Shallow Trench Isolation Taper Angle Control for Residue Removal
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Solution Overview
Problem
The existing manufacturing methods for semiconductor devices using Shallow Trench Isolation (STI) face challenges such as low yield due to dust generation and substrate damage from etching residues, and ineffective residue removal, especially when forming a forward tapered shape on the STI side face.
Innovation Solution
A method involving forming a trench on a semiconductor substrate with a first insulation film as a mask, embedding a second insulation film, selectively removing the upper portion of the first film, isotropically removing parts of the second film to create a taper angle of 90° or more on the STI side face, and adjusting the half-etching amount to prevent constricted portions and etching residues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a forward tapered shape is formed on the STI side face to inhibit etching residues, then dust generation is reduced, but processing damage to the semiconductor substrate occurs causing gate leak
Solution Approach 1:
The invention changes the geometric parameters of the STI structure by forming a tapered side face with a specific taper angle of 15° or more. This parameter modification allows the side face to be free of etching residues while preventing processing damage to the semiconductor substrate, thereby eliminating both dust generation and gate leak issues simultaneously
Solution Approach 2:
The tapered side face is formed preliminarily during the STI formation process before subsequent gate electrode and gate side wall processing. This preliminary shaping prevents etching residues from forming in the first place, eliminating the need for additional residue removal steps that could cause substrate damage
2Object-generated harmful factors
If only chamfering the side face is performed to remove residues, then dust generation is reduced, but residues cannot be effectively removed
Solution Approach 1:
The invention modifies the side face geometry by forming a tapered shape with a taper angle of 15° or more, which is a more significant geometric change than simple chamfering. This adequate taper angle ensures that etching residues can be completely removed during processing, achieving both dust reduction and effective residue removal
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 enhances yield by preventing dust generation and substrate damage, achieving a satisfactory side surface shape and improving device characteristics by controlling the taper angle and height of the STI, thereby inhibiting constricted portions and ensuring effective residue removal.
Implementation Method 1
the mask material is selectively removed using hot phosphoric acid (H3PO4) solution
Implementation Method 2
isotropically removing a part of the second insulation film
Data Source
AI summary
A trench is formed on a semiconductor substrate with a first insulation film patterned on the semiconductor substrate as a mask; a second insulation film is embedded in the trench and flattened; an upper portion of the first insulation film is selectively removed, and a part of a side face of the second insulation film is exposed; a part of the second insulation film is isotropically removed; a lower portion of the remaining first insulation film is selectively removed; and then a part of the remaining second insulation film is further isotropically removed so that an upper face of the second insulation film is at a predetermined height from a surface of the semiconductor substrate, a taper having a minimum taper angle of 90° or more is formed on the side face of the second insulation film, and a STI is formed.