Semiconductor Contact Structure Using Epitaxial Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing contact process for semiconductor devices often increases contact resistance due to over-etching, which can etch through the metal silicide layer, leading to potential short circuits and reduced electrical connectivity.
Innovation Solution
A conductive epitaxial layer is formed within the contact hole to compensate for the removed metal silicide layer, using materials like Si1-x-yCxPy, GaN, n-type polysilicon, or p-type doped polysilicon, and filled with conductive materials such as tungsten, Al, or copper, surrounded by an insulating liner layer to prevent increased contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If over-etching is performed to remove the insulating liner layer at the bottom of the contact hole, then the electrical connection is improved, but the metal silicide layer is etched through causing contact resistance to increase
Solution Approach 1:
A conductive epitaxial layer is formed in advance within the contact hole before the insulating liner layer is etched away. This preliminary formation ensures that even if the metal silicide layer is etched through during over-etching, the conductive epitaxial layer remains to maintain low contact resistance and prevent electrical connection failure.
Solution Approach 2:
The conductive epitaxial layer serves as a cushioning layer that compensates for the potential loss of the metal silicide layer during over-etching. By having this conductive layer in place beforehand, the system is protected against the harmful effect of excessive etching, ensuring stable electrical performance.
2Reliability
If the insulating liner layer is completely removed to ensure good electrical connection, then conductivity is improved, but the process window for etching is reduced
Solution Approach 1:
The conductive epitaxial layer is formed in advance within the contact hole, creating a robust conductive pathway that can tolerate variations in etching conditions. This preliminary structure allows the etching process to have a wider process window since the conductive epitaxial layer ensures electrical connection even with etching variations.
Solution Approach 2:
The conductive epitaxial layer acts as a cushion against process variations during etching. By having this layer in place beforehand, the system can accommodate a broader range of etching conditions without compromising electrical performance, thereby expanding the process window.
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 maintains low contact resistance and expands the process window of the etching process, ensuring reliable electrical connections and preventing short circuits by compensating for the etched metal silicide layer.
Implementation Method 1
A conductive epitaxial layer is formed from the doped region in the contact hole
Data Source
AI summary
A contact process for a semiconductor device is described. A substrate having a doped region and a dielectric layer over the doped region is provided. A contact hole is formed through the dielectric layer and exposing the doped region. An insulating liner layer is formed a in the contact hole. A portion of the insulating liner layer at a bottom of the contact hole is etch-removed and over-etching is performed. A conductive epitaxial layer is formed from the doped region in the contact hole, and then the contact hole is filled with a conductive material.