Stress Engineering for Self-Aligned Multi-Patterning Line Roughness
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Solution Overview
Problem
Conventional self-aligned multi-patterning (SAMP) techniques face challenges in achieving smoothness and uniformity for feature sizes below 10 nm, leading to roughness and variations in patterned lines that degrade microelectronic workpiece performance.
Innovation Solution
Applying high stress films on both sides of the substrate to introduce biaxial stress, which helps straighten pattern lines and reduce line roughness by controlling the deposition and etch processes, thereby improving the physical performance and process results of microelectronic workpieces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional SAMP techniques are used to achieve reduced feature sizes below 10 nm, then pitch reduction and small feature sizes are achieved, but line roughness and pattern uniformity deteriorate
Solution Approach 1:
The patent applies preliminary stress engineering to the substrate before performing the SAMP process. By pre-stressing the substrate in the radial direction, the pattern lines are forced to grow straighter during the deposition and etching processes, preventing roughness from developing in the first place. This preliminary action addresses the root cause of line roughness at sub-10 nm nodes.
Solution Approach 2:
The patent changes the mechanical parameter of the substrate by applying controlled stress in the radial direction. This stress parameter modification affects the physical state of the substrate during patterning, causing pattern lines to straighten and reducing line roughness. The stress level and direction are carefully controlled to optimize the effect.
2Productivity
If conventional SAMP techniques are used for sub-10 nm features, then pitch reduction is achieved, but pattern uniformity and process control become extremely difficult
Solution Approach 1:
The substrate is pre-stressed in the radial direction before patterning begins. This preliminary stress application simplifies subsequent process control by providing a mechanical framework that naturally guides pattern line formation, reducing the complexity of controlling deposition and etching processes at sub-10 nm dimensions.
3Reliability
If feature sizes are reduced below 10 nm to improve device performance, then device performance improves, but roughness variations increase and degrade final features
Solution Approach 1:
By applying radial stress to the substrate before patterning, the patent creates a mechanical environment that promotes straighter pattern line growth. This preliminary action compensates for the inherent roughness that would otherwise develop at sub-10 nm feature sizes, allowing high device performance to be achieved without the degrading effect of roughness variations.
Solution Approach 2:
The patent modifies the mechanical stress parameter of the substrate to counteract the surface tension and other forces that cause line roughness at small dimensions. This parameter change enables better roughness control while maintaining the small feature sizes needed for high device performance.
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 use of high stress films achieves line width roughness (LWR) of less than 1.6 and aspect ratios greater than 5.0, significantly improving the quality of patterned structures by reducing roughness and variations, especially for feature sizes below 10 nm.
Implementation Method 1
depositing a high stress film on the frontside and the backside of the substrate where the high stress film provides biaxial stress to the substrate due to the deposition process for the high stress film
Data Source
AI summary
Embodiments are disclosed for processing microelectronic workpieces to apply stress engineering to self-aligned multi-patterning (SAMP) processes. The disclosed processing methods utilize stress in a substrate in a SAMP process to improve resulting pattern parameters. Initially, a high stress film is deposited on the frontside and the backside of the substrate, and the high stress film provides biaxial stress to the substrate due to the deposition process for the high stress film. Next, a SAMP process is performed to form spacers in a spacer pattern. This spacer pattern is then transferred to underlying layers to form a patterned structure. The high stress film provides axial stress in at least one direction along a portion of the patterned structure during the pattern transfer thereby improving resulting pattern formation.