Method for preparing semiconductor material by using high-purity quartz sand

Abstract

The invention relates to the technical field of semiconductor materials, in particular to a method for preparing a semiconductor material from high-purity quartz sand. The method comprises the following steps: firstly, grafting and modifying the surface of quartz sand through 3-aminopropyltriethoxysilane, complexing metal impurities by using amino functional groups, and improving the purity of a precursor from the source; secondly, hydrogen / deuterium gas pulse back-and-forth switching is adopted, surface hydrogen atom dynamics is regulated and controlled through the isotope effect, and an etching-nucleation synergistic window is created; and finally, through sequential alternate supply of silane and disilane, time separation of a weak bond etching period and a high-activity nucleation period is realized. The prepared semiconductor material shows excellent performance, and compared with a traditional method, the technical problem of low-temperature deposition of a high-quality semiconductor film is solved through full-process optimization from a material source to a deposition end.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor materials, and particularly relates to a method for preparing semiconductor materials by using high-purity quartz sand. BACKGROUND

[0002] In the field of semiconductor manufacturing, preparing high-quality semiconductor thin films by using quartz sand as a silicon source is a key technical path to realize low-cost and high-performance electronic devices. Traditional semiconductor material preparation methods mainly rely on high-purity single crystal silicon as a starting material, but the preparation cost is high and the process complexity is large, which limits the large-scale application of semiconductor devices. Quartz sand, as a silicon source with abundant reserves and low cost on earth, provides a new possibility for the large-scale preparation of semiconductor materials.

[0003] However, there are many technical challenges in preparing semiconductor materials by using quartz sand. First, iron, aluminum, sodium, potassium, calcium, titanium and other metal impurities are commonly present in quartz sand. These impurities are easily transferred to the final product in the subsequent chlorination, purification and precursor preparation processes, forming deep level trap centers, which seriously affect the carrier transport performance of the semiconductor thin film. Second, the traditional silane vapor deposition process is difficult to obtain high-quality microcrystalline silicon thin films at low temperature, and often needs to be carried out at a higher temperature, which not only increases the energy consumption, but also may introduce thermal stress and structural defects.

[0004] In the prior art, although the plasma enhanced chemical vapor deposition technology can prepare amorphous silicon and microcrystalline silicon thin films at a relatively low temperature, there are still significant deficiencies in defect control and carrier modulation. The single precursor supply mode cannot effectively separate the etching and nucleation processes, resulting in high dangling bond density and many grain boundary defects in the thin film. At the same time, the traditional hydrogen dilution method has limited ability to regulate surface reactions, making it difficult to obtain ideal microcrystalline fraction and density at low temperature.

[0005] In terms of carrier modulation, the existing doping technology often uses continuous doping or uniform doping methods, which cannot achieve the synergistic optimization of carrier concentration and mobility. The introduction of doping atoms can increase the carrier concentration, but it also increases the ionized impurity scattering, which reduces the carrier mobility. How to minimize the scattering centers while ensuring sufficient carrier concentration to achieve high mobility is an important challenge faced by current technology.

[0006] In addition, the internal stress control of the semiconductor thin film is also a key factor affecting the performance and reliability of the device. High internal stress not only affects the mechanical stability of the thin film, but also affects the electronic state density distribution through lattice distortion, thereby affecting the transport characteristics of the carriers. The thin film prepared by the traditional process often has high compressive stress, which needs to be released by subsequent annealing process, but this may introduce new defects and impurities.

[0007] Therefore, it is urgent to develop a comprehensive technical solution for controlling the impurity content from the source, accurately regulating the deposition process, and realizing carrier directional modulation. The solution can prepare high-quality semiconductor thin films with low defect density and high carrier mobility under low-temperature conditions, providing a technical foundation for the manufacture of next-generation semiconductor devices. SUMMARY

[0008] Therefore, the present application aims to provide a method for preparing semiconductor materials from high-purity quartz sand to realize low defect density and high carrier mobility of semiconductor thin films prepared from high-purity quartz sand.

[0009] To achieve the above-mentioned purpose, the present application provides a method for preparing semiconductor materials from high-purity quartz sand, comprising the following steps: 1) mixing high-purity quartz sand with anhydrous ethanol and 3-aminopropyltriethoxysilane, refluxing and stirring under nitrogen protection, washing with anhydrous ethanol after filtration, and vacuum drying to obtain aminated quartz sand; 2) mixing the aminated quartz sand with petroleum coke, loading into a quartz tube reactor, and reacting with dry chlorine gas to obtain a crude silicon tetrachloride product; 3) adding the crude silicon tetrachloride product to active carbon and aluminum oxide, stirring at room temperature, and collecting the fraction with a boiling point of 57-58℃ by reduced pressure distillation to obtain high-purity silicon tetrachloride; 4) loading the high-purity silicon tetrachloride and silicon chips into a fixed bed reactor, and refluxing with hydrogen gas to obtain a chlorohydrosilane mixture mainly containing trichlorosilane; 5) hydrogenating and rearranging the chlorohydrosilane mixture through a fixed bed reactor filled with Cu / SiO2 catalyst, and collecting the generated gas by-78℃ low-temperature condensation and fractional distillation to obtain silane gas and disilane gas, respectively; 6) loading a substrate into a reaction cavity of a plasma-enhanced chemical vapor deposition device, vacuumizing, aerating, and heating the substrate; turning on a radio frequency power source and a very high frequency power source, and setting a square wave pulse; 7) alternately depositing in AB sections, performing section A: hydrogen gas, silane, and argon gas supply, and doping in section A by injecting hydrogen gas carrier containing phosphine or diborane; and then performing section B: switching to deuterium gas and disilane supply; completing the deposition of an n / p / n carrier modulation layer structure to obtain a silicon hydride compound composite thin film; 8) annealing the silicon hydride compound composite thin film in a mixed atmosphere of nitrogen and hydrogen gas to obtain a semiconductor material prepared from high-purity quartz sand.

[0010] Preferably, the particle size distribution D50 of the high-purity quartz sand is 30-60μm, and the purity is 99.8%-99.95%.

[0011] Preferably, in step (1), the high-purity quartz sand is mixed with anhydrous ethanol and 3-aminopropyl triethoxysilane in a round-bottom flask, stirred under reflux at 70-90°C for 1.5-2.5 h, washed with anhydrous ethanol for 3 times after filtration, and dried at 110-130°C under vacuum for 1.5-2.5 h.

[0012] Preferably, in step (1), the high-purity quartz sand and 3-aminopropyl triethoxysilane are used in a ratio of 300-700 g:15-35 mL.

[0013] Preferably, in step (2), the aminated quartz sand and petroleum coke are used in a mass ratio of 300-700:60-140, and the reaction is carried out by passing dry chlorine gas at a flow rate of 1.5-2.5 L / min at 850-950°C for 5-7 h.

[0014] Preferably, in step (3), the crude silicon tetrachloride, activated carbon, and aluminum oxide are used in a mass ratio of 250-550:15-25:3-5.

[0015] Preferably, in step (4), the high-purity silicon tetrachloride and metal silicon granules are used in a mass ratio of 200-400:15-25, and the dismutation is carried out by passing hydrogen gas at a flow rate of 0.8-1.2 L / min at 280-320°C for 6-10 h.

[0016] Preferably, in step (5), the chlorosilane-hydrogen mixture is subjected to hydrogenation rearrangement by passing through a fixed-bed reactor packed with a Cu / SiO2 catalyst containing 3wt%-7wt% Cu, under the conditions of hydrogen flow rate of 1.2-1.8 L / min at 180-220°C.

[0017] Preferably, the substrate is a 50mm×50mm Corning EAGLE XG glass substrate, which is sequentially cleaned with acetone for 10 min by ultrasonic, cleaned with isopropyl alcohol for 10 min by ultrasonic, rinsed with deionized water, and dried with nitrogen.

[0018] Preferably, in step (6), the vacuum degree of the substrate is 5×10 -6 Torr, the process pressure is 0.6-1.0 Torr, the substrate is heated to 200-260°C, the radio frequency power is 60-100 W at a frequency of 13.56 MHz, the very high frequency power is 30-50 W at a frequency of 60 MHz, the duty cycle of the square wave pulse is 50%-70%, and the pulse frequency is 3-7 kHz.

[0019] Preferably, in step (7), the A section is performed for 25-35 s: hydrogen flow rate of 80-120 sccm, silane flow rate of 1.5-2.5 sccm, and argon flow rate of 8-12 sccm; and then the B section is performed for 4-6 s: deuterium flow rate of 80-120 sccm and disilane flow rate of 0.8-1.2 sccm.

[0020] Preferably, in step (7), the first 15-25 s of the A section is doped by injecting 1.5-2.5 sccm of hydrogen carrier gas containing 3-7 ppm of phosphine or diborane for 2-4 s.

[0021] Preferably, in step (7), the first A section is performed for n-type doping, the second A section is non-doped, the third A section is performed for p-type doping, the fourth A section is non-doped, and the fifth A section is performed for n-type doping; the phosphine is used for n-type doping, and the diborane is used for p-type doping.

[0022] Preferably, in step (8), annealing is performed at 380-420 °C for 100-140 s in a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 95:5.

[0023] Advantages of the present application: Firstly, the present application realizes source purification control through graft modification of 3-aminopropyltriethoxysilane. The amino functional group forms a complex coordination with metal chloride during the chlorination reaction, effectively blocking the transfer path of transition metal impurities to the gas phase product. At the same time, the organic long-chain structure of the modified molecule provides a steric hindrance effect during the precursor generation stage, inhibiting the introduction of residual hydrocarbons. This full-spectrum control from inorganic to organic impurities fundamentally improves the purity level of the precursor, laying a foundation for the subsequent preparation of high-quality thin films.

[0024] Secondly, the hydrogen-deuterium isotope alternation creates a unique surface reaction regulation mechanism. The larger mass of deuterium atoms significantly extends their residence time on the film surface, providing a more stable surface passivation environment for microcrystal nucleation. This isotopic kinetic effect extends the selective window period of nucleation, enabling precise regulation of the microcrystal fraction and crystallization quality, effectively reducing the density of grain boundary defects and dangling bonds.

[0025] Thirdly, the time sequence alternation of silane and disilane dual precursors realizes the functional division of etching and nucleation phases. Silane, as a small molecule precursor, has high surface diffusion ability and etching selectivity, preferentially removing weak bond structures; disilane, as a disilicon molecule, provides higher nucleation activity and abundant silicon source supply at low temperatures. Time sequence separation avoids competitive adsorption and cross-reactions when different precursors are supplied simultaneously, resulting in higher structural density and better electrical performance.

[0026] Fourthly, the dual-frequency superimposed pulse plasma excitation produces a synergistic enhancement effect. The synergistic effect of radio frequency and very high frequency creates a rich distribution of active species energy spectrum, improving the surface migration ability and nucleation selectivity during deposition. Pulse modulation further optimizes the time-domain characteristics of the plasma, achieving precise balance between etching and deposition.

[0027] In terms of carrier modulation, an n / p / n heterostructure is constructed inside the thin film through precise timing pulse injection of phosphine and diborane. This carrier modulation layer not only provides abundant free carriers, but also improves carrier transport characteristics through the formation of built-in electric field, achieving the synergistic optimization of carrier concentration and mobility.

[0028] The semiconductor thin film prepared by the application has multiple advantages of low defect density, high carrier mobility, excellent photoelectric response characteristics, and low internal stress. The carrier mobility of the material is significantly improved, the photoconductive ratio is greatly improved, and the internal stress of the thin film is effectively reduced, providing a high-quality material basis for the manufacture of high-performance semiconductor devices. This whole-process optimization strategy opens up a new technical path for the industrial application of quartz sand-based semiconductor materials. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the application clearer, the application will be further described in detail below with specific examples.

[0030] Example 1: (1) Mix 300g of high-purity quartz sand (particle size distribution D50 of 30μm, purity of 99.8%) with 300mL of anhydrous ethanol and 15mL of 3-aminopropyltriethoxysilane in a 800mL round-bottom flask, reflux and stir at 70℃ under nitrogen protection for 1.5h, wash 3 times with anhydrous ethanol after filtration, and vacuum dry at 110℃ for 1.5h to obtain aminated quartz sand; (2) Mix 300g of aminated quartz sand with 60g of petroleum coke, load into a quartz tube reactor, and pass dry chlorine gas at a flow rate of 1.5L / min at 850℃ for 5h to obtain a crude silicon tetrachloride; (3) Add 250g of crude silicon tetrachloride to 15g of activated carbon and 3g of aluminum oxide, stir at room temperature for 1.5h, and collect the fraction with a boiling point of 57-58℃ by reduced pressure distillation to obtain high-purity silicon tetrachloride; (4) Load 200g of high-purity silicon tetrachloride and 15g of metal silicon particles into a fixed bed reactor, pass hydrogen gas at a flow rate of 0.8L / min at 280℃ for 6h to obtain a chlorosilane mixture mainly containing trichlorosilane; (5) Pass 150g of chlorosilane mixture through a fixed bed reactor loaded with 3wt% Cu / SiO2 catalyst, hydrogenate and rearrange at 180℃ under a hydrogen flow of 1.2L / min, and collect the generated gas by -78℃ low-temperature condensation fractionation to obtain silane gas and disilane gas, respectively; (6) Select 50 mm x 50 mm Corning EAGLE XG glass substrate, in turn with acetone ultrasonic cleaning 10 min, isopropyl alcohol ultrasonic cleaning 10 min, deionized water rinse and nitrogen dry, the substrate into the plasma enhanced chemical vapor deposition equipment reaction cavity, vacuum to the base vacuum 5 x 10-6Torr, gas to process pressure 0.6 Torr, substrate heating to 200°C; turn on the radio frequency power 13.56 MHz power 60 W superimposed very high frequency power 60 MHz power 30 W, set square wave pulse duty cycle 50%, pulse frequency 3 kHz.

[0031] (7) AB segment alternately deposited, the first A segment 25 s (hydrogen flow 80 sccm, silane flow 1.5 sccm, argon flow 8 sccm, in the first 15 s, 1.5 sccm flow of hydrogen carrier gas containing 3 ppm of phosphine for 2 s n-type doping), followed by the first B segment 4 s (switched to deuterium flow 80 sccm, disilane flow 0.8 sccm, no doping); the second A segment 25 s (hydrogen flow 80 sccm, silane flow 1.5 sccm, argon flow 8 sccm, no doping), followed by the second B segment 4 s (deuterium flow 80 sccm, disilane flow 0.8 sccm, no doping); the third A segment 25 s (hydrogen flow 80 sccm, silane flow 1.5 sccm, argon flow 8 sccm, in the first 15 s, 1.5 sccm flow of hydrogen carrier gas containing 3 ppm of diborane for 2 s p-type doping), followed by the third B segment 4 s (deuterium flow 80 sccm, disilane flow 0.8 sccm, no doping); the fourth A segment 25 s (hydrogen flow 80 sccm, silane flow 1.5 sccm, argon flow 8 sccm, no doping), followed by the fourth B segment 4 s (deuterium flow 80 sccm, disilane flow 0.8 sccm, no doping); the fifth A segment 25 s (hydrogen flow 80 sccm, silane flow 1.5 sccm, argon flow 8 sccm, in the first 15 s, 1.5 sccm flow of hydrogen carrier gas containing 3 ppm of phosphine for 2 s n-type doping), the deposition of n / p / n carrier modulation layer structure, get silicon hydride compound composite film; (8) The silicon hydride compound composite film is annealed at 380°C for 100 s in a mixed gas atmosphere with a nitrogen to hydrogen volume ratio of 95:5, to reduce the stress in the film and activate the dopant atoms, to obtain a semiconductor material prepared from high-purity quartz sand.

[0032] Example 2: (1) 500 g high-purity quartz sand (particle size distribution D50 of 45 μm, purity of 99.9%) was mixed with 500 mL of anhydrous ethanol and 25 mL of 3-aminopropyltriethoxysilane in a 1000 mL round-bottom flask, and stirred under reflux at 80°C under nitrogen protection for 2 h. After filtration, the product was washed with anhydrous ethanol for 3 times, and vacuum dried at 120°C for 2 h to obtain aminated quartz sand; (2) 500 g of the aminated quartz sand was mixed with 100 g of petroleum coke, and loaded into a quartz tube reactor. Dry chlorine gas was introduced at a flow rate of 2.0 L / min at 900°C for 6 h to obtain a crude silicon tetrachloride; (3) 400 g of the crude silicon tetrachloride was added with 20 g of activated carbon and 4 g of alumina, and stirred at room temperature for 2 h. The product was collected by distillation at a boiling point of 57-58°C under reduced pressure to obtain high-purity silicon tetrachloride; (4) 300 g of the high-purity silicon tetrachloride was loaded with 20 g of metal silicon particles into a fixed bed reactor, and hydrogen gas was introduced at a flow rate of 1.0 L / min at 300°C for 8 h to obtain a chlorohydrosilane mixture mainly containing trichlorosilane; (5) 200 g of the chlorohydrosilane mixture was introduced into a fixed bed reactor loaded with 5 wt% Cu / SiO2 catalyst, and hydrogenated and rearranged at 200°C under hydrogen flow of 1.5 L / min. The generated gas was condensed and fractionally collected at -78°C to obtain silane gas and disilane gas, respectively; (6) A 50 mm x 50 mm Corning EAGLE XG glass substrate was selected, and sequentially cleaned with acetone for 10 min by ultrasonic cleaning, isopropyl alcohol for 10 min by ultrasonic cleaning, and deionized water, and then dried by nitrogen blowing. The substrate was loaded into a plasma-enhanced chemical vapor deposition device reaction chamber, vacuumed to a base vacuum degree of 5 x 10 -6 Torr, and filled with gas to a process pressure of 0.8 Torr. The substrate was heated to 230°C. A radio frequency power source of 13.56 MHz was turned on at a power of 80 W, and a very high frequency power source of 60 MHz was turned on at a power of 40 W. A square wave pulse duty cycle of 60% and a pulse frequency of 5 kHz were set.

[0033] (7) Alternately depositing AB segments, performing a first A segment for 30 s (hydrogen flow rate 100 sccm, silane flow rate 2 sccm, argon flow rate 10 sccm, n-type doping by injecting a hydrogen carrier gas containing 5 ppm of phosphine at a flow rate of 2 sccm for 3 s at the 20th s), followed by a first B segment for 5 s (switching to deuterium flow rate 100 sccm, disilane flow rate 1 sccm, no doping); performing a second A segment for 30 s (hydrogen flow rate 100 sccm, silane flow rate 2 sccm, argon flow rate 10 sccm, no doping), followed by a second B segment for 5 s (deuterium flow rate 100 sccm, disilane flow rate 1 sccm, no doping); performing a third A segment for 30 s (hydrogen flow rate 100 sccm, silane flow rate 2 sccm, argon flow rate 10 sccm, p-type doping by injecting a hydrogen carrier gas containing 5 ppm of diborane at a flow rate of 2 sccm for 3 s at the 20th s), followed by a third B segment for 5 s (deuterium flow rate 100 sccm, disilane flow rate 1 sccm, no doping); performing a fourth A segment for 30 s (hydrogen flow rate 100 sccm, silane flow rate 2 sccm, argon flow rate 10 sccm, no doping), followed by a fourth B segment for 5 s (deuterium flow rate 100 sccm, disilane flow rate 1 sccm, no doping); performing a fifth A segment for 30 s (hydrogen flow rate 100 sccm, silane flow rate 2 sccm, argon flow rate 10 sccm, n-type doping by injecting a hydrogen carrier gas containing 5 ppm of phosphine at a flow rate of 2 sccm for 3 s at the 20th s), to complete the deposition of the n / p / n carrier modulation layer structure, to obtain a silicon hydride compound composite film; (8) Annealing the silicon hydride compound composite film in a mixed gas atmosphere of nitrogen and hydrogen at a volume ratio of 95:5 at 400 ℃ for 120 s to reduce the internal stress of the film and activate the doping atoms, to obtain a semiconductor material prepared from high-purity quartz sand.

[0034] Example 3: (1) Mixing 700 g of high-purity quartz sand (particle size distribution D50 of 60 μm, purity of 99.95%) with 700 mL of anhydrous ethanol and 35 mL of 3-aminopropyl triethoxysilane in a 1200 mL round-bottom flask, refluxing and stirring at 90 ℃ under nitrogen protection for 2.5 h, washing 3 times with anhydrous ethanol after filtration, and vacuum drying at 130 ℃ for 2.5 h to obtain aminated quartz sand; (2) Mixing 700 g of the aminated quartz sand with 140 g of petroleum coke, loading into a quartz tube reactor, and reacting by introducing dry chlorine at a flow rate of 2.5 L / min at 950 ℃ for 7 h, and collecting by condensation to obtain a crude silicon tetrachloride; (3) Adding 550 g of the crude silicon tetrachloride to 25 g of activated carbon and 5 g of aluminum oxide, stirring at room temperature for 2.5 h, and collecting the fraction with a boiling point of 57-58 ℃ by reduced-pressure distillation to obtain high-purity silicon tetrachloride; (4) 400 g of high purity silicon tetrachloride and 25 g of metallic silicon particles were loaded into a fixed bed reactor, and hydrogen gas with a flow rate of 1.2 L / min was introduced to reflux and disintegrate at 320°C for 10 h to obtain a chlorosilane mixture mainly containing trichlorosilane; (5) 250 g of the chlorosilane mixture was introduced into a fixed bed reactor loaded with 7 wt% Cu / SiO2 catalyst, and hydrogenation rearrangement was performed at 220°C under a hydrogen flow rate of 1.8 L / min. The generated gas was condensed and fractionally collected at -78°C to obtain silane gas and disilane gas, respectively; (6) A 50 mm x 50 mm Corning EAGLE XG glass substrate was selected, sequentially cleaned with acetone for 10 min by ultrasonic cleaning, isopropyl alcohol for 10 min by ultrasonic cleaning, and deionized water, and then dried by nitrogen blowing. The substrate was loaded into a plasma-enhanced chemical vapor deposition device reaction chamber, vacuumed to a base vacuum degree of 5 x 10-6 Torr, filled with gas to a process pressure of 1.0 Torr, and heated to 260°C. A radio frequency power source with a power of 100 W at 13.56 MHz and a very high frequency power source with a power of 50 W at 60 MHz were turned on, a square wave pulse duty cycle of 70% and a pulse frequency of 7 kHz were set.

[0035] (7) Alternate deposition in A and B segments. The first A segment is executed for 35 seconds (hydrogen flow rate 120 sccm, silane flow rate 2.5 sccm, argon flow rate 12 sccm, with a 2.5 sccm hydrogen carrier gas containing 7 ppm phosphine injected for 4 seconds at the 25th second for n-type doping). Then, the first B segment is executed for 6 seconds (switching to deuterium flow rate 120 sccm, disilane flow rate 1.2 sccm, no doping). The second A segment is executed for 35 seconds (hydrogen flow rate 120 sccm, silane flow rate 2.5 sccm, argon flow rate 12 sccm, no doping). Then, the second B segment is executed for 6 seconds (deuterium flow rate 120 sccm, disilane flow rate 1.2 sccm, no doping). The third A segment is executed for 35 seconds (hydrogen flow rate 120 sccm, silane flow rate 2.5 sccm, argon flow rate 12 sccm, with a 2.5 sccm hydrogen carrier gas containing 7 ppm phosphine injected for 4 seconds at the 25th second for n-type doping). P-type doping was performed by injecting a hydrogen carrier gas with a flow rate of 2.5 sccm and a concentration of 7 ppm diborane for 4 s, followed by a third B-stage of 6 s (deuterium flow rate 120 sccm, disilane flow rate 1.2 sccm, no doping); a fourth A-stage of 35 s (hydrogen flow rate 120 sccm, silane flow rate 2.5 sccm, argon flow rate 12 sccm, no doping), followed by a fourth B-stage of 6 s (deuterium flow rate 120 sccm, disilane flow rate 1.2 sccm, no doping); and a fifth A-stage of 35 s (hydrogen flow rate 120 sccm, silane flow rate 2.5 sccm, argon flow rate 12 sccm, with an n-type doping effect achieved by injecting a hydrogen carrier gas with a flow rate of 2.5 sccm and a concentration of 7 ppm phosphine at the 25th s for 4 s), thus completing the deposition of the n / p / n carrier modulation layer structure and obtaining a silicon-hydride composite thin film. (8) The silicon-hydrogen compound composite film was annealed at 420°C for 140s in a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 95:5 to reduce the internal stress of the film and activate the doped atoms, thus obtaining a semiconductor material prepared from high-purity quartz sand.

[0036] Comparative Example 1: The difference between Comparative Example 1 and Example 2 is that the APTES grafting modification in step (1) is omitted, and unmodified high-purity quartz sand is directly used in the subsequent chlorination-purification-preparation precursor process.

[0037] Comparative Example 2: The difference between Comparative Example 2 and Example 2 is that in Section B, deuterium (D2) is replaced with hydrogen (H2) at the same flow rate, while the other parameters in Section B remain unchanged.

[0038] Comparative Example 3: The difference between Comparative Example 3 and Example 2 is that the supply of disilane (Si2H6) is cancelled, and only the dilution gas (D2) of the same flow rate is retained in section B, without the supply of silicon source.

[0039] Comparative Example 4: The difference between Comparative Example 4 and Example 2 is that the AB alternating sequence is cancelled, and A+B co-flow continuous deposition (H2 / D2+SiH4+Si2H6 is supplied, and the total equivalent mole supply amount and single cycle length remain the same) is used instead, and the doping pulse point remains the same as the A section.

[0040] Comparative Example 5: The difference between Comparative Example 5 and Example 2 is that the 60 MHz very high frequency power supply is cancelled, and only the 13.56 MHz, 80 W single frequency plasma is retained, and the rest of the pulse parameters remain unchanged.

[0041] Comparative Example 6: The difference between Comparative Example 6 and Example 2 is that the doping pulse of the A section is cancelled, and the deposition is a intrinsic composite film.

[0042] Performance test: Purity and impurity content of the precursor: Take 50 mL of silicon tetrachloride, silane, and disilane from Examples 1-3 and Comparative Example 1 as samples. First, take 5 mL of liquid precursor silicon tetrachloride and hydrolyze it to 500 mL with ultrapure water. Use inductively coupled plasma mass spectrometry (ICP-MS) to determine the impurity content of metals and metalloids such as iron, aluminum, sodium, potassium, calcium, titanium, boron, and phosphorus, with a detection limit set at 0.1 ppb level. Take 1 L of gas sample of gaseous precursors silane and disilane under standard conditions, and use gas chromatography-mass spectrometry (GC-MS) to analyze the oxygen-containing organic impurity content. The results are shown in Table 1.

[0043] Carrier transport performance and photoconductivity: Van der Pauw-Hall effect test system is used to determine the carrier type, concentration and mobility of the semiconductor material, with a magnetic induction intensity of 0.5 T and a test temperature of room temperature. The sample is prepared as a 10 mm x 10 mm square, with ohmic contact electrodes prepared at the four corners. The photoconductivity test uses AM1.5G standard solar spectrum, with a light intensity of 100 mW / cm 2 , and the photoconductivity ratio is obtained by comparing the conductivity under light and dark conditions. The results are shown in Table 2.

[0044] Film stress: Laser curvature method is used to deposit the film on a polished single crystal silicon (100) wafer simultaneously. Laser interferometer is used to measure the curvature change of the silicon wafer before and after deposition. Film stress is calculated according to Stoney formula. The results are shown in Table 2.

[0045] Table 1 Test results of precursor performance

[0046] Data analysis: As can be seen from the data of examples 1-3 in Table 1, the high-purity precursors prepared by the present application exhibit significant purity advantages, with the total content of metal impurities in silicon tetrachloride being 18.7 ppb, 12.4 ppb and 16.2 ppb, respectively, the content of oxygen-containing organic impurities in silane being 0.26 ppm, 0.18 ppm and 0.22 ppm, respectively, and the content of oxygen-containing organic impurities in disilane being 0.21 ppm, 0.15 ppm and 0.19 ppm, respectively. This systematic control of impurity content may be due to the deep intervention of 3-aminopropyl triethoxysilane graft modification in the quartz sand raw material stage, with the amino functional group being able to form complex coordination with metal chlorides during the chlorination process, effectively preventing the transfer of transition metal impurities into the gas phase product, and the organic long-chain structure of the modified molecule may provide a steric hindrance effect during the precursor generation stage, inhibiting the introduction of residual hydrocarbons, thereby achieving the simultaneous removal of multiple impurities at the source.

[0047] As can be seen from the data of examples 2 and comparative example 1 in Table 1, there is a significant difference in the purity of the precursors, and this all-round purity improvement may be based on the strong coordination ability of the amino group and the thermal stability of the silicon-oxygen bond in the aminopropyl triethoxysilane molecule, so that the modified quartz sand surface can selectively enrich and fix metal impurities during high-temperature chlorination, blocking their migration path to the silicon tetrachloride product, and the controlled release degradation characteristics of the grafted molecule further reduce the generation of organic pollutants, achieving full-spectrum control from inorganic to organic impurities.

[0048] Table 2 Performance test results of semiconductor materials

[0049] Data analysis: As can be seen from the data of examples 1-3 in Table 2, the semiconductor materials prepared by the present application exhibit excellent consistency and high-quality characteristics in terms of carrier transport performance, and this synergistic optimization of carrier parameters may be due to the superimposed effect of the three-step progressive modification strategy: source purity control reduces the defect state density, hydrogen-deuterium isotope alternation switching creates an accurate nucleation window period, and silane-disilane time sequence supply realizes controlled distribution of structure phase and amorphous phase, multiple process coupling effectively suppresses the generation of dangling bonds and grain boundary defects, so that the carriers can maintain both high effective concentration and good transport capacity.

[0050] As can be seen from the data of Example 2 and Comparative Example 1 in Table 2, the 3-aminopropyltriethoxysilane graft modification has a significant positive impact on the performance of the semiconductor material. This significant improvement can be attributed to the high-purity precursor reducing impurity trap centers in the thin film, and more dopant atoms being effectively ionized to contribute to the carriers. In terms of carrier mobility, Example 2 is 2 times that of Comparative Example 1, and this significant improvement in mobility indicates a significant reduction in scattering centers within the thin film, which can be directly related to the reduction in metal impurity content in the precursor, fewer metal impurities mean less ionized impurity scattering and defect state scattering. The photoconductivity ratio increased by 133.3%, which indicates that the photoelectric response characteristics of the thin film have been greatly optimized, which can be related to the less pure silicon network structure reducing non-radiative recombination centers, thereby improving the efficiency and lifetime of photo-generated carriers. In terms of film stress, the compressive stress of Example 2 is significantly lower than that of Comparative Example 1, with a reduction of 38.5%, which indicates that the internal structure of the thin film is more uniform and dense, with lower defect density. The root cause of these performance improvements is that the amino modification has achieved a leap in the quality of the precursor through source purification, thereby reducing the introduction of impurities and the formation of structural defects during thin film deposition.

[0051] As can be seen from the data of Example 2 and Comparative Example 2 in Table 2, the hydrogen-deuterium gas switching has a significant control effect on the performance of the thin film, and Example 2 uses hydrogen-deuterium alternation while Comparative Example 2 only uses hydrogen, and the carrier concentration of the two is similar, but the photoconductivity ratio is very different. This can be attributed to the difference in adsorption and desorption kinetics of hydrogen atoms and deuterium atoms on the surface, and the larger mass of deuterium atoms results in a longer residence time on the surface of the thin film, providing a more stable surface passivation environment for crystallite nucleation, extending the selective window period of nucleation, and thus obtaining a better crystallization fraction and less grain boundary defect density.

[0052] As can be seen from the data of Example 2 and Comparative Example 3 in Table 2, the double-precursor time sequence alternation supply exhibits unique material design advantages compared to the single-precursor strategy, and this performance difference can be based on the deposition kinetics division brought by the difference in molecular structure between silane and disilane. Silane, as a small molecule precursor, has high surface diffusion capability and etching selectivity on the surface, and can preferentially remove weak bond structures, while disilane, as a double-silicon molecule, provides higher nucleation activity and more abundant silicon source supply at low temperature. Time sequence alternation effectively separates the etching purification phase and the high-quality nucleation phase in the time axis, avoiding mutual interference when they are performed simultaneously, and obtaining higher effective doping concentration and better microstructure quality. The relative closeness of the photoconductivity ratio indicates that although the carrier parameters of Comparative Example 3 are poor, the light response characteristics are still acceptable, which can be related to its relatively low film stress and fewer interface defects, but the overall performance is still significantly inferior to the double-precursor strategy.

[0053] As can be seen from the data of Example 2 and Comparative Example 4 in Table 2, the time-alternating deposition mode exhibits significant process advantages in semiconductor material performance regulation compared to continuous co-flow deposition, which may be due to the precise regulation of surface chemical reactions by the time separation strategy. The alternating mode enables functional division of different chemical environments (hydrogen-deuterium switching, silane-disilane switching) in the time domain, avoiding competitive adsorption and cross-reactions when multiple-component gases are supplied simultaneously. The hydrogen environment in section A is conducive to weak bond etching and surface purification, and the deuterium-disilane environment in section B provides stable high-activity nucleation conditions. This periodic surface state reconstruction effectively suppresses random nucleation and defect accumulation. Although the continuous co-flow mode maintains equivalent total molar supply, it loses the time selectivity of the reaction, leading to increased complexity of surface reactions, decreased nucleation quality, and more severe internal stress accumulation, ultimately resulting in disadvantages in carrier transport and photoelectric response.

[0054] As can be seen from the data of Example 2 and Comparative Example 5 in Table 2, the dual-frequency superimposed plasma excitation mode produces a synergistic enhancement effect in semiconductor thin film preparation compared to single-frequency plasma, which may be based on the selective excitation and dissociation mechanism of different frequency plasmas for precursor molecules. The 13.56 MHz radio frequency is mainly responsible for maintaining the overall plasma and activating the large molecule precursor, while the 60 MHz very high frequency more effectively excites the generation of small molecule radicals and fine regulation of surface reactions. Dual-frequency superposition creates a more diverse energy spectrum distribution of active species, improving surface migration ability and nucleation selectivity during deposition. Pulsed modulation further optimizes the time-domain characteristics of the plasma, achieving precise balance between etching and deposition.

[0055] As can be seen from the data of Example 2 and Comparative Example 6 in Table 2, the doping pulse plays a key role in carrier regulation of semiconductor materials. Example 2 performs n / p / n carrier modulation, while Comparative Example 6 is an intrinsic thin film. Interestingly, the intrinsic thin film exhibits a relatively high photoconductivity ratio and low film stress, which may be related to the introduction of fewer impurity atoms and the relatively pure lattice structure. However, the extremely low carrier concentration limits its application value in practical semiconductor devices. The introduction of doping pulses not only significantly increases the carrier concentration, but more importantly, through the precise timing injection of phosphine and diborane, an n / p / n heterostructure is constructed inside the thin film. This carrier modulation layer not only provides abundant free carriers, but also improves the transport characteristics of the carriers through the formation of built-in electric fields, achieving a leap from intrinsic semiconductors to functional device materials.

[0056] Those skilled in the art should understand that the above discussion of any embodiment is only intended to be exemplary in nature and is not intended to suggest that the present application is limited to these examples; under the concept of the present application, the above embodiments or technical features among different embodiments can be combined, steps can be implemented in any order, and there are many other variations of different aspects of the present application as described above, which are not provided in details for the sake of brevity.

Claims

1. A method for preparing semiconductor materials using high-purity quartz sand, characterized in that, Includes the following steps: (1) High-purity quartz sand was mixed with anhydrous ethanol and 3-aminopropyltriethoxysilane, refluxed and stirred under nitrogen protection, filtered, washed with anhydrous ethanol, and dried under vacuum to obtain amino-based quartz sand. (2) Mix aminated quartz sand with petroleum coke and load it into a quartz tube reactor. Pass dry chlorine gas through the reactor to react and collect the product by condensation to obtain crude silicon tetrachloride. (3) Add crude silicon tetrachloride to activated carbon and alumina, stir at room temperature, distill under reduced pressure, and collect the fraction with a boiling point of 57-58℃ to obtain high-purity silicon tetrachloride; (4) High-purity silicon tetrachloride and metallic silicon fragments are loaded into a fixed-bed reactor and hydrogen is introduced for reflux disproportionation to obtain a chlorosilane mixture mainly composed of trichlorosilane. (5) The chlorosilane mixture is hydrogenated and rearranged in a fixed-bed reactor packed with Cu / SiO2 catalyst. The generated gas is collected by low-temperature condensation and fractionation at -78℃ to obtain silane gas and disilane gas, respectively. (6) Load the substrate into the reaction chamber of the plasma-enhanced chemical vapor deposition equipment, evacuate, fill with gas, and heat the substrate; turn on the radio frequency power supply and superimpose the VHF power supply, and set the square wave pulse; (7) The deposition is carried out alternately in sections A and B. Section A: hydrogen, silane and argon are supplied. Hydrogen carrier gas containing phosphine or diborane is injected into section A for doping. Then section B: deuterium and disilane are supplied. The deposition of the n / p / n carrier modulation layer structure is completed to obtain the silicon-hydrogen compound composite film. (8) Anneal the silicon-hydrogen compound composite film in a mixed atmosphere of nitrogen and hydrogen to obtain a semiconductor material prepared from high-purity quartz sand.

2. The method for preparing semiconductor materials using high-purity quartz sand according to claim 1, characterized in that, The high-purity quartz sand has a particle size distribution D50 of 30-60 μm and a purity of 99.8%-99.95%.

3. The method for preparing semiconductor materials using high-purity quartz sand according to claim 1, characterized in that, In step (1), the ratio of high-purity quartz sand to 3-aminopropyltriethoxysilane is 300-700g:15-35mL.

4. The method for preparing semiconductor materials using high-purity quartz sand according to claim 1, characterized in that, In step (2), the mass ratio of aminated silica sand to petroleum coke is 300-700:60-140, and dry chlorine gas with a flow rate of 1.5-2.5 L / min is introduced at 850-950℃ to react for 5-7 hours.

5. The method for preparing semiconductor materials using high-purity quartz sand according to claim 1, characterized in that, In step (3), the mass ratio of crude silicon tetrachloride, activated carbon and alumina is 250-550:15-25:3-5.

6. The method for preparing semiconductor materials using high-purity quartz sand according to claim 1, characterized in that, In step (4), the mass ratio of high-purity silicon tetrachloride to metallic silicon fragments is 200-400:15-25.

7. The method for preparing semiconductor materials using high-purity quartz sand according to claim 1, characterized in that, In step (6), the vacuum level of the substrate is evacuated to 5×10⁻⁶. -6 Inflate to process pressure 0.6-1.0 Torr, heat substrate to 200-260℃; turn on RF power supply 13.56MHz power 60-100W superimposed VHF power supply 60MHz power 30-50W, set square wave pulse duty cycle 50%-70%, pulse frequency 3-7kHz.

8. The method for preparing semiconductor materials using high-purity quartz sand according to claim 1, characterized in that, In step (7), the A section is executed for 25-35 seconds: hydrogen flow rate 80-120 sccm, silane flow rate 1.5-2.5 sccm, and argon flow rate 8-12 sccm; then the B section is executed for 4-6 seconds: deuterium flow rate 80-120 sccm and disilane flow rate 0.8-1.2 sccm.

9. The method for preparing semiconductor materials using high-purity quartz sand according to claim 1, characterized in that, In step (7), during the 15th to 25th second of segment A, a hydrogen carrier gas with a flow rate of 1.5-2.5 sccm containing 3-7 ppm phosphine or diborane is injected for 2-4 seconds to dope the mixture.

10. The method for preparing semiconductor materials using high-purity quartz sand according to claim 1, characterized in that, In step (7), the first A segment is doped with n-type, the second A segment is undoped, the third A segment is doped with p-type, the fourth A segment is undoped, and the fifth A segment is doped with n-type; the phosphine is used for n-type doping, and the diborane is used for p-type doping.

Images