Method of manufacturing a nonlinear optical device

Abstract

Provided is a method for manufacturing a nonlinear optical device. A recess (10) is formed on a surface of a semiconductor substrate (100). A first liquid material (31) is filled into the recess (10) in a reduced pressure environment. A second liquid material (32) is brought into contact with the first liquid material (31) filled into the recess (10), thereby modulating a third liquid material (33). The third liquid material (33) is hardened, thereby forming a buried portion (310). The first liquid material (31) contains a first solute and a first solvent, or is composed only of the first solvent. The second liquid material (32) contains a second solute and a second solvent. The second solute contains a nonlinear optical polymer. The concentration of the second solute of the second liquid material (32) is higher than the concentration of the first solute of the first liquid material (31).

Description

Technical Field

[0001] This invention relates to a method for manufacturing a nonlinear optical device. Priority is claimed based on Japanese Patent Application No. 2020-130371, filed July 31, 2020. The entire contents of that Japanese patent application are incorporated herein by reference. Background Technology

[0002] A method for filling a micro-recesses formed on the surface of a substrate with a liquid material has been studied (e.g., see Patent Documents 1 to 5, see Non-Patent Document 1).

[0003] Patent Document 1: Japanese Patent Application Publication No. 2004-071934

[0004] Patent Document 2: Japanese Patent Application Publication No. 2004-103817

[0005] Patent Document 3: Japanese Patent Publication No. 2007-509769

[0006] Patent Document 4: Japanese Patent Application Publication No. 2011-210942

[0007] Patent Document 5: Japanese Patent Application Publication No. 2014-099525

[0008] Non-patent literature 1: H. Hiroshima and M. Komuro, “Control of Bubble Defects in UV Nanoimprint” Japanese Journal Applied Physics, Vol. 46, pp. 6391-6394 (Sep. 2007). Summary of the Invention

[0009] One aspect of the present invention relates to a method for manufacturing a nonlinear optical device, comprising the following:

[0010] The following are the procedures:

[0011] A recess is formed on the surface of a semiconductor substrate;

[0012] Under reduced pressure, the recess is filled with a first liquid material;

[0013] The second liquid material is brought into contact with the first liquid material filling the recess, thereby modulating the third liquid material; and

[0014] The third liquid material is hardened to form the embedded part.

[0015] The first liquid material comprises a first solute and a first solvent, or consists only of the first solvent.

[0016] The second liquid material comprises a second solute and a second solvent.

[0017] The second solute comprises a nonlinear optical polymer.

[0018] The concentration of the second solute in the second liquid material is higher than the concentration of the first solute in the first liquid material. Attached Figure Description

[0019] Figure 1 This is a schematic flowchart of the manufacturing method of the nonlinear optical device according to this embodiment.

[0020] Figure 2 This is a first schematic cross-sectional view showing the manufacturing process of the nonlinear optical device according to this embodiment.

[0021] Figure 3 This is a schematic top view showing the first example of a concave section.

[0022] Figure 4 This is a schematic top view showing the second example of a concave section.

[0023] Figure 5 This is a second schematic cross-sectional view showing the manufacturing process of the nonlinear optical device according to this embodiment.

[0024] Figure 6 This is a third schematic cross-sectional view showing the manufacturing process of the nonlinear optical device according to this embodiment.

[0025] Figure 7 This is a fourth schematic cross-sectional view showing the manufacturing process of the nonlinear optical device according to this embodiment.

[0026] Figure 8 This is the fifth schematic cross-sectional view showing the manufacturing process of the nonlinear optical device according to this embodiment.

[0027] Figure 9 This is a sixth schematic cross-sectional view showing the manufacturing process of the nonlinear optical device according to this embodiment.

[0028] Figure 10 This is the first schematic cross-sectional view showing the manufacturing process of No.2.

[0029] Figure 11 This is the second schematic cross-sectional view showing the manufacturing process of No.2.

[0030] Figure 12 This is a schematic cross-sectional view showing the manufacturing process of No.3.

[0031] Figure 13 It is a general top view of the device being evaluated.

[0032] Figure 14 This is an example of the measurement of the optical transmission fringe image of No. 2.

[0033] Figure 15 This is an example of calculating transmission loss for No. 2.

[0034] Figure 16 These are the evaluation results from No.1 to No.3.

[0035] Figure 17 This is a schematic cross-sectional view showing an example of the bottom.

[0036] Figure 18 This is an example of a synthetic route for side-chain copolymers. Detailed Implementation

[0037] <The problem to be solved by this invention>

[0038] Buried structures have been studied in nonlinear optics (NLO) devices. These buried structures are formed by filling recesses in the surface of a semiconductor substrate with NLO polymer. For example, a polymer solution containing dissolved NLO polymer is used. Specifically, the polymer solution is applied to the surface of the semiconductor substrate with the recesses and allowed to harden, thereby forming the buried portion.

[0039] With the miniaturization and high integration of NLO devices, there is a need to fill narrower and deeper recesses with polymer solutions. The narrower and deeper the recess, the more likely voids will remain after filling. For example, in cases where the embedded portion contains an optical waveguide, light may be scattered due to voids within the embedded portion. This can result in transmission loss.

[0040] To reduce voids, one could consider heating the polymer solution that fills the recesses. The increased temperature of the polymer solution makes the bubbles more mobile, thus reducing the voids.

[0041] Here, the NLO polymer comprises, for example, a host polymer and guest molecules. The guest molecules are dispersed within the host polymer. These guest molecules are polar molecules and possess NLO activity. If the polymer solution is heated, causing the temperature to rise to a level suitable for NLO polymer flow, the guest molecules may aggregate due to dipole interactions. Aggregation of the guest molecules may thus cause the NLO activity to disappear.

[0042] To reduce voids, one could consider filling the recesses with a polymer solution under pressure. It would be conceivable to cause the bubbles to shrink by applying pressure. Due to the shrinkage of the bubbles, a reduction in voids would be expected. However, the bubbles only shrink inversely with pressure. Therefore, it is impossible to completely eliminate the voids.

[0043] To reduce voids, one approach is to degas the polymer solution filling the recess under reduced pressure, for example. Reduced pressure degassing is considered to involve solvent evaporation. Solvent evaporation occurs at the surface of the polymer solution. Therefore, hardening begins from the surface of the polymer solution. During reduced pressure degassing, the polymer solution hardens from the surface, which may hinder degassing or create unevenness on the surface of the embedded portion. For example, in the case where the embedded portion contains an optical waveguide, surface unevenness may degrade optical properties. Therefore, it is necessary to move the optical waveguide away from the surface so that the impact on optical properties is sufficiently minimized. As a result, miniaturization of NLO devices may be hindered.

[0044] The object of the present invention is to form an embedded portion in an NLO device, the embedded portion having a smooth surface and few voids.

[0045] <Effects of the Invention>

[0046] According to the present invention, it is desirable to form an embedded portion with a smooth surface and few voids.

[0047] <Description of Embodiments of the Invention>

[0048] First, embodiments of the present invention and their descriptions are listed. However, the mechanism of action of the present invention includes conjecture. Whether the mechanism of action is correct or not does not limit the scope of the claims.

[0049] [1] A method for manufacturing a nonlinear optical device according to one aspect of the present invention includes the following (a) to (d).

[0050] (a) A recess is formed on the surface of a semiconductor substrate.

[0051] (b) Under reduced pressure, the recess is filled with the first liquid material.

[0052] (c) The second liquid material is brought into contact with the first liquid material filling the recess, thereby modulating the third liquid material.

[0053] (d) Harden the third liquid material to form the embedded part.

[0054] The first liquid material comprises a first solute and a first solvent, or consists only of the first solvent. The second liquid material comprises a second solute and a second solvent. The second solute comprises a nonlinear optical polymer. The concentration of the second solute in the second liquid material is higher than the concentration of the first solute in the first liquid material.

[0055] The second liquid material of the present invention has a higher concentration than the first liquid material. Here, the second liquid material is also referred to as a "high-concentration solution". The first liquid material is also referred to as a "low-concentration solution". However, "high concentration" and "low concentration" refer to the relative concentration between the second liquid material and the first liquid material, not the absolute concentration.

[0056] In the manufacturing method of the NLO device of the present invention, a low-concentration solution (first liquid material) is first filled into the recess. The first liquid material may consist only of a solvent. The low-concentration solution may have a low viscosity. It is conceivable that the low-concentration solution easily enters the recess. It is conceivable that bubbles easily move in the low-concentration solution. That is, it is conceivable that bubbles easily escape.

[0057] Furthermore, it is conceivable that even when exposed to a reduced pressure environment, low-concentration solutions would be difficult to harden from the surface.

[0058] After the recess is filled with a low-concentration solution, a high-concentration solution (second liquid material) is added to the low-concentration solution. The solute (NLO polymer) diffuses from the high-concentration solution to the low-concentration solution, thereby forming a mixed solution (third liquid material). The mixed solution in the recess hardens, thereby forming an embedded portion. In this invention, "hardening" means that the solute precipitates out by substantially removing the solvent from the solution.

[0059] As described above, in the method for manufacturing the NLO device of the present invention, a low-concentration solution (first liquid material) can penetrate to all parts of the recess, thus reducing the number of air bubbles. Therefore, a reduction in voids is also expected in the hardened embedded portion.

[0060] Furthermore, it is conceivable that hardening from the surface is difficult in low-concentration solutions (the first liquid material). Therefore, it is desirable for the surface of the embedded part to become smooth.

[0061] [2] The manufacturing method of the nonlinear optical device described in [1] above,

[0062] The first solute may, for example, contain a nonlinear optical polymer.

[0063] [3] The manufacturing method of the nonlinear optical device described in [1] or [2] above,

[0064] At least a portion of the recess may be formed, for example, to extend linearly along the surface of the semiconductor substrate.

[0065] The linearly extending recess can also be called a "slit" or similar term. Because the recess extends linearly, it is possible to fabricate, for example, a slit waveguide-type NLO device.

[0066] [4] A method for manufacturing a nonlinear optical device as described in any of [1] to [3] above,

[0067] The ratio of the depth of the recess to the width of the recess can be, for example, 0.5 to 12.

[0068] Hereinafter, the ratio of the depth (d) of the recess to the width (w) of the recess is also referred to as the "aspect ratio (d / w)". An aspect ratio of 0.5 or higher indicates, for example, the expectation of high integration. An aspect ratio of 12 or lower indicates, for example, the expectation of reduced voids.

[0069] [5] A method for manufacturing a nonlinear optical device as described in any of [1] to [4] above,

[0070] The recess can, for example, have a width of less than 170 nm.

[0071] In the manufacturing method of the NLO device of the present invention, for example, even a narrow recess with a width of less than 170 nm is expected to reduce the voids.

[0072] [6] A method for manufacturing a nonlinear optical device as described in any of [1] to [5] above,

[0073] The concentration of the first solute in the first liquid material may, for example, be from 0% by mass to 35% by mass. The concentration of the second solute in the second liquid material may, for example, be from 5% by mass to 40% by mass.

[0074] For example, the concentration of the first liquid material is 35% by mass or less, thereby reducing porosity. For example, the concentration of the second liquid material is 40% by mass or less, thereby shortening the time required for solute diffusion.

[0075] [7] A method for manufacturing a nonlinear optical device as described in any of [1] to [6] above,

[0076] Nonlinear optical polymers may, for example, comprise the following formula (I):

[0077] [Chemistry 1]

[0078]

[0079] The structure represented.

[0080] In the above equation (I), R 1 and R 2 Each can independently represent a hydrogen atom, alkyl, alkenyl, cycloalkyl, cycloalkenyl, alkoxy, haloalkyl, aryl, hydroxyl, thiol, or amino group.

[0081] The structure of formula (I) above can serve as an electron-withdrawing group (acceptor). Large NLO effects are expected in NLO polymers containing the structure of formula (I) above.

[0082] [8] In any of the methods for manufacturing nonlinear optical devices described in [1] to [7] above,

[0083] The first solvent and the second solvent may each comprise, for example, at least one selected from the group consisting of acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, cycloheptanone, acetylacetone, methylpentyl ketone, n-methyl ketone, γ-butyrolactone, tetrahydrofuran, chloroform, dibromomethane, 1,2-dichloroethane, 1,2-dibromoethane, 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane, 1,1,2-tribromoethane, 1,1,2,2-tetrabromoethane, ethyl acetate, butyl acetate, methyl lactate, ethyl lactate, butyl lactate, propylene glycol methyl ether, propylene glycol monomethyl ether acetate, and ethyl cellosolve acetate.

[0084] [9] A method for manufacturing a nonlinear optical device as described in any of [1] to [8] above,

[0085] The second solvent can be, for example, the same material as the first solvent. The second solute can be, for example, the same material as the first solute.

[0086] The second solvent is the same material as the first solvent, and the second solute is the same material as the first solute, thus, for example, it is expected that the second liquid material and the first liquid material will be mixed uniformly.

[0087]

[10] In the manufacturing method of the nonlinear optical device described in [1] above,

[0088] The first solute may, for example, comprise a nonlinear optical polymer. For example, at least a portion of the recess may be formed to extend linearly along the surface of the semiconductor substrate. The ratio of the depth to the width of the recess may be from 0.5 to 12. The recess may have a width of less than 170 nm. The concentration of the first solute in the first liquid material may be from 0% to 35% by mass. The concentration of the second solute in the second liquid material may be from 5% to 40% by mass.

[0089] <Detailed Description of Embodiments of the Invention>

[0090] Hereinafter, embodiments of the present invention (hereinafter also referred to as "this embodiment") will be described in detail. However, the following description does not limit the scope of the claims.

[0091] The geometric terms used in this embodiment (e.g., "parallel," "perpendicular," "straight line," etc.) are sufficient to substantially indicate the state. The geometric terms used in this embodiment should not be interpreted in a strict sense. For example, "parallel" indicates a state of being substantially parallel. That is, "parallel" can deviate slightly from the strictly defined state of "parallel." "Substantially parallel state" can, of course, include tolerances and errors in design, manufacturing, etc.

[0092] In this embodiment, unless otherwise stated, the description of "0.5 to 12" indicates a range including boundary values. For example, "0.5 to 12" indicates a range of "0.5 or more and 12 or less".

[0093] In this embodiment, "nonlinear optical device" refers to a product that includes at least a semiconductor substrate and a nonlinear optical polymer. For example, a nonlinear optical device can be composed of a semiconductor substrate and a nonlinear optical polymer. As long as it includes a semiconductor substrate and a nonlinear optical polymer, the nonlinear optical device can be any device. Examples of nonlinear optical devices include optical modulators, optical switches, optical transceivers, optical phased arrays, LiDAR (Light Detection and Ranging), terahertz wave generators, terahertz wave detectors, semiconductor substrates with polymer films, etc.

[0094] In this embodiment, a nonlinear optical device with an embedded portion is provided. The nonlinear optical device can have any structure as long as it has an embedded portion. For example, the nonlinear optical device can have a slit waveguide structure, a photonic crystal structure, a metamaterial structure, a plasma waveguide structure, etc. Furthermore, as examples only, the slit waveguide structure and the photonic crystal structure will be described later.

[0095] The "nonlinear optical polymer" in this embodiment is a polymer material exhibiting nonlinear optical effects. Nonlinear optical effects can be, for example, electro-optic effects, or the generation of higher harmonics of light, optical Kerr effects, etc. That is, the "nonlinear optical polymer" in this embodiment includes an "electro-optic polymer." The "nonlinear optical device" in this embodiment includes an "electro-optic device."

[0096] In this embodiment, dimensions smaller than 1 μm (e.g., the width of a recess) are measured using electron microscope images. For each object being measured, electron microscope images are taken at three or more different locations. In each electron microscope image, the dimensions are measured at three or more locations. That is, the dimensions are measured at nine or more locations. The arithmetic mean of the nine or more locations is considered the dimension of the object being measured. The electron microscope is arbitrarily selected according to the object being measured. The electron microscope can be, for example, a transmission electron microscope (TEM) or a scanning electron microscope (SEM).

[0097] <Manufacturing Methods of Nonlinear Optical Devices>

[0098] Figure 1This is a schematic flowchart of the manufacturing method of the nonlinear optical device according to this embodiment. The manufacturing method of the NLO device according to this embodiment includes "(a) forming a recess", "(b) filling a first liquid material", "(c) adding a second liquid material" and "(d) hardening". The manufacturing method of the NLO device according to this embodiment may further include "(e) state transition", etc.

[0099] "(a) Formation of concave portion"

[0100] Figure 2 This is a first schematic cross-sectional view illustrating the manufacturing process of the nonlinear optical device according to this embodiment. The manufacturing method of the NLO device according to this embodiment includes a step of forming a recess 10 on the surface 101 of a semiconductor substrate 100.

[0101] (Semiconductor substrate)

[0102] The semiconductor substrate 100 can have any shape. The planar shape of the semiconductor substrate 100 can be, for example, circular or rectangular. The semiconductor substrate 100 can have a diameter, for example, from 25 mm to 300 mm. When the planar shape of the semiconductor substrate 100 is circular, the diameter of the semiconductor substrate 100 represents the diameter of the circle. When the planar shape of the semiconductor substrate 100 is not circular, the diameter of the semiconductor substrate 100 represents the distance between the two farthest points on the outline of the semiconductor substrate 100.

[0103] The semiconductor substrate 100 may contain any semiconductor material. For example, the semiconductor substrate 100 may contain materials such as silicon (Si), silicon carbide (SiC), indium phosphide (InP), gallium arsenide (GaAs), gallium nitride (GaN), diamond, silicon nitride (Si3N4), titanium oxide (TiO2), tantalum oxynitride (TaON), tantalum pentoxide (Ta2O5), niobium oxynitride (NbON), niobium pentoxide (Nb2O5), and I2O (In2O3). x (ZnO) 1-x 〕、IGZO〔(In2O3) x (ZnO) y (Ga2O3) z , x+y+z=1〕, AZO〔(Al2O3) x (ZnO) 1-x and TTON (TiO2) x (TaON) 1-x At least one of the groups consisting of 〕 etc. is selected. In addition, in the above examples, the stoichiometric composition is described in a representative manner, but it is not limited to materials strictly expressed in stoichiometric composition. Semiconductor materials represented by stoichiometric composition are shown.

[0104] Semiconductor substrate 100 may, for example, have a single-layer structure. For example, semiconductor substrate 100 may consist solely of silicon substrate 110. Semiconductor substrate 100 may, for example, have a multi-layer structure. Semiconductor substrate 100 may, for example, be an SOI (Silicon On Insulator) substrate. That is, semiconductor substrate 100 may, for example, include silicon substrate 110, BOX (Buried Oxide) layer 120, and silicon active layer 130. Silicon active layer 130 is a single-crystal silicon layer. Silicon active layer may, for example, be doped with impurities. BOX layer 120 may be sandwiched between silicon substrate 110 and silicon active layer 130. BOX layer 120 contains silicon dioxide (SiO2). An optical waveguide is formed on BOX layer 120, thereby, for example, a strong light confinement effect is desired.

[0105] Each layer of the SOI substrate can have any thickness. For example, the box layer 120 can have a thickness of 0.1 μm to 50 μm. The box layer 120 can have a thickness of 1 μm to 10 μm. The silicon active layer 130 can have a thickness of 0.1 μm to 500 μm. The silicon active layer 130 can have a thickness of 0.1 μm to 1 μm. The silicon active layer 130 can have a thickness of 0.1 μm to 0.5 μm (100 nm to 500 nm). The silicon substrate 110 can have a thickness of 100 μm to 1 mm.

[0106] (concave)

[0107] The recess 10 can be formed by any method. For example, the recess 10 can be formed by patterning using photolithography and reactive ion etching (RIE). For example, the area around the recess 10 can be removed such that the opening of the recess 10 is higher than the surrounding area.

[0108] The "recess 10" in this embodiment includes a sidewall 11 and a bottom 12. The sidewall 11 intersects the surface 101 of the semiconductor substrate 100. The sidewall 11 may be planar or curved. For example, the sidewall 11 may be substantially perpendicular to the surface 101 of the semiconductor substrate 100. For example, the sidewall 11 may also be inclined from the surface 101 of the semiconductor substrate 100.

[0109] exist Figure 2 In the cross-section, the bottom 12 connects a pair of opposing sidewalls 11. The bottom 12 can be, for example, a plane or a curved surface. Figure 2 The cross-sectional shape of the recess 10 may include, for example, a point. The bottom 12 may be parallel to the surface 101 of the semiconductor substrate 100. Alternatively, the bottom 12 may not be parallel to the surface 101 of the semiconductor substrate 100. The cross-sectional shape of the recess 10 may be, for example, rectangular, U-shaped, V-shaped, etc. For example, as... Figure 17As shown, the width of the bottom 12 can be greater than the width of the opening.

[0110] When the semiconductor substrate 100 is an SOI substrate, the bottom layer 12 may, for example, be located within the silicon active layer 130. The bottom layer 12 may, for example, be located within the BOX layer 120. The bottom layer 12 may, for example, be located within the silicon substrate 110.

[0111] When the planar shape of the recess 10 is circular, the "width (w)" of the recess 10 indicates the diameter of the circle. When the planar shape of the recess 10 is not circular, the "width (w)" of the recess 10 indicates the minor axis of the planar shape of the recess 10. In this embodiment, the "minor axis" is defined as follows: On the outline of the planar shape of the recess 10, the straight line connecting the two furthest points is the major axis. The largest diameter among the diameters orthogonal to the major axis is the minor axis. Furthermore, when the planar shape of the recess 10 extends linearly, the major axis is sometimes uncertain. In this case, in the top view of the recess (… Figure 3 The width of the recess 10 is considered to be the width (w) of the recess 10 in the direction orthogonal to the direction in which the recess 10 extends.

[0112] The recess 10 can have any width (w). For example, the recess 10 can have a width (w) of 170 nm or less. In the manufacturing method of the NLO device of this embodiment, even a narrow recess 10 with a width (w) of 170 nm or less is expected to reduce the void space. For example, the recess 10 can have a width (w) of 150 nm or less. For example, the recess 10 can have a width (w) of 100 nm or less. The lower limit of the width (w) is arbitrary. For example, the recess 10 can have a width (w) of 10 nm or more. For example, the recess 10 can have a width (w) of 50 nm or more. For example, the recess 10 can have a width (w) of 80 nm or more.

[0113] The “depth (d)” of the recess 10 refers to the cross-section perpendicular to the surface 101 of the semiconductor substrate 100 (e.g., Figure 2 The depth (d) is the shortest distance between the deepest part of the recess 10 and the opening of the recess 10. The recess 10 can have any depth (d). For example, the recess 10 can have a depth (d) of 50 nm or more. For example, the recess 10 can have a depth (d) of 100 nm or more. For example, the recess 10 can have a depth (d) of 200 nm or more. The upper limit of the depth (d) is arbitrary. For example, the recess 10 can have a depth (d) of less than 3 μm. For example, the recess 10 can have a depth (d) of less than 2 μm. For example, the recess 10 can have a depth (d) of less than 1 μm. For example, the recess 10 can have a depth (d) of less than 300 nm.

[0114] The recess 10 can have any aspect ratio (d / w). For example, the recess 10 can have an aspect ratio (d / w) of 0.5 to 12. An aspect ratio (d / w) of 0.5 or higher is desirable, for example, for high integration. The recess 10 can have an aspect ratio (d / w) of 1 or higher. The recess 10 can have an aspect ratio (d / w) of 1.5 or higher. An aspect ratio (d / w) of 12 or lower is desirable, for example, for reducing voids. The recess 10 can have an aspect ratio (d / w) of 8 or lower. The recess 10 can have an aspect ratio (d / w) of 4 or lower. The recess 10 can have an aspect ratio (d / w) of 0.5 to 4.

[0115] The recess 10 can have any planar shape. For example, the planar shape of the recess 10 can be a circle or a polygon. For example, a polygon can be a triangle, a quadrilateral, a pentagon, a hexagon, etc.

[0116] Figure 3 This is a schematic top view showing the first example of a recess. The recess 10 can be formed, for example, as a linear extension. The linearly extending recess is filled with NLO polymer, thereby, for example, forming a slit waveguide structure. Figure 3 The arrows in the diagram indicate the direction of light transmission. The recess 10 may extend in a straight line, for example. The recess 10 may extend in a curved line, for example. The recess 10 may extend in a zigzag line, for example. The recess 10 may branch into multiple parts, for example. For example, multiple recesses 10 may merge into one.

[0117] Figure 4 This is a schematic top view showing a second example of a recess. The recess 10 can, for example, form a photonic crystal structure. In a photonic crystal structure, the planar shape of the recess 10 can be, for example, circular. For example, on the surface 101 of the semiconductor substrate 100, a plurality of recesses 10 are arranged in a triangular lattice pattern. For example, an amount of recesses 10 corresponding to a column can be filled with NLO polymer. The amount of NLO polymer filled to a column can form a photonic crystal waveguide. Figure 4 The arrows indicate the direction of light transmission. Furthermore, a photonic crystal structure can be assembled around the linearly extending slit structure. In this case, a portion of the plurality of recesses 10 extend linearly along the surface of the semiconductor substrate 100. That is, at least a portion of the recesses 10 can extend linearly along the surface of the semiconductor substrate 100.

[0118] Figure 5 This is a second schematic cross-sectional view illustrating the manufacturing process of the nonlinear optical device according to this embodiment. In this embodiment, in addition to forming the recess 10, impurity doping and electrode formation can also be performed.

[0119] For example, a first doped region 131 and a second doped region 132 can be formed in the silicon active layer 130. Each doped region can be formed by any method. For example, ion implantation can be performed. The first doped region 131 and the second doped region 132 can each have an n-type conductivity. The first doped region 131 and the second doped region 132 can each be doped with impurities such as phosphorus (P).

[0120] The first doped region 131 includes the sidewall 11 of the recess 10. The first doped region 131 can have a relatively low doping concentration. The low doping concentration of the first doped region 131 allows for the expectation, for example, that reduced transport loss.

[0121] The second doped region 132 is in contact with the electrode 200. The second doped region 132 can have a relatively high doping concentration. With a high doping concentration, a decrease in contact resistance with the electrode 200 is expected, for example.

[0122] The doping concentration of the first doped region 131 can, for example, be lower than the doping concentration of the second doped region 132. The doping concentration of the first doped region 131 can, for example, be 1 × 10⁻⁶. 16 cm -3 Up to 1×10 17 cm -3 The doping concentration of the second doped region 132 can be, for example, 1 × 10⁻⁶. 17 cm -3 Up to 1×10 18 cm -3 .

[0123] In this embodiment, impurity doping can be performed at any timing. For example, impurity doping can be performed before the formation of the recess 10. For example, impurity doping can also be performed after the formation of the recess 10.

[0124] Electrode 200 may, for example, comprise at least one material selected from the group consisting of aluminum (Al), tungsten (W), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), chromium (Cr), molybdenum (Mo), tantalum (Ta), niobium (Nb), nickel (Ni), cobalt (Co), gold (Au), silver (Ag), copper (Cu), and platinum (Pt). Electrode 200 may be formed by any method. For example, electrode 200 may be formed by vapor deposition or the like. Electrode 200 may, for example, be a signal electrode. Electrode 200 may, for example, be a ground electrode.

[0125] In this embodiment, the electrode 200 can be formed at any timing. For example, the electrode 200 can be formed before the polymer solution is applied. For example, the electrode 200 can also be formed after the polymer film 300 is formed.

[0126] (b) Filling of the first liquid material

[0127] Figure 6 This is a third schematic cross-sectional view illustrating the manufacturing process of the nonlinear optical device according to this embodiment. The manufacturing method of the NLO device according to this embodiment includes a step of filling the recess 10 with a first liquid material 31 under reduced pressure.

[0128] The first liquid material 31 is filled into the recess 10 by any method. For example, the first liquid material 31 can be applied to the surface 101 of the semiconductor substrate 100 by spin coating or the like. For example, a spin coater or the like that capable of controlling the atmosphere pressure can be used.

[0129] In this embodiment, "reduced pressure atmosphere" refers to an atmosphere with a pressure less than atmospheric pressure. It is conceivable that degassing would be promoted under a reduced pressure atmosphere. The first liquid material 31 is a low-concentration solution or the solvent itself. It is conceivable that material hardening is difficult to occur on the surface of the first liquid material 31. The reduced pressure atmosphere may, for example, have a pressure of 0.1 Pa to 90 kPa. The reduced pressure atmosphere may, for example, have a pressure of 100 Pa to 80 kPa. The reduced pressure atmosphere may, for example, have a pressure of 3 kPa to 70 kPa.

[0130] The first liquid material 31 comprises a first solute and a first solvent, or the first liquid material 31 consists only of the first solvent. The first solute is soluble in the first solvent. The concentration of the first solute in the first liquid material 31 can, for example, be from 0% by mass to 35% by mass. The concentration of the first solute in the first liquid material 31 can, for example, be from 0% by mass to 20% by mass. The concentration of the first solute in the first liquid material 31 can, for example, be from 0% by mass to 10% by mass.

[0131] The first liquid material 31 may have a low viscosity. For example, the first liquid material may have a viscosity of 1 mPa·s to 2000 mPa·s. For example, the first liquid material may have a viscosity of 1 mPa·s to 1000 mPa·s. For example, the first liquid material may have a viscosity of 1 mPa·s to 10 mPa·s. The "viscosity" of the liquid in this embodiment can be measured using a micro-sample viscometer (product name "microVISC") manufactured by RheoSense. A product equivalent to this viscometer may also be used. The measurement temperature is 25°C ± 1°C. For each test object, the viscosity is measured at least three times. The arithmetic mean of the results from the three or more measurements is considered the viscosity of the test object.

[0132] (solvent)

[0133] The first solvent may contain any component. For example, the first solvent may contain at least one component selected from the group consisting of acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, cycloheptanone, acetylacetone, methylpentyl ketone, n-methyl ketone, γ-butyrolactone, tetrahydrofuran, chloroform, dibromomethane, 1,2-dichloroethane, 1,2-dibromoethane, 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane, 1,1,2-tribromoethane, 1,1,2,2-tetrabromoethane, ethyl acetate, butyl acetate, methyl lactate, ethyl lactate, butyl lactate, propylene glycol methyl ether, propylene glycol monomethyl ether acetate, and ethyl cellosolve acetate.

[0134] (Solute)

[0135] The first solute can contain any components. The first solute can consist of essentially only one component or multiple components. For example, the first solute can contain low-molecular-weight compounds, oligomers, polymers, etc.

[0136] The first solute may include, for example, a surfactant. The surfactant may act as an evaporation inhibitor of the solvent. As an evaporation inhibitor, the evaporation of the solvent is reduced, for example, on the surfaces of the first liquid material 31 and the third liquid material 33 (described later). As a result, for example, a reduction in the surface roughness of the polymer film 300 (described later) is expected. The surfactant may include, for example, fluorinated surfactants (e.g., the product name "megaface" manufactured by DIC).

[0137] The first solute may, for example, contain NLO pigment molecules. NLO pigment molecules refer to molecules exhibiting NLO activity. NLO pigment molecules may, for example, contain electro-optic (EO) pigment molecules, as described later. Since the first solute contains NLO pigment molecules, it is desirable, for example, during a transposition process, that the orientation of the NLO pigment molecules be improved.

[0138] The first solute may, for example, contain an NLO polymer. The first solute may consist substantially only of an NLO polymer. An NLO polymer is a polymer material exhibiting nonlinear optical effects. An NLO polymer may, for example, contain an EO polymer, etc. An NLO polymer may, for example, consist substantially only of an EO polymer.

[0139] (EO polymer)

[0140] EO polymers exhibit an electro-optic effect. EO polymers can contain any components as long as they exhibit this effect. For example, EO polymers can contain guest / host polymers. The guest / host polymer contains guest molecules and a host polymer. The guest molecules are dispersed within the host polymer. The concentration of guest molecules in the guest / host polymer can, for example, be from 10% to 50% by mass. The host polymer can, for example, contain polymethyl methacrylate (PMMA), polycarbonate (PC), etc.

[0141] The guest molecule exhibits an electro-optic effect. The guest molecule is also referred to as an "EO pigment molecule". The guest molecule can be, for example, an electron-donating group (donor), a linking group, and an electron-withdrawing group (acceptor). The linking group is connected to the donor and acceptor. The linking group can, for example, contain π-conjugated structures, etc. The linking group can, for example, contain structures derived from the following formulas (II) to (IV):

[0142] [Chemistry 2]

[0143]

[0144] The structure represented.

[0145] A donor may, for example, be included by the following formula (V):

[0146] [Chemistry 3]

[0147]

[0148] The structure represented.

[0149] In the above equation (V), R 3 and R 4 Each can independently represent a hydrogen atom, alkyl group, hydroxyalkyl group, haloalkyl group, aryl group, etc.

[0150] The recipient can be represented, for example, by the following formula (I):

[0151] [Chemistry 4]

[0152]

[0153] That is, NLO polymers can contain structures represented by the above formula (I).

[0154] In the above formula (I), R 1 and R 2 Each can independently represent a hydrogen atom, alkyl, alkenyl, cycloalkyl, cycloalkenyl, alkoxy, haloalkyl, aryl, hydroxyl, thiol, or amino group.

[0155] EO polymers containing acceptors of formula (I) above can exhibit large electro-optic effects. Alkyl groups can be, for example, methyl groups. Halogenated alkyl groups can be, for example, trifluoromethyl groups. In R... 1 R 2 When the aryl group is aryl, it can be substituted. Examples of aryl groups include phenyl and naphthyl groups. The hydrogen atoms in the aryl group can be substituted, for example, with halogen atoms, alkyl groups, or haloalkyl groups.

[0156] In the above equation (I), for example R 1 and R 2 Each can independently represent a hydrogen atom, methyl, trifluoromethyl, or phenyl.

[0157] For example, EO pigment molecules can be combined with linear copolymers as side chains to form EO polymers. EO pigment molecules can be combined with the linear copolymer (main chain) through reactions of reactive groups (e.g., hydroxyl groups) contained in the donor. The linear copolymer can be a homopolymer or a copolymer. The copolymer can be, for example, any of a random copolymer, alternating copolymer, block copolymer, or graft copolymer. In this embodiment, the EO polymer in which EO pigment molecules are combined with linear copolymers as side chains is also referred to as a "side-chain copolymer".

[0158] Figure 18 This is an example of a side-chain copolymer. First, a linear copolymer is synthesized by copolymerizing dicyclopentyl methacrylate (DCPMA) and 2-methacryloyloxyethyl isocyanate (MOI). The EO pigment molecule has one hydroxyl group. The EO pigment molecule is introduced as a side chain of the linear copolymer.

[0159] For example, multiple polymer chains can be cross-linked by EO pigment molecules. For example, when an EO pigment molecule has two reactive groups, it can cross-link two polymer chains. In this embodiment, the EO polymer cross-linked by EO pigment molecules is also referred to as a "cross-linked copolymer".

[0160] It is conceivable that in guest / host polymers, if the guest molecules are at a high concentration, the guest molecules (EO pigment molecules) are prone to aggregation. Conversely, in side-chain copolymers and cross-linked copolymers, EO pigment molecules are less likely to aggregate, thus making it easier to increase the concentration of EO pigment molecules.

[0161] (c) Additional Liquid Material (Section 2)

[0162] Figure 7 This is a fourth schematic cross-sectional view showing the manufacturing process of the nonlinear optical device according to this embodiment. Figure 8This is a fifth schematic cross-sectional view showing the manufacturing process of the nonlinear optical device according to this embodiment. The manufacturing method of the NLO device according to this embodiment includes a step of contacting a second liquid material 32 with a first liquid material 31 that fills the recess 10, thereby modulating a third liquid material 33.

[0163] The second liquid material 32 comes into contact with the first liquid material 31 by any method. For example, the second liquid material 32 can be dripped onto the surface of the first liquid material 31. For example, the second liquid material 32 can be applied to the surface of the first liquid material 31. For example, the second liquid material 32 can be blown onto the surface of the first liquid material 31.

[0164] The second liquid material 32 comprises a second solute and a second solvent. The second solute is dissolved in the second solvent. The second solute comprises an NLO polymer. The second solute may, for example, consist substantially only of an NLO polymer. The second solute may also contain other components in addition to the NLO polymer. The second solute may also contain, for example, the aforementioned surfactants.

[0165] For example, when the first solute does not contain an NLO polymer, the second solute and the first solute are different materials. For example, when the first solute contains an NLO polymer, the second solute and the first solute can be different materials or the same material.

[0166] The second solvent may, for example, contain the material described as the first solvent. The second solvent may, for example, be a material different from the first solvent. The second solvent may, for example, be the same material as the first solvent. The second solute is the same material as the first solute, and the second solvent is the same material as the first solvent, thereby, for example, it is expected that the second liquid material 32 and the first liquid material 31 will be uniformly mixed.

[0167] The second liquid material 32 is a high-concentration solution. The concentration of the second solute in the second liquid material 32 is higher than the concentration of the first solute in the first liquid material 31. The concentration of the second liquid material 32 can be, for example, from 5% to 40% by mass. The concentration of the second liquid material 32 can be, for example, from 10% to 30% by mass. The concentration of the second liquid material 32 can be, for example, from 10% to 20% by mass.

[0168] The difference between the concentration of the second liquid material 32 and the concentration of the first liquid material 31 may, for example, exceed 0% by mass and be less than 40% by mass. The difference between the concentration of the second liquid material 32 and the concentration of the first liquid material 31 may, for example, be from 5% by mass to 40% by mass. The difference between the concentration of the second liquid material 32 and the concentration of the first liquid material 31 may, for example, be from 10% by mass to 20% by mass.

[0169] The second liquid material 32 may have a higher viscosity than the first liquid material 31. For example, the second liquid material 32 may have a viscosity of 2 mPa·s to 2500 mPa·s. For example, the second liquid material 32 may have a viscosity of 5 mPa·s to 2500 mPa·s. For example, the second liquid material 32 may have a viscosity of 10 mPa·s to 2500 mPa·s. For example, the second liquid material 32 may have a viscosity of 100 mPa·s to 2500 mPa·s. For example, the second liquid material 32 may have a viscosity of 1000 mPa·s to 2500 mPa·s.

[0170] The solute diffuses from the second liquid material 32 to the first liquid material 31, thereby modulating the third liquid material 33. To promote solute diffusion, the liquid materials can be heated. However, the heating temperature is adjusted to prevent solute aggregation. For example, the solute can diffuse at temperatures ranging from 20°C to 80°C. For example, the solute can diffuse at temperatures ranging from 30°C to 60°C.

[0171] Solute diffusion can be carried out, for example, under normal pressure or under pressure.

[0172] The third liquid material can be formulated to have a substantially uniform concentration. The concentration of the solute in the third liquid material 33 can, for example, be from 5% to 40% by mass. The concentration of the solute in the third liquid material 33 can, for example, be from 5% to 20% by mass. The concentration of the solute in the third liquid material 33 can, for example, be from 5% to 10% by mass.

[0173] (d) Hardening

[0174] Figure 9 This is a sixth schematic cross-sectional view illustrating the manufacturing process of the nonlinear optical device according to this embodiment. The manufacturing method of the NLO device according to this embodiment includes a step of forming an embedded portion 310 by hardening a third liquid material 33. By forming the embedded portion 310, the NLO device 1000 is completed.

[0175] The third liquid material 33 hardens, thereby forming a polymer film 300. The first solvent and the second solvent can be removed from the third liquid material 33 by any method. For example, at least one method selected from the group consisting of natural drying, vacuum drying, rotary drying, hot air drying, and infrared drying can be implemented.

[0176] The polymer film 300 includes an embedded portion 310. The embedded portion 310 is embedded into the recess 10. Part or all of the embedded portion 310 may, for example, form an optical waveguide. The embedded portion 310 of this embodiment may have a low porosity. Therefore, low transmission loss of the optical waveguide is expected.

[0177] The polymer film 300 (embedded portion 310) of this embodiment may have a smooth surface. The polymer film 300 may, for example, have a small surface roughness. The polymer film 300 may, for example, have a specified surface smoothness. The smooth surface of the polymer film 300 provides an NLO device that can be miniaturized.

[0178] (e) Transition

[0179] The manufacturing method of the NLO device in this embodiment may, for example, include a step of performing a transformation process on the embedded portion 310.

[0180] For example, if the embedded portion 310 contains an EO polymer, the embedded portion 310 is heated to the glass transition temperature (T0) of the EO polymer. g Near the electrode 200, while maintaining heating, a predetermined voltage is applied between the electrodes 200. This places the embedded part 310 in an electric field. The EO pigment molecules align along the direction of the electric field. While the voltage is applied, the EO polymer cools to room temperature. Thus, the EO pigment molecules can be fixed in their oriented state.

[0181] Example

[0182] Hereinafter, embodiments of the present invention (hereinafter also referred to as "this embodiment") will be described. However, the following description does not limit the scope of the claims.

[0183] <Fabrication of Nonlinear Optical Devices>

[0184] Evaluation devices (NLO devices) are manufactured using the manufacturing methods described in No. 1 to No. 3 below. The evaluation device in this embodiment is a slit waveguide type optical modulator.

[0185] <No.1>

[0186] "(a) Formation of concave portion"

[0187] An SOI substrate is prepared as the semiconductor substrate 100. A recess 10 is formed by patterning and RIE achieved using photolithography. In this embodiment, the recess 10 is a linearly extending slit. The width (w) of the recess 10 is 134 nm. The depth (d) of the recess 10 is 302 nm. The bottom 12 of the recess 10 is located within the BOX layer 120.

[0188] (b) Filling of the first liquid material

[0189] In this embodiment, the first liquid material 31 is composed solely of a first solvent. The first solvent is cyclohexanone. The concentration of the first solute in the first liquid material 31 is 0% by mass.

[0190] A first liquid material 31 is dropped onto the surface of the semiconductor substrate 100. After dropping, the first liquid material 31 is allowed to stand under reduced pressure for 10 minutes, thereby allowing the first liquid material 31 to fully degas. The first liquid material 31 is then filled into the recess 10. After filling, the semiconductor substrate 100 is rotated at 500 rpm for 3 seconds using a spin coater. This removes excess first liquid material 31.

[0191] (c) Additional Liquid Material (Section 2)

[0192] An EO polymer is prepared as the second solute. The EO polymer is a cross-linked copolymer. Cyclohexanone is prepared as the second solvent. The second solute is dissolved in the second solvent, thereby preparing the second liquid material 32. The concentration of the second solvent in the second liquid material 32 is 16% by mass. The concentration of the second solute in the second liquid material 32 (16% by mass) is higher than the concentration of the first solute in the first liquid material 31 (0% by mass).

[0193] The second liquid material 32 is dripped onto the first liquid material 31. That is, the second liquid material 32 comes into contact with the first liquid material 31. At room temperature, the second solute (EO polymer) diffuses, thereby modulating the third liquid material 33. The third liquid material 33 is modulated to have a substantially uniform concentration.

[0194] (d) Hardening

[0195] After the second liquid material 32 is dropped, the semiconductor substrate 100 is rotated at 1500 rpm for 60 seconds using a spin coater. As a result, the third liquid material 33 spreads substantially uniformly on the surface of the semiconductor substrate 100, and the first and second solvents evaporate. Consequently, the second solute precipitates within the recess 10. That is, the third liquid material 33 hardens. This forms a polymer film 300. The portion of the polymer film 300 that extends into the recess 10 forms an embedded portion 310. The polymer film 300 is further heated to the glass transition temperature (T0) of the EO polymer. g The remaining first and second solvents are removed by heat treatment for 1 hour under reduced pressure near the area.

[0196] (e) Transition

[0197] The embedded part 310 is heated to the glass transition temperature (T) of the EO polymer. g The embedded part 310 is placed in an electric field while heated. Then, while maintaining the electric field, the embedded part 310 is cooled down. Thus, an evaluation device is manufactured.

[0198] <No.2>

[0199] Figure 10This is a first schematic cross-sectional view showing the manufacturing process of No.2. Similar to No.1, a semiconductor substrate 100 having a recess 10 is prepared. A polymer solution 35 is prepared. The solvent for polymer solution 35 is cyclohexanone. The solute is the same EO polymer as in No.1. The concentration of polymer solution 35 is 16% by mass.

[0200] A polymer solution 35 is applied to the surface of a semiconductor substrate 100 using a spin coater under normal pressure. This fills the recess 10 with the polymer solution 35. Given the normal pressure atmosphere, it is conceivable that air bubbles 1 are unlikely to escape from the recess 10.

[0201] Figure 11 This is a second schematic cross-sectional view showing the manufacturing process of No.2. The polymer solution 35 is hardened, thereby forming a polymer film 300. It is conceivable that voids 2 remain in the embedded portion 310. After the polymer film 300 is formed, a transformation process is performed in the same manner as for No.1.

[0202] <No.3>

[0203] Figure 12 This is a schematic cross-sectional view showing the manufacturing process of No. 3. The polymer solution 35 is applied and filled under reduced pressure. It is conceivable that degassing under reduced pressure reduces the number of bubbles 1 compared to No. 2. However, it is conceivable that due to surface hardening of the polymer solution 35, unevenness will form on the surface of the polymer film 300. After forming the polymer film 300, a transformation process is performed in the same manner as for No. 1.

[0204] <Evaluation>

[0205] A first near-infrared camera is disposed above the semiconductor substrate 100. The first near-infrared camera captures an image of light transmission stripes formed by the scattering of light transmitted in the embedded portion 310.

[0206] pass Figures 13 to 15 The measurement example of transmission loss is explained. Figure 13 This is a schematic top view of the evaluation device. The evaluation device 2000 is symmetrical from left to right. The evaluation device 2000 is constructed by sequentially connecting the first polymer waveguide 2001, the first spot size transformer 2002, the first silicon strip waveguide 2003, the second spot size transformer 2004, the silicon slit waveguide 2005, the third spot size transformer 2006, the second silicon strip waveguide 2007, the fourth spot size transformer 2008, and the second polymer waveguide 2009. The length of the silicon slit waveguide 2005 is 1736 μm.

[0207] exist Figure 14 The image shows the light transmission stripe pattern for No. 2. Figure 14 The light transmission stripe image is in Figure 13The image was taken in 2005 of a silicon slot waveguide. Figure 15 As shown, the scattered light intensity (relative value) of the optical transmission fringe pattern is plotted for a position (Z) within the silicon slit waveguide 2005. The plotted group is approximated as an exponential function using the least squares method, thereby determining the transmission loss.

[0208] A second near-infrared camera is disposed on the end face of the semiconductor substrate 100. The near-field image of the light output is captured by the second near-infrared camera. The light output (relative value) is calculated based on the value of the light attenuator that becomes equivalent to the light output near-field image.

[0209] The fracture of device 2000 was evaluated by traversing the silicon slot waveguide 2005. The fracture surface was observed using SEM to confirm the presence or absence of voids within the embedded portion 310. The presence or absence of voids was confirmed at each of the fracture surfaces at more than 5 locations. The porosity was calculated using the following formula.

[0210] Porosity (%) = {(Number of fracture surfaces with voids) / (Number of observed fracture surfaces)} × 100

[0211] <Results>

[0212] Figure 16 These are the evaluation results from No.1 to No.3.

[0213] The voids were confirmed using cross-sectional SEM images. The voids are the portions of the bottom 12 of the recess 10 that were not filled with polymer.

[0214] In the cross-sectional SEM image of No.2, voids were confirmed in most cases. The porosity of No.2 was 71%. It is conceivable that many voids remain in the embedded part 310. The transmission loss is the greatest and the optical output is the lowest.

[0215] In the cross-sectional SEM image of No.3, the porosity is reduced compared to No.2. The porosity of No.3 is 9%. It is conceivable that the porosity is reduced by depressurization and degassing. However, it is conceivable that even if the porosity is reduced, the porosity can still be identified, so a small amount of porosity remains. Compared to No.2, No.3 has reduced transmission loss and increased light output. In addition, in No.3, unevenness is formed on the surface of the polymer film 300 (embedded part 310) by surface hardening of the polymer solution 35.

[0216] No voids were detected in the cross-sectional SEM image of No. 1. The porosity of No. 1 is 0%. The transmission loss of No. 1 is lower than that of No. 2 and No. 3. The light output of No. 1 is higher than that of No. 2 and No. 3. It is conceivable that the voids are significantly reduced because the first liquid material 31 easily penetrates into the recess 10. It is conceivable that in No. 1, voids are essentially completely eliminated. The surface of the polymer film 300 of No. 1 can be smooth. It is conceivable that this is because surface hardening is difficult to occur in the first liquid material 31.

[0217] <Postscript>

[0218] In this invention, NLO devices as described in Appendix 1 to Appendix 3 below may also be provided.

[0219] Appendix 1

[0220] A nonlinear optical device comprising:

[0221] Semiconductor substrates; and

[0222] polymer film,

[0223] A recess is formed on the surface of the semiconductor substrate.

[0224] The recess extends along the surface of the semiconductor substrate.

[0225] The polymer film covers at least a portion of the surface of the semiconductor substrate.

[0226] The polymer film includes an embedded portion.

[0227] The embedded part is embedded into the recess.

[0228] The embedded part contains a nonlinear optical polymer.

[0229] The transmission loss of the embedded part is below a specified value.

[0230] Appendix 2

[0231] The nonlinear optical devices described in Appendix 1

[0232] The porosity of the embedded part is below a specified value.

[0233] Appendix 3

[0234] The nonlinear optical devices described in Appendix 1 or Appendix 2,

[0235] The surface roughness of the polymer film is below a specified value.

[0236] This embodiment and this example are illustrative in all respects. This embodiment and this example are not limiting. For example, it was originally intended that arbitrary structures be extracted from this embodiment and this example and combined arbitrarily.

[0237] The technical scope defined based on the claims includes all modifications equivalent to the meaning of the claims. Furthermore, the technical scope defined based on the claims also includes all modifications within the scope equivalent to the claims.

[0238] Explanation of the label

[0239] 1. Bubble, 2. Void, 10. Recess, 11. Sidewall, 12. Bottom, 31. First liquid material, 32. Second liquid material, 33. Third liquid material, 35. Polymer solution, 100. Semiconductor substrate, 101. Surface, 110. Silicon substrate, 120. BOX layer, 130. Silicon active layer, 131. First doped region, 132. Second doped region, 200. Electrode, 300. Polymer film, 310. Embedded part, 1000. Nonlinear optical device, 2000. Evaluation device, 2001. First polymer waveguide, 2002. First spot size converter, 2003. First silicon strip waveguide, 2004. Second spot size converter, 2005. Silicon slit waveguide, 2006. Third spot size converter, 2007. Second silicon strip waveguide, 2008. Fourth spot size converter, 2009. Second polymer waveguide.

Claims

1. A method for manufacturing a nonlinear optical device, comprising the following steps: A recess is formed on the surface of a semiconductor substrate; Under a depressurized environment, a first liquid material is filled into the recess. The depressurized environment is used to inhibit the first liquid material from hardening from the surface while allowing the first liquid material to fill the recess and expel the air inside the recess. The second liquid material is brought into contact with the first liquid material filling the recess without pre-mixing, and the solute in the second liquid material diffuses into the first liquid material, thereby modulating the third liquid material within the recess; and The third liquid material is hardened to form the embedded part. The first liquid material comprises a first solute and a first solvent, or consists only of the first solvent. The second liquid material comprises a second solute and a second solvent. The second solute comprises a nonlinear optical polymer. The concentration of the second solute in the second liquid material is higher than the concentration of the first solute in the first liquid material.

2. The method for manufacturing a nonlinear optical device according to claim 1, wherein, The first solute comprises a nonlinear optical polymer.

3. The method for manufacturing a nonlinear optical device according to claim 1 or 2, wherein, At least a portion of the recess is formed to extend linearly along the surface of the semiconductor substrate.

4. The method for manufacturing a nonlinear optical device according to claim 1 or 2, wherein, The ratio of the depth of the recess to the width of the recess is between 0.5 and 12.

5. The method for manufacturing a nonlinear optical device according to claim 1 or 2, wherein, The recess has a width of less than 170 nm.

6. The method for manufacturing a nonlinear optical device according to claim 1 or 2, wherein, The concentration of the first solute in the first liquid material is from 0% to 35% by mass. The concentration of the second solute in the second liquid material is from 5% to 40% by mass.

7. The method for manufacturing a nonlinear optical device according to claim 1 or 2, wherein, The nonlinear optical polymer comprises, by the following formula (I): [Chemistry 1] The structure represented, In the above equation (I), R 1 and R 2 Each can independently represent a hydrogen atom, alkyl, alkenyl, cycloalkyl, cycloalkenyl, alkoxy, haloalkyl, aryl, hydroxyl, thiol, or amino group.

8. The method for manufacturing a nonlinear optical device according to claim 1 or 2, wherein, The first solvent and the second solvent each comprise at least one solvent selected from the group consisting of acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, cycloheptanone, acetylacetone, methylpentyl ketone, n-methyl ketone, γ-butyrolactone, tetrahydrofuran, chloroform, dibromomethane, 1,2-dichloroethane, 1,2-dibromoethane, 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane, 1,1,2-tribromoethane, 1,1,2,2-tetrabromoethane, ethyl acetate, butyl acetate, methyl lactate, ethyl lactate, butyl lactate, propylene glycol methyl ether, propylene glycol monomethyl ether acetate, and ethyl cellosolve acetate.

9. The method for manufacturing a nonlinear optical device according to claim 1 or 2, wherein, The second solvent is the same material as the first solvent. The second solute is the same material as the first solute.

10. The method for manufacturing a nonlinear optical device according to claim 1, wherein, The first solute comprises a nonlinear optical polymer. At least a portion of the recess is formed to extend linearly along the surface of the semiconductor substrate. Under reduced pressure, the recess is filled with the first liquid material. The ratio of the depth of the recess to the width of the recess is between 0.5 and 12. The recess has a width of less than 170 nm. The concentration of the first solute in the first liquid material is from 0% to 35% by mass. The concentration of the second solute in the second liquid material is from 5% to 40% by mass.

Images