Abstract: This paper briefly introduces the structure and control technology of a single-wafer rotary etching/cleaning equipment, focusing on the control and software development aspects. User experience has proven that the system is reliable, flexible, and has a user-friendly interface. It is applicable to single-wafer rotary etching, cleaning, and development processes for 4″ to 8″ wafers. 1. Introduction With the further reduction in wafer diameter and device size, traditional tank-type batch cleaning technology is no longer suitable for wet cleaning due to various process factors. New cleaning processes need to be introduced to ensure that IC specifications, performance indicators, and reliability are not reduced due to contamination. This places demands on next-generation cleaning equipment that provides non-destructive and corrosion-damage-inhibiting cleaning. The further reduction in wafer diameter and device size has led to a continuous increase in wafer costs. The shortened yield and product cycle in the process have accelerated the application of single-wafer wet cleaning technology in IC manufacturing, making this technology a mainstream trend. 2. Equipment Structure and Composition This equipment is mainly used for single-wafer etching and cleaning processes in chip manufacturing. The entire machine adopts a modular structural design, mainly composed of a frame, a cleaning and etching chamber, an automatic wafer feeding and receiving mechanism using a folding-arm robotic arm, a wafer positioning mechanism on the cleaning worktable, a cleaning nozzle oscillation mechanism, an online heating system for etching solution and DI water, an electrical control system, a piping system, and an exhaust system. 3. Main Working Principle After power-on, the wafer cassette holder containing silicon wafers is placed in the wafer loading position, and a wafer cassette signal is output. Once everything is ready, the automatic operation program is started. The folding-arm robotic arm performs complex intelligent movements, picking up the silicon wafer from the wafer loading position and transferring it to the wafer positioning mechanism. After the wafer is centered, the robotic arm removes it and transfers it to the rotary chuck in the etching and cleaning chamber. The robotic arm then retracts, and the automatic etching and cleaning process begins. 4. Control System Composition The control system adopts centralized management and distributed control, and has functions such as process parameter management, dynamic monitoring of equipment operating status, and fault diagnosis. The control system hardware mainly consists of an Advantech industrial PC control unit, a robotic arm control module, a cleaning chamber control module, a safety detection module, an online heating system for etching solution and DI water, a DC motor controller, sensors, etc., connected via a dedicated communication module. The equipment has automatic and manual operation functions. Automatic operation automatically completes silicon wafer transfer, acid etching, and DI water rinsing according to the user-programmed process. All actions are interlocked to ensure equipment and personnel safety. The manual function completes all single-step actions for user maintenance and special needs. The entire electrical control system is installed at the front of the machine body, with the operating components, control switches, temperature controller, and emergency stop mechanism mounted on the front panel. 5. Control System Software 5.1 Software System Composition: This control software consists of a host computer control module and various slave computer control modules. Each slave computer control module has corresponding driver modules and drivers based on its hardware structure. The host computer software, developed in VC++, is responsible for the coordinated operation of all functional units of the entire equipment. Data communication with each slave module uses RS232 communication and mainly consists of the following functional modules. (1) Operation Module: The operation module includes initialization after the equipment is powered on and checking the initialization conditions for automatic operation of the equipment. The operation module confirms the current running process program and automatically executes a process program. This module also has a monitoring function and uses two-dimensional graphics to dynamically display the status of each station, as well as the relevant parameters and progress of the current process step, as shown in the figure below. (2) Process Setting Module: The process setting module is used to input process data and view the input process program and each process parameter, including functions such as checking the rationality of input data, deleting, modifying, and storing. The process program includes the cleaning step sequence and the cleaning time of each step, and the motor speed. Since the controller uses an industrial control computer, the number of process programs and the number of steps in each process program are no longer limited and can be added at will. (3) Debugging Module: The debugging module realizes the operation of independent units of the equipment, including reading the status of all I/O ports; opening and closing any solenoid valve; various start-stop and rotation tests of the motor; various operations of the circulating cooling heater and temperature sampling and graphic display; and testing of various actions of the robot, such as wafer scanning, wafer picking, and wafer placement. (4) Alarm Recording Module: The alarm recording module records various alarms that occur during the operation of the equipment, helping the operation engineer to analyze the equipment faults. (5) System Setting Module: The system setting module includes password management for operation users at all levels, as well as the setting of some system parameters, such as the starting acceleration of the spindle motor. 5.2 Software Structure 5.2.1 (1) Data Structure: In the software design process, the system defines the process step structure, alarm structure, and sampling temperature structure. The process structure is defined as typedef struct _ProcessStepData { CHAR m_strName[30]; int m_nRotateSp; int m_nTime; int m_nFunction; }PROCESSSTEPDATA_ST; which includes the process step name, process step function, process step time, and motor speed. The alarm structure is defined as typedef struct _WarningData { int m_nName; int m_nDescription; char m_strTime[21]; char m_strTimeClr[21]; int m_nLevel; bool m_bOccur; }WARNINGDATA_ST; which includes the alarm occurrence time, alarm cancellation time, alarm level, and alarm description. The temperature sampling structure is defined as typedef struct _TemperatureData { float m_fTemp; char m_strTime[20]; }TEMPERATUREDATA_ST; which includes the sampled temperature value and sampling time. A dynamic array is defined for each structure, and the array capacity can be increased arbitrarily as needed. The dynamic array of the process structure is defined as follows: `CArray m_arrProc;` To add a process step, perform the following operations: `PROCESSSTEPDATA_ST stProc;` Assign values ​​to the member variables of `stProc`: `m_arrProc.Add(stProc);` To modify a process step, perform the following operations: Assign values ​​to the member variables of `stProc`: `m_arrProc.SetAt(nIndex, stProc);` To insert a process step, perform the following operations: Assign values ​​to the member variables of `stProc`: `m_arrProc.InsertAt(nIndex, stProc);` To delete a process step, perform the following operations: Assign values ​​to the member variables of `stProc`: `m_arrProc.RemoveAt(nIndex);` The dynamic array of the alarm structure is defined as follows: `CArray m_arrWarning;` The dynamic array of the temperature structure is defined as follows: `CArray m_arrTemp;` Operations on alarm records and temperature sampling records are similar to those on process steps. 5.2.2 Software Flow: This flowchart mainly describes the equipment's operation process. First, the equipment is initialized. When the equipment is in normal condition, the automatic etching and cleaning process is started. First, the robotic arm scans the wafer cassette to determine the location of the wafers, then picks up the wafers and places them in the positioning mechanism for accurate positioning. Next, the robotic arm places the calibrated wafers into the etching and cleaning chamber. The control system etches, cleans, and dries the wafers according to the pre-set process files. After the process is completed, the robotic arm picks up the wafers from the etching and cleaning chamber and places them in the receiving cassette. The process flow for a single wafer is completed, and the robotic arm begins the process flow for the next wafer. 6. Conclusion Since its implementation at Beijing Yuxiang Electronics Co., Ltd. in 2007, this system has proven highly adaptable to various wafer etching and cleaning requirements due to its process flexibility. It offers strong real-time performance, reliable operation, and is particularly suitable for mass-produced products. About the author: Cao Xiufang, born in December 1965, is a senior engineer. She is mainly engaged in the research and development of semiconductor special equipment, with a focus on the development of equipment for wet etching and cleaning, rotary cleaning and drying of wafers. Her applications include IC production lines, silicon material production lines, gallium arsenide device production lines, solar cell production lines, and discrete device production lines.