Drawing apparatus and beam intensity determination method

Abstract

Even if the surface shape of the object being drawn differs, appropriate drawing will be performed. [Solution] A drawing device that draws by irradiating light includes a laser light source (21), a modulator (23) that modulates a light beam (81) from the laser light source (21), a movement mechanism (26) that moves the irradiation position of the light beam (81) guided from the modulator (23) on a drawing target (91), and a control unit (3) that controls the modulator (23) and the movement mechanism (26). The control unit (3) determines the intensity of the light beam (81) on the drawing target (91) based on the amplitude of a spatial frequency higher than 1 / 2 the frequency of the light beam (81) among the amplitudes of spatial frequencies in the surface shape of the drawing target (91).

Description

[Technical Field]

[0001] The present invention relates to a technique for drawing images by irradiating a laser beam. [Background technology]

[0002] Conventionally, drawing devices that guide a laser beam to a drawing target and move the irradiation position of the laser beam to perform drawing have been used in various fields. For example, Patent Document 1 discloses a technology for performing drawing laser irradiation in any direction by rotating a line beam with a line beam rotation unit and moving the irradiation target in the X and Y directions. Furthermore, Patent Document 2 discloses a laser marking system that modulates the intensity distribution of a beam expanded in one direction and performs printing processing with the modulated beam. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-4877 [Patent Document 2] Japanese Patent Application Publication No. 2023-231 [Overview of the Initiative] [Problem to be solved by the invention]

[0004] Incidentally, when drawing with a laser beam, the output power of the laser beam is adjusted in advance. For example, when drawing letters or a logo on the surface of a semiconductor package by irradiating the surface with a laser beam, an operator first places multiple samples made of the same material as the surface of the semiconductor package in the drawing device and draws on each sample under multiple laser output conditions. Next, the operator visually observes the drawing state on the samples and identifies the sample with the most appropriate drawing state, thereby determining the output power of the laser beam.

[0005] However, the surface condition of the sample (including surface shape such as surface roughness) is not necessarily the same as the surface condition of the semiconductor package on which the image will actually be drawn, and if the surface conditions of the two are significantly different, the image will not be drawn properly on the semiconductor package. In this case, readjustment of the laser output is required, resulting in downtime when the image cannot be drawn.

[0006] The present invention has been made in view of the above-mentioned problems, and has as its object to perform appropriate drawing while suppressing the influence of the surface shape of the drawing target. [Means for solving the problem]

[0007] A first aspect of the present invention is a drawing device that draws by irradiating light, comprising a laser light source, a modulator that modulates the light beam from the laser light source, a movement mechanism that moves the irradiation position of the light beam guided from the modulator on the drawing object, and a control unit that controls the modulator and the movement mechanism, and the control unit determines the intensity of the light beam on the drawing object based on the amplitude of spatial frequencies in the surface shape of the drawing object that are higher than 1 / 2 the frequency of the light beam.

[0008] A second aspect of the present invention is a drawing device of the first aspect, wherein the control unit determines the intensity of the light beam on the drawing object based on the amplitude of the spatial frequency in the surface shape of the drawing object that is higher than the frequency of the light beam.

[0009] Aspect 3 of the present invention is a drawing device of aspect 1 (which may be aspect 1 or 2), in which the control unit determines the intensity of the light beam on the drawing object based on the integrated value of the amplitude of spatial frequencies in the surface shape of the drawing object that are higher than a specific spatial frequency that is between 1 / 2 and 2 times the frequency of the light beam.

[0010] A fourth aspect of the present invention is the drawing device of the first aspect (which may be any one of the first to third aspects), further comprising a measurement unit that measures the surface shape of the drawing target and inputs the measurement results to the control unit.

[0011] Aspect 5 of the present invention is a drawing apparatus according to Aspect 1 (which may be any one of Aspects 1 to 4), wherein the spatial frequency is a two-dimensional spatial frequency relating to mutually orthogonal row and column directions on the drawing object, and the control unit determines the intensity of the light beam on the drawing object based on the amplitude of the spatial frequency in the surface shape of the drawing object, where the amplitude of the spatial frequency is higher than half the frequency of the light beam in at least one of the row and column directions.

[0012] Aspect 6 of the present invention is a drawing apparatus according to Aspect 1 (which may be any one of Aspects 1 to 5), wherein the object to be drawn is metal.

[0013] A seventh aspect of the present invention is the imaging device of the first aspect (which may be any one of the first to sixth aspects), wherein the imaging target is a package of a semiconductor device.

[0014] Aspect 8 of the present invention is a drawing apparatus according to any one of aspects 1 to 7, further comprising a rotor for rotating a light beam led from the modulator, wherein the modulator spatially modulates a light beam from the laser light source, the moving mechanism moves the irradiation position of the light beam led from the rotor on the drawing object, the control unit controls the modulator, the rotor and the moving mechanism, the modulator controls the ON / OFF of light irradiation to each spot in a linearly arranged row of spots on the drawing object, the rotor rotates the row of spots, and the moving mechanism moves the row of spots in a direction perpendicular to the direction of spot arrangement.

[0015] A ninth aspect of the present invention is a beam intensity determination method for determining the intensity of a light beam on a drawing object in a drawing device comprising a laser light source, a modulator that modulates a light beam from the laser light source, a moving mechanism that moves the irradiation position of the light beam guided from the modulator on the drawing object, and a control unit that controls the modulator and the moving mechanism, the method comprising the steps of acquiring the surface shape of the drawing object, and determining the intensity of the light beam on the drawing object based on the amplitude of spatial frequencies in the surface shape of the drawing object that are higher than 1 / 2 the frequency of the light beam. [Effects of the Invention]

[0016] According to the present invention, appropriate drawing can be performed. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of a drawing device. [Figure 2] FIG. [Figure 3] FIG. 2 is a diagram showing components of an optical head. [Figure 4] FIG. 1 illustrates a modulator. [Figure 5] FIG. 1 is a diagram showing a spot train. [Figure 6] FIG. 10 is a diagram showing how drawing is performed by a spot train. [Figure 7] FIG. 2 is a diagram illustrating a flow of basic operations of the drawing device. [Figure 8] FIG. 2 is a diagram showing the configuration of a measurement unit. [Figure 9] 4 is a flowchart showing the measurement by the measurement unit and the operation of the control unit. [Figure 10] FIG. 10 is a diagram illustrating an example of a surface shape. [Figure 11] FIG. 10 is a diagram illustrating an example of an integrated value of the amplitude of a normalized frequency component. [Figure 12] FIG. 10 is a diagram showing the correlation between the sum of normalized amplitudes and absorptance. [Figure 13A]10 is an example of a surface image. [Figure 13B] 10 is another example of a surface image. DETAILED DESCRIPTION OF THE INVENTION

[0018] Figure 1 is a block diagram showing the schematic configuration of a drawing device 1 according to one embodiment of the present invention. The drawing device 1 comprises a drawing unit 101 and a measuring unit 102. Note that the measuring unit 102 is not required to be included in the drawing device 1. The drawing unit 101 includes a control unit 3, which controls the laser light source 21, modulator 23, rotor 25, and moving mechanism 26, which will be described later. The control unit 3 includes an FFT calculation unit 31 and a beam intensity determination unit 32. The functions of the FFT calculation unit 31 and the beam intensity determination unit 32 will be described later.

[0019] Figure 2 shows the drawing unit 101, and Figure 3 shows the components of the optical head 11 of the drawing unit 101 arranged in a straight line. The drawing device 1 is a device that performs drawing by irradiating a drawing object with light. The drawing unit 101 of the drawing device 1 is a so-called laser marking device and comprises a laser light source 21, an illumination optical system 22, a modulator 23, an imaging optical system 24, a rotator 25, and a moving mechanism 26. The laser light source 21 emits a light beam 81, which is laser light. In Figures 1 and 2, the light beam 81 is represented by the reference numeral 81 on the optical axis. The laser light source 21 may be provided outside the optical head 11, in which case the light emitted from the laser light source 21 is guided into the optical head 11.

[0020] The light beam 81 is incident on the illumination optical system 22, which shapes the cross-sectional shape of the light beam 81, that is, the shape of the cross-section of the light beam of the light beam 81 by a plane perpendicular to the optical axis, into a desired shape. Specifically, the illumination optical system 22 shapes the cross-section of the light beam of the light beam 81 into a roughly rectangular shaped beam that is long in one direction (hereinafter referred to as the "long axis direction") and guides it to the modulator 23. Thus, the cross-sectional shape of the shaped light beam 81 is a roughly rectangular shape that is long in the long axis direction and short in the short axis direction perpendicular to the optical axis and the long axis direction. The long axis direction and the short axis direction are perpendicular to the direction of the optical axis, that is, the direction of propagation of the light beam 81. The cross-sectional shape of the shaped light beam 81 can also be considered as a straight line extending in the long axis direction.

[0021] The illumination optical system 22 guides the light beam 81 to the modulator 23. The modulator 23 spatially modulates the light beam 81 from the laser light source 21. The configuration of the modulator 23 will be described later. The imaging optical system 24 forms an intermediate image 82 (see FIG. 3) of the modulator 23 at a predetermined position in front of the rotator 25.

[0022] The rotator 25 is a so-called image rotation optical system that can rotate the light beam by any angle around the optical axis. This rotates the light beam led from the modulator 23, and as will be described later, rotates the row of spots on the object to be drawn around an axis perpendicular to the surface of the object to be drawn. As the rotator 25, for example, an optical unit consisting of a dove prism (a trapezoidal image rotation prism with thickness) and a motor to rotate the dove prism, or an image rotation mirror unit that realizes the same function with multiple mirrors and motors to rotate each mirror, can be used.

[0023] The moving mechanism 26 is a so-called scanning optical system, and as shown in FIG. 3, has a lens 261, a pair of galvanometer mirrors 262 (the galvanometer mirror unit is illustrated as a rectangle in FIG. 3), and an fθ lens 263. The pair of galvanometer mirrors moves the irradiation position of the light beam 81 in the X and Y directions in FIG. 2. In FIG. 2, the target to be imaged is an upper surface 91 of a package 9 of a semiconductor device (hereinafter referred to as a "semiconductor package"). The upper surface 91 is parallel to the XY plane shown in FIG. 2 and perpendicular to the Z direction. Hereinafter, the upper surface 91 will be referred to as the "target to be imaged 91." The target to be imaged 91 is a metal surface. The moving mechanism 26 moves the irradiation position of the light beam 81, which is guided from the rotator 25, on the target to be imaged 91. In FIG. 2, a plurality of semiconductor packages 9 are arranged on a tray 92, and the moving mechanism 26 sequentially performs image drawing on the plurality of semiconductor packages 9.

[0024] 1 is, for example, a typical computer including a processor, a memory, an input / output unit, and a bus. The configuration of the control unit 3 may be changed in various ways. The control unit 3 controls at least the laser light source 21, the modulator 23, the rotator 25, and the movement mechanism 26. This controls the direction and movement of the modulated light beam 81 on the drawing target 91.

[0025] 4 is a diagram showing the modulator 23. The modulator 23 converts the light beam 81 from the illumination optical system 22 into a one-dimensional spatially modulated light beam 81. As the modulator 23, for example, a PLV (Planar Light Valve) that can perform modulation at high speed and can withstand kW-class laser light is used. Although the PLV is a two-dimensional spatial light modulator, the optical head 11 uses it as a one-dimensional spatial modulator.

[0026] Fig. 4 is a simplified diagram showing the structure of modulator 23, which is a PLV. Modulator 23 includes a plurality of substantially rectangular pixels 231 arranged in a matrix (i.e., two-dimensionally arranged) on a substrate (not shown). In modulator 23, the surfaces of the plurality of pixels 231 form modulation surface 234. In the example shown in Fig. 4, M pixels 231 are arranged in the vertical direction and N pixels 231 are arranged in the horizontal direction in the figure. The horizontal direction in Fig. 4 corresponds to the major axis direction of shaped light beam 81, and the vertical direction in Fig. 4 corresponds to the minor axis direction.

[0027] Each pixel 231 is a modulation mechanism including a fixed member 232 and a movable member 233. The fixed member 232 is a planar, approximately rectangular member fixed to the substrate, and has a substantially circular opening in the center. The movable member 233 is a substantially circular member provided in the opening of the fixed member 232. A fixed reflecting surface is provided on the upper surface of the fixed member 232 (i.e., the surface on the near side in the direction perpendicular to the paper surface in FIG. 4). A movable reflecting surface is provided on the upper surface of the movable member 233. The movable member 233 is movable in the direction perpendicular to the paper surface in FIG. 4.

[0028] In each pixel 231, the relative position of the fixed member 232 and the movable member 233 in the direction perpendicular to the paper surface in FIG. 4 is changed, so that the reflected light from the pixel 231 is switched between zeroth-order (diffracted) light (i.e., specularly reflected light) and non-zeroth-order diffracted light. In other words, in the pixel 231, the movable member 233 moves relative to the fixed member 232, so that light modulation using a diffraction grating is performed. The zeroth-order light emitted from the modulator 23 is guided to the drawing target 91 by the movement mechanism 26. In addition, the non-zeroth-order diffracted light (mainly first-order diffracted light) emitted from the modulator 23 is appropriately blocked so as not to reach the drawing target 91.

[0029] In the modulator 23, the diffraction state of reflected light from M pixels 231 (hereinafter also referred to as a "pixel column 230") arranged in a vertical row in FIG. 4 is the same. That is, when the reflected light from one pixel 231 is zero-order light, the reflected light from all other pixels 231 (i.e., M-1 pixels 231) in the pixel column 230 including that pixel 231 is also zero-order light. Also, when the reflected light from one pixel 231 is non-zero-order diffracted light, the reflected light from all other pixels 231 in the pixel column 230 including that pixel 231 is also non-zero-order diffracted light. That is, the modulator 23 does not perform modulation in the minor axis direction of the light beam 81, but performs modulation in the major axis direction. In this way, in the modulator 23, the M pixels 231 in one pixel column 230 (i.e., M modulation mechanisms) function as one modulation element corresponding to one unit space. The modulator 23 functions as a one-dimensional spatial light modulator having N modulation elements aligned in a row in the long axis direction of the light beam 81. In a preferred example, N is 1000 or more.

[0030] FIG. 5 is a diagram showing how a light beam 81 is irradiated onto a drawing target 91, showing a spot array 80 in which multiple spots 83 are linearly arranged. In FIG. 5, each spot 83 is represented by a square for convenience. Light from M pixels 231 in one pixel array 230 in FIG. 5 is directed so as to converge onto one spot 83 in FIG. 5. Thus, the modulator 23 controls (ON / OFF control or light intensity control) the irradiation of light onto each spot 83 in the spot array 80 in FIG. 5. The rotator 25 can rotate the spot array 80 on the drawing target 91 around an axis perpendicular to the surface of the drawing target 91, as indicated by arrow 841. The movement mechanism 26 also moves the spot array 80 in a direction perpendicular to the arrangement direction of the spots 83 (the direction indicated by arrow 842). The "perpendicular direction" here is not limited to a direction perpendicular to the arrangement direction of the spots 83 in the strict sense, but may be approximately perpendicular.

[0031] FIG. 6 is a diagram illustrating how drawing is performed by the spot array 80. Blank spots 83 indicate spots to which light is not guided, and hatched spots 83 indicate spots to which light is guided. As the spot array 80 moves to the right as indicated by arrow 843, drawing is performed in a region through which the spot array 80 passes (the region indicated by reference numeral 94, hereinafter referred to as the "passing region"), and in the region through which the spot array 80 passes (the region indicated by reference numeral 95, hereinafter referred to as the "drawing region"). Here, "drawing" refers to a change in the surface of the drawing target 91 by irradiation with light, i.e., processing. For example, it refers to causing a chemical or physical change in the surface material by heating or light irradiation, or removing a portion of the surface material by heating or light irradiation (which may also be included in the physical change). The "drawing region" is a set of positions to be drawn on the drawing target 91 (hereinafter referred to as "drawing positions"), and one drawing position is a unit of drawing by the spot 83.

[0032] 7 is a diagram showing the flow of the basic operation of the imaging device 1. First, the imaging device 1 moves the spot array 80 to a start position for performing the first imaging (step S11). However, in reality, at this stage, no light is guided to each spot 83, and therefore the pair of galvanometer mirrors of the moving mechanism 26 simply assume the corresponding posture.

[0033] Next, the movement of the spot array 80 is started by the movement mechanism 26 (step S12), and almost simultaneously, the modulator 23 modulates the light beam 81 (step S13). As a result, drawing is performed in a required area on the drawing target 91, as exemplified in FIG. 6. Note that steps S12 and S13 may be performed simultaneously, or step S13 may be performed immediately before step S12. In this case, control of the modulator 23 is started by step S13, but control is performed to maintain a state in which light is not guided to each spot 83 (i.e., an OFF state) until the movement of step S12 is started.

[0034] Once the predetermined drawing is performed, the modulation of the light beam 81 by the modulator 23 is stopped (step S14), and almost simultaneously, the movement of the spot row 80 is stopped by the movement mechanism 26 (step S15). This completes the drawing in one movement of the spot row 80, that is, the drawing in the first area that the spot row 80 passes through. Steps S14 and S15 may be performed simultaneously, or step S15 may be performed immediately before step S14. In this case, control is performed to maintain a state in which no light is directed to each spot 83 (i.e., OFF state) before the movement of the spot row 80 is stopped by step S15, and the control to maintain the OFF state ends after the movement of the spot row 80 is stopped.

[0035] If the next drawing is to be performed (step S16), the moving mechanism 26 moves the spot column 80 to the starting position for the next drawing (step S11). Then, steps S12 to S15 are executed to perform the desired drawing in the next passing area of ​​the spot column 80. Once the required number of drawings have been performed in the passing area, the drawing by the drawing device 1 is completed (step S16).

[0036] Figure 8 shows the configuration of the measurement unit 102 (see Figure 1). The measurement unit 102 is a so-called confocal laser microscope capable of measuring three-dimensional surface shapes. The measurement unit 102 comprises a laser light source 41, a collimating lens 42, a dichroic mirror 43, a pair of galvanometer mirrors 44 (in Figure 8, the galvanometer mirror unit is shown as a rectangle), an objective lens 45, a lens 46, a confocal pinhole plate 47, and a detector 48.

[0037] Laser light from laser light source 41 passes through collimator lens 42, is reflected by dichroic mirror 43, and is then guided to the object of observation (here, the surface of semiconductor package 9 held by holder 93, which is drawing object 91 in FIG. 2) via galvanometer mirror 44 and objective lens 45. The light reflected by the object of observation passes through objective lens 45, galvanometer mirror 44, dichroic mirror 43, and lens 46 and is guided to confocal pinhole plate 47. A pinhole is provided in confocal pinhole plate 47, and light that passes through the pinhole is detected by detector 48.

[0038] The laser light source 41 and the pinhole are in a confocal positional relationship, and by acquiring the light amount with the detector 48 while moving the focusing position of the laser light up and down with the objective lens 45, the height direction position (Z direction in FIG. 8) of the focusing point on the drawing target 91 can be acquired with high precision. Also, by acquiring the height direction position of the focusing point on the drawing target 91 while two-dimensionally scanning the focusing position on the drawing target 91 with the pair of galvanometer mirrors 44, that is, while moving the focusing point in the X direction and Y direction in FIG. 8, the shape of a minute two-dimensional area on the drawing target 91 (hereinafter simply referred to as "surface shape") can be acquired with high precision. The measurement results by the measurement unit 102 are input to the control unit 3.

[0039] 9 is a flowchart showing the measurement by the measurement unit 102 and the operation of the control unit 3. When the surface shape of the drawing target 91 is acquired by the measurement unit 102 as described above (step S21), information on the surface shape (so-called profile) is input to the FFT calculation unit 31 of the control unit 3 in FIG.

[0040] Figure 10 is an example of a surface shape, showing the surface shape of a 125 μm square area. The scale bar on the right shows the relationship between grayscale and height. The FFT calculation unit 31 performs a two-dimensional Fourier transform on the surface shape. In practice, since digital data is being handled, a two-dimensional discrete Fourier transform (2D DFT) is performed. The 2D DFT can be represented by summing each data point of the signal, and is shown in equation 1. As a result, the surface shape is transformed into a two-dimensional frequency space, and the amplitude spectrum of the spatial frequency is obtained (step S22).

[0041]

number

[0042] where X and Y are the number of rows and columns of the signal, f(x,y) is the two-dimensional input signal, F(u,v) is the two-dimensional Fourier transform of f(x,y), x and y are coordinates in the spatial domain, u and v are coordinates in the frequency domain, and i is the imaginary unit.

[0043] The results obtained by the 2D DFT are complex numbers, each containing amplitude and phase information. The real and imaginary parts of the complex number represent the amplitudes of the cosine and sine components, respectively, and by adding them together, the amplitude and phase of all frequency components of the signal can be obtained. Thus, the amplitude can be expressed as the absolute value of the complex number, and is represented by equation 2.

[0044]

number

[0045] where A(u,v) is the amplitude (i.e., the amplitude spectrum in frequency space), R(F(u,v)) is the real part of F(u,v), and i(F(u,v)) is the imaginary part of F(u,v).

[0046] Next, the beam intensity determination unit 32 of the control unit 3 calculates the integrated value S of the amplitude of the frequency components in the row and column directions of the amplitude spectrum A(u, v) by the calculations shown in Equations 3 and 4.v (v), S u Find (u).

[0047]

number

[0048]

number

[0049] Here, U and V are the maximum indices in the row direction (u direction) and column direction (v direction) in the frequency domain, respectively.

[0050] The beam intensity determination unit 32 further calculates the integrated value S v (v), S u (u) is the maximum integrated value max(S v ) and the maximum cumulative value in the column direction max(S u ) is normalized. This gives the integrated value S of the normalized frequency components for each row v. v '(v) and the integrated value S of the frequency components normalized for each column u u '(u) is obtained.

[0051]

number

[0052]

number

[0053] Figure 11 shows the integrated value S of the amplitude of the normalized frequency components. v (v) and the cumulative value S u The "integrated value of amplitude" is the sum of S'(u) in the column direction (vertical direction). v '(v) is the integrated value of the amplitude of each spatial frequency in the row direction (horizontal direction) at each position in the column direction, and S u'(u) is the integrated value of the amplitude of each spatial frequency in the column direction. When normalizing, the maximum integrated value of the amplitude of each spatial frequency excluding the spatial frequency 0 is taken as max(S v ),max(S u ) is normalized by finding the coefficient that sets it to 1.

[0054] The horizontal axis in Figure 11 represents the spatial frequency [1 / μm], and the vertical axis represents the "integrated value of normalized amplitude" in the column and row directions, i.e., the integrated value of the amplitude in the column direction multiplied by the coefficient in the column direction, and the sum of the amplitude in the row direction multiplied by the coefficient in the row direction.

[0055] Next, the beam intensity determination unit 32 calculates the sum S of the amplitude spectrum of the normalized high frequency components by the calculation shown in Equation 7. highfreq (Step S23). In Equation 7, c v ,c u are the column and row indices corresponding to the cutoff frequency fc [Hz]. The wavelength λc [μm] corresponding to the cutoff frequency fc is expressed using equation 8 with the speed of light c [m / s].

[0056]

number

[0057]

number

[0058] In equation 7, S total_v ' is the normalized integrated value S v '(v) - cutoff frequency c v The sum of the above frequencies is S total_u ' is the normalized column-wise integrated value S u '(u), the cutoff frequency c u The sum of the above frequencies is S total_v ' and S total_u The sum of ' is S highfreqIt is obtained as S. highfreq is the sum of the amplitude spectrum of the high frequency components of the surface shape acquired by the measurement unit 102. The cutoff frequency fc is predetermined as a spatial frequency higher than ½ the frequency of the light beam emitted from the laser light source 21 for drawing.

[0059] Next, the beam intensity determination unit 32 of the control unit 3 calculates the sum of the amplitudes S highfreq The intensity of the light beam 81 on the drawing target 91 is determined based on the sum S highfreq A table showing the relationship between the amplitude and the intensity of the light beam 81 (hereinafter referred to as "beam intensity") is prepared, and the beam intensity is determined from the sum of the amplitudes by referring to the table.

[0060] As described above, in the drawing device 1, the intensity of the light beam on the drawing target 91 is determined using the amplitude of a relatively high spatial frequency among the amplitudes of the spatial frequency of the surface shape of the drawing target 91. This makes it possible to perform appropriate drawing while suppressing the influence of the surface shape, even when the surface shape (surface state) of the drawing target 91 is different.

[0061] We now describe experimental results that show that the amplitude of relatively high spatial frequencies of surface features can be used to determine the intensity of a light beam.

[0062] FIG. 12 shows the cutoff frequency fc, which corresponds to the wavelength λc=1.064 [μm] of the laser light used for drawing, and the sum S of the normalized amplitudes of the high frequency components calculated by Equations 1 to 8. highfreq This figure shows the correlation between the absorption rate of various sample surfaces and the normalized amplitude. In Figure 12, the horizontal axis represents the absorption rate [%], and the vertical axis represents the sum of the high-frequency components of the normalized amplitude [arb.Unit]. Sample surfaces A to E have different surface shapes, but are made of the same Ni plating material. Here, as representative examples, surface images of sample A and sample C are shown in Figures 13A and 13B, respectively.

[0063] In Figure 12, the black circle and range of the error bars represent the median and ± standard deviation range of triplicate measurements. The dotted line indicates a linear fit using the least-squares method to evaluate data variability. The results in Figure 12 show a high correlation between the R-squared value of 0.973, indicating a correlation between the surface absorption rate (i.e., the laser beam intensity required for processing) and the high-frequency components of the sample's surface profile. Therefore, it is possible to determine the light beam intensity using the amplitude of the relatively high spatial frequency of the surface profile. This eliminates or simplifies the conventional process of determining the laser beam intensity when the part number of the target to be written is changed or when writing to a new lot, thereby improving process efficiency and ensuring proper writing.

[0064] The above operation is merely an example. When the spatial frequency is a two-dimensional spatial frequency in the row and column directions that are orthogonal to each other on the drawing target, the sum of only the amplitudes of the high-frequency components in the row and column directions may be used to determine the intensity of the light beam. Conversely, only the high-frequency components in the row direction or only the high-frequency components in the column direction may be used to determine the intensity of the light beam. Generally speaking, the beam intensity determination unit 32 of the control unit 3 determines the intensity of the light beam on the drawing target based on the amplitudes of spatial frequencies in the surface shape of the drawing target that are higher than half the frequency of the light beam in at least one of the row and column directions.

[0065] The surface shape used to determine the intensity of the light beam may be a one-dimensional shape along a predetermined straight line on the drawing target 91. In other words, the spatial frequency in the above description may be a one-dimensional spatial frequency. Therefore, to more generally express the operation of the beam intensity determination unit 32 of the control unit 3, the beam intensity determination unit 32 determines the intensity of the light beam on the drawing target 91 based on the amplitude of a spatial frequency in the surface shape of the drawing target 91 that is higher than half the frequency of the light beam. More preferably, the intensity of the light beam on the drawing target 91 is determined based on the amplitude of a spatial frequency in the surface shape of the drawing target 91 that is higher than the frequency of the light beam (i.e., by setting the cutoff frequency equal to the frequency of the light beam).

[0066] Note that "based on the amplitude of spatial frequencies higher than 1 / 2 the frequency of the light beam" does not mean that the amplitude of all spatial frequencies higher than 1 / 2 the frequency of the light beam is used, but rather that the amplitude of at least some spatial frequencies higher than 1 / 2 the frequency of the light beam is used. Other similar expressions can be interpreted in the same way.

[0067] Since the cutoff frequency is preferably approximately the wavelength of the laser light, it is preferable to determine the intensity of the light beam on the object to be drawn based on the integrated value of the amplitude of spatial frequencies higher than a specific spatial frequency that is between 1 / 2 and 2 times the frequency of the light beam, among the amplitudes of spatial frequencies on the surface shape of the object to be drawn 91. Since very high-frequency components have small amplitudes, they are included in the information for determining the intensity of the light beam in the above explanation, but since very high-frequency components do not contribute to the absorption rate of the light beam by the object to be drawn, such high-frequency components may be excluded from determining the intensity of the light beam.

[0068] In the drawing device 1, by providing the measurement unit 102, the intensity of the light beam can be determined inline, but the measurement unit 102 does not have to be included in the drawing device 1. In this case, the surface shape of the drawing target 91 that has been measured separately is input to the control unit 3.

[0069] The modulator 23 that spatially modulates the light beam from the laser light source 21 is not limited to a PLV, and various other modulators can be used. For example, a GLV (registered trademark) (Grating Light Valve) may be used as the modulator 23. The modulator 23 may be any device that can one-dimensionally spatially modulate a line beam (a light beam with a linear cross section). The spatial modulation may be performed by only controlling ON / OFF for each modulation unit, or by controlling modulation to an arbitrary light intensity.

[0070] The rotator 25 rotates the spot array 80 on the drawing target 91 around an axis perpendicular to the surface of the drawing target 91, but the axis of the rotation center does not need to be perpendicular in the strict sense to the surface of the drawing target 91. Depending on the arrangement of optical elements, the axis of the rotation center may be slightly inclined with respect to the normal to the surface, as long as it is substantially perpendicular to the surface of the drawing target 91.

[0071] The movement mechanism 26 may have various configurations as long as it can move the irradiation position of the light beam 81 guided from the rotator 25 on the drawing target 91. For example, a mechanism that moves the drawing target 91 two-dimensionally in the horizontal direction relative to the optical head 11 may be used as the movement mechanism. Alternatively, the light beam 81 may be movable in one direction, and the drawing target 91 may be movable in a horizontal direction perpendicular to the above direction. In this way, the movement mechanism moves the irradiation position of the light beam 81 relatively on the drawing target 91.

[0072] In the above description, the intensity of the laser light on the drawing target is controlled by the modulator 23, but the intensity of the laser light may be changed by controlling the laser light source 21.

[0073] The laser light used for drawing in the drawing device 1 is not limited to a line beam. A light beam with a single point irradiation area on the drawing target may also be used. In such a device, the modulator only turns the laser light on and off or changes the light intensity. Also, the rotator is omitted, and the movement mechanism moves the irradiation position of the light beam guided from the modulator on the drawing target, and the control unit controls the modulator and the movement mechanism.

[0074] The surface to be drawn on is preferably metal, but is not limited to metal. For example, resin (e.g., the surface of a semiconductor resin package) or glass (e.g., the surface of a glass substrate) may also be the surface to be drawn on.

[0075] The configurations in the above-described embodiment and each modification may be combined as appropriate as long as they are not mutually contradictory. [Explanation of symbols]

[0076] 1 Drawing device 3. Control Unit 9 Semiconductor Package 21 Laser light source 23 Modulator 25 Rotator 26 Moving mechanism 80 Spot Row 81 Light Beam 83 spots 91 Drawing Target 102 Measuring section S21~S24 steps

Claims

1. A drawing device that draws by irradiating light, a laser light source; a modulator that modulates the light beam from the laser light source; a moving mechanism for moving an irradiation position of the light beam guided from the modulator on a drawing target; a control unit that controls the modulator and the movement mechanism; Equipped with A drawing device in which the control unit determines the intensity of the light beam on the drawing object based on the amplitude of spatial frequencies in the surface shape of the drawing object that are higher than 1 / 2 the frequency of the light beam.

2. 2. The drawing device according to claim 1, A drawing device in which the control unit determines the intensity of the light beam on the drawing object based on the amplitude of the spatial frequency in the surface shape of the drawing object that is higher than the frequency of the light beam.

3. 2. The drawing device according to claim 1, A drawing device in which the control unit determines the intensity of the light beam on the drawing object based on the integrated value of the amplitude of spatial frequencies in the surface shape of the drawing object that are higher than a specific spatial frequency that is between 1 / 2 and 2 times the frequency of the light beam.

4. 2. The drawing device according to claim 1, The drawing apparatus further comprises a measurement unit that measures the surface shape of the drawing target and inputs the measurement results to the control unit.

5. 2. The drawing device according to claim 1, the spatial frequency is a two-dimensional spatial frequency in a row direction and a column direction which are orthogonal to each other on the rendering target, A drawing device in which the control unit determines the intensity of the light beam on the drawing object based on the amplitude of the spatial frequency in the surface shape of the drawing object, which is higher than 1 / 2 the frequency of the light beam in at least one of the row direction and the column direction.

6. 2. The drawing device according to claim 1, The imaging device is configured so that the imaging target is a metal.

7. 2. The drawing device according to claim 1, The imaging device, wherein the imaging target is a package of a semiconductor device.

8. 8. The drawing device according to claim 1, a rotator for rotating the light beam directed from the modulator; the modulator spatially modulates the light beam from the laser light source; the moving mechanism moves an irradiation position of the light beam guided from the rotator on the drawing target; the control unit controls the modulator, the rotator, and the moving mechanism; The modulator controls ON / OFF of light irradiation to each spot of a spot array arranged in a linear pattern on the target to be drawn, the rotator rotates the spot array, and the movement mechanism moves the spot array in a direction perpendicular to the spot arrangement direction.

9. A beam intensity determination method for determining an intensity of a light beam on a drawing target in a drawing device including a laser light source, a modulator that modulates a light beam from the laser light source, a movement mechanism that moves an irradiation position of the light beam guided from the modulator on the drawing target, and a control unit that controls the modulator and the movement mechanism, comprising: acquiring a surface shape of the drawing target; determining an intensity of the light beam on the object to be drawn based on an amplitude of a spatial frequency higher than half the frequency of the light beam, among amplitudes of spatial frequencies in a surface shape of the object to be drawn; A beam intensity determination method comprising:

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