Selective Silicon Etching Composition for TSV Processes
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Solution Overview
Problem
The existing acidic etchants used in semiconductor manufacturing processes have low selectivity between silicon and tungsten films, leading to increased defect rates and short circuits, particularly in Through Silicon Via (TSV) processes.
Innovation Solution
A composition comprising a fluorine compound, nitric acid, acetic acid, phosphoric acid, and an organic amine compound, specifically optimized to enhance the etch selectivity of silicon over metal films, with a combination that includes hydrofluoric acid, ammonium bifluoride, polyethyleneimine, and other additives, which control the etch rate and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If acidic etchant is used for silicon bulk etching, then etching capability is achieved, but selectivity with respect to tungsten film deteriorates
Solution Approach 1:
The patent modifies the chemical composition parameters of the etchant by combining hydrofluoric acid (for silicon etching) with organic amine compounds and chelating agents that selectively inhibit tungsten etching. This parameter adjustment achieves both high silicon etching rate and improved selectivity, resolving the contradiction between productivity and reliability.
Solution Approach 2:
The invention creates a composite etchant system that integrates multiple chemical components: hydrofluoric acid as the primary etching agent, organic amine compounds as selectivity enhancers, and chelating agents as metal etching inhibitors. This composite formulation simultaneously achieves high silicon etching capability and selective protection of tungsten films.
2Ease of manufacture
If conventional acidic etchant is used, then silicon etching is performed, but metal film etching occurs non-selectively causing defects
Solution Approach 1:
The patent introduces organic amine compounds and chelating agents as intermediary substances that mediate between the hydrofluoric acid and the metal film. These intermediaries selectively adsorb onto metal surfaces or form protective complexes, preventing direct attack by HF on tungsten while allowing silicon etching to proceed, thereby reducing defects.
3Reliability
If etching selectivity of silicon to metal film is improved, then metal film etching is minimized, but etch rate may be reduced
Solution Approach 1:
The patent applies local quality enhancement by using organic amine compounds that selectively interact with metal surfaces versus silicon surfaces. The etchant exhibits different chemical behaviors at different locations: high selectivity at metal interfaces through adsorption/complexation, and high etching rate at silicon surfaces through HF action, thus resolving the speed-selectivity tradeoff.
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 achieves an etch rate of silicon of 3 μm/min or more with selectivity of 100 or more to the metal film, effectively reducing defects and short circuits by selectively etching silicon while minimizing metal film etching.
Implementation Method 1
an acidic etchant of silicon comprises etching species such as hydrofluoric acid
Implementation Method 2
oxidizing species such as nitric acid and sulfuric acid
Data Source
AI summary
The present invention relates to a composition for selectively etching silicon on a surface on which a metal film and silicon (Si) are exposed.According to the present invention, it is possible to improve etch selectivity of silicon on the semiconductor surface on which the metal film and silicon are exposed.