CN116676083A - A kind of preparation method of etching solution - Google Patents

Abstract

The application relates to the technical field of etching solution preparation, and discloses a preparation method of etching solution, which comprises the following steps: step one, obtaining high-purity sodium fluosilicate and hydrogen peroxide; step two, adopting a microfluidic technology to put sodium fluosilicate and hydrogen peroxide into an ultrasonic reaction vessel filled with high-purity water, and reacting at room temperature until the reaction is finished; thirdly, after the reaction is finished, adding a stabilizer and a buffering agent, and uniformly stirring; sequentially adding a surfactant, mineral acid, organic acid and metal ions, fully stirring, and filtering to obtain an etching solution, wherein the pH value of the etching solution is 2-4; the purity of the sodium fluosilicate is more than 99.999 percent. The etching solution is prepared by mixing high-purity sodium fluosilicate, hydrogen peroxide and water, so that the etching rate of the etching solution changes along with the concentration change of sodium fluosilicate and hydrogen peroxide in the etching solution, and the effect of adjustable etching rate of the etching solution is further realized.

Description

A kind of preparation method of etching solution

technical field

The invention relates to the technical field of etching solution preparation, in particular to a preparation method of etching solution.

Background technique

Etching solution is one of the important processes in the manufacturing process of semiconductor devices, which is mainly used to remove excess materials or create fine structures. In the manufacturing process of semiconductor devices, amorphous silicon is one of the important intermediate materials, but it needs to be removed during the manufacturing process. Changes in rate requirements.

However, the etching rate of each traditional etching solution is fixed, and it is difficult to control the etching rate during use. At the same time, the traditional etching solution has the disadvantages of high cost and poor stability, and has certain pollution during the preparation process. , it is difficult to realize an etchant suitable for the production of most semiconductor devices, which limits its application in industrial manufacturing processes.

Contents of the invention

Aiming at the deficiencies of the prior art, the present invention provides a preparation method of etching solution, which solves the problem that the etching rate cannot be adjusted, and has the advantages of good stability, low cost and environmental protection.

To achieve the above object, the present invention is achieved through the following technical solutions: a preparation method of etching solution, the concentration of sodium fluorosilicate and hydrogen peroxide in the etching solution is proportional to the etching rate of the etching solution, comprising the following steps:

Step 1, obtaining high-purity sodium fluorosilicate and hydrogen peroxide;

Step 2, using microfluidic technology to put sodium fluorosilicate and hydrogen peroxide into an ultrasonic reaction vessel filled with high-purity water, and react at room temperature until the end of the reaction;

Step 3. After the reaction is over, add stabilizer and buffer and stir evenly;

Step 4: adding surfactant, mineral acid, organic acid, and metal ions in sequence, stirring thoroughly, and then filtering to obtain an etching solution with a pH value of 2-4.

Preferably, the purity of the sodium fluorosilicate is greater than 99.999%.

Preferably, the purity of the hydrogen peroxide is greater than 30%.

Preferably, the purity of the water is greater than 18MΩ.

Preferably, the surfactant includes sodium dodecylbenzene sulfonate, sodium dodecyl alcohol polyoxyethylene ether sulfate, sodium octyl alcohol polyoxyethylene ether sulfonate, and its content is 0.1-1.0 wt%.

Preferably, the mineral acid includes hydrofluoric acid, hydrochloric acid, nitric acid, and its content is 0.1-1.0wt%.

Preferably, the organic acid includes oxalic acid and acetic acid, the content of which is 0.1-1.0 wt%.

Preferably, the metal ions include copper ions and iron ions, the content of which is 10-1000 ppm, and they exist in the form of metal salts.

Preferably, the stabilizer includes diethylene glycol, isopropanol, tetrapropanol, and its content is 0.1-10wt%.

Preferably, the buffering agent includes acetic acid, acetic acid, sodium dihydrogen phosphate, and its content is 0.1-10wt%.

The invention provides a preparation method of etching solution. Has the following beneficial effects:

1. The present invention prepares an etching solution by mixing high-purity sodium fluorosilicate, hydrogen peroxide and water, so that the etching rate of the etching solution changes with the concentration of sodium fluorosilicate and hydrogen peroxide in the etching solution , specifically, the etching rate is directly proportional to the concentration, and then realizes the effect of adjusting the etching rate of the etching solution, and achieves the purpose of being suitable for different etching processes.

2. Through the addition of stabilizers, buffers, surfactants, mineral acids, organic acids, and metal ions, the present invention not only improves the stability of the etching solution and the selectivity during etching, but also improves the adjustable rate of the etching solution. The upper limit further improves its applicability.

3. Through the application of microfluidic technology and ultrasonic auxiliary technology, the present invention improves the efficiency of etching solution preparation and the uniformity of etching solution on the one hand, and on the other hand, ultrasonic waves can also destroy the interface active substances on the surface of the liquid, effectively reducing the preparation process. pollution and waste generation.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

An embodiment of the present invention provides a method for preparing an etching solution, the concentration of sodium fluorosilicate and hydrogen peroxide in the etching solution is proportional to the etching rate of the etching solution, comprising the following steps:

Step 1, obtaining high-purity sodium fluorosilicate and hydrogen peroxide;

Step 2, using microfluidic technology to put sodium fluorosilicate and hydrogen peroxide into an ultrasonic reaction vessel filled with high-purity water, and react at room temperature until the end of the reaction;

Step 3. After the reaction is over, add stabilizer and buffer and stir evenly;

Step 4: adding surfactant, mineral acid, organic acid, and metal ions in sequence, stirring thoroughly, and then filtering to obtain an etching solution with a pH value of 2-4.

According to the experimental results, the specific ratio of the concentration of sodium fluorosilicate and hydrogen peroxide to the etching rate can be adjusted according to actual needs. Generally, with the increase of the concentration of sodium fluorosilicate and hydrogen peroxide, the etching rate will increase accordingly , within a certain range, this relationship is linear, that is, the etching rate of the etching solution is proportional to the concentration of sodium fluorosilicate and hydrogen peroxide, but as the concentration increases, the etching rate will gradually saturate , until reaching the maximum value.

The etching solution is prepared by mixing high-purity sodium fluorosilicate, hydrogen peroxide and water, so that the etching rate of the etching solution changes with the concentration of sodium fluorosilicate and hydrogen peroxide in the etching solution. The rate is directly proportional to the concentration, and then realizes the effect of adjusting the etching rate of the etching solution, and achieves the purpose of being suitable for different etching processes.

Among them, microfluidic technology is a technology based on microchannels and microfluidic chips, which can realize fluid control at the micron level and has the characteristics of high efficiency, accuracy, and good repeatability. Microfluidic technology is used to The preparation of etching solution can achieve precise reaction control, improve reaction efficiency and uniformity, and reduce waste generation; at the same time, this technology can also realize the separation and control of multi-component reactions, so as to obtain higher reaction efficiency and products quality.

Ultrasound is an auxiliary processing technology widely used in liquids. It can promote liquid-solid reactions through the mechanical action of ultrasonic waves and the liquid flow and eddy currents caused by them, improve the uniformity of the reaction and enhance the reaction rate. Ultrasonic assisted methods are used to prepare Etching solution can promote physical processes such as mass transfer and diffusion during the reaction process by stimulating mechanical vibration in the liquid phase, improve reaction efficiency and uniformity, and reduce waste generation.

Through the application of microfluidic technology and ultrasonic auxiliary technology, on the one hand, the efficiency of etching solution preparation and the uniformity of etching solution are improved. On the other hand, ultrasonic waves can also destroy the interface active substances on the surface of the liquid, effectively reducing pollution and Waste generation.

The purity of sodium fluorosilicate is greater than 99.999%.

The purity of sodium fluorosilicate is greater than 99.999% to ensure the quality and stability of the etching solution. In the process of preparing the etching solution, if the purity of the sodium fluorosilicate is insufficient, the quality of the prepared etching solution will be unstable and prone to abnormal Uniform etching or over-etching and other problems, and high-purity sodium fluorosilicate can not only improve the quality and stability of the etching solution, but also effectively control the etching rate and precision, so as to obtain higher-quality semiconductor devices.

The purity of hydrogen peroxide is greater than 30%.

Hydrogen peroxide is a volatile and unstable liquid oxidant, which can effectively improve the etching rate and controllability of the etching solution. Hydrogen peroxide is usually prepared from a compound of water and hydrogen peroxide, and its purity directly affects the quality and stability of the etching solution. In the process of preparing the etching solution, if the purity of hydrogen peroxide is insufficient, the etching rate will be slow. Stable, even affect the quality of finished products, and high-purity hydrogen peroxide can not only improve the quality and stability of etching solution, but also can effectively control the etching rate and precision, so as to obtain higher quality semiconductor devices.

The purity of water is greater than 18MΩ.

Pure water is an important part of preparing etching solution, and its purity directly affects the quality and stability of etching solution. In general, the water used to prepare the etching solution needs to remove impurities such as ions, microorganisms, and organic substances in order to ensure the quality and stability of the etching solution. In actual use, water with higher purity can provide more stable and reliable etch effect. 18MΩ pure water is usually prepared through multiple processes such as multi-stage reverse osmosis, deionization and microporous filtration, and its purity can reach a high level, which can effectively reduce the content of ions in the etching solution, thereby Reduce the impurities of corrosion products and improve the quality and precision of etching.

The surfactant includes sodium dodecylbenzene sulfonate, sodium dodecyl alcohol polyoxyethylene ether sulfate, sodium octyl alcohol polyoxyethylene ether sulfonate, and its content is 0.1-1.0 wt%.

Adding surfactants in the process of preparing etching solution is to improve the interaction force between liquid and solid, thereby improving the wettability, uniformity and adhesion of etching solution. In the etching solution in preparing semiconductor devices, commonly used Surfactants include sodium dodecylbenzene sulfonate (SDBS), sodium dodecyl alcohol polyoxyethylene ether sulfate (AOT) and sodium octyl alcohol polyoxyethylene ether sulfonate (SLES), etc. These surfactants It has good solubility, stability and biodegradability, and can form a stable micelle structure in the etching solution, thereby improving the wettability and uniformity of the etching solution.

Mineral acids include hydrofluoric acid, hydrochloric acid, and nitric acid, and their content is 0.1-1.0 wt%.

The purpose of adding mineral acid is to improve the stability and etching rate of the etching solution. In the etching solution used in the preparation of semiconductor devices, the commonly used mineral acids are hydrofluoric acid (HF) and hydrochloric acid (HCl). Acid is more commonly used because it is more selective to silicon and has a higher etch rate and a sharper etch pattern. Hydrofluoric acid can also be mixed with other mineral acids. For example, adding a certain amount of nitric acid to a certain concentration of hydrofluoric acid can improve the stability and etching rate of the etching solution.

Organic acids include oxalic acid and acetic acid, the content of which is 0.1-1.0wt%.

Adding a certain amount of organic acid is to adjust the pH value and etching rate of the etching solution. In the etching solution for preparing semiconductor devices, commonly used organic acids include oxalic acid (H2C2O4) and acetic acid (CH3COOH). These organic acids can be freely The form of acid exists in the etching solution, which can adjust the pH value and stability of the etching solution, and can also be used as the source of hydrogen ions to increase the etching rate of the etching solution; the etching rate of oxalic acid on the silicon surface is low at low concentrations, but At high concentrations, the selectivity and clarity of the etching solution can be improved; acetic acid can also improve the clarity and selectivity of the etching solution, but its selectivity and stability are slightly worse than oxalic acid, which needs to be selected according to the specific semiconductor device process and requirements Appropriate organic acid, and proper concentration control and ratio adjustment to obtain the best etching effect.

Metal ions include copper ions and iron ions, the content of which is 10-1000ppm, and exists in the form of metal salts.

Adding a certain amount of metal ions can improve the etching rate and selectivity of the etching solution, and can also improve the clarity and dimensional stability of the etching pattern. In the etching solution in the preparation of semiconductor devices, the commonly used metal ions are copper ions (Cu2+ ) and iron ions (Fe3+), etc., these metal ions exist in the form of metal salts in the etching solution to improve the etching rate and selectivity of the etching solution; among them, copper ions can reduce the surface tension of the etching solution and promote the contact between the etching solution and silicon Surface contact can increase the etching rate and improve the etching pattern; iron ions can increase the stability of the etching solution, improve the selectivity of the etching solution, and can also control the etching rate.

The proportions of surfactants, mineral acids, organic acids, and metal ions should be adjusted and optimized according to the specific semiconductor device process and requirements to obtain the best etching effect.

The stabilizer includes diethylene glycol, isopropanol and tetrapropanol, and its content is 0.1-10wt%.

The buffering agent includes acetic acid, acetic acid, sodium dihydrogen phosphate, and its content is 0.1-10wt%.

By optimizing the formula and adding other components, such as stabilizers and buffers, the application range of the etching solution can be expanded, including other materials other than amorphous silicon, such as metals, oxides, nitrides, etc.; at the same time, the etching solution can also be Applied to similar etching processes in other industrial fields, such as the preparation of optical elements, microelectronic devices and other fields, in order to improve the stability of the etching solution and the controllability of the etching rate, the present invention adds a certain amount of stabilizers and buffers. The stabilizer is mainly used to prevent the chemical reaction of the etching solution, increase the stability and reliability of the etching solution, and reduce the change of the etching solution during storage and use. The buffer is used to adjust the pH value of the etching solution to prevent the acidity and alkalinity from being too high or too low, which will affect the performance and stability of the etching solution.

The addition of stabilizers, buffers, surfactants, mineral acids, organic acids, and metal ions not only improves the stability of the etching solution and the selectivity during etching, but also increases the upper limit of the adjustable rate of the etching solution, further improved its applicability.

According to the experimental results, the specific ratio of the concentration of sodium fluorosilicate and hydrogen peroxide to the etching rate can be adjusted according to actual needs. Generally, with the increase of the concentration of sodium fluorosilicate and hydrogen peroxide, the etching rate will increase accordingly . Within a certain range, this relationship is linear, that is, the etching rate of the etching solution is proportional to the concentration of sodium fluorosilicate and hydrogen peroxide. However, as the concentration increases, the etch rate will gradually saturate until it reaches the maximum value.

It can be seen that the adjustment of the etching rate depends on the concentration ratio of sodium fluorosilicate and hydrogen peroxide. In practical applications, the mass ratio of sodium fluorosilicate and hydrogen peroxide in the etching solution is generally determined first, and then the concentration range is determined. , and finally adjust the specific concentration according to the need to realize the control of the etching rate.

Therefore, in order to determine the specific relationship between the concentration and the etching rate, it is necessary to limit the experimental conditions, that is, on the premise of etching amorphous silicon, the concentrations of stabilizers, buffers, surfactants, mineral acids, organic acids, and metal ions are certain. Under the circumstances, the mass ratio of sodium fluorosilicate and hydrogen peroxide is 1:4, the concentration range is 0.5-5mol/L, and the results are shown in the following table:

Concentrations of sodium fluorosilicate and hydrogen peroxide etch rate 0.5mol/L 1nm/s 1mol/L 2nm/s 5mol/L 10nm/s

It should be noted that although the etching rate is proportional to the concentration of sodium fluorosilicate and hydrogen peroxide, over-etching or flattening will occur when the concentration is too high, so it needs to be adjusted according to the actual situation.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications and substitutions can be made to these embodiments without departing from the principle and spirit of the present invention. and modifications, the scope of the invention is defined by the appended claims and their equivalents.

Claims (10)

1. a preparation method of etching solution, is characterized in that, comprises the following steps: Step 1, obtaining high-purity sodium fluorosilicate and hydrogen peroxide; Step 2, using microfluidic technology to put sodium fluorosilicate and hydrogen peroxide into an ultrasonic reaction vessel filled with high-purity water, and react at room temperature until the end of the reaction; Step 3. After the reaction is over, add stabilizer and buffer and stir evenly; Step 4: adding surfactant, mineral acid, organic acid, and metal ions in sequence, stirring thoroughly, and then filtering to obtain an etching solution with a pH value of 2-4. 2. the preparation method of a kind of etching solution according to claim 1 is characterized in that, the purity of described sodium fluorosilicate is greater than 99.999%. 3. the preparation method of a kind of etching solution according to claim 1 is characterized in that, the purity of described hydrogen peroxide is greater than 30%. 4. the preparation method of a kind of etching solution according to claim 1, is characterized in that, the purity of described water is greater than 18MΩ. 5. the preparation method of a kind of etching solution according to claim 1 is characterized in that, described tensio-active agent comprises sodium dodecylbenzene sulfonate, sodium lauryl alcohol polyoxyethylene ether sulfate, octyl Sodium alcohol polyoxyethylene ether sulfonate, the content of which is 0.1-1.0 wt%. 6. The preparation method of a kind of etching liquid according to claim 1, is characterized in that, described mineral acid comprises hydrofluoric acid, hydrochloric acid, nitric acid, and its content is 0.1-1.0wt%. 7. The preparation method of a kind of etching solution according to claim 1, characterized in that, said organic acid comprises oxalic acid and acetic acid, and its content is 0.1-1.0wt%. 8. The preparation method of a kind of etching liquid according to claim 1, is characterized in that, described metal ion comprises copper ion, iron ion, and its content is 10-1000ppm, and exists with the form of metal salt. 9. The preparation method of a kind of etching liquid according to claim 1, is characterized in that, described stabilizing agent comprises diethylene glycol, isopropanol, tetrapropanol, and its content is 0.1-10wt%. 10. The preparation method of a kind of etching solution according to claim 1, characterized in that, the buffering agent comprises acetic acid, acetic acid, sodium dihydrogen phosphate, and its content is 0.1-10wt%.