Circuit Layout Dummy Pattern for Etching Residue Management
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Solution Overview
Problem
In semiconductor manufacturing, the etching process is hindered by undesired capacitance between conductive elements, leading to accumulation of charged etching residues in trench openings, which prevents successful exposure of contact plugs and affects electrical interconnection.
Innovation Solution
A circuit layout structure with a dummy pattern in the scribe line region, where the dummy pattern has a transmission rate between 0% and 1%, attracts charged etching residues during the etching process, allowing complete formation of desired via or trench patterns in the cell region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conductive alignment mark and metal hard mask are positioned close to each other in the scribe line region, then alignment precision is improved, but capacitance between them increases causing etching residue accumulation
Solution Approach 1:
The patent introduces a dummy pattern as an intermediary element positioned between the conductive alignment mark and the metal hard mask. This dummy pattern acts as a mediator that receives and accumulates the charged etching residues attracted by the capacitance field, preventing them from accumulating in the trench openings and interfering with the etching process. The dummy pattern thus serves as a sacrificial intermediary that protects the critical etching regions from harmful residue accumulation.
2Reliability
If etching process is performed to expose contact plug, then electrical interconnection is enabled, but charged etching residues accumulate in trench openings blocking the etching completion
Solution Approach 1:
The patent converts the harmful effect of capacitance-induced charged residue accumulation into a beneficial process by strategically placing a dummy pattern that acts as a trap for these residues. The capacitance field that originally caused problems now serves to direct residues toward the dummy pattern rather than the trench openings. This transforms the harmful capacitance effect into a useful mechanism for residue management, ensuring clean etching completion in the cell region while maintaining electrical interconnection reliability.
3Productivity
If dummy pattern with low transmission rate is added in scribe line region, then etching yield is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by introducing the dummy pattern specifically in the scribe line region rather than uniformly across the entire wafer. The dummy pattern is positioned locally where the capacitance issue occurs between the alignment mark and hard mask. This localized approach improves etching yield in the affected areas without unnecessarily complicating the entire device structure. The dummy pattern is confined to non-critical scribe line areas, minimizing its impact on overall device complexity while maximizing its benefit to etching performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves the yield of the etching step by ensuring the desired patterns are formed without excess residues, enabling effective electrical interconnection.
Implementation Method 1
an adverse capacitance is always generated between the metal hard mask 140 and the conductive alignment/AIM mark 124 in the scribe line region 114 during the etching step
Data Source
AI summary
A circuit layout structure includes a wafer having at least a cell region and a scribe line region defined thereon, a metal pattern formed in a first insulating layer in the scribe line region, a second insulating layer and a hard mask layer formed on the metal pattern and the first insulating layer, and at least a dummy pattern formed in the second insulating layer and the hard mask layer in the scribe line region. The dummy pattern has a transmission rate between 0% and 1%.