Ruthenium CMP Composition for Corrosion Control and Stable Removal
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Solution Overview
Problem
Chemical mechanical polishing of semiconductor substrates containing ruthenium is hindered by ruthenium corrosion and unstable polishing speed due to the use of basic chemical mechanical polishing compositions and high-oxidizing halogen-based oxidants.
Innovation Solution
A chemical mechanical polishing composition comprising abrasive grains, an acid with specific anions such as periodate ions, hypochlorite ions, or hypobromite ions, and hydrogen peroxide, with a controlled MB/MC ratio, and functional groups on the abrasive grains to prevent ruthenium corrosion and maintain stable polishing speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a basic chemical mechanical polishing composition is used to suppress ruthenium tetroxide generation, then ruthenium corrosion is reduced, but insufficiently oxidized ruthenium oxide adheres to the polishing pad and polishing characteristics degrade
Solution Approach 1:
The patent changes the chemical parameters of the polishing composition by using a neutral or weakly acidic pH range (pH 6-8) instead of basic conditions, and carefully controls the oxidant concentration and MB/MC ratio to achieve optimal oxidation without excessive corrosion or adhesion
Solution Approach 2:
The patent employs a composite chemical system combining multiple oxidants (periodate, hypochlorite, chlorite, or hypobromite with hydrogen peroxide) in specific ratios, along with abrasive grains having specific zeta potential characteristics, to achieve synergistic effects that simultaneously prevent corrosion and maintain polishing performance
2Productivity
If a halogen-based oxidant with high oxidizing power is used to maintain polishing speed, then ruthenium oxidation is sufficient, but ruthenium corrosion occurs
Solution Approach 1:
The patent reduces the oxidizing power parameter by selecting oxidants with moderate oxidation potential and controlling their concentrations, specifically using MB/MC ratios of 0.015 to 11, which provides sufficient oxidation for polishing speed while preventing excessive corrosion
Solution Approach 2:
The patent introduces abrasive grains with specific surface properties (zeta potential of +10 to +40 mV or -10 to -40 mV) as intermediaries that facilitate controlled oxidation and removal of ruthenium oxide without direct corrosive attack on the ruthenium substrate
3Object-generated harmful factors
If basic chemical mechanical polishing composition is used, then ruthenium tetroxide generation is suppressed, but ruthenium oxide adheres to polishing pad
Solution Approach 1:
The patent changes the pH parameter to neutral or weakly acidic conditions and controls oxidant concentration to achieve complete oxidation of ruthenium to stable oxide forms that do not adhere to the polishing pad, while still suppressing volatile tetroxide formation
Solution Approach 2:
The patent replaces reliance on basic chemical conditions with a controlled oxidizing environment using specific oxidant combinations, where the chemical oxidation mechanism is precisely tuned to produce non-adhering oxide products
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 composition effectively suppresses ruthenium corrosion and maintains a stable polishing speed during the chemical mechanical polishing of semiconductor substrates containing ruthenium, ensuring efficient polishing without excessive reaction.
Implementation Method 1
an acid containing at least one anion selected from the group consisting of periodate ions (IO4−), hypochlorite ions (CIO−), chlorite ions (CIO2−) and hypobromite ions (BrO−)
Implementation Method 2
hydrogen peroxide (C)
Implementation Method 3
abrasive grains (A) in the chemical mechanical polishing composition may have an absolute value of a zeta potential of 10 mV or higher
Implementation Method 4
CMP is a technique in which a chemical mechanical polishing composition is supplied onto a polishing pad stuck onto a surface plate, a semiconductor substrate is pressed on the chemical mechanical polishing composition and the semiconductor substrate and the polishing pad are made to slide on each other, thereby chemically and mechanically polishing the semiconductor substrate
Data Source
AI summary
The present invention provides a chemical mechanical polishing composition with which it is possible to suppress ruthenium corrosion and also perform chemical mechanical polishing of a semiconductor substrate containing ruthenium while maintaining a stable polishing speed. The composition for chemical mechanical polishing of the present invention contains: (A) abrasive grains; (B) an acid containing at least one anion selected from the group consisting of periodate ions (IO4−), hypochlorite ions (CIO−), chlorite ions (CIO2−) and hypobromite ions (BrO−) or a salt of said acid; and (C) hydrogen peroxide. MB/MC=0.015 to 11, where MB (mol/L) is the amount of the (B) acid or salt thereof and MC (mol/L) is the amount of hydrogen peroxide (C).