WO2019200809A1

WO2019200809A1 - Semiconductor structure and method for forming same

Info

Publication number: WO2019200809A1
Application number: PCT/CN2018/102895
Authority: WO
Inventors: 武青青; 胡少坚; 朱建军
Original assignee: 上海集成电路研发中心有限公司
Priority date: 2018-04-16
Filing date: 2018-08-29
Publication date: 2019-10-24
Also published as: CN108493161A

Abstract

Provided by the present invention are a semiconductor structure and a method for forming same: when a semiconductor structure is heated or irradiated using light, an ester material layer and the carbon nanotubes cause a flexible substrate to bend since the thermal expansion coefficient of the ester material layer is greater than the thermal expansion coefficient of the flexible substrate; furthermore, the ester material layer fills gaps between the flexible substrate and the carbon nanotubes as well as gaps between each carbon nanotube, the ester material layer expands so that the distance between the carbon nanotubes increases, and the carbon nanotubes restrict the expansion of the ester material layer so that the semiconductor structure bends; when not heated or irradiated using light, the semiconductor structure returns to being flat. The semiconductor structure has a small size, has a simple structure and is convenient to control. Moreover, the semiconductor structure may be applied in various devices, such as switches, sensors, and the like.

Description

Semiconductor structure and method of forming same

Technical field

The present invention relates to the field of semiconductor fabrication, and more particularly to a semiconductor structure and a method of forming the same.

technical background

In recent years, flexible, flexible and lightweight electronic devices and devices have received widespread attention, but the devices currently used in these flexible electronic devices are mostly traditional block hard devices, and the preparation steps are complicated to some extent. Limiting the flexibility of electronic devices limits their development in wearable electronics and related fields. Therefore, the prior art has yet to be improved and developed.

Summary of invention

It is an object of the present invention to provide a semiconductor structure and method of forming the same to improve the performance of existing flexible electronic devices.

In order to achieve the above object, the present invention provides a semiconductor structure including the semiconductor structure

Flexible substrate

a layer of an ester material, the layer of ester material being disposed on the flexible substrate, and a coefficient of thermal expansion of the layer of the ester material is greater than a coefficient of thermal expansion of the flexible substrate;

Orienting a carbon nanotube film, the aligned carbon nanotube film is embedded in the ester material layer, the oriented carbon nanotube film has a plurality of aligned carbon nanotubes, and a gap between each of the carbon nanotubes is The layer of ester material is filled.

Optionally, a layer of conductive material is disposed on a side of the flexible substrate facing away from the aligned carbon nanotube film.

Optionally, the material of the conductive material layer comprises a conductive silver paste or a composite material of carbon nanotubes/silver nanowires.

Optionally, the material of the flexible substrate comprises polyimide and/or polyethylene terephthalate.

Optionally, the material of the ester material layer comprises one or more of paraffin wax, glyceryl monostearate, aluminate and polyoxyl stearate.

The invention also provides a method for forming a semiconductor structure, characterized in that the method for forming the semiconductor structure comprises:

Providing the flexible substrate;

Forming the layer of ester material on the flexible substrate;

Laying the aligned carbon nanotube film on the ester material layer and heating, embedding the aligned carbon nanotube film in the ester material layer, and filling the carbon nanotube film with each of the carbon nanotube layers The gap between them.

Optionally, after the heating the layer of the ester material, the method for forming the semiconductor structure further comprises: forming the conductive material layer on a side of the flexible substrate facing away from the aligned carbon nanotube film to form a composite structure Floor.

Optionally, after the forming the conductive material layer, the method for forming the semiconductor structure further comprises: cutting the composite structure layer into a square shape.

Optionally, the layer of ester material and the layer of conductive material are formed by a spin coating or coating process.

Optionally, the aligned carbon nanotube film is prepared using a spinnable carbon nanotube array.

In the semiconductor structure and the method of forming the same provided by the present invention, when the semiconductor structure is heated or irradiated with light, since the coefficient of thermal expansion of the layer of the ester material is larger than the coefficient of thermal expansion of the flexible substrate, the layer of the ester material and the carbon nanotube can promote flexibility. The substrate is bent; further, the layer of the ester material is filled in the gap between each of the carbon nanotubes, the layer of the ester material is expanded to increase the pitch of the carbon nanotubes, and the carbon nanotubes have a binding effect on the expansion of the layer of the ester material, so that The semiconductor structure is bent, and the semiconductor structure is flattened when it is not heated or exposed to light. The semiconductor structure provided by the invention has the advantages of small volume, simple structure and convenient control, and the semiconductor structure can be applied to various devices such as switches and sensors, and can also adjust the orientation of the carbon nanotubes and the aspect ratio of the semiconductor structure. And the thickness of the structural layer to adjust the bending direction, bending angle, and amount of bending of the semiconductor structure.

DRAWINGS

FIG. 1 is a schematic diagram of a semiconductor structure according to an embodiment of the present invention;

FIG. 2 is a diagram showing the force analysis of the orientation of the carbon nanotubes in the direction of a according to an embodiment of the present invention.

3 is a schematic view showing an upward bending of a semiconductor structure according to an embodiment of the present invention;

4 is a schematic diagram of a semiconductor structure connecting a first conductor and a second conductor according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of a semiconductor structure disconnecting a first conductor and a second conductor according to an embodiment of the present invention;

FIG. 6 is a diagram showing the force analysis of the orientation of the carbon nanotubes in the b direction according to an embodiment of the present invention.

FIG. 7 is a schematic diagram of a semiconductor structure bent downward according to an embodiment of the present invention; FIG.

FIG. 8 is still another schematic diagram of a semiconductor structure connecting a first conductor and a second conductor according to an embodiment of the present invention;

FIG. 9 is still another schematic diagram of a semiconductor structure disconnecting a first conductor and a second conductor according to an embodiment of the present invention;

FIG. 10 is a diagram showing the force analysis of the orientation of the carbon nanotubes in the c direction according to an embodiment of the present invention.

FIG. 11 is a schematic view showing a semiconductor structure in a spiral shape according to an embodiment of the present invention; FIG.

FIG. 12 is a schematic diagram of a semiconductor structure connecting two cylindrical conductors according to an embodiment of the present invention; FIG.

FIG. 13 is still another schematic diagram of a semiconductor structure connecting two cylindrical conductors according to an embodiment of the present invention; FIG.

FIG. 14 is a schematic diagram of a semiconductor structure disconnecting two cylindrical conductors according to an embodiment of the present invention; FIG.

FIG. 15 is still another schematic diagram of a semiconductor structure disconnecting two cylindrical conductors according to an embodiment of the present invention; FIG.

16 is a flowchart of a method for forming a semiconductor structure according to an embodiment of the present invention.

17-18 are schematic diagrams showing a portion of a semiconductor structure formed by the method for forming a semiconductor structure according to an embodiment of the present invention.

Wherein, 1-flexible substrate, 2-oriented carbon nanotube film, 21-carbon nanotube, 3-ester material layer, 4-conductive material layer, 5-first conductor, 6-second conductor, aa direction, bb Direction, cc direction, zz direction, F1-first force, F2-second force

Summary of the invention

Specific embodiments of the present invention will be described in more detail below with reference to the drawings. Advantages and features of the present invention will be apparent from the description and appended claims. It should be noted that the drawings are in a very simplified form and all use non-precise proportions, and are only for convenience and clarity to assist the purpose of the embodiments of the present invention.

Please refer to FIG. 1 , which is a schematic diagram of a semiconductor structure provided by the embodiment. As shown in FIG. 1, the semiconductor structure comprises a flexible substrate 1, an oriented carbon nanotube film 2, and an ester material layer 3, the ester material layer 3 is disposed on the flexible substrate 1, and the thermal expansion of the ester material layer 3 The coefficient is greater than the coefficient of thermal expansion of the flexible substrate 1. The aligned carbon nanotube film 2 is embedded in the ester material layer 3, and the aligned carbon nanotube film 2 has a plurality of aligned carbon nanotubes 21, and a gap between each of the carbon nanotubes 21 is layered by the ester material layer. 3 fills.

Wherein, when the semiconductor structure is heated or irradiated with light, the ester material layer 3 and the carbon nanotubes 21 can promote the flexible substrate because the coefficient of thermal expansion of the ester material layer 3 is greater than the thermal expansion coefficient of the flexible substrate 1. 1 is bent, further, the ester material layer 3 is filled in a gap between the flexible substrate 1 and the carbon nanotube 21 and a gap between each of the carbon nanotubes 21, and the ester material layer 3 is expanded to The pitch of the carbon nanotubes 21 is increased, and the carbon nanotubes 21 have a binding effect on the expansion of the ester material layer 3, causing the semiconductor structure to be bent, and the semiconductor structure is restored to be flat when it is not heated or exposed to light. That is to say, the semiconductor provided by the present invention is small in size, simple in structure, convenient in control, and can be applied to various devices such as switches and sensors, and can also adjust the orientation of the carbon nanotubes 21, the aspect ratio of the semiconductor structure, and The thickness of each structural layer is used to adjust the bending direction, bending angle, and amount of bending of the semiconductor structure.

In the embodiment of the present invention, the material of the flexible substrate 1 may select a flexible material having a small thermal expansion coefficient (less than 3*10 ^-5 K ^-1 ) and high temperature resistance (>100 ° C), such as polyimide or poly pair. Ethylene phthalate or the like, the flexible substrate 1 has a characteristic of a flexible material which can be bent and deformed. Referring to FIG. 1 , an oriented carbon nanotube film 2 is disposed on the flexible substrate 1 , and the aligned carbon nanotube film 2 has a plurality of carbon nanotubes 21 distributed in an array, and the orientation of each of the carbon nanotubes 21 is uniform. Each of the carbon nanotubes 21 is an anisotropic material having a high longitudinal modulus and a low transverse modulus. The thermal expansion coefficient of the ester material layer 3 can be much larger than the thermal expansion coefficient of the flexible substrate 1, further enhancing the expansion difference between the ester material layer 3 and the flexible substrate 1 to increase the response speed of the semiconductor structure, for example, The material of the ester material layer 3 may be one or more of paraffin wax, glyceryl monostearate, aluminate and polyoxyl stearate. In this embodiment, the material of the ester material layer 3 For paraffin wax, paraffin has good adhesion to the flexible substrate 1, and has a high coefficient of thermal expansion (up to 3K ^-1 ), which can generate a great difference from the expansion of the flexible substrate 1 to make the sensitivity of the semiconductor structure. increase.

When the semiconductor structure is not heated or exposed to light, the semiconductor structure is an elongated sheet. When the semiconductor structure is heated or exposed to light, the ester material layer 3 has a large expansion coefficient when the ester material is large. When the layer 3 is thermally expanded, a force perpendicular to the orientation direction of the carbon nanotubes 21 is generated to make the gap between the carbon nanotubes 21 large, and the carbon nanotubes 21 have a high longitudinal modulus and a low a transverse modulus anisotropic material having a certain binding effect on the expansion of the ester material layer 3, thereby generating a force along the orientation direction of the carbon nanotubes 21 and contracting inward, which Two forces cause the semiconductor structure to bend.

In the embodiment of the present invention, the bottom of the flexible substrate 1 may further be provided with a layer 4 of conductive material, which may serve as a conductive electrode, the thermal expansion coefficient of the conductive material layer 4 and the thermal expansion of the flexible substrate 1. The difference in coefficient can be as small as possible so that the thermal expansion coefficient of the conductive material layer 4 and the flexible substrate 1 is close to ensure that warpage or crack does not occur between the conductive material layer 4 and the flexible substrate 1 due to the difference in expansion. Further, the conductive material layer 4 may be a material that is easy to coat and has good adhesion to the flexible substrate 1. For example, the conductive material layer 4 may be a conductive silver paste or a carbon nanotube/silver nanowire. The composite material, of course, the conductive material layer 4 may also be other conductive materials, which are not limited in the present invention.

Specifically, referring to FIG. 2 to FIG. 3, the orientation of the carbon nanotubes 21 is a direction (the a direction is a horizontal direction), and when the semiconductor structure is exposed to light or heated, the layer 3 of the ester material expands to the carbon. The pitch of the nanotubes 21 is increased to generate a first force F1 perpendicular to the a direction, and the carbon nanotubes 21 have a binding effect on the ester material layer 3 in the orientation direction thereof, resulting in a second along the a direction. The force F2, as shown in FIG. 2, because the dimension of the semiconductor structure along the a direction is larger than the dimension perpendicular to the a direction, the second force F2 is greater than the first force F1, so that the semiconductor structure is upward. (the opposite direction in the z direction in Fig. 3) is curved, as shown in Fig. 3.

One end of the semiconductor structure of this type is disposed on the first conductor 5, the conductive material layer 4 of the semiconductor structure is in contact with the first conductor 5, and the other end is disposed on the second conductor 6, when the semiconductor structure is not heated or not When illuminated, the semiconductor structure is in a flat state, and the first conductor 5 is in communication with the second conductor 6 (as shown in FIG. 4). When the semiconductor structure is heated or exposed to light, the semiconductor structure is bent upward to disconnect the first conductor 5 from the second conductor 6, as shown in FIG.

Next, referring to FIGS. 6-7, the carbon nanotubes 21 are oriented in the b direction (the b direction is perpendicular to the a direction), and when the semiconductor structure is exposed to light or heated, the layer of the ester material 3 is expanded to The pitch of the carbon nanotubes 21 is increased to generate a first force F1 perpendicular to the b direction, and the carbon nanotubes 21 have a binding effect on the ester material layer 3 in the orientation direction thereof, resulting in the second direction along the b direction. The second force F2, as shown in FIG. 6, because the dimension of the semiconductor structure along the b direction is smaller than the dimension perpendicular to the b direction, the second force F2 is smaller than the first force F1, so that the semiconductor structure Bending downward (in the z direction in Fig. 7), as shown in Fig. 7.

One end of the semiconductor structure of this type is disposed on the first conductor 5, the conductive material layer 4 of the semiconductor structure is in contact with the first conductor 5, and the other end is disposed above the second conductor 6, when the semiconductor structure is not The semiconductor structure is flat when heated or unlit (as shown in Figure 8). When the semiconductor structure is heated or exposed to light, the semiconductor structure is bent downward to connect the first conductor 5 to the second conductor 6, as shown in FIG.

Referring to FIG. 10, the carbon nanotubes 21 are oriented in the c direction (the c direction forms a 45 degree angle with the a direction and the b direction). When the semiconductor structure is exposed to light or heated, the ester material layer 3 The expansion increases the pitch of the carbon nanotubes 21 to produce a first force F1 perpendicular to the c direction, and the carbon nanotubes 21 have a binding effect on the orientation direction of the ester material layer 3 along the c The second force F2 of the direction is as shown in FIG. 10, the second force F2 is smaller than the first force F1, and the semiconductor structure is spirally curved, as shown in FIG.

When the first conductor 5 and the second conductor 6 are larger-sized pillars, the semiconductor structure can be attached to the sidewalls of the first conductor 5 and the second conductor 6, as shown in FIG. 12-13. When the semiconductor structure is not heated or exposed to light, the semiconductor structure is in a flat state, the first conductor 5 is in communication with the second conductor 6, and when the semiconductor structure is heated or exposed to light, the semiconductor structure is bent outward The first conductor 5 is disconnected from the second conductor 6, as shown in FIGS. 14-15.

Further, by adjusting the orientation of the carbon nanotubes 21, the aspect ratio of the semiconductor structure, and the thickness of each layer of material, the bending direction, the bending angle, and the amount of bending of the semiconductor structure can be controlled, and at the same time, the aligned carbon nanotubes 21 can be absorbed. Part of visible light and infrared light are converted into thermal energy, which further enhances the difference in expansion between the ester material layer 3 and the flexible substrate 1, and accelerates the light response speed of the semiconductor structure.

Referring to FIG. 1 and FIG. 16 to FIG. 18, a method for forming a semiconductor structure according to an embodiment of the present invention includes:

S1: providing the flexible substrate 1;

S2: forming the ester material layer 3 on the flexible substrate 1;

S3: laying the aligned carbon nanotube film 2 on the ester material layer 3 and heating, embedding the aligned carbon nanotube film 2 in the ester material layer 3, and filling the ester material layer 3 with each of the carbon nanometers The gap between the tubes.

First, referring to FIG. 17, the flexible substrate 1 is provided, and the flexible substrate 1 is fixed on a flat glass plate, and then the flexible substrate 1 can be annealed to keep the flexible substrate 1 isotropic. In this embodiment, the material of the flexible substrate 1 is polyimide, which can withstand high temperature up to 400 ° C, high insulation, linear thermal expansion coefficient as low as 2.8*10 ^-5 K ^-1 , and has high resistance. Irradiation performance, excellent mechanical properties. Next, paraffin particles are sprinkled on the flexible substrate 1 and heated, and the heating temperature may be between 60 ° C and 100 ° C. After the paraffin wax is melted, a spin coating or coating process is performed, and after cooling, an ester material layer is formed. 3. Alternatively, the ester material layer 3 may be other ester materials having similar properties to paraffin wax.

Next, the aligned carbon nanotube film 2 is pulled out through the spinnable carbon nanotube array, and the aligned carbon nanotube film 2 is deposited on the ester material layer 3, and the ester material layer 3 has a thickness of 100 nm to 500 nm. between. Next, as shown in FIG. 18, the ester material layer 3 is heated to a temperature of from 60 ° C to 100 ° C to be melted and uniformly entered into the gap between the carbon nanotubes 21, and the flexible substrate 1 and the carbon nanotubes 21 are filled. The gap between the ester material layer 3 and the carbon nanotube film is in close contact.

Finally, a conductive material is coated on the lower surface of the flexible substrate 1 to form a conductive material layer 4, which is used as an electrode and then cut to form a strip-shaped semiconductor structure, as shown in FIG. It can be understood that the semiconductor structure may not form the conductive material layer 4 only as a strain structure in a device. Further, when the orientation direction of the carbon nanotubes 21 is the length direction (a direction) of the elongated semiconductor structure, when the semiconductor structure is heated or exposed to light, upward bending occurs; when not heated or exposed to light, The semiconductor structure is restored to be flat; when the orientation direction of the carbon nanotubes 21 is the width direction (b direction) of the semiconductor structure, when the semiconductor structure is heated or exposed to light, downward bending occurs; when not heated or not The semiconductor structure is flattened when illuminated.

In summary, in the semiconductor structure and the method for forming the same according to the embodiments of the present invention, when the semiconductor structure is heated or exposed to light, the semiconductor structure is heated because the thermal expansion coefficient of the ester material layer is greater than the thermal expansion coefficient of the flexible substrate. Or, when irradiated with light, the layer of the ester material and the carbon nanotube can cause the flexible substrate to bend, and further, the layer of the ester material fills a gap between the flexible substrate and the carbon nanotube and each of the carbon nano a gap between the tubes, the expansion of the layer of the ester material increases the spacing of the carbon nanotubes, and the carbon nanotubes have a binding effect on the expansion of the layer of the ester material, causing the semiconductor structure to bend when not exposed to heat or illumination. When the semiconductor structure is restored to a flat state, the semiconductor structure provided by the invention has small volume, simple structure, convenient control, and can be applied to various devices such as switches and sensors, and can also adjust the orientation of the carbon nanotubes and the semiconductor structure. The aspect ratio and the thickness of the structural layer to adjust the bending direction, bending angle and bending amount of the semiconductor structure

The above is only a preferred embodiment of the present invention and does not impose any limitation on the present invention. Any changes in the technical solutions and technical contents disclosed in the present invention may be made by those skilled in the art without departing from the technical scope of the present invention. The content is still within the scope of protection of the present invention.

Claims

A semiconductor structure, characterized in that the semiconductor structure comprises

Flexible substrate

a layer of an ester material, the layer of ester material being disposed on the flexible substrate, and a coefficient of thermal expansion of the layer of the ester material is greater than a coefficient of thermal expansion of the flexible substrate;

Orienting a carbon nanotube film, the aligned carbon nanotube film is embedded in the ester material layer, the oriented carbon nanotube film has a plurality of aligned carbon nanotubes, and a gap between each of the carbon nanotubes is The layer of ester material is filled.
The semiconductor structure of claim 1 wherein a layer of conductive material is disposed on a side of said flexible substrate facing away from said aligned carbon nanotube film.
The semiconductor structure according to claim 2, wherein the material of the conductive material layer comprises a conductive silver paste or a composite material of carbon nanotubes/silver nanowires.
The semiconductor structure of claim 1 wherein the material of the flexible substrate comprises polyimide and/or polyethylene terephthalate.
The semiconductor structure according to claim 1 or 4, wherein the material of the ester material layer comprises one of paraffin wax, glyceryl monostearate, aluminate and polyoxyl stearate or A variety.
A method of forming a semiconductor structure according to any one of claims 1 to 5, wherein the method of forming the semiconductor structure comprises:

Providing the flexible substrate;

Forming the layer of ester material on the flexible substrate;

Laying the aligned carbon nanotube film on the ester material layer and heating, embedding the aligned carbon nanotube film in the ester material layer, and filling the carbon nanotube film with each of the carbon nanotube layers The gap between them.
The method of forming a semiconductor structure according to claim 6, wherein after the heating the layer of the ester material, the method for forming the semiconductor structure further comprises:

The conductive material layer is formed on a side of the flexible substrate facing away from the aligned carbon nanotube film to form a composite structural layer.
The method of forming a semiconductor structure according to claim 7, wherein after the forming the conductive material layer, the method for forming the semiconductor structure further comprises:

The composite structural layer is cut into square shapes.
A method of forming a semiconductor structure according to claim 7, wherein said ester material layer and said conductive material layer are formed by a spin coating or coating process.
The method of forming a semiconductor structure according to claim 6, wherein the aligned carbon nanotube film is prepared using a spinnable carbon nanotube array.