Plasma Oxide Densification for Void-Free Gap Fill
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in microelectronic device fabrication lies in effectively filling narrow gaps and trenches with dielectric material without clogging, which often results in voids or seams due to the shrinkage of dielectric materials during hardening, and the risk of oxidation damaging underlying layers, especially in gate all around (GAA) transistors.
Innovation Solution
A method involving the formation of an oxide layer with an initial wet etch rate, followed by a first plasma treatment using a DC bias and a second plasma treatment without bias, utilizing multiple RF sources to densify the oxide layer at temperatures below 600°C, ensuring gap fill deposition and film densification while preventing material shrinkage and oxidation damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If highly flowable precursor materials are used to fill narrow gaps, then gap filling is improved, but the deposited material shrinks during hardening leaving cracks and spaces
Solution Approach 1:
The patent applies plasma treatment to change the physical and chemical parameters of the deposited oxide layer. The plasma process modifies the film's density, reduces porosity, and improves compositional uniformity without requiring high-temperature processing that would damage underlying layers. This resolves the contradiction by transforming the film properties after deposition to achieve both good gap filling and high film density.
Solution Approach 2:
The patent utilizes plasma phase transitions to densify the oxide layer. The plasma treatment induces structural changes in the deposited material, transitioning it from a porous, low-density state to a denser, more uniform state. This phase transition approach allows the material to maintain its flowable deposition characteristics while achieving high density after treatment.
2Stability of the object's composition
If high temperature exposure is used to harden dielectric material, then film densification is improved, but underlying layers are damaged through oxidation
Solution Approach 1:
The patent replaces the thermal mechanism (high-temperature heating) with a plasma-based mechanism for film densification. Instead of using thermal energy to densify the oxide layer, the patent employs plasma energy, which can achieve similar or better densification effects at much lower substrate temperatures. This substitution eliminates the oxidation damage to underlying layers while achieving the desired film density.
Solution Approach 2:
The plasma treatment creates an inert or controlled chemical environment during the densification process. The plasma chemistry can be tailored to prevent oxidation reactions, allowing the oxide layer to be densified without exposing underlying sensitive layers to oxidizing conditions. This is achieved through careful selection of plasma gases and process parameters.
3Ease of manufacture
If spin-on dielectric materials are used to fill gaps, then ease of deposition is improved, but thermal budget constraints limit process flow options
Solution Approach 1:
The patent segments the gap-filling process into distinct stages: first, deposition of the oxide layer using spin-on or other low-temperature methods; second, separate plasma treatment to densify the film. This segmentation allows each step to be optimized independently, maintaining the ease of initial deposition while adding a subsequent step to achieve high film density without thermal budget constraints.
Solution Approach 2:
The patent performs the deposition action first using simple, low-cost methods, then applies plasma treatment as a preliminary or post-processing step to achieve the desired film properties. This preliminary action approach allows the use of easy deposition methods while still achieving high-quality dense films through the subsequent plasma modification.
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 reduces the wet etch rate of the oxide layer by half, achieving seamless gap filling and preventing structural damage, thereby enhancing the integrity of microelectronic devices like GAA transistors.
Implementation Method 1
exposing the oxide layer to a first plasma treatment to produce a treated oxide layer... generating a first plasma by a first RF source... exposing the treated oxide layer to a second plasma treatment to produce a densified oxide layer... generating a second plasma by a top RF source and a side RF source
Data Source
AI summary
Embodiments of the present disclosure generally relate to methods for gap fill deposition and film densification on microelectronic devices. The method includes forming an oxide layer containing silicon oxide and having an initial wet etch rate (WER) over features disposed on the substrate, and exposing the oxide layer to a first plasma treatment to produce a treated oxide layer. The first plasma treatment includes generating a first plasma and directing the first plasma to the oxide layer. The method also includes exposing the treated oxide layer to a second plasma treatment to produce a densified oxide layer. The second plasma treatment includes generating a second plasma and directing the second plasma to the treated oxide layer. The densified oxide layer has a final WER of less than one-half of the initial WER.