JPH0416031B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a laser light source device, and is particularly suitable for laser processing of semiconductors, etc., and is capable of increasing the stability of the output of each laser pulse. Regarding equipment.

[Background of the invention]

BACKGROUND ART As the quality of laser processing processes for semiconductors and the like has increased, stability of the output of each laser pulse has become important.

FIG. 1 is a block diagram showing an example of a conventional laser light source device of this kind. Hereinafter, the same reference numerals or symbols refer to the same or corresponding parts throughout the drawings. In the figure, 1 is a laser power source, and 2 is a laser oscillator. ,
3 is a laser beam. In FIG. 1, a laser oscillator 2 is driven by a laser power source 1 and a laser beam 3 is output. However, in this conventional device, in addition to the excitation state of the laser oscillator 2, the resonance condition changes due to deformation due to heat, vibration, etc. of the optical resonance cavity consisting of the resonator mirror and the optical amplification section of the laser oscillator 2, or due to dirt, etc. Therefore, the laser output of the obtained laser beam 3 varies. Therefore, when used in laser machining processes for semiconductors and the like that require highly stable working conditions, this fluctuation in laser output has the disadvantage that it causes deterioration in machining quality.

Next, FIG. 2 is a block diagram showing another example of a conventional laser light source device, in which 4 is a half mirror, 5 is a photodetector, and 6 is an arithmetic control section. Second
In the figure, a laser oscillator 2 is powered by a laser power source 1.
is driven, and the laser beam 3 is output. Then,
A portion of the output of this laser beam 3 is reflected by a half mirror 4 and enters a photodetector 5, and an electric signal indicating the laser power obtained here is sent to an arithmetic controller 6. Then, the actual laser output of the laser beam 3 is calculated. When the output of this laser beam 3 exceeds a predetermined output, the arithmetic control unit 6 controls the laser power supply 1 to reduce the power input to the laser oscillator 2, and in the opposite case, the power input Increase the laser oscillator 2
The portion of the output of the laser beam 3 transmitted through the half mirror 4 is made to have the required output. However, even with this conventional device, the laser oscillator 2
At the time when the laser power of the laser beam 3 is measured by the photodetector 5, the portion of the output of the laser beam 3 that has passed through the half mirror 4 continues as it is and is sent to the portion where the laser beam 3 is used. It is not possible to control the power of the laser light 3 at a point in time, but only the laser power of the laser light 3 that follows. For this reason, when used in laser processing processes for semiconductors and other products that require high quality, by the time the laser output is known to have fluctuated, the processing process with poor quality has already progressed. There were disadvantages such as controlling the laser output only returning to the previously high-quality processing process.

[Purpose of the invention]

An object of the present invention is to provide a laser light source device that eliminates the drawbacks of the above-mentioned conventional techniques and that can perform highly stable control of the output of each laser pulse, which can be used particularly for laser processing processes such as high-quality semiconductors. is to provide.

[Summary of the invention]

The present invention extracts a part of the laser output of a laser oscillator through an optical separation means and measures the laser output with a photodetector, and at the same time puts the remaining part of the laser output into an optical delay circuit and delays it. A computation and control unit compares the laser output measured by the photodetector and a predetermined output, and the output is transmitted through a laser amplifier or a laser amplifier and a transmitted light amount adjuster adjusted by a control signal based on the comparison computation from this computation and control unit. This is an optical delay type laser light source device with an amplifier, characterized in that the remaining portion of the laser output delayed by the optical delay circuit is extracted to obtain a required output.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 3 and 4.

FIG. 3 is a block diagram showing an embodiment of an optical delay type laser light source device with an amplifier according to the present invention. In FIG. 3, 1 is a laser power source for driving;
2 is a laser oscillator driven by the laser power source 1; 3 is a laser beam output from the laser oscillator 2;
4 is a light separating means for separating the laser beam 3 into two optical paths, for example, a half mirror; 5 is a means for receiving the laser beam of the reflected portion, which is one portion separated by the half mirror 4, and measuring the laser power; A photodetector 6 calculates the actual laser output of the laser beam 3 from the laser power measured by the photodetector 5, compares it with a predetermined laser output setting value set in advance, calculates the ratio, and calculates the ratio. 7 is a power supply for the laser amplifier which is controlled by the control signal from the arithmetic controller 6; 8 is a half mirror 4 which is a light separating means for the laser beam 3; An optical delay circuit 9 is provided at the subsequent stage of this optical delay circuit 8 and inputs the transparent portion that is the other remaining portion separated by and delays it by a predetermined time.
The laser beam, which is output with a delay of a predetermined time from This is a laser amplifier that amplifies the output to the required level. The optical delay circuit 8 mentioned above can be constructed using various types, such as one that combines a plurality of mirrors, one that passes a laser beam through an optical fiber, and one that causes total reflection in a prism repeatedly at an angle exceeding a limit angle. be able to.

To explain the operation of this configuration, first, a laser oscillator 2 is driven by a laser power source 1, and a laser beam 3 is output from the laser oscillator 2. A portion of the laser beam 3, for example 1%, is reflected by a half mirror 4 serving as a light separating means and enters the photodetector 5, while the remaining portion, for example 99%, is transmitted through the half mirror 4 and passes through the optical delay circuit. Enter 8. Note that the laser output of the laser beam 3 of the laser oscillator 2 can be set, for example, by power input from the laser power source 1 so that the output is a little lower than the required output. Next, the photodetector 5 that has received a portion of the laser beam 3 measures the received laser power and sends it to the arithmetic and control section 6 as an electrical signal. Then, the arithmetic control unit 6 calculates the actual laser output of the laser beam 3 from the laser power indicated by this input electric signal, performs a comparison operation with a predetermined laser output setting value set in advance by a comparison arithmetic circuit within itself, and calculates the ratio. At the same time, for example, the required amplification factor of the laser amplifier 9 to be increased by an amount lower than the required output of the transparent portion of the half mirror 4 is determined, and a corresponding control signal is sent to the laser amplifier power supply 7. When the laser amplifier 9 is being continuously excited, the power input of the laser amplifier power supply 7 to the laser amplifier 9 is adjusted. As a result, the laser amplifier 9 is adjusted to the required amplification factor and becomes ready to operate at this amplification factor. After amplifying the laser light output from the delay circuit 9 to a required output with a required amplification factor, the laser light output from the laser amplifier 9 with the required output is used to send it to a part where laser processing, etc., is performed. It will be done.

In this way, according to the amplifier-equipped optical delay type laser light source device of this embodiment, the laser light from the laser oscillator is temporarily delayed, and the laser amplifier adjusted according to the laser output measured during that time is used to Since the delayed laser light can be amplified to the required output, it is possible to control the output of each laser pulse with high stability, for example, and it can be used in laser processing processes for high-quality semiconductors and the like. Furthermore, by adding an amplifier, for example, when the gain is adjusted to 2, even if the output of the laser oscillator decreases by nearly half, it is possible to prevent the laser machining process from directly affecting the laser processing process.

Next, FIG. 4 is a block diagram showing another embodiment of the optical delay type laser light source device with an amplifier according to the present invention. In FIG. 4, reference numeral 10 denotes a power supply for the transmitted light amount adjuster, which is controlled by a control signal from the arithmetic controller 6, and 11 is arranged after the laser amplifier 9, and the output of this laser amplifier 9 is determined by the arithmetic controller 6. A transmitted light amount adjuster 12 is a laser light absorption cone which reduces the transmitted light amount to a required output with a required transmittance through the transmitted light amount adjuster power supply 10 which is controlled by the above-mentioned control signal to give the required transmittance. The laser amplifier 9 of this embodiment may be of such a type that the amplification factor itself can be set in several predetermined steps, for example, seven steps of amplification factors of 1.1, 1.2, 1.3, 1.4, 1.5, 1.7, and 2.0. In addition, the calculation control unit 6
calculates the actual laser output of the laser beam 3 from the laser power measured by the photodetector 5, compares it with a preset predetermined laser output value, calculates the ratio, and adjusts the output of the laser amplifier 9 according to the result. A value that can amplify the laser output to a greater extent than the required laser output is selected from several predetermined amplification factors, and a control signal to operate the laser amplifier 9 at the selected amplification factor is sent to the laser amplifier. At the same time, the output of the laser amplifier 9 that should be obtained when amplified with the selected amplification factor is compared with the required output, and the ratio is calculated. Determine the required transmittance of the transmitted light amount adjuster 11 that should be lowered to the required output, and send a corresponding control signal to the transmitted light amount adjuster power supply 10 to set the transmitted light amount adjuster 11 to the required transmittance. play a role. Note that as the transmitted light amount adjuster 11, a Pockels cell or the like that changes the polarization direction in which light can pass by changing the voltage can be used.

To explain the operation of this configuration, a laser oscillator 2 is driven by a laser power source 1 and a laser beam 3 is emitted.
outputs. A portion of this laser beam 3, for example 1%, is reflected by a half mirror 4 serving as a light separating means and enters a photodetector 5, while the remaining portion, for example 99%, is transmitted and input to an optical delay circuit 8. Next, the photodetector 5 measures the received laser power and sends it to the calculation control section 6 as an electrical signal. Then, the arithmetic control section 6 calculates the actual laser output of the laser beam 3 from the received laser power, compares it with a predetermined output set in advance by a comparison arithmetic circuit within itself, calculates the ratio, and calculates the actual laser beam output from the result. 3
If it is determined that the laser output of send to In this case, the amplification factor of the laser amplifier 9 can be set to seven values, for example, 1.1, 1.2, 1.3, 1.4, 1.5, 1.7, and 2.0, and is usually set to a value of, for example, 1.4 to match the normal laser output. If so, the amplification factor value, for example, 1.7, is selected so that the amplified laser output becomes larger than the required output depending on the extent to which the actual laser output of the laser beam 3 is lower than the predetermined output. As a result, the power input to the laser amplifier 9 from the laser amplifier power supply 7 that is continuously pumping the laser amplifier 9 is adjusted, and the laser amplifier 9 adjusts its own amplification factor to the selected amplification factor value, for example, 1.4. , becomes ready for operation at this selected amplification factor. On the other hand, the arithmetic control section 6 is connected to the previous laser amplifier 9.
At the same time, the output of the laser amplifier 9 that should be obtained when amplifying with the selected amplification factor is compared with the required output, the ratio is calculated, and from this, the output of the laser amplifier 9 is calculated as the required output. A required transmittance of the transmitted light amount adjuster 11 to be lowered to the output is determined, and a control signal for setting the transmitted light amount adjuster 11 to the required transmittance is correspondingly sent to the transmitted light amount adjuster power supply 10. As a result, from the transmitted light amount regulator power supply 10 to the transmitted light amount regulator 1
Adjust the power input to the transmitted light amount adjuster 11.
is adjusted to a required transmittance, and becomes ready for operation at this required transmittance. Next, the laser beam output from the optical delay circuit 8 after being delayed by a predetermined time until both the laser amplifier 9 and the transmitted light amount adjuster 11 become operational under the required conditions is outputted from the laser beam as described above. After being sent to the amplifier 9 and amplified to a predetermined value larger than the required output using the amplification factor of the selected value, it enters the transmitting light amount adjuster 11 in the subsequent stage and is adjusted to the set value for the required output with the required transmittance. This allows a laser beam with the exact required power to be obtained. In addition, when the arithmetic control section 6 determines that the actual output of the laser beam 3 is higher than the predetermined output, the arithmetic control section 6 turns on the power supply 7 for the laser amplifier if necessary according to the value of the difference. The laser amplifier 9 can be controlled to reduce the amplification factor values of several stages of the laser amplifier 9 from the usual value of 1.4 to a value of 1.1, for example, and still have a higher output than the required output.
The amplification factor of the laser amplifier 9 is adjusted to a predetermined amplification factor so that the output becomes , and the transmitted light amount adjuster power supply 10 is also controlled by the arithmetic control section 6 to adjust the transmittance of the transmitted light amount adjuster 11 to the required value. Adjust to. Then, under such predetermined conditions, the laser light outputted by the optical delay circuit 8 after being delayed by a predetermined time until the laser amplifier 9 and the transmitted light amount adjuster 11 become activated is amplified by the predetermined amplification selected by the laser amplifier 9. After being amplified by the transmittance, the transmittance light amount adjuster 11 adjusts the amount of transmitted light to the required transmittance, thereby obtaining a laser beam with the correct required output and sending it to the part that uses it, such as the laser processing process. .

In this way, according to the optical delay type laser light source device with an amplifier of this embodiment, by further arranging a transmitted light amount adjuster, for example, after the amplifier, amplification can be achieved without the need for a laser amplifier with a continuously variable amplification factor. The laser amplifier and transmitted light amount adjuster, which can be selected in multiple stages, allow the laser light delayed by the optical delay circuit to be adjusted to the exact required output, allowing for highly stable control of the output of each laser pulse, for example. This makes it possible to use it for high-quality laser machining processes.

〔Effect of the invention〕

As is clear from the above explanation, according to the amplifier-equipped optical delay type laser light source device of the present invention,
By temporarily delaying the output of the laser oscillator and adjusting it to the required output according to the measured laser output during that time, accurate and stable laser output can be obtained. Highly stable control of output becomes possible, and it can be effectively applied to various laser application fields, including laser processing processes for semiconductors and other devices that require fine precision and high quality.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a conventional laser light source device, FIG. 2 is a block diagram showing another example, FIG. 3 is a block diagram showing an embodiment of a laser light source device according to the present invention, and FIG. The figure is a block diagram showing another embodiment. 1... Laser power supply, 2... Laser oscillator, 3...
... Laser light, 4 ... Half mirror as light separation means, 5 ... Photodetector, 6 ... Arithmetic control section, 7 ...
Power supply for laser amplifier, 8... Optical delay circuit, 9...
Laser amplifier, 10...power supply for transmitted light amount adjuster,
11... Transmitted light amount adjuster.

Claims (1)

[Scope of Claims] 1. A laser oscillator, a light separation means for separating the laser light from the laser oscillator into two, and receiving one of the laser lights separated by the light separation means and measuring the laser output. a photodetector, an optical delay circuit that inputs the other laser beam separated by the optical separation means and delays it for a predetermined time, and an arithmetic control section that determines a required amplification factor from the laser output measured by the photodetector. and a laser amplifier that amplifies laser light outputted from the optical delay circuit with a predetermined time delay to a required output using the required amplification factor determined by the arithmetic control section. 2. A laser oscillator, a light separation means that separates the laser light from the laser oscillator into two, a photodetector that receives one of the laser lights separated by the light separation means and measures the laser output, and the above-mentioned an optical delay circuit that inputs the other laser beam separated by the optical separation means and delays it for a predetermined time; an arithmetic control unit that determines a predetermined amplification factor and a required transmittance from the laser output measured by the photodetector; a laser amplifier that serially amplifies and transmits the laser light output from the optical delay circuit with a predetermined time delay at the predetermined amplification factor and the required transmittance determined by the arithmetic control unit, and outputs the laser light with the required output; and a laser light source device consisting of a transmitted light amount adjuster.