APPLICATION OF THE ATOMIC-FORCE MICROSCOPE TO INTEGRATED-CIRCUIT FAILURE ANALYSIS

In IC research centers over the past two years, the Atomic Force Micro scope (AFM) has become a fairly common tool. Nondestructive imaging wi th nanometer resolution on uncoated samples in ambient conditions is p roving to have a wide range of applications in IC research. Also, duri ng this same period important advances have been made in scanning prob e microscopy, particularly relating to atomic force probes. AFM techno logy has now found acceptance in IC manufacturing as well as research. These new advances include: large sample (full wafer) capability, sha rper probe tips capable of measuring sidewalls as steep as 15 degrees from the vertical, noncontact topography measurements, frictional-forc e measurements, and cross-section analysis. True three-dimensional nan ometer-scale metrology can now be applied to process control and failu re analysis. Some uses and applications to semiconductors are (1) surf ace roughness measurement of polished silicon wafers for gate oxide pe rformance improvements, (2) surface roughness of deposited layers, (3) grain-size measurement, (4) depth measurement for etcher control, (5) step-height measurement, (6) gate-oxide integrity, (7) deposited laye r integrity over lines, (8) monitoring the effectiveness of cleaning s teps, (9) cross-section imaging, (10) high-resolution imaging for proc ess inspection, (i 1) planarization quality, (12) phase-shift mask dev elopment, (13) chrome photomasks - defect imaging and sizing, line-edg e quality, (14) defect imaging and sizing, and (15) spin-on glass cure and pore-size process studies