Accurate capacitance measurement for ultra large scale integrated circuits
First Claim
1. A test structure formed on a semiconductor substrate for measuring the parasitic capacitance between a via and adjacent conductive features of a semiconductive device, said test structure comprising:
- said semiconductor substrate;
a first conductive element having a first regularly repeating pattern, formed in a first metal layer over the substrate;
a second conductive element having a second regularly repeating pattern, formed in the first metal layer over the substrate and electrically isolated from the first conductive element;
a third conductive element, having a third regularly repeating pattern, formed in a second metal layer over the substrate;
a fourth conductive element, having a fourth regularly repeating pattern, formed in the second metal layer and electrically isolated from the third conductive element, wherein said respective first, second, third, and fourth regularly repeating patterns comprise a comb structure;
a first pattern of regularly spaced vias electrically connecting the first and fourth conductive elements; and
a second pattern of regularly spaced vias electrically connecting the second and third conductive elements.
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Abstract
Test structures and methods for measuring contact and via parasitic capacitance in an integrated circuit are provided. The accuracy of contact and via capacitance measurements are improved by eliminating not-to-be-measured capacitance from the measurement results. The capacitance is measured on a target test structure that has to-be-measured contact or via capacitance. Measurements are then repeated on a substantially similar reference test structure that is free of to-be-measured contact or via capacitances. By using the capacitance measurements of the two test structures, the to-be-measured contact and via capacitance can be calculated.
55 Citations
11 Claims
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1. A test structure formed on a semiconductor substrate for measuring the parasitic capacitance between a via and adjacent conductive features of a semiconductive device, said test structure comprising:
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said semiconductor substrate; a first conductive element having a first regularly repeating pattern, formed in a first metal layer over the substrate; a second conductive element having a second regularly repeating pattern, formed in the first metal layer over the substrate and electrically isolated from the first conductive element; a third conductive element, having a third regularly repeating pattern, formed in a second metal layer over the substrate; a fourth conductive element, having a fourth regularly repeating pattern, formed in the second metal layer and electrically isolated from the third conductive element, wherein said respective first, second, third, and fourth regularly repeating patterns comprise a comb structure; a first pattern of regularly spaced vias electrically connecting the first and fourth conductive elements; and a second pattern of regularly spaced vias electrically connecting the second and third conductive elements. - View Dependent Claims (2, 3, 4, 5)
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6. A test structure formed on a semiconductor substrate for measuring the parasitic capacitance between a via and adjacent conductive features of a semiconductive device, said test structure comprising:
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a grid of equally spaced conductive elements, a first plurality of the conductive elements being formed in a first plane, being substantially aligned in a first direction, and being electrically connected to one another; a second plurality of the conductive elements being formed in the first plane, being substantially aligned in the first direction, being electrically connected to one another, and being electrically isolated from the first plurality of conductive elements; a third plurality of the conductive elements being formed in a second plane, above the first plane, being substantially aligned in a second direction, and being electrically connected to one another; a fourth plurality of the conductive elements being formed in the second plane, being substantially aligned in the first direction, and being electrically connected to one another, and being electrically isolated from the third plurality of conductive elements; a first plurality of vias electrically connecting the first plurality of conductive elements with the fourth plurality of conductive elements at points where the fourth plurality of conductive elements overlaps the first plurality of conductive vias; a second plurality of vias electrically connecting the second plurality of conductive elements with the third plurality of conductive elements at points where the third plurality of conductive elements overlaps the second plurality of conductive vias; a first test probe pad connected to the first and fourth plurality of conductive elements; and a second test probe pad connected to the second and third plurality of conductive elements. - View Dependent Claims (7, 8, 9, 10, 11)
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Specification