Multi-light-path laser chemical vapor deposition system

Abstract

The invention provides a multi-light-path laser chemical vapor deposition system, which comprises a deposition module, which comprises a vacuum chamber and is used for depositing a thin film on the surface of a sample in the vacuum chamber by using a chemical vapor deposition method; the laser module is used for providing irradiation laser beams to the surface of the sample; the laser module comprises a plurality of laser units, each laser unit comprises a laser device and a beam expanding piece located on an emergent light path of the laser device, and the laser devices are distributed around the vacuum chamber and emit independent light paths to the surface of the sample. Through the independent optical path design, the use of a spectroscope is avoided, the laser power is reduced by half, and the efficient utilization of laser energy is ensured. Multiple laser beams of independent light paths jointly irradiate, so that source gas molecules absorb and generate an excitation or vibration effect, or the source molecules are subjected to photodecomposition to generate adsorption and decomposition effects, and then deposition is performed to form a film, so that large-area growth of single crystals is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of laser chemical vapor deposition, and particularly to a multi-beam laser chemical vapor deposition system. Background Art

[0002] Photo-chemical vapor deposition (LCVD) technology is a film-forming method that uses light energy to decompose gases and promote surface reactions. With the emergence of excimer lasers in the 1980s, LCVD technology has developed rapidly and has played a huge role in promoting the maturity of chemical vapor deposition (CVD) technology. Compared with conventional CVD technology, LCVD technology has the advantages of low temperature, low damage, precise controllability of film thickness, and selective growth. It has been successfully applied to the fabrication of semiconductor, metal, and dielectric thin films.

[0003] Growing single crystals over a large area requires ensuring laser power and spot area. The existing method of expanding the spot through a beam expander to obtain large-area crystal growth reduces the optical power density, resulting in low deposition efficiency and poor deposition quality of crystal thin films. How to break through the difficulty of growing stable and uniform crystal thin films over a large area and improve the deposition efficiency is an urgent technical problem to be solved at present. Summary of the Invention

[0004] The purpose of the present invention is to overcome the disadvantages and deficiencies of the existing technology, and to provide a multi-beam laser chemical vapor deposition system.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A multi-beam laser chemical vapor deposition system, the system comprising:

[0007] A deposition module, including a vacuum chamber for depositing a thin film on the surface of a specimen located in the vacuum chamber by chemical vapor deposition;

[0008] A laser module for providing an irradiation laser beam to the surface of the specimen;

[0009] The laser module includes a plurality of laser units,

[0010] Each laser unit includes a laser and a beam expander located on the output light path of the laser. Each laser is distributed around the vacuum chamber and emits an independent light path to the surface of the specimen.

[0011] Preferably, the laser module further includes:

[0012] An optical power sensor disposed in the vacuum chamber. The monitoring end of the optical power sensor can move to a first position where the monitoring end is on the output light path of the laser to monitor the power of the laser beam and a second position where the monitoring end is outside the output light path of the laser so that the laser beam can reach the surface of the specimen without being interfered by the optical power sensor.

[0013] Preferably, at least one laser is a tunable laser.

[0014] Preferably, each laser provides an irradiation laser beam with a different wavelength to the surface of the specimen.

[0015] Preferably, the lasers include an infrared laser, an ultraviolet laser, and a tunable laser.

[0016] Preferably, a base is provided in the vacuum chamber, the specimen is disposed on the base, and the deposition module further includes a base position control module and a base position sensor, and the Z-axis position and rotation speed of the base are adjusted by the base position module.

[0017] Preferably, the lasers are symmetrically distributed about the center of the vacuum chamber.

[0018] Preferably, the centers of the light spots formed by the independent optical paths emitted by each laser on the surface of the specimen do not coincide.

[0019] The beneficial effects of the present invention are as follows:

[0020] 1. By adopting an independent optical path design, the present invention avoids the loss of nearly half of the laser power density caused by using a beam splitter, ensuring the efficient utilization of laser energy. The multi-beam lasers with independent optical paths irradiate together, enabling the source gas molecules to absorb, generating excitation or vibration effects, or the source molecules to undergo photolysis to produce adsorption and decomposition effects, and then depositing into a film to achieve large-area growth of single crystals.

[0021] 2. The independent optical path design enables the laser beam to be flexibly adjusted, and the light spots can be dispersed at different positions on the substrate, forming a distribution where the centers of the light spots do not coincide. In the state where the base rotates, this distribution method increases the growth area while improving the deposition efficiency and film quality compared with the traditional MPCVD.

[0022] 3. The present invention further sets the types of lasers. Through the pyrolysis effect of the infrared laser on functional groups, the photolysis effect of the ultraviolet laser on functional groups, and the resonance dissociation effect of the tunable laser, multiple lasers can improve the power density and increase the nucleation area of crystal growth. The frequency-modulated laser can perform resonance excitation on different functional groups, thereby achieving cracking and significantly improving the deposition efficiency. This targeted excitation and cracking make the deposition process more efficient, while improving the purity and quality of the film. Through the synergistic effect of the pyrolysis, photolysis, and resonance cracking effects of different lasers, the present invention can achieve the decomposition of different types of groups and deposit large-area high-quality films. Description of the Drawings

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, obtaining other accompanying drawings without creative efforts still belongs to the scope of the present invention.

[0024] Figure 1 It is a front view structural schematic diagram of the reaction chamber;

[0025] Figure 2 It is a top view structural schematic diagram of the reaction chamber;

[0026] Figure 3 It is a structural block diagram of a multi-path laser chemical vapor deposition system provided by an embodiment of the present invention;

[0027] Figure 4 It is a structural schematic diagram of a laser module provided by an embodiment of the present invention;

[0028] In the figure, 100, laser module; 101, first laser; 102, second laser; 103, third laser; 111, first beam expander; 112, second beam expander; 113, third beam expander; 121, first optical power sensor; 122, second optical power sensor; 123, third optical power sensor; 200, in-situ monitoring module; 300, deposition module; 301, vacuum chamber; 400, temperature monitoring module; 500, gas delivery module; 600, waste gas treatment module; 700, control module; Detailed Embodiments

[0029] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0030] Example 1

[0031] This embodiment provides a multi-path laser chemical vapor deposition system, as Figures 1-4 shown, the system includes:

[0032] A deposition module 300, configured to deposit a thin film on the surface of a specimen by chemical vapor deposition.

[0033] The deposition module 300 includes a vacuum chamber 301, a pedestal disposed within the vacuum chamber 301, and a vacuum sensor. The pedestal is used to place a specimen on which a thin film is to be deposited. The lower end of the pedestal is connected to a pedestal control shaft, and a pedestal position control module and a pedestal position sensor are provided. The pedestal position control module includes a pedestal rotation control assembly and a pedestal lifting control assembly, and precisely controls the rotation speed and Z-axis position of the pedestal by regulating the rotation speed and telescopic length of the pedestal control shaft.

[0034] The laser module 100 is disposed on one side of the deposition module 300 and is used to provide an irradiation laser beam to the surface of the specimen.

[0035] The laser module 100 includes a laser, a water chiller, and some devices for adjusting and monitoring the laser power. Multiple (at least two) lasers are independently provided.

[0036] The temperature monitoring module 400 is connected to the deposition module 300 and is used to monitor the temperature of the surface of the specimen.

[0037] Generally, an auxiliary heating structure is provided on the pedestal within the vacuum chamber 301 to heat the pedestal so that the temperature during the deposition process meets the requirements. The temperature monitoring module 400 can simultaneously monitor the pedestal temperature and the surface temperature of the specimen. In the embodiments of the present invention, the temperature monitoring module 400 can adopt an infrared thermal imaging temperature monitoring system to detect the temperature of the surface of the pedestal irradiated by the laser through this indirect measurement method of infrared thermal imaging. Among them, multiple infrared sensors are provided to measure the temperatures at different positions on the surface of the sample stage.

[0038] In practical applications, the chemical vapor deposition system may further include:

[0039] The in-situ monitoring module 200. The in-situ monitoring module 200 can adopt a RHEED system, which is specifically composed of an electron beam source, a power supply, and a supporting optical cable.

[0040] A plurality of sealed optical windows are provided on the vacuum chamber 301 of the deposition module 300. The irradiation laser beams emitted by each laser source respectively irradiate the surface of the specimen obliquely downward through independent optical windows to form light spots. The optical windows matching the laser sources are arranged at intervals, and it further includes two sealed optical windows respectively connected to the in-situ monitoring module 200 and the temperature monitoring module 400 and a sealed optical window serving as an observation window.

[0041] The gas delivery module 500 is connected to the deposition module 300 and is used to deliver the gases required for the chemical vapor deposition process to the deposition module 300.

[0042] The gas delivery module 500 mainly consists of a precursor raw material tank, storage gas cylinders for carrier gas and dilution gas, a delivery pipeline, a flow controller, etc. The gas delivery module 500 can provide precise, stable, and continuous vapor, and accurately control the stoichiometric ratio of each metal element in the mixed raw material vapor.

[0043] The waste gas treatment module 600 is connected to the deposition module 300 and is used to treat the waste gas generated during the chemical vapor deposition process.

[0044] The control module 700 is connected to the laser module 100, the in-situ monitoring module 200, the deposition module 300, the temperature monitoring module 400, and the gas delivery module 500, and is used to control the operation of the laser module 100, the in-situ monitoring module 200, the deposition module 300, the temperature monitoring module 400, and the gas delivery module 500.

[0045] Specifically, the control module 700 can control the power of the irradiated laser beam according to the temperature of the specimen surface monitored by the temperature monitoring module 400.

[0046] The control module 700 can automatically and accurately control each step to achieve intelligence.

[0047] Furthermore, the laser module 100 can include multiple laser units, and the multiple laser units are used to provide irradiated laser beams with different wavelengths to the specimen surface.

[0048] The present invention does not limit the number of laser units. For example, the number of laser units can be two, three, or more.

[0049] In this embodiment, taking the laser module 100 including 3 laser units as an example, the specific structure of the laser module 100 is described.

[0050] First, the specific structure of each laser unit is described. Refer to Figure 2 As shown, each laser unit includes:

[0051] A laser for emitting a laser beam with a preset wavelength. The laser module 100 of the present invention includes a first laser 101, a second laser 102, and a third laser 103. The three lasers are arranged around the outer periphery of the vacuum chamber 301 in a symmetric distribution. The projection of adjacent two lasers on the XOY plane is 120°, and the three lasers emit independent light paths respectively.

[0052] Among them, the preset wavelength is the wavelength set in advance. The type and quantity of the laser are set according to the required deposition material, deposition efficiency, and film characteristics. Infrared lasers, ultraviolet lasers, tunable lasers, etc. can be used. For example, pyrolytic LCVD uses a continuously output infrared laser, such as a Nd:YAG laser or a CO2 laser; photolytic LCVD uses a short-wavelength ultraviolet laser light source, such as an excimer laser or the high harmonic output of a Nd:YAG laser; resonance dissociation LCVD uses a laser light source with a tunable wavelength, such as an infrared CO2 laser and an optical parametric oscillator laser (OPO) laser. By precisely modulating the laser wavelength, the resonance excitation of specific gas molecules is achieved. The pyrolysis effect of the infrared laser on functional groups, the photolysis effect of the ultraviolet laser on functional groups, and the resonance dissociation effect of the tunable laser. Multiple lasers can improve the power density and increase the nucleation area of crystal growth.

[0053] The co-irradiation of multiple lasers takes into account increasing the spot irradiation area, thereby enabling large-area thin film deposition. In addition, compared with the device using a beam splitter, the optical power density is also increased, so that a thin film with high crystallization quality can be obtained.

[0054] Exemplarily, the first laser 101 selects an infrared laser that emits a 1065 nm laser beam, the second laser 102 selects a pulsed laser beam that emits a 351 nm laser beam, and the third laser 103 selects a tunable short-pulse laser. By using a tunable laser light source, resonance excitation can be performed on different types of functional groups, thereby achieving cracking and improving the deposition efficiency and quality.

[0055] A beam expander is arranged on the outgoing light path of the laser and is used to expand the laser beam; there are three beam expanders in the laser module 100 of the present invention, namely the first beam expander 111, the second beam expander 112, and the third beam expander 113.

[0056] An optical power sensor is disposed in a vacuum chamber. The monitoring end of the optical power sensor can move to a first position where the monitoring end is on the optical path of the laser beam emitted by the laser after passing through the beam expander to monitor the power of the laser beam, and a second position where the monitoring end is outside the optical path of the laser beam emission so that the laser beam can reach the specimen surface without being interfered by the optical power sensor. In practical applications, the optical power sensor can be a photodiode, an energy meter or a power meter. The movement of the monitoring end here can be in the form that the monitoring end is fixed to the body of the optical power sensor, the monitoring end and the body of the optical power sensor move as a whole, or the monitoring end is movable relative to the body of the optical power sensor, or a combination of the two. In this embodiment, it is in the form that the monitoring end is movable relative to the body of the optical power sensor. Specifically, a photodetector with a telescopic probe is adopted, and the telescopic probe is controlled to extend and retract to switch the probe between the first position and the second position. The photodetector can also be equipped with a signal amplification and conversion module for amplifying the electrical signal output by the detector and an information processing module for calculating the optical power density. The information processing module feeds the processed information back to the control module 700.

[0057] There are three optical power sensors in the laser module 100 of the present invention, which are respectively denoted as the first optical power sensor 121, the second optical power sensor 122 and the third optical power sensor 123.

[0058] The three laser units in the laser module 100 of the present invention can be respectively denoted as the first laser unit, the second laser unit and the third laser unit.

[0059] Reference Figure 2 As shown, in the first laser unit, the first laser 101 emits a laser beam. After being expanded by the first beam expander 111, it passes through the monitoring end of the first optical power sensor 121 at the first position for power monitoring. After the monitoring is completed, the monitoring end of the first optical power sensor 121 contracts to the second position, and the laser beam reaches the sample surface to form a light spot.

[0060] In the second laser unit, the second laser 102 emits a laser beam. After being expanded by the second beam expander 112, it passes through the monitoring end of the second optical power sensor 122 at the first position for power monitoring. After the monitoring is completed, the monitoring end of the second optical power sensor 122 contracts to the second position, and the laser beam reaches the sample surface to form a light spot.

[0061] In the third laser unit, the third laser 103 emits a laser beam. It passes through the monitoring end of the third optical power sensor 123 at the first position for power monitoring. After the monitoring is completed, the monitoring end of the third optical power sensor 123 contracts to the second position, and the laser beam reaches the sample surface to form a light spot.

[0062] Example 2

[0063] 3C-SiC was prepared using the multi-beam laser chemical vapor deposition system of Example 1. Among them, the three lasers were selected as follows: The first laser 101 was a Nd:YAG infrared laser with an emission wavelength of 1065 nm and a pulse width of 4.58 ns. The second laser 102 was a Nd:YAG high-harmonic short-wavelength pulsed laser with an emission wavelength of 351 nm and a pulse width of 45 ns. The third laser 103 was a tunable short-pulse laser. The third laser 103 was a titanium-doped sapphire tunable laser, which could generate femtosecond or picosecond short pulses from 670 nm to 1100 nm or even a wider spectral range.

[0064] The preparation steps of 3C-SiC were as follows:

[0065] Hexamethyldisilane (HMDS) was used as the precursor source material, and a mixed gas of argon and hydrogen (Ar, H2) was used as the carrier gas. HMDS was controlled at an appropriate temperature to volatilize into a gas. The gas flow rate of HMDS was 1 - 4 SCCM, the gas flow rate of Ar was 20 - 40 SCCM, and the gas flow rate of H2 was 500 SCCM. The power of each laser was 0 - 300 W, the growth temperature was 1200 - 1300 °C, the pressure (P) was 800 - 1400 Pa, the substrate was a 2-inch <110> n-Si, and the growth time was 3 - 5 minutes, obtaining a single-crystal 3C-SiC thin film.

[0066] Example 3

[0067] A diamond thin film was prepared using the multi-beam laser chemical vapor deposition system of Example 1. The gas ratio and process parameters were as follows: Gas ratio: hydrogen (H2): 1000 sccm, methane (CH4): 100 sccm, oxygen (O2): 2 sccm, argon (Ar): 10 sccm, nitrogen (N2): 2 sccm; Process parameters: microwave frequency: 2450 ± 15 MHz, output power: 0.1 - 10 kW (adjustable according to needs), working pressure: 0.05 - 0.3 MPa (approximately equal to 3.7 - 75 Torr), ultimate vacuum pressure: less than 0.7 Pa (approximately equal to 5×10 -3 Torr), substrate temperature: 800 - 1200 °C, cooling water flow rate: 6 - 12 L / min, growth mode: TM021 or TM023.

[0068] The power density of the laser beam emitted by the laser was set to 40 W / cm 2 .

[0069] Comparative Example 1

[0070] The difference between this comparative example and Example 3 was that no laser was set, and the microwave power was set to 750 - 800 W.

[0071] After detection, the residual compressive stress of the diamond film prepared in Example 3 is 0.10 GPa, the nano-hardness is 91 GPa, and the Young's modulus is 721 GPa. The residual compressive stress of the diamond film prepared in Comparative Example 1 is 0.79 GPa, the nano-hardness is 86 GPa, and the Young's modulus is 632 GPa. The results show that under the condition of laser irradiation, the stress of the grown film is reduced, the hardness and Young's modulus are increased, the crystallization quality is improved, the stiffness is increased, the grain size is increased, and the lattice defects are reduced.

[0072] The above-disclosed are only the preferred embodiments of the present invention. Of course, the scope of the rights of the present invention cannot be limited thereby. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. A multi-optical-path laser chemical vapor deposition system, the system comprising: A deposition module, including a vacuum chamber, for depositing a thin film on the surface of a specimen located in the vacuum chamber by chemical vapor deposition; A laser module, for providing an irradiation laser beam to the surface of the specimen; The laser module includes a plurality of laser units, characterized in that: Each laser unit includes a laser and a beam expander located on the outgoing optical path of the laser. The lasers are distributed around the vacuum chamber and each emits an independent optical path to the surface of the specimen.

2. The multi-optical-path laser chemical vapor deposition system according to claim 1, characterized in that: The laser module further includes: An optical power sensor, disposed in the vacuum chamber. The monitoring end of the optical power sensor can move to a first position where the monitoring end is on the outgoing optical path of the laser to monitor the power of the laser beam, and a second position where the monitoring end is outside the outgoing optical path of the laser so that the laser beam reaches the surface of the specimen without being interfered by the optical power sensor.

3. A multi-optical-path laser chemical vapor deposition system according to claim 1, characterized in that: At least one laser is a tunable frequency laser.

4. A multi-optical-path laser chemical vapor deposition system according to claim 1, wherein: Each laser provides an irradiation laser beam with a different wavelength to the surface of the specimen.

5. A multi-optical-path laser chemical vapor deposition system according to claim 1, characterized in that: The lasers include infrared lasers, ultraviolet lasers, and tunable frequency lasers.

6. A multi-optical-path laser chemical vapor deposition system according to any one of claims 1-5, characterized in that: A base is provided in the vacuum chamber, and the specimen is disposed on the base. The deposition module further includes a base position control module and a base position sensor, and the Z-axis position and rotation speed of the base are adjusted through the base position module.

7. A multi-optical-path laser chemical vapor deposition system according to any one of claims 1-5, characterized in that: Each laser is symmetrically distributed about the center of the vacuum chamber.

8. A multi-optical-path laser chemical vapor deposition system according to any one of claims 1-5, characterized in that: The centers of the light spots formed by each laser emitting an independent optical path to the surface of the specimen do not coincide.

Images