Tungsten Film CVD Control via Opening-Blocking Detection
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Solution Overview
Problem
In semiconductor manufacturing, the non-uniform film thickness of tungsten films on sidewalls of trenches leads to poor manufacturing efficiency and economic inefficiency due to variations in cavity shapes and inconsistent etching conditions among wafers, and excessive material gas consumption after cavities are blocked.
Innovation Solution
A semiconductor manufacturing method and apparatus that detect the opening-blocking time point to set the film-formation end point, ensuring uniform film thickness and optimizing gas flow by using a predetermined time elapsed from this point, allowing for consistent etching conditions and reduced gas consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a predetermined time elapsed from start of film formation is used as end point, then film formation process is simple to control, but film thickness of tungsten films on sidewalls becomes non-uniform due to variations in cavity shapes
Solution Approach 1:
The patent uses an optical detection system to monitor the film formation process in real-time. A detector measures the amount of reflected light from the wafer surface, and when the cavity openings are blocked by the deposited tungsten film, the reflected light amount changes significantly. This feedback signal automatically determines the end point of film formation, replacing the simple time-based control. The system continuously monitors and adjusts the deposition process to achieve uniform film thickness on sidewalls despite variations in cavity shapes among different wafers.
2Ease of operation
If flow rate of material gas is kept constant from start to end point of film formation, then film formation process is simple to operate, but excessive material gas is supplied after cavities are blocked reducing economic efficiency
Solution Approach 1:
The patent implements dynamic control of material gas flow rate during the film formation process. The gas flow rate is adjusted in multiple stages: initially at a higher rate to rapidly deposit tungsten film and block the cavity openings, then reduced to a lower rate to complete the film formation with uniform thickness. This dynamic adjustment is controlled based on the detected progress of film formation, preventing excessive material gas supply after cavities are blocked and improving economic efficiency.
3Manufacturing precision
If film formation time is extended to ensure sufficient film thickness in cavities, then cavities are properly filled, but tungsten films on sidewalls become too thick requiring more etching
Solution Approach 1:
The patent uses optical detection to identify the precise moment when cavity openings are blocked by the deposited tungsten film. At this point, the system automatically adjusts the deposition conditions to focus on forming uniform sidewall films rather than continuing to fill cavities. This preliminary detection and adjustment prevents over-deposition that would create excessively thick sidewall films requiring extended etching times, thereby reducing the loss of time in subsequent etching processes.
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 ensures uniform etching of tungsten films on sidewalls, improving manufacturing and economic efficiency by maintaining consistent film thickness and reducing material gas usage across different wafers.
Implementation Method 1
a CVD method using material gas is performed to form tungsten films inside cavities in respective layers
Data Source
AI summary
A semiconductor manufacturing method according to an embodiment includes forming a first film on a semiconductor substrate. The semiconductor manufacturing method includes forming cavities in the first film. The semiconductor manufacturing method includes forming a second film inside the cavities by a CVD method using first gas containing a component of the second film, detecting a first time point at which the second film blocks openings of the cavities in forming the second film, and ending forming of the second film at a second time point at which a predetermined time has elapsed from the first time point.