A method for rapid deposition of hybrid semiconductor thin films by plasma thermal sputtering

Abstract

This application relates to the field of semiconductor thin film manufacturing, specifically disclosing a method for rapid deposition of hybrid semiconductor thin films using plasma thermal sputtering. The method includes: mounting a hybrid semiconductor target on a target substrate and partially blocking the heat conduction path between the target and the target substrate cooling system using thermal isolation; introducing a working gas after evacuation, and initiating a ignition discharge to allow the target surface to self-heat due to the accumulation of discharge heat; utilizing the enhanced thermionic emission effect of self-heating to excite a high-density plasma at a low operating voltage, rapidly sputtering the target with low damage, and depositing a dense, pure-phase hybrid semiconductor thin film on the substrate. This application achieves high-throughput sputtering at low voltage through target self-heating, resolving the contradiction between high voltage causing damage to organic components and slow deposition rate at low voltage in traditional magnetron sputtering. It can efficiently prepare hybrid semiconductor thin films with low defect density and accurate stoichiometry, and is suitable for thin film preparation in fields such as solar cells and light-emitting diodes.

Description

Technical Field

[0001] This application relates to the field of semiconductor thin film manufacturing, and in particular to a method for rapid deposition of hybrid semiconductor thin films by plasma thermal sputtering. Background Technology

[0002] Organic-inorganic hybrid semiconductor materials possess excellent properties of both organic and inorganic materials, and have broad application prospects in the field of optoelectronic devices. However, how to achieve large-area, low-cost fabrication of organic-inorganic hybrid semiconductor thin films remains a significant challenge.

[0003] Magnetron sputtering is a mature vacuum thin film deposition technology. Its basic principle is as follows: a working gas (such as argon) is introduced into a vacuum chamber, and a voltage is applied to ionize the gas to form plasma. Positive ions in the plasma are accelerated and bombard the target material under the action of an electric field, causing atoms or molecules on the target surface to be sputtered out and deposited on the substrate to form a thin film. This technology has the advantages of good uniformity of large-area film deposition and high process repeatability.

[0004] However, when conventional magnetron sputtering technology is applied to the preparation of hybrid semiconductor thin films, high-energy plasma can easily cause severe damage to the fragile organic components, resulting in a large number of organic vacancy defects and micropores inside the film, which greatly affects the quality and performance of the film. Specifically, during the etching and film formation process of the target by plasma, the organic components of the hybrid materials (especially hybrid perovskite materials) are easily destroyed and decomposed, causing problems such as stoichiometric shifts, missing organic components, and increased defects. This makes the preparation of high-quality hybrid semiconductor thin films using conventional magnetron sputtering methods extremely challenging.

[0005] Furthermore, conventional magnetron sputtering technology presents an inherent contradiction when applied to the fabrication of hybrid semiconductor thin films: increasing the operating voltage can improve the deposition rate, but it exacerbates the damage to organic components caused by high-energy plasma; decreasing the operating voltage can mitigate the damage to organic components, but it results in an excessively slow deposition rate, failing to meet mass production requirements. Therefore, there is a need in this field to develop novel plasma sputtering methods to improve the bombardment damage problem of organic components and achieve high-quality, non-destructive, and rapid deposition of hybrid semiconductor thin films. Summary of the Invention

[0006] To improve the damage to organic components when conventional magnetron sputtering technology is applied to the preparation of hybrid semiconductor thin films, and to achieve high-quality, non-destructive, and rapid deposition of hybrid semiconductor thin films, this application provides a method for rapid deposition of hybrid semiconductor thin films by plasma thermal sputtering.

[0007] This application provides a method for rapid deposition of hybrid semiconductor thin films using plasma thermal sputtering, employing the following technical solution: A method for rapid deposition of hybrid semiconductor thin films by plasma thermal sputtering includes the following steps: A hybrid semiconductor material target is provided and mounted on a target base in a sputtering chamber. Thermal isolation is used to partially block the heat conduction path between the target and the target base cooling system. After the sputtering chamber is evacuated, a working gas is introduced, and a working voltage is applied to initiate a ignition discharge. The discharge heat generated by the plasma bombarding the target material is accumulated, allowing the target material to achieve self-heating. Under the self-heating state of the target material, the enhanced electron emission effect caused by the increase in target material temperature is used to excite high-density plasma. The target material is then rapidly sputtered under low operating voltage conditions, causing sputtered particles to deposit on the substrate and form a hybrid semiconductor thin film.

[0008] This application employs thermal isolation to block the heat conduction path between the target and the cooling system, allowing the discharge heat generated by plasma bombardment during sputtering to accumulate on the target, thus achieving self-heating of the target. After self-heating, the thermionic emission on the target surface is significantly enhanced, thereby exciting high-density plasma at low operating voltages and achieving high-throughput sputtering of the target. This method overcomes the contradiction in traditional sputtering where "high voltage causes damage to organic components, while low voltage results in slow deposition rates." It achieves high deposition rates under mild conditions of low voltage and low ion bombardment energy, reducing the decomposition and destruction of organic components in hybrid materials by high-energy particles, achieving low-damage, high-rate deposition, and producing dense, pure-phase films with few defects.

[0009] Furthermore, the thermal isolation means include: removing the thermally conductive metal connector between the target material and the target base, and / or adding a thermal insulation medium layer between the target material and the target base.

[0010] By removing the thermally conductive metal connectors and / or adding a thermal insulation layer between the target and the target base, the loss of heat from the target to the cooling system can be effectively blocked, localizing the heat generated by bombardment to the target surface and promoting rapid self-heating of the target. This thermal isolation method is simple and easy to implement, requires no complex modifications to the magnetron sputtering equipment, and is low in cost and highly compatible.

[0011] Furthermore, the thermal isolation method includes: using several point-contact thermally insulating and conductive connectors to connect the target material to the target base, thereby achieving a conductive connection between the target material and the target base, and partially blocking the thermal conduction path between the target material and the target base.

[0012] By employing several point-contact thermally conductive connectors (such as carbon-based connectors), an electrical connection is achieved between the target material and the target base, while the low thermal conductivity of carbon material partially blocks the heat conduction path. This structure ensures that the operating voltage required for discharge can be applied normally to the target material, while effectively suppressing the transfer of heat from the target material to the cooling system.

[0013] Furthermore, the sputtering chamber is a magnetron sputtering chamber, wherein the maximum magnetic flux parallel to the target surface is 30–70 mT, the sputtering working gas pressure is 1–20 Pa, and the average working voltage is -300–-600 V.

[0014] Preferably, the sputtering voltage waveform adopts one of the following: sine wave, pulse wave, or square wave.

[0015] Controlling the magnetic flux within the range of 30–70 mT efficiently confines electrons near the target surface, increasing the probability of collisional ionization between electrons and argon atoms. A working gas pressure of 1–20 Pa balances plasma stability maintenance with the mean free path of sputtered particles. An average voltage of -300–-600 V falls within the relatively low voltage range, significantly reducing bombardment damage to organic components from high-energy particles. The synergistic effect of these parameters provides an ideal process window for rapid sputtering of low-voltage, high-density plasma.

[0016] Furthermore, by controlling the operating voltage, the deposition rate of the thin film is controlled within the range of 10–500 nm / min.

[0017] Because the electron emission capability of the target material is greatly enhanced after self-heating, the plasma density is highly sensitive to changes in the operating voltage. By linearly fine-tuning the operating voltage, the film deposition rate can be precisely controlled within a wide rate range of 10–500 nm / min. This satisfies both the laboratory's need for precise control of nanoscale thin films and the industrial-scale large-area continuous deposition requirements for high throughput, providing excellent process flexibility.

[0018] Furthermore, the thickness of the deposited film is controlled between 200 nm and 10 μm, and the single sputtering time is controlled between 3 and 20 min.

[0019] By controlling the film thickness within the range of 200 nm to 10 μm and the single sputtering time within the range of 3 to 20 min, it is possible to ensure the film thickness required for optoelectronic devices while avoiding thermal stress fracture or component thermal decomposition of the target material due to prolonged heat accumulation. This time window, matched with a high deposition rate, achieves the optimal balance between high-speed film formation and target thermal protection.

[0020] Furthermore, the maximum self-heating temperature of the target material does not exceed 200°C.

[0021] Limiting the maximum self-heating temperature of the target material to no more than 200℃ can both excite sufficient thermionic emission to achieve low-voltage high-density sputtering and prevent the organic components in the hybrid semiconductor material from decomposing and volatilizing due to excessively high temperatures, thus avoiding thermal damage to the target material.

[0022] Furthermore, the hybrid semiconductor material target is obtained by uniformly mixing organic-inorganic hybrid semiconductor material precursor powder with a band gap of 1.0 eV to 3.0 eV through solid-state synthesis and then pressing it; the precursor powder includes organic halide components and inorganic metal halide components.

[0023] Furthermore, the organic halide component is selected from one or more of FAI, FABr, FACl, MAI, MABr, MACl, PEAI, PEABr, and BABr.

[0024] Furthermore, the inorganic metal halide component is selected from one or more of PbI2, PbBr2, PbCl2, SnI2, SnBr2, and SnCl2.

[0025] The target composition covers the main optoelectronic application bands from visible light to near-infrared. By adjusting the ratio of organic cations (such as FA, MA, PEA) and halogens (iodine, bromine, chlorine), the band structure, defect density, and environmental stability of the thin film can be controlled. Tin-based components are environmentally friendly, while lead-based components exhibit excellent optoelectronic properties. Under low-damage conditions of thermal sputtering, the organic and inorganic components in the target can be completely and uniformly co-deposited, resulting in thin films with accurate stoichiometry and pure, dense phases. This provides high-quality, customizable semiconductor thin films for optoelectronic devices such as solar cells and light-emitting diodes.

[0026] In summary, this application includes the following beneficial technical effects: This application introduces thermal isolation between the target and the target-base cooling system, partially blocking the heat conduction path from the target to the cooling system. This prevents the sputtering heat and discharge heat generated by ion bombardment during sputtering from being rapidly dissipated, resulting in heat accumulation inside the target and rapid self-heating of the target surface. As the target temperature rises, its surface thermionic emission capability is significantly enhanced. Under these conditions, only a relatively low sputtering voltage is needed to generate high-density plasma above the target, achieving high-flux etching. This application achieves high deposition rates under mild conditions of low voltage and low ion bombardment energy, reducing the decomposition and damage of organic components in hybrid materials by high-energy particles, significantly suppressing the formation of organic vacancy defects and micropores, and ensuring the accuracy of the thin film stoichiometry and low defect density.

[0027] This application addresses the contradiction in conventional magnetron sputtering technology: "high voltage causes damage to organic components, while low voltage results in slow deposition rates." By utilizing the enhanced electron emission effect of the target's self-heating, high-throughput sputtering can be achieved at low operating voltages, with deposition rates meeting mass production requirements, while maintaining low-damage levels through bombardment energy. The resulting films are dense, pure-phase, and free of large particle defects. Based on conventional magnetron sputtering equipment, this method requires only simple modifications to the target mounting method. It offers high process repeatability and excellent film uniformity, making it particularly suitable for the large-area, low-cost mass production of organic-inorganic hybrid semiconductor materials (especially hybrid perovskites), providing a reliable technical path for industrial applications in optoelectronic devices. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of target installation (thermal sputtering) in Embodiment 1 of this application; Figure 2 These are schematic diagrams of target installation (cold sputtering) in Comparative Examples 1 and 2 of this application. Figure 3 This is the X-ray diffraction (XRD) pattern of the hybrid semiconductor thin film obtained in Example 1 of this application; Figure 4 This is the ultraviolet-visible absorption spectrum of the hybrid semiconductor thin film obtained in Example 1 of this application; Figure 5 This is a calculated optical bandgap diagram of the hybrid semiconductor thin film obtained in Example 1 of this application; Figure 6 This is the X-ray diffraction (XRD) pattern of the hybrid semiconductor thin film obtained in Comparative Example 1 of this application; Figure 7 These are scanning electron microscope (SEM) images of hybrid semiconductor thin films obtained in Example 1 and Comparative Example 1 of this application, where (a) is Example 1 and (b) is Comparative Example 1. Detailed Implementation

[0029] The following is in conjunction with the appendix Figure 1-7 This application will be described in further detail.

[0030] Example 1 (Low-voltage thermal sputtering) Example 1 discloses a method for rapid deposition of hybrid semiconductor thin films using plasma thermal sputtering. It includes the following steps: Step 1, Target preparation: Synthesis of FAPbI3 perovskite precursor powder: Formamidinium hydroiodate (FAI) and lead iodide (PbI2) were placed in an agate ball mill jar at a 1:1 molar ratio (the corresponding product was labeled as pure phase FAPbI3), and an appropriate amount of agate balls were added. After mixing evenly, the mixture was sealed and mechanically ball-milled at room temperature and an ambient relative humidity of approximately 20% for 4 hours at a milling speed of 300 rpm to obtain the perovskite solid precursor material.

[0031] Subsequently, the perovskite solid precursor material prepared by the ball mill jar was thoroughly ground using an agate mortar and pestle to obtain well ground FAPbI3 perovskite precursor powder, which was placed in a 10 mL centrifuge tube and stored in a nitrogen glove box for later use.

[0032] Take about 0.8 g of the above-ground FAPbI3 perovskite precursor powder, fill it into a custom mold, and press it under a pressure of 60 MPa using a tablet press to finally form a FAPbI3 perovskite target with a diameter of 2 cm and a thickness of about 2 mm. Store it in a self-sealing bag for later use.

[0033] Step 2, Target and Substrate Mounting: The FAPbI3 perovskite target prepared in step 1 is mounted on the cathode target base of the magnetron sputtering instrument, such as... Figure 1 As shown, several point-contact carbon-based conductive connectors are installed between the target and the target base to achieve conductive connection between the target and the target base, and to block the heat conduction path between the target and the target base cooling system. A cleaned glass substrate is then fixed onto a sample tray facing the target.

[0034] Step 4, Plasma thermal sputtering and thin film deposition: Evacuate the magnetron sputtering chamber to 10. -3 Below Pa, argon gas is introduced and the working pressure is maintained at 10 Pa. A low sputtering working voltage of approximately -350 V is applied to initiate the ignition discharge, and the maximum magnetic flux parallel to the target surface is 50 mT.

[0035] Because the heat-conducting medium between the target and the target substrate is removed, the plasma discharge heat accumulates on the target surface, causing the target surface to heat up to 190-200℃. As the target surface temperature increases, the electron emission on the target surface is significantly enhanced by thermal excitation. Under a relatively low sputtering operating voltage, the enhanced electron emission effect is used to excite a high-density plasma above the target. Under mild bombardment conditions that maintain low ion kinetic energy (low damage), the plasma rapidly sputters and etches the target, causing the sputtered hybrid precursor particles to be transported in the gas phase and rapidly deposited and nucleated on the substrate surface.

[0036] Under the aforementioned low-pressure, high-density plasma conditions, continuous sputtering deposition was carried out for 8 minutes, with the deposition rate controlled at approximately 40 nm / min, ultimately forming a dense, pure-phase hybrid semiconductor thin film.

[0037] Step 5, Annealing: The substrate was removed and annealed on a hot plate at 160 °C for 30 min to prepare a perovskite film, which was then stored in a nitrogen atmosphere.

[0038] Comparative Example 1 (High-voltage cold sputtering) In traditional magnetron sputtering equipment, a highly thermally conductive metal backplate or thermally conductive silicone is typically used to connect the target to the target base, such as... Figure 2 As shown, the heat of the target material is conducted through the target base and then carried away by the water cooling system to prevent the target material from overheating.

[0039] The difference from Example 1 is that in step 2 of Comparative Example 1, the above-mentioned traditional target installation method is adopted, that is, the target and the target base are connected by a metal heat-conducting component to ensure that the target is forcibly cooled by circulating water during the sputtering process, and no temperature rise occurs, and the target temperature is maintained at 20~30°C.

[0040] In order to obtain a deposition rate similar to that of Example 1, in step 4 of Comparative Example 1, the sputtering operating voltage was increased to approximately -800 V for ignition discharge.

[0041] Comparative Example 2 (Low Voltage Cold Sputtering) The difference from Example 1 is that in step 2 of Comparative Example 2, a traditional target installation method is used, that is, the target and the target base are connected by a metal heat-conducting component to ensure that the target is forcibly cooled by circulating water during sputtering, so that no temperature rise occurs and the target temperature is maintained at 20~30°C.

[0042] To avoid damage to the organic components from high-energy ion bombardment, in step 4 of Comparative Example 2, the sputtering operating voltage was adjusted to the same low voltage level (approximately -350 V) as in Example 1.

[0043] The films prepared in the above embodiments and comparative examples were characterized, and the results are as follows: In Example 1, the thin film deposition rate is fast, and due to the low operating voltage, the bombardment and damage of organic components by high-energy ions is avoided. For example... Figure 7 As shown in (a), the annealed film exhibits a dense, pore-free, large-grain pure-phase FAPbI3 structure with extremely low internal defect state density and no large particle defects on the surface. Figure 3 The XRD pattern shows that the film obtained in Example 1 has a good perovskite phase and exhibits characteristic diffraction peaks of FAPbI3 at 13.9° (corresponding to the 001 crystal plane) and 28° (corresponding to the 002 crystal plane). Figure 4 absorption spectrum and Figure 5 The optical bandgap calculation results show that the thin film obtained in Example 1 has a corresponding absorption band edge at 800 nm. The optical bandgap calculated from the absorption spectrum of the thin film is 1.54 eV, indicating that the thin film has good absorption in the visible light range and can achieve corresponding photoelectric conversion.

[0044] Although Comparative Example 1 achieved a considerable film thickness, the high operating voltage (-800 V) resulted in severe pyrolysis and volatilization of the fragile organic formamidinium component (FAI) due to the intense bombardment of the target and substrate by high-energy argon ions. Figure 7 As shown in (b), the annealed film has a large number of pores inside, and the surface of the film shows obvious agglomerated large particles due to edge arc discharge. Figure 6 The XRD pattern shows that the thin film obtained in Comparative Example 1 has obvious insulating impurity phase (PbI2) precipitation, indicating that there is a large lack of organic components in the sputtered thin film, and the deposition of stoichiometric thin film cannot be achieved. This thin film cannot be used to prepare high-performance optoelectronic devices.

[0045] Because the target material in Comparative Example 2 was in a cold state, it lacked the secondary electron emission enhancement effect brought about by self-heating. At a low voltage of -350V, the plasma density within the system was extremely low, resulting in a sharp drop in sputtering yield. Its deposition rate was only about 2-5 nm / min. After 8 minutes of continuous sputtering, only a very thin precursor layer (less than 40 nm thick) was deposited on the substrate. After annealing, a continuous and dense perovskite light-absorbing layer could not be formed, making it unsuitable for fabricating high-performance optoelectronic devices. Extending the sputtering time, allowing the film to remain in the plasma environment for an extended period, easily leads to the decomposition and volatilization of organic components in the film, failing to achieve the same effect as in Example 1.

[0046] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for rapid deposition of hybrid semiconductor thin films by plasma thermal sputtering, characterized in that: Includes the following steps: A hybrid semiconductor material target is provided and mounted on a target base in a sputtering chamber. Thermal isolation is used to partially block the heat conduction path between the target and the target base cooling system. After the sputtering chamber is evacuated, a working gas is introduced, and a working voltage is applied to initiate a ignition discharge. The discharge heat generated by the plasma bombarding the target material is accumulated, allowing the target material to achieve self-heating. Under the self-heating state of the target material, the enhanced electron emission effect caused by the increase in target material temperature is used to excite high-density plasma. The target material is then rapidly sputtered under low operating voltage conditions, causing sputtered particles to deposit on the substrate and form a hybrid semiconductor thin film.

2. The method for rapid deposition of hybrid semiconductor thin films by plasma thermal sputtering according to claim 1, characterized in that: The thermal isolation methods include: removing the thermally conductive metal connector between the target material and the target base, and / or adding a thermal insulation medium layer between the target material and the target base.

3. The method for rapid deposition of hybrid semiconductor thin films by plasma thermal sputtering according to claim 2, characterized in that: The thermal isolation method includes: using several point-contact thermally insulating and conductive connectors to connect the target material to the target base, thereby achieving a conductive connection between the target material and the target base, and partially blocking the thermal conduction path between the target material and the target base.

4. The method for rapid deposition of hybrid semiconductor thin films by plasma thermal sputtering according to claim 1, characterized in that: The sputtering chamber is a magnetron sputtering chamber, wherein the maximum magnetic flux parallel to the target surface is 30 to 70 mT, the sputtering working gas pressure is 1 to 20 Pa, and the average working voltage is -300 to -600 V.

5. A method for rapid deposition of hybrid semiconductor thin films by plasma thermal sputtering according to claim 4, characterized in that: By controlling the operating voltage, the deposition rate of the thin film is controlled within the range of 10–500 nm / min.

6. A method for rapid deposition of hybrid semiconductor thin films by plasma thermal sputtering according to claim 5, characterized in that: The thickness of the deposited film was controlled between 200 nm and 10 μm, and the single sputtering time was controlled between 3 and 20 min.

7. The method for rapid deposition of hybrid semiconductor thin films by plasma thermal sputtering according to claim 6, characterized in that: The maximum self-heating temperature of the target material shall not exceed 200°C.

8. A method for rapid deposition of hybrid semiconductor thin films by plasma thermal sputtering according to claim 1, characterized in that: The hybrid semiconductor material target is obtained by mixing organic-inorganic hybrid semiconductor material precursor powder with a band gap of 1.0 eV to 3.0 eV uniformly through solid-state synthesis and then pressing it; the precursor powder includes organic halide components and inorganic metal halide components.

9. The method for rapid deposition of hybrid semiconductor thin films by plasma thermal sputtering according to claim 8, characterized in that: The organohalide component is selected from one or more of FAI, FABr, FACl, MAI, MABr, MACl, PEAI, PEABr, and BABr.

10. The method for rapid deposition of hybrid semiconductor thin films by plasma thermal sputtering according to claim 8, characterized in that: The inorganic metal halide component is selected from one or more of PbI2, PbBr2, PbCl2, SnI2, SnBr2, and SnCl2.

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