JP2012011402A - Method for processing workpiece, device for emitting light for processing workpiece, and program used for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a depth constant even when a workpiece temperature is unequal, in a method of laser processing, which melts a workpiece by a prescribed depth by relatively displacing a laser beam and the workpiece, while emitting the laser beam to the workpiece.SOLUTION: In the method, a temperature of a point of the workpiece, which is different from a point to be irradiated of the workpiece, is measured to control an output power based on the depth and the temperature.

Description

  The present invention relates to a workpiece processing method, a workpiece processing light irradiation apparatus, and a program used therefor, in which at least one of light and a workpiece is scanned while the workpiece is irradiated with light such as a laser.

  There are laser welding, annealing, doping, surface modification, and the like as the work is heat-treated by scanning at least one of the laser light and the work while irradiating the work with the laser light. In these processes, the laser is used as a heating source for performing a desired process such as tissue change or melting on the workpiece. In these processes, in many cases, it is desired that the depth to be modified or melted by the laser is uniform regardless of the position in the workpiece.

Patent Document 1 relates to CO ₂ laser welding, in order to make the penetration depth and welding beat width of the welded portion constant, the temperature and weld width at the rear of the welded portion are measured, and the measured temperature and weld width are set in advance. A technique for controlling heat input to an object to be welded so as to obtain a temperature and a welding width is disclosed.

  FIG. 5 shows a configuration of an apparatus according to Patent Document 1. In FIG. 5, a laser beam 103 from a laser oscillator 101 is optically converted by an optical mirror 102, condensed by a laser beam condensing lens 104, and irradiated onto a workpiece 120. A half mirror 106 is disposed between the optical mirror 102 and the condenser lens 104 at an inclination of 45 ° with respect to the laser light. The half mirror and the condenser lens are integrally formed by a case 121. This portion is hereinafter referred to as a laser welding head. In the vicinity of the welding head, an infrared condensing head 107 for detecting the temperature at the rear of the melting pool 105 of the welded portion is fixed to the welding head. Infrared light from the welded portion is condensed by the infrared condensing head 107 and transmitted to the infrared temperature detector 115 by the optical fiber 112. In the infrared temperature detector 115, the transmitted infrared wavelength is limited by the optical filter 113 and is incident on the infrared detector 114. Here, photoelectric conversion is performed, and amplification is performed by the amplifier 116. That is, the magnitude of the output electric signal of the amplifier 116 corresponds to the temperature of the weld. The temperature signal from the amplifier 116 is processed by the microcomputer 117, and the output of the laser oscillator 101 is controlled via the laser irradiation output control device 119 so that the detected temperature matches the set temperature.

On the other hand, the portion of the half mirror 106 of the welding head includes a television camera 109 and a lens 108 for imaging the welded portion. The half mirror 106 is a mirror that transmits CO ₂ laser light and reflects visible light. The video signal from the TV camera is binarized by the image signal processor 110 to detect the width of the weld pool 105 of the welded part. In addition, the welded portion is displayed on the monitor TV 111 and is used for monitoring. The output from the image signal processor 110, that is, the melt pool width signal is processed by the microcomputer 117, and the position of the condensing lens 104 of the laser beam is moved up and down so that the detected weld width matches the set melt width. The focal position of the focused laser beam with respect to the workpiece is controlled via the mechanism 118.

  Patent Document 2 discloses a light beam heating apparatus that can obtain a desired temperature rise curve and construction conditions.

  FIG. 6 is a configuration diagram of a light beam heating device described in Patent Document 2. In FIG. An irradiation means is constituted by the optical fiber 201 and the lens 202, and the object to be heated 204 can be applied by the irradiation light 203. Reference numeral 206 denotes a supply substance that is supplied to the irradiated portion 205 during heating, and reference numeral 207 denotes a supply substance feeding device. Reference numeral 208 denotes a temperature sensor for measuring the temperature of the irradiated portion 205, and reference numeral 209 denotes a temperature recording unit for recording temperature measurement data from the temperature sensor 208. Reference numeral 210 denotes a thermal constant calculation unit that calculates the thermal constant of the irradiated portion 205 from the temperature measurement data from the temperature recording unit 209. The flowchart of FIG. 6 shows the flow of processing. DATA (Tn, tn) is temperature measurement data recorded in the temperature recording unit 209 and includes a measurement temperature Tn and a measurement time tn. In the thermal constant calculation unit 210, a temperature increase function T (t) = f (R, C, P, t) + Ta is prepared in advance. The temperature rise function T (t) is a dependent variable, and the time t is an independent variable. Further, the temperature increase function T (t) includes a heat radiation resistance R, a heat capacity C, an irradiation output P as parameters, and an ambient temperature Ta as a constant term. Among the parameters, the heat radiation resistance R and the heat capacity C are thermal constants and are values specific to the irradiated portion 205. The ambient temperature Ta may be expressed as the temperature of the irradiated portion 5 or the heated object 204 before being heated by irradiation.

  Among the variables constituting the temperature increase function T (t), the values of the irradiation output P and the ambient temperature Ta are constants because they can be known by the power measuring device and the thermometer before the irradiation. The measured value of the irradiation output P and the ambient temperature Ta and the temperature measurement data DATA (Tn, tn) are substituted into the temperature rise function T (t), and a solution is obtained for the heat radiation resistance R and the heat capacity C, which are thermal constants.

  The temperature measurement data can be expressed as a function by the heat radiation resistance R and the heat capacity C, which are the thermal constants specific to the irradiated part 205. In addition, an arbitrary temperature rise curve can be obtained by substituting an arbitrary irradiation output P and ambient temperature Ta into the function formula, and a construction condition set value can be obtained from the calculated thermal constant and desired temperature conditions. it can.

  Patent Document 3 discloses a technique for measuring the depth of the melted portion at the laser beam incident position of a laser annealing object.

  FIG. 7 shows a schematic diagram of a laser annealing apparatus described in Patent Document 3. The XY stage 301 holds the semiconductor substrate 302 to be annealed and moves it in a two-dimensional direction parallel to the surface. An xyz orthogonal coordinate system is defined in which a plane parallel to the surface of the semiconductor substrate 302 is defined as an xy plane, and a normal direction of the substrate is defined as a z-axis. FIG. 5 shows a schematic view when seen with a line of sight parallel to the y-axis.

  The annealing laser light source 305 emits an annealing pulse laser beam La in synchronization with the trigger signal sig1 from the control device 350.

  A laser beam La emitted from the annealing laser light source 305 is incident on the semiconductor substrate 302 held on the XY stage 301 via the shaping and uniformizing optical system 306. The shaping and homogenizing optical system 306 makes the cross section of the laser beam on the surface of the semiconductor substrate 302 long and long in the y-axis direction, and makes the light intensity distribution in the plane uniform. By repeating the main scanning process in which the pulse laser beam is incident while driving the XY stage 301 to move the semiconductor substrate 302 in the x-axis direction and the sub-scanning process in which the semiconductor substrate 302 is shifted in the y-axis direction, Nearly the entire surface of 302 can be laser annealed. The XY stage 301 is controlled by the control device 350.

  A measurement light source 310 emits a measurement laser beam. The measurement laser beam emitted from the measurement light source 310 enters the region of the semiconductor substrate 302 where the annealing pulse laser beam is incident, via the pulsing device 311, the optical fiber 312, and the lens 313.

  The reflected light of the measurement laser beam reflected by the surface of the semiconductor substrate 302 enters the reflected light detector 324 via the lens 320, the first filter 321, the second filter 322, and the optical fiber 323. The first filter 321 blocks light having a wavelength shorter than 530 nm, and the second filter 322 blocks light having a wavelength longer than 700 nm. The first filter 321 and the second filter 322 shield the plasma light from the plume generated by the incidence of the annealing laser beam, the black body radiation light due to the temperature rise, etc., mainly the reflected light of the measurement laser beam. Enters the reflected light detector 324.

  The reflected light detector 324 converts the intensity of the reflected light into an electrical signal. The intensity signal sig2 of the reflected light converted into the electric signal is input to the control device 350.

  When one laser pulse of the pulse laser beam La is incident on the semiconductor substrate 302, the surface layer portion is temporarily melted, and when the laser pulse is incident, the melted portion is recrystallized. Since the reflectance increases during the period when the surface layer portion is melted, the reflected light intensity signal sig2 increases.

The elapsed time from the time when the reflected light intensity increased to 1/2 the amount of increase from the background level to the maximum value to the time when the reflected light intensity decreased to 1/2 was taken as the melting time. Controller 350 can be based on equation (1), to calculate the melting depth h _m from the melting time tau _s.

Here, C ₁ and C ₂ are constants.

JP 59-212184 A JP-A-11-221683 JP 2008-117877 A

  However, in the technique described in Patent Document 1, even if the temperature and the welding width at the rear portion of the welded portion are constant, it cannot be said that the penetration depth is always constant. In the technique described in Patent Document 1, the temperature being measured is the surface temperature of the member to be welded. When the temperature of the member to be welded changes with the progress of welding, etc., even if the surface temperature of the rear part of the welded part is controlled to be constant using the technique described in Patent Document 1, the temperature in the deep part always matches. I can't say that. That is, it cannot be said that the penetration depth is constant.

  The technique described in Patent Document 2 also uses the ambient temperature Ta as a constant, and does not consider the case where the ambient temperature Ta changes as the welding progresses. Therefore, there is a possibility that an error occurs in the calculation of the heat radiation resistance R and the heat capacity C as the ambient temperature Ta changes. Moreover, since it is not a technique for melting an irradiated object to a predetermined depth by heating, it cannot be used for such applications.

In the technique described in Patent Document 3, in the calculation according to the equation (1), it is assumed that the loss due to heat conduction or the like among the energy given to the semiconductor substrate 302 is constant. If the temperature of the front is not constant, this means that the loss is changed, causing an error in the calculation of the melting depth h _m.

For example, when scanning while irradiating a workpiece with laser light, temperature unevenness occurs in the workpiece surface due to heat conduction from the laser irradiation region. For this reason, an error occurs in the calculation of the melting depth. Further, even if the workpiece is scanned while keeping the melting time τ _s or the laser output constant, the melting depth becomes non-uniform.

  FIG. 8 schematically shows the temperature distribution on the workpiece as an isotherm when the workpiece is irradiated with a circular laser beam while being scanned and straight lines are drawn at regular intervals. FIG. 8A shows a temperature distribution immediately before starting laser irradiation from a point P1 on the workpiece. In FIG. 8A, since the temperature Ti in the substrate surface is constant, there is no isotherm on the workpiece. Thereafter, as laser irradiation is performed, the heat applied to the workpiece by the laser beam irradiation spreads in the workpiece due to heat conduction, and the temperature of the workpiece rises. Therefore, immediately before starting the fourth scan shown in FIG. 8B from the point P3, a temperature gradient occurs around the end point P2 of the third scan. Further, the temperature Ti ′ immediately before the laser irradiation at the point P3 is higher than Ti. Therefore, when the laser output at the point P1 is the same as the laser output at the point P3, the melting depth at the point P3 is deeper than the melting depth at the point P1. Further, even if the melting time at the point P1 is the same as the melting time at the point P3, the melting depth at the point P3 becomes deeper than the melting depth at the point P1.

In addition, since the technique described in Patent Document 3 is a technique for calculating the depth using the melting time τ _s in pulse irradiation, the melting depth cannot be calculated when laser light or the like is continuously irradiated.

  In view of the above problems, an object of the present invention is to provide a processing method, a light irradiation apparatus, and a program for melting a workpiece to a desired melting depth.

  Another object of the present invention is to provide a processing method, a light irradiation apparatus, and a program for making the melting depth constant even when the temperature of the workpiece becomes non-uniform due to heat conduction from the light irradiation region.

  Another object of the present invention is to provide a processing method, a processing apparatus, and a program for making the melting depth constant by using a light emitter that continuously irradiates.

  In order to solve the above-described problem, the processing method of the present invention is configured to move the optical axis of the light and the work relative to each other while irradiating the irradiated portion of the work with the work to a predetermined depth. In the melting processing method, the temperature Tx of the workpiece at a position different from the irradiated portion is measured, and the light output is controlled from the depth and the temperature Tx.

  Further, the temperature Ts of the irradiated portion is measured, and the output is controlled from the temperature Ts, the temperature Tx, and the output.

  The output is controlled by calculating a logical value of the surface temperature of the irradiated portion from the temperature Ts, the temperature Tx, and the output so that the temperature Ts approaches a logical value.

  Further, the output of the light is controlled using the ratio between the logical value and the temperature Ts as the output correction coefficient α.

  Further, the different position is a position separated from the irradiated portion by a predetermined distance forward in the scanning direction of the light.

  Further, as the temperature Tx, a temperature previously measured for a predetermined time is used.

  Further, the different position is a back surface of the irradiated portion.

  The program of the present invention is a program for controlling a light irradiation apparatus that heats the workpiece by moving the optical axis of the light relative to the workpiece while irradiating the irradiated portion of the workpiece with light. The program calculates an output from the step of measuring the temperature Tx of the workpiece at a position different from the irradiated portion that is the position irradiated with the light on the irradiated surface of the workpiece, and the depth and the temperature Tx. And a step of controlling the light output based on the calculating step.

The inventor's light irradiation apparatus is a light irradiation apparatus that melts the work to a predetermined depth by relatively moving the optical axis of the light and the work while irradiating the irradiated portion of the work with light. A light emitter and a peripheral thermometer for measuring a temperature Tx at a position different from the irradiated portion;
A light irradiation apparatus comprising: an arithmetic unit that calculates an output from the depth and the temperature Tx; and a control unit that controls the output of the light to the output.

  Further, the light emitter includes a stop whose aperture size can be adjusted in a direction orthogonal to the scanning direction of the light, and an imaging lens for forming an image of the stop.

  Further, the position different from the irradiated portion is configured to be movable about a position around the irradiated portion.

  According to the present invention, it is possible to perform light irradiation that melts a workpiece to a desired depth.

  Further, since the light output Q is calculated based on the temperature Tx before irradiation measured by the ambient thermometer, the melting depth can be made constant.

  Moreover, the light emitter which irradiates continuously can be used.

It is a schematic diagram which shows the structure of the laser beam irradiation apparatus concerning this Embodiment. It is a flowchart which shows the flow of control of the laser processing method which concerns on this Embodiment. It is a graph which shows the temperature change from the normal temperature to the quasi-stationary state according to the present embodiment. It is a schematic diagram which shows the structure of the laser beam irradiation apparatus concerning this Embodiment. It is a schematic diagram of an apparatus used for CO ₂ laser welding according to the prior art. It is the schematic of the light beam heating apparatus which concerns on a prior art. It is the schematic of the laser annealing apparatus based on a prior art. It is a schematic diagram which shows the temperature distribution on a workpiece | work with an isotherm.

  Hereinafter, a workpiece machining method, a workpiece machining light irradiation apparatus, and a program used therefor according to an embodiment of the present invention will be described in detail.

  In the following, a workpiece to be melted at least part of its surface by heating by light irradiation is called a workpiece. Applications of the workpiece processing method according to the embodiment of the present invention include doping processing using a semiconductor wafer as a workpiece and laser annealing for recrystallization. In addition, the present invention can be applied to other workpieces as long as the object to be processed is melted, such as soldering or welding.

  FIG. 1 is a schematic diagram illustrating a configuration of a light irradiation apparatus. The laser oscillator 2, which is a light emitter, oscillates laser light in response to a signal from the control unit 7 and irradiates the irradiated surface of the work 3 with the laser light. The irradiated laser light has a circular uniform energy distribution with a radius of 20 μm on the irradiated surface. The workpiece 3 is supported on a stage 8 which is a moving unit, and the laser beam irradiation apparatus 1 can move the workpiece 3 relative to the optical axis of the laser beam by the operation of the stage 8. The laser beam irradiation apparatus of the present embodiment can perform heat treatment by irradiating the laser beam along an arbitrary pattern on the irradiated surface of the workpiece 3 by operating the stage 8 while irradiating the laser beam.

  Two radiation thermometers are installed above the work 3. One is an irradiated portion thermometer 5 that measures the surface temperature of the workpiece 3 at a position (hereinafter referred to as an irradiated portion) irradiated with laser light on the irradiated surface of the workpiece 3. Installed in focus.

  The other peripheral thermometer 4 is installed with a focus on the different position in order to measure the temperature at a position different from the irradiated portion of the work 3. The position where the peripheral thermometer 4 is focused needs to be far from the irradiated part to such an extent that heat conduction from the irradiated part can be ignored. In the present embodiment, the error in the temperature of the irradiated portion resulting from the heat conduction is set to 1% or less of the amount of temperature rise in the irradiated portion, so that the position where the peripheral thermometer 4 focuses and the irradiated portion The distance x was set to 0.2 mm.

  The different position is a position on the irradiated surface which is a distance x away from the irradiated portion in the direction opposite to the feeding direction of the stage 8, in other words, in the scanning direction of the laser beam.

  Further, it is desirable that the position where the peripheral thermometer 4 is focused is configured to be movable around the irradiated portion. In this configuration, when the scanning direction of the laser beam is changed, the position where the peripheral thermometer 4 is focused is set to the front of the scanning direction of the laser beam only by rotating the position where the peripheral thermometer 4 is focused. And the distance x does not change. Therefore, the scanning direction of the laser beam can be arbitrarily changed.

  Further, the irradiated portion thermometer 5 and the peripheral thermometer 4 may be interchanged depending on the scanning direction. In this case, in order to set the position where the peripheral thermometer 4 is focused as the irradiated part and the position where the irradiated thermometer 5 is focused as the front in the scanning direction of the laser beam, the irradiated thermometer 5 It is necessary to move the position where the focus is adjusted, the position where the peripheral thermometer 4 is focused, or the position of the irradiated part.

  The two radiation thermometers are connected to the calculation unit 6, and the temperature measurement value is input to the calculation unit 6. The calculation unit 6 includes a storage unit that stores a program and a CPU that executes the program. The stored program controls the laser beam irradiation apparatus of the present embodiment, and is used for the peripheral thermometer 4 and the irradiated unit. Based on the measurement value input from the thermometer 5, the output of the laser beam which the laser oscillator 2 should emit is calculated, and the processing method of the present embodiment is executed.

  The calculation unit 6 is connected to the control unit 7 and configured to input the calculated result to the control unit 7. On the axis of the laser beam from the laser oscillator 2 to the workpiece 3, an aperture 9 whose aperture size can be adjusted and an imaging lens 10 that forms an image of the aperture 9 are installed, and the shape of the laser beam irradiated onto the workpiece 3 Can be adjusted.

  In the laser beam irradiation apparatus 1 of the present embodiment, it is only necessary that the laser beam irradiation apparatus 1 can move relatively by moving at least one of the optical axis of the laser beam and the work 3 (in this specification, the movement is “scan”). Will be called). That is, the laser beam irradiation apparatus 1 of this embodiment uses the stage 8 as a fixed stage, and a moving unit that moves the laser oscillator 2, the peripheral thermometer 4, the irradiated portion thermometer 5, the diaphragm 9, and the imaging lens 10. May be provided instead.

  FIG. 2 is a flowchart showing a control flow of the laser processing method of this embodiment. Hereinafter, the procedure of the laser processing method of the present embodiment for melting the workpiece to a predetermined depth z will be described with reference to FIGS.

  First, in S1, 1 is input as an initial value to the correction coefficient α, which is a variable stored in the calculation unit 6. Next, in S2, the ambient thermometer 4 measures the ambient temperature Tx, and the calculation unit 6 stores the ambient temperature Tx.

  Next, in S <b> 3, the calculation unit 6 calculates the necessary laser light output Q [W] from the desired melting depth z and the ambient temperature Tx. For the calculation, among the ambient temperatures Tx stored in the calculation unit 6, the ambient temperature Tx measured previously by the time x / v obtained by dividing the distance x by the scan speed v is used. The Tx is the previous temperature of the surface of the work 3 located at the irradiated portion when the output Q is calculated. However, when the elapsed time from the start of scanning or the start of Tx measurement is less than x / v [sec], the value at the start of scanning of the laser beam or the start of Tx measurement (the elapsed time from the start is 0 sec) is used. In this embodiment, x = 0.2 mm and v = 100 mm / second, so x / v = 0.002 seconds.

  It should be noted that Tx measured before time x / v−Δt may be used for calculating the output Q by using the time lag Δt between the calculation of the output Q and the irradiation of the laser beam controlled by the output Q. . In this case, the previous temperature of the surface of the work 3 positioned at the irradiated portion at the time of irradiation of the laser light controlled by the output Q is used for calculation of the output Q.

  In the present embodiment, the ambient temperature Tx is measured at a position away from the irradiated portion in the scanning direction of the laser beam, and the output Q is controlled or calculated by the output Q. By using the previous temperature of the surface of the work 3 positioned at the irradiated portion at the time of laser light irradiation for the calculation of the output Q, the measurement due to the difference between the measurement position of the temperature Tx and the position of the irradiated portion on the work 3 Errors can be eliminated.

The principle of the calculation will be described in detail. According to “Nikkei Technical Library Co., Ltd. Laser Processing 220-221”, the temperature rise θ (r, z) [K] for the moving heat source having a circular uniform distribution heat of radius a and the heat flux q ₀ [ The relationship in the steady state with W / m ² ] is given by equation (2).

v: scan speed, k: thermal diffusivity, λ: thermal conductivity.

  Here, assuming that the temperature at the depth z before the laser irradiation is Tx, and assuming that the temperature reaches the melting point Tm at the depth z immediately under the irradiated portion, θ (0, z) = Tm in the equation (2). -Tx, r = 0, and if it is substituted and arranged, the necessary output Q [W] is given by equation (3).

A: Absorption rate of workpiece surface, α: Correction coefficient.

  Since Q of the formula (3) does not consider the heat of fusion of the workpiece, βΔT is added as the rising temperature corresponding to the heat of fusion. The equation after βΔT addition is shown in equation (4).

ΔT is a value calculated as ΔT = L / c [K] using the heat of fusion L [J / kg] of the workpiece 3 and the specific heat c [J / kg · K]. Β is a correction coefficient, which is a value calculated based on the relationship between the heat quantity Q and the melting depth z in the previous irradiation experiment. According to the equation (4), it is possible to calculate the amount of heat Q necessary for melting to the depth z by a moving heat source having a circular uniform distribution heat with a radius a.

  Next, in S4, the control unit 7 oscillates the laser oscillator 2 based on the heat quantity Q calculated by the calculation unit 6, and irradiates the laser beam.

  Next, in S5, the irradiated portion thermometer 5 measures the surface temperature Ts of the irradiated portion.

Next, in S6, the calculation unit 6 calculates Ts ′ = θ (0,0) + Tx−ΔT by using the logical value Ts ′ of the surface temperature of the irradiated portion in Expression (2). In calculating θ (0,0), a value obtained by dividing the output Q by the irradiation area πa ² is used as q ₀ . Next, using the Ts measured in S5 and the logical value Ts ′, the correction coefficient α = (Ts−Tx) / (Ts′−Tx) based on the ratio between the logical value Ts ′ and the temperature Ts. And the value of the correction coefficient α stored in the calculation unit 6 is updated to the calculated value of the correction coefficient α.

  Next, in S7, it is determined whether or not the scan is completed. If completed, the irradiation is stopped, and if not completed, the process returns to S2. Since the correction coefficient α is updated in S6, the updated correction coefficient α is used for calculation of the output Q in the next S3. This enables feedback control. In this embodiment, feedback loop control with S2 to S6 as one cycle is performed once every 0.002 seconds. Expressions (2) to (4) are relational expressions in the steady state. In this embodiment, since the quasi-steady state is reached in a very short time after the start of laser irradiation, the feedback control interval is set to the quasi-steady state. In the present embodiment, which is longer than the time until the error, the error is within an allowable range.

  FIG. 3 is a graph showing the temperature change from the normal temperature to the quasi-steady state by laser irradiation. From the graph of FIG. 3, it can be seen that the temperature reached 1330 degrees after 0.0006 seconds after the start of irradiation, decreased to 1328 degrees after 0.0008 seconds, and increased again to 1334 degrees after 0.001 seconds. That is, after 0.0008 seconds, no upward trend is observed, and it is estimated that the steady state transitions within the range of 6 ° C. from 1328 degrees to 1334 degrees.

  The laser beam irradiation apparatus of the present embodiment is a laser beam irradiation apparatus that controls the output of the laser beam to an output Q determined by a desired melting depth z and an ambient temperature Tx.

  Further, the laser beam irradiation apparatus of the present embodiment controls the laser beam output Q so that the measured value Ts approaches the logical value Ts ′ of the surface temperature of the irradiated portion that is uniquely determined by the output Q and the ambient temperature Tx. It is a light irradiation device.

  According to the present embodiment, it is possible to perform laser irradiation for melting the workpiece to the desired depth z.

  Further, since the laser beam output Q is calculated based on the temperature Tx before laser irradiation measured by the ambient thermometer 4, the melting depth can be made constant regardless of the temperature Tx.

  In addition, a continuous irradiation laser can be used.

  When the absorption rate A of the laser beam is different between when the workpiece 3 is solid and when the workpiece 3 is liquid, regarding a section where θ (0,0) <Tm (that is, until the surface of the workpiece 3 reaches the melting point Tm), The output Qs may be obtained using the solid absorptance, the output Ql may be obtained using the liquid absorptivity for the period after reaching the melting point, and the output Qs may be obtained by adding the output Qs and the output Ql. .

  When the laser light is not a circular uniform distribution on the irradiated surface, equations corresponding to each distribution may be used instead of equations (2) to (4).

  For example, a Gaussian-distributed laser oscillator may be used as the laser oscillator 2, and in this case, the expression (5) is used instead of the expression (2) as described in “Nikkei Technical Library Co., Ltd. Laser Processing 220-221”. To calculate.

  Further, as an approximation, the ideal point heat source equation (6) described in “Nikkei Technical Library Co., Ltd. Laser Processing 220-221” may be used instead of the equation (2).

  In addition, when the temperature distribution in the horizontal direction changes due to the control of the laser output and the width of the melting region changes, the aperture size in the direction orthogonal to the scanning direction of the laser beam of the diaphragm 9 is adjusted to adjust the melting region. It is desirable to adjust the width. For example, when the melting width is increased by controlling the laser output, the aperture size is narrowed to reduce the irradiation area. Here, since the output per unit area of the laser beam does not change, the influence on the melting depth z is small, and the reduction amount of the melting width is almost equal to the reduction amount of the opening size, so that the melting width can be adjusted with high accuracy. .

  In this embodiment, the laser oscillator 2 is continuously oscillated and the laser beam is continuously irradiated. However, the laser beam may be pulsated. In that case, a calculation formula for the temperature increase θ corresponding to the pulse irradiation may be used instead of the formulas (2) to (4).

  FIG. 4 is a schematic diagram illustrating a configuration of a laser beam irradiation apparatus (light irradiation apparatus) according to the present embodiment. In the present embodiment, unlike the first embodiment, the peripheral thermometer 4 is installed below the stage 8 and is placed in focus on the back of the irradiated portion.

  The plate thickness of the work 3 needs to be so thick that heat conduction from the irradiated portion can be ignored. In the present embodiment, the error in the temperature of the irradiated portion resulting from the heat conduction is set to 1% or less of the amount of temperature rise in the irradiated portion, so that the position where the peripheral thermometer 4 focuses and the irradiated portion The distance x was set to 0.2 mm.

  By measuring the temperature Tx on the back surface of the irradiated part, the interval between the time when measuring the temperature Ts and the time when measuring the temperature Tm can be shortened and ideally at the same time. The generated error can be reduced.

  In addition, the configuration of the laser beam irradiation apparatus of the present embodiment can be simplified because it is not necessary to configure the position measured by the peripheral thermometer 4 so that the position can be rotated about the irradiated portion.

    INDUSTRIAL APPLICABILITY The processing method and the irradiation apparatus according to the present invention can be used in fields of application in which not only laser light but also electromagnetic waves including visible light are irradiated, or high-temperature gas is injected to heat a workpiece and melt it to a predetermined depth. .

2 Laser Oscillator 4 Peripheral Thermometer 5 Irradiated Part Thermometer 6 Arithmetic Unit 7 Control Unit 8 Stage 9 Aperture 10 Imaging Lens

Claims (11)

In the processing method of melting the workpiece to a predetermined depth by relatively moving the optical axis of the light and the workpiece while irradiating the irradiated portion of the workpiece,
Measure the temperature Tx of the workpiece at a position different from the irradiated part,
A processing method comprising controlling the light output from the depth and the temperature Tx. Measure the temperature Ts of the irradiated part,
The processing method according to claim 1, wherein the output is controlled from the temperature Ts, the temperature Tx, and the output. The output is controlled by calculating a logical value of a surface temperature of the irradiated portion from the temperature Ts, the temperature Tx, and the output, and making the temperature Ts close to the logical value. The processing method of thru | or 2.   4. The laser processing method according to claim 3, wherein the output of the light is controlled using the ratio between the logical value and the temperature Ts as the output correction coefficient α.   The processing method according to claim 1, wherein the different position is a position away from the irradiated portion by a predetermined distance forward in the scanning direction of the light.   The processing method according to claim 5, wherein a temperature measured previously for a predetermined time is used as the temperature Tx.   The processing method according to claim 1, wherein the different position is a back surface of the irradiated portion. A program for controlling a light irradiation device that heats the workpiece by moving the optical axis of the light relative to the workpiece while irradiating the irradiated portion of the workpiece,
The program is
Measuring the temperature Tx of the workpiece at a position different from the irradiated portion that is the position irradiated with the light on the irradiated surface of the workpiece;
Calculating an output from the depth and the temperature Tx;
Controlling the output of the light based on the calculating step;
A program characterized by comprising. A light irradiation device that melts the work to a predetermined depth by relatively moving the optical axis of the light and the work while irradiating the irradiated portion of the work,
A light emitter;
A peripheral thermometer for measuring a temperature Tx at a position different from the irradiated portion;
An arithmetic unit for calculating an output from the depth and the temperature Tx;
A control unit for controlling the output of the light to the output;
A light irradiation apparatus comprising: The light emitter is
A diaphragm whose aperture size can be adjusted in a direction orthogonal to the scanning direction of the light; and an imaging lens that forms an image of the diaphragm;
The light irradiation apparatus according to claim 9, comprising:   The light irradiation apparatus according to claim 10, wherein the position different from the irradiated portion is configured to be able to move a position around the irradiated portion.