Co-Flow Epitaxial Deposition for Low-Temperature Selective Si Doping
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Solution Overview
Problem
Current epitaxial deposition processes face challenges in achieving selective Si:P or Si:Sb deposition at low temperatures (550 degrees Celsius or less), leading to complex and time-consuming cyclic deposition/etch processes with low throughput due to the inactivity of HCl at these temperatures.
Innovation Solution
A method involving the co-flow of chlorosilane precursors, such as dichlorosilane and trichlorosilane, with antimony-containing or phosphorous-containing precursors, allowing for continuous etching and selective deposition of epitaxial layers on crystalline surfaces while maintaining low temperatures, thereby improving selectivity and growth rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If lower processing temperatures (600°C or less) are used for selective epitaxial deposition, then thermal damage to underlying structures is reduced, but typical etching gases fail to provide suitable selectivity between epitaxial and polycrystalline layers
Solution Approach 1:
The patent changes the chemical parameters of the deposition process by using chlorosilane-based precursors instead of traditional silicon precursors. This chemical parameter change enables the deposition to proceed selectively at lower temperatures (550°C or less) without requiring high-temperature etching gases, thereby maintaining both low temperature and high selectivity simultaneously.
2Manufacturing precision
If cyclic deposition/etch process is used for selective epitaxial deposition, then selectivity can be achieved, but the process becomes complex and difficult to maintain with low throughput
Solution Approach 1:
The patent merges the deposition and etching functions into a single continuous process step. By using chlorosilane precursors that inherently provide both deposition and self-limiting etching behavior, the complex cyclic process is simplified into a straightforward single-step selective epitaxial deposition, reducing process complexity while maintaining selectivity.
Solution Approach 2:
The patent implements continuous deposition without interruption by eliminating the need for cyclic deposition/etch steps. The chlorosilane-based process maintains continuous useful action through a single continuous deposition step that achieves selective growth, thereby increasing throughput and simplifying process control.
3Manufacturing precision
If cyclic deposition/etch process is used for selective epitaxial deposition, then selectivity can be achieved, but throughput is reduced due to multiple process steps
Solution Approach 1:
The patent combines multiple process steps into a single continuous deposition step using chlorosilane precursors. This merging eliminates the need for repeated deposition and etching cycles, directly increasing throughput while maintaining the selectivity required for high-quality epitaxial growth.
Solution Approach 2:
The patent achieves continuous useful action by implementing a single continuous deposition process without interruption. The chlorosilane-based chemistry enables continuous selective epitaxial growth without the need to pause for etching steps, thereby maximizing productivity and throughput while maintaining manufacturing precision.
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 method enables high-concentration phosphorous and antimony doping with enhanced adhesion and growth rates on crystalline surfaces, reducing faceting and improving the electrical conductivity of source/drain regions without the need for additional etch back processes, thus increasing the efficiency and selectivity of the epitaxial deposition process.
Implementation Method 1
flowing a first chlorosilane precursor gas selected from dichlorosilane and trichlorosilane; co-flowing a higher order chlorosilane precursor gas having a formula ClySixH(2X+2−y)
Implementation Method 2
heating the substrate to a temperature of about 550° C. or less
Implementation Method 3
co-flowing an n-type dopant precursor gas with the first chlorosilane precursor gas and the higher order chlorosilane precursor gas
Data Source
AI summary
Methods for selectively depositing an epitaxial layer are provided. In some implementations, the selective epitaxial deposition process includes providing the co-flow of chlorosilane precursors with at least one of an antimony-containing precursor and a phosphorous-containing precursor. The method utilizes co-flowing of multiple chlorosilane precursors to enable combination of silicon and at least one of phosphorous and antimony in the same matrix using a low-temperature selective process. The deposited epitaxial layer using the epitaxial deposition techniques described not only contains phosphorous and/or antimony but also has a high activated phosphorous and/or antimony concentration.