lithoAPC Critical Dimension
lithoAPC impresses with its modern design and user friendly user interface.
The user can navigate between all features easily since the well structured architecture.
• Comfortable user interface
All modules are integrated into the APC desktop application. The user interface combines all functionality to setup, monitor and control the APC control. In details this covers:
- visualize measurement and process data visualize
- create, delete and setup all master data
- control status of master data
- visualize and compare all analysis results and intermediate information including
- systematic failure
- value and residual statistics
- trigger manual analysis for single or selected runs
- edit run context information or measurement values
- access wafer visualizations
- visualize the process time line in diagrams
- access user management and system capabilities
- connect to any lithoAPC server in the network
- export and import functionality
- copy of all table information
The ongoing development of the system will produce frequent new modules and new features accessible in the user interface.
• Master data and parametrization
lithoAPC is completely configurable via master data. Any master data item can be an instruction or some piece of information, which is required for the analysis like wafer layout, target set, parameter model.
New master data implementations but also customer’s master databases are accepted and enable functional extensions of the system.
Master data can be parametrized. Such parameters are evaluated dynamically during the analysis. In this case the values are evaluated at the first request for the given run.
• Workflow based
The analysis of lithoAPC is document and work-flow based. The work-flow is defined by the engineers in the master data. It contains the general flow of dedicated analysis steps and their settings. The document approach ensures, that all details of the analysis is collected into a single document, which is stored in the system database. It can be reviewed by the engineer at any time.
• Fine alignment
The target locations provided by measurement tools usually do correspond to the design coordinates. If a target set of the design information is provided, lithoAPC calculates the wafer shift and corrects the target location to the real design coordinates. Furthermore, recipe issues are detected and the measurement is rejected.
• Flier elimination
The calculation of the startup values is based on previous runs and their optimal process conditions. The system expects a continuous distribution and tests the data quality. The flier elimination will detect and remove all runs, which do not follow the common behavior.
Flier elimination is based on a combination of absolute flier limits and the definition of relative tunnels.
• Data validation
All misalignment data are subject for a flier elimination. The elimination accepts absolute and relative borders. The flier elimination is applied to the residuals after the analysis is done. This ensures a maximum of sensitivity for the flier elimination even with respect for systematic failiure.
• Standard analysis
By default the analysis is done by a Gaussian solver. This is different from other CD analysis system which usually are based on statistics only. The solver is model based and allows to introduce any kind of parameter model to the analysis. Now the correction could be sensitive to projection problem, which might be dependent on radius or any other coordinate.
lithoAPC combines the Gaussian solver with row and column weighting to support different specification and with respect to the different value ranges of the systematic failures.
This approach allows to extrapolate the systematic based on an measurement and to generate a shot correction map for the exposure recipe.
• Qualification step
lithoAPC has an integrated rule based qualification function. The user defined rules are applied on the input and output values or the work flow. As result of the qualification check messages for the MES system are generated, which can be used to control the next process steps of the lot.
All diagramming is based on a separate module called „Statistics module“. It allows to define diagram templates for various visualization types and to combine those with analysis and R2R data. Finally, the templates can be called from the analysis or R2R modules to visualize the currently selected runs.
This template approach is a very efficient and flexible. It supports advanced diagramming features like:
various diagramming types
- scatter plot
- box plot
- pie charts
- bar plot
- probability plot
- table output
- event time line
- histogram and normal
- distribution chart
In addition the data can be group into distinct charts or series based on the run context.
The software allows to measure several features with one single recipe. All features are assigned to separate groups. A single group or a combination of groups can be used for R2R control (APC). For other groups a simple statistics is calculated and a specification test is performed.
• Multivariate Constraint Optimizer
The „Advanced Solver“ is a unique approach to find the best corrective values for a given lot. The solver takes care for very specific configurations like: it accepts targets from different features with different specifications to calculate the correction it accept target specific specifications and optimizes according to the probability of a specification violation. The solver minimizes the maximum failure. The user can use the specification to fine tune lithoAPC for the chip design. The solver will access any parameter model configured by the user for the process tool.
• Gradient Monitor
lithoAPC analyzes the effective gradient based on productive runs. This allows the engineer to update the configured gradient continuously.The need for test runs to find the optimum gradient will be reduced.
• Source Code Option
Every APC solution is a critical part of semiconductor production. This concerns both the availability of the APC solution and the support for new requirements. We offer a source-code option for the APC solution, which allows you to integrate your own modules, implement new functions and, if required, continue to develop the solution independently.