TW202231395A - Laser light introduction device - Google Patents

Abstract

Provided is a laser light introduction device in which the effect of curbing any fouling of the member that allows the laser light to pass through can be increased. In the present invention, an opening is provided to a plate-shaped member that has a top surface and bottom surface facing opposite directions from one another. A transmission member that allows laser light to pass through is attached to the top surface of the plate-shaped member, and blocks off the opening. A distal end of a gas flow path serves as a spout that opens on a side surface of the opening, and a gas jets out from the spout in a direction facing an opposing side surface. In plan view, a direction orthogonal to the direction in which the gas jets out from the spout is defined as the width direction. The width of the opening varies in the thickness direction of the plate-shaped member, with the width at the bottom surface being greater than the minimum value of the width.

Description

Laser light introduction device

The invention relates to a laser light introduction device.

Laser annealing is used in annealing to activate dopants implanted in semiconductor wafers, annealing to polycrystallize amorphous films, and the like. When laser annealing is performed, an object to be processed such as a semiconductor wafer is accommodated in a processing chamber, and the laser light is made incident on the object to be processed through a laser light transmission window provided on a ceiling surface of the processing chamber.

The laser light transmission window is contaminated by scattering objects scattered from the object to be processed during laser annealing and adheres to the laser light transmission window. If the laser light transmission window is contaminated, the transmittance of the laser light decreases. Therefore, the intensity of the laser light on the surface of the object to be processed is lowered, and proper laser annealing cannot be performed. Various annealing apparatuses for suppressing contamination of the laser light transmission window have been proposed (for example, refer to Patent Document 1, etc.).

In the annealing apparatus disclosed in Patent Document 1, a box is provided just below the laser light transmission window, and gas is blown from the gas flow path in the box to the laser light transmission window. Thereby, the flow of the gas from the inside of the box to the outside is formed, so that the scattering material from the object to be processed does not go toward the laser light transmission window. [Prior Art Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2000-021807

[Problems to be Solved by Invention]

An object of the present invention is to provide a laser light introduction device capable of enhancing the contamination suppressing effect of a member that transmits laser light. [Technical means to solve problems]

According to an aspect of the present invention, a laser light introduction device is provided, which is provided with: a plate-like member provided with an opening portion and having an upper surface and a lower surface facing in opposite directions to each other; a transmission member mounted on the upper surface of the plate-shaped member to seal the opening and transmit the laser light; and The gas flow path is provided with an ejection port opening to the side surface of the opening portion at the front end, and the gas is ejected from the ejection port in a direction toward the opposite side surface. When the direction perpendicular to the gas ejection direction from the ejection port in plan view is defined as the width direction, the width of the opening portion varies in the thickness direction of the plate-shaped member, and the width on the lower surface is smaller than the minimum value of the width. width. [Effect of invention]

By the flow of the gas ejected from the ejection port, the scattering material which enters the opening from the lower surface side of the plate-like member and goes toward the permeable member is shielded. By making the width of the opening on the lower surface of the plate-like member wider than the minimum value of the width, the gas tends to flow downward, the flow of the gas toward the permeable member is suppressed, and the effect of shielding scattered objects can be enhanced.

Referring to FIG. 1 to FIG. 7 , a laser light introduction device according to an embodiment of the present invention will be described. FIG. 1 is a schematic diagram of a laser processing apparatus equipped with a laser light introducing apparatus 10 according to the present embodiment. The laser processing apparatus based on this embodiment is used, for example, for activation annealing of dopants implanted in semiconductor wafers. The object to be processed 52 such as a semiconductor wafer is held on a movable table 51 accommodated in the processing chamber 50 . The laser light introduction device 10 is mounted on the top surface of the processing chamber 50 . The laser beam 70 is introduced into the processing chamber 50 through the laser beam introduction device 10 and is incident on the object to be processed 52 .

The gas is supplied from the gas supply source 40 to the laser light introducing device 10 through the piping 41 . As the gas, nitrogen gas, clean dry air, or the like is used. The gas supplied to the laser light introduction device 10 is introduced into the processing chamber 50 and discharged from the exhaust port 53 .

Next, the laser optical system will be described. In the laser processing apparatus according to this embodiment, a laser diode is used as the laser light source 61 . In addition, as the laser light source 61, other laser oscillators, for example, solid-state laser oscillators such as Nd:YAG lasers can be used. The laser light source 61 outputs, for example, a quasi-continuous oscillation (QCW) laser beam 70 having a wavelength of 808 nm. In addition, a laser light source that outputs a laser beam in the infrared region with a wavelength of 800 nm or more and 950 nm or less can be used. Alternatively, a laser light source that outputs a laser beam in a green wavelength region or an ultraviolet wavelength region can also be used.

The laser beam 70 output from the laser light source 61 passes through the attenuator 62 , the beam expander 63 , the homogenizer 64 , and is reflected downward by the folding mirror 65 . The laser beam 70 reflected downward is introduced into the processing chamber 50 through the condenser lens 66 and the laser beam introduction device 10 . The laser beam 70 introduced into the processing chamber 50 is incident on the object to be processed 52 .

The beam expander 63 collimates the laser beam 70 and amplifies the beam diameter. The homogenizer 64 and the condenser lens 66 shape the beam spot on the surface of the object 52 into an elongated shape, and uniformize the light intensity distribution in the beam cross section. The movable table 51 moves the object 52 in two directions orthogonal to the optical axis of the condenser lens 66 , whereby the laser beam 70 can be incident on substantially the entire surface of the object 52 .

FIG. 2 is a top view of the laser light introducing device 10 according to the present embodiment. 3A and 3B are cross-sectional views taken along the single-dot chain line 3A-3A and the single-dot chain line 3B-3B of FIG. 2, respectively. An xyz orthogonal coordinate system is defined in which the two directions parallel to the upper surface of the object 52 are the x direction and the y direction, and the normal direction of the upper surface of the object 52 is the z direction. Let the longitudinal direction of the long beam spot 71 of the laser beam 70 ( FIG. 1 ) incident on the object 52 be the y direction.

An opening 50A is provided on the top surface of the processing chamber 50 . The laser light introduction device 10 is installed on the top surface of the processing chamber 50 so as to seal the opening 50A from the inside. The laser light introduction device 10 includes a plate-shaped member 11 and a transmission member 12 . An opening 15 is provided in the plate-shaped member 11 . Of the two surfaces of the plate-like member 11 , the surface facing the outside of the processing chamber 50 is referred to as the upper surface 11T, and the surface on the opposite side (the surface facing the inner side of the processing chamber 50 ) is referred to as the lower surface 11B.

The permeable member 12 is supported on the upper surface side of the plate-shaped member 11 via the permeable member holder 13 . The permeable member 12 has a circular shape in plan view, and closes the opening 15 of the plate-shaped member 11 . The transmission member 12 is formed of an optical material that transmits the laser beam 70 . The laser beam 70 passes through the transmission member 12 , passes through the opening 15 of the plate-shaped member 11 and the opening 50A of the processing chamber 50 , and is introduced into the processing chamber 50 . The laser beam 70 passing through the opening 15 is a condensed beam.

The plate-shaped member 11 is provided with a gas flow path 20 . The gas is supplied from the gas supply source 40 to the gas flow path 20 through the piping 41 . Moreover, in FIG. 3A, the piping 41 is shown schematically. The gas supplied to the gas flow path 20 is ejected from the ejection port 21 arranged in a part of the side surface of the opening 15 in the direction toward the opposing side surface 15C. In FIG. 2 and FIG. 3A , the ejection direction of the gas is indicated by arrows. The shape of the opening 15 in plan view is a rounded rectangle. The ejection port 21 is provided on the side surface corresponding to one side of the rectangle.

The direction (y direction) orthogonal to the ejection direction (x direction) of the gas in plan view is defined as the width direction. The width of the opening portion 15 varies in the thickness direction of the plate-shaped member 11 . The width on the lower surface 11B is wider than the minimum value of the width of the opening portion 15 . The portion closer to the upper surface 11T than the position where the width is narrowest is referred to as the upper portion 15A of the opening 15 , and the portion on the lower surface 11B side is referred to as the lower portion 15B of the opening 15 . The side surface of the upper portion 15A extending in the x direction is inclined corresponding to the shape of the laser beam 70 condensed on the yz section ( FIG. 3B ). That is, the width of the upper portion 15A is gradually narrowed from the upper surface 11T toward the lower surface 11B.

At the boundary between the upper portion 15A and the lower portion 15B, a step is provided on the side surface of the opening portion 15 so that the width of the lower portion 15B is discontinuously wider than that of the upper portion 15A. The width of the lower portion 15B also gradually narrows from the upper surface 11T toward the lower surface 11B. The width of the lower end of the lower portion 15B is wider than the width of the lower end of the upper portion 15A. In the thickness direction of the plate-shaped member 11 , the position of the upper end of the ejection port 21 and the position of the boundary between the upper portion 15A and the lower portion 15B correspond to each other.

The side surface on which the opening 15 of the ejection port 21 is provided (the side surface on the left side in FIG. 3A ) is inclined corresponding to the shape of the laser beam 70 condensed in the zx cross-section. The side surface 15C (the side surface on the right side in FIG. 3A ) of the opening portion 15 facing the ejection port 21 is inclined from the upper surface 11T toward the lower surface 11B in a direction away from the ejection port 21 . In other words, the normal vector toward the outer side of the side surface 15C is directed obliquely downward.

The gas flow path 20 expands in the width direction (y direction) from the upstream side toward the downstream side of the gas flow in plan view. The ejection port 21 has a shape long in the width direction. A plurality of partition walls 22 are provided inside the gas flow path 20 . A part of the gas flow path 20 on the side of the ejection port 21 is divided into a plurality of partitions in the width direction by a plurality of partition walls 22 . The partition wall 22 extends from the discharge port 21 toward the upstream side of the gas flow, and reaches a region where the width of the gas flow path 20 is narrowed.

In the gas flow path 20 , a portion 20A of the front end continuous with the ejection port 21 is inclined in a direction away from the upper surface 11T from the upstream side toward the downstream side of the gas flow. Therefore, the gas is ejected slightly downward with respect to the direction parallel to the xy plane.

A gap 30 is secured between the upper surface 11T of the plate-shaped member 11 and the permeable member 12 . The branch path 25 branched from the gas flow path 20 extends to the gap 30 . For example, the bifurcated path 25 includes a circumferential portion 25A arranged along the circular outer circumference of the permeable member 12 in plan view, a portion 25B from the circumferential portion 25A toward the gap 30 , and a space connecting the circumferential portion 25A and the gas flow path 20 . Section 25c. The gas introduced into the gas flow path 20 is ejected into the gap 30 through the branch path 25 .

Next, the excellent effects of the above-described embodiments will be described. When the laser beam 70 is incident on the object to be processed 52 , the scattered objects scatter from the object to be processed 52 . By the gas ejected from the ejection port 21 , a gas flow that flows in the opening portion 15 mainly along the x-direction is formed. By causing the scattered matter from the object 52 to flow in the x-direction along with the airflow, the scattered matter toward the permeable member 12 is shielded, and the attachment of the scattered matter to the permeable member 12 is suppressed. Thereby, the permeable member 12 is less likely to be contaminated.

Next, the excellent effects of the embodiments will be described according to various structures characteristic of the laser light introduction device 10 .

[Effect of the structure based on widening the width of the opening portion 15 on the lower surface 11B] 4A is a schematic plan view of the laser light introduction device 10 according to the embodiment, and FIG. 4B is a schematic plan view of the laser light introduction device 10 according to the comparative example.

In the laser light introducing device 10 ( FIG. 4A ) according to the embodiment, the width of the upper side portion 15A provided on the plate-like member 11 ( FIG. 3B ) is gradually narrowed toward the lower side, at the boundary between the upper side portion 15A and the lower side portion 15B , the width widens discontinuously. Furthermore, the width of the lower portion 15B also gradually narrows downward. The width of the lower end of the lower portion 15B is wider than the width of the lower end of the upper portion 15A.

On the other hand, in the comparative example ( FIG. 4B ), the width of the opening 15 does not change discontinuously, but gradually narrows continuously from the upper surface 11T to the lower surface 11B. The side surfaces on both sides in the width direction are the same as the side surfaces of the upper portion 15A in FIG. 3B , and are inclined corresponding to the shape of the condensed laser beam 70 . The ejection port 21 is arranged over substantially the entire area in the width direction on the side surface extending in the width direction of the opening 15 .

In the comparative example ( FIG. 4B ), the gas ejected from the ejection port 21 flows toward the side surface 15C facing the ejection port 21 , and further goes obliquely downward along the inclination of the side surface 15C facing the ejection port 21 . Since the width of the opening portion 15 is gradually narrowed downward, a part of the gas hits the slope 15D on the side of the opening portion 15 and is less likely to leak downward. Therefore, the pressure in the vicinity of the lower end of the inclined surface 15D is increased, and a part of the gas is returned to the opening portion 15 . Part of the gas returned to the opening 15 reaches the surface of the permeable member 12 . In this way, disturbance occurs in the flow of the gas, and thus, the function of shielding the scattered objects from the object to be processed 52 ( FIGS. 3A and 3B ) toward the permeable member 12 is deteriorated.

In the embodiment ( FIG. 4A ), the ejection openings 21 are arranged over substantially the entire width direction of the upper portion 15A, and the lower portion 15B is wider in the width direction than the widthwise range in which the ejection openings 21 are arranged. When the gas ejected from the ejection port 21 flows obliquely downward along the side surface 15C facing the ejection port 21 and reaches the lower portion 15B, it expands in the width direction. Therefore, the degree of pressure increase in the vicinity of the lower end of the side surface 15C is smaller than that in the comparative example ( FIG. 4B ). Therefore, most of the gas does not turn around in the vicinity of the lower end of the side surface 15C, but flows into the processing chamber 50 ( FIGS. 3A and 3B ). The gas flow is less likely to be turbulent, and therefore, the function of shielding the scattered objects from the object to be processed 52 ( FIGS. 3A and 3B ) toward the permeable member 12 is less likely to decline.

If the width of the upper portion 15A is expanded to the same extent as the width of the lower portion 15B without changing the dimension of the ejection port 21 in the width direction, a sufficient flow of gas does not occur in the opening portion 15 in plan view. area. In the region where the flow of gas is insufficient, the function of shielding the scattering objects toward the permeable member 12 is low. In the embodiment, by expanding only the lower portion 15B in the width direction, in the upper portion 15A of the opening portion 15 in a plan view, a region where the flow of gas is insufficient is prevented from being generated.

In addition, even if the width of the lower portion 15B is widened, by keeping the size of the upper portion 15A slightly larger than the cross-section of the laser beam 70 in plan view, it is possible to suppress the direction from the object 52 to the transmissive member 12 (Fig. 3A and 3B), the cross-section of the path of the flying object is unnecessarily large.

In the embodiment, the side surfaces on both sides in the width direction of the lower side portion 15B (the side surfaces appearing in FIG. 3B ) are inclined in such a manner that the width of the lower side portion 15B gradually narrows downward, but the side surfaces are not necessarily inclined. The side surfaces may also be made perpendicular to the lower surface 11B.

Further, the side surface of the lower side portion 15B may be inclined in the opposite direction. That is, the side surface of the lower side part 15B may be inclined so that the width of the lower side part 15B gradually becomes wider downward. At this time, it is not necessary to form a level difference at the boundary between the upper portion 15A and the lower portion 15B. That is, the width of the upper end of the lower side portion 15B can be made equal to the width of the lower end of the upper side portion 15A.

[Effect of the structure in which the normal vector of the side surface 15C facing the ejection port 21 faces obliquely downward] FIG. 5A is a cross-sectional view of the laser light introduction device 10 according to the embodiment, and FIG. 5B is a cross-sectional view of the laser light introduction device 10 according to the comparative example.

In the comparative example ( FIG. 5B ), the side surface 15C of the opening 15 facing the ejection port 21 is inclined in accordance with the shape of the condensed laser beam 70 . That is, the side surface 15C is inclined downward toward the direction of the discharge port 21 . When the gas ejected from the ejection port 21 reaches the opposing side surface 15C, a part of the gas flows obliquely upward along the side surface 15C, as indicated by the arrow in FIG. 5B , and reaches the permeable member 12 . Therefore, the function of shielding the scattered objects from the object 52 to the transmission member 12 is reduced.

On the other hand, in the embodiment ( FIG. 5A ), the side surface 15C is inclined downward and away from the discharge port 21 . Therefore, as indicated by arrows in FIG. 5A , most of the gas ejected from the ejection port 21 and reaching the side surface 15C flows obliquely downward along the side surface 15C and is introduced into the processing chamber 50 . The flow of the gas toward the permeable member 12 is less likely to occur, so that the scattering from the object 52 toward the permeable member 12 can be shielded. In addition, since the scatter from the object to be processed 52 flows in the lateral direction along with the airflow and is removed from the space above the object to be processed 52 , the re-adhesion of the scatter to the object 52 can be suppressed.

In order to obtain sufficient scattering shielding function, the angle formed by the upper surface 11T and the side surface 15C is preferably an acute angle, more preferably 60° or less.

[Effect of dividing the vicinity of the front end of the gas flow path 20 into a plurality of partitions] 6A is a schematic plan view of the laser light introduction device 10 according to the embodiment, and FIG. 6B is a schematic plan view of the laser light introduction device 10 according to the comparative example.

In the laser light introduction device 10 according to the embodiment ( FIG. 6A ), the vicinity of the front end of the gas flow path 20 is divided into a plurality of partitions by a plurality of partition walls 22 in the width direction. On the other hand, in the comparative example ( FIG. 6B ), the gas flow path 20 is not divided into a plurality of partitions in the width direction. In FIGS. 6A and 6B , the trend of the length distribution of the arrow indicating the direction of the airflow indicates the trend of the flow velocity distribution.

In the comparative example ( FIG. 6B ), the flow velocity of the gas in the center portion in the width direction of the discharge port 21 is faster than the flow velocity of the gas in the both end portions. In a plan view, in a region where the flow velocity is slow, the function of shielding the scattered objects from the object 52 toward the transmission member 12 is reduced. On the other hand, in the embodiment, the portion near the front end of the gas flow path 20 is divided into a plurality of partition regions in the width direction by a plurality of partition walls 22 . Since the partition wall 22 extends from the discharge port 21 toward the upstream side of the gas flow to the region where the width of the gas flow path 20 is narrowed, the distribution of the flow velocity in the width direction is nearly uniform. Therefore, the effect of shielding the scattered objects from the object 52 toward the transmission member 12 can be made substantially uniform over the entire region in the opening portion 15 .

[Effects based on the structure in which a portion 20A of the front end of the gas flow path 20 faces obliquely downward] In the embodiment, since a part 20A ( FIG. 3A ) of the front end of the gas flow path 20 faces obliquely downward, the gas ejected from the ejection port 21 flows obliquely downward. Therefore, the flow of the gas toward the permeation member 12 is less likely to occur, so that the reduction in the effect of shielding the scattered objects from the object 52 toward the permeation member 12 can be suppressed.

[Effect of setting fork road 25] FIG. 7 is a cross-sectional view of the laser light introduction device 10 according to the embodiment. In the embodiment, a part of the gas introduced into the gas flow path 20 is supplied to the gap 30 between the plate-shaped member 11 and the permeable member 12 through the branch path 25 . As indicated by the arrows, the gas supplied to the gap 30 is introduced into the processing chamber 50 through the opening 15 . Therefore, it is possible to suppress the generation of the airflow that reaches the permeation member 12 toward the upper side in the opening portion 15 . Thereby, the effect of shielding the scattered objects from the object to be processed 52 toward the transmission member 12 can be enhanced.

In the above, with respect to each of the five characteristic structures of the laser light introduction device 10 according to the embodiment, the excellent effects that can be obtained by the structure have been described. The laser light introduction device 10 according to the embodiment has all of the above-mentioned five characteristic structures, but does not need to have all of the above-mentioned five characteristic structures in order to suppress contamination of the transmission member 12 . Even in a laser light introduction device having at least one of the five characteristic structures, an excellent effect of suppressing contamination of the transmission member 12 can be obtained.

Next, various modifications of the above-described embodiment will be described. In the above-mentioned embodiment, the shape of the opening 15 ( FIG. 2 ) provided in the plate-like member 11 in a plan view is a rectangle with rounded corners, but other shapes may be adopted. For example, a circle, an ellipse, or the like can be used. The shape of the opening portion 15 may be set according to the shape of the beam cross section of the laser beam 70 . When the shape of the opening 15 in plan view is a circle or an ellipse, the width of the opening 15 changes in the x direction. In this case, the width on the lower surface 11B may be wider than the minimum value of the width of the opening 15 in each of the cross-sections perpendicular to the x-direction (corresponding to the cross-sectional view of FIG. 3B ).

In addition, in the above-described embodiment, the example in which the laser light introducing device 10 is mounted on the laser annealing device for activating the dopant has been described, but it can also be mounted on other laser processing devices.

In addition, in the above-mentioned embodiment, the plate-shaped member 11 (FIG. 3A, FIG. 3B) of the laser light introduction device 10 is installed on the top surface of the processing chamber 50, but the wall surface of the processing chamber 50 itself can also be used for laser light introduction The plate-like member 11 of the device 10 .

The above-mentioned embodiments are illustrative, and the present invention is not limited to the above-mentioned embodiments. For example, it is apparent to those skilled in the art that various changes, improvements, combinations, and the like can be made.

10: Laser light introduction device 11: Plate member 11B: Lower surface of plate-like member 11T: Upper surface of plate member 12: Through Components 13: Through the component holder 15: Opening 15A: Upper part 15B: Lower part 15C: Side of the opening 15D: Slope on the side of the opening 20: Gas flow path 20A: A part of the front end of the gas flow path 21: spout 22: Dividing wall 25: Fork Road 25A, 25B, 25C: bifurcated part 30: Gap 40: Gas supply source 41: Piping 50: Processing room 50A: Opening of processing chamber 51: Movable workbench 52: Processing object 53: exhaust port 61: Laser light source 62: Attenuator 63: Beam Expander 64: Homogenizer 65: folding mirror 66: Condenser lens 70: Laser Beam 71: Beam Spot

FIG. 1 is a schematic diagram of a laser processing apparatus equipped with the laser light introducing apparatus according to the embodiment. [FIG. 2] It is a top view of the laser light introduction device based on this embodiment. [FIG. 3A] and [FIG. 3B] are cross-sectional views taken along the single-dot chain line 3A-3A and the single-dot chain line 3B-3B in FIG. 2, respectively. FIG. 4A is a schematic plan view of a laser light introduction device according to an example, and FIG. 4B is a schematic plan view of a laser light introduction device according to a comparative example. [ FIG. 5A ] is a cross-sectional view of a laser light introduction device based on an embodiment, and [ FIG. 5B ] is a cross-sectional view of a laser light introduction device based on a comparative example. FIG. 6A is a schematic plan view of a laser light introduction device according to an example, and FIG. 6B is a schematic plan view of a laser light introduction device 10 according to a comparative example. FIG. 7 is a cross-sectional view of the laser light introducing device according to the embodiment.

10: Laser light introduction device

11: Plate member

11B: Lower surface of plate-like member

11T: Upper surface of plate member

12: Through Components

13: Through the component holder

15: Opening

15A: Upper part

15B: Lower part

15C: Side of the opening

20: Gas flow path

20A: A part of the front end of the gas flow path

21: spout

25A: Forked Section

25B: Forked Section

25C: Forked Section

30: Gap

40: Gas supply source

41: Piping

50: Processing room

50A: Opening of processing chamber

52: Processing object

70: Laser Beam

Claims (6)

A laser light introduction device is provided with: a plate-like member provided with an opening portion and having an upper surface and a lower surface facing in opposite directions to each other; a transmission member mounted on the upper surface of the plate-shaped member to seal the opening and transmit the laser light; and The gas flow path is provided with an ejection port opening to the side surface of the opening portion at the front end, and the gas is ejected from the ejection port in a direction toward the opposite side surface. When the direction perpendicular to the gas ejection direction from the ejection port in plan view is defined as the width direction, the width of the opening portion varies in the thickness direction of the plate-shaped member, and the width on the lower surface is smaller than the minimum value of the width. width. The laser light introduction device according to claim 1, wherein, In the thickness direction of the said plate-shaped member, the side surface of the upper surface side of the position of the narrowest width of the said opening part is inclined so that the width may become narrower from the upper surface toward the lower surface. The laser light introduction device according to claim 1 or claim 2, wherein, The side surface of the said opening part which opposes the said ejection port is inclined in the direction away from the said ejection port from the upper surface to the lower surface. The laser light introduction device according to claim 1 or claim 2, wherein, The ejection port has a shape long in the width direction, and a partition wall is provided inside the gas flow path to divide a part of the front end of the gas flow path into a plurality of partition regions in the width direction. The laser light introduction device according to claim 1 or claim 2, wherein, At least a part of the front end of the gas flow path is inclined in a direction away from the upper surface of the plate-shaped member from the upstream side toward the downstream side of the gas flow. The laser light introduction device according to claim 1 or claim 2, wherein, A gap is secured between the plate-shaped member and the permeable member, The laser light introduction device further includes a bifurcated path that bifurcates from the gas flow path to eject gas to a gap between the plate-shaped member and the transmission member.

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