Semiconductor Floating Gate Spacer Overlap for Coupling Ratio
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Solution Overview
Problem
The complexity of fabricating semiconductor devices with nonvolatile memory, logic transistors, and resistors separately using different masks and processes, along with the need to enhance the coupling ratio of control and floating gates to reduce operating voltage and power consumption in nonvolatile memory.
Innovation Solution
A semiconductor device structure comprising a semiconductor substrate, a tunnel dielectric, a floating gate, a control gate with an insulation layer, and a spacer that overlaps the top surface of the floating gate, enhancing the coupling ratio by varying the widths of the floating and control gates to reduce operating voltage and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nonvolatile memory and logic transistors are fabricated separately with different masks and processes, then each component can be optimized independently, but the fabrication process complexity increases significantly
Solution Approach 1:
The patent merges the fabrication processes for nonvolatile memory and logic transistors into a unified process. The same mask patterns and deposition steps are used to form both the control gate of the memory device and the gate electrode of the logic transistor, eliminating the need for separate fabrication sequences while maintaining the ability to optimize both component types
Solution Approach 2:
The control gate structure serves dual functions: it acts as the control electrode for the nonvolatile memory device and simultaneously forms the gate electrode for the logic transistor. This multi-functional design allows a single structure to fulfill multiple circuit roles, simplifying the overall device architecture and fabrication process
2Use of energy by moving object
If the coupling ratio between control gate and floating gate is increased, then operating voltage and power consumption are reduced, but the device structure becomes more complex
Solution Approach 1:
The control gate of the nonvolatile memory and the gate electrode of the logic transistor are merged into a single continuous conductive structure. This merging increases the effective coupling area between the control gate and floating gate, enhancing the coupling ratio without requiring additional separate gate structures or complex multi-layer configurations
Solution Approach 2:
The unified control gate structure performs multiple functions simultaneously: it controls the nonvolatile memory device, serves as the gate electrode for the logic transistor, and provides the necessary coupling to the floating gate. This multi-functionality achieves high coupling ratio without adding structural complexity
3Manufacturing precision
If multiple separate fabrication processes are used for memory and logic components, then each component achieves design specifications, but manufacturing time and productivity are reduced
Solution Approach 1:
The patent combines multiple fabrication steps into a single integrated process sequence. The same photolithography, deposition, and etching steps that define the memory device features also define the logic transistor features, doubling the fabrication throughput for both component types without sacrificing dimensional precision or material quality
Data Source
AI summary
A method for fabricating a semiconductor device includes the steps of providing a semiconductor substrate; forming a tunnel dielectric on the semiconductor substrate; forming a floating gate on the tunnel dielectric; forming an insulation layer conformally disposed on the top surface and the sidewall surface of the floating gate; forming a control gate disposed on the insulation layer and the floating gate; and forming a spacer continuously distributed on the sidewall surfaces of the floating gate and the control gate, where the spacer overlaps portions of the top surface of the floating gate.