Selective N-Doped Silicon Epitaxy Without Low-Temperature Etch Cycles
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Solution Overview
Problem
Traditional selective epitaxy processes face challenges in achieving suitable selectivity between epitaxial and polycrystalline/amorphous layers at low temperatures (e.g., 500 degrees Celsius or less), leading to complex and time-consuming cyclic deposition/etch processes with low throughput.
Innovation Solution
A low-temperature selective epitaxial deposition process using a co-flow of chlorosilane precursors with antimony- or phosphorous-containing precursors, enabling etchant-free deposition of silicon-containing films with high dopant concentrations, selectively forming on crystalline surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional etching gases are used at lower processing temperatures, then deposition temperature is reduced, but selectivity between epitaxial layer and polycrystalline/amorphous layer deteriorates
Solution Approach 1:
The patent changes the chemical parameters of the gas mixture by introducing specific organometallic precursors (trimethylantimony, trimethylphosphine) combined with silane and hydrogen. This chemical parameter change enables selective epitaxial growth at lower temperatures (350-500°C) without compromising selectivity, as the organometallic compounds provide selective reactivity only on crystalline silicon surfaces.
Solution Approach 2:
The patent uses a composite gas mixture comprising multiple components: silane (SiH4), hydrogen (H2), trimethylantimony (Sb(CH3)3), and trimethylphosphine (P(CH3)3). This composite approach combines the benefits of each gas component, where silane provides silicon source, hydrogen maintains reducing atmosphere, and the organometallic compounds provide selective doping and enhanced selectivity at low temperatures.
2Manufacturing precision
If cyclic deposition/etch processes are used to achieve selectivity, then selectivity is improved, but process complexity and processing time increase
Solution Approach 1:
The patent extracts and eliminates the etching step from the traditional cyclic deposition/etch process. By using organometallic precursor gases that provide inherently selective reactivity, the process achieves the desired selectivity through deposition alone, removing the need for separate etching cycles and significantly simplifying the overall process flow.
Solution Approach 2:
The patent implements a continuous selective deposition process where the organometallic-containing gas mixture continuously deposits epitaxial silicon with simultaneous in-situ doping. This continuous action eliminates the intermittent stop-and-go nature of cyclic processes, improving throughput and reducing process complexity while maintaining high selectivity.
3Manufacturing precision
If cyclic deposition/etch processes are used to achieve selectivity, then selectivity is improved, but throughput decreases
Solution Approach 1:
The patent implements a continuous selective deposition process where the organometallic-containing gas mixture continuously deposits epitaxial silicon with simultaneous in-situ doping. This continuous action eliminates the intermittent stop-and-go nature of cyclic processes, improving throughput and reducing process complexity while maintaining high selectivity.
Solution Approach 2:
The patent performs preliminary action by incorporating dopant precursors (trimethylantimony, trimethylphosphine) into the deposition gas mixture before deposition begins. This allows simultaneous in-situ doping during the deposition process itself, eliminating the need for separate post-deposition doping steps and thereby increasing overall throughput.
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 process improves throughput and selectivity, allowing for high-concentration dopant deposition at low temperatures, enhancing adaptability and feasibility for advanced semiconductor device manufacturing.
Implementation Method 1
heating a substrate disposed within a processing chamber to a temperature in a range from about 350 degrees Celsius to about 500 degrees Celsius
Implementation Method 2
exposing the substrate to a soak process in a phosphorous source gas at a first chamber pressure for a period of time
Implementation Method 3
exposing the substrate to a deposition gas mixture including a chlorosilane gas and an antimony-containing source gas to deposit a silicon-containing epitaxial layer including antimony on the substrate
Implementation Method 4
The deposition reaction causes an epitaxial layer to be formed on monocrystalline surfaces of a substrate
Data Source
AI summary
Methods for low temperature selective deposition of epitaxial silicon-containing films and semiconductor devices incorporating the epitaxial silicon-containing films are provided. The method includes etchant-free selective epitaxy of N-type doped silicon including either a soak in a phosphorous source gas or an antimony seed layer. In one or more implementations, an underlying silicon surface is exposed to a pre-soak process performed by exposing the silicon surface to a phosphorous-containing gas, for example, phosphine gas, for a period of time followed by growing the N-doped epitaxial silicon film by co-flowing silicon sources and antimony sources only. The pre-soak/deposition process can be applied repeatedly to achieve desirable stack thickness. In one or more implementations, a seed layer of antimony-doped silicon is formed by co-flowing silicon and antimony source gases followed by co-flowing silicon source gases, antimony source gases, and phosphorous source gases to grow the N-doped epitaxial silicon film.