Integrated Etch Clean for Dielectric Recessed Features
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Solution Overview
Problem
The challenge in semiconductor fabrication is to etch recessed features in dielectric material without damaging the underlying semiconductor material, especially as device dimensions shrink, as conventional etching processes using high ion energies result in significant damage due to excessive ion bombardment.
Innovation Solution
A method involving two etching operations: a first etching operation using a capacitively coupled plasma to etch the dielectric material to a specific depth, stopping before ions penetrate through, followed by a second etching operation using an inductively coupled plasma for atomic layer etching to finish the recessed feature without high ion energies, thereby minimizing damage to the semiconductor material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional etching processes use high ion energies to etch dielectric material, then etching speed and depth are improved, but damage to the underlying semiconductor material increases significantly
Solution Approach 1:
The etching process is divided into two distinct stages: a first etching operation using capacitively coupled plasma to etch the dielectric material to a controlled depth, and a second etching operation using inductively coupled plasma to complete the etching. This segmentation allows the high ion energy process to be limited to only the portion needed for productivity, while the final delicate work is performed with low ion energy to prevent damage.
Solution Approach 2:
The patent changes the plasma generation parameters between the two etching operations. The first operation uses capacitively coupled plasma with higher ion energies for efficient material removal, while the second operation switches to inductively coupled plasma with lower ion energies and more gentle conditions to finish etching without damaging the semiconductor material underneath.
2Object-affected harmful factors
If the first etching operation is stopped before complete penetration, then damage to semiconductor material is prevented, but additional processing steps are required
Solution Approach 1:
The etching process is divided into two distinct stages: a first etching operation using capacitively coupled plasma to etch the dielectric material to a controlled depth, and a second etching operation using inductively coupled plasma to complete the etching. This segmentation allows the high ion energy process to be limited to only the portion needed for productivity, while the final delicate work is performed with low ion energy to prevent damage.
Solution Approach 2:
The patent introduces an intermediary approach by using two different plasma coupling methods in sequence. The capacitively coupled plasma acts as the primary etching tool, and the inductively coupled plasma serves as the gentle finishing tool. This intermediary second operation with different plasma characteristics enables complete etching while protecting the semiconductor material.
3Productivity
If device dimensions are reduced to create narrower features, then device density is improved, but etching selectivity and damage control become increasingly difficult
Solution Approach 1:
The patent changes the plasma generation parameters between the two etching operations. The first operation uses capacitively coupled plasma with higher ion energies for efficient material removal, while the second operation switches to inductively coupled plasma with lower ion energies and more gentle conditions to finish etching without damaging the semiconductor material.
Solution Approach 2:
The patent applies different plasma conditions to different stages of the etching process. The first etching operation uses conditions optimized for removing dielectric material efficiently, while the second operation uses conditions optimized for precision and minimal damage. This local optimization of process conditions at different stages enables successful etching of narrow features at high aspect ratios.
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 effectively prevents damage to the underlying semiconductor material by controlling ion penetration and energy, allowing for precise and damage-free etching of narrow features at high aspect ratios, even in advanced technology nodes.
Implementation Method 1
performing a first etching operation in the first reaction chamber to etch the recessed feature in the dielectric material to a first depth, the first etching operation including exposing the substrate to a first plasma including a first set of ions with a mean free path in the dielectric material, the first plasma being a capacitively coupled plasma
Implementation Method 2
performing a second etching operation in the second reaction chamber to etch the recessed feature to a final depth, where the second etching operation is an atomic layer etching operation that includes exposing the substrate to a second plasma, the second plasma being an inductively coupled plasma
Implementation Method 3
exposing the substrate to an etching reactant and allowing the etching reactant to adsorb onto the substrate surface
Implementation Method 4
removing non-adsorbed etching reactant from the second reaction chamber
Implementation Method 5
exposing the substrate to the second plasma to drive a reaction between a species in the adsorbed reactant and dielectric material in the recessed feature to thereby remove a portion of the dielectric material
Data Source
AI summary
The embodiments herein relate to methods and apparatus for etching a recessed feature in dielectric material. In various embodiments, a recessed feature is formed in two etching operations. The first etching operation partially etches the features and may take place in a reactor configured to produce a capacitively coupled plasma. The first etching operation may end before the underlying semiconductor material experiences substantial damage due to penetration of ions through the dielectric atop the semiconductor material. The second etching operation may take place in a reactor configured to produce an inductively coupled plasma. Both the first and second etching operations may themselves be multi-step, cyclic processes.