Photo diode with dual backside deep trench isolation depth

#Many modern day electronic devices, such as digital cameras and video cameras, contain image sensors to convert optical images to digital data. To achieve this, an image sensor comprises an array of pixel regions. Each pixel region contains a photodiode configured to capture optical signals (e.g., light) and convert it to digital data (e.g., a digital image). Complementary metal-oxide-semiconductor (CMOS) image sensors are often used over charge-coupled device (CCD) image sensors because of their many advantages, such as lower power consumption, faster data processing, and lower manufacturing costs.

#Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

#FIG. 1 illustrates a cross-sectional view of some embodiments of an image sensor having a pixel region with a full backside deep trench isolation (BDTI) structure and a partial BDTI structure.

#FIG. 2A illustrates a top view of some embodiments of an image sensor having a plurality of pixel regions separated by full and partial BDTI structures.

#The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

#Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

#An image sensor may include a plurality of pixel regions arranged in an array having rows and columns. A first pixel region of the array comprises a first photodiode. In a complementary metal-oxide-semiconductor (CMOS) image sensor, a first transfer transistor is between the first photodiode and a floating diffusion (FD) node. The first photodiode is configured to convert incident light to charge carriers and the first transfer transistor is configured to transfer the charge carriers to the FD node. Adjacent to the first pixel region is a second pixel region. In a shared pixel layout structure, the second pixel region comprises a second transfer transistor arranged between a second photodiode and the FD node. The FD node is coupled to a plurality of transistors (e.g., a reset transistor, a source follower transistor, etc.) in a pixel device region.