U-Shaped Word Line Thickening Layer for Leakage Control
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Solution Overview
Problem
Semiconductor devices face challenges in scaling down while maintaining improved quality, yield, performance, and reliability, particularly due to issues like gate-induced drain leakage.
Innovation Solution
The semiconductor device incorporates a thickening layer with a U-shaped cross-sectional profile between the word line conductive and capping layers, enhancing the thickness of the word line dielectric layer and shielding it with a top capping layer to prevent recessing during etching or cleaning processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the word line dielectric layer is made thinner to scale down device dimensions, then device scaling is achieved, but gate-induced drain leakage increases
Solution Approach 1:
The word line dielectric layer is segmented into a first word line dielectric layer and a second word line dielectric layer with different dielectric constants. The first layer (closer to the channel) has higher dielectric constant than the second layer (closer to the control gate), creating a graded dielectric structure that reduces electric field penetration and minimizes gate-induced drain leakage while maintaining scaled dimensions.
Solution Approach 2:
Different regions of the word line dielectric structure use materials with different dielectric constants optimized for their specific functions. The region closer to the channel uses high-k material for strong field confinement, while the region closer to the control gate uses lower-k material to reduce parasitic capacitance and leakage, achieving local optimization of electrical properties.
2Ease of manufacture
If conventional etching processes are used without protection, then processing is simpler, but the word line dielectric layer and conductive layers are recessed causing short circuits
Solution Approach 1:
Capping layers are formed over the word line conductive layers and word line dielectric layers before etching processes. These capping layers serve as protective barriers that prevent recessing and damage to the underlying sensitive layers during subsequent etching and cleaning operations, ensuring reliable device formation.
Solution Approach 2:
The capping layers act as intermediary protective structures between the etching environment and the sensitive word line components. They withstand the etching process while protecting the dielectric and conductive layers underneath, preventing direct harmful interaction between the etchant and the device structures.
Data Source
AI summary
The present application discloses a semiconductor device and a method for fabricating the same. The semiconductor device includes a substrate; a word line structure including a word line dielectric layer in the substrate and including a U-shaped profile, a word line conductive layer on the word line dielectric layer and within the substrate, and a word line capping layer on the word line conductive layer; a top thickening layer including a U-shaped profile, between the word line conductive layer and the word line capping layer, and between the word line dielectric layer and the word line capping layer; a bottom capping layer on the substrate and adjacent to the word line dielectric layer; and a top capping layer covering the bottom capping layer and the word line structure. Top surfaces of the top thickening layer and the word line dielectric layer are coplanar and higher than the substrate.