Optical critical dimension (OCD) measurement Optical critical dimension (OCD) measurement

Optical critical dimension (OCD) measurement

Optical Critical Dimension (OCD) measurement in semiconductor processes: Precision control in photolithography and etching

Optical Critical Dimension (OCD) measurement is a technique used in photolithography and etching processes to precisely measure critical dimensions, such as feature sizes and shapes, on semiconductor wafers. Overall, OCD measurement in both photolithography and etching contributes to the precise control and optimization of critical dimensions, enabling the production of semiconductor devices with the required performance characteristics and reliability. It plays a crucial role in maintaining the quality and consistency of the semiconductor manufacturing process.

 

By irradiating white light onto a surface at a minute angle and detecting the reflected diffracted light spectroscopically, spectral waveforms corresponding to the pattern shape are obtained, and the data is used to analyze minute dimensions such as surface structure. The measurement with high throughput and high repeatability allows to measure trench holes and complex 3D structures.

Line sensors for spectrophotometry

These mage sensors for measurement have sensitivity in the ultraviolet to near-infrared regions. A wide range of products are available according to wavelength and purpose of use, including types with high sensitivity in the ultraviolet and near-infrared regions and types with high resistance to ultraviolet irradiation.

Mini-spectrometers

These compact spectrometers integrate an optical system, image sensor, and circuitry. They cover a wide range of wavelengths from the ultraviolet to near-infrared regions.

InGaAs linear image sensors

Hamamatsu provides high sensitivity low noise InGaAs image sensors with multiple cutoff wavelengths from 1.7um to 2.5um

Laser-Driven Light Sources (LDLS)

These are the world's only light sources that use a method of maintaining emission by generating plasma with a focused laser beam between discharge electrodes in a bulb filled with xenon gas. Compared to conventional xenon lamps, these light sources provide higher bright light in the ultraviolet region and have features such as long life and minute emission points.

Semiconductor processes using Optical Critical Dimension (OCD) measurement

Photolithography

In photolithography, OCD measurement is essential for dimension control, ensuring precise management of critical feature dimensions on the wafer, encompassing elements like transistors and interconnects in integrated circuits. Additionally, OCD plays a crucial role in overlay control, ensuring accurate alignment of different layers during multiple exposure and patterning steps. This precision is vital for creating intricate and layered semiconductor structures with optimal functionality.

Etching

OCD measurement is crucial in etching processes for process monitoring, allowing precise control of feature dimensions etched onto semiconductor material. It ensures the etching process achieves the desired depths and shapes. Additionally, OCD is employed for endpoint detection during etching, determining the optimal stopping point to prevent over-etching and potential defects, ensuring the desired features are accurately etched into the material.

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