JP2013502728A - High-speed growth method and structure for gallium and nitrogen containing ultra-thin epitaxial structures for devices - Google Patents

Abstract

A method for rapid growth of gallium and nitrogen containing materials is described. The method includes providing a bulk gallium and nitrogen containing substrate. A first thickness of the first epitaxial material is formed on the substrate, preferably by a pseudomorphic process. The method also forms a second epitaxial layer on the first layer, thereby providing a stack structure. The stack structure is constructed with an overall thickness of less than about 2 microns.
[Selection] Figure 4

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is directed to US Provisional Application No. 61 / 235,989 (Athony Docket No. 027364-007500 US; filing date: August 21, 2009) assigned to the assignee of the present invention. Claims priority and is hereby incorporated by reference in its entirety for all purposes.

The present invention generally relates to lighting technology. More particularly, embodiments of the present invention include techniques for rapid growth of epitaxial structures using metal organic chemical vapor deposition (“MOCVD”) techniques on bulk gallium and nitrogen containing materials. The present invention can be applied to, for example, white lighting, multicolor lighting, flat panel displays and other optoelectronic devices and applications for other applications.

In the late 1800s, Thomas Edison invented the light bulb. Conventional bulbs are called “Edison bulbs” and have been used for over a hundred years. In the case of a conventional bulb, a tungsten filament is enclosed in a glass bulb, the glass bulb is sealed in the base, and the base is screwed into the socket. The socket is connected to AC power or DC power. Conventional light bulbs are widely found in homes, buildings and outdoor lighting, and areas that require other lighting or displays. Unfortunately, conventional Edison bulbs have the following defects: That is, a large amount of heat energy is dissipated in the case of a conventional bulb. That is, more than 90% of the energy used in the conventional bulb is dissipated as heat energy. Furthermore, conventional bulbs often fail regularly due to thermal contraction of the filament element.

Fluorescent lamps eliminate some of the deficiencies of conventional bulbs. In a fluorescent lamp, a tube structure filled with a halogen gas is used. A pair of electrodes in the tube is connected to an AC power source through a ballast. When the gas is excited, it discharges and emits light. The tube is often coated with a phosphor material. Many buildings use fluorescent lamps, and more recently, fluorescent lamps are adapted to be screwed into standard incandescent bulb sockets.

Solid state lighting technology is known. Solid state lighting typically relies on semiconductor materials in the manufacture of light emitting diodes (LEDs). In the early days, red LEDs were demonstrated and commercialized. In the red LED, an aluminum indium gallium phosphide (AlInGaP) semiconductor material is used. More recently, Shuji Nakamura pioneered the use of InGaN materials to produce LEDs that emit blue spectrum light. This blue LED led to innovations such as Blu-ray DVD players, solid phase white lighting, and other developments. Other color LEDs have also been proposed, but solid-state lighting still has limitations. Further details of such constraints are described throughout this specification and are described in detail below.

From the above, it can be seen that a technique for improving an optical device is strongly desired.

The present invention generally relates to lighting technology. More particularly, embodiments of the present invention include techniques for rapid growth of epitaxial structures using metal organic chemical vapor deposition (“MOCVD”) techniques on bulk gallium and nitrogen containing materials. The present invention can be applied to, for example, white lighting, multicolor lighting, flat panel displays and other optoelectronic devices and applications for other applications.

In certain embodiments, the present invention provides a method for rapid growth of gallium and nitrogen containing materials. The method includes providing a bulk gallium and nitrogen containing substrate having a surface region. The method forms a first epitaxial material of a first thickness on the surface of the bulk gallium and nitrogen containing substrate. In a preferred embodiment, the first epitaxial material is formed pseudomorphically. The method also forms a second epitaxial material on the first epitaxial material to form a stack structure. In a preferred embodiment, the second epitaxial material forms an active region (eg, a junction). Preferably, the total thickness of the stack structure is less than about 2 microns, and the stack structure characterizes at least a substantial portion of the epitaxial region of the optical or electrical device. As used herein, the terms “first” and “second” generally do not imply any order or sequence. In certain embodiments, “pseudomorphically” generally refers to a lattice matching process that lattice matches the first epitaxial material to the bulk gallium and nitrogen containing substrate. In a preferred embodiment, the interfaces of the epitaxially formed gallium nitride material and the bulk gallium and nitrogen containing substrate are substantially or completely lattice matched to each other.

In certain embodiments, the first epitaxial material is less than 1 micron or less than 100 nm. The thickness of the epitaxial material is less than 1 micron or less than 10 nm. The first epitaxial material is characterized in that the stack defect density can be 1E4 cm ⁻¹ or less and the threading dislocation can be 1E8 cm ⁻² or less. The epitaxial material is characterized in that it has a substantially uniform defect density from the first region to the second region. Preferably, the first epitaxial layer and the surface region have an interface that is substantially free of nucleation layers (eg, GaN or AlN or AlGaN, or other gallium and nitrogen containing materials).

The method is characterized by a fast growth time. In certain embodiments, the total growth time for the formation of gallium and nitrogen containing epitaxial materials is less than 1 hour, often less than 30 minutes, but can be less than 15 minutes. In certain embodiments, the method has a chamber time characterized by a total growth time and a temperature ramping time. The chamber time can be less than 1 hour, but can be less than 30 minutes. In certain embodiments, the method has a cycle time including a chamber time and loading and unloading times. The cycle time is less than 2 hours, but can be less than 1 hour, and even less than 30 minutes. In a particular embodiment, the gallium and nitrogen containing material is characterized by a growth rate of 4 microns / hour or more, and the growth rate of the n-type gallium and nitrogen containing material is 6 microns / hour or more. In certain embodiments, the growth rate of the p-type gallium and nitrogen containing material is 2 microns / hour or more. Preferably, the higher growth rate is obtained by use of an atmospheric MOCVD reactor, but the pressure may be slightly above atmospheric pressure or less than atmospheric pressure. The growth temperature is about 950 ° C. to 1200 ° C. or more in the case of n-type gallium and nitrogen-containing materials (eg, including silicon dopant), or in the case of p-type gallium and nitrogen-containing materials (eg, containing magnesium dopant). 950 ° C to about 1025 ° C. It should be noted that conventional MOCVD reactors include a thermocouple temperature device connected to a susceptor, although this may be modified. The susceptor holds the workpiece and / or the substrate.

In another embodiment, the epitaxial material (s) can be formed in a reactor. The reactor can handle a plurality of wafers in an automatic growth sequence (eg, an autocassette). In such a configuration, the loading and unloading of wafers from the growth chamber to the load lock can be performed without interference or waiting for the movement of the wafer between the load lock and the laboratory or manufacturing floor. It can be done automatically. In one configuration, a robot arm is used to move the wafer between the load lock chamber and the reaction chamber. In such a configuration, movement of the wafer to or from the growth chamber is performed on a susceptor or tray, and epitaxial growth is performed on the wafer on the susceptor or tray. In a preferred embodiment, the susceptor or tray includes a plurality of wafers so that the epitaxial material (s) can be formed in the reactor chamber and can be grown on the plurality of wafers simultaneously. As used herein, the term “autocassette” generally refers to a cassette having a series of trays. Each of these series of trays has a substrate wafer or workpiece, which allows for automatic loading of each workpiece continuously. In a preferred embodiment, a cassette containing a plurality of substrates or workpieces is maintained in the chamber. The chamber is connected to the MOCVD chamber. Thereby, handling time etc. reduce.

The present invention enables methods and systems using multi-wafer autocassettes and fast growth (eg, ultra-fast growth). In certain embodiments, the methods and systems can be configured for atmospheric pressure growth. This is because the methods and systems allow for faster growth rates and shorter growth times, both of which are desirable. In certain embodiments, the present systems and methods can be configured for large substrates (eg, 4 inches, 6 inches, or more) using a multi-wafer cassette. In a preferred embodiment, the method also moves impurities away from the growth interface. The present invention can be used with various optical devices that emit blue, purple, green, yellow, and the like. Of course, other changes, modifications, and alternatives are possible.

The present invention provides a method for rapid growth of gallium and nitrogen containing materials. The method includes providing a bulk gallium and nitrogen-containing substrate having a surface region and growing a first epitaxial material of a first thickness on the surface region of the bulk gallium and nitrogen-containing substrate by at least 4 nm / hour. Forming at a speed. The first epitaxial material is pseudomorphically formed on the surface region of the bulk gallium and nitrogen containing substrate. The method includes forming one or more second epitaxial materials on the first epitaxial material. The one or more second epitaxial materials are configured to form a stack structure.

In still other embodiments, the epitaxial material (s) can be formed in a single or multiple chambers. In certain embodiments, one or more of the epitaxial materials or all of the epitaxial materials may be formed in a single chamber and / or in multiple chambers or any combination. In a preferred embodiment, the epitaxial material or materials are formed to have a uniform temperature distribution inside. Of course, other changes, modifications, and alternatives are possible.

By the above method, a smooth epitaxial material can be obtained. For example, when n-type gallium and nitrogen-containing materials are used, the surface roughness in a spatial region of 5 microns × 5 microns is about 1 nm RMS or less. For example, when p-type gallium and nitrogen-containing materials are used, the surface roughness in a spatial region of 5 microns × 5 microns is about 1 nm RMS or less.

A further understanding of the nature and advantages of the present invention may be obtained by reference to the latter portions of the specification and the accompanying drawings.

1 is a simplified diagram of a conventional optical device using a thick epitaxial layer according to an embodiment of the present invention.

1 is a simplified diagram of an optical device according to an embodiment of the present invention.

It is a simplified diagram showing a processing method according to an embodiment of the present invention.

In the optical device processing method by one Embodiment of this invention, it is the simple figure which plotted temperature with respect to growth time.

FIG. 6 is a simplified diagram plotting a conventional optical device on sapphire for comparison with an optical device according to one embodiment of the present invention.

1 is a simplified diagram of an optical device growth method according to an embodiment of the present invention. FIG.

2 is a simplified diagram of a growth method for rectification of a pn junction diode according to an embodiment of the present invention. FIG.

2 is a simplified diagram of a growth method of a high electron mobility transistor or a metal-semiconductor field effect transistor according to an embodiment of the present invention.

Conventional GaN light emitting diodes (LEDs) that emit in the ultraviolet and visible regions are based on heteroepitaxial growth that begins to grow on substrates other than GaN (eg, sapphire, silicon carbide, or silicon). This is because a free-standing GaN substrate has a limited supply amount and high cost, and as a result, the stand-alone GaN substrate cannot be used in LED manufacturing. However, the field of bulk GaN technology has grown significantly over the past few decades, and as a result, large scale deployments in LED manufacturing are possible. Such technology shifts provide benefits in LED performance and manufacturing.

Referring to FIG. 1, in order to grow on a foreign substrate, the following is often required: That is, a technique such as a low-temperature nucleation layer or a high-temperature nucleation layer at the substrate interface, lateral epitaxial abnormal growth for moving misalignment defects formed at the GaN / substrate interface; usually composed of n-type GaN (In _x Reduction of adverse effects due to misalignment defects by growing a thick buffer layer between the substrate and the light emitting active layer (which may be made of other materials such as Al _y Ga _1-xy N); InGaN Improving radiation efficiency through strain transfer, defect transfer or some other mechanism by placing / GaN or AlGaN / GaN or AlInGaN / AlInGaN superlattice between the substrate and the light-emitting active layer; InGaN buffer layer or AlGaN Strain transfer, defect transfer or some other mechanism by placing a buffer layer between the substrate and the light emitting active layer Improvement of radiation efficiency through; by p-type GaN layer having a thickness of from, and the like reduce the movement and leakage current of electrostatic discharge (ESD). In order to include all these layers, conventional LED growth can require 4-10 hours.

By growing the LED on the bulk GaN substrate, the low temperature nucleation layer can be eliminated, for example, as shown in FIG. FIG. 2 is merely an illustration and should not unduly limit the scope of the claims set forth herein. Those skilled in the art will recognize other changes, modifications, and alternatives. Since there is no misalignment displacement, a defect transfer technique such as lateral epitaxial abnormal growth is unnecessary. In order to improve radiation efficiency, it is often necessary to use an alloy superlattice or alloy layer between the substrate and the active region. The buffer layer that separates the substrate from the light emitting layer can be as thin as 1 to 2 microns to 10 to 20 nm, or can be completely eliminated. By alleviating the constraints on layer thickness and the requirements on layer inclusion in this way, the total epitaxial stack total thickness can be reduced to a fraction of that of conventional LED structures. The total LED thickness can be reduced to less than 250 nm and theoretically can be reduced to ˜30 nm. As a result, the total LED growth time can be reduced to less than 1 hour, and theoretically can be reduced to ~ 15 minutes.

In addition, since a wide variety of growth layers are required on a conventional LED grown on a foreign substrate, different growth temperatures are required. However, in this LED structure, only a few growth layers are required. Since it is not necessary, the temperature ramping in the growth recipe is also smaller. The shorter the total growth time, the more important the ratio of temperature ramping time within the total cycle time. Therefore, the reduction in ramping required in this scheme is important for achieving high growth throughput.

Because the desired chamber time is significantly reduced for the wafer, the wafer handling time required to load and unload the wafer from the growth tool becomes increasingly important when a reduction in total growth cycle time is desired. That is, if the load time and unload time at the start and end of each growth run are 15 to 30 minutes, the total time associated with these steps is 30 to 60 minutes. If the required chamber time is less than 1 hour, the loading and unloading steps will be 1/3 to 1/2 of the total cycle time. A large portion of the load time and unload time is occupied by load pumping and backfilling between the growth chamber and the external environment. The purpose of this is to avoid entry of contaminants into the growth chamber and to avoid growth products leaving the chamber. Configuring the growth tool to automatically move wafers between the growth chamber and a load lock chamber with a wafer cassette for storing wafers to be grown later reduces total growth cycle time by a factor of two It becomes possible to do. First, since the load lock pump and purge need only be performed once during loading and unloading of the entire cassette, fewer pump and purge cycles are required. That is, if the cassette can hold 10 wafers for continuous growth, instead of pumping and purging each wafer individually in the load and unload cycles for all 10 wafers. The total pump purge time is reduced by a factor of 10 by performing the pump and purge only once. The second time reduction is made possible by the handling of hot wafers made possible by the automatic load / unload mechanism. This is possible because there is no possibility of contamination because the moving mechanism composed of metal or other material can withstand high temperatures and is not exposed to the ambient environment when the wafer is hot. Because. These and other features of the method and structure of the present invention can be found throughout this specification and are detailed below.

Finally, using this ultra-high-speed growth method together with the autocassette function and multi-wafer MOCVD reactor described above, two or more substrates are loaded into the same chamber. In another variation, the reactor can be configured with multiple chambers to maintain each chamber at a different temperature, minimizing temperature cycle time and stabilization time. Such a configuration uses a moving arm to move the wafer from one chamber to another.

FIG. 3 is a simplified diagram of a processing method according to an embodiment of the present invention. FIG. 3 is merely exemplary and is not intended to unduly limit the scope of the claims set forth herein. Those skilled in the art will recognize other changes, modifications, and alternatives.

FIG. 4 is a simple diagram plotting temperature against growth time in an optical device processing method according to an embodiment of the present invention. This diagram is merely an example and should not unduly limit the scope of the claims set forth herein. Those skilled in the art will recognize other changes, modifications, and alternatives. As shown, the vertical axis indicates the thermocouple temperature (° C.) and the horizontal axis indicates the growth time in minutes. As shown, the plot indicated by 1 ′, 2 ′, 3 ′ shows nonpolar LED growth on the bulk gallium nitride-containing material. The bulk gallium nitride material is nonpolar GaN, but may be other materials. Also, as shown, the plots indicated by 1, 2, 3, 4, 5, 6, 7 show conventional c-plane LED device growth on sapphire material. This table compares the growth of a conventional LED structure on a foreign substrate and the growth on a bulk substrate in terms of growth time. Reference numeral 1 indicates an LED structure grown on bulk GaN using temperature cycling for active region growth. Reference number 2 shows an LED structure grown on bulk GaN without temperature cycling (ie, all epi layers are grown at the same temperature). Clearly, the growth time of the bulk gallium nitride material is significantly shorter than the growth time of the conventional c-plane LED device. By eliminating growth layers such as nucleation layers and InGaN / GaN superlattices and reducing the thickness of n- and p-GaN cladding layers, a significant reduction in growth time was achieved. Of course, other changes, modifications, and alternatives are possible.

FIG. 5 is a simple plot comparing a conventional optical device on sapphire with an optical device according to an embodiment of the present invention. This diagram is merely an example and should not unduly limit the scope of the claims set forth herein. Those skilled in the art will recognize other changes, modifications, and alternatives.

FIG. 6 is a simplified diagram of a method of growing an optical device according to an embodiment of the present invention. This diagram is merely an example and should not unduly limit the scope of the claims set forth herein. Those skilled in the art will recognize other changes, modifications, and alternatives. As shown, the growth sequence includes at least (1) an n-type epitaxial material, (2) an active region, (3) an electron blocking region, and (4) a p-type epitaxial material. Of course, other changes, modifications, and alternatives are possible. Further details of the method are described throughout the specification and are detailed below.

1. Bulk wafer:
Arbitrary orientation (eg, polar, nonpolar, semipolar, c-plane)
(Al, Ga, In) N-based material threading dislocation (TD) density <1E8 cm ⁻²
Stacking defect (SF) density <1E4 cm ⁻¹
Doping> lE17 cm ⁻³

2. N-type epitaxial material:
Thickness <2um, <lum, <0.5um, <0.2um
(Al, Ga, In) N base material growth T <1200C, <1000C
Unintentionally doped (UID) or doped

3. Active region:
Thickness>20A,>50A,> 80A of at least one AlInGaN layer multiple quantum well (MQW) structure QW
QW and n- and p-layer growth temperatures are the same or similar emission wavelengths <575 nm, <500 nm, <450 nm, <410 nm

4). P-type epitaxial material thickness of at least one Mg doped layer <0.3um, <0.1um
(Al, Ga, In) N base growth T <1100C, <1000C, <900C
At least one layer functions as an electron blocking layer and at least one layer functions as a contact layer

Of course, other changes, modifications, and alternatives are possible. Further details are described throughout the specification and are detailed below.

In certain embodiments, the method provides a bulk gallium and nitrogen containing substrate. In certain embodiments, the gallium nitride substrate member is a bulk GaN substrate characterized by having a semipolar or nonpolar crystalline surface region, but may be others. In certain embodiments, the bulk nitride GaN substrate comprises nitrogen and has a surface displacement density of less than 10 ⁵ cm ⁻² . The nitride crystal or wafer may include Al _x In _y Ga _1-xy N (0 <x, y, x + y <1). In one particular embodiment, the nitride crystal comprises GaN, but may be other. In one or more embodiments, the threading dislocation density in a direction substantially perpendicular or oblique to the surface of the GaN substrate is from about 10 ⁵ cm ⁻² to about 10 ⁸ cm ⁻² . As a result of such displacement in the perpendicular or oblique direction, the surface displacement density is lower than about 10 ⁵ cm ⁻² . In a preferred embodiment, the method can include gallium and nitrogen containing substrates configured with any orientation (eg, c-plane, a-plane, m-plane). In certain embodiments, the substrate is preferably (Al, Ga, In) N based. The threading dislocation (TD) density of the substrate <1E8 cm −2, the stacking defect (SF) density <5E3 cm −1, and can be doped with silicon and / or oxygen at a concentration> 1E17 cm −3. Of course, other changes, modifications, and alternatives are possible.

As shown, the method forms an n-type material on the surface of the gallium and nitrogen containing substrate. In certain embodiments, the n-type material is formed epitaxially, and the thickness of the n-type material is less than 2 microns, less than 1 micron, less than 0.5 microns, or less than 0.2 microns, and other thicknesses It may be. In certain embodiments, the n-type material is (Al, Ga, In) N based. The growth is performed using a temperature below about 1200 ° C. or a temperature below about 1000 ° C., but generally using a temperature above 950 ° C. In a preferred embodiment, the n-type material is unintentionally doped (UID) or doped with silicon species (eg Si) or oxygen species (eg O 2). In certain embodiments, the dopant may be derived from silane, disilane, oxygen, and the like. In a particular embodiment, the n-type material functions as the n-type (silicon-doped) GaN contact region, is about 5 microns thick, and has a doping level of about 2 × 10 ¹⁸ cm ^−3. Is characterized in that In a preferred embodiment, gallium and nitrogen containing epitaxial materials are deposited on the substrate at atmospheric pressure by metal organic chemical vapor deposition (MOCVD). The growth flow ratio between the Group V precursor (ammonia) and the Group III precursor (trimethylgallium, trimethylindium, trimethylaluminum) is about 3,000 to about 12,000. Of course, other changes, modifications, and alternatives are possible.

In a preferred embodiment, the method forms an active region on the n-type contact region. The active region includes at least one AlInGaN layer, and preferably includes a multi-quantum well structure. Each of the quantum wells is characterized by a thickness of 20 angstroms or less, 50 angstroms or less, or 80 angstroms or less, or combinations thereof. If desired, the active region may also include one or more barrier regions. In certain embodiments, the growth temperatures of the n-type contact region and the quantum well region are the same or slightly different. In a preferred embodiment, the MQW structure is configured for emission of 500 nm or less, emission of 450 nm or less, or emission of 410 nm or less.

In certain embodiments, an undoped AlGaN electron blocking region is deposited. In certain embodiments, the blocking region has a thickness of 0.3 microns or less or 0.1 microns or less. In a preferred embodiment, a p-type GaN contact region is deposited. Preferably, the growth temperature of the p-type contact region is 1100 ° C. or lower, 1000 ° C. or lower, or 900 ° C. or lower. Indium tin oxide (ITO) is e-beam evaporated on the p-type contact layer as a p-type contact and subjected to rapid thermal annealing. The LED mesa is formed by photolithography and dry etching with a size of about 300 × 300 μm ² using chlorine based inductively coupled plasma (ICP) technology. Ti / Al / Ni / Au is electron beam evaporated on the exposed n-GaN layer to form an n-type contact, and Ti / Au is electron beam evaporated on a portion of the ITO layer to form a p-contact pad. Once formed, the wafer is diced to obtain separate LED dies. The electrical contacts are formed by conventional wire bonding. Of course, other changes, modifications, and alternatives are possible.

In other embodiments, the method is characterized by a fast growth time. In certain embodiments, the total growth time is characterized by the formation of gallium and nitrogen containing epitaxial materials. The total growth time is less than 1 hour, less than 30 minutes, less than 15 minutes, and the like. In certain embodiments, the method has a chamber time characterized by a total growth time and a temperature ramping time. The chamber time may be less than 1 hour, less than 30 minutes, etc. In certain embodiments, the method has a cycle time. The cycle time is obtained by chamber time and loading and unloading time. The cycle time can be less than 2 hours, less than 1 hour, less than 30 minutes, and the like. In certain embodiments, the gallium and nitrogen containing material is characterized in that the growth rate is 4 microns / hour or more, and the n-type gallium and nitrogen containing material is characterized in that it is 6 microns / hour or more. . In certain embodiments, the p-type gallium and nitrogen containing material is grown at a rate of 2 microns / hour or more. Preferably, the higher growth rate is generated by an atmospheric MOCVD reactor and may be slightly above or below atmospheric pressure. The growth temperature may be in the range of about 950 ° C. to 1200 ° C. or higher in the case of n-type gallium and nitrogen containing materials (eg, including silicon dopant), or p-type gallium and nitrogen containing materials (eg, magnesium dopant). In the case of (including), it may be in the range of 950 ° C. to about 1025 ° C. Of course, other changes, modifications, and alternatives are possible.

In a preferred embodiment, the method results in a smooth epitaxial material. For example, when n-type gallium and nitrogen-containing materials are used, the surface roughness in a spatial region of 5 microns × 5 microns is about 1 nm RMS or less. In certain embodiments, for example when using p-type gallium and nitrogen containing materials, the surface roughness in a 5 micron x 5 micron spatial region is characterized by about 1 nm RMS or less. Of course, other changes, modifications, and alternatives are possible.

FIG. 7 is a simplified diagram of a growth method for rectifying a pn junction diode according to an embodiment of the present invention. This diagram is merely an example and should not unduly limit the scope of the claims set forth herein. Those skilled in the art will recognize other changes, modifications, and alternatives. As shown, the growth sequence includes at least (1) an n-type epitaxial material and (4) a p-type epitaxial material. Of course, other changes, modifications, and alternatives are possible. Further details of the method can be found throughout the specification and are particularly detailed below.

1. Bulk wafer arbitrary orientation (Al, Ga, In) N base threading dislocation (TD) density <1E8 cm −2
Stacking defect (SF) density <5E3 cm-1
Doping> lE17cm-3

2. N-type layer <2um, <lum, <0.5um, <0.2um
(Al, Ga, In) N base growth T <1200C, <1000C
UID or dope

3. P-type layer at least one Mg doped layer <0.3 um, <0.1 um
(Al, Ga, In) N base growth T <1100C, <1000C, <900C
At least one layer functions as an electron blocking layer and at least one layer functions as a contact layer

Of course, other changes, modifications, and alternatives are possible. Further details are described throughout this specification.

FIG. 8 is a simplified diagram of a method for growing a high electron mobility transistor or a metal semiconductor field effect transistor according to an embodiment of the present invention. This diagram is merely an example and should not unduly limit the scope of the claims set forth herein. Those skilled in the art will recognize other changes, modifications, and alternatives. As shown, the growth sequence includes at least (1) an unintentionally doped epitaxial material (buffer) and (4) a barrier that is an unintentionally doped material or an n-type epitaxial material (AlInGaN). It is out. Of course, other changes, modifications, and alternatives are possible. Further details of the method can be found throughout the specification and are particularly detailed below.

1. Bulk wafer arbitrary orientation (Al, Ga, In) N base threading dislocation (TD) density <1E8 cm −2
Stacking defect (SF) density <5E3 cm-1
Doping> lE17cm-3

2. Buffer layer <2um, <lum, <0.5um, <0.2um
(Al, Ga, In) N base growth T <1200C, <1000C
At least one semi-insulating layer with UID or doped Fe or C doping

3. Barrier layer <0.1um, <500nm, <30nm
(Al, Ga, In) N base growth T <1200C, <1100C, <1000C
At least one Si-doped layer

Of course, other changes, modifications, and alternatives are possible. Further details are described throughout the specification.

In a particular embodiment, the nitride crystal comprises nitrogen and the surface displacement density of the nitride crystal is less than 10 ⁵ cm ⁻² . The nitride crystal or wafer is _{Al x In y Ga 1-x} -y N may comprise (0 <x, y, x + y <1). In one particular embodiment, the nitride crystal includes GaN. In a preferred embodiment, the nitride crystal is substantially free of low-angle grain boundaries or tilt boundaries over a length scale of at least 3 millimeters. The nitride crystal may also include a release layer. At least one wavelength at which the base crystal under the release layer becomes substantially transparent, the light absorption coefficient of the release layer is greater than 1000 cm ⁻¹ and the light absorption coefficient is less than 50 cm ⁻¹ for high quality An epitaxial layer may further be included. The surface displacement density of the high quality epitaxial layer is also less than 10 ⁵ cm ⁻² . The release layer may be etched under conditions where the nitride base crystal and the high quality epitaxial layer are not etched. Of course, other changes, modifications, and alternatives are possible.

In certain embodiments, the substrate can have a large surface orientation. The large surface orientations are (0 0 0 1), (0 0 0 -1), {1 -1 0 0}, {1 1 -2 0}, {1 -1 0 ± 1}, {1 -1 0 ± 2}, {1-1 0 ± 3} or {1 1 -2 ± 2} within 10 degrees, within 5 degrees, within 2 degrees, within 1 degree, within 0.5 degrees, or 0.2 degrees Is within. The displacement density of the substrate may be less than 10 ⁴ cm ^−2, less than 10 ³ cm ⁻² , or less than 10 ² cm ⁻² . The light absorption coefficient of the nitride-based crystal or wafer at a wavelength of about 465 nm to about 700 nm can be less than 100 cm ^−1, less than 50 cm ^−1, or less than 5 cm ⁻¹ . The light absorption coefficient of the nitride-based crystal at a wavelength of about 700 nm to about 3077 nm and a wavelength of about 3333 nm to about 6667 nm can be less than 100 cm ^−1, less than 50 cm ^−1, or less than 5 cm ⁻¹ . Of course, other changes, modifications, and alternatives are possible.

Although specific embodiments have been described in detail above, various modifications, alternative constructions, and equivalents may be used. As an example, the present invention can be applied to use of an autocassette MOCVD reactor. In this autocassette MOCVD reactor, the cassette holds two or more (or ten or more) single wafers or wafer platters for a multi-wafer reactor. In one or more embodiments, the epitaxial structure can form an LED device. The LED device can emit electromagnetic radiation in the range of 390-420 nm, 420-460 nm, 460-4500 nm, 500-600 nm, and the like. In certain embodiments, for example, pn diodes, Schottky diodes, transistors, high electron mobility transistors (HEMT), bipolar junction transistors (BJT), heterojunction bipolar transistors (HBT), metal semiconductor field effect transistors ( There are various devices such as MESFET), metal oxide semiconductor field effect transistor (MOSFET), metal insulator semiconductor heterojunction field effect transistor (MISHFET), and combinations thereof. In other embodiments, the method is applicable to laser diode devices (eg, those described in US Serial No. 12 / 759,273; Attorney Docket No. 027600-000210US). This document is incorporated by reference for all purposes. In one or more embodiments, the gallium and nitrogen containing material may be characterized by one or a variety of surface orientations (eg, nonpolar, semipolar, polar). Further details of the invention can be found throughout the specification and are particularly detailed below.

Example:
In order to prove the principle and operation of this experiment, the present inventors conducted an experiment. The inventors have demonstrated a high quality GaN epitaxial film at a high growth rate of 4 microns / hour or more. This experiment was performed using the atmospheric pressure MOCVD reactor configured with the reaction gas as described above. The chamber is configured to provide thermal energy to the growth as described above. The reaction temperature is measured by a thermocouple connected to the susceptor. The susceptor holds a bulk wafer. It is conceivable that the growth temperature is slightly lower than the growth temperature described herein. Furthermore, the experiment was performed using the following parameters.

1. Bulk wafer:
Nonpolar, semipolar, or polar GaN-based material threading dislocation (TD) density <1E8 cm-2
Stacking defect (SF) density <1E4 cm-1
N-type silicon doping> lE17 cm-3

2. N-type epitaxial material:
Thickness <2um
(Al, Ga, In) N base material 950C <growth temperature <1050C
Silicon doping roughness: 2 nanometer RMS in 25 micron region

The inventors have demonstrated a high quality film with a surface roughness in the region of 25 microns of 2 nm RMS or less using high-speed growth technology. Of course, other changes, modifications, and alternatives are possible.

Although specific embodiments have been described in detail above, various modifications, alternative constructions, and equivalents may be used. As an example, the present invention can be applied to use of an autocassette MOCVD reactor. In this autocassette MOCVD reactor, the cassette holds two or more (or ten or more) single wafers or wafer platters for a multi-wafer reactor. In one or more embodiments, the epitaxial structure can form an LED device. The LED device can emit electromagnetic radiation in the range of 390-420 nm, 420-460 nm, 460-4500 nm, 500-600 nm, and the like. In certain embodiments, for example, pn diodes, Schottky diodes, transistors, high electron mobility transistors (HEMT), bipolar junction transistors (BJT), heterojunction bipolar transistors (HBT), metal semiconductor field effect transistors ( There are various devices such as MESFET), metal oxide semiconductor field effect transistor (MOSFET), metal insulator semiconductor heterojunction field effect transistor (MISHFET), and combinations thereof. In other embodiments, the method is applicable to laser diode devices (eg, those described in US Serial No. 12 / 759,273; Attorney Docket No. 027600-000210US). This document is incorporated by reference for all purposes. In one or more embodiments, the gallium and nitrogen containing material may be characterized by one or a variety of surface orientations (eg, nonpolar, semipolar, polar). Therefore, the above description and drawings do not limit the scope of the invention, which is defined by the following claims.

Claims (60)

A method for rapid growth of gallium and nitrogen containing materials comprising:
Providing a bulk gallium and nitrogen containing substrate having a surface region;
Forming a first epitaxial material of a first thickness on the surface region of the bulk gallium and nitrogen containing substrate, wherein the first epitaxial material is the surface of the bulk gallium and nitrogen containing substrate. Being formed pseudomorphically on the region;
Forming one or more second epitaxial materials on the first epitaxial material, wherein the one or more second epitaxial materials are configured to form a stack structure. ,
The total thickness of the stack structure is less than about 2 microns, and the stack structure characterizes at least a substantial portion of an epitaxial region of an optical or electrical device.
The method of claim 1, wherein the first epitaxial material is less than 1 micron.
The method of claim 1, wherein the first epitaxial material is less than 500 nm.
The method of claim 1, wherein the first epitaxial material is less than 100 nm.
The method of claim 1, wherein the one or more second epitaxial materials are less than 1 micron.
The method of claim 1, wherein the one or more second epitaxial materials are less than about 500 nm.
The method of claim 1, wherein the one or more second epitaxial materials are less than about 100 nm.
The method of claim 1, wherein the one or more second epitaxial materials are less than about 1000 nm.
The method of claim 1, wherein the first epitaxial material has a stacking defect density of 1E4 cm −1 or less.
2. The method according to claim 1, wherein the first epitaxial material has a threading dislocation of 1E8 cm−2 or less or 1E6 cm−2 or less.
The method of claim 1, wherein the first epitaxial material has a substantially uniform defect density from a first region to a second region.
The method of claim 11, wherein the substantially uniform defect density is essentially uniform.
The method of claim 11, wherein the substantially uniform defect density is completely uniform.
The method of claim 1, wherein the first epitaxial material and the surface region include an interface that is substantially free of one or more nucleation layers.
The method of claim 1, wherein the total thickness is less than about 1 micron.
The method of claim 1, wherein the total thickness is less than about 500 nm.
The method of claim 1, wherein the total thickness is less than about 200 nm.
The method of claim 1, wherein the stack structure is provided within a total growth time characterized by the formation of gallium and nitrogen containing epitaxial materials.
The method of claim 18, wherein the total growth time is less than 1.5 hours or less than 2 hours.
The method of claim 18, wherein the total growth time is less than 1 hour.
The method of claim 18, wherein the total growth time is less than 30 minutes.
The method of claim 18, wherein the total growth time is less than 15 minutes.
The method of claim 1, wherein the stack structure is provided within a chamber time characterized by a total growth time and a temperature ramping time.
24. The method of claim 23, wherein the chamber time is less than 1 hour or less than 1.5 hours.
24. The method of claim 23, wherein the chamber time is less than 30 minutes.
The method of claim 1, wherein the stack structure is provided within a cycle time characterized by chamber time and loading and unloading times.
27. The method of claim 26, wherein the cycle time is less than 2 hours or less than 2.5 hours.
27. The method of claim 26, wherein the cycle time is less than 1 hour.
27. The method of claim 26, wherein the cycle time is less than 30 minutes.
The method of claim 1, wherein the first epitaxial material and the one or more second epitaxial materials are deposited in a single chamber.
The method of claim 1, wherein the first epitaxial material and the one or more second epitaxial materials are each deposited in a plurality of chambers.
The method of claim 1, further comprising maintaining a temperature determined during formation of the first epitaxial material and the one or more second epitaxial materials.
The method of claim 1, further comprising using an autocassette MOCVD reactor, wherein the autocassette MOCVD reactor is configured to hold wafer platters for two or more single wafer or multi-wafer reactors. Method.
The method of claim 1, further comprising using an autocassette MOCVD reactor, wherein the autocassette MOCVD reactor is configured to hold wafer platters for three or more single wafer or multi-wafer reactors. Method.
2. The method of claim 1, further comprising using an autocassette MOCVD reactor, wherein the autocassette MOCVD reactor is configured to hold wafer platters for ten or more single wafer or multi-wafer reactors. Method.
The method of claim 1, wherein the epitaxial stack structure forms LED emission in a wavelength range of 390 to 420 nm.
The method of claim 1, wherein the epitaxial stack structure forms LED emissions in the wavelength range of 420-460 nm.
The method of claim 1, wherein the epitaxial stack structure forms LED emissions in the wavelength range of 460 to 500 nm.
The method of claim 1, wherein the epitaxial stack structure forms LED emissions in the wavelength range of 500-600 nm.
The method of claim 1, wherein the epitaxial stack structure forms a pn diode.
The method of claim 1, wherein the epitaxial stack structure forms a laser diode.
The method of claim 1, wherein the epitaxial stack structure forms a Schottky diode.
The method of claim 1, wherein the epitaxial stack structure forms a transistor.
The method of claim 1, wherein the epitaxial stack structure forms a high electron mobility transistor (HEMT).
The method of claim 1, wherein the epitaxial stack structure forms a bipolar junction transistor (BJT).
The method of claim 1, wherein the epitaxial stack structure forms a heterojunction bipolar transistor (HBT).
The method of claim 1, wherein the epitaxial stack structure forms a metal semiconductor field effect transistor (MESFET).
The method of claim 1, wherein the epitaxial stack structure forms a metal oxide semiconductor field effect transistor (MOSFET).
The method of claim 1, wherein the epitaxial stack structure forms a metal insulator-semiconductor heterojunction field effect transistor (MISHFET).
The method of claim 1, wherein the gallium and nitrogen containing substrate is characterized by a nonpolar surface orientation.
The method of claim 1, wherein the gallium and nitrogen containing substrate is characterized by a semipolar or polar surface orientation.
A method for rapid growth of gallium and nitrogen containing materials comprising:
Providing a bulk gallium and nitrogen containing substrate having a surface region;
Forming a first epitaxial material of a first thickness on the surface region of the bulk gallium and nitrogen containing substrate at a desired growth rate, the first epitaxial material comprising the bulk gallium and nitrogen Being formed pseudomorphically on the surface region of the containing substrate;
Forming one or more second epitaxial materials on the first epitaxial material, wherein the one or more second epitaxial materials are configured to form a stack structure. That way.
53. The method of claim 52, wherein the formation is maintained in a temperature range of about 950 ° C. to about 1200 ° C., and the desired growth rate is 4 microns / hour or more.
53. The method of claim 52, wherein the providing comprises selecting the bulk gallium and nitrogen containing substrate from an autocassette maintained in a chamber.
53. The method of claim 52, wherein the formation is provided in an atmospheric pressure MOCVD chamber.
53. The method of claim 52, wherein the gallium and nitrogen containing substrate is maintained at approximately atmospheric pressure during the formation.
53. The method of claim 52, wherein the first thickness of the first epitaxial material has a surface roughness at 5 x 5 square microns of about 2 nm RMS or less.
53. The method of claim 52, wherein the first thickness of the first epitaxial material is an n-type material.
53. The method of claim 52, wherein the second epitaxial material is a p-type material.
53. The method of claim 52, wherein the first epitaxial material has a stacking defect density of 1E4 cm-1 or less.