FilmTek 2000M TSV - For Spectroscopic Reflectometry

FilmTek™ 2000M TSV is a fully automated metrology instrument that employs highly focused light at a perpendicular angle. It assesses film thickness, critical dimension (CD), Total Thickness Variation (TTV), high-aspect-ratio trenches, and through-silicon via (TSV) applications crucial for front-end and advanced packaging development.

2000M TSV is an invaluable tool for high-volume semiconductor manufacturing, MEMS foundries, R&D, and shared common development facilities due to its adaptability and broad application coverage in a single platform.

FilmTek 2000M TSV Delivers:

• Nanometer resolution with a high-resolution detector/spectrometer that can resolve extreme high-frequency oscillations from thick films.
• The patented signal collection and post-processing capabilities allow the instrument to measure thickness across a broad range, including rough metal substrates, from 5 nm to 350 µm.
• Small spot size down to 2 × 1 µm allowing for measurements of high aspect ratio (HAR) vias or films in tight spaces.

26-point patch plot of TSV depth variation across a 300 mm wafer. Image Credit: Bruker Nano Surfaces and Metrology

Delivering Application Flexibility

Film Thickness Measurements Using a Patented Optical Design for Collimated Light

Standard reflectometry techniques employ a highly concentrated laser beam to achieve a small measuring spot size. However, using a concentrated beam with a high numerical aperture for thick film applications can result in a wide range of reflected angles, causing destructive interference and incoherent reflectance.

The innovative optical design of the FilmTek 2000M TSV addresses this issue by generating a collimated beam with a small spot size. This design enables coherent measurements of thick and thin films. With the 2000M TSV, precise thickness measurements ranging from 5 nm to 350 μm are achievable, maintaining coherent reflectance even for very thick films due to a collimated beam and tiny spot size.

When paired with a high-resolution spectrometer, the 2000M TSV can effectively fit and model the high-frequency oscillations often observed in reflectance data.

Power spectral density (PSD) plot that enables fitting to yield improved thickness accuracy and repeatability. Inset: Measured and simulated reflectance spectra of ~100 μm photoresist on silicon, showing high-frequency oscillations. Image Credit: Bruker Nano Surfaces and Metrology

High Aspect Ratio TSV Characterization Using Non-Destructive Reflectance Measurements

The Filmtek 2000M TSV characterizes HAR TSV structures through rapid and nondestructive reflectance measurements, leveraging its proprietary optical design and processing method. The 2000M TSV's optical architecture resolves this challenge by employing a collimated beam and customizable spot size, ensuring consistent and coherent reflectance data from HAR TSV structures. 

Traditional reflectometry systems are unable to measure TSV depth accurately because of incoherence. The CCD camera measures the top CD of the TSV and other imaging tasks. In contrast, the high-resolution spectrometer is specifically designed to measure the depths of TSV structures by analyzing light reflected from the top and bottom of the TSV. 

It can measure TSV diameters with aspect ratios as high as 40:1 with an accuracy of up to 2 μm. Thanks to its patented TSV data processing methods, it utilizes simple reflectance measurements to offer comprehensive real-time analysis of TSV depth and CD. 

Schematic and scanning electron microscope image (inset) of HAR TSV structures. Image Credit: Bruker Nano Surfaces and Metrology

Small-Spot Measurements for Next-Gen Semiconductor Applications

The patented optical design of 2000M TSV allows manufacturers to stay ahead of the curve with a variable spot size that can go as small as 2 × 1 µm, capable of measuring the smallest test pads and in extremely tight spaces, even as the semiconductor industry finds innovative ways to produce smaller devices. 

2000M TSV can measure thin and thick layers on top of and surrounding devices to offer process control and reduce scrap in various applications, including front-end production, sophisticated packaging, and hard drive applications.

PSD plot of 500 nm Si₃ N₄ on 950 nm SiO₂ on a Si substrate, showing a distinct peak from each layer. Inset: measured and simulated SiN/SiO2 stack spectra, measured with a 2 μm spot size. Image Credit: Bruker Nano Surfaces and Metrology

How Small-Spot Collimated-Beam Technology Works 

A white light beam is directed through a microscope and collimated using a variable aperture. It then passes through beam splitters and different objective lenses, including high and low magnification, to achieve various spot sizes ranging as small as 2 × 1 µm. 

The XYZ stage positions the collimated beam to exit the objective perpendicular to the sample surface. After reflecting off the sample, the beam enters a lens through a second beam splitter. A high-resolution spectrometer collects one portion of the beam that passes through a pinhole slit. At the same time, a CCD camera captures the remaining portion, offering a real-time image of the measurement site.

Image Credit: Bruker Nano Surfaces and Metrology

FilmTek 2000M TSV Specifications

Source: Bruker Nano Surfaces and Metrology