A method of digitalizing a corrosion pattern

Abstract

The application relates to the technical field of semiconductors. A method for corroding a digital mode stores the crystal direction and the type of doping of a silicon wafer; during the corrosion process of the current silicon wafer, the concentration of a liquid medicine is detected through a concentration sensor, the crystal direction and the type of doping of the silicon wafer in the whole corrosion process are correlated with the concentration of the liquid medicine, and the concentration of the corrosion liquid medicine corresponding to the silicon wafer with different crystal directions and doping is obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor technology, in particular to a method for etching silicon wafers. BACKGROUND

[0002] In the surface cleaning process of semiconductor material silicon, the removal of surface damage layer after mechanical processing of silicon wafers, the thinning of directly bonded silicon wafers, and the chemical etching of defects in silicon, a chemical etching process of silicon is required.

[0003] The chemical etching of the silicon surface generally adopts a wet etching method. The surface etching of the silicon wafer forms randomly distributed micro-cells, and the etching current is relatively large, generally exceeding 100 mA / cm 2 However, due to the requirement for high purity of the etching liquid and reduction of possible metal ion pollution, the current mainly uses a mixed acid etching liquid of hydrofluoric acid (HF), nitric acid (HNO3) and acetic acid (CH3COOH).

[0004] In the entire etching process, each new liquid has a fixed number of uses; different crystal orientations and doping types of products are etched at different times. After the etching times, products that need to be processed urgently can only be processed after the subsequent replacement of the liquid and the corresponding etching times. SUMMARY

[0005] In view of the problems in the prior art, the present application provides a method for etching digitalization to solve at least one of the above technical problems.

[0006] In order to achieve the above purpose, the present application provides a method for etching digitalization, characterized in that the crystal orientation and the type of doping of the silicon wafer are stored and recorded;

[0007] In the etching process of the current silicon wafer, the concentration of the liquid is detected by a concentration sensor, and the crystal orientation and the type of doping of the silicon wafer and the concentration of the liquid are data correlated in the entire etching process.

[0008] The concentration of the etching liquid corresponding to the silicon wafer with different crystal orientations and doping is obtained.

[0009] Further preferably, the concentration sensor is an ABB concentration analyzer.

[0010] Further preferably, the concentration sensor records data every 30 seconds.

[0011] Further preferably, the time point of putting in the silicon wafer for etching and the time point of taking out the silicon wafer are recorded, and the current crystal orientation and doping type of the silicon wafer for etching are inputted; the concentration sensor monitors the concentrations of hydrofluoric acid, nitric acid and acetic acid in the chemical solution on line within the time range from the time point of putting in the silicon wafer for etching to the time point of taking out the silicon wafer, and stores them in the database.

[0012] Further preferably, the database is classified in three levels according to the crystal orientation of the silicon wafer, the doping type of the silicon wafer and the time sequence of the time points.

[0013] Further preferably, the database is stored in a server which is in communication connection with the host computer.

[0014] When the host computer inputs the crystal orientation and the doping type of the silicon wafer, the etching parameter information of the silicon wafer with the current crystal orientation and doping type is automatically retrieved from the database, and the etching parameter information includes the concentrations of hydrofluoric acid, nitric acid and acetic acid at the time point of putting in the silicon wafer for etching and the time point of taking out the silicon wafer.

[0015] Further preferably, before etching the silicon wafer, the concentrations of hydrofluoric acid, nitric acid and acetic acid in the current chemical solution are detected, and the concentrations of hydrofluoric acid, nitric acid and acetic acid in the chemical solution required for etching the current silicon wafer are compared with the concentrations of hydrofluoric acid, nitric acid and acetic acid in the current chemical solution; at least one of hydrofluoric acid, nitric acid and acetic acid is added to adjust the concentrations of the chemical solution for etching to the concentrations of hydrofluoric acid, nitric acid and acetic acid required for etching the current silicon wafer.

[0016] Further preferably, during the etching process of the silicon wafer, the concentration sensor detects the concentrations of hydrofluoric acid, nitric acid and acetic acid in the chemical solution in real time, and the concentration sensor transmits the concentration information to the host computer, and the host computer receives the time information recorded by the timer.

[0017] The host computer analyzes the concentration information and the time information, and the warning device gives a warning once the concentrations of hydrofluoric acid, nitric acid and acetic acid in the chemical solution reach the concentrations of hydrofluoric acid, nitric acid and acetic acid at the time point of taking out the silicon wafer or the time is within 10 minutes before the difference between the time point of putting in the silicon wafer for etching and the time point of taking out the silicon wafer.

[0018] Further preferably, the chemical solution for etching is a mixed acid solution with a mass percentage concentration of 9%-15% of hydrofluoric acid, a mass percentage concentration of 30%-35% of nitric acid and a mass percentage concentration of 15%-25% of acetic acid. DETAILED DESCRIPTION

[0019] The application will be further described below.

[0020] Specific embodiment 1, a method of corrosion digital mode, the crystal orientation of the silicon wafer and the type of doping are stored; during the current silicon wafer corrosion process, the concentration of the etching solution is detected by the concentration sensor, and the crystal orientation of the silicon wafer and the type of doping during the whole corrosion process are associated with the concentration of the etching solution; the concentration of the etching solution corresponding to the silicon wafer with different crystal orientation and doping is obtained.

[0021] The concentration sensor is an ABB concentration analyzer.

[0022] The silicon wafer etching put-in time point and the silicon wafer take-out time point are recorded, and at the same time, the crystal orientation and the doping type of the current etching silicon wafer are inputted; within the time range from the silicon wafer etching put-in time point to the silicon wafer take-out time point, the concentration of hydrofluoric acid, nitric acid and acetic acid in the etching solution is monitored online by the concentration sensor, and stored in the database.

[0023] The database is classified according to the crystal orientation of the silicon wafer, classified according to the doping type of the silicon wafer, and classified according to the sequence of the time points.

[0024] The database is stored in the server, and the server is in communication connection with the host;

[0025] When the host inputs the crystal orientation and the doping type of the silicon wafer, the etching parameter information of the silicon wafer with the current crystal orientation and doping type in the database is automatically retrieved, and the etching parameter information includes the concentrations of hydrofluoric acid, nitric acid and acetic acid at the silicon wafer etching put-in time point and the silicon wafer take-out time point.

[0026] Before the silicon wafer is etched, the concentrations of hydrofluoric acid, nitric acid and acetic acid in the current etching solution are detected, the concentrations of hydrofluoric acid, nitric acid and acetic acid in the etching solution required by the current silicon wafer are compared with the concentrations of hydrofluoric acid, nitric acid and acetic acid in the current etching solution, at least one of hydrofluoric acid, nitric acid and acetic acid is added, and the concentration of the etching solution is adjusted to the corresponding concentration of hydrofluoric acid, nitric acid and acetic acid required by the etching solution of the current silicon wafer.

[0027] During the silicon wafer etching process, the concentration sensor detects the concentrations of hydrofluoric acid, nitric acid and acetic acid in the etching solution in real time, the concentration sensor transmits the concentration information to the host, and the host receives the time information recorded by the timer;

[0028] The host analyzes the concentration information and the time information, and once the concentrations of hydrofluoric acid, nitric acid and acetic acid in the etching solution reach the concentrations of hydrofluoric acid, nitric acid and acetic acid corresponding to the silicon wafer take-out time point or the time is within 10 minutes before the difference between the silicon wafer etching put-in time point and the silicon wafer take-out time point, the warning device makes a pre-warning.

[0029] The corrosion liquid is a mixed acid liquid with mass percentage concentration of 9%-15% hydrofluoric acid, mass percentage concentration of 30%-35% nitric acid and mass percentage concentration of 15%-25% acetic acid.

[0030] The above merely is the preferred embodiment of the present application, it should be pointed out that, for the ordinary skilled in the art, without departing from the principles of the present application, can also make several improvements and refinements, these improvements and refinements also should be considered as the protection scope of the present application.

Claims

1. A method for etching a digital pattern, characterized in that, The crystal orientation and doping type of the silicon wafer are stored and recorded. During the etching process of the current silicon wafer, the concentration of the chemical solution is detected by a concentration sensor, and the crystal orientation and doping type of the silicon wafer are correlated with the concentration of the chemical solution throughout the etching process. To obtain the concentration of etching solution corresponding to silicon wafers with different crystal orientations and doping; The time points for etching the silicon wafer and the time points for removing the silicon wafer are recorded. At the same time, the crystal orientation and doping type of the silicon wafer being etched are input. Within the time range of the time points for etching the silicon wafer and the time points for removing the silicon wafer, the concentration sensor monitors the concentrations of hydrofluoric acid, nitric acid and acetic acid in the solution online and stores them in the database. The database is classified into three levels: first-level classification based on the crystal orientation of the silicon wafers, second-level classification based on the doping type of the silicon wafers, and third-level classification based on the chronological order of time.

2. The method for a digital corrosion pattern according to claim 1, characterized in that: The concentration sensor is an ABB concentration analyzer.

3. The method for a digital corrosion mode according to claim 1, characterized in that: The concentration sensor records data every 30 seconds.

4. The method for a digital corrosion mode according to claim 1, characterized in that: The database is stored on the server, and the server communicates with the host. When the host inputs the crystal orientation and doping type of the silicon wafer, it automatically retrieves the corrosion parameter information of the silicon wafer with the current crystal orientation and doping type from the database. The corrosion parameter information includes the concentrations of hydrofluoric acid, nitric acid, and acetic acid at the time the silicon wafer is placed in the etching process, and the concentrations of hydrofluoric acid, nitric acid, and acetic acid at the time the silicon wafer is removed.

5. The method for a digital corrosion pattern according to claim 1, characterized in that: Before etching the silicon wafer, the concentrations of hydrofluoric acid, nitric acid, and acetic acid in the current etching solution are measured. The required concentrations of hydrofluoric acid, nitric acid, and acetic acid in the etching solution for the current silicon wafer are compared with the current concentrations of hydrofluoric acid, nitric acid, and acetic acid in the etching solution. At least one of hydrofluoric acid, nitric acid, and acetic acid is added to adjust the concentration of the etching solution to the corresponding concentrations of hydrofluoric acid, nitric acid, and acetic acid required for the current silicon wafer.

6. The method for a digital corrosion pattern according to claim 5, characterized in that: During the silicon wafer etching process, concentration sensors detect the concentrations of hydrofluoric acid, nitric acid, and acetic acid in the solution in real time. The concentration sensors transmit the concentration information to the host computer, which then receives the time information recorded by the timer. The host analyzes the concentration and time information. Once the concentration of hydrofluoric acid, nitric acid, and acetic acid in the solution reaches the concentration of hydrofluoric acid, nitric acid, and acetic acid corresponding to the silicon wafer removal time, or if the time is 10 minutes before the difference between the silicon wafer etching placement time and the silicon wafer removal time, the warning device will issue an alert.

7. The method for a digital corrosion pattern according to claim 1, characterized in that: The corrosive solution is a mixture of hydrofluoric acid (9%-15% by mass), nitric acid (30%-35% by mass), and acetic acid (15%-25% by mass).