Gradient Oxidation Seed Layer Removal for Bottom-Up Gap Fill
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Solution Overview
Problem
Conventional methods for gap fill in semiconductor devices face challenges with critical dimension control, process uniformity, and defects due to incomplete filling of gaps and residual seed layer removal, leading to increased fabrication costs and defects.
Innovation Solution
A method and apparatus using gradient oxidation and etch processes in an inductively coupled plasma reactor to selectively oxidize and remove excess metal seed layer from the field region while preserving a seed layer at the bottom of features, followed by a metal gap-fill process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to remove the seed layer from the sides of the gap, then the seed layer is removed from the sides, but the seed layer at the bottom of the gap is also removed unintentionally
Solution Approach 1:
The oxidation process creates different oxidation states of the seed layer at different locations - fully oxidized at the top surface and partially oxidized at the bottom of the gap. This local differentiation allows selective removal of the top seed layer while preserving the bottom seed layer, resolving the contradiction between complete seed layer removal and bottom seed layer preservation
2Manufacturing precision
If multiple incremental processes are used to control critical dimensions, then critical dimension control is improved, but fabrication time and defect risk increase
Solution Approach 1:
The patent combines the oxidation process and etch back process into a single integrated process sequence within the same reactor chamber. This merging of processes achieves precise critical dimension control through in-situ selective oxidation and removal, while eliminating the need for multiple separate process steps, thereby improving both precision and productivity
3Manufacturing precision
If the liner and seed layer are prepared to grow metal gap-fill, then the gap fill material can be deposited, but the residual seed layer on the sides causes the fill material to close off the gap prematurely
Solution Approach 1:
The oxidation and etch back processes are performed as preliminary steps before the metal gap-fill deposition. This preliminary removal of the side seed layer prevents the gap-fill material from adhering to the sidewalls, ensuring that the gap fills uniformly from the bottom up without premature closure, thus achieving the desired gap fill shape and uniformity
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
Achieves a seam-free bottom-up gap fill with high selectivity and throughput, reducing fabrication time and defects by maintaining a quality seed layer at the bottom of features.
Implementation Method 1
A gradient oxidation process is performed in an inductively coupled plasma (ICP) reactor to oxidize exposed portions of the metal seed layer to form a metal oxide, wherein the gradient oxidation process preferentially oxidizes a field region of the substrate over the bottom surface of the features
Implementation Method 2
An etch back process is preformed in the same ICP reactor to remove or reduce the oxidized portion of the seed layer
Data Source
AI summary
A method and apparatus for a gap-fill in semiconductor devices are provided. The method includes forming a metal seed layer on an exposed surface of the substrate, wherein the substrate has features in the form of trenches or vias formed in a top surface of the substrate, the features having sidewalls and a bottom surface extending between the sidewalls. A gradient oxidation process is performed in a first process chamber to oxidize exposed portions of the metal seed layer to form a metal oxide, wherein the gradient oxidation process preferentially oxidizes a field region of the substrate over the bottom surface of the features. An etch back process is performed in the first process chamber removes or reduces the oxidized portion of the seed layer. A metal gap-fill process fills or partially fills the features with a gap fill material.