Ruthenium Recess Filling with Cyclic Deposition and Ozone Etching
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Solution Overview
Problem
Existing methods face challenges in embedding ruthenium in recesses without generating voids or seams, which increase resistance in wires and contacts on a substrate.
Innovation Solution
A film-forming method involving the sequential steps of supplying a ruthenium raw material gas, followed by ozone gas to etch excess ruthenium, and annealing, repeated in a controlled manner to form a low-resistance ruthenium layer in a bottom-up fashion, thereby avoiding voids and seams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ruthenium is embedded in recesses to form low-resistance wires and contacts, then electrical conductivity is improved, but voids and seams are generated on side walls leading to increased resistance
Solution Approach 1:
The continuous ruthenium film formation process is segmented into alternating deposition and etching cycles. During each cycle, ruthenium is deposited on the substrate surface and then selectively etched away from the side walls using ozone gas, while the bottom of the recess is protected. This segmentation allows precise control over where ruthenium remains, eliminating voids and seams on side walls while maintaining continuous conductive paths at the bottom.
Solution Approach 2:
The patent employs periodic alternation between ruthenium deposition and ozone etching steps. The deposition step builds up ruthenium material, and the subsequent ozone etching step selectively removes ruthenium from exposed side wall surfaces. This periodic action is repeated multiple times to progressively build a uniform ruthenium film that completely fills the recess without forming side wall voids, ensuring both electrical conductivity and film uniformity.
2Manufacturing precision
If etching is performed to remove ruthenium pieces from side walls, then film uniformity is improved, but excessive etching may remove ruthenium from the bottom of the recess
Solution Approach 1:
A protective layer is deposited on the bottom of the recess before the alternating deposition and etching cycles begin. This protective layer remains on the bottom surface throughout the process, preventing ozone gas from etching the ruthenium at the bottom of the recess. The protective layer is removed only after the ruthenium film formation is complete, ensuring that the bottom conductive path is never compromised while side wall uniformity is achieved.
Solution Approach 2:
The protective layer acts as an intermediary barrier between the ozone etching gas and the ruthenium film at the bottom of the recess. It allows the etching process to selectively remove ruthenium from side walls while protecting the bottom surface. This intermediary layer enables precise spatial control of the etching action, maintaining film uniformity without sacrificing electrical conductivity at the critical bottom contact points.
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 enables the formation of a low-resistance ruthenium layer without voids or seams, improving the etching resistance and throughput by controlling the etching amount and grain size of the ruthenium layer.
Implementation Method 1
supplying a gas containing a ruthenium raw material gas into the processing container to form a ruthenium layer
Implementation Method 2
supplying a gas containing an ozone gas into the processing container to etch the ruthenium layer
Implementation Method 3
a step of annealing the ruthenium layer
Data Source
AI summary
A film-forming method of embedding ruthenium in a substrate having a recess includes: (a) providing the substrate in a processing container; (b) supplying a gas containing a ruthenium raw material gas into the processing container to form a ruthenium layer; (c) annealing the ruthenium layer; and (d) supplying a gas containing an ozone gas into the processing container to etch the ruthenium layer, wherein (b), (c), and (d) are repeatedly executed in this order.