Silicon Etching Composition for Fast Start and Layer Selectivity
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Solution Overview
Problem
Existing etching compositions struggle to selectively remove silicon layers without damaging epitaxial layers and achieve rapid reaction initiation during the manufacturing of integrated circuit devices.
Innovation Solution
An etching composition comprising an acid mixture of hydrofluoric acid, nitric acid, phosphoric acid, and acetic acid, with a reaction initiator that reduces nitric acid to nitrous acid, enhancing etching reaction initiation and selectivity for different silicon layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional etching compositions are used, then silicon layers can be removed, but the etching reaction initiation is slow and selectivity between different silicon layers is insufficient
Solution Approach 1:
The patent changes the chemical parameters of the etching composition by introducing a reaction initiator that reduces nitric acid to nitrous acid, transforming the etching mechanism from slow direct oxidation to rapid nitrous acid-mediated etching. This parameter change enables both fast reaction initiation and maintained selectivity between differently doped silicon layers
Solution Approach 2:
The reaction initiator acts as an intermediary substance that converts nitric acid into nitrous acid, which then serves as the active etching agent. This intermediary mechanism resolves the contradiction by providing a fast-acting etching species while maintaining the compositional selectivity needed for differential etching of silicon layers
2Speed
If etching composition aggressively removes silicon, then etching speed increases, but damage to epitaxial layers occurs
Solution Approach 1:
The patent applies local quality by making the etching action selective to specific silicon regions based on their doping characteristics. The nitrous acid-generated etching mechanism preferentially attacks heavily doped silicon layers while sparing lightly doped epitaxial layers, achieving fast etching speed without causing damage to sensitive structures
Solution Approach 2:
By changing the etching mechanism from direct nitric acid oxidation to nitrous acid-mediated etching through the reaction initiator, the patent achieves a parameter transformation that enables aggressive etching of target silicon layers while the selective chemistry inherently protects epitaxial layers from damage
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 composition enables rapid and selective etching of silicon layers, improving etching reaction initiation and maintaining surface morphology, thereby enhancing the manufacturing process of integrated circuit devices.
Implementation Method 1
a reaction initiator that initiates a reaction between the silicon layer and the acid mixture and includes a reducing organic compound... the reaction initiator may reduce the nitric acid to nitrous acid
Implementation Method 2
an acid mixture including hydrofluoric acid, nitric acid, phosphoric acid, and acetic acid... a reaction between the silicon layer and the acid mixture
Implementation Method 3
an etching composition that may selectively remove the silicon layer without damaging the epitaxial layer... efficiently etch the silicon layer through rapid reaction initiation
Data Source
AI summary
Disclosed is an etching composition for etching a silicon layer, the etching composition including an acid mixture including hydrofluoric acid, nitric acid, phosphoric acid, and acetic acid, a reaction initiator that initiates a reaction between the silicon layer and the acid mixture and includes a reducing organic compound, and water.