Element transcription method and element transcription device

Abstract

In this element transcription method, an element (10) is transcribed onto a target substrate (2) via a stamp (3) by moving the target substrate and the stamp relative to and toward each other so that the target substrate and the element contact with each other, and by moving the target substrate and the stamp relative to and away from each other while vibrating the stamp and the element using a vibration unit (80).

Description

Element transfer method and element transfer device

[0001] The present disclosure relates to a device transfer method and a device transfer apparatus.

[0002] In recent years, the use of light has been explored in the fields of high-speed communication, large-capacity communication, and sensing. In particular, a technology called "silicon photonics" has attracted attention. This technology involves forming optical circuits on silicon substrates using a complementary metal oxide semiconductor (CMOS) process, similar to semiconductor electronic circuits. Optical circuits formed using silicon photonics are micro-sized circuits with optical control functions, including optical input / output units and optical modulators. These components are connected to each other via submicron-order micro-optical waveguides. Normally, to operate an optical circuit, light from a light source such as an LD must be connected to an optical input unit with high precision via an external transmission medium such as an optical fiber. However, by directly placing an LD chip or an optical element itself on an optical circuit substrate and optically connecting the LD chip or optical element, the optical circuit can be operated in a small space with a small number of components.

[0003] Another device that requires the placement of microchips is a microLED display. Conventionally, when manufacturing a microLED display, a wafer is divided into individual pieces, and multiple microLEDs formed are placed one by one on a circuit board using a pick-and-place process. This manufacturing method requires the pick-and-place process to be repeated tens of thousands of times, which is time-consuming and increases manufacturing costs.

[0004] Patent Document 1 discloses a method for transferring multiple elements to a target substrate in a single pick-and-place process using a temporary holding member such as an adhesive stamp, thereby shortening the process time and reducing manufacturing costs.

[0005] However, if the adhesive strength of such a holding member for holding the element is weak, the held element may fall off the holding member, preventing the element from being transferred to the desired position on the target substrate, resulting in operational malfunction. Therefore, the holding member is required to have strong adhesive strength for holding the element. On the other hand, if the adhesive strength of the holding member for holding the element is too strong, the held element will not be transferred to the target substrate and will remain held by the holding member. This will prevent the element from being transferred to the desired position on the target substrate, resulting in operational malfunction. Furthermore, if the pick-and-place process is carried out with the element remaining on the holding member, the element on the substrate will collide with the element remaining on the holding member, resulting in damage to the element.

[0006] Therefore, Patent Document 1 also discloses a method for facilitating the transfer of elements by plasma treatment of the contact surface of the element with the target substrate, or a method for facilitating the transfer of elements by reducing the adhesive force of the holding member by heat treatment.

[0007] Patent No. 6453437

[0008] The conventional technology disclosed in Patent Document 1 requires expensive equipment to generate plasma, and the optical element may fall off during plasma processing. Furthermore, due to differences in the thermal expansion coefficients of the optical element, the holding member, and the target substrate caused by heat processing, the optical element may not be transferred to the desired position. In other words, relative positional misalignment between the element and the target substrate may occur. Furthermore, the holding member may deteriorate due to the heat processing cycle.

[0009] A non-limiting example of the present disclosure aims to provide an element transfer method and element transfer device that has a simple configuration, reduces adhesive force during element transfer, thereby preventing elements from falling off or remaining on the stamp, and enables highly accurate and reliable element transfer.

[0010] A method for transferring an element according to one aspect of the present disclosure includes aligning the positions of a target substrate and an element picked up by the adhesive force of a stamp; bringing the target substrate and the stamp relatively close to each other to bring the target substrate and the element into contact; and transferring the element from the stamp to the target substrate by moving the target substrate and the stamp relatively apart while applying vibrations to the stamp and the element using a vibration unit.

[0011] an element transfer device according to one aspect of the present disclosure, comprising: a target substrate setting table on which a target substrate is placed; a stamp head having a stamp capable of picking up elements by adhesive force; a frame holding the stamp head so that the stamp can face the target substrate setting table; a substrate position adjustment mechanism capable of adjusting the position of the target substrate with respect to the stamp and of moving the target substrate and the stamp relatively closer to or farther apart; an imaging unit that images the element and the stamp and also images the element and the target substrate, thereby making it possible to detect the amount of misalignment between the element and the stamp and the amount of misalignment between the element and the target substrate; a contact detection unit that detects contact between the element and the target substrate; and a vibration unit that is disposed between the contact detection unit and the frame and applies vibrations to the stamp and the element. (a) controls the substrate position adjustment mechanism so as to reduce the amount of positional misalignment; (b) controls the substrate position adjustment mechanism so as to bring the target substrate and the stamp relatively closer together; (c) detects contact between the target substrate and the element of the stamp using the contact detection unit; (d) controls the vibration unit so as to impart vibration to the stamp and the element; and (e) controls the vibration unit and the substrate position adjustment mechanism so as to transfer the element from the stamp to the target substrate by moving the target substrate and the stamp relatively apart while imparting vibration to the stamp and the element.

[0012] According to the above aspects of the present disclosure, it is possible to provide an element transfer method and element transfer device that do not require plasma treatment or heat treatment, and that have a simple configuration that includes a vibration unit that applies vibration to the element and stamp, thereby reducing the adhesive force during element transfer, thereby achieving highly accurate and reliable element transfer.

[0013] FIG. 1 is a diagram showing a configuration example of an element transfer device according to an embodiment of the present disclosure. FIG. 2 is a diagram showing a stamp head and a vibration unit of an element transfer device according to an embodiment of the present disclosure. FIG. 3 is a flowchart showing an element transfer method according to an embodiment of the present disclosure. FIG. 4 is a diagram for explaining an element transfer method according to an embodiment of the present disclosure. FIG. 5 is a diagram for explaining an element transfer method according to an embodiment of the present disclosure. FIG. 6 is a diagram for explaining an element transfer method according to an embodiment of the present disclosure.

[0014] Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functions are designated by the same reference numerals, and redundant description will be omitted. In the following drawings, the shapes, thicknesses, lengths, etc. of the components shown in each drawing may differ from the actual shapes, thicknesses, lengths, etc. of the components due to the creation of the drawings. Furthermore, the materials of the components are not limited to those described in this embodiment.

[0015] In FIG. 1 and subsequent drawings, the X-axis direction, the Y-axis direction, and the Z-axis direction represent directions parallel to the X-axis, the Y-axis, and the Z-axis, respectively. The X-axis direction and the Y-axis direction are perpendicular to each other. The X-axis direction and the Z-axis direction are perpendicular to each other. The Y-axis direction and the Z-axis direction are perpendicular to each other. The XY plane represents an imaginary plane parallel to the X-axis direction and the Y-axis direction. The XZ plane represents an imaginary plane parallel to the X-axis direction and the Z-axis direction. The YZ plane represents an imaginary plane parallel to the Y-axis direction and the Z-axis direction. Also, in FIG. 1 and subsequent drawings, the direction indicated by the arrow in the X-axis direction is the positive X-axis direction, and the direction opposite to this direction is the negative X-axis direction. Also, in FIG. 1 and subsequent drawings, the direction indicated by the arrow in the Y-axis direction is the positive Y-axis direction, and the direction opposite to this direction is the negative Y-axis direction. Also, in FIG. 1 and subsequent drawings, the direction indicated by the arrow in the Z-axis direction is the positive Z-axis direction, and the direction opposite to this direction is the negative Z-axis direction. The Z-axis direction is, for example, equivalent to the vertical direction or up-down direction, and the X-axis direction and the Y-axis direction are, for example, equivalent to the horizontal direction or left-right direction.

[0016] [Embodiment 1] <Element Transfer Apparatus> First, an element transfer apparatus D1 according to an embodiment of the present disclosure will be described with reference to Figures 1 and 2. Figure 1 is a diagram showing an example of the configuration of the element transfer apparatus D1 according to the embodiment of the present disclosure, and Figure 2 is a diagram showing the stamp head 30 and the vibration unit 80 of the element transfer apparatus D1 according to the embodiment of the present disclosure.

[0017] The element transfer device D1 includes at least a source substrate mounting table 11, a target substrate mounting table 21, a stamp head 30, a frame 40, a substrate position adjustment mechanism 51, an imaging unit 60, an imaging unit adjustment mechanism 61, a contact detection unit 70, a vibration unit 80, and a control unit C1. The element transfer device D1 picks up elements 10 from a source substrate 1 by the adhesive force of a stamp 3, reduces the adhesive force, and then transfers the elements 10 from the stamp 3 to a target substrate 2.

[0018] The source substrate mounting stage 11 is, for example, a rectangular plate-shaped stage on which the source substrate 1 is mounted. The type of the source substrate mounting stage 11 is not limited as long as it is capable of mounting the source substrate 1. The source substrate mounting stage 11 may be provided with suction holes for adsorbing the source substrate 1, for example, and the source substrate 1 may be tightly attached to the source substrate mounting stage 11 by applying negative pressure to the suction holes.

[0019] Here, the source substrate 1 is, for example, a rectangular plate-shaped member, and the elements 10 are formed on its surface. The elements 10 are, for example, optical elements formed on the source substrate 1 by a CMOS process. The elements 10 may be formed by any method that can achieve the desired performance, and the type of method is not important. The source substrate 1 and the elements 10 may have alignment marks formed thereon for the purpose of aligning the stamp 3 and the elements 10 when they are picked up from the source substrate 1 by the stamp 3.

[0020] The target substrate mounting table 21 is, for example, a rectangular plate-shaped table on which the target substrate 2 is mounted. The type of the target substrate mounting table 21 is not limited as long as it is capable of mounting the target substrate 2. The target substrate mounting table 21 may be provided with suction holes for adsorbing the target substrate 2, for example, and the target substrate 2 may be brought into close contact with the target substrate mounting table 21 by applying negative pressure to the suction holes.

[0021] Here, the target substrate 2 is, for example, a rectangular plate-shaped member, and is a substrate onto whose surface the elements 10 formed on the source substrate 1 are transferred. The target substrate 2 may have an electrical circuit or optical circuit (not shown) formed thereon so that desired performance is obtained when the elements 10 are transferred. The target substrate 2 may have an alignment mark for the purpose of aligning the elements 10 with the target substrate 2 when the elements 10 are picked up from the source substrate 1 and transferred.

[0022] The stamp head 30 is, for example, a rectangular plate-shaped base that is held on the underside of a through-hole 40a in the center of the top plate 40b of the frame 40 and that holds the stamp 3. As shown in Figure 2, the stamp head 30 may be of any type as long as it can hold a stamp 3 that has, for example, a T-shaped side, in other words, a rectangular plate-shaped stamp 3 with the central portion 3a protruding downward in the shape of a rectangular plate. The stamp head 30 may be provided with, for example, suction holes for adsorbing the stamp 3, and the stamp 3 may be brought into close contact with the stamp head 30 by applying negative pressure to the suction holes.

[0023] Here, the stamp 3 has viscoelasticity and is a member that uses its viscoelasticity, i.e., adhesive force, to pick up the elements 10 formed on the source substrate 1 with the central portion 3a of the stamp 3 and transfer the elements 10 to the desired positions on the target substrate 2. The stamp 3 is made of viscoelastic material such as silicone rubber. Any type of stamp 3 may be used as long as it has viscoelasticity. However, by making the stamp 3 transparent, the positions of the stamp 3 and the elements 10, or the positions of the elements 10 picked up by the stamp 3 and the target substrate 2, can be simultaneously observed from above in the Z-axis direction when capturing an image with the imaging unit 60 described below. The stamp 3 may have a convex structure, such as the protruding central portion 3a, on the surface facing the elements 10, with the same size as the elements 10 in the X-axis and Y-axis directions. This prevents other elements formed on the source substrate 1 from being picked up when the elements 10 come into contact with the stamp 3. The size of the convex structure of the stamp 3 in the X-axis direction and the Y-axis direction is not limited to being the same as that of the element 10, and it may be larger than or smaller than that of the element 10 in the X-axis direction and the Y-axis direction. By making the size of the convex structure of the stamp 3 in the Z-axis direction at least twice the size of the element 10 in the Z-axis direction, it is possible to easily prevent pick-up of other elements when the element 10 and the stamp 3 come into contact with each other.

[0024] The frame 40 is a downward C-shaped member and holds the stamp head 30 at a position below the through-hole 40a in the center of the top plate 40b. An imaging unit 60 (described later) is arranged above the through-hole 40a in the frame 40, and by using the imaging unit 60 to capture an image of the stamp head 30 side below the through-hole 40a, it is possible to observe the relative positions of the stamp 3 and the elements 10, or the relative positions of the elements 10 picked up by the stamp 3 and the target substrate 2, from above in the Z-axis direction. The frame 40 is made of a material such as stainless steel.

[0025] The substrate stage 50 is a platform disposed below the top plate 40b of the frame 40, and is supported by a substrate position adjustment mechanism 51. A source substrate mounting table 11 and a target substrate mounting table 21 are placed on the upper surface of the substrate stage 50. The substrate stage 50 may be integral with the source substrate mounting table 11 and the target substrate mounting table 21, or the source substrate mounting table 11 and the target substrate mounting table 21 may be fixed to the substrate stage 50 as separate members using screws or the like.

[0026] The substrate position adjustment mechanism 51 is a movable stage for adjusting the position of the substrate stage 50 in the X-axis, Y-axis, and Z-axis directions. Specifically, the substrate position adjustment mechanism 51 can adjust the position of the substrate stage 50 in the X-axis and Y-axis directions so that the relative positions of the elements 10 of the source substrate 1 placed on the source substrate placement table 11 on the substrate stage 50 and the stamp 3 in the X-axis and Y-axis directions roughly match during pickup. Furthermore, the substrate position adjustment mechanism 51 can adjust the position of the substrate stage 50 in the X-axis and Y-axis directions so that the relative positions of the target substrate 2 placed on the target substrate placement table 21 on the substrate stage 50 and the elements 10 picked up by the stamp 3 in the X-axis and Y-axis directions roughly match during transfer. Furthermore, the substrate position adjustment mechanism 51 controls the position of the substrate stage 50 in the Z-axis direction so that the elements 10 of the source substrate 1 placed on the source substrate placement table 11 on the substrate stage 50 and the stamp 3 can come into contact with and separate from each other during pickup, thereby enabling the pickup operation. Furthermore, the substrate position adjustment mechanism 51 controls the position of the substrate stage 50 in the Z-axis direction so that the target substrate 2 placed on the target substrate placement table 21 on the substrate stage 50 and the elements 10 picked up by the stamp 3 can come into contact with and separate from each other during transfer, thereby enabling the transfer operation. The substrate position adjustment mechanism 51 is realized by combining, for example, a linear stage using a linear ball guide, a gonio stage, etc.

[0027] An imaging unit 60 (described later) is used to detect positional misalignment during position adjustment of the substrate stage 50. The substrate position adjustment mechanism 51 is configured to be movable in at least four mutually different axial directions. The four axial directions include the X-axis, Y-axis, and Z-axis directions, as well as a rotational direction around the Z-axis. This allows for fine movements in each step of the element transfer method (described later), improving transfer accuracy and achieving high-quality transfer. The substrate position adjustment mechanism 51 may be movable in six directions: the X-axis, Y-axis, and Z-axis directions, as well as rotational directions around each of these axes. The substrate position adjustment mechanism 51 is provided with a motor (not shown) and an encoder (not shown), and position information detected by the encoder (not shown) is input to the control unit C1.

[0028] The imaging unit 60 is a unit disposed above the through-hole 40a of the frame 40 in the vertical direction, and captures images of the stamp 3 and the elements 10 on the source substrate 1, as well as the elements 10 picked up by the stamp 3 and the target substrate 2, thereby making it possible to detect the amount of misalignment between the stamp 3 and the elements 10 on the source substrate 1, and the amount of misalignment between the elements 10 picked up by the stamp 3 and the target substrate 2. The imaging unit 60 is composed of, for example, a lens and a camera, and information captured by the camera is input to the control unit C1, and the amount of misalignment is calculated by a calculation unit C2 of the control unit C1.

[0029] The imaging unit adjustment mechanism 61 is a movable stage for adjusting the position of the imaging unit 60. Specifically, the imaging unit 60 is adjusted to a position where the stamp 3 and the elements 10 on the source substrate 1 can be observed by the imaging unit 60 during pickup, and the elements 10 picked up by the stamp 3 and the target substrate 2 can be observed by the imaging unit 60 during transfer. The imaging unit adjustment mechanism 61 is realized by combining, for example, a linear motion stage using a linear ball guide. The imaging unit adjustment mechanism 61 is configured to be movable in at least three mutually different axial directions. The three axial directions include the X-axis direction, the Y-axis direction, and the Z-axis direction. The imaging unit adjustment mechanism 61 is provided with a motor (not shown) and an encoder (not shown), and position information detected by the encoder (not shown) is input to the control unit C1.

[0030] As shown in FIG. 2 , the contact detection unit 70 is a sensor disposed between the stamp head 30 and a vibration unit 80 (described later) to detect contact of the stamp 3. Specifically, for example, the contact detection unit 70 detects contact between the stamp 3 and the elements 10 on the source substrate 1 during pickup, and contact between the elements 10 picked up by the stamp 3 and the target substrate 2 during transfer. The contact detection unit 70 is, for example, a piezoelectric force sensor. The voltage and force information measured by the contact detection unit 70 is input to the control unit C1. By monitoring the force information detected by the contact detection unit 70 with the control unit C1, the position of the substrate stage 50 in the Z-axis direction can be adjusted, and the control unit C1 can detect the application of excessive pressure to the elements 10, thereby preventing damage to the elements 10.

[0031] As shown in FIG. 2 , the vibration unit 80 is disposed between the contact detection unit 70 and the frame 40 and applies vibration to the stamp 3 via the contact detection unit 70. Specifically, when the element 10 picked up by the stamp 3 and the target substrate 2 are separated in the Z-axis direction by the substrate position adjustment mechanism 51 during transfer, the vibration unit 80 applies vibration to the stamp 3 and the element 10 picked up by the stamp 3 via the contact detection unit 70. The vibration unit 80 generates any vibration, for example, with a frequency of 10 Hz to 100 kHz and an amplitude of 10 nm to 10 μm, and is, for example, an actuator using a piezoelectric element that utilizes the piezoelectric effect. The vibration unit 80 is configured to generate vibrations, for example, in the X-axis direction and the Y-axis direction, i.e., vibration direction A and vibration direction B shown in FIG. 2 . Preferably, the vibration unit 80 is configured to generate vibrations in three mutually different axial directions. The three axial directions include the X-axis direction, the Y-axis direction, and the Z-axis direction, which are respectively indicated as vibration direction A, vibration direction B, and vibration direction C in FIG. 2 . The vibration unit 80 is controlled by the control unit C1 so as to apply vibrations to the stamp 3 and the elements 10 of the stamp 3.

[0032] The control unit C1 is a microcomputer or the like that controls the operation of the components that make up the element transfer apparatus D1, and has a calculation unit C2 that performs various calculations, such as calculating the amount of misalignment from imaged information. The control unit C1 controls the image capture unit adjustment mechanism 61 so that, by capturing images with the image capture unit 60, the stamp 3 and the elements 10 on the source substrate 1 can be observed during pickup, and the elements 10 picked up by the stamp 3 and the target substrate 2 can be observed during transfer. The control unit C1 also controls the substrate position adjustment mechanism 51 so that the amount of misalignment in the X-axis and Y-axis directions between the stamp 3 and the elements 10 detected by the image capture unit 60 during pickup, and the amount of misalignment in the X-axis and Y-axis directions between the elements 10 picked up by the stamp 3 and the target substrate 2 during transfer, each approach as close to zero as possible. Furthermore, the control unit C1 detects contact between the stamp 3 and the elements 10 on the source substrate 1 during pickup and contact between the elements 10 picked up by the stamp 3 and the target substrate 2 during transfer, based on force information detected by the contact detection unit 70, and controls the substrate position adjustment mechanism 51. Furthermore, upon detecting contact between the elements 10 picked up by the stamp 3 and the target substrate 2 during transfer, the control unit C1 controls the vibration unit 80 to apply vibrations to the stamp 3 and the elements 10 on the stamp 3.

[0033] <Element Transfer Method> Next, the element 10 is transferred by at least the following steps S101 to S105.

[0034] First, in step S101, the control unit C1 controls the operation of the substrate position adjustment mechanism 51 based on the information captured by the imaging unit 60 to align the positions of the element 10 on the source substrate 1 and the stamp 3 (corresponding to step S10 below).

[0035] Next, in step S102, the control unit C1 controls the operation of the substrate position adjustment mechanism 51 to move the source substrate 1 and the stamp 3 relatively closer to each other and separate them, thereby picking up the element 10 onto the stamp 3 using the adhesive force of the stamp 3 (corresponding to steps S20, S21, and S30 below).

[0036] Next, in step S103, the control unit C1 controls the operation of the substrate position adjustment mechanism 51 based on the information captured by the imaging unit 60, and aligns the positions of the target substrate 2 and the elements 10 of the stamp 3 (corresponding to step S40 below).

[0037] Next, in step S104, the control unit C1 controls the operation of the substrate position adjustment mechanism 51 to bring the target substrate 2 and the stamp 3 relatively close to each other, so that the elements 10 of the stamp 3 come into contact with the target substrate 2 (corresponding to steps S50 and S51 below).

[0038] Next, in step S105, the vibration unit 80 applies vibration to the stamp 3 and the elements 10 on the stamp 3, while the control unit C1 controls the operation of the substrate position adjustment mechanism 51 to move the target substrate 2 and the stamp 3 relatively apart, thereby transferring the elements 10 from the stamp 3 to the target substrate 2 (corresponding to steps S60 and S70 below).

[0039] These steps are described in more detail below.

[0040] A method for transferring elements according to an embodiment of the present disclosure using element transfer apparatus D1 will be described with reference to Figures 3, 4A, 4B, 4C, 4D, 4E, 4F, and 4G. Figure 3 is a flowchart illustrating the method for transferring elements according to an embodiment of the present disclosure, and Figures 4A, 4B, 4C, 4D, 4E, 4F, and 4G are diagrams for explaining the method for transferring elements according to an embodiment of the present disclosure.

[0041] 4A, an alignment operation is performed between the element 10 and the stamp 3 (step S10). In step S10, the source substrate 1 is placed on the source substrate placement stage 11, and the target substrate 2 is placed on the target substrate placement stage 21.

[0042] Here, the alignment operation refers to the control of the control unit C1 to control the substrate position adjustment mechanism 51 to move the substrate stage 50 to a predetermined position in the XY plane. In step S10, the predetermined position refers to, for example, the position of the substrate stage 50 where the positions of the elements 10 on the source substrate 1 and the stamp 3 coincide in the XY plane. Here, "the positions of the elements 10 and the stamp 3 coincide" means that their alignment marks coincide with each other or their outer shapes coincide with each other. Therefore, in step S10, the imaging unit 60 images the elements 10 and the stamp 3 on the source substrate 1, and the calculation unit C2 calculates and detects the amount of misalignment between the elements 10 and the stamp 3 on the source substrate 1 relative to the predetermined position based on the image information. Based on the detected amount of misalignment, the substrate position adjustment mechanism 51 adjusts the position of the substrate stage 50 under the control of the control unit C1 so as to reduce the amount of misalignment. Adjusting the position of the substrate stage 50 adjusts the position of the source substrate 1 and the position of the elements 10 on the source substrate 1. Furthermore, if adjustment of the position of the imaging unit 60 is necessary, the position of the imaging unit 60 may be adjusted by the imaging unit adjustment mechanism 61 under the control of the control unit C1. The position adjustment accuracy of the substrate position adjustment mechanism 51 in the operation of step S10 is on the order of nanometers. Note that the accuracy of the position adjustment in the operation of step S10 is not limited to the order of nanometers, and may be performed to be on the order of micrometers. Figure 4A shows the state after the alignment operation of the element 10 and the stamp 3 is completed.

[0043] Next, as shown in FIG. 4B , the substrate stage 50 is raised (step S20). The substrate position adjustment mechanism 51 is used to raise the substrate stage 50 under the control of the controller C1. As the substrate stage 50 rises, the distance in the Z-axis direction between the elements 10 on the source substrate 1 and the stamp 3 decreases. After the substrate stage 50 starts to rise, if the controller C1 determines, based on the detection information from the contact detection unit 70, that the contact detection unit 70 has not detected contact between the elements 10 and the stamp 3 (step S21, NO), the controller C1 controls the substrate position adjustment mechanism 51 to continue raising the substrate stage 50. If the controller C1 determines, based on the detection information from the contact detection unit 70, that the contact detection unit 70 has detected contact between the elements 10 and the stamp 3 (step S21, YES), the controller C1 controls the substrate position adjustment mechanism 51 to stop raising the substrate stage 50.

[0044] Here, the threshold value used by the contact detector 70 to determine contact is appropriately set depending on the physical properties and shapes of the element 10 and the stamp 3. For example, if a piezoelectric force sensor is used for the contact detector 70, the threshold value used to determine contact is 1 nN to 10 N. In step S20, the substrate position adjustment mechanism 51 raises the substrate stage 50 at a speed of, for example, 1 nm / sec to 1000 μm / sec under the control of the controller C1. Note that by lowering the threshold value used by the contact detector 70 to determine contact or slowing the raising speed of the substrate stage 50, excessive elevation of the substrate stage 50 can be suppressed, thereby preventing damage to the element 10. Figure 4B shows a state in which the substrate stage 50 has been raised and the element 10 has come into contact with the stamp 3.

[0045] Next, as shown in FIG. 4C , the substrate stage 50 is lowered (step S30). The substrate position adjustment mechanism 51 is used under the control of the controller C1 to lower the substrate stage 50. With the elements 10 and the stamp 3 in contact, the substrate stage 50 is lowered under the control of the controller C1. By lowering the substrate stage 50 under the control of the controller C1, the elements 10 are peeled off from the source substrate 1 due to the adhesive force of the stamp 3 and picked up by the stamp 3. The adhesive force of the stamp 3 is appropriately selected depending on the physical properties of the elements 10 and the target substrate 2 (described later). In step S30, the substrate position adjustment mechanism 51 lowers the substrate stage 50 at a speed of, for example, 10 μm / sec to 1000 mm / sec under the control of the controller C1. It is known that the adhesive force of a viscoelastic material such as the stamp 3 increases depending on the peeling speed in a certain speed range. Therefore, the faster the speed at which the substrate stage 50 descends while the element 10 and the stamp 3 are in contact, the stronger the adhesive strength of the stamp 3 becomes, and the stronger the force that peels the element 10 from the source substrate 1. In other words, the element 10 can be easily picked up by the stamp 3. Figure 4C shows a state in which the substrate stage 50, which had been raised, is lowered after contact between the element 10 and the stamp 3 is detected.

[0046] Next, as shown in FIG. 4D , an alignment operation between the elements 10 and the target substrate 2 is performed (step S40). Here, the alignment operation refers to the controller C1 controlling the operation of the substrate position adjustment mechanism 51 to move the substrate stage 50 to a predetermined position in the XY plane. In step S40, the predetermined position refers to, for example, a position on the substrate stage 50 where the positions of the target substrate 2 and the elements 10 picked up by the stamp 3 coincide in the XY plane. Here, the alignment of the positions of the target substrate 2 and the elements 10 means that their alignment marks coincide with each other or their outer shapes coincide with each other. Therefore, in step S40, the imaging unit 60 images the target substrate 2 and the elements 10 picked up by the stamp 3, and the calculation unit C2 calculates and detects the amount of positional misalignment between the target substrate 2 and the elements 10 picked up by the stamp 3 relative to the predetermined position based on the image information. Based on the detected amount of positional misalignment, the substrate position adjustment mechanism 51 adjusts the position of the substrate stage 50 under the control of the controller C1 so as to reduce the amount of positional misalignment. The position of the target substrate 2 is adjusted by adjusting the position of the substrate stage 50. Furthermore, if adjustment of the position of the imaging unit 60 is necessary, the position of the imaging unit 60 may be adjusted by the imaging unit adjustment mechanism 61 under the control of the control unit C1. The position adjustment accuracy of the substrate position adjustment mechanism 51 by the operation of step S40 is on the order of nanometers. Note that the accuracy of the position adjustment in the operation of step S40 is not limited to the order of nanometers, and may be performed to be on the order of micrometers. Figure 4D shows a state in which the alignment operation of the target substrate 2 and the element 10 picked up by the stamp 3 has been completed.

[0047] Next, as shown in FIG. 4E , the substrate stage 50 is raised (step S50). As the substrate stage 50 rises, the distance in the Z-axis direction between the target substrate 2 and the element 10 picked up by the stamp 3 decreases. After the substrate stage 50 starts to rise, if the controller C1 determines, based on the detection information from the contact detector 70, that the contact detector 70 has not detected contact between the target substrate 2 and the element 10 picked up by the stamp 3 (step S51, NO), the controller C1 controls the substrate position adjustment mechanism 51 to continue raising the substrate stage 50. If the controller C1 determines, based on the detection information from the contact detector 70, that the contact detector 70 has detected contact between the target substrate 2 and the element 10 picked up by the stamp 3 (step S51, YES), the controller C1 controls the substrate position adjustment mechanism 51 to stop raising the substrate stage 50. The threshold value for determining contact by the contact detector 70 is appropriately set based on the mechanical properties and shapes of the target substrate 2, the stamp 3, and the element 10. For example, if a piezoelectric force sensor is used for the contact detection unit 70, the threshold for determining contact is 1 nN to 10 N. In step S50, the substrate position adjustment mechanism 51 raises the substrate stage 50 at a speed of, for example, 1 nm / sec to 1000 μm / sec. By lowering the threshold for determining contact in the contact detection unit 70 or slowing the raising speed of the substrate stage 50, excessive elevation of the substrate stage 50 can be suppressed, thereby preventing damage to the elements 10. FIG. 4E illustrates a state in which the substrate stage 50 has risen and the elements 10 picked up by the stamp 3 have come into contact with the target substrate 2. Here, the state in which the elements 10 picked up by the stamp 3 have come into contact with the target substrate 2 refers to a state in which the amount of pressing of the elements 10 into and held in contact with the target substrate 2 is greater than the amplitude of vibration in the Z-axis direction, as described below, so that the elements 10 do not detach from the target substrate 2 even when vibration is applied. Under such dimensional relationships, as an example, when the amplitude of vibration by the vibration unit 80 is 10 nm to 10 μm, the amount by which the element 10 is pressed into the target substrate 2 via the stamp 3 is, for example, 1 μm to 50 μm.Furthermore, by making the amount by which the element 10 is pressed into the target substrate 2 through the stamp 3 smaller than the dimension in the Z-axis direction of the convex structure of the stamp 3, contamination of the target substrate 2 or the stamp 3 caused by parts of the stamp 3 other than the convex structure coming into contact with the target substrate 2 can be prevented.

[0048] Next, with the target substrate 2 and the elements 10 picked up by the stamp 3 in contact with each other, the vibration unit 80 starts vibrating the stamp 3 and the elements 10 on the stamp 3 (step S60), as shown in Fig. 4F. When the vibration direction is the X-axis direction, i.e., vibration direction A, a shear stress acts at the interface between the target substrate 2 and the elements 10. The main cause of the adhesive force acting at the interface between the stamp 3 and the elements 10 is van der Waals force, but van der Waals bonds are more likely to break when a shear force acting in a lateral direction, for example, horizontally, i.e., in the X-axis and Y-axis directions, is applied compared to a tensile force in the vertical direction, i.e., in the Z-axis direction. Therefore, even if the force acting on the target substrate 2 and the elements 10 is weak when the substrate stage 50 is lowered in step S70 described later to relatively separate the target substrate 2 and the stamp 3, the vibration unit 80 can impart vibration to the stamp 3 and the elements 10 on the stamp 3, thereby breaking the van der Waals bonds formed at the interface between the stamp 3 and the elements 10, and therefore the elements 10 can be reliably transferred to the target substrate 2 with reduced adhesive force. Similarly, even when the vibration direction is the Y-axis direction, that is, vibration direction B shown in FIG. 2 , a shear stress acts at the interface between the target substrate 2 and the elements 10. 2 , a tensile stress acts at the interface between the target substrate 2 and the elements 10, and in addition to the tensile force acting when the substrate stage 50 is lowered to relatively separate the target substrate 2 and the stamp 3 in step S70 described later, the van der Waals bonds formed at the interface between the stamp 3 and the elements 10 can be broken by controlling the stress in the tensile direction due to the vibration, so that the elements 10 can be easily transferred to the target substrate 2 with reduced adhesive force. The vibration direction by the vibration unit 80 may be any one of the X-axis direction, Y-axis direction, and Z-axis direction, i.e., vibration direction A, vibration direction B, and vibration direction C shown in FIG. 2 . However, by simultaneously applying vibration in vibration direction A and vibration direction B, the elements 10 can be more easily transferred to the target substrate 2 when the substrate stage 50 is lowered in step S70 described later.Furthermore, by vibrating the vibration unit 80 in the X-axis direction, Y-axis direction, and Z-axis direction, i.e., vibration direction A, vibration direction B, and vibration direction C shown in FIG. 2 , the stress generated at the interface between the stamp 3 and the element 10 can be converted into a cleavage stress, thereby more locally reducing the adhesive force and enabling stable and easy transfer of the element 10 to the target substrate 2. Furthermore, in regions where the vibration frequency of the vibration unit 80 is low, the vibration is absorbed due to the stamp 3 being a viscoelastic material. On the other hand, in regions where the vibration frequency of the vibration unit 80 is too high, the stamp 3 is heated by the vibration, which may cause deterioration of the stamp material. Therefore, the vibration frequency of the vibration unit 80 should be 10 Hz to 100 kHz, and preferably 500 Hz to 50 kHz. This allows for more stable stress control by vibration and ensures reliable transfer of the element 10 to the target substrate 2. Furthermore, in regions where the amplitude of vibration by the vibration unit 80 is small, the vibration is absorbed due to the stamp 3 being made of a viscoelastic material. On the other hand, in regions where the amplitude of vibration by the vibration unit 80 is large, the vibration may damage the elements 10. Therefore, the vibration by the vibration unit 80 may have an amplitude of 10 nm to 10 μm, preferably 10 nm to 1 μm, to more stably obtain the effect of stress control by vibration and reliably transfer the elements 10 to the target substrate 2. Furthermore, the vibration unit 80 may be operated so that at least one of the vibration frequency and amplitude is non-uniform by operating at least one vibration direction at a different frequency or amplitude from the others. Figure 4F illustrates a state in which the vibration unit 80 applies vibration to the stamp 3 and the elements 10 on the stamp 3 after detecting contact between the target substrate 2 and the elements 10 on the stamp 3.

[0049] As a specific example, the adhesive force can be more easily reduced by increasing the amplitude in the X-axis direction or Y-axis direction parallel to the length direction of the outer shape of the element 10 where the aspect ratio is large (e.g., the direction along the long side of a rectangle or the long axis of an ellipse) compared to the amplitude in the Y-axis direction or X-axis direction parallel to the length direction of the outer shape of the element 10 where the aspect ratio is small (e.g., the direction along the short side of a rectangle or the short axis of an ellipse). This is because the elastic deformation of the stamp 3 is greater in the length direction of the outer shape of the element 10 than in the length direction of the outer shape of the element 10 where the aspect ratio is small, and the amplitude of the vibration is more absorbed by the stamp 3, thereby reducing the shear force generated at the interface between the stamp 3 and the element 10. When increasing the amplitude, it is preferable to increase it by at least about 10% in order to practically exert the adhesive force reduction effect, and it is more preferable to increase it by at least the aspect ratio of the outer shape of the element 10, i.e., if the aspect ratio is 2, it is more preferable to increase it by 200% or more.

[0050] Next, as shown in FIG. 4G , the substrate stage 50 is lowered (step S70). Under the control of the controller C1, the substrate stage 50 is lowered while the target substrate 2 and the picked-up elements 10 are in contact with each other and while the vibration unit 80 applies vibration to the stamp 3 and the elements 10 on the stamp 3. By this, the adhesion between the target substrate 2 and the elements 10 causes the elements 10 to peel off from the stamp 3 and be transferred to the target substrate 2. In step S70, the substrate position adjustment mechanism 51 lowers the substrate stage 50 at a speed of, for example, 1 nm / sec to 100 μm / sec. It is known that the adhesive force of a viscoelastic material such as the stamp 3 increases depending on the peeling speed within a certain speed range. Therefore, the slower the speed at which the substrate stage 50 is lowered while the target substrate 2 and the elements 10 on the stamp 3 are in contact with each other, the weaker the adhesive force of the stamp 3 and the ability of the stamp 3 to hold the elements 10 become. However, since the effect of the descent speed is limited, in step S60, the vibration unit 80 applies vibration to the stamp 3 and the elements 10 of the stamp 3, thereby reducing the adhesive force acting on the stamp 3 and the elements 10, thereby enabling reliable transfer even when the force acting on the target substrate 2 and the elements 10 is weak. Fig. 4G shows a state in which the raised substrate stage 50 has been lowered while the vibration unit 80 is applying vibration to the stamp 3 and the elements 10 of the stamp 3.

[0051] By the above steps, the transfer of the element 10 is achieved.

[0052] As described above, in the transfer of the element 10, in step S60, the vibration unit 80 applies vibration to the stamp 3 and the element 10 of the stamp 3 in at least one of the vibration directions A, B, and C shown in FIG. 2, thereby controlling the stress at the interface between the stamp 3 and the element 10 of the stamp 3 and reducing the adhesive force acting on the stamp 3 and the element 10 of the stamp 3, thereby enabling the element 10 to be reliably transferred to the target substrate 2.

[0053] Therefore, according to the above embodiment, neither plasma treatment nor heat treatment is required, and a simple configuration equipped with a vibration unit 80 is used, and by reducing the adhesive force when transferring the elements, it is possible to prevent the elements 10 from falling off or remaining on the stamp 3, and to achieve high-quality, i.e., high-precision and reliable transfer of the elements 10 to the target substrate 2.

[0054] It should be noted that any of the various embodiments or modifications described above can be appropriately combined to achieve the effects of each. In addition, combinations of embodiments, combinations of examples, or combinations of embodiments and examples are possible, and combinations of features from different embodiments or examples are also possible.

[0055] Although the present disclosure has been fully described in connection with the preferred embodiments with reference to the accompanying drawings, various changes or modifications will be apparent to those skilled in the art. Such changes or modifications should be understood to be included within the scope of the present disclosure as defined by the appended claims, unless they depart therefrom. Furthermore, changes in the combination or order of elements in the embodiments may be made without departing from the scope and spirit of the present disclosure.

[0056] (Additional Notes) The above description of the embodiments discloses the following techniques.

[0057] (Technology 1) A method for transferring an element, comprising: aligning the positions of a target substrate and an element picked up by the adhesive force of a stamp; bringing the target substrate and the stamp relatively close to each other to bring the target substrate and the element into contact; and transferring the element from the stamp to the target substrate by moving the target substrate and the stamp relatively apart while applying vibrations to the stamp and the element using a vibration unit.

[0058] (Technology 2) The element transfer method according to Technology 1, further comprising, before the alignment, bringing a source substrate having the elements and the stamp relatively close to and farther from each other, and picking up the elements of the source substrate onto the stamp by the adhesive force of the stamp.

[0059] (Technology 3) The method for transferring an element according to Technology 1 or 2, wherein bringing the target substrate and the stamp relatively close to each other to bring the target substrate and the element into contact includes detecting contact between the target substrate and the element by a contact detection unit, and moving the target substrate and the stamp relatively apart while applying vibrations to the stamp and the element by the vibration unit includes applying vibrations to the stamp and the element in at least one of an X-axis direction, a Y-axis direction, and a Z-axis direction by the vibration unit.

[0060] (Technology 4) The method for transferring an element described in Technology 3, wherein bringing the target substrate and the stamp relatively close to each other to bring the target substrate and the element into contact includes pressing the element into the target substrate by a predetermined pressing amount, and the vibration by the vibration unit has an amplitude in the Z-axis direction, and the amplitude in the Z-axis direction is smaller than the predetermined pressing amount.

[0061] (Technology 5) The element transferring method according to any one of Technologies 1 to 4, wherein the frequency of the vibration by the vibration unit is 10 Hz to 100 kHz, and the amplitude of the vibration by the vibration unit is 10 nm to 10 μm.

[0062] (Technology 6) A target substrate setting table on which a target substrate is set; a stamp head having a stamp capable of picking up an element by adhesive force; a frame holding the stamp head so that the stamp can face the target substrate setting table; a substrate position adjustment mechanism capable of adjusting the position of the target substrate with respect to the stamp and of moving the target substrate and the stamp relatively closer to or farther apart; an imaging unit that images the element and the stamp and also images the element and the target substrate, thereby making it possible to detect the amount of positional misalignment between the element and the stamp and the amount of positional misalignment between the element and the target substrate; a contact detection unit that detects contact between the element and the target substrate; and a vibration unit that is arranged between the contact detection unit and the frame and applies vibrations to the stamp and the element. (a) controlling the substrate position adjustment mechanism so as to reduce the amount of misalignment; (b) controlling the substrate position adjustment mechanism so as to bring the target substrate and the stamp relatively closer together; (c) detecting contact between the target substrate and the element of the stamp using the contact detection unit; (d) controlling the vibration unit so as to impart vibration to the stamp and the element; and (e) a control unit that controls the vibration unit and the substrate position adjustment mechanism so as to transfer the element from the stamp to the target substrate by relatively separating the target substrate and the stamp while imparting vibration to the stamp and the element.

[0063] (Technology 7) An element transfer device according to Technology 6, further comprising a source substrate setting table on which a source substrate on which the element is formed is set, wherein the frame holds the stamp head so that the stamp can also face the source substrate setting table, the substrate position adjustment mechanism is capable of adjusting the position of the source substrate with respect to the stamp and is capable of moving the source substrate and the stamp closer and farther apart relative to each other, the contact detection unit detects contact between the element and the stamp, and the control unit controls the substrate position adjustment mechanism to move the source substrate and the stamp closer and farther apart relative to each other, thereby picking up the element onto the stamp by the adhesive force of the stamp.

[0064] (Technology 8) The element transfer device described in Technology 7, wherein the control unit detects contact between the element and the stamp using the contact detection unit when picking up the element onto the stamp by the adhesive force of the stamp, and the control unit controls the vibration unit to apply vibration to the stamp and the element in at least one direction among an X-axis direction, a Y-axis direction, and a Z-axis direction when transferring the element from the stamp to the target substrate.

[0065] (Technology 9) The element transfer device described in Technology 8, wherein the control unit controls the substrate position adjustment mechanism so as to press the element into the target substrate by a predetermined pressing amount when the target substrate and the stamp are brought relatively close to each other, and the vibration by the vibration unit has an amplitude in the Z-axis direction, and the amplitude in the Z-axis direction is smaller than the predetermined pressing amount.

[0066] (Technology 10) The element transfer apparatus according to any one of Technologies 6 to 9, wherein the vibration unit generates any vibration having a frequency of 10 Hz to 100 kHz and an amplitude of 10 nm to 10 μm.

[0067] Each of these technologies does not require plasma treatment or heat treatment, and uses a simple configuration that includes a vibration unit that applies vibration to the element and stamp, thereby reducing the adhesive force when transferring the element, thereby enabling high-precision and reliable transfer of the element.

[0068] An embodiment of the present disclosure can be suitably used for an element transfer method and an element transfer device. Furthermore, the element transfer method and element transfer device according to the above aspect of the present disclosure can transfer, for example, an optical element to a target substrate with high accuracy, and therefore can be applied in fields such as micro LED displays, high-speed optical communications typified by silicon photonics, and high-accuracy sensing using laser light.

[0069] REFERENCE SIGNS LIST 1 source substrate 2 target substrate 3 stamp 3a central portion 10 element 11 source substrate mounting base 21 target substrate mounting base 30 stamp head 40 frame 40a through hole 40b top plate 50 substrate stage 51 substrate position adjustment mechanism 60 imaging unit 61 imaging unit adjustment mechanism 70 contact detection unit 80 vibration unit C1 control unit C2 calculation unit D1 element transfer device

Claims

1. A method for transferring an element, comprising: aligning the positions of a target substrate and an element picked up by the adhesive force of a stamp; bringing the target substrate and the stamp relatively close to each other to bring the target substrate and the element into contact with each other; and transferring the element from the stamp to the target substrate by moving the target substrate and the stamp relatively apart while applying vibrations to the stamp and the element with a vibration unit.

2. The method for transferring an element according to claim 1, further comprising, prior to the alignment, bringing a source substrate having the element and the stamp relatively close to and away from each other, and picking up the element of the source substrate onto the stamp by the adhesive force of the stamp.

3. The method for transferring an element as described in claim 1, wherein bringing the target substrate and the stamp relatively close to each other to bring the target substrate and the element into contact includes detecting contact between the target substrate and the element by a contact detection unit, and moving the target substrate and the stamp relatively apart while imparting vibrations to the stamp and the element by the vibration unit includes imparting vibrations to the stamp and the element in at least one of an X-axis direction, a Y-axis direction, and a Z-axis direction by the vibration unit.

4. The method for transferring an element as described in claim 3, wherein bringing the target substrate and the stamp relatively close to each other to bring the target substrate and the element into contact includes pressing the element into the target substrate by a predetermined pressing amount, and the vibration by the vibration unit has an amplitude in the Z-axis direction, and the amplitude in the Z-axis direction is smaller than the predetermined pressing amount.

5. The element transfer method according to any one of claims 1 to 4, wherein the frequency of the vibration caused by the vibration unit is 10 Hz to 100 kHz, and the amplitude of the vibration caused by the vibration unit is 10 nm to 10 μm.

6. A target substrate mounting table on which a target substrate is mounted; a stamp head having a stamp capable of picking up an element by its adhesive force; a frame holding the stamp head so that the stamp can face the target substrate mounting table; a substrate position adjustment mechanism capable of adjusting the position of the target substrate with respect to the stamp and moving the target substrate and the stamp relatively closer to each other; an imaging unit that images the element and the stamp and also images the element and the target substrate to detect the amount of positional misalignment between the element and the stamp and the amount of positional misalignment between the element and the target substrate; a contact detection unit that detects contact between the element and the target substrate; and a vibration unit that is disposed between the contact detection unit and the frame and applies vibrations to the stamp and the element. (a) controlling the substrate position adjustment mechanism so as to reduce the amount of positional misalignment; (b) controlling the substrate position adjustment mechanism so as to bring the target substrate and the stamp relatively closer together; (c) detecting contact between the target substrate and the element by the contact detection unit; (d) controlling the vibration unit so as to impart vibration to the stamp and the element; and (e) a control unit which controls the vibration unit and the substrate position adjustment mechanism so as to transfer the element from the stamp to the target substrate by relatively separating the target substrate and the stamp while imparting vibration to the stamp and the element.

7. An element transfer device as described in claim 6, further comprising a source substrate mounting table on which a source substrate on which the element is formed is mounted, wherein the frame holds the stamp head so that the stamp can face the source substrate mounting table as well, the substrate position adjustment mechanism is capable of adjusting the position of the source substrate relative to the stamp and of moving the source substrate and the stamp relatively closer to and farther from each other, the contact detection unit detects contact between the element and the stamp, and the control unit controls the substrate position adjustment mechanism to move the source substrate and the stamp relatively closer to and farther from each other so that the element is picked up by the stamp by the adhesive force of the stamp.

8. The element transfer device described in claim 7, wherein the control unit detects contact between the element and the stamp using the contact detection unit when the element is picked up onto the stamp by the adhesive force of the stamp, and the control unit controls the vibration unit to impart vibration to the stamp and the element in at least one of the X-axis direction, Y-axis direction, and Z-axis direction when the element is transferred from the stamp to the target substrate.

9. The element transfer device described in claim 8, wherein the control unit controls the substrate position adjustment mechanism so as to press the element into the target substrate by a predetermined amount when the target substrate and the stamp are brought relatively close to each other, and the vibration produced by the vibration unit has an amplitude in the Z-axis direction, and the amplitude in the Z-axis direction is smaller than the predetermined amount of pressing.

10. An element transfer device according to any one of claims 6 to 9, wherein the vibration unit generates any vibration having a frequency of 10 Hz to 100 kHz and an amplitude of 10 nm to 10 μm.

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