Laser processing equipment, laser processing method

Abstract

The present invention provides a laser processing device that can use multiple lasers in combination while reducing the effects of reflected light. [Solution] The laser annealing apparatus 1 includes a first laser apparatus 21 that irradiates a first laser L1p having p polarization toward a semiconductor wafer 3 along the irradiation direction, a second laser apparatus 22 that irradiates a second laser having s polarization toward a semiconductor wafer 3 along the irradiation direction, a polarizing element 41 that directs the first laser L1p and the second laser, which are incident from different directions, toward a common irradiation direction toward the semiconductor wafer 3, an irradiation control unit 71 that stops the irradiation of the laser by the second laser apparatus 22 when the first laser apparatus 21 irradiates the semiconductor wafer 3 with the first laser L1p, and a second shielding unit 6 that shields the reflected light L1s having s polarization from the semiconductor wafer 3 from the second laser apparatus 22 while the first laser apparatus 21 is irradiating the semiconductor wafer 3 with the first laser L1p.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a laser annealing apparatus that recrystallizes a silicon thin film using one laser device.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In one laser device, the output of the laser annealing apparatus may be insufficient. In order to increase the output of the laser annealing apparatus, it is conceivable to use two laser devices, but it is necessary to "synthesize" the two lasers into substantially one laser. Further, as a new problem, the problem of "return light" has also been confirmed, in which the laser emitted from one laser device is reflected by the object to be processed and returns to the other laser device, causing damage or the like.

[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 use a plurality of lasers in combination while reducing the influence of return light.

Means for Solving the Problems

[0006] To solve the above problems, a laser processing apparatus according to one aspect of the present disclosure includes: a first laser apparatus that irradiates a workpiece with a first polarization along the irradiation direction with a first laser; a second laser apparatus that irradiates a workpiece with a second polarization different from the first polarization along the irradiation direction with a second laser; a polarizing element that directs the first and second lasers incident from different directions in a common irradiation direction toward the workpiece; an irradiation control unit that stops the irradiation of the laser by the other laser apparatus when one of the first and second laser apparatuses irradiates a workpiece with a laser; and a second shielding unit that shields the reflected light having the second polarization from the workpiece from the second laser apparatus while the first laser apparatus is irradiating the workpiece with the first laser.

[0007] According to this embodiment, by using a polarizing element to direct the first laser and the second laser, which have different polarizations, toward a common irradiation direction toward the workpiece, they can be treated as substantially a single laser. Furthermore, according to this embodiment, while the first laser device is irradiating the workpiece with the first laser, the reflected light from the workpiece having the second polarization can be safely shielded by the second shielding unit from the second laser device when irradiation is stopped.

[0008] Another aspect of the present disclosure is a laser processing method. This method involves: irradiating a workpiece with a first laser having a first polarization along the irradiation direction using a first laser device; irradiating a workpiece with a second laser having a second polarization different from the first polarization along the irradiation direction using a second laser device; directing the first and second lasers incident from different directions towards a common irradiation direction toward the workpiece using a polarizing element; stopping the irradiation of the laser by the other laser device when one of the first and second laser devices irradiates the workpiece with a laser; and shielding the reflected light having the second polarization from the workpiece from the second laser device while the first laser device is irradiating the workpiece with a first laser.

[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. [Effects of the Invention]

[0010] According to this disclosure, multiple lasers can be used in combination while reducing the effects of reflected light. [Brief explanation of the drawing]

[0011] [Figure 1] A schematic diagram of the laser annealing apparatus during the first laser irradiation period is shown. [Figure 2] A schematic diagram of the laser annealing apparatus during the second laser irradiation period is shown. [Figure 3] The first shielding section is schematically shown. [Figure 4] A schematic diagram of the laser annealing apparatus during the first laser irradiation period is shown. [Figure 5] A schematic diagram of the laser annealing apparatus during the second laser irradiation period is shown. [Modes for carrying out the invention]

[0012] The following describes in detail the forms (hereinafter also referred to as embodiments) for carrying out this disclosure, 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 in order 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 this disclosure. The laser annealing apparatus 1 is an apparatus that irradiates a semiconductor wafer 3 (placed on a wafer table T) as a workpiece with a laser or laser light L (a collective term for the first laser L1 and second laser L2 described later) oscillated by a laser apparatus 2 (a collective term for the first laser apparatus 21 and second laser apparatus 22 described later) to perform an annealing process (heating process). Note that the laser processing apparatus according to this disclosure is not limited to the laser annealing apparatus 1, and any apparatus that irradiates any workpiece with a laser of any form to perform any processing may be used. For example, a laser exposure apparatus that performs laser lithography (exposure) on a workpiece may also be used.

[0014] The laser annealing apparatus 1 in the illustrated example is significantly simplified from the actual apparatus, and many components that cannot be described in detail in this embodiment (for example, a laser scanning unit that moves the laser L and semiconductor wafer 3 relative to each other, components for measuring the laser L and 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, and various optical elements such as lenses) are omitted.

[0015] In this embodiment, two laser devices 2 are provided as multiple laser devices 2: a first laser device 21 and a second laser device 22. Since these two laser devices 21 and 22 have a common basic configuration, the first laser device 21 will be described as representative of the laser devices 2. Therefore, the laser device 2 in the following description mainly refers to the first laser device 21, but this description also applies almost directly to the second laser device 22.

[0016] Similarly, in this embodiment, the first laser device 21 emits the first laser L1, and the second laser device 22 emits the second laser L2. As will be described later, it is preferable that the first laser L1 and the second laser L2 are substantially the same except for the difference in polarization. Therefore, the first laser L1 will be described as representative of the laser L. Accordingly, the laser L in the following description mainly refers to the first laser L1, but this description also applies almost directly to the second laser L2.

[0017] The laser device 2 irradiates a semiconductor wafer 3 as a workpiece with a laser L along the irradiation direction (rightward in FIG. 1). In the illustrated example, on the path of the laser L (for example, in FIG. 1, the linear path from the left first laser device 21 toward the right semiconductor wafer 3), a first shielding portion 5 (in the case of the second laser L2, a second shielding portion 6), polarization elements 41, and a quarter-wave plate 42 are arranged in this order. As long as at least a part of the operations and / or effects of the present embodiment described below are realized, some of these components may be omitted or modified, or additional components may be provided at any position on the path of the laser L. Examples of such additional components include a relay lens unit as a transmission optical system, a homogenizer as a shaping optical system, an irradiation lens, a mask, an energy adjustment mechanism, and the like.

[0018] Hereinafter, directions related to the configuration and / or operation of the laser annealing apparatus 1 will be described based on a three-dimensional orthogonal coordinate system with each of the X, Y, and Z axes orthogonal to each other as coordinate axes. Hereinafter, for convenience, it is assumed that the X direction and the Y direction are horizontal directions (that is, the XY plane is a horizontal plane), and the Z direction is a vertical direction. The laser L from the laser device 2 is relatively driven in the XY plane with respect to the semiconductor wafer 3 under the control of a laser scanning unit (not shown).

[0019] For example, the semiconductor wafer 3 is driven in the X direction (in this case, the X direction is also referred to as the driving direction) by a laser scanning unit (not shown), and the laser L from the laser device 2 is scanned in the Y direction (in this case, the Y direction is also referred to as the scanning direction) by a laser scanning unit (not shown). Further, the semiconductor wafer 3 may be driven in the Z direction integrally with an elevating table (not shown) (in this case, the Z direction is also referred to as the elevating direction). This Z direction is also the incident direction or the irradiation direction in which the laser L is incident on the semiconductor wafer 3. Hereinafter, for convenience, the X direction is also referred to as the longitudinal direction, the Y direction is also referred to as the lateral direction, and the Z direction is also referred to as the height direction.

[0020] The laser device 2 outputs a laser L of any wavelength or mode suitable for the annealing process of the semiconductor wafer 3 under the control of an irradiation control unit 71 described later. 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 arbitrarily set. For example, the pulse width is preferably 1 ns or more and less than 1000 ns. The wavelength of the laser L can also be arbitrarily selected. For example, a laser L with a wavelength in the ultraviolet region, green, or infrared region may be used for the annealing process of the semiconductor wafer 3. Also, a laser L with a wavelength longer than the ultraviolet region may be used for the annealing process of the semiconductor wafer 3. The laser device 2 according to this embodiment may be configured by, for example, a fiber laser device that oscillates a laser pulse or the like as the laser L by means of an optical fiber. The laser L emitted from the laser device 2 is irradiated onto the semiconductor wafer 3 along the Z direction as the irradiation direction after passing through a polarization element 41 or the like described later.

[0021] A laser scanning unit (not shown) relatively scans the laser L irradiated along the Z direction with respect to the semiconductor wafer 3 in the X direction and the Y direction (that is, within the XY plane) with respect to the semiconductor wafer 3. The laser scanning unit (not shown) that relatively scans the laser L and the semiconductor wafer 3 within the XY plane may be configured by a galvanometer scanner, a polygon mirror scanner, a MEMS (Micro Electro Mechanical Systems) mirror, etc. that scan the laser L in the X direction and / or the Y direction, or may be configured by a robot such as a robot hand or a robot arm that is driven in the X direction and / or the Y direction while fixing or gripping an irradiation lens or the like (not shown), or may be configured by a driving device such as a stage device that drives the semiconductor wafer 3 in the X direction and / or the Y direction.

[0022] In this embodiment, two laser devices 2, a first laser device 21 and a second laser device 22, are used in combination to increase the output of the laser annealing apparatus 1. The first laser L1 and the second laser L2 emitted by the first laser device 21 and the second laser device 22 are "combined" substantially coaxially by a polarizing element 41, utilizing the difference in their polarization directions. Therefore, the first laser device 21 and the second laser device 22 emit the first laser L1 and the second laser L2, which have linear polarization with different polarization directions. Note that the first laser device 21 itself may be composed of multiple (for example, two) laser devices, and the second laser device 22 itself may be composed of multiple (for example, two) laser devices.

[0023] The first laser L1 has a first polarization, which is either p-polarized light having a polarization direction parallel to the incident plane (in this embodiment, the ZX plane, which is the plane of the paper in Figure 1) containing the normal to the semiconductor wafer 3 and the incident light (both in the Z direction), or s-polarized light having a polarization direction perpendicular to the incident plane. The second laser L2 has a second polarization, which is the other of p-polarized and s-polarized light. In this embodiment, the first polarization of the first laser L1 is p-polarized, and the second polarization of the second laser L2 is s-polarized. However, the first laser L1 may contain an s-polarized component that is less than the p-polarized component, and the second laser L2 may contain a p-polarized component that is less than the s-polarized component.

[0024] As shown in Figure 1, the first laser device 21 irradiates the semiconductor wafer 3 with a first laser L1p having p-polarization (first polarization) along the Z direction as the irradiation direction. Here, the first laser device 21 may be composed of a combination of a laser oscillator that oscillates the laser and a half-wave plate or the like that controls the laser to p-polarization (similarly, the second laser device 22 may be composed of a combination of a laser oscillator that oscillates the laser and a half-wave plate or the like that controls the laser to s-polarization). In the illustrated state, the first light-transmitting portion 51 of the first shielding portion 5, which will be described later, is positioned on the optical path of the first laser L1p, so the first laser L1p can be transmitted without being shielded by the first shielding portion 5.

[0025] A polarizing element 41 is positioned downstream of the first shielding section 5. The polarizing element 41 is an optical element that has polarization properties that direct the first laser L1p and the second laser L2s (Figure 2), which are incident from different directions, toward a common irradiation direction (Z direction) toward the semiconductor wafer 3. The polarizing element 41 is composed of, for example, a polarizing beam splitter. In the illustrated example, the polarizing element 41 transmits p-polarized light from the first laser L1p, etc., in the left-right direction in Figure 1, and reflects s-polarized light from the second laser L2s (Figure 2), etc., between the X and Z directions (that is, it bends s-polarized light incident in the X direction by 90 degrees and reflects it toward the Z direction, and bends s-polarized light incident in the Z direction by 90 degrees and reflects it toward the X direction).

[0026] In the example shown in Figure 1, the first laser L1p, emitted as p-polarized light by the first laser device 21, passes through the polarizing element 41 and travels along the Z direction toward the semiconductor wafer 3. Between the polarizing element 41 and the semiconductor wafer 3, a quarter-wave plate 42 is placed to convert the linearly polarized (p-polarized) light of the first laser L1p into, for example, clockwise circularly polarized light L1r and irradiate the semiconductor wafer 3 with it.

[0027] In this way, a portion of the right-handed circularly polarized light L1r originating from p-polarization irradiated onto the semiconductor wafer 3 is reflected back to the quarter-wave plate 42 as left-handed circularly polarized light L1l. That is, the direction of rotation of the circularly polarized light is reversed before and after reflection by the semiconductor wafer 3. The quarter-wave plate 42 converts the circularly polarized light L1l of the reflected light from the semiconductor wafer 3 into linearly polarized light L1s and returns it to the polarizing element 41. Since the circularly polarized light L1l is left-handed (opposite direction to the right-handed circularly polarized light L1r originating from p-polarization), the linearly polarized light L1s after passing through the quarter-wave plate 42 becomes s-polarized light.

[0028] Such s-reflected light L1s is reflected by the polarizing element 41 and directed towards the second laser device 22 along the X direction. However, as will be described later, in the state shown in Figure 1, the second laser device 22, which is stopped from irradiating by the irradiation control unit 71, is safely shielded from the s-reflected light L1s by the second shielding unit 6.

[0029] As described above, according to this embodiment, the s-reflected light L1s having second polarization (s-polarization) from the semiconductor wafer 3 while the first laser device 21 shown in Figure 1 is irradiating the semiconductor wafer 3 with the first laser L1p / L1r (hereinafter also referred to as the first laser irradiation period) can be safely shielded by the second shielding unit 6 from the second laser device 22 when irradiation is stopped.

[0030] Figure 2 schematically shows the laser annealing apparatus 1 while the second laser apparatus 22 is irradiating the semiconductor wafer 3 with the second laser L2s / L2l (hereinafter also referred to as the second laser irradiation period). During this second laser irradiation period, the irradiation control unit 71 stops the irradiation of the first laser apparatus 21. In this way, when one of the first laser apparatus 21 or the second laser apparatus 22 irradiates the semiconductor wafer 3 with the laser L, the irradiation control unit 71 stops the irradiation of the laser L by the other of the first laser apparatus 21 or the second laser apparatus 22.

[0031] Specifically, the irradiation control unit 71 stops the irradiation of the second laser L2 by the second laser device 22 during the first laser irradiation period (Figure 1) when the first laser device 21 irradiates the semiconductor wafer 3 with the first laser L1, and stops the irradiation of the first laser L1 by the first laser device 21 during the second laser irradiation period (Figure 2) when the second laser device 22 irradiates the semiconductor wafer 3 with the second laser L2. The irradiation control unit 71 may alternately irradiate the first laser device 21 and the second laser device 22 with the laser L (i.e., the first laser irradiation period and the second laser irradiation period may be alternated).

[0032] As shown in Figure 2 during the second laser irradiation period, the second laser device 22 irradiates the semiconductor wafer 3 with a second laser L2s having s-polarization (second polarization) along the Z direction, which is the irradiation direction. Specifically, the second laser L2s emitted by the second laser device 22 along the X direction is reflected in the Z direction by the polarizing element 41. In the illustrated state, the second light-transmitting portion 61 of the second shielding portion 6, which will be described later, is positioned on the optical path of the second laser L2s, so the second laser L2s can be transmitted without being shielded by the second shielding portion 6.

[0033] In the example shown in Figure 2, the second laser L2s, emitted as s-polarized light by the second laser device 22, is reflected by the polarizing element 41 and directed towards the semiconductor wafer 3 along the Z direction. Between the polarizing element 41 and the semiconductor wafer 3, the aforementioned quarter-wave plate 42 is placed to convert the linearly polarized (s-polarized) second laser L2s into, for example, counterclockwise circularly polarized light L2l and irradiate the semiconductor wafer 3 with it.

[0034] In this way, some of the left-handed circularly polarized light L2l originating from s-polarization irradiated onto the semiconductor wafer 3 is reflected back to the quarter-wave plate 42 as right-handed circularly polarized light L2r. The quarter-wave plate 42 converts the circularly polarized light L2r of the reflected light from the semiconductor wafer 3 into linearly polarized light L2p and returns it to the polarizing element 41. Because the circularly polarized light L2r is right-handed (opposite direction to the left-handed circularly polarized light L2l originating from s-polarization), the linearly polarized light L2p after passing through the quarter-wave plate 42 becomes p-polarized light.

[0035] Such p-reflected light L2p passes through the polarizing element 41 and travels along the Z direction toward the first laser device 21. However, as will be described later, in the state shown in Figure 2, the first laser device 21, which is stopped from irradiating by the irradiation control unit 71, is safely shielded from the p-reflected light L2p by the first shielding unit 5.

[0036] As described above, according to this embodiment, the first shielding unit 5 can safely shield the first reflected light L2p having first polarization (p polarization) from the semiconductor wafer 3 while the second laser device 22 shown in Figure 2 is irradiating the semiconductor wafer 3 with the second laser L2s / L2l (second laser irradiation period).

[0037] Next, the first shielding section 5 and the second shielding section 6 according to this embodiment will be described. Since these two shielding sections 5 and 6 have a common basic configuration, the first shielding section 5 will be described as a representative shielding section. Therefore, the following description of the first shielding section 5 applies almost directly to the second shielding section 6 (for example, replace "first" with "second" and "5" with "6" in the symbols).

[0038] Figure 3 schematically shows the first shielding section 5 according to this embodiment in a ZX plan view and an XY plan view, similar to Figure 1. The first shielding section 5 shields the reflected light L2p having p polarization (first polarization) from the semiconductor wafer 3 from the first laser device 21 while the second laser device 22 is irradiating the semiconductor wafer 3 with the second laser L2s (Figure 2). The first shielding section 5 is deactivated while the first laser device 21 is irradiating the semiconductor wafer 3 with the first laser L1p (Figures 1 and 3).

[0039] For example, the first shielding portion 5 is a first light-shielding member that, as shown in Figure 2, is positioned in the optical path between the first laser device 21 and the polarizing element 41 to shield the reflected light L2p having p-polarization (first polarization) while the second laser device 22 is irradiating the semiconductor wafer 3 with the second laser L2s, and is removed from the optical path while the first laser device 21 is irradiating the semiconductor wafer 3 with the first laser L1p, as shown in Figures 1 and 3.

[0040] In the examples shown in Figures 1 and 3, one or more first light-transmitting portions 51 provided on the first shielding portion 5, which acts as a light-shielding member, are positioned on the optical path of the first laser L1p, thereby removing the first shielding portion 5 from the optical path and rendering it ineffective. The one or more first light-transmitting portions 51 are windows through which the first laser L1p and / or the measurement light S described later can pass, and may be formed as holes penetrating the first shielding portion 5.

[0041] As shown in Figure 3, the first shielding portion 5 may be a substantially disc-shaped member with an XY cross-section that is substantially circular. This substantially disc-shaped first shielding portion 5, which serves as a light-shielding member, may be rotationally driven by a first rotational drive unit 52 such as a motor around a first rotation axis 5A parallel to the optical path of the first laser L1p. One or more first light-transmitting portions 51 are provided in the substantially disc-shaped first shielding portion 5 at radial positions where the first laser L1p and / or measurement light S are irradiated. When multiple first light-transmitting portions 51 are provided, it is preferable that they be arranged at equal intervals along the circumferential direction (i.e., at equal angles with respect to the first rotation axis 5A).

[0042] When the first rotation drive unit 52 rotates the first shielding unit 5 at a substantially constant speed, one or more first light-transmitting units 51 are arranged at substantially constant intervals along the optical path of the first laser L1p and / or the measurement light S. That is, as shown in Figures 1 and 3, the light-transmitting state, in which the first laser L1p and / or the measurement light S are transmitted through any of the first light-transmitting units 51, and the light-shielding state, in which the reflected light L2p and / or the measurement light S are shielded by the first shielding unit 5 (the portion where the first light-transmitting units 51 are not provided), are switched substantially periodically. The number of first light-transmitting units 51 and their lengths along the circumferential direction can be appropriately adjusted according to the desired irradiation interval and irradiation time per irradiation of the first laser L1p.

[0043] Although detailed illustrations are omitted (as shown in Figures 1 and 2), the second shielding unit 6 in this embodiment shields the reflected light L1s having s-polarization (second polarization) from the semiconductor wafer 3 from the second laser device 22 while the first laser device 21 is irradiating the semiconductor wafer 3 with the first laser L1p (Figures 1 and 3). The second shielding unit 6 is deactivated while the second laser device 22 is irradiating the semiconductor wafer 3 with the second laser L2s (Figure 2).

[0044] For example, the second shielding portion 6 is a second light-shielding member that, as shown in Figure 1, is positioned in the optical path between the second laser device 22 and the polarizing element 41 to shield reflected light L1s having s-polarization (second polarization) while the first laser device 21 is irradiating the semiconductor wafer 3 with the first laser L1p, and is removed from the optical path while the second laser device 22 is irradiating the semiconductor wafer 3 with the second laser L2s, as shown in Figure 2.

[0045] In the example shown in Figure 2, one or more second light-transmitting portions 61 provided in the second shielding portion 6, which acts as a light-shielding member, are positioned on the optical path of the second laser L2s, thereby removing the second shielding portion 6 from the optical path and rendering it ineffective. The one or more second light-transmitting portions 61 are windows through which the second laser L2s and / or the measurement light S described later can pass, and may be formed as holes penetrating the second shielding portion 6.

[0046] Similar to the first shielding portion 5 shown in Figure 3, the second shielding portion 6 may be a substantially disc-shaped member with a substantially circular YZ cross-section. This substantially disc-shaped second shielding portion 6, which serves as a light-shielding member, may be rotationally driven by a second rotational drive unit 62, such as a motor, around a second rotation axis 6A parallel to the optical path of the second laser L2s. One or more second light-transmitting portions 61 are provided in the substantially disc-shaped second shielding portion 6 at radial positions where the first laser L2s and / or measurement light S are irradiated. When multiple second light-transmitting portions 61 are provided, it is preferable that they be arranged at equal intervals along the circumferential direction (i.e., at equal angles with respect to the second rotation axis 6A).

[0047] When the second rotation drive unit 62 rotates the second shielding unit 6 at a substantially constant speed, one or more second light-transmitting units 61 are arranged at substantially constant intervals along the optical path of the second laser L2s and / or the measurement light S. That is, the light-transmitting state, in which the second laser L2s and / or the measurement light S are transmitted through any of the second light-transmitting units 61 as shown in Figure 2, and the light-shielding state, in which the reflected light L1s and / or the measurement light S are shielded by the second shielding unit 6 (the portion where the second light-transmitting units 61 are not provided), are switched substantially periodically. The number of second light-transmitting units 61 and their length along the circumferential direction can be appropriately adjusted according to the desired irradiation interval and irradiation time per irradiation of the second laser L2s.

[0048] The irradiation control unit 71 and the shielding control unit 72 coordinately control the first laser device 21, the second laser device 22, the first rotation drive unit 52, and the second rotation drive unit 62 so that during the first laser irradiation period as shown in Figures 1 and 3, the semiconductor wafer 3 is annealed by the first laser L1p emitted from the first laser device 21, and the second laser device 22 is shielded from reflected light L1s from the semiconductor wafer 3 by the second shielding unit 6, and during the second laser irradiation period as shown in Figure 2, the semiconductor wafer 3 is annealed by the second laser L2s emitted from the second laser device 22, and the first laser device 21 is shielded from reflected light L2p from the semiconductor wafer 3 by the first shielding unit 5.

[0049] Specifically, during the first laser irradiation period as shown in Figures 1 and 3, the irradiation control unit 71 causes the first laser device 21 to emit the first laser L1p when one of the first light-transmitting sections 51 in the first shielding section 5 is in front of the first laser device 21. This first laser L1p passes through the first light-transmitting section 51, through the polarizing element 41 and the quarter-wave plate 42, and is irradiated onto the semiconductor wafer 3. During this time, the irradiation control unit 71 stops the irradiation of the second laser L2s by the second laser device 22.

[0050] At the same time, the shielding control unit 72 rotates the substantially disc-shaped first shielding part 5 and the second shielding part 6 at substantially the same speed using the first rotation drive unit 52 and the second rotation drive unit 62. However, there is a substantially constant difference in phase (i.e., rotational position) between the first shielding part 5 and the second shielding part 6, which is maintained by the shielding control unit 72. As a result, as shown in Figure 1, the shielding control unit 72 ensures that when the first light-transmitting part 51 is in front of the first laser device 21, the second light-transmitting part 61 is not in front of the second laser device 22 (the second shielding part 6, acting as a light-shielding member, is in front).

[0051] Similarly, during the second laser irradiation period as shown in Figure 2, the irradiation control unit 71 causes the second laser L2s to be emitted from the second laser device 22 when one of the second light-transmitting sections 61 in the second shielding section 6 is in front of the second laser device 22. This second laser L2s passes through the second light-transmitting section 61, through the polarizing element 41 and the quarter-wave plate 42, and is irradiated onto the semiconductor wafer 3. During this time, the irradiation control unit 71 stops the irradiation of the first laser L1p by the first laser device 21.

[0052] Simultaneously, the shielding control unit 72 rotates the substantially disc-shaped first shielding section 5 and the second shielding section 6 at substantially the same speed (a substantially constant speed throughout the first laser irradiation period) using the first rotation drive unit 52 and the second rotation drive unit 62. However, a substantially constant difference exists in the phase between the first shielding section 5 and the second shielding section 6 throughout the first laser irradiation period, and this is maintained by the shielding control unit 72. As a result, as shown in Figure 2, the shielding control unit 72 ensures that when the second light-transmitting section 61 is in front of the second laser device 22, the first light-transmitting section 51 is not in front of the first laser device 21 (the first shielding section 5, acting as a light-shielding member, is in front of it).

[0053] According to this embodiment, the polarizing element 41 directs the first laser L1p and the second laser L2s, which have different polarizations, toward a common irradiation direction (Z direction) toward the semiconductor wafer 3, thereby allowing them to be treated as essentially a single laser L (however, as mentioned above, the first laser L1p and the second laser L2s are irradiated alternately with a substantially constant time difference).

[0054] Furthermore, according to this embodiment, while the first laser device 21 is irradiating the semiconductor wafer 3 with the first laser L1p, the reflected light L1s having s-polarization (second polarization) from the semiconductor wafer 3 can be safely shielded by the second shielding unit 6 from the second laser device 22 which is stopped irradiating. Similarly, while the second laser device 22 is irradiating the semiconductor wafer 3 with the second laser L2s, the reflected light L2p having p-polarization (first polarization) from the semiconductor wafer 3 can be safely shielded by the first shielding unit 5 from the first laser device 21 which is stopped irradiating. Note that an interval period may be provided during which both the first laser device 21 and the second laser device 22 stop irradiating. During such an interval period, no undesirable reflected light is generated, so the state of the first shielding unit 5 and the second shielding unit 6 is arbitrary.

[0055] To support the timing control by the irradiation control unit 71 and the shielding control unit 72 as described above, a first rotation state detection unit 53, 54 for detecting the rotation state of the first shielding unit 5 as a light-shielding member and / or a second rotation state detection unit 63, 64 for detecting the rotation state of the second shielding unit 6 as a light-shielding member may be provided.

[0056] The first rotation state detection units 53, 54 and / or the second rotation state detection units 63, 64 can be configured by rotation sensors or rotation encoders of any principle, but it is preferable that they be configured by optical rotation sensors that can utilize the first light-transmitting portion 51 in the first shielding portion 5 and / or the second light-transmitting portion 61 in the second shielding portion 6, as schematically shown in Figures 1 to 3.

[0057] Specifically, the first rotation state detection units 53 and 54 include a first light-emitting unit 53 and a first light-receiving unit 54 arranged opposite each other with a first shielding unit 5 acting as a light-shielding member in between. Based on the event that light emitted by the first light-emitting unit 53 (measurement light S schematically shown in Figure 3) passes through the first light-transmitting unit 51 and is received by the first light-receiving unit 54, the rotation state or phase of the first shielding unit 5 is detected. In this way, one or more first light-transmitting units 51 have both the function of transmitting the first laser L1p and the function of transmitting the measurement light S.

[0058] Similarly, the second rotation state detection units 63 and 64 each include a second light-emitting unit 63 and a second light-receiving unit 64, which are positioned opposite each other with a second shielding unit 6 acting as a light-shielding member in between. Based on the event that light emitted by the second light-emitting unit 63 passes through the second light-transmitting unit 61 and is received by the second light-receiving unit 64, the rotation state or phase of the second shielding unit 6 is detected. In this way, one or more second light-transmitting units 61 have both the function of transmitting the second laser L2s and the function of transmitting measurement light.

[0059] The irradiation control unit 71 and / or shielding control unit 72 preferably adaptively adjust their operation according to the rotational state of the first shielding unit 5 and / or the second shielding unit 6 detected by the first rotational state detection units 53, 54 and / or the second rotational state detection units 63, 64.

[0060] For example, the irradiation control unit 71 controls the timing for irradiating the first laser device 21 and the second laser device 22 with lasers (and stopping the irradiation) in accordance with the rotational state of the first shielding unit 5 and / or the second shielding unit 6 detected by the first rotational state detection units 53, 54 and / or the second rotational state detection units 63, 64. The shielding control unit 72 rotates the first shielding unit 5 and / or the second shielding unit 6 so that the difference between the rotational state of the first shielding unit 5 and / or the second shielding unit 6 detected by the first rotational state detection units 53, 54 and / or the second rotational state detection units 63, 64 (e.g., rotational position and rotational speed) and the desired rotational state is minimized (e.g., adaptively adjusting the rotational speed).

[0061] The present disclosure has been described above based on embodiments. Various modifications are possible for each component and each combination of processes in the exemplary embodiments, and it will be obvious to those skilled in the art that such modifications are included in the scope of the present disclosure.

[0062] In Figures 1 to 3, the first and second laser devices 21 and 22 are shielded from undesirable reflected light by the rotational drive of the roughly disc-shaped first shielding section 5 and second shielding section 6. However, the first shielding section 5 and second shielding section 6 may be configured in any other manner.

[0063] For example, as shown in Figures 4 and 5, which correspond to Figures 1 and 2, the first shielding part 5 and the second shielding part 6 may be driven to slide in front of the first laser device 21 and the second laser device 22, for example, along the direction of the bidirectional arrows shown, thereby shielding the first laser device 21 and the second laser device 22 from undesirable reflected light. During the first laser irradiation period in Figure 4, the first shielding part 5 is retracted to allow the first laser light L1p to pass through, and the second shielding part 6 is mechanically driven to slide in front of the second laser device 22 to shield against undesirable reflected light L1s. During the second laser irradiation period in Figure 5, the second shielding part 6 is retracted to allow the second laser light L2s to pass through, and the first shielding part 5 is mechanically driven to slide in front of the first laser device 21 to shield against undesirable reflected light L2p.

[0064] Furthermore, the first shielding section 5 and the second shielding section 6 may be composed of, for example, polarization control elements whose polarization characteristics can be controlled electrically. During the first laser irradiation period as shown in Figures 1 and 4, the first shielding section 5 is optically controlled to allow the first p-polarized laser L1p to pass through, while the second shielding section 6 is optically controlled to shield the s-polarized reflected light L1s. During the second laser irradiation period as shown in Figures 2 and 5, the second shielding section 6 is optically controlled to allow the second s-polarized laser L2s to pass through, while the first shielding section 5 is optically controlled to shield the p-polarized reflected light L2p.

[0065] The configuration, operation, and function of each device and method described in the embodiments can be realized by hardware resources or software resources, or by the cooperation of hardware resources and software resources. Hardware resources include, for example, processors, ROMs, RAMs, and various integrated circuits. Software resources include, for example, operating systems and application programs. [Explanation of symbols]

[0066] 1 Laser annealing apparatus, 3 Semiconductor wafer, 5 First shielding section, 6 Second shielding section, 21 First laser apparatus, 22 Second laser apparatus, 41 Polarizing element, 42 Quarter wave plate, 51 First light-transmitting section, 52 First rotation drive section, 53 First light-emitting section, 54 First light-receiving section, 61 Second light-transmitting section, 62 Second rotation drive section, 63 Second light-emitting section, 64 Second light-receiving section, 71 Irradiation control section, 72 Shielding control section.

Claims

1. A first laser apparatus that irradiates an object to be processed with a first laser having a first polarization along the irradiation direction, A second laser apparatus that irradiates the workpiece with a second laser having a second polarization different from the first polarization along the irradiation direction, A polarizing element that directs the first laser and the second laser, which are incident from different directions, toward a common irradiation direction toward the workpiece, When one of the first laser device and the second laser device irradiates the workpiece with a laser, an irradiation control unit stops the irradiation of the laser by the other of the first laser device and the second laser device, While the first laser device is irradiating the workpiece with the first laser, a second shielding unit shields the reflected light having the second polarization from the workpiece from the second laser device, A laser processing device equipped with the following features.

2. The laser processing apparatus according to claim 1, wherein the second shielding portion is deactivated while the second laser device is irradiating the workpiece with the second laser.

3. The laser processing apparatus according to claim 2, wherein the second shielding portion is a second light-shielding member that is positioned in the optical path between the second laser device and the polarizing element to shield reflected light having the second polarization while the first laser device is irradiating the workpiece with the first laser, and is removed from the optical path while the second laser device is irradiating the workpiece with the second laser.

4. The laser processing apparatus according to claim 3, wherein the second light-shielding member is rotated by a second rotation drive unit around a second rotation axis parallel to the optical path, and includes a second light-transmitting portion which is positioned on the optical path and transmits the second laser while the second laser device is irradiating the workpiece with the second laser, and is removed from the optical path while the first laser device is irradiating the workpiece with the first laser.

5. The system includes a second rotation state detection unit that detects the rotation state of the second light-shielding member, At least one of the irradiation control unit and the second rotation drive unit adaptively adjusts its operation according to the rotation state of the second light-shielding member detected by the second rotation state detection unit. The laser processing apparatus according to claim 4.

6. The laser processing apparatus according to claim 5, wherein the irradiation control unit controls the timing for irradiating the first laser device and the second laser device with lasers in accordance with the rotation state of the second light-shielding member detected by the second rotation state detection unit.

7. The laser processing apparatus according to claim 5, wherein the second rotation drive unit rotates the second light-shielding member so that the difference between the rotation state of the second light-shielding member detected by the second rotation state detection unit and a desired rotation state becomes small.

8. The laser processing apparatus according to any one of claims 5 to 7, wherein the second rotation state detection unit comprises a second light-emitting unit and a second light-receiving unit arranged opposite each other with the second light-shielding member in between, and detects the rotation state of the second light-shielding member based on the event that light emitted by the second light-emitting unit passes through the second light-transmitting unit and is received by the second light-receiving unit.

9. The laser processing apparatus according to any one of claims 1 to 7, further comprising a first shielding unit that shields the first reflected light having the first polarization from the workpiece from the first laser apparatus while the second laser apparatus is irradiating the workpiece with the second laser.

10. The laser processing apparatus according to any one of claims 1 to 7, wherein the irradiation control unit alternately irradiates the first laser device and the second laser device with lasers.

11. The laser processing apparatus according to any one of claims 1 to 7, wherein a quarter-wave plate is provided between the polarizing element and the workpiece, which converts the linearly polarized light of the first laser and the second laser into circularly polarized light and irradiates it onto the workpiece, and converts the circularly polarized light of the reflected light from the workpiece back into linearly polarized light and returns it to the polarizing element.

12. The first polarization is either p-polarized light having a polarization direction parallel to the plane of incidence containing the normal to the workpiece and the incident light, or s-polarized light having a polarization direction perpendicular to the plane of incidence. The second polarization is the other of the p-polarization and the s-polarization. The laser processing apparatus according to any one of claims 1 to 7.

13. The laser processing apparatus according to any one of claims 1 to 7, wherein the polarizing element is a polarizing beam splitter.

14. A laser processing apparatus according to any one of claims 1 to 7, wherein the first laser and the second laser are used to perform an annealing treatment on the workpiece.

15. The first laser device irradiates the workpiece with a first laser having a first polarization along the irradiation direction, The second laser device irradiates the workpiece with a second laser having a second polarization different from the first polarization along the irradiation direction, The polarizing element directs the first and second lasers, which are incident from different directions, towards a common irradiation direction toward the workpiece. When one of the first laser device and the second laser device irradiates the workpiece with a laser, the irradiation of the laser by the other of the first laser device and the second laser device is stopped. While the first laser device is irradiating the workpiece with the first laser, the reflected light having the second polarization from the workpiece is shielded from the second laser device. A laser processing method that performs this operation.

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