Substrate Inclination and Rotation for Recess Etching
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Solution Overview
Problem
In semiconductor device wiring, the damascene method results in base metal layers becoming thicker at corner portions of recesses, narrowing the opening and leading to defective copper embedding due to void generation, as existing etching methods can remove the base metal layer and are not effective in uniformly expanding the opening width.
Innovation Solution
A method involving the formation of a barrier and seed layer on a substrate, followed by etching these layers while inclining the substrate relative to the ion irradiation direction and rotating it, to preferentially etch the metal layers at corner portions and expand the opening width without removing the base metal layer from the recess walls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If sputter etching is performed on the base metal layer to expand the opening width, then the opening width is expanded, but the base metal layer becomes thinner and may be removed
Solution Approach 1:
The patent applies different etching conditions to different regions of the base metal layer. By controlling the substrate inclination angle and rotation, the etching is selectively applied to the corner portions where the opening width needs expansion, while the wall surface regions are protected from excessive etching. This local differentiation allows opening expansion without compromising the base metal layer integrity.
Solution Approach 2:
The patent introduces dynamic control of the substrate during etching by rotating the substrate and adjusting its inclination angle relative to the ion beam. This dynamic adjustment allows real-time control of the etching process, enabling selective removal of base metal at corners while preserving it on wall surfaces, thus resolving the contradiction between opening expansion and material preservation.
2Reliability
If the base metal layer is made thicker to ensure coverage, then the layer provides better coverage, but the opening width is narrowed leading to defective copper embedding
Solution Approach 1:
The patent performs preliminary etching of the base metal layer before copper embedding to expand the opening width. By proactively removing excess base metal from the corner portions in advance, the opening is widened to accommodate subsequent copper filling, preventing defective embedding while maintaining adequate base metal coverage on critical surfaces.
Solution Approach 2:
The patent creates local variations in base metal layer thickness through selective etching. The corner portions are thinned to expand the opening, while the wall surface portions maintain sufficient thickness for reliable copper embedding. This local quality differentiation resolves the contradiction between overall coverage and local opening width.
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 effectively suppresses the loss of the base metal layer and expands the recess opening width, preventing voids during copper embedding and ensuring uniform etching of the metal layers, thereby improving the copper wiring process.
Implementation Method 1
In such a sputter etching, however, the wall surface that defines the recess, for example, the base metal layer formed on a bottom surface, as well as the base metal layer formed in the corner portion, may be also etched.
Implementation Method 2
at least one of etching the barrier layer and etching the seed layer, wherein, in the at least one of etching the barrier layer and etching the seed layer, the substrate is inclined with respect to an irradiation direction of ions while rotating the substrate
Implementation Method 3
In general, a sputtering method is used to form the barrier layer and the seed layer
Data Source
AI summary
There is provided a method for performing a pre-treatment to form a copper wiring in a recess formed in a substrate, which includes forming a barrier layer on a surface of the substrate that defines the recess, and forming a seed layer on the barrier layer. The method further includes at least one of etching the barrier layer and etching the seed layer. In the at least one of etching the barrier layer and etching the seed layer, the substrate is inclined with respect to an irradiation direction of ions while rotating the substrate.