Laser processing device and laser processing method

Abstract

A laser annealing device 1 for performing annealing treatment by irradiating a semiconductor wafer 3 with a laser L includes an intensity variable optical system for varying a two-dimensional intensity distribution in an irradiation spot SP of the laser L on the semiconductor wafer 3 along at least an X direction within an intensity range equal to or higher than a threshold required for the annealing treatment. The intensity variable optical system periodically varies the two-dimensional intensity distribution along at least the X direction within the intensity range equal to or higher than the threshold. The ratio of a standard deviation to an average value of the intensity of the irradiation spot SP in the X direction is between 2% and 30%.

Description

Laser processing apparatus, laser processing method

[0001] The present disclosure relates to a laser processing apparatus and the like.

[0002] Patent Document 1 discloses a laser annealing apparatus that equalizes the energy distribution of a laser using a homogenizer.

[0003] Japanese Patent Application Laid-Open No. 7-266064

[0004] If the energy distribution of the laser cannot be completely equalized by the homogenizer, slight intensity unevenness may remain, which may deteriorate the appearance of the wafer after the annealing process.

[0005] The present disclosure has been made in view of such a situation, and an object thereof is to provide a laser processing apparatus and the like that can improve the appearance of a workpiece.

[0006] In order to solve the above problems, a laser processing apparatus according to an aspect of the present disclosure is a laser processing apparatus that performs a predetermined process by irradiating a workpiece with a laser, and includes an intensity variation optical system that varies a two-dimensional intensity distribution within a laser irradiation spot on the workpiece at least along a first direction within an intensity range equal to or higher than a threshold value required for the process.

[0007] In this aspect, the two-dimensional intensity within the laser irradiation spot on the workpiece is intentionally varied by the intensity variation optical system. This variation is preferably minute enough not to be perceived as deterioration of the appearance of the workpiece by the naked eye, and may appear as minute stripe patterns on the workpiece, for example. By intentionally adding (or superimposing) such variations, even if there is extensive intensity unevenness in the irradiation spot, the possibility of being visually perceived as unevenness in appearance is reduced. Note that the above-described variation in laser intensity is performed within an intensity range equal to or higher than a threshold value required for a predetermined process (for example, an annealing process), so that the appearance of the workpiece can be improved without hindering the process itself.

[0008] Another aspect of the present disclosure is a laser processing method. This method is a laser processing method that performs a predetermined processing on an object to be processed by irradiating it with a laser, wherein the two-dimensional intensity distribution within the laser irradiation spot on the object to be processed is varied along at least a first direction within an intensity range above a threshold required for processing.

[0009] Furthermore, any combination of the above components, as well as any representations thereof converted into methods, apparatus, systems, recording media, computer programs, etc., are also included in this disclosure.

[0010] According to this disclosure, the appearance of the processed object can be improved.

[0011] A schematic diagram of the configuration of the laser annealing apparatus is shown. A schematic diagram of the rectangular irradiation spot is shown. A schematic and exaggerated diagram of the intensity distribution in the X and / or Y directions of the rectangular laser irradiation spot on a semiconductor wafer in a comparative example laser annealing apparatus is shown. A schematic and exaggerated diagram of the intensity distribution in the X and / or Y directions of the rectangular laser irradiation spot on a semiconductor wafer in a laser annealing apparatus according to this embodiment is shown. A schematic diagram of the configuration of the second molding element is shown. An example of the appearance of a semiconductor wafer after annealing treatment by the laser annealing apparatus according to this embodiment is shown.

[0012] The following describes in detail the forms for implementing this disclosure (hereinafter also referred to as embodiments) with reference to the drawings. In the description and / or drawings, identical or equivalent components, members, processes, etc., are denoted by the same reference numerals, and redundant descriptions are omitted. The scale and shape of the illustrated parts are set for convenience to simplify the description and are not to be interpreted restrictively unless otherwise specified. The embodiments are illustrative and do not limit the scope of this disclosure in any way. Not all features or combinations thereof presented in the embodiments are necessarily essential to this disclosure. For convenience, embodiments are presented by breaking them down into components for each function and / or group of functions that realize them. However, one component in an embodiment may actually be realized by a combination of multiple components as separate entities, and multiple components in an embodiment may actually be realized by a single component as a whole. Furthermore, multiple embodiments and modifications may be disclosed in parallel, and any components of each embodiment and / or modification may be combined in any manner as long as they do not interfere with each other's functions.

[0013] Figure 1 schematically shows the configuration of a laser annealing apparatus 1 as a laser processing apparatus according to an embodiment of the present disclosure. The laser annealing apparatus 1 is an apparatus that irradiates a semiconductor wafer 3 (placed on a wafer table not shown) as a workpiece with a laser L (or laser light L) oscillated by a laser apparatus 2 to perform an annealing process (heating process). The laser processing apparatus according to the present disclosure is not limited to the laser annealing apparatus 1, and may be any apparatus that irradiates any workpiece with a laser of any form to perform any processing, for example, a laser cutter that performs laser cutting on a workpiece.

[0014] The laser annealing apparatus 1 in the illustrated example is significantly simplified from the actual apparatus, and many components that are not mentioned in the description of this embodiment (for example, components for measuring the semiconductor wafer 3, components for transporting the semiconductor wafer 3, components for stopping the irradiation of the laser L in an emergency, a chamber for housing the semiconductor wafer 3, various optical elements not shown, and the control unit of the laser annealing apparatus 1) are omitted.

[0015] In the illustrated example, a relay lens unit 11 as a transmission optical system, a second molding element 14 and a first molding element 13 as an intensity variation optical system or a molding optical system, an irradiation lens 15, etc. are provided along the path of the laser L. As will be described later, these components 11 to 15, together with the laser device 2, constitute a laser irradiation unit that irradiates the semiconductor wafer 3, which is the workpiece, with the laser L. In addition to or in place of the above components 11 to 15, any other components (for example, an energy adjustment mechanism that adjusts the energy and energy density of the laser L emitted from the laser device 2 to a value suitable for the desired annealing process, a mask, etc.) may be provided between the laser device 2 and the semiconductor wafer 3, and their arrangement is also arbitrary.

[0016] In the following, the configuration and / or operation of the laser annealing apparatus 1 will be described based on a three-dimensional Cartesian coordinate system with mutually orthogonal X, Y, and Z axes as coordinate axes. For convenience, in the following, the X and Y directions will be considered horizontal (i.e., the XY plane is the horizontal plane), and the Z direction will be considered vertical. As will be described later, the laser L from the laser apparatus 2 is driven relative to the semiconductor wafer 3 in the XY plane under the control of the laser scanning unit 31.

[0017] For example, the semiconductor wafer 3 is driven in the X direction by the laser scanning unit 31 (in this case, the X direction is also referred to as the driving direction), and the laser L from the laser device 2 is scanned in the Y direction by the laser scanning unit 31 (in this case, the Y direction is also referred to as the scanning direction). The semiconductor wafer 3 may also be driven in the Z direction integrally with a lifting table (not shown) (in this case, the Z direction is also referred to as the lifting direction). This Z direction is also the incident direction in which the laser L is incident on the semiconductor wafer 3. For convenience, in the following, the X direction will also be referred to as the vertical direction, the Y direction as the horizontal direction, and the Z direction as the height direction.

[0018] The laser device 2 outputs a laser L of any wavelength or mode suitable for annealing a semiconductor wafer 3, under the control of a laser control unit (not shown). This laser L may be pulsed laser light with a predetermined repetition frequency or continuous wave laser light. In the case of pulsed laser light, the pulse width and period can be set arbitrarily, but a pulse width of, for example, 1 ns or more and less than 1000 ns is preferred. The wavelength of the laser L can also be selected arbitrarily, but for example, a laser L with wavelengths in the ultraviolet, green, or infrared regions may be used for annealing a semiconductor wafer 3. Alternatively, a laser L with a wavelength longer than the ultraviolet region may be used for annealing a semiconductor wafer 3. The laser device 2 according to this embodiment may be configured, for example, as a fiber laser device that oscillates laser pulses as the laser L through an optical fiber.

[0019] The laser L is emitted from the laser device 2, for example, in the Z direction. The laser annealing device 1, which guides this laser L to the semiconductor wafer 3, the object to be irradiated (work to be processed), is equipped with a relay lens unit 11, a second molding element 14, a first molding element 13, and an irradiation lens 15 in this order along the path of the laser L.

[0020] The schematicly illustrated relay lens unit 11 is an optical system that adjusts the laser L to a beam size suitable for the second shaping element 14 and the first shaping element 13. Each relay lens unit 11 may be responsible not only for transmitting the laser L, but also for at least part of adjusting the size (or diameter) of the laser L, shaping the laser L, and adjusting the intensity distribution of the laser L.

[0021] The first molding element 13 and the second molding element 14 constitute an optical system that combines the function of a molding optical system for shaping the cross-section of the laser L into a desired shape, and the function of an intensity variation optical system for varying the two-dimensional intensity distribution (in the XY plane) within the irradiation spot SP of the laser L on the semiconductor wafer 3 along the X direction as a first direction and / or the Y direction as a second direction. However, the molding optical system and the intensity variation optical system may be configured as separate optical systems provided at different positions along the path of the laser L. In the example of this embodiment, the first molding element 13 and the second molding element 14 as a molding optical system, or a molding optical system according to another embodiment (e.g., a homogenizer), shapes the XY cross-section of the laser L into a rectangle having a first side along the X direction and a second side along the Y direction. However, the molding optical system may shape the XY cross-section of the laser L into any shape (e.g., a circle or an ellipse) not limited to a rectangle. Note that the size adjustment and shaping of the laser L may be performed by a mask (not shown) having a size and / or shape suitable for the desired annealing process. The detailed configurations of the first molded element 13 and the second molded element 14 will be described later.

[0022] The irradiation lens 15 focuses the laser L, which is scanned relative to the semiconductor wafer 3 by the laser scanning unit 31, onto the semiconductor wafer 3 to be annealed. The laser L from the irradiation lens 15 is incident on the semiconductor wafer 3 in the Z direction. The laser L focused onto the semiconductor wafer 3 by the irradiation lens 15 in this way forms an irradiation spot SP of a predetermined shape on the semiconductor wafer 3. As described above, since the XY cross-section of the laser L in this embodiment is rectangular, the shape of the irradiation spot SP in the XY plane is also rectangular.

[0023] The irradiation spot SP on the semiconductor wafer 3 may be square, but in this embodiment, it is a long rectangle along the X direction, which is the first direction. As schematically shown in Figure 2, the rectangular irradiation spot SP has a long side with a first dimension A along the X direction and a short side with a second dimension B along the Y direction. However, in modified examples not shown, the rectangular irradiation spot SP may have a short side with a first dimension B along the X direction and a long side with a second dimension A along the Y direction. In this embodiment, the first dimension A is 1000 μm and the second dimension B is 200 μm, but other arbitrary dimension designs are possible in this disclosure. As schematically shown in Figure 2, the two-dimensional intensity distribution within the irradiation spot SP of the laser L is finely varied, for example, in a striped pattern along the X and / or Y directions by the first molding element 13 and the second molding element 14, which are described later as intensity variation optical systems.

[0024] The laser scanning unit 31 scans the laser L emitted from the irradiation lens 15 relative to the semiconductor wafer 3 along the X and Y directions (i.e., in the XY plane). In this embodiment, where the irradiation spot SP is a long rectangle along the X direction, the irradiation lens 15 may directly irradiate the semiconductor wafer 3 with a laser L having a rectangular cross-section, or the laser scanning unit 31 may rapidly drive a laser L with a small rectangular cross-section along the X direction to form a rectangular irradiation spot SP.

[0025] The laser scanning unit 31, which scans the laser L and the semiconductor wafer 3 relative to each other in the XY plane, may be composed of a galvanometer scanner, polygon mirror scanner, MEMS (Micro Electro Mechanical Systems) mirror, etc., which scans the laser L in the X and / or Y directions; it may be composed of a robot such as a robot hand or robot arm that drives in the X and / or Y directions while fixing or gripping the irradiation lens 15; or it may be composed of a drive device such as a stage device that drives the semiconductor wafer 3 in the X and / or Y directions.

[0026] The laser measurement unit 32 is a sensor capable of measuring the laser L before it is irradiated onto the semiconductor wafer 3, either online (i.e., during the annealing process) or offline. In particular, the laser measurement unit 32 in this embodiment is composed of a beam profiler or the like, capable of measuring the intensity distribution or intensity fluctuation along the X and / or Y directions in the XY cross-section of the laser L that has passed through the intensity fluctuation optical system, such as the first molding element 13 and the second molding element 14.

[0027] Figure 3 schematically and exaggeratedly shows the intensity distribution in the X and / or Y directions of a rectangular irradiation spot SP of the laser L on a semiconductor wafer 3 in a laser annealing apparatus according to a comparative example (for example, Patent Document 1). The horizontal axis represents the position in the X or Y direction, and the vertical axis represents the intensity of the laser L at each position. In this comparative example, a homogenizer is provided to equalize the two-dimensional intensity distribution of the laser L, but because the homogenization is incomplete, intensity unevenness remains, with the intensity changing gradually over a wide area across the entire width of the irradiation spot SP. As a result, as schematically shown in the appearance image at the top of Figure 3, appearance unevenness such as color shades remains on the semiconductor wafer 3.

[0028] In contrast, Figure 4 schematically and exaggeratedly shows the intensity distribution in the X and / or Y directions of the rectangular irradiation spot SP of the laser L on the semiconductor wafer 3 in the laser annealing apparatus 1 according to this embodiment. The horizontal axis represents position, the width of the irradiation spot SP in the X direction is A shown in Figure 2, and the width of the irradiation spot SP in the Y direction is B shown in Figure 2. In this embodiment, the first molding element 13 and / or the second molding element 14 (Figure 1) as an intensity variation optical system causes the two-dimensional intensity distribution within the irradiation spot SP of the laser L on the semiconductor wafer 3 to fluctuate finely in a wave-like or sawtooth pattern along the X direction as the first direction and / or the Y direction as the second direction, within an intensity range above the threshold TH required for annealing (i.e., above the threshold TH in Figure 4).

[0029] As a result, as schematically shown in the appearance image at the top of Figure 4, a striped pattern with fine color variations appears on the semiconductor wafer 3. The pitch P or period of this striped pattern is preferably minute to the naked eye, for example, between 1 μm and 100 μm, preferably between 1 μm and 50 μm, and more preferably between 1 μm and 10 μm. Expressed as a ratio of the 1000 μm long side A of the irradiation spot SP, the pitch P of the striped pattern is preferably between 0.1% and 10.0%, preferably between 0.1% and 5.0%, and more preferably between 0.1% and 1.0%. Similarly, expressing it as a ratio of the 200 μm short side B of the irradiation spot SP, the pitch P of the striped pattern is preferably between 0.5% and 50.0%, preferably between 0.5% and 25.0%, and more preferably between 0.5% and 5.0%.

[0030] As described above, minute stripe patterns are not perceived by the naked eye as deterioration of the appearance of the semiconductor wafer 3, or even if they are visible to the naked eye, they are perceived as giving regularity to the appearance. In this embodiment, by intentionally adding (or overlapping) such minute fluctuations or patterns, even if there is widespread intensity unevenness in the irradiation spot SP as in the comparative example in Figure 3, it is substantially overwritten or filled in by the stripe pattern as in Figure 4, thus reducing the possibility of it being perceived as visual unevenness in appearance. Furthermore, since the intensity fluctuations of the laser L described above are performed within an intensity range above the threshold TH required for the annealing process, the appearance of the semiconductor wafer 3 can be improved without hindering the annealing process itself.

[0031] As schematically shown in Figure 4, at both ends LP and RP of the irradiation spot SP or rectangular laser beam L (left end LP and right end RP in Figure 4), there are regions where the intensity is less than the threshold TH (or, the regions where the intensity is below the threshold TH may be defined as the left end LP and right end RP). For this reason, irradiating only the ends LP and RP once is insufficient to properly anneal the semiconductor wafer 3. Therefore, as will be described later, it is preferable to overlap the ends LP and RP of two adjacent rectangular laser beams L in the XY plane (for example, irradiating the same position or region on the semiconductor wafer 3 with the right end RP of the "left" rectangular laser beam L and the left end LP of the "right" rectangular laser beam L overlapping), so that the overlapping irradiation region is also irradiated with a laser L with a total intensity exceeding the threshold TH (i.e., proper annealing is performed).

[0032] On the other hand, the central portion CP sandwiched between the LP and RP at both ends of the irradiation spot SP or rectangular laser beam L occupies at least 50% of the width of the irradiation spot SP (the long side A or short side B mentioned above), and its intensity exceeds the threshold TH throughout the entire area. Therefore, in order to perform proper annealing, irradiation of the central portion CP once is sufficient. If the central portion CP is irradiated in overlapping directions at the same position or region on the semiconductor wafer 3, excessive heat or energy will be supplied to the area to be annealed, which may lead to deterioration of quality such as the adhesion of the silicide (alloy) to be formed by the annealing process, or detachment or alteration of the film or components to be bonded by the annealing process.

[0033] Therefore, it is preferable that the central CP is not irradiated with overlap in either the X or Y direction. In other words, it is preferable that overlap irradiation be performed only on the aforementioned end LP and RP. In this case, the overlap rate (the ratio of overlapping end LP and RP to the width of the irradiation spot SP (long side A or short side B)) will vary depending on the dimensions of each end LP and RP, but as an example, the overlap rate on the long side A (X direction) is about 4%, and the overlap rate on the short side B (Y direction) is about 20%.

[0034] As described above, the intensity at the central part CP of the irradiation spot SP or rectangular laser beam L fluctuates along the X and / or Y directions within an intensity range above the threshold TH required for annealing. Here, if the average value of the intensity at the central part CP is μ, then μ > TH. Also, the minimum value of the intensity at the central part CP is above the threshold TH. The wavy or sawtooth intensity fluctuation at the central part CP needs to be large enough to obtain the appearance improvement effect described above, while being small enough not to adversely affect the actual annealing process. The preferred range of such fluctuation can be quantified, for example, by the ratio σ / μ (%) of the standard deviation σ (schematically shown in Figure 4) to the average value μ of the central part CP. Specifically, σ / μ (%) is preferably between 2% and 30%, more preferably between 2% and 20%, and even more preferably between 2% and 10%.

[0035] Furthermore, while the intensity fluctuation pattern in the central CP is preferably periodic or regular, as illustrated in Figure 4, it may be aperiodic or irregular (or random) as long as the aforementioned appearance improvement effect is obtained. As is clear from comparing Figure 3 of the comparative example with Figure 4 of this embodiment, this embodiment can be understood as obtaining the desired appearance improvement effect by substantially overwriting or filling in the low spatial frequency intensity unevenness in the comparative example with a high spatial frequency intensity fluctuation pattern. Thus, this disclosure encompasses various embodiments in which, regardless of the periodicity and / or regularity of the intensity fluctuation pattern, intensity fluctuation components with higher spatial frequencies than the wide-area intensity unevenness of the irradiation spot SP as in the comparative example are intentionally introduced or mixed in by an intensity fluctuation optical system such as the first molding element 13 and / or the second molding element 14.

[0036] The intensity fluctuation pattern in the central CP, as illustrated in Figure 4, is introduced by the first molding element 13 and / or second molding element 14, which function as an intensity fluctuation optical system as shown in Figure 1. The first molding element 13 forms the irradiation spot SP in at least the X direction as a first direction, and the second molding element 14 forms the irradiation spot SP in at least the Y direction as a second direction.

[0037] The first shaping element 13 comprises a pair of first lens arrays 131 and 132, as schematically shown in Figure 1, in which a large number of microlenses are arranged (or aligned) along the X direction. Each microlens extends along the Y direction. The first lens array 131 on the input side of the laser L and the first lens array 132 on the output side of the laser L are positioned opposite each other on the path of the laser L, adjusting the energy or intensity distribution of the laser L in the X direction (the longitudinal direction of the laser L) and shaping the laser L in the X direction.

[0038] Such lens array pairs are also used in conventional homogenizers, but ideally, the goal is to obtain a uniform intensity distribution, as shown in the comparative example in Figure 3. In contrast, in this embodiment, a pair of first lens arrays 131 and 132 is used to obtain a non-uniform intensity distribution as shown in Figure 4 while shaping the laser L into a desired shape such as a rectangle. The pitch P (X direction) of the periodic intensity fluctuation in Figure 4 can be adjusted or controlled by the width (X direction) of each microlens in the first lens arrays 131 and 132, based on the following formula: pitch P = focal length of the irradiation lens 15 × wavelength of the laser L ÷ width of each microlens (X direction). Note that the width of each microlens in this embodiment is smaller than the width of each microlens in a conventional homogenizer. Reducing the width of each microlens makes it easier for wavy or sawtooth-like fringe patterns, as illustrated in Figure 4, to appear.

[0039] Similarly, the second shaping element 14 comprises a pair of second lens arrays 141, 142, each having a number of microlenses aligned along the Y direction, as schematically shown in Figures 1 and 5. Each microlens extends along the X direction. The second lens array 141 on the input side of the laser L and the second lens array 142 on the output side of the laser L are positioned opposite each other on the path of the laser L to adjust the energy or intensity distribution of the laser L in the Y direction (the short-length direction of the laser L) and to shape the laser L in the Y direction.

[0040] In this embodiment, a pair of second lens arrays 141 and 142 are used to obtain a non-uniform intensity distribution as shown in Figure 4 while shaping the laser L into a desired shape such as a rectangle. The pitch P (Y direction) of the periodic intensity fluctuation in Figure 4 can be adjusted or controlled by the width (Y direction) of each microlens in the second lens arrays 141 and 142, based on the following formula: pitch P = focal length of the irradiation lens 15 × wavelength of the laser L ÷ width of each microlens (Y direction).

[0041] The design and / or adjustment of the first molded element 13 and / or the second molded element 14 as described above is preferably carried out while referring to the measurement results of the laser L by the laser measurement unit 32. For example, the designer and / or adjuster of the first molded element 13 and / or the second molded element 14 preferably designs and / or adjusts the configuration and arrangement of each lens array, etc. in the first molded element 13 and / or the second molded element 14 so as to realize a desired intensity distribution and waveform, while referring to the measurement results of the intensity distribution of the laser L by the laser measurement unit 32 as shown in Figure 4.

[0042] In the above examples, the intensity variation optical system according to this disclosure was configured with a lens array pair similar to that of a conventional homogenizer, but it can be configured with any optical element as long as the intensity variation as illustrated in Figure 4 can be obtained. For example, the intensity variation optical system according to this disclosure may be configured with aspherical lenses or diffractive optical elements (DOEs), etc.

[0043] Figure 6 shows an example of the appearance of a semiconductor wafer 3 after annealing by the laser annealing apparatus 1 according to this embodiment. As described with respect to Figure 2, the laser annealing apparatus 1 sequentially forms rectangular irradiation spots SP on the semiconductor wafer 3, with the long side being the first dimension A along the X direction and the short side being the second dimension B along the Y direction. In the illustrated example, the laser scanning unit 31 in Figure 1 sequentially irradiates (or scans) the rectangular laser L (irradiation spot SP) along the Y direction.

[0044] As described above, in the sequential irradiation along the Y direction, the overlap rate of two adjacent irradiation spots SP in the Y direction is adjusted such that both end portions LP and RP in FIG. 4 overlap appropriately for the annealing process and the central portion CP does not overlap. For example, the overlap rate in the Y direction as the short-side direction is set to about 20%. Here, for setting the overlap rate, the laser scanning unit 31 may refer to the measurement result of the laser L by the laser measurement unit 32. By referring to the measurement result of the laser L by the laser measurement unit 32, the dimensions of both end portions LP and RP to be overlap-irradiated can be grasped, so that the overlap rate can be optimized.

[0045] When the Y-direction scan as described above is completed, the laser scanning unit 31 step-moves the rectangular laser L (irradiation spot SP) along the X direction. Also in this step movement along the X direction, the overlap rate of two adjacent irradiation spots SP in the X direction is adjusted such that both end portions LP and RP in FIG. 4 overlap appropriately for the annealing process and the central portion CP does not overlap. For example, the overlap rate in the X direction as the long-side direction is set to about 4%. Here, for setting the overlap rate, the laser scanning unit 31 may refer to the measurement result of the laser L by the laser measurement unit 32.

[0046] As schematically shown in FIG. 6, a stripe pattern due to the intentional intensity variation exemplified in FIG. 4 appears in each irradiation spot SP (in FIG. 6, only the "horizontal stripes" due to the intensity variation along the X direction, which is the long-side direction where the intensity unevenness is likely to be prominent as in FIG. 3, are exemplarily shown). Such minute stripe patterns cannot be perceived by the naked eye as a deterioration of the appearance of the semiconductor wafer 3, or even if they are reflected in the naked eye, they are perceived as giving regularity to the appearance. Therefore, according to the present embodiment, the appearance of the semiconductor wafer 3 can be improved.

[0047] In addition, secondary effects such as an improvement in the adhesion of the silicide (alloy) to be formed by the annealing process are also expected by the annealing process using the laser L with a striped intensity distribution.

[0048] As described above, the present disclosure has been explained based on embodiments. It is obvious to those skilled in the art that various modifications are possible for the combinations of each component and each process in the exemplary embodiments, and such modifications are included in the scope of the present disclosure.

[0049] In FIG. 2 and the like, a rectangular laser L or irradiation spot SP is illustrated, but the shape of the laser L or irradiation spot SP is arbitrary. For example, when the laser L or irradiation spot SP is circular or elliptical, the intensity fluctuation optical system according to the present disclosure may vary the two-dimensional intensity distribution within the irradiation spot SP of the laser L on the semiconductor wafer 3 along the radial direction and / or circumferential direction as the first direction and / or the second direction.

[0050] Note that the configurations, operations, and functions of each device and each method described in the embodiments can be realized by hardware resources or software resources, or by the cooperation of hardware resources and software resources. As hardware resources, for example, a processor, ROM, RAM, and various integrated circuits can be used. As software resources, for example, programs such as an operating system and an application can be used.

[0051] The present disclosure relates to a laser processing apparatus and the like.

[0052] 1 Laser annealing apparatus, 2 Laser apparatus, 3 Semiconductor wafer, 13 First shaping element, 14 Second shaping element.

Claims

1. A laser processing apparatus that performs a predetermined process on an object to be processed by irradiating it with a laser, the laser processing apparatus comprising an intensity variation optical system that varies the two-dimensional intensity distribution within the laser irradiation spot on the object to be processed along at least a first direction within an intensity range of a threshold or higher required for the process.

2. The laser processing apparatus according to claim 1, wherein the intensity variation optical system periodically varies the two-dimensional intensity distribution within an intensity range above the threshold, along at least a first direction.

3. The laser processing apparatus according to claim 1, wherein the ratio of the standard deviation of the intensity of the irradiation spot in the first direction to the mean value is between 2% and 30%.

4. The laser processing apparatus according to claim 1, wherein the intensity variation optical system varies the two-dimensional intensity distribution along a second direction orthogonal to the first direction within an intensity range of the threshold or higher.

5. The laser processing apparatus according to any one of claims 1 to 4, wherein the intensity-variable optical system forms the irradiation spot such that the first dimension along the first direction is larger than the second dimension along the second direction perpendicular to the first direction.

6. The laser processing apparatus according to claim 5, wherein the intensity-variable optical system forms the irradiation spot into a rectangle with the first dimension being the longer side and the second dimension being the shorter side.

7. The laser processing apparatus according to claim 5, wherein the intensity variation optical system comprises a first molding element for shaping the irradiation spot in at least the first direction, and a second molding element for shaping the irradiation spot in at least the second direction.

8. The laser processing apparatus according to claim 7, wherein the first molding element comprises a pair of first lens arrays in which a plurality of lenses are arranged along the first direction, and the second molding element comprises a pair of second lens arrays in which a plurality of lenses are arranged along the second direction.

9. The laser processing apparatus according to any one of claims 1 to 4, further comprising a laser scanning unit that scans the laser relative to the workpiece along at least a second direction perpendicular to the first direction.

10. The laser processing apparatus according to claim 9, wherein the laser scanning unit scans the laser relative to the workpiece along the first direction.

11. The laser processing apparatus according to any one of claims 1 to 4, wherein the processing is an annealing process of the workpiece using the laser.

12. A laser processing method comprising irradiating an object to be processed with a laser to perform a predetermined process, wherein the two-dimensional intensity distribution within the laser irradiation spot on the object to be processed is varied along at least a first direction within an intensity range of a threshold or higher required for the processing.

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