Pre-Doped Sputter Targets for Low-Resistance Source/Drain Contacts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As integrated circuitry scales to smaller feature dimensions, the reduced contact area between source or drain regions and their corresponding contacts leads to increased contact resistance, negatively impacting transistor performance.
Innovation Solution
The formation of silicide, germanide, and/or germanosilicide regions between the source or drain regions and contacts, where the metals used for these regions are pre-doped with dopants to prevent dopant diffusion from the source or drain regions, maintaining satisfactory dopant concentrations and reducing contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If integrated circuitry is scaled to smaller feature dimensions, then transistor density is improved, but contact area between source/drain regions and contacts is reduced leading to increased contact resistance
Solution Approach 1:
The patent changes the chemical composition parameters of the contact region by forming silicide, germanide, or germanosilicide compounds. This transforms the contact material from pure metal to a compound material with optimized electrical properties, thereby reducing contact resistance despite reduced contact area due to scaling
Solution Approach 2:
The patent uses composite material structures where silicide, germanide, or germanosilicide regions are formed between the source/drain regions and the contacts. These composite materials combine the benefits of metal conductivity with semiconductor compatibility, providing low contact resistance in scaled devices
2Reliability
If metals are pre-doped with dopants to prevent dopant diffusion, then dopant concentration in source/drain regions is maintained, but process complexity increases
Solution Approach 1:
The patent applies preliminary doping to the metal layers before they react with the source/drain regions. By pre-doping the metals with dopants, the contact regions are prepared in advance to prevent dopant diffusion during subsequent annealing processes, thereby maintaining dopant concentration stability
Solution Approach 2:
The pre-doped metal layers act as intermediary regions between the source/drain regions and the external contacts. These intermediary layers prevent direct dopant diffusion pathways while maintaining electrical connectivity, thus stabilizing dopant concentrations in the source/drain regions
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 maintains satisfactory dopant concentrations in the source or drain regions, thereby reducing contact resistance and improving transistor performance by preventing substantial dopant diffusion during the annealing process.
Implementation Method 1
The sputter target includes a metal and a dopant. The sputter target is sputtered to deposit the metal on a substrate
Implementation Method 2
the annealing process, the one or more metals combine or otherwise react with the semiconductor material of the source or drain region
Implementation Method 3
dopant from the source or drain region may diffuse from the source or drain region into the silicide, germanide, and/or germanosilicide
Data Source
AI summary
An integrated circuit structure includes a source or drain region, and a contact coupled to the source or drain region. Sputter targets that include metals doped with the appropriate dopant types are used to deposit a conductive layer on the source or drain region that is annealed to form a region including metals and semiconductor materials between the source or drain region and the contact. A first dopant is within the source or drain region, and a second dopant is within the region. In one example, the first dopant is elementally different from the second dopant. In another example, the first dopant is elementally the same as the second dopant, wherein a concentration of the first dopant within a section of the source or drain region is within 20% of a concentration of the second dopant within the region.