Tungsten Conductive Layer Etching for Uniform Anisotropic Profiles
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Solution Overview
Problem
The challenge in semiconductor device fabrication is the undercutting of conductive interconnect features due to wet-chemical etching, leading to loss in etched pattern resolution and non-uniform etch rates across zones of varying pattern densities, which increases processing time.
Innovation Solution
A method involving a plasma process with a specific gas mixture of fluorine, chlorine, and oxygen, combined with a pulsing bias voltage, is used to etch a tungsten layer through a carbon hard mask, achieving anisotropic etching and uniform etch rates across zones of different pattern densities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wet-chemical etching is used to etch the metal layer, then the etching process can be performed, but undercutting of the layer under the etch mask occurs leading to loss in etched pattern resolution
Solution Approach 1:
The patent replaces wet-chemical etching with a plasma etching process. The plasma process uses reactive ions to etch the metal layer, providing anisotropic etching that eliminates undercutting and improves etched pattern resolution while maintaining the ability to transfer patterns accurately.
Solution Approach 2:
The patent changes the etching parameters by using a specific plasma process with a gas mixture containing fluorine-based gas, chlorine-based gas, and oxygen. This parameter change enables controlled anisotropic etching that prevents undercutting while achieving the desired pattern transfer.
2Productivity
If wet-chemical etching is used, then etching can be performed, but the etch rate varies in zones with different pattern densities requiring multiple stages which increases processing time
Solution Approach 1:
The patent replaces wet-chemical etching with plasma etching, which provides uniform etch rates across zones with different pattern densities. The plasma process eliminates the need for multiple etching stages, reducing processing time while maintaining precise etch rate control throughout the entire metal layer.
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 efficient fabrication of a conductive layer with controlled etch profiles and uniform etch rates, allowing for the formation of features with varying gaps in a single process, reducing processing time and improving etch profile control.
Implementation Method 1
performing a plasma process to the metal layer through the patterned hard mask layer
Implementation Method 2
a process gas mixture used in the plasma process includes a fluorine based gas, a chlorine based gas, and oxygen
Implementation Method 3
a process gas mixture used in the plasma process includes a fluorine based gas, a chlorine based gas, and oxygen
Implementation Method 4
A method involving a plasma process with a specific gas mixture of fluorine, chlorine, and oxygen, combined with a pulsing bias voltage
Implementation Method 5
achieving anisotropic etching and uniform etch rates
Data Source
AI summary
A method of forming a conductive layer of a semiconductor device is described. The method includes forming a hard mask layer on a metal layer overlying a substrate, in which the metal layer includes tungsten. The method further includes patterning the hard mask layer until portions of the metal layer are exposed from the patterned hard mask layer. The method further includes performing a plasma process to the metal layer through the patterned hard mask layer until portions of the substrate are exposed from the etched metal layer, in which a process gas mixture used in the plasma process includes a fluorine based gas, a chlorine based gas, and oxygen.