As critical dimensions shrink to fit advanced process generation requirements, line width roughness (LWR) has become
more and more important.
As design rules for semiconductor devices shrink, the line width roughness approaches the CD of the line itself. This
leads to poor device performance or even device failure. Thus, an accurate process monitor for LWR is required.
CD-SEM measurements for LWR require a reference to verify the accuracy. TEM has traditionally played this role.
However, its destructive nature, the errors induced by sample preparation, the limited data output and long turnaround
time make routine TEM measurement undesirable.
CD-AFM is a non-destructive technique that is able to generate highly accurate three-dimensional profiles of a sample
surface over tens of microns in the X and Y directions with sub-nanometer resolution.
In this paper we present results that show strong correlation between CD-SEM, TEM and inline CD-AFM based on
measurements of an OPC grating. Based on these results, CD-AFM has successfully replaced TEM as the reference
tool of choice for the R&D stage of a 45nm generation process.
To improve this situation, we have successfully adopted in-line X3D AFM to replace FA TEM as the verification tool in
the R&D stage of a 45nm generation process.
Chemical mechanical planarization (CMP) is a challenging process step for manufacturers implementing dualdamascene architectures at the 65 nm technology node. The polishing rate can vary significantly from wafer-to-wafer, across a single wafer, and across a single die, depending on factors including electroplate profile, slurry chemistry, pad wear, and underlying structure. The process is further complicated by the introduction of low-k dielectrics that have significantly different mechanical properties than the harder SiO<sub>2</sub> they replace. Picosecond ultrasonics is a nondestructive, small-spot method that can be used for in-line on-product monitoring of metal processes including copper CMP. In this paper we will present gauge-capable picosecond ultrasonic results on copper erosion test structures that also demonstrate excellent correlation with electrical test measurements and TEM results on 65 nm products.
Proc. SPIE. 6152, Metrology, Inspection, and Process Control for Microlithography XX
KEYWORDS: Oxides, Etching, Silicon, Nondestructive evaluation, Photodiodes, Atomic force microscopy, Scanning electron microscopy, Transmission electron microscopy, Process control, Semiconducting wafers
In the 65nm process development, use traditional top-view SEM and off-line XSEM and TEM to monitor STI profile became insufficient and inefficient. How to find one non-destructive, in-line monitor method to monitor trench depth, step height, and micro-planarity of STI (Shallow Trench Isolation) module profile become more important and
challenge than before. In-line AFM just cover this challenge during 65nm process development stage. In this paper, we report how to use in-line Atomic Force Microscope (AFM) technology to monitor STI module profile. Use of this technology on profile step-height and critical dimension in production facilities offers superior precision,
accuracy, non-destructive. high throughput and cost effective measurement result. Meanwhile, this paper outlines the implementation of AFM based metrology in an automatic production facility. We focus on the process step just after nitride removed, two key applications on this step, one is to monitor the step height difference and the other is to monitor divot depth at the interfaces height difference between the active area and the isolation area within the STI module.
Because the STI step height and divot after oxide fill might dominate the device threshold voltage value(Vt), we check the step height and divot of STI from SiN removed step to the step of thin gate oxide AEI. Then we check and trace where these defect occurred. We also measured 11 points on 300mn wafer to come out one wafer-level topographic chart to monitor its cross-wafer uniformity. Besides, we compared and correlated the AFM measurement result with FA TEM data. It shows good correlation result between X3D AFM and FA TEM. It means this in-line measurement method could efficient act as one important role on advanced STI module process development.
New Ga doped GeSb based phase-change materials are investigated. These materials possess good optical contrast at short wavelengths. Crystallization temperature increasing and grain size refinement are obtained by addition of Ga. More than 50 dB CNR and 25 dB erasability are measured in disks using blue laser.
Wafer bonding is an important fabrication step for some MEMS devices. ALignment of device patterns is vital for a successful bonding. When anisotropic wet etching is employed to fabricate microstructures on single crystal silicon wafers, the same mask may result in different etched patterns on different wafers. If the wafer pair for bonding are not matched well, the position and orientation of device patterns cannot be aligned simultaneously. This article presents a method for position and orientation alignment of the device patterns on wafer pairs. An offset angle indicating mark and a self-aligning bonding fixture are developed to satisfy the alignment requirement. The photomask for wet anisotropic etching contains patterns of indicating marks and wafer cutting targets. The indicating marks provide information of offset angles between device patterns and crystal planes after wet etching. Wafer pairs for bonding are matched with offset angles, depending on the device configuration. Simultaneously align the position and orientation is possible for the matched wafer pairs. Wafers are cut with the guide of cutting targets to ensure they have the same size. The bonding fixture consists of a steel frame and a pair of flat glass plates. The steel frame has a rectangular opening where the wafer pair are sandwiched between the glass plates. The wafer cutting process is the major source of misalignment in this bonding method.