Photonic structures and integrated device for detecting and analyzing molecules
System and methods for analyzing single molecules and performing nucleic acid sequencing. An integrated device may include multiple pixels with sample wells configured to receive a sample, which when excited, emits radiation. The integrated device includes a surface having a trench region recessed from a portion of the surface and an array of sample wells, disposed in the trench region. The integrated device also includes a waveguide configured to couple excitation energy to at least one sample well in the array and positioned at a first distance from a surface of the trench region and at a second distance from the surface in a region separate from the trench region. The first distance is smaller than the second distance. The system also includes an instrument that interfaces with the integrated device. The instrument may include an excitation energy source for providing excitation energy to the integrated device by coupling to an excitation energy coupling region of the integrated device.
1. A method of forming an integrated device comprising:
forming a waveguide over a substrate;
forming a top cladding over the waveguide;
forming a trench region in the top cladding;
forming a metal layer on a surface of the top cladding; and
forming at least one sample well at a bottom surface of the trench region proximate to the waveguide.
2. The method of claim 1 , further comprising planarizing the top cladding to a distance from the surface of the top cladding to the waveguide.
3. The method of claim 2 , wherein the distance between the surface of the top cladding to the waveguide at a location within the trench region is between 150 nm and 600 nm.
4. The method of claim 1 , wherein forming the at least one sample well comprises selectively etching the metal layer to form openings that extend to the top cladding layer.
5. The method of claim 4 , wherein selectively etching the metal layer comprises:
selectively etching the metal layer using a photoresist mask; and
selectively etching the top cladding using a photoresist mask or a hard mask.
6. The method of claim 1 , wherein forming the at least one sample well comprises performing a timed etch of the top cladding.
7. The method of claim 1 , wherein forming the at least one sample well comprises:
forming at least one etch stop layer on the top cladding;
forming a dielectric layer over the top cladding and the at least one etch stop layer; and
removing the dielectric layer at locations that overlap with the at least one etch stop layer to expose the at least one etch stop layer.
8. The method of claim 1 , further comprising forming a spacer on at least a portion of a sidewall of a sample well of the at least one sample well.
9. The method of claim 8 , wherein forming the spacer is performed with an atomic layer deposition (ALD) process.
10. The method of claim 8 , wherein forming the spacer comprises etching the spacer from a surface of the sample well proximate the waveguide.