JP4158481B2 - Laser processing method and apparatus, and drilling method using the apparatus - Google Patents

Laser processing method and apparatus, and drilling method using the apparatus Download PDF

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JP4158481B2
JP4158481B2 JP2002305573A JP2002305573A JP4158481B2 JP 4158481 B2 JP4158481 B2 JP 4158481B2 JP 2002305573 A JP2002305573 A JP 2002305573A JP 2002305573 A JP2002305573 A JP 2002305573A JP 4158481 B2 JP4158481 B2 JP 4158481B2
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beam
intensity distribution
laser
diffractive optical
region
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JP2004136358A (en
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淳 尼子
永一 藤井
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セイコーエプソン株式会社
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Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laser processing method and apparatus for forming a modified region in a transparent material using a laser in the process of forming a hole or groove by removing the modified region formed in a transparent material such as quartz glass, The present invention also relates to a drilling method using the apparatus.
[0002]
[Prior art]
In the conventional laser processing method, a workpiece made of a transparent material such as quartz glass is placed on a stage that can be moved in the vertical direction by a movable means including a driving means such as a motor, and the thickness of the workpiece. Irradiate the position of the upper end of the through-hole formed in the (depth) direction (upper surface of the workpiece) with, for example, an ultrashort pulse laser beam condensed by a condenser lens and move the stage upward. The beam is moved in the depth direction of the workpiece, and is grown for a long time while being physically altered in the depth direction in the region where the through hole is formed in the workpiece, thereby forming a modified region corresponding to the through hole. Incidentally, physical property alteration means that physical properties such as dielectric constant change compared to before laser irradiation, and the transparent material is altered only in the region where the laser intensity exceeds the processing threshold in the laser irradiation part in the workpiece. To do. Then, the workpiece on which the altered region is formed by the laser is immersed in a solvent, and the altered region is removed by solvent etching to form a through hole. At this time, the etching of the altered region that is the laser irradiation portion proceeds faster, and the etching of the portion other than the altered region that is the laser unirradiated portion proceeds more slowly (see, for example, Non-Patent Document 1).
[0003]
[Non-Patent Document 1]
“Optics Letters Vol. 26” (USA), 5th edition, Optical Society of America, 2001, p. 277-279
[0004]
[Problems to be solved by the invention]
In the conventional laser processing method as described above, the altered region for forming the through hole of the workpiece is formed by moving the beam irradiation point in the depth (thickness) direction. The point is moved by moving the stage on which the workpiece is placed in the vertical direction using a movable means. The size of the altered region is from several μm to several tens of μm, and depends on the laser intensity distribution. The general factors that determine the laser intensity distribution are the laser beam intensity, beam diameter, and light concentration. The laser irradiation conditions such as the condensing distance of the lens, the condensing system NA (Numerical Aperture, the figure of merit of the lens determined from the effective diameter of the condensing lens and the condensing distance), etc. The beam irradiation point was moved. However, in order to form the altered region formed on the workpiece at a desired position and size, the movable means must be moved in accordance with the laser irradiation conditions. Precision and accuracy are required, and in order to meet the requirements, the structure of the movable means is complicated and large, and the cost is high. There was a problem such as.
[0005]
The present invention has been made in order to solve the above-described problems. The movable region is omitted, and a desired region in which a through hole or the like of the workpiece is formed without moving the workpiece or the beam irradiation point. An object of the present invention is to provide a laser processing method and apparatus capable of forming an altered region by irradiating a laser beam on the surface, improving the processing efficiency while reducing costs, and a drilling method using the apparatus. It is what.
[0008]
[Means for Solving the Problems]
  The laser processing method according to the present invention uses a laser beam that is an ultrashort pulse laser beam.A non-diffracted beam having a predetermined intensity distribution along the optical axis direction is generated by shaping through a diffractive optical element, and a beam of an intensity distribution portion above the predetermined level of the non-diffracted beam is formed into a transparent workpiece. Irradiating at least in correspondence with a desired region in the thickness direction, and processing the entire region of the desired region with the beam..
[0009]
  Also,The laser processing method according to the present invention comprises:A laser beam, which is an ultrashort pulse laser beam, is shaped through a diffractive optical element to form a beam having an intensity distribution in which light energy is condensed and localized in a predetermined region along the optical axis direction, and the intensity distribution The partial beam is irradiated so as to correspond to at least a desired region in the thickness direction of the transparent workpiece, and the entire region of the desired region is processed by the beam.
[0010]
  Further, the laser processing method according to the present invention includes arranging a plurality of diffractive optical elements in series on the optical axis, shaping a laser beam that is an ultrashort pulse laser beam through the plurality of diffractive optical elements, and A beam having an intensity distribution in which light energy is condensed and localized along a direction is formed, and the beam in the intensity distribution portion is made to correspond to at least a desired area in the thickness direction of the transparent workpiece. Irradiating and processing the entire desired area with the beam..
  In the above method, the desired region of the workpiece is a region where a hole or a groove is formed.
[0012]
  According to the present inventionA laser processing apparatus for processing a transparent workpiece includes a laser oscillator that oscillates an ultrashort pulse laser beam, and a diffractive optical element that shapes the ultrashort pulse laser beam emitted from the laser oscillator,
  The diffractive optical element generates a non-diffracted beam having a predetermined intensity distribution along the optical axis direction.
[0013]
  A laser processing apparatus for processing a transparent workpiece according to the present invention includes a laser oscillator that oscillates an ultrashort pulse laser beam, and a diffractive optical element that shapes the ultrashort pulse laser beam emitted from the laser oscillator. With
  The diffractive optical element generates a beam having an intensity distribution in which light energy is condensed and localized in a predetermined region along the optical axis direction.
[0014]
  A laser processing apparatus for processing a transparent workpiece according to the present invention includes a laser oscillator that oscillates an ultrashort pulse laser beam and an optical axis that shapes the ultrashort pulse laser beam emitted from the laser oscillator. A plurality of diffractive optical elements arranged in series,
  A combination of the plurality of diffractive optical elements generates a beam having an intensity distribution in which light energy is condensed and localized in a predetermined region along the optical axis direction..
[0015]
The drilling method according to the present invention uses any one of the laser processing apparatuses described above to irradiate a desired region in the thickness direction of the work piece with a beam for processing the work piece, thereby changing the physical properties. The altered region is removed by solvent etching to form a hole or groove. According to this, a hole or a groove can be formed in a short time, and the processing efficiency can be improved while suppressing high cost.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
FIG. 1 is a configuration explanatory view of a main part of a laser processing apparatus according to Embodiment 1 of the present invention, and FIG. 2 is a plan view of a diffractive optical element according to the laser processing apparatus. In the figure, reference numeral 1 denotes a diffractive optical element made of a transparent material such as quartz and having a concavity and convexity formed on the surface and having an equal period p. The laser beam 2 oscillated from a laser oscillator (not shown) having a predetermined intensity distribution for processing a workpiece to be described later is non-diffracted on the optical axis X and in the vicinity thereof. Beam). When an ultrashort pulse such as femtosecond is used, there are many problems such as deterioration of the pulse quality when the laser beam passes through the optical device. For this reason, it is desirable to reduce the influence on the pulse by reducing the thickness of the optical device. Since the diffractive optical element 1 is sufficiently thin, the influence on the pulse can be reduced, and this is used in the present invention.
[0017]
Here, a manufacturing process of the diffractive optical element 1 will be briefly described.
(1) First, a resist is applied to a quartz substrate that forms the diffractive optical element 1.
(2) Next, the resist is exposed with a focused laser beam, and the resist is patterned. At the time of exposure, the amount of exposure is changed for each location in accordance with the shape to be realized (here, a concentric pattern with the same period p). Thereafter, the resist is developed to form a resist pattern (uneven shape).
(3) Next, an ionized gas (for example, CHF) is formed on the resist pattern.Three), And using the same pattern as a mask, ion etching for transferring the pattern to the quartz substrate is performed.
(4) After ion etching, the remaining resist is removed to form a diffractive optical element 1 having a desired concavo-convex shape (a shape to be realized) on a quartz substrate.
[0018]
Since the surface of the diffractive optical element 1 formed in this way is formed in a concentric pattern with the same period p, phase modulation can be applied to the laser beam wavefront, thereby processing the workpiece. A beam having a predetermined intensity distribution is obtained, and the shape and size of the altered region that becomes a through hole or groove formed in the thickness (depth) direction of the workpiece can be changed by the intensity distribution of the beam. It becomes possible. In other words, the first embodiment according to the present invention shapes the laser beam 2 using the diffractive optical element 1 having such a phase distribution, and has a predetermined intensity distribution for processing the workpiece ( (Non-diffracted beam) is formed on and near the optical axis X, and the beam having this intensity distribution, particularly the beam of the intensity distribution portion of a predetermined level or higher, is positioned in a desired region as a degenerated region formed on the workpiece. Thus, the entire desired area is processed by the beam.
[0019]
Further, in FIG. 1, reference numeral 3 denotes a workpiece made of a transparent material through which a laser beam such as quartz is transmitted, and is formed with a through hole or a groove, and is placed on a table (not shown) and processed. Note that the table does not move in the vertical direction or the like, and the workpiece 3 placed during processing has a beam of a predetermined intensity distribution whose desired region is formed on and near the optical axis X (above a predetermined level). The position corresponding to the intensity distribution portion beam) is fixed. Although not shown, the laser processing apparatus includes a total reflection mirror that reflects the laser beam 2 from the laser oscillator toward the workpiece 3 and a beam expander that widens the laser beam 2 totally reflected by the total reflection mirror. Is provided between the laser oscillator and the diffractive optical element 1.
[0020]
When forming the altered region 5 for forming a through hole in the workpiece 3 using the laser processing apparatus according to the first embodiment configured as described above, first, the workpiece to be irradiated with the laser beam 2 is formed. 3 so as to correspond to a beam having a predetermined intensity distribution formed on and near the optical axis X (a beam of an intensity distribution portion of a predetermined level or higher). The object 3 is fixed to the table. Next, when the laser oscillator is driven, the laser beam 2 is oscillated and reflected by the total reflection mirror, is broadened by the beam expander, and enters the diffractive optical element 1. At this time, the optical axis X of the laser beam 2 incident on the diffractive optical element 1 substantially coincides with the center of the diffractive optical element 1. The laser beam 2 incident on the diffractive optical element 1 is phase-modulated by a concentric pattern formed on the surface of the diffractive optical element 1 and having the same period p, and has a predetermined intensity distribution for processing the workpiece 3. The beam (non-diffracted beam) is formed on the optical axis X and in the vicinity thereof, and the desired region 4 of the workpiece 3 is irradiated with the beam of the intensity distribution portion above the predetermined level.
[0021]
The phase distribution φ (r) of the diffractive optical element 1 that generates a beam (non-diffracted beam) having a predetermined intensity distribution for processing the workpiece 3 is given by the following equation (1).
φ (r) = mod [2 mπr / p] (1)
Here, m is the diffraction order of the diffractive optical element 1, r is the radius of the diffractive optical element 1, λ is the laser wavelength, p is the period of the diffractive optical element 1, and the function mod [] folds the phase distribution by 2π. The intensity distribution I (z) on the optical axis X of the non-diffracted beam obtained from this phase distribution can be calculated by the following equation (2).
I (z) = C1zexp (-C2z2);
C1= 2πI0sin2θ, C2= (2sin2θ / a2) ... (2)
However, the intensity distribution of the incident beam is a Gaussian distribution, and I (r) = I0exp (-2r2/ A2) And its radius (1 / e2A). Further, sin θ = mλ / p, which means beam shaping on the optical axis X using mth-order diffracted waves.
From the formula (2), the position Z at which the intensity on the optical axis X is maximum is obtained.cIs obtained by differentiating the equation as shown in the following equation (3).
Zc= (A / 2) (p / λ) (1 / m) (3)
From this relationship, the distance in the optical axis X direction of the intensity distribution (distance (depth) from the intensity distribution intensity 0 to the maximum intensity intensity 0 again) and a predetermined level of intensity distribution according to the processing content, For example, in order to change the depth of the intensity distribution portion of 90% or more of the maximum intensity, (A) the period p of the diffractive optical element 1 is changed, or (B) the diffraction order m is selected. From the expression (3), the position Z at which the intensity on the optical axis X is maximum is obtained.cThe beam intensity at is obtained as follows.
I (Zc) = (ΠaI0/ Exp (1/2)) · m (λ / p) (4)
From equation (4), it can be seen that the beam intensity on the optical axis X increases as the period p of the diffractive optical element 1 is shortened. In addition, when beam shaping is performed using a higher-order (m> 1) diffracted wave, the diffraction order m is increased, so that the beam intensity on the optical axis X is increased. The width W orthogonal to the optical axis X of the non-diffracted beam is given by the following equation.
W = ~ p (5)
[0022]
A calculation example of the beam intensity distribution I (z) obtained from these relationships is shown in FIG. In the calculation, it is assumed that the first order (m = 1) diffraction wave is used as the diffraction order m, and the laser wavelength λ = 0.80 μm and the incident beam radius a = 3.0 mm.
FIG. 4A shows the case where the period p of the diffractive optical element 1 is 20.0 mm, and the position Z at which the intensity on the optical axis X is maximum is 37.5 mm. The depth of is 24 mm. Here, the predetermined level or more is defined as 90% or more of the maximum intensity. FIG. 4B shows the case where the period p of the diffractive optical element 1 is 10.0 mm, and the position Z at which the intensity on the optical axis X is maximum is 18.8 mm. The depth of is 12 mm. Further, FIG. 4 (c) shows the case where the period p of the diffractive optical element 1 is 5.0 mm, and the position Z at which the intensity on the optical axis X is maximum is 9.4 mm, and the intensity distribution portion above a predetermined level. The depth of is 6 mm.
[0023]
In a laser processing apparatus in which a beam having such a predetermined intensity distribution is formed, as shown in FIG. 1, a predetermined region 4 that is a denatured region 5 in which a through hole of the workpiece 3 is formed has a predetermined region. When a beam having an intensity distribution (a beam of an intensity distribution portion above a predetermined level) is irradiated, the beam is spread over the entire desired region 4 (depth to several mm to several tens mm, width to several μm to several tens μm). Irradiated, the altered region 5 is formed by changing the physical properties of the desired region 4 through a multiphoton absorption process.
After the laser processing, as shown in FIG. 3, the workpiece 3 on which the altered region 5 is formed is immersed in an etching solvent such as HF (-10% aqueous solution), and the altered region 5 is removed by solvent etching. The through hole 6 is formed.
[0024]
In this way, the diffractive optical element 1 capable of applying phase modulation to the laser beam wavefront is provided, and a beam having a predetermined intensity distribution is formed on the optical axis X and in the vicinity thereof by the diffractive optical element 1, and the workpiece 3 The desired region 4 is fixed so as to correspond to the beam of the intensity distribution portion of the predetermined level or more, and the entire region of the desired region 4 is processed by this beam. Without moving the beam irradiation point, the altered region 5 that becomes the through hole 6 formed in the thickness (depth) direction of the workpiece 3 can be formed in a short time. Further, by repeating such processing, a plurality of altered regions 5 can be formed in various forms on one workpiece 3. Furthermore, the shape and size of the altered region 5 formed on the workpiece 3 can be easily changed by changing the beam intensity distribution shape formed on or near the optical axis X or certain beam irradiation conditions (intensity, time). Can be changed to Further, when forming the groove, the workpiece 3 so that the end portion on the deepest side of the beam of the intensity distribution portion of a predetermined level or higher is positioned at the portion of the maximum depth of the groove formed in the workpiece 3. Is fixed to the table and irradiated with the beam, so that a groove having a desired size (depth) can be formed. Thereby, the through-hole 6 or a groove | channel can be formed in a short time, and the laser processing method and its processing apparatus which can suppress a high cost and can improve processing efficiency can be obtained.
[0025]
Embodiment 2. FIG.
FIG. 5 is a configuration explanatory diagram of a main part of the laser processing apparatus according to the second embodiment of the present invention. In the second embodiment, a transparent material such as quartz is used instead of the diffractive optical element 1 according to the first embodiment. Unlike the diffractive optical element 1 according to the first embodiment, the periods p are not formed at regular intervals, and the laser from the laser oscillator is used. The beam 2 is diffracted by using the diffractive optical element 7 to form a beam having a substantially rectangular intensity distribution that concentrates and localizes light energy only in a predetermined region on the optical axis X, and its intensity. An altered region 5 in which the beam of the distribution portion is made to correspond to the desired region 4 where the through hole 6 of the workpiece 3 is formed, and the entire desired region 4 is processed by the beam to become the through hole 6 (desired region 4). Is formed.
[0026]
When the altered region 5 for forming the through hole 6 is formed in the workpiece 3 using the laser processing apparatus according to the second embodiment configured as described above, first, the workpiece to be irradiated with the laser beam 2 is formed. The workpiece 3 is fixed to the table so that the desired region 4 that becomes the altered region 5 of the object 3 corresponds to a beam having a substantially rectangular intensity distribution in a predetermined region formed on the optical axis X. Next, when the laser oscillator is driven, the laser beam 2 is oscillated, reflected by the total reflection mirror, enlarged by the beam expander, and incident on the diffractive optical element 7. At this time, the optical axis X of the laser beam 2 incident on the diffractive optical element 7 substantially coincides with the center of the diffractive optical element 1. Then, the laser beam 2 incident on the diffractive optical element 7 is phase-modulated by the unevenness formed on the surface of the diffractive optical element 7, and a beam having a substantially rectangular intensity distribution for processing the workpiece 3 is obtained. The desired region 4 of the workpiece 3 is irradiated with a beam of a substantially rectangular intensity distribution portion formed in a predetermined region on the optical axis X.
[0027]
The phase distribution φ (r) of the diffractive optical element 7 that generates a beam having a substantially rectangular intensity distribution that concentrates and localizes light energy in a predetermined region on the optical axis X is expressed by the following equation (6). Given in.
φ (r) = (2π / λ) ∫ (r / z (r)) dr (6)
However, the integration interval is 0 to r. Here, z (r) is the position of the point where the beam emitted from the diffractive optical element 7 intersects the optical axis X, and the position z (r) is obtained by the following equation (7).
z (r) = za+ (Zb-Za) (∫i (r) rdr) / (∫i (r) rdr) (7)
However, the integration interval (numerator) is 0 to r, the integration interval (denominator) is 0 to R, za, ZbIs the position of both ends of the beam intensity distribution (measured with reference to the surface of the diffractive optical element 7), i (r) is the intensity distribution of the incident beam, and R is the maximum radius of the incident beam.
Then, using the phase distribution φ (r) of the diffractive optical element 7 obtained from the equations (6) and (7), the beam intensity distribution I (z) on the optical axis X is expressed by the following equation (8) using Fresnel's integral formula. ).
[0028]
[Expression 1]
[0029]
A calculation example of the beam intensity distribution I (z) based on the equation (8) is shown in FIG. In the calculation, the incident beam has a Gaussian distribution and its radius a = 3.0 mm. In addition, the center value of a predetermined region on the optical axis X where the beam intensity distribution I (z) is formed is 50 mm here.
And Fig.6 (a) is za40.0 mm, zbIs 60.0 mm, the depth of the intensity distribution portion on the optical axis X in the predetermined region is 20 mm. When calculated using these, the beam intensity distribution I (z) as shown in FIG. can get. In addition, FIG.a45.0 mm, zbIs 55.0 mm, the depth of the intensity distribution portion on the optical axis X in the predetermined region is 10 mm. When calculated using these, the beam intensity distribution I (z) as shown in FIG. can get. In addition, FIG.a47.5mm, zbIs 52.5 mm, the depth of the intensity distribution portion on the optical axis X in the predetermined region is 5 mm. When calculated using these, the beam intensity distribution I (z) as shown in FIG. can get.
Then, each diffractive optical element 7 having a phase distribution from which each beam intensity distribution I (z) is obtained is formed, and has an intensity distribution that condenses and localizes light energy only in a predetermined region on the optical axis X. Generate a beam.
[0030]
In a laser processing apparatus in which a beam having a substantially rectangular intensity distribution for concentrating light energy only in a predetermined region on the optical axis X is formed, as shown in FIG. When the desired region 4 which is the altered region 5 in which the through hole 6 of the object 3 is formed is irradiated with a beam having a substantially rectangular intensity distribution that concentrates and localizes light energy only in a predetermined region, the beam Is irradiated on the entire region of the desired region 4 (depth to several mm to several tens mm, width to several μm to several tens μm), and the altered region 5 is formed by changing the physical properties of the desired region 4 through a multiphoton absorption process. To do.
After the laser processing, the workpiece 3 in which the altered region 5 is formed is immersed in an etching solvent such as HF (-10% aqueous solution), and the altered region 5 is removed by solvent etching, thereby forming the through hole 6. .
[0031]
As described above, the diffractive optical element 7 capable of applying phase modulation to the laser beam wavefront is provided, and the diffractive optical element 7 collects and localizes the light energy only in a predetermined region on the optical axis X so as to have a substantially rectangular intensity. A beam having a distribution is formed, and the desired region 4 of the workpiece 3 is fixed so as to correspond to a beam having a substantially rectangular intensity distribution only in a predetermined region. Since the machining is performed, the altered region 5 that becomes the through hole 6 formed in the thickness (depth) direction in the workpiece 3 without moving the workpiece 3 or the beam irradiation point by the mechanical movable means. Can be formed in a short time. Further, by changing the shape of the beam intensity distribution formed in the predetermined region on the optical axis X, the shape and size of the altered region 5 formed on the workpiece 3 can be easily changed. Furthermore, when forming a groove, the end Z of the intensity distribution of the beambHowever, a desired size (depth) can be obtained by fixing the workpiece 3 to the table and irradiating the beam so that the beam is positioned at the maximum depth portion of the groove formed in the workpiece 3. Can be formed. Thereby, the through-hole 6 or a groove | channel can be formed in a short time, and the laser processing method and its processing apparatus which can suppress a high cost and can improve processing efficiency can be obtained.
[0032]
Embodiment 3 FIG.
FIG. 7 is an explanatory diagram of the configuration of the main part of the laser processing apparatus according to Embodiment 3 of the present invention. This Embodiment 3 replaces the diffractive optical element 7 according to Embodiment 2 with a plurality of diffractive optical elements. Is used to form a substantially rectangular beam intensity distribution that concentrates and localizes light energy only in a predetermined region on the optical axis X, and the through hole 6 of the workpiece 3 forms the beam of the intensity distribution portion. The entire region of the desired region 4 is processed by the beam so as to correspond to the desired region 4 to be formed, and the altered region 5 to be the through hole 6 (desired region 4) is formed. Then, a first diffractive optical element 8 that converts the beam intensity distribution of the laser beam 2 from the laser oscillator, and a second diffractive optical that corrects a change in the phase of the beam converted by the first diffractive optical element 8. An element 9 and a third diffractive optical element 10 for converging the beam intensity from the second diffractive optical element 9 into a ring-shaped intensity distribution and condensing the beam to irradiate the workpiece 3; The diffractive optical elements 8, 9, 10 are arranged in series on the optical axis X.
[0033]
When forming the altered region 5 for forming the through hole 6 in the workpiece 3 using the laser processing apparatus according to the third embodiment configured as described above, first, the workpiece to which the laser beam 2 is irradiated is formed. The workpiece 3 is fixed to the table so that the desired region 4 that becomes the altered region 5 of the object 3 corresponds to a beam having a substantially rectangular intensity distribution in a predetermined region formed on the optical axis X. Next, when the laser oscillator is driven, the laser beam 2 is oscillated and reflected by the total reflection mirror, is broadened by the beam expander, and enters the diffractive optical element 8. At this time, the intensity distribution of the laser beam 2 incident on the diffractive optical element 8 is made Gaussian and the phase distribution flat. Next, the laser beam 2 incident on the diffractive optical element 8 exchanges the beam intensity distribution to obtain a predetermined intensity distribution on the diffractive optical element 9. Since the phase distribution of the beam also changes due to the action of the diffractive optical element 8, the phase change is corrected by the diffractive optical element 9, and a plane wave beam having a ring-shaped intensity distribution is obtained on the diffractive optical element 10. Next, the plane wave beam having a ring-shaped intensity distribution is condensed by the diffractive optical element 10 to form a beam having a substantially rectangular intensity distribution in a predetermined region on the optical axis X. The workpiece 3 is irradiated with a substantially rectangular intensity distribution beam.
[0034]
In such a laser processing apparatus in which a beam having a substantially rectangular intensity distribution is formed in a predetermined region on the optical axis X, as shown in FIG. 7, an altered region in which a through hole of the workpiece 3 is formed. When a desired region 4 which is 5 is irradiated with a beam having a substantially rectangular intensity distribution only on a predetermined region, the beam is irradiated to the desired region 4 (depth to several mm to several tens of mm, width to several μm to several to several The altered region 5 is formed by changing the physical properties of the desired region 4 through a multiphoton absorption process.
After the laser processing, the workpiece 3 in which the altered region 5 is formed is immersed in an etching solvent such as HF (-10% aqueous solution), and the altered region 5 is removed by solvent etching, thereby forming the through hole 6. .
[0035]
As described above, the plurality of diffractive optical elements 8 to 10 are arranged in series on the optical axis X, and the optical energy is condensed only in a predetermined region on the optical axis X by the diffractive optical elements 8, 9, and 10. Forming a beam having a substantially rectangular intensity distribution to be localized, and fixing the desired region 4 of the workpiece 3 so as to correspond to a beam having a substantially rectangular intensity distribution only in a predetermined region, Since the entire region of the desired region 4 is processed by this beam, the workpiece 3 is formed in the thickness (depth) direction of the workpiece 3 without moving the workpiece 3 or the beam irradiation point by the mechanical moving means. The altered region 5 to be the through hole 6 can be formed in a short time. Further, by changing the shape of the beam intensity distribution formed on the optical axis X, the shape and size of the altered region 5 formed on the workpiece 3 can be easily changed. Further, when forming the groove, the workpiece 3 is fixed to the table so that the end located in the deep direction of the beam intensity distribution is located at the maximum depth of the groove formed in the workpiece 3. By irradiating the beam, a groove having a desired size (depth) can be formed. Thereby, the through-hole 6 or a groove | channel can be formed in a short time, and the laser processing method and its processing apparatus which can suppress a high cost and can improve processing efficiency can be obtained.
[0036]
In the above-described third embodiment, the case where the three diffractive optical elements 8, 9, and 10 are provided is shown. However, the action of the second diffractive optical element 9 and the action of the third diffractive optical element 10 are integrated. The same action may be obtained by one diffractive optical element. In this case, the same effect is obtained.
[0037]
In the first to third embodiments described above, various altered regions 5 having different shapes or sizes are formed by controlling the beam intensity distribution on the optical axis X by the diffractive optical elements 1, 7 to 10. However, the present invention is not limited to this, and any method that controls the beam intensity distribution on the optical axis X can be used as appropriate. Further, by moving the laser beam 2 or the workpiece 3 in a direction orthogonal to the optical axis X, it is possible to form through grooves having various shapes.
[Brief description of the drawings]
FIG. 1 is a configuration explanatory diagram of a main part of a laser processing apparatus according to a first embodiment.
2 is a plan view of a diffractive optical element according to the laser processing apparatus of FIG. 1. FIG.
FIG. 3 is an operation explanatory diagram of the first embodiment.
FIG. 4 is a diagram showing a calculation example of a beam intensity distribution according to the first embodiment.
FIG. 5 is a configuration explanatory diagram of a main part of a laser processing apparatus according to a second embodiment.
FIG. 6 is a diagram showing a calculation example of a beam intensity distribution according to the second embodiment.
FIG. 7 is a configuration explanatory diagram of a main part of a laser processing apparatus according to a third embodiment.
[Explanation of symbols]
1, 7, 8, 9, 10 Diffractive optical element, 2 laser beam, 3 workpiece, 4 desired area, 5 altered area, 6 through-hole.

Claims (8)

  1. A laser beam which is an ultrashort pulse laser beam is shaped through a diffractive optical element to generate a non-diffracted beam having a predetermined intensity distribution along the optical axis direction, and the intensity distribution of the non-diffracted beam above a predetermined level. A laser processing method , comprising: irradiating a partial beam corresponding to at least a desired region in a thickness direction of a transparent workpiece, and processing the entire region of the desired region with the beam .
  2. A laser beam, which is an ultrashort pulse laser beam, is shaped through a diffractive optical element to form a beam having an intensity distribution in which light energy is condensed and localized in a predetermined region along the optical axis direction, and the intensity distribution A laser processing method, comprising: irradiating a partial beam corresponding to at least a desired region in a thickness direction of a transparent workpiece, and processing the entire region of the desired region with the beam.
  3. A plurality of diffractive optical elements are arranged in series on the optical axis, a laser beam that is an ultrashort pulse laser beam is shaped through the plurality of diffractive optical elements, and light energy is collected in a predetermined region along the optical axis direction. Forming a light beam having a localized intensity distribution, irradiating the beam of the intensity distribution portion in correspondence with at least a desired region in the thickness direction of the transparent workpiece, A laser processing method characterized by processing with a beam .
  4. The laser processing method according to any one of claims 1 to 3, wherein the desired region of the workpiece is a region where a hole or a groove is formed .
  5. A laser oscillator that oscillates an ultrashort pulse laser beam, and a diffractive optical element that shapes the ultrashort pulse laser beam emitted from the laser oscillator,
    A laser processing apparatus for processing a transparent workpiece, wherein the diffractive optical element generates a non-diffracted beam having a predetermined intensity distribution along an optical axis direction.
  6. A laser oscillator that oscillates an ultrashort pulse laser beam, and a diffractive optical element that shapes the ultrashort pulse laser beam emitted from the laser oscillator,
    The diffractive optical element generates a beam having an intensity distribution in which light energy is condensed and localized in a predetermined region along the optical axis direction, and laser for processing a transparent workpiece Processing equipment.
  7. A laser oscillator that oscillates an ultrashort pulse laser beam, and a plurality of diffractive optical elements arranged in series on an optical axis that shapes the ultrashort pulse laser beam emitted from the laser oscillator,
    A transparent workpiece characterized in that, by combining the plurality of diffractive optical elements, a beam having an intensity distribution in which light energy is condensed and localized in a predetermined region along the optical axis direction is generated. laser processing apparatus for processing a.
  8. Using the laser processing apparatus according to any one of claims 5 to 7, a beam for processing a transparent workpiece is irradiated to the entire desired region in the thickness direction of the workpiece to change the physical properties. The hole-drilling method is characterized in that a hole or a groove is formed by removing the altered region by solvent etching.
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JP5702556B2 (en) 2010-07-26 2015-04-15 浜松ホトニクス株式会社 Laser processing method
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JP5693074B2 (en) 2010-07-26 2015-04-01 浜松ホトニクス株式会社 Laser processing method
US9108269B2 (en) 2010-07-26 2015-08-18 Hamamatsu Photonics K. K. Method for manufacturing light-absorbing substrate and method for manufacturing mold for making same
WO2012014722A1 (en) 2010-07-26 2012-02-02 浜松ホトニクス株式会社 Substrate processing method
JP5389264B2 (en) 2010-07-26 2014-01-15 浜松ホトニクス株式会社 Laser processing method
JP5574866B2 (en) 2010-07-26 2014-08-20 浜松ホトニクス株式会社 Laser processing method
EP2599576B1 (en) 2010-07-26 2019-12-11 Hamamatsu Photonics K.K. Laser processing method
JP5554838B2 (en) 2010-07-26 2014-07-23 浜松ホトニクス株式会社 Laser processing method
JP5653110B2 (en) 2010-07-26 2015-01-14 浜松ホトニクス株式会社 Chip manufacturing method
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FR2989294A1 (en) 2012-04-13 2013-10-18 Centre Nat Rech Scient Device and method for laser nano-machining
JP2013251456A (en) * 2012-06-01 2013-12-12 Denso Corp Semiconductor device manufacturing method and semiconductor device
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JP6355194B2 (en) * 2014-05-30 2018-07-11 国立研究開発法人理化学研究所 Removal processing apparatus and method for semiconductor substrate

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