Acidic Post-CMP Cleaning Composition for Copper Wafer Surface Roughness Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional post-CMP cleaning solutions are ineffective in removing contaminants like Cu-BTA complexes and copper oxides from wafer surfaces after the Cu-CMP process, leading to increased wafer surface roughness and reliability issues in subsequent semiconductor manufacturing processes.
Innovation Solution
An acidic cleaning composition comprising polyamino-polycarboxylic acids, hydroxycarboxylic acids, and surfactants, with a pH of 1 to 5, is used to effectively remove metallic and non-metallic particulates, controlling the etching rate and enhancing wettability, thereby preventing redeposition of contaminants and minimizing wafer surface roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional post-CMP cleaning solutions containing ammonium hydroxide and amines are used, then contaminants can be removed from the wafer surface, but the cleaning solution produces fishy odors and amines poison the photoresist leading to reliability issues
Solution Approach 1:
The invention changes the chemical parameters of the cleaning solution by using organic acids (formic acid, acetic acid, propionic acid, or butyric acid) instead of conventional ammonium hydroxide-based solutions. This parameter change eliminates the fishy odor and prevents amine poisoning of photoresist while maintaining effective contaminant removal capabilities
Solution Approach 2:
The invention employs readily available organic acids that can be easily disposed of after use, replacing the problematic amine-based solutions. These organic acids provide effective cleaning without the harmful side effects and can be discarded without special handling requirements
2Reliability
If strong cleaning agents are used to remove contaminants like Cu-BTA complexes and copper oxides, then cleaning effectiveness improves, but wafer surface roughness increases
Solution Approach 1:
The invention optimizes the strength parameters of the cleaning solution by using mild organic acids with controlled concentrations (0.1-10% for formic acid, 0.1-5% for acetic acid, etc.). These parameter settings provide sufficient cleaning power to remove Cu-BTA complexes and copper oxides while maintaining low etching rates that preserve wafer surface smoothness
Solution Approach 2:
The invention employs dynamic control of the cleaning process by adjusting the organic acid concentration and contact time to achieve optimal cleaning effectiveness. The solution strength is tuned to provide just enough cleaning power without excessive etching, adapting the cleaning action to the specific contamination level on the wafer surface
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 acidic cleaning composition efficiently removes contaminants while maintaining low copper etching rates, ensuring smooth subsequent processes like thin layer deposition and photolithography by effectively removing BTA and copper residues, thus enhancing device reliability and yield.
Implementation Method 1
an acidic cleaning composition that is useful for removing the contaminants (such as abrasives, metal complexes, and organic compounds) from a wafer surface after a chemical mechanical polishing (CMP) process
Implementation Method 2
at least one polyamino-polycarboxylic acid, or salt thereof
Implementation Method 3
The conventional post-CMP cleaning solution also usually included a surfactant which is also called a wetting agent that is able to lower the surface tension of the post-CMP cleaning solution, allowing easier spreading
Implementation Method 4
the extent of copper etching is very low after using the acidic cleaning composition of the present invention for removing the contaminants from the wafer surface after a CMP process
Data Source
AI summary
An acidic post-CMP cleaning composition includes at least one polyamino-polycarboxylic acid, or salt thereof; at least one hydroxycarboxylic acid, or salt thereof; and the remainder being substantially water. The acidic cleaning composition also includes a surfactant. The acidic post-CMP cleaning composition has a pH of 1 to 5, and is useful for removing the contaminants from the wafer surface after a CMP process without making roughness worse.