Graded Boron-Silicon Film for Hardmask Etch Selectivity
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Solution Overview
Problem
Existing semiconductor processing methods face challenges in producing boron-and-silicon-containing layers that provide both high etch resistance and selectivity, leading to issues with precise hardmask openings and endpoint definition in high-aspect ratio structures.
Innovation Solution
A method and system that form a boron-and-silicon-containing layer with a continuously varying boron-to-silicon atomic ratio, where the proximal end has a lower ratio for increased etch selectivity and the distal end has a higher ratio for enhanced etch resistance, achieved by controlling the flow rates of boron- and silicon-containing precursors during deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a boron-and-silicon-containing layer is formed with high boron concentration to increase etch resistance, then etch resistance is improved, but etch selectivity compared to the etch stop layer deteriorates
Solution Approach 1:
The patent applies local quality by creating a boron-and-silicon-containing layer with spatially varying boron concentration. The layer has higher boron concentration (higher atomic ratio of boron to silicon) at the distal end for etch resistance, and lower boron concentration (lower atomic ratio) at the proximal end for etch selectivity. This gradient structure allows different regions of the same layer to serve different functional requirements simultaneously.
Solution Approach 2:
The patent employs parameter changes by continuously varying the boron-to-silicon atomic ratio throughout the thickness of the layer. The deposition process dynamically adjusts precursor flow rates to achieve a gradient where the atomic ratio transitions from approximately 0.2-0.5 at the proximal end to 0.8-1.5 at the distal end, thereby optimizing both etch selectivity and etch resistance in different regions.
2Ease of manufacture
If a uniform boron-to-silicon ratio is used throughout the layer, then manufacturing simplicity is maintained, but both etch resistance and etch selectivity cannot be simultaneously optimized
Solution Approach 1:
The patent applies dynamics by making the deposition process dynamic rather than static. The precursor flow rates are continuously adjusted during deposition to create the desired concentration gradient. The boron-containing precursor flow rate varies relative to the silicon-containing precursor flow rate, enabling the atomic ratio to change continuously through the layer thickness while maintaining process control.
Solution Approach 2:
The patent applies preliminary action by establishing the concentration gradient during the deposition process itself, rather than attempting to create it afterward. The gradient is built into the layer as it is being formed by controlling the relative flow rates of precursors, ensuring the desired property distribution is achieved from the outset.
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 solution enables precise hardmask openings with reduced overetching, improving the definition and smoothness of high-aspect ratio features in semiconductor devices by balancing etch resistance and selectivity.
Implementation Method 1
flowing a silicon-containing precursor into a substrate processing region of a semiconductor processing chamber, and also flowing a boron-containing precursor and molecular hydrogen (H2) into the substrate processing region
Data Source
AI summary
Exemplary semiconductor processing methods may include flowing a silicon-containing precursor into a substrate processing region of a semiconductor processing chamber. The methods may include flowing a boron-containing precursor into the substrate processing region of the semiconductor processing chamber. The methods may include depositing a boron-and-silicon-containing layer on a substrate in the substrate processing region of the semiconductor processing chamber. The boron-and-silicon-containing layer may be characterized by an increasing ratio of boron-to-silicon from a first surface in contact with the substrate to a second surface of the boron-and-silicon-containing layer opposite the first surface. A flow rate of the boron-containing precursor may be increased during the deposition of the boron-and-silicon-containing layer.