Cerium Oxide Abrasive Selection for Silicon Oxide CMP Rate Control
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Solution Overview
Problem
Existing polishing liquids containing abrasive grains struggle to adjust the polishing rate of materials effectively, particularly for silicon oxide in blanket wafers, necessitating a novel method to enhance polishing efficiency.
Innovation Solution
The selection of abrasive grains based on the average positron lifetime measured by a positron annihilation method, specifically using cerium oxide with a crystallite diameter of 30-50 nm, allows for adjusting the polishing rate by controlling the oxygen defects and mechanical polishing force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polishing liquids containing abrasive grains are used, then polishing can be performed, but the polishing rate of silicon oxide in blanket wafers is insufficient and cannot be adjusted effectively
Solution Approach 1:
The invention changes the physical-chemical parameters of the abrasive grains by controlling the positron lifetime (which reflects oxygen defect density) and crystallite diameter. By adjusting these parameters within specific ranges, the polishing rate of silicon oxide can be effectively controlled and adjusted to meet different application requirements.
Solution Approach 2:
The invention uses composite abrasive grains containing both cerium oxide and silicon oxide, where the cerium oxide component provides chemical polishing action and the silicon oxide component provides mechanical polishing action. This composite structure enables effective polishing of silicon oxide substrates with adjustable rates.
2Productivity
If abrasive grains with high mechanical polishing force are used, then polishing rate increases, but control over polishing rate adjustment becomes difficult
Solution Approach 1:
The invention establishes specific parameter ranges for positron lifetime (300-360 ps) and crystallite diameter (36-50 nm) that optimize the balance between mechanical polishing force and chemical polishing activity. Within these ranges, the abrasive grains maintain high polishing rate while allowing effective control and adjustment.
3Productivity
If abrasive grains with small crystallite diameter are used, then chemical polishing activity increases, but mechanical polishing force decreases
Solution Approach 1:
The invention creates a composite abrasive grain system where cerium oxide particles with small crystallite diameter (30-50 nm) provide chemical polishing activity, while the overall particle structure and composition maintain sufficient mechanical polishing force. The composite nature allows both mechanisms to work synergistically.
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 approach significantly increases the polishing rate of silicon oxide in both blanket and pattern wafers, maintaining high mechanical polishing force and achieving rates of 25 nm/min or more in blanket wafers and 15 nm/min or more in pattern regions with specific line/space configurations.
Implementation Method 1
the abrasive grains are selected on the basis of an average value of a positron lifetime as measured by a positron annihilation method
Implementation Method 2
abrasive grains containing cerium oxide... increasing the polishing rate of silicon oxide
Implementation Method 3
CMP (chemical mechanical polishing) technology... as a polishing liquid used in CMP, a polishing liquid that contains abrasive grains containing cerium is known
Data Source
AI summary
A selection method for abrasive grains, in which the abrasive grains contain cerium, and the abrasive grains are selected on the basis of an average value of a positron lifetime as measured by a positron annihilation method. Abrasive grains containing cerium, in which an average value of a positron lifetime as measured by a positron annihilation method is 360 ps or less. A polishing liquid containing the above-described abrasive grains and water. A multi-pack polishing liquid having a first liquid containing the above-described abrasive grains and water, and a second liquid containing a component other than the above-described abrasive grains and water, and water. A polishing method including polishing a member to be polished by using the above-described polishing liquid.