Contact etch stop layer for a pixel sensor

A method, comprising:

• depositing, based on providing gas flow of nitrogen trihydride (NH3) and silicon tetrahydride (SiH4) in a ratio of greater than approximately 70:1, a contact etch stop layer, comprising less than approximately 12 percent hydrogen, on a substrate,
• wherein depositing the contact etch stop layer comprises depositing contact etch stop layer material at a temperature of greater than approximately 600 degrees Celsius, and
• wherein depositing the contact etch stop layer material comprises depositing NH3 and SiH4 at a ratio of greater than approximately 70:1;
• depositing a silicon-based layer above the contact etch stop layer;
• forming a photodiode, having an upper surface with angles in a range of approximately 80 degrees to approximately 100 degrees, between within the silicon-based layer;
• and
• performing an etching operation to etch a trench, for a trench isolation structure, into the photodiode and the silicon-based layer until reaching a portion of the contact etch stop layer, wherein the portion of the contact etch stop layer is less than an entire thickness of the contact etch stop layer.

A method, comprising:

• depositing, based on providing gas flow of nitrogen trihydride (NH3) and silicon tetrahydride (SiH4) in a ratio of greater than approximately 70:1, a contact etch stop material, with a concentration of less than 12 percent hydrogen, on a substrate;
• depositing a dielectric layer on the contact etch stop material;
• depositing a silicon-based layer on the dielectric layer and above the contact etch stop material, wherein the silicon-based layer comprises one or more photodiodes having an upper surface with angles in a range of approximately 80 degrees to approximately 100 degrees;
• and performing an etching operation to etch one or more trenches, for one or more trench isolation structures, into the photodiodes and the dielectric layer until reaching a portion of the contact etch stop layer, wherein the portion of the contact etch stop layer is less than an entire thickness of the contact etch stop layer.