JPH10286683A - Excimer laser machining equipment and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an excimer laser machining equipment and method with a mask imaging method. SOLUTION: An excimer laser machining equipment is provided with are attenuator 7 capable of stepless or step-wise regulation of attenuation of excimer laser beam 6, an energy meter 11 for the excimer laser beam passing through the attenuator, a mask 3 and a lens 4. A machining object its irradiated with the excimer laser beam of a prescribed energy amount by controlling the attenuator 7 corresponding to the relative position of the mask 3, the lens 4 and the machining object 5. Further, by moving against at least two optical axes among the mask, the lens and the machining object while the image formation state of the mask pattern image is kept, the pattern reduction ratio is changed step by step or in stepless, and by keeping the energy density of the excimer laser beam in constant, the machining object is irradiated with the excimer laser beam having the most suitable energy for machining, and a hole whose diameter is changed in the depth direction and a groove whose width is changed, etc., are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an excimer laser processing apparatus and a processing method thereof.

[0002]

2. Description of the Related Art An excimer laser is oscillated by electric discharge in a mixed gas of a rare gas such as Ar, Kr or Xe and a halogen gas such as F and Cl at a fixed ratio. It is a high-output pulse laser having an oscillation wavelength, and many industrial applications such as microfabrication related to semiconductors and electronic components are put to practical use by utilizing this feature. As an application example, there is an application to fine processing of a polymer material such as fine opening of an orifice plate of an ink jet recording head and processing of through holes and via holes of a flexible printed circuit board. Polyimide excimer laser, polysulfone, polycarbonate, processing of polymeric materials such as polyethylene terephthalate differs from other industrial laser, for example, CO ₂ laser, a thermal melting process by YAG laser,
Since this is an ablation process called a photochemical reaction, the influence of heat is extremely small, so that high-quality processing is possible.

[0003] A mask imaging method and a contact mask method are known for such drilling with an excimer laser. Among them, the mask imaging method uses an excimer laser beam from an excimer laser oscillator 1 as shown in FIG. 6 is reflected by a reflection mirror 2 which is an optical system, and is then irradiated on the mask 3, and the excimer laser beam 6 that has passed through the shape (mask pattern) of the opening 3 a of the mask 3 is enlarged or reduced by the lens 4 for processing. This is a method of irradiating the object 5 by projecting it on an enlarged or reduced scale. In the contact mask method, as shown in FIG. 8, an excimer laser beam 6 from an excimer laser oscillator 1 is reflected by a reflecting mirror 2 and then enlarged or reduced by a lens 4 to irradiate the mask 3 to open the mask 3. In this method, a hole is drilled in the workpiece 5 by the excimer laser beam 6 that has passed through the portion 3a.

In the mask imaging method shown in FIG. 7 among the above-described double-drilling processing methods, basically, a mask pattern is imaged on the surface of a processing object 5 by a lens 4. The following relational expression (1) is established from the pattern reduction ratio (M), the energy density of the excimer laser beam at the image forming position (Ew), and the energy density of the excimer laser beam on the mask 3 surface (Em). .

Ew = M ² Em (1) Here, a separation distance (a) between the mask 3 and the lens 4,
The following relational expressions (2) and (3) are established from the separation distance (b) between the lens 4 and the surface of the processing target 5 which is the image forming position, and the focal length (f) of the lens 4.

M = a / b (2) 1 / a + 1 / b = 1 / f (3) The energy density (Ew) at the image forming position has an optimum value for processing depending on various materials. Therefore, in order to perform high-quality drilling, it is necessary to find the energy density (Ew) at the imaging position in advance.

[0007]

Most of the processing examples using the excimer laser are drilling and grooving. For this, a mask 3 having a round or square mask pattern is used. For example, in the case of drilling, in order to perform processing by changing the hole diameter on the processing target 5, as is apparent from FIG. 7 or FIG. It is necessary to change the reduction ratio (M) of the mask pattern.

Therefore, in the case where a pattern having a different mask pattern diameter is punched by using the mask 3, a large number of masks 3 may be prepared.
Since a mask for an excimer laser is generally used, a metal mask formed by processing a metal plate or a glass mask in which a pattern is formed on a glass substrate that passes the excimer laser beam with a thin film material that reflects the excimer laser beam is used. As such, each mask will take a considerable number of days to elaborate it,
Also, the fabrication is quite expensive.

On the other hand, when the size of the pattern for drilling is changed by changing the reduction ratio (M) of the mask pattern, as is apparent from the above-mentioned equation (1), the connection of the mask pattern is changed. The energy density (Ew) of the excimer laser beam at the image position also changes, and it is not always possible to obtain the optimum processing energy for the processing target. For example, when the pattern image is narrowed down by increasing the reduction ratio (M), the energy of the excimer laser beam applied to the processing target 5 increases, and when the processing target 5 is a polymer material, The appearance of thermal processing such as sagging on the processing end surface began to appear,
The processing quality decreases.

When a large number of holes having different pattern diameters are to be formed in one processing object 5, a mask 3 corresponding to the diameter of the hole to be processed is required. Complicated work is required for positioning the beam 6 and the like.

[0011] Excimer laser processing has the above-mentioned problems. As a technique for solving these problems, Japanese Patent Application Laid-Open No. Hei 7-185847 has been proposed. Although the excimer laser beam can be narrowed to an arbitrary size using a variable slit to narrow the beam size to an arbitrary size, the disadvantage is that the beam shape of the excimer laser beam is limited to only a rectangular shape. have.

On the other hand, when the boring process is performed by irradiating an excimer laser beam, the size of the excimer laser beam emitting surface of the object 5 to be processed becomes smaller than the size of the excimer laser beam emitting surface of the object 5. As a result,
It is known that the cross section inside the hole is naturally tapered. [OPTRONICS (1994) No. 7,
pp. 141-147). The fact that such a tapered processing is performed by the inventors of the present invention suggests that, when a hole is formed in a processing target made of a polyimide material, which is one of the polymer materials, the excimer irradiated onto the processing target is pierced. Depending on the energy density of the laser beam, a taper angle of 6 to 8 degrees is naturally formed in the processing cross section, and the naturally formed taper angle depends on the material to be processed and the energy density of the laser to be irradiated. It is confirmed until it is fixed.

[0013] However, in the drilling of the workpiece 5 made of a polymer material, for example, the cross section inside the hole is one.
It is considered difficult to form a hole having a large taper angle of 0 ° or more, and a technique for solving such a problem is disclosed in JP-A-7-284975 and JP-A-8-284975.
No. 25066. However, in the case of JP-A-7-284975,
There is a problem that a plurality of laser irradiations are required for one drilling, and it is difficult to control an excimer laser beam. In the case of Japanese Patent Application Laid-Open No. 8-25066, a prism and a pinion are used to form a prism. To irradiate an excimer laser beam while vibrating
There is a problem that the device becomes complicated.

As a method of forming a groove in a processing target by excimer laser processing, a rectangular excimer laser beam 6 is irradiated onto a processing target 5 via a mask 3 and a lens 4 as shown in FIG. 3, a method of forming a groove having a rectangular cross section by scanning at least one of the excimer laser beam 6 and the workpiece 5 at a constant speed is generally used. However, in the method of scanning a fixed pattern, it is impossible to form a groove having a constant width even if a groove having a constant width can be formed.

Accordingly, an object of the present invention is to perform drilling of an arbitrary size without exchanging a laser processing mask and by irradiating an object to be processed with an excimer laser beam having an optimum energy density for processing. To provide an excimer laser processing device capable of performing high quality,
By changing the reduction ratio of the mask pattern stepwise or steplessly while irradiating the excimer laser on the processing target, like a hole having a large tapered cross section, a groove whose width changes, An object of the present invention is to provide a processing method of a shape that has been difficult to process by a conventional processing method.

[0016]

According to the first aspect of the present invention, an excimer laser beam emitted from an excimer laser oscillator is attenuated to a predetermined energy amount by an attenuator, and then shielded by a mask having a mask pattern of a predetermined shape. In an excimer laser processing apparatus that performs reduced projection on a processing object through a lens while performing removal processing of a shape similar to a mask pattern shape, the size of the mask pattern,
The relative positions of the mask, the lens and the object to be processed are automatically determined from predetermined parameters such as the focal length of the lens, the pattern reduction ratio or the size of the pattern reduced and projected on the object to be processed, and the position is determined in accordance with the relative position. By controlling the attenuator to irradiate an object to be processed with an excimer laser beam having an optimum energy amount for processing, the above-mentioned problem is solved.

According to a second aspect of the present invention, there is provided an attenuator capable of adjusting a stepwise or stepless attenuation of an excimer laser beam in an excimer laser beam path between a laser emission port of a laser oscillator and a mask, and the attenuator comprising: Measuring means for measuring the energy of the passed excimer laser beam, moving means for moving at least two of a mask, a lens and an object to be processed in parallel with the optical axis, and imaging of the mask, lens and mask pattern Detecting means for detecting the relative position of the surface, the attenuator,
Control means for controlling a measuring means, a moving means and a detecting means, the control means comprising: a size of the mask pattern, a focal length of a lens, a required reduction ratio of the mask pattern or a reduced projection onto a processing object. Obtain predetermined parameters such as the size of the mask pattern obtained, determine the relative positions of the mask, the lens and the object to be processed based on the parameters, control the attenuator according to the relative positions, and optimize the processing. The object described above is solved as a laser processing apparatus according to claim 1, wherein an excimer laser beam having a large amount of energy is applied to a processing object.

According to a third aspect of the present invention, in the excimer laser processing by the mask imaging method, the object to be processed is irradiated with a laser, and while the processing is in progress, the mask pattern image is maintained while the image formation state is maintained. By moving at least two of the lens and the processing object in parallel to the optical axis, the pattern reduction ratio is changed stepwise or steplessly, and the excimer laser beam irradiated on the processing object is changed. An excimer laser processing method is characterized in that a material to be processed is removed while the energy density is kept constant, thereby solving the above-mentioned problem.

According to the fourth aspect of the present invention, in the excimer laser processing by the mask imaging method, the mask pattern is reduced and projected on the object to be processed, and the shape of the laser emission surface becomes smaller with respect to the laser incidence surface. The above problem is solved as an excimer laser processing method according to claim 3, wherein the pattern is formed.

According to a fifth aspect of the present invention, in the excimer laser processing by the mask imaging method, the mask pattern is reduced and projected on the processing object, and at least one of the processing object, the excimer laser beam and the mask is scanned. By doing so, a groove having a variable width is formed, thereby solving the above-mentioned problem as an excimer laser processing method according to claim 3.

An excimer laser processing apparatus according to the present invention comprises:
As is clear from FIG. 1, by moving at least two of the mask, the lens, and the object to be processed in parallel with the optical axis, an arbitrary reduction ratio is set as long as the excimer laser beam path length can be sufficiently secured. can do. In other words, if only one mask is manufactured for one shape, it is possible to reduce and project the mask pattern on a processing target in an arbitrary size and to perform a drilling operation of an arbitrary size. However, if the relative positions of the mask, the lens, and the object to be processed are adjusted and an arbitrary reduction ratio is set, the energy density of the laser at the image forming position is equal to the value determined by the above-described relational expression (1). Therefore, the value is not always optimal for the object to be processed. Therefore, it is necessary to adjust the energy density of the excimer laser beam finally irradiated on the surface of the processing object by attenuating the energy of the beam irradiated on the mask surface by the attenuator to obtain an optimum value for the processing object. It becomes possible.

According to the laser processing apparatus of the present invention, at least two of the mask, the lens, and the object to be processed are moved while maintaining the image formation state of the mask pattern during the processing, so that the laser processing apparatus can perform stepwise processing. It is possible to change the size of the mask pattern in a targeted or stepless manner and to obtain the optimum laser energy for the object to be processed. The shape corresponding to the reduction ratio that changes during laser irradiation, for example, the cross section is tapered It is possible to easily form high-quality holes and grooves having variable widths.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an excimer laser processing apparatus and a processing method according to an embodiment of the present invention will be described in detail.

Embodiment 1 FIG. 1 is a diagram showing a configuration of an excimer laser processing apparatus according to Embodiment 1 of the present invention. The excimer laser processing apparatus includes an excimer laser oscillator 1, a reflection mirror 2 as an optical system, a mask 3 for shielding the excimer laser, and a lens 4 as a lens system. A beam splitter 8 as an optical system, first and second position detection / holding mechanisms 9 as position detection / holding means, a work stage 10,
It has an energy meter 11 as measuring means and a computer 12 as control means. In the excimer laser processing apparatus having the above configuration, the excimer laser oscillator 1 is configured to emit an excimer laser beam 6. The attenuator 7 is an excimer laser oscillator 1
Is configured to attenuate the excimer laser beam 6 emitted from the laser beam into a beam having a predetermined energy amount. The reflection mirror 2 is configured to reflect the excimer laser beam 6 attenuated by the attenuator 7 toward the processing target 5. The mask 3 has an opening 3a having a predetermined mask pattern. The excimer laser beam 6 reflected by the reflection mirror 2 is passed through the opening 3a having a shape corresponding to the predetermined mask pattern. Is configured to shield. The lens 4 is a mask 3
The excimer laser beam 6 passing through the work stage 1
It is configured to perform reduced projection on the processing object 5 on 0.

Each of the first and second position detecting / holding mechanisms 9 moves the mask 3 and the lens 4 in the direction of the optical axis of the excimer laser beam 6 between the reflecting mirror 2 and the object 5 in the direction of the arrow in the figure. A position detection signal indicating where the mask 3 and the lens 4 are located in the optical path of the excimer laser beam 6 is fed back to the computer 12, and the mask 3 is driven by a drive signal from the computer 12. And the lens 4 can be moved in parallel in the direction of the arrow in the figure.

The beam splitter 8 is inserted between the attenuator 7 and the mask 3, and the excimer laser beam 6
Is allowed to pass in the direction of the reflection mirror 2 while a part of the excimer laser beam 6 is made incident on the energy meter 11. The energy meter 11 is configured to measure the energy amount of the excimer laser beam from the beam splitter 8 and feed back the measurement signal to the computer 12. The computer 12 can output a control signal for controlling the amount of attenuation of the excimer laser beam 6 to the attenuator 7 in response to the input of the measurement signal from the energy meter 11, and output the control signal from the position detection / holding mechanism 9. A drive signal can be output to the position detection / holding mechanism 9 in response to the input of the position detection signal. The computer 12 determines the relative positions of the mask 3, the lens 4 and the workpiece 5 from the input of the position detection signal from the position detection / holding mechanism 9, and monitors the measurement signal from the energy meter 11 according to the relative position. By controlling the attenuator 7, an excimer laser beam having an optimum energy amount for processing can be applied to the processing target 7.

Using the laser processing apparatus according to the first embodiment having such a configuration, the work stage 10 is actually
A processing method for forming a hole in the upper processing target 5 will be described. Here, the opening 3a of the mask 3 has a circular shape with a diameter (φm), and the mask pattern corresponds to this. Then, a hole having a diameter (φw) corresponding to the mask pattern is formed in the processing target 5. In this case, assuming that the pattern reduction rate indicating how much the size of the processing pattern of the hole of the processing target 5 is reduced with respect to the size of the mask pattern of the mask 3 is M, the pattern reduction rate (M) The following relational expression (4) holds.

M = φm / φw (4) Therefore, the following relational expressions (5) and (6) are established by the relational expressions (1) to (4).

[0029] a = f (φm / φw + 1), b = f (φw / φm + 1) ... (5) Em = (φw 2 / φm 2) Ew ... (6) where the excimer laser Em is passing through the attenuator 7 The energy density Ew of the beam 6 is the image formation position, that is, the energy density of the excimer laser beam 6 at the workpiece 5.

Therefore, the computer 12 determines the mask 3 and the lens based on the predetermined mask pattern size, processing pattern size, focal length (f) of the lens 4 and energy density (Ew) required for processing. 4. The energy amounts (Em) of the excimer laser beam 6 passing through the respective positions (a) and (b) and the attenuator 7 can be calculated by the above-mentioned relational expressions (5) and (6). The computer 12 controls and outputs a drive signal to each of the first and second position detection / movement mechanisms 9 based on the calculated values to position the mask 3 and the lens 4 at predetermined positions, and About the energy of
Obtained from the measurement signal from the energy meter 11, the control signal is controlled and output so as to change the attenuation rate of the attenuator 7 so that the energy density of the excimer laser beam on the workpiece 5 becomes a predetermined energy density. .

Next, a general expression will be described below as to how the pattern reduction ratio (M) can be changed by using the laser processing apparatus according to the first embodiment. According to the present invention, there are the following four conditions that restrict the hole diameter, that is, the pattern reduction ratio (M).

(A) The size of the entire apparatus, that is, the optical path length of the excimer laser beam 6 (b) The focal length of the lens 4 (f) (c) The beam diameter of the excimer laser beam (d) The attenuation rate variable range of the attenuator 7 Among the constraint conditions (a) to (d), the one that determines the pattern reduction rate (M) is the variation range of the attenuation rate (η) of the attenuator 7. Theoretically, this attenuation rate (η) is 0 <η <1 (7), but is actually about 5 to 95%.

The energy density (Ew) of the excimer laser beam at the image forming position, the pattern reduction rate (M), the attenuation rate (η) of the excimer laser beam by the attenuator 7,
The following relational expression (8) holds for the energy density (Eo) of the excimer laser beam 6 immediately after being emitted from the laser oscillator 1.

Ew = M ² · η · Eo (8) Here, if α <η <β, in the first embodiment, the imaging position excimer laser beam energy density (Ew) is applied to the workpiece 5. Since the attenuation rate (η) is determined so as to be constant at a value corresponding thereto, the following relational expression (Equation) is used between the change area of the attenuation rate (η) and the change area of the pattern reduction rate (M). 9) is established.

(1 / β) · (Ew / Eo) <M ² <(1 / α) · (Eo / Ew) (9) Processing of polymer material by excimer laser based on the above relational expression The first embodiment will be described in further detail by taking the most typical processing of polyimide as an example.

When the object 5 to be processed is a polyimide material as the polymer material, the optimum energy density (Ew) of the excimer laser beam on the surface to be processed is determined to be 0.
It was confirmed to be 7 to 1.2 (J / cm ² ). The target processing shape is a round hole having a diameter of 100 (μm) or less, which is difficult to process by conventional machining. For example, in the case where a hole having a diameter of 50 (μm) is formed in the processing target 5, a metal mask 3 having a circular pattern with a diameter of 200 (μm) is prepared. The energy density (Ew) of the excimer laser beam on the processing surface is in the range of 0.7 to 1.
When 2 (J / cm ² ) is changed to 0.9 (J / cm ² ),
Assuming that the focal length (f) of the lens 4 to be used is 100 (mm), the energy density (Em) of the excimer laser beam 6 that has passed through the attenuator 7 is expressed by the relational expression (6).
Is 0.056 (J / cm ² ), and from the relational expression (5),
The distance (a) between the mask and the lens is 500 (mm), and the distance (b) between the lens and the imaging position (the surface of the processing target 5) is 12
5 (mm).

Eo = 0.1 J / cm ² , 0.05
If ≦ η ≦ 0.95, the pattern reduction ratio (M) is 3.08 <M <13.4 according to the above-mentioned relational expression (9), and a hole can be formed with one mask having a diameter of 200 (μm). The diameter of the hole will be 14.9 (μm) to 64.9 (μm). Although the hole shape is a circle here, a similar polygonal shape or a rhombus shape can be similarly processed for any shape.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. When the laser processing apparatus shown in FIG. 1 described above is used, the diameter of the workpiece 5 in the thickness direction is changed by changing the pattern reduction ratio (M) while maintaining the combined state of the mask patterns even during the processing. It is possible to machine a hole that becomes smaller, that is, a hole having a tapered cross section. In this case, assuming that the material thickness of the processing target 5 is sufficiently small with respect to the focal length (f) of the lens 4 and within a negligible range, the processing rate of the material by excimer laser processing is grasped in advance. This makes it possible to easily perform a high-quality tapered hole drilling process.

FIG. 2A shows the mask 3, the lens 4 and the object 5 to be processed. The mask 3 and the lens 4 are respectively moved by the first and second position detecting / holding mechanisms 9 in the direction of the arrow in the figure. Can be moved. Then, as shown in FIG. 2B, the workpiece 5 is made of polyimide which is a polymer material, the thickness of the material is T (mm), the processing rate of the material is r (mm / sec), and the excimer laser beam incident side. The hole diameter is φ1 (mm) and the hole diameter on the excimer laser beam emission side is φ
If 2 (mm) (φ1> φ2), the above relational expression
According to (5) and (8), the moving speed Vm of the mask 3 after t seconds.
(mm / sec), the moving speed VL (mm / sec) of the lens 4, and the changing speed Rη (/ sec) of the attenuation rate η of the attenuator 7 are expressed by the following relational expressions (10), (11) and (12). become. However, here, for simplification of description, the ratio of the change in the hole diameter is calculated as a constant. Further, among the mask 3, the lens 4, and the processing object 5, the processing object 5 is fixed,
The configuration is such that the lens 4 and the mask 3 are moved.

Vm = (φ1−φ2) · f · r / T · [φm · T ² / P ² −1 / φm] (10) where P = T · φ1−r · (φ1−φ2) · t VL = (φ2-φ1) · 1 / φm · f · r / T ... (11) Rη = 2 · Ew / Eo · (φ1-φ2) / φm 2 · r / T · [(φ1-φ2) · r / T · t-φ1] (12) Next, an actual processing example will be described based on the above relational expressions. For example, a polyimide material having a hole entrance diameter of 60
(Μm), and a hole having a diameter of 15 (μm) at the hole exit is formed. As in the first embodiment, the diameter of the mask pattern is 200 (μm), the energy density of the excimer laser beam on the processing surface is 0.9 (J / cm ² ), and the output energy density of the laser oscillator 1 is 0.1 (J / cm ² ). cm ² ), and the focal length (f) of the lens 4 to be used is 100 (mm). The material processing rate is 0.04 (mm) / sec, and the material thickness is 0.5 (mm). The above relational expressions (10) to (1)
According to 2), the moving speed (Vm) of the mask 3, the moving speed (VL) of the lens 4, and the rate of change (Rη) of the attenuation rate of the attenuator 7 are calculated as follows as a function of the elapsed time (t) from the start of processing. Asked to do so.

Vm = -0.018 / (0.03-0.0
018t) ² +1.8 (mm / sec) VL = 1.8 (mm / sec) Rη = 0.005832t−0.0972 FIG. 3A shows the moving speed (Vm) of the mask 3 and the lens 4 The results of calculations for the moving speed (VL) and the rate of change (Rη) of the attenuation rate of the attenuator 7 are shown in a table. Based on this chart, the value of each control parameter at the elapsed time t from the start of the processing can be calculated in advance by the computer 12, so that the computer 12 sets the mask 3 and the lens based on the calculated values. The position control 4 and the attenuation rate of the attenuator 7 may be controlled steplessly. Generally, as shown in FIG. 3B, it is general that the values of the parameters are assumed to be constant during the short time interval (Δt), and the calculation is performed stepwise. In this case, the smaller the value of Δt, the higher the accuracy of calculation.

According to the second embodiment, as apparent from the principle, φ1> φ2, that is, processing of a pattern in which the hole entrance size on the excimer laser beam incident side is larger than the hole exit size on the excimer laser beam emission side. It is only possible to do.

Third Embodiment A third embodiment according to the present invention will be described with reference to FIGS. The third embodiment is a case where a groove is formed in the processing target 5. FIG. 4A shows a mask 3 and a lens 4.
And a processing object 5, and a mask 3 and a lens 4 are respectively provided with first and second position detection / holding mechanisms 9.
Each can be moved in the direction of the arrow in the figure. FIG.
An opening 3a having a size of L × k is formed in the mask 3 of (a), and a mask pattern is determined by this. With this mask pattern, a groove processing in which the groove width is changed to L1 to L2 is performed on the processing target 5 shown in FIGS. The groove 5 in the third embodiment is processed using the excimer laser processing apparatus shown in FIG.
The groove processing that changes the width is performed.

Explained below, the excimer laser oscillator 1
The oscillation frequency of the excimer laser beam 6 is H (Hz), the scanning speed is v (mm / sec), the length of the processing pattern in the scanning direction is k (mm), and the processing rate is r (mm / sec). Assuming that the depth of the groove is h (mm), the following relational expression (13) is established in these relations.

H = k · r · H / v (13) In the case of processing grooves having a constant depth and different widths, the groove width is changed from L1 (mm) to L2 (mm) in order to simplify the description. Up to a constant rate (where L1> L2), the length of the groove j (mm), and the length of the mask pattern in the direction perpendicular to the k, L, the movement of the mask 3 from the above equation. Speed V
m (mm / sec), the moving speed V1 (mm / sec) of the lens 4, and the change speed Rη (/ sec) of the attenuation rate M of the attenuator 7 are as follows. However, among the mask 3, the lens 4, and the processing object 5, the processing object 5 is fixed, and the mask 3 and the lens 4 are fixed.
Move.

Vm = f · 1 / α · e · {L / [L1-L−e] ² −1 / L} (14) V1 = −f / 1 / L · 1 / α · e (15) ) Rη = 2 · Ew / Eo · 1 / L 2 · 1 / α · (e-L1 + L) · e ... (16) in this case, the scanning speed of the workpiece stage 10 (Vs) is as follows.

Vs = r · H / h · k / L · (L1−L−e) (17) where e = exp [(t + β) / α] α = r · H · k · j · 1 / (L2-L1) · 1 / h · 1
/ L β = α · log _e L In the third embodiment, similarly to the second embodiment, the mask 3 and the lens 4 are moved by substituting predetermined numerical values into the relational expressions (14) to (16). Speed, attenuation rate of the attenuator 7, scanning speed of the work stage 10 (Vs)
Is defined as a function of time (t) from the start of processing. FIG. 5A schematically shows the above calculation results in a table.

Similarly to the second embodiment, in the third embodiment, the values of the respective control parameters at the elapsed time t from the start of the processing are calculated by the computer 12 in advance based on the chart of FIG. Therefore, the positions of the mask 3 and the lens 4 and the attenuation factor M of the attenuator 7 may be controlled steplessly based on the calculated values. Generally, as shown in FIG. 5B, it is general that the calculation is performed in a stepwise manner on the assumption that the values of the respective parameters are constant during the minute time interval (Δt). In this case, the smaller the value of Δt, the higher the accuracy of calculation.

The technique described in Japanese Patent Application Laid-Open No. 8-88161 will be described with reference to FIG. FIG.
(A) is an excimer laser processing apparatus of the publication, and FIG.
(B) is an excimer laser processing apparatus according to an embodiment of the present invention. In the publication of FIG. 6A, a circular excimer laser beam 6 is output from an excimer laser oscillator 1, and the circular excimer laser beam 6 is
In the embodiment of the present invention shown in FIG. 6B, a rectangular excimer laser beam 6 is output from the excimer laser oscillator 1. After the rectangular excimer laser beam 6 is formed into a mask pattern by the mask 3, the object 5 is irradiated via the lens 4. Therefore, in the case of the publication, the beam diameter of the excimer laser beam 6 output from the excimer laser oscillator 1 is adjusted by the beam diameter variable means from the beam diameter detected before entering the lens 4, and the adjusted beam diameter is adjusted. However, in the embodiment of the present invention, the excimer laser beam 6 for irradiating the processing target 5 is a projected image of a mask pattern, and the size of the projected image is determined by the mask 3, lens 4, It is uniquely determined by the relative position of the processing object 5, and there is no beam diameter varying means as in the publication. That is,
In the case of this publication, it is necessary to adjust the excimer laser beam before it is incident on the lens 4 closest to the processing object 5, so that the beam size of the excimer laser beam must be controlled by the beam diameter varying means. On the other hand, in the present embodiment, the excimer laser beam is
Since there is no need to make adjustments before entering the lens 4 closest to the lens, such a beam diameter varying means is unnecessary, the beam size can be controlled by the projection magnification of the mask pattern, and the processing of the processing object 5 can be performed with high accuracy. Is supposed to be able to do it.

[0050]

As is apparent from the above description, according to the excimer laser processing apparatus of the present invention, the excimer laser beam emitted from the excimer laser oscillator is attenuated to a predetermined energy amount by the attenuator, and then the mask having the predetermined shape is formed. In an excimer laser processing apparatus that performs reduced projection on a processing object through a lens while shielding with a mask having a pattern, and performs removal processing similar to the mask pattern shape, the size of the mask pattern, the focal length of the lens, and the pattern reduction rate Or from a predetermined parameter such as the size of the pattern reduced and projected on the workpiece
Since the relative positions of the mask, the lens, and the object to be processed are automatically determined, and the attenuator is controlled in accordance with the relative position, an excimer laser beam having an optimal energy amount for processing is irradiated on the object to be processed. By moving at least two of the lens and the object to be processed in parallel with the optical axis, any reduction ratio can be set as long as the path length of the excimer laser beam can be sufficiently secured. If only one mask is made, the mask pattern is reduced and projected on the object to be processed in an arbitrary size, and further, the energy of the beam irradiated on the mask surface is attenuated by the attenuator, and finally processed. By adjusting the energy density of the excimer laser beam irradiated on the surface of the object, it can be adjusted to the optimum value for the processing object. Because, without having to replace the mask,
High quality processing can be performed. Further, according to the laser processing apparatus of the present invention, by moving at least two of the mask, the lens, and the object to be processed while maintaining the image formation state of the mask pattern during the processing, the laser processing apparatus can perform stepwise or non-stepping during the processing. It is possible to change the size of the mask pattern in stages and obtain the optimum laser energy for processing, and obtain the laser energy while changing the pattern reduction ratio while the material is being removed. It is possible to easily process a shape, for example, a hole having a tapered cross section, a groove having a variable width, or the like, which has been difficult to process, with high quality and high quality.

According to the excimer laser processing method of the present invention, in the excimer laser processing by the mask imaging method, the object to be processed is irradiated with laser, and while the processing is in progress, the image forming state of the mask pattern image is maintained. ,
By moving at least two of a mask, a lens, and an object to be processed in parallel to the optical axis, the pattern reduction ratio is changed stepwise or steplessly, and an excimer laser beam irradiated onto the object to be processed Since the material removal of the object to be processed is performed while keeping the energy density of the workpiece constant, for example, a pattern having a tapered cross section, a groove whose width changes, or the like is irradiated with an excimer laser beam, and the pattern is removed while the material is being removed. Processing of the shape obtained while changing the reduction ratio can be performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an excimer laser processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram for describing a laser processing method according to a second embodiment of the present invention;

FIG. 3 is a chart provided for explaining the processing method of FIG. 1;

FIG. 4 is a diagram for explaining a laser processing method according to a third embodiment of the present invention;

FIG. 5 is a chart for explaining the processing method of FIG. 4;

FIG. 6 is a diagram for explaining a difference between a conventional technique and an embodiment of the present invention.

FIG. 7 is a diagram provided for explanation of a mask imaging method in laser processing.

FIG. 8 is a diagram for explaining a contact mask method in laser processing;

FIG. 9 is a diagram for explaining a method of forming a groove in a workpiece by excimer laser processing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Excimer laser oscillator 2 Reflection mirror 3 Mask 4 Lens 5 Workpiece 6 Excimer laser beam 7 Attenuator 8 Beam splitter 9 Position detection / parallel movement mechanism 10 Work stage 11 Energy meter 12 Computer

Claims (5)

[Claims] An excimer laser beam emitted from an excimer laser oscillator is attenuated to a predetermined energy amount by an attenuator, and then reduced and projected onto a processing target object through a lens while being shielded by a mask having a mask pattern of a predetermined shape. In an excimer laser processing apparatus that performs removal processing of a shape similar to a shape, the size of the mask pattern, the focal length of the lens, the pattern reduction ratio, or a predetermined parameter such as the size of the pattern reduced and projected on the processing target is determined by using a predetermined parameter. Automatically determining the relative positions of a mask, a lens, and a processing target, and irradiating the processing target with an excimer laser beam having an optimal energy amount for processing by controlling the attenuator according to the relative position. Excimer laser processing equipment. 2. An attenuator capable of stepwise or steplessly attenuating an excimer laser beam in an excimer laser beam path between a laser emission port of a laser oscillator and a mask, and an energy of the excimer laser beam passing through the attenuator. Measuring means for measuring the distance, moving means for moving at least two of the mask, the lens and the object to be processed in parallel with the optical axis, and detecting the relative positions of the image forming surfaces of the mask, the lens and the mask pattern. Detecting means;
A control means for controlling the attenuator, the measuring means, the moving means and the detecting means, wherein the control means comprises: a size of the mask pattern, a focal length of a lens, a required reduction ratio of the mask pattern or an object to be processed. While obtaining a predetermined parameter such as the size of the mask pattern projected and reduced to the mask, based on the parameters, determine the relative position of the mask, lens and the workpiece, control the attenuator according to the relative position,
The excimer laser processing apparatus according to claim 1, wherein an excimer laser beam having an optimum energy amount for processing is irradiated on a processing target. 3. In excimer laser processing by a mask imaging method, an object to be processed is irradiated with a laser, and while the processing is in progress, an image of a mask, a lens, and an object to be processed is maintained while an image forming state of a mask pattern image is maintained. By moving at least two in parallel to the optical axis, the pattern reduction ratio is changed stepwise or steplessly, and
An excimer laser processing method characterized in that material removal of an object to be processed is performed while keeping the energy density of an excimer laser beam irradiated onto the object to be processed constant. 4. An excimer laser processing by a mask imaging method, wherein a mask pattern is reduced and projected on a processing object to form a tapered pattern in which a shape of a laser emission surface is reduced with respect to a laser incidence surface. The excimer laser processing method according to claim 3, wherein: 5. In an excimer laser processing by a mask imaging method, a width is changed by projecting a mask pattern on a processing target in a reduced size and scanning at least one of the processing target, an excimer laser beam and a mask. 4. The excimer laser processing method according to claim 3, wherein a groove is formed.