A molecular beam source furnace for dynamic control of source flux

Abstract

The application provides a molecular beam source furnace for dynamically controlling source flow, which is sequentially provided with a bottom layer source evaporation pre-heating device, an intermediate layer dynamic temperature compensation heating device and a top layer beam flow high-low temperature heating device from bottom to top of a source material container. Each layer respectively heats the source material. According to the epitaxial growth rate of the material, the power of the bottom layer source evaporation pre-heating device is reasonably set; and according to the material component or material doping change, the power of the intermediate layer dynamic temperature compensation heating device and the top layer beam flow high-low temperature heating device is reasonably adjusted, so as to solve the problem of rapidly and dynamically adjusting the doping metal source flow in a molecular beam epitaxial growth system.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of thin film preparation, and particularly relates to a molecular beam source furnace for dynamically controlling the flow of a doped metal source in a molecular beam epitaxy growth process. BACKGROUND

[0002] Molecular beam epitaxy is a high-precision thin film preparation technology, and a source furnace storing a material required by a thin film is a key component for controlling the quality of thin film growth. The molecular beam epitaxy technology heats the source material to a high temperature through the source furnace, and deposits the formed molecular beam flow on a suitable substrate. In the growth process, different source furnaces are opened and switched to realize thin film materials with different material components and different doping concentrations. The temperature of the source furnace affects the saturation vapor pressure of the material, and further affects the concentration of the required material in the unit time molecular beam flow. The early source furnace adopts single-temperature-zone heating, and only the bottom of the source furnace is heated. On the one hand, it is difficult to control the uniformity of the internal material temperature of the single-zone-heating source furnace, and on the other hand, the top of the source furnace is at a low temperature, and it is easy to condense large-particle solid or liquid source materials in the process. These large particles are deposited on the growth interface during material growth, resulting in material defects and affecting the material quality. People have developed double-temperature-zone heating, and a heater is configured at the top of the source furnace, which can greatly reduce material defects. This double-temperature-zone heating method has developed into various combinations. In addition, for some materials as the main component of the thin film, the flow of the molecular beam generated by ordinary heating is not enough, so people have developed an electron beam heating source furnace. The electron beam directly heats the source material to generate a sufficient amount of source molecular beam.

[0003] With the increasing complexity of device structures and the diversification of thin film components, the process control requirements are also more and more precise. Multiple source furnaces are required to generate molecular beams in the molecular beam system, and the same source also needs to quickly change the beam flow according to the changes of the thin film structure and the process. In particular, the doped source material needs to be quickly and accurately regulated, which puts higher requirements on the design of the molecular beam epitaxy system, especially the source furnace system. SUMMARY

[0004] The application provides a molecular beam source furnace for dynamically controlling the source flow to solve the problem of quickly and dynamically adjusting the flow of the doped metal source in the molecular beam epitaxy growth system.

[0005] The molecular source furnace for dynamically controlling source flow provided by the application has the technical scheme that: in the source material container, a bottom layer source evaporation pre-heating device, an intermediate layer dynamic temperature compensation heating device and a top layer beam high-low temperature heating device are sequentially arranged from the bottom to the top; the bottom layer source evaporation pre-heating device is a two-section resistance heating sheet arranged outside the source material container and a ceramic protective shell outside the two-section resistance heating sheet; the intermediate layer dynamic temperature compensation heating device is arranged at the middle position of the source material container and includes a middle electromagnetic emitter arranged outside the source material container and a middle magnetic metal disc arranged above the source material inside the source material container; and the top layer beam high-low temperature heating device is arranged at the upper position of the source material container and includes an upper electromagnetic emitter arranged outside the source material container and an upper magnetic metal disc arranged above the middle magnetic metal disc inside the source material container. The process flow is that: the bottom layer source evaporation pre-heating device melts the source material arranged in the source material container; the intermediate layer dynamic temperature compensation heating device heats the middle magnetic metal disc through the middle electromagnetic emitter to compensate and control the temperature of the sublimated source material vapor; and the top layer beam high-low temperature heating device heats the upper magnetic metal disc through the upper electromagnetic emitter, and the heating power is adjusted in real time according to the material epitaxial growth process. When acceleration growth or increase of the source material concentration is needed, the heating power of the top layer beam high-low temperature heating device is higher than that of the intermediate layer dynamic temperature compensation heating device; when deceleration growth or decrease of the source material concentration is needed, the heating power of the top layer beam high-low temperature heating device is lower than that of the intermediate layer dynamic temperature compensation heating device, and part of the source material will be condensed and deposited and cannot reach the substrate.

[0006] Further, the heating power of the bottom layer source evaporation pre-heating device, the intermediate layer dynamic temperature compensation heating device and the top layer beam high-low temperature heating device can be adjusted in real time according to the material epitaxial growth process.

[0007] Further, the middle magnetic metal disc and the upper magnetic metal disc are respectively arranged as four, and are respectively supported by a middle ceramic support frame, a middle ceramic protective shell and an upper ceramic support frame and an upper ceramic protective shell, and the materials of the middle ceramic support frame, the middle ceramic protective shell, the upper ceramic support frame and the upper ceramic protective shell include alumina or boron nitride, and the materials of the middle magnetic metal disc and the upper magnetic metal disc are composed of high-temperature magnetic steel, iron, cobalt, nickel or a combination thereof.

[0008] Further, the material of the two-section resistance heating sheet includes tungsten, molybdenum or a combination thereof, and the material of the ceramic protective shell includes alumina or boron nitride.

[0009] Further, the included angle of the projection of the two ceramic support frames of the middle magnetic metal disc and the upper magnetic metal disc on the bottom surface of the source furnace is 45°.

[0010] Further, the heating power of the intermediate layer dynamic temperature compensation heating device is dynamically changed in time domain, and the power waveform includes square wave, triangular wave or sinusoidal wave.

[0011] The advantage of the present application is that the power of the bottom layer source evaporation preheating device can be reasonably set according to the basic growth rate of the material, and the power of the intermediate layer dynamic temperature compensation heating device and the top layer beam high-low temperature heating device can be reasonably adjusted according to the material component or material doping change, so as to realize dynamic control of the molecular beam source furnace growth epitaxial film. BRIEF DESCRIPTION OF DRAWINGS

[0012] Fig. 1 is a schematic structure side view cross-sectional view of the present application.

[0013] Fig. 2 is a schematic structure top view cross-sectional view of the present application.

[0014] Fig. 3 is a schematic structure intermediate layer top view cross-sectional view of the present application.

[0015] Fig. 4 is a schematic structure bottom layer top view cross-sectional view of the present application.

[0016] Reference signs: 101, 103, 105, 107 upper ceramic protective shell, 201, 203, 205, 207 intermediate ceramic protective shell, 102, 104, 106, 108 upper magnetic metal disc, 202, 204, 206, 208 intermediate magnetic metal disc, 109 upper ceramic support frame, 209 intermediate ceramic support frame, 110 upper electromagnetic emitter, 210 intermediate electromagnetic emitter, 301 two-section resistance heating sheet, 302 ceramic protective shell, 401 source material container, 402 source material. DETAILED DESCRIPTION

[0017] Embodiment one: according to figures 1-4, in the molecular beam epitaxy equipment installed with the dynamic control source flow source furnace of the present application, Mg doped GaN is grown, a clean sapphire substrate is placed on the molecular beam epitaxy substrate holder, the cavity vacuum degree is pumped to a value suitable for growth, the Ga source furnace is heated, and an undoped GaN film is grown on the substrate. The Mg source material 402 is melted by the bottom layer source evaporation preheating device, the middle layer dynamic temperature compensation heating device heats the middle magnetic metal wafers 202, 204, 206 and 208 through the middle electromagnetic emitter 210, thereby compensating and regulating the temperature of the sublimated Mg source material 402 vapor, the top beam high-low temperature heating device heats the upper magnetic metal wafers 102, 104, 106 and 108 through the upper electromagnetic emitter 110, by adjusting the power of the upper electromagnetic emitter 110 to a square wave, the period is 4s, and the duty cycle is 50%, so that the Mg concentration appears a certain gradient change in the growth direction, and δ-doped pGaN is obtained.

[0018] The bottom layer source evaporation preheating device includes a two-stage resistance heating sheet 301, which is composed of tungsten, molybdenum or a combination thereof, and the ceramic protective shell 302 is made of aluminum oxide or boron nitride. The middle magnetic metal wafer and the upper magnetic metal wafer are respectively arranged as 4, and are respectively provided with a middle ceramic support 109, a middle ceramic protective shell 201, 203, 205, 207 and an upper ceramic support 209, an upper ceramic protective shell 101, 103, 105, 107 for supporting, the materials of the middle ceramic support 109, the middle ceramic protective shell 201, 203, 205, 207 and the upper ceramic support 209, the upper ceramic protective shell 101, 103, 105, 107 include aluminum oxide or boron nitride, and the materials of the upper magnetic metal wafer 102, 104, 106, 108 and the middle magnetic metal wafer 202, 204, 206, 208 are composed of high-temperature magnetic steel, iron, cobalt, nickel or a combination thereof. The included angle of the projection of the upper ceramic support 109 and the middle ceramic support 209 on the bottom surface of the source furnace is 45°.

[0019] The above embodiments mainly illustrate the process method for growing δ-doped pGaN by the dynamic control source flow source furnace of the present application, although only one embodiment of the present application is described, but the present application can be implemented in many other ways without deviating from the main idea and scope. Therefore, it should be understood that the above embodiments are not limited to the present application, and any modification, replacement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A molecular beam source furnace with dynamically controlled source flow rate, characterized in that... In the source material container, from bottom to top, a bottom layer source evaporation pre-heating device, an intermediate layer dynamic temperature compensation heating device and a top layer beam high-low temperature heating device are arranged in sequence; the bottom layer source evaporation pre-heating device is used for melting the source material in the source material container, and its structure is that a two-section resistance heating sheet and a ceramic protective shell outside the two-section resistance heating sheet are arranged on the periphery of the source material container; the intermediate layer dynamic temperature compensation heating device is arranged at a middle position of the source material container, and is used for heating a magnetic metal disc through an electromagnetic emitter thereof, so as to compensate and control the temperature of the sublimated source material vapor; the structure of the intermediate layer dynamic temperature compensation heating device comprises a middle electromagnetic emitter on the periphery of the source material container and a middle magnetic metal disc inside the source material container above the source material; the top layer beam high-low temperature heating device is arranged at an upper position of the source material container, and is used for heating a magnetic metal disc through an electromagnetic emitter thereof, and adjusting the heating power in real time according to the material epitaxial growth process to control the amount of source material vapor reaching the substrate; the structure of the top layer beam high-low temperature heating device comprises an upper electromagnetic emitter on the periphery of the source material container and an upper magnetic metal disc inside the source material container above the middle magnetic metal disc; when it is needed to increase the source material beam, the heating power of the top layer beam high-low temperature heating device is controlled to be higher than the heating power of the intermediate layer dynamic temperature compensation heating device; when it is needed to reduce the source material beam, the heating power of the top layer beam high-low temperature heating device is controlled to be lower than the heating power of the intermediate layer dynamic temperature compensation heating device, so that part of the source material vapor is condensed.

2. A molecular beam source oven for dynamically controlling source flux according to claim 1, wherein The heating powers of the bottom layer source evaporation pre-heating device, the intermediate layer dynamic temperature compensation heating device and the top layer beam high-low temperature heating device can be adjusted in real time according to the material epitaxial growth process.

3. A molecular beam source oven for dynamically controlling source flux according to claim 1, wherein The middle magnetic metal disc and the upper magnetic metal disc are respectively arranged in four, and are respectively supported by a middle ceramic support frame, a middle ceramic protective shell and an upper ceramic support frame, and an upper ceramic protective shell, and the materials of the middle ceramic support frame, the middle ceramic protective shell and the upper ceramic support frame and the upper ceramic protective shell comprise alumina or boron nitride, and the materials of the middle magnetic metal disc and the upper magnetic metal disc are composed of high-temperature magnetic steel, iron, cobalt, nickel or a combination thereof.

4. The molecular beam source oven for dynamically controlling source flux of claim 1, wherein The material of the two-section resistance heating sheet comprises tungsten, molybdenum or a combination thereof, and the material of the ceramic protective shell comprises alumina or boron nitride.

5. A molecular beam source oven for dynamically controlling source flux according to claim 3, wherein The included angle of the projection of the middle magnetic metal disc and the upper magnetic metal disc on the bottom surface of the source furnace is 45°.

6. A molecular beam source oven for dynamically controlling source flux according to claim 1, wherein The heating power of the intermediate layer dynamic temperature compensation heating device is dynamically changed in the time domain, and the power waveform comprises a square wave, a triangular wave or a sine wave.

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