X-FAB Announces Industry’s First 4T CIS Process for High-Speed Applications Requiring Large Pixels

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BusinessWire: X-FAB Silicon Foundries introduces XS018, said to be the first specialized 0.18µm CMOS process for fast and large image sensor pixels. Unlike the 4T pixels used in consumer products such as mobile phones and digital cameras, which have small sizes, the new XS018 technology is said to be the first to support high-speed large pixels required for medical and scientific applications such as computer tomography and x-ray scanners for 3D images. The XS018 process supports pixel sizes up to 200µm x 200µm with high-speed reading capability. The charge transfer time can be as short as 20ns with almost no image lag. The low dark current of less than 5pA/cm² gives designers a high SNR that allows high DR designs.

XS018 has a 3.3V core that results in a very low mask count, reducing cost if 1.8V devices are not necessary. Optionally, it can be extended for higher integration by using a 1.8V module.

The new 4T pixel cells with pinned photo diodes offer lower dark current and lower noise than the 3T cells commonly used today for large pixel designs. The pinned photo diode available with four different pinning voltages and a 3.3V n-channel MOS transistor with five different options for low-threshold voltages can be used as a SF, RST device or row SEL device in the pixel. This flexibility allows for higher voltage swing as the SF, and higher floating diffusion voltage as the RST device, diminishing image lag and increasing transfer speed. The XS018 also offers a 3.3V low-noise buried n-channel transistor that can reduce pixel noise.

According to Detlef Sommer, Business Line Manager CMOS Sensors at X-FAB, “Our customers in the medical and scientific sectors require large pixels and often large dies to handle the high-speed optical sensing their applications demand. We are pleased to meet this need with our new XS018 CMOS image sensor process – the first to support 4-transistor large pixel designs. In addition, our proven stitching process supports large dies – up to one die per wafer – giving our customers a clear edge for their advanced designs.

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