In semiconductor manufacturing, large quantities of hazardous gases and chemicals are used. For example, arsine (AsH₃), which is widely applied in N-type doping and Chemical Vapor Deposition (CVD) processes, is a colorless, flammable, and highly toxic gas. Exposure to concentrations as low as 6.25~15.5 ppm can be fatal within 30 minutes to one hour. Therefore, before replacing gas cylinders, the gas lines must be thoroughly purged to ensure personnel safety.

As semiconductor technology evolves from mature processes to advanced nodes, manufacturing processes impose increasingly stringent requirements on high purity piping systems. Among these, leak rate is a critical control parameter. To minimize leakage risks, it is essential not only to select appropriate sealing methods and properly install valves, fittings, and other piping components, but also to reduce the number of pipeline connections wherever possible.

A Purge Block is designed to connect gas cylinders to specialty gas delivery lines. Featuring a multi-valve integrated design, it incorporates the valves and associated piping for delivery, purging, and exhaust into a single valve body. This significantly reduces the number of connection points and effectively lowers potential leakage risks, making it especially suitable for toxic and hazardous gas delivery systems. During cylinder replacement, the Purge Block enables thorough removal of residual media within the pipeline, as well as air and moisture that may have entered the system during the replacement process. The FITOK Purge Block is built around an integrated assembly of three diaphragm valves with extremely low leak rates. Additional advantages include compacter structure with a small footprint, reduced purge gas consumption, shorter downtime in the manufacturing process, and higher overall productivity—especially when considering the cost of one hour of downtime in a semiconductor fabrication facility (fab).

Figure 1 illustrates a comparison before and after employing a Purge Block. Since a larger number of piping components are required in the configuration prior to using the Purge Block, only some of the weld joints are marked in the diagram for clarity. It can be observed that the piping system requires fewer weld joints and components, occupies less space in gas cabinets, and reduces overall weight​ after the Purge Block is implemented. The FITOK Purge Block is available in two versions: low-pressure (300 psig) and high-pressure (4500 psig), suitable for low-pressure and high-pressure gas cylinder applications in specialty gas rooms, respectively.

Figure 1. Comparison Before and After Using the Purge Block

Basic Structure and Functions

 

The Purge Block adopts a compact modular design and typically includes four gas ports and one sensor port, as shown in Figure 2. Process gas flows into the block through the process gas inlet (from the cylinder valve side) and is supplied to the process pipeline through the process gas outlet. The purge gas inlet and waste gas port are used for introducing purge media (such as N₂) and discharging waste gas, respectively. The sensor port is designed for installing a pressure sensor or pressure gauge to enable real-time monitoring of the internal pressure within the block.

Figure 2. A Typical Port Configuration of Purge Block

• Process Gas Inlet:

  • Typically equipped with standard cylinder connections (such as CGA, DIN, and CGA DISS), and can also be customized according to customer requirements to meet various working conditions.

     

• Process Gas Outlet, Purge Gas Inlet, and Waste Gas Port:

  • Use weld connections or face seal fittings to ensure gas-tight integrity.

     

• Sensor Port:

  • IFR4 (1/4" integral female FR fitting) as standard, suitable for high-purity and ultra-high-purity applications.

     

• Pigtail:

  • Provides a flexible connection between the Purge Block and the gas panels, typically using 1/4" or 6 mm tubing. The design is superior to hoses, which require annual leak checks.

Working Principle and Operating Procedure

 

Through its multi-valve integrated design, the Purge Block enables pipeline purging before and after cylinder replacement, ensuring system cleanliness (see Figure 3).

Figure 3. Schematic Diagram of Purge Block

Technical Specifications of Purge Block

 

As a fluid system component manufacturer deeply engaged in the semiconductor industry, FITOK provides various configurations of Purge Blocks. The technical data are shown in Table 1 and can meet diverse working condition requirements.

Table 1 Technical Specifications of Purge Block

Through advanced design and manufacturing processes, along with strict quality control, FITOK ensures high reliability even under demanding working conditions. The FITOK Purge Block offers the following advantages:

• Multiple process gas inlet options: In addition to CGA, DIN, CGA DISS cylinder connections, other types can be provided according to customer requirements.
• Mature product portfolio: FITOK has the capability to manufacture various types of diaphragm valves, valve manifolds (two-valve three-way, three-valve four-way), and integrated valve assemblies, and can design and produce diaphragm valve products with complex flow paths.
• Fast delivery capability: With a flexible manufacturing system, a well-established supply chain, and warehousing system, FITOK helps customers reduce procurement and inventory costs while achieving rapid delivery.

FITOK products are widely used in the semiconductor industry. In addition to offering various series and models of diaphragm valves, FITOK can also provide valve manifolds tailored to customers’ specific working conditions, better meeting customers’ application requirements.