JP2003001451A - Laser beam machining device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser beam machining device with which a work to be machined is cut without causing a molten surface or a crack strayed from an intended line to be cut on the surface of the work to be machined. SOLUTION: The laser beam machining device 100 is provided with a laser light source 101 which emits a laser beam L of which pulse width is 1 μs or smaller, means 401 which adjusts the power of the laser beam on the basis of an input, a condenser lens 105 which condenses the laser beam so that the peak power density of the laser beam at a condensed point P of the laser beam becomes 1×10<8> (W/cm<2> ) or greater, a means 405 which adjusts the aperture number of an optical system including the condenser lens on the basis of an input, a means 113 with which the condensed point of the laser beam is aligned with the inner part of the work 1 to be machined, means 109 and 111 which move the condensed point of the laser beam along the intended line to be cut 5, a means 127 which preliminarily storages the correlation between a combination of the power magnitude of the laser beam and the aperture number and the dimension of a modified spot and selects the dimension of the modified spot formed with an inputted value and a means 129 which displays the dimension.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor material substrate,
Used to cut workpieces such as piezoelectric material substrates and glass substrates
The present invention relates to a laser processing apparatus. One of the laser applications is cutting, and laser
The general cutting by is as follows. For example, semiconductor wafer
Where to cut workpieces such as wafers and glass substrates
Is irradiated with laser light having a wavelength that is absorbed by the workpiece.
-At the part to be cut by absorbing the light,
The object to be processed by heating and melting from the front to the back
Disconnect. However, with this method, the surface of the workpiece
Of these, the area surrounding the area to be cut is also melted. By
If the workpiece is a semiconductor wafer,
Of the semiconductor devices formed on the surface,
The semiconductor element to be placed may be melted. SUMMARY OF THE INVENTION Problems to be Solved by the Invention
As a method for preventing melting, for example, JP 2000-21
No. 9528 and JP 2000-15467.
There is a laser cutting method shown. Of these publications
In the cutting method, the part of the workpiece to be cut is changed to laser light.
By heating more and cooling the workpiece,
A thermal shock is generated at the part to be cut of the workpiece to be processed.
Cut the figurine. However, in the cutting methods of these publications, additional processing is required.
If the thermal shock generated on the workpiece is large, the surface of the workpiece
In addition, cracks that are off the cutting line or laser irradiation
Unnecessary cracks such as cracks up to the previous point may occur.
There is. Therefore, these cutting methods perform precision cutting.
I can't. In particular, the object to be processed is a semiconductor wafer,
The glass substrate on which the liquid crystal display device is formed, and the electrode pattern
In the case of the formed glass substrate, this unnecessary cracking
Damage to semiconductor chips, liquid crystal display devices, and electrode patterns
Sometimes. Also, with these cutting methods, the average input energy
Because the energy is large, the thermal damage to the semiconductor chip etc.
The page is also big. The object of the present invention is to make the surface of the work piece unnecessary.
The surface does not melt without causing necessary cracks.
It is to provide a laser processing apparatus. Means for Solving the Problems Laser processing according to the present invention
The device emits pulsed laser light with a pulse width of 1 μs or less.
Of the laser light source and the magnitude of the power of the pulse laser light
Pulse laser emitted from laser light source based on input
Power adjusting means for adjusting the magnitude of the light power;
Peak of the condensing point of pulsed laser light emitted from the light source
Power density is 1 × 10 ⁸ (W / cm ² ) Pal to be more
Condensing lens that collects laser light and numerical aperture
Of the numerical aperture of the optical system including the condenser lens
A numerical aperture adjustment means that adjusts the size and a condenser lens
The focusing point of the focused pulsed laser beam is
According to the section to be machined and the cutting line of the workpiece.
To move the focusing point of the pulse laser light relatively
Means for aligning the condensing point inside the workpiece 1
To irradiate the workpiece with a pulsed laser beam
One modified spot is formed inside the workpiece.
Of the pulse laser beam adjusted by the power adjusting means.
Opening adjusted by power magnitude and numerical aperture adjustment means
The correlation between the number of units and the size of the modification spot
Correlation storage means stored in advance and input pulse level
-The magnitude of the laser beam power and the input numerical aperture
Modified spots formed in these sizes based on the length
Selection means for selecting the size of the model from the correlation storage means
And the dimension of the modified spot selected by the dimension selection means
Dimensional display means for displaying
The According to the laser processing apparatus of the present invention, the power
Align the focusing point of the laser light with the inside of the workpiece.
The peak power density at one condensing point is 1 × 10 ⁸ (W / c
m ² ) Processing under the above conditions with a pulse width of 1 μs or less
An object can be irradiated with pulsed laser light. By
The pulse laser using the laser processing apparatus according to the present invention
When the workpiece is irradiated with light, multiple light is emitted inside the workpiece.
Phenomenon occurs, which causes the inside of the workpiece
A modified region is formed. At the point where the workpiece is cut
If there is any starting point, the workpiece can be moved with a relatively small force.
Can be broken and cut. Therefore, the label according to the present invention
-The workpiece processed using the laser processing machine
Divide or break along the planned cutting line from the area
Can be cut. Therefore, relatively small
The workpiece can be cut with great force.
Unnecessary cracks off the planned cutting line on the surface of the figurine
The workpiece can be cut without being generated. Also, according to the laser processing apparatus of the present invention,
For example, multiphoton absorption occurs locally inside the workpiece.
As a result, a modified region is formed. Therefore, the surface of the workpiece
Since the laser beam is hardly absorbed,
The surface of the metal does not melt. The focusing point is a laser.
It is the location where the light is collected. The cutting line is processed
It may be a line that is actually drawn on the surface or inside of the object.
It may be a line of thought. According to the present inventors, the pulse laser beam
As the power is reduced, the modification spot becomes smaller
Can be controlled and improved by increasing the power of pulsed laser light
It turns out that the spot can be controlled to become larger
It was. And increase the numerical aperture of the optical system including the condenser lens.
If this is done, the modified spot can be controlled to a small size and its numerical aperture
It can be seen that the smaller the spot, the greater the modification spot can be controlled.
won. A modified spot is a single pulse laser beam.
This is a modified part formed by
As a result, it becomes a modified region. Control of the dimensions of the modification spot
It affects the cutting of the workpiece. That is, reforming
If the spot is too large, the line to cut the workpiece
The accuracy of cutting along the surface and the flatness of the cut surface deteriorate. one
On the other hand, the modified spot is extreme for the thick workpiece
If the edge is too small, it is difficult to cut the workpiece. Main departure
According to the laser processing apparatus related to Ming,
By adjusting the size of the warper,
Control, and includes a condensing lens
By adjusting the numerical aperture of the optical system
The pot size can be controlled. Also, the power of the input pulse laser beam
And the input numerical aperture
Can know the dimensions of the modified spot before laser processing.
The DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.
This will be described with reference to the drawings. Laser according to this embodiment
The processing equipment forms a modified region by multiphoton absorption.
The Multiphoton absorption is a field where the intensity of laser light is greatly increased.
This is a phenomenon that occurs when First, let us briefly discuss multiphoton absorption.
Just explain. Band gap E of material absorption _G Than photon
When the energy hν of is small, it becomes optically transparent. By
Thus, the condition for absorption in the material is hν> E _G It is. Only
Even if it is optically transparent, the intensity of the laser beam is very large.
Then nhν> E _G (N = 2, 3, 4,...
Absorption occurs in the material. This phenomenon is called multiphoton absorption.
Yeah. In the case of a pulse wave, the intensity of the laser beam is the concentration of the laser beam.
Point peak power density (W / cm ² ), For example pea
The power density is 1 × 10 ⁸ (W / cm ² ) Multiphoton under the above conditions
Absorption occurs. The peak power density is
Laser light energy per pulse) ÷ (Laser light
Of beam spot cross section x pulse width)
The In the case of continuous wave, the intensity of the laser beam is
Electric field strength at the focal point (W / cm ² ) This embodiment utilizing such multiphoton absorption
1 to 6 on the principle of laser processing related to the state
explain. FIG. 1 is a plan view of a workpiece 1 during laser processing.
2 is along the line II-II of the workpiece 1 shown in FIG.
FIG. 3 is a workpiece 1 after laser processing.
FIG. 4 is a plan view of the workpiece 1 shown in FIG.
FIG. 5 is a cross-sectional view taken along the line IV, and FIG. 5 is a processing target shown in FIG.
FIG. 6 is a cross-sectional view taken along line VV of the object 1, and FIG.
1 is a plan view of an object 1 to be processed. As shown in FIG. 1 and FIG.
The surface 3 has a cutting line 5. Scheduled cutting line
Reference numeral 5 denotes a virtual line extending linearly. The label according to this embodiment
-The laser processing is performed under the condition that multiphoton absorption occurs.
Align the focused point P inside and irradiate the workpiece 1 with the laser beam L
The modified region 7 is formed by spraying. The focusing point is a laser.
It is the location where the light L is condensed. A laser beam L is projected along the cutting line 5
(I.e., along the direction of arrow A)
As a result, the condensing point P is moved along the planned cutting line 5.
Make it. As a result, as shown in FIGS.
Is only inside the workpiece 1 along the planned cutting line 5
It is formed. The laser processing method according to the present embodiment is processed
The object 1 is processed by absorbing the laser beam L.
The modified region 7 is not formed by heating 1. processing
The laser beam L is transmitted through the object 1 and inside the object 1 to be processed.
The modified region 7 is formed by generating multiphoton absorption. Yo
The laser beam L is almost on the surface 3 of the workpiece 1
Since it is not absorbed, the surface 3 of the workpiece 1 melts.
Is not. In cutting the workpiece 1, the parts to be cut
If there is a starting point, the workpiece 1 will break from that starting point.
Then, as shown in FIG. 6, the workpiece 1 is moved with a relatively small force.
Can be cut. Therefore, the surface 3 of the workpiece 1
Cutting workpiece 1 without causing unnecessary cracks
Can be interrupted. It should be noted that the workpiece to be processed starting from the modified region.
There are two possible ways of cutting. One is a modified area type
After the process, artificial force is applied to the workpiece.
As a result, the workpiece is cracked starting from the modified region,
This is when an object is cut. This is for example a workpiece
This is cutting when the thickness is large. An artificial force is applied
For example, along the planned cutting line of the workpiece
To apply bending stress or shear stress to the workpiece.
Thermal stress was generated by giving a temperature difference to the object
It is to do. The other is to form a modified region.
The cross-sectional direction of the workpiece from the modified region
Naturally cracks in the (thickness direction), resulting in processing
This is when an object is cut. This is for example a workpiece
If the thickness is small, even one modified region is possible,
When the thickness of the workpiece is large, multiple modifications in the thickness direction
This is possible by forming the region. Note that this nature
In some cases, a modified region is formed at the location to be cut.
There is no pre-cracking to the surface on the part that is not
Only the surface on the part where the modified part is formed can be cleaved.
Therefore, the cleaving can be controlled well. In recent years
Semiconductor wafers such as recon wafers tend to be thinner
Therefore, such a cleaving method with good controllability is very effective.
It is. In the present embodiment, multiphoton absorption is used.
The following modified areas (1) to (3) are
The (1) One or more cracks in the modified region
In the case of a crack area containing laser, the laser beam is irradiated on the workpiece (eg glass or LiTaO _Three Consist of
Align the focal point inside the piezoelectric material)
Electric field strength is 1 × 10 ⁸ (W / cm ² ) And the pulse width is 1
Irradiate under conditions of μs or less. The magnitude of this pulse width is
Excessive damage to the workpiece surface while causing multiphoton absorption
Crack area only inside the workpiece without giving
Is a condition that can be formed. As a result,
The phenomenon of optical damage due to multiphoton absorption occurs in the area
The This optical damage causes thermal strain inside the workpiece.
This induces cracks inside the workpiece.
A zone is formed. The upper limit value of the electric field strength is, for example, 1
× 10 ¹² (W / cm ² ). For example, the pulse width is 1 ns to 2
00 ns is preferred. In addition, the crack area by multiphoton absorption
For example, the 45th Laser Thermal Processing Society Paper
Of the collection (December 1998), pages 23-28
Internal marking of glass substrate by body laser harmonics "
It is described in. The inventor found that the electric field strength and crack size
The relationship was determined by experiment. The experimental conditions are as follows:
is there. (A) Object to be processed: Pyrex (registered quotient
Standard) Glass (thickness 700 μm) (B) Laser light source: semiconductor laser excitation Nd: YAG laser wavelength: 1064 nm Laser light spot cross-sectional area: 3.14 × 10 ^-8 cm ² Oscillation form: Q switch pulse repetition frequency: 100 kHz Pulse width: 30 ns Output: Output <1 mJ / pulse laser light quality: TEM ₀₀ Polarization characteristics: Linearly polarized light (C) Condensation lens Transmittance to wavelength of laser light: 60% (D) Moving speed of mounting table on which workpiece is mounted: 10
0mm / second The laser beam quality is TEM ₀₀ Is a highly condensing laser
It means that light can be collected up to the wavelength of light. FIG. 7 is a graph showing the results of the above experiment.
The The horizontal axis is the peak power density, and the laser beam is pulsed
Since it is a laser beam, the electric field strength is expressed by the peak power density.
The The vertical axis shows the inside of the workpiece by one pulse of laser light.
Of cracks (crack spots) formed in
It shows. Crack spots gather and crack area
It becomes an area. The size of the crack spot
The size of the part of the shape of the
The The data indicated by black circles in the graph is the condensing lens (C)
When the magnification is 100 times and the numerical aperture (NA) is 0.80
The On the other hand, the data indicated by white circles in the graph is the condensing lens
When the magnification of (C) is 50 times and the numerical aperture (NA) is 0.55
It is. Peak power density is 10 ¹¹ (W / cm ² ) From the degree
Crack spots occur inside the workpiece and peak
As the power density increases, the crack spot increases.
I can see that Next, in the laser processing according to this embodiment,
The mechanism of cutting the workpiece by forming the crack region
Is described with reference to FIGS. As shown in FIG.
As shown in FIG.
The processing object 1 is irradiated with the laser beam L with the focusing point P aligned with the part
To form a crack region 9 along the line to be cut
To do. The crack region 9 contains one or more cracks.
Area. As shown in FIG.
As the crack grows further as shown in FIG.
The rack reaches the front surface 3 and the back surface 21 of the workpiece 1 and
As shown in Fig. 11, the workpiece 1 is processed by cracking.
The object 1 is cut. Reach the front and back of the workpiece
Cracks that grow may grow naturally and are subject to processing
In some cases, the object grows when a force is applied to the object. (2) When the modified region is a melted region, the laser beam is irradiated on the object to be processed (for example, a semiconductor such as silicon).
The focusing point inside the material) and the electric field at the focusing point
Strength 1x10 ⁸ (W / cm ² ) And the pulse width is 1μs
Irradiate under the following conditions. As a result, the inside of the workpiece is
Heated locally by multiphoton absorption. This heating
A melt processing area is formed inside the workpiece. Melting
The treatment area is the area once solidified after melting, in the molten state
Less of the region and the region in the state of resolidifying from melting
Means either one. In addition, the melt processing area
It can also be a region that has changed or a crystal structure has changed.
Yes. In addition, the melt treatment region is a single crystal structure or an amorphous structure.
In one structure, polycrystalline structure, one structure changes to another
It can also be called an area. That is, for example, a single crystal structure
From a single crystal structure to a multiple
Region changed to crystal structure, from single crystal structure to amorphous structure and
It means a region changed to a structure including a polycrystalline structure. processing
When the object has a silicon single crystal structure, the melt processing area is an example.
For example, it has an amorphous silicon structure. The upper limit of electric field strength
For example, the value is 1 × 10 ¹² (W / cm ² ). Pal
For example, the width is preferably 1 ns to 200 ns. The inventor has melted the inside of the silicon wafer.
It was confirmed by experiment that a treatment region was formed. Experiment
The conditions are as follows. (A) Workpiece: silicon wafer (thickness
(350 μm, outer diameter 4 inches) (B) Laser light source: semiconductor laser excitation Nd: YAG laser wavelength: 1064 nm Laser light spot cross-sectional area: 3.14 × 10 ^-8 cm ² Oscillation form: Q switch pulse repetition frequency: 100 kHz Pulse width: 30 ns Output: 20 μJ / pulse laser light quality: TEM ₀₀ Polarization characteristics: Linearly polarized light (C) Condenser lens magnification: 50 times NA: 0.55 Transmittance with respect to laser light wavelength: 60% (D) Moving speed of mounting table on which workpiece is placed: 10
0mm / sec Fig. 12 shows the slicing cut by laser processing under the above conditions.
It is the figure showing the photograph of the section in the part of the con-wafer
The A melt processing region 13 is formed inside the silicon wafer 11.
It is made. Note that the melting treatment formed under the above conditions.
The size of the treatment region in the thickness direction is about 100 μm. Melting region 13 is formed by multiphoton absorption.
Explain what was done. FIG. 13 shows the wavelength of the laser light and the wavelength.
It is a graph which shows the relationship with the transmittance | permeability inside a recon board.
The However, each of the front side and back side of the silicon substrate
The reflection component is removed, and only the transmittance inside is shown. Shi
The thickness t of the recon substrate is 50 μm, 100 μm, 200 μm,
The above relationship is shown for each of 500 μm and 1000 μm.
It was. For example, the wavelength 106 of the Nd: YAG laser is used.
At 4 nm, the thickness of the silicon substrate is 500 μm or less
In this case, 80% or more of the laser beam is transmitted inside the silicon substrate.
You can see that Silicon wafer 11 shown in FIG.
Since the thickness of 350μm, melting by multiphoton absorption
The processing area is near the center of the silicon wafer, that is, from the surface.
It is formed in a part of 175 μm. The transmittance in this case is
When referring to a silicon wafer with a thickness of 200 μm, 90
% Or more, so the laser beam is inside the silicon wafer 11
Little is absorbed and most is transmitted. this
This means that the laser beam is absorbed inside the silicon wafer 11.
As a result, a melt processing region is formed inside the silicon wafer 11.
(In other words, the melting treatment area is formed by normal heating with laser light.
The melt processing area is not multi-photon absorption.
Means more formed. Melting by multiphoton absorption
For example, the formation of the treatment area
66th (April 2000), pages 72-73
"Processing characteristics evaluation of silicon by picosecond pulse laser"
It is described in. It should be noted that the silicon wafer has a melting region.
A crack is generated in the cross-sectional direction as the starting point,
As this reaches the front and back surfaces of the silicon wafer,
As a result. Front and back of silicon wafer
The cracks that reach the
It may grow when force is applied to the work object.
The It should be noted that the front and back of the silicon wafer from the melt processing area
The cracks grow naturally on the surface, once melted and resolidified
If a crack grows from the state of the state,
When cracks grow from the region and when they resolidify from melting
At least any of the cases where cracks grow from the state area
One of them. In either case, the cut surface after cutting is shown in FIG.
As shown in FIG. 2, a melt processing region is formed only inside.
Cleavage when forming a melt treatment area inside the workpiece
Unnecessary cracks that are off the planned cutting line
Therefore, the cleaving control becomes easy. (3) When the modified region is a refractive index changing region, the laser beam is focused on the inside of the workpiece (eg glass).
And the electric field strength at the condensing point is 1 × 10 ⁸ (W / c
m ² ) Irradiation is performed under the above conditions with a pulse width of 1 ns or less.
The pulse width is extremely shortened to reduce the multiphoton absorption of the workpiece.
When caused inside, the energy from multiphoton absorption is converted into heat.
Without being converted into energy, ions inside the workpiece
Permanent structural changes such as valence change, crystallization or polarization orientation
Induced, a refractive index changing region is formed. Above field strength
As a limit value, for example, 1 × 10 ¹² (W / cm ² ). Pa
For example, the pulse width is preferably 1 ns or less, more preferably 1 ps or less.
preferable. Formation of the refractive index change region by multiphoton absorption is
For example, the 42nd Laser Thermal Processing Workshop Proceedings (1997)
Year. November), page 105 to page 111, “Femtosecond
For "Light-induced structure formation inside glass by laser irradiation"
Has been described. As described above, according to this embodiment, the reforming process is performed.
The region is formed by multiphoton absorption. And this embodiment
The state is the power of the pulsed laser beam and the condensing lens
By adjusting the numerical aperture of the optical system including
The size of the modification spot is controlled. With reforming spot
Is a shot of one pulse of a pulse laser beam (that is, one pulse).
Modified part formed by laser irradiation of
It becomes a modified region by gathering spots. Reformer
Example of crack spot about necessity of dimensional control of robot
Explained. If the crack spot is too large, the cutting
The accuracy of cutting the workpiece along the fixed line is reduced.
In addition, the flatness of the cut surface is deteriorated. 14 ~
This will be described with reference to FIG. FIG. 14 shows a label according to this embodiment.
-Use cracking method to make crack spots relatively large
It is a top view of the process target object 1 at the time of forming. FIG.
Cut along XV-XV on the planned cutting line 5 in FIG.
It is sectional drawing. 16, FIG. 17, and FIG.
XVI-XVI, XVII-XVII, which is orthogonal to the planned cutting line 5 of 4,
It is sectional drawing cut | disconnected along XVIII-XVIII. these
As you can see, the crack spot 90 is too big
Then, the variation in the size of the crack spot 90 is also large.
Become. Therefore, as shown in FIG.
The accuracy of cutting the workpiece 1 along the line is deteriorated. Also,
Cutting because the unevenness of the cut surface 43 of the workpiece 1 is large
The flatness of the surface 43 is deteriorated. In contrast, as shown in FIG.
As described above, the laser processing method according to this embodiment is used to
The rack spot 90 is relatively small (for example, 20 μm or less).
Bottom) Once formed, crack spots 90 can be formed uniformly.
In the direction of the planned cutting line of crack spot 90
The spread in the direction deviated can be suppressed. Therefore, in FIG.
As shown, the cut of the workpiece 1 along the planned cutting line 5
The accuracy of cutting and the flatness of the cut surface 43 can be improved.
The Thus, the crack spot is too large.
And a precise cut or a flat cut surface along the planned cutting line
Can not be cut. However, the thickness is large
The crack spot is extremely small compared to the workpiece to be machined
If too much, it becomes difficult to cut the workpiece. According to this embodiment, the size of the crack spot
Explain that the law can be controlled. As shown in FIG.
If the peak power density is the same, the magnification of the condenser lens
Crack spot size for 100 and NA 0.8
Is the class when the condenser lens magnification is 50 and NA is 0.55.
It becomes smaller than the size of the click spot. Peak power
As described above, the density is determined per one pulse of the laser beam.
Is proportional to the energy of the pulse laser beam
Therefore, the same peak power density means that the laser beam power
Means the same. In this way, the laser light
If the power is the same and the beam spot cross-section is the same,
When the numerical aperture of the condenser lens increases (decreases), the
The size of the cspot can be controlled to be small (large). Even if the condensing lens has the same numerical aperture,
If the laser power (peak power density) is reduced
The size of the crack spot can be controlled small, and the laser beam
Increasing power increases crack spot dimensions
Can be controlled. Therefore, as can be seen from the graph shown in FIG.
In addition, increasing the numerical aperture of the condenser lens and laser light
The size of the crack spot by reducing the power of
The method can be controlled small. Conversely, the numerical aperture of the condenser lens
To make it smaller and to increase the power of the laser beam
The size of the crack spot can be controlled more greatly. Regarding the control of crack spot dimensions, FIG.
Further explanation will be given using the surface. The example shown in FIG.
The pulse laser beam L is inside using a condensing lens with a numerical aperture.
It is sectional drawing of the process target object 1 condensed on the. Region 4
No. 1 causes multiphoton absorption by this laser irradiation.
This is a region where the electric field strength is higher than the threshold value. FIG.
Formed due to multiphoton absorption by this laser beam L irradiation.
FIG. 6 is a cross-sectional view of a crack spot 90 that has been removed. On the other hand, FIG.
The example shown in FIG. 4 is a condensing with a numerical aperture larger than the example shown in FIG.
The pulse laser beam L is condensed inside using the lens for
FIG. FIG. 25 shows this layout.
A cluster formed due to multiphoton absorption by irradiation with the light L
FIG. Crack spot 9
The height h of 0 is in the thickness direction of the workpiece 1 in the region 41.
The width w of the crack spot 90 depends on the size of the region 4
1 depending on the dimension of the workpiece 1 in the direction perpendicular to the thickness direction
Exist. That is, reduce these dimensions of region 41
And the height h and width w of the crack spot 90 can be reduced.
Increasing these dimensions increases the height of the crack spot 90
h and width w can be increased. If FIG. 23 is compared with FIG.
As can be seen, when the power of the laser beam is the same,
By increasing (decreasing) the numerical aperture of the
Decrease the size of the height h and width w
B) Can be controlled. Further, the example shown in FIG. 26 is shown in FIG.
Pulse laser beam L with a smaller power than the example is focused inside.
It is sectional drawing of the to-be-processed target object 1. Example shown in FIG.
Then, since the power of the laser beam is reduced,
The area is smaller than the region 41 shown in FIG. FIG.
Is shaped due to multiphoton absorption due to the irradiation of this laser beam L.
It is sectional drawing of the formed crack spot 90. FIG. FIG.
As is clear from the comparison between FIG. 27 and FIG.
If the number is the same, reduce (increase) the laser beam power
Then, the height h and width w of the crack spot 90 are reduced.
(Large) control. Further, the example shown in FIG. 28 is shown in FIG.
Pulse laser beam L with a smaller power than the example is focused inside.
It is sectional drawing of the to-be-processed target object 1. Figure 29 shows this
Formed due to multiphoton absorption by laser light L irradiation
3 is a cross-sectional view of a crack spot 90. FIG. 23 and 29
As can be seen from the comparison, the numerical aperture of the condenser lens is increased.
And make the laser beam power small (large)
The height h and width w of the crack spot 90
Can be controlled to be small (large). By the way, crack spots can be formed.
The area where the electric field strength is higher than the threshold value
The region 41 shown is limited to the condensing point P and its vicinity.
The reason is as follows. This embodiment provides high beam quality
Because the laser light source of
The light can be condensed up to about the wavelength of the laser beam. this
Therefore, the beam profile of this laser beam is Gaussian
The distribution of the electric field strength is strongest at the center of the beam,
Strength decreases as the distance from the center increases
The distribution is as follows. This laser beam is actually a condensing lens
In the process of being focused by the
The light is condensed in a cyan distribution state. Therefore, the region 41
Is limited to the condensing point P and its vicinity. As described above, according to this embodiment, a crack is generated.
The spot size can be controlled. Crack spot dimensions
Is required for precise cutting degree, flatness on the cut surface
Determined by considering the degree requirements and the thickness of the workpiece
The The size of the crack spot is the material of the workpiece
It is also possible to decide in consideration of According to this embodiment
For example, the dimensions of the modified spot can be controlled, so the thickness can be compared.
For small workpieces, reduce the modification spot
Can be cut precisely along the planned cutting line.
Cutting with good flatness of the cut surface
It becomes. Also, by increasing the reforming spot,
Even a workpiece having a relatively large thickness can be cut. Also, for example, due to the crystal orientation of the workpiece
Makes it easy to cut and difficult to cut the workpiece.
There may be directions. Cutting such workpieces
For example, as shown in FIG. 20 and FIG.
The size of the crack spot 90 that is formed in the easy direction
Make it smaller. On the other hand, as shown in FIGS.
The direction of the planned cutting line perpendicular to the planned cutting line 5 is cut.
If the direction is difficult, crack spots formed in this direction
The dimension of the G 90 is increased. This makes it easy to cut
A flat cut surface can be obtained in the direction, and cutting is difficult.
Cutting is possible even in difficult directions. It is possible to control the dimensions of the modified spot.
As explained in the case of crack spots,
The same can be said for the spot of refraction and refractive index change.
The The power of the pulse laser beam is, for example, per pulse
It can be expressed in energy (J) or hit one pulse
Is obtained by multiplying the energy of the laser by the frequency of the laser beam.
It can also be expressed as average power (W). Next, a specific example of this embodiment will be described. [First Example] A laser according to the first example of the present embodiment.
The machining apparatus will be described. FIG. 31 shows this laser processing.
2 is a schematic configuration diagram of an apparatus 400. FIG. Laser processing device 400
Are a laser light source 101 that generates laser light L, and a laser.
Laser light source to adjust light L power, pulse width, etc.
A laser light source control unit 102 for controlling 101 and a laser beam
Adjusting the power of the laser beam L emitted from the source 101
A power adjustment unit 401. The power adjustment unit 401 includes, for example, a plurality of NDs.
(neutral density) filter and each ND filter laser
Move to a position perpendicular to the optical axis of the light L or laser light L
And a mechanism for moving it out of the optical path. ND Fi
Ruta is light without changing the relative spectral distribution of energy.
It is a filter that reduces the strength of Multiple ND filters
Each has a different fading rate. The power adjustment unit 401 includes a plurality of
By either one of ND filters or a combination of these
The power of the laser light L emitted from the laser light source 101
To adjust. In addition, the same dimming rate of multiple ND filters
And the power adjusting unit 401 with respect to the optical axis of the laser light L
Changing the number of ND filters moved to a vertical position
As a result of the laser light L emitted from the laser light source 101,
You can also adjust the power. It should be noted that the power adjustment unit 401 is for linearly polarized light.
Polarization film arranged perpendicular to the optical axis of the laser beam L
And a polarizing filter around the optical axis of the laser beam L
And a mechanism that rotates only by an angle. Pa
In the word adjusting unit 401, only a desired angle with respect to the optical axis.
The laser light source 10 is rotated by rotating the polarizing filter.
The power of the laser beam L emitted from 1 is adjusted. It should be noted that the semiconductor laser for excitation of the laser light source 101 is used.
Laser which is an example of drive current control means
The laser light source 1 is controlled by the light source control unit 102.
Adjusting the power of the laser beam L emitted from 01
You can also. Therefore, the power of the laser beam L can be adjusted.
At least one of the unit 401 and the laser light source control unit 102
It can be adjusted by either one. Laser light source control
By simply adjusting the power of the laser beam L by the unit 102
If the size of the region can be set to a desired value, the power adjustment unit 40
1 is unnecessary. The power adjustment described above is performed by the laser.
The operator of the processing apparatus keys the overall control unit 127 described later.
-By inputting the magnitude of power using a board, etc.
It will be done. The laser processing apparatus 400 further includes power adjustment.
Only the laser beam L whose power is adjusted by the node 401 is incident.
The laser beam L is arranged to change the direction of the optical axis by 90 °.
Dichroic mirror 103 and dichroic mirror
A condensing laser that condenses the laser light L reflected by the laser beam 103
Lens selection mechanism 403 including a plurality of lenses and a lens selector
A lens selection mechanism control unit 405 for controlling the structure 403;
Prepare. The lens selection mechanism 403 is a condensing lens 10.
5a, 105b, 105c and supporting plates for supporting them
407. Optics including condensing lens 105a
System numerical aperture, aperture of optical system including condensing lens 105b
The numerical aperture of the optical system including the condensing lens 105c is
Each is different. The lens selection mechanism 403 is a lens selection mechanism.
The support plate 407 is rotated based on a signal from the control unit 405.
By doing so, the condensing lenses 105a, 105b,
The desired condensing lens among the laser beams L from 105c
Place on the axis. That is, the lens selection mechanism 403
Revolver type. It is attached to the lens selection mechanism 403.
The number of condensing lenses to be used is not limited to three, but any other number
But you can. The whole that the operator of the laser processing device will explain later
Use a keyboard or the like for the control unit 127 to adjust the numerical aperture.
Is the condensing lens 105a, 105b, 105c
By entering an instruction to select one of them.
Is selected, that is, the numerical aperture is selected. The laser processing apparatus 400 further includes a condensing laser.
Are arranged on the optical axis of the laser beam L among the laser beams 105a to 105c.
The laser beam L collected by the placed focusing lens is irradiated.
Mounting table 107 on which workpiece 1 to be processed is mounted, and mounting table
X-axis stage 109 for moving 107 in the X-axis direction
And the mounting table 107 is moved in the Y-axis direction orthogonal to the X-axis direction.
Y-axis stage 111 and mounting table 107 for
Z axis for moving in the Z axis direction perpendicular to the Y axis direction
Stage 113 and these three stages 109, 111,
A stage control unit 115 for controlling the movement of 113.
Yeah. The Z-axis direction is orthogonal to the surface 3 of the workpiece 1
The direction of the laser beam L incident on the workpiece 1
Point depth direction. Therefore, the Z-axis stage 113 is
By moving it in the direction.
-The condensing point P of the laser beam L can be adjusted. Also this
The movement of the focal point P in the X (Y) axis direction moves the workpiece 1 to the X (Y) axis.
Move in the X (Y) axis direction by stage 109 (111)
To do. X (Y) axis stage 109 (111)
It becomes an example of a moving means. The laser light source 101 generates pulsed laser light.
Nd: YAG laser. Used for laser light source 101
In addition, Nd: YVO _Four Laser or Nd:
There are YLF laser and titanium sapphire laser. crack
Nd: YAG laser, N
d: YVO _Four It is preferable to use a laser or an Nd: YLF laser.
When forming the refractive index change region, titanium sapphire array
It is preferable to use Z. In the first example, pulse processing is used for machining the workpiece 1.
-Ther light is used, but it can cause multiphoton absorption
If possible, continuous wave laser light may be used. Condensing lens 10
Reference numerals 5a to 105c are examples of light collecting means. Z axis stage
113 aligns the condensing point of the laser beam with the inside of the workpiece.
This is an example of the means. Condensing lenses 105a to 105c
The laser beam can also be collected by moving the
The light spot can be adjusted to the inside of the workpiece. The laser processing apparatus 400 further includes a mounting table 1.
Illuminate the workpiece 1 placed on 07 with visible light
An observation light source 117 that generates visible light and a die
Same as Croix mirror 103 and condensing lens 105
Visible light beam splitter 119 arranged on the optical axis
And comprising. Beam splitter 119 and condensing lens
Dichroic mirror 103 is arranged between
ing. Beam splitter 119 is about half of visible light
And has the function of reflecting the other half and visible light
Are arranged so as to change the direction of the optical axis by 90 °. View
Visible light generated from the observation light source 117 is beam splitted.
About half of the reflected light is reflected by the reflected light ray 119.
The dichroic mirror 103 and the condensing lens 105
That includes the scheduled cutting line 5 of the workpiece 1
Illuminate surface 3. The laser processing apparatus 400 further includes a beam scanner.
Plitter 119, dichroic mirror 103 and light collecting
Imaging device 12 disposed on the same optical axis as lens 105
1 and an imaging lens 123. As the image sensor 121
For example, there is a CCD (charge-coupled device) camera.
Of visible light illuminating the surface 3 including the line 5 to be cut, etc.
The reflected light is a condensing lens 105, a dichroic mirror.
103, the beam splitter 119, and the imaging lens
123 is imaged and imaged by the image sensor 121,
Data. The laser processing apparatus 400 further includes an image sensor.
Imaging data to which the imaging data output from 121 is input
Control unit 125 and the entire laser processing apparatus 400.
A general control unit 127 and a monitor 129. Shoot
The image data processing unit 125 is used for observation based on the imaging data.
The visible light generated by the light source 117 is focused on the surface 3.
The focus data for calculating is calculated. Based on this focus data
The stage controller 115 moves the Z-axis stage 113.
By controlling, the visible light is focused on the surface 3
To. Therefore, the imaging data processing unit 125
It functions as a digital unit. In addition, imaging data processing
The unit 125 is an enlarged image of the surface 3 based on the imaging data
The image data is calculated. This image data is stored in the overall control unit.
127, and various processes are performed by the overall control unit.
129. This expands to the monitor 129
Images etc. are displayed. The overall controller 127 includes a stage controller 1
15 and image from the imaging data processing unit 125
Data etc. are input, and laser light is also based on these data.
Source control unit 102, observation light source 117, and stage control unit
115 to control the entire laser processing apparatus 400.
Control the body. Therefore, the overall control unit 127 is a computer.
Function as a data unit. In addition, the overall control unit 127 is
The power adjustment unit 401 is electrically connected. FIG.
The illustration is omitted. Power to the overall control unit 127
Is input, the overall control unit 127
Controls the power adjustment unit 401 to adjust the power
Is done. FIG. 32 shows a part of an example of the overall control unit 127.
FIG. The overall control unit 127 selects dimensions.
Selection unit 411, correlation storage unit 413, and image creation unit 41
5 is provided. The dimension selection unit 411 is operated by a laser processing apparatus.
The author can control the power of pulsed laser light using a keyboard.
The size and the numerical aperture of the optical system including the condenser lens
Entered. In this example, the numerical aperture is directly
Condensing lenses 105a, 105b, 10 instead of input
An input for selecting one of 5c may be used. This place
In this case, the collective lenses 105a and 105 are connected to the overall control unit 127.
b, 105c, each numerical aperture is registered in advance and selected.
The numerical aperture data of the optical system including the selected condenser lens
It is automatically input to the dimension selection unit 411. The correlation storage unit 413 includes a pulse laser.
A set of light power and numerical aperture and a modified spot
The correlation with the dimensions of the robot is stored in advance. FIG.
Is an example of a table showing this correlation. This example
Then, in the column of the numerical aperture, condensing lenses 105a and 105b,
For each of 105c, the numerical aperture of the optical system including them
Is registered. In the power column, the power adjustment unit 401
The power level of the pulsed laser beam to be adjusted is registered.
It is. The dimension column shows the power and numerical aperture of the corresponding set.
The dimensions of the modified spots formed by the combination are registered
Is done. For example, the power is 1.24 × 10 ¹¹ (W / cm ² )
The modified spot formed when the numerical aperture is 0.55
The dimension is 120 μm. This correlation data is
For example, the experiment described in FIGS. 22 to 29 before laser processing
It can be obtained by doing. The size selection unit 411 has a power level and an opening level.
By inputting the size of the number of units, the dimension selection unit 41
1 is the same value as these sizes from the correlation storage unit 413
Select a set and monitor the dimension data corresponding to that set.
129. As a result, it is input to the monitor 129.
Formed under the magnitude of power and numerical aperture.
The size of the modified spot is displayed. These sizes and
If there is no pair with the same value, the dimension corresponding to the closest pair
Legal data is sent to the monitor 129. Corresponding to the group selected by the dimension selection unit 411
Dimension data is obtained from the dimension selection unit 411 to the image creation unit 4.
15 is sent. The image creation unit 415 stores data of this dimension.
The image data of the modified spot of this dimension is created based on the data.
And send it to the monitor 129. As a result, the monitor 129
The image of the modified spot is also displayed. Therefore, laser
Know the dimensions of the modified spot and the shape of the modified spot before processing
Can. The power is fixed and the numerical aperture is large.
Can be made variable. The table in this case is shown in FIG.
As shown in FIG. For example, the power is 1.49 × 10
¹¹ (W / cm ² ) And fixed when the numerical aperture is 0.55
The size of the modified spot is 150 μm. Also open
The number of units is fixed and the power is variable.
You can also. The table in this case is as shown in FIG.
Become. For example, the numerical aperture is fixed at 0.8 and the power is 1.1.
9x10 ¹¹ (W / cm ² ) Modified spots formed during
The dimension is 30 μm. Next, the present embodiment will be described with reference to FIGS.
A laser processing method according to the first example of the embodiment will be described. FIG.
Is a flow chart for explaining this laser processing method.
Is. The workpiece 1 is a silicon wafer. First, the light absorption characteristics of the workpiece 1 are illustrated.
Measure with a spectrophotometer. Based on this measurement result
A wavelength transparent to the workpiece 1 or little absorption
Select a laser light source 101 that generates laser light L with a long wavelength
(S101). Next, the thickness of the workpiece 1 is measured.
The Based on the thickness measurement result and the refractive index of the workpiece 1
Thus, the amount of movement of the workpiece 1 in the Z-axis direction is determined (S10
3). This is because the condensing point P of the laser beam L is within the workpiece 1
Is located on the surface 3 of the workpiece 1
Z-axis direction of the workpiece 1 with reference to the focal point of the laser beam L
The amount of movement in the direction. This movement amount is input to the overall control unit 127.
It is powered. The object 1 to be processed is mounted on the laser processing apparatus 400.
It is mounted on the mounting table 107. From the observation light source 117
Visible light is generated to illuminate the workpiece 1 (S10)
5). Work object 1 including illuminated cutting line 5
The surface 3 is imaged by the image sensor 121. This imaging device
The data is sent to the imaging data processing unit 125. This imaging device
On the basis of the data, the imaging data processing unit 125 uses the observation light source 1.
Focus data such that 17 visible light focuses on the surface 3
(S107). This focus data is sent to the stage controller 115.
Sent. The stage controller 115 uses the focus data
Based on this, the Z-axis stage 113 is moved in the Z-axis direction (S
109). As a result, the focus of visible light from the observation light source 117 is increased.
A point is located on the surface 3. The imaging data processing unit 125
Is processing including the planned cutting line 5 based on the imaging data
The enlarged image data of the surface 3 of the object 1 is calculated. This expansion
Large image data is sent to the monitor 129 via the overall control unit 127.
This causes the monitor 129 to send a cut line 5
A nearby enlarged image is displayed. The overall control unit 127 is previously provided with step S10.
The movement amount data determined in step 3 has been entered.
The movement amount data is sent to the stage control unit 115. Stay
On the basis of this movement amount data, the control unit 115
At the position where the condensing point P of the light L is inside the workpiece 1, the Z axis
The workpiece 1 is moved in the Z-axis direction by the stage 113.
(S111). Next, as described above, power and open
The number of units is input to the overall control unit 127. Entered
Based on the measured power data, the power of the laser beam L
It is adjusted by the word adjustment unit 401. Input numerical aperture
Based on the data, the numerical aperture is determined by the lens selection mechanism control unit 4.
The lens selection mechanism 403 selects the condensing lens via 05.
It is adjusted by selecting. Also, these data are
Input to the dimension selection unit 411 (FIG. 32) of the overall control unit 127
Is done. As a result, irradiation with one pulse of laser light L
Of the melt processing spot formed inside the workpiece 1
Dimensions and shape of melt processing spot are displayed on monitor 129
(S112). Next, the laser light L is emitted from the laser light source 101.
The laser beam L is generated and the surface 3 of the workpiece 1 is cut.
Irradiate the planned line 5. The focal point P of the laser beam L is the machining pair.
Since it is located inside the figurine 1, the melt processing area is processed.
It is formed only inside the object 1. And the cutting schedule
X-axis stage 109 and Y-axis stage 1 along in-5
11 is moved and the melt processing area is moved to the cutting line 5
It forms in the inside of the workpiece 1 so that it may follow (S11)
3). Then, the workpiece 1 is cut along the planned cutting line 5
The workpiece 1 is cut by bending it (S11).
5). As a result, the workpiece 1 is divided into silicon chips.
Divide. The effect of the first example will be described. According to this,
Inside the workpiece 1 under conditions that cause multiphoton absorption
Align the focusing point P with the laser beam L to be cut.
5 is irradiated. And X axis stage 109 and Y axis
By moving the stage 111, the focal point P is turned off.
It is moved along the scheduled disconnection line 5. This
Modified region (for example, crack region, melt processing region, refractive index)
(Working area) along the planned cutting line 5
1 is formed inside. At the point where the workpiece is cut
If there is any starting point, the workpiece can be moved with a relatively small force.
Can be broken and cut. Therefore, starting from the reforming region
Break the workpiece 1 along the cutting line 5 as
To cut the workpiece 1 with a relatively small force.
You can. This cuts the surface 3 of the workpiece 1
To generate unnecessary cracks that deviate from the planned line 5
The workpiece 1 can be cut without any problems. Further, according to the first example, there are many processing objects 1.
Under conditions that cause photon absorption and inside the workpiece 1
The line where the focused laser beam P is aligned and the pulse laser beam L is to be cut
5 is irradiated. Therefore, the pulse laser beam L
The object passes through the object 1 and the pulse 3
Since the light L is hardly absorbed,
Therefore, the surface 3 is not damaged such as melting. As explained above, according to the first example, the machining
Unnecessary of being off the planned cutting line 5 on the surface 3 of the object 1
The workpiece 1 without cutting or melting
Can. Therefore, the workpiece 1 is, for example, a semiconductor
In the case of a wafer, the semiconductor chip is off the cutting line.
Semiconductor chips without unnecessary cracking or melting
Can be cut from the semiconductor wafer. Electrode on the surface
The workpiece on which the pattern is formed and the piezoelectric element wafer
Like glass substrates on which display devices such as C and liquid crystal are formed
For workpieces with electronic devices formed on the surface
But the same is true. Thus, according to the first example, the object to be processed
Products manufactured by cutting
, Piezoelectric device chips, liquid crystal display devices)
Marriage can be improved. Further, according to the first example, the table of the workpiece 1 is shown.
Since the planned cutting line 5 of the surface 3 does not melt,
Width of the inner 5 (this width is, for example, in the case of a semiconductor wafer, half
This is the distance between the regions that become the conductor chips. Small)
Yes. Thereby, it is produced from one piece of processing object 1.
Increase the number of products and improve product productivity
The Further, according to the first example, the cutting of the workpiece 1 is performed.
Since laser light is used for cutting,
More complicated processing than the dicing used is possible. example
For example, as shown in FIG.
Even so, according to the first example, cutting is possible. This
These effects are the same in the examples described later. [Second Example] Next, a second example of this embodiment will be described.
The difference from the first example will be mainly described. Figure 38 shows this layout.
It is a schematic block diagram of the processing apparatus 500. Laser processing equipment
Among the 500 components, the label according to the first example shown in FIG.
-The same components as the components of the laser processing device 400 are the same.
The description is omitted by assigning a reference numeral. The laser processing apparatus 500 includes a power adjustment unit 4.
Laser light L between 01 and the dichroic mirror 103
A beam expander 501 is arranged on the optical axis of
The The beam expander 501 has a variable magnification, and
The beam expander 501 increases the beam diameter of the laser beam L
It is adjusted so that it becomes necessary. Beam expander 501
Is an example of a numerical aperture adjusting means. Laser processing equipment
500 is for condensing instead of the lens selection mechanism 403
A lens 105 is provided. The operation of the laser processing apparatus 500 is the same as that of the first example.
The difference from the operation of the laser processing device is that the overall control unit 127
The numerical aperture is adjusted based on the input numerical aperture size.
The This will be described below. The overall control unit 127 is
The beam expander 501 is electrically connected.
In FIG. 38, this illustration is omitted. In the overall control unit 127
By inputting the size of the numerical aperture, the overall control unit 1
27 is a control for changing the magnification of the beam expander 501.
To do. As a result, the laser beam incident on the condensing lens 105 is
Adjust the magnification of the beam diameter of the light L. Therefore, for collecting light
Even if there is only one lens 105, the condensing lens 105
It is possible to adjust to increase the numerical aperture of the optical system. This
This will be described with reference to FIGS. 39 and 40. FIG. In FIG. 39, the beam expander 501 is arranged.
Laser with condensing lens 105 when not placed
FIG. 4 is a diagram showing the collection of light L. On the other hand, FIG.
Condensing lens when Xspanda 501 is arranged
FIG. 10 is a diagram showing the focusing of laser light L by 105. FIG.
As shown in FIG. 40 and FIG.
Condensing lens 10 in the case where the solder 501 is not disposed
In the second example, the numerical aperture of the optical system including
The number can be adjusted to be large. [Third Example] Next, a third example of this embodiment will be described.
The explanation will focus on the differences from the previous examples. Figure 41 shows this
It is a schematic block diagram of the laser processing apparatus 600 of. Laser processing
Among the components of the construction equipment 600, the records related to the examples so far
-The same symbols are used for the same elements as the components of the laser processing machine
The description is omitted by attaching. The laser processing apparatus 600 has a beam explorer.
Dichroic mirror 103 instead of
Iris on the optical axis of the laser beam L between the condensing lens 105
A diaphragm 601 is disposed. The opening of the iris diaphragm 601
The effective diameter of the condensing lens 105 is changed by changing the size.
Adjust. The iris diaphragm 601 is an example of numerical aperture adjusting means.
is there. In addition, the laser processing apparatus 600 includes an iris diaphragm 601.
Iris diaphragm controller 603 for controlling the size of the aperture
Is provided. The iris diaphragm control unit 603 is connected to the overall control unit 127.
More controlled. The operation of the laser processing apparatus 600 has been performed so far.
The difference from the operation of the example laser processing apparatus is that the overall control unit 1
Adjustment of the numerical aperture based on the numerical aperture input to 27
It is. The laser processing apparatus 600 has a large input numerical aperture.
Change the size of the aperture of the iris diaphragm 601 based on the size
This reduces the effective diameter of the condensing lens 105.
Make a clause. As a result, the number of condensing lenses 105 is one.
However, the numerical aperture of the optical system including the condensing lens 105 is reduced.
It can be adjusted to be small. This is shown in FIG.
This will be described with reference to FIG. FIG. 42 shows a case where no iris diaphragm is arranged.
The condensing of the laser beam L by the condensing lens 105 is shown.
FIG. On the other hand, in FIG. 43, the iris diaphragm 601 is arranged.
Of the laser light L by the condensing lens 105
It is a figure which shows light. Compare Figure 42 and Figure 43
As shown in FIG.
If the numerical aperture of the optical system including
In the example, the numerical aperture can be adjusted to be small.
The Next, a modification of this embodiment will be described. Figure
44 is provided in a modification of the laser processing apparatus of this embodiment.
2 is a block diagram of the overall control unit 127. FIG. Overall control unit 1
27 includes a power selection unit 417 and a correlation storage unit 413.
Prepare. The correlation storage unit 413 stores the correlation shown in FIG.
Related data is stored in advance. Laser processing equipment
The operator modifies the power selection unit 417 with a keyboard or the like.
Enter the desired dimensions of the spot. Modification spot dimensions
Is determined in consideration of the thickness and material of the workpiece.
By this input, the power selection unit 417 causes the correlation storage unit to
From 413, the power corresponding to the same value as this dimension
Selected, and the power data is sent to the power adjustment unit 401.
The Therefore, the laser power adjusted to the magnitude of this power
Modification of desired dimensions by laser processing with a processing device
Spots can be formed. Great power
The size data is also sent to the monitor 129, where the power is large.
Is displayed. In this example, the numerical aperture is fixed and power is possible.
It becomes strange. Note that dimensions with the same value as the input dimension are correlated.
If not stored in the relationship storage unit 413, the closest value
The power data corresponding to the dimensions of the
And sent to the monitor 129. This is a variable described below.
The same applies to the examples. FIG. 45 shows another laser processing apparatus according to this embodiment.
FIG. 4 is a block diagram of an overall control unit 127 provided in the modification example of FIG.
is there. The overall control unit 127 includes a numerical aperture selection unit 419 and a correlation.
A relationship storage unit 413 is provided. Differences from the modification of FIG.
Is that the numerical aperture is selected instead of power. phase
In the relationship storage unit 413, the data shown in FIG.
It is remembered. The operator of the laser processing equipment is a keyboard etc.
The numerical aperture selection unit 419 causes the desired size of the modified spot.
Enter. Thereby, the numerical aperture selection unit 419 performs correlation.
Corresponds to a dimension having the same value as this dimension from the relationship storage unit 413.
The numerical aperture is selected and the numerical aperture data is selected by the lens selector.
Structure controller 405, beam expander 501, or iris diaphragm
To the control unit 603. Therefore, the size of this numerical aperture
By laser processing with controlled laser processing equipment
It is possible to form a modified spot with a desired size
Become. The numerical aperture data is also sent to the monitor 129.
Sent and the numerical aperture is displayed. In this example, power
-Is fixed and the numerical aperture is variable. FIG. 46 shows the laser processing apparatus of this embodiment.
In addition, the block of the overall control unit 127 provided in another modification is provided.
FIG. The overall control unit 127 includes a set selection unit 421 and a phase.
A relationship storage unit 413 is provided. 44 and 45
The difference is that both power and numerical aperture are selected.
It is. The correlation storage unit 413 stores the power and power shown in FIG.
And the correlation data between the numerical aperture pair and dimensions are stored in advance.
It is. The operator of the laser processing device uses a keyboard, etc.
The desired size of the modified spot is input to the group selection unit 421
The As a result, the pair selection unit 421 causes the correlation storage unit 4
13 to the power corresponding to the same value as this dimension and
Select a set of numerical apertures. Power data for the selected set
Is sent to the power adjustment unit 401. Meanwhile, the selected pair
Numerical aperture data of the lens selection mechanism control unit 405,
Sent to the mu expander 501 or the iris diaphragm control unit 603
It is. Therefore, adjust the power and numerical aperture of this set.
By laser processing with the laser processing equipment
It becomes possible to form a modified spot of a desired size
The The power and numerical aperture data for this set are
The power and numerical aperture are also displayed.
Is done. According to these modifications, the modification spots
The dimensions can be controlled. Therefore, the reforming spot
By reducing the dimensions, the workpiece to be cut
Able to cut precisely along the in and get a flat cut surface
be able to. If the thickness of the workpiece is large,
Cutting the workpiece by increasing the pot dimensions
Can be interrupted. According to the laser processing apparatus of the present invention,
A crack that is not on the surface of the workpiece to be melted or cut
The workpiece can be cut without causing this.
The Therefore, it is produced by cutting the workpiece.
Products (for example, semiconductor chips, piezoelectric device chips,
To improve the yield and productivity of LCDs.
You can. According to the laser processing apparatus of the present invention, the modification
The size of the quality spot can be controlled. For this reason,
The workpiece can be precisely cut along the
A cut surface can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of an object to be processed during laser processing by the laser processing method according to the present embodiment. FIG. 2 is a cross-sectional view taken along the line II-II of the workpiece shown in FIG. FIG. 3 is a plan view of an object to be processed after laser processing by the laser processing method according to the present embodiment. 4 is a cross-sectional view taken along line IV-IV of the workpiece shown in FIG. FIG. 5 is a cross-sectional view taken along line VV of the workpiece shown in FIG. FIG. 6 is a plan view of a processing object cut by the laser processing method according to the present embodiment. FIG. 7 is a graph showing the relationship between electric field strength and crack size in the laser processing method according to the present embodiment. FIG. 8 is a cross-sectional view of an object to be processed in a first step of the laser processing method according to the present embodiment. FIG. 9 is a cross-sectional view of an object to be processed in a second step of the laser processing method according to the present embodiment. FIG. 10 is a cross-sectional view of an object to be processed in a third step of the laser processing method according to the present embodiment. FIG. 11 is a cross-sectional view of an object to be processed in a fourth step of the laser processing method according to the present embodiment. FIG. 12 is a view showing a photograph of a cross section of a part of a silicon wafer cut by the laser processing method according to the embodiment. FIG. 13 is a graph showing the relationship between the wavelength of laser light and the transmittance inside the silicon substrate in the laser processing method according to the present embodiment. FIG. 14 is a plan view of an object to be processed when a relatively large crack spot is formed using the laser processing method according to the present embodiment. 15 is a cross-sectional view taken along XV-XV on the planned cutting line shown in FIG. 16 is an XVI- orthogonal to the planned cutting line shown in FIG.
It is sectional drawing cut | disconnected along XVI. FIG. 17 is XVII orthogonal to the planned cutting line shown in FIG.
It is sectional drawing cut | disconnected along -XVII. 18 is XVII orthogonal to the planned cutting line shown in FIG.
It is sectional drawing cut | disconnected along I-XVIII. FIG. 19 is a plan view of the workpiece shown in FIG. 14 cut along a planned cutting line. FIG. 20 is a cross-sectional view of an object to be processed along a planned cutting line when a crack spot is formed to be relatively small using the laser processing method according to the present embodiment. FIG. 21 is a plan view of the workpiece shown in FIG. 20 cut along a planned cutting line. FIG. 22 is a cross-sectional view of an object to be processed showing a state in which pulse laser light is condensed inside the object to be processed using a condensing lens having a predetermined numerical aperture. 23 is a cross-sectional view of an object to be processed including crack spots formed due to multiphoton absorption caused by laser light irradiation shown in FIG. 24 is a cross-sectional view of an object to be processed when a condensing lens having a larger numerical aperture than the example shown in FIG. 22 is used. 25 is a cross-sectional view of an object to be processed including crack spots formed due to multiphoton absorption by laser light irradiation shown in FIG. 24. FIG. 26 is a cross-sectional view of an object to be processed when pulse laser light having a smaller power than the example shown in FIG. 22 is used. 27 is a cross-sectional view of an object to be processed including crack spots formed due to multiphoton absorption by laser light irradiation shown in FIG. 26. FIG. FIG. 28 is a cross-sectional view of an object to be processed when pulse laser light having a smaller power than the example shown in FIG. 24 is used. 29 is a cross-sectional view of an object to be processed including crack spots formed due to multiphoton absorption by laser light irradiation shown in FIG. 28. FIG. 30 is a cross section of XXX− perpendicular to the planned cutting line shown in FIG.
It is sectional drawing cut | disconnected along XXX. FIG. 31 is a schematic configuration diagram of a laser processing apparatus according to the first example of the present embodiment. FIG. 32 is a block diagram illustrating a part of an example of an overall control unit provided in the laser processing apparatus according to the present embodiment. FIG. 33 is a diagram showing an example of a table of a correlation storage unit included in the overall control unit of the laser processing apparatus according to the present embodiment. FIG. 34 is a diagram showing another example of the table of the correlation storage unit included in the overall control unit of the laser processing apparatus according to the present embodiment. FIG. 35 is a diagram showing still another example of the table of the correlation storage unit included in the overall control unit of the laser processing apparatus according to the present embodiment. FIG. 36 is a flowchart for explaining a laser processing method according to the first example of the embodiment; FIG. 37 is a plan view of a processing object for explaining a pattern that can be cut by the laser processing method according to the first example of the embodiment; FIG. 38 is a schematic configuration diagram of a laser processing apparatus according to a second example of the present embodiment. FIG. 39 is a diagram showing laser beam focusing by a focusing lens when no beam expander is arranged. FIG. 40 is a diagram showing laser beam condensing by a condensing lens when a beam expander is arranged. FIG. 41 is a schematic configuration diagram of a laser processing apparatus according to a third example of the present embodiment. FIG. 42 is a diagram showing laser beam condensing by a condensing lens when no iris diaphragm is arranged. FIG. 43 is a diagram showing laser beam condensing by a condensing lens when an iris diaphragm is disposed. FIG. 44 is a block diagram illustrating an example of an overall control unit provided in a modification of the laser processing apparatus according to the present embodiment. FIG. 45 is a block diagram of another example of the overall control unit provided in the modification of the laser processing apparatus of the present embodiment. FIG. 46 is a block diagram of still another example of the overall control unit provided in the modification of the laser processing apparatus of the present embodiment. [Explanation of Symbols] 1 ... workpiece, 3 ... surface, 5 ... scheduled line, 7 ... modified region, 9 ... crack region, 1
DESCRIPTION OF SYMBOLS 1 ... Silicon wafer, 13 ... Melting process area, 4
DESCRIPTION OF SYMBOLS 1 ... Area | region, 43 ... Cut surface, 90 ... Crack spot, 101 ... Laser light source, 105, 105a,
105b, 105c ... Condensing lens, 109 ... X
Axis stage, 111 ... Y axis stage, 113 ... Z
Axis stage, 400... Laser processing apparatus, 401.
Power adjustment unit, 403 ... lens selection mechanism, 411
... Dimension selection unit, 413 ... Correlation storage unit, 41
5... Image creation unit, 417... Power selection unit, 41
9: Numerical aperture selection unit, 421: Set selection unit, 500
... Laser processing device, 501 ... Beam expander, 600 ... Laser processing device, 601 ... Iris diaphragm, P ... Condensing point

─────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme code (reference) C03B 33/09 C03B 33/09 H01L 21/301 B23K 101: 40 // B23K 101: 40 H01L 21/78 B (72) Inventor Naomi Uchiyama 1 1126 Nomachi, Hamamatsu City, Shizuoka Prefecture 1 Hamamatsu Photonics Co., Ltd. (72) Inventor Toshimitsu Wakuda 1126 Nomachi, Hamamatsu City, Shizuoka Prefecture 1 ) 3C069 AA01 BA08 BB01 BB02 BB04 CA05 CA11 EA02 EA05 4E068 AA01 AD00 AE01 CA02 CA03 CA07 CA11 CB03 CB04 CD13 DA10 DB13 4G015 FA04 FA06 FB01 FC01 FC14

Claims (1)

1. A laser light source that emits a pulse laser beam having a pulse width of 1 μs or less, and a pulse laser beam emitted from the laser light source based on an input of the magnitude of the power of the pulse laser beam Power adjusting means for adjusting the magnitude of the power of the laser, and the pulse laser beam so that the peak power density at the condensing point of the pulse laser beam emitted from the laser light source is 1 × 10 ⁸ (W / cm ² ) or more. A condensing lens for condensing light, a numerical aperture adjusting means for adjusting the numerical aperture of an optical system including the condensing lens based on an input of the numerical aperture, and the condensing lens Means for aligning the condensing point of the condensed pulsed laser light with the inside of the object to be processed; and moving means for relatively moving the condensing point of the pulsed laser light along the planned cutting line of the object to be processed; Comprising the above By irradiating the pulse laser beam of one pulse with its focusing point on the workpiece in part, 1 to the internal
Two modified spots are formed, and the correlation between the magnitude of the power of the pulsed laser beam adjusted by the power adjusting means and the size of the numerical aperture adjusted by the numerical aperture adjusting means and the size of the modified spot Correlation storage means for storing the relationship in advance, and the size of the modified spot formed at these magnitudes based on the magnitude of the power of the inputted pulsed laser beam and the magnitude of the inputted numerical aperture A laser processing apparatus, comprising: a dimension selecting unit that selects from the correlation storage unit; and a dimension displaying unit that displays a dimension of the modified spot selected by the dimension selecting unit.