Etch
In semiconductor manufacturing, the etch process creates patterned features on the wafer by selectively removing material. Integrated circuit manufacturing typically requires that the wafer undergo multiple patterning cycles, where conductor and dielectric features are etched according to the pattern defined at the preceding photolithography step.
Industry Challenges
New technologies such as multi-patterning, 3D devices, and multi-layer film stacks are introducing a significant increase in etch process complexity. The transition to high aspect ratio, 3D transistor design requires tight control over the vertical profile to ensure sufficient and uniform device performance. Combined with shrinking feature sizes, this dictates angstrom-level etch uniformity across the wafer and in etch chamber-to-chamber matching, which in turn requires sub-angstrom metrology precision.
Non-destructive metrology of next-generation vertical memory is also becoming a critical need for etch process control. The thick alternating-layer stacks contain buried features and require precision etching of high aspect ratio contacts. Measuring these complex structures requires optical sensitivity to variation in very small profile features, together with advanced optical CD modeling to account for light interaction with the entire vertical memory structure.
Nova’s Solutions
Nova’s in-line optical metrology technologies offer a wide range of application solutions for current and next-generation etch challenges. Our stand-alone scatterometry platforms offer high performance solutions with maximum application flexibility. Such performance is needed for extremely difficult 3D applications such as the channel cavity etch measurement, where multiple critical parameters such as cavity CD, depth, and proximity must be measured. Nova also offers Integrated Metrology (IM) solutions for complex etch applications that require wafer-to-wafer or within-wafer feedforward (FF) or feedback (FB) control.
By maximizing the extraction of information from optical spectra, our NovaFit solutions can be used to extend our optical metrology capabilities by minimizing the effects of structural complexity and providing a direct link to reference metrology, such as electrical test measurements.
Nova’s in-line x-ray-based metrology solutions complement our optical techniques by leveraging unique strengths to extract post-etch dimensional information from structures. For example, our low-energy x-ray fluorescence (LE-XRF) technology can provide critical dimension (CD) information by quantifying the change in critical atomic species present in post-etch structures, such as Magnetic Tunnel Junction (MTJ) pillars found in Magnetic Random Access Memory (MRAM) devices.
For some of the most challenging etch applications, our hybrid metrology solutions combine the strengths of two or more metrology technologies to provide results superior to what each technology can obtain individually.
