KR102723643B1 - Semiconductor device and method for fabricating the same - Google Patents

Abstract

The present disclosure relates to a semiconductor device and a method for manufacturing the same. According to the method for manufacturing the same, an amorphous carbon layer is formed on a starting substrate including a single crystal layer of a group III nitride compound on an upper surface thereof, a semiconductor layer of the group III nitride compound is formed and grown on the amorphous carbon layer, and then the semiconductor layer is released from the starting substrate.

Description

SEMICONDUCTOR DEVICE AND METHOD FOR FABRICATING THE SAME

The present disclosure relates to a semiconductor device, and more particularly, to a group III nitride compound semiconductor device, and more particularly, to a gallium nitride (GaN) semiconductor device and a method for manufacturing the same.

Group III nitride compound semiconductors, especially gallium nitride (GaN) semiconductors, have the advantages of high breakdown voltage and high band gap, which are advantageous for high power output, and high carrier concentration and high electron mobility, which result in a high field saturation speed, while low carrier scattering, which is advantageous for high-speed switching (i.e., high-frequency operation).

Since these semiconductor devices generate a lot of heat, they require a combination with a heat spreader to ensure that the devices remain in a temperature range where they can operate stably. One well-known conventional approach is to use a GaN layer disposed on a silicon carbide (SiC) substrate configured to manage heat instead of Si (silicon; silicon; silicon) which has a thermal conductivity of only about 149 W/m K (e.g., U.S. Patent No. 9,111,750). In this manner, a buffer layer using AlN, GaN, etc. is manufactured on a Si or SiC substrate, and then a GaN epilayer as an active layer (for manufacturing electronic devices such as AlGaN/GaN HFET (high electron mobility transistor) devices) is placed on the buffer layer.

However, for high-frequency, high-power RF devices made of gallium nitride, the thermal conductivity of 350 to 400 W/m K of the SiC substrate was not sufficient to withstand the thermal load, so attempts were made to use materials with the highest thermal conductivity, such as diamond.

For example, a technique for placing a GaN device on a diamond substrate, as disclosed in U.S. Patent Nos. 7,595,507 and 9,359,693, is to attach a GaN epilayer on a synthetic diamond substrate, such as CVD polycrystalline diamond. However, introducing CVD diamond in this manner still has the problem of a bow caused by a material lattice mismatch and a difference in the thermal expansion coefficients of the GaN layer and the diamond layer.

US 9111750 B US 9359693 B

The present disclosure aims to provide a novel method for manufacturing a semiconductor device using a CVD diamond substrate that can effectively remove heat generated by a GaN semiconductor, while overcoming problems such as lattice mismatch and bow that occur in conventional technologies.

Specifically, the present disclosure provides a method of forming a GaN device on a high-quality self-standing GaN substrate or bulk GaN substrate, and then separating the GaN device and bonding it to a diamond substrate to solve the shortcomings of the above-mentioned conventional technologies.

The characteristic configuration of the present invention to achieve the purpose of the present invention as described above and to realize the characteristic effects of the present invention described below is as follows.

According to one aspect of the present disclosure, a method for manufacturing a semiconductor device is provided, the method comprising: forming an amorphous carbon layer on a starting substrate including a single crystal layer of a group III nitride compound on an upper surface thereof; forming and growing a semiconductor layer of the group III nitride compound on the amorphous carbon layer; and releasing the semiconductor layer from the starting substrate.

Preferably, the method further comprises a step of attaching the separated semiconductor layer to a receiving substrate.

More preferably, the receiving substrate is a diamond substrate. The diamond substrate may be composed of CVD polycrystalline diamond.

Advantageously, the amorphous carbon layer is formed on the starting substrate by organometallic chemical vapor deposition. The amorphous carbon layer may be a monolayer amorphous carbon layer.

In one embodiment, the separating step comprises: depositing a stressor layer on the semiconductor layer; and separating the semiconductor layer and the stressor layer from the starting substrate.

Preferably, the stress-generating layer is a metal layer.

Advantageously, the tape is a flexible tape.

More specifically, in the separation step, a roller having an adhesive material on its surface is rolled over the stress-generating layer, so that the semiconductor layer and the stress-generating layer can be separated from the starting substrate by the adhesive force of the adhesive material.

Preferably, the radius of curvature of the roller may be equal to or greater than one time the longest dimension of the starting substrate.

Alternatively, the separating step may further include a step of attaching a tape over the stress-generating layer, and in the separating step, the semiconductor layer and the stress-generating layer may be separated from the starting substrate using the tape.

In one embodiment, the Group III nitride compound is Al _x Ga _1-x N, where x is a real number greater than or equal to 0 and less than or equal to 1. Here, Al _x Ga _1-x N may include gallium nitride and aluminum nitride.

According to another aspect of the present disclosure, a semiconductor device is provided, comprising: a starting substrate including a single crystal layer of a group III nitride compound on an upper surface thereof; an amorphous carbon layer formed on the starting substrate; and a semiconductor layer of a group III nitride compound formed on the amorphous carbon layer.

According to another aspect of the present disclosure, a semiconductor device is provided, comprising: a diamond substrate; and a semiconductor layer of a group III nitride compound attached on the diamond substrate, the semiconductor layer being formed on an amorphous carbon layer and then separated from the amorphous carbon layer.

In one embodiment, the semiconductor layer comprises a region where the residue from the amorphous carbon layer is deformed by at least one of heat and pressure.

According to the semiconductor device manufacturing method of the present disclosure, a low-defect, high-quality GaN device with low dislocation density and reduced bow can be manufactured by forming the GaN device on a high-quality self-standing GaN substrate or bulk GaN substrate, thereby reducing heat generation of the device and extending its lifespan, thereby improving reliability.

In addition, according to the present disclosure, the excellent thermal conductivity of a diamond substrate can be effectively utilized, thereby having the effect of improving the reliability of a conventional gallium nitride (GaN-on-diamond) device on a diamond substrate.

In order to understand the present invention, examples will be described with reference to the accompanying drawings to show a process in which the method of the present disclosure is actually performed. However, these are only non-limiting examples, and it should be understood that a person having ordinary knowledge in the technical field to which the present disclosure belongs (hereinafter referred to as “ordinary skilled in the art”) can obtain other drawings based on these drawings without additional efforts leading to another invention.
FIG. 1 is a diagram illustrating main steps of a method for manufacturing a semiconductor device according to the present disclosure.
Figure 2 is a perspective view of a semiconductor device conceptually illustrating each step of Figure 1.

The detailed description of the principle of the semiconductor device and the semiconductor device manufacturing method according to the present disclosure described below refers to the accompanying drawings, which illustrate specific embodiments in which the present disclosure can be implemented, in order to clarify the objectives, technical solutions, and advantages of the invention disclosed in the present disclosure. In the description with reference to the accompanying drawings, the same components are given the same reference numerals regardless of the drawing numbers, and redundant descriptions thereof will be omitted. It will be understood that the semiconductor structure according to the present disclosure does not have the same length ratio as shown in the drawings, and the dimensions of each part of the drawings are only shown for the purpose of explanation and do not limit the scope of the present disclosure. For example, the dimensions of some of the elements shown in the drawings are for the purpose of helping the understanding of various embodiments. In addition, the description and drawings do not mean that they are in the order described. A person skilled in the art will understand that the operations and/or steps described or illustrated in a specific order may not require any special limitation to such order.

Specific structural or functional descriptions of the embodiments are disclosed for illustrative purposes only and may be modified and implemented in various forms. Accordingly, the embodiments are not limited to a specific disclosed form, and the scope of the present disclosure includes modifications, equivalents, or alternatives included in the technical idea.

Although the terms first or second may be used to describe various components, such terms should be construed only for the purpose of distinguishing one component from another. For example, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component.

When it is said that a component is "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may also be other components present in between. Also, when it is said that a component is "on" another component, it should be understood that it may be "directly above" that other component, but that there may also be other components present in between.

Singular expressions include plural expressions unless the context clearly indicates otherwise. In this disclosure, the terms "comprises" or "has" and the like are intended to specify the presence of a described feature, number, step, operation, component, part, or combination thereof, but should be understood to not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning they have in the context of the relevant art, and will not be interpreted in an idealized or overly formal sense unless explicitly defined in this disclosure.

In the present disclosure, 'epitaxy' or 'epitaxial growth' refers to a phenomenon in which a oriented crystal film grows on a crystal base, wherein the crystal of the base may be the same as the material being grown or may be a different material having a similar lattice structure. It is well known to those skilled in the art that methods such as MOCVD (metalorganic chemical vapour deposition), MBE (molecular beam epitaxy), and ALD (atomic layer deposition) can be applied for the epitaxial growth of the GaN device described in the present disclosure.

Additionally, in the present disclosure, the terms 'diamond substrate' are used interchangeably, and for example, a person skilled in the art will understand that such a diamond substrate may include a polycrystalline diamond substrate having a predetermined diameter (e.g., 4 inches or 100 mm or more).

In the present disclosure, the term "semiconductor layer" is a term that includes a semiconductor layer structure as an active layer of semiconductor necessary for implementing optoelectronic devices such as high-frequency transistors, high-voltage switches, Schottky diodes, and/or laser diodes, LEDs, and other electronic devices.

For example, the semiconductor layer can be formed of multiple layers, for example, a GaN semiconductor layer belonging to a group III nitride compound and an AlGaN semiconductor layer can be formed together to form an active device such as an AlGaN/GaN HFET.

In this disclosure, the term "layer" refers to a material that is disposed in a continuous or discontinuous manner over at least a portion of an underlying surface. Furthermore, the term "layer" does not necessarily imply that the disposed material has a constant thickness. The disposed material may have either a constant thickness or a varying thickness. Furthermore, any "layer" used in this disclosure may refer to a single layer or multiple layers, unless the context clearly indicates otherwise. In this disclosure, the expressions "disposed on" or "disposed over" and "disposed between" mean, unless otherwise indicated, that they are disposed in direct contact with each other or indirectly so disposed through other intervening layers. Furthermore, "on" and "over" merely indicate relative positions between layers/devices, which may be viewed differently depending on the viewing perspective of the observer. Also, "formed on ~" has a broad meaning, and when a layer is formed on another layer, it does not imply direct physical contact with that other layer. For example, when it is said that "a semiconductor layer is formed on a substrate," there may be one or more layers interposed between the semiconductor layer and the substrate. On the other hand, "formed directly on ~" implies direct physical contact.

The present invention encompasses all possible combinations of the embodiments set forth in this disclosure. It should be understood that the various embodiments of the present invention are different from each other, but are not necessarily mutually exclusive. For example, specific shapes, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the present invention with respect to one embodiment. That is, although the embodiments of the present invention are described with reference to drawings of semiconductor devices illustrating the concept of ideal embodiments of the present invention, they should not be considered limited to the specific region shapes of the structures as illustrated, and various modifications may be included as shapes of the resulting products by manufacturing. The regions illustrated in the drawings are conceptually illustrated in terms of their characteristics and shapes, and are not intended to depict the exact shapes of the structures, regions, or to limit the scope of the present invention. For example, regions illustrated as rectangular blocks in the drawings may often be tapered, curved, or rounded.

It should be understood that the location or arrangement of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the present invention. Accordingly, the following detailed description is not intended to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims, along with the full scope equivalent to which such claims are entitled, if properly described.

Unless otherwise indicated in this disclosure or clearly contradicted by context, items referred to in the singular include the plural unless the context otherwise requires. In addition, in describing the present invention, if a specific description of a related known configuration or function is determined to be related to materials, processes, etc. that are well known to those skilled in the art of semiconductor technology and may obscure the gist of the present invention, an excessively detailed description thereof will be omitted.

Hereinafter, in order to enable those skilled in the art to easily practice the present invention, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

Referring to FIG. 1, main steps of a method for manufacturing a semiconductor device according to the present disclosure are illustrated. Each step corresponds to a perspective view of the semiconductor device illustrated in FIG. 2.

As shown in FIGS. 1 and 2, the semiconductor device manufacturing method of the present disclosure first includes a step (S100) of forming an amorphous carbon (200) layer on a starting substrate (100) including a single crystal layer of a group III nitride compound on an upper surface.

Here, the Group III nitride compound is Al _x Ga _1-x N, where x is a real number greater than or equal to 0 and less than or equal to 1. That is, Al _x Ga _1-x N may include gallium nitride and aluminum nitride.

Therefore, for example, the starting substrate (100) may be a GaN single crystal layer formed on a Si or SiC substrate (GaN on Si/SiC), a free-standing GaN substrate, or a bulk GaN substrate, and these may be collectively referred to as a GaN starting substrate.

The top surface of the GaN starting substrate can be a polar surface, i.e., the surface normal of the top surface can have a crystallographic orientation in the +c direction or the -c direction or a crystallographic orientation that deviates from it by an angle of 5 degrees or less.

For example, if the top surface of the GaN starting substrate is the Ga-plane, the opposite surface may be the N-plane, and if the top surface of the GaN starting substrate is the N-plane, the opposite surface may be the Ga-plane.

In addition, the amorphous carbon layer (200) may be composed of a single layer of amorphous carbon, but is not limited thereto, and an amorphous carbon layer composed of two to three layers is also included.

For example, the amorphous carbon layer (200) may be formed on the starting substrate (100) by deposition such as CVD, MBE, ALD, etc., particularly metal-organic chemical vapor deposition (MOCVD), but is not limited thereto.

Next, the method for manufacturing a semiconductor device of the present disclosure further includes a step (S200) of forming and growing a semiconductor layer (300) of a group III nitride compound on the amorphous carbon layer (200).

For example, the formation and growth of the semiconductor layer (300) can be performed by an epitaxy process.

Accordingly, in step (S200), the semiconductor device includes a starting substrate (100) including a single crystal layer of a group III nitride compound on an upper surface, an amorphous carbon layer (200) formed on the starting substrate, and a semiconductor layer (300) of a group III nitride compound formed on the amorphous carbon layer (200).

Unlike a pure graphene layer, a single-layer amorphous carbon layer (200) does not block the semiconductor layer (300) from growing with the same crystal structure (e.g., hexagonal crystal structure) as the single-crystal layer of the starting substrate (100) (and the amorphous carbon layer (200)) when the semiconductor layer (300) is grown on the starting substrate (100). That is, even if a single-layer amorphous carbon layer (200) is applied to the starting substrate (100), a semiconductor layer (300) having the same crystal structure as the group-III nitride compound of the starting substrate (100) can be easily grown on the single-layer amorphous carbon layer.

However, a person skilled in the art will be able to understand that even if the amorphous carbon layer (200) is composed of 2 to 3 layers rather than a single layer, there is an effect similar to that of a single-layer amorphous carbon.

For example, when the upper surface of the GaN starting substrate (100) is the Ga-plane, the lower surface of the semiconductor layer (300) becomes the N-plane and the upper surface becomes the Ga-plane due to the growth of the semiconductor layer (300) according to its polarity. When the upper surface of the GaN starting substrate (100) is the N-plane, the lower surface of the semiconductor layer (300) becomes the Ga-plane and the upper surface becomes the N-plane according to its polarity.

Continuing with reference to FIGS. 1 and 2, the semiconductor device manufacturing method of the present disclosure further includes a separation step (S300) of separating (releasing) the semiconductor layer (300) from the starting substrate (100) by separating the upper and lower portions of the amorphous carbon layer (200).

In one embodiment, the separation step (S300) may be performed by depositing a stressor layer (400) on a semiconductor layer (300) (S320) and detaching the semiconductor layer (300) and the stressor layer (400) from the starting substrate (100) (S360).

Here, the stressor layer refers to a material layer that generates stress to facilitate separation between the starting substrate (100) and the semiconductor layer (300) and induces and propagates a crack or fracture of the amorphous carbon layer (200) located under the semiconductor layer (300). The stressor layer may be composed of, for example, a high-stress metal film, for example, a nickel (Ni) film, and may be formed on the semiconductor layer (300) by, for example, deposition.

Specifically, in the separation step (S300), particularly in the step (S360), a roller (500) having an adhesive material (510) on its surface is rolled over the stress-generating layer (400), so that the semiconductor layer (300) and the stress-generating layer (400) can be separated from the starting substrate (100) by the adhesive force of the adhesive material (510).

Preferably, the radius of curvature of the roller (500) may be equal to or greater than one time the longest dimension of the starting substrate (100) so that the semiconductor layer (300) is not damaged by the stress applied by the roller (500) to the semiconductor layer (300) and the stress-generating layer (400).

Here, the longest dimension refers to the largest value that the distance from one point in an object to another point can have.

Alternatively, the separation step (S300) may further include a step (S340; not shown) of attaching a tape (500'; not shown) on the stress-generating layer (400), and in step (S360), the semiconductor layer (300) and the stress-generating layer (400) may be separated from the starting substrate (100) using the tape (500').

The tape (500') is strongly adhered to the stress-generating layer (400) and serves to separate the stress-generating layer (400) from the starting substrate (100) together with the semiconductor layer (300). The tape (500') for this purpose may be a flexible tape.

Although the present disclosure only describes an example of separating a semiconductor layer (300) from a starting substrate (100) by a mechanical method, those skilled in the art will understand that the semiconductor layer can also be separated from the starting substrate by other methods, for example, an optical method using a laser.

Next, the method for manufacturing a semiconductor device of the present disclosure may further include a step (S400) of attaching a separated semiconductor layer (300) to a receiving substrate (600).

Here, the receiving substrate (600) may be a diamond substrate. The diamond substrate may be a polycrystalline diamond substrate manufactured to have a thickness of 200 micrometers or greater through, for example, a deposition process such as chemical vapor deposition (CVD) followed by a lapping process and a polishing process. Preferably, the diamond substrate has a thickness of 350 micrometers or greater.

There was a problem when forming a GaN semiconductor layer (300) directly on a diamond substrate without the intervention of another layer according to the conventional technology. Gallium nitride has a lattice constant different from that of diamond, and placing a GaN semiconductor layer (300) directly on a diamond substrate having a lattice constant different from that of diamond, that is, a lattice-mismatched diamond substrate, can cause serious dislocations and stress strain. Here, 'dislocation' refers to a defect in which the order of the lattice structure at the atomic level is destroyed. This defect is a defect formed when atoms in the lattice are locally deviated from the normal atomic arrangement. Since the GaN semiconductor layer must have a sufficiently low dislocation density to be suitable for the manufacture of optoelectronic or electronic devices, a relatively thick buffer layer had to be provided in the past to prevent this dislocation.

On the other hand, since the present disclosure adopts a method of manufacturing the diamond substrate and the semiconductor layer separately and then bonding them, the buffer layer does not need to be provided, so the disadvantage of the buffer layer conventionally acting as a thermal barrier between the semiconductor layer and the diamond substrate can be overcome, and the excellent thermal conductivity of the diamond substrate can be sufficiently utilized. In particular, according to the method of the present disclosure, the semiconductor layer is grown on a material having the same hexagonal lattice structure, particularly on a single crystal layer of the same material, so that the generation of dislocations is suppressed and the bow is reduced, thereby improving the quality of the semiconductor layer.

Next to the step (S400), the method for manufacturing a semiconductor device of the present disclosure may further include a step (S500) of removing a stress-generating layer (400) from a semiconductor layer (300).

Thereafter, various optoelectronic or electronic devices may be fabricated on the semiconductor layer (300), but the fabrication step of such devices may also be performed on the semiconductor layer (400) before the stress-generating layer (400) is attached.

Accordingly, the semiconductor device may include a diamond substrate; and a semiconductor layer (300) of a group III nitride compound attached on the diamond substrate, wherein the semiconductor layer (300) is formed on an amorphous carbon layer (200) and then separated from the amorphous carbon layer (200), so that the semiconductor layer (300) may include a residue from the amorphous carbon layer (200), or a portion where the residue is deformed by at least one of heat and pressure.

While the present invention has been described above with reference to only a few selected embodiments, those skilled in the art will readily understand the concepts upon which the present disclosure is based, and will readily utilize the concepts as a basis for designing other structures and processes for carrying out some of the purposes of the present invention. According to the method for manufacturing a semiconductor device of the present disclosure, by growing a GaN semiconductor layer on a self-standing GaN substrate or a bulk GaN substrate, it has the advantage of manufacturing a high-quality GaN semiconductor device with low dislocation and low bow while allowing reuse of an expensive self-standing GaN substrate or bulk GaN substrate. In addition, compared to the case where the self-standing GaN substrate or the bulk GaN substrate is utilized as is, it has the advantage of being able to effectively utilize the excellent thermal conductivity of the diamond substrate.

Although the present invention has been described with specific details such as specific components and limited embodiments and drawings, these have been provided only to help a more general understanding of the present invention, and the present invention is not limited to the embodiments, and those skilled in the art may make various modifications and variations from this description.

Therefore, the spirit of the present invention should not be limited to the embodiments described above, and all things equivalent to or modified by the appended claims of this disclosure as well as the same shall fall within the scope of the spirit of the present invention. For example, appropriate results may be achieved even if the described techniques are performed in a different order from the described method, and/or the described elements, structures, devices, etc., are combined or combined in a different form from the described method, or are replaced or substituted by other elements or equivalents.

Such equivalent or equivalent modifications would include, for example, a method capable of producing the same results as those obtained by carrying out the method according to the present invention, and the spirit and scope of the present invention should not be limited by the examples set forth above, but should be understood in the broadest sense permissible by law.

100: Starting board
200: Amorphous carbon layer
300: Semiconductor layer
400: Stress generating layer
500: Roller having adhesive material on its surface
500': Tape
600: Acceptance substrate

Claims (14)

As a method for manufacturing a semiconductor device,
A step of forming an amorphous carbon layer as a single layer or two to three layers on a starting substrate including a single crystal layer of a group III nitride compound on the upper surface;
A step of forming and growing a semiconductor layer of the Group III nitride compound on the amorphous carbon layer; and
A separation step for separating (releasing) the semiconductor layer from the starting substrate by separating the amorphous carbon layer upward and downward.
A method for manufacturing a semiconductor device, comprising: In the first paragraph,
A step of attaching the separated semiconductor layer to a receiving substrate
A method for manufacturing a semiconductor device, further comprising: In the second paragraph,
A method for manufacturing a semiconductor device, wherein the above-mentioned receiving substrate is a diamond substrate. In the third paragraph,
A method for manufacturing a semiconductor device, wherein the above diamond substrate is composed of CVD polycrystalline diamond. In the first paragraph,
The above separation step is,
A step of depositing a stressor layer on the semiconductor layer; and
A step of removing the semiconductor layer and the stress-generating layer from the starting substrate.
A method for manufacturing a semiconductor device, comprising: In paragraph 5,
The above separation step is,
A method for manufacturing a semiconductor device, characterized in that a roller having an adhesive material on its surface is rolled over the stress-generating layer, and the semiconductor layer and the stress-generating layer are separated from the starting substrate by the adhesive force of the adhesive material. In Article 6,
A method for manufacturing a semiconductor device, characterized in that the radius of curvature of the roller is equal to or greater than 1 time the longest dimension of the starting substrate. In the first paragraph,
A method for manufacturing a semiconductor device, wherein the amorphous carbon layer is formed on the starting substrate by metalorganic vapor-phase epitaxy (MOCVD). In the first paragraph,
A method for manufacturing a semiconductor device, wherein the amorphous carbon layer is a monolayer amorphous carbon layer. In the first paragraph,
A method for manufacturing a semiconductor device, wherein the above-mentioned Group III nitride compound is Al _x Ga _1-x N, wherein x is a real number greater than or equal to 0 and less than or equal to 1. delete As a semiconductor device,
diamond substrate; and
A semiconductor layer of a group III nitride compound attached on the above diamond substrate
Including,
A semiconductor device, wherein the semiconductor layer is formed on an amorphous carbon layer and then separated from the amorphous carbon layer. In Article 12,
A semiconductor device, wherein the semiconductor layer comprises a residue from the amorphous carbon layer, or a portion of the residue deformed by at least one of heat and pressure. In clause 12 or 13,
A semiconductor device wherein the above Group III nitride compound is Al _x Ga _1-x N, where x is a real number greater than or equal to 0 and less than or equal to 1.