Plasma Nitrided Polysilicon Oxidation Barrier
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Solution Overview
Problem
Conventional semiconductor manufacturing processes face challenges in forming uniformly ultra-thin nitrided regions due to 'bird's beak' formation at the interface between polysilicon and CVD oxide films, which is exacerbated by high-temperature heat treatments, making it difficult to control and stabilize the performance of semiconductor devices.
Innovation Solution
A method using plasma nitriding treatment with a microwave-generated plasma, employing a planar antenna with slots, to form a nitrided region that functions as an oxidation barrier, allowing for the suppression of 'bird's beak' formation at lower temperatures, thereby controlling the nitrided region's thickness and improving device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature heat treatment is performed to form a nitride layer by ammonia gas atmosphere, then the bird's beak problem can be suppressed, but the thermal oxidation causes the end portion of the interface to become thick and affects the entire manufacturing process
Solution Approach 1:
The patent changes the fundamental parameter of the nitriding process from thermal (high-temperature) to plasma-based (lower temperature). By using plasma nitriding instead of conventional thermal nitriding, the process can form a nitrided region at lower temperatures while still achieving effective bird's beak suppression, thus resolving the contradiction between reliability improvement and temperature control.
Solution Approach 2:
The patent substitutes the thermal field (heat treatment) with a plasma field (microwave-generated plasma). This replacement allows the nitriding process to occur at lower temperatures while maintaining or improving the effectiveness of bird's beak suppression, thereby resolving the technical contradiction between achieving reliable suppression and avoiding excessive thermal oxidation.
2Quantity of substance
If conventional thermal oxidation is performed to form oxide film on sidewalls, then the oxide film can be formed, but the oxidation continues to proceed into both end portions of the polysilicon layer causing bird's beak formation
Solution Approach 1:
The patent applies preliminary nitriding treatment to form a nitrided region on the polysilicon layer before performing thermal oxidation. This pre-formed nitrided region acts as a barrier that prevents oxygen from penetrating into the polysilicon layer during subsequent oxidation processes, thereby eliminating bird's beak formation while still allowing oxide film formation on sidewalls through controlled oxidation.
3Quantity of substance
If the nitrided region is formed by high-temperature heat treatment, then the nitride layer can be formed, but it is hard to control the uniformly ultra-thin nitride layer in fine accuracy
Solution Approach 1:
The patent changes the process mechanism from thermal diffusion (temperature-driven) to plasma-enhanced chemical reaction. This parameter change enables precise control of nitride layer thickness and uniformity at lower temperatures, as the plasma process can be more precisely controlled in terms of reaction time, power, and gas flow, thereby achieving fine accuracy in ultra-thin nitride layer formation.
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 plasma nitriding treatment effectively forms a uniform, high-nitrogen-concentration nitrided region that acts as an oxidation barrier, preventing 'bird's beak' formation and enhancing the stability and performance of semiconductor devices by reducing oxygen diffusion and thermal oxidation effects.
Implementation Method 1
forming a nitrided region on a layer having silicon on a target substrate to be processed by using a plasma which is generated by introducing a microwave into a processing chamber
Implementation Method 2
introducing a microwave into a processing chamber by means of a planar antenna provided with a plurality of slots
Implementation Method 3
forming an oxide film on the layer having silicon on the target substrate to be processed by a heat treatment while the nitrided region functions as an oxidation barrier
Data Source
AI summary
A nitrided region is formed on a surface of a polysilicon layer by a nitriding treatment wherein plasma of a processing gas is generated by introducing microwaves into a processing chamber by a planar antenna having a plurality of slots. Then, a CVD oxide film or the like is formed on the nitrided region and after patterning the polysilicon layer and the like after the prescribed shape, and then, a thermal oxide film is formed by thermal oxidation on exposed side walls and the like of the polysilicon layer by having the nitrided region as an oxidation barrier layer. Thus, generation of bird's beak can be suppressed in the process at a temperature lower than the temperature in a conventional process.