Dipole-Forming Gate Layers for MOSFET Threshold Voltage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for controlling the threshold voltage of metal-oxide-semiconductor field-effect transistors (MOSFETs) are inadequate for advanced channel dimensions below 5 nm, requiring improved integration-compatible techniques to enhance performance and energy efficiency.
Innovation Solution
A semiconductor processing system employing a cyclical deposition process with alternating precursor pulses forms a dipole-forming layer on a substrate, using different elements and reactants to create a thermally stable and etch-resistant layer that controls the threshold voltage of MOSFETs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If interface dipole engineering is used to control threshold voltage in MOSFETs with channel dimensions below 5 nm, then performance and energy efficiency are improved, but manufacturing precision and process control become more difficult
Solution Approach 1:
The dipole-forming layer is segmented into multiple sub-layers with different elements (first element from first precursor, second element from second precursor) deposited in alternating pulses. This segmentation allows independent control of each sub-layer's composition and thickness, enabling precise overall threshold voltage control while maintaining manufacturability through modular deposition processes.
Solution Approach 2:
The invention changes physical and chemical parameters during deposition by alternating between different precursors with distinct electronegativities. Each precursor pulse modifies the layer's compositional parameters, and by controlling pulse duration, temperature, and precursor concentration, the dipole moment and resulting threshold voltage can be precisely tuned without compromising process control.
2Reliability
If a dipole-forming layer is formed using cyclical deposition with alternating precursors, then threshold voltage control is achieved, but device complexity increases
Solution Approach 1:
The cyclical deposition process serves multiple functions simultaneously: it deposits the dipole-forming layer, controls element distribution, adjusts compositional ratios, and manages layer thickness all through a single integrated process sequence. This multi-functionality reduces the need for separate processing steps, thereby managing device complexity while achieving precise threshold voltage control.
Solution Approach 2:
The invention employs periodic alternating pulses of different precursors to build the dipole-forming layer. This periodic deposition creates a structured multilayer architecture where each cycle contributes to the overall dipole moment. The regularity of the periodic action simplifies process control and modeling, counterbalancing the increased structural complexity with predictable, repeatable manufacturing.
3Reliability
If interface dipole engineering is implemented, then effective work function modulation is improved, but process compatibility with current integration flows becomes challenging
Solution Approach 1:
The dipole-forming layer is applied locally at the critical interface region where work function modulation is needed, rather than modifying the entire device structure. By concentrating the dipole-forming materials and deposition processes at the specific metal gate-dielectric interface, the invention achieves effective work function modulation while minimizing disruption to other parts of the integration flow.
Solution Approach 2:
The dipole-forming layer is deposited in advance as part of the gate stack formation process, before subsequent integration steps. This preliminary action embeds the threshold voltage control functionality into the base structure early in the manufacturing sequence, allowing later process steps to proceed without modification and ensuring compatibility with existing integration flows.
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 method allows precise control of threshold voltage with minimal impact on equivalent oxide thickness, enabling efficient integration into advanced transistor designs.
Implementation Method 1
a cyclical deposition process comprising one or more super cycles, wherein ones from the one or more super cycles comprise sequentially executing a first sub cycle and a second sub cycle; wherein the first sub cycle comprises a first precursor pulse that comprises operating the one or more reaction chamber valves to expose the substrate to the first precursor; wherein the second sub cycle comprises a second precursor pulse that comprises operating the one or more reaction chamber valves to expose the substrate to the second precursor; thereby forming a dipole-forming layer on the substrate
Implementation Method 2
Interface dipole engineering [IDE] is getting increasingly important for metal oxide field effect transistors (MOSFETs) as the channel dimensions are approaching below 5 nm. IDE improves the performance, modulating the effective work function (EWF) of metal gates, which can be employed to control the threshold voltage (Vt) of MOSFETs. Because of the different electronegativity of the various atoms in the interfacial layer, a dipole layer with an electric field can be formed altering the band alignment in the MOS stack.
Data Source
AI summary
Semiconductor processing apparatuses and methods for forming dipoles, dipole-forming layers, and work function metals for use in integrated circuits. Related structures, such as metal-insulator-metal capacitors are described as well. Exemplary methods include contacting a substrate with a first precursor and a second precursor that comprise different elements.