Semiconductor Spacer Etching to Remove Polymer Residues
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Solution Overview
Problem
The existing photolithography processes struggle to meet the continuously decreasing critical dimensions of semiconductor devices due to the formation of carbon-based polymer residues during etching, which can lead to defects like bumps in subsequent film layers, affecting product yield and productivity.
Innovation Solution
A two-step etching process is employed, where a filling layer is first removed with a high etching rate to expose the spacer, and then with a lower etching rate to specifically remove carbon-based polymers at the boundary of the filling layer and spacer, ensuring the removal of residual polymers and improving the quality of subsequent processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If dry etching is performed using fluorocarbon plasma to etch film layers, then etching capability is improved, but carbon-based polymer residues are formed on the surface of film layers
Solution Approach 1:
The etching process is divided into two distinct stages: a first etching process that removes a first preset thickness of filling layer, and a second etching process that removes a second preset thickness of filling layer. This segmentation allows each etching process to be optimized independently - the first for high removal rate and the second for polymer residue elimination at boundaries.
Solution Approach 2:
The patent applies different etching rates to different regions and stages of the filling layer removal. The first etching process uses a higher etching rate for bulk material removal, while the second etching process uses a lower etching rate specifically at the boundary regions where polymer residues form, achieving local optimization of both etching efficiency and surface quality.
2Device complexity
If polymer residues are not removed, then process simplicity is maintained, but subsequent film layers become defective with bumps affecting product yield
Solution Approach 1:
The patent performs preliminary removal of polymer residues during the etching process itself by exposing the spacer and removing carbon-based polymers at the boundary of the filling layer and spacer before subsequent film layer formation. This preliminary action prevents defects in subsequent processes without requiring separate complex cleaning steps.
3Productivity
If a single high etching rate process is used, then productivity is improved, but polymer residues remain at boundaries affecting critical dimension uniformity
Solution Approach 1:
The etching process is divided into two distinct stages: a first etching process that removes a first preset thickness of filling layer, and a second etching process that removes a second preset thickness of filling layer. This segmentation allows each etching process to be optimized independently - the first for high removal rate and the second for polymer residue elimination at boundaries.
Solution Approach 2:
The patent applies different etching rates to different regions and stages of the filling layer removal. The first etching process uses a higher etching rate for bulk material removal, while the second etching process uses a lower etching rate specifically at the boundary regions where polymer residues form, achieving local optimization of both etching efficiency and surface quality.
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 method effectively eliminates carbon-based polymers, enhancing the stability and quality of semiconductor structures by preventing defects and ensuring even critical dimensions, thereby improving product yield and productivity.
Implementation Method 1
Dry etching is taken as an example, in the dry etching, etching is typically performed using a gas containing fluorocarbon plasma
Implementation Method 2
etching is typically performed using a gas containing fluorocarbon plasma. The adopted gas includes carbon tetrafluoride (CF4), C4F8, C5F8, or C4F6, which may be used as a reaction gas for providing carbon atoms and fluorine atoms
Implementation Method 3
Etching with such gases typically produces a carbon (C)-based polymer after the etching process
Data Source
AI summary
A manufacturing method of a semiconductor structure is disclosed, which includes: an initial structure is provided; a filling layer covering a spacer is formed on the initial structure; a filling layer with a first preset thickness is removed at a high first etching rate through a first etching process, then a filling layer with a second preset thickness is removed at a low second etching rate through a second etching process, and the partial spacer is exposed; and the filling layer and the spacer are patterned.