Carbon Gapfill Layer Sequencing for Void-Free High-Aspect Trenches
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Solution Overview
Problem
Conventional gapfill techniques struggle with voids and seams in high aspect ratio structures due to premature overgrowth, especially in semiconductor devices with varying gap widths and aspect ratios, making void-free and seam-free filling increasingly difficult as device geometries shrink and thermal budgets are reduced.
Innovation Solution
A multi-step carbon gapfill process involving a dep-etch operation with hydrocarbon precursor and etchant gases, followed by co-flowed precursor and etchant gases to form multiple carbon layers, optimizing plasma conditions for uniform deposition and etching to fill trenches effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional gapfill techniques are used to fill high aspect ratio structures, then the gapfill material can be deposited into the structures, but voids and seams form due to premature overgrowth at the top of the gap
Solution Approach 1:
The gapfill process is divided into multiple sequential steps: initial deposition step, first etch step, second deposition step, and second etch step. Each step targets specific regions of the high aspect ratio structure, with the etch steps removing overgrown material at the top while preserving material at the bottom, thereby eliminating voids and seams that would form with conventional single-step filling
Solution Approach 2:
The patent employs periodic alternation between deposition and etching operations. The etch steps are performed at specific intervals during the filling process to periodically remove overgrown material from the top of the gap, preventing premature closure and ensuring complete filling without voids or seams
2Productivity
If device geometries are shrunk to advance technology nodes, then device density and performance are improved, but gapfill becomes increasingly difficult due to higher aspect ratios and varying gap widths
Solution Approach 1:
The patent employs dynamic adjustment of process parameters including gas flow rates, pressure, and temperature throughout the multi-step filling process. The etch selectivity and deposition rates are dynamically controlled to adapt to the varying geometries of different gaps on the same substrate, enabling effective filling of high aspect ratio structures while maintaining processability
Solution Approach 2:
The patent utilizes changes in physical and chemical parameters such as plasma power, gas composition, and process temperature to control the deposition and etching rates. By adjusting these parameters between and during steps, the process accommodates varying gap widths and aspect ratios, reducing filling difficulty despite advanced device geometries
3Stability of the object's composition
If thermal budgets are reduced to protect underlying structures, then structure integrity is maintained, but gapfill material deposition becomes increasingly difficult
Solution Approach 1:
The patent replaces thermal-driven deposition mechanisms with plasma-enhanced chemical vapor deposition (PECVD). This substitution allows gapfill material to be deposited at lower temperatures through plasma activation, maintaining structure integrity while enabling effective gapfilling in reduced thermal budget processes
Solution Approach 2:
The patent employs composite processing approaches combining deposition and etching operations with different plasma chemistries. This composite process enables material filling at low temperatures while the selective etching steps compensate for reduced deposition efficiency, maintaining both structure integrity and filling effectiveness
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 ensures complete filling of high aspect ratio trenches with minimal voids and seams, enhancing semiconductor device performance by maintaining gap integrity and reducing defects.
Implementation Method 1
forming a layer in the at least one feature by flowing a first hydrocarbon precursor gas into the processing volume and etching the layer by flowing a first etchant gas into the processing volume
Implementation Method 2
etching the layer by flowing a first etchant gas into the processing volume
Implementation Method 3
forming a second gapfill layer in the at least one feature by co-flowing a second hydrocarbon precursor gas and a second etchant gas into the processing volume
Data Source
AI summary
A method for forming a gapfill layer, comprising: positioning a substrate in a processing volume of a processing chamber, forming a plurality of first gapfill layers in at least one feature disposed on the substrate, comprising, for each first gapfill layer included in the plurality of first gapfill layers: forming a layer in the at least one feature by flowing a first hydrocarbon precursor gas into the processing volume and etching the layer by flowing a first etchant gas into the processing volume, and forming a second gapfill layer in the at least one feature by co-flowing a second hydrocarbon precursor gas and a second etchant gas into the processing volume.