Noncontact electrical metrology of Cu/low-k interconnect for semiconductor production wafers

Abstract

We have demonstrated a technique capable of in-line measurement of dielectric constant of low-k interconnect films on patterned wafers utilizing a test key of ~50×50 μm 2 in size. The test key consists of a low-k film backed by a Cu grid with >50% metal pattern density and <0.25 μm pitch, which is fully compatible with the existing dual-damascene interconnect manufacturing processes. The technique is based on a near-field scanned microwave probe and is noncontact, noninvasive, and requires no electrical contact to or grounding of the wafer under test. It yields <0.3% precision and ±2% accuracy for the film dielectric constant.

Near-Field Scanning Microwave Microscope for Interline Capacitance Characterization of Nanoelectronics Interconnect

“…Such a probe size is very well suited for precise and accurate dielectric constant measurements of 100 to 1000 nm thick films [11]. It also appears to be optimal for blanket low-k dielectric constant measurements on semiconductor production wafers [12] using test vehicles of about 50 × 50 μm 2 in size. In the present paper we demonstrate how the probe formed by a balanced parallel strip transmission line, unique in near-field scanning microwave microscopy, can be used for a noncontact measurement of a test vehicle's lumped element impedance (preliminary results were presented in [13]).…”

Improving Contact Resistance at the Nanotube−Cu Electrode Interface Using Molecular Anchors

“…Copper is currently the leading on-chip interconnect for integrated circuits using fabrication processes established in the 1990s that have been well-studied and improved since then. – Advantages of Cu are that have led to its extensive use in electronics is that it has the second highest electrical conductivity of pure metals and is abundant and inexpensive. Thus, it would be most desirable to connect Cu electrodes directly to the CNT or SGS.…”

Non-destructive complex permittivity measurement of low permittivity thin film materials

“…Recently, Talanov et al [9][10][11] have developed a new probe in order to provide a non-contact, non-invasive measurement system for low-k materials. The equipment requirements for this system, such as the tip-sample distance control mechanism to provide distances of 50-100 nm between tip and the sample, can prove costly.…”