Voltage contrast inspection of deep trench isolation
View Patent ↗A method including forming a first test structure and a second test structure in electrical contact with an inner buried plate and an outer buried plate, respectively, where the first and second test structures each comprise a deep trench filled with a conductive material, and measuring the voltage of the inner buried plate and the outer buried plate immediately after the formation of a deep trench isolation structure, where the inner buried plate and the outer buried plate are positioned on opposite sides of the deep trench isolation structure.
1. A method comprising:
forming a first test structure and a second test structure in electrical contact with an inner buried plate and an outer buried plate, respectively, wherein the first and second test structures each comprise a deep trench filled with a conductive material; and
measuring a voltage of the inner buried plate and the outer buried plate immediately after formation of a deep trench isolation structure, wherein the inner buried plate and the outer buried plate are positioned on opposite sides of the deep trench isolation structure.
2. The method of claim 1 , further comprising:
comparing a voltage measurement of the inner buried plate with a voltage measurement of the outer buried plate; and
determining the integrity of the deep trench isolation structure based on the voltage measurements of the inner buried plate and the outer buried plate.
3. The method of claim 1 , wherein measuring the voltage of the inner buried plate and the outer buried plate comprises;
using an inspection scanning electron microscope to measure electron emission.
4. The method of claim 1 , wherein the deep trench isolation structure completely surrounds the inner buried plate and electrically isolates the inner buried plate from the outer buried plate.
5. The method of claim 1 , wherein both the first test structure and the second test structure are each formed in recesses having substantially similar depths and substantially similar widths.
6. The method of claim 1 , wherein measuring the voltage of the inner buried plate and the outer buried plate comprises:
grounding the deep trench isolation structure by electrically connecting it to a ground structure.
7. The method of claim 1 , wherein the first test structure, the second test structure, and the deep trench isolation structure each comprise a recess lined with a dielectric material and filled with the conductive material.
8. The method of claim 1 , wherein the first test structure, the second test structure, and the deep trench isolation structure each comprise substantially similar structures with different dimensions, the deep trench capacitor being wider than both the first and second test structures.