Semiconductor Gate Spacer Prevents Wordline Leakage
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Solution Overview
Problem
Current flash memory manufacturing processes suffer from wordline leakage, leading to device failure and reduced yield due to surface area issues in the cell array area.
Innovation Solution
A semiconductor structure is designed with a gate structure including a floating gate, inter-gate dielectric layer, and control gate, where a first spacer is positioned on the sidewall of the control gate structure, covering the electrode, contact, and cap layers, effectively preventing diffusion and oxidation, thereby reducing wordline leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If self-aligned contact processes are used to reduce surface area in the cell array area, then the surface area of the cell array area is reduced, but wordline leakage occurs leading to device failure
Solution Approach 1:
A first spacer is introduced as an intermediary structure between the control gate structure and the contact layer. This spacer acts as a protective barrier that prevents direct interaction between the contact layer and the control gate electrode, thereby preventing wordline leakage while maintaining the self-aligned contact process benefits for reducing cell array surface area.
Solution Approach 2:
The harmful diffusion path is extracted or removed by introducing the first spacer that physically separates and isolates the contact layer from the control gate electrode. This extraction of the diffusion pathway prevents the leakage mechanism while preserving the compact cell array design.
2Ease of manufacture
If the contact layer is exposed during polysilicon deposition, then deposition can proceed, but oxidation and diffusion occur creating voids and seams
Solution Approach 1:
The first spacer is formed in advance before the polysilicon deposition process. This preliminary action creates a protective barrier that prevents oxidation and diffusion during the subsequent deposition steps, eliminating the need for complex protective measures while ensuring high manufacturing precision and reducing defect density.
Solution Approach 2:
The first spacer serves as an intermediary protective layer between the contact layer and the polysilicon deposition environment. This intermediary structure prevents harmful oxidation and diffusion processes during deposition, ensuring high manufacturing precision while maintaining ease of manufacture.
3Device complexity
If no protective structure is added to prevent wordline leakage, then device complexity remains low, but yield is reduced due to leakage failures
Solution Approach 1:
The gate structure is segmented by adding the first spacer as a distinct protective component. This segmentation creates a clear separation between the control gate electrode and the contact layer, providing targeted protection against wordline leakage while maintaining overall structural organization and achieving high manufacturing yield.
Solution Approach 2:
The first spacer is introduced as a simple intermediary structure that provides effective protection against wordline leakage. This single protective element significantly improves manufacturing yield without substantially increasing device complexity, as it integrates seamlessly with the existing self-aligned contact process.
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 semiconductor structure effectively prevents wordline leakage, reduces voids and seams during polysilicon deposition, and increases yield by isolating the contact layer from oxidation and diffusion, ensuring a stable and reliable semiconductor device.
Implementation Method 1
a first spacer is disposed on a sidewall of the control gate structure and covering the electrode, the contact layer and the cap layer
Implementation Method 2
effectively preventing diffusion and oxidation, thereby reducing wordline leakage
Data Source
AI summary
A semiconductor structure is provided. The semiconductor structure includes a substrate, a gate structure, and a first spacer. The gate structure includes a floating gate structure disposed on the substrate, an inter-gate dielectric layer disposed on the floating gate structure, and a control gate structure disposed on the inter-gate dielectric layer. The control gate structure includes an electrode layer disposed on the inter-gate dielectric layer, a contact layer disposed on the electrode layer, and a cap layer disposed on the contact layer. The first spacer is disposed on a sidewall of the control gate structure and covering the electrode, the contact layer and the cap layer. A bottom surface of the first spacer is positioned between a bottom surface and a top surface of the electrode layer.