Composite Mold Layer Structure to Prevent Capacitor Bowing
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Solution Overview
Problem
The increase in capacitor height in semiconductor devices due to reduced size requirements poses challenges in maintaining the required capacitance, leading to issues in forming capacitors effectively.
Innovation Solution
A semiconductor structure incorporating a composite mold layer comprising bowing sacrificial and bowing prevention layers to stabilize the mold structure, preventing bowing during etching and enabling efficient capacitor formation despite increased height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the capacitor size is reduced to achieve higher integration, then the integration density is improved, but the capacitor height must increase to maintain required capacitance, causing mold layer bowing and formation difficulties
Solution Approach 1:
The mold layer is segmented into multiple sub-layers (first mold layer, second mold layer, third mold layer) with different functions. The first mold layer provides structural support, the second mold layer prevents bowing during etching, and the third mold layer serves as a sacrificial layer. This segmentation allows each layer to be optimized for its specific function, resolving the contradiction between maintaining flatness and enabling high integration.
Solution Approach 2:
The patent employs a composite mold layer structure combining materials with different properties. The support layer uses materials with high mechanical strength, the bowing prevention layer uses materials resistant to etching-induced stress, and the sacrificial layer uses materials that can be selectively removed. This composite approach enables the mold structure to simultaneously maintain flatness and accommodate increased capacitor heights.
2Reliability
If the capacitor height is increased to maintain capacitance in smaller devices, then the required capacitance is maintained, but the mold layer experiences bowing during etching processes
Solution Approach 1:
The bowing prevention layer is positioned between the support layer and the capacitor structure to preemptively counteract the bowing forces that arise during etching. This layer applies a counteracting stress that prevents the mold layer from deforming, allowing the capacitor to achieve its required height and capacitance without compromising mold layer stability.
Solution Approach 2:
The sacrificial layer acts as an intermediary element that mediates between the mold structure and the capacitor formation process. This layer is temporarily present during critical formation stages to provide additional structural support and prevent bowing, then is selectively removed afterward. The intermediary enables the system to maintain stability during the process while achieving the required capacitor dimensions.
3Device complexity
If a single-layer mold structure is used, then the device structure is simple, but it cannot effectively prevent bowing during etching of tall capacitors
Solution Approach 1:
The mold structure is divided into three distinct layers, each with specific etching resistance properties. The first mold layer provides baseline support, the second mold layer offers enhanced bowing prevention during etching, and the third sacrificial layer can be selectively removed. This segmentation transforms a single complex function into multiple simpler, specialized layers, maintaining overall structural simplicity while improving etching precision.
Data Source
AI summary
A semiconductor structure of the inventive concepts includes a chip region comprising a plurality of semiconductor chips on the substrate; and a peripheral region at a periphery of the chip region, the peripheral region including a mold structure. The mold structure may include a base mold layer on the substrate, and a composite mold layer on the base mold layer, the composite mold layer comprising at least one bowing sacrificial layer and at least one bowing prevention layer.