JP3349371B2 - Beam homogenizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beam homogenizer for uniformizing the intensity distribution of a light beam in a cross section.

[0002]

2. Description of the Related Art A cylinder array type beam homogenizer includes two pairs of cylinder arrays each including a front cylinder array and a rear cylinder array, and a focus lens. Each cylinder array is configured by arranging a plurality of equivalent cylindrical lenses in a direction perpendicular to the optical axis plane. The optical axis surfaces of the cylindrical lenses of the preceding cylinder array are arranged so as to coincide with the optical axis surfaces of the corresponding cylinder arrays of the subsequent cylinder array. Here, the optical axis plane means a plane of symmetry of an imaging system which is plane-symmetrical to the cylindrical lens. The intersection of the plane perpendicular to the cylindrical surface of each cylindrical lens and the optical axis plane is called the optical axis. The two cylinder array pairs are arranged such that the optical axes of the cylindrical lenses are parallel to each other and the optical axis surfaces are orthogonal to each other.

[0003] When a light beam enters a cylinder array at the preceding stage of one cylinder array pair, the light beam is converged by each cylindrical lens. Each converged light beam is converged again by each cylindrical lens of the cylinder array at the subsequent stage of the cylinder array pair. In this way, the two cylinder arrays divide the incident light beam into small light beams corresponding to the number of the cylindrical lenses.

[0004] Depending on the relative positions of the two cylinder arrays, the obtained small light beam becomes divergent light, parallel light, or convergent light. By superimposing the small light beams on a certain surface using the focus lens group, it is possible to make the light intensity distribution in the irradiation area uniform in the direction perpendicular to the optical axis plane of the cylindrical lens. The surface on which the light beams are superimposed is called a homogenized surface.

[0005] The two cylinder array pairs make it possible to make the light intensity distribution in the irradiation area uniform in two axial directions orthogonal to each other in a plane perpendicular to the optical axis.

Consider a case where excimer laser light whose light intensity changes in a plane perpendicular to the optical axis is incident on a cylinder array type beam homogenizer. The excimer laser light has a substantially uniform light intensity distribution on the homogenized surface. When the substrate is placed on the homogenized surface, a part of the surface of the substrate can be uniformly irradiated with laser light.

[0007]

The excimer laser light is
The direction in which the electrodes of the laser device face each other (electrode direction)
The divergence angle of the beam is different between the beam and the direction perpendicular thereto. For this reason, for example, when the laser beam is designed as light collimated in both directions in the optical design, since the spread angle is actually different between the two, different focus points are set in both axes in the electrode direction and the direction perpendicular thereto. Will happen. Even if the lens is designed in consideration of the divergence angle of both axes, the divergence angle also depends on various adjustments inside the laser, so that a beam with the expected divergence angle may not be obtained. A phenomenon occurs in which the focus points are different between the two axes.

When the substrate is placed at a position homogenized in the electrode direction, the light intensity distribution in the irradiation area becomes almost uniform in the electrode direction, but does not become uniform in the direction perpendicular to the electrode direction. As described above, the light intensity distribution in the light irradiation area on the substrate surface cannot be made uniform simultaneously in two directions, the electrode direction and the direction orthogonal thereto.

An object of the present invention is to provide a beam homogenizer capable of simultaneously making light intensity distributions in two directions orthogonal to each other on a light irradiation surface uniform.

[0010]

According to one aspect of the invention, an incident light beam is defined for each of a first direction and a second direction orthogonal to each other in a virtual plane perpendicular to the optical axis of the incident light beam. A homogenizing optical system for equalizing the light intensity distribution of the light, and at least one convex cylindrical lens and one concave cylindrical lens disposed on the incident side of the homogenizing optical system, wherein the first direction and the second direction are related to each other. A beam homogenizer having a divergence angle correcting optical system that can independently change the divergence angle of the light beam and makes the light beam with the divergence angle independently changed incident on the homogenizing optical system.

The divergence angle of the incident light beam in the first direction can be corrected with respect to the divergence angle in the second direction by using the divergence angle correcting optical system. Thereby, the homogenized surface in the first direction and the homogenized surface in the second direction by the homogenizing optical system can be made to coincide with each other.

[0012]

FIG. 1 is a sectional view of a beam homogenizer according to an embodiment of the present invention. Consider an xyz rectangular coordinate system having a z-axis parallel to the optical axis of a light beam incident on a beam homogenizer. FIG. 1A is a sectional view parallel to the yz plane, and FIG. 1B is a sectional view parallel to the xz plane.

As shown in FIG. 1A, the generatrix directions of seven equivalent cylindrical lenses are respectively oriented in the x-axis direction.
The cylinder arrays 1A and 1B are arranged in the y-axis direction and along a virtual plane parallel to the xy plane. The optical axis plane of each cylindrical lens of the cylinder arrays 1A and 1B is parallel to the xz plane, and the generatrix of the cylindrical surface is parallel to the x axis. Here, the optical axis plane means a plane of symmetry of a plane-symmetric imaging system of a cylindrical lens. The cylinder array 1A is arranged on the light incident side (left side in the figure), and the cylinder array 1B is arranged on the light outgoing side (right side in the figure).

As shown in FIG. 1B, the generatrix directions of the equivalent seven cylindrical lenses are respectively oriented in the y-axis direction.
The cylinder arrays 2A and 2B are arranged in the x-axis direction and along a virtual plane parallel to the xy plane. The optical axis plane of each cylindrical lens of the cylinder arrays 2A and 2B is parallel to the yz plane, and the generatrix of the cylindrical surface is parallel to the y axis. The cylinder array 2A is arranged in front of the cylinder array 1A (left side in the figure), and the cylinder array 2B is arranged between the cylinder arrays 1A and 1B. The optical axis planes of the corresponding cylindrical lenses of the cylinder arrays 1A and 1B match, and the optical axis planes of the corresponding cylindrical lenses of the cylinder arrays 2A and 2B also match.

A converging lens 3 is arranged behind the cylinder array 1B. The optical axis of the converging lens 3 is parallel to the z-axis.

The cylindrical lenses 4A and 4B are arranged on the incident side of the cylinder array 2A. The cylindrical lens 4A is a convergent lens, and the cylindrical lens 4B is a divergent lens. The optical axis surfaces of the cylindrical lenses 4A and 4B coincide with the optical axis surface of the central cylindrical lens of the cylinder array 2A, and the generatrix of the cylindrical surface is parallel to the y-axis.

Consider a case where the beam homogenizer shown in FIG. 1 has an optical axis parallel to the z-axis, a ray bundle 10 which is substantially parallel in the yz plane and slightly diverges in the xz plane. The light beam 10 is represented by a curve 21y in FIG. 1A with respect to the y-axis direction and FIG.
As shown by the curve 21x in (B), the light intensity distribution is strong at the center and weak at the periphery.

Referring to FIG. 1A, the state of propagation of a light beam in the yz plane will be described. In the yz plane,
Since the cylinder arrays 2A and 2B and the cylindrical lenses 4A and 4B are simply flat plates, they do not affect the convergence and divergence of the light beam. Cylindrical lens 4A
From the left, a light beam 10 having an optical axis parallel to the z-axis enters the cylindrical lens 4A.

The light beam 10 has a cylindrical lens 4A,
4B and the cylinder array 2A, and enter the cylinder array 1A. The incident light beam is divided into seven convergent light beams corresponding to each cylindrical lens by the cylinder array 1A. In FIG. 1A, only the light beams at the center and both ends are representatively shown. The seven convergent light beams have light intensity distributions indicated by curves 21ya to 21yg in the y-axis direction, respectively. The light beam converged by the cylinder array 1A is converged again by the cylinder array 1B.

Each of the seven converging light beams 12 converged by the cylinder array 1B forms an image in front of the converging lens 3. This imaging position is closer to the lens than the focal point on the entrance side of the converging lens 3. Therefore, the light transmitted through the converging lens 3
The two light beams become divergent light beams, and overlap on the homogenizing surface 5. Irradiate the homogenized surface 5 7
The light intensity distribution of the two light beams in the y-axis direction is equal to the distribution obtained by extending the light intensity distributions 21ya to 21yg in the y-axis direction. Since the light intensity distributions 21ya and 21yg, 21yb and 21yd, and 21yc and 21ye have respective inverted relations in the y-axis direction, the light intensity distributions obtained by superimposing these light fluxes are uniform as shown by the solid line 22y. Approach distribution.

Referring to FIG. 1B, the state of propagation of a light beam in the xz plane will be described. In the xz plane,
Since the cylinder arrays 1A and 1B are simply flat plates,
Does not affect the convergence and divergence of the light beam. When the light beam 10 passes through the cylindrical lenses 4A and 4B, it becomes a light beam 11 that is substantially parallel in the xz plane. By adjusting the interval between the cylindrical lenses 4A and 4B according to the spread angle of the incident light beam 10, a light beam 11 that is substantially parallel in the xz plane can be obtained. The light beam 11 enters the cylinder array 2A.

The light beam 11 is divided into seven convergent light beams corresponding to the respective cylindrical lenses by the cylinder array 2A. FIG. 1B shows only the light beams at the center and both ends as representatives. The seven convergent light beams have light intensity distributions indicated by curves 21xa to 21xg in the x-axis direction, respectively.

Each light beam is condensed in front of the cylinder array 2B, and enters the cylinder array 2B as a divergent light beam. Each ray bundle incident on the cylinder array 2B exits at a certain exit angle, and enters the converging lens 3.

Each of the seven light beams transmitted through the converging lens 3 becomes a convergent light beam and overlaps on the homogenizing surface 5. X of seven ray bundles illuminating the homogenized surface 5
The light intensity distribution in the axial direction approaches a uniform distribution as shown by a solid line 22x as in the case of FIG.

Light beam 11 incident on cylinder array 2A
Can be considered as a ray bundle that is parallel in both the x-axis direction and the y-axis direction. Therefore, the homogenized surface in the yz plane coincides with the homogenized surface in the xz plane. On the other hand, the cylindrical lenses 4A and 4A
If B is not arranged, the homogenized planes in the yz plane and the xz plane may not match. For example, if the divergence angle of the light beam 10 in the xz plane is different by 1 mrad, the homogenized surface may be shifted from several mm to several tens mm depending on the optical system used.

With the cylindrical lenses 4A and 4B,
Since the light beam 11 is substantially a parallel light beam, the substrate surface to be irradiated with the laser beam is disposed at the position of the homogenized surface 5 so that a partial area of the substrate surface is moved in the x axis direction and the
Irradiation can be performed almost uniformly in the axial direction.

In the above embodiment, the case where the divergence angle of the incident light beam is adjusted by combining the convergent cylindrical lens and the divergent cylindrical lens has been described. Other optical systems may be used as long as the divergence angle in one axial direction in a plane perpendicular to the optical axis of the incident light beam is changed and the divergence angle in the axial direction perpendicular thereto is not changed. Further, more generally, an optical system that can independently change the spread angles of the light beam in two directions may be used. For example, two sets of optical systems combining cylindrical lenses may be provided.

In the above embodiment, the case where the incident light beam 10 is a parallel light beam in the yz plane and a divergent light beam in the xz plane in FIG. 1 has been described. Need not be. Divergent light beams having different divergent angles in the yz plane and the xz plane may be used. In this case, the distance between the cylindrical lenses 4A and 4B is adjusted to correct the relative divergence angle between the two in the yz plane and the xz plane. With this correction, the homogenized positions in the yz plane and the xz plane can be matched.

Next, a laser annealing apparatus using the beam homogenizer shown in FIG. 1 will be described.

FIG. 2 is a schematic plan view of the laser annealing apparatus. The housing 50 includes a processing chamber 51, a transport chamber 52, a loading chamber 53, a loading chamber 54, a homogenizer 42, a CCD camera 58, and a video monitor 5.
9 is attached.

The processing chamber 51 and the transfer chamber 52 are connected via a gate valve 55, and the transfer chamber 52 and the load chamber 53, and the transfer chamber 52 and the discharge chamber 54 are connected via gate valves 56 and 57, respectively. I have. Processing chamber 51, loading chamber 53
The vacuum pump 61,
62 and 63 are attached, and the inside of each chamber can be evacuated.

A transfer robot 64 is housed in the transfer chamber 52. The transfer robot 64 transfers the processing substrate between the processing chamber 51, the loading chamber 53, and the unloading chamber 54.

On the upper surface of the processing chamber 51, a window 60 for transmitting laser light is provided. The laser beam output from the excimer laser device 41 having pulsed oscillation enters the homogenizer 42 through the attenuator 46. The homogenizer 42 makes the cross section of the laser beam into an elongated shape. The laser beam that has passed through the homogenizer 42 passes through an elongated window 60 corresponding to the cross-sectional shape of the laser light, and irradiates the processing substrate in the processing chamber 51. Homogenizer 4 so that the surface of the processing substrate coincides with the homogenizer surface.
The relative position between 2 and the processing substrate is adjusted.

The processing substrate moves in parallel in a direction perpendicular to the long axis direction of the window 60. By moving the processing substrate at such a speed that a part of the irradiation area for one shot overlaps a part of the irradiation area in the previous shot, a large area on the surface of the processing substrate can be irradiated. Processing substrate surface is CC
The substrate surface being photographed by the D camera 58 and being processed can be observed on the video monitor 59.

Excimer laser device 41, homogenizer 4
2. The operations of the transfer robot 64 and the gate valves 55 to 57 are controlled by the control device 65.

FIG. 3 is a schematic diagram showing an optical system of the laser annealing apparatus shown in FIG. The laser beam output from the excimer laser device 41 passes through the attenuator 46, is reflected by the turn mirrors 47 and 48, and enters the homogenizer 42. The laser beam that has passed through the homogenizer 42 is reflected by the turn mirror 49, passes through the glass window 60, and is introduced into the processing chamber 51.

The homogenizer 42 and the turn mirror 49
The parallel movement along the optical axis of the incident laser light can be performed while maintaining the mutual relative positional relationship. Turn mirror 4
When the laser beam reflected at 9 is at position c in the figure, the processing substrate 51 in the processing chamber 51 is irradiated with laser light.

In the processing chamber 51, a power meter 7 is provided.
2 are arranged. When the laser beam is moved to the position d, the laser beam is irradiated on the power meter 72, and the intensity of the laser beam can be measured. A power meter 73 is also provided outside the processing chamber 51, and the intensity of the laser beam before being introduced into the processing chamber 51 can be measured by moving the laser beam to the position b.

Outside the processing chamber 51, a beam profiler 74 in which optical sensors are linearly arranged is arranged. By moving the laser beam to the position a and irradiating the laser beam to the beam profiler 74, it is possible to measure the intensity distribution of the laser beam having a linear cross-sectional shape in the major axis direction in the cross section.

A power meter 70 is arranged between the attenuator 46 and the turn mirror 47, and a power meter 71 is arranged between the turn mirror 48 and the homogenizer 42. The power meters 70 and 71 can measure the intensity of the laser beam at that position.

By comparing the intensity of the laser light detected by the power meters 70 to 73 with the normal value at each position, it is possible to know the state of deterioration of each optical component. Further, by analyzing the detection signal from the beam profiler 74, the normality of the intensity distribution in the major axis direction of the cross section of the laser beam can be confirmed.

As described in the embodiment of FIG. 1, by arranging the cylindrical lenses 4A and 4B, the light intensity distribution can be made nearly uniform at the same time in two directions on the irradiation surface. Since the light intensity distribution per one shot approaches uniformity, the entire surface of the substrate can be evenly irradiated with laser light.

The present invention has been described in connection with the preferred embodiments.
The present invention is not limited to these. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

[0044]

As described above, according to the present invention,
The homogenized surfaces in each of two mutually orthogonal axial directions in the irradiation surface can be made to coincide with each other. Therefore, the light intensity distribution on the irradiation surface can be made more uniform.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a beam homogenizer according to an embodiment of the present invention.

FIG. 2 is a plan view schematically showing a laser annealing apparatus using the beam homogenizer shown in FIG.

FIG. 3 is a diagram showing an optical system of the laser annealing apparatus shown in FIG.

[Explanation of symbols]

 Reference Signs List 1A, 1B, 2A, 2B Cylinder array 3 Converging lens 4A, 4B cylindrical lens 5 Homogenized surface 10, 11 Light beam 12 Divided light beam 21x, 21y, 22x, 22y Light intensity distribution 41 Excimer laser device 42 Homogenizer 46 Attenuator 47 , 48, 49 Turn mirror 50 Housing 51 Processing chamber 52 Transfer chamber 53, 54 Loading / unloading chamber 55-57 Gate valve 58 CCD camera 59 Video monitor 60 Window 61, 62, 63 Vacuum pump 64 Transfer robot 65 Control device 70, 71 , 72, 73 Power meter

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02B 27/00 H01L 21/30

Claims (2)

(57) [Claims] 1. A homogenizing optical system for equalizing the light intensity distribution of an incident light beam in each of a first direction and a second direction orthogonal to each other in a virtual plane perpendicular to the optical axis of the incident light beam. And at least one convex cylindrical lens and at least one concave cylindrical lens disposed on the incident side of the homogenizing optical system, and independently changing the spread angle of the light beam in the first direction and the second direction. Can be
A beam homogenizer having a divergence angle correcting optical system for causing a light beam whose divergence angle is independently changed to enter the homogenizing optical system. 2. The homogenizing optical system according to claim 1, wherein the plurality of first cylindrical lenses have their generatrix and optical axis plane parallel to the first direction and arranged in the second direction. A second cylinder in which a first cylinder array and a plurality of second cylindrical lenses are arranged such that a generating line and an optical axis surface of each cylindrical surface are parallel to the first direction and are arranged in the second direction; An array, wherein each of the second cylindrical lenses has a common optical axis plane with the corresponding first cylindrical lens, and a light beam transmitted through the first cylindrical lens is used by a corresponding second cylindrical lens. The second incident on the
And a third cylinder array in which a plurality of third cylindrical lenses make the generatrix of each cylindrical surface and the optical axis surface parallel to the second direction, and are arranged in the first direction. The third cylinder array in which each optical axis surface of the third cylindrical lens is orthogonal to the optical axis surfaces of the first and second cylinder arrays; and the plurality of fourth cylindrical lenses are each A fourth cylinder array in which the generatrix of the cylindrical surface and the optical axis surface are parallel to the second direction, and are arranged in the first direction, wherein each of the fourth cylindrical lenses corresponds to the corresponding cylindrical lens. An optical axis plane is shared with the third cylindrical lens, and the light beam transmitted through the third cylindrical lens is incident on the corresponding fourth cylindrical lens.
The beam homogenizer according to claim 1, further comprising: a cylinder array; and a converging optical system that converges a light beam transmitted through the first to fourth cylinder arrays.