Selective Barrier Metal Etching for Ruthenium Etch Stop Removal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In semiconductor manufacturing, particularly at sub 7 nm nodes, ruthenium-based structures face challenges during lithography-and-etch processes due to the partial oxidation of barrier metal layers, which acts as an etch stop layer, preventing the ruthenium layer from being etched to the surface of the barrier metal layer.
Innovation Solution
A method involving hydrogen implantation in an inductively coupled plasma (ICP) etch chamber to chemically reduce the oxidized portion of the barrier metal layer, followed by an etch process using a chlorine containing gas to remove the hydrogen implanted portion, thereby allowing the ruthenium layer to be etched to the desired profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If oxygen containing etching gas is used to etch the ruthenium layer, then the ruthenium layer can be etched, but the barrier metal layer is partially oxidized and sputtered onto the ruthenium layer, acting as an etch stop layer
Solution Approach 1:
The patent applies preliminary action by performing hydrogen implantation on the oxidized barrier metal layer before the etching process. This pre-treatment reduces the oxidized portion of the barrier metal layer, eliminating the etch stop layer issue before etching begins, thereby enabling the ruthenium layer to be etched to the desired profile without interruption
Solution Approach 2:
The patent changes the chemical state of the barrier metal layer by using hydrogen implantation to reduce the oxidized portion. This parameter change transforms the barrier metal from an oxidized state (which acts as an etch stop) to a reduced state (which allows etching to proceed), resolving the contradiction between etching speed and etch profile
2Reliability
If the barrier metal layer is oxidized during etching, then the ruthenium layer etching is interrupted, but the desired etch profile cannot be achieved
Solution Approach 1:
The hydrogen implantation process is performed as a preliminary action before etching to reduce the oxidized barrier metal layer. This pre-treatment ensures that the barrier metal layer will not act as an etch stop during the subsequent etching process, thereby maintaining both process stability and achieving the desired line critical dimension
Solution Approach 2:
The patent converts the harmful effect of oxidation (which creates an etch stop layer) into a beneficial process step. By intentionally oxidizing the barrier metal layer and then using hydrogen implantation to reduce it, the process transforms a problematic side effect into a controlled preparatory step that ensures successful etching
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 method enables the formation of ruthenium-based structures with desired line critical dimensions by effectively removing the oxidized barrier metal layer, thus overcoming the etch stop layer issue and achieving the desired etch profile.
Implementation Method 1
performing a hydrogen implantation process, in an inductively coupled plasma (ICP) etch chamber, to chemically reduce an oxidized portion of a barrier metal layer
Implementation Method 2
to chemically reduce an oxidized portion of a barrier metal layer formed within a feature
Implementation Method 3
performing an etch process, in the ICP etch chamber, to remove the hydrogen implanted portion of the barrier metal layer
Implementation Method 4
the barrier metal layer is partially oxidized and is sputtered onto the ruthenium layer
Data Source
AI summary
A method for selective barrier metal etching includes performing a hydrogen implantation process, in an inductively coupled plasma (ICP) etch chamber, to chemically reduce an oxidized portion of a barrier metal layer formed within a feature in a metal layer on the barrier metal layer, and performing an etch process, in the ICP etch chamber, to remove the hydrogen implanted portion of the barrier metal layer.