General Semiconductor Model#

Overview#

This Modelling Guide proposes a baseline modelling approach tailored to Semiconductor business scenarios. It outlines an approach for generic use-cases, while certain Semiconductor-specific cases may require additional modeling and configurations solutions.

Business Context#

Semiconductor manufacturing is a highly controlled and data-driven environment in which materials move through a sequence of precise processing and validation steps. The business model must therefore support a strong relationship between the physical execution of the process and its representation in the MES.
Both Front-End and Back-End Semiconductor processes are covered by MES functionalities, although their basic modeling and configuration differ.
The next section presents the basic structure and entities required for a generic MES model, highlighting the differences between Front-End and Back-End processes.

MES Modeling#

1. Materials, Forms, Quantities & Units#

In Front-End processes, Parent Material is represented as a Material with Form Lot and it groups a set of Wafers, which are its Sub-Materials, and have Form Wafer or Substrate.
Each Submaterial typically has as its Primary Quantity the number of Wafers - usually 1 per Submaterial - and as its Secondary Quantity the number of Dies/Chips expected to be produced from that Wafer. Tracking die quantity per wafer is optional, often only introduced in the later stages of the Front-End Flows.
Lot Materials typically have as Primary Quantity the sum of the Primary Quantities of their Submaterials, and as Secondary Quantity the sum of the Secondary Quantities of their Submaterials:

Example of a Wafer sub-material quantities in the MES:

When crossing from Front-End into Back-End processes, between Wafer Probing and Die Attach processes, the Primary Quantity should switch to track the Dies rather than the Wafers.
At this stage, Lot remains as the Material Form, with the Primary Quantity representing the number of Dies, and the Secondary Quantity (optional) representing the number of Wafers. Dies are not modeled as Submaterials in Back-End processes; instead they can be tracked through Wafer Maps.
In the Die Attach process, the wafer dies will be transferred into another Lot that can have a different Substrate (Strips, Panels, Lead Frames, Boards, etc), which will be the lot that will carry on in the process. Depending on the traceability requirements, these packaging substrates can also be tracked as sub-materials in the system, including their own Maps to track the Dies therein.

Example of a Back-End Lot Material quantities in the MES, without substrate tracking:

3. Container#

Physically, Materials are placed in Carriers for transport and processing:

• FOUPs, FOSBs, Cassettes, in Front-End processes.
• Magazines and Trays for Back-End processes.

In MES, these are represented by the Container entity.

Typically, in Front-End processes, each Submaterial occupies a specific Container position, matching the positions in the physical Carrier, while in Back-End processes, the position of each Material in the Container is not always tracked.

MES Position tracking is specially critical in 300mm Front-End processes for:

• Slot Map Verification: Slot Map in the MES should match the reality, as slot verification can be more reliable and cost-effective than verifying wafer physical IDs in each step.
• Automation Processes: to ensure that in full automated processes, jobs are executed in the correct sequence;
• Data Collection: in processes where data is collected at Submaterial level, to ensure that the data is linked to the correct Material Name.

In automated processes, when a Container is physically received at an equipment Load Port, its name is read, allowing the MES to automatically Dispatch the Materials therein to start processing.

Operations such as Dispatch, Track In, Track Out, Move Next, or Abort are performed at the Material level rather than at the Container level.

4. Resource#

In general, tools and equipment are represented in the MES by the Resource entity, which can also represent Load Ports, individual Chambers, or Wafer and Carrier Stockers.

For a standard process, the following modelling structure is required:

• Main Equipment/Tool/Cluster: a Resource representing the main equipment such as a Bay, Reactor or Metrology tool, with Processing Type = Process.
• Chambers or Process Modules: many front-end processes such as Deposition or Etch are executed inside controlled process chambers, also called Process Modules. In MES, each chamber should be modeled as a Resource with Processing Type = Process and linked to the main tool as a Sub-Resource.
• Load Ports: Resource with Processing Type = Load Port. Load Port Type should also be defined as Input, Output or both, and the Display Order must be set from 1 to N, according to the number of Load Ports on the Equipment.

Other components like Transport Modules, Consumable Feeders or other relevant parts, can also be modeled as sub-resources with Processing Type = Component, in order to track component states and manage part-specific maintenance plans.

5. Flows and Steps#

In Front-Ends, it is a common scenario to execute the same operation multiple times. For example, the Deposition - Lithography - Etch operation sequence, is often repeated several times throughout the process.
The MES supports reusing the same Step multiple times within the Flow, with a different naming, by assigning a Step Logical Name. This means that, depending on its position in the Flow, the Step can have a different, more meaningful, and business-friendly name, while the underlying Step remains the same.
Same approach can also be applied to Flows, where the same Flow, can have different Logical Flow Path names depending on the context in which it is used. It is possible to configure different contexts for a given Step, depending on its Logical Flow Path, by defining in the relevant context tables (e.g. different Checklists can be performed depending on the Logical Flow Path defined).

6. Recipe#

In semiconductor manufacturing, a Recipe is the defined set of machine conditions and parameters used to process a wafer in a specific Step. It defines the equipment parameters, such as temperature, time, gas flows, pressure, power, and other settings needed to run the process consistently. Recipes can be created and managed manually in the MES, although in semiconductor scenarios, Recipes are usually synchronized from the tools to the MES via automation. Recipe Management flag must be enabled on the Resources.

7. Experiments#

In any industry, it is common to have deviations from the standard manufacturing process. In MES, this can be managed through the Experiments module.

An Experiment Definition is a controlled deviation from the standard manufacturing process, created to evaluate and track the impact of a specific change.

Several actions can be defined, such as changing the Flow or Step, assigning a different BOM, Resource, or Checklist, skipping a Step, among others.

In the semiconductor context, especially in R&D fabs, recipe variation is especially common because teams intentionally compare results to find the best setting. In the MES, this can be achieved by creating Experiment Definitions and assigning the Set Recipe action, in specific Steps for specific Material Groups.

8. Maps#

As mentioned before, die-level tracking is done in the MES through the Mapping module. Substrate Mapping in MES uses SEMI E142 standard, which is used extensively in semiconductor manufacturing to represent wafer maps and other substrate data in a structured XML format. SEMI E85 standard maps are also supported. Wafer Maps are linked to Packaging Substrate (e.g. Strip) Maps via Transfer Maps

E-142 Maps are essential for:

• Wafer tracking — Visualizing die-level data across wafers
• Yield analysis — Mapping bin codes to identify patterns (pass/fail, bin quality)
• Equipment integration — Exchanging map data with Die Bonding, Test and inspection tools (often via SECS/GEM)
• Traceability — Tracking individual devices through assembly and test