A method for correcting lattice defects of silicon-based materials based on electric field action

Abstract

The present invention discloses a method for correcting lattice defects of silicon-based materials based on electric field action. The method for correcting lattice defects of silicon-based materials based on electric field action of the present invention corrects the lattice defects of the silicon-based material itself and the lattice defects generated during the wet etching process by preheating the silicon-based material after wet etching and applying a direct current electric field. Under high temperature conditions, the electron wind force generated by the electric field force acts on related electrons and atoms, so that the silicon-based material is restored to its original state, thereby improving the quality factor of the silicon-based material, enhancing its application performance and increasing its application prospects.

Description

Technical Field

[0001] The present invention relates to the field of micro-nano manufacturing technology, and in particular to a method for correcting lattice defects of silicon-based materials based on electric field action. Background Art

[0002] In today's rapidly advancing technological world, micro- and nanostructured materials are playing an increasingly important role. The potential applications of silicon-based materials with micro- and nanostructures lie primarily in three areas: optoelectronic devices, photonic devices, and leveraging their high porosity (or large specific surface area) as carriers for other devices. Wet etching is a common method used. Micro- and nanostructured silicon materials prepared by wet etching are characterized by simplicity, ease of operation, and suitability for etching large silicon areas and large-scale production. However, due to surface defects inherent in silicon-based materials and the inevitable chemical reactions that occur during the etching process, mechanical stresses build up within the material. This can lead to point or line defects in the crystal lattice of the wet-etched silicon. These defects can degrade the material's quality and limit its application. Summary of the Invention

[0003] In order to overcome the above-mentioned deficiencies of the prior art, the object of the present invention is to provide a method for correcting lattice defects of silicon-based materials based on electric field action.

[0004] In order to solve the above problems, the present invention adopts the following technical solutions:

[0005] The present invention provides a method for correcting lattice defects of silicon-based materials based on electric field action, comprising the following steps:

[0006] Cleaning the silicon-based material;

[0007] etching the cleaned silicon-based material using a wet etching method;

[0008] The silicon-based material after the etching process is first preheated, and then a direct current electric field is applied to correct lattice defects.

[0009] Preferably, the preheating treatment is performed at a temperature of 900-1300° C. and for a time of 20-30 minutes.

[0010] Preferably, the current of the DC electric field is 0-100 A, and the application time of the DC electric field is 20-30 min.

[0011] Preferably, the etching process is isotropic etching, and the etchant is a mixed solution of HNO3, HF and water.

[0012] Preferably, the mass ratio of HNO3, HF and water in the etchant is (4-9): (1-3): (1-3).

[0013] Preferably, CH3COOH solution is also added to the etchant.

[0014] Preferably, the mass ratio of HNO3, HF, CH3COOH and water in the etchant is (4-9): (1-3): (0.1-0.5): (1-3).

[0015] Preferably, the cleaning process comprises the following steps:

[0016] First, place the silicon-based material in a hydrocarbon cleaning agent for soaking and cleaning;

[0017] Then rinse the silicon-based material with deionized water;

[0018] Then, the silicon-based material is immersed in anhydrous ethanol for cleaning;

[0019] Finally, the silicon-based material is placed in an acidic solution for soaking and cleaning.

[0020] Preferably, the acidic solution is an HF solution.

[0021] Compared with the prior art, the technical effects of the present invention are embodied in:

[0022] The present invention provides a method for correcting lattice defects of silicon-based materials based on electric field action. The method preheats the silicon-based material after wet etching and applies a DC electric field to correct the lattice defects of the silicon-based material itself and the lattice defects generated during the wet etching process. Under high temperature conditions, the electron wind force generated by the electric field force acts on related electrons and atoms, so that the silicon-based material is restored to its original state, thereby improving the quality factor of the silicon-based material, enhancing its application performance and increasing its application prospects.

[0023] Additional advantages, objects, and features of the present invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art after studying the following or may be learned from practice of the present invention.

[0024] Those skilled in the art will understand that the purposes and advantages that can be achieved by the present invention are not limited to the above specific descriptions, and the above and other purposes that can be achieved by the present invention will be more clearly understood based on the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the principle of correcting lattice point defects of silicon-based materials based on electric field action provided by an embodiment of the present invention;

[0026] Figure 2 A schematic diagram of the principle of correcting lattice line defects in silicon-based materials based on electric field action provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0028] It should be noted that the process equipment or devices not specifically specified in the following embodiments are all conventional equipment or devices in the art.

[0029] In addition, it should be understood that one or more method steps mentioned in the present invention do not exclude the existence of other method steps before or after the combination step or the insertion of other method steps between these explicitly mentioned steps, unless otherwise specified; and, unless otherwise specified, the numbering of each method step is merely a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to define the scope of implementation of the present invention. Changes or adjustments in their relative relationships, without substantially changing the technical content, should also be regarded as the scope of implementation of the present invention.

[0030] An embodiment of the present invention provides a method for correcting lattice defects in silicon-based materials based on electric field action, comprising the following steps:

[0031] (1) Cleaning the silicon-based material;

[0032] (2) etching the cleaned silicon-based material using a wet etching method;

[0033] (3) The etched silicon-based material is preheated and then a DC electric field is applied to correct the lattice defects.

[0034] Before cleaning, the silicon-based material (silicon wafer) is cut into samples of appropriate size, and then the samples are placed in a hydrocarbon cleaning agent for soaking and cleaning. In order to facilitate the experiment, the silicon wafer is cut into several pieces of 3cm*3cm in size and 500um~1000um in thickness, some of which are used for the experiment and some for the control group after the experiment. Since there will be impurities on the surface of the silicon wafer, in order to reduce the undesirable factors during the etching process and the addition of the electric field later, the surface needs to be cleaned. Among them, the cleaning treatment in the above step (1) may specifically include the following steps: 1) first, the sample silicon wafer is placed in a hydrocarbon cleaning agent for cleaning to dissolve the organic matter on the surface of the silicon wafer; 2) then rinsed with deionized water several times; 3) the sample is continued to be placed in anhydrous ethanol to dissolve the remaining organic matter; 4) then the sample is immersed in an acidic solution to remove the silicon oxide on the surface of the silicon wafer, and the acidic solution is preferably HF solution; finally, the sample is dried in a vacuum drying oven.

[0035] In the above step (2), the etching process uses a wet etching method to etch the silicon wafer. HF or KOH solutions can be used. The most common silicon etching method used in the embodiment of the present invention is isotropic etching. The etchant is a mixture of HNO3, HF and water (or CH3COOH). Etching process: First, HNO3 reacts on the surface of the silicon wafer to form a dense SiO2 film. This film is insoluble in HNO3 and water. HF can dissolve SiO2. This process is carried out continuously. Water is used to dilute the etchant. CH3COOH acts as a buffer solvent to inhibit the decomposition of HNO3 and maintain the concentration of HNO3. The overall reaction equation is: Si + HNO3 + 6HF → H2SiF6 + HNO2 + H2+ H2O. The reaction rate can be adjusted by changing the temperature of the solution and the ratio of HNO3 to HF, and then by diluting with water or adding a buffer. When the HNO3 concentration is low, there's enough HF in the etchant to dissolve SiO2, and the silicon etching rate is determined by the HNO3 concentration. When the HF concentration is low, the silicon etching rate is determined by the HF concentration. When the etchant is a mixed solution of HNO3, HF, and water, the mass ratio of HNO3, HF, and water is (4-9):(1-3):(1-3). When the etchant is a mixed solution of HNO3, HF, CH3COOH, and water, the mass ratio of HNO3, HF, CH3COOH, and water is (4-9):(1-3):(0.1-0.5):(1-3).

[0036] In the above step (3), the preheat treatment of the etched silicon wafer is carried out in a high-temperature furnace connected to an electrode plate and equipped with current overload protection. Preferably, the preheat treatment temperature is 900-1300°C and the time is 20-30 minutes. The preheat treatment allows the silicon wafer to reach the required state for the experiment, shortening the experimental time. Then, under the high temperature state, a DC electric field is applied. Preferably, the current of the DC electric field is 0-100A and the application time of the DC electric field is 20-30 minutes. Under the action of the electric field, the high temperature state generated by the strong current makes the atoms more active, accelerates the correction process, and causes the silicon atoms to move to the lattice defects in the form of lattice diffusion.

[0037] In the above step (3), the control of the preheating temperature is relatively important. Generally, the temperature variation range needs to be controlled within about 1000°C, preferably 900-1300°C, so that the preheating temperature does not exceed the melting point of the silicon wafer, and the silicon wafer can clearly feel the influence of the electron wind force on it when the electric field acts.

[0038] The present invention provides a method for correcting lattice defects of silicon-based materials based on electric field action. The method preheats the silicon-based material after wet etching and applies a DC electric field to correct the lattice defects of the silicon-based material itself and the lattice defects generated during the wet etching process. Under high temperature conditions, the electron wind force generated by the electric field force acts on related electrons and atoms, so that the silicon-based material is restored to its original state, thereby improving the quality factor of the silicon-based material, enhancing its application performance and increasing its application prospects.

[0039] The correction method of the present invention can offset the adverse effects of mechanical stress inside the silicon wafer, and ultimately ensure that the silicon wafer surface can dominate the internal structure and form stably without the interference of internal mechanical stress, thereby correcting the point defects of the silicon wafer. The correction principle is as follows: Figure 1 As shown in the figure, due to the large number of free electrons within the silicon wafer, an additional electric field exerts an electron wind on the electrons. The electric field and the electron wind force are in the same direction. Driven by this electron wind force, the electrons collide with silicon atoms, transferring some of their energy to the atoms. This increases the kinetic energy of the silicon atoms and forces them to move toward lattice defects, thereby correcting point defects.

[0040] The principle of the correction method of the present invention for correcting line defects is as follows: Figure 2 As shown, the dislocation at point A moves forward under the action of the electron wind and does not develop into a rotating spiral, as shown in Figure 2 As shown in Figure a, the dislocation develops from line 1 to line 5. Because the direction of the electron wind force applied to the dislocation is consistent with the direction of electron drift, the force is not perpendicular to the dislocation. Finally, the dislocation perpendicular to the direction of the drifting electron moves toward the grain boundary or annihilates during the movement, while the dislocation parallel to the direction of the drifting electron remains unchanged under the action of the electron wind and becomes straight. Figure 2 As shown in c, it is like a piece of seaweed flowing into the water. When point A and point B are fixed at the same time, as shown in Figure 2 As shown in b, the dislocation forms a positive arc under the action of the electron wind. When the electron wind force is greater than the critical restoring force of the dislocation, the dislocation moves forward, as shown in Figure 2 As shown in d. Figure 2 As can be seen in Figure e, if the dislocation on the slip plane is not pinned, the dislocation will move forward until it is blocked by some obstacle and becomes an arc.

[0041] In general, although the direction of electron drift and the electron wind force alternate with the direction of current flow, analysis shows that the current density in the initial direction is always greater than that in the subsequent reverse direction. Therefore, the combined effect of the electron wind force on dislocations aligns with the direction of the initial electron drift. When the electron wind acts on a dislocation cluster, the dislocation moves forward under the influence of the electron force. When a dislocation is pinned by a dislocation tangle, it stretches forward like a sheet of flowing seaweed. When the dislocation is loosely pinned, the electron wind pulls the dislocation out of its original position and moves it forward, gradually untangling the dislocation tangle and beginning to disperse toward the edge. When a dislocation is blocked by the dislocation tangle, the electron wind force bends it in the direction of electron drift, forming a small arc whose resistance is equal to the electron wind force. This correspondence can be used to calculate the magnitude of the electron wind force. Under the influence of drifting electrons, the movement of vacancies and dislocations is enhanced, accelerating the rate of dislocation annihilation. Conversely, under the influence of electron drift, the silicon wafer does not generate a large number of dislocations, resulting in a simultaneous decrease in the dislocation multiplication rate. Finally, the dislocation density decreases, and the dislocation structure realigns parallel to the direction of the drifting electrons. In the correction method of the present invention, dislocations are also affected by residual stress, making it difficult to determine the proportion of the electron wind force. However, the dislocation curvature can be used to characterize the magnitude of the electron wind force.

[0042] After using the correction method of the present invention to correct the lattice defects of silicon wafers, it was found that the silicon wafers after the defects were corrected by the electric field had a higher quality factor and better absorption of light. In application, it can greatly improve the conversion efficiency of solar cells and also improve the performance of high-purity silicon as a semiconductor material, and have good feedback results in aspects such as optical communications.

[0043] The following is further described with reference to specific embodiments.

[0044] Example 1

[0045] Embodiment 1 of the present invention provides a method for correcting lattice defects of silicon-based materials based on electric field action, comprising the following steps:

[0046] Step 1: Take a piece of silicon with a size of 3cm*3cm and a thickness of 500um, place it in a hydrocarbon cleaning agent to clean it and dissolve the organic matter on the surface; then rinse it several times with deionized water; place the sample in anhydrous ethanol to dissolve the remaining organic matter; then soak the sample in HF acid solution to remove silicon oxides on the silicon surface, and finally dry the sample in a vacuum drying oven.

[0047] Step 2: Place the cleaned silicon in a mixture of HNO3, HF, and water (in a ratio of 8:1:1) and let it sit for 10 minutes. Step 3: Preheat the etched silicon in a high-temperature furnace (1000°C) equipped with an electrode plate and current overload protection for 20 minutes. Then, apply an electric field with a current of 60A. After 30 minutes, remove the silicon and observe it under an electron microscope.

[0048] Example 2

[0049] Embodiment 2 of the present invention provides a method for correcting lattice defects of silicon-based materials based on electric field action, comprising the following steps:

[0050] Step 1: Take a piece of silicon with a size of 3cm*3cm and a thickness of 800um, place it in a hydrocarbon cleaning agent to clean it and dissolve the organic matter on the surface; then rinse it several times with deionized water; place the sample in anhydrous ethanol to dissolve the remaining organic matter; then soak the sample in HF acid solution to remove silicon oxides on the silicon surface, and finally dry the sample in a vacuum drying oven.

[0051] Step 2: Place the cleaned silicon into a mixture of HNO3, HF and water in a ratio of 6:3:1 and let it stand for 15 minutes.

[0052] Step 3: Place the etched silicon in a high-temperature furnace (1200°C) connected to an electrode plate and with current overload protection for preheating for 20 minutes, then connect it to an electric field with a current intensity of 80A. After 20 minutes, take out the silicon and observe it under an electron microscope.

[0053] Example 3

[0054] Embodiment 3 of the present invention provides a method for correcting lattice defects of silicon-based materials based on electric field action, comprising the following steps:

[0055] Step 1: Take a piece of silicon with a size of 3cm*3cm and a thickness of 1000um, place it in a hydrocarbon cleaning agent to clean it and dissolve the organic matter on the surface; then rinse it several times with deionized water; place the sample in anhydrous ethanol to dissolve the remaining organic matter; then soak the sample in HF acid solution to remove silicon oxides on the silicon surface, and finally dry the sample in a vacuum drying oven.

[0056] Step 2: Place the cleaned silicon into a mixture of HNO3, HF and water in a ratio of 5:2:3 and let it stand for 20 minutes.

[0057] Step 3: Place the etched silicon in a high-temperature furnace (1000°C) connected to an electrode plate and with current overload protection and preheat for 30 minutes. Then connect it to an electric field with a current intensity of 40A. After 30 minutes, take out the silicon and observe it under an electron microscope.

[0058] Example 4

[0059] Embodiment 4 of the present invention provides a method for correcting lattice defects of silicon-based materials based on electric field action, comprising the following steps:

[0060] Step 1: Take a piece of silicon with a size of 3cm*3cm and a thickness of 1000um, place it in a hydrocarbon cleaning agent to clean it and dissolve the organic matter on the surface; then rinse it several times with deionized water; place the sample in anhydrous ethanol to dissolve the remaining organic matter; then soak the sample in HF acid solution to remove silicon oxides on the silicon surface, and finally dry the sample in a vacuum drying oven.

[0061] Step 2: Place the cleaned silicon into a mixture of HNO3, HF, CH3COOH and water in a ratio of 5:2:0.5:3 and let it stand for 20 minutes.

[0062] Step 3: Place the etched silicon in a high-temperature furnace (1000°C) connected to an electrode plate and with current overload protection and preheat for 30 minutes. Then connect it to an electric field with a current intensity of 90A. After 20 minutes, take out the silicon and observe it under an electron microscope.

[0063] The results of electron microscopy observations show that after the silicon wafers in Examples 1 to 4 of the present invention are corrected by the high-temperature electric field, the point defects and line defects inside and on the surface of the silicon wafers can be significantly eliminated.

[0064] The present invention is not limited to the above specific embodiments, and various modifications and variations are possible. Any modification, equivalent replacement, improvement, etc. made to the above embodiments based on the technical essence of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A method for correcting lattice defects of silicon-based materials based on electric field action, characterized in that: The following steps are involved: Cleaning the silicon-based material; etching the cleaned silicon-based material using a wet etching method; The silicon-based material after the etching process is first preheated at a temperature of 900-1300° C., and then a direct current electric field is applied under high temperature to correct lattice defects.

2. The method for correcting lattice defects of silicon-based materials based on electric field action according to claim 1, characterized in that: The preheating time is 20 to 30 minutes.

3. The method for correcting lattice defects of silicon-based materials based on electric field action according to claim 1, characterized in that: The current of the DC electric field is 0-100A, and the application time of the DC electric field is 20-30 minutes.

4. The method for correcting lattice defects of silicon-based materials based on electric field action according to claim 1, characterized in that: The etching process is isotropic etching, and the etchant is a mixed solution of HNO3, HF and water.

5. The method for correcting lattice defects of silicon-based materials based on electric field action according to claim 4, characterized in that: The mass ratio of HNO3, HF and water in the etchant is (4~9): (1~3): (1~3).

6. The method for correcting lattice defects of silicon-based materials based on electric field action according to claim 4, characterized in that: A CH3COOH solution is also added to the etchant.

7. The method for correcting lattice defects of silicon-based materials based on electric field action according to claim 6, characterized in that: The mass ratio of HNO3, HF, CH3COOH and water in the etchant is (4-9): (1-3): (0.1-0.5): (1-3).

8. The method for correcting lattice defects of silicon-based materials based on electric field action according to claim 1, characterized in that: The cleaning process comprises the following steps: First, place the silicon-based material in a hydrocarbon cleaning agent for soaking and cleaning; Then rinse the silicon-based material with deionized water; Then, the silicon-based material is immersed in anhydrous ethanol for cleaning; Finally, the silicon-based material is placed in an acidic solution for soaking and cleaning.

9. The method for correcting lattice defects of silicon-based materials based on electric field action according to claim 8, characterized in that: The acidic solution is an HF solution.

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