JP6391764B2 - Laser irradiation device - Google Patents

Description

The present invention relates to a laser irradiation apparatus that guides a pulse laser beam from a first laser light source and a pulse laser beam from a second laser light source to the same optical path and irradiates a laser irradiated object.

Conventionally, two laser light sources (laser resonators) that emit a pulse laser beam at a predetermined frequency are used, and the pulse laser beams from these laser resonators are in a desired range of a laser irradiated object (for example, a semiconductor substrate). Have been developed (for example,
Patent Document 1) below. FIG. 9 shows a configuration example of such a laser irradiation apparatus. As shown in FIG. 9, the laser irradiation apparatus includes two laser resonators 31 and 32, a pulse control device 33,
An optical path combining optical member 35, a beam expander 37, a cylindrical lens array 39, and a condenser lens 41 are provided.

The first laser resonator 31 emits a linearly polarized pulsed laser beam having a polarization direction perpendicular to the paper surface of FIG. 9 at a predetermined frequency, and the second laser resonator 32 has a polarization direction of FIG. A linearly polarized pulsed laser beam in the vertical direction is emitted at a predetermined frequency.

The pulse control device 33 includes the first and the first so that the timing at which the pulse laser beam is emitted from the first laser resonator 31 and the timing at which the pulse laser beam is emitted from the second laser resonator 32 are shifted. 2 laser resonators 31 and 32 are controlled.

The optical path combining optical member 35 guides the pulse laser beams to the same optical path by utilizing the fact that the polarization directions of the pulse laser beams from the first and second laser resonators 31 and 32 are shifted by 90 degrees. . The optical path combining optical member 35 is, for example, a polarization beam splitter that reflects a pulse laser beam linearly polarized in a direction perpendicular to the paper surface of FIG. 9, but transmits a pulse laser beam linearly polarized in the vertical direction of FIG. Thus, the optical path combining optical member 35
To guide the pulse laser beams from the two laser resonators 31 and 32 to the same optical path,
Thereby, the frequency of the pulse laser beam can be doubled and the power of the pulse laser beam can be increased.

The beam expander 37 adjusts the shape of each pulse laser beam from the optical path synthesis optical member 35 to be horizontally long. Each pulse laser beam that has passed through the beam expander 37 has a cross-sectional shape perpendicular to the traveling direction thereof that is horizontally long (for example, linear or rectangular) on the laser irradiation surface on the laser irradiation object (for example, a semiconductor substrate). Adjusted as follows. In the example of FIG. 9, the cross-sectional shape is adjusted to be horizontally long in the vertical direction of FIG.

The cylindrical lens array 39 divides the incident pulse laser beam into a plurality of beams, and the condenser lens 41 superimposes the divided plurality of beams on the laser irradiation surface on the laser irradiation object. Reference numeral 43 denotes a short-side direction condensing lens that condenses the pulse laser beam on the laser irradiation surface in a direction perpendicular to the paper surface of FIG.

When the pulse laser beam is sequentially irradiated onto the surface of the semiconductor substrate by the laser irradiation apparatus described above, the semiconductor substrate is transported in a direction perpendicular to the paper surface of FIG. Thereby, the pulse laser beam is irradiated over a desired range on the surface of the semiconductor substrate. In addition, as other prior art documents other than Patent Document 1, for example, there is Patent Document 2 below.

Japanese Patent Laying-Open No. 2007-110064 (FIG. 14) JP 2004-95792 A

When performing laser annealing on a semiconductor substrate by performing laser irradiation on the semiconductor substrate using the laser irradiation apparatus of FIG. 9, the polarization state is different for each pulse laser beam.
The difference in the polarization state for each pulse laser beam may adversely affect the laser irradiation body.

When laser annealing is performed by irradiating the laser irradiation surface of the semiconductor substrate only with a pulsed laser beam that is S-polarized light to a desired range of the amorphous semiconductor substrate, and with respect to the laser irradiation surface of the semiconductor substrate surface The average size of crystallized semiconductor crystal grains is different from that in the case where laser annealing is performed by irradiating only a pulsed laser beam of P-polarized light onto a desired range of the amorphous semiconductor substrate. Here, S-polarized light refers to a polarization state in which the electric field direction of the beam is parallel to the vertical direction of the paper surface on the laser irradiation surface of FIG. . FIG. 10 is a graph showing this difference. In FIG. 10, the horizontal axis indicates the energy density of the pulsed laser beam applied to the surface of the amorphous semiconductor substrate, the vertical axis indicates the average size of the semiconductor crystal grains crystallized by laser annealing, and the square indicates , S
Each measurement result when the amorphous semiconductor substrate is irradiated with only the polarized pulsed laser beam is shown, and the diamond shape indicates each measurement when the amorphous semiconductor substrate is irradiated with only the P-polarized pulsed laser beam. Results are shown. As can be seen from FIG. 10, the dimensions of the semiconductor crystal grains grown by the S-polarized pulse laser beam are different from the dimensions of the semiconductor crystal grains grown by the P-polarized pulse laser beam. Therefore, when the semiconductor substrate is irradiated with the S-polarized pulse laser beam and the P-polarized pulse laser beam alternately, the region irradiated with the S-polarized pulse laser beam and the region irradiated with the P-polarized pulse laser beam May occur. As a result, the crystal grain size may be non-uniform, and a stable crystalline semiconductor may not be obtained. Thus, the difference in the polarization state for each pulse laser beam may adversely affect the laser irradiation body.

Therefore, an object of the present invention is to provide a laser irradiation body with a difference in polarization state for each pulse laser beam when a pulse laser beam from two laser light sources is guided to the same optical path and irradiated to the laser irradiation object. It is an object of the present invention to provide a laser irradiation apparatus that can eliminate or greatly reduce the influence.

To achieve the above object, according to the present invention, a first laser light source that emits a polarized pulsed laser beam;
A second laser light source that emits a pulsed laser beam having a polarization state different from that of the pulsed laser beam from the first laser light source;
An optical path combining optical member for guiding the pulse laser beams from the first and second laser light sources onto the same optical path,
A polarization control member for controlling the polarization state of the pulse laser beam from the optical path synthesis optical member,
The polarization control member is arranged in an arrangement direction orthogonal to the traveling direction of the pulse laser beam, and has first and second polarization control units through which beam components of the pulse laser beam pass,
The first and second polarization control units are formed such that the beam component that has passed through the first polarization control unit and the beam component that has passed through the second polarization control unit have different polarization states. Has been
There is provided a laser irradiation apparatus comprising a beam superimposing optical member that superimposes the beam components having different polarization states on a laser irradiation surface on a laser irradiation object.

In the above configuration, when the pulsed laser beams emitted from the first and second laser light sources having different polarization states are guided on the same optical path and irradiated to the laser irradiated object, the first and second
Each of the pulse laser beams emitted from the laser light source is separated into a plurality of beam components having different polarization states (first polarization state and second polarization state) by the polarization control member, and the beam superposing optical member Since the beam components having different polarization states are superimposed on the laser irradiation surface on the laser irradiation object, any pulse laser beam is
The first polarization state and the second polarization state are mixed on the laser irradiation surface. Thereby, the influence which the difference of the polarization state for every pulse laser beam has on a laser irradiation body can be eliminated, or it can reduce significantly.

According to a preferred embodiment of the present invention, the total energy amount of the beam component passing through the first polarization control unit and the total energy amount of the beam component passing through the second polarization control unit are the same or substantially the same. And the length of the first polarization controller in the arrangement direction, and
The length of the second polarization controller in the arrangement direction is set.

In this way, the arrangement direction is such that the total energy of the beam component passing through the first polarization controller and the total energy of the beam component passing through the second polarization controller are the same or substantially the same. Since the length of the first polarization control unit in and the length of the second polarization control unit in the arrangement direction are set, any of the pulse laser beams emitted from the first and second laser light sources As for the laser beam, the energy of the beam component in the first polarization state and the energy of the beam component in the second polarization state can be made the same on the laser irradiation surface. Thereby, more stable laser irradiation (for example, laser annealing of a semiconductor substrate) becomes possible.

According to a preferred embodiment of the present invention, at least one of the first polarization control unit and the second polarization control unit is divided into a plurality so as to sandwich all or part of the other in the arrangement direction.

In this way, at least one of the first polarization control unit and the second polarization control unit may be divided into a plurality of parts so that all or part of the other is sandwiched in the arrangement direction. Even with this configuration, the same effect as described above can be obtained.

According to a preferred embodiment of the present invention, the first laser light source and the second laser light source each emit a linearly polarized pulsed laser beam with a polarization direction shifted by 90 degrees,
The first polarization controller is a half-wave plate that rotates the polarization direction of the beam component from the first laser light source and the second laser light source by 90 degrees,
The second polarization controller is formed so as not to change the polarization state of the beam components from the first laser light source and the second laser light source.

In this way, the beam component that has passed through the half-wave plate of the first polarization control unit rotates the polarization direction by 90 degrees, and the second polarization control unit changes the polarization state of the beam component that has passed through it. Do not change. As a result, for each pulse laser beam, the beam component that has passed through the first polarization controller and the beam component that has passed through the second polarization controller can be in different polarization states.

Preferably, the second polarization controller has an optical path length within which the pulse laser beam travels first.
It is made of the same material as that of the polarization controller.

Thus, the second polarization controller has the first optical path length through which the pulse laser beam travels.
Therefore, there is no difference between the optical path length in which the beam travels in the first polarization control section and the optical path length in which the beam travels in the second polarization control section. ,
An adverse effect (for example, an imaging position error on the laser irradiation surface) due to the difference in optical path length can be prevented.

According to another embodiment of the present invention, the first laser light source and the second laser light source each emit a linearly polarized pulsed laser beam with a polarization direction shifted by 90 degrees from each other,
The first and second polarization control units are 45 in both the polarization direction of the pulse laser beam from the first laser light source and the polarization direction of the pulse laser beam from the second laser light source.
A quarter-wave plate with an optical axis forming an angle of degrees,
The optical axis of the first polarization controller and the optical axis of the second polarization controller are shifted from each other by 90 degrees.

When the optical axis of the quarter-wave plate makes an angle of 45 degrees on the one side with the polarization direction of the linearly polarized laser, this quarter-wave plate rotates the laser passing therethrough in the first direction of polarization. Use circularly polarized light. When the optical axis of the quarter-wave plate makes an angle of 45 degrees to the polarization direction of the linearly polarized laser and the other side, the quarter-wave plate passes the laser passing therethrough and the polarization direction is the first direction. Circularly polarized light that rotates in the opposite direction.
Therefore, in the above configuration, the first and second polarization control units are configured so that the polarization direction of the pulse laser beam from the first laser light source and the polarization direction of the pulse laser beam from the second laser light source are the same. Is a quarter-wave plate having an optical axis that forms an angle of 45 degrees, and the optical axis of the first polarization controller is offset by 90 degrees from the optical axis of the second polarization controller. The beam component that has passed through the first polarization controller and the beam component that has passed through the second polarization controller are:
A circular polarization state in which the polarization directions rotate in opposite directions is obtained. Thereby, the beam component that has passed through the first polarization control unit and the beam component that has passed through the second polarization control unit can have different polarization states.

According to the present invention described above, when a pulse laser beam from two laser light sources is guided to the same optical path to irradiate the laser irradiation object, the influence of the difference in the polarization state of each pulse laser beam on the laser irradiation object. Can be eliminated or greatly reduced. Thus, a stable crystalline semiconductor can be obtained by performing laser irradiation on the semiconductor substrate using the laser irradiation apparatus of the present invention.

It is a block diagram of the laser irradiation apparatus by 1st Embodiment of this invention. It is an enlarged view of the part II of FIG. The energy density distribution of each beam component on the laser irradiation surface and the energy distribution obtained by superimposing these energy density distributions are shown. It is an electron microscope image of the laser irradiation surface for showing the effect acquired by a 1st embodiment. It is an optical microscope image of the laser irradiation surface for showing the effect acquired by a 1st embodiment. FIG. 2 is an enlarged view of part II of FIG. 1, showing a case of the second embodiment of the present invention. The modification of the polarization control member by other embodiment of this invention is shown. The modification of the polarization control member and cylindrical lens array by another embodiment of this invention is shown. It is a block diagram of the laser irradiation apparatus using two laser resonators. 5 is a graph showing a difference in semiconductor crystal size depending on a polarization direction in laser annealing on a semiconductor substrate.

The best mode for carrying out the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

[First Embodiment]
FIG. 1 is a configuration diagram of a laser irradiation apparatus 10 according to a first embodiment of the present invention. 2 is shown in FIG.
FIG. 2 is an enlarged view of a portion “II” in FIG. As shown in FIG. 1, the laser irradiation device 10 includes first and second laser light sources 3 and 4, a pulse control device 5, an optical path synthesis optical member 7, a beam expander 8, a polarization control member 9, and beam superposition optics. A member 11 is provided.

The first laser light source 3 is a laser resonator that emits a polarized pulsed laser beam at a predetermined frequency. The second laser light source 4 is a laser resonator that emits a pulse laser beam having a polarization state different from that of the pulse laser beam from the first laser light source 3 at a predetermined frequency. In this example, the frequency at which the first laser light source 3 emits a pulsed laser beam is the same as the frequency at which the second laser light source 4 emits a pulsed laser beam. In the present embodiment, the first laser light source 3 emits a linearly polarized pulse laser beam (hereinafter referred to as a first linearly polarized state) whose polarization direction is perpendicular to the paper surface of FIGS. 1 and 2 at a predetermined frequency. Ejected and second laser light source 4
Is a linearly polarized light whose polarization direction is the vertical direction of FIGS. 1 and 2 (hereinafter referred to as a second linear polarization state).
Are emitted at a predetermined frequency.

The pulse control device 5 includes the first and the first so that the timing at which the pulse laser beam is emitted from the first laser resonator 3 and the timing at which the pulse laser beam is emitted from the second laser resonator 4 are shifted. 2 laser resonators 3 and 4 are controlled.

The optical path combining optical member 7 guides the pulse laser beams from the first and second laser light sources 3 and 4 on the same optical path. Thereby, the frequency of the pulse laser beam can be doubled and the power of the pulse laser beam can be increased. The optical path combining optical member 7 may be the same as the optical path combining optical member 35 shown in FIG. In the example of FIG. 1, the optical path combining optical member 7 is a polarization beam splitter that reflects the pulse laser beam from the first laser resonator 3 and transmits the pulse laser beam from the second laser resonator 4.

The beam expander 8 adjusts the shape of each pulse laser beam from the optical path combining optical member 7 so as to be horizontally long. Each pulsed laser beam that has passed through the beam expander 8 has a cross-sectional shape that is perpendicular to the traveling direction of the pulsed laser beam on the laser irradiation surface on the laser irradiated body (for example,
Linear or rectangular). In FIG. 1 and FIG. 2, it adjusts so that it may become horizontally long in the up-down direction of FIG.

The polarization control member 9 controls the polarization state of the pulse laser beam from the optical path synthesis optical member 7 and the beam expander 8. The polarization control member 9 is disposed in an arrangement direction (vertical direction in FIG. 2) orthogonal to the traveling direction of the pulse laser beam, and the first and second beam components of the pulse laser beam from the optical path combining optical member 7 pass through, respectively. Polarization control units 13 and 15. The beam component that has passed through the first polarization control unit 13 (the portion indicated by hatching in FIG. 2);
The first and second polarization control units 13 and 15 are formed so that the beam components that have passed through the second polarization control unit 15 are in different first and second polarization states, respectively. . At least one of the first polarization control unit 13 and the second polarization control unit 15 may be divided into a plurality so as to sandwich all or part of the other in the arrangement direction. In the example of FIG. 2, the first polarization control unit 13 is divided into three polarization control elements 13a, 13b, and 13c, and the second polarization control unit 15 is divided into two polarization control elements 15a and 15b. Polarization control element 13a,
13b sandwiches the polarization control element 15a in the arrangement direction, the polarization control elements 13a and 13c sandwich the polarization control element 15b in the arrangement direction, and the polarization control elements 15a and 15b sandwich the polarization control element 13a in the arrangement direction. Has been placed.
In the present embodiment, the total energy amount of the beam component passing through the first polarization control unit 13 and the total energy amount of the beam component passing through the second polarization control unit 15 are the same or substantially the same. The length of the first polarization control unit 13 in the arrangement direction and the length of the second polarization control unit 15 in the arrangement direction are set.
In the present embodiment, the first polarization control unit 13 (polarization control elements 13a to 13c) is 1 /
The second polarization controller 15 (polarization control elements 15a and 15b) is a wave plate (full wave plate) or a quartz plate that does not change the polarization state of the beam component passing therethrough. 1/2 wavelength plate 13
, 13a to 13c also have a second polarization direction of the pulse laser beam from the first laser resonator 3.
The polarization direction of the pulse laser beam from the laser resonator 4 is also arranged to rotate 90 degrees. That is, the optical axis of the half-wave plate is set to 45 degrees with respect to the polarization direction of the pulse laser beam from the first laser resonator 3, and the polarization of the pulse laser beam from the second laser resonator 4. By making the angle 45 degrees with respect to the direction, the polarization direction of the pulse laser beam from any of the laser resonators 3 and 4 is rotated by 90 degrees by the half-wave plate 13. As a result, when the beam component in the first linear polarization state passes through the half-wave plate 13, the beam component in the second linear polarization state becomes the second linear polarization state (second polarization state).
When the light passes through the wave plate 13, the first linear polarization state (first polarization state) is obtained.
The second polarization control units 15, 15 a, and 15 b are formed of a material that transmits the pulse laser beam and has the same optical path length as the first polarization control unit 13 through which the pulse laser beam travels. That is, the material of the second polarization controller 15 is the same as the material of the first polarization controller 13.
For example, the second polarization control unit 15 may be a full-wave plate or a quartz plate made of quartz. Therefore, when the beam component in the first linear polarization state passes through the second polarization control unit 15, it remains in the first linear polarization state (first polarization state), and the beam component in the second linear polarization state becomes the second When passing through the polarization controller 15, the second linear polarization state (second polarization state) remains.

The beam superimposing optical member 11 superimposes the beam component in the first polarization state and the beam component in the second polarization state on the laser irradiation surface on the laser irradiated body. In the present embodiment, the beam superimposing optical member 11 includes a cylindrical lens array 17 and a condenser lens 18. The cylindrical lens array 17 has a plurality of convex cylindrical lenses 17a arranged in the arrangement direction. Accordingly, the pulse laser beam incident on the cylindrical lens array 17 is divided into a plurality of beams by the plurality of convex cylindrical lenses 17a. The plurality of divided beams are superimposed on the laser irradiation surface on the laser irradiation object by the condenser lens 18. Thereby, even if the pulse laser beam before passing through the beam superimposing optical member 11 has a non-uniform energy density distribution, the energy density is uniform or nearly uniform on the laser irradiation surface on the laser irradiation object. Have a distribution. In the example of FIG. 2, each polarization control element 13a, 13b, 13c, 1
Corresponding to 5a and 15d, the same number of convex cylindrical lenses 17a are provided.
As a result, the beam component from each polarization control element that has passed through each convex cylindrical lens 17 a is irradiated by the condenser lens 18 to the entire laser irradiation region on the laser irradiation surface.
The laser irradiated body is a semiconductor substrate in this embodiment. The semiconductor substrate means a substrate formed of a semiconductor such as a silicon wafer or a substrate in which a semiconductor film is formed on the surface of an insulating substrate. Reference numeral 12 denotes a short-side direction condensing lens that condenses the pulse laser beam on the laser irradiation surface in a direction perpendicular to the paper surface of FIG.

Next, the operation of the laser irradiation apparatus 10 having the above configuration will be described. Polarization control member 9
The beam component in the first polarization state and the beam component in the second polarization state are irradiated on the laser irradiation surface such that the energy density distribution is extended over the entire laser irradiation region on the laser irradiation surface. Thus, the first polarization state and the second polarization state are mixed at each position of the laser irradiation region.
As described above, the beam component in the first linear polarization state is a half-wave plate (polarization control element 13a).
˜13c), the second linear polarization state (second polarization state) is obtained, and the beam component of the second linear polarization state enters the first linear polarization state (first polarization state) after passing through the half-wave plate. On the other hand, the polarization control elements 15a and 15b do not change the polarization state of the passing beam component. Therefore, both the pulse laser beam in the first linear polarization state and the pulse laser beam in the second linear polarization state pass through the polarization control member 9, so that the beam component in the first polarization state and the beam component in the second polarization state And have both.
In FIG. 2, the energy density distribution of the pulse laser beam before passing through the polarization control member 9 is shown corresponding to the positions of the polarization control elements 13a to 13c, 15a and 15b. When the pulse laser beam in the first linear polarization state having the energy density distribution shown in FIG. 2 passes through the polarization control member 9, the energy density distribution of the beam components that have passed through the polarization control elements 13a, 13b, 13c, 15a, and 15b. Respectively have the energy density distributions shown in FIGS. 3A to 3E on the laser irradiation surface by the action of the beam superposing optical member 11. In FIG. 3, each vertical axis represents the position in the arrangement direction on the laser irradiation surface, and each horizontal axis represents the energy density of the beam component. More specifically, in FIG. 3, (a) shows the energy density distribution of the beam component in the second polarization state that has passed through the polarization control element 13a on the laser irradiation surface, and (b) has passed through the polarization control element 13b. The energy density distribution that the beam component in the second polarization state has on the laser irradiation surface is shown. (C) shows the energy density distribution that the beam component in the second polarization state that has passed through the polarization control element 13c has on the laser irradiation surface. (D) shows the energy density distribution of the beam component in the first polarization state that has passed through the polarization control element 15a on the laser irradiation surface, and (e) shows the polarization control element 15b.
The beam component in the first polarization state that has passed through is shown an energy density distribution on the laser irradiation surface, and (f) shows an approximate energy density distribution obtained by superimposing these energy density distributions of (a) to (e). . With such an energy density distribution, the first polarization state and the second polarization state are mixed at each position of the laser irradiation region on the laser irradiation surface.
In the present embodiment, in FIG. 3, the total amount of energy (a), (b), (c) and (
The total amount of energy in d) and (e) is the same.

2 and 3 show the case where the pulse laser beam in the first linear polarization state passes through the polarization control member 9, the same applies when the pulse laser beam in the second polarization state passes through the polarization control member 9. It is. In this case, in FIG. 3, (a) is the energy density distribution of the beam component in the first polarization state that has passed through the polarization control element 13a, and (b) is the beam component in the first polarization state that has passed through the polarization control element 13b. An energy density distribution is obtained, and (c) is a polarization control element 13c.
(D) becomes the energy density distribution of the beam component in the second polarization state that has passed through the polarization control element 15a, and (e) passes through the polarization control element 15b. Thus, the energy density distribution of the beam component in the second polarization state is obtained.

While the laser irradiation apparatus 10 irradiates the laser irradiation surface on the laser irradiated object with a pulse laser beam, the laser irradiated object is conveyed in a direction perpendicular to the paper surface of FIGS. Thereby, a pulse laser beam is irradiated over a desired range on the laser irradiation object.

According to the laser irradiation apparatus 10 according to the first embodiment of the present invention described above, the pulsed laser beams emitted from the first and second laser light sources 3 and 4 having different polarization states are guided on the same optical path to be irradiated with the laser beam. When irradiating the irradiating body, the pulsed laser beams emitted from the first and second laser light sources 3 and 4 are different from each other in the polarization state (first polarization state and second polarization state) by the polarization control member 9. ), And the beam superimposing optical member 11 superimposes the beam components having different polarization states on the laser irradiation surface on the laser irradiation object. The first polarization state and the second polarization state are mixed on the laser irradiation surface. Thereby, the influence which the difference of the polarization state for every pulse laser beam has on a laser irradiation body can be eliminated, or it can reduce significantly.

Further, the arrangement direction is such that the total energy of the beam component passing through the first polarization control unit 13 and the total energy of the beam component passing through the second polarization control unit 15 are the same or substantially the same. Since the length of the first polarization controller 13 and the length of the second polarization controller 15 in the arrangement direction are set, the first and second laser light sources 3 are set.
, 4 for any of the pulsed laser beams emitted from the laser irradiation surface,
The total energy of the beam component in the first polarization state and the total energy of the beam component in the second polarization state can be made the same. Thereby, more stable laser irradiation (for example, laser annealing of a semiconductor substrate) becomes possible.

Further, the second polarization controller 15 has an optical path length within which the pulse laser beam travels first.
Therefore, there is a difference between the optical path length in which the beam travels in the first polarization control section 13 and the optical path length in which the beam travels in the second polarization control section. Thus, adverse effects due to the difference in optical path length (for example, an imaging position error on the laser irradiation surface) can be prevented.

(Example)
4 and 5 are images of the laser irradiation surface for illustrating the effect obtained by the first embodiment. 4 is an electron microscope image, and FIG. 5 is an optical microscope image.
4 and 5, the upper images (A) to (C) to be compared are lasers on the semiconductor substrate obtained by irradiating the semiconductor substrate with laser without using the polarization control member 9. It is an image of the irradiated surface, among which (A) is a case of irradiation with a P-polarized pulse laser beam,
(B) shows the case of irradiation with an S-polarized pulse laser beam, and (C) shows the case of irradiation with a composite of P-polarized light and S-polarized pulse laser beam (that is, the polarization control member 9 in FIG. 1). This is a low-magnification image of the case where laser irradiation is performed with a configuration in which is omitted.
On the other hand, in each of FIGS. 4 and 5, the lower images (D) to (F) corresponding to the present embodiment are obtained by irradiating the semiconductor substrate with laser using the polarization control member 9. It is an image of the upper laser irradiation surface, among which (D) is the case of irradiation with a P-polarized pulse laser beam (that is, the first of the first and second laser light sources 3 and 4 in FIG. 1). (E) is a case where an S-polarized pulse laser beam is irradiated (ie,
In FIG. 1, the second laser light source 4 is used among the first and second laser light sources 3 and 4), and (F) shows a combination of P-polarized and S-polarized pulsed laser beams. 2 is a low-magnification image when irradiated (that is, when laser irradiation is performed with the configuration of FIG. 1).
In comparison, in FIGS. 4 and 5, since there is a difference in polarization state between (A) and (B), unevenness caused by the difference in polarization state occurs in the synthesized pulse laser beam as shown in (C). . On the other hand, in the present embodiment, there is almost no difference depending on the polarization state between (D) and (E). Therefore, as shown in (F), the synthetic pulse laser beam has unevenness caused by the difference in polarization state. Disappears.

[Second Embodiment]
In the laser irradiation apparatus according to the second embodiment of the present invention, the configuration of the polarization control member is different from the configuration of the polarization control member 9 of the first embodiment. Other configurations of the second embodiment may be the same as those of the first embodiment. FIG. 6 is an enlarged view of the portion “II” in FIG. 1 and shows the configuration of the second embodiment.

A portion of the configuration of the polarization control member 19 that is the same as that of the first embodiment will be described.
As shown in FIG. 6, the polarization control member 19 controls the polarization state of the pulse laser beam from the optical path synthesis optical member 7. The polarization control member 19 is arranged in the arrangement direction (vertical direction in FIG. 4), and passes through the first and second polarization control units 21 and 23 through which the beam components of the pulse laser beam from the optical path synthesis optical member 7 pass, respectively. Have. The first and second polarization states are different so that the beam component that has passed through the first polarization control unit 21 and the beam component that has passed through the second polarization control unit 23 are different from each other. And the 2nd polarization control parts 21 and 23 are formed. At least one of the first polarization controller 21 and the second polarization controller 23 is
It may be divided into a plurality of parts so as to sandwich all or part of the other in the arrangement direction. In the example of FIG. 6, the first polarization control unit 21 is divided into three polarization control elements 21a to 21c, and the second polarization control unit 23 is divided into two polarization control elements 23a and 23b. Element 21
a, 21b sandwich the polarization control element 23a in the arrangement direction, polarization control elements 21a, 21c sandwich the polarization control element 23b in the arrangement direction, and polarization control elements 23a, 23b sandwich the polarization control element 21a in the arrangement direction. Is arranged.
Further, the arrangement direction is such that the total energy of the beam component passing through the first polarization control unit 21 and the total energy of the beam component passing through the second polarization control unit 23 are the same or substantially the same. The length of the first polarization control unit 21 and the length of the second polarization control unit 23 in the arrangement direction are set.

Of the configuration of the polarization control member 19, a part different from the first embodiment will be described.
According to the second embodiment, the first and second polarization control units 21 and 23 of the polarization control member 19 perform the polarization direction of the pulse laser beam from the first laser light source 3 (direction perpendicular to the paper surface of FIG. 6). ) And the polarization direction of the pulse laser beam from the second laser light source 4 (vertical direction in FIG. 6)
These are quarter-wave plates having an optical axis that forms an angle of 45 degrees. The optical axis of the first polarization controller 21 and the optical axis of the second polarization controller 23 are shifted from each other by 90 degrees.
Accordingly, when the beam component in the first linear polarization state from the first laser resonator 3 passes through the first polarization control unit 21, the circularly polarized light (first polarization direction) whose polarization direction rotates in the direction of arrow A in FIG. (Polarized state) beam component. FIG. 6 shows a case where the pulse laser in the first linear polarization state is incident on the polarization control member 19, but the beam component in the second linear polarization state from the second laser resonator 4 is the first polarization. When the light passes through the control unit 21, it becomes a beam component of circularly polarized light (second polarization state) whose polarization direction rotates in the direction of the arrow B in FIG. 6, which is opposite to the arrow A in FIG. On the other hand, when the beam component in the first linear polarization state from the first laser resonator 3 passes through the second polarization control unit 23, the polarization direction is in the direction of the arrow B which is opposite to the arrow A in FIG. Rotating circularly polarized light (second
(Polarized state) beam component. FIG. 6 shows a case where the pulse laser in the first linear polarization state is incident on the polarization control member 19, but the beam component in the second linear polarization state from the second laser resonator 4 is the second polarization. In the case of passing through the control unit 23, the polarization component is a beam component of circularly polarized light (first polarization state) rotating in the direction of arrow A in FIG.

According to the laser irradiation apparatus of the second embodiment described above, any of the pulse laser beams emitted from the first and second laser light sources 3 and 4 and the beam component in the first polarization state by the optical path combining optical member 7 The beam component in the first polarization state and the beam component in the second polarization state are superimposed on the laser irradiation surface on the laser irradiated body by the beam superimposing optical member 11. Therefore, any pulsed laser beam is in a state in which the first polarization state and the second polarization state are mixed on the laser irradiation surface. Thereby, the influence which the difference of the polarization state for every pulse laser beam has on a laser irradiation body can be eliminated, or it can reduce significantly.
In addition to this effect, the same effects and operations as those of the laser irradiation apparatus 10 described above in the first embodiment can be obtained in the second embodiment.

[Other Embodiments]
In the first embodiment or the second embodiment, the following modifications can be adopted. Hereinafter, a modification of the first embodiment will be described, but the same modification can also be adopted in the second embodiment.
As shown in FIGS. 7A to 7C, the polarization control member 9 of the first embodiment is a polarization control element 13a.
, 13b and polarization control elements 15a, 15b, 15c. (A)
Then, the polarization control member 9 includes two polarization control elements 13a and 13b and one polarization control element 15.
In (B), the polarization control member 9 has one polarization control element 13a and one polarization control element 15a. In (C), the polarization control member 9 has two polarization control elements. Element 13a, 1
3b and three polarization control elements 15a, 15b, 15c. 7A to 7C, the length of the first polarization control unit 13 that combines the polarization control elements 13a and 13b in the arrangement direction, and the polarization control elements 15a, 15b, and 15c in the arrangement direction. As described above, the combined length of the second polarization control unit 15 includes the total amount of energy of the beam component passing through the first polarization control unit 13 and the beam component passing through the second polarization control unit 15. It is set so that the total amount of energy is the same or nearly the same.
In the first embodiment, as shown in FIG. 8, the first polarization control unit 13 is configured by one polarization control element 13a, and the second polarization control unit 15 is also configured by one polarization control element 15a. Has been. The width Wa1 in the arrangement direction of the polarization control element 13a and the width Wa2 in the arrangement direction of the polarization control element 15b (Wa1 = Wa2 in FIG. 8) are n times the width Wb of the convex cylindrical lens 17a of the cylindrical lens array 17 ( Where n
Can be an integer of 2 or more. In this case, the width Wc in the arrangement direction of the beam on the incident surface of the pulse laser beam to the polarization control member 9 is set to the convex cylindrical lens 17.
The width ab is preferably m times (where m is an integer of 2 or more). Thereby, not only can the number of polarization control elements 13a and 15a be reduced, but also the polarization control elements 13a and 15a.
The beam component that has passed through a can be irradiated over the entire laser irradiation region on the laser irradiation surface with respect to the arrangement direction. Thereby, the polarization control elements 13a, 15a
Even if the number is reduced, it is possible to prevent a portion where the energy density of the first polarization state or the second polarization state is relatively high in the laser irradiation region. In the example of FIG. 8, the polarization control element 1
3 and one polarization control element 15 are provided. However, when other numbers of polarization control elements are provided, Wa1 = n1 × Wb, Wa2 = n2 × Wb, Wc = m × Wb (however, , N1, n2, and m are integers of 2 or more), the same effect can be obtained.

The present invention is not limited to the above-described embodiment, and various changes can be made without departing from the scope of the present invention.

For example, the first polarization control unit 13 (polarization control elements 13a to 13c) and the second polarization control unit 15 (polarization control elements 15a and 15b) are arranged in the vertical direction of FIG. It is not limited. For example, in FIG. 2, when the cross-sectional shape perpendicular to the traveling direction of the pulse laser beam incident on the polarization control member 9 also extends in the direction perpendicular to the paper surface of FIG. 13 (polarization control elements 13a to 13c) and the second polarization control unit 15 (polarization control elements 15a and 15b) may be arranged in a direction perpendicular to the paper surface of FIG. 2 as in the vertical direction of FIG. The same applies to other cases such as FIG.

3 ... 1st laser resonator (1st laser light source), 4 ... 2nd laser resonator (2nd
5 ... Pulse control device, 7 ... Optical path combining optical member, 8 ... Beam expander, 9 ... Polarization control member, 10 ... Laser irradiation device, 11 ... Beam superimposing optical member, 12... Short-side condensing lens, 13... First polarization controller, 13
a, 13b, 13c ... polarization control element, 15 ... second polarization control unit, 15a, 15b
... Polarization control element, 17 ... Cylindrical lens array, 17a ... Convex cylindrical lens, 18 ... Condenser lens, 19 ... Polarization control member, 21 ... First
Polarization control unit, 21a, 21b, 21c ... polarization control element, 23 ... second polarization control unit, 23a, 23b ... polarization control element

Claims (1)

A first laser light source that emits a polarized pulsed laser beam;
A second laser light source that emits a pulsed laser beam having a polarization state different from that of the pulsed laser beam from the first laser light source;
An optical path combining optical member that combines the pulse laser beams from the first laser light source and the second laser light source on the same optical path;
A polarization control member that controls a polarization state of the pulse laser beam from the optical path combining optical member,
The polarization control member is disposed in a direction orthogonal to the traveling direction of the pulse laser beam, and includes one first polarization control element and one second polarization control element through which the beam components of the pulse laser beam pass, respectively. Configured,
The first polarization control element and the beam component that have passed through the first polarization control element and the beam component that has passed through the second polarization control element have different polarization states. A second polarization control element is disposed;
The have a beam superposing optical element for superimposing the laser irradiation surface on the beam components between the laser irradiated body of different polarization states to each other,
The beam superimposing optical member has a cylindrical lens array including a plurality of convex cylindrical lenses,
The first polarization control element and the second polarization control element each have a width n times (where n is an integer of 2 or more) the width of the convex cylindrical lens,
The pulse laser beam on the plane of incidence of the pulse laser beam on the polarization control member has a width of m times (where m is an integer of 2 or more) the width of the convex cylindrical lens. Laser irradiation device.