Chemical Planarization Using Solubility-Changing Agent
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Solution Overview
Problem
Chemical Mechanical Polishing (CMP) is a harsh, expensive, and yield-reducing process that cannot be used for certain microfabrication steps, such as transistor fabrication, especially when gate oxide is exposed, and is not suitable for creating planar surfaces required in photolithography.
Innovation Solution
A chemical planarization process using a developable planarization material, such as silicon-based developer soluble bottom anti-reflective coating (Si-DBARC), which is coated and then selectively dissolved with a solubility-changing agent to achieve a planar surface without mechanical polishing, allowing for simultaneous patterning and etching at multiple heights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If Chemical Mechanical Polishing (CMP) is used to planarize the wafer surface, then a planar surface is achieved, but the process becomes harsh, expensive, and reduces yield
Solution Approach 1:
The patent replaces the mechanical polishing component of CMP with a purely chemical process. A planarization layer made of developer-soluble material (such as DBARC) is deposited and then chemically dissolved using a solubility-changing agent, eliminating mechanical abrasion while achieving the desired planar surface. This substitution resolves the contradiction by removing the harsh mechanical action that reduces yield while maintaining the planarity function.
Solution Approach 2:
The patent changes the chemical parameters of the planarization layer by using a material whose solubility can be altered by a solubility-changing agent. The planarization layer is made of developer-soluble material that becomes soluble when exposed to the solubility-changing agent, enabling controlled chemical removal. This parameter change allows the process to achieve planarization without mechanical stress, thereby improving yield while maintaining surface quality.
2Manufacturing precision
If CMP is used for planarization, then surface planarity is achieved, but processing time and cost increase
Solution Approach 1:
By replacing mechanical polishing with chemical dissolution, the process eliminates the time-consuming mechanical abrasion step. The chemical planarization process using solubility-changing agents acts more rapidly and efficiently than mechanical CMP, reducing overall processing time while achieving the same planarity outcome.
Solution Approach 2:
The patent extracts and removes the mechanical polishing step from the traditional CMP process, retaining only the chemical planarization function. This extraction of the harmful mechanical component streamlines the process, eliminating unnecessary time and cost associated with mechanical abrasion while preserving the essential planarization capability.
3Manufacturing precision
If CMP is used to planarize the wafer, then a planar surface is achieved, but the process is harsh and physically abrasive
Solution Approach 1:
The patent directly substitutes mechanical abrasion with a chemical dissolution process. The planarization layer is removed through chemical reaction with a solubility-changing agent rather than mechanical friction, completely eliminating the harmful mechanical abrasion effect while achieving the desired planar surface.
Solution Approach 2:
The patent introduces a planarization layer made of developer-soluble material as an intermediary between the underlying structure and the final planar surface. This intermediary layer can be chemically dissolved without affecting the underlying sensitive structures, providing a protective buffer that eliminates direct mechanical contact and abrasion on the wafer surface.
4Manufacturing precision
If CMP is used for planarization, then surface flatness is achieved, but flexibility in process application is reduced
Solution Approach 1:
The patent uses a planarization layer with variable chemical properties—specifically, a developer-soluble material whose removal can be controlled by applying a solubility-changing agent. This chemical parameter change allows the process to be adapted to different process requirements, such as adjusting the amount of material removed or selecting different soluble materials for different applications, thereby increasing process flexibility while maintaining surface flatness.
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 method eliminates the need for CMP, reduces costs and processing time, enhances flexibility in resist selection, and preserves sensitive structures by providing a non-abrasive planarization technique that can handle complex topographies, improving the efficiency and yield of microchip fabrication.
Implementation Method 1
The solubility-changing agent is activated such that the solubility-changing agent changes a solubility of a top portion of the planarizing film
Data Source
AI summary
A chemical planarization process described herein can be used for planarizing a substrate without using mechanical abrasion. A developable planarization material can be applied to a substrate having a non-planar topography, such that a planar surface results. The resulting planarization layer can cover existing structures on the substrate. A top portion of the planarization layer can be solubilized using a solubility-changing agent, and then the soluble portion can be removed thereby slimming a height of the planarization material to a target value, which can be a top surface of a tallest underlying structure. With the substrate planarized, additional patterning operations can be executed.