Optical weighing using short-wave infrared wavelengths

Abstract

Optical metrology techniques based on the visible wavelength of light can generate lower signal intensity and higher noise, which can negatively impact measurement accuracy and throughput. [Solution] The optical weighing tool includes a first detector configured to image a sample based on illumination having a first wavelength range, and further includes a second detector configured to image a sample based on illumination having a second wavelength range different from the first wavelength range, wherein the first and second detectors include a first imaging channel mounted on a camera changer to selectively position the first or second detector within an acquisition path for imaging a sample, and a second imaging channel having an independent acquisition path separate from the first imaging channel, which includes a third detector configured to image a sample based on illumination having a third wavelength range different from the first wavelength range.

Claims

1. It is an optical weighing tool, A light source comprising one or more light sources, wherein at least one of the light sources is configured to generate illumination within the short-wave infrared (SWIR) spectral range, and at least one of the light sources is configured to generate illumination outside the SWIR spectral range, One or more illumination optical systems configured to direct illumination from one or more illumination sources onto a sample, A first imaging channel includes a first detector configured to image the sample based on illumination having a first wavelength range, wherein the first wavelength range includes at least several wavelengths within the SWIR spectral range from one or more illumination sources, and further includes a second detector configured to image the sample based on illumination having a second wavelength range different from the first wavelength range, wherein the second wavelength range includes at least several wavelengths outside the SWIR spectral range from one or more illumination sources, and the first and second detectors are mounted on a camera changer such that the first imaging channel selectively positions the first detector or the second detector within a collection path for imaging the sample. A second imaging channel having an independent acquisition path separate from the first imaging channel, comprising a third detector configured to image the sample based on illumination having a third wavelength range different from the first wavelength range, wherein the third wavelength range includes at least several wavelengths outside the SWIR spectral range from one or more illumination sources, A controller communicatively coupled to the first and second detectors, the controller including one or more processors configured to execute program instructions on one or more processors, Includes, The execution of the program instructions by one or more of the aforementioned processors, The camera changer is driven to position the first detector, and one or more first images of the sample are received. The camera changer is driven to position the second detector, and one or more second images of the sample are received. The third detector receives one or more third images of the sample. Based on one or more first images, one or more second images, and one or more third images, one or more optical metrological measurements of a sample are generated. Optical weighing tools.

2. An optical weighing tool according to claim 1, At least one of the second wavelength range or the third wavelength range includes at least one of the visible wavelength or the ultraviolet wavelength. Optical weighing tools.

3. An optical weighing tool according to claim 1, The one or more optical metrological measurements include at least one of overlay metrological measurements or optical limit dimensional metrological measurements. Optical weighing tools.

4. An optical weighing tool according to claim 1, The first imaging channel and the second imaging channel are configured to provide in-focus images of different layers of the sample at optimized focal positions, wherein one or more first images from the first detector include images of features on the first layer of the sample, and at least one of one or more second images from the second detector or one or more third images from the third detector includes images of features on the second layer of the sample. Optical weighing tools.

5. An optical weighing tool according to claim 1, The first detector includes at least one of an indium gallium arsenide (InGaAs) detector or a mercury cadmium telluride (HgCdTe) detector. Optical weighing tools.

6. An optical weighing tool according to claim 5, The second detector includes at least one of a silicon detector or a GaAs detector. Optical weighing tools.

7. An optical weighing tool according to claim 1, The first wavelength range and the second wavelength range do not overlap and are separated by a cutoff wavelength, the first wavelength range includes wavelengths above the cutoff wavelength, and the second wavelength range includes wavelengths below the cutoff wavelength. Optical weighing tools.

8. An optical weighing tool according to claim 7, The aforementioned cutoff wavelength is in the range of 700 nm to 1100 nm. Optical weighing tools.

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