Titanium Nitride Film Stress Control via Sputtering Pressure and Bias
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Solution Overview
Problem
Current methods fail to separately manufacture thin films with desired compressive and tensile stresses while maintaining high film density, which is essential for semiconductor device manufacturing, particularly for titanium nitride films used as hard masks, as they often result in decreased density when attempting to change stress from compressive to tensile.
Innovation Solution
A method involving sputtering with a nitrogen-containing gas at elevated pressures and controlled bias conditions, where a weak bias is applied to achieve tensile stress and increasing bias to shift stress to compressive, maintaining high film density by adjusting the pressure and bias ratios within specific ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a high-density titanium nitride film is formed by conventional sputtering methods, then the film density is high, but the film stress is high on the compressive side
Solution Approach 1:
The patent changes multiple sputtering parameters simultaneously: increases process gas pressure from conventional low levels to 0.5-5 Pa, applies weak substrate bias voltage (0-50 V), and controls gas composition (Ar/N2 ratio). These parameter changes work together to reduce film stress from compressive to tensile while maintaining high film density, resolving the contradiction between density and stress control.
2Stress or pressure
If the process gas pressure is increased to reduce compressive stress, then film stress shifts to tensile side, but film density decreases
Solution Approach 1:
The patent optimizes the process gas pressure to a specific range (0.5-5 Pa) and combines it with weak substrate bias (0-50 V) and controlled gas composition. This coordinated parameter change achieves the dual goal of reducing compressive stress (shifting to tensile) while maintaining high film density, preventing the density decrease that would normally occur with pressure increase alone.
3Stress or pressure
If a titanium nitride film with tensile stress is formed to balance stress with underlying compressive stress films, then the overall film stress is balanced, but the titanium nitride film density decreases
Solution Approach 1:
The patent employs a specific combination of process parameters: process gas pressure of 0.5-5 Pa, weak substrate bias voltage of 0-50 V, and controlled Ar/N2 gas composition. This parameter set enables the formation of titanium nitride films with tensile stress needed for balancing overall film stress, while simultaneously maintaining high film density through the synergistic effect of these parameters.
4Stress or pressure
If conventional methods are used to change film stress from compressive to tensile, then stress control is achieved, but complex additional systems or post-forming heat treatment is required
Solution Approach 1:
The patent achieves stress control from compressive to tensile by modifying standard sputtering parameters (pressure, bias voltage, gas composition) that are already available in conventional sputtering systems. This eliminates the need for complex additional systems or post-forming heat treatment processes, as the stress control is accomplished during the film formation process itself through parameter optimization.
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 allows for the stable production of titanium nitride films with desired stress values from compressive to tensile while maintaining high density, suitable for semiconductor applications, enabling balanced film stress and resistance to etching.
Implementation Method 1
a method of forming an internal stress control film on one surface of an object to be processed by a sputtering method
Implementation Method 2
selecting a pressure of a process gas at the time of forming the internal stress control film from a pressure region higher than a threshold value of 5 (Pa)
Data Source
AI summary
A method of forming an internal stress control film on one surface of an object to be processed by a sputtering method, includes selecting a pressure of a process gas at the time of forming the internal stress control film from a pressure region higher than a threshold value of 5 (Pa) so that stress of the object to be processed when a bias is applied to the object to be processed becomes larger stress on a tensile side and the internal stress control film has higher density, as compared with stress in a case in which a bias is not applied thereto.