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Visualization and control of the etching of silicon wafers at the Belarusian company INTEGRAL in Minsk

August 9, 2016 | Reliance SCADA

INTEGRAL is a global development and production company that focuses on the supply of integrated circuits, semiconductors, LCDs, medical equipment, digital watches, and other products.


Source: www.integral.by



In 2015, the company's management decided to supply two wet benches for the etching of silicon wafers. The system for the control and visualization of the etching process, which was implemented by the CSVG company, is provided with a Tecomat TC700 PLC and the Reliance SCADA/HMI system. The GEOVAP company was responsible for developing software for the control system and for creating the visualization project.



Control system

The control system is installed in a hermetically sealed part of the wet bench. The entire wet bench is located in the technical zone of the production area. The control system is used to monitor and control the complete process, which involves the removal of silicon wafers' photoresist after performing the process of photolithography and the removal of residual dust particles smaller than one micrometer from the surface of the silicon wafers.


The removal of the photoresist is performed in a solution of sulfuric acid and hydrogen peroxide at a temperature of 120 °C. In this part of the process, the control system takes care of replenishing the loss of hydrogen peroxide in the etching solution and regulating the process temperature and the solution level.


Source: Pavel Redina, YouTube


Dust particles stick to the surface due to strong adhesive forces. To remove the particles, a solution of hydrogen peroxide, ammonium hydroxide, and demineralized water is used at a temperature of 75 °C. In this step, the control system evaluates the solution concentration again and, based on a request, keeps the solution concentration, temperature, and solution level constant.


According to a created process program, ultra-pure water quick dump rinses are applied to the silicon wafers between individual chemical processes. Based on the program, the Tecomat PLC controls the process of quick dump rinsing and monitors the purity and temperature of the water using a resistivity meter.


All handling is performed by a manipulator, which is controlled by another TC700 PLC and
a GT-7752 biaxial positioning module.


All data from the control system is passed to the industrial touch panel PC equipped with Reliance 4 Control. Using visualization screens, the Reliance SCADA/HMI system allows the operator to monitor the process and alarm reports, set parameters including recipes, and use trends and reports to view historical data.



Examples of visualization windows



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