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Feature Depth Estimation Using Sheet Resistance Method

IP.com Disclosure Number: IPCOM000028110D
Original Publication Date: 2004-May-25
Included in the Prior Art Database: 2004-May-25
Document File: 1 page(s) / 24K

Publishing Venue

Siemens

Related People

Juergen Carstens: CONTACT

Abstract

For measuring the depth of semiconductor structures, usually techniques like Atomic Force Microscopy (AFM) or Physical Failure Analysis (PFA) are used. Here, a new method is proposed that can easily be applied to test structures with a fixed number of features. By measuring the electrical resistance between two termination points of the test structure, the average depth of the features can be estimated. To enable electrical continuity between the two electrical termination points, a thin, conformal and continuos conductive film is deposited. This can be achieved using e.g. Atomic Layer Deposition (ALD). An example of such a test structure is shown in Figure 1. If "A" is the area of cross-section of the conductive liner material, "r" its resistivity and "R" the measured sheet resistance of the test structure, the mean feature depth can be estimated using the following equation:

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S

Feature Depth Estimation Using Sheet Resistance Method

Idea: Srivatsa Kundalgurki, DE-Dresden

For measuring the depth of semiconductor structures, usually techniques like Atomic Force Microscopy (AFM) or Physical Failure Analysis (PFA) are used. Here, a new method is proposed that can easily be applied to test structures with a fixed number of features. By measuring the electrical resistance between two termination points of the test structure, the average depth of the features can be estimated. To enable electrical continuity between the two electrical termination points, a thin, conformal and continuos conductive film is deposited. This can be achieved using e.g. Atomic Layer Deposition (ALD).

An example of such a test structure is shown in Figure 1. If "A" is the area of cross-section of the conductive liner material, "r" its resistivity and "R" the measured sheet resistance of the test structure, the mean feature depth can be estimated using the following equation:

d = 0.5 * [((A*R)/(n*r)) - (2*t) - (L1 - (2*t)) - L2]

The thickness "t" of the conductive liner is determined by the deposition process, while the critical dimensions "L1" and "L2" as well as the cross-section "A" can be deduced by measuring the

corresponding dimensions on the upper side of the test structure using e.g. Scanning Electron Microscopy (SEM).

Figure 1:

t = Thickness of the conductive Liner. L1 = Bottom critical dimension (CD) of the deep feature.

L2 = Pitch of the test structure (dis...