AMHS (Automated Material Handling System) for 300mm Semiconductor Fab

The writing will be written over three times with respect to the AMHS in the Semiconductor and FPD Fab.
First, “Automated Material Handling System for 300mm Semiconductor Fab”
The second is about ” Automated Material Handling System in FPD Fab”
The third is the configuration and review of the layout for configuring the system prior to configuring the AMHS in the previous 300mm Semiconductor Fab and the FPD Fab in recent years as a ‘plan, design and simulation analysis of the AMHS and Fab layout’ and it will be written in terms of forecasting and analytical through simulation.

Introduction
  The implications of the launch of the 300mm-caliber Semiconductor industry means a quantum leap in production efficiency compared to the conventional 200 mm (8-inch) wafer production process.
The productivity of the Semiconductor can increase the productivity of the 12-inch wafer is 2.25 times as compared to the 8-inch wafer in the difference between the wafer caliber.
This high productivity should be supported by changes in the caliber of the wafer and each process technology, and all the production process can be only under automated manufacturing systems.

This fully automated manufacturing system, while increasing productivity at the same time ensuring the flexibility of each of the smooth transfer of the logistics between the process and each unit of equipment based on the interface technology between all the manufacturing system is a single system Fab itself that can be seen that the configuration of a single manufacturing equipment.

In such a fully automated manufacturing system, the Stocker system that is responsible for the Buffer function between each process equipment in order to smoothly or flexibly transfer the logistics between each process, in addition to the OHS (Over Head Shuttle), OHT (Overhead Hoist Transport) system that is responsible for the transfer of inter-process logistics, or OHT, AGV (Automated Guided Vehicle) that is responsible for logistics in Intrabay, the Rail Guided Vehicle (RGV) system by efficiently controlling and managing the activity of complex systems, it consists of a software system to quickly change the flow between processes to prevent the deadlock or traffic congestion of the inter-process logistics. A description of the key parts of the logistics transfer and the general configuration, purpose and function of these systems.

[Figure 1] Productivity due to Wafer Viewing

Characteristics of 300mm Semiconductor Fab
  The Semiconductor process is a complex process, as it is the process of making several layers of ultra-fine circuit lines on the wafer. Therefore, using the equipment arrangement of the conventional manufacturing line cannot be transported to the inter-process logistics. Using the same equipment between many processes is to be monitored in real time whether the process proceeds to any process for each wafer is in progress, it must be transported in accordance with each process order to complete more than 25 iterations process. [Figure 2] as can be seen in the semiconductor process is a significant problem that can be transported within a predetermined time between each of the process equipment and the process equipment for the distribution of the process and the number of processes repeated. Must always be in a constant position before going through a particular process equipment and [Figure 3], when each of the process is completed, the wafer should be transported using a specific system in order to proceed to the next step. In the fab, the wafer must stand in the process of being re-made (WIP: Work in Process) is also a significant challenge to minimize this (re-production) because it can be expressed as a process in stock. Depending on how you plan the automatic transport system, it can make a huge impact on process efficiency, the hardware portion of the automatic conveying system and the operating algorithm of the software is also a lot of research. Efficiency of these systems, flexibility, and to establish the standardization of SEMI Standard (Semiconductor Equipment and Materials International Standard) in the International Semiconductor equipment Standardization Organization SEMI for seamless communication and interface between many types of systems and stipulate the details that may appear between each system. This provision of SEMI can be said to be standardized for all matters to co-exist different concepts of functional differentiation (role allocation) and integrity between process equipment and transport equipment.

[Figure 2] Iterative Process of Semiconductor Fab
[Figure 3] Simplifying the System
 

The configuration of the 300mm Semiconductor Fab is largely composed of Interbay and Intrabay.
Interbay is mainly the track system (OHT, OHS) to the place where the reliability and efficiency of the system for the digestion of mass distribution in the Fab as a central passage for the distribution of the logistics between each process located in the center of the manufacturing system it is responsible.

The use of the Bay concept layout of Interbay and Intrabay in Semiconductor Fab is so complex that the Semiconductor process is too complicated and many iterative processes are achieved, if each of the process or equipment to be transported to the logistics of the complex transport system, such as a web, one to be responsible for most of the logistics transfer in the center by integrating the logistics transport system with respect to these requirements, the cost side and the efficiency of the semiconductor process because it is suitable for specificity.

[Figure 4] Bay Layout of 300mm Semiconductor Fab

Software for Fab Operations
The role of the software system in the Semiconductor Fab is a very important part.
The efficient operation of the system can be directly related to high productivity, and is configured as follows.

MES (Manufacturing Execution System)
As a production integrated management system is a connection and integrated management system with other systems for sales/order management and production support from the MRP system to estimate the requirements of existing materials and to respond to complex corporate environments.

MCS (Material Control System)
MCS system is the allocation of an appropriate automatic conveying system in accordance with the material flow (material flow Control) to operate the integrated automatic conveying system that is responsible for the transport of the Logistics (Lot unit) based on the information of the H/W and S/w for each process equipment, optimized route search function and includes the ability to determine the appropriate transport system.

AMHS Controller (Automated Material Handling System Controller)
 As unit equipment of the Automated Material Handling System, such as Stocker, AGV, OHS, OHT, each system is a portion and a subsystem for the top SW of the GUI for the dispatching function and monitoring, depending on the needs of the system, that is, it consists of a control portion for controlling Motion.

In addition to the above operating software, but the scheduler is responsible for scheduling between production processes, in terms of the Automated Material Handling System MCS and AMHS Controller is a part that operates the Automated Material Handling System.
The upper or lower communication and operating terms of each software are also defined as SEMI standards. The provisions of the Stocker system of MCS and AMHS systems are subdivided, including the general function of the E88 (StockerSEM), the original purpose of the Stocker system, the storage function and the incoming and outgoing scenarios, the interface portion of the mouth factory other systems.
If StockerSEM is a thing about the Stocker system that has a storage function OHT or OHS or AGV system, etc., because it is the purpose of performing only the function of transporting the logistics OF THE TSC (Transport System Controller) to the other standard E82 (IBSEM) it stipulates the particulars. In the case of OHS or OHT, which is responsible for logistics at the central Interbay, the Stocker system and OHS or OHT systems are either the main (Active) or unit ( Passive) is defined in accordance with the provisions of the operating system.

[Figure 5] Software Architecture

Interbay System
The system that carries the FOUP (Front-Opening Unified Pod) system that contains a 300mm wafer in the center of the entire logistics transfer system in the central of the automatic conveying system in the FAB is required high efficiency and high reliability is a transfer body (Vehicle) and is called the OHS, and, conversely, the under carrying system is called OHT. In the case of conventional 200mm Semiconductor Fab, Interbay is the central conveying system mainly used for OHS systems, in the case of the return in each Intrabay, but mainly used OHT system, in the case of the 300mm Fab process is made of a concept to minimize the material (WIP: Work in process), the OHT system in the Interbay and Intrabay is considered to be used to integrate.

The distribution of the Interbay system is divided into two layers of track system and Stocker system to be transferred to the feed amount and the Intrabay that are required in the entire Fab, Stocker system is a function of Buffer for storing WIP in the Fab and for the purpose of delivery to Intrabay track system for the transfer to the Intrabay.

OHT System for Interbay
Track system can be used in dual-rail double-level form in the case of 300mm, the delivery of FOUP with the upper OHT level and the lower OHT level uses a Stocker system that exists in the Bay. [Figure 6]
The top OHT system has a fast feed rate (more than 5m/sec) compared to subsystems. Transport unit vehicle is the role of the operating software (OHT Controller), so that the state of the vehicle, such as the interference of the vehicle to the destination for feeding, Rail occupancy status of the vehicle and the allocation of the empty vehicle is to be identified in real time it can have a significant impact on the logistics transfer capacity in the Fab.

[Figure 6] Double-level OHT System within Interbay
[Figure 7] OHS, Stocker System
 

Intrabay System
The interface between the process equipment in addition to the other automatic transfer system for the distribution of the feed in the Bay where each process is formed is required.
In addition, the FOUP (Front Opening Unified Pod) is used so that the wafer is not exposed during transfer for other processes in the process equipment because it is very susceptible to the fine dust particles (Particle), therefore is protected by the opener of the wafer to the outside of the machine, and the FOUP can automatically open/close to protect the wafer from fine dust and other logistics transfer system (OHT , AGV, etc.) and plays an interface role.

The Automated Material Handling System in the Intrabay consists of a system such as AGV, RGV, OHT, AGV, RGV system falls its efficiency, Intrabay in the same position as the Operator in the 300mm Fab due to the problem of congestion and stability mainly the Track system OHT is mainly used.

[Figure 8] Intrabay OHT System

When using the OHT system in Intrabay can be used to configure the system layout in each Bay-specific integration or separation form. OHT system can be configured in the same form as [Figure 9] when using a link by Bay, in which case there is an advantage that can reduce the Stocker system. Since the tendency to minimize the Stocker system in the 300mm Fab, it constitutes a single integrated OHT track by link to each bay. If you configure a single rail by linking all the bay, the feed rails must contain the functions of branching and joining (Merge/diverge).
[Figure 10] is a form that separates Interbay and Intrabay, mainly used in the conventional 200mm Fab form. When using the separation of Interbay and Intrabay, but the use of the TFE (Transfer Equipment) when the return between the Rail and Rail is considered, in fact, TFE is rarely applied. In most cases, using the Stocker between Interbay and Intrabay is used by connecting Interbay and Intrabay.

[Figure 9] Intrabay Track system linked to Multi-Bay
[Figure 10] Track System where Interbay and Intrabay are Separated
 

The reasons why OHT is mainly used in Intrabay is:
– Excellent bounce ability.
– OHT can be installed and operated by utilizing the remaining space of the upper Bay.
– The operation of Clean Room requires a lot of cost, but OHT does not require additional space for the system, so it has the effect of cost savings.
– The operation of the vehicle of OHT with the operator in the Bay is not done at the same time, thus the safety of the operator is high.
– Because the system is in the upper part, the bottom part can be utilized as a different space for the Bay operation.
– As production changes, vehicle is very easy to add.

The Track system within Intrabay is a short distance between each machine, therefore is operated in a low speed state compared to the Track system within the Interbay.


FOUP Opener System:

FOUP Opener system is used as the Load Port of each process equipment, it is equipped with a BCR (Bar Code Reader) for each port, and the ability to detect the alignment of the wafer and the function of passing the process information in progress of the wafer to the process equipment it has.
When installing multiple FOUP Openers, it can be used as an EFEM system.

AGV / RGV System:
The introduction of the AGV system was tested by some users, whether the applicability of the initial 300mm. However, the tendency to be excluded from the adequacy when considering the spatial limitations of the Intrabay and safety, transport efficiency and the Operator. [Figure 11]

Also, when using the AGV system, if you want to transfer logistics from Intrabay to Interbay, the Stocker system must be in the corner of Intrabay and Interbay. As mentioned earlier, the recent trend is to Install the stocker system between Intrabay and Interbay, so the concept of minimizing WIP in the Fab is configured automatically, as in the form as in the conventional 200mm Fab always a certain amount of the process between the re-holes (WIP: Work In process).

[Figure 11] AGV and RGV System within Intrabay

Comparing the Pros and Cons when integrating OHT Loop between Interbay and Intrabay

Pros: Drastic reduction of Stocker Quantity (Within 50%)
Cost Saving for AMHS
Reduction in the number of logistics transfers in Interbay
Reduction of OHT Controller Quantity
Reduced utilization of Stocker Robot and reduced required Storage space

Cons: Increased risk of logistics transport in the Fab based on OHT’s performance
Increased Required Quantity of OHT Vehicle in a specific Intrabay
Can increase feed time and distance between Bay and Bay transport.

Conclusion
The most important part of the automatic conveying system of the 300mm Semiconductor Fab is that the logistics transfer of Interbay and Intrabay, it was emphasized that the efficiency of the system has a significant effect on the efficiency of the entire Fab.
In the AMHS system it summarized the system-specific features according to the layout of the OHT system in the Interbay and Intrabay has the greatest impact on the substantially operating efficiency within the 300mm Fab.

Interbay Automated Material Handling System
Bay Stocker: Storage in Interbay and Intrabay AMHS link Ability
Interbay Track(OHT,OHS): Transport Logistics by linking Interbay Stockers

Intrabay Automated Material Handling System
Linked OHT System
Linked OHT System Transport Logistics between Tools in the Bay
Intersection point between Bay or Bay Stockers connect using Turntable

MCS Integrator
Function as a Bridge between Interbay AMHS and Intrabay AMHS

Integrated OHT layout of Interbay and Intrabay
1. Distributing Buffering using OHT
– The Tool and Tool can be directly transported to the Fab, facilitating the transfer from the Tool to the next Buffer.
– For an important Tool It should compensate for a relatively long transfer time using the Buffer of the Tool itself.
2. The Importance of OHT Management Technology
– Vehicle Management : Set up and manage vehicle Routing and allocation of empty Vehicle
– Scheduler Ability : Vehicle allocation and resource management of OHT Systems (For Efficient Operation)
3. The Bridge function of Interbay and Intrabay is not necessary.
– Minimalizing the Stocker Robot Moves : Stocker Quantity decreases compared to total WIP amount

OHT layout separated by Interbay and Intrabay
Interbay AMHS
Bay Stocker: Storage in Interbay and Intrabay AMHS link Ability
Interbay Track(PHT, OHS) : Transport Logistics by linking Interbay Stockers

Intrabay AMHS
Intrabay only in charge of Tool and Tool Logistics transfer: OHT, AGV, RGV, PGV, etc.

In accordance with the integrated or detachable layout of the Interbay and Intrabay mentioned above, if the integrated operation of the logistics volume and the Intrabay Tool in the Interbay to integrate the logistics of Intrabay inter-logistics transfer time can be longer state, in this case, the core process equipment requires its own Buffer function, the selection of the MHS (Material Handling System) in accordance with the amount of logistics required in the Intrabay if operated by separating the Interbay and Intrabay can be varied All of them.

JT Shin / CEO

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