FinFET Standard Cell Layout with Double Self-Aligned Contacts
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Solution Overview
Problem
The existing FinFET standard cell designs face challenges in reducing the area of the device while maintaining the integrity of the transistor properties, as the conventional double diffusion break process requires multiple dummy fins to prevent bridge connections between metal layers, which increases the overall size and affects device performance.
Innovation Solution
The FinFET standard cell with double self-aligned contacts incorporates a semiconductor substrate with a first metal gate and two second metal gates separated by a diffusion bonding hole and filling plug cap, along with self-aligned gate and diffusion bonding hole contacts, and a buffer layer to reduce the size of active and dummy fins, using tungsten or cobalt for the contacts and insulation materials for the cap layer, to prevent bridge connections and minimize area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conventional double diffusion break (DDB) process is used, then the transistor properties are maintained, but the area of the standard cell increases due to multiple dummy fins
Solution Approach 1:
The patent extracts and eliminates the dummy fins from the conventional DDB process structure. By removing the unnecessary dummy fins while retaining the essential transistor functionality through self-aligned contacts, the standard cell area is reduced without compromising transistor properties.
Solution Approach 2:
The patent transitions from a planar contact structure to a self-aligned contact structure that extends in the vertical dimension. The self-aligned contacts are positioned precisely over the active fins, utilizing the vertical stacking dimension to achieve separation and alignment without requiring additional horizontal space for dummy fins.
2Area of stationary object
If the size of active fin or dummy fin is reduced, then the standard cell area decreases, but bridge connection between metal layers occurs
Solution Approach 1:
The patent introduces self-aligned contacts as intermediary structures that precisely define the boundaries between active and dummy regions. These contacts act as mediators that maintain proper electrical isolation and prevent bridge connections between metal layers, even when the spacing between active fins is minimized.
Solution Approach 2:
The self-aligned contacts automatically position themselves in the correct locations through the self-aligned formation process. This self-service mechanism ensures that the contacts are precisely aligned with the active fins and properly separated from dummy fins, preventing bridge connections without requiring additional design constraints or larger dimensions.
3Reliability
If at least two dummy fins are required between adjacent active fin regions, then bridge connection is prevented, but the standard cell area increases
Solution Approach 1:
The patent extracts and removes the dummy fins from the structure entirely. By using self-aligned contacts to define the active regions and provide electrical isolation, the dummy fins become unnecessary and are eliminated, reducing the standard cell area while maintaining prevention of bridge connections.
Solution Approach 2:
The self-aligned contacts serve as precise copies or replicas of the active fin structures, positioned exactly where needed. This copying approach allows the contacts to inherit the alignment and spacing characteristics of the active fins, ensuring proper isolation without requiring separate dummy fin structures.
Data Source
AI summary
The present disclosure describes a fin field-effect transistor (FinFET) standard cell with double self-aligned contacts. The FinFET standard cell with double self-aligned contacts includes a self-aligned gate contact spanning over a diffusion bonding hole and a self-aligned diffusion bonding hole contact spanning over a gate, and the FinFET device further includes a cap layer between the two self-aligned contacts so as to separate the two self-aligned contacts, thereby further reducing the size of the active fin or a dummy fin so as to further reduce the area of the FinFET standard cell, to prevent a bridge connection between adjacent M0 structures like the M0A and M0P, thereby improving yield of manufacturing.