Silicon Nitride Reactive Sputtering for High-Tensile Film Deposition
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Solution Overview
Problem
Existing methods for depositing silicon nitride films in reactive sputtering fail to achieve the high tensile stress required for semiconductor manufacturing, while plasma CVD methods are costly.
Innovation Solution
A method involving a reactive sputtering process where a silicon target and to-be-deposited object face each other, with controlled nitrogen gas flow and target potential, and an electrically conductive member to maintain the silicon target in a transition mode, allowing deposition of β-silicon nitride with a columnar structure and high tensile stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If plasma CVD method is used to deposit silicon nitride film, then high tensile stress (+300 MPa or more) can be achieved, but manufacturing cost increases
Solution Approach 1:
The invention changes the deposition parameters by controlling the nitrogen gas flow ratio and target potential in reactive sputtering to maintain the silicon target surface in transition mode, which enables achieving high tensile stress equivalent to plasma CVD method while using the lower-cost sputtering process
Solution Approach 2:
The invention replaces the plasma CVD method with reactive sputtering method, substituting one deposition mechanism with another that can achieve similar performance (high tensile stress) while reducing manufacturing cost
2Ease of manufacture
If reactive sputtering is used to deposit silicon nitride film, then manufacturing cost is reduced, but tensile stress cannot reach the level required for semiconductor devices
Solution Approach 1:
The invention changes the deposition parameters by controlling the nitrogen gas flow ratio and target potential in reactive sputtering to maintain the silicon target surface in transition mode, which enables achieving high tensile stress equivalent to plasma CVD method while using the lower-cost sputtering process
Solution Approach 2:
The invention dynamically controls the sputtering parameters (nitrogen gas flow ratio and target potential) to maintain the silicon target surface in transition mode between metallic and compound modes, enabling the deposition of silicon nitride film with high tensile stress
3Quantity of substance
If silicon hydride base gas is used in plasma CVD, then silicon nitride film can be deposited, but hydrogen atoms are captured in the film adversely affecting semiconductor devices
Solution Approach 1:
The invention replaces the plasma CVD method with reactive sputtering method, substituting one deposition mechanism with another that can achieve similar performance (high tensile stress) while reducing manufacturing cost
Solution Approach 2:
The invention uses a sputtering gas containing nitrogen and rare gas (inert atmosphere) instead of silicon hydride base gas, eliminating the source of hydrogen atoms that would be captured in the deposited film and adversely affect semiconductor devices
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
The method achieves a silicon nitride film with tensile stress exceeding +300 MPa and refractive index of 2.0±0.2, reducing manufacturing costs and maintaining stable plasma discharge.
Implementation Method 1
a sputtering gas, containing therein nitrogen gas, is introduced into the vacuum chamber in a vacuum atmosphere; and applying a negative potential to the silicon target such that the silicon nitride film having a tensile stress is deposited in a reactive sputtering
Implementation Method 2
maintaining the state in which the bias potential is free from being applied to the to-be-deposited object; and controlling at least one of a flow ratio of the nitrogen gas to the sputtering gas, and the potential to be applied to the silicon target such that the surface of the silicon target can be maintained in a transition mode between a metallic mode and a compound mode, thereby depositing β-silicon nitride
Data Source
AI summary
In a method in which inside a vacuum chamber, a silicon target and a to-be-deposited object are disposed in a positional relationship to face each other; a sputtering gas, containing therein nitrogen gas, is introduced into the vacuum chamber which is in a vacuum atmosphere; a negative potential is applied to the silicon target such that a silicon nitride film having a tensile stress is deposited in a reactive sputtering on a surface of the to-be-deposited object that is placed in an electrically floated state. The method includes steps: in which the to-be-deposited object is made to a state in which a bias potential is free from being applied thereto; and at least one of a flow ratio of the nitrogen gas to the sputtering gas, and the potential to be applied to the silicon target is controlled such that the surface of the silicon target can be maintained in a transition mode.