Pulsed Plasma Densification of ALD TaN Barrier Films
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Solution Overview
Problem
The challenge in the semiconductor industry is to produce barrier films with lower resistivity and higher density, especially at the 3 nm node and below, where traditional ALD films are non-conformal and PVD films are not effective in reducing RC delay and ensuring device reliability.
Innovation Solution
The solution involves treating ALD tantalum nitride films with a pulsed bias power in a plasma environment, which densifies the films and reduces resistivity, while maintaining conformality and minimizing damage to underlying low-k materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If ALD chambers are used to deposit barrier films, then conformality is improved, but film density and resistivity deteriorate
Solution Approach 1:
The patent applies pulsed bias power during plasma treatment to periodically accelerate ions toward the ALD film surface. This periodic ion bombardment densifies the film by compacting the atomic structure and reducing voids, thereby improving film density while preserving the conformal morphology deposited by ALD.
Solution Approach 2:
The patent changes the physical and chemical parameters of the film through plasma treatment with controlled bias power. By adjusting plasma power, gas composition, and treatment duration, the film's density, resistivity, and atomic structure are modified without compromising the conformal geometry established during ALD deposition.
2Volume of stationary object
If PVD chambers are used to deposit barrier films, then film density is improved, but conformality deteriorates
Solution Approach 1:
The patent merges the advantages of both ALD and PVD processes by combining ALD deposition with pulsed plasma treatment in a single integrated process. The ALD step provides conformal film deposition, while the subsequent plasma treatment step enhances film density, effectively merging the benefits of both techniques into one unified process.
3Volume of stationary object
If barrier film thickness is increased to improve barrier properties, then film density is improved, but RC delay and device reliability deteriorate
Solution Approach 1:
The patent changes the physical parameters of the barrier film through plasma treatment, achieving higher density and lower resistivity within the same film thickness. This allows the use of thinner films that maintain excellent barrier properties while reducing RC delay and improving device reliability.
Solution Approach 2:
The patent replaces the mechanical approach of increasing film thickness to achieve better barrier properties with a plasma-based physical treatment approach. Instead of adding more material, the plasma process modifies the existing film's atomic structure to achieve superior density and electrical properties, thereby reducing RC delay.
4Volume of stationary object
If continuous high power bias is applied during plasma treatment, then film densification is improved, but damage to underlying low-k materials increases
Solution Approach 1:
The patent uses pulsed bias power instead of continuous high power, applying brief bursts of high voltage to accelerate ions intermittently. This periodic application provides sufficient ion energy for film densification while allowing thermal and mechanical relaxation between pulses, preventing cumulative damage to underlying low-k dielectric materials.
Solution Approach 2:
The patent dynamically controls the bias power during plasma treatment by using time-varying pulse widths, frequencies, and duty cycles. This dynamic adjustment optimizes ion bombardment energy for film densification while preventing excessive energy accumulation that could damage sensitive underlying structures.
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 results in barrier films with improved density and reduced resistivity, effectively addressing the challenges of RC delay and device reliability at the 3 nm node and below, while maintaining conformality and minimizing damage to underlying layers.
Implementation Method 1
treating an exposed layer deposited on a substrate and within a feature of the substrate by pulsing a bias power applied to a substrate support supporting the substrate while exposing the layer to a plasma
Implementation Method 2
exposing the layer to a plasma. The plasma can comprise a source gas including one or more of a noble gas, nitrogen (N2), oxygen gas (O2), or water vapor (H2O)
Data Source
AI summary
Methods and apparatus for forming a barrier layer are provided herein. In some embodiments, a method of forming a barrier layer on a substrate includes treating an exposed layer deposited on a substrate and within a feature of the substrate by pulsing a bias power applied to a substrate support supporting the substrate while exposing the layer to a plasma. The exposed layer can be deposited by an atomic layer deposition process, and can be, for example, a tantalum nitride layer. The bias power can be up to 500 watts of RF power at a pulse frequency of about 1 Hz to about 10 kHz. The bias power can be pulsed uniformly or at multiple different levels.