JPH11245060A - Laser processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser processing device which is capable of continuing a processing even when an output power of a laser beam is reduced or stopped. SOLUTION: This is referred to a laser processing device to carry out a processing of a fuse being 'a part to be processed' by irradiating a semi-conductor device 23 mounted on a stage 24 as 'an object to be processed' with the plural laser beams. The device has the first, second light-receiptive parts 21, 22 as 'the detective units' to detect when each of the above laser beam output is lowered below a reference value, and a main controller being 'a controller' to control a relative movement of the semi-conductor device 23 and the other laser beam upon receipt of signals from the first, second light-receiptive parts 21, 22 so that a fuse originally scheduled to be processed with the laser beam, output power of which is lowered below the reference value, is processed with the other laser beam.

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 for processing a workpiece by irradiating a workpiece mounted on a stage with a plurality of laser beams, and in particular, reducing the output of a laser beam. The present invention relates to a laser processing apparatus capable of continuing processing even when the processing is performed.

[0002]

2. Description of the Related Art Conventionally, as this type of laser processing apparatus, for example, there is an apparatus for processing a fuse in a semiconductor device.

In some cases, a semiconductor device is provided with a wiring portion called a fuse, which is intended to cut a laser beam. For example, in a DRAM, a fuse is attached to each memory cell column at the time of design / manufacture, and a spare memory cell column is arranged. The cell column is isolated in the device, and the spare memory cell column is replaced with the spare column by cutting a fuse for designating the address of the defective column, thereby improving the yield of the DRAM. In a gate array, a part of a fuse in a circuit called a program link is cut,
By leaving a part selectively, a specific program is built in a device. The former is called laser repair, and the latter is called laser trimming.

A fuse in such a semiconductor device is generally formed of a thin line made of polysilicon or aluminum (width 0.8 to 1.5 μm, thickness 0.3 to 1.0 μm,
The length of the cut portion is 3 to 10 μm). This fuse has Y
A laser beam from a processing laser light source such as an AG laser is focused and irradiated, and the material constituting the fuse is heated and evaporated by light energy to remove the fuse, thereby cutting the fuse. The fuse is usually made of a transparent SiO ₂ film (0.
2 to 0.5 μm).

As for the position data of the fuse to be blown, data from a tester, which is another device for inspecting a defective portion, is input to a laser repair device via a medium such as online communication or FD. In a laser repair apparatus, a semiconductor device is placed on an XY table and positioned, and the fuses are sequentially cut while automatically adjusting the position of the fuse to be cut to the focal point of the laser beam.

By the way, in recent years, with high integration of memories,
The number of fuses for memory cell rescue has increased dramatically, the number of fuses to be processed has become enormous, and the area occupied by the rescue fuses for high integration has been demanded, and the fuse pitch tends to be narrowed.

However, there is a limit in increasing the oscillation frequency (about several kHz) of the processing laser while maintaining the energy required for processing, and it is necessary to increase the moving speed between the fuses specified by the frequency more than the current level. Because it ’s difficult
The cutting capability of the laser processing apparatus is naturally limited.

[0008] Therefore, there has been proposed an apparatus which performs processing using two laser beams to solve such a problem. For example, as shown in FIG. 3, the stage on which the semiconductor device is mounted is moved in the direction of the arrow (the X-axis direction), and on the semiconductor device, the stage is parallel at a certain interval. A plurality of fuses 1 are respectively arranged on two lines P1 and P2. And
The first laser beam cuts (processes) the fuse 1 at the processing point indicated by "x" in the figure, and the second laser beam cuts (processes) the fuse 1 at the processing point indicated by "o" in the figure. I am trying to do it.

[0009]

However, since two different laser beams are used to machine different fuses 1 respectively assigned to the two laser beams, if one of the laser beams fails to output due to a failure or stops. Is designed to stop processing by the other normal laser beam and repair the light source of the one laser beam, etc. During that time, processing has to be stopped, so it takes a lot of time to process There was a problem.

Therefore, an object of the present invention is to provide a laser processing apparatus capable of continuing processing even when the output of a certain laser beam is reduced or stopped.

[0011]

In view of such a problem, the invention described in claim 1 irradiates a plurality of laser beams to a workpiece mounted on a stage to process a workpiece. In the laser processing apparatus to be performed, a detecting means for detecting that the output of each of the laser beams has dropped below a reference value, and a signal from the detecting means, which is to be processed with the laser beam having dropped below the reference value. A laser processing apparatus having a controller for controlling the relative movement between the workpiece and the other laser beam so that the existing workpiece is processed by another laser beam.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, a plurality of the processing portions are arranged on a plurality of parallel lines at a certain interval, and each of the laser beams is The apparatus is set to scan on the plurality of different lines.

According to a third aspect of the present invention, in addition to the configuration of the first or second aspect, the processed portion is a fuse disposed on a semiconductor device.

[0014]

Embodiments of the present invention will be described below.

1 and 2 show an embodiment of the present invention.

First, the structure will be described. As shown in FIG.
First and second laser light sources 11 and 12 such as YAG lasers
These laser light sources 11 and 12 are independently oscillated at arbitrary timings by a trigger issued from a main controller 13 as a “controller” via a stage controller 14. The power sources of the laser light sources 11 and 12 are not shown.

The laser light emitted from each of the first and second laser light sources 11 and 12 is applied to a first laser optical system 15 respectively.
The first and second optical systems for laser 15 and 16 are connected to a laser power controller 17, which controls the energy value of the processing laser. And the beam size of the processing laser beam is controlled.

The first and second laser optical systems 15, 16
Are incident on the first and second reflecting mirrors 18 and 19, respectively. Most of the laser light is reflected downward by the first and second reflecting mirrors 18 and 19 and is incident on the objective lens 20. And a part of the laser light is
The light passes through the reflection mirrors 18 and 19 and enters the first and second light receiving sections 21 and 22 as “detecting means”.
It is connected to the.

The first and second reflection mirrors 18, 1
Reference numeral 9 is set so that the optical axes of the laser beams are parallel.

The laser beam incident on the objective lens 20 passes through the objective lens 20 and is condensed.
The beam becomes a spot beam and is radiated to the fuse 23a, which is a “working part” of the semiconductor device 23 as a “workpiece”. The beam diameter of both spot beams is about 5 μm.

The semiconductor device 23 is mounted on a stage 24 via a chuck (not shown). The stage 24 moves in two directions, XY and up and down, and rotates about the up and down direction. The actuator 26 is driven in a predetermined direction by a stage actuator 26 in response to a command from the stage controller 14. At this time, the position of the stage 24 is detected by the position monitor 27.

Further, in addition to the first and second laser light sources 15 and 16 for processing, an alignment laser light source 28 which is a helium-neon laser for positioning the semiconductor device 23 is separately provided. The alignment laser light emitted from the alignment laser light source 28 passes through an alignment optical system 29 and passes through the objective lens 20.
And is projected on the semiconductor device 23. The alignment optical system 29 is connected to the main controller 13 via the alignment controller 30.
It is connected to the. Thereby, the position between the fuses 23a in the semiconductor device 23 is measured, the offset amount between the alignment laser and the processing laser is measured, and the position information obtained from the alignment laser and the offset amount are corrected to perform the processing. To be done.

Further, a loader controller 31 for transferring semiconductor devices is provided between a storage case (not shown) and the stage 24, and the loader controller 31 is also connected to the main controller 13 and controlled. ing.

The main controller 13 detects from the signals from the first and second light receiving sections 21 and 22 that the output of each of the laser beams has dropped below a reference value, and one of the laser beams is turned off. When it is lower than the reference value, the stage controller 14 and the laser power controller 17 are controlled so that the fuse 23a to be processed by this laser beam is processed by another laser beam. The semiconductor device 23 and the other laser beam are relatively moved.

Further, as shown in FIG. 2, the semiconductor device 2 is moved along an arrow direction (X-axis direction) which is a moving direction of the stage 24 on which the semiconductor device 23 is mounted.
3, two parallel lines P1 and P2 at a certain interval
A plurality of fuses 23a are arranged on the (virtual line). Then, two laser beams scan on the two lines P1 and P2, and an arbitrary portion of the fuse 23a arranged on the lines P1 and P2 is cut.

Next, the operation will be described.

The first and second laser beams emitted from the first and second laser light sources 11 and 12 are controlled to predetermined processing energy values and beam sizes by first and second laser optical systems 15 and 16, respectively. Is done. The laser beams passing through the first and second laser optical systems 15 and 16 are the first and second optical systems.
Most of the laser light is incident on the second reflecting mirrors 18 and 19, is reflected downward by the first and second reflecting mirrors 18 and 19, and is incident on the objective lens 20, and a part of the laser light is reflected on the second reflecting mirror 18 and 19. 1, through the second reflecting mirrors 18 and 19,
The light enters the second light receiving units 21 and 22.

Then, an arbitrary fuse 23a is cut by each laser beam focused by the objective lens 20.

On the other hand, a part of the laser beam is incident on the first and second light receiving sections 21 and 22, and signals from the first and second light receiving sections 21 and 22 are input to the main controller 13. It is detected whether the output of each laser beam has dropped below the reference value.

In FIG. 2, in the area A, the outputs of both laser beams are not lower than the reference value, are normal, and the first
The first laser beam from the laser light source 11 causes the fuse 23a at the processing point indicated by "x" in the figure to
With the second laser beam from No. 2, the fuse 23a at the processing point indicated by “○” in the figure is normally cut.

Thereafter, when the second light receiving section 22 detects that the output of the second laser beam has dropped below the reference value in the area B in the figure, the main controller 13 is operated without stopping the entire apparatus. Thus, the moving direction of the stage 24, the oscillation pulse of the first laser beam, and the like are controlled, and the first laser beam as this "other laser beam" is indicated by "x" in the upper region C of the figure. Working point fuse 23
a is disconnected. Next, the first laser beam moves the stage 24 from the right end of the line P1 to the right end of the line P2 by moving the stage 24 in the Y direction (upward in the figure) as shown by the arrow, and then moves the stage 24 to the X direction. By moving the line P2 in the left direction by moving the line P2 in the right direction in the drawing,
On this line P2, the fuse 23a at the processing point indicated by “x” in the area C is cut. On this line P2, the fuse 23a at the processing point indicated by "x" in the area C in the drawing is "the part to be processed which was to be processed by the laser beam lower than the reference value".

As described above, the outputs of the two laser beams are constantly monitored, and if the processing of the fuse 23a cannot be performed by the one laser beam due to the failure of one of the laser light sources 11 or 12, an automatic operation is performed. By controlling the other laser beam, the fuse 23a originally intended to be processed by the one laser beam is processed by the other laser beam.

[0033] Therefore, when this change is made automatically, it is possible to minimize the hearing when the device is stopped due to a failure.

When this change occurs, the operator is notified. In addition, it is possible to select whether or not to make the change automatically.

In the above-described embodiment, the processing is performed by two laser beams. However, it is needless to say that three or more laser beams may be used, and the "processed portion" is limited to the fuse of the semiconductor device. Not something. In addition, the first and second light receiving units 21 and 22 are used as the “detection unit”, but the present invention is not limited to this, and the first and second laser optical systems 15 and
16 may be provided with a sensor for detecting the output of each laser beam.

[0036]

As described above, according to the inventions described in the claims, the outputs of a plurality of laser beams are constantly monitored, and when a laser light source or the like fails, the laser beam is processed by the laser beam. When the processing of the part becomes impossible, by automatically controlling the other laser beam, the part to be processed originally intended to be processed by the certain laser beam is replaced by the other laser beam. By processing, it is possible to minimize the hearing when the apparatus is stopped due to a failure, thereby improving the processing performance.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing an overall configuration of a laser processing apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a case where a fuse of a semiconductor device is cut using the laser processing apparatus according to the embodiment;

FIG. 3 is an explanatory diagram showing a case where a fuse of a semiconductor device is cut using a conventional laser processing apparatus.

[Explanation of symbols]

 11 First laser light source 12 Second laser light source 13 Main controller (controller) 15 First laser optical system 16 Second laser optical system 20 Objective lens 21 First light receiving section (detection means) 22 Second light receiving section (detection means) ) 23 Semiconductor device (workpiece) 23a Fuse (workpiece part) 24 Stage P1, P2 Plural parallel wires at a certain interval

Claims (3)

[Claims] 1. A laser processing apparatus for processing a portion to be processed by irradiating a plurality of laser beams to a workpiece mounted on a stage, wherein an output of each laser beam is reduced below a reference value. A detecting means for detecting, and a signal to be processed from the detecting means, wherein the portion to be processed, which was to be processed by a laser beam lower than the reference value, is processed by another laser beam. A laser processing apparatus comprising: a controller that controls a relative movement between an object and the another laser beam. 2. The method according to claim 1, wherein the plurality of processing portions are arranged on a plurality of parallel lines at a certain interval, and each of the laser beams is set to scan on the plurality of different lines. The laser processing apparatus according to claim 1. 3. The laser processing apparatus according to claim 1, wherein the portion to be processed is a fuse disposed on a semiconductor device.