JP3216987B2 - Laser transfer processing apparatus and laser transfer processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser transfer processing apparatus and a laser transfer processing method for efficiently processing a workpiece with an arbitrary irradiation intensity distribution by using a light transmission type hologram as a processing optical system. It is.

[0002]

2. Description of the Related Art FIG.
1 is a configuration diagram illustrating a schematic configuration of a conventional laser transfer processing apparatus disclosed in SPIE, Vol. 1377, pp. 30-35. In the figure, a laser beam (hereinafter, referred to as a beam) emitted from a laser oscillator 1 is applied to a mask 6 with a uniform intensity distribution through a mask irradiation beam homogenizing optical system 3. The mask pattern image by the beam transmitted through the mask 6 is transferred by the transfer lens 7 to the deflection mirror 2.
After that, the light is deflected to a processing target (hereinafter, referred to as a target) 8 as a processing target to form an image.

Next, the operation of the conventional apparatus will be described. A beam emitted from a laser oscillator 1 which is, for example, an excimer laser is applied to a beam homogenizing optical system 3 for mask irradiation.
Thus, the light is irradiated onto the mask 6 with a uniform intensity distribution.
A mask pattern image formed by a beam transmitted through the transfer pattern of the mask 6 is formed as a transfer image on a target 8 by a transfer lens 7, and laser processing is performed. The beam transferred by the transfer lens 7 is deflected by the deflecting mirror 2 in the direction of the target 8 before being irradiated on the target 8 to form an image.

In addition, for example, Applied Opti
cs Vol.13 No.2 p269-273, JP-A-51-73698, JP-A-54-102692, JP-A-57-81986, Applie
d Optics Vol. 30 No. 25 p3604
Another conventional device disclosed in US Pat.
In order to perform processing similar to that of the laser transfer processing apparatus shown in FIG. 1, a hologram is used in a processing optical system.

[0005] As an example of using a hologram for the processing optical system, there is a processing optical system schematically shown in FIG. This processing optical system is called “Applied Optics
Vol. 13 No. 2 pp. 269-273, Modulated Zo which is a kind of hologram
A hologram element called ne Plate is used.

In the figure, a beam emitted from a laser oscillator 1 is expanded by a beam expanding optical system 11, and a pattern image of the expanded beam is irradiated on a target 8 by diffraction by a hologram 5. The hologram 5 has interference fringes formed on the surface along the processing pattern.

Next, the operation of the conventional apparatus using the hologram 5 for the processing optical system will be described. The beam emitted from the laser oscillator 1 is expanded through the beam expanding optical system 11 and is diffracted by the hologram 5 so that the target 8
Irradiated in the form of a processing pattern above. As a result, a certain pattern can be laser-processed on the target 8.

As another processing optical system using a hologram, there is a laser processing apparatus disclosed in Japanese Patent Application Laid-Open No. 57-81986 as shown in FIG. The configuration of the processing optical system of this apparatus is almost the same as that of the processing optical system shown in FIG. 20, and the arrangement of the optical system elements is different. When the beam emitted from the laser oscillator 1 passes through the beam expanding optical system 11, it is expanded, enters the hologram 5, and is diffracted.

The beam diffracted from the hologram 5 is imaged on the target 8 so as to have a predetermined processing pattern, and reproduces the processing pattern on the processing surface. Thus, the target 8 is laser-processed into a predetermined pattern.
The basic configuration of the processing optical system is the same as that of the processing optical system shown in FIG.

[0010]

Since the conventional apparatus is constructed as described above, most of the beam irradiated on the mask does not pass through the mask 6, for example, hitting the light shielding portion of the mask. There is a problem that the beam use efficiency is significantly reduced. For example, in a transfer processing method using an excimer laser, generally, only a small portion of the inner surface of the entire surface of a target is irradiated with a laser and processed.

Further, in laser processing for forming a hole for electric conduction in a polyimide substrate for mounting an electronic circuit, a hole having a diameter of about 100 μm is formed per cm ² of the polyimide substrate.
Laser processing for opening about 00 pieces is common. In such a case, the ratio of the area actually laser-processed to all the surfaces to be processed is 0.8% or less. Therefore, when such processing is performed by the laser processing apparatus using the conventional processing optical system shown in FIG. 19, most of the energy of the beam is lost by the light shielding portion of the mask. Therefore, there is a problem that the energy actually used for processing is 0.8% or less of the output of the laser oscillator, and the beam use efficiency in laser transfer processing is extremely low.

In the case of irradiating a beam one spot at a time in order to machine holes one by one, as in the case of drilling a hole in an electronic substrate, for example, the area to be illuminated is narrowed for effective use of light. There is also a processing method of scanning a large number of holes along a drilling processing position.

However, in order to substantially increase the light use efficiency by narrowing the irradiation area, most of the beam irradiation area must transmit light, so that the irradiation area becomes extremely small. In the case of drilling, one or two holes are formed. Therefore, it is necessary to divide the entire processing area into small pieces and sequentially process them. If such a method of sequentially processing is employed, there is a problem that much time is required for beam scanning and the associated irradiation positioning, and the processing time becomes long, resulting in an inefficient processing method.

Further, the processing optical system constituted by using the hologram is for improving the defect of the transfer optical system for forming an image of the processing pattern on the target by using the mask.
However, in a conventional processing optical system using a hologram as shown in FIG. 21, in order to reproduce a correct processing pattern by the hologram, a beam having a very high spatial and temporal coherence must be applied.

In a processing method using a hologram, the reproduction pattern of the hologram, which is a processing pattern, directly depends on the property (coherence) of the irradiated beam. That is, the processing pattern and the processing accuracy by such a processing method are determined by the performance of the hologram and the properties of the irradiation beam. Therefore, when a laser having low spatial coherence, such as an excimer laser, is used, in order to obtain an accurate processing pattern, as shown in, for example, Keigo Iizuka, “Optical Engineering”, pp. 250-252. The spatial coherence must be enhanced using a spatial filter.

In the spatial filter, as shown in FIG. 23, a plate 13 having a pinhole having a very small diameter is provided at a focal position of a lens 24 to remove light of a disturbed wavefront in a beam. To remove the distorted wavefront, a pinhole with a diameter equal to the width of the main probe of the beam at the focal position is used. However, with a beam having low spatial coherence, the energy transmittance of the spatial filter is greatly reduced, so that a high laser use efficiency cannot be achieved.

Therefore, a processing optical system using a hologram can be used only for a laser having a very high coherence, and an excimer laser having a relatively low spatial coherence can be used for a processing optical system using a hologram. Could not be applied.

Therefore, the conventional laser transfer processing apparatus is inefficient, and if the processing time is to be reduced, the laser oscillator must be operated at a high output at the expense of the life and stability. Was unreliable. In addition, a conventional laser processing apparatus using a hologram can be applied only to a beam having an extremely high spatial coherence, and a spatial filter for an excimer laser or the like having a relatively low spatial coherence. However, there is a problem that an optical system for enhancing coherence must be used, and high laser use efficiency cannot be achieved.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a laser transfer processing apparatus and a laser transfer processing method capable of achieving high laser use efficiency in a laser processing optical system formed using holograms. The purpose is to obtain a processing method.

[0020]

SUMMARY OF THE INVENTION In view of the foregoing, the present invention provides a laser oscillator and a laser oscillator.
A focusing lens that focuses the focused laser beam,
The laser beam is applied to the processing pattern on the workpiece.
And a mask that allows the light to pass through the opening
Transfer the mask pattern image transmitted through the mask to the workpiece.
Transfer lens, from the beam emission side of the laser oscillator
Located at any point in the optical path to the mask,
An interference fringe pattern was formed to match the mask pattern
A hologram, and divided by the hologram.
Each beam is shaped according to the opening shape of the mask.
In the laser transfer processing device, the work piece is
Spatial coherence of the laser beam in the optical path to
That the coherence reducing means for reducing
It is in the laser transfer processing device. Also, coherent
Means for lowering the laser beam
Plurality of thick and thin optical areas in random order
The phase plate according to claim 1, wherein
User transfer processing equipment. Also, means for reducing coherence
Is a process for fine irregularities on the transparent substrate surface through which the laser beam passes.
2. The diffusion plate as claimed in claim 1, wherein
Laser processing machine. Also, the interference fringe pattern
Optical hologram on the opposite surface of the hologram substrate
A plurality of thick and thin regions are formed in random order and
A phase difference is generated between the laser beams passing through these regions.
Phase plane that reduces spatial coherence
The laser transfer processing apparatus according to claim 1, wherein:
It is in. A hologram with an interference fringe pattern formed on one side
The surface of the ram opposite to the substrate is subjected to fine irregularities to
Diffuses the laser beam to reduce spatial coherence
2. The method according to claim 1, wherein a diffusion surface is formed.
Laser processing machine. Also, the interference fringe pattern
On the substrate surface of the formed hologram, the optical thickness is
A plurality of regions and thin regions are formed in random order, and these regions are transparent.
Phase difference between the laser beams
That it has at the same time form a phase plane to lower the Hirensu
The laser transfer processing apparatus according to claim 1,
You. Also, a hologram substrate with an interference fringe pattern
The surface is subjected to fine unevenness processing to spread the transmitted laser beam.
Diffuse surfaces that scatter and reduce spatial coherence
2. The laser transfer process according to claim 1, wherein
In the construction equipment. In addition, the laser emitted from the laser oscillator
The beam is focused by a focusing lens and this focused laser
-Match the beam to the machining pattern for the workpiece
Transmit the light through the opening of the opened mask, and
Pattern image is transferred to the workpiece by a transfer lens.
At this time, the laser beam transmitted through the mask is
Hologram with interference fringe pattern formed
Ram and split it into several parts.
The beam is shaped according to the opening shape of the mask,
A number of laser beams split by the ram
Above, partially overlap each other and within a certain range
Laser transfer processing to create an irradiation area with an intensity distribution
Method, divided by a hologram and on a mask
Holographic spacing of the superposed laser beams
Of each laser beam divided by
A laser characterized by having a pot diameter (half width) or less.
Transfer processing method. It is also superimposed on the mask
Of the spot diameter to the laser beam superposition interval
Desired uniformity on the mask, with the ratio of the half width being FP%
Is ± Er%, the condition of Er ≧ 1.12√FP
9. The FP is set to satisfy the condition.
In the laser transfer processing method described in (1). The laser beam width d of the laser beam incident on the hologram, the focal length f of the condenser lens, and the incident side NA of the transfer lens are (d
The laser transfer processing method according to claim 8, wherein the relationship of (/ 2) ≦ f · NA is satisfied.

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Hereinafter, embodiments of the present invention will be described. FIG. 1 is a diagram showing a laser transfer processing apparatus according to the present embodiment. The laser beam emitted from the laser oscillator 1 is divided into a number of beams traveling in any directions by a hologram. The beam split by the hologram 9 is condensed by the condensing lens 10 and
Is irradiated. The mask pattern image transmitted through the mask 6 is formed as a transfer image on the target 8 by the transfer lens 7.

Next, the operation of this embodiment will be described. The laser light exiting the laser oscillator 1 is split by the hologram 9 into a number of beams traveling in arbitrary directions. Then, the respective beams are condensed by the condensing lens 10 and irradiated onto the mask 6. The mask pattern image formed by the beam transmitted through the pattern of the mask 6 is formed as a transfer image on the target 8 by the transfer lens 7, and laser processing is performed.

Since the beam is split by the hologram 9 into a beam traveling in an arbitrary direction, each of the split beams is condensed by the condensing lens 10 and irradiated on the mask 6. Numerous irradiation spots obtained by irradiation are
The hologram 9 can be arranged at any position on the mask 6 by the interference fringe pattern.

Therefore, if the interference fringe pattern is formed corresponding to the shape of the opening of the mask 6, each irradiation spot can be selectively arranged on the opening on the mask 6. As a result, it is possible to reduce the number of beams that needlessly irradiate the light-shielding portion of the mask, so that the laser energy consumed by the light-shielding portion of the mask is almost eliminated, and high-efficiency laser processing with high laser utilization can be performed. .

In the case of a processing pattern in which a large number of drilling positions are distributed on the processing surface, one irradiation spot is formed at intervals on each opening on the mask 6 by the above-described method. It should just be arranged. However, it is conceivable that the processing pattern has a complicated shape as shown in FIG.

For such a complicated processing shape, as shown in FIG. 2B, a number of irradiation spots are arranged so as to partially overlap each other along the processing shape, and the irradiation intensity within the processing pattern is reduced. By making adjustments to be constant, stable laser processing can be performed with high efficiency even for complicated processing patterns.

When a large number of processing patterns are processed simultaneously, when the processing depth of each processing pattern is different, it is necessary to change the beam irradiation intensity for each processing pattern. For such processing, the target 8 can be set at different depths for each processing pattern without adjusting the output of the laser oscillator 1 by arbitrarily selecting the intensity ratio of each beam split by the hologram 9. Can be processed.

Embodiment 2 FIG. 3 is a configuration diagram of a laser transfer processing apparatus provided with a reduction optical system for reducing the beam width of the beam emitted from the laser oscillator 1. In the drawing, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts. FIG.
Reference numeral 14 denotes a reduction optical system that reduces the beam width of the beam 4 emitted from the laser oscillator 1. The reduction optical system 14 includes a convex lens and a concave lens.

Next, the operation of this embodiment will be described. The beam 4 is incident on the reduction optical system 14, and the beam diameter is reduced. Thereafter, the beam 4 is divided into a plurality of beams 4a after being shaped by the hologram 9. Each beam 4a is condensed by the condensing lens 10 and is irradiated on the surface of the mask 6. An opening having a shape corresponding to the processing pattern is provided on the surface of the mask 6. The beam transmitted through the opening has a beam profile formed by the mask 6, is reduced to an arbitrary magnification by the transfer lens 7, and is transferred to the processing surface of the target 8.

Next, the role and effect of the reduction optical system 14, which is one of the features of the present embodiment, will be described. One of the roles of the reduction optical system 14 is to effectively use the beam 4. In order to use the beam 4 effectively, when the beam 4 enters the transfer lens 7 through the reduction optical system 14, the hologram 9, the condenser lens 10, and the mask 6, the incident side NA (Numerical Apertur) of the transfer lens 7 is used.
e), the following relationship needs to be established between the beam width d of the beam 4 incident on the hologram 9 and the focal length f of the condenser lens.

(D / 2) ≦ f · NA

This means that the reduction optical system 14 is provided before the hologram 9.
And the beam width d of the beam 4 is reduced. By configuring the optical system in this manner, since the divergence angle of the beam after passing through the mask 6 is large, a part of the beam is not lost while passing through the transfer lens 7, and the beam is effectively used. be able to. When the reduction optical system 14 is omitted, the incident side N of the transfer lens 7 is set in advance.
A needs to be designed with a large value.

Embodiment 3 Next, a method of making the intensity distribution of the beam on the mask 6 uniform will be described. FIG.
Represents the degree of overlap 15 of the beam spots divided by the hologram 9 and focused on the mask 6 by the focusing lens 10.

The beams split in a plurality of arbitrary directions by the hologram 9 are respectively focused on the mask 6 by the focusing lens 10. At this time, an arbitrary beam intensity distribution appears on the mask 6 surface on which the beams are superimposed.

Therefore, in order to obtain a uniform intensity distribution as a whole, it is necessary to set the spot diameter of each beam and the superimposing pitch of adjacent spots to optimum values. In order to make the intensity distribution uniform, it is necessary to change the overlapping pitch so as to satisfy the above conditions,
There are two methods for changing the width of the Gaussian distribution of the converging spot.

When the pitch of the superposition is changed, a large number of light beams having a Gaussian distribution condensed by the condenser lens 10 are superimposed on the mask 6 as shown in FIG. When the focused beam has a Gaussian distribution, the intensity distribution is uniformed if the superimposing pitch (p) is within about 70% of the half width.

When the width of the Gaussian distribution of the converging spot is changed, the divergence angle of the beam is changed by changing the distance between the condensing lens 10 and the mask 6 or changing the reduction ratio of the reduction optical system 14. Is changed, so that the width of the Gaussian distribution can be changed.

However, when the intensity distribution is made uniform by changing the overlapping pitch of the converging spots by the method of forming the interference fringe pattern of the hologram 9, if the converged beam is not Gaussian, The spot diameter of the beam and the interval of superposition are set under the above conditions (about 70% of the half width)
%). For example, when the focused beam is like a triangular wave, the overlapping pitch may be within the same order of magnitude as the spot diameter (half width) of each focused beam.

Embodiment 4 As in the second embodiment, the intensity of each beam divided by the hologram 9 and condensed by the condensing lens 10 may vary by about ± 10% depending on the production accuracy of the hologram 9. In such a case (when the value of E shown in FIG. 4 exists), it is necessary to further reduce the overlapping pitch p.

FIG. 5 shows the variation in the intensity of each beam divided by the hologram (Irregular).
%) Are 5% and 10%, the uniformity of the overall intensity (FWHM / Pitch%) with respect to the spot diameter of the beam on the mask surface (FWHM / Pitch%) with respect to the beam spot diameter (half-width of Gaussian distribution) Error%) is plotted on the vertical axis. As can be seen from FIG. 5, when the intensities of the beams vary, it is necessary to change the overlapping pitch depending on the magnitude of the variations in order to keep the overall intensity within a predetermined uniformity.

For example, the variation of each beam is ± 1.
In the case of 0%, the pitch needs to be within 20% of the half width of the Gaussian distribution of each beam in order to keep the uniformity within ± 5%.

When the intensity of each beam split by the hologram 9 is about ± 10%,
Assuming that the ratio of the half value width of the spot diameter to the interval of superposition of the beams superimposed on the mask 6 is FP% and the desired uniformity on the mask 6 is ± Er%, Er ≧
By setting the FP so as to satisfy the condition of 1.12√FP, the uniformity can be suppressed within a predetermined range.

One of the features of this optical system is that the uniformity can be suppressed within a predetermined range by using such a method when the intensity of the focused beam varies.

Embodiment 5 When the divergence angle changes due to the deterioration of the beam quality, the spot diameter on the mask 6 surface changes and the intensity of each focused beam changes.
In such a case, in order to keep the intensity distribution and the energy density of the beam having uniform intensity as a whole on the processing surface unchanged, the maximum and minimum values of the divergence angle (or spot diameter) that can be considered in advance are considered. It is necessary to set the overlapping pitch in consideration of the above.

The method of setting the pitch is such that the pitch is determined so as to satisfy the conditions of Embodiments 2 and 3 at the minimum value of the spot diameter (or divergence angle) of the focal point, and the spot diameter (or divergence) of the focal point is further determined. The number of condensed beams to be superimposed is determined so that the intensity distribution within the desired irradiation range becomes uniform at the maximum value of the angle. In this way, even if the beam quality deteriorates and the divergence angle changes, the uniformity of the intensity distribution within the desired irradiation range does not change, and the energy density is kept constant.

FIG. 6 shows that when the direction of the beam is taken in the Z direction, the maximum value of the spot diameter in the X direction is 80 μm, the minimum value is 40 μm, and the maximum value of the spot diameter in the Y direction is 100 μm.
This is a specific example in which the intensity distribution and the energy density do not change within a desired irradiation range when 0 μm and the minimum value are 300 μm.

When the desired irradiation range is set within the dotted line (± 200 μm in the X direction and ± 5000 μm in the Y direction) as shown in the figure, even if the spot diameter increases, only the slope of the foot of the Gaussian distribution becomes gentler. Does not change in the intensity distribution and the energy density within the irradiation range. At this time, the desired irradiation range should be set not as a one-dimensional linear shape but as a two-dimensional plane.

One of the features of this processing apparatus is that even if the divergence angle (or spot diameter) of the beam condensed by the above method changes, the intensity distribution or energy density changes within a predetermined irradiation range. It is possible to prevent it.

Embodiment 6 FIG. In each of the above Examples 1 to 5, the position of the hologram 9 is fixed on the optical axis, but in the present embodiment, the hologram 9 is moved in parallel with the optical axis to change the angle of the beam incident on the condenser lens 10. adjust.

FIGS. 7A and 7B are configuration diagrams showing a part of the processing optical system of the laser transfer processing apparatus according to the present embodiment. The hologram 9 is arranged along the optical axis in the order of the laser oscillator 1, the hologram 9, and the condenser lens 10. The beam emitted from the laser oscillator 1 and incident on the hologram 9 is split by the hologram 9 into a number of beams. These beams are respectively condensed by the condensing lens 10 to create a number of irradiation spots on the mask 6.

In such a configuration of the processing optical system, the mask 6 is moved by moving the hologram 9 in parallel with the optical axis.
Can be changed as shown in FIGS. 7 (a) and 7 (b). Mask 6
The beam transmitted through is then transferred to a transfer lens 7 (see FIG. 1).
Is incident on. When the beam incident on the transfer lens 7 is far away from the optical axis or is incident at a large angle with respect to the optical axis, each beam is transferred onto the target 8 (see FIG. 1) without aberration by the transfer lens 7. It is difficult to form an image. However, when the optical system is configured so that the hologram 9 can be moved in parallel with the optical axis, the angle of the beam incident on the condenser lens 10 can be adjusted, so that the performance of the transfer lens 7 can be effectively brought out.

In particular, when the hologram 9 is arranged at the focal position on the incident light side of the condenser lens 10, all the beams split by the hologram 9 enter the mask 6 perpendicularly to the condenser lens 10. By using the transfer lens 7 having the entrance side telecentric configuration, stable laser processing can be performed on the target 8.

When the distance between the condenser lens 10 and the mask 6 is maintained at the focal length of the condenser lens 10 with high accuracy,
Even if the hologram 9 is moved in parallel with the optical axis, the position of the irradiation spot on the mask 6 does not change, and only the angle of incidence on the mask 6 changes, thereby further increasing the stability of laser processing.

Embodiment 7 FIG. In the first to sixth embodiments, a processing optical system is configured by arranging an optical system element on the optical axis in the order of the hologram 9, the condensing lens 10, and the mask 6, but in the present embodiment, as shown in FIG. The hologram 9 is disposed between the condenser lens 10 and the mask 6. Therefore, the beam emitted from the laser oscillator 1 is condensed by the condensing lens 10 and is incident on the hologram 9, and after being divided into a number of beams by the hologram 9, creates a number of irradiation spots on the mask 6.

According to such an arrangement of the hologram 9,
Before the beam passes through the hologram 9, the focusing lens 10
, The condensing lens 10 only needs to be able to condense a beam that enters perpendicularly along the optical axis. Therefore, the condensing lens 10 may be a lens having a small aperture, the configuration of the optical system is simplified, and the size and cost of the apparatus can be reduced.

Embodiment 8 FIG. When an excimer laser is used for the laser oscillator 1, the beam diameter and the divergence angle have different values depending on the gas flow direction and the discharge direction of the excitation gas of the laser oscillator.
Therefore, the second, third, fourth, and fifth embodiments can be implemented independently for each of the gas flow direction and the discharge direction.

That is, in the second embodiment, independent reduction optical systems are used in each of the gas flow direction and the discharge direction (by using a cylindrical lens), and the beam diameter can be changed independently. FIG. 19 is a configuration diagram of a laser transfer processing apparatus using independent reduction optical systems. In the drawing, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts. In the drawing, reference numeral 14a denotes a reduction optical system that acts in the direction of the gas flow of the excimer laser, and 14b denotes a reduction optical system that also acts in the discharge direction of the excimer laser. According to this reduction optical system, when the traveling direction of the beam is taken on the Z axis, the X axis direction of the beam diameter is changed by the reduction optical system 4a,
A desired beam diameter can be obtained by changing the Y-axis direction of the beam diameter with the reduction optical system 4b.

In Embodiments 3 and 4, since the spot diameter of the beam focused on the mask by the focusing lens differs in the gas flow direction and the discharge direction, the overlapping pitch is in the gas flow direction and the discharge direction. Different pitch intervals can be set for each.

Similarly, the divergence angle of the beam can be changed separately in the gas flow direction and the discharge direction. In the fifth embodiment, when the X direction is the gas flow direction and the Y direction is the discharge direction, the maximum and minimum values of the spot diameter in the X direction and Y
The maximum value and the minimum value of the spot diameter in the directions can be set separately for the gas flow direction and the discharge direction using independent reduction optical systems 4a and 4b.

Embodiment 9 After passing through the reduction optics,
The beam incident on the hologram 9 should be a parallel light. When the light is made parallel, the occurrence of aberration by the hologram 9 can be suppressed. When the beams are made parallel light, the respective beams split by the hologram also become parallel light. As a result, since the focal length of the condenser lens 10 is uniquely determined for each beam, the adjustment of the spot diameter formed on the surface of the mask 6 (by the method of the third embodiment) becomes easy.

Embodiment 10 FIG. Each of the above-described embodiments 1 to 9 has been described for the case where a laser oscillator having a low spatial coherency is used. However, in the present embodiment, a laser oscillator having a high spatial coherency is used. This also ensures that the uniform laser irradiation intensity is obtained on the target 8 without interference between the beams.

FIG. 9 is a configuration diagram of a laser transfer processing apparatus according to the present embodiment. In the drawing, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts. In the figure, reference numeral 16 denotes a phase plate arranged between the laser oscillator 1 and the hologram 9.
As shown in FIG. 10, in the phase plate 16, the optical thickness of the surface of the phase plate 16 in consideration of the refractive index is partially changed at random to give a partial phase difference to the beam. According to the figure, the hatched portion 17 shows an area that is optically thicker than the other white portions 18.

Next, the operation of this embodiment will be described. When, for example, a normal excimer laser oscillator having low spatial coherency is used as the laser oscillator 1, a large number of beams split by the hologram 9 are imaged on the target 8 through the condenser lens 10 and the mask 6. However, since the spatial coherency of the beams is low, the beams do not interfere with each other. Therefore, a uniform laser irradiation intensity can be obtained on the target 8.

However, when, for example, a long pulse excimer laser oscillator, a YAG laser oscillator or a CO ₂ laser oscillator is used as the laser oscillator 1, these laser oscillators emit a beam having high spatial coherency. Therefore, when the beams are superimposed on each other to obtain a uniform irradiation intensity on the target 8, the respective beams interfere with each other to generate interference fringes, thereby losing the uniformity of the irradiation intensity. Therefore, using a beam having a high spatial coherency results in a loss of the stability of laser processing of the target 8.

Therefore, in this embodiment, in order to reduce the spatial coherency, the phase plate 16 is inserted between the laser oscillator 1 and the hologram 9, and the beam is transmitted through the phase plate 16. The beam is partially in the optically thick region 1
7. Since the light passes through the thin region 18, the phase of the beam transmitted through these regions changes relatively. As a result, the phase of the spatially high coherency beam, which is in phase before passing through the phase plate 16, is partially disturbed and can be changed to a spatially low coherency beam. .

As described above, in the laser transfer processing apparatus according to the present embodiment, the phase plate 16 having a region where the optical thickness is partially large and the region where the optical thickness is small is partially combined with the laser oscillator 1 and the hologram 9.
, The coherency of the beam having high spatial coherency emitted from the laser oscillator 1 can be reduced. Therefore, even when a large number of beams are superimposed on the target 8, it is possible to obtain a uniform irradiation intensity without interference between the beams, and there is an effect that stable laser processing can be performed with a simple configuration.

In the present embodiment, the phase plate 16 is arranged between the laser oscillator 1 and the hologram 9;
The function of 6 is to partially impart a phase difference to the beams when multiple beams are superimposed on the target 8 in order to prevent interference between the beams. Therefore, the phase plate 16
May be arranged at any point in the optical path from the laser oscillator 1 to the target 8. Alternatively, it may be arranged in the laser oscillator 1 as shown in FIG. Furthermore, even if the arrangement of the phase plate 16 is determined so that the entire beam does not pass through the phase plate 16 and only a part of the beam passes through the phase plate 16, the effect of partially giving a phase difference to the beam does not change. Absent.

Embodiment 11 FIG. Embodiment 10
Although the phase plate 16 is formed by partially changing the optical thickness of the surface of the glass plate, in the present embodiment, a diffusion plate having at least one surface polished into a glass is used. FIG. 12 is a configuration diagram of a laser transfer processing apparatus according to the present embodiment.
In the drawing, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts. In the figure, reference numeral 19 denotes the laser oscillator 1 and the hologram 9
And a diffusion plate disposed between the two. FIG. 13 is a front view and a sectional view of the diffusion plate 19 according to the present embodiment. Diffusion plate 19
Forms one side of a glass plate in the shape of polished glass to partially impart a phase difference to an incident beam.

More specifically, when a large number of fine irregularities are randomly formed on the surface of a glass plate made of quartz to form the diffusion plate 19, the thickness of the diffusion plate 19 varies at random according to the fine irregularities. Therefore, the optical thickness of the glass sheet also changes randomly in accordance with the uneven shape, so that the phase of the transmitted beam also changes randomly.

Therefore, a beam having a high spatial coherency having a uniform phase before passing through the diffusion plate 19 becomes a beam whose phase is randomly disturbed after passing through the diffusion plate 16, and a beam having a high spatial coherency is obtained. It becomes a low beam.

As described above, the laser transfer processing apparatus according to the present invention does not need to make optically thick or thin portions such as the phase plate 16 by etching or stamping, so that the beam wavelength order is less than the order of the wavelength of the beam. By making fine scratches on the surface of the glass, it is possible to produce a polished glass-like diffusion plate 19 having a large number of random fine irregularities formed on the glass surface.

By inserting the diffusing plate 19 formed in this manner between the laser oscillator 1 and the hologram 6, a beam having a high spatial coherency emitted from the laser oscillator 1 can be inexpensively converted into a spatially coherent beam. It can be reduced with low coherency beams.

Therefore, even when a large number of beams are superimposed on the target 8 as a workpiece, a uniform irradiation intensity can be obtained without interference between the beams, and stable laser processing can be performed at low cost. There is an effect that can be done. still,
As in the case of the phase plate 16, it is possible to arbitrarily select the position where the diffusion plate 19 is arranged and the arrangement of the diffusion plate 19 so that a part of the beam passes through the diffusion plate 19.

Embodiment 12 FIG. In the tenth embodiment, the phase plate 16 and the hologram 9 are individually provided. However, in the present embodiment, a phase plate serving as a phase plate is formed on one surface of a glass plate material such as quartz glass, and the hologram is formed on multiple surfaces. Is formed to form a single phase plate and hologram. FIG. 14 is a configuration diagram of a laser transfer processing apparatus according to the present embodiment. In the drawing, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts. In the figure, 9A is a phase hologram in which a phase plate and a hologram are integrally formed.

As shown in FIG. 15, the phase hologram 9A has the phase plane 20 of the phase plate described in the tenth embodiment formed on the beam incident surface which is one surface of a single substrate (quartz glass plate). Then, a hologram 21 having an interference fringe pattern formed on the other surface is formed.

Next, the operation of the present embodiment will be described. When a beam partially passes through a region having a large optical thickness or a region having a small optical thickness on the phase plane 20, the phase of the beam passing through these regions changes relatively. And the phase plane 20
The phase of the beam having a high spatial coherency that has been aligned before passing through is partially disturbed, and the beam has a low spatial coherency. This beam becomes a split beam that travels in an arbitrary direction by the hologram 21.

In the present embodiment, the phase plane 20 and the hologram 21 having a region having a thick optical thickness and a region having a thin optical region are respectively formed on the front and the back of the same substrate. Compared to when inserted inside,
The configuration is simple, and the loss due to reflection on unnecessary surfaces can be reduced, and the coherency of the beam having high spatial coherency emitted from the laser oscillator 1 can be reduced. Therefore, even when a large number of beams are superimposed on the target 8 which is a workpiece, a uniform irradiation intensity can be obtained without interference between the beams, so that stable laser processing can be performed with high efficiency. This has the effect.

It is to be noted that even if the phase plane 20 is not provided on the entire surface of the substrate, even if the formation area of the phase plane 2 is set so that a part of the beam passes through the phase plane 20, a partial phase difference is given to the beam. Can be. Further, on which surface of the substrate the phase plane 20 or the hologram 21 is formed can be arbitrarily determined when forming the interference fringe pattern corresponding to the mask pattern.

Embodiment 13 FIG. In the eleventh embodiment, the diffusion plate 19 and the hologram 9 are individually provided. However, in this embodiment, a diffusion surface serving as a diffusion plate is formed on one surface of a glass plate material such as quartz glass, and the diffusion surface is formed on the other surface. A diffusion plate and a hologram are formed as a single unit by forming an interference fringe pattern serving as a hologram. FIG. 16 is a configuration diagram of a laser transfer processing apparatus according to the present embodiment. In the drawing, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts. In the drawing, reference numeral 9B denotes a diffusion hologram in which a diffusion plate and a hologram are integrally formed.

As shown in FIG. 17, the diffusion hologram 9B has the diffusion surface 22 of the diffusion plate described in the eleventh embodiment formed on the beam incident surface which is one surface of a single substrate (quartz glass plate). Then, a hologram 21 having an interference fringe pattern formed on the other surface is formed.

Next, the operation of this embodiment will be described. When the beam passes through the fine irregularities of the diffusion surface 22, the phase of the beam passing through these portions changes relatively. Then, the phase of the beam having high spatial coherency, which has been aligned before transmitting through the diffusion surface 22, is partially disturbed, and becomes a beam having low spatial coherency. This beam becomes a split beam that travels in an arbitrary direction by the hologram 21.

In the present embodiment, the diffusion surface 22 and the hologram 21 having fine irregularities are formed on the front and the back of the same substrate, respectively. Therefore, compared to the case where the diffusion plate and the hologram are separately inserted into the optical path, The configuration is simple, the loss due to reflection on unnecessary surfaces can be reduced, and the coherency of the beam having high spatial coherency emitted from the laser oscillator 1 can be reduced. Therefore, even when a large number of beams are superimposed on the target 8 which is a workpiece, it is possible to obtain a uniform irradiation intensity without interference between the beams, so that stable laser processing can be performed with high efficiency. This has the effect.

It is to be noted that even if the diffusion surface 22 is not provided on the entire surface of the substrate, even if the formation area of the diffusion surface 2 is set so that a part of the beam passes through the diffusion surface 22, a partial phase difference may be given to the beam. Can be. The surface on which the diffusion surface 22 or the hologram 21 is formed can be arbitrarily determined when forming the interference fringe pattern corresponding to the mask pattern.

Embodiment 14 FIG. In the twelfth embodiment,
Phase plane 20 and hologram 2 on the front and back of the same substrate, respectively.
1, the phase plate and the hologram are integrally formed. In this embodiment, however, the interference fringe pattern for the hologram and the random pattern composed of the optically thick and thin regions are simultaneously formed on the same surface of the substrate. The hologram and the phase plane are simultaneously formed.

FIG. 18 shows a phase hologram 23 in which the hologram and the phase plane are simultaneously formed on the same plane of the substrate as described above.
FIG. Even if a large number of beams are superimposed on the target 8 which is a workpiece, the beams passing through the phase hologram created in this way are overlapped with each other because the spatial coherency of the beams is reduced. Without irradiation, a uniform irradiation intensity can be obtained on the target 8. Therefore, there is an effect that laser transfer processing with stable irradiation intensity can be realized at low cost.

In the above embodiment, the hologram and the phase plate are combined on the same surface of the substrate in order to eliminate the interference between the beams and obtain a beam with uniform irradiation intensity. Merge into one surface. That is, by forming the surface of the hologram into a polished glass shape,
There is an effect that laser processing with stable irradiation intensity can be realized at lower cost.

[0104]

According to the present invention, a laser oscillator, a condensing lens for condensing a laser beam emitted from the laser oscillator, and the condensed laser beam are formed into a processing pattern for a workpiece. A mask that transmits the opening that is aligned with the mask, and a transfer lens that transfers a mask pattern image that has passed through the mask to the workpiece; and any one of optical paths from the beam emission side of the laser oscillator to the mask. Since a hologram in which an interference fringe pattern is formed in accordance with the processing pattern is arranged at the position (1), the beam irradiating the light-shielding portion of the mask can be reduced. There is an effect that highly efficient laser processing can be performed with high efficiency.

Further , since the hologram is arranged in the optical path between the laser oscillator and the condenser lens, the beam cut off by the mask can be extremely reduced, so that there is an effect that the laser processing can be performed efficiently.

Further , since the hologram is arranged in the optical path between the condenser lens and the mask, the beam cut off by the mask can be extremely reduced, so that the laser processing can be performed efficiently.

Also, since the reduction optical system for reducing the diameter of the laser beam incident on the hologram is disposed in front of the hologram, the divergence angle of the beam after passing through the condenser lens becomes large, and the beam passes through the transfer lens. There is an effect that a part of the beam is not lost during the operation and the beam can be used effectively.

Also, since the reduction optical system uses a cylindrical lens or a cylindrical mirror which can be installed independently of the gas flow of the laser oscillator and the discharge direction,
There is an effect that the beam can be finely adjusted.

Further , since the hologram can be moved in parallel with the optical path, the angle of the incident light with respect to the transfer lens can be adjusted, so that the performance of the transfer lens can be effectively brought out.

Further , since the coherence reducing means for reducing the spatial coherence of the laser beam is arranged in the optical path from the laser oscillator to the workpiece, even if a large number of beams are superimposed on the workpiece, they are not mutually coherent. It is possible to obtain a uniform irradiation intensity without interference between the beams, and it is possible to perform stable laser processing.

Further , since the coherence reducing means is a phase plate in which a plurality of regions having a large optical thickness and a plurality of regions having a small optical thickness are formed on a transparent substrate surface through which a laser beam is transmitted, a large number of beams are superimposed on a workpiece. Even so, it is possible to obtain a uniform irradiation intensity without interference between the beams, and there is an effect that stable laser processing can be performed.

Further , since the coherence reducing means is a diffusion plate in which a transparent substrate through which a laser beam is transmitted has been subjected to fine unevenness processing, even if a large number of beams are superimposed on a workpiece, the two beams are not connected to each other. It is possible to obtain a uniform irradiation intensity without interference, and it is possible to perform stable laser processing at low cost.

[0113] Further, the opposite surface of the substrate of the hologram forming an interference fringe pattern on one side, the thick region and the thin region thickness forming a plurality of spatial by generating a phase difference between the laser beam passing through these areas Because a phase plane that reduces coherence is formed, even if many beams are superimposed on the workpiece, it is possible to obtain a uniform irradiation intensity without interference between the beams, and stable laser processing And an effect that the configuration is simpler and the laser energy can be reduced by beam reflection on an unnecessary surface, as compared with the case where the phase plate and the hologram are individually arranged in the optical path.

Also, the opposite surface of the substrate of the hologram having the interference fringe pattern formed on one surface is subjected to fine unevenness processing to form a diffusion surface which diffuses a transmitted laser beam and reduces spatial coherence. It becomes possible to obtain a uniform irradiation intensity without interference between the beams, and it is possible to perform stable laser processing at a low cost, as compared with a case where the diffusion plate and the hologram are arranged alone in the optical path, There is an effect that the configuration is simple and the laser energy can be reduced by beam reflection on an unnecessary surface.

Further, a plurality of thick and thin regions are formed on the substrate surface of the hologram on which the interference fringe pattern is formed, and a phase difference is generated between laser beams passing through these regions to reduce spatial coherence. As a result, a stable laser processing can be performed, and the beam is formed on an unnecessary surface with a simpler structure than when a phase plate and a hologram are individually arranged in the optical path. There is an effect that laser energy can be reduced by reflection.

Further , the surface of the hologram on which the interference fringe pattern is formed is subjected to fine unevenness processing to form a diffusion surface which diffuses a transmitted laser beam and reduces spatial coherence, thereby providing stable laser processing. And the effect that the laser energy can be reduced by the beam reflection on an unnecessary surface compared with the case where the diffusing plate and the hologram are individually arranged in the optical path. is there.

A laser beam emitted from a laser oscillator is condensed by a condensing lens, and the condensed laser beam is transmitted through an opening of a mask opened in accordance with a processing pattern for a workpiece. When the transmitted mask pattern image is transferred to the workpiece by the transfer lens, a laser beam transmitted through the mask is transmitted through a hologram having an interference fringe pattern formed in accordance with the processing pattern to be divided into a plurality of pieces. As a result, the beam irradiating the mask light-shielding portion can be reduced,
There is almost no laser energy consumed by the mask, and there is an effect that laser processing with high energy utilization efficiency and high efficiency can be performed.

Also, since a large number of laser beams split by the hologram partially overlap each other on the mask to create an irradiation area having an arbitrary intensity distribution within a certain range, the laser beam is formed on the mask. There is an effect that the beam intensity distribution becomes uniform.

[0119] Also, split by the hologram, since the distance between the superposition of the laser beams are superimposed on the mask and below the spot diameter of each of the laser beams split by the hologram (half width), optionally in the processed surface There is an effect that laser processing can be performed by irradiating an intensity distribution and an arbitrary pattern beam.

Further, the ratio of the half value width of the spot diameter to the interval of superposition of the laser beams superposed on the mask is defined as FP%, and the desired uniformity on the mask is ± Er.
%, The FP is set so as to satisfy the condition of Er ≧ 1.12√FP, so that even if the beam intensity varies by about 10%, the uniformity of the intensity is within a predetermined range. There is an effect that can be suppressed.

Further, the laser beam width d of the laser beam incident on the hologram and the focal length f of the condenser lens
And the incident side NA of the transfer lens satisfies the relationship of (d / 2) ≦ f · NA, so that there is an effect that all the beams incident on the transfer lens can be effectively used.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a laser transfer processing apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a diagram showing a processing pattern.

FIG. 3 is a configuration diagram of a laser transfer processing apparatus according to Embodiment 2 of the present invention.

FIG. 4 is a diagram showing a beam diffracted by a hologram and condensed by a condenser lens in the third embodiment.

FIG. 5 shows that the variation in the intensity of each beam diffracted by the hologram in the fourth embodiment is 5% and 10%.
FIG. 9 is a diagram showing the relationship between the overlap distance and the overall uniformity with respect to the beam spot diameter on the mask surface in the case of FIG.

FIG. 6 is a diagram showing a laser intensity distribution on a mask surface when a focused spot diameter is changed in a fifth embodiment.

FIG. 7 is a diagram illustrating a mask irradiation optical system of a laser transfer processing apparatus according to a sixth embodiment of the present invention.

FIG. 8 is a diagram illustrating a mask irradiation optical system of the laser transfer processing apparatus described in the seventh embodiment.

FIG. 9 is a configuration diagram of a laser transfer processing apparatus according to Embodiment 9 of the present invention.

FIG. 10 is a front view of a phase plate used in the laser transfer processing apparatus described in the ninth embodiment.

FIG. 11 is a configuration diagram of a laser transfer processing apparatus according to Embodiment 10 of the present invention.

FIG. 12 is a configuration diagram of a laser transfer processing apparatus according to Embodiment 11 of the present invention.

13A and 13B are a front view and a cross-sectional view of a diffusion plate used in the laser transfer processing device described in Embodiment 11.

FIG. 14 is a configuration diagram of a laser transfer processing apparatus according to Embodiment 12 of the present invention.

FIG. 15 illustrates a phase surface (front surface) and a hologram surface (back surface) used in the laser transfer processing apparatus described in Embodiment 12.

FIG. 16 is a configuration diagram of a laser transfer processing apparatus according to Embodiment 13 of the present invention.

FIG. 17 illustrates a diffusion surface (front surface) and a hologram surface (back surface) used in the laser transfer processing apparatus described in Embodiment 13.

FIG. 18 is a front view of the phase hologram shown in the fourteenth embodiment.

FIG. 19 is a configuration diagram of a laser transfer processing apparatus according to an eighth embodiment of the present invention.

FIG. 20 is a configuration diagram illustrating a schematic configuration of a conventional laser transfer processing apparatus.

FIG. 21 is a diagram showing a schematic configuration of a conventional processing optical system using a hologram.

FIG. 22 is a configuration diagram of a conventional processing optical system using a hologram.

FIG. 23 is a schematic configuration diagram of a spatial filter.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 laser oscillator, 2 deflecting mirror, 4 beams emitted by laser oscillator, 6 masks, 4 a beam split by hologram, 8 target (workpiece), 9 hologram, 9A phase hologram, 9B
Diffusion hologram, 10 condenser lens, 14 reduction optical system, 15 beam spot focused on mask surface, 1
6 phase plate, 17 optically thick part of phase plate, 18
Optically thin portion of phase plate, 19 diffuser, 20 random phase, 21 hologram, 22 diffuser, 2
3 Hologram with random phase plates.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-290264 (JP, A) JP-A-63-244736 (JP, A) JP-A-9-512749 (JP, A) Kita, one outsider , “Present and Future of Micromachining with Excimer Laser”, Mechanical Technology, Nikkan Kogyo Shimbun, November 1995, Vol. 43, No. 12, p. 27-27-32 (58) Field surveyed (Int. Cl. ⁷ , DB name) B23K 26/06

Claims (10)

(57) [Claims] 1. A laser oscillator and a laser oscillator
A focusing lens that focuses the emitted laser beam and a focusing lens
Laser beam that has been processed
A mask that allows the light to pass through the opening
The mask pattern image transmitted through the mask
A transfer lens for transferring and a beam emission of the laser oscillator
Placed at any point in the optical path from the side to the mask
In addition, an interference fringe pattern is formed in accordance with the mask pattern.
And a hologram formed.
Each split beam is shaped according to the opening shape of the mask.
In laser transfer processing equipment,
In the optical path to the workpiece, the spatial coherence of the laser beam
Coherence reduction means to reduce
And a laser transfer processing apparatus. 2. The coherence reducing means includes a laser beam.
Optically thick and thin areas on a transparent substrate surface
Characteristic of a phase plate with multiple regions formed in random order
The laser transfer processing apparatus according to claim 1. 3. The coherence reducing means includes a laser beam.
Diffuser plate with fine irregularities on the transparent substrate surface
The laser transfer processing according to claim 1, wherein
apparatus. 4. A hologram having an interference fringe pattern formed on one surface.
On the opposite side of the ram substrate, the optically thick and thin areas
A plurality of regions are formed in any order, and
Spatial coherence by generating a phase difference between the laser beams
Characterized by forming a phase surface that reduces
Item 2. A laser transfer processing apparatus according to Item 1. 5. A hologram having an interference fringe pattern formed on one surface.
The surface of the ram opposite to the substrate is subjected to fine irregularities to
Diffuses the laser beam to reduce spatial coherence
2. The method according to claim 1, wherein a diffusion surface is formed.
Laser transfer processing equipment. 6. A hologram having an interference fringe pattern formed thereon.
The order of thick and thin optical areas on the substrate surface is out of order.
Similarly, a plurality of laser beams are formed between laser beams passing through these regions.
Phase difference to reduce spatial coherence
Wherein the phase planes are formed at the same time.
The laser transfer processing apparatus as described in the above. 7. A hologram having an interference fringe pattern formed thereon.
A laser beam that passes through the substrate surface by applying a fine unevenness process
Diffuse surface that diffuses light and reduces spatial coherence
2. The laser drive according to claim 1, wherein
Photo processing equipment. 8. A laser beam emitted from a laser oscillator.
The laser beam is focused by a focusing lens, and the focused laser beam is
Open the arm according to the machining pattern for the workpiece.
Through the opening of the mask, and the mask pattern
When the transfer image is transferred to the workpiece by the transfer lens,
A laser beam transmitted through the mask is applied to the mask pattern.
Hologram with an interference fringe pattern
Transmitted and split into multiple beams, each of these split beams
Is formed by the opening shape of the mask,
Therefore, a large number of split laser beams are alternated on the mask.
Any overlap within a certain range
A laser transfer processing method that creates an irradiation area with a distribution
Is divided by the hologram and superimposed on the mask
The hologram is used to determine the laser beam
Of each laser beam divided by
Laser transfer processing characterized in that the diameter (half value width) or less
Construction method. 9. A laser beam superimposed on a mask
Of the spot value half width to the overlap distance
Is FP%, and the desired uniformity on the mask is ± Er%.
In this case, satisfy the condition Er ≧ 1.12√FP.
9. The laser according to claim 8, wherein an FP is set.
The transfer processing method. 10. A laser beam incident on a hologram.
Laser beam width d, focal length f of the condenser lens, and
When the incident side NA of the imaging lens is (d / 2) ≦ f · NA,
9. The laser transfer process according to claim 8, wherein
Construction method.