Bottom-Up Polysilicon Recess Filling via Selective Etching
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Solution Overview
Problem
Conventional semiconductor device manufacturing methods, such as the DED process, face challenges in efficiently filling high aspect ratio recesses with silicon films without generating voids, often requiring repetitive processes that prolong the manufacturing period.
Innovation Solution
A method involving bottom-up film deposition where an amorphous silicon film is etched to leave it on the recess bottom, followed by depositing a polysilicon film using dichlorosilane, eliminating the need for repetitive DED processes by selectively growing the silicon film from the bottom without voids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional DED process is used to fill high aspect ratio recesses, then silicon film can be deposited, but repetitive deposition and etching cycles are required which prolongs manufacturing time
Solution Approach 1:
An amorphous silicon film is deposited in advance across the entire surface including the recess before the filling process. This preliminary film serves as a foundation that enables selective bottom-up growth in subsequent steps, eliminating the need for repeated deposition-etching cycles while ensuring complete recess filling.
Solution Approach 2:
Instead of the conventional top-down approach where film is deposited and then etched back repeatedly, this invention uses bottom-up selective growth where silicon grows preferentially from the recess bottom upward. The etching step removes amorphous silicon from surfaces while preserving crystalline silicon, inverting the conventional sequence and achieving complete filling in fewer cycles.
2Manufacturing precision
If DED process is used for recess filling, then silicon film can be formed, but voids may be generated requiring multiple cycles to eliminate
Solution Approach 1:
The invention inverts the conventional approach by implementing bottom-up selective growth where silicon grows from the recess bottom upward. This ensures complete filling without void formation because the growth originates at the deepest point and progresses outward, naturally eliminating voids that plague top-down methods.
Solution Approach 2:
The invention changes the growth parameters by using specific gas compositions and temperature conditions that promote selective crystalline silicon growth from the recess bottom. By controlling deposition temperature, gas flow rates, and precursor selection, the process achieves uniform bottom-up growth that fills high aspect ratio recesses completely without voids in a single cycle.
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 allows for efficient filling of recesses with high-quality silicon films, reducing process time and preventing fin bending issues associated with conventional methods, as the polysilicon film grows uniformly without generating voids.
Implementation Method 1
an amorphous silicon film is deposited in a recess provided in a surface of a substrate by supplying a silicon-containing gas to the substrate
Implementation Method 2
The amorphous silicon film is etched by supplying an etching gas to the substrate so as to leave the amorphous silicon film on a bottom of the recess
Implementation Method 3
A silicon film is deposited on the amorphous silicon film by supplying dichlorosilane to the substrate
Data Source
AI summary
A method for manufacturing a semiconductor device is provided. In the method, an amorphous silicon film is deposited in a recess provided in a surface of a substrate by supplying a silicon-containing gas to the substrate. The amorphous silicon film is etched by supplying an etching gas to the substrate so as to leave the amorphous silicon film on a bottom of the recess. A silicon film is deposited on the amorphous silicon film by supplying dichlorosilane to the substrate.