A molecular beam epitaxial thin film growth system with integrated in-situ measurement

Abstract

The present invention discloses a molecular beam epitaxial thin film growth system with integrated in-situ measurement, which belongs to the field of semiconductor thin film measurement technology. The growth system includes a vacuum reaction chamber, which is provided with an installation port and the bottom part or all of which is made of a light-transmitting material, for providing a reaction environment, and the installation port is used to install a furnace source; a sample stage, which is arranged in the vacuum reaction chamber; a first driving component, which is arranged outside the vacuum reaction chamber and connected to the sample stage through a connecting rod, for driving the sample stage and adjusting the position of the sample stage; a wide spectrum monitoring device, which is arranged at the bottom of the vacuum reaction chamber, includes a second driving component and a monitoring component; the monitoring component driven by the second driving component keeps synchronous movement with the sample on the sample stage driven by the first driving component to obtain information on thin film growth. The present invention can realize non-contact, in-situ online monitoring of semiconductor film thickness, and obtain accurate film thickness data without affecting film growth.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor thin film measurement, and in particular to a molecular beam epitaxial thin film growth system integrating in-situ measurement. Background Art

[0002] Traditionally, molecular beam epitaxy (MBE) technology has been widely used as an important thin film growth technology in the field of semiconductor device preparation. MBE technology deposits atoms or molecules layer by layer under vacuum conditions, which can achieve precise control of semiconductor material films. Therefore, it is widely used in the preparation of high-performance electronic devices, optoelectronic devices and quantum devices.

[0003] However, in practical applications, the thickness uniformity of semiconductor films is one of the key factors affecting device performance and reliability. At present, the monitoring of film thickness uniformity mainly relies on indirect measurement methods, such as probe testing, surface topology analysis, or post-microscope analysis. However, these methods have disadvantages such as high time cost, complex operation, and inability to monitor in real time, which limits the real-time control and optimization of the film growth process. In order to solve the above problems, some real-time monitoring methods based on optical principles have emerged in recent years, such as reflected high-energy electron diffraction, laser interferometer, atomic force microscopy, X-ray reflection, electron beam optical excitation, etc. However, these methods have challenges in practical applications such as complex equipment, high cost, and cumbersome data processing, which limits their wide application in industrial production.

[0004] Therefore, in response to the need for monitoring the uniformity of semiconductor film thickness, there is an urgent need for a system that can achieve in-situ, real-time, and efficient monitoring to improve the control accuracy and production efficiency of the semiconductor film growth process. Summary of the invention

[0005] The purpose of the present invention is to monitor the uniformity of film thickness during the growth process, thereby adjusting the growth process parameters online in real time, improving the uniformity of film thickness, and reducing the impact of film thickness non-uniformity on the performance, stability and reliability of materials and devices.

[0006] In order to achieve the above object, the present invention provides a molecular beam epitaxial thin film growth system with integrated in-situ measurement, comprising:

[0007] A vacuum reaction chamber is provided with an installation port and the bottom part or the whole of which is made of a light-transmitting material, and is used to provide a reaction environment. The installation port is used to install a furnace source;

[0008] A sample stage, arranged in the vacuum reaction chamber;

[0009] A first driving assembly, disposed at the top of the outside of the vacuum reaction chamber and connected to the sample stage through a connecting rod, for driving the sample stage and adjusting the position of the sample stage;

[0010] A wide spectrum monitoring device, disposed at the bottom of the vacuum reaction chamber, comprises a second driving component and a monitoring component;

[0011] During operation, the monitoring component driven by the second driving component and the sample on the sample stage driven by the first driving component maintain relative motion to obtain information on thin film growth.

[0012] Furthermore, the monitoring assembly includes a fixing component, a polarizing light path, a light source, a polarizing light path, and a detector;

[0013] The fixing part includes a plurality of movable epitaxial ends above, the polarizing optical path and the light source and the analyzing optical path and the detector are installed on different epitaxial ends, the light beam generated by the light source generates a light beam with a specific polarization direction through the polarizing optical path to irradiate the sample surface, the analyzing optical path is used to analyze the polarization spectrum information of the reflected light generated by the sample, and the detector is used to receive, measure and output the polarization spectrum information of the reflected light;

[0014] The second driving assembly comprises a translation component, a rotation component and a lifting component respectively connected to the fixed component, and a workbench is further arranged between the rotation component and the translation component;

[0015] Wherein, the sample stage and the fixing component have the same axis.

[0016] Furthermore, the monitoring component driven by the second driving component maintains synchronous movement with the sample on the sample stage driven by the first driving component, and the information on thin film growth is obtained while ensuring that the distance between the light source and the test point on the sample surface is constant while considering the influence of nonlinear disturbances.

[0017] Furthermore, the method of ensuring that the distance between the light source and the test point on the sample surface is constant while considering the influence of nonlinear disturbance is specifically as follows:

[0018]

[0019] The three-dimensional coordinate system is constructed with the initial positions of the sample stage and the fixed components, D(t) is the distance between the light source and the test point on the sample surface; n is the number of tests, n = 1, 2, 3, ...; r n is the distance from the light source to the origin; r n is the distance from the test point to the origin; t is the time; θ n (t) is the angle of the light source; θ n is the angle of the test point; H is the vertical distance between the light source and the sample stage; α is the amplitude of the sinusoidal perturbation; β is the frequency of the sinusoidal perturbation; γ is the initial amplitude of the exponential decay; δ is the speed of the exponential decay; the corresponding parameters at time t can be measured in real time.

[0020] Furthermore, the wide spectrum monitoring device also includes a processing and display component;

[0021] The processing and display component is used to receive and process the signal output by the detector, and perform data analysis and result display.

[0022] Furthermore, a portion of the bottom end of the vacuum reaction chamber is extended inward to form an extended portion to provide space for installing the wide spectrum monitoring device;

[0023] The extension portion is made of light-transmitting material.

[0024] Furthermore, the extended height is 1 / 4 to 1 / 3 of the height of the vacuum reaction chamber.

[0025] Furthermore, a cold pump is installed on the side wall of the vacuum reaction chamber, and the cold pump is used to maintain the vacuum degree inside the chamber.

[0026] Furthermore, a reflection-type high-energy electron diffraction device is also provided on the side wall of the vacuum reaction chamber.

[0027] The present invention also provides the application of the above-mentioned molecular beam epitaxial thin film growth system with integrated in-situ measurement to in-situ monitoring of film thickness and doping concentration when growing semiconductors on the surface of a sample.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The growth system of the present invention obtains information on film growth by maintaining relative motion between a monitoring component driven by a second driving component and a sample on a sample stage driven by a first driving component, thereby realizing non-contact, in-situ online monitoring of semiconductor film thickness and obtaining accurate film thickness data without affecting film growth.

[0030] The growth system of the present invention is applicable to various materials and growth conditions and has strong versatility and applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 The schematic diagram of the structure of the molecular beam epitaxial thin film growth system with integrated in-situ measurement of the present invention is shown;

[0033] Figure 2The schematic diagram of the structure of the wide spectrum monitoring device of the present invention is shown;

[0034] Figure 3 The working flow chart of the molecular beam epitaxial thin film growth system with integrated in-situ measurement of the present invention is shown;

[0035] Figure 4 A schematic diagram of detection by the wide spectrum monitoring system of the present invention is shown;

[0036] Description of reference numerals:

[0037] 1. Vacuum reaction chamber; 2. Sample stage; 3. First driving assembly; 31. Rotation control component; 32. Lifting control component; 4. Broad spectrum monitoring device; 41. Housing; 42. Monitoring assembly; 421. Fixing component; 422. Polarizing light path; 423. Light source; 424. Polarizing light path; 425. Detector; 43. Second driving assembly; 431. Translation component; 432. Rotation component; 433. Lifting component; 434. Workbench; 44. Processing and display component; 441. Computer; 442. Display screen; 5. First furnace source; 6. Second furnace source; 7. Sample transfer port; 8. Second gate valve; 9. Cold pump; 10. First gate valve; 11. High energy electron gun; 12. Fluorescent screen; 13. Sample; 14. Extension part. DETAILED DESCRIPTION

[0038] The following will be combined with the specific embodiments of the present invention and the drawings of the specification to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] Example

[0040] like Figure 1 As shown, a molecular beam epitaxial thin film growth system with integrated in-situ measurement includes a vacuum reaction chamber 1, a sample stage 2 located in the vacuum reaction chamber 1, a first driving component 3 and a wide spectrum monitoring device 4.

[0041] The side wall of the vacuum reaction chamber 1 is provided with an installation port, a sample transfer cavity, a sample transfer port 7, a cold pump 9, and a reflection high-energy electron diffraction device, and a bottom portion of the vacuum reaction chamber 1 is extended inward to form an extension portion 14, and the extension portion 14 provides space for the installation of the wide spectrum monitoring device 4. The extension height is 1 / 4 to 1 / 3 of the height of the vacuum reaction chamber 1, and the material of the extension portion 14 is a light-transmitting material. Among them, the installation port is used to install the furnace source, the furnace source includes a first furnace source 5 and a second furnace source 6, the installation port and the vacuum reaction chamber 1 axially form a point angle to ensure uniform deposition of the growing material; the sample transfer port 7 is connected to the vacuum reaction chamber 1 through a flange and a sealing ring, and a second gate valve 8 is provided at the connection. The sample 13 can be transferred from the sample transfer chamber to the sample stage 2 through a ring manipulator, wherein the sample stage 2 can also heat the sample 13; the cold pump 9 is connected to the vacuum reaction chamber 1 through a flange and a sealing ring to maintain the vacuum degree inside the vacuum reaction chamber 1; a first gate valve 10 is provided at the connection between the vacuum reaction chamber 1 and the cold pump 9, and the first gate valve 10 is used to control the pressure atmosphere inside the vacuum reaction chamber 1 and protect the cold pump 9; the reflection high-energy electron diffraction device includes a high-energy electron gun 11 and a fluorescent screen 12.

[0042] The first driving assembly 3 is disposed at the top of the outside of the vacuum reaction chamber 1 and connected to the sample stage 2 through a connecting rod, and is used to drive the sample stage 2 and adjust the position of the sample stage 2. The first driving assembly 3 includes a rotation control component 31 and a lifting control component 32, which are used to control the rotation and lifting of the sample stage 2 respectively. The rotation control component 31 includes a stepper motor, a turntable, a transmission device and a controller; the lifting control system includes a stepper motor, a linear guide rail, a transmission device and a controller.

[0043] The wide spectrum monitoring device 4 is arranged at the bottom of the vacuum reaction chamber 1, and includes a second driving component 43, a monitoring component 42, a housing 41 and a processing display component 44. The second driving component 43 and the monitoring component 42 are arranged in the housing 41, the upper end of the outer shell 41 abuts against the extension portion 14 of the vacuum reaction chamber 1, and the lower end of the outer shell 41 is located below the bottom of the vacuum reaction chamber 1. Figure 2As shown, the monitoring assembly 42 includes a fixed component 421, a polarizing optical path 422, a light source 423, a polarizing optical path 424, and a detector 425. The upper portion of the fixed component 421 includes a plurality of movable epitaxial ends. In this embodiment, there are two epitaxial ends. The fixed component 421 presents a "Y"-shaped structure. The left epitaxial end is provided with a polarizing optical path 424 and a detector 425, and the right epitaxial end is provided with a polarizing optical path 422 and a light source 423. The light beam generated by the light source 423 generates a light beam with a specific polarization direction through the polarizing optical path 422 and irradiates the surface of the sample 13. The polarizing optical path 424 is used to analyze the polarization spectrum information of the reflected light generated by the sample 13, and the detector 425 is used to receive, measure and output the polarization spectrum information of the reflected light. A small electric motor can also be provided at the left / right epitaxial end to achieve precise control of the left / right epitaxial end and fine adjustment of the optical path angle. The second driving assembly 43 includes a translation component 431, a rotation component 432 and a lifting component 433 respectively connected to the fixed component 421. A workbench 434 is also arranged between the rotation component 432 and the translation component 431. The axis of the sample stage 2 and the fixed component 421 are the same. The processing and display component 44 includes a computer 441 and a display screen 442. The computer 441 is used to receive and process the signal output by the detector 425 and perform data analysis, and the display screen 442 is used to display the results.

[0044] In this embodiment, the light-transmitting material is quartz; the light source 423 is a white light source, which has a uniform spectral distribution and stable light intensity output, is suitable for general thin film thickness uniformity monitoring, and has a long life and low power consumption, and is easy to install and maintain; the detector 425 is a spectrometer, which can finely analyze optical characteristic data and complete the data acquisition process in a shorter time, thereby improving the efficiency and performance of the monitoring system. The spectrometer is connected to the processor via a data line to extract the signal.

[0045] The following is a detailed description of the workflow of the molecular beam epitaxial thin film growth system with integrated in-situ measurement of this embodiment. Figure 3 As shown:

[0046] S101. Before growth, a wide spectrum monitoring device is focused on the pre-deposited sample.

[0047] Before growth, the sample stage is transferred from the sample transfer chamber to the vacuum reaction chamber by a ring-shaped manipulator. It is first positioned by the translation component, rotation component and lifting component of the wide spectrum monitoring system. Then, the angle of the fixed component and the position and angle of the polarizing light path and the analyzing light path are adjusted to ensure the normal transmission of the light path and focus on the pre-deposited sample.

[0048] S102, determining the semiconductor thin film growth process parameters and starting the growth.

[0049] Set the growth process parameters, start heating the source furnace, start heating the sample stage, and heat the sample at π / 15rad·s -1 The substrate was rotated at a constant speed and after reaching the target temperature, the substrate surface was baked at high temperature for 30 minutes to remove the surface oxide. The furnace baffle was opened to start the growth and the film growth was observed through the RHEED display.

[0050] S103, during the growth process, obtaining measurement spectra of multiple regions of the semiconductor thin film in real time.

[0051] During the growth process, the rotating parts are adjusted so that the worktable moves at a speed of π / 15rad·s -1 The sample rotates at a constant speed, and this point is marked as a test point. The light source is turned on, and the light path passes through the quartz glass into the growth chamber. Refraction and reflection occur on the surface of the sample, and the polarization state of the light changes. Then, the light passes through the analyzer light path, and the detector obtains the measured spectrum of the sample test point, which is transmitted to the computer through the data line. The position of the workbench is adjusted, and the above steps are repeated to measure the measured spectra of multiple points.

[0052] During measurement, it is necessary to ensure that the angular velocity of the light source and the test point is the same to ensure that they move synchronously, so that the angle difference between the light source and the test point is constant, and the distance between the light source and the test point is constant. In order to improve the accuracy of the test, the influence of nonlinear disturbance is considered while ensuring the distance between the light source and the test point on the sample surface is constant.

[0053] like Figure 4 As shown, a three-dimensional coordinate system is constructed with the initial positions of the sample stage and the fixed components. After testing one point, another point is tested. From measurement position 1 to measurement position 2, the light source rotates from point A to A', and the test point changes from point B to B'. The angular velocities of the sample stage and the light source are the same and remain unchanged during the test.

[0054] To ensure that the distance between the light source and the test point on the sample surface is constant, the influence of nonlinear disturbance is considered as follows:

[0055]

[0056] The three-dimensional coordinate system is constructed with the initial positions of the sample stage and the fixed components, D(t) is the distance between the light source and the test point on the sample surface; n is the number of tests, n = 1, 2, 3, ...; r n is the distance from the light source to the origin; r n is the distance from the test point to the origin; t is the time; θ n (t) is the angle of the light source; θ n is the angle of the test point; H is the vertical distance between the light source and the sample stage; α is the amplitude of the sinusoidal perturbation; β is the frequency of the sinusoidal perturbation; γ is the initial amplitude of the exponential decay; δ is the speed of the exponential decay; the corresponding parameters at time t can be measured in real time.

[0057] S104, obtaining real-time information of the semiconductor film on the surface of the sample according to the obtained measurement spectrum, and making adjustments.

[0058] The computer stores semiconductor film information and a spectral database. By comparing the real-time measured spectrum with the database, real-time information about the semiconductor film on the sample surface can be obtained. The semiconductor film information includes the thickness and doping concentration of the semiconductor film. After the growth stage of the sample is completed, the relationship between the thickness, doping concentration and test spectrum of different semiconductor films can be obtained through characterization methods such as reflection high-energy electron diffraction, laser interferometer, atomic force microscopy, X-ray reflection, and electron beam optical excitation, and a database can be constructed based on this.

[0059] The operator can compare the real-time film thickness uniformity or doping concentration with the database to determine whether the real-time thickness uniformity or doping concentration of the semiconductor film reaches the expected value. If the growth process parameter film thickness uniformity or doping concentration reaches the expected value, the growth is continued until the process is completed; if the growth process parameter film thickness uniformity or doping concentration does not reach the expected value, it is necessary to adjust the process parameters, such as the temperature of the source furnace or the temperature of the sample stage and the rotation rate.

[0060] Comparative Example

[0061] Compared with the embodiment, the difference is that the influence of nonlinear disturbance is not considered in step S103, and only the angular velocity of the light source and the sample stage are controlled to be the same, and the distance between the light source and the test point on the sample surface is constant. The relationship is:

[0062]

[0063] The results show that the embodiment of the present invention takes into account the influence of nonlinear perturbations and can more quickly and accurately identify the thickness and doping concentration of the film during in-situ growth, and the detection results are better matched with the semiconductor film information and spectral database.

[0064] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A molecular beam epitaxial thin film growth system with integrated in-situ measurement, characterized in that: include, A vacuum reaction chamber, provided with an installation port and having a bottom part or entirely made of a light-transmitting material, for providing a reaction environment, wherein the installation port is used to install a furnace source; A sample stage, arranged in the vacuum reaction chamber; A first driving assembly, disposed at the top of the outside of the vacuum reaction chamber and connected to the sample stage through a connecting rod, for driving the sample stage and adjusting the position of the sample stage; A wide spectrum monitoring device, disposed at the bottom of the vacuum reaction chamber, comprises a second driving component and a monitoring component; When working, the monitoring component driven by the second driving component keeps synchronous movement with the sample on the sample stage driven by the first driving component to obtain the information of the thin film growth; The monitoring assembly includes a fixing component, a polarizing light path, a light source, a polarizing light path, and a detector; The fixing part includes a plurality of movable epitaxial ends above, the polarizing optical path and the light source and the analyzing optical path and the detector are installed on different epitaxial ends, the light beam generated by the light source generates a light beam with a specific polarization direction through the polarizing optical path to irradiate the sample surface, the analyzing optical path is used to analyze the polarization spectrum information of the reflected light generated by the sample, and the detector is used to receive, measure and output the polarization spectrum information of the reflected light; The second driving assembly comprises a translation component, a rotation component and a lifting component respectively connected to the fixed component, and a workbench is further arranged between the rotation component and the translation component; The monitoring component driven by the second driving component keeps synchronous movement with the sample on the sample stage driven by the first driving component, and the information on the film growth is obtained by ensuring that the distance between the light source and the test point on the sample surface is constant while considering the influence of nonlinear disturbance; The method of ensuring a constant distance between the light source and the test point on the sample surface while considering the influence of nonlinear disturbance is specifically as follows: ； ； Among them, a three-dimensional coordinate system is constructed with the initial positions of the sample stage and the fixed components. D ( t ) is the distance between the light source and the test point on the sample surface; n is the number of tests, n =1,2,3,…; r n is the distance from the light source to the origin; r n is the distance from the test point to the origin; t for the moment; θ n ( t ) is the angle of the light source; Θ n is the angle of the test point; H is the vertical distance between the light source and the sample stage; α is the amplitude of the sinusoidal disturbance; β is the frequency of the sinusoidal disturbance; γ The initial amplitude of the exponential decay; δ The speed of exponential decay; corresponding to t The time parameters can be measured in real time.

2. The molecular beam epitaxial thin film growth system with integrated in-situ measurement according to claim 1, characterized in that: The sample stage and the fixing component have the same axis.

3. The molecular beam epitaxial thin film growth system with integrated in-situ measurement according to claim 1, characterized in that: The wide spectrum monitoring device also includes a processing and display component; The processing and display component is used to receive and process the signal output by the detector, and perform data analysis and result display.

4. The molecular beam epitaxial thin film growth system with integrated in-situ measurement according to claim 1, characterized in that: The bottom portion of the vacuum reaction chamber is extended inward to form an extended portion to provide space for installing the wide spectrum monitoring device; The extension portion is made of light-transmitting material.

5. The molecular beam epitaxial thin film growth system with integrated in-situ measurement according to claim 4, characterized in that: The extended height is 1 / 4 to 1 / 3 of the height of the vacuum reaction chamber.

6. The molecular beam epitaxial thin film growth system with integrated in-situ measurement according to claim 1, characterized in that: A cold pump is installed on the side wall of the vacuum reaction chamber, and the cold pump is used to maintain the vacuum degree inside the chamber.

7. The molecular beam epitaxial thin film growth system with integrated in-situ measurement according to any one of claims 1 to 6, characterized in that: The side wall of the vacuum reaction chamber is also provided with a reflection type high energy electron diffraction device.

8. An application of the molecular beam epitaxial thin film growth system with integrated in-situ measurement as claimed in any one of claims 1 to 7 for in-situ monitoring of film thickness and doping concentration when growing semiconductors on a sample surface.

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