Two-dimensional scanning capacitance microscopy measurements of cross-sectioned very large scale integration test structures

Abstract

Scanning probe technology, with its inherent two-dimensionality, offers unique capabilities for the measurement of electrical properties on a nanoscale. We have developed a setup which uses scanning capacitance microscopy (SCM) to obtain electrical information of cross-sectioned samples while simultaneously acquiring conventional topographical atomic force microscopy (AFM) data. In an extension of our work on very large scale integration cross sections, we have now obtained one-dimensional and two-dimensional SCM data of cross sections of blanket-implanted, annealed Si wafers as well as special test structures on Si. We find excellent agreement of total implant depth obtained from SCM signals of these cross-sectioned samples with conventional secondary ion mass spectrometry (SIMS) profiles of the same samples. Although no modeling for a direct correlation between signal output and absolute concentration has yet been attempted, we have inferred quantitative dopant concentrations from correlation to SIMS depth profiles obtained on the same sample. By these means of indirect modeling, we have found that our SCM technique is sensitive to carrier density concentrations varying over several orders of magnitude, i.e., <1×1015 to 1×1020 atoms/cm3, with a lateral resolution of 20–150 nm, depending on tip and dopant level.

Cross-Sectional Scanning Tunneling Microscopy

“…In this section we describe studies in which scanning tunneling microscopy and spectroscopy performed in the cross-sectional geometry have been used to delineate the electronic structure of Si MOSFET's with extremely high spatial resolution. Related techniques such as scanning capacitance microscopy, − scanning resistance microscopy, − Kelvin probe force microscopy, − and other scanning probe techniques − have also been used for extensive high-resolution characterization of Si pn junctions in both the planar and cross-sectional geometries. As feature sizes in state-of-the-art commercial microelectronic devices such as Si MOSFET's continue to shrink, scanning probe techniques are likely to assume increased importance for performing the nanometer-scale electronic and structural characterization of device structures and fabrication processes that will be essential for reliable, reproducible, and uniform fabrication of large-scale circuits based on ultrasubmicron devices.…”

Tip Characterization from AFM Images of Nanometric Spherical Particles

“…AFM is a powerful technique for studying the micro- and nanoscopic world because the measurement of three-dimensional surface topography is straightforward and can be applied under a wide variety of sample conditions. , As a result, AFM has found applications in fields ranging from semiconductor physics − to biology. − In addition, several variations on the imaging “mode” have been developed, enabling investigation of physical properties such as friction, , magnetism, , surface charge, , rigidity, , and capacitance. , …”

Metrology For Emerging Research Materials And Devices

“…Dynamic and time of flight Secondary Ion Mass Spectroscopy (SIMS) [5] and scanning capacitance techniques [8,9] offer some insight into dopant concentration and distribution within bulk materials. However, spatial resolution of these techniques appears to be insufficient to satisfy the characterization requirements projected for nanometer scale structures.…”