Structure and method of advanced LCoS back-plane having highly reflective pixel via metallization
Processing methods may be performed to form a pixel material in a semiconductor substrate. The methods may include forming a lithographic mask overlying the semiconductor substrate. The lithographic mask may include a window. The method may include forming a via in the semiconductor substrate by a dry etch process through the window. The method may also include forming the pixel material by depositing a fill material in the via.
1. A semiconductor structure comprising:
a semiconductor substrate;
a metal layer overlying the semiconductor substrate;
a spacer layer overlying the metal layer;
a mirror layer overlying the spacer layer;
an optical stack overlying the mirror layer; and
a pixel material extending from the metal layer to the optical stack, the pixel material comprising a refractory material; and
a reflective cap overlying the pixel material, the reflective cap having a reflective surface substantially level with an upper surface of the optical stack.
2. The semiconductor structure of claim 1 , wherein the reflective cap comprises aluminum.
3. The semiconductor structure of claim 1 , wherein the reflective cap is characterized by a thickness, relative to the upper surface of the reflective cap, of at least 60 nm.
4. The semiconductor structure of claim 3 , wherein the reflective cap is characterized by a thickness, relative to the upper surface of the reflective cap, of less than 100 nm.
5. The semiconductor structure of claim 1 , wherein the reflective cap is characterized by an aspect ratio less than 1.
6. The semiconductor structure of claim 1 , further comprising a barrier layer overlying the reflective cap and the optical stack, the barrier layer comprising silicon carbon nitride.
7. The semiconductor structure of claim 1 , wherein the refractory material comprises one or more of tungsten, ruthenium, or tantalum nitride.
8. A semiconductor structure comprising:
a semiconductor substrate;
a metal layer overlying the semiconductor substrate;
a spacer layer overlying the metal layer;
a mirror layer overlying the spacer layer;
an optical stack overlying the mirror layer; and
a pixel material extending from the metal layer to the optical stack, the pixel material comprising a non-refractory material; and
a reflective cap overlying the pixel material, the reflective cap having a reflective surface substantially level with an upper surface of the optical stack.
9. The semiconductor structure of claim 8 , wherein the reflective cap comprises aluminum.
10. The semiconductor structure of claim 8 , wherein the reflective cap is characterized by a thickness, relative to the upper surface of the reflective cap, of at least 60 nm.
11. The semiconductor structure of claim 10 , wherein the reflective cap is characterized by a thickness, relative to the upper surface of the reflective cap, of less than 100 nm.
12. The semiconductor structure of claim 8 , wherein the reflective cap is characterized by an aspect ratio less than 1.
13. The semiconductor structure of claim 8 , further comprising a barrier layer overlying the reflective cap and the optical stack, the barrier layer comprising silicon carbon nitride.