Metal Oxide Etch Stop Layer With Low-Hydroxyl Oxidation Control
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Solution Overview
Problem
Existing etch stop layers in semiconductor fabrication contain hydroxyl groups, which can cause oxidation of metal elements in underlying conductive features, leading to void formation and increased parasitic capacitance as semiconductor technology scales down.
Innovation Solution
A method is developed to significantly reduce or eliminate hydroxyl groups from the etch stop layer, allowing for an etch stop layer thickness of less than 50 Å, by using special treatments such as ALD processes, dopant deposition, and plasma treatments to form M—O—Si groups, thereby reducing oxidation capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal oxide composite is used to form etch stop layer, then high etch selectivity is achieved, but hydroxyl groups cause oxidation of metal elements in underlying conductive features
Solution Approach 1:
The patent removes hydroxyl groups from the metal oxide etch stop layer through thermal annealing treatment. This extraction of harmful hydroxyl groups eliminates their oxidation capability while preserving the metal oxide's etch stop functionality, thereby resolving the contradiction between maintaining etch selectivity and preventing metal oxidation.
Solution Approach 2:
The patent applies thermal annealing treatment to the metal oxide layer before it contacts the underlying conductive features. This preliminary removal of hydroxyl groups prevents subsequent oxidation of metal elements during device fabrication, addressing the harmful effect before it can occur.
2Length of stationary object
If etch stop layer thickness is reduced, then parasitic capacitance is reduced, but oxidation protection capability may be compromised
Solution Approach 1:
The patent changes the chemical composition parameter of the etch stop layer by removing hydroxyl groups through thermal annealing. This parameter change eliminates the oxidation capability of the layer, allowing it to provide adequate protection even at reduced thicknesses, thus resolving the contradiction between thin layer requirements and protection capability.
3Ease of manufacture
If hydroxyl groups are present in metal oxide layer, then etch stop layer formation is adequate, but void formation occurs due to oxidation of metal elements
Solution Approach 1:
The patent utilizes thermal annealing treatment to convert the harmful hydroxyl groups into water vapor that can be evacuated. This process transforms the oxidation-prone hydroxyl groups into a removable byproduct, eliminating void formation while maintaining the etch stop layer's manufacturing adequacy.
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
The method effectively prevents oxidation of underlying conductive features, reduces parasitic capacitance, and increases the operation speed of integrated circuits, while being easily integratable into existing semiconductor fabrication processes.
Implementation Method 1
Metal oxide composite may be used to form etch stop layers for end point control, providing high etch selectivity. However, hydroxyl group (—OH) is often found in metal oxide containing layers
Implementation Method 2
by using special treatments such as ALD processes, dopant deposition, and plasma treatments to form M—O—Si groups
Implementation Method 3
plasma treatments to form M—O—Si groups, thereby reducing oxidation capability
Data Source
AI summary
A semiconductor device includes a substrate, a first conductive feature disposed in a top portion of the substrate, an etch stop layer formed of a metal oxide composite and disposed on a top surface of the substrate, and a second conductive feature disposed on and through the etch stop layer and in contact with the first conductive feature. The metal oxide composite contains a metal element represented by M, and a top surface of the etch stop layer includes an M—O—X group, O representing oxygen, and X representing an element other than hydrogen.