Substrate processing apparatus and substrate processing method

Abstract

Provided is a substrate processing apparatus for processing a substrate, the apparatus including: a substrate holding part that holds the substrate; a laser irradiation part that irradiates the substrate held by the substrate holding part with laser light; and a beam damper that is provided so as to surround the entire periphery of the outer peripheral section of the substrate holding part and has an opening for allowing the laser light to enter.

Description

Substrate processing apparatus and substrate processing method

[0001] The present disclosure relates to a substrate processing apparatus and a substrate processing method.

[0002] Patent Document 1 discloses a substrate processing method that includes irradiating one of a first main surface and a second main surface of a substrate with a laser beam to flatten the one surface, and, after flattening the one surface of the substrate, grinding the other surface facing opposite to the one surface of the substrate to flatten the other surface.

[0003] International Publication No. 2022 / 158333

[0004] The technology according to the present disclosure prevents damage to device components caused by laser light when a substrate is irradiated with laser light in a substrate processing apparatus for processing.

[0005] One aspect of the present disclosure is a substrate processing apparatus for processing a substrate, comprising: a substrate holding unit for holding the substrate; a laser irradiation unit for irradiating the substrate held by the substrate holding unit with laser light; and a beam damper arranged to surround the entire outer periphery of the substrate holding unit and having an opening for allowing the laser light to enter.

[0006] According to the present disclosure, when a substrate is processed by irradiating it with laser light in a substrate processing apparatus, damage to apparatus components caused by the laser light can be suppressed.

[0007] 1 is a flow diagram showing main steps of wafer processing according to the present embodiment; FIG. 2 is a cross-sectional view showing an outline of the configuration of a wafer processing apparatus according to the present embodiment; FIG. 3 is a plan view showing an outline of the configuration of a wafer processing apparatus according to the present embodiment; FIG. 4 is an explanatory view showing an outline of the configuration of a laser irradiation unit according to the present embodiment; FIG. 5 is an explanatory view showing a state in which laser light is irradiated onto a first surface of a wafer; FIG. 6 is a perspective view showing an outline of the configuration of a wafer holding unit and a beam damper; FIG. 7 is a perspective view showing an outline of the configuration of a wafer holding unit and a beam damper; FIG. 8 is a cross-sectional view showing an outline of the configuration of a wafer holding unit and a beam damper; FIG. 9 is an enlarged view showing an outline of the configuration of a beam damper; FIG. 10 is an explanatory view showing an air flow in a chamber; FIG. 11 is an enlarged view showing an outline of the configuration of a beam damper according to another embodiment; FIG. 12 is an explanatory view showing an air flow in a chamber according to another embodiment;

[0008] 2. Description of the Related Art In the manufacturing process of semiconductor devices, the cut surfaces of disk-shaped semiconductor wafers (hereinafter referred to as "wafers") obtained by slicing a single crystal ingot with a wire saw or the like are flattened.

[0009] Wafers sliced ​​from a single crystal ingot have waviness on both sides. Therefore, in the method described in Patent Document 1, the waviness of the wafer is measured, and then one side of the wafer is irradiated with a laser beam based on the waviness measurement results, thereby flattening the one side. In this process, the irradiation point of the laser beam is moved using, for example, a galvanometer scanner, and the laser beam is irradiated onto one side of the wafer.

[0010] Here, because the waviness of the wafer extends over the entire surface of the wafer, it is necessary to irradiate the entire surface of the wafer with the laser light. In other words, it is necessary to move the irradiation point of the laser light over the entire surface of the wafer. However, in this case, the irradiation point of the laser light may move outward from the outer edge of the wafer, and the laser light may be irradiated onto device components other than the wafer.

[0011] The technology disclosed herein prevents damage to device components caused by laser light when a substrate is irradiated with laser light in a substrate processing apparatus. Hereinafter, a wafer processing apparatus as a substrate processing apparatus and a wafer processing method as a substrate processing method according to the present embodiment will be described with reference to the drawings. Note that in this specification and the drawings, elements having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted.

[0012] First, a wafer processing method according to this embodiment will be described. In this embodiment, both surfaces of a wafer W, which is a substrate obtained by slicing a single crystal ingot, are flattened.

[0013] The wafer W is a silicon wafer or a compound semiconductor wafer. The compound semiconductor wafer is not particularly limited, but may be, for example, a GaAs wafer, a SiC wafer, a GaN wafer, or an InP wafer. The wafer W is disk-shaped and has a first surface Wa and a second surface Wb. The second surface Wb is the surface opposite to the first surface Wa. The first surface Wa and the second surface Wb are each cut surfaces formed by slicing the wafer W, and have waviness.

[0014] First, the waviness of the wafer W is measured (St1 in FIG. 1). In St1, the waviness of at least one surface of the wafer W is measured. A known measuring device is used to measure the waviness in St1. For example, an infrared sensor, a laser displacement meter, a capacitance sensor, or the like is used to measure the height distribution of the first surface Wa or the second surface Wb set on the laser-processed surface, and the waviness of the first surface Wa or the second surface Wb is measured.

[0015] After measuring the waviness of both the surface Wa and the surface Wb in St1, the laser processing surface may be set to the surface with the smallest waviness or the surface with the largest waviness.

[0016] Next, based on the measurement results of the waviness of the first surface Wa measured in St1, the entire surface of the first surface Wa is irradiated with laser light to flatten the first surface Wa (St2 in FIG. 1). In St2, the irradiation point (focus) of the laser light is moved to the entire surface of the first surface Wa using the wafer processing apparatus 1 (see FIG. 2), and the laser light is irradiated. The detailed configuration of the wafer processing apparatus 1 will be described later.

[0017] In St2, when the first surface Wa is irradiated with laser light, the first surface Wa absorbs the laser light and either changes state from a solid phase to a gas phase and disperses, or disperses while remaining in the solid phase, and is removed. The depth of the surface layer of the first surface Wa that is removed by the laser light is controlled by the integrated irradiation amount, which is the product of the intensity of the laser light (laser light output) and the irradiation time. The greater the integrated irradiation amount, the greater the depth of the surface layer of the first surface Wa that is removed.

[0018] In St2, the integrated dose of laser light per unit area of ​​the first surface Wa is controlled based on the measurement results of the waviness of the first surface Wa measured in St1. Since the first surface Wa has waviness, the integrated dose is changed depending on the location within the first surface Wa. For example, the integrated dose is increased in locations with large waviness and decreased in locations with small waviness. Then, the waviness of the first surface Wa is removed, and the first surface Wa is flattened.

[0019] Next, the first surface Wa that has been laser-machined in St2 is cleaned (St3 in FIG. 1). A known cleaning device is used to clean the first surface Wa in St3. For example, the first surface Wa may be scrubbed or cleaned with a cleaning solution. This cleaning removes particles (debris) adhering to the first surface Wa. Note that the second surface Wb may also be cleaned in St3.

[0020] Next, the second surface Wb is ground to flatten it (St4 in FIG. 1 ). A known grinding device is used to grind the second surface Wb in St4. For example, while the first surface Wa is held by a chuck, multiple grindstones attached to a grinding wheel of a grinding tool are brought into contact with the second surface Wb, and the chuck and grinding wheel are rotated to grind the entire second surface Wb. At this time, since the first surface Wa has been flattened in St2, the wafer W can be held horizontally by the chuck, and the second surface Wb can be properly ground. Then, any waviness in the second surface Wb is removed, and the second surface Wb is flattened.

[0021] Next, the second surface Wb ground in St4 is cleaned (St5 in FIG. 1). A known cleaning device is used to clean the second surface Wb in St5. For example, the second surface Wb may be scrubbed. This cleaning removes grinding debris adhering to the second surface Wb. Note that the first surface Wa may also be cleaned in St5. Furthermore, the first surface Wa, which is the laser-processed surface, may be ground after St5.

[0022] Next, the second surface Wb cleaned in St5 is etched (St6 in FIG. 1 ). A known etching device is used to etch the second surface Wb in St6. For example, an etching solution is supplied to the second surface Wb, and the second surface Wb is wet-etched. By etching the second surface Wb in this manner, a damaged layer (grinding marks) formed on the second surface Wb during grinding is removed. Furthermore, by etching the second surface Wb, the uniformity of the thickness of the wafer W can be improved.

[0023] In St6, the first surface Wa may be etched. By etching the first surface Wa, it is possible to remove a damaged layer (laser processing marks) formed on the first surface Wa during laser processing or grinding marks formed on the first surface Wa during grinding. It is also possible to remove contaminants that have adhered to the first surface Wa during grinding. Etching is particularly effective for removing contaminants that contain metal components, which are difficult to remove.

[0024] As described above, in the wafer processing of this embodiment, the first surface Wa can be planarized by laser processing in St 2, and the second surface Wb can be planarized by grinding in St 4. Furthermore, the second surface Wb may be laser processed before grinding.

[0025] Next, the configuration of the wafer processing apparatus 1 used in the laser processing of St2 will be described.

[0026] 2, the wafer processing apparatus 1 has a chamber 10, a laser irradiation unit 20, and a wafer holding unit 30. The laser irradiation unit 20 is disposed in the upper part of the chamber 10, and the wafer holding unit 30 is disposed in the lower part of the chamber 10. Inside the chamber 10, a processing space S is formed between the laser irradiation unit 20 and the wafer holding unit 30.

[0027] The chamber 10 has a fixed cover 11 and an openable cover 12. The fixed cover 11 is fixed by a support member (not shown). The fixed cover 11 has a configuration in which a truncated cone portion 11a and a cylindrical portion 11b are integrated together. Note that the configuration of the chamber 10 is not limited to the example shown in the figure. For example, the chamber 10 may have a cylindrical shape as a whole.

[0028] The truncated cone portion 11a has a truncated cone shape with open top and bottom surfaces, and has a tapered shape in side view with a diameter increasing from top to bottom. The upper end of the truncated cone portion 11a is disposed away from the laser irradiation unit 20, which will be described later. As shown in FIGS. 2 and 3 , a gas inlet 13 serving as a first gas inlet is formed in an annular shape between the upper end of the truncated cone portion 11a and the laser irradiation unit 20. The gas inlet 13 is formed to allow gas to flow into the chamber 10, as will be described later. Furthermore, by forming a gap serving as the gas inlet 13 between the upper end of the truncated cone portion 11a and the laser irradiation unit 20, vibrations generated when the laser irradiation unit 20 operates are not transmitted to the chamber 10, and further transmission to the wafer holder 30 can be suppressed.

[0029] An air inlet 14 may be formed on the side surface of the truncated cone portion 11a, for example, below the laser irradiation unit 20. The air inlet 14 is provided with an air supply unit 15 equipped with, for example, a fan and a filter. The air supply unit 15 supplies gas from the air inlet 14 into the chamber 10. Note that the air inlet 14 may be formed around the entire circumference of the truncated cone portion 11a.

[0030] The cylindrical portion 11b has a cylindrical shape that is open at the top and bottom and extends downward from the bottom end of the truncated cone portion 11a. The diameter of the cylindrical portion 11b is the largest in the fixed cover 11. A loading / unloading port 16 is formed at the bottom of the cylindrical portion 11b to load and unload the wafer W into and from the chamber 10.

[0031] The open-close cover 12 has a cylindrical shape with openings on the top and bottom. The open-close cover 12 is provided inside the cylindrical portion 11b of the fixed cover 11 at a position corresponding to the loading / unloading opening 16. The open-close cover 12 is configured to be able to move up and down by a lifting mechanism (not shown) and opens and closes the loading / unloading opening 16. The open-close cover 12 rises inside the cylindrical portion 11b when opening the loading / unloading opening 16, and descends to and is accommodated in a cover accommodating section 60 (described later) when closing the loading / unloading opening 16.

[0032] A laser irradiation unit 20 is provided above the fixed cover 11 of the chamber 10. The laser irradiation unit 20 is disposed above the wafer holder 30 and irradiates the wafer W held by the wafer holder 30 with laser light L. As shown in FIG. 4 , the laser irradiation unit 20 includes a light source 21, an optical system 22, and a lens 23.

[0033] The light source 21 is, for example, a pulsed laser, and oscillates a pulsed laser beam L to be irradiated onto the first surface Wa of the wafer W. The laser beam L is absorbent by the wafer W. If the wafer W is a silicon wafer, the laser beam L is, for example, UV light or IR laser beam, and the wavelength of the IR laser beam is, for example, 1064 nm. The wafer W absorbs the laser beam L and either changes state from a solid phase to a gas phase and disperses, or disperses while remaining in the solid phase. As a result, the first surface Wa of the wafer W is planarized. The laser beam L may be irradiated onto the first surface Wa of the wafer W in a focused manner. The irradiation point P of the laser beam L is the focal point where the power density is highest, but it does not have to be the focal point.

[0034] The optical system 22 has a galvanometer scanner 24. The galvanometer scanner 24 is disposed above the wafer holder 30. The galvanometer scanner 24 has a galvanometer mirror 25 and a galvanometer motor 26. The galvanometer motor 26 rotates the galvanometer mirror 25 to displace the irradiation point P of the laser light L. The galvanometer scanner 24 can move the position of the irradiation point P of the laser light L on the first surface Wa of the wafer W, without moving the wafer holder 30, to scan the laser light L.

[0035] The optical system 22 may include other optical elements. For example, the optical system 22 may include a homogenizer and an aperture to form a rectangular irradiation spot P with a uniform intensity distribution. Furthermore, for example, the optical system 22 may include an attenuator to adjust the output of the laser light L. The shape of the irradiation spot P is not limited to a rectangle and may be, for example, a circle.

[0036] An fθ lens, for example, is used as the lens 23. The lens 23 forms a focal plane perpendicular to the Z-axis direction. While the galvanometer scanner 24 moves the position of the irradiation point P in the X-axis direction or the Y-axis direction, the lens 23 maintains the Z-axis position of the irradiation point P on the focal plane, and also maintains the shape and dimensions of the irradiation point P on the focal plane. As a result, the rectangular irradiation points P can be arranged two-dimensionally, regularly, and without gaps on the surface of the wafer W.

[0037] 5, the laser irradiation unit 20 having the above configuration moves the irradiation point P of the laser light L in the X-axis direction and also in the Y-axis direction. The laser irradiation unit 20 then irradiates the laser light L onto the entire surface or selectively onto the first surface Wa of the wafer W. For example, the laser light L may be irradiated onto part of the first surface Wa depending on the waviness of the first surface Wa.

[0038] Although the laser irradiation unit 20 in this embodiment has the galvanometer scanner 24, the configuration for moving the irradiation point P of the laser light L is not limited to this. For example, the laser irradiation unit 20 may have a wedge scanner, which moves the irradiation point P.

[0039] As shown in Fig. 2, a wafer holder 30 is provided below the open / close cover 12 of the chamber 10. As shown in Figs. 6 to 10, the wafer holder 30 has a stage 31 and a plurality of, for example, three, holding pins 32. The stage 31 has a disk shape, and for example, the diameter of the stage 31 is smaller than the diameter of the wafer W. The three holding pins 32 are arranged on the upper surface of the stage 31 at equal intervals on a circumference concentric with the stage 31. The three holding pins 32 contact and hold the second surface Wb of the wafer W.

[0040] Since the wafer holding unit 30 is fixed, displacement of the wafer W relative to the wafer holding unit 30 is suppressed. The configuration of the wafer holding unit 30 is not limited to this embodiment. For example, a suction mechanism (not shown) may be provided on the upper surface of the holding pins 32, and the wafer W may be held by suction using the holding pins 32. The wafer holding unit 30 may also hold the wafer W by suction, and may use a vacuum chuck or an electrostatic chuck.

[0041] A cover 33 is provided at the center of the upper surface of the stage 31. The cover 33 has a hollow shape with an open bottom and is disposed so as to cover, for example, the through-hole 70. A gap is formed between the cover 33 and the upper surface 31a of the stage 31. In the cover 33, gas supplied from the gas supply unit 73 flows in through the through-hole 70 and flows out through the through-hole 80, as will be described later. In addition, in the cover 33, gas within the chamber 10 flows in from the space between the wafer W and the stage 31 and flows out through the through-hole 80, as will be described later. The cover 33 is made of a material that is transparent to the laser light L.

[0042] A beam damper 40 is provided on the outer periphery of the stage 31 of the wafer holder 30. The beam damper 40 is arranged in a ring shape along the outer periphery of the stage 31. At the radially outer side of the outer periphery of the stage 31, the height of the upper surface 40a of the beam damper 40 and the height of the upper surface 31a of the stage 31 may be approximately the same. Since there is no step between the upper surfaces 40a and 31a, particle accumulation can be suppressed and gas can flow smoothly over the upper surfaces 40a and 31a. The beam damper 40 extends from the radially outer side of the outer periphery of the stage 31 to below the outer periphery of the stage 31. The inner upper side surface 40b of the beam damper 40 has a step 40c that fits the outer periphery of the stage 31 and is in contact with the outer periphery side surface 31b and lower surface 31c of the stage 31. The beam damper 40 and the stage 31 may be provided integrally.

[0043] An annular first opening 41 is formed in the upper surface of the beam damper 40 so as to surround the entire outer periphery of the stage 31. As shown in Fig. 10, the radial distance D of the first opening 41 is, for example, 10 mm to 20 mm. Note that the distance D is set arbitrarily depending on the height of the wafer W (the height of the holding pins 32) and the angle of the laser light L irradiated onto the outer periphery of the wafer W.

[0044] An annular second opening 42 that opens toward the inner periphery of the beam damper 40 is formed in an inner lower side surface 40d below the stage 31 and below the step portion 40c of the beam damper 40. The position where the second opening 42 is formed is not limited to this. For example, the second opening 42 may be formed in the lower surface 40e of the beam damper 40.

[0045] An internal flow path 43 connected to the first opening 41 and the second opening 42 is formed inside the beam damper 40. The internal flow path 43 is composed of a first flow path 43a, a second flow path 43b, and a third flow path 43c. The first flow path 43a, the second flow path 43b, and the third flow path 43c are arranged in this order from above. The first flow path 43a extends substantially vertically downward from the first opening 41 and communicates with the second flow path 43b. The second flow path 43b extends obliquely downward from the radially outer side to the radially inner side in a cross-sectional view. The third flow path 43c extends substantially horizontally from the second opening 42 and communicates with the second flow path 43b.

[0046] The beam damper 40 is made of a material that is resistant to laser light and that absorbs or diffuses the laser light L in other directions, such as a metal material such as aluminum. Furthermore, the outer surface of the beam damper 40 and the inner surface of the internal flow path 43 of the beam damper 40 may be subjected to surface treatment such as anodizing in order to absorb the laser light L or diffuse it in other directions.

[0047] The beam damper 40 having the above configuration allows the laser light L to enter through the first opening 41 when the irradiation point P of the laser light L deviates from the wafer W during irradiation of the laser light L from the laser irradiation unit 20. As shown by the dotted line in FIG. 10 , the laser light L entering through the first opening 41 is reflected (e.g., specularly reflected) or absorbed within the internal flow path 43, and is therefore attenuated within the internal flow path 43 and prevented from exiting the first opening 41. Furthermore, even when the laser light L entering through the first opening 41 exits the first opening 41, the intensity of the exiting laser light L is smaller than a predetermined desired intensity. The desired intensity is set arbitrarily.

[0048] In other words, the internal flow path 43 has a structure in which the laser light L that enters through the first opening 41 and is reflected by the internal flow path 43 does not exit from the first opening 41 with an intensity (output) greater than or equal to a desired intensity. The first flow path 43a, the second flow path 43b, and the third flow path 43c that constitute the internal flow path 43 are designed to have a structure that achieves the above-mentioned effects.

[0049] When the beam damper 40 absorbs the laser light L, the laser light L is converted into heat, causing an increase in the temperature of the beam damper 40. In this regard, in the present embodiment, gas flows through the internal flow path 43 as will be described later, so that the increase in temperature of the beam damper 40 can be suppressed.

[0050] Furthermore, in order to suppress a temperature rise in the beam damper 40, concave and convex portions (not shown) may be formed on at least the outer surface (e.g., the outer peripheral side surface 31b or the lower surface 31c) of the beam damper 40. In such a case, the surface area of ​​the outer surface of the beam damper 40 can be increased to promote heat dissipation (cooling of the beam damper 40) of the beam damper 40. Furthermore, a cooling mechanism (not shown) may be further provided outside the beam damper 40 to promote heat dissipation (cooling of the beam damper 40). In one example, the cooling mechanism forms a refrigerant flow path outside the beam damper 40.

[0051] Furthermore, gas within the chamber 10 flows into the first opening 41 of the beam damper 40, flows through the internal flow path 43, and is discharged to the exhaust path 50 described below. Therefore, the internal flow path 43 also functions as the first gas flow path in the present disclosure. Note that a gas flow path may be provided separately from the internal flow path 43 inside the beam damper 40.

[0052] 6 to 10 , an exhaust path 50 is provided below the beam damper 40. The exhaust path 50 is arranged in an annular shape so as to surround at least the second opening 42, and is in communication with the internal flow path 43 via the second opening 42. In this embodiment, the exhaust path 50 is airtightly attached to the beam damper 40 so as to surround the inner lower side surface 40d and the bottom surface 40e of the beam damper 40.

[0053] Three exhaust ports 51 are formed on the underside of the exhaust path 50, for example, at different positions in an annular (circumferential) shape. An exhaust pipe 52 is connected to each exhaust port 51. The exhaust pipe 52 is connected to an exhaust mechanism (not shown), such as a vacuum pump. In this case, gas flowing through the internal flow path 43 of the beam damper 40 is exhausted via the exhaust path 50, the exhaust ports 51, and the exhaust pipe 52.

[0054] A cover housing portion 60 is provided on the upper portion of the outer peripheral side surface 40f of the beam damper 40. The cover housing portion 60 is attached in an annular shape around the entire outer periphery of the beam damper 40. The cover housing portion 60 has a rectangular shape with an open top in a cross-sectional view, and is configured to be able to house the open-close cover 12 when the open-close cover 12 closes the load / unload opening 16.

[0055] The wafer holding unit 30 has a through-hole 70 formed therein that opens to the upper surface 31 a of the stage 31 and penetrates through in the thickness direction. Note that a plurality of through-holes 70 may be formed. A flow path 71 extending substantially vertically downward from the through-hole 70 is provided below the wafer holding unit 30. The laser light L irradiated from the laser irradiation unit 20 passes through the through-hole 70, and the laser light L or a gas also flows through the flow path 71. The through-hole 70 and the flow path 71 function as a passage for the laser light L in the present disclosure, and also function as a third gas flow path in the present disclosure.

[0056] An air supply path 72 is connected to the lower end of the flow path 71. The air supply path 72 is connected to an exhaust mechanism (not shown), such as a vacuum pump, via an exhaust pipe (not shown). The air supply path 72 may be connected to the exhaust path 50 described above. Gas within the chamber 10 is then exhausted from the exhaust path via the through-hole 70 and the flow path 71.

[0057] An air supply unit 73 that supplies gas to the air supply path 72 is provided on a side surface of the air supply path 72. The air supply unit 73 includes, for example, a fan and a filter. A transmission window 74 that allows the laser light L to pass through is formed on the bottom surface of the air supply path 72.

[0058] A power meter 75 is provided on the underside of the air supply path 72 below the wafer holding unit 30. A transmission window 76 is formed on the upper surface of the power meter 75 at a position corresponding to the transmission window 74 of the air supply path 72. The laser light L irradiated from the laser irradiation unit 20 enters the power meter 75 via the cover 33, the through-hole 70, the flow path 71, the air supply path 72, the transmission window 74, and the transmission window 76. The power meter 75 measures the power (output) of the laser light L. The power meter 75 also measures the positional relationship between the laser light L and the wafer W when the wafer W is not held on the wafer holding unit 30. The laser irradiation unit 20 may be calibrated based on the measurement results of the power meter 75. Furthermore, a beam profiler (not shown) may be provided on the underside of the air supply path 72 below the wafer holding unit 30. The beam profiler detects the shape and position of the beam. The laser light L before being received by the power meter 75 may be split and received by a beam profiler.

[0059] In this embodiment, the laser light L and the gas flow through the through-hole 70 and the flow path 71, but the flow path for the laser light L and the flow path for the gas may be provided separately.

[0060] The wafer holding unit 30 has a plurality of, for example, three, through-holes 80 formed therein, which open to the upper surface 31 a of the stage 31 and penetrate through the wafer holding unit 30 in the thickness direction. A plurality of, for example, three, exhaust paths 81 are provided below the wafer holding unit 30, each extending substantially vertically downward from each through-hole 80. The three exhaust paths 81 are connected to an exhaust mechanism (not shown), such as a vacuum pump. In this case, as will be described later, gas supplied from the gas supply unit 73 flows sequentially through the gas supply path 72, the flow path 71, the through-hole 70, the cover 33, the through-hole 80, and the exhaust path 81 before being exhausted.

[0061] As shown in FIG. 2 , the wafer processing apparatus 1 is provided with at least one control unit 100. The control unit 100 processes computer-executable instructions that cause the wafer processing apparatus 1 to perform the various processes described in this disclosure. The control unit 100 may be configured to control each element of the wafer processing apparatus 1 to perform the various processes described herein. In one embodiment, part or all of the control unit 100 may be included in the wafer processing apparatus 1. The control unit 100 may include a processing unit, a storage unit, and a communication interface. The control unit 100 is realized, for example, by a computer. The processing unit may be configured to read from the storage unit a program that provides logic or routines that enable various control operations and to execute the read program to perform various control operations. This program may be stored in the storage unit in advance or may be acquired via a medium when needed. The acquired program is stored in the storage unit and read from the storage unit by the processing unit for execution. The medium may be various computer-readable storage media or a communication line connected to the communication interface. The storage medium may be temporary or non-temporary. The processing unit may be a CPU (Central Processing Unit). The storage unit may include a RAM (Random Access Memory), a ROM (Read Only Memory), a HDD (Hard Disk Drive), a SSD (Solid State Drive), or a combination thereof. The communication interface may communicate with the wafer processing apparatus 1 via a communication line such as a LAN (Local Area Network).

[0062] In the wafer processing apparatus 1 having the above configuration, the laser processing of St2 described above is performed. First, the access cover 12 in the chamber 10 is raised to open the loading / unloading port 16. Next, a wafer W is loaded into the chamber 10 by a wafer transfer device (not shown) provided outside the wafer processing apparatus 1, and is transferred to and held by the wafer holder 30. After that, the wafer transfer device leaves, and the access cover 12 is lowered to close the loading / unloading port 16.

[0063] Next, with a downflow generated in the chamber 10, the laser irradiation unit 20 irradiates the entire first surface Wa of the wafer W with laser light L to planarize the first surface Wa. At this time, as shown in Fig. 5 , the laser irradiation unit 20 moves the irradiation point P of the laser light L in the X-axis direction and also in the Y-axis direction. The laser irradiation unit 20 then irradiates the entire first surface Wa of the wafer W with the laser light L.

[0064] Here, when laser light L is irradiated from laser irradiation unit 20 onto the entire first surface Wa, irradiation point P of laser light L is moved in the X-axis direction and the Y-axis direction, and therefore irradiation point P may deviate radially outward from wafer W. This laser light L that has deviated from wafer W enters through first opening 41 of beam damper 40 and is attenuated in internal flow path 43. This prevents laser light L from escaping from first opening 41. Furthermore, even if laser light L does exit from first opening 41, the intensity of the escaping laser light L can be made smaller than a predetermined desired intensity.

[0065] According to this embodiment, the beam damper 40 receives and absorbs the laser light L from the laser irradiation unit 20 along the entire circumference of the wafer W held by the wafer holding unit 30, thereby preventing the laser light L from reaching below the wafer holding unit 30. As a result, damage to device components due to the laser light L can be prevented. In other words, since the beam damper 40 is provided along the entire circumference of the outer periphery of the wafer W, the laser light L can be moved and irradiated over the entire surface of the wafer W.

[0066] It should be noted that the configuration and shape of the beam damper 40 are not limited to the above example. In the technology of the present disclosure, the beam damper refers to a device that receives laser light and has the function of preventing damage to device components due to reflection of the laser light, as described above.

[0067] Here, in laser processing, when a wafer is irradiated with laser light, particles are generated from the wafer and scattered throughout the chamber, creating a problem of efficiently exhausting the generated particles from the chamber. Therefore, next, the airflow within the chamber 10 during laser processing in St2 will be described. As shown in FIG. 11 , gas is introduced into the chamber 10 from the outside of the fixed cover 11 of the chamber 10 through the gas inlet 13, generating a downflow within the chamber 10. In this case, gas may be supplied to the gas inlet 13 from a gas supply source (not shown) provided outside the chamber 10 to generate a downflow within the chamber 10. Alternatively, gas may be supplied into the chamber 10 through the gas inlet 14 by the gas supply unit 15, which also generates a downflow within the chamber 10. Alternatively, a downflow may be generated within the chamber 10 by evacuating the chamber 10 from an exhaust mechanism connected to the exhaust path 50 and an exhaust mechanism connected to the air supply path 72.

[0068] The gas in the chamber 10 flows over the first surface Wa of the wafer W or along the radially outer side of the wafer W, and is exhausted by sequentially flowing through the first opening 41, the internal flow path 43, the second opening 42, the exhaust path 50, the exhaust port 51, and the exhaust pipe 52. Hereinafter, this gas path may be referred to as a first gas path G1.

[0069] Furthermore, gas supplied from the gas supply unit 73 flows sequentially through the gas supply path 72, the flow path 71, the through-hole 70, the cover 33, the through-hole 80, and the exhaust path 81 before being discharged. At this time, the gas flowing upward from the through-hole 70 flows within the cover 33 and therefore does not impinge on the backside of the wafer W held by the wafer holder 30. Furthermore, gas flowing from within the chamber 10 into the space between the wafer W and the stage 31 flows along the upper surface 31a of the stage 31 and is discharged through the through-hole 80 and the exhaust path 81. Hereinafter, this gas path may be referred to as a second gas path G2. Note that, because the gas supplied from the gas supply unit 73 flows sequentially through the gas supply path 72 and the flow path 71, adhesion of particles to the power meter 75 provided below the gas supply path 72 can be suppressed. As a result, it is possible to avoid deterioration in power measurement accuracy due to particle adhesion to the power meter 75 and the risk of damage or burning due to laser heating of accumulated particles.

[0070] Here, in the laser processing of St2, when the laser irradiation unit 20 irradiates the first surface Wa of the wafer W with laser light L, particles emerge from the first surface Wa. In this regard, since a downflow is formed within the chamber 10, it is possible to prevent particles from scattering within the chamber 10 and adhering to the wafer W. Furthermore, since the chamber 10 is evacuated, it is possible to efficiently discharge particles and prevent particles from remaining within the chamber 10.

[0071] Furthermore, the gas inside chamber 10 is sucked out by an exhaust mechanism connected to exhaust path 50 and an exhaust mechanism connected to air supply path 72, creating a negative pressure inside chamber 10 relative to the outside of chamber 10. In this case, the gas inside chamber 10 is prevented from leaking out, and furthermore, particles inside chamber 10 are prevented from leaking out of chamber 10.

[0072] Next, another embodiment of the wafer processing apparatus 1 will be described. As shown in FIG. 12 , the beam damper 40 may be disposed along the outer periphery of the wafer holding unit 30, spaced apart from the outer periphery. In this case, a gap is formed between the inner upper side surface 40 b of the beam damper 40 and the outer periphery of the wafer holding unit 30 (the outer periphery side surface 31 b and the bottom surface 31 c of the stage 31), and this gap forms a gas flow path 200 as a second gas flow path. The gas flow path 200 is formed along the outer periphery side surface 31 b and the bottom surface 31 c of the stage 31 and along the step portion 40 c of the inner upper side surface 40 b of the beam damper 40. The gas flow path 200 may be connected to the exhaust path 50 or the gas supply path 72, or may be connected to another exhaust path (not shown).

[0073] In this embodiment, when a downflow is generated in the chamber 10 as shown in FIG. 13, in addition to the first gas path G1 and the second gas path G2 similar to those in FIG. 11, the gas in the chamber 10 flows through the gas flow path 200 (third gas path G3) and is then discharged.

[0074] Next, another embodiment of the wafer processing apparatus 1 will be described. As shown in Figure 14, in the chamber 10, the openable cover 12 may be provided radially outside the cylindrical portion 11b of the fixed cover 11. A gas inlet 210 serving as a second gas inlet is formed in an annular shape between the fixed cover 11 and the openable cover 12. The gas inlet 210 is formed to allow gas to flow into the chamber 10.

[0075] 15 , when a downflow is generated in the chamber 10, gas flows in through the gas inlet 210 (fourth gas path G4), flows sequentially through the first opening 41, the internal flow path 43, the second opening 42, the exhaust path 50, the exhaust port 51, and the exhaust pipe 52, and is then discharged. At this time, the downward flow of gas from the gas inlet 210 can direct the gas in the chamber 10 toward the first opening 41. At this time, gas also flows in through the gap between the lower end of the openable cover 12 and the cover housing portion 60 (fifth gas path G5). Note that the fourth gas path G4 and the fifth gas path G5 may be supplied with gas from a gas supply source (not shown) provided outside the chamber 10.

[0076] Here, if gas flows radially outward over the first surface Wa of the wafer W, there is a risk that the gas will collide with the opening / closing cover 12 and rise. This gas is sucked into the first opening 41 and is prevented from rising, but in addition, the downward flow of gas flowing in from the gas inlet 210 can also prevent the gas from rising.

[0077] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims. For example, the components of the above-described embodiments may be arbitrarily combined. Such an arbitrary combination naturally provides the functions and effects of each of the components involved in the combination, and also provides other functions and effects that are apparent to those skilled in the art from the description of this specification.

[0078] Furthermore, the effects described herein are merely descriptive or exemplary and are not limiting. In other words, the technology according to the present disclosure may achieve other effects that are apparent to those skilled in the art from the description of this specification, in addition to or in place of the above-described effects.

[0079] REFERENCE SIGNS LIST 1 wafer processing apparatus 20 laser irradiation unit 30 wafer holding unit 40 beam dumper L laser light W wafer

Claims

1. A substrate processing apparatus for processing a substrate, comprising: a substrate holding section for holding the substrate; a laser irradiation section for irradiating laser light onto the substrate held by the substrate holding section; and a beam damper arranged to surround the entire outer periphery of the substrate holding section, the beam damper having an opening for allowing the laser light to enter.

2. The substrate processing apparatus according to claim 1, wherein the laser irradiation section moves an irradiation point of the laser light with respect to the substrate held by the substrate holding section.

3. The substrate processing apparatus according to claim 1, wherein the beam damper has an internal flow path connected to the opening, and the internal flow path has a structure such that the laser light entering from the opening and reflected by the internal flow path does not exit from the opening with an intensity greater than a desired intensity.

4. The substrate processing apparatus of claim 3, wherein said internal flow passage extends downward and radially inward from said opening.

5. The substrate processing apparatus according to claim 3, wherein an inner surface of said internal flow passage absorbs said laser light.

6. The substrate processing apparatus according to claim 1, wherein the beam damper has a first gas passage connected to the opening.

7. The substrate processing apparatus according to claim 6, further comprising an exhaust passage provided below said beam damper and communicating with said first gas passage.

8. The substrate processing apparatus according to claim 1, wherein the beam damper is provided in contact with an outer periphery of the substrate holding part or is integral with the substrate holding part.

9. The substrate processing apparatus according to claim 1, further comprising a second gas passage provided between said beam damper and said substrate holder.

10. The substrate processing apparatus according to claim 9, wherein the beam damper is provided along an outer periphery of the substrate holding part at a distance from the outer periphery, and the second gas flow path is formed between an inner periphery side surface of the beam damper and an outer periphery side surface of the substrate holding part.

11. The substrate processing apparatus according to claim 1, further comprising a third gas passage penetrating said substrate holding section in a thickness direction.

12. The substrate processing apparatus according to claim 1, further comprising a chamber forming a processing space between said laser irradiation section and said substrate holding section, and a first gas inlet being formed between said chamber and said laser irradiation section.

13. The substrate processing apparatus of claim 12, wherein the chamber has a fixed cover configured so that its diameter increases from the laser irradiation section to the substrate holding section, and an opening / closing cover formed at the bottom of the fixed cover for opening and closing an opening for loading and unloading the substrate.

14. The substrate processing apparatus according to claim 13, further comprising a second gas inlet formed between said fixed cover and said openable cover.

15. The substrate processing apparatus of claim 12, further comprising an exhaust port for exhausting the interior of the chamber.

16. The substrate processing apparatus according to claim 15, further comprising a control unit that controls exhaust from said exhaust port so that the inside of said chamber becomes negative pressure relative to the outside of said chamber.

17. A substrate processing method for processing a substrate, comprising: irradiating a laser beam from a laser irradiation unit onto the substrate held by a substrate holding unit; and attenuating the laser beam by causing the laser beam to enter an opening in a beam damper, the opening being provided so as to surround the entire outer periphery of the substrate holding unit.

18. The substrate processing method according to claim 17, wherein, when irradiating the laser light, the laser irradiation section moves an irradiation point of the laser light with respect to the substrate held by the substrate holding section.

19. A substrate processing method as described in claim 17, wherein, when the laser light is attenuated, in an internal flow path provided in the beam damper, the laser light which enters through the opening and is reflected by the internal flow path is not allowed to exit from the opening with an intensity greater than a desired intensity.

20. The substrate processing method according to claim 17, further comprising flowing a gas through a gas flow passage provided in the beam damper and connected to the opening.

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