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Semiconductor Glossary

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Advanced Production Scheduling


This term refers to the management of processes involved in the optimization of raw materials and resource capacity within a wafer fab or factory.


An optimization term that describes a piece of software that will make decisions and/or take actions in its environment in order to achieve a given goal.




A wafer batch, also known as a wafer lot, is a group of wafers that are processed together, at the same time. 



A bottleneck refers to a tool that is limiting the production capacity of a fab. This is usually caused by more wafers arriving at the tool than it can process, causing a build up of queuing WIP.




Capacity refers to the maximum level of output of wafers a manufacturer can achieve over a period of time.

Cycle Time

Cycle time is the total amount of time taken to complete the manufacturing, from start to finish, of a single unit i.e., one wafer.




Dispatch System


A system, often referred to as real-time dispatch (RTD), that is used by chip manufacturers to dispatch wafers onto tools using basic heuristic rules such as “first in, first out”.



In wafer fabrication, etching refers to any technology that will selectively remove material from a thin film on a substrate (with or without prior structures on its surface) and by this removal create a pattern of that material on the substrate.






Semiconductor processing facility which turns silicon wafers into integrated circuits.



Furnaces, also known as diffusion furnaces, are heated tubular spaces used in the manufacturing process of semiconductors. They are used to add doping impurities into high purity silicon wafers, thereby creating embedded semiconductor devices.


Global Scheduling (Fab-wide)

Global scheduling is a capability of Flexciton’s advanced scheduler whereby the optimizer is able to take into consideration the entirety of the fab – such as the state of toolsets further down the production line.




A heuristic is any approach to problem-solving that uses a practical method or various shortcuts in order to produce solutions that may not be optimal but are sufficient given a limited timeframe or deadline.

Hybrid Optimization

A unique model based on mixed-integer linear programming (MILP), using a unique combination of mathematical optimization, heuristic search and smart decomposition methods.





Implantation, or ion implantation, is a low-temperature process by which ions of one element are accelerated into a solid target, thereby changing the physical, chemical, or electrical properties of the target.



Machine Learning

The use and development of computer systems that are able to learn and adapt without following explicit instructions, by using algorithms and statistical models to analyse and draw inferences from patterns in data.

Manufacturing Execution System (MES)

Commonly referred to as MES, manufacturing execution systems serve as the intermediary between a business system and a manufacturer's plant floor control equipment.


Metrology is the science of measuring and characterising tiny structures and materials, and there are a number of tools and technologies within this category.


Mixed-integer linear programming (MILP) is the state-of-the-art mathematical framework for the optimization of processes and systems.




The action of making the best or most effective use of a situation or resource.

On Time Delivery (OTD)

On Time Delivery or OTD refers to a key performance indicator measuring the rate of finished product and deliveries made in time.





A photolithography system undertakes a process whereby highly complex circuit patterns from a reticle are reduced using ultra-high-performance lenses and exposed onto a wafer.


Reticles are typically carried around in the factory in containers known as pods. A pod is inserted into a machine, and the machine can use the reticles in the pod.

Preventative Maintenance

Preventative maintenance keeps equipment in good condition through regular machinery checkups and maintenance tasks. These services may be scheduled according to a calendar or based on equipment operating time.




Queue Time

The amount of time a batch of wafers spends waiting at a tool before it can be processed.





A reticle, also known as a photomask, is a plate of optical glass with an opaque pattern on it, used in photolithography. When laser light is shone through the reticle, a pattern of light and dark is projected onto the silicon wafer.


A rule-based system is a system that applies human-made rules to store, sort and manipulate data. In doing so, it mimics human intelligence.




Scheduling is the process of arranging, controlling and optimizing work and workloads in a production process or manufacturing process.


Reticles are stored in a central magazine called a Stocker. An engineer inserts a pod into the stocker, and the stocker robotically opens the pod, removes some reticles and replaces them with different ones.

Smart Manufacturing

The next-generation of manufacturing that employs computer-integrated systems, high levels of adaptability and rapid design changes, digital information technology, and more flexible technical workforce training.






Throughput is the amount of wafers that a company can produce and deliver to a client within a specified period of time. The term is often used in the context of a company's rate of production or the speed at which something is processed.


A timelink (also known as time constraints, time lag constraints, time loops or close coupling constraints) is a maximum amount of time that can elapse between two or more consecutive manufacturing process steps of a batch of wafers.


A group of tools which can run the same recipes.





A wafer is a thin disc of silicon (one of the most abundant semiconductors available worldwide) or another semiconductor material, used as the basis for creating electronic integrated circuits.

Wafer Priority

The importance placed on a batch of wafers that helps to determine which should be prioritised in order to benefit the objectives of the fab.

Wafer Step

Wafers travel along a defined route through the fab, and that route is made up of multiple steps. Generally speaking, each step is one process in one tool using one recipe.


WIP stands for Work In Progress and refers to wafers that have entered the production process but are not yet a finished product.






Yield is a quantitative measure of the quality of a semiconductor process. It is the fraction of dies on the yielding wafers that are not discarded during the manufacturing process.