In the semiconductor manufacturing process, the Front Opening Unified Pod (FOUP) is a critical container used for protecting, transporting, and storing wafers. Its interior can accommodate 25 pieces of 300mm wafers, and its main components include a front-opening container and a dedicated door frame for opening and closing. The FOUP is a core carrier in the automated transportation system within 12inch wafer fabs. It is typically transported in a closed state and only opens when pushed to the equipment load port, allowing wafers to be transferred into the equipment’s loading/unloading port.
The design of the FOUP is adapted to micro-environment requirements. It features slots at the rear for wafer insertion, and the lid is specifically designed to match the clamp of the opener. Wafer-handling robots operate in a Class 1 clean air environment, ensuring that the wafers are not contaminated during transmission. Furthermore, the FOUP is moved between process tools via an automated material handling system (AMHS). Modern wafer fabs mostly use overhead rail systems for transportation, while a few older fabs may use ground-based automated guided vehicles (AGVs).
The FOUP not only enables automated wafer transfer but also serves a storage function. Due to the numerous manufacturing steps, wafers may take months to complete the entire process flow. Combined with high monthly production volumes, this means that tens of thousands of wafers within a fab are constantly in transit or temporary storage at any given time. During storage, FOUPs are periodically purged with nitrogen to prevent contaminants from contacting the wafers, ensuring a clean and reliable production process.
1. Functions and Importance of FOUP
The core function of the FOUP is to protect wafers from external shock and contamination, particularly avoiding impacts on yield during transfer. It effectively prevents moisture through methods like gas purging and Local Atmosphere Control (LAC), ensuring wafers remain in a safe state while awaiting the next manufacturing step. Its sealed and controlled system allows only necessary compounds and elements to enter, significantly reducing the adverse effects of VOCs, oxygen, and moisture on the wafers.
Since a FOUP fully loaded with 25 wafers can weigh up to 9 kilograms, its transportation must rely on an Automated Material Handling System (AMHS). To facilitate this, the FOUP is designed with various combinations of coupling plates, pins, and holes, and is equipped with RFID electronic tags for easy identification and classification. This automated handling requires almost no manual operation, greatly reducing error rates and enhancing the safety and accuracy of the manufacturing process.
2. Structure and Classification of FOUP
The typical dimensions of a FOUP are approximately 420 mm in width, 335 mm in depth, and 335 mm in height. Its main structural components include: a top OHT (mushroom head) for overhead hoist transport; a front Door for equipment wafer access; side Handles, often color-coded to distinguish process areas with different contamination levels; a Card area for placing message cards; and a bottom RFID tag that serves as the unique identifier for the FOUP, allowing tools and overhead hoists to recognize it. The base is also equipped with four identification and positioning holes for matching with tools and distinguishing process areas.
Based on usage, FOUPs are classified into three types: PRD (for production), ENG (for engineering wafers), and MON (for monitor wafers). PRD FOUPs can be used for product manufacturing, ENG types are suitable for R&D or experiments, and MON types are dedicated to process monitoring for steps like CMP and DIFF. It is important to note that PRD FOUPs can be used for both ENG and MON purposes, and ENG types can be used for MON, but the reverse operation poses quality risks.
Classified by contamination level, FOUPs can be divided into FE FOUP (front-end process, metal-free), BE FOUP (back-end process, contains metal), and those specialized for specific metal processes like NI FOUP, CU FOUP, and CO FOUP. FOUPs for different processes are typically distinguished by the color of the side handles or door panels. FOUPs from front-end processes can be used in back-end processes, but back-end FOUPs must never be used in front-end processes, as this would cause contamination risks.
As a key carrier in semiconductor manufacturing, the FOUP, through high automation and strict contamination control, ensures the safety and cleanliness of wafers during the production process, making it an indispensable infrastructure in modern wafer fabs.
Conclusion
XKH is committed to providing customers with highly customized Front-Opening Unified Pod (FOUP) solutions, strictly adhering to your specific process requirements and equipment interface specifications. Leveraging advanced material technology and precision manufacturing processes, we ensure that every FOUP product delivers exceptional airtightness, cleanliness, and mechanical stability. Our technical team possesses profound industry expertise, offering comprehensive lifecycle support—from selection consultation and structural optimization to cleaning and maintenance—ensuring seamless integration and efficient collaboration between the FOUP and your Automated Material Handling System (AMHS) as well as processing equipment. We consistently prioritize the safety of wafers and the enhancement of production yield as our core objectives. Through innovative products and all-encompassing technical services, we provide a robust guarantee for your semiconductor manufacturing processes, ultimately boosting production efficiency and product yield.
Post time: Sep-08-2025