JPH10156560A - Laser marking device and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a satisfactory machining depth and also to improve machining speed. SOLUTION: This device is such that, in the process of forming a dot by emitting a Q-switch laser beam in plural times to one place on an object to be machined, the Q-switch element 4 is controlled by the controller 2 in accordance with a machining program stored preliminarily in a memory 1. Then, the oscillation frequency of the Q-switch laser beam outputted by a resonator 3 is converted from the first frequency to the second frequency that is higher than the first.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a laser marking apparatus and method, and more particularly, to a laser marking apparatus and method for marking a desired pattern by forming dots on a wafer using a Q-switched laser beam.

[0002]

2. Description of the Related Art When a dot is formed on a silicon wafer using a Q-switch laser beam to perform a desired marking,
Generally, in order to form one dot, the same spot on a wafer is irradiated with laser light a plurality of times.

Conventionally, in this type of laser marking apparatus, dots are formed on a wafer with the oscillation frequency kept constant.

[0004]

When dots are formed on a silicon wafer by a Q-switch laser beam, the state of the wafer, for example, thermal conductivity and absorptivity, change every moment. However, in the conventional laser marking device, the marking is performed with the Q-switched laser beam having the same oscillation frequency despite such a change in the state. Processing cannot be performed. Therefore, there is a problem that marking cannot be performed with a sufficient processing depth and processing speed.

[0005]

In order to solve the above-mentioned problems, a laser marking apparatus of the present invention forms one dot by irradiating a spot on a workpiece with a Q-switch laser beam a plurality of times. A laser marking device, comprising: means for changing the oscillation frequency of the Q-switched laser light from a first frequency to a second frequency higher than the first frequency in the process of forming the one dot.

[0006] The laser marking method of the present invention comprises:
A laser marking method for irradiating a single point on a workpiece with a Q-switch laser beam a plurality of times to form one dot, wherein in the process of forming the one dot, the oscillation frequency of the Q-switch laser beam is changed. The first frequency is changed to a second frequency higher than the first frequency.

[0007]

Next, an embodiment of the present invention will be described in detail with reference to the drawings.

In the present embodiment, one dot is formed by irradiating a Q-switch laser beam to a spot on a wafer a plurality of times, and the dot thus formed is moved while moving the laser beam irradiation position. A plurality of dots are formed, and a desired pattern is drawn on the wafer by a combination of the plurality of dots.

Then, while one dot is formed by irradiating the Q-switch laser beam a plurality of times, the oscillation frequency of the Q-switch laser beam is changed from a low frequency to a high frequency as shown in FIG. 1 or FIG. Let me.

That is, in the process of forming one dot, first, as an initial step, the oscillation frequency of the Q-switched laser light is set to a low frequency such as 1 KHz or less, and the pulse width is narrow and the Q value is high. The switch laser light is irradiated on the wafer. Then, in the final step of dot formation, the oscillation frequency of the Q-switched laser light is set to a high frequency such as 2 to 10 KHz, the pulse width is wider than in the initial step, and the peak value is increased in the initial step. The wafer is irradiated with a Q-switched laser beam which is lower than the time. In an intermediate step from the initial step to the final step, as shown in FIG. 1, the oscillation frequency of the Q-switched laser light is changed stepwise from a low setting to a high setting, or as shown in FIG. The oscillation frequency is gradually changed from a low setting to a high setting.

As shown in FIG. 3, in an initial step, Q
By setting the oscillation frequency of the switch laser light low and using a Q-switch laser light with a narrow pulse width and a high peak value, the narrow range on the surface of the silicon wafer can be instantaneously and deeply as deep as possible. The heat diffusion can be spread.

In addition, as shown in FIG. 4, in the intermediate step, by increasing the pulse width and lowering the peak value, the dots formed in the initial step can be maintained in the horizontal direction while maintaining the thermal diffusion in the depth direction. Spread heat diffusion in the direction.

In the final step, the oscillation of the Q-switched laser beam is set to be high, and the pulse width is wider and the Q-switched laser beam having a lower peak value is used. Since it is smaller than the Q-switch laser light in the process, when forming a plurality of dots, uniform and stable dots can be formed.

When one dot is formed by irradiating 200 shots of a Q-switch laser beam on a mirror-polished surface of a silicon wafer, the oscillation frequency of the laser beam is
For example, the control is performed as shown in FIG. That is,
In the initial step of dot formation, a laser beam having an oscillation frequency of 1 KHz is irradiated for two shots to spread heat diffusion at a stretch to a narrow area on the wafer surface, and then a laser having an oscillation frequency of 3 KHz is set. By irradiating 198 shots of light, the diffusion is expanded in the lateral direction while maintaining the thermal diffusion in the depth direction processed first.

When all of the 200 shots of laser light are irradiated with the oscillation frequency set to 3 KHz, the processing depth of the dot is 7 μm. In the present embodiment, however, the processing depth is 9 μm, which is deeper. It has become possible to form dots.

When one dot is formed on a wafer by irradiating 25 shots of a Q-switch laser beam, the oscillation frequency of the laser beam is controlled, for example, as shown in FIG. That is, the first one shot is irradiated with a Q-switched laser beam whose oscillation frequency is set to 1 KHz, and the subsequent 19 shots have an oscillation frequency of 2 KH
Irradiated with a Q-switch laser beam set to z. Then, the last five shots are irradiated with a Q-switched laser beam whose oscillation frequency is set to 5 KHz.

The oscillation frequency of the laser light when one dot is formed on the wafer by irradiating 25 shots of the Q-switch laser light may be controlled as shown in FIG. That is, the oscillation frequency is 1K for the first shot.
Irradiate with Q-switched laser light set to Hz, irradiate subsequent shots with Q-switched laser light set so that oscillation frequency gradually increases, and set last shot to oscillation frequency of 5 KHz Irradiation with the Q-switched laser light.

Referring to FIG. 8, in the laser marking apparatus of the present embodiment, the control section 2 reads a dot forming processing program stored in a memory 1 in advance, and in accordance with the read processing program, a laser resonator. The Q-switch element 4 provided in 3 is controlled to change the oscillation frequency, pulse width, and peak value of the Q-switch laser light.

[0019]

As described above, in the laser marking device and method of the present invention, since the characteristics of the Q-switched laser light according to the oscillation frequency are used efficiently,
Compared to the case of marking with laser light of the same frequency in the process of forming one dot, a dot having a deeper processing depth can be formed and the processing speed can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a change in an oscillation frequency of a Q-switched laser beam according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating another example of a change in the oscillation frequency of a Q-switched laser beam according to an embodiment of the present invention.

FIG. 3 is a diagram showing a processing state by initial laser beam irradiation in one embodiment of the present invention.

FIG. 4 is a diagram showing a processing state formed by changing the oscillation frequency of the Q-switched laser light from the state shown in FIG. 3 in one embodiment of the present invention.

FIG. 5 is a diagram showing a specific example of a change in the oscillation frequency of a Q-switched laser beam according to an embodiment of the present invention.

FIG. 6 is a diagram illustrating another specific example of a change in the oscillation frequency of the Q-switched laser light according to an embodiment of the present invention.

FIG. 7 is a diagram showing still another specific example of a change in the oscillation frequency of the Q-switched laser light according to the embodiment of the present invention.

FIG. 8 is a diagram showing a configuration of a laser marking device according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Memory 2 Control part 3 Laser resonator 4 Q switch element

Claims (6)

[Claims] 1. A laser marking device for forming one dot by irradiating a spot on a workpiece with a Q-switch laser beam a plurality of times, wherein the Q-switch laser is formed in the process of forming the one dot. A laser marking device comprising: means for changing an oscillation frequency of light from a first frequency to a second frequency higher than the first frequency. 2. In the process of forming one dot, the Q-switched laser light initially irradiated is set to a first frequency having an oscillation frequency of 1 KHz or less, and thereafter, the formation of the dot proceeds. 2. The laser marking device according to claim 1, wherein the oscillating frequency is gradually or gradually increased. 3. In the process of forming one dot, the Q-switched laser light initially irradiated has a smaller pulse width and a higher peak value than the lastly irradiated Q-switched laser light. The laser marking device according to claim 2, wherein: 4. A laser marking method for irradiating a spot on a workpiece with a Q-switch laser beam a plurality of times to form one dot, wherein the Q-switch laser is formed in the step of forming the one dot. A laser marking device, wherein an oscillation frequency of light is changed from a first frequency to a second frequency higher than the first frequency. 5. In the process of forming one dot, the Q-switched laser light initially irradiated is set to a first frequency having an oscillation frequency of 1 KHz or less, and thereafter, the formation of the dot proceeds. 5. The laser marking method according to claim 4, wherein the oscillation frequency is increased gradually or stepwise. 6. In the process of forming one dot, the Q-switched laser light initially irradiated has a narrower pulse width and a higher peak value than the lastly irradiated Q-switched laser light. The laser marking method according to claim 5, wherein: