Plasma Deposition Initiation Modulation for Film Stress Control
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Solution Overview
Problem
Conventional semiconductor deposition methods face challenges such as film shrinking, increased internal stress, and poor interfacial density, leading to issues like wafer bowing and undercut during etching processes, particularly when using silicon oxide films deposited with tetraethyl orthosilicate (TEOS) at high temperatures.
Innovation Solution
The method involves forming a plasma of an oxygen-containing precursor within a semiconductor processing chamber, ramping the flow rate of a silicon-containing precursor, and controlling the deposition process to achieve films with controlled stress characteristics by alternating between tensile and compressive stress layers, thereby improving interfacial density and reducing film shrinking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high temperature deposition is used to deposit silicon oxide films with TEOS, then deposition rate is improved, but film shrinking and internal stress increase
Solution Approach 1:
The patent changes the deposition temperature parameter from conventional high temperatures (400-450°C) to lower temperatures (200-400°C), and modifies the precursor chemistry from traditional TEOS to alternative silicon sources. This parameter change resolves the contradiction by achieving adequate deposition rates at lower temperatures that reduce film shrinking and internal stress, improving film stability without sacrificing productivity
Solution Approach 2:
The patent uses oxygen plasma as a strong oxidant during deposition to enhance the reactivity and deposition rate at lower temperatures. The oxygen plasma provides accelerated oxidation of the silicon precursor, enabling sufficient deposition rates at reduced temperatures where film shrinking and stress are minimized, thus resolving the contradiction between productivity and reliability
2Ease of manufacture
If conventional deposition methods are used, then deposition process is simple, but interfacial density is poor leading to undercut during etching
Solution Approach 1:
The patent applies preliminary plasma treatment to the substrate surface before deposition and uses specific precursor sequencing (introducing oxygen-containing precursors before silicon-containing precursors) to prepare the surface. This preliminary action creates a high-density interfacial layer that prevents undercut during etching, improving manufacturing precision while maintaining process simplicity through integrated plasma steps
Solution Approach 2:
The patent introduces oxygen-containing precursors as an intermediary layer between the substrate and the silicon oxide film. This intermediary layer forms a high-density transition region that improves interfacial adhesion and prevents etch undercut, achieving better manufacturing precision without significantly complicating the overall deposition process
3Productivity
If high flow rate of silicon precursor is used, then deposition rate increases, but film stress becomes uncontrolled causing wafer bowing
Solution Approach 1:
The patent employs periodic modulation of precursor flow rates during deposition, alternating between oxygen-containing and silicon-containing precursors in controlled cycles. This periodic action allows the film to deposit at adequate rates while periodically relieving built-up stress through oxygen-rich segments, preventing uncontrolled stress accumulation and wafer bowing
Solution Approach 2:
The patent uses dynamic adjustment of precursor flow rates and plasma power during the deposition process. By dynamically modulating the silicon precursor flow rate and oxygen plasma conditions, the system maintains controlled stress levels while achieving sufficient deposition rates, resolving the contradiction between productivity and stress control
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 results in higher quality films with reduced film shrinking, improved interfacial density, and enhanced sidewall coverage, minimizing undercut during etching and maintaining film integrity, while allowing for lower temperature deposition and controlled stress adjustment.
Implementation Method 1
forming a plasma of an oxygen-containing precursor within a processing region of a semiconductor processing chamber
Implementation Method 2
forming the plasma of the oxygen-containing precursor may produce an oxygen-radicalized surface termination of the silicon of the semiconductor substrate
Implementation Method 3
flowing a silicon-containing precursor into the processing region of the semiconductor processing chamber at a first flow rate... depositing a silicon-containing material on the semiconductor substrate
Data Source
AI summary
Exemplary deposition methods may include forming a plasma of an oxygen-containing precursor within a processing region of a semiconductor processing chamber. The processing region may house a semiconductor substrate on a substrate support. The methods may include, while maintaining the plasma of the oxygen-containing precursor, flowing a silicon-containing precursor into the processing region of the semiconductor processing chamber at a first flow rate. The methods may include ramping the first flow rate of the silicon-containing precursor over a period of time to a second flow rate greater than the first flow rate. The methods may include depositing a silicon-containing material on the semiconductor substrate.