Process vessel (bubbler) for precursor evaporation
Bubblers are used for the safe and precise handling of high-purity chemicals in microelectronics applications. They enable the controlled vaporization of liquid chemicals and their reliable transport into the process, contributing to stable and reproducible manufacturing conditions. Depending on the application, they can also be used for chemical storage or as intermediate vessels within a chemical delivery system.
To meet the stringent purity requirements of the semiconductor industry, bubblers are manufactured from high-quality materials and feature dead-space-optimized designs. This minimizes the risk of contamination while ensuring safe and reliable vapor delivery. With their high process reliability and durable construction, bubblers are an essential component of modern high-purity precursor evaporation systems.
SEMPA-Bubbler-Portfolio
SEMPA offers a comprehensive portfolio of bubblers for the safe and reliable handling and delivery of high-purity chemicals in microelectronics applications. Standard sizes from 150 ml to 3,950 ml are available for a wide range of process chemicals and can be combined with heating jackets and trace-heating solutions. Depending on the application, SEMPA can also support the integration and installation of these heating solutions in chemical delivery systems, for example as an alternative to water baths and with customized stand or height-adjustment concepts. ATEX-compliant heating jacket solutions may also be available for selected applications. Heating concepts can be configured not only for the vessel body, but also to provide heat to the vapor and dip-tube/valve areas where required. In addition to standard sizes, SEMPA manufactures custom bubblers with capacities above 3,950 ml in coordination with the customer and according to the specific process requirements and system configuration. With extensive expertise in high-purity technology, SEMPA provides solutions designed to meet demanding purity and process-reliability requirements. |  |
Operating Principle
A bubbler consists of a stainless-steel vessel body with a base and lid and is designed to contain a liquid or solid precursor. For high-purity chemical applications, the internal wetted surfaces are electropolished to achieve very low surface roughness. This smooth surface minimizes the adhesion and retention of precursor residues, particles, condensates, and reaction products, thereby improving cleanability and reducing contamination, particle release, and memory effects. It also supports more uniform wetting and drainage behavior, which contributes to reproducible and reliable precursor delivery.
A high-purity carrier gas, such as nitrogen or argon, is introduced through a dip tube extending toward the bottom of the vessel and brought into contact with the precursor medium. As the gas passes through the precursor, it becomes enriched with precursor vapor and transports it at a defined concentration to the downstream process, such as a CVD or MOVPE system. The delivered precursor concentration is primarily determined by the precursor temperature, system pressure, and carrier-gas flow rate.
Highest Purity for Demanding Processes
Even the smallest impurities can significantly affect yield in semiconductor manufacturing. For this reason, bubblers are specifically designed for ultra-high-purity (UHP) applications. Electropolished internal surfaces, high-quality materials such as 316L stainless steel, precision orbital welds, and a low dead-volume design minimize particle generation and residue accumulation. At the same time, helium leak-tested integrity and optimized flow paths ensure maximum process reliability and enable nearly complete utilization of the precursor.
Tailored Solutions
Bubblers can be configured to customer requirements with valves from different manufacturers, a choice of level sensors with three-point or five-point evaluation, and an optional heating jacket. These options allow the bubbler configuration to be adapted to the requirements of semiconductor, LED, and photonics manufacturing processes while supporting reliable handling of ultra-high-purity process media.
Technical Specifications
| Capacity | 150 ml to < 4000 ml The vessel geometry is optimized for maximum precursor utilization and efficient vapor generation. |
| Materials | TCC tubing with electropolished internal surface (Ra = 0.6 µm) The electropolished internal surface provides an ultra-clean wetted surface with low roughness, supporting good chemical compatibility, cleanability, and reliable process performance. |
| Valves | Standard valves for operating temperatures up to 60°C Compatible with premium diaphragm valves from leading manufacturers. Configurable with manual or pneumatic actuation, as well as optional crossover and purge functions for safe operation and easy maintenance. |
| Connections | ¼” VCR |
Compatible Precursors | Suitable for a wide range of high-purity liquid precursors used in semiconductor manufacturing, including organometallic compounds and specialty chemicals for ALD, CVD, MOCVD, EPI, and other deposition processes. Typical process media include TMA, TEOS, TDMAT, TEMAH, HCDS, as well as numerous other customer-specific precursors. |
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