HORIBA SEC-Z500X Mass Flow Controller

The Quality Flow Control Revolution in Semiconductor Manufacturing: A Comprehensive Analysis of the SEC-Z500X Series

Introduction: Challenges and Solutions in Gas Control

In the precision oriented field of semiconductor manufacturing, the success or failure of key processes such as atomic layer deposition and plasma etching often depends on a seemingly simple but extremely critical step - precise control of gas mass flow rate. The value of each wafer is based on chemical reactions with nanometer level precision, and the dose deviation of reactants will directly lead to a decrease in device performance or even scrap. Therefore, the Mass Flow Controller (MFC) is not only a component in the gas supply chain, but also a core strategic equipment that determines yield and production efficiency.

Faced with the semiconductor industry's pursuit of higher integration, larger wafer sizes, and more complex process structures, traditional MFCs are gradually becoming inadequate in terms of response speed, adaptability, and maintainability. To address this challenge, the market urgently needs a solution that can break through existing technological bottlenecks. This article will take the SEC-Z500X series as an example to explore in depth how it redefines the standards of high-performance quality flow control through a series of innovative designs, and provides engineers with a comprehensive guide from technical principles to practical applications.

Core Control Technology Innovation: Variable PID and High Speed Response

In processes such as thin film deposition, the response speed of MFC directly determines the length of the transition zone and the quality of the material interface. An inherent problem with traditional MFCs is that their PID (Proportional Integral Derivative) control parameters are typically optimized for Full Scale (F.S.) flow. When the process needs to operate at low flow rates (such as 2% or 10% of full scale), the same set of PID parameters often leads to slow system response or severe overshoot and oscillation.

The core breakthrough of the SEC-Z500X series lies in its installation of a "variable PID system". Unlike traditional fixed parameter algorithms, this technology can continuously and dynamically adjust the PID factor based on the current set flow point. This means that whether the user needs a high flow rate purge operation at 100% full scale or a precise deposition process fine tuned to 2% full scale, the controller can automatically match the optimal control logic.

According to test data, this technology enables the SEC-Z500X to achieve a response speed of less than 1 second across the entire flow range (from 0% to 100% F.S.). Specifically:

Step response (0 → 100% F.S.): The controller can quickly fully open the valve, establish flow quickly, and converge smoothly through an optimized PID algorithm near the set point without significant overshoot.

Small flow response (0 → 2% F.S.): This is the most difficult range to control with traditional MFCs. The variable PID system adopts high gain and low integration parameters within this range, which can achieve fast and stable flow establishment even at extremely small valve openings, eliminating the phenomenon of "stagnation" at low flow rates.

For process engineers, this means more compact process formulations, shorter by-product blowdown times, and more consistent low-speed flow control effects, providing a solid foundation for improving equipment capacity and process repeatability.

Disruption of operational efficiency: multi gas/multi range on-site configuration function

Semiconductor factories are typically complex environments with multiple gases (such as corrosive WF6, flammable H2, inert N2 and Ar) and multiple flow ranges coexisting. Traditionally, configuring dedicated MFCs for each gas and flow range means high spare parts inventory costs and lengthy replacement cycles. Once the process changes, old models of MFC may face scrapping, resulting in resource waste.

The SEC-Z500X series introduces the flexible concept of Multi Gas/Multi Range, making it a powerful tool for factory operation management. Its core lies in the dedicated configuration software provided by HORIBA STEC. Through this software, operators can change the applicable gas type and full-scale flow rate of MFC on site without removing it from the gas panel or pipeline.

The specific application scenarios are as follows:

Gas type change: The gas supply system of the equipment needs to switch from N2 to Ar. The operator does not need to replace the hardware, only needs to enter the new gas (Ar) and its working concentration range in the software, and the system will automatically call the corresponding thermodynamic parameters and conversion coefficients to recalibrate the MFC.

Full scale flow rate change: The process requirement has changed from the original SF6 flow rate of 100 SCCM (standard milliliters per minute) to 500 SCCM. Users do not need to purchase a new 500 SCCM specification MFC, they only need to change the full-scale setting value in the software and select the corresponding new MR/MG (range/gas) number.

In order to ensure the accuracy after the change, the core of this function is based on a large database of gas and flow ranges. For example, for N2 gas, the table provides multiple range options from R01 (3-10 SCCM) to R13 (2500-10000 SCCM). Users can select by MR/MG number, and the system can automatically map the valve stroke and sensor linearization curve. For more complex gases such as WF6, the system also provides dedicated numbers corresponding to different ranges such as 750-3000 SCCM.

This feature directly brings two major advantages: firstly, it significantly reduces spare parts inventory, and one MFC model can cover multiple process requirements; The second is to shorten the time for process switching and equipment reconfiguration, reducing hours or even days of modification work to just a few minutes of software operation.

Flexible communication architecture and system integration

In the automation system of modern semiconductor factories, MFC is no longer an isolated terminal, but an intelligent node in the factory host/PLC network. The SEC-Z500X series has proactively designed multiple communication interfaces to adapt to control system architectures of different scales and requirements.

1. Analog communication and RS-485

For traditional renovation projects or simple control systems, this series retains standard analog interfaces and provides them through D-sub 9-pin connectors:

Input: 0-5V DC flow setting signal.

Output: 0-5V DC flow monitoring signal.

Power supply: ± 15V DC power supply.

Meanwhile, the integrated RS-485 digital interface (RJ-45 connector) allows users to use a simple serial communication protocol (F-Net protocol) for parameter reading, writing, and status monitoring.

2. DeviceNet ™  communication

For applications that require moderate data integration, SEC-Z500X supports DeviceNet ™ Open fieldbus standard. There are significant advantages to using this interface:

Cost optimization: No need to additionally configure expensive AD/DA (analog/digital conversion) modules and dedicated I/O (input/output) boards on the PLC rack.

Simplified installation: With just one network cable for daisy chain connection and simple address settings, multiple MFCs can be interconnected with the main control system.

Compatibility guarantee: Compliant with ODVA (Open DeviceNet) ™ The specifications of the Supplier Association have passed consistency testing, ensuring interoperability in a multi vendor environment.

3. EtherCAT ®  communication

EtherCAT is the preferred solution for advanced processes that prioritize high speed and real-time performance. The SEC-Z500X also follows this trend and is equipped with an EtherCAT interface.

Fast data refresh: EtherCAT's "real-time processing" mechanism enables the master station to scan a large number of slave devices at extremely fast intervals, which is crucial for special applications that require fast closed-loop control.

Standard hardware: The main station can be connected using standard Ethernet interfaces, eliminating the need for expensive dedicated hardware and reducing the overall system cost.

Industry certification: Strictly following ETG (EtherCAT) ® The specifications of the technical group, including functional requirements and consistency testing, only certified devices are allowed to use the EtherCAT logo.

By providing complete communication options from traditional simulation to real-time industrial Ethernet, the SEC-Z500X series can seamlessly integrate into any existing or newly built factory control architecture.

Predictive maintenance: eDiagnostic monitoring system

In the semiconductor manufacturing industry that pursues "zero downtime", the passive "failure shutdown repair" mode is no longer acceptable. Engineers hope to receive early warnings at the beginning of equipment performance degradation and arrange maintenance before faults occur. This is precisely where the value of SEC-Z500X's eDiagnostic system lies.

Traditional troubleshooting often relies solely on whether the flow set value matches the feedback value, but this cannot fully reflect the health status of the valve, such as valve seat wear or particulate matter contamination. These faults may not cause significant set/feedback deviations in the early stages, but can affect long-term stability.

The principle of eDiagnostic system is as follows:

It continuously monitors two key parameters inside MFC through digital communication:

Flow control valve position: Real time monitoring of valve opening.

Flow control conditions: Compare the current control output with the theoretical model.

The typical warning scenario is as follows:

Scenario A (filter blockage): The upstream filter is slightly clogged, and in order to maintain a flow rate of 1SLM, the valve has to be opened 5% more than usual. The eDiagnostic system detects that the valve opening deviates from the reference value for a long time and issues a warning to check the gas filter.

Scenario B (valve seat leakage): Despite the valve closing command, there is still a small amount of flow passing through. The system will detect "zero drift" and issue an alarm for "decreased valve sealing".

The architecture of this system is fully digital. Each MFC is connected to the workshop level data recording unit via RS-485 or DeviceNet bus. A central server (Surveillance Server) connects these data recording units through LAN (Local Area Network) to collect real-time diagnostic data of all MFCs. Engineers can view the status of all MFCs in the entire plant from the central control room. The log function can replay the valve opening and flow change curves of each MFC before the fault occurred, which is highly valuable for post analysis of the root cause.

In addition, HORIBA provides a dedicated monitoring software that is compatible with F-Net protocol and DeviceNet. This software not only displays all communication parameters, but also automatically outputs alarms when anomalies are detected, truly achieving the transition from "regular maintenance" to "status maintenance".

Technical specifications and selection guide

It is crucial to have a deep understanding of specification parameters to assist engineers in accurately selecting models.

1. Precision definition

The accuracy of this MFC is divided into two situations. When the full-scale is greater than 35%, the set value is ± 1.0%, which is a relative accuracy indicator, meaning that the error varies with the set value. When it is less than 35% of full scale, it is ± 0.35% of full scale, which is an absolute accuracy indicator that ensures that even at extremely low flow rates, the absolute error is controlled within 3.5 thousandths of full scale.

2. Work pressure difference

There are strict regulations on pressure difference for different models. For SEC-Z567MGX with high flow rates (such as 500 SLM), it is recommended to have a working pressure difference of 250-350 kPa. A stable pressure difference is a prerequisite for ensuring the linearity and repeatability of MFC. Engineers need to ensure that the difference between the inlet pressure and the outlet pressure in the gas path design is stable within this range.

3. Flow range

Note that the units SCCM and SLM represent milliliters per minute and liters per minute under standard conditions (0 ° C, 101.3 kPa). For highly corrosive gases such as HBr, detailed MR/MG numbers are provided in the table.

4. Leakage rate

The requirement for external leakage rate is extremely high. According to SEMI (Semiconductor Industry Institute) standards, the helium leakage rate is ≤ 5x10 ⁻¹² Pa · m ³/s. For highly toxic or corrosive gases such as WF6 and HBr, this indicator directly affects factory safety and environmental compliance.

5. Wet materials

All components that come into contact with gas are made of 316L stainless steel and have undergone surface polishing treatment to minimize the adsorption and particle generation of reactive gases such as HBr.

Selection decision matrix:

Recommended Model Series Key Features for Process Requirements

Small flow rate (≤ 50 SCCM), corrosive gas SEC-Z51/52 1/4 inch VCR interface, high precision ± 1.0% F.S

Medium flow rate (10-100 SLM), universal gas SEC-Z53/54 multi gas/multi range, DeviceNet/EtherCAT optional

High flow rate (300-500 SLM), such as N2 blowing SEC-Z55/56/57 1/2-inch VCR interface, fast response, large pressure difference range

DeviceNet fieldbus integration SEC-Z... 4... dedicated DeviceNet communication interface and EDS file support

EtherCAT high-speed real-time control SEC-Z... X... meets ETG standards, high bus efficiency

Installation, Configuration, and Maintenance Practice

1. Mechanical installation

Installation direction: This series is not sensitive to installation direction, but for optimal zero stability, it is recommended to install it in the direction of the factory calibration (usually horizontal installation with the solenoid valve on top).

Interface: Provide 1/4 inch or 1/2 inch VCR (vacuum coupling) compatible connectors according to the model, as well as 1.125 inch or 1.5-inch IGS (integrated gas system) interface options.

Size difference: Please note that the Z53 series (H=126 or 139mm) and Z56 series (H=150 or 158.5mm) have different heights. When designing panel layouts, please refer to the bottom view and size chart.

2. Electrical configuration

Power on sequence: Connect+15V first, then -15V and the common terminal. The power-off sequence is reversed.

Signal type: Distinguish between valve open/close input (Pin1), flow output (Pin2), and set input (Pin6). The SEF (Mass Flow Meter) model has no valve, and its valve open/close input pin defaults to a normally closed state.

DeviceNet wiring: Ensure correct connection of V+, V -, CAN_S, CAN_L, and correctly install terminal resistors at both ends of the network.

EtherCAT wiring: Use an M8 male connector that complies with the ETG5003.2020 standard for power supply (Pin1: V+, Pin3: Power Common).

3. On site configuration (multi gas/multi range operation)

Step 1: Ensure that the MFC is in a closed or no airflow state.

Step 2: Connect the PC with Z500 configuration software to the MFC network via RS-485 or DeviceNet.

Step 3: Select the new gas type and target full-scale in the software.

Step 4: The software will automatically recommend the corresponding MR/MG number. After confirmation, download the parameters to the EEPROM (electrically erasable programmable read-only memory) of MFC.

Step 5: Execute the zero calibration command.

Step 6: Perform final validation using calibration gas (usually N2) to ensure accuracy meets the requirements.

4. Maintenance process based on eDiagnostic

Step 1: Establish a baseline. After the installation and stable operation of the new MFC, record its valve opening under several typical process steps as a health benchmark.

Step 2: Set the threshold. Set alarm thresholds for "valve opening deviation" and "response time delay" in eDiagnostic software.

Step 3: Daily monitoring. Engineers check the status of all MFCs on the software panel daily.

Step 4: Troubleshooting. When an alarm is triggered (such as a valve opening deviation of 10%), perform targeted checks: if the valve needs to be opened larger to maintain flow, mainly check the inlet filter or pressure regulator; If the valve cannot be closed, the main check is the sealing of the valve seat.

Step 5: Maintain validation. After cleaning or replacing the components, re record the valve opening and verify if it has returned to near the reference line.

5. Quick troubleshooting of common problems

Possible causes and solutions for the phenomenon

Set the value to 0, but if the output is greater than 0 due to valve leakage or zero drift, perform automatic zero calibration; Check if the valve seat is contaminated

Slow response or unstable overshoot pressure difference or PID parameter mismatch check upstream and downstream pressure; Re import the correct MR/MG number using configuration software to reset the PID

Check DIP switch address settings for communication failure (DeviceNet), address conflicts, loss of terminal resistance, or wiring errors; Confirm that there is a 120 ohm resistor at both ends of the network; Measure the voltage of CAN_S and CAN_L

Flow output fluctuation, atmospheric phase inlet pressure fluctuation, or upstream sensor pollution, add a stabilizing valve; Perform diagnostic checks on sensor raw signals