Plasma Silicon Oxide Film Formation for Mask Opening Control
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Solution Overview
Problem
In semiconductor manufacturing, the resolution limit of traditional resist masks restricts the formation of patterns smaller than the mask's resolution, and existing methods to reduce opening widths, such as using silicon oxide films, require high temperatures and dedicated equipment, potentially damaging the workpiece and affecting device characteristics.
Innovation Solution
A plasma processing method involving alternating sequences of silicon halide gas plasma generation, purging, oxygen gas plasma generation, and further purging, allows for the formation of a thin, uniform silicon oxide film on the mask at low temperatures without dedicated equipment, enabling precise adjustment of opening widths and reducing line edge roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a silicon oxide film is formed on the resist mask by atomic layer deposition (ALD) method using aminosilane gas, then the opening width of the mask is reduced, but high temperature processing is required which may damage the workpiece and affect device characteristics
Solution Approach 1:
The invention changes the chemical parameters of the precursor gas from aminosilane to silicon halide gas, which enables film formation at lower temperatures. By altering the chemical composition and reactivity of the gas phase precursor, the process temperature is reduced while maintaining the ability to form conformal silicon oxide films on the mask, thus preventing workpiece damage while achieving precise opening width control
Solution Approach 2:
The invention replaces the thermal field (high temperature ALD process) with a plasma field (low temperature plasma CVD process). By using plasma activation instead of thermal activation, the mechanical/thermal stress on the workpiece is eliminated while the chemical deposition process continues to function effectively, enabling low temperature film formation with precise control
2Ease of manufacture
If traditional photolithography technique is used to form the resist mask, then the process is simple and widely applicable, but the critical dimension is limited by the resolution limit of the photolithography system
Solution Approach 1:
The invention performs a preliminary action by forming a silicon oxide film on the resist mask before the actual photolithography patterning step. This preliminary film deposition modifies the mask properties to enable sub-resolution patterning, allowing the subsequent photolithography process to achieve critical dimensions smaller than the traditional resolution limit while maintaining process simplicity
Solution Approach 2:
The invention creates a composite mask structure by depositing silicon oxide film on the resist mask, forming a multi-layer composite material system. This composite structure combines the patterning capability of the resist mask with the dimensional control properties of the silicon oxide film, enabling precise critical dimension control below the photolithography resolution limit
3Manufacturing precision
If alternating plasma generation and purging processes are used to form silicon oxide film, then conformal coverage and uniform thickness are achieved, but the processing time increases
Solution Approach 1:
The invention applies periodic action by alternating between plasma generation phases (for film deposition) and purging phases (for byproduct removal and gas exchange). This periodic cycling enables conformal film coverage and uniform thickness control while managing the trade-off with processing time through optimized cycle durations and sequences
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 forms conformal silicon oxide films with controlled thickness, enhancing the controllability of mask opening widths and reducing damage to the workpiece, while maintaining the integrity of electronic device characteristics.
Implementation Method 1
a first process of generating plasma of a first gas containing a silicon halide gas in a processing container
Implementation Method 2
a third process of generating plasma of a second gas containing oxygen gas in the processing container to form a silicon oxide film
Implementation Method 3
forming a thin, uniform silicon oxide film on the mask
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
Disclosed is a method of processing a workpiece including a mask. The processing method includes: a first process of generating plasma of a first gas containing a silicon halide gas in a processing container of a plasma processing apparatus that accommodates a workpiece having a mask, to form a reactive precursor; a second process of purging a space in the processing container; a third process of generating plasma of a second gas containing oxygen gas in the processing container to form a silicon oxide film; and a fourth process of purging the space in the processing container. In the processing method, a sequence including the first to fourth processes is repeated.