Cerium Oxide Polishing Liquid for ULSI Substrate Surface Finish
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional polishing liquids, such as fumed silica-based and colloidal silica-based solutions, exhibit low polishing speed and insufficient smoothness for semiconductor substrates, particularly in ultra-large scale integrated (ULSI) semiconductor device production, where high precision and minimal residual film thickness differences are required.
Innovation Solution
A polishing liquid comprising cerium oxide particles, an organic acid with a specific pKa value, a polymer compound with carboxyl acid or carboxylate groups, and water, which improves polishing speed and surface smoothness by maintaining dispersion stability and preventing scratches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fumed silica-based polishing liquid is used, then the polishing liquid can remove inorganic insulation film, but the polishing speed is low
Solution Approach 1:
The invention uses a composite polishing liquid containing both cerium oxide particles and silica particles. The cerium oxide particles (0.1-10 μm) provide high polishing speed, while the silica particles (0.01-1 μm) provide surface smoothness. This composite approach resolves the contradiction by combining materials with complementary properties rather than using a single material type.
Solution Approach 2:
The invention changes the particle size parameters of the polishing agents. Cerium oxide particles are sized at 0.1-10 μm for efficient material removal, while silica particles are sized at 0.01-1 μm for surface finishing. This multi-scale particle size distribution optimizes both polishing speed and surface smoothness by assigning different particle sizes to different functional requirements.
2Productivity
If cerium oxide polishing liquid is used, then the polishing speed is faster, but the dishing amount increases and smoothness deteriorates
Solution Approach 1:
The invention creates a composite system where cerium oxide particles (0.1-10 μm) perform the primary polishing action at high speed, while silica particles (0.01-1 μm) perform surface finishing and dishing correction. The combination allows the system to achieve both high polishing speed and good surface smoothness without the drawbacks of using cerium oxide alone.
Solution Approach 2:
The invention applies different particle types to different functional zones of the polishing process. Cerium oxide particles handle the bulk material removal requiring high speed, while silica particles handle the surface finishing requiring smoothness. This functional differentiation resolves the contradiction by assigning specialized roles to each material type.
3Productivity
If colloidal silica-based polishing liquid is used for STI, then the silicon oxide film can be removed, but the polishing speed ratio between silicon oxide film and stopper film is insufficient
Solution Approach 1:
The invention changes the chemical composition parameters of the polishing liquid by incorporating cerium oxide particles in addition to silica particles. This compositional change increases the polishing speed ratio between silicon oxide film and stopper film, allowing selective removal of the oxide film while protecting the stopper film, thereby resolving the insufficient selectivity of conventional colloidal silica-based liquids.
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 polishing liquid enhances polishing speed and surface smoothness, reducing the dishing amount and ensuring precise film thickness uniformity on semiconductor substrates, thereby improving the production quality of ULSI devices.
Implementation Method 1
a polishing liquid for chemical mechanical polishing (CMP) including cerium oxide particles
Implementation Method 2
chemical mechanical polishing (CMP)
Implementation Method 3
an organic acid A, a polymer compound B having a carboxyl acid group or a carboxylate group
Implementation Method 4
a polishing liquid for chemical mechanical polishing (CMP) including cerium oxide particles, an organic acid A, a polymer compound B having a carboxyl acid group or a carboxylate group, and water
Data Source
AI summary
Provided is a polishing liquid including cerium oxide particles, an organic acid A, a polymer compound B having a carboxyl acid group or a carboxylate group, and water, wherein the organic acid A has at least one group selected from the group consisting of —COOM group, -Ph-OM group, —SO3M group and —PO3M2 group, pKa of the organic acid A is less than 9, a content of the organic acid A is 0.001 to 1 mass % with respect to the total mass of the polishing liquid, and a content of the polymer compound B is 0.01 to 0.50 mass % with respect to the total mass of the polishing liquid, and pH is in the range of 4.0 to 7.0.