CMP Polishing Composition for Dishing and Skew Reduction
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Solution Overview
Problem
As semiconductor devices become more integrated and complex, the CMP process faces challenges in minimizing defects such as dishing and skew during the polishing of substrates with multiple exposed films, like silicon oxide and silicon nitride.
Innovation Solution
A polishing composition comprising abrasive particles, a polyoxyalkylene-based surfactant with a hydrophile-lipophile balance (HLB) value of 13 or higher, and a skew inhibitor, which effectively inhibits dishing on silicon oxide films and skew on silicon nitride films while maintaining a high polishing speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polishing compositions are used to maintain high polishing speed, then polishing rate is improved, but dishing and skew defects increase
Solution Approach 1:
The patent changes the chemical parameters of the polishing composition by specifying a pH range of 9.0 to 11.0 and controlling the content of metallic elements (Al, Fe, Ca, Mg) within specific ranges. This parameter optimization allows the composition to maintain high polishing speed while reducing dishing and skew defects through controlled chemical interactions with the substrate surfaces.
Solution Approach 2:
The polishing composition is formulated as a composite system containing multiple components: abrasive particles, oxidizing agents, chelating agents, and specific additives. This composite structure enables simultaneous achievement of high polishing rate and surface quality by combining the functions of different materials - abrasives for material removal, oxidizers for surface preparation, and chelators for defect prevention.
2Adaptability or versatility
If polishing composition contains multiple exposed films (silicon oxide and silicon nitride), then versatility is improved, but control of dishing and skew becomes more difficult
Solution Approach 1:
The polishing composition exhibits local quality by providing different chemical environments for different film types. The controlled pH and metallic element content create selective chemical interactions - silicon oxide films experience conditions that minimize dishing, while silicon nitride films are protected from skew through the chelating action of additives like EDTA and citric acid, allowing simultaneous optimization for multiple materials.
Solution Approach 2:
Chelating agents such as EDTA and citric acid act as intermediaries between the polishing composition and the substrate films. These additives bind to metallic ions that could cause harmful chemical reactions, thereby mediating the interaction to prevent skew on silicon nitride while maintaining effective polishing on silicon oxide, enabling controlled multi-film processing.
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 proposed solution significantly reduces the frequency of defects such as dishing and skew, while maintaining a high polishing selectivity ratio and polishing rate, thereby improving the smoothness and quality of the substrate surface.
Implementation Method 1
a polyoxyalkylene-based surfactant... which effectively inhibits dishing on silicon oxide films
Implementation Method 2
a skew inhibitor... which effectively inhibits... skew on silicon nitride films
Implementation Method 3
abrasive particles... CMP is used as a planarization technique to remove steps in certain layers
Implementation Method 4
chemical mechanical polishing (CMP)... polishing composition includes abrasive particles, a polyoxyalkylene-based surfactant, and a skew inhibitor
Data Source
AI summary
A polishing composition for a semiconductor process includes abrasive particles, a polyoxyalkylene-based surfactant, and a skew inhibitor of Formula 1 below. The polyoxyalkylene-based surfactant has a hydrophile-lipophile balance (HLB) value of 13 or higher.In Formula 1 above, R1 is H, a methyl group or an ethyl group, and R2, R3, and R4 are each independently a methyl or ethyl group. When the polishing composition having these characteristics is applied to the polishing of a substrate comprising two or more layers, the polishing composition can provide a smoother polished surface while maintaining a certain level of polishing speed.