Selective Carbon Deposition for Trench Bottom Opening Precision
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Solution Overview
Problem
Conventional semiconductor processing methods struggle to form openings in bottom surfaces of trenches without breaking through protection layers on top and side surfaces, leading to damage as device sizes shrink and protection layers become thinner.
Innovation Solution
A method involving selective deposition of a carbon-containing layer with a higher thickness on the top surface of trenches than the bottom surface, using a deposition gas mixture of carbon-containing gases like methane and nitrogen, and generating a plasma with controlled electron temperature and pressure to ensure the layer remains intact during etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a uniform protection layer is deposited on trench surfaces, then the top and side surfaces are protected during etching, but the layer must be made thinner as device sizes shrink, causing etching to break through to the top surface and damage devices
Solution Approach 1:
The patent applies local quality by depositing a non-uniform carbon-containing layer with different thicknesses at different locations on the trench surfaces. The layer is thicker on horizontal surfaces (top and bottom) and thinner on vertical sidewalls, providing location-specific protection that prevents etching breakthrough at critical areas while maintaining processability.
Solution Approach 2:
The patent changes the deposition parameters (plasma power, pressure, gas composition) to control the deposition rate and achieve the desired non-uniform thickness distribution. By adjusting these parameters, the process creates a protection layer with varying thickness that optimizes both protection and etching performance.
2Reliability
If a thicker protection layer is used to prevent etching breakthrough, then top surface protection is improved, but the layer becomes too thick to allow precise formation of openings in the bottom surface
Solution Approach 1:
The patent creates local quality differences in the protection layer thickness, making it thicker where protection is needed (top surface) and thinner where precise etching is required (bottom surface). This spatial variation in thickness allows both protection integrity and opening formation precision to be achieved simultaneously.
3Ease of manufacture
If conventional plasma deposition is used, then carbon-containing layer deposition is achieved, but the deposition characteristics do not provide sufficient selectivity between top and bottom surfaces
Solution Approach 1:
The patent modifies deposition parameters including plasma power (50-300 Watts), pressure (1-10 mTorr), and gas composition (CH4/N2 mixtures) to achieve selective deposition. These parameter changes enable the process to deposit more material on top surfaces than bottom surfaces, providing the necessary selectivity while maintaining ease of manufacture through a single-step plasma process.
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 prevents etching through the protection layer on top surfaces, allowing for precise formation of openings in the bottom surfaces while maintaining unbroken coverage on top and side surfaces, reducing damage to semiconductor devices.
Implementation Method 1
depositing a carbon-containing layer on the top surface and the bottom surface of the substrate trenches
Implementation Method 2
flowing a deposition gas into a plasma excitation region of the reaction chamber
Data Source
AI summary
Semiconductor processing methods are described that include providing a substrate to a reaction chamber, where the substrate includes substrate trenches that have a top surface and a bottom surface. A deposition gas that includes a carbon-containing gas and a nitrogen-containing gas flows into a plasma excitation region of the reaction chamber. A deposition plasma having an electron temperature less than or about 4 eV is generated from the deposition gas. The methods further include depositing a carbon-containing layer on the top surface and the bottom surface of the substrate trenches, where the as-deposited carbon-containing layer has a top surface-to-bottom surface thickness ratio of greater than or about 3:1. Also described are semiconductor structures that include an as-deposited carbon-containing layer on the top and bottom surface of at least a first and second trench, where the carbon-containing layer has a top surface-to-bottom surface thickness ratio of greater than or about 3:1.