KR20220161628A - 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 manufacturing method, an amorphous carbon layer is formed on a starting substrate including a single crystal layer of a Group III nitride-based compound on the upper surface, and a semiconductor layer of the Group III nitride-based compound is formed and grown on the amorphous carbon layer. Then, the semiconductor layer is released from the starting substrate.

Description

Semiconductor device and method for manufacturing the same {SEMICONDUCTOR DEVICE AND METHOD FOR FABRICATING THE SAME}

The present disclosure relates to a semiconductor device, specifically a Group III nitride-based compound semiconductor device, and more specifically to a gallium nitride (GaN) semiconductor device and a method of manufacturing the same.

Group Ⅲ nitride-based compound semiconductors, in particular, gallium nitride (GaN) semiconductors have a high breakdown voltage and a high band gap, which is advantageous for high power output, and a high electric field saturation rate due to high carrier concentration and high electron mobility. On the other hand, carrier scattering is low, which is advantageous for high-speed switching (ie, high-frequency operation).

Since such a semiconductor device generates a lot of heat, a combination with a heat spreader is required so that the device can remain in a stable operating temperature range. One well-known conventional approach has been to place and use a GaN layer on a silicon carbide (SiC) substrate configured to manage heat in place of silicon, which has a thermal conductivity of only about 149 W/m K. (eg US Patent No. 9,111,750). In this way, conventionally, after manufacturing a buffer layer using AlN, GaN, etc. on a Si substrate or a SiC substrate (e.g., an electronic device such as an AlGaN / GaN HFET (high electron mobility transistor) device) For the fabrication of} a GaN epilayer as an active layer was placed on top of the buffer layer.

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

For example, as disclosed in US Patents US 7,595,507 and US 9,359,693, etc., a technique for mounting a GaN device on a diamond substrate is to attach a GaN epilayer on a synthetic diamond substrate, for example, CVD polycrystalline diamond. In this way, the bow problem due to the material lattice mismatch and the difference in thermal expansion coefficient between the GaN layer and the diamond layer still remains.

US 9111750 B US 9359693 B

The present disclosure is to provide a novel semiconductor device manufacturing method capable of overcoming problems such as lattice mismatch and bow occurring in the prior art while using a CVD diamond substrate to effectively remove heat generated by GaN semiconductors. The purpose.

Specifically, in the present disclosure, a method of forming a GaN device on a high-quality freestanding GaN substrate or a bulk GaN substrate, separating the GaN device, and bonding the GaN device to a diamond substrate is provided in order to solve the above-mentioned disadvantages of the prior art.

The characteristic configuration of the present invention for achieving the object of the present invention as described above and realizing the characteristic effects of the present invention described later is as follows.

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

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

In one embodiment, the separating step may include depositing a stressor layer on the semiconductor layer; and separating the semiconductor layer and the stress generating 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 separating step, a roller having an adhesive material on a surface may be rolled over the stress generating layer, and the semiconductor layer and the stress generating layer may be separated from the starting substrate by adhesive force of the adhesive material.

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

Alternatively, the separating step may further include a step of attaching a tape on 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-based compound is Al _x Ga _1-x N, but x is a real number of 0 or more and 1 or less. 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-based compound on an upper surface; an amorphous carbon layer formed on the starting substrate; and a semiconductor layer of a Group III nitride-based compound formed on the amorphous carbon layer.

According to another aspect of the present disclosure, a semiconductor device is provided, including: a diamond substrate; and a semiconductor layer of a Group III nitride-based compound attached on the diamond substrate, wherein the semiconductor layer is formed on the amorphous carbon layer and then separated from the amorphous carbon layer.

In one embodiment, the semiconductor layer includes a portion where a 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 high-quality GaN device with low dislocation density and reduced bow can be manufactured by forming a GaN device on a high-quality self-standing GaN substrate or a bulk GaN substrate. Therefore, there is an effect of improving reliability such as reducing heat generation of the device and extending its lifespan.

In addition, according to the present disclosure, it is possible to effectively use the excellent thermal conductivity of a diamond substrate, thereby improving the reliability of a conventional GaN-on-diamond device.

For understanding of the present invention, embodiments will be described with reference to the accompanying drawings in order to show a process in which the method of the present disclosure is actually performed, which is only a non-limiting example, and which is common in the art to which the present disclosure belongs. Of course, other drawings can be obtained based on these drawings without additional effort leading to another invention for a person having knowledge of (hereinafter referred to as "ordinary skilled person").
1 is a diagram showing major steps of a method for manufacturing a semiconductor device according to the present disclosure.
FIG. 2 is perspective views of a semiconductor device conceptually illustrating each step of FIG. 1 .

A detailed description of the principles of a semiconductor device and a semiconductor device manufacturing method according to the present disclosure to be described later is specific to which the present invention can be practiced in order to make clear the objects, technical solutions, and advantages of the invention presented in the present disclosure. Reference is made to the accompanying drawings which illustrate embodiments by way of example. In the description with reference to the accompanying drawings, the same reference numerals are given to the same components regardless of reference numerals, and overlapping descriptions thereof will be omitted. It will be appreciated that the semiconductor structures according to the present disclosure do not have length ratios as shown in the drawings, and the dimensions of each part in the drawings are shown only for purposes of explanation and do not limit the scope of the present invention. For example, the dimensions of some of the elements shown in the drawings are to aid understanding of various embodiments. In addition, the description and drawings are not meant to be written in the order in which they are written. Those skilled in the art will appreciate that acts and/or steps described or illustrated in a particular order may require no particular 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. Therefore, the embodiments are not limited to the specific disclosed form, and the scope of the present disclosure includes changes, equivalents, or substitutes included in the technical spirit.

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

It should be understood that when an element is referred to as being “connected” to another element, it may be directly connected or connected to the other element, but other elements may exist in the middle. In addition, it should be understood that when an element is referred to as being 'on' another element, it may be 'directly on' the other element, but another element may exist in the middle.

Singular expressions include plural expressions unless the context clearly dictates otherwise. In this disclosure, terms such as "comprise" or "have" are intended to designate that the described feature, number, step, operation, component, part, or combination thereof exists, but one or more other features or numbers, It should be understood that the presence or addition of steps, operations, components, parts, or combinations thereof is not precluded.

Unless defined otherwise, 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 such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and unless explicitly defined in the present disclosure, interpreted in an ideal or excessively formal meaning. It doesn't work.

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

In addition, in the present disclosure, 'diamond substrate' is a term used interchangeably with each other. For example, such a diamond substrate is a polycrystalline diamond substrate having a predetermined diameter (eg, 4 inches or 100 mm or more). Those skilled in the art will understand that it may include.

In this disclosure, “semiconductor layer” refers to a semiconductor as an active layer of a semiconductor required for implementation of optoelectronic devices, such as high frequency transistors, high voltage switches, Schottky diodes, and/or laser diodes, LEDs, and the like, and other electronic devices. A term that includes a layered structure.

For example, the semiconductor layer may be formed of a plurality of layers. For example, a GaN semiconductor layer belonging to a group III nitride-based compound and an AlGaN semiconductor layer may constitute an active device such as an AlGaN/GaN HFET.

In this disclosure, the term “layer” refers to a material disposed over at least a portion of an underlying surface in a continuous or discontinuous manner. Also, the term "layer" does not necessarily mean that the disposed material has a constant thickness. The disposed material may have either a constant thickness or a varying thickness. Moreover, any “layer” used in this disclosure may refer to a single layer or a plurality of layers, unless the context clearly dictates otherwise. In this disclosure, the expression "disposed on" or "disposed on", and the expression "disposed between", unless otherwise specified, are arranged to be in direct contact with each other or interposed therebetween. It means that it was so arranged indirectly through other layers. Moreover, "on ~" and "on ~" only represent relative positions between layers/devices, because they may be seen differently depending on the observer's viewing point. Also, "formed on (over)" has a broad meaning, and that a layer is formed on another layer does not imply direct physical contact with the other layer. For example, when "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" means direct physical contact.

The invention covers all possible combinations of the embodiments presented in this disclosure. It should be understood that the various embodiments of the present invention are different, but need not be mutually exclusive. For example, specific shapes, structures, and characteristics described herein may be implemented in one embodiment in another embodiment without departing from the spirit and scope of the invention. That is, the embodiments of the present invention are described with reference to the drawings of the semiconductor device showing the concept of the ideal embodiment of the present invention, but should not be considered as being limited to the shape of a specific region of the structure as shown, and the result of manufacturing. As the shape of this branch, various modifications may be included. The regions shown in the drawings are conceptually shown in their characteristics and shapes, and are not intended to illustrate the exact shape of a structure or region, nor are they intended to limit the scope of the present invention. For example, a region shown as a rectangular block 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 invention. Accordingly, the detailed description set forth below is not to be taken in a limiting sense, and the scope of the present invention, if properly described, is limited only by the appended claims, along with all equivalents as claimed by those claims.

In this disclosure, unless otherwise indicated or clearly contradicted by context, terms referred to in the singular encompass the plural unless the context requires otherwise. In addition, in describing the present invention, if it is determined that the detailed description of a related known configuration or function is related to materials, processes, etc. well known to those skilled in the art and may obscure the gist of the present invention, the description thereof is excessive. Therefore, detailed descriptions are omitted.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily practice the present invention.

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

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

Here, the Group III nitride-based compound is Al _x Ga _1-x N, but x is a real number of 0 or more and 1 or less. 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. It can be collectively referred to as a substrate.

The top surface of the GaN starting substrate may be a polar surface, i.e., the surface normal of the top surface has a +c or -c crystallographic orientation, or an angular difference of less than 5 degrees therefrom. can have a crystallographic orientation.

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

In addition, the amorphous carbon layer 200 may be composed of a monolayer amorphous carbon, but is not limited thereto, and an amorphous carbon layer composed of 2 to 3 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, or ALD, in particular, metal organic chemical vapor deposition (MOCVD), but is not limited thereto.

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

For example, the formation and growth of the semiconductor layer 300 may 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 the amorphous carbon layer ( 200) and a semiconductor layer 300 of a group III nitride-based compound formed on it.

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

However, those skilled in the art will understand that even when the amorphous carbon layer 200 is composed of two or three layers instead of 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 a Ga-plane, the lower surface of the semiconductor layer 300 becomes an N-plane and the upper surface becomes a 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 to refer to FIGS. 1 and 2 , the semiconductor device manufacturing method of the present disclosure separates the semiconductor layer 300 from the starting substrate 100 by separating the upper and lower portions of the amorphous carbon layer 200. Step S300 is further included.

In one embodiment, the separation step (S300) deposits a stressor layer 400 on the semiconductor layer 300 (S320), and the semiconductor layer 300 and the stressor layer 400 are deposited on the starting substrate 100. ) from (S360).

Here, the stressor layer generates stress to facilitate the separation between the starting substrate 100 and the semiconductor layer 300, thereby cracking the amorphous carbon layer 200 located below the semiconductor layer 300 ( It refers to a layer of material that serves to induce and propagate cracks or fractures. The stress generating layer may be formed 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), the roller 500 having the adhesive material 510 on its surface is rolled over the stress generating layer 400, and the adhesive force by the adhesive material 510 is applied to the semiconductor. Layer 300 and stressor layer 400 may be peeled off from starting substrate 100 .

Preferably, the curvature of the roller 500 is such 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 The radius may be greater than or equal to one time the longest dimension of the starting substrate 100 .

Here, the longest dimension refers to the largest value that a distance from one point to another point included in an object 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 tape 500' ') may be used to separate the semiconductor layer 300 and the stress generating layer 400 from the starting substrate 100.

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 may be a flexible tape.

In this disclosure, only an example of separating the semiconductor layer 300 from the starting substrate 100 by a mechanical method has been described, but a person skilled in the art separates the semiconductor layer from the starting substrate by another method, for example, an optical method using a laser. You will understand that you can.

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

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

There is a problem when the GaN semiconductor layer 300 is directly formed on a diamond substrate according to the prior art without intervening other layers. Gallium nitride has a lattice constant different from that of diamond. Placing the GaN semiconductor layer 300 directly on a diamond substrate having a different lattice constant, that is, having a lattice-mismatched Severe displacements and strains can occur. Here, 'dislocation' refers to a pre-defect in a state in which the rules are broken in the lattice structure of the atomic unit. These line defects are defects that are formed as atoms in the lattice are locally dislocated from their normal atomic arrangement. Since the GaN semiconductor layer must have a sufficiently low dislocation density to be suitable for manufacturing optoelectronic or electronic devices, this dislocation Conventionally, in order to prevent this, a relatively thick buffer layer had to be placed.

On the other hand, in the present disclosure, by taking a method of manufacturing the diamond substrate and the semiconductor layer separately and bonding them together, there is no need to place a buffer layer, so the disadvantage of the buffer layer acting as a thermal barrier between the semiconductor layer and the diamond substrate in the prior art is overcome. and can fully utilize the excellent thermal conductivity of the diamond substrate. In particular, according to the method of the present disclosure, the semiconductor layer is grown on a material having the same hexagonal lattice structure, in particular, 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. do.

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

After that, various optoelectronic or electronic devices may be fabricated on the semiconductor layer 300 , but fabrication steps of such devices may also be performed on the semiconductor layer 400 before the stress generating layer 400 is attached.

Accordingly, the semiconductor device includes a diamond substrate; and a semiconductor layer 300 of a Group III nitride-based compound attached on the diamond substrate. Here, the semiconductor layer 300 is formed on the amorphous carbon layer 200 and then removed from the amorphous carbon layer 200. Since it is separated, 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.

In the above, the present invention has been described only with selected examples, but those skilled in the art can easily understand the concept on which this disclosure is based, and as a basis for designing other structures and processes for performing some objects of the present invention. You will be able to use the concept easily. According to the method for manufacturing a semiconductor device of the present disclosure, a GaN semiconductor layer is grown on a free-standing GaN substrate or a bulk GaN substrate to manufacture a high-quality GaN semiconductor device with low potential and low bow while reusing an expensive free-standing GaN substrate or bulk GaN substrate. There are advantages to doing so. In addition, there is an advantage in that the excellent thermal conductivity of the diamond substrate can be effectively used compared to the case of using a free-standing GaN substrate or a bulk GaN substrate as it is.

As such, although the present invention has been described with specific details such as specific components and limited embodiments and drawings, this is provided only to help a more general understanding of the present invention, and the present invention is not limited to the above embodiments, and usually Various modifications and variations can be made from these descriptions by those skilled in the art.

Therefore, the spirit of the present invention should not be limited to the above-described embodiments, and the claims attached to this disclosure as well as all modifications equivalent or equivalent to these claims are the spirit of the present invention. would be said to fall into the category of For example, the described techniques may be performed in a different order than the described method, and/or the described elements, structures, devices, etc. may be combined or combined in a different form than the described method, and other components or equivalents may be used. Appropriate results can be achieved even when substituted or substituted by water.

Such equivalent or equivalent modifications will include, for example, a method capable of producing the same results as in the practice of the method according to the present invention, and the spirit and scope of the present invention are limited by the above examples. It should not be, and should be understood in the broadest sense permitted by law.

100: starting substrate
200: amorphous carbon layer
300: semiconductor layer
400: stress generating layer
500: roller having adhesive material on the surface
500': tape
600: receiving substrate

Claims (14)

As a semiconductor device manufacturing method,
Forming an amorphous carbon layer on a starting substrate including a single crystal layer of a Group III nitride-based compound on an upper surface;
forming and growing a semiconductor layer of the Group III nitride-based compound on the amorphous carbon layer; and
A release step of releasing the semiconductor layer from the starting substrate.
Including, a semiconductor device manufacturing method. According to claim 1,
attaching the separated semiconductor layer to a receiving substrate;
Further comprising a semiconductor device manufacturing method. According to claim 2,
The semiconductor device manufacturing method of claim 1 , wherein the receiving substrate is a diamond substrate. According to claim 3,
wherein the diamond substrate is composed of CVD polycrystalline diamond. According to claim 1,
The separation step is
depositing a stressor layer on the semiconductor layer; and
detaching the semiconductor layer and the stress generating layer from the starting substrate;
Including, a semiconductor device manufacturing method. According to claim 5,
The separation step is
A method of manufacturing a semiconductor device, characterized in that a roller having an adhesive material on a surface thereof is rolled over the stress generating layer, and the semiconductor layer and the stress generating layer are separated from the starting substrate by an adhesive force by the adhesive material. According to claim 6,
Characterized in that the radius of curvature of the roller is equal to or greater than one time of the longest dimension of the starting substrate. According to claim 1,
The amorphous carbon layer is formed on the starting substrate by metalorganic vapor-phase epitaxy (MOCVD). According to claim 1,
The method of claim 1 , wherein the amorphous carbon layer is a monolayer amorphous carbon layer. According to claim 1,
The Group III nitride-based compound is Al _x Ga _1-x N, but x is a real number of 0 or more and 1 or less, a semiconductor device manufacturing method. As a semiconductor device,
a starting substrate including a single crystal layer of a Group III nitride-based compound on an upper surface;
an amorphous carbon layer formed on the starting substrate; and
A semiconductor layer of a group III nitride-based compound formed on the amorphous carbon layer
Including, a semiconductor device. As a semiconductor device,
diamond substrate; and
A semiconductor layer of a group III nitride-based compound deposited on the diamond substrate
including,
The semiconductor device, wherein the semiconductor layer is formed on and then separated from the amorphous carbon layer. According to claim 12,
The semiconductor device of claim 1 , wherein the semiconductor layer includes a residue from the amorphous carbon layer or a portion where the residue is deformed by at least one of heat and pressure. According to claim 12 or 13,
The group Ⅲ nitride-based compound is Al _x Ga _1-x N, but x is a real number of 0 or more and 1 or less, a semiconductor device.

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