Bottle-Shaped Gate Structure via Ar/O2 Plasma Treatment
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Solution Overview
Problem
The semiconductor industry faces challenges in achieving desired critical dimensions for integrated circuits due to unwanted re-entrant profiles in gate structures, which can lead to electrical shorts and complexity in manufacturing, particularly at submicron technology nodes like 65 nm and smaller.
Innovation Solution
A method involving an Ar/O2 treatment is applied before the final overetching of the gate structure to create a bottle-shaped gate structure, which includes flowing O2 and Ar gases along with specific power ranges, and can be performed ex-situ or in-situ, to reduce the height of the barrier diffusion oxide and prevent electrical shorts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching processes are used to form gate structures, then manufacturing simplicity is maintained, but re-entrant profiles form causing electrical shorts and critical dimension failures
Solution Approach 1:
An Ar/O2 plasma treatment is performed before the final overetching step to modify the oxide layer surface. This preliminary action reduces the oxide height and creates a favorable surface condition that prevents re-entrant profile formation during subsequent etching, thereby maintaining critical dimension accuracy without adding significant process complexity
Solution Approach 2:
The patent introduces specific process parameters including Ar gas flow rate (0-1000 SCCM), O2 gas flow rate (0-200 SCCM), source power (10-1000 Watts), and bias power (10-300 Watts) to control the plasma treatment. By optimizing these parameters, the oxide layer is selectively modified to prevent re-entrant profiles while maintaining manufacturing process simplicity
2Manufacturing precision
If the gate structure is etched to achieve desired critical dimensions, then manufacturing precision improves, but re-entrant profiles cause electrical shorts between conductive layers
Solution Approach 1:
The patent converts the potentially harmful oxide layer that causes re-entrant profiles into a beneficial feature. By applying Ar/O2 plasma treatment, the oxide layer is selectively reduced in height and modified to create a bottle-shaped profile. This transformation eliminates the re-entrant profile problem while maintaining the oxide's protective function, thereby improving both critical dimension precision and electrical isolation reliability
Solution Approach 2:
The plasma treatment is applied locally to the oxide layer regions that would otherwise form re-entrant profiles. The Ar/O2 treatment modifies only the necessary portions of the structure, creating a bottle-shaped gate profile where the oxide height is reduced at critical locations. This localized modification ensures electrical isolation between conductive layers while maintaining overall manufacturing precision
3Manufacturing precision
If positive resist is used for lithography, then line and space dimensions below 3 μm are achieved, but re-entrant profiles form during subsequent processing steps
Solution Approach 1:
The Ar/O2 plasma treatment is performed as a preliminary step before final etching to pre-modify the oxide layer surface. This preliminary action creates a favorable surface condition that prevents re-entrant profile formation during subsequent etching steps, allowing the positive resist pattern to be transferred accurately without profile distortion
Solution Approach 2:
By controlling plasma parameters (Ar flow 0-1000 SCCM, O2 flow 0-200 SCCM, source power 10-1000 Watts, bias power 10-300 Watts), the oxide layer is selectively modified to prevent re-entrant profiles. This parameter optimization allows small line and space dimensions to be achieved with proper profile control, resolving the contradiction between feature size reduction and profile quality
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 effectively reduces the bridge fail rate and maintains desirable critical dimensions without increasing manufacturing complexity or costs, by forming a bottle-shaped gate structure that enlarges the poly-gate etch critical dimension and reduces the height of the barrier diffusion oxide layer.
Implementation Method 1
performing an Ar/O2 treatment prior to a final overetching of the gate structure
Implementation Method 2
The Ar/O2 treatment can comprise flowing O2 gas in a range of 0 to 200 standard cubic centimeters per minute (SCCM), flowing Ar in a range of 0 to 1000 standard cubic centimeters per minute (SCCM)
Implementation Method 3
if the sidewall of a multi-layer stack containing a tungsten silicide layer in all but the base layer is oxidized, the edges of the tungsten silicide layer will oxidize much more rapidly than the other layers, resulting in a re-entrant sidewall profile
Data Source
AI summary
A semiconductor device can be manufactured by a method that includes forming a structure that includes a plurality of layers of semiconductor material. One or more etching processes are performed on the multi-layered semiconductor structure, and then an Ar/O2 treatment is performed on the multi-layered semiconductor structure. The Ar/O2 treatment includes exposure of the structure to Ar ion bombardment and O2 molecular oxidation. The Ar/O2 treatment can be used to create a bottle-shaped structure.