JP2593460B2 - Laser processing method and laser processing apparatus - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing method and a laser processing apparatus, and more particularly to laser processing in which a workpiece placed on a movable stage is processed by a laser beam. It is applied to the device.

[Conventional technology]

As this type of laser processing apparatus, for example, there is an apparatus that reprocesses a chip once processed by a laser beam in order to repair a defect of a memory chip on a semiconductor wafer. In this type of processing apparatus, it is required to align a wafer with a laser beam processing position with high speed and high accuracy.

However, in a conventional laser processing apparatus, as a method of positioning a workpiece to a processing position of a laser beam, first, a method of moving a stage on which a compound is mounted, and second, a method of moving a laser beam. Position the optical system (for example,
(A galvanometer mirror or the like).

[Problems to be solved by the invention]

The method of moving the first stage has the advantage that it can be positioned with high precision at the processing position of the laser beam. However, since the mass of the stage on which the workpiece is mounted and the driving mechanism thereof are considerably large, There is a problem that the matching speed cannot be increased so much.

Further, the second method of moving the laser beam has an advantage that the moving speed can be increased, but there is a problem that the positioning accuracy for positioning the laser beam at a predetermined processing position of the workpiece cannot be so high. .

An object of the present invention is to realize high speed and high accuracy when processing a workpiece by positioning the workpiece at a processing position of a laser beam.

[Means for solving the problem]

The first aspect of the present invention is to provide a laser beam output from a processing laser through a laser beam irradiating system to a required processing portion of a workpiece mounted on a movable stage. In the laser processing method of processing the required processing portion by irradiating the stage, the stage is moved to the irradiation position while the distance between the irradiation position of the laser beam and the required processing portion exceeds a predetermined value. By moving at a first speed, the required processing portion is brought closer to the irradiation position of the laser beam, and when the distance becomes equal to or less than the predetermined value, the stage is moved from the average value of the first speed. While continuing to move in the same direction at a slow second constant speed, the irradiation position of the laser beam is moved toward the required processing portion, so that when the distance becomes equal to or less than an allowable value, Start the irradiation of Zabimu to provide a laser processing method "for processing the main processing unit.

In this case, while the distance exceeds the predetermined value,
As the distance decreases, the first speed is gradually decreased toward a predetermined speed, and when the distance becomes equal to or less than the predetermined value, a second constant speed which is the same as or close to the predetermined speed is used. Preferably, the stage is moved.

Further, the present invention provides a processing laser for generating a laser beam, a stage on which a workpiece is placed and movable, and a drive control of the stage for bringing the required processing portion closer to the laser beam irradiation position. A stage drive control unit,
A laser beam irradiation system drive control unit that drives and controls the laser beam so as to approach the required processing portion, and the laser beam when the distance between the required processing portion and the laser beam irradiation position is equal to or less than an allowable value. In a laser processing apparatus including a laser drive control unit that supplies power for generating the processing laser to the processing laser, the stage drive control unit includes a target position corresponding to a position of the required processing portion and an irradiation position of the laser beam. A stage driving subtraction circuit that calculates a difference output corresponding to the distance between the input and the distances, compares a reference signal corresponding to a predetermined value and the difference output, and the difference output is based on the reference signal. A comparison circuit for outputting the signal L as a comparison output if the signal L is larger than the reference signal, and receiving the difference output and the comparison output, When the comparison output is a signal L, the difference output is transmitted, and when the comparison output is a signal H, the stage drive gate circuit for stopping the transmission of the difference output, and receiving a signal from the stage drive gate circuit, While the difference output is input, the input difference output is sent out while holding the difference output, and when the signal from the stage driving gate circuit is stopped, the last difference output held is output. A hold circuit for maintaining transmission, and receiving the difference output from the hold circuit, and while the difference output changes, sends out power having a first speed to drive the stage, and the difference output is A speed control circuit that drives the stage by sending power that becomes a second constant speed that is lower than the average value of the first speed when the speed becomes constant, and the laser beam irradiation system drive control unit includes: Receiving the comparison output and the difference output sent from the stage drive control unit, if the comparison output is a signal L, a predetermined reference position of the laser beam irradiation position is sent out, and if the comparison output is a signal H, For example, an irradiation system drive gate circuit that sends the difference output, and the reference position is sent when the reference position is input from the irradiation system drive gate circuit, and the difference output is sent from the irradiation system drive gate circuit. An irradiation system drive subtraction circuit for subtracting the difference output from the movement amount of the laser beam irradiation position from the reference position and outputting a subtraction value; and the reference position from the irradiation system drive subtraction circuit. Is input, the irradiation position of the laser beam is moved to the reference position. When the subtraction value is input from the irradiation system driving subtraction circuit, the laser beam is moved until the subtraction value becomes zero. A laser processing device comprising a laser beam drive circuit for moving a laser beam irradiation position.

[Action]

With the configuration as in the preceding invention, when the required processing portion PP is far away from the irradiation position of the processing laser beam LB,
By moving the stage 1 at high speed, the required processing portion PP can be quickly brought close to the vicinity of the irradiation position of the processing laser beam LB. Then, when the required processing part PP reaches the vicinity of the irradiation position of the processing laser beam LB, the processing laser beam LB is moved while moving the stage 1 at a constant minute speed.
To the required processing part PP. Thus, the required processing part PP
And the irradiation position of the processing laser beam LB can be aligned with high speed and high accuracy.

According to another aspect of the present invention, when the stage to be processed PP is positioned at the irradiation position of the laser beam LB by moving the stage 1 movable in both the X and Y axes directions, Although the movement of the stage 1 is stopped when the positioning is completed, the movement in the other direction is continued even when the positioning is completed, so that high-speed and high-accuracy laser processing can be realized.

〔Example〕

Referring to the drawings, an embodiment in which the present invention is applied to a semiconductor manufacturing apparatus will be described in detail.

In FIG. 1, reference numeral 1 denotes a wafer stage mounted on a base 2, which can be moved in X and Y directions by a wafer stage drive motor 3.

A wafer 4 is mounted on the upper surface of the wafer stage 1 as a workpiece by, for example, vacuum suction, and receives a processing laser beam LB irradiated from a laser beam irradiation system 5.

The laser beam irradiation system 5 includes an objective lens system, and is fixed to a laser beam stage 12 provided above a gantry 11 mounted on the base 2 so as to face the wafer stage 1 with the wafer 4 interposed therebetween. I have.

The laser beam LBX generated from the processing laser 13 is supplied to the laser beam irradiation system 5 after the power is adjusted by the beam power control unit 14. The laser beam LBX is then processed as a processing laser beam LB via the mirror 15 and the aperture 16. 5 is supplied. Since the aperture 16 and the wafer 4 have a conjugate relationship with respect to the laser beam irradiation system 5, the laser beam irradiation system 5 forms a processing laser beam LB formed into the opening shape of the aperture 16 on the wafer 4, and forms an image. The semiconductor wafer portion at the set position is processed.

The laser beam stage 12 holds the laser beam irradiation system 5 movably in the X and Y directions. On the other hand, the laser beam irradiation system 5
There is provided a laser beam driving device 20 for moving the laser beam in the X direction or the Y direction.

The laser beam driving device 20 has a bearing 21 sandwiched and held on the outer surface of the lens barrel of the laser beam irradiation system 5 as shown in the X-axis direction, for example. It has a configuration in which both ends are held from outside by a laser beam drive element 22 and a compression spring 23.
The laser beam driving element 22 is configured by, for example, a piezo element having one end fixed to the gantry 11. One end of the base 11
The bearing 21 is pressed onto the laser beam driving element 22 by a compression spring 23 fixed to the bearing 21.

Thus, when the laser beam driving element 22 expands and contracts in proportion to the supplied voltage, the laser beam irradiation system 5 becomes a compression spring.
The laser beam drive element 22 is moved in the X direction by an amount corresponding to the amount of compression and expansion of the laser beam drive element 22 by the urging force of the laser beam drive element 22.

Similarly, in the Y direction, the laser beam driving element
22 and a compression spring 23 are provided so that the laser beam irradiation system 5 can move in the Y-axis direction by an amount corresponding to the compression and expansion of the laser beam driving element 22.

Thus, in order to align a predetermined required processing portion PP on the wafer 4 with the processing laser beam LB, the wafer stage 1 is moved by the wafer stage driving motor 3 in the X direction and / or the Y direction.
A first method of moving in the direction of
By using one or both of the second method of moving the laser beam irradiation system 5 in the X direction and / or the Y direction by the laser beam driving element 22, the relative movement between the wafer 4 and the laser beam irradiation system 5 The position can be adjusted by changing the proper position.

FIG. 2 shows an objective lens 5a housed in the laser beam irradiation system 5 and a lens 11a fixed in the gantry 11, and both lenses constitute an infinite system. Objective lens
5a from the position of the solid line shown in FIG. 2, to the position of the dashed lines shown, when the moving distance X _1, and the beam position on the wafer 4 is moved by a distance X _1. Distance ray passing through the objective lens 5a when X ₁ is extremely small, considered almost passes the optical axis of the lens, thus not affected by the aberration of the lens.

 This relationship is the same in the Y-axis direction.

Under such conditions, the irradiation position on the XY plane irradiated from the laser beam irradiation system 5 and the position on the XY plane of the wafer 4 are measured by the interferometers 25 and 26, respectively.

The interferometer 25 for the laser beam irradiation system 5 has a parallel output beam emitted from the wavelength-stabilized measurement laser 31 fixed to the outer surface of the laser beam irradiation system 5 via beam splitters 32 and 33 sequentially. The light enters the detection mirror 34 and the reflected light is received by the beam splitter 33. At the same time, the interferometer 25
The output beam of the light enters the reference mirror 36 provided at the reference position of the gantry 11 via the beam splitters 32 and 33 and the mirror 35, and reflects the reflected light via the mirror 35 to the beam splitter 33.
It is configured to return to. In addition, beam splitter 33
The output side node of the laser beam irradiation system 5 is set so as to be located on an extension of the output beam reciprocating between the laser beam and the mirror 34. Accordingly, when the laser beam LB is displaced in the same direction on the wafer 4 as the beam irradiation system 5 is displaced in the direction orthogonal to the optical axis, the displacement amounts of the laser beam LB and the laser beam LB coincide with each other. The accuracy of displacement detection is improved.

Thus, from the beam splitter 33, an interference beam that causes interference between the reflected beam reflected from the reference mirror 36 and the reflected beam reflected from the detection mirror 34 is obtained. Incident on.
This interference beam is based on the difference between the position of the reference mirror 36 in the X direction and the position of the detection mirror 34 and thus the laser beam irradiation system 5 in the X direction. The brightness changes, and the photoelectric sensor 37 sends out a detection pulse DT1 corresponding to the feed amount from the photoelectric sensor 37 according to the change in brightness.

On the other hand, the interferometer 26 for detecting the position of the wafer 4 applies the output beam of the measuring laser 31 to the detection mirror 43 fixed to the side surface of the wafer stage 1 via the beam splitter 32, the mirror 41, and the beam splitter 42. The reflected light is incident on the beam splitter 42. At the same time, the output beam of the measuring laser 31 is changed to a beam splitter 32, a mirror 41,
A detection beam is incident on the reference mirror 36 via the beam splitter 42 and the mirror 44, and the reflected beam is reflected by the mirror.
It is configured to return to the beam splitter 42 via 44.

Thus, in the beam splitter 42, an interference beam due to the reflected beam from the detection mirror 43 and the reflected beam from the reference mirror 36 is formed, and the change in brightness of the interference beam is detected by the photoelectric sensor 45. The photoelectric sensor 45 generates a detection pulse DT2 corresponding to the detection mirror 43 relative to the reference position of the reference mirror 36, that is, the feed of the wafer 4.

Thus, the laser beam irradiation system 5 from the interferometers 25 and 26 to the reference position where the reference mirror 36 is provided.
And the detection pulses DT1 and DT2 corresponding to the movement amount of the wafer 4 and the movement amount of the wafer 4, respectively.
By controlling the drive control unit and the wafer stage drive control unit of the laser beam irradiation system 5 based on DT1 and DT2, respectively, the wafer 4 is positioned at the irradiation position of the processing laser beam LB.
The upper processed part can be aligned.

That is, the position of the processing laser beam LB when the laser beam irradiation system 5 is at the origin on the XY plane and the position of the reference mark formed on the wafer 4 on the XY plane
It is measured in advance by a wafer alignment measuring device provided in the processing apparatus shown in the figure. In addition, the positional relationship between the required processing portion PP on the wafer 4 and the reference mark formed on the wafer 4 is accurately measured in advance as a design value or a measurement result. Therefore, the required processing part PP on the wafer 4
Since the positional relationship between the laser beam LB and the processing laser beam LB on the XY plane is known in advance, distances in the X-axis direction and the Y-axis direction corresponding to the positional deviation are set as target values, and the target value is reached. Wafer 4 (hence wafer stage 1)
The positioning control may be performed by relatively sending the laser beam irradiation system 5 in the X direction and the Y direction.

Such positioning control is performed by a drive control device shown in FIG.
Performed by 51. Although FIG. 3 shows only the drive control system in the X direction, it is assumed that the drive control system in the Y axis direction has the same configuration.

The drive control unit 51 includes a laser beam irradiation system drive control unit 52 for the laser beam irradiation system 5, a wafer stage drive control unit 53 for the wafer stage 1, and a processing laser light source.
13 and a laser drive control unit 54.

In the wafer stage drive controller 53, a counter 55
Receives the detection pulse DT2 obtained from the photoelectric sensor 45, the stage 1 generates a count output X _C indicating whether a to which position on the current X-axis, and sends the subtraction input terminal of the subtracting circuit 56. The addition input terminal of the subtracting circuit 56 is input the target value X ₀ representing the feed amount in the X-axis direction, compare the difference between X _D1 = X ₀ -X _C ...... consisting of (5) subtraction output X _D1 Supply to circuit 57.

Thus, the subtraction output X _D1 obtained from the subtraction circuit 56,
As shown in FIG. 4A, a relative difference between a position of a processing laser beam LB at a reference position described later and a position of a required processing portion PP on the wafer 4 is shown. Difference X
_From the value X _D1 = X ₀ at the correction operation start time t = t ₀ , the count output X _C of the counter 55 increases and decreases as the value approaches the target value X _0. when X _C has reached the target value X _0, indicating that the alignment operation is completed it becomes the difference output X _D1 is 0.

Comparator circuit 57 compares the difference output X _D1 reference signal X ₁ and, when the content of the difference output X _D1 is greater than the content of the reference signal X _1, as shown in FIG. 4 (B), a logic "L" The comparison output COM1 that maintains the level is sent. Here, the reference signal X ₁ is switched from a mode of positioning by sending the wafer stage 1, ie, a wafer stage feed mode, to a mode of aligning by moving the laser beam irradiation system 5, ie, a laser beam irradiation system feed mode. The content of the difference output _{XD1 at} the timing
As shown, when the difference output X _D1 is smaller than the value X ₁ coming close to 0, is selected to a value that inverts the logic level of the comparison output COM1 of the comparator circuit 57 to "H" level ing. The comparison output COM1 is provided to the gate circuit 59 via the inverter 58.

When the positioning of the stage 1 and the laser beam irradiation system 5 in the Y-axis direction is completed, the gate circuit 59 also receives a Y-axis positioning completion signal Cy which is inverted to a logical "H" level.

The gate circuit 59 is controlled to be open regardless of the logical level of the Y-axis positioning completion signal Cy as long as the comparison output COM1 is at the logic “L” level, and the comparison output COM1 and the Y-axis positioning completion signal Cy
Are closed when both of them reach the logic "H" level.

When the gate circuit 59 is opened, the difference output _XD1 becomes the gate circuit 59,
It is supplied to the motor drive circuit 60 via the hold circuit 81, the D / A converter 79, and the speed control circuit 82, whereby the drive of the wafer stage drive motor 3 (FIG. 1) is continued.

While hold circuit 81 holds the difference output X _D1 from the gate circuit 59, as it is sent to the D / A converter 79, comparator output COM1, COM3 are both logic gate circuit 59 rises to the "H" level closing control If that difference is no longer come sent the output X _D1 is made to send a difference output X _D1 was held immediately before the D / a converter 79.

Differential output X _D1 of the subtracting circuit 56 is supplied to the addition input terminal of the subtracting circuit 62 through the gate circuit 61 of the laser beam irradiation system drive control unit 52.

The laser beam irradiation system drive control unit 52, a detection pulse DT1 of photoelectric sensors 37 and counted in the counter 63, and supplies the count output X _F to the subtracting input of subtractor circuit 62. Thus subtraction output X _D2 obtained at the output terminal of the subtracting circuit 62 D / A
It is provided to laser beam drive circuit 64 via converter 80. A laser beam driving circuit 64 at this time sends a drive output DR ₂ for the laser beam driving device 22 comprising a piezoelectric element. Count output X _F of this the counter 63, the laser beam irradiation system 5 until it matches the value of the addition input terminal is driven and controlled. Thus the difference between the output X _D1 of the subtraction circuit 56 is a fourth
Figure when it is mode switching level X ₁ of (A), the target value
The data of the relative difference remaining between X ₀ and the position X _{C of the} wafer 4, that is, X _D1 (= X ₁ ) is given to the subtraction circuit 62 as an addition input, so that the count output X _F of the counter 63 is obtained.
Is driven until the difference output X _D1 (≦ X ₁ ) matches the remaining difference output X _D1 (≦ X ₁ ).

The laser beam irradiation system drive control unit 52, in addition to the above configuration has a configuration where the reference position data of the reference position data generating circuit 71 is X _OR applied through gate circuit 72 to the adding input of subtractor circuit 62 . The comparison output COM1 of the comparison circuit 57 is given to the gate circuit 72 via an inverter 73 as an open control signal, whereby the gate circuit 72 operates in the opposite direction to the gate circuit 61.

Thus, while the comparison output COM1 is at logic "L" and the gate circuit 61 is closed, the gate circuit 72 is opened and the reference position data _XOR is supplied to the subtraction circuit 62. By driving the laser beam drive element 22 by the drive circuit 64, the irradiation position of the processing laser beam LB is brought to the reference position as the home position. In the case of this embodiment, the reference position data
X _OR is selected to be a value that causes the processing laser beam LB to irradiate the coordinate origin on the X axis. Thus, while the wafer stage drive control unit 53 aligns the wafer stage 1, the laser beam irradiation system drive control is performed. The part 52 positions the processing laser beam LB at a position where the origin on the X axis can be irradiated.

Subtraction output X _D2 of the subtracting circuit 62 is supplied to the comparison circuit 75 of the laser drive control unit 54. Comparison circuit 75, when the difference output X _D2 becomes the reference signal X ₂ smaller value to generate a logical comparison rises to "H" level output COM2 (FIG. 4 (C)), which gate circuit 76 Supply to input terminal. Here, the value of the reference signal X ₂ is preselected in the signal level representing the allowable range which can be regarded as the alignment on the X-axis of the stage 1 and the laser beam irradiation system 5 is completed.

The gate circuit 76 receives the aforementioned comparison outputs COM1 and COM2,
When the positioning between the stage 1 and the laser beam irradiation system 5 is completed on the X-axis and both comparison outputs COM1 and COM2 become logic "H" level, a logic "H" level X-axis direction positioning completion signal Cx is gated. Send to 77.

The gate circuit 77 is also supplied with the aforementioned Y-axis direction positioning completion signal Cy which becomes a logical “H” level when the positioning of the stage 1 and the laser beam irradiation system 5 is completed on the Y-axis. When the laser beam LB can be radiated and both the positioning signals Cx and Cy both reach the logical “H” level, the gate circuit 77 is opened. With this, the laser Q
The trigger output TRG of the switch trigger oscillator 78 is supplied to the processing laser 13. As a result, the processing laser 13 generates a laser beam LBX (FIG. 1) and irradiates the wafer 4 with the processing laser beam LB.

In the above configuration, at the time point t ₀ of FIG. 4, the positioning of the Y axis is already finished, the stage 1 and the beam irradiation system 5
Stop the displacement in the Y-axis direction, and therefore, it is assumed that the Y-axis direction positioning completion signal Cy at the logical "H" level has been input to the gate circuits 59 and 77. Further, at this time, the processing laser beam LBX is in the position of the origin 0 on the X axis, and a main processing part PP of the wafer 4 is in the position of the target value X _0, the wafer stage drive control unit 53 from this state drive control Start operation. That is, at time t ₀ , wafer stage 1
In a state where but not started operation, the still detection pulse DT2 from the photoelectric sensor 45 is not transmitted, the count output X _C of the counter 55 is zero, thus the difference in the subtraction circuit 56 outputs X
_D1 is the target value X _0, and has a larger say than the reference signal X ₁ of the comparator circuit 57. Therefore, the comparison output CO of the comparison circuit 57
M1 is at the logic "L" level, and therefore the gate circuits 59, 72
Are opened and the gate circuits 61 and 76 are closed.

As a result, the difference output X _D1 from the subtraction circuit 56, the gate circuit 59, via a hold circuit 81 is converted into an analog signal by a D / A converter 79 is added to the speed control circuit 82.
The speed control circuit 82 generates a speed control signal corresponding to the analog signal and sends it to the motor drive circuit 60. The motor drive circuit 60, a driving output DR ₁ that amplifies the speed control signal generated is sent to the wafer stage drive motor 3. As a result, the drive motor 3 is started, and the required processing portion PP of the wafer 4 starts moving toward a point where the processing laser beam LB can be irradiated, that is, toward the origin 0 on the X axis. Eventually detection pulse DT2 from the photoelectric sensor 45 representing the amount of movement of the main processing part PP is generated, thereby counting an output X _C of the counter 55 is gradually increased,
As a result, the difference output _XD1 decreases toward zero. Speed control circuit 82, while the stage drive motor 3 is rotating, receives a speed signal indicative of the rotational speed of the motor 3 from the tachogenerator built in the drive motor 3, the speed control signal generated on the basis of the difference between the output X _D1 And this speed signal is controlled. This speed control signal is a signal that tends to drive the motor 3, that is, the stage 1, at a lower speed as the distance difference indicated by the difference output XD ₁ becomes smaller, and finally stops the stage 1 when the distance difference disappears.

Thus, the position of the required processing portion PP of the wafer 4 approaches the irradiation position of the processing laser beam LB together with the wafer stage 1. In this operation mode, the reference position data generation circuit 71 is added to the subtraction circuit 62 of the laser beam irradiation system drive control unit 52.
Of is given a reference position data X _OR, counter 63 with respect to the origin position on the X-axis represented by the reference position data X _OR
As values match, the drive output DR ₂ is given to the laser beam driving device 22 from the laser beam driving circuit 64, the working laser beam LB maintains a state capable of irradiating the origin.

At time t ₁ of FIG. 4 (A) Then, when the difference output X _D1 becomes the reference signal X ₁ value less than the comparison output COM1 of the comparator circuit 57 rises to a logic "H" level (FIG. 4 (B) ). As a result, the gate circuits 59 and 72 are controlled to be closed,
The gate circuit 61 is controlled to open.

Therefore, the hold circuit 81 outputs the difference output held immediately before.
X _D1 is sent to D / A converter 79, and as a result
Drive output DR for wafer stage drive motor 3 after t _1
1 is switched to a constant voltage, and the position of the required processing portion PP of the wafer 4 moves at a constant minute speed. This speed is set to a value that allows the laser beam irradiation system 5 driven as described later to sufficiently follow the movement of the required processing portion PP.

On the other hand, the subtraction circuit 62 of the laser beam irradiation system drive control unit 52, in place of the reference position data X _OR, differential output X _D1 of the subtraction circuit 56 is switched to a state given through the gate circuit 61. Differential output X _D2 resulting subtraction circuit 62, it to the irradiation position of the processing laser beam LB (i.e. the origin), abruptly changes to a value corresponding to the difference between the value of the difference output X _D1 of the subtracting circuit 56 This driving output DR ₂ from the laser beam driving circuit 64 for the laser beam driving device 22 is sent by.
Thus the position of the laser beam LB can be irradiated, starts to move toward the time t ₁ to the position of the main processing unit PP, detected by the detection pulse DT1 generated the movement amount from the photoelectric sensor 37, thereby the counter 63 count output X _F is gradually increased, the value of the difference output X _D2 becomes smaller.

Eventually at time t _2, when the difference between the output X _D2 of the subtraction circuit 62 is smaller than the reference signal X ₂ of the comparison circuit 75, the comparison output COM2 of the comparison circuit 75 rises to a logic "H" level (FIG. 4 (C)) . The change of the comparison output COM2 is given to the gate circuit 77 through the gate circuit 76. At this time, since the logic “H” level Y-axis direction positioning completion signal Cy has already been applied to the gate circuit 77, the gate circuit 77 is controlled to open, and processing is performed based on the trigger output TRG of the laser Q trigger oscillator 78. driving output DR ₃ is sent to the laser 13.

As a result, the processing laser beam LB is irradiated onto the wafer 4. Position of the processing laser beam LB in this case is entered into the laser irradiation tolerance range, represented by the reference signal X _2, thus main processing part PP of the wafer 4 is processed by the processing laser beam LB.

At time t ₃ the process is finished, one main processing unit
Processing work for the PP is completed, the 'target value X ₀ to specify the location of' (Y-axis direction of the value the value of the target position input X ₀ have the following main processing part PP of the wafer stage drive control unit 53 changes To be not included). At this time, the difference output between the target position input X ₀ ′ and the counter output X _C indicating the current position of the stage 1 is output.
X _D1 is greater than the reference signal X _1, new by comparison output COM1 changes to logic "L" level, the time t ₀ and the operation as well as the motor driving circuit 60 between t ₁ of the comparison circuit 57 Positioning for the target position X ₀ ′ starts.

Also, since the comparison output COM1 is at logic "L", the gate circuit
While the closing operation of 61 is performed, the gate circuit 72 opens, and the reference position data _XOR is supplied to the subtracting circuit 62. As a result, the laser beam driving element 22 is
To start the operation of returning the irradiation position of the processing laser beam LB to the home position as the home position.

Led to time t _4, the difference output X _D1 is below the reference signal X _1, and the laser beam irradiation system drive control unit 52 and wafer stage drive control unit 53, the same operation as the period from the time point t _1, t ₂ Let it start. That is, the rising comparison output COM1 of the comparator circuit 57 at time t ₄ is the logic "H" level (FIG. 4 (B)), thereby the gate circuit 59,72 is controlled closed,
The gate circuit 61 is controlled to open.

Thus, in the wafer stage control unit 53, the hold circuit 81, a difference output X _D1 was held immediately before the D / A converter
Will be sent to 79, thereafter driving the output DR ₁ to the wafer stage driving motor 3 is switched to a constant voltage, the position of the main processing unit PP 'of the wafer 4 is moved at a constant small rate. On the other hand, the subtraction circuit 62 of the laser beam irradiation system drive control unit 52
To switch to their respective positions differential output X _D1 of the subtracting circuit 56 is supplied through the gate circuit 61. Differential output X _D2 resulting subtraction circuit 62 corresponds to the difference between the irradiation position of the processing laser beam LB indicated by the counter X _F at time t _4, the value of the difference output X _D1 of the subtraction circuit 56 (i.e., X ₁₎ It changes abruptly to a value, which drives the output DR ₂ corresponding to is sent from the laser beam driving circuit 62. Thus the position of the laser beam LB can be irradiated, starts to move toward the position of the main processing unit PP 'from the time t _4.

At time t ₅ eventually, the difference output X _D2 of the subtraction circuit 62 is smaller than the reference signal X ₂ of the comparison circuit 75, the comparison output COM2 of the comparison circuit 75 rises to a logic "H" level (FIG. 4 (C)) . The change in the comparison output COM2 is given to the gate circuit 77 via the gate circuit 76, and the gate circuit 77 is controlled to open the gate circuit 77, whereby the drive output DR ₃ for the processing laser 13 is output based on the trigger output TRG of the laser Q trigger oscillator 78. Is sent, and the processing laser beam LB is processed on the wafer 4 at the required processing portion PP ′.
Is irradiated.

At time t ₆ this process is completed, 'machining operation is completed with respect, followed by the target position input X ₀ of the wafer stage drive control unit 53' main processing unit PP value of the position of the next main processing part PP " The specified target value X ₀ ″ is changed, and the same operation as described above is performed. However, the difference between the output X _D1 between the counter output X _C representing the current position of the target position input X ₀ "and stage 1, the reference signal X
Is smaller than _1, the laser beam irradiation system 5, without performing a home position return operation as performed between the time t ₃ of t _4, starts to move immediately towards the main processing unit PP ".

Incidentally, In the above embodiments, decreasing the distance between the stage 1 and the laser beam irradiation position, the moving speed of the stage 1 from the difference output X _D1 becomes the reference signal X ₁ value less than the speed at that time Although fixed, the present invention is not limited to this, and multi-illumination may be increased or decreased as long as the laser beam irradiation system 5 can follow the movement of the required processing portion PP at a constant speed. However the average speed of the stage 1 to the difference between the output X _D1 becomes the reference signal X ₁ value less than, i.e. the average speed of the stage 1 from time t ₀ to t ₁ is faster than the subsequent constant rate of speed This is a necessary condition to obtain the effect.

In the above embodiment, when the positioning in the Y-axis direction is completed earlier than in the X-axis direction, that is, before the X-axis positioning signal Cx, the Y-axis positioning completion signal Cy is set to the logic “H” level. In the opposite case, the positioning signal Cx is generated, the stage 1 and the beam irradiation system 5 stop displacing in the X-axis direction, and the position
After the distance between the position in the axial direction and the position in the Y-axis direction of the beam irradiation system 5 approaches within a predetermined range, the stage 1 is displaced at a constant minute speed in the Y-axis direction, and the laser beam is generated along with the generation of the positioning signal Cy. LB will be irradiated to the required processing part.

According to the configuration of the above-described embodiment, when the difference between the required processing portion PP and the irradiation position of the processing laser beam LB is large, the required processing portion PP of the wafer 4 is moved by driving the wafer stage 1 at a high speed. When the position of the required processing portion PP comes close to the position near the processing laser beam LB as a result, the processing laser beam is moved while the wafer stage 1 is moved at a constant minute speed and constant speed.
By switching to the operation mode in which the LB is moved, long distance movement can be performed with high accuracy by moving the wafer stage, and the response speed is relatively fast when performing minute positioning. By moving the position of the laser beam LB using the laser beam driving element 22, it is possible to position the laser beam LB on the required processing portion PP at a high speed.

In addition, since the driving range of the laser beam driving element 22 can be set sufficiently small, an element suitable for operating the narrow range with high accuracy can be selected as the laser beam driving element 22. Positioning to the processing part PP can be performed with sufficiently high precision for practical use.

Further, since the stage 3 is driven continuously, when a plurality of required processing parts PP and PP 'on the same wafer 4 are continuously processed, one required processing part PP is replaced with another required processing part PP. ′
Since no useless time is spent when moving to the position, high-speed positioning can be performed.

In the above description, the case where the present invention is applied to wafer repair has been described. However, the present invention is not limited to this, and can be generally applied to a case where a predetermined position on a workpiece is laser-processed.

〔The invention's effect〕

As described above, according to the present invention, while the distance between the required processing part PP processing part and the processing laser beam is large, the stage on which the workpiece is mounted is driven by driving the required processing part side. By using the mechanism, it is possible to approach the target position at high speed. At the same time, when the distance between the required processing portion and the processing laser beam becomes sufficiently small, the laser beam irradiation system is driven while driving the required processing portion side at a constant minute speed, so that the position of the required processing portion is reduced. The processing laser beam can be positioned with high speed and high accuracy.

According to yet another aspect of the present invention, when the stage to be processed is positioned at the irradiation position of the laser beam by moving the stage movable in both the X and Y axes, the movement of the stage in the direction in which the positioning has been completed first is not performed. Although it stops when completed, the movement in the other direction is continued even when the positioning is completed, so that high-speed and high-accuracy laser processing can be realized.

Either invention can easily realize high-speed and high-accuracy positioning in laser beam processing.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a mechanical structure of a laser processing apparatus according to the present invention, FIG. 2 is a schematic diagram showing a movement state of a laser beam irradiation position when a laser beam irradiation system is moved,
FIG. 3 is a block diagram showing a drive control device for controlling FIG. 1, and FIG. 4 is a time chart for explaining a positioning operation. DESCRIPTION OF SYMBOLS 1 ... Wafer stage, 2 ... Base 3, ... Wafer stage drive motor, 4 ... Wafer, 5 ... Laser beam irradiation system, 11 ... Stand, 12 ... Laser beam stage, 13
…… Processing laser, 14 …… Beam power control unit, 20 ……
Laser beam driving device, 21 bearing, 22 laser beam driving element, 23 compression spring, 25 laser beam irradiation system position detection interferometer, 26 wafer stage position detection interferometer, 31 ... Measurement laser, 51... Drive controller, 52... Laser beam irradiation system drive controller, 53... Wafer stage drive controller, 54... Laser drive controller.

Claims (3)

(57) [Claims] A laser beam output from a processing laser is directed to a required processing portion of a workpiece placed on a movable stage through a laser beam irradiation system. In the laser processing method of processing the required processing portion by irradiating the stage, while the distance between the irradiation position of the laser beam and the required processing portion exceeds a predetermined value, the stage is directed to the irradiation position By moving at a first speed, the required processing portion is brought closer to the irradiation position of the laser beam, and when the distance becomes equal to or less than the predetermined value, the stage is moved to a second speed lower than an average value of the first speed. The laser beam irradiation position is moved toward the required processing portion while the laser beam is continuously moved in the same direction at a constant speed, so that when the distance becomes equal to or less than an allowable value, the laser beam is irradiated. Laser processing method for processing the main processing unit to start the irradiation of the beam. 2. While the distance is above the predetermined value,
As the distance decreases, the first speed is gradually decreased toward a predetermined speed, and when the distance becomes equal to or less than the predetermined value, the first speed is reduced to a second constant speed which is the same as or close to the predetermined speed. Along with moving the stage, the irradiation position of the laser beam is moved toward the required processing portion, whereby, when the distance becomes equal to or less than an allowable value, the irradiation of the laser beam is started. The laser processing method according to claim 1, wherein: 3. A processing laser for generating a laser beam, a stage on which a workpiece is mounted and movable, and a stage for driving and controlling the stage so as to bring the required processing portion closer to the irradiation position of the laser beam. A drive control unit, a laser beam irradiation system drive control unit that performs drive control to bring the laser beam closer to the processing-needed part, and when a distance between the processing-needed part and the laser beam irradiation position is equal to or less than an allowable value. In a laser processing apparatus comprising a laser drive control unit for supplying power for generating the laser beam to the processing laser, the stage drive control unit includes a target position corresponding to a position of the required processing unit and the laser. A stage driving subtraction circuit for calculating a difference output corresponding to the distance between the beam irradiation positions which are inputted, and a predetermined predetermined value. A comparison circuit that compares a corresponding reference signal with the difference output, and outputs a signal L as a comparison output if the difference output is greater than the reference signal, and a signal H if the difference output is less than or equal to the reference signal; And the comparison output is received. If the comparison output is a signal L, the difference output is sent out, and the comparison output is a signal H
Then, a stage driving gate circuit for stopping the transmission of the difference output, and receiving a signal from the stage driving gate circuit, while the difference output is input, the difference output is held and input. A hold circuit that sends out the difference output, and maintains the last difference output held when the signal from the stage drive gate circuit is stopped; and receiving the difference output from the hold circuit. While the difference output is changing, the stage is driven by sending the power at the first speed, and when the difference output is constant, the power becomes the second constant speed lower than the average value of the first speed. And a speed control circuit for driving the stage to transmit the laser beam irradiation system, the laser beam irradiation system drive control unit, the comparison output and the difference output sent from the stage drive control unit An irradiation system driving gate circuit for transmitting a predetermined reference position of the laser beam irradiation position when the comparison output is a signal L, and transmitting the difference output when the comparison output is a signal H; When the reference position is input from the system drive gate circuit, the reference position is sent out, and when the difference output is input from the irradiation system drive gate circuit, the movement amount of the laser beam irradiation position from the reference position And an irradiation system driving subtraction circuit that subtracts the difference output and the difference output to output a subtraction value, and moves the irradiation position of the laser beam to the reference position when the reference position is input from the irradiation system driving subtraction circuit. And a laser beam driving circuit for moving the laser beam irradiation position until the subtraction value becomes zero when the subtraction value is inputted from the irradiation system driving subtraction circuit. Laser processing equipment.