Hard Mask Removal Using Protecting Structure to Shield Isolation
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Solution Overview
Problem
The existing methods for removing hard masks in semiconductor device fabrication often result in etching of shallow trench isolations, leading to reduced thickness and increased current leakage, as well as seam formation between the contact etch stop layer and the isolation structure during the wet etching process.
Innovation Solution
A method involving the formation of a protecting structure, such as a photoresist layer or bottom anti-reflective coating, to shield the isolating structure from etching during the removal of the hard mask, preventing recess formation and subsequent current leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wet etching process is used to remove hard mask, then hard mask can be effectively removed, but shallow trench isolation is simultaneously etched causing thickness reduction and current leakage
Solution Approach 1:
The patent introduces a protecting structure as an intermediary layer between the etching process and the shallow trench isolation. This protecting structure selectively protects the isolation regions during hard mask removal, allowing precise etching of the hard mask while preventing damage to the isolation structure, thereby resolving the contradiction between removal precision and isolation integrity
Solution Approach 2:
The patent applies different protective measures to different regions: the protecting structure is formed only in regions where shallow trench isolation is present, while leaving other regions exposed for complete hard mask removal. This localized protection approach enables selective preservation of isolation structures without compromising overall hard mask removal effectiveness
2Ease of manufacture
If wet etching process is used to remove hard mask, then hard mask can be removed, but recess formation occurs in shallow trench isolation leading to seam formation with contact etch stop layer
Solution Approach 1:
The protecting structure serves as an intermediary barrier that prevents the etching process from creating recesses in the shallow trench isolation. By blocking the etchant from contacting the isolation structure, the protecting structure maintains the isolation's original flat surface profile, preventing seam formation with the subsequent contact etch stop layer while still allowing easy hard mask removal
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 effectively prevents the etching of shallow trench isolations, reducing current leakage and avoiding seams between the contact etch stop layer and the isolating structure, thereby enhancing the integrity of the semiconductor device fabrication process.
Implementation Method 1
A protecting structure is formed on the isolating structure and the hard mask is exposed from the protecting structure
Data Source
AI summary
A removing method of a hard mask includes the following steps. A substrate is provided. At least two MOSFETs are formed on the substrate. An isolating structure is formed in the substrate and located between the at least two MOSFETs. Each of the MOSEFTs includes a gate insulating layer, a gate, a spacer and a hard mask on the gate. A protecting structure is formed on the isolating structure and the hard mask is exposed from the protecting structure. The exposed hard mask is removed to expose the gate.