Two-Stage CMP Slurry for Planarization and Self-Stopping
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Solution Overview
Problem
Conventional chemical mechanical polishing methods, such as HPS-CMP, fail to achieve high planarity and often damage structures with protrusions due to excessive polishing and lack of self-stopping characteristics, leading to incomplete removal of stepped portions and potential damage to the substrate.
Innovation Solution
A method involving a two-stage polishing process using a first slurry composition with a surfactant and pH control to create a self-stopping characteristic, followed by a second slurry composition without this characteristic, to efficiently planarize the substrate while protecting the structure and preventing excessive polishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If HPS-CMP process is used to achieve high planarity, then planarity is improved, but substrate structures with protrusions are damaged due to excessive polishing
Solution Approach 1:
The polishing process is divided into two distinct stages: a first polishing process using a first slurry composition to remove stepped portions and achieve preliminary planarity, and a second polishing process using a second slurry composition to achieve final high planarity. This segmentation allows each stage to be optimized for its specific function, preventing substrate damage while achieving the desired planarity.
Solution Approach 2:
The invention changes the chemical parameters of the slurry composition between the two polishing stages. The first slurry composition has different chemical properties compared to the second slurry composition, allowing controlled removal of stepped portions in the first stage and precise planarity achievement in the second stage, thereby avoiding excessive polishing and substrate damage.
2Device complexity
If conventional single slurry composition is used for polishing, then process simplicity is maintained, but self-stopping characteristic is lost leading to excessive polishing
Solution Approach 1:
The polishing process is segmented into two distinct processes with different slurry compositions. The first polishing process uses a first slurry composition optimized for removing stepped portions, while the second polishing process uses a second slurry composition optimized for achieving final planarity. This segmentation provides self-stopping characteristics that prevent excessive polishing and improve manufacturing precision.
3Productivity
If first slurry composition with self-stopping characteristic is used, then stepped portions are removed effectively, but additional polishing step is required for final planarity
Solution Approach 1:
The invention segments the polishing process into two specialized stages: the first polishing process efficiently removes stepped portions using a first slurry composition with self-stopping characteristics, and the second polishing process achieves final high planarity using a second slurry composition. This segmentation optimizes each stage for its specific function, improving overall productivity while maintaining manageable process complexity.
Solution Approach 2:
The two polishing processes are designed to be continuous and complementary. The first polishing process prepares the surface by removing stepped portions, and the second polishing process immediately follows to achieve final planarity. This continuous action ensures efficient use of time and resources, maximizing productivity without creating unnecessary process gaps or complexity.
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 method achieves high planarity with minimal substrate damage by selectively removing stepped portions and ensuring the polishing process stops once the surface is flat, maintaining structural integrity and efficiency.
Implementation Method 1
the surface portion of the semiconductor substrate is chemically polished by reactions between chemical components included in the slurry composition and ingredients in the surface portion of the semiconductor substrate
Implementation Method 2
a layer having a stepped portion that is passivated by polymers to reduce a chemical polishing rate of the layer
Implementation Method 3
The abrasive of the slurry composition and protrusions of the polishing pad may mechanically polish the surface portion of the semiconductor substrate
Implementation Method 4
The semiconductor substrate and the polishing pad may be moved with respect to each other while the polishing pad makes contact with the semiconductor substrate
Data Source
AI summary
In an embodiment, a chemical mechanical polishing method for a substrate having a first layer and a stepped portion. A surface of the first layer is positioned above an upper face of the stepped portion. A polishing process for selectively removing the stepped portion is performed on the first layer by using a first slurry composition that has a self-stopping characteristic so that the first layer is changed into a second layer having a substantially flat surface. A second polishing process is performed using a second slurry composition that does not have the self-stopping characteristic, until the upper face of the stepped portion is exposed.