CN103789823B - A kind of nitride semi-conductor material vapour phase epitaxy reactor design and method - Google Patents

Abstract

The invention discloses a reactor design for vapor phase epitaxy (HVPE) of nitride semiconductor materials. It includes an axisymmetric cylindrical reaction chamber, a concentric ring nozzle, a heater, a graphite boat and a substrate, etc.; the graphite boat and the substrate are heated by resistance wire or infrared light; the outer wall of the bottom of the chamber is tangentially arranged with three There are six gas outlet passages with rectangular cross-section; a concentric ring buffer zone is set between the outlet passage and the inner wall of the chamber; a concentric ring collecting channel is arranged on the periphery of the outlet passage; The flow channels are all through. The design of the reactor of the present invention enables the reactant gas to form a micro-swirl flow in the effective growth area of the substrate, thereby significantly improving the thickness of the epitaxial growth and the uniformity of its components; because the graphite boat rotating device and the The auxiliary components not only simplify the device, save energy, and facilitate maintenance, but also eliminate the adverse effects of unstable rotational motion on epitaxial growth.

Description

Design and method of a reactor for vapor phase epitaxy of nitride semiconductor materials

technical field

The invention belongs to the technical field of semiconductors, and relates to a hydride vapor phase epitaxy (HVPE) growth system, such as a nitride semiconductor material growth system, in particular to the design and method of a reactor for Group III nitride vapor phase epitaxy.

Background technique

III-V nitride semiconductor materials are new materials that have received much attention in the semiconductor field at home and abroad in recent years, mainly represented by GaN, InGaN, AlGaN and other alloy materials. Group III nitride semiconductors have been found to play an increasingly important role in the development and fabrication of short-wavelength light-emitting diodes (LEDs), laser diodes (LDs), and electronic devices.

There are many methods for growing GaN materials: such as metal organic vapor phase epitaxy (MOCVD), GaN single crystal growth under high temperature and high pressure, liquid phase growth method, molecular beam epitaxy (MBE), sublimation method and hydride vapor phase epitaxy (HVPE), etc. Because the GaN material is limited by its own physical properties, it is difficult to grow its single crystal, so the heteroepitaxial method is mainly used to grow GaN at present. Hydride vapor phase epitaxy has a high growth rate and lateral-to-vertical epitaxy ratio, and can be used for homoepitaxial growth of self-supporting GaN substrates, so it has attracted extensive attention and research in recent years.

Hydride vapor phase epitaxy (HVPE) at this stage is still limited to the use of small-scale reactors, such as growing 3 to 6 2-inch GaN wafers at a time. The traditional HVPE growth system usually adopts a horizontal reactor design, the substrate support plate is usually at a certain angle to the horizontal plane, and the nozzle structure mostly adopts a circular nozzle. This reactor design, when the substrate area increases or the effective growth area expands , the distribution uniformity of the reactants on the substrate surface becomes poor, resulting in poor uniformity of the growth thickness of the GaN wafer, so it is not suitable for the material growth of multiple substrates or large-size single substrates. In the hanging vertical or hanging inverted HVPE growth system, since the reactor can be designed as an axisymmetric cylindrical shape, and the nozzle can be designed as a circular tube or concentric ring tube structure, the flow field and concentration ratio of the injected gas The formula system is easy to be uniform, so that the quality of material growth can be improved to a certain extent.

The most important indicator of GaN wafer preparation is the uniformity of its growth thickness and its composition. The key to obtaining high-quality wafers lies in the rational design of the reactor and how to create the best precursor concentration field and temperature field. Usually, the uniform temperature field is achieved by auxiliary heating or infrared light irradiation on the graphite boat, and the uniform concentration field (including radial and circumferential) of the precursor is obtained through the ingenious design of the nozzle. However, at this stage, there is no ideal gas inlet structure that can obtain uniform precursor distribution in the radial direction, and uniform precursor distribution in the circumferential direction is mainly achieved by rotating the graphite boat placed in its groove. In the reactor of the existing HVPE system, the rotation mechanism of the graphite boat is relatively complicated. For example, a rotating shaft needs to be used between the power source motor and the graphite boat to realize power transmission to make the graphite boat rotate; it is necessary to accurately control the rotation speed of the rotating shaft , to ensure the stability of the substrate rotation; and the connection mechanism between the rotating shaft and the bottom flange of the reactor chamber must not only ensure the unobstructed rotation of the rotating shaft, but also ensure the vacuum condition in the reactor chamber. According to the existing reactor system, it is difficult to ensure the stability of the system under the above conditions and create an optimal concentration field of the precursor.

Based on the above reasons, in order to further simplify the structure, facilitate maintenance, save energy consumption, and improve the quality of material growth, it is necessary to improve the technical design of the reactor.

Contents of the invention

The main purpose of the present invention is to provide a reactor design and method for vapor phase epitaxy (HVPE) of nitride semiconductor materials. For this reason, it is necessary to improve and innovate the existing reactors for vapor phase epitaxy (HVPE).

The invention proposes a reactor design and method for vapor phase epitaxy of nitride semiconductor materials. The main technical solution is: in the existing hanging vertical or hanging inverted HVPE system, the graphite boat and substrate rotation are omitted. The motor, transmission shaft and auxiliary components simplify the equipment; the outlet channel of the reaction gas in the reaction chamber is modified, and the outlet channel is drawn from the tangent direction of the outer wall of the chamber. The cross-section of the outlet channel is rectangular. Depending on the gas flow rate, the gas outlet direction of each channel is clockwise or counterclockwise of the cavity cross section (or graphite boat disc). In this way, the reactant gas forms a centrifugal micro-swirl flow on the surface of the substrate or the effective growth area, which is beneficial to improving the epitaxial growth thickness of the nitride material and the uniformity of its components.

Specifically, the reactor for vapor phase epitaxy of nitride materials in the present invention includes a nozzle, a chamber, a graphite disk, a heating device, and the like. The reactor nozzle and cavity structure are made of high-purity quartz material; the reactor is designed as an axisymmetric cylinder, the nozzle is a concentric ring tube structure, and the length of the inner tube is slightly shorter than the outer tube; the reactor cavity is surrounded by resistors Wire heating, and several different temperature zones are designed in the axial direction of the reactor. The graphite boat and its upper substrate are individually heated by resistance wire or infrared light auxiliary heating; the reaction gas mixture in the reactor cavity passes through the cavity The gas outlet channel at the bottom is discharged. The cross section of the outlet channel is designed as a rectangle. The number and size of the outlet channels depend on the gas flow rate, and the exhaust direction of each outlet channel is clockwise along the cross section of the cavity (or the graphite boat disc). Direction or counterclockwise, the reactants form a centrifugal micro-swirl flow on the graphite boat and the surface of the substrate. In order to further expand the effective area of the growth material, a concentric ring buffer zone is set between the mixed gas outlet and the inner wall of the reactor chamber to expand the effective area of epitaxial growth and at the same time weaken the violent flow of fluid at each outlet. The quality of epitaxial growth adverse effects, the height of the buffer zone is consistent with the height of each outlet channel. On the periphery of the outlet of the reactor, a concentric ring-shaped collecting channel is also provided with a rectangular or circular cross-section. The collecting channel is designed with only one outlet to collect the gases from the outlets of the reaction chamber in one place for centralized treatment.

The design and method of a reactor for vapor phase epitaxy of nitride semiconductor materials proposed by the present invention saves the graphite boat rotation, power device and accessory components in the existing HVPE system reactor, not only greatly simplifying the device, saving energy consumption, and being convenient. Maintenance, moreover, eliminate the adverse effect of graphite boat rotation instability on the growth material on the substrate; the design of the reactor of the present invention makes the reactant gas form a kind of centrifugal micro-swirl flow on the large-scale substrate surface or large-area effective growth area, Thus, the growth thickness of the nitride material and its composition uniformity are significantly improved.

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Description of drawings

Fig. 1 is a sectional view of a reactor for vapor phase epitaxy of nitride semiconductor materials according to the present invention.

Fig. 2 is a top view of a reactor for vapor phase epitaxy of nitride semiconductor materials in Embodiment 1 of the present invention.

Fig. 3 is a schematic structural diagram of a reactor for vapor phase epitaxy of nitride semiconductor materials in Embodiment 2 of the present invention, wherein:

3A is a cross-sectional view of the reactor;

3B is a top view of the reactor.

Fig. 4 is a plan view of a reactor for vapor phase epitaxy of nitride semiconductor materials in Embodiment 3 of the present invention.

detailed description

Embodiment 1: As shown in Figure 1, in the suspended vertical HVPE system, the precursor gas and the isolation gas are injected from the concentric ring nozzle 1 at the top of the reactor, and the length of the inner circular tube of the precursor channel is slightly shorter than the length of the peripheral circular tube The periphery of the nozzle 1 is an axisymmetric cylindrical reactor cavity 2; the outer wall of the cavity is wrapped with a resistance wire heater 3 and covers the entire cavity in the axial direction; a graphite boat disc 4 is placed directly below the nozzle 1, and graphite The upper surface of the boat disc 4 is provided with a plurality of grooves, and substrate wafers are loaded in the grooves. The temperature of the graphite boat disc 4 and the substrate is maintained at 1070° C. by heating the resistance wire 5 alone or by infrared light irradiation. As shown in Figure 2, the reacted mixed gas in the reactor is discharged through the outlet channel 6 arranged on the outer edge of the bottom of the cavity, and the outlet channel 6 is drawn out in the tangential direction of the outer wall of the cavity 2, and the cross section of the outlet channel is rectangular, its The number is set to four, and the exhaust direction of each outlet channel is consistent, and they are all along the counterclockwise or clockwise tangential direction of the cavity cross section, so that the reactants form a centrifugal micro-swirl flow above the effective growth area on the substrate surface to facilitate the reaction. The generated nitride is uniformly deposited on the surface of the substrate, and finally a high-quality nitride semiconductor wafer is obtained.

Embodiment 2: As shown in Figures 3A and 3B, the reactor is further improved on the basis of Embodiment 1. In order to further expand the effective area of the growable material, a hole is set between the mixed gas outlet channel 6 and the inner wall of the cavity 2. Concentric ring buffer zone 7, the height of the buffer zone 7 is consistent with the height of each gas outlet channel 6, this design expands the effective area of the substrate where materials can grow, and at the same time weakens the violent flow of fluid at each outlet to uniform growth of nitride materials on the substrate adverse effects.

Embodiment 3: As shown in Figure 4, in combination with the advantages of Embodiments 1 and 2, the reactor has been further improved, and a concentric ring with the axisymmetric cavity is arranged on the periphery of the gas outlet channel 6 after the reactor reaction Collecting channel 8, the cross section of said collecting channel 8 is rectangular or circular, and each reaction gas outlet channel 6 is connected with the collecting channel 8, and the collecting channel 8 is only designed with one outlet 9, so as to discharge the gas from each outlet channel. The gas is collected in one place for centralized processing.

The reactor for vapor phase epitaxy of nitride semiconductor materials proposed by the present invention replaces the graphite boat rotating device, auxiliary components and driving motors in the existing HVPE growth system by adopting a structural design of tangential discharge for the gas outlet channel after reaction, not only It greatly simplifies the device, saves energy consumption, facilitates maintenance, and eliminates the rotation instability of the graphite boat in the existing reactor (which is mainly manifested in the two aspects of shaking during the movement and whether the substrate can maintain the level). growth thickness and component uniformity, and more importantly, this design mechanism makes the reactant form a centrifugal micro-swirl flow in the effective growth area of the graphite boat and the substrate surface, so that the nitride produced by the reaction is on the substrate Uniform deposition on the surface can obtain high-quality nitride semiconductor wafers, and the area of the effective growth region is enlarged to facilitate mass production.

The above descriptions are only some specific embodiments of the present invention, so they cannot be used to limit the patent scope of the present invention. It should be noted that, for the technology in this field, any modification, equivalent replacement, improvement, etc. made without departing from the concept of the present invention shall be included in the protection scope of the present invention.

Claims (6)

1. a nitride semi-conductor material vapour phase epitaxy reactor, it is characterized by: reactor shower nozzle adopts donut structure, and described shower nozzle inner circle length of tube is less than outer toroid length of tube, it is graphite boat disk immediately below shower nozzle, this shower nozzle periphery is the reactor of rotational symmetry cylinder shape cavity configuration, and described cavity periphery resistance heater wraps up and is covered to whole cavity vertically; In described reactor, graphite boat is fixed on cavity bottom central authorities, and resistance wire heater heats used separately by graphite boat disk; Be arranged with reactant gases discharge-channel outside described reactor cavity bottom, channel outlet is along cylinder shape chamber outer wall tangential direction, and number of channels and size are determined according to reactant gases total amount; The tangential in design of described channel outlet makes reactant above graphite boat and the effective growth district of substrate, form a kind of centrifugal eddy flow that declines.

2. reactor according to claim 1, is characterized in that: wherein the graphite boat heats mode can also adopt infrared light boosting.

3. reactor according to claim 1, it is characterized in that: described reactant gases discharge-channel, its cross section is rectangle, its quantity be 2 ~ 5 not etc., the discharge directions of its each discharge-channel is all along the clockwise direction or counterclockwise of cavity cross section (or graphite boat disk).

4. reactor according to claim 1, it is characterized by: between reactor bottom end outlet passage and cavity inner wall, arrange a donut buffer strip, described buffer strip height is consistent with each Gas outlet channels height.

5. a nitride semi-conductor material vapour phase epitaxy reactor, it is characterized by: reactor shower nozzle adopts donut structure, and described shower nozzle inner circle length of tube is less than outer toroid length of tube, it is graphite boat disk immediately below shower nozzle, this shower nozzle periphery is the reactor of rotational symmetry cylinder shape cavity configuration, and described cavity periphery resistance heater wraps up and is covered to whole cavity vertically; In described reactor, graphite boat is fixed on cavity bottom central authorities, and resistance wire heater heats used separately by graphite boat disk; Reaction gas outlet passage is arranged with outside described reactor cavity bottom, one concentric ring type collection flow channels is set in this exit passageway periphery, described Exit to all routes and collection flow channels are all through, collection flow channels cross section is rectangle or circle, collection flow channels only designs an outlet, focuses on after institute's Exhaust Gas collects a place.

6. reactor described in claim any one of claim 1-5, is further characterized in that: this reactor is applied to and hangs vertical HVPE system, invert support HVPE system.