Large-Surface VBPR Contact Structure for Robust BPR Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In semiconductor device design, particularly at advanced technology nodes, aligning and landing the Backside Power Rail (BPR) to the Via to Buried Power Rail (VBPR) is challenging due to small contact areas, leading to high contact resistance and complex process integration.
Innovation Solution
A semiconductor device structure is developed with a contact comprising a first section on the front side of a source or drain and a second section extending to the backside, featuring a via with a smaller width and a connection area with a larger width, which is curved to increase the contact area with the backside power rail, reducing resistance and simplifying alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a small contact area is used for VBPR alignment, then the device size is reduced, but contact resistance increases and alignment becomes more difficult
Solution Approach 1:
The patent extends the contact structure from a single-plane via to a three-dimensional structure that penetrates through the substrate thickness, creating multiple contact interfaces (front side contact section, intermediate connection area, and backside contact section). This dimensional transition increases the effective contact area and reduces contact resistance without increasing the planar footprint.
Solution Approach 2:
The contact structure is nested within the substrate thickness, with the via penetrating through the substrate and the connection area expanding within the substrate volume. This nested configuration allows the contact to occupy three-dimensional space efficiently, providing large contact area while maintaining compact device dimensions.
2Area of stationary object
If a small contact area is used for VBPR alignment, then the device size is reduced, but alignment precision becomes more difficult to achieve
Solution Approach 1:
By transitioning from two-dimensional planar alignment to three-dimensional alignment through substrate penetration, the patent provides additional alignment degrees of freedom. The front side contact section and backside contact section can be aligned independently, and the connection area provides a transition zone that tolerates minor misalignments.
Solution Approach 2:
The connection area acts as an intermediary between the front side contact section and the backside contact section. This intermediate region provides a transition zone that facilitates alignment by allowing gradual matching of the contact interfaces, reducing the stringency of alignment requirements.
3Ease of manufacture
If a via with uniform width is used, then the manufacturing process is simpler, but contact resistance is higher due to smaller cross-sectional area
Solution Approach 1:
The contact structure employs varying cross-sectional dimensions at different locations: a narrower via section for precise alignment and a broader connection area for reduced contact resistance. This local quality variation optimizes both alignment precision and electrical performance without significantly complicating the manufacturing process.
Data Source
AI summary
A semiconductor device comprising a contact comprising a first section and a second section; wherein the first section of the contact is located on a front side of a source or drain; wherein the second section extends from the front side of the source or drain to a backside of the source or drain; wherein the second section of the contact is comprised of a via and a connection area; wherein the via has a first width and the connection area has a second width, and wherein the second width is larger than the first width.