Contact Barrier Layer Height Control for Low-Capacitance Contacts
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Solution Overview
Problem
As semiconductor devices are scaled down, there is a need to reduce capacitance while maintaining electrical stability between contacts, which existing methods struggle to achieve effectively.
Innovation Solution
A method of fabricating semiconductor devices involves forming an active pattern on a substrate, followed by the formation of source/drain patterns and contact holes. A contact barrier layer with a specific height is formed within the contact holes, and a passivation layer is applied. A mask layer is then used to expose portions of the contact barrier layer, which is subsequently reduced in height. Finally, a contact filling layer is formed to cover the contact barrier layer and fill the contact holes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pitch size of the semiconductor device is reduced to increase density, then the device scaling is improved, but the capacitance between contacts increases and electrical stability deteriorates
Solution Approach 1:
The contact structure is segmented into multiple functional layers: contact barrier layer (first height), passivation layer, and contact filling layer. This segmentation allows each layer to perform its specific function - the barrier layer prevents diffusion, the passivation layer provides insulation, and the filling layer provides electrical connection, thereby maintaining electrical stability in scaled devices
Solution Approach 2:
Different materials and structures are applied to different regions of the contact hole. The contact barrier layer has a first height while the contact filling layer has a second height, creating local variations in height and material properties. This local quality differentiation enables optimized electrical performance and reduced capacitance in specific contact regions
2Length of moving object
If the contact hole dimensions are reduced to maintain pitch scaling, then the device scaling is improved, but the electrical stability between contacts deteriorates
Solution Approach 1:
The contact structure uses composite materials including the contact barrier layer (e.g., titanium nitride), passivation layer (insulating material), and contact filling layer (conductive material such as tungsten). This composite structure maintains electrical stability in reduced-dimensional contacts by combining materials with complementary properties - barrier against diffusion, insulation for stability, and conduction for connectivity
3Device complexity
If conventional contact formation methods are used in scaled devices, then the manufacturing process is simple, but the capacitance reduction and electrical stability maintenance are insufficient
Solution Approach 1:
The contact barrier layer is formed in the contact hole before the contact filling layer is deposited. This preliminary action of creating the barrier layer with a specific first height establishes the foundation for subsequent layers, ensuring proper diffusion prevention and electrical stability are in place before final contact formation
Solution Approach 2:
The contact structure extends in the vertical dimension with different height levels - the contact barrier layer has a first height and the contact filling layer has a second height. This vertical dimensionality allows for optimized electrical performance by creating height differences that reduce capacitance while maintaining connectivity
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 improves the reliability of semiconductor devices by effectively reducing capacitance while maintaining electrical stability between contacts, thus addressing the scaling challenges in semiconductor technology.
Implementation Method 1
forming a passivation layer on the contact liner layer by oxidizing an upper surface of the contact liner layer in the contact hole
Data Source
AI summary
A method of fabricating a semiconductor device includes: forming an active pattern on a substrate, forming a source/drain pattern on the active pattern, forming a contact hole on the source/drain pattern, forming a contact barrier layer, which has an upper surface of a first height based on a bottom surface of the contact hole, in the contact hole, forming a passivation layer on the contact barrier layer in the contact hole, forming a mask layer on the passivation layer in the contact hole, removing an upper portion of the contact barrier layer so that an upper surface of the contact barrier layer has a second height lower than the first height, removing the passivation layer and the mask layer, and forming a contact filling layer, which covers the upper surface of the contact barrier layer and fills the contact hole, in the contact hole.