Gate Electrode Work Function Tuning With AlW Layers
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Solution Overview
Problem
The semiconductor industry faces challenges in tuning work function values of gate electrodes in semiconductor devices, which affects the integration density and performance of electronic components, particularly in achieving lower threshold voltages and higher speed.
Innovation Solution
The method involves implanting dopants like lanthanum, aluminum, or magnesium in p-type work function metal layers and exposing n-type work function metal layers to transition metal chlorides to form tuning layers, thereby adjusting the work function values and increasing the process window for gate electrode filling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If work function values are not tuned, then manufacturing process is simpler, but threshold voltage cannot be lowered and device speed is limited
Solution Approach 1:
The patent applies preliminary action by forming tuning layers (such as aluminum oxide, titanium oxide, or tantalum oxide) on the work function metal layers before final gate electrode fabrication. This preliminary oxidation process pre-adjusts the work function values, enabling subsequent steps to achieve desired threshold voltages and higher device speed without adding excessive manufacturing complexity.
Solution Approach 2:
The patent employs parameter changes by modifying the chemical composition and physical properties of work function metal layers through controlled oxidation. By adjusting oxidation conditions (temperature, time, atmosphere), the work function values are precisely tuned to achieve lower threshold voltages and improved device performance while maintaining manufacturing feasibility.
2Manufacturing precision
If work function metal layers are not tuned, then manufacturing process window is larger, but threshold voltage control is insufficient
Solution Approach 1:
The tuning layers are formed in advance through controlled oxidation processes, establishing a foundation for precise threshold voltage control. This preliminary step creates a more predictable and controllable manufacturing process window, allowing subsequent fabrication steps to achieve better threshold voltage precision without significantly reducing overall productivity.
Solution Approach 2:
By changing the oxidation parameters (temperature, duration, gas composition), the patent achieves precise control over the tuning layer properties, which directly influences threshold voltage. This parameter adjustment capability enhances manufacturing precision while maintaining an adequate process window for production.
3Reliability
If dopants are implanted in work function metal layers, then work function values are tuned and device performance improves, but additional manufacturing steps are required
Solution Approach 1:
The patent uses oxidation processes as an intermediary method to tune work function values, avoiding the need for direct dopant implantation. The oxidation process acts as a mediator that modifies the work function metal layers through chemical transformation rather than physical doping, achieving device performance improvement while reducing manufacturing complexity.
Solution Approach 2:
The patent replaces mechanical/physical dopant implantation processes with chemical oxidation processes. This substitution eliminates the need for complex ion implantation equipment and multiple doping steps, reducing the number of manufacturing steps while achieving comparable or superior device performance through controlled chemical reactions.
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 manufacturing of semiconductor devices with lower threshold voltages, higher speed, and improved performance by tuning work function values, enhancing the integration density and flexibility of subsequent layers.
Implementation Method 1
exposing the n-type work function metal layer to a work function tuning gas... may deposit a tuning layer over the n-type work function metal layer
Implementation Method 2
implanting a dopant in a p-type work function metal layer
Data Source
AI summary
Methods for tuning effective work functions of gate electrodes in semiconductor devices and semiconductor devices formed by the same are disclosed. In an embodiment, a semiconductor device includes a channel region over a semiconductor substrate; a gate dielectric layer over the channel region; and a gate electrode over the gate dielectric layer, the gate electrode including a first work function metal layer over the gate dielectric layer, the first work function metal layer including aluminum (Al); a first work function tuning layer over the first work function metal layer, the first work function tuning layer including aluminum tungsten (AlW); and a fill material over the first work function tuning layer.