Laser amplifier, laser apparatus, and method of manufacturing electronic device

Abstract

To provide a laser amplifier in which the deformation of seed light due to a thermal lens is suppressed even if the energy of excitation light becomes high.SOLUTION: A laser amplifier includes a laser amplification medium 1b having a rectangular cross section perpendicular to an optical path of seed light, a pair of metallic blocks 2a and 2b joined to two wider surfaces 11 and 12 facing each other among four surfaces of the laser amplification medium parallel to the optical path, a pumping source that outputs pumping light for pumping the laser amplification medium, and a collimating lens that collimates the pumping light.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to laser amplifiers, laser apparatus, and methods of manufacturing electronic devices. [Background technology]

[0002] In recent years, semiconductor exposure devices have been required to improve their resolution in response to the miniaturization and high integration of semiconductor integrated circuits. To this end, the wavelength of light emitted from exposure light sources has been shortened. For example, KrF excimer laser devices, which output laser light with a wavelength of approximately 248 nm, and ArF excimer laser devices, which output laser light with a wavelength of approximately 193 nm, are used as gas laser devices for exposure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Summary of the specification of U.S. Patent No. 5,159,605

[0004] A laser amplifier according to one aspect of the present disclosure includes a laser amplification medium having a rectangular cross section perpendicular to an optical path axis of seed light, a pair of metal blocks joined to two opposing wider surfaces of four surfaces of the laser amplification medium parallel to the optical path axis, an excitation light source that outputs excitation light that excites the laser amplification medium, and a collimating lens that collimates the excitation light.

[0005] A laser device according to one aspect of the present disclosure includes a seed laser that outputs pulsed seed light, a laser amplification medium having a rectangular cross section perpendicular to the optical path axis of the seed light, a pair of metal blocks joined to two opposing wider surfaces of the four surfaces of the laser amplification medium that are parallel to the optical path axis, an excitation light source that outputs excitation light that excites the laser amplification medium, and a collimating lens that collimates the excitation light.

[0006] A method for manufacturing an electronic device according to one aspect of the present disclosure includes generating laser light using a laser apparatus including a seed laser that outputs pulsed seed light, a laser amplification medium having a rectangular cross section perpendicular to the optical path axis of the seed light, a pair of metal blocks joined to two opposing wider surfaces of the four surfaces of the laser amplification medium that are parallel to the optical path axis, an excitation light source that outputs excitation light that excites the laser amplification medium, and a collimating lens that collimates the excitation light, laser processing an interposer substrate with the laser light to produce an interposer, bonding the interposer and an integrated circuit chip to electrically connect them to each other, and bonding the interposer and a circuit board to electrically connect them to each other. [Brief explanation of the drawings]

[0007] Some embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which: [Figure 1] FIG. 1 shows the configuration of a laser processing system in a comparative example. [Figure 2] FIG. 2 is a cross-sectional view of an amplification unit in a comparative example. [Figure 3] FIG. 3 shows the light intensity distribution of the laser light when the pumping power of the pumping light is 0 W in the comparative example. [Figure 4] FIG. 4 shows the light intensity distribution of the laser light when the pumping power of the pumping light is 120 W in the comparative example. [Figure 5] FIG. 5 is a cross-sectional view of the amplification unit in the first embodiment. [Figure 6] FIG. 6 shows the light intensity distribution of the laser light when the pumping power of the pumping light is 120 W in the first embodiment. [Figure 7] FIG. 7 is a graph showing the relationship between the pumping power of the pumping light and the output power of the laser light in the comparative example and the first embodiment. [Figure 8] FIG. 8 is a cross-sectional view of an amplification unit according to the second embodiment. [Figure 9] FIG. 9 shows a schematic configuration of the electronic device. [Figure 10] FIG. 10 is a flowchart showing a method for manufacturing an electronic device. Embodiment

[0008] <Contents> 1. Comparative Example 1.1 Laser processing system 1.2 Laser Amplifier 100 1.2.1 Configuration 1.2.2 Operation 1.3 Amplification unit AMP 1.4 Issues with the comparative example 2. An embodiment in which the cross section of the laser amplification medium 1b is rectangular 2.1 Configuration 2.2 Operation 2.3 Effect 3. Embodiment in which the metal blocks 2a and 2b include the flow path 2c 3.1 Configuration and operation 3.2 Effect 4.Other 4.1 Electronic Devices Containing Interposer IP 4.2 Supplementary Information

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The embodiments described below show some examples of the present disclosure and do not limit the content of the present disclosure. Furthermore, not all of the configurations and operations described in each embodiment are necessarily essential as the configurations and operations of the present disclosure. Note that the same components are given the same reference symbols, and redundant explanations will be omitted.

[0010] 1. Comparative Example 1.1 Laser processing system 1 shows the configuration of a laser processing system in a comparative example. The comparative example of the present disclosure is a configuration that the applicant recognizes as being known only by the applicant, and is not a publicly known example that the applicant acknowledges. The laser processing system includes a seed laser SL, a laser amplifier 100, and a laser irradiation device 200.

[0011] The seed laser SL is a laser oscillator that outputs pulsed seed light SB. The wavelength of the seed light SB is, for example, approximately 1030 nm. The laser amplifier 100 amplifies the seed light SB and outputs pulsed laser light LB. The laser light LB may be converted by a wavelength converter (not shown) to the oscillation wavelength of a KrF excimer laser device or an ArF excimer laser device (not shown) and further amplified by such an excimer laser device. The laser irradiation device 200 includes an irradiation optical system (not shown) for irradiating a workpiece (not shown) with the laser light LB. The workpiece is, for example, an interposer substrate for manufacturing an interposer IP that connects an integrated circuit chip IC and a circuit board CS, which will be described later with reference to FIG. 9.

[0012] 1.2 Laser Amplifier 100 1.2.1 Configuration The laser amplifier 100 includes a pump laser PL, an end cap EC, a collimating lens CL, a focusing lens FL, dichroic mirrors DM1 and DM2, and an amplification unit AMP. Although the following description will be given of the case where the laser amplifier 100 is a forward-pumped laser amplifier, the laser amplifier 100 may also be a backward-pumped laser amplifier or a double-end-pumped laser amplifier.

[0013] The amplification unit AMP includes a laser amplification medium 1a (see FIG. 2). The laser amplification medium 1a is, for example, a crystal of Yb:YAG (Ytterbium-doped Yttrium Aluminum Garnet).

[0014] The pump laser PL is an excitation light source that outputs excitation light PB that excites the laser amplification medium 1a, and is configured, for example, by a semiconductor laser or a solid-state laser. The wavelength of the excitation light PB is set according to the absorption wavelength of the amplification unit AMP. When the laser amplification medium 1a is a Yb:YAG crystal, the wavelength of the excitation light PB is set to either 940 nm or 969 nm.

[0015] The end cap EC is placed at the output end of the optical fiber connected to the pump laser PL.

[0016] The collimating lens CL is disposed in the optical path of the excitation light PB emitted from the end cap EC. The focal length of the collimating lens CL is, for example, 12 mm.

[0017] The focus lens FL is disposed in the optical path of the excitation light PB emerging from the collimator lens CL. The focal length of the focus lens FL is, for example, 250 mm.

[0018] The dichroic mirror DM1 is disposed obliquely with respect to the optical path axis of the seed light SB output from the seed laser SL and the optical path axis of the excitation light PB output from the focus lens FL. The dichroic mirror DM2 is disposed obliquely with respect to the optical path axis of the laser light LB output from the amplification unit AMP. The dichroic mirrors DM1 and DM2 are configured to reflect wavelength components contained in the seed light SB and the laser light LB and to transmit wavelength components contained in the excitation light PB.

[0019] 1.2.2 Operation The pump light PB output from the pump laser PL is emitted as divergent light from the end cap EC. The pump light PB is converted into parallel light by the collimating lens CL. The pump light PB output from the collimating lens CL is converted into convergent light by the focusing lens FL. Figure 1 shows only the optical path axis of the light beam.

[0020] The excitation light PB emitted from the focus lens FL passes through the dichroic mirror DM1 and is collected at the first end E1 of the laser amplification medium 1a included in the amplification unit AMP.

[0021] The seed light SB emitted from the seed laser SL is reflected by the dichroic mirror DM1 and enters the first end E1. It is desirable that the pump light PB and the seed light SB entering the amplification unit AMP are coaxial with each other. In the present disclosure, "coaxial," "parallel," and "perpendicular" do not necessarily mean perfectly coaxial, parallel, and perpendicular, but also include an error within a practical range, for example, an error within 5°.

[0022] The laser amplification medium 1a included in the amplification unit AMP is excited by the energy of the pumping light PB and amplifies the seed light SB. The amplified seed light SB is emitted as laser light LB from a second end E2 of the laser amplification medium 1a. The laser light LB emitted from the second end E2 is reflected by a dichroic mirror DM2 and output from the laser amplifier 100.

[0023] The pumping light PB is, for example, a continuous wave laser light. Alternatively, the pumping light PB may be a pulsed laser light, in which case synchronization control is performed so that the pulse of the seed light SB and the pulse of the pumping light PB overlap in the amplification unit AMP.

[0024] A part of the pumping light PB may pass through the laser amplification medium 1a and be emitted from the second end E2. The pumping light PB that has been emitted from the second end E2 passes through the dichroic mirror DM2 and enters a beam damper (not shown).

[0025] 1.3 Amplification unit AMP Fig. 2 is a cross-sectional view of an amplification unit AMP in a comparative example. The direction of the optical path axes of the pump light PB and seed light SB incident on the amplification unit AMP is defined as the Z direction. The cross section shown in Fig. 2 is perpendicular to the Z direction. The amplification unit AMP includes a laser amplification medium 1a, a pair of metal blocks 2a and 2b, and a pair of heat sinks 3a and 3b.

[0026] The laser amplifying medium 1a has a rectangular prism shape that is long in the Z direction. The metal blocks 2a and 2b contain aluminum or copper, each have a rectangular prism shape, and are arranged in contact with the laser amplifying medium 1a. The lengths of the metal blocks 2a and 2b in the Z direction are approximately the same as the length of the laser amplifying medium 1a in the Z direction. The cross section of the optical path of the pumping light PB that enters the laser amplifying medium 1a coaxially with the seed light SB is shown by the dashed line in Figure 2. Heat generated inside the laser amplifying medium 1a by the energy of the pumping light PB is discharged to the outside of the laser amplifying medium 1a by thermal conduction to the metal blocks 2a and 2b.

[0027] However, since the thermal conductivity of the laser amplification medium 1a is low, it is not desirable to make the distance from the optical path of the pumping light PB, which is the region where heat is generated inside the laser amplification medium 1a, to the contact surfaces with the metal blocks 2a and 2b too long. The length of one side of the cross section of the laser amplification medium 1a perpendicular to the Z direction is set to, for example, about 2 mm.

[0028] To promote heat dissipation to the metal blocks 2a and 2b, it is conceivable to bring all four surfaces 11 to 14 of the laser gain medium 1a parallel to the Z direction into contact with the metal blocks 2a and 2b. However, it is difficult to precisely machine the metal blocks 2a and 2b so that they come into close contact with all four surfaces 11 to 14 of the laser gain medium 1a, whose cross-sectional side length is approximately 2 mm, and poor contact increases thermal resistance. For this reason, the metal blocks 2a and 2b are brought into contact only with the two opposing surfaces 11 and 12 of the laser gain medium 1a, respectively. The opposing direction of the two surfaces 11 and 12 of the laser gain medium 1a that come into contact with the metal blocks 2a and 2b, respectively, is defined as the Y direction or -Y direction. The direction parallel to the surfaces 11 and 12 and perpendicular to the Z direction is defined as the X direction or -X direction.

[0029] Each of the metal blocks 2a and 2b has a surface 24 in contact with the laser amplification medium 1a, a first surface 21 on the opposite side thereof, and second and third surfaces 22 and 23 that intersect with the X direction and are parallel to the Z direction. The first to third surfaces 21 to 23 are contact surfaces that come into contact with the heat sinks 3a and 3b. Indium foils 2d and 2e are arranged on the first to third surfaces 21 to 23.

[0030] The heat sinks 3a and 3b include aluminum or copper. The heat sink 3a is located on the X-direction side of the metal blocks 2a and 2b, and the heat sink 3b is located on the -X-direction side. The heat sink 3a corresponds to the first member in this disclosure, and the heat sink 3b corresponds to the second member in this disclosure. The heat sinks 3a and 3b are arranged so that their rectangular grooves face each other and surround the metal blocks 2a and 2b. A portion of each of the metal blocks 2a and 2b is accommodated in the groove of the heat sink 3a, and another portion of each of the metal blocks 2a and 2b is accommodated in the groove of the heat sink 3b. The lengths of the heat sinks 3a and 3b in the Z direction are approximately the same as the lengths of the metal blocks 2a and 2b in the Z direction. Each of the heat sinks 3a and 3b includes a flow path 3c through which a cooling medium such as cooling water passes. The flow path 3c is connected to a heat exchanger and a pump (not shown). The cooling medium flows through the flow path 3c as indicated by the arrows IN and OUT, and cools the heat sinks 3a and 3b.

[0031] 1.4 Issues with the comparative example Fig. 3 shows the light intensity distribution of the laser light LB emitted from the second end E2 in a comparative example when the pumping power of the pumping light PB is 0 W. Fig. 4 shows the light intensity distribution of the laser light LB emitted from the second end E2 in a comparative example when the pumping power of the pumping light PB is 120 W. Contours of the light intensity are shown in the center of each of Fig. 3 and Fig. 4 together with a scale of relative values. The bottom of each of Fig. 3 and Fig. 4 shows the light intensity distribution Iy along the Y direction, and the left end shows the light intensity distribution Ix along the X direction.

[0032] As described above, the metal blocks 2a and 2b are in contact with only the two opposing surfaces 11 and 12 of the laser amplifying medium 1a. Even if air is flowed along the surfaces 13 and 14, the cooling efficiency of the laser amplifying medium 1a in the X and -X directions may be inferior to that in the Y and -Y directions. For this reason, heat is efficiently discharged in the Y and -Y directions, resulting in a steep temperature gradient in the Y direction inside the laser amplifying medium 1a, but heat is difficult to discharge in the X and -X directions, resulting in a long high-temperature region in the X direction inside the laser amplifying medium 1a, and a gentle temperature gradient in the X direction. When the temperature gradients differ between the Y and X directions in this way, a thermal lens with different refractive indices is formed inside the laser amplifying medium 1a in the Y and X directions.

[0033] When the pumping power is 0 W as shown in Figure 3, there is almost no temperature gradient, so the seed light SB inside the laser amplification medium 1a is hardly affected by thermal lensing, and the light intensity distribution of the laser light LB is almost circular. When the pumping power becomes 120 W as shown in Figure 4, the contour lines of the light intensity distribution of the laser light LB are stretched in the Y and -Y directions due to thermal lensing in the Y direction.

[0034] In contrast, the pumping light PB is multimode light and therefore is less susceptible to the effects of thermal lensing. This can cause a mismatch between the shape of the optical path of the seed light SB and the shape of the optical path of the pumping light PB inside the laser amplification medium 1a, resulting in a decrease in amplification efficiency.

[0035] The embodiments described below are related to suppressing the deformation of the seed light SB due to thermal lensing even when the energy of the excitation light PB increases, thereby suppressing the mismatch in the shapes of the optical paths of the seed light SB and the excitation light PB and suppressing the decrease in amplification efficiency.

[0036] 2. An embodiment in which the cross section of the laser amplification medium 1b is rectangular 2.1 Configuration 5 is a cross-sectional view of the amplifier unit AMP1 in the first embodiment. The configuration of the laser amplifier 100 is the same as that of the comparative example, except that the amplifier unit AMP1 is used instead of the amplifier unit AMP.

[0037] The amplification unit AMP1 includes a laser amplification medium 1b instead of the laser amplification medium 1a. The cross section of the laser amplification medium 1b perpendicular to the Z direction is rectangular. The length of the long side of the rectangle is preferably between two and five times the length of the short side.

[0038] The metal blocks 2a and 2b are bonded to two opposing wider surfaces 11 and 12 of the four surfaces 11 to 14 of the laser amplification medium 1b parallel to the Z direction. The length in the X direction of each of the metal blocks 2a and 2b is equal to or greater than the length in the X direction of the laser amplification medium 1b.

[0039] The laser amplification medium 1b and the metal blocks 2a and 2b may be joined by diffusion bonding, brazing, or soldering, but atomic diffusion bonding is most preferable. The metal blocks 2a and 2b are preferably atomic diffusion bonded to the entire surfaces 11 and 12. The thickness of the atomic diffusion bonded interface layer is about 100 nm. Of the four surfaces 11 to 14 of the laser amplification medium 1b parallel to the Z direction, the two narrower opposing surfaces 13 and 14 may be in contact with a gas such as air.

[0040] The diameter of the focused pumping light PB by the focus lens FL is preferably equal to or less than half the length of the short side of the cross section perpendicular to the Z direction of the laser amplification medium 1b, and equal to or less than one-fourth the length of the long side. For example, the length of the short side may be 2 mm, the length of the long side may be 5 mm, and the diameter of the focused pumping light PB may be 0.5 mm. The focused diameter is defined as 1 / e of the peak intensity at the focused position. 2 The full angle value in radians of the beam divergence of the pumping light PB focused by the focus lens FL is preferably equal to or less than the value obtained by dividing the length of the short side of the cross section perpendicular to the Z direction of the laser amplification medium 1b by the length of the laser amplification medium 1b in the Z direction.

[0041] 2.2 Operation Fig. 6 shows the light intensity distribution of the laser light LB emitted from the second end E2 when the pumping power of the pumping light PB is 120 W in the first embodiment. The center of Fig. 6 shows contour lines of the light intensity together with a scale of relative values. The bottom of Fig. 6 shows the light intensity distribution Iy along the Y direction, and the left end shows the light intensity distribution Ix along the X direction.

[0042] According to the first embodiment, the laser amplification medium 1b is longer in the X direction than in the Y direction and is in contact with the metal blocks 2a and 2b over a wide range in the X direction, so heat is discharged from the laser amplification medium 1b to the metal blocks 2a and 2b over a wide range in the X direction. As a result, areas away from the optical path of the excitation light PB in the X and -X directions are also cooled, so a temperature gradient occurs not only in the Y direction but also in the X direction. This reduces the difference in temperature gradient between the Y and X directions, and reduces the difference in the refractive index of the thermal lens between the Y and X directions.

[0043] 6, even when the pumping power of the pumping light PB is high, the light intensity distribution of the laser light LB has a shape close to a concentric circle. This can increase the coincidence between the shape of the optical path of the seed light SB and the shape of the optical path of the pumping light PB inside the laser amplification medium 1b, thereby improving the amplification efficiency.

[0044] 7 is a graph showing the relationship between the pumping power of the pumping light PB and the output power of the laser light LB in the comparative example and the first embodiment. The cross section perpendicular to the Z direction of the laser amplification medium 1a in the comparative example is a square of 2 mm × 2 mm, and the cross section perpendicular to the Z direction of the laser amplification medium 1b in the first embodiment is a rectangle of 2 mm × 5 mm. When the pumping power of the pumping light PB is low, there is not much difference in the output power of the laser light LB between the comparative example and the first embodiment, but when the pumping power exceeds 30 W, the improvement in the output power of the laser light LB in the first embodiment becomes significant. When the pumping power is 120 W, the output power of the laser light LB in the first embodiment is about 1.5 times that of the comparative example.

[0045] In other respects, the first embodiment may be similar to the comparative example.

[0046] 2.3 Effect (1) According to the first embodiment, the laser amplifier 100 includes a laser amplification medium 1b having a rectangular cross section perpendicular to the optical path axis of the seed light SB, a pair of metal blocks 2a and 2b joined to two opposing wider surfaces 11 and 12 of four surfaces 11 to 14 of the laser amplification medium 1b parallel to the optical path axis of the seed light SB, a pump laser PL that outputs excitation light PB that excites the laser amplification medium 1b, and a collimating lens CL that collimates the excitation light PB.

[0047] According to this, the cross section of the laser amplification medium 1b is rectangular, and the metal blocks 2a and 2b are joined to the two opposing wider surfaces 11 and 12 of the four surfaces 11 to 14, so that heat generated inside the laser amplification medium 1b by the energy of the pumping light PB can be released not only in the Y direction and the -Y direction perpendicular to the surfaces 11 and 12, but also in the X direction and the -X direction parallel to the surfaces 11 and 12. Therefore, the difference between the thermal gradient in the Y direction and the thermal gradient in the X direction can be reduced. This reduces the difference between the influence of thermal lensing in the Y direction and the influence of thermal lensing in the X direction on the seed light SB, and suppresses deformation of the cross-sectional shape of the optical path of the seed light SB. Therefore, it is possible to suppress mismatch between the optical path of the pumping light PB and the optical path of the seed light SB, and improve the amplification efficiency.

[0048] (2) According to the first embodiment, the length of the long side of the cross section of the laser amplification medium 1b is between two and five times the length of the short side.

[0049] The reason why it is preferable that it is 2 times or more is that it is possible to sufficiently improve the effect of releasing heat in the X direction and the -X direction, which are the directions of the long sides.The reason why it is preferable that it is 5 times or less is that even if the long sides are made longer, the effect of releasing heat in the X direction and the -X direction is difficult to improve, although the size of the laser amplification medium 1b increases.

[0050] (3) According to the first embodiment, the length in the X direction of each of the pair of metal blocks 2a and 2b is equal to or greater than the length of the long side of the cross section of the laser amplification medium 1b.

[0051] This allows heat to be released to the metal blocks 2a and 2b from the entire two opposing wider surfaces 11 and 12 of the four surfaces 11 to 14 of the laser amplification medium 1b, thereby further improving the effect of releasing heat in the X direction and the -X direction.

[0052] (4) According to the first embodiment, the laser amplifier 100 includes a focus lens FL that focuses the pumping light PB that has passed through the collimator lens CL onto the laser amplification medium 1b. The diameter of the focused pumping light PB by the focus lens FL is equal to or smaller than half the length of the short side of the cross section of the laser amplification medium 1b.

[0053] This allows the distance from the two surfaces 11 and 12 joining the metal blocks 2a and 2b to the optical path of the excitation light PB to be increased, and makes it possible to prevent part of the excitation light PB from entering the two surfaces 11 and 12 joining the metal blocks 2a and 2b.

[0054] (5) According to the first embodiment, the laser amplifier 100 includes a focus lens FL that focuses the pumping light PB that has passed through the collimator lens CL onto the laser amplification medium 1b. The diameter of the focused pumping light PB by the focus lens FL is equal to or smaller than one-fourth the length of the long side of the cross section of the laser amplification medium 1b.

[0055] This allows the distance from the two opposing narrower surfaces 13 and 14 of the four surfaces 11 to 14 of the laser amplification medium 1b to the optical path of the excitation light PB to be sufficiently increased, and the effect of dissipating the heat generated inside the laser amplification medium 1b by the energy of the excitation light PB in the X direction and the −X direction can be further improved.

[0056] (6) According to the first embodiment, the laser amplifier 100 includes a focus lens FL that focuses the pumping light PB that has passed through the collimator lens CL onto the laser amplification medium 1b. The value of the total angle, measured in radians, of the beam divergence of the pumping light PB focused by the focus lens FL is equal to or less than the value obtained by dividing the length of the short side of the cross section of the laser amplification medium 1b by the length in the Z direction parallel to the optical path axis of the laser amplification medium 1b.

[0057] This can prevent the excitation light PB from spreading and being incident on the two surfaces 11 and 12 that are joined to the metal blocks 2a and 2b.

[0058] (7) According to the first embodiment, the pair of metal blocks 2a and 2b are atomic diffusion bonded to the laser amplification medium 1b.

[0059] According to this, bonding can be performed at room temperature by atomic diffusion bonding, and residual stress after bonding is small, so that deterioration of performance of the laser amplification medium 1b is suppressed. Furthermore, since the adhesion between the laser amplification medium 1b and the metal blocks 2a and 2b is high and the interface layer is thin, bonding with low thermal resistance can be achieved, and heat can be efficiently dissipated from the laser amplification medium 1b to the metal blocks 2a and 2b.

[0060] (8) According to the first embodiment, the pair of metal blocks 2a and 2b are atomic diffusion bonded to the entire two opposing wider surfaces 11 and 12 of the four surfaces 11 to 14 of the laser amplification medium 1b.

[0061] This allows heat to be efficiently released from the entire two opposing faces 11 and 12, which are wider among the four faces 11 to 14, to the metal blocks 2a and 2b.

[0062] (9) According to the first embodiment, of the four surfaces 11 to 14 of the laser amplification medium 1b parallel to the optical path axis of the seed light SB, the two narrower opposing surfaces 13 and 14 are in contact with the gas.

[0063] This means that there is no need to be concerned with the machining accuracy of the two narrower opposing surfaces 13 and 14 of the four surfaces 11 to 14, and it is sufficient to ensure the machining accuracy required for joining on the two wider opposing surfaces 11 and 12, so that joining between the laser amplification medium 1b and the metal blocks 2a and 2b can be reliably performed.

[0064] (10) According to the first embodiment, the laser amplifier 100 includes heat sinks 3a and 3b in contact with the pair of metal blocks 2a and 2b.

[0065] According to this, since the heat sinks 3a and 3b are provided in addition to the metal blocks 2a and 2b joined to the laser amplification medium 1b, the heat dissipated from the laser amplification medium 1b to the metal blocks 2a and 2b can be efficiently discharged from the metal blocks 2a and 2b.

[0066] (11) According to the first embodiment, the heat sinks 3a and 3b include either aluminum or copper.

[0067] This allows the heat sinks 3a and 3b to be made of inexpensive material with high thermal conductivity.

[0068] (12) According to the first embodiment, the heat sinks 3a and 3b include the flow passages 3c through which the cooling medium passes.

[0069] This allows the heat to be efficiently removed from the heat sinks 3a and 3b by the cooling medium.

[0070] (13) According to the first embodiment, indium foils 2d and 2e are disposed on the contact surfaces between the pair of metal blocks 2a and 2b and the heat sinks 3a and 3b, respectively.

[0071] According to this, indium has high malleability and can ensure high adhesion between the metal blocks 2a and 2b and the heat sinks 3a and 3b, so that heat can be efficiently dissipated from the metal blocks 2a and 2b to the heat sinks 3a and 3b.

[0072] (14) According to the first embodiment, the heat sinks 3a and 3b are in contact with the first, second, and third surfaces 21, 22, and 23 of each of the pair of metal blocks 2a and 2b, the first surface 21 being opposite to the surface 24 joined to the laser amplification medium 1b, and the second and third surfaces 22 and 23 intersecting with the X direction, which is the direction of the long side of the cross section of the laser amplification medium 1b.

[0073] According to this, the heat sinks 3a and 3b come into contact with the first, second, and third surfaces 21, 22, and 23, so that heat can be efficiently dissipated from the metal blocks 2a and 2b to the heat sinks 3a and 3b.

[0074] (15) According to the first embodiment, the pair of metal blocks 2a and 2b are surrounded by and in contact with the heat sinks 3a and 3b.

[0075] This allows the pair of metal blocks 2a and 2b sandwiching the laser amplification medium 1b to be integrally held by the heat sinks 3a and 3b.

[0076] (16) According to the first embodiment, the heat sinks 3a and 3b include the heat sink 3a, which is a first member located on the X-direction side parallel to the long side of the cross section of the laser amplification medium 1b, and the heat sink 3b, which is a second member located on the −X-direction side.

[0077] According to this, the metal blocks 2a and 2b are surrounded by the heat sinks 3a and 3b, which include two members, so that the metal blocks 2a and 2b and the heat sinks 3a and 3b can be easily assembled and disassembled.

[0078] (17) According to the first embodiment, each of the pair of metal blocks 2a and 2b includes either aluminum or copper.

[0079] This allows the metal blocks 2a and 2b to be made of an inexpensive material with high thermal conductivity.

[0080] 3. Embodiment in which the metal blocks 2a and 2b include the flow path 2c 3.1 Configuration and operation 8 is a cross-sectional view of the amplifier unit AMP2 in the second embodiment. The configuration of the laser amplifier 100 is the same as that of the comparative example, except that the amplifier unit AMP2 is used instead of the amplifier unit AMP.

[0081] The amplification unit AMP2 does not necessarily have to include the heat sinks 3a and 3b or the indium foils 2d and 2e. The metal blocks 2a and 2b included in the amplification unit AMP2 include a flow path 2c through which a cooling medium such as cooling water passes. The flow path 2c is connected to a heat exchanger and a pump (not shown). The cooling medium flows through the flow path 2c as indicated by the arrows IN and OUT, and cools the metal blocks 2a and 2b.

[0082] In other respects, the second embodiment may be similar to the first embodiment.

[0083] 3.2 Effect (18) According to the second embodiment, each of the pair of metal blocks 2a and 2b includes a flow path 2c through which a cooling medium passes.

[0084] According to this, the metal blocks 2a and 2b can be cooled directly, so that the heat dissipated from the laser amplification medium 1b to the metal blocks 2a and 2b can be efficiently discharged from the metal blocks 2a and 2b.

[0085] 4.Other 4.1 Electronic Devices Containing Interposer IP Fig. 9 is a schematic diagram showing the configuration of an electronic device, which includes an integrated circuit chip IC, an interposer IP, and a circuit board CS.

[0086] The integrated circuit chip IC is, for example, a chip in which an integrated circuit (not shown) is formed on a silicon substrate, and the integrated circuit chip IC is provided with a plurality of bumps ICB that are electrically connected to the integrated circuit.

[0087] The interposer IP includes an insulating substrate with a plurality of through holes (not shown), each of which has a conductor (not shown) electrically connecting the front and back of the substrate. One surface of the interposer IP is formed with a plurality of lands (not shown), each of which is connected to a bump ICB, and each of the lands is electrically connected to one of the conductors in the through holes. The other surface of the interposer IP is provided with a plurality of bumps IPB, and each of the bumps IPB is electrically connected to one of the conductors in the through holes.

[0088] A plurality of lands (not shown) are formed on one surface of the circuit board CS, and the circuit board CS is provided with a plurality of terminals that are electrically connected to the lands, respectively.

[0089] 10 is a flowchart showing a method for manufacturing an electronic device. In S1, laser processing and wiring formation are performed on an interposer substrate that constitutes an interposer IP. Laser processing of the interposer substrate includes forming through holes by irradiating the interposer substrate with laser light LB. Wiring formation includes forming a conductive film on the inner wall surface of the through holes formed in the interposer substrate. Through these steps, an interposer IP is manufactured.

[0090] In S2, the interposer IP is bonded to the integrated circuit chip IC. This step includes, for example, placing the bumps ICB of the integrated circuit chip IC on the lands of the interposer IP and electrically connecting the bumps ICB to the lands.

[0091] In S3, the interposer IP is bonded to the circuit board CS. This step includes, for example, placing the bumps IPB of the interposer IP on the lands of the circuit board CS and electrically connecting the bumps IPB to the lands.

[0092] 4.2 Supplementary Information The above description is intended to be illustrative rather than limiting. Thus, it will be apparent to one skilled in the art that modifications can be made to the disclosed embodiments without departing from the scope of the claims. It will also be apparent to one skilled in the art that the disclosed embodiments can be used in combination.

[0093] Terms used throughout this specification and claims should be construed as "open ended" unless expressly stated otherwise. For example, words such as "comprise," "have," "comprise," and "equip" should be construed as meaning "without excluding the presence of elements other than those listed." In addition, the modifier "a" should be construed as meaning "at least one" or "one or more." In addition, the term "at least one of A, B, and C" should be construed as "A," "B," "C," "A+B," "A+C," "B+C," or "A+B+C." Furthermore, it should be construed as including combinations of these with elements other than "A," "B," and "C."

Claims

1. a laser amplification medium having a rectangular cross section perpendicular to the optical path axis of the seed light; a pair of metal blocks bonded to two opposing wider surfaces of the four surfaces of the laser amplification medium parallel to the optical path axis; a pumping light source that outputs pumping light for exciting the laser amplification medium; a collimating lens that collimates the excitation light; A laser amplifier comprising:

2. 2. The laser amplifier of claim 1, The length of the long side of the cross section is 2 times or more and 5 times or less than the length of the short side of the cross section. Laser amplifier.

3. 2. The laser amplifier of claim 1, The length of each of the pair of metal blocks in the direction of the long sides of the cross section is equal to or greater than the length of the long sides of the cross section. Laser amplifier.

4. 2. The laser amplifier of claim 1, a focusing lens that focuses the excitation light that has passed through the collimating lens onto the laser amplification medium; a diameter of the excitation light focused by the focus lens is equal to or less than half the length of a short side of the cross section; Laser amplifier.

5. 2. The laser amplifier of claim 1, a focusing lens that focuses the excitation light that has passed through the collimating lens onto the laser amplification medium; a diameter of the excitation light focused by the focus lens is equal to or less than one-fourth of the length of the long side of the cross section; Laser amplifier.

6. 2. The laser amplifier of claim 1, a focusing lens that focuses the excitation light that has passed through the collimating lens onto the laser amplification medium; a value of a total angle in radians of the beam divergence of the excitation light focused by the focus lens is equal to or less than a value obtained by dividing the length of the short side of the cross section by the length of the laser amplification medium in a direction parallel to the optical path axis, Laser amplifier.

7. 2. The laser amplifier of claim 1, the pair of metal blocks are atomic diffusion bonded to the laser amplification medium; Laser amplifier.

8. 2. The laser amplifier of claim 1, The pair of metal blocks are atomic diffusion bonded to the entire two surfaces. Laser amplifier.

9. 2. The laser amplifier of claim 1, Two narrower opposing surfaces of the four surfaces are in contact with the gas. Laser amplifier.

10. 2. The laser amplifier of claim 1, a heat sink in contact with the pair of metal blocks; Laser amplifier.

11. 11. The laser amplifier of claim 10, The heat sink includes either aluminum or copper. Laser amplifier.

12. 11. The laser amplifier of claim 10, The heat sink includes a flow path for passing a cooling medium. Laser amplifier.

13. 11. The laser amplifier of claim 10, an indium foil is disposed on a contact surface between each of the pair of metal blocks and the heat sink; Laser amplifier.

14. 11. The laser amplifier of claim 10, the heat sink is in contact with first, second, and third surfaces of each of the pair of metal blocks, the first surface being opposite to the surface bonded to the laser amplification medium, and the second and third surfaces intersecting the direction of the long side of the cross section; Laser amplifier.

15. 11. The laser amplifier of claim 10, The heat sink surrounds and contacts the pair of metal blocks. Laser amplifier.

16. 11. The laser amplifier of claim 10, The heat sink includes a first member located on one side in a direction parallel to a long side of the cross section and a second member located on the other side. Laser amplifier.

17. 2. The laser amplifier of claim 1, each of the pair of metal blocks contains either aluminum or copper; Laser amplifier.

18. 2. The laser amplifier of claim 1, Each of the pair of metal blocks includes a flow path for passing a cooling medium. Laser amplifier.

19. a seed laser that outputs pulsed seed light; a laser amplification medium having a rectangular cross section perpendicular to an optical path axis of the seed light; a pair of metal blocks bonded to two opposing wider surfaces of the four surfaces of the laser amplification medium parallel to the optical path axis; a pumping light source that outputs pumping light for exciting the laser amplification medium; a collimating lens that collimates the excitation light; A laser device comprising:

20. A method for manufacturing an electronic device, comprising: a seed laser that outputs pulsed seed light; a laser amplification medium having a rectangular cross section perpendicular to an optical path axis of the seed light; a pair of metal blocks bonded to two opposing wider surfaces of the four surfaces of the laser amplification medium parallel to the optical path axis; a pumping light source that outputs pumping light for exciting the laser amplification medium; a collimating lens that collimates the excitation light; generating a laser beam by a laser device comprising: laser processing the interposer substrate with the laser light to fabricate an interposer; coupling the interposer and the integrated circuit chip together to electrically connect them; The interposer and the circuit board are coupled to each other to electrically connect them together. A method for manufacturing an electronic device, comprising:

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