Therefore, the embodiment of the beam homogenizer of the present invention will be described more specifically below.
As described above, the cylindrical lens array can be adopted as the optical path shortening type array lens of the beam homogenizer of the present invention. In this case, in the first embodiment, the optical path shortening type front array lens and the optical path shortening type rear array lens are used. Are both constituted by two cylindrical lens arrays, the curved surface of the front cylindrical lens array of the front array lens is convex, the curved surface of the rear cylindrical lens array is concave, and the front cylindrical lens array of the rear array lens These curved surfaces are preferably concave, and the curved surface of the rear cylindrical lens array is convex.

In the second embodiment, the optical path shortening type front array lens is composed of two cylindrical lens arrays, the curved surface of the front cylindrical lens array of the front array lens is convex, and the curved surface of the rear cylindrical lens array is concave. In addition, it is preferable that the non-shortened optical path rear array lens is a cylindrical lens array.
Further, in the third embodiment, the optical path non-shortening type front array lens is a cylindrical lens array, the optical path shortening type rear array lens is composed of two cylindrical lens arrays, and the front cylindrical lens of the rear array lens is used. The curved surface of the array is preferably concave, and the curved surface of the rear cylindrical lens array is preferably convex.

  Further, as described above, the fly-eye lens array can be adopted as the optical path shortening type array lens of the beam homogenizer of the present invention. In this case, in the first embodiment, the optical path shortening type front array lens and the optical path shortening type post lens are used. Each of the side array lenses is composed of two fly-eye lenses, the front fly-eye lens of the front array lens has a convex curved surface, the rear fly-eye lens has a concave curved surface, and the front of the rear array lens. The curved surface of the fly-eye lens should be concave, and the curved surface of the rear fly-eye lens should be convex.

In the second embodiment, the optical path shortening type front array lens is composed of two fly eye lenses, the curved surface of the front fly eye lens of the front array lens is convex, and the curved surface of the rear fly eye lens is concave. Further, it is preferable that the non-optical path shortened rear array lens is a fly-eye lens.
Further, in the third embodiment, the optical path non-shortening type front array lens is a fly-eye lens, the optical path shortening type rear array lens is composed of two fly-eye lenses, and the front fly-eye of the rear array lens is formed. The curved surface of the lens is preferably concave, and the curved surface of the rear fly-eye lens is preferably convex.

  Further, as described above, a cylindrical lens array having curved surfaces on both sides can be adopted as the optical path shortening type array lens of the beam homogenizer of the present invention. In that case, in the first embodiment, the optical path shortening type front side array lens and Each of the optical path shortening rear array lenses is composed of a cylindrical lens array having curved surfaces on both sides, the front curved surface of the front array lens is convex, the rear curved surface is concave, and the front curved surface of the rear array lens is The concave shape and the rear curved surface are preferably convex.

In the second embodiment, the optical path shortening type front array lens is constituted by a cylindrical lens array having curved surfaces on both sides, the front curved surface of the front array lens is convex, the rear curved surface is concave, and the optical path non-shortening rear side The array lens is preferably a single-sided curved cylindrical lens array.
Further, in the third embodiment, the optical path non-shortening type front array lens is a single-sided curved cylindrical lens array, and the optical path shortening type rear array lens is constituted by a cylindrical lens array having curved surfaces on both sides, the rear array lens It is preferable that the front curved surface is concave and the rear curved surface is convex.

  The laser irradiation apparatus of the present invention uses the beam homogenizer of various forms described above to uniformize the energy density distribution in the short side direction and the long side direction of the irradiation beam, and the irradiation beam in which the energy density distribution in both directions is uniformed. A stage on which an irradiation surface for projecting is provided, or the energy density distribution in one direction of either the short side direction or the long side direction is made uniform, and the energy density distribution in the remaining other direction is made uniform, and both directions And a stage on which an irradiation surface for projecting an irradiation beam having a uniform energy density distribution is provided.

In the beam homogenizer of the present invention, the principal point position of the lens system is intentionally changed by using a beam homogenizer having various optical path shortening type array lenses composed of a lens system that combines a convex lens and a concave lens. It is possible to shorten the distance between lenses and shorten the optical path length.
Therefore, a rectangular beam spot having a uniform energy distribution, in particular, a linear beam spot can be formed on the irradiation surface by a more compact optical system.
When the beam homogenizer of the present invention is used in a laser irradiation apparatus, the space occupied by the optical system in the apparatus can be reduced, and a laser irradiation apparatus that is smaller and has a smaller footprint can be provided.

In describing the embodiment of the present invention, first, a beam homogenizer using a cylindrical lens array and a cylindrical lens will be described with reference to FIG.
The cylindrical lens array is a plurality of cylindrical lenses arranged in the curvature direction, and has a role of dividing the number of cylindrical lenses into the same number as the number of cylindrical lenses constituting incident light.
As shown in FIG. 1, the focal length of the cylindrical lens array 102 of f _2, a focal length distance between the cylindrical lens array 101 of f ₁ is arranged such that f _2.
Note that f ₁ <f ₂ .
Thereby, the incident light is divided into five.

The interval here is the distance from the second principal point position of the cylindrical lens array 101 to the first principal point position of the cylindrical lens array 102.
The technical meaning of the first principal point and the second principal point will be described later.
The light divided into five by the cylindrical lens arrays 101 and 102 is synthesized by the cylindrical lens 103 having a focal length of f ₃ on the irradiation surface 104 arranged at the position of the distance f ₃ behind the cylindrical lens 103 and has an energy distribution. It is made uniform.
Although FIG. 1 shows an example in which light is divided into five, uniformity increases as the number of divisions increases.

By arranging the optical system as shown in FIG. 1, the apex surface of each cylindrical lens constituting the cylindrical lens array 101 and the irradiation surface 104 are in an optically conjugate positional relationship, and the image on the apex surface is an irradiation surface. 104 is projected.
That is, the irradiation surface 104 is uniformly irradiated by each cylindrical lens constituting the cylindrical lens array 101.
Naturally, the sum of the energy distributions of the beams from all the cylindrical lenses constituting the cylindrical lens array 101 is also uniform.

Therefore, even if light incident on the entire surface of the cylindrical lens array has uneven energy distribution depending on the position and orientation, a beam having a uniform energy distribution on the irradiation surface can be obtained by the beam homogenizer shown in FIG. .
At this time, the length D of the beam spot formed on the irradiation surface 104 is determined by the following formula (1), where d is the width of the cylindrical lens constituting the cylindrical lens array.
D = (f ₃ / f ₂ ) d (1)
Note that the interval between the cylindrical lens array 102 and the cylindrical lens 103 is independent of other parameters and can be freely determined.

As described above, in order to form a linear beam having a uniform energy distribution, it is understood that an optical system as shown in FIG. 1 may be assembled in both the long side direction and the short side direction of the linear beam.
In that case, the short side direction of the linear beam can be made uniform first, and then the long side direction can be made uniform, or vice versa. Therefore, it is preferable to first uniform the energy distribution in the short side direction and then uniformize the energy distribution in the long side direction.

For this reason, when designing a beam homogenizer in the long side direction for forming a linear beam having a very long long side direction as shown in FIG. 4, for example, f ₃ (cylindrical lens) of the formula (1) When the focal length of 406 is reduced, the beam is rapidly extended at a short distance, and it is difficult to sufficiently equalize the energy distribution in the long side direction.
Therefore, it is necessary to secure a distance (distance from the second surface of the cylindrical lens 406 to the irradiation surface) for enlarging the long side direction of the beam spot.
Therefore, it is necessary to increase the focal length of the condensing lens (cylindrical lens 407) in the short side direction.
Further, the width of the beam spot in the short side direction is determined by the above-described equation (1).

When f ₃ (focal length of the cylindrical lens 407) is increased from the equation (1), it is necessary to increase f ₂ (the combined focal length of the cylindrical lens arrays 404a and 404b).
As described above, it can be seen that it is effective to make the optical system compact in order to make the energy distribution in the short side direction uniform in order to make the entire optical system compact.
Therefore, when trying to form a linear beam having a long length in the long side direction, as derived from the equation (1), f ₂ of the optical system that equalizes the energy distribution in the short side direction is reduced. Is required.

In the optical system of FIG. 4, reducing f ₂ (the combined focal length of the cylindrical lens arrays 404a and 404b) means that the second principal point of the lens system composed of the cylindrical lens arrays 403a and 403b and the cylindrical lens arrays 404a and 404b. This is nothing but reducing the distance from the first principal point of the lens system.
Thus, consider the principal point position of the lens.
When light enters one mass-produced lens with a thin lens thickness as listed in the lens manufacturer's catalog, etc., the first principal point and the second principal point of the lens are both in the lens or on the lens surface. Exists.

The first principal point and the second principal point in the lens are as follows.
The lens has two principal points, similar to the focal point, which are the first principal point and the second principal point, and the first principal point is as follows.
A ray that passes through the front (left) focal point (that is, a ray that travels parallel to the optical axis after passing through the lens) is replaced with two refractions that occur on both the front and back sides of the lens when actually passing through the lens. The virtual surface when it is assumed that the refraction is assumed can be actually defined, the virtual surface is called the first principal surface, and the intersection of the surface and the optical axis is called the first principal point.

In other words, when it is assumed that a light ray incident on the lens from the right side parallel to the optical axis is refracted once at a certain imaginary line instead of being refracted twice on both sides of the lens when actually passing through the lens. The virtual surface is called the first principal surface, and the intersection of the surface and the optical axis is called the first principal point.
On the contrary, assuming that the light beam passing through the rear (right) focal point is refracted once at an imaginary line instead of being refracted twice on both the front and back surfaces of the lens when actually passing through the lens. Is called the second principal surface, and the intersection of the surface and the optical axis is called the second principal point.

On the other hand, in the case of a lens system in which a plurality of lenses are combined, the position where the principal point is formed differs greatly depending on the lens curvature and the lens interval, and may be formed outside the lens.
For example, as shown in FIG. 2A, when the first lens 201 is a convex lens and the second lens 202 is a concave lens, the principal point is formed in front of the first lens 201.
On the other hand, as shown in FIG. 2B, when the first lens 203 is a concave lens and the second lens 204 is a convex lens, the principal point is formed behind the second lens.

Therefore, in the case of the lens system shown in FIG. 2A, the position of the second principal point moves to the front of the lens system as compared with the case where one lens is used, and the lens system shown in FIG. In this case, the position of the first principal point moves to the rear of the lens system.
As described above, it has been found that the principal point position can be manipulated by using a lens system including a plurality of lenses.
The above description is a description of the prerequisites for understanding the present invention, and the embodiment of the present invention will be described in detail below based on these matters.

In the following, embodiments of the present invention will be described in detail with respect to embodiments of the beam homogenizer, and an overview of the embodiments of the laser irradiation apparatus will be described.
It goes without saying that the present invention is not limited by these embodiments and is specified by the scope of the claims.
Moreover, it will be easily understood by those skilled in the art that the modes and details can be variously changed without departing from the spirit and scope of the present invention.
Note that in the structures of the present invention described below, the same reference numerals are used in common in different drawings.

First, an embodiment of the beam homogenizer will be described in detail with reference to FIG.
FIG. 3A is a beam homogenizer having the same configuration as that in FIG. 1. In this case, the position of the first principal point Y of the cylindrical lens array 102 is the position of the second principal point X of the cylindrical lens array 101 at the position of A and the position of B. The distance between the second principal point X and the first principal point Y is f ₂ .
On the other hand, FIG. 3B is an application of the lens system of FIGS. 2A and 2B to a beam homogenizer.

A lens system including the cylindrical lens array 301 and the cylindrical lens array 302 is a first lens system (corresponding to an optical path shortening type front array lens), and a lens system including the cylindrical lens array 303 and the cylindrical lens array 304 is a second lens system (optical path). Applicable to shortened rear array lens).
The first lens system, the combined focal length is set (the distance between the first principal point of the second principal point and the cylindrical lens array 302 of the cylindrical lens array 301) f ₁ and so as lens curvature, lens distance As in the lens system shown in FIG. 2A, the light enters the convex lens first and then enters the concave lens.

Thereby, the second principal point position C of the first lens system is formed in front of the cylindrical lens array 301.
Therefore, the first lens system can be moved backward in order to match the second principal point position X of the cylindrical lens array 101 with the second principal point position C of the first lens system.
That is, the optical path length can be shortened by the amount of movement of the second principal point position of the first lens system.

Further, in the second lens system, the lens curvature and the inter-lens distance (distance between the cylindrical lens array 303 and the cylindrical lens array 304) are set so that the combined focal length becomes f _2, and FIG. Similar to the lens system shown, it first enters the concave lens and then enters the convex lens.
As a result, the first principal point position D of the second lens system is formed behind the cylindrical lens array 304.
Therefore, the second lens system can be moved forward in order to match the second principal point position Y of the cylindrical lens array 102 with the first principal point position D of the second lens system.

As described with reference to FIG. 1, there is no particular restriction on the distance between the cylindrical lens array 102 and the cylindrical lens 103, so that the cylindrical lens 305 can be brought closer to the second lens system by the amount of movement of the second lens system.
That is, when the position of the cylindrical lens 305 is fixed, the first lens system and the second lens system can be moved by the amount of movement of the first principal point position of the second lens system. The optical path length can be shortened by the amount of movement of one principal point position.

  In the beam homogenizer shown in FIG. 3B, a synthetic cylindrical lens array is employed for both the front array lens and the rear array lens, which is a preferred embodiment of the present invention. In the beam homogenizer of the invention, only one set of the synthetic cylindrical lens array is required. For example, as shown in FIG. 5 illustrating one embodiment of the laser irradiation apparatus, the front array lens is a single cylindrical lens array, that is, an optical path. A non-shortening array lens may be used.

Further, although not shown, the rear array lens instead of the front array lens may be replaced with one cylindrical lens array, that is, an optical path non-shortening array lens.
In this case as well, since one set of the synthetic cylindrical lens array is adopted, the optical path length can be shortened and the size can be reduced. However, two sets such as the beam homogenizer shown in FIG. If the synthetic cylindrical lens array is adopted, the optical path length can be shortened and the size can be reduced.

Here, the beam homogenizer of the present invention is used for homogenizing the short side direction of the beam, but of course, it can also be used for uniforming the long side direction, and the short side direction and the long side direction can be used. It can also be used when both of them are made uniform.
In the beam homogenizer of FIG. 3B, the beams divided by both the front and rear synthetic cylindrical lens arrays are synthesized by the cylindrical lens 305 arranged immediately thereafter, and the energy distribution is made uniform.

Next, an outline of two types of embodiments of the laser irradiation apparatus will be described with reference to FIGS.
FIG. 4 illustrates a laser irradiation apparatus employing the beam homogenizer of FIG.
That is, the laser irradiation apparatus employs two sets of synthetic cylindrical lens arrays, that is, the front side synthetic cylindrical lens arrays 403a and 403b and the rear side synthetic cylindrical lens arrays 404a and 404b. Reference numerals 403b, 404a, and 404b correspond to the optical path shortening type front array lens and the optical path shortening type rear array lens of the beam homogenizer of the present invention, and this corresponds to the first embodiment.

Further, the short side direction of the beam is divided by these, and the divided beam is condensed (combined) by the cylindrical lens 407, and the energy distribution in the short side direction is made uniform.
Further, cylindrical lens arrays 405a and 405b for dividing the long side direction exist in front of the beam traveling direction of the cylindrical lens 407, and the long side directions of the beams divided by these are synthesized by the cylindrical lens 406 to be uniform. It becomes.

In the laser irradiation apparatus of FIG. 4, the cylindrical lens 407 corresponds to the condensing lens of the beam homogenizer of the present invention.
In FIG. 4, this lens is arranged after the cylindrical lens arrays 405a and 405b and the cylindrical lens 406, which form a beam homogenizer in the long side direction. However, this lens may be arranged in this manner, and of course, the arrangement shown in FIG. Although they are different, they may be arranged in front of the cylindrical lens arrays 405a and 405b.

The laser irradiation apparatus of FIG. 5 illustrates a laser irradiation apparatus of a mode different from the laser irradiation apparatus of FIG. 4, and the beam homogenizer employed therein is the beam homogenizer illustrated in FIG. 1 is replaced with one cylindrical lens array 503, which is a non-synthetic array lens with a non-shortening optical path.
Although changed as described above, in this case as well, since one set of synthetic cylindrical lenses is employed, the optical path length can be shortened and the size can be reduced.
Note that the beam homogenizer employed in the laser irradiation apparatus of FIG. 5 corresponds to the third embodiment.

However, in that case, as compared with the case where a synthetic cylindrical lens array, which is an optical path shortening type array lens, is used for both the front and rear array lenses as in the beam homogenizer shown in FIG. Since it is adopted, the degree of shortening of the optical path is low.
That is, when a synthetic cylindrical lens array, which is an optical path shortening type array lens, is used for both the front and rear array lenses as in the beam homogenizer shown in FIG. 4, the optical path is only applied to the one array lens shown in FIG. The degree of shortening of the optical path is higher than when a synthetic cylindrical lens array, which is a shortened array lens, is employed.
Note that the two types of laser irradiation apparatuses will be described in detail in Examples below.

In the following, embodiments of the present invention will be specifically described with reference to the drawings. However, the present invention is not limited to the embodiments, but is specified by the claims. Nor.
Moreover, it will be easily understood by those skilled in the art that the modes and details can be variously changed without departing from the spirit and scope of the present invention.
Note that in the structures of the present invention described below, the same reference numerals are used in common in different drawings.

FIG. 4 illustrates the optical system employed in the first embodiment, and this embodiment will be described with reference to the side view of FIG.
The side view includes the short side direction of the linear beam spot formed by the optical system on the paper surface.
The laser beam emitted from the XeCl excimer laser oscillator 401 is propagated in the direction of the arrow in FIG.
First, the laser beam is expanded by the spherical lenses 402a and 402b.
This configuration is not necessary when the beam spot emitted from the laser oscillator 401 is sufficiently large.
The laser beam emitted from the laser oscillator is divided in the short side direction by a cylindrical lens array described below.

The long side direction and the short side direction are the same as the direction in which the width of the linear beam spot formed on the irradiation surface 409 is long and the direction in which the width is short as described above.
In addition, the lens surface is a surface on which light is incident as a first surface and an exit surface as a second surface.
The sign of the radius of curvature is positive when the center of curvature is on the light exit side with respect to the lens surface, and negative when the center of curvature is on the incident side with respect to the lens surface.
Further, the lens used in this embodiment is made of synthetic quartz having a high transmittance and laser resistance with respect to a XeCl excimer laser having a wavelength of 308 nm.

The cylindrical lens array 403a is an array of 11 cylindrical lenses having a curved surface having a curvature radius of 146.8 mm, a second surface being flat, a thickness of 5 mm, and a short side width of 4 mm in the curvature direction. In the cylindrical lens array 403b, eleven cylindrical lenses having a flat first surface, a curved surface with a curvature radius of 160 mm, a thickness of 5 mm, and a width of 4 mm in the short side direction are arranged in the curvature direction.
The distance between the second surface of the cylindrical lens array 403a and the first surface of the cylindrical lens array 403b is 85 mm, and the combined focal length of the cylindrical lens array 403a and the cylindrical lens array 403b is 837.5 mm. The second principal point position of the system is formed at a position 162.4 mm ahead of the first surface of the cylindrical lens array 403a.

The cylindrical lens array 404a is an array of 11 cylindrical lenses having a curved surface with a radius of curvature of -262.4 mm, a flat surface of the second surface, a thickness of 5 mm, and a width of 4 mm in the short side in the curvature direction. In the cylindrical lens array 404b, 11 cylindrical lenses having a flat first surface, a curved surface with a curvature radius of −200 mm, a thickness of 5 mm, and a width of 4 mm in the short side direction are arranged in the curvature direction. .
When both cylindrical lenses are arranged at a distance of 60 mm between the second surface of the cylindrical lens array 404a and the first surface of the cylindrical lens array 404b, the combined focal length of the cylindrical lens array 404a and the cylindrical lens array 404b is 1139.8 mm. The first principal point position of the two lens systems is approximately 118 mm behind the second surface of the cylindrical lens array 404b.

The composite focal length (f) and the distance (z) from the second principal point of the second lens to the second principal point of the composite system can be obtained by various known calculation formulas, for example, 2 The composite focal length of the composite lens composed of two lenses can be obtained by the following equation (2) and the above equation (3), where L is the distance between the lens principal points.
1 / f = 1 / f ₁ + 1 / f ₂ −L / f ₁ f ₂ Formula (2)
z = −f ₂ L / (f ₁ + f ₂ −L) Formula (3)

  The distance between the second principal point position of the front side synthetic cylindrical lens array composed of the cylindrical lens array 403a and the cylindrical lens array 403b and the first principal point position of the rear side synthetic cylindrical lens array composed of the cylindrical lens array 404a and the cylindrical lens array 404b. However, the cylindrical lens array 404a is arranged at a position 694.4 mm behind the second surface of the cylindrical lens array 403b so that the combined focal length of the cylindrical lens array 404a and the cylindrical lens array 404b is 1139.8 mm.

  The spot divided by the cylindrical lens arrays 403a, 403b, 404a, and 404b has a curved surface with a curvature radius of 486mm, a second surface that is 1815mm behind the second surface of the cylindrical lens array 404b, a flat surface with a second surface, and a thickness of The light is condensed by the 20 mm cylindrical lens 407, and a surface 410 having a uniform energy distribution with a length of 3.5 mm in the short side direction is formed at a position about 1000 mm rearward from the second surface of the cylindrical lens 407.

As described above, in the cylindrical lens array 403a that is a convex lens and the cylindrical lens array 403b that is a concave lens, the first surface having the same focal length as the combined focal length is curved, the second surface is flat, and the lens thickness is 5 mm. And a cylindrical lens array 404a that is a concave lens and a cylindrical lens array 404b that is a convex lens, the first surface having a focal length that is the same as the combined focal length, the second surface The optical path length can be shortened by about 283.6 mm as compared with a case where the surface is replaced with a cylindrical lens array having a curved surface and a lens thickness of 5 mm.
As described above, the combination of the cylindrical lens arrays 403a, 403b, 404a, 404b and the cylindrical lens 407 is a beam homogenizer in the short side direction, which corresponds to the beam homogenizer of the present invention.

The surface 410 having a uniform energy distribution formed by the beam homogenizer is placed on an irradiation surface 220 mm behind the second surface of the cylindrical lens 408b by a doublet cylindrical lens 408 disposed behind the uniform surface of the energy distribution 1250mm. Project.
That is, the uniform surface 410 and the irradiation surface 409 are in a conjugate position with respect to the doublet cylindrical lens 408.
Thereby, the energy distribution in the short side direction of the linear beam spot is made uniform, and the length in the short side direction is determined.
The doublet cylindrical lens 408 includes a cylindrical lens 408a and a cylindrical lens 408b.

The cylindrical lens 408a is a cylindrical lens having a curved surface with a curvature radius of 125 mm, a second surface with a curvature radius of 77 mm, and a thickness of 10 mm. The cylindrical lens 408b has a curved surface with a curvature radius of 97 mm on the first surface. The surface is a curved lens having a curvature radius of −200 mm and a cylindrical lens having a thickness of 20 mm, and the distance between the second surface of the cylindrical lens 408a and the first surface of the cylindrical lens 408b is 5.5 mm.
Note that a singlet cylindrical lens may be used when the uniformity of the beam spot on the irradiation surface is not so required, or when the F-number (F = lens focal length / incidence pupil diameter) of the doublet cylindrical lens is very large.

Next, the plan view of FIG. 4A will be described.
The plan view includes the long side direction of the linear beam spot formed by the optical system on the paper surface.
The laser beam emitted from the laser oscillator 401 is divided into spots in the long side direction by the cylindrical lens array 405a and the cylindrical lens array 405b.
In the cylindrical lens array 405a, the first surface is a curved surface having a curvature radius of 40 mm, the second surface is a flat surface, the thickness is 3 mm, and the width of the long side direction is 9 mm. Twelve cylindrical lenses are arranged in the curvature direction. In the cylindrical lens array 405b, 12 cylindrical lenses having a flat first surface, a curved surface with a curvature radius of −55 mm, a thickness of 3 mm, and a width of 9 mm in the long side direction are arranged in the curvature direction.

The distance between the second principal point of the cylindrical lens array 405a and the first principal point of the cylindrical lens array 405b is set to be a focal length of 113.3 mm of the cylindrical lens array 405b.
A spot divided by the cylindrical lens arrays 405a and 405b by the cylindrical lens 406 having a first surface disposed flat 82mm behind the second surface of the cylindrical lens array 405b and a second surface having a curvature radius of −2140 mm is an irradiation surface 409. Superimposed on top.
Thereby, the energy distribution in the long side direction of the linear beam spot is made uniform, and the length in the long side direction is determined.

The cylindrical lens 406 can reduce the energy attenuation portion generated at both ends of the linear beam spot in the long side direction.
However, the focal length of the present lens may be remarkably increased due to the configuration of the apparatus. In such a case, the effect of the present lens may be reduced and may not be used.
As described above, the combination of the cylindrical lens arrays 405a and 405b and the cylindrical lens 406 is a beam homogenizer in the long side direction, but this does not correspond to the beam homogenizer of the present invention.

As described above, a linear beam spot having a uniform energy distribution with a length of 700 μm in the short side direction and a length of 300 mm in the long side direction is formed on the irradiation surface 409 by the optical system shown in FIG. Can be formed.
FIG. 7 shows the result of calculation of ray tracing for the optical system shown in FIG. 4 using optical design software.
The vertical axis represents the intensity of the obtained beam spot, and the horizontal axis represents the short side and the long side length of the beam spot.

The laser oscillator combined with the beam homogenizer of the present invention preferably has a wavelength region that has a large output and is well absorbed by the semiconductor film.
When a silicon film is used as the semiconductor film, the wavelength of the laser beam emitted from the laser oscillator to be used is preferably 600 nm or less in consideration of the absorption rate.
Examples of the laser oscillator that emits such a laser beam include an excimer laser, a YAG laser (harmonic), and a glass laser (harmonic).

As a laser oscillator that oscillates a laser beam having a wavelength suitable for crystallization of a silicon film, for example, a YVO ₄ laser (harmonic), a YLF laser (harmonic), an Ar laser, a GdVO ₄ laser (harmonic), Ti : Sapphire laser (harmonic).
The optical system of the present invention may be used in the air, or may be used in a nitrogen or Ar atmosphere in order to suppress breakdown and damage to the lens surface due to laser light having high energy.

The present embodiment is an example of an optical system different from the optical system described above, and is as illustrated in FIG.
In FIG. 5, the part other than the cylindrical lens array forming the homogenizer in the short side direction passes through exactly the same optical path as the optical system shown in FIG. 4 illustrating the first embodiment.
The beam homogenizer shown in the present embodiment will be described along the side view of FIG.
The lens shown in this embodiment is made of synthetic quartz having high transmittance and laser resistance with respect to the XeCl excimer laser.

The laser beam emitted from the laser oscillator is divided in the short side direction by a cylindrical lens array described below.
In the cylindrical lens array 503, 11 cylindrical lenses having a curved surface with a curvature radius of 412.8 mm, a second surface with a flat surface, a thickness of 5 mm, and a short side width of 4 mm are arranged in the curvature direction. .
The second principal point of the cylindrical lens array 503 is formed about 3.6 mm inside the lens from the second surface of the cylindrical lens.

The cylindrical lens array 404a is an array of 11 cylindrical lenses having a curved surface with a radius of curvature of -262.4 mm, a flat surface of the second surface, a thickness of 5 mm, and a width of 4 mm in the short side in the curvature direction. In the cylindrical lens array 404b, 11 cylindrical lenses having a flat first surface, a curved surface with a curvature radius of −200 mm, a thickness of 5 mm, and a width of 4 mm in the short side direction are arranged in the curvature direction. .
The distance between the second surface of the cylindrical lens array 404a and the first surface of the cylindrical lens array 404b is 60 mm, and the combined focal length of the cylindrical lens array 404a and the cylindrical lens array 404b is 1139.8 mm. One principal point position is formed at a position of about 118 mm behind the second surface of the cylindrical lens array 404b.

  The distance between the second principal point of the cylindrical lens array 503 and the position of the first principal point of the lens system including the cylindrical lens array 404a and the cylindrical lens array 404b is the combined focal length of the cylindrical lens array 404a and the cylindrical lens array 404b. The cylindrical lens array 404 a is arranged to be 948.2 mm behind the second surface of the cylindrical lens array 503 so as to be 1139.8 mm.

The spot divided by the cylindrical lens arrays 503, 404a and 404b is a curved surface having a radius of curvature of 486 mm, a second surface of which is 1815 mm behind the second surface of the cylindrical lens array 404b, a plane having a thickness of 20 mm, and a thickness of 20 mm. Condensed by the lens 407, a uniform surface with an energy distribution having a length of 3.6 mm in the short side direction is formed at a position 1000 mm behind the second surface of the cylindrical lens 405.
Compared with the case where the cylindrical lens array 404a which is a concave lens and the cylindrical lens array 404b which is a convex lens are replaced with a cylindrical lens array of one convex lens having the same focal length as the combined focal length, the optical path length is about 119. It can be shortened by 6 mm.

In this embodiment, an example of an optical system different from the optical system described above will be given and described with reference to FIG.
As in the other examples, the lens shown in this example is made of synthetic quartz having a high transmittance and laser resistance with respect to the XeCl excimer laser. However, the lens material is appropriately selected according to the laser to be used and the wavelength region. It is also possible to select.
FIG. 8A shows only the optical system that equalizes the energy density distribution in the short side direction of the beam in the optical system described in FIG. 4B.
Note that the optical system for making the energy density distribution in the long side direction uniform is used in the same manner as in the other embodiments.

The cylindrical lens arrays 403a and 403b used here correspond to an optical path shortening type front array lens in the beam homogenizer of the present invention, and this is used as a cylindrical lens array 801 having a curvature on both the first surface and the second surface. The case where it changed is shown in FIG.8 (b).
The cylindrical lens array 801 has a first surface curvature of 47.8 mm, a second surface curvature of 50.5 mm, a thickness of 10 mm, and a focal length of 832.8 mm.
The second principal point of the cylindrical lens array 801 is formed at a position 56.9 mm away from the second surface toward the first surface, that is, 46.9 mm away from the first surface.

The distance between the second principal point of the cylindrical lens array 801 and the first principal point position of a lens system (hereinafter referred to as a second lens system) composed of the cylindrical lens array 404a and the cylindrical lens 404b is the second lens system. The cylindrical lens array 801 is arranged so as to have a combined focal length of 1139.8 mm.
That is, the distance between the second surface of the cylindrical lens array 801 and the first surface of the cylindrical lens array 404a is 894.9 mm.

Compared to the case where the cylindrical lens array 801 having curved surfaces on both sides is replaced with a cylindrical lens array of one plano-convex lens having the same focal length as that of the cylindrical lens array 801 (the first surface is curved and has a thickness of 5 mm). Then, the optical system shown in FIG. 8 can shorten the optical path length by 48.5 mm.
In this embodiment, an example in which the energy density distribution in the short side direction is made uniform has been shown, but it may be used for making the energy density distribution in the long side direction uniform, and the energy in the long side direction and the short side direction. It may be used to make the density distribution uniform.

As described above, in this embodiment, when the cylindrical lens array 403a and the cylindrical lens array 403b are replaced with a single cylindrical lens array 801 having curved surfaces on both sides, the optical path is compared with the case where one plano-convex lens is used. It has the effect of shortening the length.
The same effect can be obtained by replacing the cylindrical lens array 404a and the cylindrical lens array 404b with a single cylindrical lens array 801 having curved surfaces on both sides.

Further, the cylindrical lens array 403a and the cylindrical lens array 403b are replaced with a single cylindrical lens array 801 having curved surfaces on both sides, and the cylindrical lens array 404a and the cylindrical lens array 404b are replaced with one cylindrical lens array having curved surfaces on both sides. In this case, it is possible to obtain an optical path shortening effect by replacing both the front and rear lens arrays.
That is, in that case, an optical path shortening effect can be achieved when the optical path shortening front array lens and the optical path shortening rear array lens are employed.

In this embodiment, adjustment of the beam width using the optical system described in the other embodiments such as the first embodiment will be described with reference to FIG.
The lens shown in this embodiment is made of synthetic quartz having a high transmittance and laser resistance with respect to the XeCl excimer laser, but it is also possible to select a lens material as appropriate in accordance with the laser to be used and the wavelength region. .
FIG. 9A shows only the optical system related to the short side direction of the beam in the optical system described with reference to FIG.
The optical system related to the long side direction of the beam may be used in the same manner as in the other embodiments.
Here, the point 410 having a uniform energy density distribution is the focal point of the cylindrical lens 407.

Beam width D is formed at this point, the cylindrical lens array 403a, 403b, 404a, f ₄₀₄ individual width in the short side direction d of the lens, the combined focal length of the cylindrical lens array 404a and 404b having the 404b, cylindrical When the focal length of the lens 407 and f _407, can be expressed by the following equation (4).
D = (f ₄₀₇ / f ₄₀₄ ) × d Equation (4)
By substituting f ₄₀₄ = 1139.8 mm, f ₄₀₇ = 1000.8 mm, and d = 4 mm into the above equation (4), D = 3.5 mm is obtained.
By projecting this beam with a lens having a magnification of 5, a beam having a width of 700 μm can be formed.

Here, as shown in FIG. 9B, when it is desired to change the width of the beam formed at the point 410 having a uniform energy density distribution, the second surface of the cylindrical lens array 404b is changed from the second surface of the cylindrical lens array 404a. This can be realized by changing the distance to one surface.
However, if the distance between the two lenses is changed, the position of the first principal point of the cylindrical lens arrays 404a and 404b (second lens system) moves.
Therefore, the distance from the second principal point position of the lens system including the cylindrical lens arrays 403a and 403b (hereinafter referred to as the first lens system) to the first principal point position of the second lens system is _f404. Need to move the other lens.

For example, when the width of the beam formed by the optical system in FIG. 9A is changed, the cylindrical lens array 404a is moved by +15.5 mm in the z direction in FIG. 9 and the second surface of the cylindrical lens array 404a and the cylindrical surface are moved. The distance between the first surface of the lens array 404b is reduced from 60 mm to 44.5 mm.
By this operation, the composite focal length of the second lens system is changed from 1139.8 mm to 1238.2 mm.
The z axis is an axis parallel to the optical axis, and the direction in which the light travels is positive (+).

The position of the first principal point of the second lens system moves with the movement of the cylindrical lens array 404a.
The whole first lens system is z in FIG. 9 so that the distance between the second principal point position of the first lens system and the first principal point position of the second lens system is equal to the combined focal length of the second lens system. Move 113.6 mm in the axial direction.
Moreover, by moving the cylindrical lens array 404a, the value of the focal length f ₄₀₄ becomes 1238.2Mm.

As described above, as confirmed by substituting into Equation 1, a beam having a width of 3.23 mm is formed at the point 410 having a uniform energy density distribution.
Furthermore, a 646 μm beam can be formed by projecting this beam onto another surface with a lens having a magnification of 5.
As described above, when the beam homogenizer of the present invention is used, the width of the beam to be formed can be changed by moving the position of the lens.
Although this embodiment has been described using the optical system of Embodiment 1, this embodiment can be combined with other embodiments.

In this embodiment, an example is shown in which a fly-eye lens (also referred to as an integrator) is used as a lens for making the beam uniform and shortening the optical path length.
A fly-eye lens is an aggregate of lenses having a compound eye lens structure, and is configured by arranging one type of lens (for example, a rod lens) element having curvature on both surfaces, and an incident side lens element group. Some are configured by arranging the exit-side lenses to face each other.
The function of the fly-eye lens is to project the light incident on the lens surface on the incident side onto the irradiation surface by passing through the exit side of the lens.

When each projected light is added on the irradiation surface, the intensity distribution on the irradiation surface becomes uniform.
In addition, the shape of the beam spot on the irradiation surface reflects the shape of the lens element.
In this embodiment, an example in which the shape of each lens constituting the fly-eye lens is a square is shown, but the present invention is not limited to this, and the same applies to the case where the shape of the lens constituting the fly-eye lens is a rectangle or a triangle. Can be used.

As in the other examples, the lens shown in this example is made of synthetic quartz having a high transmittance and laser resistance to the XeCl excimer laser. However, the lens material is appropriately selected according to the laser to be used and the wavelength region. It is also possible to select.
FIG. 10 is a diagram showing an optical system when a homogenizer in the second direction orthogonal to the first direction and the first direction of the beam is configured by a fly-eye lens.
Although the plan view is shown in FIG. 10 (a) and the side view is shown in FIG. 10 (b), the shape of each lens constituting the fly-eye lens is square in this embodiment, so the first side direction of the beam And the second direction are made uniform in the same way.

The laser beam emitted from the XeCl excimer laser oscillator 1001 is propagated in the direction of the arrow in FIG.
First, the laser beam is expanded by spherical lenses 1002a and 1002b.
This configuration is not necessary when the beam diameter of the laser emitted from the laser oscillator 1001 is large.
A laser beam emitted from the laser oscillator 1001 is divided into spots in both the first direction and the second direction by a fly-eye lens described below.

As shown in FIG. 11A, the fly-eye lens 1003a has a curved surface with a curvature radius of 146.8 mm, a second surface that is flat, a thickness of 5 mm, and a length in the first direction and the second direction. Both 11 mm spherical lenses are arranged in the first direction and 11 in the second direction as shown in FIG. 11B.
The fly-eye lens 1003b is a spherical lens whose first surface is a flat surface, whose second surface is a curved surface with a curvature radius of 160 mm, whose thickness is 5 mm, and whose length in both the first direction and the second direction is 4 mm. As shown in b), 11 are arranged in the first direction and 11 are arranged in the second direction.

The distance between the second surface of the fly-eye lens 1003a and the first surface of the fly-eye lens 1003b is 85 mm, and the combined focal length of the fly-eye lens 1003a and the fly-eye lens 1003b is 837.5 mm. The second principal point position of the system is formed at a position 162.4 mm ahead of the first surface of the fly-eye lens 1003a.
As shown in FIG. 11C, the fly-eye lens 1004a has a curved surface with a curvature radius of 262.4 mm, a second surface that is flat, a thickness of 5 mm, and a length in the first direction and the second direction. 11 spherical lenses of 4 mm are arranged in the first direction and 11 are arranged in the second direction. The fly-eye lens 1004b has a flat first surface, a curved surface with a curvature radius of -200 mm, and a thickness of 5 mm. 11 spherical lenses each having a length of 4 mm in both the first direction and the second direction are arranged in the first direction and 11 in the second direction.

When the fly-eye lenses 1004a and 1004b are arranged so that the distance between the second surface of the fly-eye lens 1004a and the first surface of the fly-eye lens 1004b is 60 mm, the fly-eye lens 1004a and the fly-eye lens 1004b The combined focal length is 139.8 mm, and the position of the first principal point of the two lens systems is about 118 mm behind the second surface of the fly-eye lens 1004b.
In the composite lens system composed of two lenses, the focal length f and the distance z from the position of the second principal point of the second lens to the position of the second principal point of the composite lens system are the above-described equations (2), respectively. And (3).

The distance between the second principal point position of the front compound lens composed of the fly eye lens 1003a and the fly eye lens 1003b and the first principal point of the rear compound lens composed of the fly eye lens 1004a and the fly eye lens 1004b is the fly eye lens. The fly-eye lens 1004a is disposed at a position 694.4 mm behind the second surface of the fly-eye lens 1003b so that the combined focal length of 1004a and the fly-eye lens 1004b is 1139.8 mm.
Spots divided by the fly-eye lenses 1003a, 1003b, 1004a, and 1004b are arranged 1815 mm behind the fly-eye lens 1004b second surface, the first surface is a curved surface with a radius of curvature of 486 mm, the second surface is flat, and the thickness Is collected by a spherical lens 1005 having a diameter of 20 mm, and a square surface 1008 having a uniform energy distribution of 3.5 mm on a side is formed at a position about 1000 mm behind the second surface of the spherical lens 1005.

Here, the fly-eye lens 1003a and the fly-eye lens 1003b are replaced with a single fly-eye lens having the same focal length as the combined focal length, the first surface is curved, the second surface is flat, and the lens thickness is 5 mm. Also, the fly-eye lens 1004a and the fly-eye lens 1004b are replaced with a single fly-eye lens having the same focal length as the combined focal length, the first surface is flat, the second surface is curved, and the lens thickness is 5 mm. Compared with the case of the optical path length, the optical path length can be shortened by about 283.6 mm.
The beam eye homogenizer of the present invention is a combination of the fly-eye lenses 1003a, 1003b, 1004a, 1004b and the spherical lens 1005.

An irradiation surface located 220 mm behind the second surface of the spherical lens 1006b by a doublet lens 1006 in which the surface 1008 having a uniform energy distribution formed by the beam homogenizer is disposed 1250 mm behind the surface 1008 with the uniform energy distribution. Project to 1007.
That is, the surface 1008 with uniform energy distribution and the irradiation surface 1007 are in a conjugate position with respect to the doublet lens 1006.
Thereby, the energy distribution in the first direction and the second direction of the square beam spot is made uniform, and the lengths in both directions are determined.
The doublet lens 1006 includes a spherical lens 1006a and a spherical lens 1006b.

The spherical lens 1006a has a curved surface with a curvature radius of 125 mm, a second surface with a curvature radius of 77 mm, and a spherical lens with a thickness of 10 mm. The spherical lens 1006b has a curved surface with a curvature radius of 97 mm on the first surface, and a second surface. The surface is a curved surface having a curvature radius of −200 mm and a spherical lens having a thickness of 20 mm. The distance between the second surface of the spherical lens 1006a and the first surface of the spherical lens 1006b is 5.5 mm.
In the case where the uniformity of the beam spot is not so required on the irradiation surface 1007, or when the F value (F = lens focal length / incidence pupil diameter) of the doublet lens is very large, a singlet (single) lens is used. Also good.

As described above, the optical system shown in FIG. 10 can form a square beam spot having a uniform energy distribution with a side of 700 μm on the irradiation surface 1007.
The laser oscillator combined with the beam homogenizer of the present invention preferably has a large output and a wavelength region that is well absorbed by the semiconductor film. When a silicon film is used as the semiconductor film, the wavelength of the laser beam emitted from the laser oscillator to be used is preferably 600 nm or less in consideration of the absorption rate.

Examples of the laser oscillator that emits such a laser beam include an excimer laser, a YAG laser (harmonic), a glass laser (harmonic), a YVO ₄ laser (harmonic), a YLF laser (harmonic), an Ar laser, and a GdVO _4. There are laser (harmonic) and titanium / sapphire laser (harmonic).
In addition, you may use not only the laser mentioned here but another laser.
Further, the laser may be converted into a harmonic using a known nonlinear optical element so as to have a wavelength of 600 nm or less.
The optical system of the present invention may be used in the air, or may be used in a nitrogen or argon atmosphere in order to suppress breakdown and damage to the lens surface caused by high energy laser light.

In the present embodiment, an example is shown in which a spherical plano-convex lens and a spherical plano-concave lens are used as elements constituting a fly-eye lens, but a lens having a curved surface on both the first surface and the second surface may be used as a component. Alternatively, lenses having different curvatures in the first direction and the second direction may be used.
When lenses having different curvatures in the first direction and the second direction are used, when the condensing lens is a spherical lens, the formed beam spot is rectangular.
If it is desired to form a rectangular beam spot having an aspect ratio larger than 1, the condensing lens may be a toric lens or a cross cylindrical lens having different curvatures in the first direction and the second direction, instead of a spherical lens. A cylindrical lens that collects light only in the first direction and a cylindrical lens that collects light only in the second direction may be disposed.

Further, in this embodiment, an example is shown in which a fly-eye lens having a curvature on one side is used, but the fly-eye lenses 1003a and 1003b have a curvature on both the first surface and the second surface as in the third embodiment. It is also possible to change to a fly-eye lens.
In this case as well, the optical path length is shortened compared to the case where the fly-eye lens having curvatures on both sides is replaced with a single plano-convex lens having the same focal length as that of the fly-eye lens, as in the third embodiment. Is possible.
Furthermore, even if the fly-eye lenses 1004a and 1004b are changed to fly-eye lenses having curvatures on both the first surface and the second surface, the same effect can be obtained.

In addition, the fly-eye lenses 1003a and 1003b can be replaced with one fly-eye lens having curvature on both sides, and the fly-eye lenses 1004a and 1004b can be replaced with one fly-eye lens having curvatures on both sides. The optical path shortening effect can be obtained by replacing both the front and rear lenses.
That is, in that case, an optical path shortening effect can be achieved when the optical path shortening front array lens and the optical path shortening rear array lens are employed.

In this embodiment, a method for simultaneously manufacturing an n-channel TFT and a p-channel TFT using the laser irradiation apparatus of the present invention over the same substrate will be described with reference to FIGS.
A metal layer 1202 is formed on the substrate 1201, and an adhesive body 1203 is formed thereon.
In this embodiment, a glass substrate is used as the substrate 1201, and a metal material containing tungsten (W) as a main component is used for the metal layer 1202.
Note that the adhesive body 1203 is processed and formed into a desired shape so as to be disposed between TFTs to be formed later.

Next, an oxide layer 1204 that also functions as a base insulating film is formed over the metal layer 1202 and the adhesive body 1203.
In this embodiment, a silicon oxynitride film (composition ratio: Si = 32%, O = 59%, N = 7%, H, H) formed from a plasma CVD method using a film forming temperature of 300 ° C., a source gas SiH ₄ and N ₂ O = 2%) to a thickness of 100 nm, an oxide layer 1204 is formed.

Further, a semiconductor layer having an amorphous structure (here, an amorphous silicon layer) is formed with a thickness of 54 nm by a plasma CVD method and continuously with a film forming gas SiH ₄ without being exposed to the atmosphere. .
This amorphous silicon layer contains hydrogen, and can be peeled off in the oxide layer or at the interface by physical means by diffusing hydrogen by a subsequent heat treatment.
Thereafter, a nickel acetate solution containing 10 ppm of nickel in terms of weight is applied by a spinner method. In this case, a method of spraying nickel element over the entire surface by a sputtering method may be used instead of the application method.

Next, heat treatment is performed to crystallize to form a semiconductor film having a crystal structure (here, a polysilicon layer). Here, after heat treatment for dehydrogenation (500 ° C., 1 hour), crystallization is performed. Heat treatment (550 ° C., 4 hours) is performed to obtain a silicon film having a crystal structure.
The heat treatment for dehydrogenation (500 ° C., 1 hour) also serves as heat treatment for diffusing hydrogen contained in the amorphous silicon film to the interface between the metal layer 1202 and the oxide layer 1204. Although a crystallization technique using nickel as a metal element for promoting crystallization of silicon is used here, other known crystallization techniques such as a solid phase growth method and a laser crystallization method may be used.

Next, after removing the oxide film on the surface of the silicon film having a crystal structure with dilute hydrofluoric acid or the like, laser light (XeCl: wavelength 308 nm) for increasing the crystallization rate and repairing defects left in the crystal grains Irradiation is performed in air or in an oxygen atmosphere.
In this embodiment, the laser irradiation apparatus used in Embodiment 2 is used, which is as shown in FIG.

In FIG. 5, the part other than the cylindrical lens array that forms the homogenizer in the short side direction passes through the same optical path as the optical system shown in FIG. 4 illustrating the first embodiment.
The beam homogenizer shown in the present embodiment will be described along the side view of FIG.
The lens shown in this embodiment is made of synthetic quartz having a high transmittance and laser resistance with respect to the XeCl excimer laser. However, when other lasers are used, the lens material can be appropriately changed. For example, a lens made of a material such as a polysilicate crown glass, quartz, or sapphire can be used.

The laser beam emitted from the laser oscillator is divided in the short side direction by a cylindrical lens array described below.
In the cylindrical lens array 503, 11 cylindrical lenses having a curved surface with a curvature radius of 412.8 mm, a second surface with a flat surface, a thickness of 5 mm, and a short side width of 4 mm are arranged in the curvature direction. .
The second principal point of the cylindrical lens array 503 is formed about 3.6 mm inside the lens from the second surface of the cylindrical lens.

The cylindrical lens array 404a is an array of 11 cylindrical lenses having a curved surface with a radius of curvature of -262.4 mm, a flat surface of the second surface, a thickness of 5 mm, and a width of 4 mm in the short side in the curvature direction. In the cylindrical lens array 404b, 11 cylindrical lenses having a flat first surface, a curved surface with a curvature radius of −200 mm, a thickness of 5 mm, and a width of 4 mm in the short side direction are arranged in the curvature direction. .
The distance between the second surface of the cylindrical lens array 404a and the first surface of the cylindrical lens array 404b is 60 mm, and the combined focal length of the cylindrical lens array 404a and the cylindrical lens array 404b is 1139.8 mm. One principal point position is formed at a position of about 118 mm behind the second surface of the cylindrical lens array 404b.

  The distance between the second principal point of the cylindrical lens array 503 and the position of the first principal point of the lens system including the cylindrical lens array 404a and the cylindrical lens array 404b is the combined focal length of the cylindrical lens array 404a and the cylindrical lens array 404b. The cylindrical lens array 404 a is arranged to be 948.2 mm behind the second surface of the cylindrical lens array 503 so as to be 1139.8 mm.

  The spot divided by the cylindrical lens arrays 503, 404a and 404b is a curved surface having a radius of curvature of 486 mm, a second surface of which is 1815 mm behind the second surface of the cylindrical lens array 404b, a plane having a thickness of 20 mm, and a thickness of 20 mm. Condensed by the lens 407, a uniform surface with an energy distribution having a length of 3.6 mm in the short side direction is formed at a position 1000 mm behind the second surface of the cylindrical lens 405.

As described above, in the sixth embodiment, the cylindrical lens array 404a that is a concave lens and the cylindrical lens array 404b that is a convex lens are replaced with a cylindrical lens array of a single convex lens having the same focal length as the combined focal length. Compared to the case, the optical path length in the short side direction can be shortened by about 119.6 mm.
Although the above description relates to the uniform energy distribution in the short side direction and the shortening of the optical path length, the uniform energy distribution can also be performed in the long side direction.

The equalization of the energy distribution in the long side direction is performed by the cylindrical lenses 405a and 405b, and this point is common to the laser irradiation apparatuses shown in FIGS.
The specific contents are described in detail in the description of the first embodiment using the laser irradiation apparatus illustrated in FIG. 4, and the same can be adopted in the sixth embodiment.

As the laser light used for the laser irradiation, excimer laser light having a wavelength of 400 nm or less, and second and third harmonics of a YAG laser are used.
About the laser beam, using a pulse laser beam with a repetition frequency of about 10 to 1000 Hz, condensing the laser beam to 100 to 500 mJ / cm ² with an optical system, and irradiating with an overlap rate of 90 to 95%, The surface of the silicon film may be scanned, but here, laser light irradiation is performed in the atmosphere at a repetition frequency of 30 Hz and an energy density of 470 mJ / cm ² .

Further, since the laser beam irradiation is performed in the air or in an oxygen atmosphere, an oxide film is formed on the surface.
Note that although an example using a pulsed laser is shown here, a continuous wave laser may be used, and in order to obtain a crystal having a large grain size when an amorphous semiconductor film is crystallized, continuous wave is possible. It is preferable to apply a second to fourth harmonic of the fundamental wave using a solid-state laser.
Typically, a second harmonic (532 nm) or a third harmonic (355 nm) of an Nd: YVO ₄ laser (fundamental wave 1064 nm) may be applied.
In the case of using a continuous wave laser, laser light emitted from a continuous wave YVO ₄ laser having an output of 10 W is converted into a harmonic by a non-linear optical element.

Further, there is a method in which a YVO ₄ crystal and a nonlinear optical element are placed in a resonator to emit harmonics. Preferably, an optical system is used to form a laser beam having a rectangular or elliptical shape on the irradiation surface, and the target is covered. Irradiate the treatment body.
Energy density in that case 0.01 to 100 MW / cm ² about (preferably 0.1 to 10 MW / cm ²⁾ is required, relatively semiconductor to the laser light at a speed of about 10 to 2000 cm / s Irradiation may be performed by moving the film.
Note that the laser is not limited to the laser described above, and other lasers may be used.

Thereafter, in addition to the oxide film formed by the laser beam irradiation, the surface is treated with ozone water for 120 seconds to form a barrier layer made of an oxide film having a total thickness of 1 to 5 nm.
In this embodiment, ozone water is used to form the barrier layer. However, the surface of the semiconductor film having a crystal structure is formed by a method of oxidizing the surface of the semiconductor film having a crystal structure by irradiation with ultraviolet rays in an oxygen atmosphere or by oxygen plasma treatment. The barrier layer may be formed by depositing an oxide film of about 1 to 10 nm by an oxidation method, a plasma CVD method, a sputtering method, an evaporation method, or the like.
Further, the oxide film formed by laser light irradiation may be removed before forming the barrier layer.

Next, an amorphous silicon film containing an argon element serving as a gettering site is formed with a thickness of 10 to 400 nm, here 100 nm, over the barrier layer by a sputtering method.
In this embodiment, an amorphous silicon film containing an argon element is formed in an atmosphere containing argon using a silicon target. However, when an amorphous silicon film containing an argon element is formed using a plasma CVD method, The film forming conditions are as follows: the flow ratio of monosilane to argon (SiH ₄ : Ar) is 1:99, the film forming pressure is 6.665 Pa (0.05 Torr), the RF power density is 0.087 W / cm ² , The film forming temperature is 350 ° C.

Further, gettering is performed by placing in a furnace heated to 650 ° C. for 3 minutes to reduce the nickel concentration in the semiconductor film having a crystal structure.
A lamp annealing apparatus may be used instead of the furnace.
Thereafter, the amorphous silicon film containing an argon element as a gettering site is selectively removed using the barrier layer as an etching stopper, and then the barrier layer is selectively removed with dilute hydrofluoric acid.
Note that during gettering, nickel tends to move to a region with a high oxygen concentration, and thus it is desirable to remove the barrier layer made of an oxide film after gettering.

Next, after forming a thin oxide film with ozone water on the surface of the obtained silicon film having a crystal structure (also called a polysilicon film), a mask made of resist is formed and etched into a desired shape to form islands. The separated semiconductor layers 1205 and 1206 are formed.
After the semiconductor layers 1205 and 1206 are formed, the resist mask is removed (FIG. 12A).
Thereafter, the oxide film is removed with an etchant containing hydrofluoric acid, and at the same time, the surface of the silicon film (semiconductor layers 1205 and 1206) is washed, and then an insulating film containing silicon as a main component to be the gate insulating film 1207 is formed. In the example, a silicon oxide film is formed with a thickness of 115 nm by plasma CVD (FIG. 12B).

Further, a first conductive film 1208 with a thickness of 20 to 100 nm and a second conductive film 1209 with a thickness of 100 to 400 nm are stacked over the gate insulating film 1207.
In this embodiment, a tantalum nitride film with a thickness of 50 nm to be the first conductive film 1208 and a tungsten film with a thickness of 370 nm to be the second conductive film 1209 are sequentially stacked over the gate insulating film 1207.

Note that as a conductive material for forming the first conductive film 1208 and the second conductive film 1209, an element selected from Ta, tungsten, Ti, Mo, Al, and Cu, or an alloy material containing the element as a main component is used. Alternatively, a compound material can be used.
At that time, as the first conductive film 1208 and the second conductive film 1209, a semiconductor film typified by a polycrystalline silicon film doped with an impurity element such as phosphorus, or an AgPdCu alloy may be used.

Further, the present invention is not limited to the two-layer structure. For example, a three-layer structure in which a 50 nm-thickness tungsten film, a 500 nm-thickness aluminum and silicon alloy (Al-Si) film, and a 30 nm-thickness titanium nitride film are sequentially stacked. In this case, tungsten nitride instead of tungsten of the first conductive film, and aluminum / titanium alloy film (Al—Si) instead of the aluminum and silicon alloy (Al—Si) film of the second conductive film may be used. Ti), a titanium film may be used in place of the titanium nitride film of the third conductive film.
A single layer structure may be used.

Next, as shown in FIG. 12C, masks 1210 and 1211 made of resist are formed by a light exposure process, and a first etching process is performed to form gate electrodes and wirings. The processing is performed under the first and second etching conditions.
As an etching gas at that time, a chlorine-based gas typified by Cl ₂ , BCl ₃ , SiCl ₄ , CCl ₄ or the like, a fluorine-based gas typified by CF ₄ , SF ₆ , NF _3, or the like, or O ₂ is used. It can be used as appropriate.

  For the etching, an ICP (Inductively Coupled Plasma) etching method is preferably used, and the ICP etching method is used to apply etching conditions (the amount of power applied to the coil-type electrode and the electrode on the substrate side). The film can be etched into a desired taper shape by appropriately adjusting the amount of electric power, electrode temperature on the substrate side, and the like.

In this embodiment, 150 W of RF (13.56 MHz) power is also applied to the substrate side (sample stage), and a substantially negative self-bias voltage is applied.
The electrode area size on the substrate side is 12.5 cm × 2.5 cm, and the coil-type electrode area size (here, a quartz disk provided with a coil) is a disk having a diameter of 25 cm. The tungsten film is etched under this first etching condition so that the end portion of the first conductive layer is tapered.

The etching rate for tungsten under the first etching conditions is 200.39 nm / min, the etching rate for tantalum nitride is 80.32 nm / min, and the selectivity of tungsten to tantalum nitride is about 2.5.
Further, the taper angle of tungsten is about 26 ° depending on the first etching condition.

Thereafter, the resist masks 1210 and 1211 are not removed and the second etching conditions are changed, CF ₄ and Cl ₂ are used as etching gases, and the respective gas flow ratios are set to 30/30 (sccm). Etching was performed for about 30 seconds by applying 500 W of RF (13.56 MHz) power to the coil-type electrode at a pressure of 1 Pa to generate plasma.
20 W RF (13.56 MHz) power is also applied to the substrate side (sample stage), and a substantially negative self-bias voltage is applied.

Under the second etching condition in which CF ₄ and Cl ₂ are mixed, the tungsten film and the tantalum nitride film are etched to the same extent.
The etching rate for tungsten under the second etching condition is 58.97 nm / min, and the etching rate for tantalum nitride is 66.43 nm / min.
Note that in order to perform etching without leaving a residue on the gate insulating film, it is preferable to increase the etching time at a rate of about 10 to 20%.

In the first etching process, the shape of the mask made of resist is made suitable, and the end portions of the first conductive layer and the second conductive layer are tapered due to the effect of the bias voltage applied to the substrate side. Thus, the angle of the tapered portion may be 15 to 45 °.
Thus, the first shape conductive layer 1212 is formed from the first conductive layer 1212a and the second conductive layer 1212b by the first etching treatment, and the first conductive layer 1213a and the second conductive layer 1213b are A conductive layer 1213 having a shape of 1 is formed.
The insulating film 1207 to be a gate insulating film is etched by about 10 to 20 nm, and becomes a gate insulating film 1207 in which a region not covered with the first shape conductive layers 1212 and 1213 is thinned.

Next, as shown in FIG. 12D, second-shaped conductive layers 1214 and 1215 are formed by a second etching process without removing the resist mask.
Here, SF ₆ , Cl _2, and O ₂ are used as the etching gas, the respective gas flow ratios are 24:12:24 (sccm), and 700 W of RF ( 13.56 MHz) Electric power is applied to generate plasma, and etching is performed for 25 seconds.
10 W RF (13.56 MHz) power is also applied to the substrate side (sample stage), and a substantially negative self-bias voltage is applied.

The etching rate for tungsten in the second etching process is 227.3 nm / min, the etching rate for tantalum nitride is 32.1 nm / min, the selectivity of tungsten to tantalum nitride is 7.1, and the gate insulating film 1211 is formed. The etching rate with respect to SiON is 33.7 nm / min, and the selection ratio of tungsten with respect to SiON is 6.83.
In this way, when SF ₆ is used as the etching gas, since the selectivity with respect to the gate insulating film 1211 is high, the film loss can be suppressed, and the film thickness of the gate insulating film 1207 in this embodiment is about 8 nm.

By this second etching treatment, the taper angle of tungsten can be set to 70 °, and the second conductive layers 1214b and 1215b are formed.
At this time, the first conductive layer is hardly etched and becomes the first conductive layers 1214a and 1215a.
Note that the first conductive layers 1214a and 1215a are approximately the same size as the first conductive layers 1212a and 1213a.
Actually, the width of the first conductive layer may be about 0.3 μm, that is, the entire line width may be receded by about 0.6 μm as compared with that before the second etching process, but the size is hardly changed.

In place of the two-layer structure, a three-layer structure in which a 50-nm-thick tungsten film, a 500-nm-thick aluminum and silicon alloy (Al-Si) film, and a 30-nm-thick titanium nitride film are sequentially stacked, As the first etching condition in the first etching process, BCl ₃ , Cl _2, and O ₂ are used as source gases, the respective gas flow ratios are set to 65: 10: 5 (sccm), and the substrate side (sample stage) ) 300W RF (13.56MHz) power is applied to the coil-type electrode at a pressure of 1.2Pa and 450W RF (13.56MHz) power is generated to generate plasma and perform etching for 117 seconds. Just do it.

As the second etching condition in the first etching process, CF ₄ , Cl _2, and O ₂ are used, the gas flow ratio is 25:25:10 (sccm), and the substrate side (sample stage) is set. If 20W RF (13.56MHz) power is applied, 500W RF (13.56MHz) power is applied to the coil-type electrode at a pressure of 1Pa, plasma is generated, and etching is performed for about 30 seconds. Good.
Further, BCl ₃ and Cl ₂ are used for the second etching process, the respective gas flow ratios are set to 20:60 (sccm), and 100 W of RF (13.56 MHz) power is input to the substrate side (sample stage). Then, etching may be performed by generating 600 W of RF (13.56 MHz) power to the coil-type electrode at a pressure of 1.2 Pa to generate plasma.

Next, after removing the resist masks 1210 and 1211, a resist mask 1218 is formed as shown in FIG. 13A, and a first doping process is performed.
The doping process may be performed by ion doping or ion implantation.
Note that the mask 1218 is a mask for protecting a semiconductor film forming a p-channel TFT and a peripheral region thereof.

The condition of the ion doping method in the first doping treatment is that phosphorus (P) is doped with a dose amount of 1.5 × 10 ¹⁵ atoms / cm ² and an acceleration voltage of 60 to 100 keV.
Note that phosphorus (P) or arsenic (As) can be typically used as the impurity element imparting n-type conductivity.
Here, impurity regions are formed in each semiconductor layer in a self-aligned manner using the second conductive layers 1214b and 1215b as masks, but of course, they are not added to the regions covered with the mask 1218.
Thus, a first impurity region 1219 and a second impurity region 1220 are formed.
An impurity element imparting n-type conductivity is added to the first impurity region 1219 in a concentration range of 1 × 10 ²⁰ to 1 × 10 ²¹ / cm ³ , but here, the first impurity region 1219 has the same concentration range as the first impurity region. The region is also called an n ⁺ region.

The second impurity region 1220 is formed at a lower concentration than the first impurity region 1219 by the first conductive layer 1215a and imparts n-type in a concentration range of 1 × 10 ¹⁸ to 1 × 10 ¹⁹ / cm ^3. Impurity elements to be added are added.
Note that the second impurity region 1220 has a concentration gradient in which the impurity concentration increases toward the end of the tapered portion because doping is performed by passing the portion of the first conductive layer 1215a having a tapered shape. ing.
Here, a region having the same concentration range as second impurity region 1220 is also referred to as an n ⁻ region.

Next, after the resist mask 1218 is removed, a resist mask 1221 is newly formed, and a second doping process is performed as shown in FIG.
The doping process may be performed by ion doping or ion implantation.
Note that the mask 1221 is a mask for protecting a semiconductor film forming an n-channel TFT and a peripheral region thereof.
The ion doping conditions in the second doping treatment are boron (B) with a dose of 1 × 10 ¹⁵ to 2 × 10 ¹⁶ atoms / cm ² and an acceleration voltage of 50 to 100 keV.

Here, impurity regions are formed in the respective semiconductor layers in a self-aligned manner using the second conductive layers 1214b and 1215b as masks, but of course, boron is not added to the regions covered with the mask 1221.
Through the second doping treatment, a third impurity region 1222 and a fourth impurity region 1223 in which an impurity element imparting p-type conductivity is added to the semiconductor layer forming the p-channel TFT are formed.
Further, an impurity element imparting p-type conductivity is added to the third impurity region 1222 in a concentration range of 1 × 10 ²⁰ to 1 × 10 ²¹ / cm ³ .

The fourth impurity region 1223 is formed in a region overlapping with the tapered portion of the first conductive layer 1214a and imparts p-type in a concentration range of 1 × 10 ¹⁸ to 1 × 10 ²⁰ / cm ^3. Impurity elements are added.
Note that the fourth impurity region 1223 has a concentration gradient in which the impurity concentration increases toward the end portion of the tapered portion in order to perform doping by transmitting the portion of the first conductive layer 1214a having a tapered shape.
Here, a region having the same concentration range as the fourth impurity region 1223 is also referred to as a p ⁻ region.
Through the above steps, an impurity region having n-type or p-type conductivity is formed in each semiconductor layer.
Note that the second shape conductive layers 1214 and 1215 serve as a gate electrode of the TFT.

Next, a step of activating the impurity element added to each semiconductor layer is performed.
This activation step may be a rapid thermal annealing method (RTA method) using a lamp light source, a method of irradiating a YAG laser or an excimer laser from the back surface, a heat treatment using a furnace, or a combination thereof. By different methods.
After that, a first insulating film 1224 is formed.
In this embodiment, a silicon nitride oxide film having a thickness of 50 nm formed by a plasma CVD method is used. Of course, this insulating film is not limited to a silicon nitride oxide film, but silicon nitride, silicon oxide, etc. The insulating film may be used as a single layer or a stacked structure.

Further, a second insulating film 1225 is formed over the first insulating film 1224.
As the second insulating film 1225 formed here, an insulating film such as silicon nitride, silicon nitride oxide, or silicon oxide can be used. In this embodiment, a film having a thickness of 50 nm formed by a plasma CVD method is used. A silicon nitride film is used.

Next, after the second insulating film 1225 made of a silicon nitride film is formed, a heat treatment (heat treatment at 300 to 550 ° C. for 1 to 12 hours) is performed to perform a step of hydrogenating the semiconductor layer (FIG. 13C )).
This step is a step of terminating dangling bonds in the semiconductor layer with hydrogen contained in the second insulating film 1225. As other means for hydrogenation, heat treatment at about 350 ° C. in a hydrogen atmosphere or plasma hydrogenation can be performed. (Using hydrogen excited by plasma) can also be performed.

After that, a third insulating film 1226 made of an organic insulating material is formed over the second insulating film 1225. Here, an acrylic resin film having a thickness of 1.6 μm is formed.
Further, contact holes 1227 reaching the respective impurity regions are formed.
Since the acrylic resin used in this embodiment is photosensitive acrylic, a desired position can be opened by exposure and development.
Further, a part of the first insulating film 1224 and the second insulating film 1225 is etched by a dry etching method, and the second insulating film 1225 is etched using the first insulating film 1224 as an etching stopper. Then, the first insulating film 1224 is etched.
As a result, a contact hole 1227 is obtained.

As described above, in this embodiment, the case where the contact hole is formed after the third insulating film 1226 formed of the organic resin film has been described. However, before the third insulating film 1226 is formed, the first insulating film 1226 is formed. The second insulating film 1225 and the first insulating film 1224 can be dry-etched.
Note that in this case, it is preferable that the substrate is heat-treated (300 to 550 ° C. for 1 to 12 hours) after the etching and before the third insulating film 1226 is formed.
Further, as shown in FIG. 13D, by forming the wiring 1228 using Al, Ti, Mo, tungsten, or the like, the n-channel TFT 1301 and the p-channel TFT 1302 can be formed over the same substrate.

When the laser irradiation apparatus of the present invention is used, not only the semiconductor device described in this embodiment but also various semiconductor devices can be manufactured.
In addition, this embodiment can be freely combined with the embodiment mode and other embodiments.

The figure explaining the concept of a beam homogenizer. The figure explaining the 1st principal point and 2nd principal point of a synthetic lens of a convex lens and a concave lens, and synthetic focal distance. The figure explaining the concept of the beam homogenizer of this invention. The figure explaining the laser irradiation apparatus of this invention. The figure explaining another aspect of the laser irradiation apparatus of this invention. The figure explaining the laser irradiation apparatus of background art. The figure which shows the result of having calculated the laser irradiation apparatus of this invention shown in FIG. 4 with optical design software. FIG. 6 is a diagram illustrating Example 3. FIG. 6 is a diagram illustrating Example 4; FIG. 10 is a diagram illustrating Example 5. FIG. 10 is a diagram illustrating the structure of a fly-eye lens used in Example 5. 8A and 8B illustrate a method for manufacturing a TFT of Example 6. 8A and 8B illustrate a method for manufacturing a TFT of Example 6.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Cylindrical lens array 102 Cylindrical lens array 103 Cylindrical lens 104 Irradiation surface 201 Lens 202 Lens 203 Lens 204 Lens 301 Cylindrical lens array 302 Cylindrical lens array 303 Cylindrical lens array 304 Cylindrical lens array 305 Cylindrical lens 401 Laser oscillator 402a Spherical lens 402b Spherical lens 403a Cylindrical lens array 403b Cylindrical lens array 404a Cylindrical lens array 404b Cylindrical lens array 405a Cylindrical lens array 405b Cylindrical lens array 405 Cylindrical lens 406 Cylindrical lens 407 Cylindrical lens 408 Ret cylindrical lens 409 Irradiation surface 410 Surface 503 Cylindrical lens array 601 Laser oscillator 603 Cylindrical lens array 604 Cylindrical lens 605 Cylindrical lens 606 Mirror 607 Doublet cylindrical lens 608 Irradiation surface 801 Cylindrical lens array 1001 Laser oscillator 1005 Spherical lens 1007 Doublet lens 1007 1008 surface 1201 substrate 1202 metal layer 1203 adhesive 1204 oxide layer 1205 semiconductor layer 1207 insulating film 1208 conductive film 1209 conductive film 1210 mask 1211 gate insulating film 1212 conductive layer 1214 conductive layer 1218 mask 1219 impurity region 1220 impurity region 1221 mask 1222 impurity Region 1223 Impurity region 1224 Enmaku 1225 insulating film 1226 the insulating film 1227 contact hole 1228 wiring 1301 n-channel type TFT
1302 p-channel TFT
602a Cylindrical lens array 602b Cylindrical lens array 1002a Spherical lens 1002b Spherical lens 1003a Fly-eye lens 1003b Fly-eye lens 1004a Fly-eye lens 1004b Fly-eye lens 1006a Spherical lens 1006b Spherical lens 1212a Conductive layer 1212b Conductive layer 1214a Conductive layer 1214b Conductive layer 1214b layer

Claims (20)

  An optical path shortening type front array lens in which the second principal point is located in front of the beam incident side, an optical path shortening type rear array lens in which the first principal point is located in the rear of the beam exit side, and a condensing lens, further comprising the front array A beam homogenizer characterized in that the distance between the second principal point of the lens and the first principal point of the rear array lens is the focal length of the rear array lens.   An optical path shortening type front array lens in which a second principal point is positioned in front of the beam incident side, an optical path non-shortening type rear array lens, and a condenser lens are provided, and the second principal point of the front array lens and the rear array are further provided. A beam homogenizer characterized in that the distance from the first principal point of the lens is the focal length of the rear array lens.   An optical path non-shortening type front array lens, an optical path shortening type rear array lens whose first principal point is located on the rear side of the beam exit side, and a condensing lens, and further, a second principal point of the front array lens and the rear array A beam homogenizer characterized in that the distance from the first principal point of the lens is the focal length of the rear array lens.   The beam homogenizer according to any one of claims 1 to 3, wherein the optical path shortening type front array lens and the optical path shortening type rear array lens are synthetic array lenses or array lenses having curved surfaces on both sides.   The beam homogenizer according to claim 4, wherein the synthetic array lens includes two or more array lenses, and each array lens is a cylindrical lens array or a fly-eye lens.   The beam homogenizer according to claim 4, wherein the array lens having curved surfaces on both sides is any of a cylindrical lens array, a fly-eye lens, or a crossed cylindrical lens array having curved surfaces on both the front and rear sides.   4. The beam homogenizer according to claim 2, wherein the array lens constituting the optical path non-shortening type front array lens or the optical path non-shortening type rear array lens is a combination array lens or a non-combination array lens.   The beam homogenizer according to claim 7, wherein the non-combination array lens is a cylindrical lens array or a fly-eye lens.   4. The beam homogenizer according to claim 1, wherein the condenser lens is a cylindrical lens, a toric lens, or a crossed cylindrical lens.   Both the optical path shortening type front array lens and the optical path shortening type rear array lens are constituted by two cylindrical lens arrays, the curved surface of the front cylindrical lens array of the front array lens is convex, and the curved surface of the rear cylindrical lens array is concave. The beam homogenizer according to claim 1, wherein the curved surface of the front cylindrical lens array of the rear array lens is concave and the curved surface of the rear cylindrical lens array is convex.   The optical path shortening type front array lens is composed of two cylindrical lens arrays, the curved surface of the front cylindrical lens array of the front side array lens is convex, the curved surface of the rear cylindrical lens array is concave, and the rear side of the optical path non-shortening type The beam homogenizer according to claim 2, wherein the array lens is a cylindrical lens array.   The optical path non-shortening type front array lens is a cylindrical lens array, the optical path shortening type rear array lens is composed of two cylindrical lens arrays, and the curved surface of the front cylindrical lens array of the rear array lens is concave, and the rear cylindrical lens. The beam homogenizer according to claim 3, wherein the curved surface of the array is convex.   Both the optical path shortening type front array lens and the optical path shortening type rear array lens are composed of two fly eye lenses, the curved surface of the front fly eye lens of the front array lens is convex, and the curved surface of the rear fly eye lens is concave. 6. The beam homogenizer according to claim 1, wherein the curved surface of the front fly-eye lens of the rear array lens is concave and the curved surface of the rear fly-eye lens is convex.   The optical path shortening type front array lens is composed of two fly eye lenses, the curved surface of the front fly eye lens of the front array lens is convex, the curved surface of the rear fly eye lens is concave, and the rear side of the optical path non-shortening type The beam homogenizer according to claim 2, wherein the array lens is a fly-eye lens.   The optical path non-shortening type front array lens is a fly-eye lens, the optical path shortening type rear array lens is composed of two fly-eye lenses, the curved surface of the front fly-eye lens of the rear array lens is concave, and the rear fly-eye The beam homogenizer according to claim 3, wherein the curved surface of the lens is convex.   The optical path shortening type front array lens and the optical path shortening type rear array lens are both configured by a cylindrical lens array having curved surfaces on both sides, the front curved surface of the front array lens is convex, the rear curved surface is concave, and the rear The beam homogenizer according to claim 1, 4 or 6, wherein the front curved surface of the side array lens is concave and the rear curved surface is convex.   The optical path shortening type front array lens is composed of a cylindrical lens array having curved surfaces on both sides, the front curved surface of the front side array lens is convex, the rear curved surface is concave, and the non-optical path back side array lens is a single-sided curved cylindrical lens. The beam homogenizer according to claim 2 which is an array.   The optical path non-shortening type front array lens is a single-sided curved cylindrical lens array, and the optical path shortening type rear array lens is composed of a cylindrical lens array having curved surfaces on both sides, and the front curved surface of the rear array lens is concave and the rear curved surface is The beam homogenizer according to claim 3 which is a convex type. A beam homogenizer according to any one of claims 1 to 18, wherein the energy density distribution in one direction of the short side direction or the long side direction is made uniform, and the energy density distribution in the remaining other direction is made uniform, and both directions And a stage on which an irradiation surface for projecting an irradiation beam having a uniform energy density distribution is provided. Irradiation in which an energy density distribution in both the short side direction and the long side direction is made uniform by the beam homogenizer according to any one of claims 1 to 18 and an irradiation beam in which the energy density distribution in both directions is made uniform is projected. A laser irradiation apparatus comprising a stage for setting a surface.

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