Backside-Patterned Nanostructured Lens in BSI CMOS Sensors

This invention introduces a novel approach to enhancing backside-illuminated (BSI) Complementary Metal-Oxide-Semiconductor (CMOS) sensors by integrating patterned nanostructured lens elements, such as metalenses, directly into the backside silicon layer or additional material layers. Unlike conventional microlens arrays, these nanostructured lenses improve light collection efficiency, simplify sensor design, and reduce system complexity by eliminating the need for external microlenses and color filters. The fully CMOS-compatible fabrication process ensures seamless integration within standard foundry workflows, enabling scalable production for high-performance imaging applications.

Background: 
Backside-illuminated (BSI) CMOS sensors are widely used in imaging applications due to their superior light sensitivity and efficiency compared to front-side-illuminated (FSI) sensors. However, traditional BSI CMOS designs rely on external microlens arrays to focus light onto photodiodes, which introduces additional fabrication steps and alignment challenges. Additionally, separate color filters are required to achieve spectral selection. This invention overcomes these limitations by incorporating nanostructured lens elements directly into the backside silicon layer of the sensor. These lenses function both as light-focusing elements and color filters, thereby reducing manufacturing complexity and improving sensor performance.

Applications:

• Consumer electronics (smartphones, tablets, cameras)
• Industrial imaging and machine vision
• Automotive imaging and advanced driver-assistance systems (ADAS)
• Medical imaging and life sciences

Advantages: 

• Simplified Manufacturing: Eliminates the need for separate microlens arrays and color filters, reducing production costs and complexity
• Enhanced Performance: Improves photon collection efficiency, alignment accuracy, and overall imaging quality
• Scalability: Fully compatible with CMOS foundry processes, enabling cost-effective large-scale production
• Optimized for BSI Sensors: Takes advantage of BSI architecture for minimal light obstruction and enhanced image clarity