Plasma Oxidation for Sharp Junctions and Selective Metal Protection
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Solution Overview
Problem
Conventional oxidation processes for semiconductor devices face challenges such as diffusion of junction definitions at high temperatures, contamination issues in plasma processes, and inability to achieve selective sidewall oxidation in the presence of certain metal alloys, leading to defects like bird's beak and reduced device performance.
Innovation Solution
The method involves forming an oxide layer using a plasma process in a decoupled or remote plasma oxidation chamber with a gas mixture containing hydrogen, oxygen, and nitridizing or supplemental oxidizing gases, allowing for pure or selective oxidation of semiconductor structures at temperatures below 700 degrees Celsius, thereby avoiding unwanted oxidation of metal-containing layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thermal oxidation processes are used to form oxide layers, then oxide formation is achieved, but junction definitions become diffused at high temperatures above 700 degrees Celsius
Solution Approach 1:
The patent changes the oxidation mechanism from thermal diffusion to plasma-enhanced chemical reaction, enabling oxide formation at lower temperatures (below 700°C) while maintaining sharp junction definitions. The plasma process uses reactive species to oxidize the semiconductor surface without requiring high thermal energy that would cause diffusion.
Solution Approach 2:
The patent replaces the thermal field (heat-driven oxidation) with a plasma field (reactive species-driven oxidation). This substitution eliminates the need for high temperatures while achieving complete oxide formation, thereby preserving junction sharpness.
2Manufacturing precision
If plasma oxidation processes are performed at high chamber pressure, then oxide layer formation is achieved, but contaminants accumulate in the gate oxide layer causing defects
Solution Approach 1:
The patent optimizes the chamber pressure to an intermediate range that balances oxide formation efficiency with contaminant exclusion. This parameter optimization ensures sufficient reactive species flux for complete oxidation while maintaining low enough pressure to prevent contaminant accumulation.
3Manufacturing precision
If plasma oxidation processes are performed at low chamber pressure, then contaminant accumulation is reduced, but increased plasma ion energy causes ion bombardment damage and diffusion problems
Solution Approach 1:
The patent carefully controls chamber pressure to an optimal range that limits ion energy sufficient to prevent bombardment damage while maintaining enough reactive species flux to achieve complete and selective oxidation. This parameter optimization resolves the trade-off between ion damage and oxidation efficiency.
4Manufacturing precision
If conventional oxidation processes are used, then oxide layer formation is achieved, but bird's beak defects occur due to oxide layer diffusion into adjacent layers
Solution Approach 1:
The patent replaces thermal oxidation with plasma-enhanced oxidation, which occurs at lower temperatures and through a different mechanism that prevents lateral diffusion into adjacent layers. This substitution eliminates the bird's beak defect while achieving complete oxide coverage on the intended surfaces.
Solution Approach 2:
The patent achieves selective oxidation where oxide forms only on non-metal containing layers while metal-containing layers remain protected. This local selectivity prevents oxide intrusion into adjacent regions, eliminating the bird's beak profile defect.
5Manufacturing precision
If selective sidewall oxidation is attempted in the presence of titanium nitride metal alloy, then oxidation of non-metal layers is desired, but the oxidation process undesirably oxidizes the TiN metal layer
Solution Approach 1:
The patent achieves selective oxidation by exploiting differences in material reactivity to plasma species. Non-metal containing layers oxidize preferentially while metal-containing layers like TiN remain protected, enabling precise spatial control over where oxidation occurs.
Solution Approach 2:
The patent modifies process parameters including gas composition, pressure, and power to create a plasma environment that provides selective oxidation. These parameter changes enable differentiation between metal and non-metal layer reactivity, achieving the desired selectivity.
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 enables the formation of high-quality oxide layers with reduced defects and bird's beak, while maintaining sharp junction definitions and preserving the integrity of metal-containing layers, improving the performance of semiconductor devices.
Implementation Method 1
forming a plasma in the process chamber from a process gas to form an oxide layer on the substrate
Implementation Method 2
forming a plasma in the process chamber from a process gas
Data Source
AI summary
Methods of fabricating an oxide layer on a semiconductor substrate are provided herein. The oxide layer may be formed over an entire structure disposed on the substrate, or selectively formed on a non-metal containing layer with little or no oxidation of an exposed metal-containing layer. The methods disclosed herein may be performed in a variety of process chambers, including but not limited to decoupled plasma oxidation chambers, rapid and/or remote plasma oxidation chambers, and/or plasma immersion ion implantation chambers. In some embodiments, a method may include providing a substrate comprising a metal-containing layer and non-metal containing layer; and forming an oxide layer on an exposed surface of the non-metal containing layer by exposing the substrate to a plasma formed from a process gas comprising a hydrogen-containing gas, an oxygen-containing gas, and at least one of a supplemental oxygen-containing gas or a nitrogen-containing gas.