JP2001047270A - Device for laser beam machining and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for laser beam machining and a method therefor capable of executing excellent cutting working on all patterns of cutting objects to be worked. SOLUTION: The device is equipped with laser beam emitting means 41, 45 to emit a laser beam on a working point of an object to be worked 20 placed on a stage 11, energy setting means 42, 72 to set energy of the laser beam emitted on the working point at a prescribed energy value, and an energy converting means 70 which converts the energy set by energy setting means 42, 72 into the prescribed energy value according to positional information of the working point in a surface of the object to be worked 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing apparatus and a laser processing method for processing a surface of a workpiece in a non-contact manner by utilizing a high power density of a laser beam.
The present invention relates to a laser processing apparatus and a laser processing method used for cutting a fine wiring pattern in an integrated circuit.

[0002]

2. Description of the Related Art A laser processing apparatus is an apparatus for intentionally cutting a fine wiring pattern by irradiating a fine wiring pattern formed on the surface of a workpiece (for example, a wafer) with a laser beam. . Such a laser processing apparatus has been conventionally used for laser repair and laser trimming.

[0003] In such a laser processing apparatus, the energy value of a laser beam applied to a wiring pattern to be cut (hereinafter referred to as a "cutting pattern") on a workpiece (for example, a wafer) is determined by the type of the workpiece. Is set to a predetermined energy value in accordance with the cutting process. Further, the laser processing apparatus is provided with an objective lens for condensing the laser light set to the predetermined energy value, and an autofocus function for positioning the pattern to be cut on the workpiece at the focal position of the objective lens. Have been.

Therefore, in a laser processing apparatus, after a pattern to be cut on a workpiece is positioned at a focal position of an objective lens by an autofocus function, the pattern to be cut is irradiated with laser light to perform cutting. The offset value used when positioning the pattern to be cut is set to a predetermined offset value according to the type of the workpiece.

[0005]

However, in the above-mentioned conventional laser processing apparatus, good processing results cannot always be obtained for all of a plurality of patterns to be cut on a workpiece.

That is, cutting may not be performed reliably due to insufficient processing, or damage to the underlying film may occur due to excessive processing. As described above, for example, the size (width, length, or thickness) of the cutting target pattern is slightly different depending on the position of the cutting target pattern in the workpiece, as a cause of the variation in the sharpness of the cutting target pattern. It is conceivable that the thickness and lamination state of the thick transparent protective film covering the surface of the workpiece differ depending on the location of the workpiece.

An object of the present invention is to provide a laser processing apparatus and a laser processing method capable of performing good cutting on all patterns to be cut on a workpiece.

[0008]

According to a first aspect of the present invention, there is provided a laser processing apparatus, comprising: a stage on which a workpiece is mounted; and a laser irradiation for irradiating a laser beam to a processing point of the workpiece mounted on the stage. Means, an energy setting means for setting the energy of the laser beam applied to the processing point to a predetermined energy value, and the energy set by the energy setting means to the in-plane position information of the processing point in the workpiece. Energy changing means for changing the energy value to a predetermined energy value accordingly.

The invention described in claim 2 is the first invention.
In the laser processing apparatus described in the above, by measuring the position of the processing point in the optical axis direction of the laser light, by moving the stage in the optical axis direction based on the measurement result, positioning means for positioning the processing point, Offset setting means for setting an offset used for positioning the processing point to a predetermined offset value, and changing the offset set by the offset setting means to a predetermined offset value according to the in-plane position information of the processing point. And offset changing means.

According to a third aspect of the present invention, there is provided a laser processing apparatus, comprising: a stage on which a workpiece is mounted; a laser irradiating means for irradiating a processing point of the workpiece mounted on the stage with laser light; By measuring the position of the processing point in the optical axis direction of the light, and by moving the stage in the optical axis direction based on the measurement result, a positioning means for positioning the processing point, and an offset used for positioning the processing point Offset setting means for setting a predetermined offset value, and offset changing means for changing the offset set by the offset setting means to a predetermined offset value in accordance with the in-plane position information of the processing point in the workpiece. It is provided with.

The invention described in claim 4 is the first invention.
Alternatively, in the laser processing apparatus according to claim 2, the energy changing unit has an energy storage unit that stores the determined energy value of the processing point. According to a fifth aspect of the present invention, in the laser processing apparatus according to the second or third aspect, the offset changing unit has an offset storage unit that stores the determined offset value of the processing point. I have.

According to a sixth aspect of the present invention, in the laser processing apparatus according to the second, third or fifth aspect, the laser irradiation means has an objective optical system for condensing a laser beam. ing. Further, the offset changing means changes the offset so that the position of the processing point in the optical axis direction coincides with the focal position of the objective optical system. According to a seventh aspect of the present invention, in the laser processing apparatus according to the second, third, fifth, or sixth aspect, the positioning means is configured to process the workpiece from a direction inclined with respect to the optical axis direction. A measuring unit is provided for measuring the position of the processing point in the optical axis direction by making the beam incident on the object and detecting the beam reflected by the workpiece.

[0013] The invention described in claim 8 is the invention according to claim 7.
Wherein the offset setting means has a shift member for shifting the trajectory of the reflected beam when measuring the position by the measuring unit of the positioning means. The offset setting means sets an offset in accordance with the amount of orbit shift by the shift member.

According to a ninth aspect of the present invention, in the laser processing apparatus according to the first, second or fourth aspect, the laser irradiating means has a light source for emitting a laser beam. . The energy setting means has an attenuating member that attenuates the energy of the laser light emitted from the light source. The energy setting means sets the energy applied to the processing point in accordance with the amount of energy attenuation by the attenuation member.

According to a tenth aspect of the present invention, there is provided a laser processing method for irradiating a laser beam to a processing point of a workpiece mounted on a stage, and irradiating the processing point prior to the laser irradiation step. Energy setting step of setting the energy of the laser beam to be performed to a predetermined energy value, and prior to the energy setting step, the energy set in the energy setting step is converted into information on the in-plane position of the processing point within the workpiece. Energy changing step of changing the energy value to a predetermined energy value accordingly.

According to another aspect of the present invention, there is provided a laser processing method for irradiating a laser beam to a processing point of a workpiece mounted on a stage, and a position of the processing point in an optical axis direction of the laser light. Is measured, and by moving the stage in the optical axis direction based on the measurement result, a positioning step of positioning the processing point, and prior to the positioning step, an offset used for positioning the processing point is set to a predetermined offset value. An offset setting step to set, and an offset for changing an offset set in the offset setting step to a predetermined offset value according to in-plane position information of a processing point in a workpiece prior to the offset setting step. And a change step.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) First, a first embodiment will be described. The first embodiment is described in claim 1, claim 4, claim 9,
This corresponds to claim 10.

The laser processing apparatus 10 (FIG. 1) of the first embodiment uses a laser beam to
This is a device for processing the surface of a. In the first embodiment, particularly, a description will be given of an example in which a fine wiring pattern formed on the surface of the wafer 20 is cut. Incidentally, the fine wiring pattern described above is a wiring portion intended for laser beam cutting, and is usually called a "fuse".

Here, prior to the description of the laser processing apparatus 10 (FIG. 1), a wafer 20 to be processed and a fuse formed on the surface thereof will be described. As shown in FIG. 2A, a plurality of semiconductor chips 21, 21,... Are arranged on the surface of the wafer 20. Each semiconductor chip 2
Reference numeral 1 denotes a circuit on which a predetermined circuit (not shown) (for example, a memory circuit or a special circuit for image processing) is formed. The position of each semiconductor chip 21 in the wafer 20 is as follows:
In the order of arrangement 1, 2, ... along the column direction,
Are specified by the arrangement order 1, 2,... Along the row direction.

The surface of each semiconductor chip 21 is entirely covered with a thick protective film (not shown) for the purpose of protecting the above-mentioned predetermined circuit from oxygen and moisture in the air. Several μm to several tens μm). However, a predetermined portion (for example, a peripheral portion) of each semiconductor chip 21 is provided in FIG.
As shown in (c), a window 22a is formed by partially opening the thick protective film 22 described above. This window 22
The size w of a is about 40 μm to 45 μm. FIG. 2B is an enlarged plan view showing a part of the semiconductor chip 21. FIG. 2C is a sectional view taken along line AA of FIG.

Then, in the window portion 22a, FIG.
As shown in (c) and (d), a plurality (4 in FIG.
.) Are formed. The number of fuses 23 varies depending on the type of the semiconductor chip 21, and is not limited to four. FIG. 2 (d)
FIG. 3 is a sectional view taken along line BB of FIG.

These fuses 23, 23,...
For example, it is a switching element connected to a redundant circuit in the semiconductor chip 21. Each fuse 23 is made of polysilicon or aluminum (having a width of about 1 μm and a length of 8 μm).
m and a thickness of about 0.5 μm), which are formed at the same time when wiring is formed in a well-known wiring forming step. The insulating film 2 is provided between the fuse 23 and the wafer 20.
4 are formed. On the fuse 23, a thin protective film 25 is formed.

As described above, on the surface of the wafer 20, a plurality of fuses 23, 23,.
Are formed. The position of each fuse 23 in the wafer 20 is specified in advance as XY coordinates (in-plane position information) in the wafer 20 (see FIG. 2B). Now, the fuses 23 formed on the surface of the wafer 20 will be described.
Are cut by using the laser processing apparatus 10 (FIG. 1) of the first embodiment described below, and the laser beam of predetermined energy narrowed according to the width of the fuses 23 and the interval between the fuses 23 is cut. This is performed by irradiating the fuse 23 to be pulsed.

In the first embodiment, the energy value of the laser beam applied to the fuse 23 to be cut is changed for each semiconductor chip 21 so that the number of fuses 23 formed on the surface of the wafer 20 are changed. On the other hand, cutting processing is performed by irradiating a laser beam having substantially the same energy value. Now, the laser processing apparatus 10 according to the first embodiment will be described.
The overall configuration of FIG. 1 will be described.

As shown in FIG. 1, the laser processing apparatus 10 has a Z stage 11 on which a wafer 20 having the above-mentioned fuses 23, 23,.
Z actuator 12 for driving stage 11 in the Z direction
An XY stage 13 supporting the Z stage 11, and X
An XY actuator 14 for driving the Y stage 13 in the XY directions is provided.

An XY position monitor 16 for measuring the position of the XY stage 13, that is, the XY position of the wafer 20, is provided on the XY stage 13. As the XY position monitor 16, for example, linear encoders provided in the X direction and the Y direction are used. Further, the laser processing apparatus 10 has a surface (fuse 23) of the wafer 20.
An irradiation system 40 for irradiating the laser light for processing and an objective lens 45 for condensing the laser light for processing are provided.

Here, the irradiation system 40 includes a processing laser 41 for emitting the laser beam L1, and an attenuator 42 for attenuating the energy of the laser beam L1 emitted from the processing laser 41.
An optical system 43 that adjusts the beam size of the laser light L2 that has passed through the attenuator 42, and a beam splitter 44 that guides the laser light L3 that has passed through the optical system 43 to the wafer 20 along the optical axis of the objective lens 45. It is composed of

The processing laser 41 includes, for example, N
d: A YLF laser (oscillation wavelength 1047 nm) or the like is used. The emission timing of the laser beam L1 from the processing laser 41 is determined externally (a stage controller 71 described later).
Is controlled by a trigger signal (a signal for emitting a laser beam), and pulse oscillation is performed according to the trigger signal.

As the attenuator 42, a polarizing plate that optically attenuates energy by using the polarization state of the laser light L1 is used. An actuator (rotating the attenuator 42 with respect to the polarization plane of the laser light L1) is used. (Not shown) and the attenuator 42
And an encoder (not shown) for measuring the rotation angle φ. The optical system 43 includes a beam expander that enlarges the cross-sectional shape of the laser beam L2 from the attenuator 42, and a variable aperture that shapes the cross-sectional shape.

In such an irradiation system 40, the laser beam L3 emitted from the processing laser 41 and having passed through the attenuator 42 and the optical system 43 is reflected by the beam splitter 44 and then passes through the objective lens 45 and is condensed. Is done. The beam size of the laser beam L3 at the focal position of the objective lens 45 is about 3 μm to 4 μm. Also, the objective lens 4
The laser beam L3 that has passed through 5 is actually applied to the surface (fuse 23) of the wafer 20 placed on the Z stage 11. Hereinafter, the laser beam L3 that has passed through the objective lens 45
Is referred to as “processing laser light L3”.

Here, the energy value of the processing laser beam L3 is determined according to the amount of energy attenuation by the attenuator 42 (that is, the rotation angle φ of the attenuator 42) when the output of the processing laser 41 is constant. Hereinafter, the energy value of the processing laser beam L3 is referred to as a “processing energy value”. In the laser processing apparatus 10, on the XY stage 13, a joule meter 19 for directly measuring the above processing energy value (energy value of the processing laser light L3 applied to the surface (fuse 23) of the wafer 20) is provided. Have been.

Further, the surface of the wafer 20 (fuse 2) mounted on the Z stage 11 is
An oblique incidence type Z sensor 17 for measuring how much the 3 position (3) (the position in the optical axis direction of the processing laser light L3) deviates from the reference position is provided. In the first embodiment, the reference position is adjusted so as to correspond to the focal position of the objective lens 45.

Here, the Z sensor 17 will be described.
As shown in FIG. 3A, the Z sensor 17 emits light L11 from a direction inclined with respect to the Z direction.
And a collimator lens 32 arranged on the trajectory of the light L11 from the LED 31 and a parallel flat glass obliquely arranged with respect to the trajectory of the light L12 reflected on the surface of the wafer 20 (hereinafter referred to as "sample surface 20a"). 33, a condenser lens 34 for condensing the light L13 passing through the parallel plate glass 33,
It comprises a two-divided detector 35 for detecting the light L13 condensed by the condenser lens 34.

Note that the two-divided detector 35 is shown in FIG.
As shown in FIG. 3, the light receiving section has two light receiving sections 35a and 35b. Here, the parallel flat glass 33 (FIG. 3A) is disposed obliquely with respect to the trajectory of the light L12 as described above. Thus, the light L1 that has passed through the parallel flat glass 33
The trajectory of No. 3 can be shifted from the trajectory of the light L12 reflected on the sample surface 20a. This parallel flat glass 33
Is determined according to the inclination angle θ of the parallel flat glass 33 with respect to the trajectory of the light L12.

In such a Z sensor 17, the LED
Light L <b> 11 from 31 enters obliquely through a collimator lens 32 to a transparent protective film 22 that covers the entire surface of the wafer 20. At this time, light L11
Is refracted on the surface of the protective film 22. Then, the protective film 22
The light L11 incident on the sample passes through the protective film 22 and is reflected on the sample surface 20a.

In FIG. 3A, the fuse 2 formed between the wafer 20 and the protective film 22 is shown for simplicity.
3, illustration of the insulating film 24 and the protective film 25 (see FIG. 2C) is omitted. Thus, the protective film 2 is formed on the sample surface 20a.
2 and the light L11 from the LED 31 is refracted on the surface of the protective film 22, so that the light L12 reflected on the sample surface 20a
Is shifted by ΔOb from the reflected light L15 (indicated by a dotted line in the figure) when the sample surface 20a is not covered with the protective film 22.

The orbit is ΔOb due to the influence of the protective film 22.
The light L12 shifted by only
Incident on. The parallel flat glass 33 shifts the trajectory of the light L12 by ΔOa according to the inclination angle θ as described above. In the first embodiment, the inclination angle θ of the parallel flat glass 33 is set so that ΔOa = ΔOb.

Therefore, the point D at which the light L13 passing through the parallel flat glass 33 enters the two-divided detector 35
Coincides with the point where the reflected light L15 (indicated by a dotted line in the figure) enters when the sample surface 20a is not covered with the protective film 22. As described above, in the Z sensor 17, the shift ΔOb of the trajectory of the light L12 due to the influence of the protective film 22 is corrected by disposing the parallel plate glass 33 having the inclination angle θ on the trajectory of the light L12 reflected by the sample surface 20a. can do. That is, at the time of measurement by the Z sensor 17, as shown in FIG. 3C, an offset can be placed on the Z position of the sample surface 20a.

Further, in the Z sensor 17, the point D at which the light L13 passing through the parallel flat glass 33 is incident on the two-segment detector 35 is, as shown in FIG.
It differs depending on the Z position of the sample surface 20a. In FIG. 4A,
When the Z position of the sample surface 20a is Z1, Z2, Z3, the state where the light L13 passing through the parallel flat glass 33 is incident on the positions D1, D2, D3 of the two-divided detector 35 is shown. 4B to 4D show the light L13 and the light receiving unit 3
The positional relationship with 5a and 35b is shown.

The two-divided detector 35 includes a light receiving section 35a,
The light L13 is received in each of the light receiving portions 35b, and a difference signal based on the difference in the amount of received light is output. Incidentally, this difference signal is calculated based on the incident position (D1, D1) of the light L13 in the two-segment detector 35.
2, D3), that is, the Z position (Z1, Z1) of the sample surface 20a.
Z2, Z3). In the first embodiment, the difference signal from the two-segment detector 35 is zero when the Z position of the sample surface 20a (substantially equal to the Z position of the fuse 23) matches the reference position (the focal position of the objective lens 45). Becomes

Therefore, according to the Z sensor 17, based on the difference signal from the two-divided detector 35, the sample surface 20
It is possible to measure the amount of displacement of the Z position a (the Z position of the fuse 23) from the reference position (the focal position of the objective lens 45).

The spot size of the light L11 on the sample surface 20a is about 1200 μm. That is, Z
The light L11 emitted upon measurement by the sensor 17 is:
A window 22a in which a plurality of fuses 23 are formed (FIG. 2B)
reference. A large area including a size w of about 40 μm) is entirely irradiated. As a result, the influence of the minute unevenness of the protective film 22 covering the surface of the wafer 20 is cancelled, and a measurement result (position shift amount) with less noise is obtained.

Here, the above-described offset set by the parallel flat glass 33 at the time of measurement by the Z sensor 17 corresponds to a focus offset. The laser processing apparatus 10 (FIG. 1) has an observation system 50 for observing the surface shape of the wafer 20 and monitoring the processing state.
And an alignment system 60 for detecting an alignment mark formed on the surface of the wafer 20.

The observation system 50 includes an illumination lamp 51.
(For example, a halogen lamp), a half mirror 52, and I
TV camera 53, image processing unit 54, monitor 5
5 are provided. In such an observation system 50, the observation illumination light L4 emitted from the illumination lamp 51 is guided to the wafer 20 side along the optical axis of the objective lens 45 by the half mirror 52, and is irradiated on the surface of the wafer 20. You.

The light reflected on the surface of the wafer 20 returns along the optical axis of the objective lens 45, passes through the half mirror 52 (light L5), and is detected by the ITV camera 53. A detection signal from the ITV camera 53 is output to a monitor 55 through various signal processing in an image processing unit 54. The monitor 55 displays an image of the surface of the wafer 20.

The alignment system 60 includes an alignment laser 61 (for example, a He-Ne laser having a wavelength of 633 nm), a beam splitter 62, and a half mirror 6
3 and a detection optical system 64 including a photodetector formed of a photoelectric conversion element or the like. Such an alignment system 60
, The alignment laser light L6 emitted from the alignment laser 61 is transmitted through the half mirror 63, and then the objective lens 4
5 is guided to the wafer 20 side along the optical axis of
Irradiation is performed on the 0 surface (alignment mark).

The light reflected on the surface (alignment mark) of the wafer 20 returns along the optical axis of the objective lens 45, is reflected on the beam splitter 62 and the half mirror 63 (light L7), and is detected by the detection optical system 64. Is detected by The detection optical system 64 outputs an alignment signal based on the light L7. The laser processing apparatus 10 according to the first embodiment includes a Z controller 12, an XY actuator 14, an XY position monitor 16, a Z sensor 17, a stage controller 71 connected to the processing laser 41 of the irradiation system 40, and irradiation. Attenuator 42 of system 40 and optical system 4
3, a laser power controller 72 connected to the joule meter 19, and a detection optical system 64 of the alignment system 60.
And an alignment controller 73 connected to the controller.

Further, the laser processing apparatus 10 includes a stage controller 71, a laser power controller 72,
An alignment controller 73, a main controller 70 connected to the image processing unit 54 of the observation system 50,
A loader controller 74 connected to the main controller 70 is provided. In addition, the laser processing device 10
An input unit 75 composed of a keyboard or the like is connected to the main controller 70.

The main controller 70 includes a storage unit 70a. The storage unit 70 a stores the wafer 2 of each fuse 23 formed on the wafer 20.
XY coordinates (in-plane position information) within 0 and each fuse 23
The optimum processing energy value (hereinafter, referred to as “optimum energy value”) when performing the cutting process is stored as a control table.

The control table relating to the optimum energy value of each fuse 23 will be specifically described.
In the embodiment, as shown in FIG. 5, the optimum energy value and the position of the semiconductor chip 21 (Column, Row)
And it is made to correspond. That is, in the optimum energy value control table 76 shown in FIG. 5, the same optimum energy value is set for the fuses 23 formed in the same semiconductor chip 21.

The optimum energy value control table 76 stores the optimum energy value obtained based on data measured by an external device, for example, in the main controller 70.
Are created by inputting from an input unit 75 connected to the storage unit 70a, and stored in the storage unit 70a. The measurement by the external device is performed, for example, by trial hitting the sample of the wafer 20 and observing the cutting state.

The control table 7 for the optimum energy value
No. 6 is usually prepared for each type of the wafer 20 which is a workpiece. The storage unit 70a of the main controller 70 stores processing condition data such as the beam size, the number of pulses, and the wavelength of the processing laser light L3, in addition to the control table 76 of the optimum energy value.

Further, the storage unit 70a stores the wafer 20
Of the fuses 23, 23,.
The XY coordinates (in-plane position information) of the fuse to be cut (hereinafter referred to as “cut target fuse”) 23 in the wafer 20, the order data for performing the laser processing for these cut target fuses, and the laser processing A program for performing the processing is stored in advance.

The main controller 70 has a storage unit 70a
Based on various data and programs stored in
Stage controller 71, power controller 72,
Alignment controller 73, loader controller 7
4 to perform laser processing on the fuse 23 to be cut (details will be described later). Incidentally, the laser power controller 72 controls the actuator (not shown) of the attenuator 42 while monitoring the rotation angle φ of the attenuator 42 by an encoder (not shown) attached to the attenuator 42 of the irradiation system 40. Sets the rotation angle φ of the attenuator 42 to a desired angle, that is, the Z stage 11
The processing energy value of the processing laser beam L3 applied to the surface (fuse 23) of the wafer 20 placed on the wafer 20 is set to a desired value.

Such a laser power controller 72
, The setting of the processing energy value of the processing laser beam L3 applied to the surface (fuse 23) of the wafer 20 is a control signal related to the processing energy value output from the main controller 70. It is performed based on. For this reason, the laser power controller 72 is provided with a storage unit 72a that stores, as a control table, the relationship between the processing energy value and the rotation angle φ of the attenuator 42.

Incidentally, the control table of the processing energy value with respect to the rotation angle φ of the attenuator 42 contains the measurement results (rotation angle φ) of the encoder attached to the attenuator 42 by the laser power controller 72 prior to the laser processing described later. ) And the measurement result (processing energy value) of the Joule meter 19, and stored in the storage unit 72a.

When the processing energy value is measured by the joule meter 19, a control signal is output from the main controller 70 to the stage controller 71, and the joule meter 19 is positioned on the optical axis of the objective lens 45. The above-described wafer 20 corresponds to the “workpiece” in claim 1. The Z stage 11 corresponds to the “stage” of claim 1. The fuse 23 to be cut corresponds to the “working point” in claim 1. Processing laser 41, optical system 4
3, the beam splitter 44, the objective lens 45, and the laser power controller 72 correspond to the "laser irradiating means" in claim 1.

Further, the attenuator 42 and the laser power controller 72 correspond to the "energy setting means" of the first aspect. The main controller 70 is configured to
"Energy changing means". Storage unit 70a
Corresponds to the “energy storage unit” in claim 4. The processing laser 41 corresponds to the “light source unit” in claim 9. The attenuator 42 corresponds to a “damping member” of claim 9.

Next, fuses 23, 23,... (FIG. 2) formed on each semiconductor chip 21 on the wafer 20 using the laser processing apparatus 10 (FIG. 1) configured as described above.
The processing operation when cutting is described. First, the main controller 70 outputs a control signal to the loader controller 74, and transports one of the plurality of wafers 20, 20, ... stored in the workpiece storage case (not shown) to the Z stage 11.

Next, the main controller 70 performs alignment of the wafer 20 placed on the Z stage 11. For the alignment, the main controller 70
Outputs a control signal to the stage controller 71 to output X
While moving the Y stage 13, a control signal is output to the alignment controller 73 to obtain an alignment signal output from the detection optical system 64 of the alignment system 60.

Then, the main controller 70 determines the position of the XY stage 13 when the alignment signal from the detection optical system 64 becomes maximum (when the laser beam L6 from the alignment laser 61 crosses the alignment mark) by the position monitor 16. Is detected based on the XY position information output from. When the alignment is completed in this manner, the main controller 70 starts laser processing on the wafer 20 placed on the Z stage 11.

In the laser processing, the main controller 70 first obtains one XY coordinate (Xo, Yo) of the fuse 23 to be cut stored in the storage unit 70a. Further, the main controller 70 transmits the acquired XY
An optimum energy value Eo (optimum energy value when cutting the fuse 23 to be cut) predetermined according to the coordinates (Xo, Yo) is obtained from the control table 76 (FIG. 5) in the storage unit 70a. get. The XY coordinates (Xo, Yo) of the fuse 23 to be cut and the semiconductor chip 2
The correspondence with the position 1 (Column, Row) is known.

Then, the main controller 70 outputs a control signal relating to the obtained optimum energy value Eo to the laser power controller 72, and changes the processing energy value set by the laser power controller 72. The laser power controller 72 obtains a rotation angle φo of the attenuator 42 corresponding to the optimum energy value Eo from a control table in the storage unit 72a based on a control signal related to the optimum energy value Eo output from the main controller 70. I do.

Next, the laser power controller 72
Controls the actuator of the attenuator 42 while monitoring the rotation angle φ by the encoder of the attenuator 42, and sets the rotation angle φ of the attenuator 42 to the obtained rotation angle φo (that is, the processing energy value). Is set to the optimum energy value Eo). On the other hand, the main controller 70
The XY coordinates (X
A control signal relating to (o, Yo) is output to the stage controller 71.

The stage controller 71 outputs a control signal relating to XY coordinates (Xo, Yo) output from the main controller 70 and a measurement result (X
The XY actuator 13 is controlled based on the Y position information) to move the XY stage 13 in the XY directions.

As a result, the fuse 23 (XY coordinates (Xo, Yo)) to be cut is positioned on the optical axis of the objective lens 45. Next, the stage controller 71 acquires the difference signal output from the two-divided detector 35 of the Z sensor 17, and based on the difference signal, sets the Z stage 11 in the Z
A drive signal for moving the object in the direction is calculated. And
The stage controller 71 outputs the calculated drive signal to the Z actuator 12, and moves the Z stage 11 in the Z direction. The stage controller 71, the Z sensor 17, the Z stage 11, and the Z actuator 12 constitute an autofocus system.

Here, the difference signal output from the two-divided detector 35 is, as described above,
The fuse 23 to be cut is positioned at the reference position (the focal position of the objective lens 45) by the above-mentioned autofocus system in order to indicate the amount of positional deviation between the Z position of (1) and the reference position (the focal position of the objective lens 45). You. When the positioning of the fuse 23 to be cut in the XY direction and the Z direction is completed in this way, the stage controller 71 outputs a trigger signal to the processing laser 41.

The processing laser 41 oscillates in response to a trigger signal from the stage controller 71.
The laser light L1 from the processing laser 41 passes through the attenuator 42, the optical system 43, and the beam splitter 44, and passes through the objective lens 4
5 is guided to the wafer 20 side along the optical axis. And
The processing laser light L3 is applied to the surface (the cutting target fuse 23) of the wafer 20 mounted on the Z stage 11.

Since the fuse 23 to be cut is positioned at the focal position of the objective lens 45 by the above-described positioning in the Z direction, the processing laser beam L3 that has passed through the objective lens 45 and is condensed is transmitted to the fuse 23 to be cut. Is irradiated.

Further, since the attenuator 42 is set at the rotation angle φo, the processing laser beam L having the optimum energy value Eo is obtained.
3 is irradiated to the fuse 23 to be cut and cut. 1
When the cutting of one of the fuses to be cut 23 is completed, the main controller 70 starts the cutting of the next fuse to be cut 23 according to the sequence data and the program stored in advance.

In other words, the main controller 70 determines the XY coordinates (X
i, Yi) is transmitted to the stage controller 7
1 and outputs a control signal related to the optimum energy value Ei to the laser power controller 72. Further, the laser power controller 72 sets the rotation angle φ of the attenuator 42 to the rotation angle φi corresponding to the optimum energy value Ei.
(That is, the processing energy value is set to the optimum energy value Ei).

On the other hand, the stage controller 71 outputs a trigger signal to the processing laser 41 after positioning the next fuse 23 to be cut in the XY direction and the Z direction. Then, the cutting laser 23 is irradiated with the processing laser beam L3 having the optimum energy value Ei, and is cut. As described above, according to the laser processing apparatus 10 of the first embodiment, the processing energy value of the processing laser light L3 applied to the cutting target fuse 23 is determined in advance according to the XY coordinates of the cutting target fuse 23. Cutting processing can be performed by changing the setting to the optimum energy value.

Therefore, when a plurality of fuses 23 to be cut are formed on the wafer 20, the size (width, length, thickness) of the fuse 23 to be cut is determined by the position (XY coordinate) in the wafer 20. ), The setting change of the processing energy value, the positioning of the cutting target fuse 23, and the pulse oscillation of the processing laser beam L3 are repeatedly performed, so that all the cutting target fuses 23, 23, .. Can be favorably cut.

That is, all the fuses 23 to be cut in the wafer 20 are replaced with the respective fuses 23 to be cut.
Can be reliably cut without damaging the underlying film (such as the insulating film 24 in FIGS. 2C and 2D). Also,
Since it is not necessary to change the output of the processing laser 41 in order to change the setting of the processing energy value of the processing laser light L3, a small laser with a small output can be used as the processing laser 41. Further, since the output of the processing laser 41 may be kept constant, the control is simplified.

(Second Embodiment) Next, a second embodiment will be described. The second embodiment is described in claim 3 and claim 5 to claim 5.
This corresponds to claims 8 and 11. FIG. 6 is an overall configuration diagram illustrating a laser processing apparatus 90 according to the second embodiment.
The laser processing device 90 (FIG. 6) of the second embodiment is also a device for processing the surface of the wafer 20 which is a workpiece using laser light. Here, as in the first embodiment described above, Fuse 2 formed on the surface of wafer 20
(FIG. 2) will be described as an example.

The cutting process for the fuses 23 formed on the surface of the wafer 20 is performed in the same manner as in the first embodiment described above, with the predetermined energy narrowed according to the width of the fuses 23 and the interval between the fuses 23. This is performed by irradiating a pulse of laser light to the fuse 23 to be cut.
However, in the second embodiment, unlike the above-described first embodiment, the energy value of the laser beam applied to the fuse 23 to be cut is changed to the wafer 20 of the fuse 23 to be cut.
The cutting process is performed while maintaining a constant value regardless of the XY coordinates in the area.

Instead, in the second embodiment, the offset value (see FIG. 3C) used for positioning the fuse 23 to be cut in the Z direction is changed to the semiconductor chip 21.
The setting is changed in units, and a cutting process is performed on a large number of fuses 23 formed on the surface of the wafer 20. When the fuses 23, 23,... Formed in the same semiconductor chip 21 are positioned in the Z direction, the same offset value is used.

Here, the offset value (see FIG. 3C) used for positioning the fuse 23 to be cut in the Z direction is determined by the parallel flat glass 33 constituting the Z sensor 17.
(See FIG. 3 (a)). In the laser processing apparatus 90 (FIG. 6) of the second embodiment, the parallel flat glass 33
An actuator (not shown) for rotating the laser beam 3 with respect to the trajectory of the light L12 and an encoder (not shown) for measuring the inclination angle θ of the parallel flat glass 33 are provided.

Next, the overall configuration of the laser processing apparatus 90 will be described focusing on differences from the laser processing apparatus 10 (FIG. 1) of the first embodiment. In the laser processing apparatus 90 (FIG. 6), the same reference numerals are given to the same components as those of the laser processing apparatus 10 (FIG. 1). The laser processing device 90 (FIG. 6) includes the main controller 7 of the laser processing device 10 (FIG. 1) of the above-described first embodiment.
0, a stage controller 71, and a laser power controller 72, a main controller 80, a stage controller 81, and a laser power controller 82 are provided.

The main controller 80 includes a storage section 80a. The storage unit 80a stores the wafer 2 of each fuse 23 formed on the wafer 20.
XY coordinates (in-plane position information) within 0 and each fuse 23
Is stored as a control table with an optimum offset value (hereinafter, referred to as an “optimal offset value”) when positioning is performed in the Z direction.

The control table relating to the optimum offset value of each fuse 23 will be specifically described.
In the embodiment, as shown in FIG. 7, the optimum offset value and the position of the semiconductor chip 21 (Column, Row)
And it is made to correspond. That is, in the optimal offset value control table 83 shown in FIG. 7, the same optimal offset value is set for the fuses 23 formed in the same semiconductor chip 21.

By the way, the optimum offset value control table 83 is obtained by inputting the optimum offset value obtained based on data measured by an external device (such as a microscope) from the input unit 75 connected to the main controller 80. And is stored in the storage unit 80a. The data measured by the external device is, for example, the protective film 22 covering the surface of the semiconductor chip 21 (see FIG. 2C).
On the thickness and the state of lamination.

The control table 8 for the optimum offset value
No. 3 is usually prepared for each type of the wafer 20 which is the workpiece. The storage unit 80a of the main controller 80 stores, in addition to the control table 83 of the above-described optimum offset value, the processing energy value, the beam size, the number of pulses, the wavelength, and the like of the processing laser light L3 applied to the fuse 23 to be cut. Processing condition data is also stored.

Further, in the storage unit 80a, XY coordinates (in-plane position information) of the plurality of cut target fuses 23, 23,... In the wafer 20, and laser processing for these cut target fuses are performed. Order data, a program for performing laser processing, and the like are stored in advance. The main controller 80 controls the stage controller 81, the power controller 82, the alignment controller 73, and the loader controller 74 based on various data, programs, and the like stored in the storage unit 80a, and performs laser processing on the fuse 23 to be cut. (Details will be described later).

On the other hand, the stage controller 81 uses an encoder (not shown) attached to the parallel plate glass 33 of the Z sensor 17 to tilt the parallel plate glass 33 at an angle θ.
By controlling the actuator (not shown) of the parallel flat glass 33 while monitoring the
Is set to a desired angle, that is, the surface (the fuse 2) of the wafer 20 placed on the Z stage 11 is set.
3) The offset value for positioning in the Z direction is set to a desired value.

The setting of the inclination angle θ of the parallel flat glass 33 by the stage controller 81, that is, the setting of the offset value when positioning the surface (fuse 23) of the wafer 20 in the Z direction is performed by the main controller 8
This is performed based on a control signal regarding an offset value output from 0. For this reason, the stage controller 81 is provided with a storage unit 81a that stores, as a control table, the relationship of the offset value to the tilt angle θ of the parallel flat glass 33.

By the way, the inclination angle θ of the parallel flat glass 33
The control table of the offset value for is prepared by the stage controller 81 and stored in the storage unit 81a prior to the laser processing described later. Further, the laser power controller 82 uses an encoder (not shown) attached to the attenuator 42 of the irradiation system 40 to control the attenuator 4.
By controlling the actuator (not shown) of the attenuator 42 while monitoring the rotation angle φ of No. 2, the rotation angle φ of the attenuator 42 is set to a desired angle, that is, mounted on the Z stage 11. Surface of wafer 20 (fuse 23)
Is set to a desired value of the processing energy value of the processing laser beam L3 applied to the laser beam.

The above-mentioned wafer 20 is provided in claim 3
Corresponds to the “workpiece”. The Z stage 11 corresponds to the “stage” of claim 3. Fuse 23 to be cut
Corresponds to the “machining point” in claim 3. Processing laser 4
1, optical system 43, beam splitter 44, objective lens 4
5. The laser power controller 82 corresponds to the “laser irradiation means” in claim 3.

The Z sensor 17, the Z stage 11, the Z actuator 12, the stage controller 8
The autofocus system constituted by 1 corresponds to “positioning means” in claim 3. The parallel flat glass 33 and the stage controller 81 correspond to the “offset setting means” in claim 3. The main controller 80 corresponds to an “offset changing unit” in claim 3.

Further, the above-mentioned storage section 80a corresponds to the "offset storage section" of the present invention. Objective lens 45
Corresponds to the “objective optical system” of claim 6. LED31
The light L11 from corresponds to the “beam” in claim 7.
The Z sensor 17 corresponds to the “measuring unit” in claim 7. The parallel flat glass 33 corresponds to the “shift member” of claim 8.

Next, the fuses 23, 23,... (FIG. 2) formed on each semiconductor chip 21 on the wafer 20 using the laser processing apparatus 90 (FIG. 6) configured as described above.
The processing operation when cutting is described. When the transfer of the wafer 20 to the Z stage 11 and the alignment of the wafer 20 placed on the Z stage 11 are completed, the main controller 80 starts laser processing on the wafer 20 placed on the Z stage 11.

In the laser processing, the main controller 80 obtains one XY coordinate (Xo, Yo) of the fuse 23 to be cut stored in the storage section 80a, and controls the obtained XY coordinate (Xo, Yo). The signal is output to the stage controller 81. Further, the main controller 80 stores the optimum offset value OSo (the optimum offset value when positioning the cutting target fuse 23 in the Z direction) predetermined according to the acquired XY coordinates (Xo, Yo) in the storage unit 80a. Control table 83 (FIG. 7)
To get from.

Then, the main controller 80 outputs a control signal relating to the obtained optimum offset value OSo to the stage controller 81, and
Change the offset value set by 1. on the other hand,
The stage controller 81 includes a main controller 80
Control signals output from the XY-coordinates (Xo, Yo) and the measurement results of the XY position monitor 16 (XY position information)
XY actuator 14 is controlled based on
The stage 13 is moved in the X and Y directions. As a result, the cutting target fuse 23 (XY coordinates (Xo, Yo)) is positioned on the optical axis of the objective lens 45.

The stage controller 81 outputs the optimum offset value O output from the main controller 80.
Based on a control signal relating to So, the inclination angle θo of the parallel flat glass 33 corresponding to the optimum offset value OSo.
From the control table in the storage unit 81a. Next, the stage controller 81 controls the actuator of the parallel flat glass 33 while monitoring the tilt angle θ by the encoder of the parallel flat glass 33, and sets the tilt angle θ of the parallel flat glass 33 to the obtained tilt angle θo. (That is, the offset value is changed to the optimum offset value OSo.
Set to.)

When the setting of the tilt angle θo (optimum offset value OSo) is completed, the stage controller 81 determines the Z actuator 12 based on the difference signal (representing the amount of displacement) output from the two-divided detector 35 of the Z sensor 17.
To move the Z stage 11 in the Z direction. Here, since the parallel flat glass 33 is set at the inclination angle θo, the difference signal output from the two-segment detector 35 is added with the optimum offset value OSo. Therefore, the fuse 23 to be cut is accurately positioned at the reference position (the focal position of the objective lens 45).

When the positioning of the fuse 23 to be cut in the XY and Z directions is completed, the stage controller 81 outputs a trigger signal to the processing laser 41. The processing laser 41 performs pulse oscillation according to a trigger signal from the stage controller 81.

The laser light L1 from the processing laser 41 passes through the attenuator 42, the optical system 43, and the beam splitter 44,
The light is guided toward the wafer 20 along the optical axis of the objective lens 45. Then, the processing laser beam L3 is irradiated onto the surface of the wafer 20 placed on the Z stage 11 (the fuse 23 to be cut).
Is irradiated. Since the fuse 23 to be cut is accurately positioned at the focal position of the objective lens 45 by the above-described positioning in the Z direction, the processing laser light L3 condensed through the objective lens 45 is focused on the fuse 23 to be cut. Irradiated and cut.

When the cutting of one fuse 23 is completed, the main controller 80 starts the cutting of the next fuse 23 in accordance with the sequence data and program stored in advance.
As described above, the main controller 80 outputs to the stage controller 81 a control signal related to the XY coordinates (Xi, Yi) of the next fuse 23 to be cut and a control signal related to the optimum offset value OSi.

The stage controller 81 sets the inclination angle θ of the parallel flat glass 33 to the inclination angle θi corresponding to the optimum offset value OSi (that is, sets the offset value to the optimum offset value OSi). This gives Z
The optimum offset value OSi is added to the difference signal output from the two-divided detector 35 of the sensor 17.

Then, the stage controller 81 positions the next fuse 23 to be cut in the X and Y directions, and positions the next fuse 23 to be cut in the Z direction based on the difference signal with the optimum offset value OSi added. After that, a trigger signal is output to the processing laser 41.

Since the fuse 23 to be cut is accurately positioned at the focal position of the objective lens 45 by the above-described positioning in the Z direction, the processing laser light L3 condensed through the objective lens 45 is cut off by the cutting. Target fuse 23
Irradiated and cut. As described above, according to the laser processing apparatus 90 of the second embodiment, the offset value (FIG. 3C) used for positioning the fuse 23 to be cut in the Z direction is converted to the XY coordinates of the fuse 23 to be cut. The cutting process can be performed by changing the setting to a predetermined optimum offset value accordingly.

Therefore, when a plurality of fuses 23 to be cut are formed on the wafer 20, the surface state of the wafer 20 (for example, the thickness or the laminated state of the protective film 22 shown in FIG. 2C). Is different depending on the position (XY coordinates) in the wafer 20, the setting change of the offset value, the positioning of the cutting target fuse 23, and the pulse oscillation of the processing laser light L <b> 3 are repeatedly performed. All fuses to be cut 23, 2
Good cutting can be performed on 3,.

That is, all the fuses 23 to be cut in the wafer 20 are replaced with the respective fuses 23 to be cut.
Can be reliably cut without damaging the underlying film (such as the insulating film 24 in FIGS. 2C and 2D). (Third Embodiment) Next, a third embodiment will be described. The third embodiment is described in claim 2, claim 4 to claim 11.
Corresponding to

FIG. 8 shows a laser processing apparatus 1 according to the third embodiment.
FIG. 3 is an overall configuration diagram illustrating 00. In the third embodiment, the fuse 2 formed on the surface of the wafer 20
2 (see FIG. 2), the energy value of the laser beam applied to the cutting target fuse 23 is changed for each semiconductor chip 21 and the offset used for positioning the cutting target fuse 23 in the Z direction. The value (see FIG. 3C) is set and changed for each semiconductor chip 21.

For this reason, the laser processing apparatus 100 (FIG. 8)
The XY coordinates of each fuse 23 formed on the wafer 20 in the wafer 20 and the optimum energy value when cutting each fuse 23 are stored in the storage unit 85a of the main controller 85 provided in the main controller 85. , Each fuse 23
Is stored as a control table.

The control table will be specifically described. In the third embodiment, as shown in FIG.
The optimum energy value and the optimum offset value correspond to the position (Column, Row) of the semiconductor chip 21. That is, the control table 88 of the optimum energy value and the optimum offset value shown in FIG.
Now, the fuse 2 formed in the same semiconductor chip 21
3, the same optimal energy value and optimal offset value are set.

The optimum energy value in the control table 88 is, for example, the optimum energy value obtained based on data measured by an external device,
Are input from the input unit 75 connected to the. The measurement by the external device is, for example, test hitting on a sample of the wafer 20 and observation of sharpness by a microscope.

The optimum offset value in the control table 88 is obtained, for example, by inputting the optimum offset value obtained based on data measured by an external device (such as a microscope) from the input section 75 connected to the main controller 85. It is. The data measured by the external device is, for example,
The protective film 22 covering the surface of the semiconductor chip 21 (FIG. 2)
(c)) is data on the thickness and the state of lamination.

The storage section 85a of the main controller 85 (FIG. 8) stores, in addition to the control table 88, processing information such as the beam size, pulse number, and wavelength of the processing laser light L3 applied to the fuse 23 to be cut. Condition data is also stored. Further, the storage unit 85a stores the XY in the wafer 20 of the plurality of fuses to be cut 23, 23,.
Coordinates, order data for performing laser processing on these fuses to be cut, and a program for performing laser processing are stored in advance.

On the other hand, the stage controller 86 and the storage unit 86a provided in the laser processing apparatus 100 are the same as the stage controller 81 and the storage unit 81a (FIG. 6) of the second embodiment described above, and the description thereof will be omitted. I do. Further, the laser power controller 87 and the storage unit 87a provided in the laser processing apparatus 100 are the same as the laser power controller 72 and the storage unit 72a (FIG. 1) of the above-described first embodiment, and a description thereof will be omitted. .

In the laser processing apparatus 100 (FIG. 8), the configuration other than the main controller 85, the stage controller 86, and the power controller 87 is the same as the laser processing apparatus 10 (FIG. 1) of the first embodiment described above.
Since it is common to the laser processing apparatus 90 (FIG. 6) of the embodiment, the same reference numerals are given and the description is omitted. here,
The above-described autofocus system including the Z sensor 17, the Z stage 11, the Z actuator 12, and the stage controller 86 corresponds to the "positioning means" of the present invention. Parallel flat glass 33, stage controller 8
6 corresponds to the “offset setting means” of claim 2.
The main controller 85 corresponds to the “offset changing unit” in claim 2.

Next, when the fuses 23, 23,... (FIG. 2) formed on each semiconductor chip 21 on the wafer 20 are cut using the laser processing apparatus 100 (FIG. 8) configured as described above. Will be described. The main controller 85 controls the stage controller 86, the power controller 87, the alignment controller 73, and the loader controller 74 based on various data and programs stored in the storage unit 85a, and performs laser processing on the fuse 23 to be cut. .

When the laser processing is started, the main controller 85 obtains one XY coordinate (Xo, Yo) of the fuse 23 to be cut stored in the storage unit 85a, and obtains the obtained XY coordinate (Xo, Yo). The control signal is output to the stage controller 86. The main controller 85 also determines an optimum energy value Eo (optimum energy value when cutting the fuse 23 to be cut) predetermined according to the acquired XY coordinates (Xo, Yo), and an optimum offset value. OSo (the optimal offset value when positioning the cutting target fuse 23 in the Z direction) is obtained from the control table 88 (FIG. 9) in the storage unit 85a.

Then, the main controller 85 outputs a control signal relating to the obtained optimum energy value Eo to the laser power controller 87, and changes the processing energy value set by the laser power controller 87. Further, the main controller 85 outputs a control signal relating to the acquired optimum offset value OSo to the stage controller 86, and changes the offset value set by the stage controller 86.

On the other hand, the laser power controller 87
Based on a control signal related to the optimum energy value Eo from the main controller 85, the rotation angle φo of the attenuator 42 corresponding to the optimum energy value Eo is acquired from the storage unit 87a, as in the laser power controller 72 described above. Is rotated to set the rotation angle φo (that is, the processing energy value is set to the optimum energy value Eo).

The stage controller 86, like the stage controller 81, based on the control signal about the XY coordinates (Xo, Yo) from the main controller 85 and the measurement result of the XY position monitor 16, 23 (XY coordinates (Xo, Yo)) is positioned on the optical axis of the objective lens 45.

Further, based on a control signal relating to the optimum offset value OSo from the main controller 85, the stage controller 86 determines the inclination angle θo of the parallel flat glass 33 corresponding to the optimum offset value OSo, similarly to the stage controller 81 described above. Obtained from the storage unit 86a, the parallel flat glass 33 is rotated to set the inclination angle θo (that is, the offset value is set to the optimum offset value OS).
o)).

When the setting of the inclination angle θo (optimum offset value OSo) is completed, the stage controller 86 determines the difference signal (the optimum offset value OSo is added) output from the two-divided detector 35 of the Z sensor 17. Thus, similarly to the stage controller 81 described above, the fuse 23 to be cut is accurately positioned at the reference position (the focal position of the objective lens 45).

When the positioning of the fuse 23 to be cut in the XY and Z directions is completed in this way, a trigger signal is output from the stage controller 86 to the processing laser 41, and the processing laser light L3 that has oscillated from the processing laser 41 is oscillated. , Wafer 20 mounted on Z stage 11
(The fuse 23 to be cut). Since the fuse 23 to be cut is accurately positioned at the focal position of the objective lens 45 by the above-described positioning in the Z direction, the processing laser light L3 condensed through the objective lens 45 is focused on the fuse 23 to be cut. Irradiated.

Furthermore, since the attenuator 42 is set at the rotation angle φo, the processing laser light L having the optimum energy value Eo is obtained.
3 is irradiated to the fuse 23 to be cut. as a result,
The blow target fuse 23 is satisfactorily blown. When the cutting of one fuse to be cut 23 is completed, the main controller 85 sends the next fuse to be cut 2 according to the sequence data and program stored in advance.
The cutting process for No. 3 is started.

The main controller 85, as described above,
A control signal related to the XY coordinates (Xi, Yi) of the next fuse 23 to be cut and a control signal related to the optimum offset value OSi are output to the stage controller 86, and a control signal related to the optimum energy value Ei is output to the laser power controller 87. I do. Further, the laser power controller 87 sets the rotation angle φ of the attenuator 42 to the rotation angle φi corresponding to the optimum energy value Ei (that is, sets the processing energy value to the optimum energy value Ei).

Further, the stage controller 86 sets the inclination angle θ of the parallel flat glass 33 to the optimum offset value OS.
i is set to the inclination angle θi corresponding to i (that is, the offset value is set to the optimum offset value OSi). As a result, the optimum offset value OSi is added to the difference signal output from the two-divided detector 35 of the Z sensor 17.
Then, the stage controller 86 positions the next fuse 23 to be cut in the XY directions, and positions the fuse 23 to be cut in the Z direction based on the difference signal on which the optimum offset value OSi is added.
A trigger signal is output to the processing laser 41.

Since the fuse 23 to be cut is accurately positioned at the focal position of the objective lens 45 by the above-described positioning in the Z direction, the processing laser light L3 condensed through the objective lens 45 is cut off by the cutting. Target fuse 23
Is irradiated. Furthermore, the cutting target fuse 23 is also irradiated with the processing laser beam L3 having the optimum energy value Ei to be cut.

As described above, according to the laser processing apparatus 100 of the third embodiment, the processing energy value of the processing laser beam L3 applied to the fuse 23 to be cut is determined in advance according to the XY coordinates of the fuse 23 to be cut. The setting is changed to the determined optimum energy value, and the offset value (FIG. 3C) used for positioning the fuse 23 to be cut in the Z direction is determined in advance according to the XY coordinates of the fuse 23 to be cut. The cutting process can be performed by changing the setting to the offset value.

Therefore, when a plurality of fuses 23 to be cut are formed on the wafer 20, the size (width, length, and thickness) of the fuse 23 to be cut and the surface condition of the wafer 20 (for example, FIG. Even if the thickness of the protective film 22 and the laminated state shown in FIG. 2 (c) are different depending on the position (XY coordinates) in the wafer 20, the setting change of the processing energy value and the offset value described above and the cutting target fuse are performed. By repeatedly performing the positioning of 23 and the pulse oscillation of the processing laser light L3, it is possible to perform good cutting of all the fuses 23 to be cut in the wafer 20.

That is, all the fuses 23 to be cut in the wafer 20 are replaced with the respective fuses 23 to be cut.
Can be reliably cut without damaging the underlying film (such as the insulating film 24 in FIGS. 2C and 2D). In addition,
In the above-described first to third embodiments, the disconnection target fuse 2
Although the example in which the energy value of the laser beam applied to the laser beam 3 and / or the offset value used for positioning the fuse 23 to be cut in the Z direction is changed in the unit of the semiconductor chip 21 has been described, the setting change is performed by the semiconductor. Depending on the type of the chip 21, the operation can be performed in one unit in which a plurality of semiconductor chips are put together. Further, one semiconductor chip can be divided into a plurality of blocks, and the setting can be changed for each block as one unit.

In the first to third embodiments described above,
An example in which the offset value (see FIG. 3C) used for positioning the fuse 23 formed on the wafer 20 in the Z direction is set according to the inclination angle θ of the parallel plate glass 33 has been described. Not limited to For example, one of a plurality of prisms (glass blocks) having different thicknesses prepared in advance may be configured to be inserted into the trajectory of the light L12 according to an offset value to be set.

The stage controllers 71 (, 8)
1, 86) may add an offset signal in the process of calculating a drive signal for the Z stage 11 based on the difference signal output from the two-divided detector 35 of the Z sensor 17. In this case, since the parallel plate glass 33 is not required for the Z sensor 17, there is an advantage that the laser processing apparatus does not increase in size.

Further, in the first to third embodiments described above, the fuse 23 to be cut is
Has been described above with reference to the focal position of the objective lens 45, but the optimum Z position when performing laser processing on the fuse 23 to be cut is not necessarily the focal position of the objective lens 45. Depending on the type of the semiconductor chip 21,
The “Z position intentionally shifted from the focal position of the objective lens 45” may be the optimum Z position for laser processing (for example, the Z position at which workability is improved).

In this case, the reference position of the autofocus system is set to “the Z position intentionally shifted from the focal position of the objective lens 45”, or
By setting the offset value in consideration of the amount of deviation between the focal position of the laser beam and the Z position optimal for laser processing, the fuse 23 to be cut is made to coincide with the Z position optimal for laser processing by the autofocus system. Can be.

The optimum Z position for the laser processing of the fuse 23 to be cut is determined by performing a test shot on a sample of the wafer 20 while keeping the processing energy constant and changing the distance between the objective lens 45 and the wafer 20. It can be determined by doing. In the second and third embodiments described above, an example is described in which an external device (such as a microscope) is used to create a control table (see FIGS. 7 and 9) for the optimum offset value. It can also be created based on data measured by the laser processing devices 90 and 100 of the third embodiment.

Here, an example of a method of measuring the optimum offset value using the laser processing device 90 (FIG. 6) will be described. In measuring the optimum offset value, the parallel flat glass 33 (see FIG. 3) of the Z sensor 17 is fixed at an inclination angle of 90 degrees. At this time, the trajectory of the light L13 passing through the parallel plate glass 33 does not shift (ΔOa is zero). That is, the trajectory of the light L12 reflected on the sample surface 20a (the protective film 2
2 is shifted by ΔOb).

When the autofocus system is operated in this state, the sample surface 20a (the fuse 23 to be cut)
Are positioned at positions shifted from the reference position. Incidentally, the deviation amount between the Z position of the sample surface 20a and the reference position at this time corresponds to the optimum offset value. Therefore, when the observation system 50 (FIG. 6) of the laser processing apparatus 90 is operated to observe the surface state of the wafer 20, the image processing unit 5
4 to the main controller 80, the optimum offset value can be obtained based on the focus shift of the image signal.

The operation of obtaining such an optimum offset value is performed at a necessary portion of the wafer 20 (for example, the semiconductor chip 2).
By doing so, a control table (see FIG. 7) for the optimum offset value can be created. Further, as another method for obtaining the optimal offset value, (1) the Z stage 11 is moved while operating the observation system 50 (FIG. 6) of the laser processing apparatus 90 to observe the surface state of the wafer 20. (2) When the image displayed on the monitor 55 is focused, the Z stage 11 is stopped,
(3) There is a method of operating the Z sensor 17 in this state to measure the amount of displacement between the Z position of the sample surface 20a (the fuse 23 to be cut) and the reference position.

The displacement measured at this time corresponds to the optimum offset value if the inclination angle θ of the parallel flat glass 33 (see FIG. 3) constituting the Z sensor 17 is fixed at 90 degrees. Become. In this case as well, the operation of measuring the amount of positional deviation (obtaining the optimum offset value) is performed at a necessary portion of the wafer 20 (for example, for each semiconductor chip 21), so that the control table of the optimum offset value is obtained (see FIG. 7). Can be created.

When the autofocus system is operated using the optimal offset value control table created in this manner, the sample surface 20a (the fuse 23 to be cut) is positioned at the Z position where the observation system 50 can observe the sample surface 20a well. Is done. Further, in the above-described second and third embodiments, an example is described in which the input unit 75 is connected to the main controllers 80 and 85, and a control table of the optimum offset value is created based on data input from the input unit 75. However, when the optimum offset value is measured in the laser processing devices 90 and 100 as described above, the control table creation can be automated, and the operability is improved. In this case, the input unit 75 connected to the main controllers 80 and 85 becomes unnecessary.

In the first to third embodiments described above,
Storage unit 70 of main controller 70 (, 80, 85)
Although the example in which the control table of the optimum energy value and / or the optimum offset value is stored in a (, 80a, 85a) (the energy storage unit of claim 4 and the offset storage unit of claim 5 are provided) has been described, If high-speed processing is not required, the optimum energy value and / or the optimum offset value can be input each time the processing point changes.

Further, in the above-described first to third embodiments, the example in which the alignment of the wafer 20 placed on the Z stage 11 by the alignment system 60 has been described, but the image processing unit 54 of the observation system 50 Alignment can also be performed based on image signals output to the controller 70 (80, 85). in this case,
The alignment system 60 becomes unnecessary.

In the first to third embodiments described above,
Although the XY position monitor 16 is configured by a linear encoder,
The XY position monitor 16 can be composed of a reflecting mirror mounted on the Z stage 11 or the XY stage 13 and a laser interferometer that irradiates the reflecting mirror with a laser beam for measurement.

Furthermore, in the above-described first to third embodiments, an example has been described in which the Z sensor 17 is provided with the two-segment detector 35, but a four-segment detector may be provided instead of the two-segment detector 35. Further, the Z position of the sample surface 20a may be detected by using a multi-point AF system that measures a plurality of emitted lights at multiple points. In the above-described first to third embodiments, the example in which the XY stage 13 is moved to position the fuse 23 to be cut on the optical axis of the processing laser light L3 has been described, but the XY stage 13 is stopped. In advance, the processing laser beam L3 can be moved to position the fuse 23 to be cut. The point is that the relative positional relationship between the cutting target fuse 23 and the optical axis of the processing laser beam L3 may be moved.

Further, in the first to third embodiments described above, an example has been described in which the laser processing apparatuses 10, 90, 100 are used for laser repair. Good cutting can be performed on all the patterns (thin-film resistors) to be cut in the workpiece. That is, all the patterns to be cut (thin film resistors) in the workpiece can be reliably cut without damaging the underlying film of each pattern to be cut. Therefore, the resistance value of the thin film resistor can be adjusted with high accuracy.

[0142]

As described above, according to the first to eleventh aspects of the present invention, it is possible to perform good cutting on all the patterns to be cut on the workpiece. Reliability in laser processing is improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of a laser processing apparatus 10.

FIG. 2 is a diagram illustrating a wafer 20, a semiconductor chip 21, and a fuse 23.

FIG. 3 is a diagram illustrating an oblique incidence type Z sensor 17;

FIG. 4 is a diagram for explaining the operation of the Z sensor 17 according to the Z position of the sample surface 20a.

FIG. 5 is a diagram illustrating an optimal energy value control table.

FIG. 6 is a block diagram illustrating an overall configuration of a laser processing apparatus 90.

FIG. 7 is a diagram illustrating a control table 83 of an optimum offset value.

FIG. 8 is a block diagram illustrating an overall configuration of the laser processing apparatus 100.

FIG. 9 is a diagram illustrating a control table 88 of an optimum energy value and an optimum offset value.

[Explanation of symbols]

 10, 90, 100 Laser processing apparatus 11 Z stage 12 Z actuator 13 XY stage 14 XY actuator 16 XY position monitor 17 Z sensor 19 Joule meter 20 Wafer 21 Semiconductor chip 22, 25 Protective film 23 Fuse 24 Insulating film 31 LED 32 Collimator lens Reference Signs List 33 parallel flat glass 34 condensing lens 35 two-segment detector 40 irradiation system 41 processing laser 42 attenuator 43 optical system 44, 62 beam splitter 50 observation system 51 illumination lamp 52, 63 half mirror 53 ITV camera 54 image processing unit 55 monitor 60 Alignment system 61 Alignment laser 64 Detection optical system 70, 80, 85 Main controller 71, 81, 86 Stage controller 72, 82, 87 Laser power controller Over La 73 alignment controller 74 the loader controller 75 input unit 76,83,88 control table

Claims (11)

[Claims] 1. A stage on which a workpiece is mounted, a laser irradiating means for irradiating a laser beam to a processing point of the workpiece mounted on the stage, and an energy of the laser light irradiating the processing point Energy setting means for setting a predetermined energy value, and changing the energy set by the energy setting means to a predetermined energy value in accordance with in-plane position information of the processing point in the workpiece. A laser processing apparatus comprising: 2. The laser processing apparatus according to claim 1, wherein a position of the processing point in an optical axis direction of the laser beam is measured, and the stage is moved in the optical axis direction based on a result of the measurement. By doing so, positioning means for positioning the processing point, offset setting means for setting an offset used for positioning the processing point to a predetermined offset value, and an offset set by the offset setting means, An offset changing unit for changing the offset value to a predetermined offset value according to the in-plane position information. 3. A stage on which a workpiece is mounted, a laser irradiating means for irradiating a laser beam to a processing point of the workpiece mounted on the stage, and the processing point in an optical axis direction of the laser light. Positioning means for positioning the processing point by measuring the position of the processing point and moving the stage in the optical axis direction based on the result of the measurement; and an offset used for positioning the processing point by a predetermined offset value. Offset setting means to be set, Offset set by the offset setting means, Offset change means to change to a predetermined offset value according to the in-plane position information of the processing point in the workpiece A laser processing apparatus comprising: 4. The laser processing apparatus according to claim 1, wherein the energy changing unit has an energy storage unit that stores the determined energy value of the processing point. Laser processing equipment. 5. The laser processing apparatus according to claim 2, wherein the offset changing unit has an offset storage unit that stores the determined offset value of the processing point. Laser processing equipment. 6. The laser processing apparatus according to claim 2, wherein the laser irradiation unit has an objective optical system that focuses the laser light, and the offset changing unit includes: A laser processing apparatus, wherein an offset is changed such that a position of the processing point in the optical axis direction coincides with a focal position of the objective optical system. 7. The laser processing apparatus according to claim 2, wherein the positioning unit emits a beam to the workpiece from a direction inclined with respect to the optical axis direction. A laser processing apparatus, comprising: a measuring unit for measuring a position of the processing point in the optical axis direction by detecting a beam reflected by the workpiece. 8. The laser processing apparatus according to claim 7, wherein the offset setting unit has a shift member that shifts the trajectory of the reflected beam when measuring the position of the positioning unit by the measurement unit. A laser processing apparatus, wherein an offset is set according to a shift amount of the track by a shift member. 9. The laser processing apparatus according to claim 1, wherein the laser irradiation unit has a light source unit that emits the laser light, and the energy setting unit includes the light source. A laser processing apparatus, comprising: an attenuating member that attenuates energy of a laser beam emitted from a part; and setting energy applied to the processing point according to an amount of energy attenuation by the attenuating member. 10. A laser irradiation step of irradiating a processing point of a workpiece placed on a stage with a laser beam, and prior to the laser irradiation step, the energy of the laser beam applied to the processing point is changed to a predetermined energy. Energy setting step to set a value, prior to the energy setting step, the energy set in the energy setting step, the predetermined energy according to the in-plane position information of the processing point in the workpiece And an energy changing step of changing the value to a value. 11. A laser irradiation step of irradiating a laser beam to a processing point of a workpiece placed on a stage; measuring a position of the processing point in an optical axis direction of the laser light; A positioning step of positioning the processing point by moving the stage in the optical axis direction based on the offset; and an offset setting for setting an offset used for positioning the processing point to a predetermined offset value prior to the positioning step. Prior to the offset setting step, an offset set in the offset setting step is changed to an offset value that is changed to a predetermined offset value according to in-plane position information of the processing point in the workpiece. And a laser processing method.