Spectral filter, and image sensor and electronic device including the spectral filter

A method of manufacturing a spectral filter, the method comprising:

• forming a first etch stop layer and a first dielectric layer, in this order, on a lower reflective layer;
• etching a part of the first dielectric layer to expose a part of the first etch stop layer;
• forming a second etch stop layer and a second dielectric layer, in this order, on the exposed part of the first etch stop layer and on the first dielectric layer;
• etching a part of the second dielectric layer to expose a part of the second etch stop layer;
• wherein at least a top of the second dielectric layer and a top of the exposed part of the second etch stop layer form respective boundaries of a first cavity and a second cavity having different thicknesses from each other;
• and
• forming an upper reflective layer on the first cavity and the second cavity

An image sensor comprising:

• a spectral filter;
• and
• a pixel array receiving light transmitted through the spectral filter,
• wherein the spectral filter comprises:
• a plurality of first reflective layers spaced apart from each other and facing each other;
• and
• at least a first cavity and a second cavity provided between the plurality of first reflective layers, wherein the first cavity has a different thickness than the second cavity, a thickness of the first cavity determined according to a first center wavelength, and a thickness of the second cavity determined according to a second center wavelength,
• wherein each of the first cavity and the second cavity includes a plurality of etch stop layers having a constant total thickness and the first cavity has one or more dielectric layers having a first total thickness, and the second cavity has one or more dielectric layers having a second total thickness, wherein the first total thickness and the second total thickness differ from each other according to the first center wavelength of the first cavity and the second center wavelength of the second cavity.