Focus system for oblique optical metrology device
a technology of optical metrology and focus system, which is applied in the field of optical metrology, can solve the problems of high cost and difficulty, difficult to achieve, and require very precise alignment,
Active Publication Date: 2022-06-02
ONTO INNOVATION INC
View PDF0 Cites 0 Cited by
- Summary
- Abstract
- Description
- Claims
- Application Information
AI Technical Summary
Benefits of technology
This approach allows for accurate and rapid focus positioning of optical metrology devices, reducing inaccuracies and alignment costs by distinguishing between top surface and underlying layer reflections based on selected light characteristics, thereby improving measurement precision and efficiency.
Problems solved by technology
Such focusing systems, however, require very precise alignment, which is expensive and difficult.
Such devices, however, are susceptible to inaccuracies due to stray light.
Method used
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View moreImage
Smart Image Click on the blue labels to locate them in the text.
Smart ImageViewing Examples
Examples
Experimental program
Comparison scheme
Effect test
Embodiment Construction
[0019]Oblique optical metrology devices, including oblique angle reflectometers and ellipsometers, require proper focusing of the light that is incident on the sample. Because multiple areas of a sample, e.g., a semiconductor wafer, may be measured by the optical metrology device, the optical metrology device must be properly focused at each measurement location. To alter the focal position of such an optical metrology device, the distance between the optical system and the sample may be adjusted, which takes time. Accordingly, it is desirable to not only determine the focus position accurately, but the focus position should be determined quickly.
[0020]An accurate, real time focus system for an oblique optical metrology device may use an image of the measurement spot on the sample to determine a best focal position for the device. For example, the light reflected from the sample may be split, so that a portion of the light is received by the metrology device's detector for measureme...
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More PUM
| Property | Measurement | Unit |
|---|---|---|
| optical path length | aaaaa | aaaaa |
| ultraviolet wavelength range | aaaaa | aaaaa |
| visible wavelengths | aaaaa | aaaaa |
Login to View More
Abstract
The light from an optical metrology device is focused into a measurement spot on a sample using a focusing system. The focusing system uses an image of the light reflected from the measurement spot to determine a best focal position at a desired position of the sample. The focusing system selects a characteristic of reflected light, such as polarization state or wavelengths, to use for focusing. The characteristic of the reflected light that is selected for use in determining focal position is affected different by different portions of the sample. For example, light reflected from a top surface of a sample may have a different characteristic than light reflected by an underlying layer. The selected characteristic of the reflected light is used by the focusing system to focus the measurement spot at the top surface or an underlying layer of the sample.
Description
FIELD OF THE DISCLOSURE[0001]The present invention is related to optical metrology, and in particular to focusing an optical metrology device.BACKGROUND[0002]Semiconductor and other similar industries often use optical metrology equipment to provide non-contact evaluation of substrates during processing. With optical metrology, a sample under test is illuminated with light, e.g., at a single wavelength or multiple wavelengths. After interacting with the sample, the resulting light is detected and analyzed to determine a desired characteristic of the sample.[0003]Some optical metrology devices use light that is obliquely incident on the sample and reflects or scatters off a sample before being detected. One example of an optical metrology device that uses an oblique angle of incidence is an ellipsometer. Ellipsometers are optical metrology devices that detect changes in the polarization state of light reflected from a surface of a sample in order to measure characteristics of the sam...
Claims
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More Application Information
Patent Timeline
Login to View More Patent Type & Authority Applications(United States)
IPC IPC(8): G01N21/95G01B11/25
CPCG01N21/9501G01N2201/068G01B11/25G01N21/211G02B27/28G01N21/8422G01B11/0641G01B2210/56G03B13/36
Inventor SHACHAF, AMITTHOMPSON, DANIELLESOINE, JOHN F.
Owner ONTO INNOVATION INC