Void-Free Cobalt Plating Additive for Submicron Features
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Solution Overview
Problem
Current cobalt electroplating processes face challenges in achieving void-free filling of submicrometer-sized recessed features on semiconductor substrates, particularly as feature sizes decrease, and there is a need for additives that ensure seamless deposition in nanometer-scale apertures.
Innovation Solution
A composition comprising cobalt ions and specific additives of formula I, which include alkanediyl, alkenediyl, or alkynediyl groups, along with amino or hydroxy functionalities, is used to create a cobalt electroplating bath that enables void-free and seam-free filling of nanometer-sized interconnect features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional cobalt electroplating processes are used, then the plating can be performed with standard additives, but void-free filling of submicrometer-sized recessed features cannot be achieved
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition parameters of the electroplating bath. Specifically, it introduces a novel additive with a defined molecular structure containing specific functional groups (carboxylic acid, hydroxyl, amino, or sulfonic acid groups) at controlled concentrations (0.1-10 ppm). This chemical parameter modification enables the cobalt electroplating process to achieve void-free filling of submicrometer features by altering the deposition kinetics and adhesion properties at the nanometer scale.
Solution Approach 2:
The patent employs an intermediary substance - the specially designed organic additive molecule - that mediates between the cobalt ions in solution and the substrate surface. This intermediary additive adsorbs onto the substrate and modifies the local chemical environment, facilitating uniform cobalt deposition and preventing void formation in recessed features. The additive acts as a bridge that enables controlled metal ion reduction and deposition at critical interfaces.
2Manufacturing precision
If aperture size of recessed features decreases to nanometer scale, then the demand for filling precision increases, but conventional additives fail to provide void-free filling
Solution Approach 1:
The patent applies local quality by designing an additive with specific functional groups positioned to interact with the substrate surface at critical locations. The molecular structure contains multiple functional groups (carboxylic acid, hydroxyl, amino, or sulfonic acid) that can selectively adsorb at different sites on the substrate and within recessed features. This localized chemical interaction ensures uniform deposition quality throughout the aperture, particularly at the bottom and sidewalls where voids typically form, rather than just on the surface.
Solution Approach 2:
The patent uses a composite approach by combining multiple functional groups within a single additive molecule. The additive comprises a organic compound containing at least two different functional groups from the specified categories, creating a multifunctional molecule that can simultaneously provide adhesion promotion, deposition control, and void prevention. This composite functional structure within one additive entity addresses multiple deposition challenges simultaneously.
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 deposits cobalt or cobalt alloys into features with aperture sizes of 100 nanometers or less, ensuring at least 95% void-free and seam-free filling, thereby improving the reliability and quality of semiconductor manufacturing.
Implementation Method 1
the presence of organic substances as additives in the electroplating bath can be crucial in achieving a uniform metal deposit on a substrate surface
Implementation Method 2
Filling of small features, such as vias and trenches, by metal electroplating is an essential part of the semiconductor manufacture process
Data Source
Figure 1~2
Figure 3~4
AI summary
Use of a compound of formula I for depositing cobalt on semiconductor substrates comprising recessed features having an aperture size below 100 nm, preferably below 50 nm wherein R1 is selected from X-Y; R2 is selected from R1 and R3; X is selected from linear or branched C1 to C10 alkanediyl, linear or branched C2 to C10 alkenediyl, linear or branched C2 to C10 alkynediyl, and -(C2H3R6-O)m-; Y is selected from OR3; R3is selected from (i) H, (ii) C5 to C20 aryl, (iii) C1 to C10 alkyl (iv) C6 to C20 arylalkyl, (v) C6 to C20 alkyl aryl, which may be substituted by OH, SO3H, COOH or a combination thereof, and (vi) (C2H3R6-O)n-H, ; m, n are integers independently selected from 1 to 30; R6 is selected from H and C1 to C5 alkyl.