Cyclic Etch and Deposit for High Aspect Ratio Sidewall Cleaning
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Solution Overview
Problem
Conventional etching techniques face challenges in uniformly removing unwanted material from high aspect ratio features in semiconductor processing, particularly due to difficulties in delivering etch chemistry deep into features and controlling the etching process, leading to issues like over-etching and under-etching.
Innovation Solution
A method involving alternating cycles of etching and deposition operations using inductively coupled and capacitively coupled plasmas, where a protective film is deposited to prevent over-etching and enhance reactant delivery, allowing for selective removal of unwanted material from sidewalls in a controlled manner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching techniques are used to remove unwanted material from high aspect ratio features, then the etching process can be performed, but uniform removal of material is difficult to achieve due to poor reactant delivery deep into features
Solution Approach 1:
The patent applies periodic action by cycling between etching operations and deposition operations. During etching, unwanted material is removed from sidewalls. During deposition, a protective film is deposited to enhance reactant delivery. This periodic cycling continues until uniform material removal is achieved throughout the high aspect ratio feature, resolving the contradiction between manufacturing precision and quantity of substance delivery.
2Productivity
If etching is performed to remove unwanted material, then material can be removed from sidewalls, but over-etching occurs leading to loss of material
Solution Approach 1:
The patent applies preliminary action by depositing a protective film on the sidewalls before performing the etching operation. This protective film serves as a sacrificial layer that controls the etching depth, allowing unwanted material to be removed at a high rate while preventing over-etching. The protective film is deposited in advance to establish the etching boundary, resolving the contradiction between productivity and manufacturing precision.
Solution Approach 2:
The patent applies feedback by cycling between etching and deposition operations, where the deposition step replenishes the protective film that was consumed during etching. This feedback mechanism ensures continuous control of etching depth, allowing high material removal rates while maintaining precise control, thus resolving the contradiction between productivity and manufacturing precision.
3Manufacturing precision
If protective film is deposited to prevent over-etching, then etching control is improved, but the deposition operation adds process time
Solution Approach 1:
The patent applies partial action by depositing a protective film that extends only partially down the sidewalls, leaving the bottom portion exposed for etching. This partial coverage allows etching to proceed efficiently at the bottom while the upper portion is protected, reducing the total deposition time needed compared to full sidewall coverage. This resolves the contradiction between manufacturing precision and loss of time.
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 enables precise and uniform removal of unwanted material along the entire sidewall, reducing the risk of over-etching and achieving controlled sidewall profiles, thereby improving the efficiency and accuracy of semiconductor processing.
Implementation Method 1
performing an etching operation by exposing the substrate to an etching plasma, the etching plasma including a remotely generated inductively coupled plasma
Implementation Method 2
the etching plasma including a remotely generated inductively coupled plasma including an etching reactant
Implementation Method 3
the deposition plasma including a capacitively coupled plasma including a deposition reactant
Implementation Method 4
the deposition plasma including a capacitively coupled plasma including a deposition reactant
Data Source
AI summary
Methods and apparatus for laterally etching unwanted material from the sidewalls of a recessed feature are described herein. In various embodiments, the method involves etching a portion of the sidewalls, depositing a protective film over a portion of the sidewalls, and cycling the etching and deposition operations until the unwanted material is removed from the entire depth of the recessed feature. Each etching and deposition operation may target a particular depth along the sidewalls of the feature. In some cases, the unwanted material is removed from the bottom of the feature up, and in other cases the unwanted material is removed from the top of the feature down. Some combination of these may also be used.