Graded Boron-Silicon Films for Etch Resistance and Selectivity
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Solution Overview
Problem
Existing semiconductor processing methods struggle to achieve precise control over boron concentration gradients in boron-and-silicon-containing layers, leading to challenges in etch resistance and selectivity, which affect the formation of high-aspect ratio openings in semiconductor devices.
Innovation Solution
The method involves flowing silicon-containing and boron-containing precursors into a semiconductor processing chamber, with a continuously increasing boron-to-silicon atomic ratio in the deposited layer, achieved by increasing the flow rate of the boron-containing precursor while maintaining a constant boron-to-hydrogen flow rate ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a uniform boron-to-silicon ratio is used in the deposited layer, then the deposition process is simple and fast, but the etch resistance and etch selectivity cannot be simultaneously optimized
Solution Approach 1:
The patent applies local quality by creating a boron-and-silicon-containing layer with a non-uniform boron-to-silicon atomic ratio that varies through the thickness of the layer. The ratio is highest at the interface with the etch stop layer and lowest at the opposite surface, providing locally optimized properties: high etch resistance near the etch stop layer and high etch selectivity at the outer surface.
Solution Approach 2:
The patent implements parameter changes by continuously varying the boron-to-silicon atomic ratio as a function of depth through the layer. This is achieved by dynamically adjusting precursor flow rates during deposition, transforming a constant-parameter deposition into a variable-parameter process that optimizes both etch resistance and selectivity.
2Productivity
If high-aspect ratio openings are formed, then device density and integration are improved, but control over etch endpoint and opening precision becomes more difficult
Solution Approach 1:
The patent applies local quality by creating distinct compositional regions within the hardmask layer: a high-boron region near the etch stop layer provides enhanced etch resistance for maintaining opening precision during deep etching, while a low-boron region at the outer surface provides high etch selectivity for precise endpoint control, enabling both high-aspect ratio formation and precision control.
Solution Approach 2:
The patent creates a composite hardmask layer with spatially varying composition rather than a homogeneous material. This composite structure combines regions of high boron content (for etch resistance) and low boron content (for etch selectivity), enabling the layer to perform multiple functions simultaneously in high-aspect ratio opening processes.
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 a boron-and-silicon-containing layer with enhanced etch resistance at one end and improved etch selectivity at the other end, enabling precise formation of high-aspect ratio openings in semiconductor devices such as DRAM and 3D NAND memory.
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
Embodiments of the present technology include semiconductor processing methods to make boron-and-silicon-containing layers that have a changing atomic ratio of boron-to-silicon. The methods may include 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 of the semiconductor processing chamber. The boron-containing precursor and the H2 may be flowed at a boron-to-hydrogen flow rate ratio. The flow rate of the boron-containing precursor and the H2 may be increased while the boron-to-hydrogen flow rate ratio remains constant during the flow rate increase. The boron-and-silicon-containing layer may be deposited on a substrate, and may be characterized by a continuously 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 furthest from the substrate.