Full-Chip Cell CD Correction via Density Map Retargeting
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Solution Overview
Problem
Existing methods for manufacturing masks in semiconductor processes struggle to effectively correct cell critical dimension (CD) errors across a full-chip, leading to inaccuracies in pattern transfer and increased defects.
Innovation Solution
A method involving the generation of a density map for a full-chip, conversion into a retarget rule table, reconfiguration of cell blocks into an optical proximity correction (OPC) target cell layout, application of biases based on the retarget rule table, and performing hierarchical OPC to generate an optical proximity corrected (OPC'ed) layout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing mask manufacturing methods are used, then the process is simple and fast, but cell critical dimension errors cannot be effectively corrected across the full-chip
Solution Approach 1:
The full-chip layout is divided into multiple cell blocks, which are further segmented into individual cells. This hierarchical segmentation allows the correction process to be applied systematically across the entire chip while managing complexity through modular processing of smaller units.
Solution Approach 2:
A density map is generated and analyzed before the actual OPC correction is applied. The retarget rule table is prepared in advance based on the density analysis, allowing the correction process to use pre-calculated parameters rather than computing everything during the correction phase.
2Manufacturing precision
If conventional OPC methods are applied, then the manufacturing process remains simple, but pattern transfer accuracy deteriorates due to uncorrected CD errors
Solution Approach 1:
The density map generation and retarget rule table creation are performed as preliminary steps before the actual OPC correction. This allows the complex calculations to be done once in advance, making the subsequent correction process more efficient and reducing overall processing time.
Solution Approach 2:
The correction process applies different biases to different cells based on their local density characteristics. Each cell receives a customized correction amount determined by its position in the density map, allowing precise local adjustments without requiring full-chip reprocessing.
3Manufacturing precision
If no density-based correction is applied, then the process is fast and simple, but CD errors vary significantly across different regions of the full-chip
Solution Approach 1:
The patent applies different correction biases to different regions of the chip based on the density map. High-density regions receive one type of correction while low-density regions receive another, ensuring uniform CD control across the entire chip by addressing local variations specifically.
Solution Approach 2:
The density map serves as an intermediary data structure that captures the spatial distribution of pattern density across the chip. This intermediate representation allows the system to analyze density variations and translate them into appropriate correction parameters without directly manipulating the original layout data.
Data Source
AI summary
A full-chip cell critical dimension (CD) correction method and a method of manufacturing a mask by using the same are provided. The full-chip cell CD correction method includes receiving a database (DB) about a full-shot; analyzing a hierarchy of the DB; generating a density map of a full-chip by using the DB and converting the density map into a retarget rule table, the converting including mapping the density map by using a density rule; reconfiguring cell blocks of the full-chip into an optical proximity correction (OPC) target cell layout for OPC; applying a first bias to the OPC target cell layout, based on the retarget rule table; and generating an optical proximity corrected (OPC'ed) layout for the full-chip by performing hierarchical OPC.