Semiconductor Interconnect Cleaning for Metal Residue Diffusion Control
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Solution Overview
Problem
The semiconductor industry faces challenges in preventing metal diffusion and migration during the fabrication of interconnect structures in ICs, leading to short circuits and manufacturing defects due to metal residues left after etching and chemical mechanical planarization processes.
Innovation Solution
A two-step cleaning and etching process is employed, where a first chemical with a low concentration is used to recess the dielectric layer and a second chemical containing fluorine or chlorine is applied to convert metal residues into stable metal fluorides or chlorides, preventing reaction with oxygen and thus eliminating manufacturing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If etching and CMP processes are used to form interconnect structures, then manufacturing efficiency is improved, but metal residues are left that cause diffusion and short circuits
Solution Approach 1:
A metal residue removal process is performed before subsequent interconnect formation steps to eliminate metal residues from etching and CMP processes. This preliminary cleaning action prevents metal diffusion and short circuits in future processing steps, resolving the contradiction between maintaining manufacturing efficiency and ensuring interconnect reliability.
Solution Approach 2:
The patent converts the harmful effect of metal residues (causing diffusion and short circuits) into a controlled removal process. By specifically targeting and removing only the problematic metal residues while preserving the intended metal interconnect structures, the harmful byproducts of manufacturing are transformed into an opportunity to enhance product reliability.
2Device complexity
If metal residues are not removed, then manufacturing process is simpler, but diffusion causes short circuits between conductive features
Solution Approach 1:
The patent introduces a metal residue removal process as an intermediary step between etching/CMP and subsequent interconnect formation. This intermediary process specifically targets and removes metal residues without affecting the intended metal structures, thereby preventing metal diffusion and short circuits while adding minimal complexity to the overall manufacturing process.
3Loss of time
If conventional single-step cleaning is used, then process time is reduced, but metal residues react with oxygen causing manufacturing defects
Solution Approach 1:
The cleaning process is segmented into multiple sequential steps: a first cleaning step that removes organic residues, followed by a second cleaning step that removes inorganic metal residues. This segmentation allows each step to be optimized for its specific function, ensuring complete residue removal and preventing reactions with oxygen, thereby improving manufacturing reliability without excessive time penalty.
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 method effectively removes reactive metal residues, preventing diffusion and ensuring the stability of interconnect structures, thereby enhancing the reliability and efficiency of semiconductor device fabrication.
Implementation Method 1
a second chemical containing fluorine or chlorine is applied to convert metal residues into stable metal fluorides or chlorides
Data Source
AI summary
A semiconductor structure includes a substrate, a conductive feature over the substrate, a dielectric layer over the conductive feature and the substrate, and a structure disposed over and electrically connected to the conductive feature. The structure is partially surrounded by the dielectric layer and includes a first metal-containing layer and a second metal-contain layer surrounded by the first metal-containing layer. The first and the second metal-containing layers include different materials. A lower portion of the first metal-containing layer includes a transition metal or a transition metal nitride and an upper portion of the first metal-containing layer includes a transition metal fluoride or a transition metal chloride.