Dual-Sided Transistor Contacts With Interfacial Layer for Low Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High contact resistances on the backside contacts to the source/drain (S/D) region in transistor devices lead to reduced drive currents, limiting the performance of dual-sided metallization schemes.
Innovation Solution
An interfacial layer with low resistivity, such as silicon or silicon and carbon with high active dopant concentration, is deposited between the bottom surface of the S/D region and the backside contact to reduce contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If dual-sided metallization scheme is used to contact S/D regions from top and bottom surfaces, then capacitance between metal lines is decreased, but contact resistance increases due to poor or non-ohmic contact between backside metal and S/D regions
Solution Approach 1:
An interfacial layer is introduced between the backside metal contact and the source/drain region to serve as an intermediary that improves contact quality. This layer, composed of materials such as silicon, silicon-germanium, or silicon-carbon with high doping concentrations, facilitates better electrical contact and transforms the non-ohmic contact into a more reliable ohmic contact, thereby reducing contact resistance while maintaining the dual-sided metallization configuration
Solution Approach 2:
The electrical parameters of the contact interface are modified by introducing the interfacial layer with specific material properties and high doping concentrations. This changes the contact characteristics from poor/non-ohmic to improved/ohmic, enabling the backside metal contact to achieve lower contact resistance and enhance drive current while preserving the capacitance benefits of dual-sided metallization
2Device complexity
If backside metal contact is made directly to S/D regions, then device structure is simplified, but drive current is reduced due to high contact resistance
Solution Approach 1:
The interfacial layer acts as a mediator between the backside metal contact and the source/drain region, enabling improved electrical contact without significantly complicating the device structure. This additional layer is integrated into the existing fabrication process and provides the necessary electrical interface to enhance drive current while maintaining structural simplicity
Solution Approach 2:
The contact structure is formed as a composite system comprising the backside metal contact, the interfacial layer with high doping concentration, and the source/drain region. This composite structure combines the advantages of different materials to achieve low contact resistance and enhanced drive current while keeping the overall device structure relatively simple and compatible with standard fabrication processes
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 use of an interfacial layer significantly reduces contact resistance, enhancing drive current and improving the overall performance of transistor devices with dual-sided metallization.
Implementation Method 1
An interfacial layer with low resistivity, such as silicon or silicon and carbon with high active dopant concentration, is deposited between the bottom surface of the S/D region and the backside contact to reduce contact resistance
Data Source
AI summary
Embodiments disclosed herein include transistor devices and methods of making such devices. In an embodiment, the transistor device comprises a stack of semiconductor channels with a first source/drain region on a first end of the semiconductor channels and a second source/drain region on a second end of the semiconductor channels. In an embodiment, the first source/drain region and the second source/drain region have a top surface and a bottom surface. In an embodiment, the transistor device further comprises a first source/drain contact electrically coupled to the top surface of the first source/drain region, and a second source/drain contact electrically coupled to the bottom surface of the second source/drain region. In an embodiment, the second source/drain contact is separated from the second source/drain region by an interfacial layer.