阅读说明：本技术 用于转移半导体器件的桥拾取头 (Bridge pick-up head for transferring semiconductor devices ) 是由 奥斯卡·托伦茨阿巴德 丹尼尔·布罗多塞亚努 阿里·森古尔 波亚·萨克提 于 2020-04-21 设计创作，主要内容包括：拾取工具(PUT)包括桥拾取头。桥拾取头包括：第一桥支腿部分、第二桥支腿部分以及在第一支腿部分和第二支腿部分之间的桥中心部分,第一桥支腿部分和第二桥支腿部分均包括顶面和侧面,第一桥支腿部分和第二桥支腿部分的顶面在桥中心部分上方延伸；在桥中心部分上的桥基部分,桥基部分包括在桥中心部分上的底侧、小于底侧的顶侧以及限定在顶侧和底侧之间的一个或更多个倾斜表面；以及尖端,该尖端被配置为在桥基部分的顶侧上与半导体器件附接。(The pick-up tool (PUT) comprises a bridge pick-up head. The bridge pick-up head includes: a first bridge leg portion, a second bridge leg portion, and a bridge center portion between the first leg portion and the second leg portion, the first bridge leg portion and the second bridge leg portion each including a top surface and a side surface, the top surfaces of the first bridge leg portion and the second bridge leg portion extending above the bridge center portion; an abutment portion on the bridge center portion, the abutment portion including a bottom side on the bridge center portion, a top side smaller than the bottom side, and one or more inclined surfaces defined between the top side and the bottom side; and a tip configured to attach with the semiconductor device on the top side of the abutment portion.)

1. A system, comprising:

a target substrate; and

pick-up tool (PUT), comprising:

a first leg portion and a second leg portion;

an abutment portion between the first leg portion and the second leg portion; and

a tip on the bridge base portion, the tip configured to attach with a semiconductor device and place the semiconductor device on the target substrate, the first leg portion and the second leg portion contacting the target substrate when the semiconductor device is placed on the target substrate.

2. The system of claim 1, wherein:

the abutment portion and the tip exert a force on the semiconductor device toward the target substrate; and

the bridge portion is compressed when the force is applied to the semiconductor device.

3. The system of claim 2, wherein:

the first and second leg portions extend below the tip when the abutment portion is compressed to adhere to the target substrate and hold the semiconductor device in a target position on the target substrate; and

the tip extends under the first leg portion and the second leg portion when the abutment portion is uncompressed.

4. The system of any preceding claim, wherein any one or more of the following holds:

a) wherein the PUT comprises a conformable material; or

b) Wherein a space is defined between the bridge base portion and the bridge leg portion, and another semiconductor device previously placed on the target substrate is fitted in the space when the first leg portion and the second leg portion contact the target substrate.

5. The system of any preceding claim, wherein the PUT comprises:

a substrate;

a backing layer on the substrate; and

a bridge pick head comprising the first and second leg portions, the abutment portion and a tip, the bridge pick head being located on the backing layer.

6. The system of claim 5, wherein the substrate is formed from a fused silica wafer, the backing layer is formed from Polydimethylsiloxane (PDMS), and the bridge pick-up head is formed from PDMS.

7. The system of any preceding claim, wherein the PUT is transparent to light.

8. The system of claim 7, further comprising an imaging device configured to generate an image using light transmitted through the PUT to align the semiconductor device attached with the PUT with a target location on the target substrate.

9. The system of any preceding claim, wherein one or more of the following holds:

a) wherein at least one of the first and second bridge leg portions includes an alignment mark; or

b) Wherein at least one of the first and second bridge leg portions comprises a displacement feature that deforms to indicate an amount of pressure applied by the PUT; or

c) Further comprising a target table holding the target substrate, the target table configured to apply heat to the target substrate when the first leg portion and the second leg portion contact the target substrate to bond contacts of the semiconductor device with contacts of the target substrate.

10. The system of any preceding claim, further comprising a carrier substrate, and wherein the PUT is configured to pick the semiconductor device from the carrier substrate.

11. The system of claim 10, wherein the bridge portion is uncompressed and the tip extends below the first and second leg portions when the tip is in contact with and attached to the semiconductor device on the carrier substrate.

12. A method, comprising:

attaching a semiconductor device to a tip of a pick tool (PUT), the PUT comprising:

a first leg portion and a second leg portion;

an abutment portion between the first leg portion and the second leg portion; and

the tip on the abutment portion; and

placing the semiconductor device on a target substrate by the PUT, the first leg portion and the second leg portion contacting the target substrate when the semiconductor device is placed on the target substrate.

13. The method of claim 12, wherein:

the abutment portion and the tip exert a force on the semiconductor device toward the target substrate; and

the bridge portion is compressed when the force is applied to the semiconductor device.

14. The method of claim 13, wherein:

the first and second leg portions extend below the tip when the abutment portion is compressed to adhere to the target substrate and hold the semiconductor device in a target position on the target substrate; and

the tip extends under the first leg portion and the second leg portion when the abutment portion is uncompressed.

15. The method of any one of claims 12 to 14, wherein one or more of the following holds true:

a) wherein the PUT comprises a conformable material; or

b) Wherein a space is defined between the bridge base portion and the bridge leg portion, and another semiconductor device previously placed on the target substrate is fitted within the space when the first leg portion and the second leg portion contact the target substrate; or

c) Wherein the PUT is transparent to light; and the method further comprises generating an image using light transmitted through the PUT to align the semiconductor device attached to the PUT with a target location on the target substrate.

Background

The present disclosure relates to the manufacture of small display elements that are transferred from an initial substrate to a receiving substrate using a pick and place transfer process.

In order to fill (output) a display with very small Light Emitting Diodes (LEDs), such as micro-LEDs, it may be necessary to transfer the LEDs from a native substrate (native substrate) or temporary carrier substrate on which the LEDs are fabricated to a target substrate or "display substrate" that forms part of the display. Such small semiconductor devices may be assembled on a target substrate with a defined separation distance between them or packed closely together. Because of the small size of these devices (e.g., less than 100 μm in diameter or width), conventional pick and place techniques are not suitable.

SUMMARY

According to a first aspect of the present invention, there is provided a system comprising: a target substrate; and a pick-up tool (PUT), the pick-up tool comprising: a first leg portion and a second leg portion; an abutment portion between the first leg portion and the second leg portion; and a tip on the bridge base portion, the tip configured to attach with and place the semiconductor device on the target substrate, the first leg portion and the second leg portion contacting the target substrate when the semiconductor device is placed on the target substrate.

Preferably, the abutment portion and the tip exert a force on the semiconductor device towards the target substrate; and the bridge portion is compressed when the force is applied to the semiconductor device.

Conveniently, the first leg portion and the second leg portion extend below the tip when the abutment portion is compressed to adhere to the target substrate and hold the semiconductor device in a target position on the target substrate; and, when the abutment portion is uncompressed, the tip extends below the first leg portion and the second leg portion.

Preferably, the PUT comprises a conformable material.

Conveniently, a space is defined between the abutment portion and the bridge leg portion, and another semiconductor device previously placed on the target substrate is fitted in the space when the first leg portion and the second leg portion contact the target substrate.

Preferably, the PUT comprises: a substrate; a backing layer on the substrate; and a bridge pick-up head (bridge pick-up head) comprising first and second leg portions, a bridge base portion, and a tip, the bridge pick-up head being located on the backing layer.

Conveniently, the substrate is formed from a fused silica wafer, the backing layer is formed from Polydimethylsiloxane (PDMS), and the bridge pick-up head is formed from PDMS.

Preferably, the PUT is transparent to light.

Conveniently, the system further comprises an imaging device configured to generate an image using light transmitted through the PUT to align the semiconductor device attached to the PUT with a target location on a target substrate.

Preferably, at least one of the first and second bridge leg portions comprises an alignment mark.

Conveniently, at least one of the first and second bridge leg portions comprises a displacement feature that deforms to indicate an amount of pressure applied by the PUT.

Preferably, the system further includes a target table holding a target substrate, the target table being configured to apply heat to the target substrate when the first leg portion and the second leg portion contact the target substrate to bond contacts of the semiconductor device with contacts of the target substrate (bond).

Conveniently, the system further comprises a carrier substrate, and wherein the PUT is configured to pick up the semiconductor device from the carrier substrate.

Preferably, the bridge portion is uncompressed when the tip is in contact with and attached to a semiconductor device on the carrier substrate, and the tip extends below the first and second leg portions.

According to another aspect of the present invention, there is provided a method comprising: attaching a semiconductor device to a tip of a pick tool (PUT), the PUT comprising: a first leg portion and a second leg portion; an abutment portion between the first leg portion and the second leg portion; and a tip on the abutment portion; and placing the semiconductor device on the target substrate by the PUT, the first leg portion and the second leg portion contacting the target substrate when the semiconductor device is placed on the target substrate.

Preferably, the abutment portion and the tip exert a force on the semiconductor device towards the target substrate; and the bridge portion is compressed when a force is applied to the semiconductor device.

Conveniently, the first leg portion and the second leg portion extend below the tip when the abutment portion is compressed to adhere to the target substrate and hold the semiconductor device in a target position on the target substrate; and, when the abutment portion is uncompressed, the tip extends below the first leg portion and the second leg portion.

Preferably, the PUT comprises a conformable material.

Conveniently, a space is defined between the abutment portion and the bridge leg portion, and another semiconductor device previously placed on the target substrate is fitted in the space when the first leg portion and the second leg portion contact the target substrate.

Preferably, the PUT is transparent to light; and, the method further comprises generating an image using light transmitted through the PUT to align the semiconductor device attached to the PUT with a target location on a target substrate.

Embodiments relate to pick-up tools (PUTs) for picking, placing and bonding semiconductor devices, such as LEDs, to a target substrate. Some embodiments include a system comprising a target substrate and a pick tool (PUT). The PUT includes: the leg assembly includes first and second leg portions, an abutment portion between the first and second leg portions, and a tip on the abutment portion. The tip is attached with the semiconductor device and the semiconductor device is placed on the target substrate. The first leg portion and the second leg portion contact the target substrate when the semiconductor device is placed on the target substrate.

Embodiments are also related to attaching a semiconductor device to a tip of a pick tool (PUT). The PUT includes first and second leg portions, an abutment portion between the first and second leg portions, and a tip on the abutment portion. The method also includes placing the semiconductor device on the target substrate by the PUT. The first leg portion and the second leg portion contact the target substrate when the semiconductor device is placed on the target substrate.

Brief Description of Drawings

Fig. (fig.)1 is a diagram showing a display assembly system according to an embodiment.

FIG. 2 is a diagram illustrating a bridge pick tool (PUT) according to one embodiment.

FIG. 3 is a diagram illustrating a bridge pick-up head according to one embodiment.

FIG. 4 is a diagram illustrating a side view of a bridge pick-up head according to one embodiment.

FIG. 5 is a diagram illustrating a close-up view of the tip of a bridge pick-up head according to one embodiment.

Fig. 6A is a diagram illustrating picking of a semiconductor device using a bridge pick-up tool (bridge-up tool) according to an embodiment.

Fig. 6B is a diagram illustrating placement and bonding of semiconductor devices using a bridge pick tool according to one embodiment.

Fig. 7 is a schematic diagram illustrating a displacement sensor of a pickup according to an embodiment.

Fig. 8A, 8B, and 8C are diagrams illustrating manufacturing of a bridge PUT according to an embodiment.

FIG. 9 is a flow diagram of a method of manufacturing an electronic device according to one embodiment.

The figures depict embodiments of the present disclosure for purposes of illustration only.

Detailed Description

Embodiments relate to pick-up tools (PUTs) for picking, placing and bonding semiconductor devices, such as LEDs, to a target substrate. The PUT has a structure that provides stability during pick, place, and bonding operations and prevents contact with previously bonded semiconductor devices. The PUT is transparent and may include alignment marks to facilitate optical alignment during pick, place and bond operations. The PUT may include a displacement feature to facilitate measurement of force-displacement during thermocompression bonding.

Overview of the System

FIG. 1 is a diagram illustrating a display assembly system 100 according to one embodiment. The system 100 manufactures a display device by assembling the semiconductor device 112 from the carrier substrate 114 to the target substrate 118. In some embodiments, the semiconductor devices 112 are Light Emitting Diodes (LEDs) of different colors. The carrier substrate 114 may be a temporary carrier that holds the LEDs for pick up by the Pick Up Tool (PUT) 104. The target substrate 118 may be a display substrate of a display device including control circuitry for the LEDs. The system 100 places the LEDs at pixel locations of the display substrate and then bonds the LEDs to the display substrate.

In some embodiments, semiconductor device 112 is a μ LED having a diameter or width less than 100 μm, reduced divergence of light output, and a small light emitting area. In some embodiments, the feature size (e.g., diameter) and spacing of the μ LEDs (e.g., spacing between μ LEDs on the target substrate 118 or carrier substrate 114) is in the sub-micron (e.g., about 0.1 μm) to 10 μm range. In other embodiments, the semiconductor device 112 is a Vertical Cavity Surface Emitting Laser (VCSEL).

The system 100 may include, among other components, a chamber 102, the chamber 102 defining an internal environment for picking and placing semiconductor devices 112 within the chamber 102. System 100 also includes PUT 104, controller 106, imaging device 108, pickup actuator 122, and object table 120.

Controller 106 is coupled to imaging device 108 and PUT 104 via pickup actuator 122, and controls the operation of these components. For example, the controller 106 also causes the PUT 104 to pick up one or more semiconductor devices 112 located on the carrier substrate 114 via (e.g., van der waals forces or chemical) attachment and place the one or more semiconductor devices 112 on the target substrate 118. In some embodiments, the controller includes a processor 160 and a memory 162. The memory 162 may be a non-transitory computer-readable storage medium that stores instructions that, when executed by the processor 160, cause the processor 160 to perform the functions discussed herein, for example, by controlling other components of the system 100. In some embodiments, the controller 106 may comprise an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), or other type of processing circuitry.

PUT 104 includes one or more pick-up heads 124. PUT 104 can include an array of pick-up heads 124 attached to a pick-up head substrate 126. Each pick-up head 124 may pick up a semiconductor device 112 from the carrier substrate 114 and place the semiconductor device 112 on the target substrate 118. In some embodiments, each pick-up head 124 includes a compliant tip (compliant tip) that adheres to the semiconductor device 112. PUT 104 can support selective, parallel pick and place of multiple semiconductor devices 112 via attachment to pick head 124. In some embodiments, the system 100 includes a single pick-up head 124 rather than an array.

After picking up the semiconductor device 112, the pickup head 124 is aligned with a target position on the target substrate 118 to place the semiconductor device 112 on the target substrate 118.

The pickup actuator 122 is an electromechanical component that controls the movement of the PUT 104 based on control signals from the controller 106. For example, the pick-up head actuator 122 may move the PUT 104 or a single pick-up head 124 with multiple degrees of freedom, including up and down, left and right, front and back, and rotation along X, Y and the Z-axis. In some embodiments, the pickup head actuator 122 may include a rotary motor, a linear motor, and/or a hydraulic cylinder.

The imaging device 108 facilitates visual alignment of picking up the semiconductor device 112 from the carrier substrate 114 and placing the semiconductor device 112 on the target substrate 118. The PUT 104 can be formed of a transparent material such that the substrates 114, 118 and the semiconductor device 112 are visible through the PUT 104. Imaging device 108 generates images of PUT 104 and carrier substrate 114 and provides the images to controller 106. Controller 106 aligns one or more pick-up heads 124 of PUT 104 with one or more semiconductor devices 112 on carrier substrate 114 based on the image and picks up the one or more semiconductor devices 112. In another example, the imaging device 108 generates images of the one or more pickup heads 124 of the PUT 104 and the target substrate 118 and provides the images to the controller 106. The controller 106 aligns the one or more pickup heads 124 with the display substrate 118 based on the images and places the one or more semiconductor devices 112 attached to the one or more pickup heads 124 on the display substrate 118. The system 100 may include a plurality of imaging devices, such as an imaging device directed at the carrier substrate 114, an imaging device directed at the target substrate 118. In some embodiments, imaging device 108 is attached to PUT 104.

The system 100 may include one or more carrier substrates 114. For example, different carrier substrates 114 may carry different color LEDs. Carrier substrate 114 may hold singulated semiconductor devices 112 for transfer to a target substrate 118. The system 100 may also include one or more target substrates 118. In some embodiments, such as when the target substrate 118 is a display substrate for receiving the semiconductor device 112, the system includes a target table 120 having heaters for thermo-compression (TC) bonding the electrical contacts 148 and 150 of the semiconductor device 112 to the contacts of the target substrate 118. The heater may provide heat in conjunction with the PUT 104 exerting a force on the semiconductor device 112 toward the target substrate 118. In some embodiments, laser assisted bonding may be used to bond electrical contacts 148 and 150 of semiconductor device 112 to contacts of target substrate 118. For example, as PUT 104 exerts a force on semiconductor device 112, a laser may be directed through PUT 104 to apply heat to electrical contacts 148 and 150 of semiconductor device 112 to facilitate bonding.

FIG. 2 is a diagram illustrating a bridge pick tool (PUT)200 according to one embodiment. Bridge PUT 200 is an example of PUT 104 of display assembly system 100. Bridge PUT 200 includes a pick head substrate 226 that provides a support structure for one or more bridge pick heads 222. The pick-up head substrate 226 may be formed of a transparent rigid material, such as a fused silica wafer.

Bridge PUT 200 also includes backing layer 224 on pick-up head substrate 226 and bridge pick-up head 222 on backing layer 224. The backing layer 224 may be formed of a transparent conformable material. In some embodiments, the backing layer 224 is formed of an elastomer, such as Polydimethylsiloxane (PDMS).

The bridge pick-up head 222 provides a surface for attachment with one or more semiconductor devices 112. The bridge pick-up head 222 may be formed of a transparent conformable material that provides adhesion with the one or more semiconductor devices 112. In some embodiments, bridge pick-up head 222 is formed of an elastomer that is transparent and provides sufficient adhesion material, such as Polydimethylsiloxane (PDMS). In some embodiments, bridge pick-up head 222 provides attachment to one or more semiconductor devices 112 via covalent bonding or van der waals bonding.

Pick-up head substrate 226, backing layer 224, and bridge pick-up head 222 may each be transparent to light to allow visibility through bridge PUT 200 to facilitate alignment using imaging device 108 during pick-and-place operations.

Although a single bridge pick-up head 222 and backing layer 224 are shown in fig. 2, bridge PUT 200 may include an array of bridge pick-up heads 222 and backing layers 224 to facilitate parallel pick-up and placement of multiple semiconductor devices 112.

Fig. 3 is a diagram illustrating a bridge pick-up head 222 according to an embodiment, and fig. 4 is a diagram illustrating a side view of the bridge pick-up head 222. Bridge pick-up head 222 includes a bridge leg portion 302a, a bridge leg portion 302b, a bridge base portion 316 between bridge leg portions 302a and 302b, and a tip 306 on bridge base portion 316.

The tip 306 includes a tip base portion 308 on an abutment portion 316, a tip center portion 310 on the tip base portion 308, and a tip apex portion 312 on the tip center portion 310. The tip portion 312 includes a pick-up surface 322 attached to the semiconductor device 112. The tip apex portion 312 and the tip center portion 310 may form a base (pedestal) having a mushroom shape, as shown in fig. 4, the width of the tip apex portion 312 being wider than the width of the tip center portion 310. In other examples, tip 306 may include some other shape. For example, the tip portion 312 may form a flap that is attached to the tip central portion 310 on one side and protrudes out of the other side of the tip central portion 310. In some embodiments, a plurality of tips 306 may be located on the abutment portion 316.

The bridge leg portions 302a and 302b each include a bridge leg surface 320. Each bridge leg surface 320 may include one or more alignment marks 314 to facilitate alignment of bridge pick-up head 222 during pick and place operations. For example, the alignment marks 314 increase the bonding accuracy of the semiconductor device 112 to the target substrate 118 during the bonding cycle. In some embodiments, the alignment marks 314 are defined by grooves in the bridge leg surface 320.

The abutment portion 316 is between the bridge leg portions 302a and 302 b. As shown in FIG. 4, the abutment portion 316 has a bottom side 324 and a top side 326, wherein the bottom side is larger than the top side 326, and one or more inclined surfaces 332 defined between the bottom side 324 and the top side 326. The abutment portion 316 may include a pyramidal, conical, or other sloped shape. A space 330 is defined between one or more inclined surfaces 332 of the abutment portion 316 and a (e.g., non-inclined) side surface 334 of the leg portions 302a and 304 b. The space 330 prevents contact with nearby semiconductor devices 112 during pick or place operations. During the bonding cycle, the space 330 prevents contact or shearing (shearing) with the semiconductor device 112 previously bonded to the target substrate 118.

In some embodiments, as discussed in more detail in connection with fig. 8A, 8B, and 8C, bridge pickup head 222 may be fabricated using a 3D printing process and a subsequent dual molding step process. This allows fabrication of bridge pickup heads 222 with sub-micron features and tailoring of stress distribution during bonding of semiconductor devices 112 to target substrate 118.

FIG. 5 is an illustration showing a close-up view of tip 306 of bridge pick-up head 222, in accordance with one embodiment. As shown, the tip 306 includes a tip apex portion 312 having a pick-up surface 322, a tip center portion 310 below the apex portion 312, and a tip base portion 308 below the tip center portion 310.

Fig. 6A is a diagram illustrating the pick-up of a semiconductor device using a bridge PUT 600 according to one embodiment. Bridge PUT 600 is similar to bridge PUT 200, but includes a plurality of tips 306a and 306b attached to abutment portion 316.

In one pick, place, and bond cycle, the bridge PUT 600 picks the semiconductor devices 112a and 112b from the carrier substrate 114, places the semiconductor devices 112a and 112b on the target substrate 118, and bonds contacts of the semiconductor devices 112a and 112b to the contacts 602 of the target substrate 118.

As shown in fig. 6A, bridge PUT 600 picks up semiconductor devices 112a and 112b from carrier substrate 114 by contacting semiconductor devices 112a and 112b with tips 306A and 306b, respectively. Contact between each tip 306 and the semiconductor device 112 results in (e.g., adhesive) attachment. In some embodiments, an elastic layer is formed on the semiconductor device 112 to facilitate attachment.

A light contact between tip 306 and semiconductor device 112 may be sufficient to achieve attachment, and thus bridge PUT 600 deforms little or no during pick-up. Bridge PUT 600 is at or near rest. In the rest state, tip 306 of bridge PUT 600 extends beyond bridge leg portions 302a and 302 b. A bridge gap is defined between bridge leg portions 302a and 302b and carrier substrate 114. The bridge gap prevents contact with the non-selected semiconductor devices 112c on the carrier substrate 114. In addition, the space 330 defined by the bridge depth (defined from the bridge leg surface 320 to the junction of the bridge leg portion 302 at the bottom side 324 of the bridge base portion 316) and the bridge width (defined from the end of the top side 326 to the junction of the bridge leg portion 302) prevents contact with the non-selected semiconductor devices 112d on the carrier substrate 114 proximate to the selected semiconductor devices 112a and 112.

Once the semiconductor devices 112a and 112b are attached to the bridge PUT 600, the bridge PUT 600 may be separated from the carrier substrate 114 (e.g., lifted along the Y-axis) to remove the semiconductor devices 112a and 112b from the carrier substrate 114.

Fig. 6B is a diagram illustrating placement and bonding of semiconductor devices using bridge PUT 600 according to one embodiment. The bridge PUT 600 with the attached semiconductor devices 112a and 112b is aligned with a target location on the target substrate 118. Contacts to the semiconductor devices 112a and 112b are placed on the contacts 602 of the target substrate 118.

The bonding process may include thermal compression bonding, wherein a force is exerted on the semiconductor devices 112a and 112b (e.g., along the Y-axis) toward the target substrate 118 by the bridge PUT 600. The applied force causes the bridge PUT 600 to be in a compressed state as shown in fig. 6B, wherein the abutment portion 316 and/or the tip 306 are compressed (e.g., reducing the undulation depth and/or tip length), and the bridge leg surface 320 of each bridge leg portion 302a and 302B contacts the target substrate 118. When compression is applied through the bridge PUT 600, heat may be applied (e.g., by the target table 120 holding the target substrate 118) to perform thermocompression bonding. Thermal compression bonding results in the contacts of the semiconductor devices 112a and 112b being bonded to the contacts 602 of the target substrate 118.

Contact between the bridge leg portions 302a and 302b and the target substrate 118 reduces relative lateral movement (in the X-Z plane) between the bridge PUT 600 and the target substrate 118 and holds the semiconductor devices 112a and 112b in place. The bridge leg portions 302a and 302b act as anchor points by adhering to the target substrate 118. To adhere the bridge leg portions 302a and 302b to the target substrate 118, a load (also referred to as a preload) is applied by the bridge PUT 600 to urge the bridge leg portions 302a and 302b against the target substrate 118 until the bridge leg surfaces 320 of the surfaces of the bridge leg portions 302a and 302b contact the target substrate 118 (bridge gap 0).

In the rest state shown in fig. 6A, the tip 306 extends under the bridge leg portions 302a and 302b to prevent contact with the carrier substrate 114 or semiconductor devices 112 that are not to be picked up. Otherwise, it is possible that the bridge leg portion 302a or 302b may inadvertently pick up the semiconductor device. In the compressed state shown in fig. 6B, the bridge leg portions 302 and 302B extend below the tip 306 to allow the bridge leg surface 320 to contact the target substrate 118.

Bridge PUT 600 defines a space 330 between bridge leg portion 302a and tip 306a, and another space 330 between bridge leg portion 302b and tip 306 b. The spaces 330 prevent contact or shearing of previously bonded semiconductor devices, such as semiconductor device 112 e. In some embodiments, the bridge depth may be greater than 30 μm, for example 60 μm.

FIG. 7 is a schematic diagram illustrating displacement features 702 of a bridge pick-up head 700 according to one embodiment. The bridge leg portion 302 of the bridge pick head 700 may include a displacement feature 702 defined at the bridge leg surface 320. The displacement feature 702 provides an optical determination of the force-displacement of the bridge pick head 700 during pick-up, placement, or bonding of the semiconductor device 112. In some embodiments, the displacement features 702 are discrete cones or hemispheres of 1 μm to multiple μm depth distributed on the one or more bridge leg portions 302. The displacement feature 702 provides an assessment of the deformation and stress-strain states. Based on the viscoelasticity of the material (e.g., PDMS) of the pickup head 700, the amount of pressure applied by the pickup head 700 may be determined based on the amount of deformation on the displacement features 702. For the displacement feature 702 in FIG. 7, different amounts of deformation are shown. In some embodiments, the bridge leg portion 302 may include an array of displacement features 702, with more compression of a displacement feature 702 at a particular location of the bridge leg portion 302 indicating more force-displacement at the corresponding location.

Fig. 8A, 8B, and 8C are diagrams illustrating manufacturing of a bridge PUT according to an embodiment. The bridge PUT can be manufactured using a 3D printing process followed by a dual molding step process. Referring to fig. 8A, a master structure 802 for a bridge pick-up head is printed on a substrate 804. The master structure 802 may be made of a photoresist material, such as a negative photoresist material. In some embodiments, a two-photon polymerization (2pp) printing process may be used to print the master structure 802 on the substrate 804.

Referring to fig. 8B, a first molding is performed to create a negative mold 806 from the master structure 802 on a substrate 808. The negative mold 806 may be made of PDMS. The negative mold 806 may be formed by molding PDMS with the master structure 802 and baking the molded PDMS in an oven. To facilitate safe stripping of the negative mold 806 from the master structure 802 after baking, the surface of the master structure 802 may be functionalized prior to molding. For example, an anti-stick silylation process can be applied to the master structure 802.

Referring to FIG. 8C, a second molding is performed to create a bridge pick head 822 on backing layer 824 and pick head substrate 826. The bridge pick-up head 822 may be made of PDMS. The bridge pick-up head 822 may be formed by molding PDMS with the negative mold 806 and baking the molded PDMS in an oven. To facilitate safe stripping of the negative mold 806 from the bridge pick-up head 822 after baking, the surface of the negative mold 806 may be functionalized prior to molding. For example, an anti-stick silylation process may be applied to the surface of the female mold 806.

FIG. 9 is a flow chart illustrating a method of manufacturing an electronic device according to one embodiment. The manufacturing method may be performed by the display assembly system 100 to manufacture a display. Here, the semiconductor device is an LED. In one example, the light emitting diodes are μ LEDs. The manufacturing method may include fewer steps or additional steps, and the steps may be performed in a different order.

One or more tips of the bridge PUT may be aligned with one or more selected semiconductor devices on the carrier substrate and then contacted with the selected semiconductor devices for attachment. The bridge PUT then picks up 905 the semiconductor device on the carrier substrate. A light contact can be used with little or no deformation of the bridge PUT. The tip of the bridge PUT extends beyond the bridge leg portions to define a bridge gap between each bridge leg portion and the carrier substrate. The bridge gap prevents contact with non-selected semiconductor devices on the carrier substrate.

In some embodiments, the bridge PUT is transparent to allow an imaging device to generate an image of the bridge PUT and an underlying carrier substrate using light transmitted through the bridge PUT. In some embodiments, the bridge PUT may include alignment marks to facilitate alignment.

The bridge PUT places 910 the semiconductor device on the target substrate. The bridge PUT with the one or more semiconductor devices attached thereto is aligned with one or more corresponding target locations on the target substrate. Contacts of the semiconductor device are placed on contacts of the target substrate.

In some embodiments, the bridge PUT is transparent to allow an imaging device to generate an image of the bridge PUT and an underlying target substrate using light transmitted through the bridge PUT. In some embodiments, the bridge PUT may include alignment marks to facilitate alignment.

The bridge PUT exerts 915 a force on the semiconductor device toward the target substrate to promote thermocompression bonding to bond the semiconductor device to the target substrate. The force may cause compression of the abutment portion and/or the tip of the bridge PUT, and may also cause the bridge leg surface of each bridge leg portion of the bridge PUT to contact the target substrate. The contact between the bridge leg portion and the target substrate holds the semiconductor device in place during bonding. In conjunction with applying force through the bridge PUT, heat is applied (e.g., by a target table holding a target substrate) to bond contacts of one or more semiconductor devices to contacts of the target substrate.

In some embodiments, the bridge PUT may include displacement features that provide an optical determination of the force-displacement of the bridge pick-up head during pick-up, placement, or bonding of the semiconductor device. The displacement feature facilitates fine control over the different amounts of force applied during the pick and place/bond steps.

The method of fig. 9 is explained with reference to a single bonding cycle in which one or more semiconductor devices are placed on a target substrate. The fabrication of the electronic device may be completed using multiple bonding cycles. For example, the electronic device may be a display device and the semiconductor device may be an LED. Multiple bonding cycles may be used to place different color LEDs on the target display substrate of the display device. In some embodiments, one or more bonding cycles may be used to place different color LEDs on different display substrates, and multiple arrays of display substrates are combined to form a display device.

The foregoing description of the embodiments has been presented for purposes of illustration; it is not intended to be exhaustive or to limit the patent to the precise form disclosed. One skilled in the relevant art will recognize that many modifications and variations are possible in light of the above disclosure.

The language used in the specification has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter. Accordingly, the scope of patented claims is not limited to the detailed description, but rather by any claims that may be filed based on the application on which it is based. Accordingly, the disclosure of the embodiments is intended to be illustrative, but not limiting, of the scope of the patent rights, which are set forth in the following claims.