Test line structure for integrated chip comprising optical devices

A method for forming an integrated chip, comprising:

• performing an etching process on a semiconductor substrate to form a first optical test input/output (I/O) structure and a second optical test I/O structure in a semiconductor layer of the semiconductor substrate, wherein the semiconductor substrate comprises a base substrate and an insulator structure between the semiconductor layer and the base substrate, wherein the first and second optical test I/O structures are arranged in a test line region;
• forming one or more optical test devices on the semiconductor layer and within the test line region, wherein the one or more optical test devices are optically coupled between the first optical test I/O structure and the second optical test I/O structure;
• forming a plurality of first optical devices on the semiconductor layer and within a first device region adjacent to the test line region;
• forming an interconnect structure over the semiconductor substrate, wherein the interconnect structure comprises a plurality of conductive interconnects arranged in a dielectric structure;
• depositing a passivation structure over the interconnect structure;
• and
• forming a plurality of electrical I/O structures in the passivation structure and within the test line region, wherein a first lateral distance between the one or more optical test devices and a first electrical I/O structure in the plurality of electrical I/O structures is less than a second lateral distance between the first and second optical test I/O structures.

A method for forming an integrated chip, comprising:

• forming a plurality of first optical devices on a semiconductor substrate and within a first device region;
• forming a plurality of second optical devices on the semiconductor substrate and within a second device region;
• forming a plurality of optical input/out (I/O) structures on the semiconductor substrate and within a test line region spaced between the first device region and the second device region;
• forming a plurality of optical test devices on the semiconductor substrate and within the test line region, wherein the plurality of optical test devices are optically coupled to one or more of the optical I/O structures, wherein the plurality of optical test devices are formed concurrently with the plurality of first optical devices and the plurality of second optical devices, wherein the plurality of optical test devices comprises a modulator having a first doped region;
• depositing a dielectric structure over the semiconductor substrate;
• forming a plurality of conductive wires and a plurality of conductive vias in the dielectric structure;
• and
• forming a plurality of electrical I/O structures on the dielectric structure and within the test line region, wherein a first electrical I/O structure in the plurality of electrical I/O structures is electrically coupled to the first doped region.