Polyoxyalkylated Polyhydric Alcohol Suppressor for Void-Free Submicron Filling
Solution Overview
Problem
The challenge in semiconductor manufacturing is filling small features like vias and trenches with copper electroplating, particularly at nanometer scales, where seed overhang issues lead to void formation and non-conformal copper seed deposition results in defects such as voids and seams, especially in features with convex shapes and high aspect ratios.
Innovation Solution
The use of polyoxyalkylated polyalcohols with random copolymer or triblock copolymer structures as additives in the copper electroplating bath, which react with polyhydric alcohols having multiple hydroxyl groups and alkylene oxides, effectively suppresses sidewall copper growth, enabling a pronounced bottom-up fill and defect-free trench filling by controlling the growth front.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional suppressors are used for copper electroplating, then general filling is achieved, but void-free filling of submicron features with seed overhang is not achieved
Solution Approach 1:
The patent modifies the molecular weight and chemical structure parameters of the suppressor polymer. Specifically, it uses polyalkylene glycols with molecular weights of 10,000-100,000 g/mol (higher than conventional suppressors) and incorporates specific functional groups (hydroxyl, carboxyl, amine, or amide groups) at controlled concentrations (0.1-10 mmol/g). These parameter changes enable the suppressor to effectively handle seed overhang conditions and achieve void-free filling in submicron features.
Solution Approach 2:
The patent employs composite suppressor molecules that combine polyalkylene glycol backbones with grafted functional groups. The polyalkylene glycol provides the base suppressor functionality, while the grafted functional groups (such as polyethylene glycol chains with terminal hydroxyl groups, or carboxymethyl groups) provide enhanced adhesion and control over copper deposition. This composite structure allows the suppressor to simultaneously manage sidewall deposition and bottom-up filling in challenging submicron features with seed overhang.
2Area of moving object
If aperture size is reduced to below 100 nanometers, then higher integration is achieved, but filling becomes especially challenging due to seed overhang and inhomogeneity
Solution Approach 1:
The patent adjusts the suppressor molecular weight to 10,000-100,000 g/mol and controls the functional group content at 0.1-10 mmol/g. These parameter optimizations are specifically tailored for sub-100nm aperture filling, where the enhanced molecular weight provides better steric hindrance and the functional groups ensure uniform adsorption on the copper surface, achieving conformal and homogeneous filling even in the presence of seed overhang.
Solution Approach 2:
The patent introduces functional groups at specific locations on the suppressor molecule (grafted onto the polyalkylene glycol backbone). These locally concentrated functional groups create zones of enhanced interaction with the copper seed layer, ensuring uniform nucleation and growth control specifically at the critical interfaces where seed overhang occurs, while the polyalkylene glycol backbone provides overall suppressor functionality.
3Reliability
If suppressor strength is increased to avoid sidewall growth, then void formation is prevented, but filling efficiency may be reduced
Solution Approach 1:
The patent optimizes the suppressor molecular weight to 10,000-100,000 g/mol and functional group content to 0.1-10 mmol/g. This parameter range provides sufficient suppressor strength to prevent sidewall growth and void formation, while the polyalkylene glycol backbone structure ensures adequate copper ion transport to the substrate, maintaining acceptable filling speeds despite the enhanced suppression capability.
Solution Approach 2:
The composite suppressor structure combines the polyalkylene glycol backbone (which provides moderate suppression and good ion transport) with grafted functional groups (which provide strong local suppression at the copper interface). This composite design achieves strong overall suppression to prevent voids while maintaining filling efficiency through the balanced contribution of both structural components.
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 results in a substantially void-free and seamless filling of features, even with non-conformal copper seeds, and ensures homogeneous filling in dense feature areas, particularly effective for aperture sizes of 30 nanometers or below, addressing the seed overhang issue and achieving defect-free trench filling.
Implementation Method 1
suppressors are used to provide a substantially bottom-up filling of small features like vias or trenches
Implementation Method 2
Filling of small features, such as vias and trenches, by copper electroplating
Data Source
AI summary
A composition comprising at least one source of metal ions and at least one additive obtainable by reacting a polyhydric alcohol comprising at least 5 hydroxyl functional groups with at least a first alkylene oxide and a second alkylene oxide from a mixture of the first alkylene oxide and the second alkylene oxide or a third alkylene oxide, a second alkylene oxide, and a first alkylene oxide in aforesaid sequence, the third alkylene oxide having a longer alkyl chain than the second alkylene oxide and the second alkylene oxide having a longer alkyl chain than the first alkylene oxide.