WO2012027909A1 - Method for in situ fabricating doped black silicon - Google Patents

Abstract

A method for in situ fabricating doped black silicon is provided. The method comprises: a silicon wafer is put into the injecting chamber of a black silicon fabrication device; the mixed gases with etching and passivation function and the gas with doped elements are introduced into the device in turn; the process parameters of the black silicon fabrication device are accordingly adjusted into a preset scale respectively; the black silicon fabrication device produces plasma respectively, and reaction ions in the plasma with etching and passivation function react with silicon wafer to form the black silicon; ion radicals with the doped elements are injected into the silicon by the injecting bias so as to realize in situ fabrication doped black silicon. By using the method, in situ fabrication doped black silicon can be realized in the same device with a simple process and a low production cost, and the method can easily reach a high doping concentration.

Description

 Method for preparing doped black silicon in situ

Technical field

 The present invention relates to the field of optoelectronic device manufacturing technology, and more particularly to a method for preparing doped black silicon in situ. Background technique

 Silicon is widely used as a substrate material in the fabrication of optoelectronic devices because of its many advantages. However, when silicon is used in the fabrication of optoelectronic devices, especially solar cells, the following problems exist: The reflectance of silicon to visible light is as high as 40%, and the utilization rate of solar energy is low, resulting in low efficiency of solar cells. In order to reduce the reflectivity of silicon to visible light, in 1999, Professor Eric Mazur of Harvard University in the United States used the experimental method of scanning silicon wafers with femtosecond laser to produce black silicon. Compared with the general silicon material structure, black silicon has a strong light absorption capability. When black silicon is used for the production of solar cells, the efficiency of the battery can be significantly improved.

 Before and after making black silicon, black silicon needs to be doped for various reasons: if B (boron) needs to be injected,

P (phosphorus) and As (broken) elements form a PN junction; in order to increase the infrared absorption rate of silicon, a sulfur element (sulfur: S, selenium: Se, 碲: Te) is incorporated into silicon. In the conventional process, black silicon fabrication and doping are performed in different devices, and an additional process is required between black silicon fabrication and doping, so that the process of preparing black silicon having doped elements is complicated, and the production cost is increased. On the other hand, the traditional doping method mainly uses thermal diffusion to dope into black silicon, such as incorporating B, P, and As to form a PN junction, and incorporating a sulfur element to increase the infrared absorption rate of silicon; When other elements are doped into the black silicon by thermal diffusion, the high doping concentration cannot be achieved due to the solid solubility of these elements in the black silicon.

In the prior art, in order to increase the infrared absorption rate of silicon, there is a method in which a powder containing a sulfur-based element is coated on a silicon surface by a solvent, and then a surface of the silicon wafer is scanned with a femtosecond laser to form black at the same time in one step. Silicon structure and chalcogenide doping. Although this method achieves the simultaneous completion of the black silicon structure For the doping of sulfur-based elements, however, compared with the conventional process, before and after the doping of the black silicon structure and the chalcogen-based element, the surface of the silicon wafer is coated with the sulfur-containing element powder and the residual powder is removed. The two-step process makes the process more complicated. In addition, since the sulfur-containing element powder has a large influence on the vacuum system, it is not commonly used in the semiconductor manufacturing process; moreover, the femtosecond laser method itself has disadvantages such as cumbersome process control, high equipment cost, and inconvenient maintenance, so the use of this A method for fabricating black silicon with doping elements has a complicated process, high production and maintenance cost, and is difficult to mass-produce. Summary of the invention

 The technical problem to be solved by the present invention is to provide a method for preparing doped black silicon in situ. With the method, black silicon fabrication and in-situ doping can be realized on the same device, the process cartridge is simple, and the production cost is low, and It is easy to achieve a high doping concentration.

 In order to solve the above technical problems, the present invention provides a method of preparing doped black silicon in situ, the method comprising:

 Place the silicon wafer in the injection chamber of the black silicon preparation device;

 And introducing a mixed gas into the black silicon preparation device, wherein the mixed gas is composed of a gas having an etching action and a gas having a passivation effect, and adjusting a process parameter of the black silicon preparation device into a preset numerical range, The black silicon preparation device generates a plasma, and the reactive ions in the plasma react with the silicon wafer to form black silicon;

Stopping the mixed gas, and extracting all the gases in the black silicon preparation device; keeping the formed black silicon in place, introducing a gas having a doping element into the black silicon preparation device, adjusting the gas The process parameters of the black silicon preparation device enter a preset numerical range, and the black silicon preparation device generates a plasma, and ions or ionic groups having doping elements in the plasma are injected into the black silicon. , in-situ preparation of doped black silicon. Further, the present invention has the following features: the step of placing the silicon wafer in the injection chamber of the black silicon preparation device further comprises: electrically connecting the silicon wafer to a power source to which a bias voltage can be applied.

 Further, the present invention has the following features: The process parameters include: background pressure and working pressure of the injection chamber, flow rate of the injected gas, velocity of the extracted gas, composition of the mixed gas, composition ratio and concentration, plasma The output power and frequency of the body power supply, the bias voltage applied by the power supply to which the bias voltage can be applied, and the plasma injection time.

 Further, the present invention has the following features: The bias voltage is formed by combining a plurality of bias voltages, by adjusting the plasma injection time, the flow rate and composition ratio of the injected gas, and the output of the plasma power source. The power or the bias voltage changes the doping concentration of the doped black silicon.

Further, the present invention has the following features: The gas having etching action includes SF ₆ , CF ₄ , CHF ₃ , C ₄ F ₈ , NF ₃ , SiF ₄ , C ₂ F ₆ , HF, BF ₃ , PF ₃ , Cl ₂ , HCl, SiH ₂ Cl ₂ , SiCl ₄ , BC1 ₃ or HBr.

Further, the present invention has the following features: The gas having a passivation function includes 0 ₂ , N ₂ 0 or N ₂ .

Further, the present invention has the following features: The gas having a doping element includes B ₂ H ₆ , B(OCH ₃ ) ₃ , B ₂ 0 ₃ , BN, BC1 ₃ , BBr ₃ , BF ₃ , PH ₃ , PC1 ₃ , PBr ₃ , PF ₃ , PF ₅ , P ₂ 0 ₅ , POCl ₃ , AsH ₃ , AsCl ₃ , AsF ₃ , AsF ₅ , H ₂ S, H ₂ Se or H ₂ Te.

Further, the present invention has the following characteristics: in the step of formation of black silicon in the injection chamber base pressure of 10- ⁷ Pa ~ lOOOPa, working pressure of 10- ³ Pa ~ lOOOPa, the mixed gas The flow rate is 1 sccm ~ 1000 sccm, the output power of the plasma power supply is 1W ~ 100000 W, the applied bias voltage is -100,000 V ~ 100000V, the frequency of the plasma power supply is DC ~ 10GHz, and the power supply can be applied with a bias voltage. The frequency is from DC to 10 GHz, and the volume ratio between the etched gas and the passivating gas in the mixed gas is 0.01 to 100. Further, the present invention has the following features: in the step of doping black silicon, the background pressure of the injection chamber is 1 (T ⁷ Pa ~ lOOOPa, the working pressure is 10 - ³ Pa ~ lOOOPa, The gas flow rate of the doping element is 1 sccm ~ 1000 sccm, the output power of the plasma power source is 1 W ~ 100000 W, the applied bias voltage is -100,000 V ~ 100,000 V, and the frequency of the plasma power source is DC ~ 10 GHz. The frequency of the power supply to which the bias voltage can be applied is from DC to 10 GHz, and the doping concentration of the doped black silicon is greater than 1E15 cm- ³ .

 In order to solve the above technical problem, the present invention also provides a method for preparing doped black silicon in situ, the method comprising:

 Place the silicon wafer in the injection chamber of the black silicon preparation device;

 And introducing a mixed gas into the black silicon preparation device, wherein the mixed gas is composed of a gas having an etching action, a gas having a passivation effect, and a gas having a doping element, and adjusting a process parameter of the black silicon preparation device a predetermined range of values, the black silicon preparation device generates a plasma, and reactive ions in the plasma react with the silicon wafer to form black silicon, and at the same time, doping element ions in the plasma are implanted into the chamber In the black silicon, black silicon in-situ doping is completed.

 Compared with the prior art, the present invention has the following advantages:

 1. Compared with the conventional process, the method of the present invention can complete black silicon fabrication and black silicon doping in one device, that is, achieve in-situ doping, thereby reducing the process of preparing black silicon with doping elements. Reduce process complexity and thus reduce manufacturing costs;

2. Compared with the method of incorporation of other elements into the black silicon by thermal diffusion, the method of the present invention is ion implantation, and the concentration of the element incorporated into the silicon is not limited by the solid solubility, and a high doping concentration can be achieved; And according to the requirements for subsequent fabrication of the solar cell, the doping concentration can be changed by adjusting the plasma injection time, the flow rate and composition ratio of the injection gas, the output power of the plasma power source, or the bias voltage, so that Doping concentration of doped black silicon is controllable; 3. Compared with the doping of the black silicon structure and the chalcogen element doping by the femtosecond laser method, the apparatus used in the method of the invention does not require the processes of powder coating and powder removal, and the process cartridge is controllable and the production cost is low. , easy to mass produce. DRAWINGS

 1 is a schematic flow chart of a first embodiment of a method for preparing doped black silicon in situ according to the present invention; FIG. 2 is a schematic flow chart of a second embodiment of a method for preparing doped black silicon in situ according to the present invention; Is a schematic flow chart of a third embodiment of the method for preparing doped black silicon in situ according to the present invention; FIG. 4 is a schematic flow chart of a fourth embodiment of the method for preparing doped black silicon in situ according to the present invention; A schematic flow diagram of a fifth embodiment of a method of in situ preparation of doped black silicon. detailed description

 The present invention will be described in detail below with reference to the drawings and specific embodiments. Plasma Immersion Ion Implantation (also known as plasma), sometimes referred to as plasma implantation, plasma doping, plasma immersion implantation, plasma source ion implantation, plasma-based ion implantation, etc. Etc., these several methods represent the same process technology, that is, the sample to be injected is directly immersed in the plasma, and the sample and the plasma are made by applying a bias voltage (also referred to as "injection voltage") to the sample. An electric field is injected between the sheath layers; the reactive ions located in the electric field injected into the sheath and entering the electric field from the plasma into the sheath are directly injected into the sample under the acceleration of the electric field. Since a sheath is formed on the surface of the sample, the surface of the sample exposed to the plasma will be simultaneously injected at the same time.

The invention utilizes plasma immersion ion implantation to realize in-situ doping of black silicon, which can complete black silicon fabrication and doping in one device, that is, realize in-situ doping of black silicon, the main steps are: The sheet is placed in a black silicon preparation device, and a mixed gas having an etch passivation function and a process gas having a doping element are respectively introduced, and the process parameters of the black silicon preparation device are respectively adjusted to enter a preset numerical range. Black silicon preparation and doping in the same black silicon fabrication unit is completed without the need to replace equipment.

 Black silicon preparation devices, such as plasma immersion ion implanters, typically include an implantation chamber and a plasma source. In the injection chamber, a sample stage on which a sample can be placed is provided. On the side opposite the sample stage, a plasma source is provided. The plasma source includes an evacuation system that evacuates the injection chamber to a predetermined background pressure range; a gas supply system that can charge the injection chamber with the desired gas and can follow a certain control rule Adjusting various parameters of the gas, such as gas flow rate, extraction speed, gas composition ratio and concentration, etc., when the gas is charged into the injection chamber, the pressure of the injection chamber can be brought into a preset working pressure range; and the plasma The power source, which can be a radio frequency power source, a microwave power source, or a direct current power source, can also be powered in pulses, and the frequency of these power sources can be a fixed frequency or a variable frequency.

 Alternatively, the black silicon preparation device further includes a power source to which a bias voltage can be applied. The power source to which the bias voltage is applied is electrically connected to the sample stage in the injection chamber. The type of power supply to which the bias voltage can be applied is similar to that of a plasma power source. It can be a radio frequency power source, a wave power source, or a DC power source. These power supplies can also be supplied in pulses, or any combination of these power supplies, and thus can be supplied to the sample stage. The bias voltage composed of the bias voltage.

Alternatively, the black silicon preparation apparatus may further include monitoring components that monitor various process conditions within the injection chamber, such as electron temperature, plasma density, ion potential, ion mass spectrometry distribution, and emission spectrum, etc. within the monitoring chamber. The power of the plasma power source and the power source to which the bias voltage can be applied can be adjusted according to certain control rules. If the power is supplied in a pulse form, the frequency, duty cycle, and pulse width of the plasma power source and the power source to which the bias voltage can be applied are also It can be adjusted according to certain control rules. A power supply that can apply a bias voltage can adjust its applied bias voltage according to certain control rules. In the in-situ preparation method of doping black silicon in the present invention, doping concentration of doped black silicon and plasma implantation time (for example, from starting a biasable power source to turning off a biasable power source) The period of time is equivalently calculated, the flow rate and composition ratio of the injected gas, the output power of the plasma power source, and the bias voltage are related. By adjusting the above process parameters, the desired doping concentration can be obtained. Heteroblack silicon, that is to say, compared with the existing thermal diffusion method, not only a doping concentration of 4 Å can be obtained by this method, but also a doping concentration can be controlled.

 The included but not limited embodiments of the invention are described below in conjunction with the drawings.

 Example 1

 Referring to FIG. 1, an embodiment of the present invention provides a first embodiment of a method for preparing doped black silicon in situ by plasma immersion ion implantation, including the following steps:

 Step 101: pretreating the silicon wafer;

 Silicon wafer pretreatment includes wafer cleaning, polishing, annealing, etching, texturing (also known as velvet) and/or patterning, and the shape can be circular, square or rectangular, etc. It can also be any other complicated shape;

 Step 102: placing the silicon wafer in a black silicon preparation device;

 The black silicon preparation device may be a plasma immersion ion implanter, the silicon wafer is placed in the injection chamber of the device, and placed on the sample stage; in some embodiments, the black silicon preparation device includes a power source to which a bias voltage can be applied, The silicon wafer is electrically connected to the sample stage. Since the sample stage is electrically connected to a power source to which a bias voltage can be applied, the silicon wafer is electrically connected to a power source to which a bias voltage can be applied. Under certain conditions, the startup can be biased. A voltage source can apply a bias voltage to the silicon wafer;

Step 103: introducing a mixed gas having etching, passivation and doping elements into the black silicon preparation device, adjusting a process parameter of the black silicon preparation device to achieve a plasma generating working condition; Acting gases include SF ₆ , CF ₄ , CHF ₃ , C ₄ F ₈ , NF ₃ , SiF ₄ , C ₂ F ₆ , HF, BF ₃ , PF ₃ , Cl ₂ , HCl, SiH ₂ Cl ₂ , SiCl ₄ , BC1 ₃ or HBr; the gas having a passivation includes 0 ₂ , N ₂ 0 or N ₂ ; the gas having a doping element includes B ₂ H ₆ , B(OCH ₃ ) ₃ , B ₂ 0 ₃ , BN, BC1 ₃ , BBr ₃ , BF ₃ , PH ₃ , PC1 ₃ , PBr ₃ , PF ₃ , PF ₅ , P ₂ 0 ₅ , P0C1 ₃ , AsH ₃ , AsCl ₃ , AsF ₃ , AsF ₅ , H ₂ S, H ₂ Se or H ₂ Te; process parameters include background pressure and working pressure of the injection chamber, flow rate of the injected gas, velocity of the extracted gas, mixed gas Composition, composition ratio and concentration, output power and frequency of the plasma power source, bias voltage applied by the power supply to which the bias voltage can be applied, and pulse width, duty cycle and frequency if pulsed;

The background pressure of the injection chamber may range from 10 to ⁷ Pa to 100 OOPa, preferably from 10 to ⁵ Pa to 10 Pa, more preferably from 10 to ⁵ Pa to 10 to ³ Pa; and the working pressure of the injection chamber The range may be 10 - ³ Pa ~ lOOOPa, preferably 0.01 Pa - 100 Pa, more preferably O.lPa - 50 Pa; the flow rate of the mixed gas may be 1 - 1000 sccm, preferably 10 - 100 sccm, more preferably The ground power may be 20 to 80 sccm; the output power of the plasma power source is 1 to 100000 W, preferably 10 to 50000 W, more preferably 300 to 5000 W; the applied bias voltage is -100,000 to 100,000 V, preferably -50000 ~ 50000 V, more preferably -10000 ~ 0 V; pulse width is 1 us ~ 1 s, preferably lus ~ 0.1 s, more preferably lus ~ l ms; duty cycle is 1 % ~ 99%, preferably 10% ~ 90%, more preferably 20% ~ 80%, the frequency of the plasma power source is DC ~ 10GHz, preferably 1MHz ~ 5GHz, more preferably 13.56MHz ~ 5GHz; the frequency of the power supply to which the bias voltage can be applied is DC ~ 10GHz;

Step 104: After the plasma is generated and immersed in the silicon wafer, the electric field of the sheath layer formed between the silicon wafer and the plasma is accelerated by applying a bias voltage to the silicon wafer, and is located in the sheath electric field and enters from the plasma. The ions of the sheath electric field are directly injected into the silicon wafer; for example, in the case where the injected gas is a mixed gas composed of SF ₆ , 0 ₂ and H ₂ Se, after ionization, SF ₆ and 0 ₂ respectively have an etching effect. F* group and a 0* group having a passivation effect, wherein the F* group forms an etch by Si by forming SiF ₄ with Si; meanwhile, the 0* group forms Si _{x on the} surface of the etched wall O _y F _z , which has a passivation effect on the etched wall; Therefore, under the dual action of etching and passivation, black silicon having a porous or network structure is finally formed; an ion or ionic group having a doping element, such as the above mixed gas of SF ₆ , 0 ₂ and H ₂ Se Producing a group containing Se ions, injecting into black silicon under the acceleration of the implantation voltage, in-situ doping black silicon, the doping concentration of the doped black silicon is greater than 1E15 cm" ³ , and the doping concentration is controllable; , black silicon preparation and in-situ doping can be carried out simultaneously;

 Step 105: post-processing the in-situ doped black silicon;

 The in-situ doped black silicon post-treatment includes black silicon cleaning, polishing, annealing, etching, texturing (also known as texturing) and/or patterning.

 Example 2

 Referring to FIG. 2, an embodiment of the present invention provides a second embodiment of a method for preparing doped black silicon in situ by plasma immersion ion implantation, including the following steps:

 Step 201: pretreating the silicon wafer;

 Silicon wafer pretreatment includes wafer cleaning, polishing, doping, annealing, etching, texturing (also known as texturing) and/or patterning, and the shape can be round, square or rectangular. a conventional shape, or any other complicated shape;

 Step 202: placing the silicon wafer in a black silicon preparation device;

 The black silicon preparation device may be a plasma immersion ion implanter, the silicon wafer is placed in the injection chamber of the device, and placed on the sample stage; in some embodiments, the black silicon preparation device includes a power source to which a bias voltage can be applied, The silicon wafer is electrically connected to the sample stage. Since the sample stage is electrically connected to a power source to which a bias voltage can be applied, the silicon wafer is electrically connected to a power source to which a bias voltage can be applied. Under certain conditions, the startup can be biased. A voltage source can apply a bias voltage to the silicon wafer;

Step 203: Passing a mixed gas having etching and passivation into the black silicon preparation device, and adjusting a process parameter of the black silicon preparation device to reach a working condition capable of generating plasma; The gas having etching action includes SF ₆ , CF ₄ , CHF ₃ , C ₄ F ₈ , NF ₃ , SiF ₄ , C ₂ F ₆ , HF, BF ₃ , PF ₃ , Cl ₂ , HCl, SiH ₂ Cl ₂ , SiCl ₄ , BC1 ₃ or HBr; the passivating gas includes 0 ₂ , N ₂ 0 or N ₂ ; the process parameters include the background pressure and working pressure of the injection chamber, the flow rate of the injected gas, the velocity of the extracted gas, and the mixing Gas composition, composition ratio and concentration, output power and frequency of the plasma power source, bias voltage applied by the power supply to which the bias voltage can be applied, and pulse width, duty cycle and frequency if pulsed;

The background pressure of the injection chamber may range from 10 to ⁷ Pa to 100 OOPa, preferably from 10 to ⁵ Pa to 10 Pa, more preferably from 10 to ⁵ Pa to 10 to ³ Pa; and the working pressure of the injection chamber The range may be 10 - ³ Pa ~ lOOOPa, preferably 0.01 Pa - 100 Pa, more preferably O.lPa - 50 Pa; the flow rate of the mixed gas may be 1 - 1000 sccm, preferably 10 - 100 sccm, more preferably The ground power may be 20 to 80 sccm; the output power of the plasma power source is 1 to 100000 W, preferably 10 to 50000 W, more preferably 300 to 5000 W; the applied bias voltage is -100,000 to 100,000 V, preferably -50000 ~ 50000 V, more preferably -10000 ~ 0 V; pulse width is 1 us ~ 1 s, preferably lus ~ 0.1 s, more preferably lus ~ l ms; duty cycle is 1 % ~ 99%, preferably 10% ~ 90%, more preferably 20% ~ 80%, the frequency of the plasma power source is DC ~ 10GHz, preferably 1MHz ~ 5GHz, more preferably 13.56MHz ~ 5GHz; the frequency of the power supply to which the bias voltage can be applied is DC ~ 10GHz;

Step 204: After the plasma is generated and immersed in the silicon wafer, the electric field of the sheath layer formed between the silicon wafer and the plasma is accelerated by applying a bias voltage to the silicon wafer, and is located in the sheath electric field and enters from the plasma. The reactive ions of the sheath electric field are directly injected into the silicon wafer; for example, in the case where the injected gas is a mixed gas composed of SF ₆ and 0 ₂ , after ionization, SF ₆ and 0 ₂ respectively generate an F* having an etching effect. a group and a 0* group having a passivation effect, wherein the F* group forms an etch by Si by forming SiF ₄ with Si; meanwhile, the 0* group forms Si _x O _y F on the surface of the etched wall _z , inducing passivation on the etched wall; therefore, under the dual action of etching and passivation, finally forming a porous or network-like black silicon; Step 205: stopping the introduction of the gas, and withdrawing all the gases in the black silicon preparation device, keeping the formed black silicon in place; then introducing a mixed gas having a doping element into the black silicon preparation device, adjusting the black The process parameters of the silicon preparation device are such that the working conditions for the process can be achieved;

The mixed gas having a doping element includes B ₂ H ₆ , B(OCH ₃ ) ₃ , B ₂ 0 ₃ , BN, BC1 ₃ , BBr ₃ , BF ₃ , PH ₃ , PC1 ₃ , PBr ₃ , PF ₃ , PF ₅ , P ₂ 0 ₅ , POCl ₃ , AsH ₃ , AsCl ₃ , AsF ₃ , AsF ₅ , H ₂ S, H ₂ Se or H ₂ Te; process parameters including background pressure and working pressure of the injection chamber, injection gas Flow rate, velocity of the extracted gas, composition of the mixed gas, composition ratio and concentration, output power and frequency of the plasma power source, bias voltage applied by the power supply to which the bias voltage can be applied, and pulse width if pulsed , duty cycle and frequency;

The background pressure of the injection chamber may range from 10 to ⁷ Pa to 1000 Pa, preferably from 10 to ⁵ Pa to 10 Pa, more preferably from 10 to ⁵ Pa to 10 to ³ Pa; and the working pressure of the injection chamber The range may be 10 - ³ Pa - lOOOPa, preferably 0.01 Pa - lOOPa, more preferably O.lPa - 50 Pa; the flow rate of the mixed gas may be 1 - 1000 sccm, preferably 10 - 100 sccm, more preferably The ground power may be 20 to 80 sccm; the output power of the plasma power source is 1 to 100000 W, preferably 10 to 50000 W, more preferably 300 to 5000 W; the applied bias voltage is -100,000 to 100,000 V, preferably -50000 ~ 50000 V, more preferably -10000 ~ 0 V; pulse width is 1 us ~ 1 s, preferably lus ~ 0.1 s, more preferably lus ~ l ms; duty cycle is 1 % ~ 99%, preferably 10% ~ 90%, more preferably 20% ~ 80%, the frequency of the plasma power source is DC ~ 10GHz, preferably 1MHz ~ 5GHz, more preferably 13.56MHz ~ 5GHz; the frequency of the power supply to which the bias voltage can be applied is DC ~ 10GHz;

Step 206: After the plasma is generated, the mixed gas having the doping element is decomposed into ions or ionic groups having doping elements (for example, B ions, P ions, As ions, Se ions, Te ions or ionic groups, etc.) These ions or ionic groups are doped into black silicon under the acceleration of the implantation bias to prepare in-situ doped black silicon. The doping concentration of doped black silicon is greater than 1E15 cm- ³ , and the doping concentration is controllable. ; Step 207: Perform post-treatment on in-situ doped black silicon;

 The in-situ doped black silicon post-treatment includes black silicon cleaning, polishing, annealing, etching, texturing (also known as texturing) and/or patterning.

 In this embodiment, steps 205 to 206 may be repeated multiple times to achieve different doping of black silicon. Example 3

 Referring to FIG. 3, an embodiment of the present invention provides a third embodiment of a method for preparing doped black silicon in situ by plasma immersion ion implantation, including the following steps:

 Step 301: pretreating the silicon wafer;

 Silicon wafer pretreatment includes wafer cleaning, polishing, annealing, etching, texturing (also known as velvet) and/or patterning, and the shape can be circular, square or rectangular, etc. It can also be any other complicated shape;

 Step 302: placing the silicon wafer in the black silicon preparation device;

 The black silicon preparation device may be a plasma immersion ion implanter, the silicon wafer is placed in the injection chamber of the device, and placed on the sample stage; in some embodiments, the black silicon preparation device includes a power source to which a bias voltage can be applied, The silicon wafer is electrically connected to the sample stage. Since the sample stage is electrically connected to a power source to which a bias voltage can be applied, the silicon wafer is electrically connected to a power source to which a bias voltage can be applied. Under certain conditions, the startup can be biased. A voltage source can apply a bias voltage to the silicon wafer;

 Step 303: introducing a mixed gas having a doping element into the black silicon preparation device, and adjusting a process parameter of the black silicon preparation device to achieve a working condition capable of performing the process;

The mixed gas having a doping element includes B ₂ H ₆ , B(OCH ₃ ) ₃ , B ₂ 0 ₃ , BN, BC1 ₃ , BBr ₃ , BF ₃ , PH ₃ , PC1 ₃ , PBr ₃ , PF ₃ , PF ₅ , P ₂ 0 ₅ , POCl ₃ , AsH ₃ , AsCl ₃ , AsF ₃ , AsF ₅ , H ₂ S, H ₂ Se or H ₂ Te; process parameters including background pressure and working pressure of the injection chamber, injection gas Flow rate, velocity of extracted gas, composition of mixed gas, composition ratio and concentration, plasma The output power and frequency of the power supply, the bias voltage applied by the power supply to which the bias voltage can be applied, and, if pulsed, the pulse width, duty cycle, and frequency;

The background pressure of the injection chamber may range from 10 to ⁷ Pa to 100 OOPa, preferably from 10 to ⁵ Pa to 10 Pa, more preferably from 10 to ⁵ Pa to 10 to ³ Pa; and the working pressure of the injection chamber The range may be 10 - ³ Pa ~ lOOOPa, preferably 0.01 Pa - 100 Pa, more preferably O.lPa - 50 Pa; the flow rate of the mixed gas may be 1 - 1000 sccm, preferably 10 - 100 sccm, more preferably The ground power may be 20 to 80 sccm; the output power of the plasma power source is 1 to 100000 W, preferably 10 to 50000 W, more preferably 300 to 5000 W; the applied bias voltage is -100,000 to 100,000 V, preferably -50000 ~ 50000 V, more preferably -10000 ~ 0 V; pulse width is 1 us ~ 1 s, preferably lus ~ 0.1 s, more preferably lus ~ l ms; duty cycle is 1 % ~ 99%, preferably 10% ~ 90%, more preferably 20% ~ 80%, the frequency of the plasma power source is DC ~ 10GHz, preferably 1MHz ~ 5GHz, more preferably 13.56MHz ~ 5GHz; the frequency of the power supply to which the bias voltage can be applied is DC ~ 10GHz;

Step 304: After the plasma is generated, the mixed gas having the doping element is decomposed into ions or ionic groups having doping elements, and the ions or ionic groups are doped into the silicon wafer under the acceleration of the implantation bias. For doping of silicon, the doping concentration is controllable and greater than 1E15 cm- ³ ;

 Step 305: Stop the introduction of the mixed gas having the doping element, and extract all the gases in the black silicon preparation device, keep the doped silicon wafer in place; then pass into the black silicon preparation device with etching and blunt The mixed gas of the action, adjusting the process parameters of the black silicon preparation device to achieve a working condition capable of generating plasma;

The gas having etching action includes SF ₆ , CF ₄ , CHF ₃ , C ₄ F ₈ , NF ₃ , SiF ₄ , C ₂ F ₆ , HF, BF ₃ , PF ₃ , Cl ₂ , HCl, SiH ₂ Cl ₂ , SiCl ₄ , BC1 ₃ or HBr; gases with passivation include

0 ₂ , N ₂ 0 or N ₂ ; The process parameters include the background pressure and working pressure of the injection chamber, the flow rate of the injected gas, the velocity of the extracted gas, the composition of the mixed gas, the composition ratio and the concentration, and the plasma power supply. Output power and frequency, the bias voltage applied by the power supply to which the bias voltage can be applied, and, if pulsed, the pulse width, duty cycle, and frequency;

The background pressure of the injection chamber may range from 10 to ⁷ Pa to 100 OOPa, preferably from 10 to ⁵ Pa to 10 Pa, more preferably from 10 to ⁵ Pa to 10 to ³ Pa; and the working pressure of the injection chamber The range may be 10 - ³ Pa ~ lOOOPa, preferably 0.01 Pa - 100 Pa, more preferably O.lPa - 50 Pa; the flow rate of the mixed gas may be 1 - 1000 sccm, preferably 10 - 100 sccm, more preferably The ground power may be 20 to 80 sccm; the output power of the plasma power source is 1 to 100000 W, preferably 10 to 50000 W, more preferably 300 to 5000 W; the applied bias voltage is -100,000 to 100,000 V, preferably -50000 ~ 50000 V, more preferably -10000 ~ 0 V; pulse width is 1 us ~ 1 s, preferably lus ~ 0.1 s, more preferably lus ~ l ms; duty cycle is 1 % ~ 99%, preferably 10% ~ 90%, more preferably 20% ~ 80%, the frequency of the plasma power source is DC ~ 10GHz, preferably 1MHz ~ 5GHz, more preferably 13.56MHz ~ 5GHz; the frequency of the power supply to which the bias voltage can be applied is DC ~ 10GHz;

Step 306: After the plasma is generated and immersed in the silicon wafer, under the acceleration of the sheath electric field formed between the silicon wafer and the plasma by applying a bias voltage to the silicon wafer, it is located in the sheath electric field and enters from the plasma. The reactive ions of the sheath electric field are directly injected into the silicon wafer; for example, in the case where the injected gas is a mixed gas composed of SF ₆ and 0 ₂ , after ionization, SF ₆ and 0 ₂ respectively generate F* having an etching action. a group and a 0* group having a passivation effect, wherein the F* group forms an etch by Si by forming SiF ₄ with Si; meanwhile, the 0* group forms Si _x O _y F on the surface of the etched wall _z , inducing passivation on the etched wall; therefore, under the dual action of etching and passivation, finally forming a porous or network-like black silicon;

 Step 307: post-processing the in-situ doped black silicon;

 The in-situ doped black silicon post-treatment includes black silicon cleaning, polishing, annealing, etching, texturing (also known as texturing) and/or patterning.

In this embodiment, step 303 to step 304 may be repeated multiple times to implement different elements of black silicon (for example) Such as P, As, Se and Te), different concentrations and different proportions of doping.

 Example 4

 Referring to FIG. 4, an embodiment of the present invention provides a fourth embodiment of a method for preparing doped black silicon in situ by plasma immersion ion implantation, including the following steps:

 Step 401: pretreating the silicon wafer;

 Silicon wafer pretreatment includes wafer cleaning, polishing, annealing, etching, texturing (also known as velvet) and/or patterning, and the shape can be circular, square or rectangular, etc. It can also be any other complicated shape;

 Step 402: placing the silicon wafer in a black silicon preparation device;

 The black silicon preparation device may be a plasma immersion ion implanter, the silicon wafer is placed in the injection chamber of the device, and placed on the sample stage; in some embodiments, the black silicon preparation device includes a power source to which a bias voltage can be applied, The silicon wafer is electrically connected to the sample stage. Since the sample stage is electrically connected to a power source to which a bias voltage can be applied, the silicon wafer is electrically connected to a power source to which a bias voltage can be applied. Under certain conditions, the startup can be biased. A voltage source can apply a bias voltage to the silicon wafer;

 Step 403: Passing a mixed gas having a doping element into the black silicon preparation device, and adjusting a process parameter of the black silicon preparation device to achieve a working condition capable of performing the process;

The mixed gas having a doping element includes B ₂ H ₆ , B(OCH ₃ ) ₃ , B ₂ 0 ₃ , BN, BC1 ₃ , BBr ₃ , BF ₃ , PH ₃ , PC1 ₃ , PBr ₃ , PF ₃ , PF ₅ , P ₂ 0 ₅ , POCl ₃ , AsH ₃ , AsCl ₃ , AsF ₃ , AsF ₅ , H ₂ S, H ₂ Se or H ₂ Te; process parameters including background pressure and working pressure of the injection chamber, injection gas Flow rate, velocity of the extracted gas, composition of the mixed gas, composition ratio and concentration, output power and frequency of the plasma power source, bias voltage applied by the power supply to which the bias voltage can be applied, and pulse width if pulsed , duty cycle and frequency;

The background pressure of the injection chamber may range from 10 to ⁷ Pa to 100 OOPa, preferably from 10 to ⁵ Pa to 10 Pa. More preferably, it may be 10 - ⁵ Pa - 10 - ³ Pa; the working pressure of the injection chamber may range from 10 - ³ Pa to 100 OOPa, preferably from 0.01 Pa to 100 Pa, and more preferably from 0.1 Pa to 50 Pa. The flow rate of the mixed gas may be 1 to 1000 sccm, preferably 10 to 100 sccm, more preferably 20 to 80 sccm; the output power of the plasma power source is 1 to 100,000 W, preferably 10 to 50000 W, more Preferably, it may be 300 to 5000 W; the applied bias voltage is -100,000 to 100,000 V, preferably -50,000 to 50,000 V, more preferably -10000 to 0 V; and the pulse width is 1 us to 1 s, preferably Lus ~ 0.1 s, more preferably lus ~ l ms; duty ratio 1% ~ 99%, preferably 10% ~ 90%, more preferably 20% ~ 80%, plasma power supply The frequency is DC ~ 10 GHz, preferably 1 MHz ~ 5 GHz, more preferably 13.56 MHz ~ 5 GHz; the frequency of the power supply capable of applying a bias voltage is DC ~ 10 GHz;

 Step 404: After the plasma is generated, the mixed gas having the doping element is decomposed into ions or ionic groups having doping elements (for example, B ions, P ions, As ions, Se ions, Te ions or ionic groups, etc.) These ions or ionic groups are doped into the silicon wafer under the acceleration of the implantation bias to achieve doping of silicon;

 Step 405: Stop the introduction of the mixed gas having the doping element, and extract all the gases in the black silicon preparation device, keep the doped silicon wafer in place; then pass into the black silicon preparation device with etching and Passivating mixed gas, adjusting the process parameters of the black silicon preparation device to achieve plasma working conditions;

The gas having etching action includes SF ₆ , CF ₄ , CHF ₃ , C ₄ F ₈ , NF ₃ , SiF ₄ , C ₂ F ₆ , HF, BF ₃ , PF ₃ , Cl ₂ , HCl, SiH ₂ Cl ₂ , SiCl ₄ , BC1 ₃ or HBr; gases with passivation include

0 ₂ , N ₂ 0 or N ₂ ; The process parameters include the background pressure and working pressure of the injection chamber, the flow rate of the injected gas, the velocity of the extracted gas, the composition of the mixed gas, the composition ratio and concentration, and the output power of the plasma power source. And frequency, the bias voltage applied by the power supply to which the bias voltage can be applied, including the pulse width, duty cycle, and frequency, if pulsed; The background pressure of the injection chamber may range from 10 to ⁷ Pa to 100 OOPa, preferably from 10 to ⁵ Pa to 10 Pa, more preferably from 10 to ⁵ Pa to 10 to ³ Pa; and the working pressure of the injection chamber The range may be 10 - ³ Pa ~ lOOOPa, preferably 0.01 Pa - 100 Pa, more preferably O.lPa - 50 Pa; the flow rate of the mixed gas may be 1 - 1000 sccm, preferably 10 - 100 sccm, more preferably The ground power may be 20 to 80 sccm; the output power of the plasma power source is 1 to 100000 W, preferably 10 to 50000 W, more preferably 300 to 5000 W; the applied bias voltage is -100,000 to 100,000 V, preferably -50000 ~ 50000 V, more preferably -10000 ~ 0 V; pulse width is 1 us ~ 1 s, preferably lus ~ 0.1 s, more preferably lus ~ l ms; duty cycle is 1 % ~ 99%, preferably 10% ~ 90%, more preferably 20% ~ 80%, the frequency of the plasma power source is DC ~ 10GHz, preferably 1MHz ~ 5GHz, more preferably 13.56MHz ~ 5GHz; the frequency of the power supply to which the bias voltage can be applied is DC ~ 10GHz;

Step 406: After the plasma is generated and immersed in the silicon wafer, under the acceleration of the sheath electric field formed between the silicon wafer and the plasma due to the application of the bias voltage to the silicon wafer, it is located in the electric field of the sheath and enters from the plasma. The reactive ions of the sheath electric field are directly injected into the silicon wafer; for example, in the case where the injected gas is a mixed gas composed of SF ₆ and 0 ₂ , after ionization, SF ₆ and 0 ₂ respectively generate an F* having an etching effect. a group and a 0* group having a passivation effect, wherein the F* group forms an etch by Si by forming SiF ₄ with Si; meanwhile, the 0* group forms Si _x O _y F on the surface of the etched wall _z , inducing passivation on the etched wall; therefore, under the dual action of etching and passivation, finally forming a porous or network-like black silicon;

 Step 407: Turn off all process gases, pass a mixed gas with doping elements into the black silicon preparation device, and adjust the process parameters of the black silicon preparation device to achieve working conditions for the process;

The mixed gas having a doping element includes B ₂ H ₆ , B(OCH ₃ ) ₃ , B ₂ 0 ₃ , BN, BC1 ₃ , BBr ₃ , BF ₃ , PH ₃ , PC1 ₃ , PBr ₃ , PF ₃ , PF ₅ , P ₂ 0 ₅ , POCl ₃ , AsH ₃ , AsCl ₃ , AsF ₃ , AsF ₅ , H ₂ S, H ₂ Se or H ₂ Te; process parameters including background pressure and working pressure of the injection chamber, injection gas Flow rate, velocity of extracted gas, composition of mixed gas, composition ratio and concentration, plasma The output power and frequency of the power supply, the bias voltage applied by the power supply to which the bias voltage can be applied, and, if pulsed, the pulse width, duty cycle, and frequency;

The background pressure of the injection chamber may range from 10 to ⁷ Pa to 100 OOPa, preferably from 10 to ⁵ Pa to 10 Pa, more preferably from 10 to ⁵ Pa to 10 to ³ Pa; and the working pressure of the injection chamber The range may be 10 - ³ Pa - lOOOPa, preferably 0.01 Pa - 100 Pa, more preferably 0.15 Pa - 50 Pa; the flow rate of the mixed gas may be 1 - 1000 sccm, preferably 10 - 100 sccm, more preferably It can be 20 ~ 80 sccm; the output power of the plasma power source is 1~100000 W, preferably 10~50000W, more preferably 300~5000 W; the applied bias voltage is -10000 ~ 100000V, preferably - 50000 ~ 50000 V, more preferably -10000 ~ 0 V; pulse width is 1 us ~ 1 s, preferably lus ~ 0.1 s, more preferably lus ~ l ms; duty cycle is 1% ~99%, preferably 10% to 90%, more preferably 20% to 80%, and the plasma power source has a frequency of from DC to 10 GHz, preferably from 1 MHz to 5 GHz, and more preferably from 13.56 MHz to 5 GHz. The frequency of the power supply to which the bias voltage can be applied is DC ~ 10 GHz;

Step 408: After the plasma is generated, the mixed gas having the doping element is decomposed into ions or ionic groups having doping elements (for example, B ions, P ions, As ions, Se ions, Te ions or ionic groups, etc.) The ions or ionic groups are doped into the black silicon under the acceleration of the implantation bias to prepare the doped black silicon in situ, and the doping concentration is controllable, and is greater than 1E15 cm- ³ ;

 Step 409: Perform post-treatment on in-situ doped black silicon;

 The in-situ doped black silicon post-treatment includes black silicon cleaning, polishing, annealing, etching, texturing (also known as texturing) and/or patterning.

 In this embodiment, step 403 to step 404, step 407 to step 408 may be repeated a plurality of times to achieve doping of different elements, different concentrations, and different ratios of black silicon.

 Example 5

Referring to FIG. 5, an embodiment of the present invention provides in-situ preparation of doping by plasma immersion ion implantation. A fifth embodiment of the method for hetero-black silicon includes the following steps:

 Step 501: pretreating the silicon wafer;

 Silicon wafer pretreatment includes wafer cleaning, polishing, annealing, etching, texturing (also known as velvet) and/or patterning, and the shape can be circular, square or rectangular, etc. It can also be any other complicated shape;

 Step 502: placing the silicon wafer in the black silicon preparation device;

 The black silicon preparation device may be a plasma immersion ion implanter, the silicon wafer is placed in the injection chamber of the device, and placed on the sample stage; in some embodiments, the black silicon preparation device includes a power source to which a bias voltage can be applied, The silicon wafer is electrically connected to the sample stage. Since the sample stage is electrically connected to a power source to which a bias voltage can be applied, the silicon wafer is electrically connected to a power source to which a bias voltage can be applied. Under certain conditions, the startup can be biased. A voltage source can apply a bias voltage to the silicon wafer;

 Step 503: introducing a mixed gas having a doping element into the black silicon preparation device, and adjusting a process parameter of the black silicon preparation device to achieve a working condition capable of performing the process;

The mixed gas having a doping element includes B ₂ H ₆ , B(OCH ₃ ) ₃ , B ₂ 0 ₃ , BN, BC1 ₃ , BBr ₃ , BF ₃ , PH ₃ , PC1 ₃ , PBr ₃ , PF ₃ , PF ₅ , P ₂ 0 ₅ , POCl ₃ , AsH ₃ , AsCl ₃ , AsF ₃ , AsF ₅ , H ₂ S, H ₂ Se or H ₂ Te; process parameters including background pressure and working pressure of the injection chamber, injection gas Flow rate, velocity of the extracted gas, composition of the mixed gas, composition ratio and concentration, output power and frequency of the plasma power source, bias voltage applied by the power supply to which the bias voltage can be applied, and pulse width if pulsed , duty cycle and frequency;

The background pressure of the injection chamber may range from 10 to ⁷ Pa to 1000 Pa, preferably from 10 to ⁵ Pa to 10 Pa, more preferably from 10 to ⁵ Pa to 10 to ³ Pa; and the working pressure of the injection chamber The range may be 10 - ³ Pa - lOOOPa, preferably 0.01 Pa - lOOPa, more preferably O.lPa - 50 Pa; the flow rate of the mixed gas may be 1 - 1000 sccm, preferably 10 - 100 sccm, more preferably Ground can be 20 ~ 80 sccm; plasma power supply The output power is from 1 to 100000 W, preferably from 10 to 50000 W, more preferably from 300 to 5000 W; the applied bias voltage is from -100,000 to 100,000 V, preferably from -50,000 to 50,000 V, more preferably It is -10000 ~ 0 V; the pulse width is 1 us ~ 1 s, preferably lus ~ 0.1 s, more preferably lus ~ l ms; the duty ratio is 1% ~ 99%, preferably 10% ~ 90 More preferably, it is 20% to 80%, and the frequency of the plasma power source is DC to 10 GHz, preferably 1 MHz to 5 GHz, more preferably 13.56 MHz to 5 GHz; the frequency of the power source to which the bias voltage can be applied DC ~ 10GHz;

 Step 504: After the plasma is generated, the mixed gas having the doping element is decomposed into ions or ionic groups having a doping element (for example, B ion, P ion, As ion, Se ion, Te ion or ionic group, etc.) These ions or ionic groups are doped into the silicon wafer under the acceleration of the implantation bias to achieve doping of silicon;

 Step 505: Stop introducing a mixed gas having a doping element, and extract all the gases in the black silicon preparation device; and then pass a mixed gas having etching, passivation, and doping elements into the black silicon preparation device. Adjusting the process parameters of the black silicon preparation device to a working condition capable of generating plasma;

The gas having etching action includes SF ₆ , CF ₄ , CHF ₃ , C ₄ F ₈ , NF ₃ , SiF ₄ , C ₂ F ₆ , HF, BF ₃ , PF ₃ , Cl ₂ , HCl, SiH ₂ Cl ₂ , SiCl ₄ , BC1 ₃ or HBr; a gas having a passivation includes 0 ₂ , N ₂ 0 or N ₂ ; a mixed gas having a doping element includes B ₂ H ₆ , B(OCH ₃ ) ₃ , B ₂ 0 ₃ , BN, BC1 ₃ , BBr ₃ , BF ₃ , PH ₃ , PC1 ₃ , PBr ₃ , PF ₃ , PF ₅ , P ₂ 0 ₅ , P0C1 ₃ , AsH ₃ , AsCl ₃ , AsF ₃ , AsF ₅ , H ₂ S, H ₂ Se or H ₂ Te; process parameters include background pressure and working pressure of the injection chamber, flow rate of the injected gas, velocity of the extracted gas, composition of the mixed gas, composition ratio and concentration, output power of the plasma power source, and Frequency, the bias voltage applied by the power supply to which the bias voltage can be applied, including the pulse width, duty cycle, and frequency, if pulsed;

The background pressure of the injection chamber may range from 10 to ⁷ Pa to 100 OOPa, preferably from 10 to ⁵ Pa to 10 Pa. More preferably, it may be 10 - ⁵ Pa - 10 - ³ Pa; the working pressure of the injection chamber may range from 10 - ³ Pa to 100 OOPa, preferably from 0.01 Pa to 100 Pa, and more preferably from 0.1 Pa to 50 Pa. The flow rate of the mixed gas may be 1 to 1000 sccm, preferably 10 to 100 sccm, more preferably 20 to 80 sccm; the output power of the plasma power source is 1 to 100,000 W, preferably 10 to 50000 W, more Preferably, it may be 300 to 5000 W; the applied bias voltage is -100,000 to 100,000 V, preferably -50,000 to 50,000 V, more preferably -10000 to 0 V; and the pulse width is 1 us to 1 s, preferably Lus ~ 0.1 s, more preferably lus ~ l ms; duty ratio 1% ~ 99%, preferably 10% ~ 90%, more preferably 20% ~ 80%, plasma power supply The frequency is DC ~ 10 GHz, preferably 1 MHz ~ 5 GHz, more preferably 13.56 MHz ~ 5 GHz; the frequency of the power supply capable of applying a bias voltage is DC ~ 10 GHz;

Step 506: After the plasma is generated and immersed in the silicon wafer, under the acceleration of the sheath electric field formed between the silicon wafer and the plasma due to the application of the bias voltage to the silicon wafer, it is located in the sheath electric field and enters from the plasma. The reactive ions of the sheath electric field are directly injected into the silicon wafer; for example, in the case where the injected gas is a mixed gas composed of SF ₆ , 0 ₂ and PH ₃ , after ionization, SF ₆ and 0 ₂ respectively have an etching effect. F* group and a 0* group having a passivation effect, wherein the F* group forms an etch by Si by forming SiF ₄ with Si; meanwhile, the 0* group forms Si _{x on the} surface of the etched wall O _y F _z , which inactivates the etched wall; therefore, under the dual action of etching and passivation, a black or porous structure of black silicon is finally formed; an ion or ionic group having a doping element, The mixed gas of SF ₆ , 0 ₂ and PH ₃ described above generates a P ion-containing group, and is injected into the black silicon under the acceleration of the injection voltage to prepare the doped black silicon in situ;

 Step 507: Turn off all process gases, pass a mixed gas with doping elements into the black silicon preparation device, and adjust the process parameters of the black silicon preparation device to achieve working conditions for the process;

The mixed gas having a doping element includes B ₂ H ₆ , B(OCH ₃ ) ₃ , B ₂ 0 ₃ , BN, BC1 ₃ , BBr ₃ , BF ₃ , PH ₃ , PC1 ₃ , PBr ₃ , PF ₃ , PF ₅ , P ₂ 0 ₅ , P0C1 ₃ , AsH ₃ , AsCl ₃ , AsF ₃ , AsF ₅ , H ₂ S, H ₂ Se or H ₂ Te; process parameters including background pressure and working pressure of the injection chamber, injection gas The flow rate of the body, the velocity of the extracted gas, the composition of the mixed gas, the composition ratio and concentration, the output power and frequency of the plasma power source, the bias voltage applied by the power supply to which the bias voltage can be applied, and the pulse form, including the pulse Width, duty cycle and frequency;

The background pressure of the injection chamber may range from 10 to ⁷ Pa to 100 OOPa, preferably from 10 to ⁵ Pa to 10 Pa, more preferably from 10 to ⁵ Pa to 10 to ³ Pa; and the working pressure of the injection chamber The range may be 10 - ³ Pa ~ lOOOPa, preferably 0.01 Pa - 100 Pa, more preferably O.lPa - 50 Pa; the flow rate of the mixed gas may be 1 - 1000 sccm, preferably 10 - 100 sccm, more preferably The ground power may be 20 to 80 sccm; the output power of the plasma power source is 1 to 100000 W, preferably 10 to 50000 W, more preferably 300 to 5000 W; the applied bias voltage is -100,000 to 100,000 V, preferably -50000 ~ 50000 V, more preferably -10000 ~ 0 V; pulse width is 1 us ~ 1 s, preferably lus ~ 0.1 s, more preferably lus ~ l ms; duty cycle is 1 % ~ 99%, preferably 10% ~ 90%, more preferably 20% ~ 80%, the frequency of the plasma power source is DC ~ 10GHz, preferably 1MHz ~ 5GHz, more preferably 13.56MHz ~ 5GHz; the frequency of the power supply to which the bias voltage can be applied is DC ~ 10GHz;

Step 508: After the plasma is generated, the mixed gas having the doping element is decomposed into ions or ionic groups having doping elements (for example, B ions, P ions, As ions, Se ions, Te ions or ionic groups, etc.) The ions or ionic groups are doped into the black silicon under the acceleration of the implantation bias to prepare the doped black silicon in situ, and the doping concentration is controllable, and is greater than 1E15 cm- ³ ;

 Step 509: post-processing the in-situ doped black silicon;

 The in-situ doped black silicon post-treatment includes black silicon cleaning, polishing, annealing, etching, texturing (also known as texturing) and/or patterning.

In this embodiment, steps 503 to 504, and steps 507 to 508 may be repeated multiple times to achieve doping of different elements, different concentrations, and different ratios of black silicon; in this example, steps 503 to 504 may be omitted. There may be no steps 507 to 508. In all the embodiments disclosed in the present invention, although the preparation of black silicon and the in-situ doping are sequential, the preparation of black silicon and in-situ doping are successively performed in the same process in the same apparatus.

 The objects, technical solutions and advantageous effects of the present invention are further described in detail in the specific embodiments described above. It should be understood that the above description is only illustrative of specific embodiments of the invention and is not intended to limit the invention. All modifications, equivalents, improvements, etc., made within the spirit and scope of the invention are intended to be included within the scope of the invention.

Claims

Claim  What is claimed is: 1. A method for in situ preparation of doped black silicon, the method comprising: placing a silicon wafer in an implantation chamber of a black silicon preparation device;  And introducing a mixed gas into the black silicon preparation device, wherein the mixed gas is composed of a gas having an etching action and a gas having a passivation effect, and adjusting a process parameter of the black silicon preparation device into a preset numerical range, The black silicon preparation device generates a plasma, and the reactive ions in the plasma react with the silicon wafer to form black silicon;  Stopping the mixed gas, and extracting all the gases in the black silicon preparation device; keeping the formed black silicon in place, introducing a gas having a doping element into the black silicon preparation device, adjusting the gas The process parameters of the black silicon preparation device enter a preset numerical range, and the black silicon preparation device generates a plasma, and ions or ionic groups having doping elements in the plasma are injected into the black silicon. In-situ preparation of doped black silicon is achieved.  2. The method of preparing doped black silicon in situ according to claim 1, wherein: the step of placing the silicon wafer in the implantation chamber of the black silicon preparation device further comprises: Electrical connection to the power supply to which the bias voltage is applied.  3. The method of preparing doped black silicon in situ according to claim 2, wherein: the process parameters include a background pressure and a working pressure of the injection chamber, a flow rate of the injected gas, a velocity of the extracted gas, and a mixture. The gas composition, composition ratio and concentration, the output power and frequency of the plasma power source, the bias voltage applied by the power source to which the bias voltage can be applied, and the plasma injection time. 4. The method of preparing doped black silicon in situ according to claim 3, wherein: the bias voltage is formed by combining a plurality of bias voltages, by adjusting the plasma injection time, the implanting The flow rate and composition ratio of the gas, the output power of the plasma power source, or the bias voltage are changed The doping concentration of the doped black silicon. The method for preparing doped black silicon in situ according to any one of claims 1 to 4, wherein: the gas having etching action comprises SF ₆ , CF ₄ , CHF ₃ , C ₄ F _8. NF ₃ , SiF ₄ , C ₂ F ₆ , HF, BF ₃ , PF ₃ , Cl ₂ , HCl, SiH ₂ Cl ₂ , SiCl ₄ , BC1 ₃ or HBr. The in-situ preparation method of doping black silicon according to any one of claims 1 to 4, wherein the gas having a passivation comprises 0 ₂ , N ₂ 0 or N ₂ . The method of preparing doped black silicon in situ according to any one of claims 1 to 4, wherein: the gas having a doping element comprises B ₂ H ₆ , B(OCH ₃ ) ₃ , B ₂ 0 ₃ , BN, BC1 ₃ , BBr ₃ , BF ₃ , PH ₃ , PC1 ₃ , PBr ₃ , PF ₃ , PF ₅ , P ₂ 0 ₅ , POCl ₃ , AsH ₃ , AsCl ₃ , AsF ₃ , AsF ₅ , H ₂ S, H ₂ Se or H ₂ Te. 8. The method of claim 3, the in-situ doped black silicon preparation, characterized in that: in the step of formation of black silicon in the injection chamber base pressure of 10- ⁷ Pa ~ lOOOPa, The working pressure is 10 - ³ Pa ~ lOOOPa, the flow rate of the mixed gas is 1 sccm ~ 1000 sccm, the output power of the plasma power source is 1W ~ 100000 W, and the applied bias voltage is -100,000 V ~ 100,000 V. The frequency is DC ~ 10GHz, and the frequency of the power supply to which the bias voltage can be applied is DC ~ 10GHz, 0.01 ~ 100. 9. The method of claim 3 in-situ doped black silicon preparation as claimed in claim, wherein: said step of black silicon doped in the injection chamber base pressure of 10- ⁷ Pa ~ lOOOPa The working pressure is 10" Pa ~ lOOOPa, the flow rate of the gas with doping elements is 1 sccm ~ 1000 sccm, the output power of the plasma power source is 1 W ~ 100000 W, and the applied bias voltage is -100,000 V ~ 100000V, the frequency of the plasma power supply is DC ~ 10GHz, the frequency of the power supply that can apply the bias voltage is DC ~ At 10 GHz, the doping concentration of the doped black silicon is greater than 1E15 cm- ³ .  10. A method of preparing doped black silicon in situ, the method comprising: placing a silicon wafer in an implantation chamber of a black silicon preparation device;  And introducing a mixed gas into the black silicon preparation device, wherein the mixed gas is composed of a gas having an etching action, a gas having a passivation effect, and a gas having a doping element, and adjusting a process parameter of the black silicon preparation device a predetermined range of values, the black silicon preparation device generates a plasma, and reactive ions in the plasma react with the silicon wafer to form black silicon, and at the same time, doping element ions in the plasma are implanted into the chamber In the black silicon, black silicon in-situ doping is completed.