Semiconductor Contact Hole Formation Using Barrier Layers
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Solution Overview
Problem
In semiconductor device manufacturing, particularly in gate-last processes, the formation of self-aligned contact holes is challenging due to the risk of short-circuits between the contact hole and the metal gate, exacerbated by misalignment during photolithography and etching, which compromises electrical performance and miniaturization requirements.
Innovation Solution
A semiconductor device structure and method involving multiple barrier layers and dielectric layers are used, where the etch rate of the third barrier layer is less than one-sixth of the first dielectric layer, and a self-aligned contact hole is formed through these layers to minimize exposure and risk of short-circuits, using fluorine-containing gases for etching, and the second dielectric layer is formed using spin-on-glass or flowable chemical vapor deposition processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a self-aligned contact hole is formed in a gate-last process, then the electrical performance is improved by avoiding heat exposure, but the risk of short-circuit between the contact hole and metal gate is aggravated due to misalignment
Solution Approach 1:
The patent introduces a barrier layer as an intermediary substance between the metal gate and the contact hole. This barrier layer physically separates the two conductive elements, preventing direct contact and thus eliminating the short-circuit risk while allowing the gate-last process benefits to be retained.
Solution Approach 2:
The barrier layer is formed before the contact hole is etched through. This preliminary action ensures that the protective barrier is already in place to prevent short-circuits during subsequent processing steps, addressing the alignment issue before it can cause problems.
2Length of moving object
If the contact hole is positioned close to the metal gate to meet miniaturization requirements, then the device size is reduced, but the short-circuit risk is aggravated
Solution Approach 1:
The barrier layer serves as a mediating structure that allows the contact hole to be positioned close to the metal gate for miniaturization while maintaining electrical isolation. The intermediary barrier enables tight spacing without compromising reliability.
3Manufacturing precision
If photolithography and etching processes are used to form the contact hole, then the manufacturing precision is improved, but misalignment may occur that aggravates the short-circuit risk
Solution Approach 1:
The barrier layer is deposited beforehand to provide a cushioning protective layer. Even if misalignment occurs during photolithography and etching, this pre-formed barrier layer acts as a safety margin that prevents the contact hole from directly contacting the metal gate, thus cushioning against the harmful effects of misalignment.
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 effectively prevents short-circuits and ensures satisfactory electrical performance and miniaturization of semiconductor devices by protecting the metal gates from etchants and heat, while allowing for the combination of gate-last processes with self-aligned contact hole fabrication.
Implementation Method 1
etching the dielectric layer to form the self-aligned contact hole
Implementation Method 2
the etch selectivity ratio between the SiN barrier layer and the dielectric layer may be substantially high
Implementation Method 3
the second dielectric layer is formed using spin-on-glass or flowable chemical vapor deposition processes
Implementation Method 4
the second dielectric layer is formed using spin-on-glass or flowable chemical vapor deposition processes
Data Source
AI summary
A semiconductor device includes a substrate, a first barrier layer disposed on the substrate, a first dielectric layer disposed on the first barrier layer, and a second barrier layer disposed on the first barrier layer. The semiconductor device further includes a third barrier layer and a first metal gate each being disposed between a first portion of the second barrier layer and a second portion of the second barrier layer. The first metal gate is disposed between the third barrier layer and the substrate. The semiconductor device further includes a second dielectric layer. The third barrier layer is disposed between the first metal gate and the second dielectric layer. The semiconductor device further includes a second metal gate. The semiconductor device further includes a contact hole positioned between the first metal gate and the second metal gate.