X-ray scatterometry optics for HAR feature measurement
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Solution Overview
Problem
Current X-ray scatterometry techniques face challenges in accurately measuring geometrical structures of semiconductor devices, particularly High Aspect Ratio (HAR) features, due to limitations in angular resolution and sensitivity, which affect the detection of small geometrical changes and require larger system footprints.
Innovation Solution
The development of an X-ray apparatus and method that includes a beam limiter with adjustable slits, a crystal with a tapered channel, and a beam blocker to control beam parameters such as position, spot size, and divergence, along with a processor to align and calibrate the beam, enhancing angular resolution and sensitivity while reducing system size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional X-ray scatterometry techniques are used, then the system can measure geometrical structures of semiconductor devices, but the angular resolution and sensitivity are insufficient for detecting small geometrical changes in HAR features
Solution Approach 1:
The X-ray beam is segmented into multiple discrete beams using an adjustable slit assembly, allowing independent control of beam parameters. This segmentation enables precise angular resolution by directing specific beams at controlled angles to the sample, while maintaining sensitivity through optimized beam paths and detection geometry for HAR feature measurement
Solution Approach 2:
The slit assembly is made dynamically adjustable to control beam parameters such as divergence and spot size in real-time. This dynamic control allows optimization of angular resolution and sensitivity for different measurement conditions and HAR feature geometries, resolving the contradiction between fixed system limitations and variable measurement requirements
2Area of stationary object
If conventional X-ray scatterometry techniques are used, then the system can operate with standard configuration, but the system footprint becomes larger
Solution Approach 1:
The system utilizes angular dimensionality by directing multiple X-ray beams at different angles to the sample and detecting scattered beams at corresponding angles. This angular space utilization achieves high angular resolution without requiring proportional increases in physical system footprint, as the measurement precision is derived from angular control rather than spatial scale
3Reliability
If the beam divergence is increased to improve signal intensity, then the sensitivity improves, but the angular resolution deteriorates
Solution Approach 1:
The slit assembly provides dynamic control over beam divergence, allowing the system to adjust beam parameters based on measurement requirements. For HAR feature measurement, the system can optimize beam divergence to achieve both sufficient signal intensity for sensitivity and controlled angular spread for resolution, resolving the contradiction through adaptive parameter control
Solution Approach 2:
The system changes beam parameters such as divergence angle and spot size by adjusting slit positions and orientations. This parameter control enables optimization of the relationship between signal intensity and angular resolution, allowing the system to achieve both high sensitivity and precision by selecting appropriate parameter combinations for different measurement scenarios
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves the sensitivity and angular resolution for detecting X-rays scattered from HAR features, allowing for precise measurement of small geometrical changes while minimizing the system's footprint, maintaining high sensitivity and resolution.
Implementation Method 1
The beam limiter is positioned on the first side of the sample so as to intercept the beam of the X-rays. The beam limiter includes first and second blades and first and second actuators. The first and second blades have respective first and second edges positioned in mutual proximity so as to define a slit, through which the beam of the X-rays will pass
Implementation Method 2
a crystal with a tapered channel, and a beam blocker to control beam parameters such as position, spot size, and divergence
Implementation Method 3
a crystal with a tapered channel, and a beam blocker to control beam parameters such as position, spot size, and divergence
Implementation Method 4
The detector is positioned on a second side of the sample, opposite the first side, so as to receive at least a part of the X-rays that have been transmitted through the sample
Implementation Method 5
The X-ray source is configured to direct a beam of X-rays toward a first side of the sample
Data Source
AI summary
An X-ray apparatus includes a mount, an X-ray source, a detector, an actuator, and a controller. The mount is configured to hold a sample. The X-ray source is configured to direct a beam of X-rays toward a first side of the sample. The detector is positioned on a second side of the sample, opposite the first side, so as to receive at least a portion of the X-rays that have been transmitted through the sample and to output signals indicative of an intensity of the received X-rays. The actuator is configured to scan the detector over a range of positions on the second side of the sample so as to measure the transmitted X-rays as a function of a scattering angle. The controller is coupled to receive the signals output by the detector and to control the actuator, responsively to the signals, so as to increase an acquisition time of the detector at first positions where the intensity of the received X-rays is weak relative to the acquisition time at second positions where the intensity of the received X-rays is strong.