Cusp Magnetic Field Sputtering for Metal Nitride Gate Electrodes
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Solution Overview
Problem
Advanced CMOS device manufacturing faces challenges in achieving desired effective work function and reducing gate leak current without increasing equivalent oxide thickness, particularly with the PVD method, which struggles to obtain desired effective work function and deteriorates leak current characteristics.
Innovation Solution
The method involves using a sputtering deposition process with a cusp magnetic field to form metal nitride films on semiconductor substrates, employing a metal target and introducing nitrogen gas to create plasma, allowing for the formation of high-permittivity insulating films and metal nitride layers that improve leak current characteristics and achieve desired effective work functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the PVD method is used to form metal gate electrodes, then fewer impurities are mixed in the material compared to CVD, but the leak current characteristics deteriorate and the desired effective work function cannot be obtained
Solution Approach 1:
The invention changes the physical parameters of the sputtering process by introducing a cusp magnetic field configuration and optimizing gas flow rates (Ar: 20-100 sccm, N2: 5-50 sccm) and pressure (0.5-5 Pa) to achieve both high material purity and excellent leak current characteristics with effective work function of 4.5-5.0 eV
Solution Approach 2:
The invention uses composite metal nitride materials (TiN, TaN, WN) as gate electrodes, combining the advantages of different metals to achieve both low impurity content and desired effective work function while maintaining excellent leak current characteristics
2Reliability
If the CVD method is used to form metal gate electrodes, then the desired effective work function and good leak current characteristics are achieved, but a larger amount of impurities is mixed in the material
Solution Approach 1:
The invention replaces the chemical vapor deposition process with a physically-based sputtering process enhanced by cusp magnetic field, substituting chemical reactions with physical bombardment to reduce impurity incorporation while maintaining the ability to control effective work function and leak current characteristics
3Ease of manufacture
If conventional DC sputtering is used to form metal nitride films, then the process is simple, but the leak current characteristics deteriorate and the desired effective work function cannot be obtained with transistor miniaturization
Solution Approach 1:
The invention introduces dynamic control elements to the sputtering process including adjustable cusp magnetic field strength, variable gas flow rates, and controllable pressure conditions, allowing optimization of both process simplicity and device performance for miniaturized transistors
Solution Approach 2:
The cusp magnetic field acts as an intermediary that enhances the sputtering process by confining plasma and increasing ion bombardment efficiency, thereby improving leak current characteristics and effective work function without significantly complicating the overall manufacturing process
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 enables the achievement of desired effective work functions and improved leak current characteristics without increasing equivalent oxide thickness, suitable for both n-type and p-type MOSFETs, enhancing transistor performance.
Implementation Method 1
a step of sputtering deposition in an evacuatable process chamber by use of a metal target and a cusp magnetic field formed over a surface of the metal target
Implementation Method 2
forming plasma of the nitrogen by the cusp magnetic field
Implementation Method 3
a cusp magnetic field formed over a surface of the metal target by a structure in which a plurality of magnet pieces are arranged as grid points
Data Source
AI summary
The present invention provides a method and apparatus for manufacturing a semiconductor device using a PVD method and enabling achievement of a desired effective work function and reduction in leak current without increasing an equivalent oxide thickness. A method for manufacturing a semiconductor device in an embodiment of the present invention includes the steps of: preparing a substrate on which an insulating film having a relative permittivity higher than that of a silicon oxide film is formed; and depositing a metal nitride film on the insulating film. The metal nitride depositing step is a step of sputtering deposition in an evacuatable chamber using a metal target and a cusp magnetic field formed over a surface of the metal target by a magnet mechanism in which magnet pieces are arranged as grid points in such a grid form that the adjacent magnet pieces have their polarities reversed from each other.