SPM Probe-Driving Mechanism for Straight-Axis Positioning
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Solution Overview
Problem
Scanning probe microscopes (SPMs) face challenges in achieving high positioning accuracy and throughput due to structural issues in probe-driving mechanisms, such as circular arc errors and interference between axes, which hinder in-line semiconductor manufacturing applications by reducing measuring efficiency and accuracy.
Innovation Solution
The implementation of a probe-driving mechanism with paired stage-driving mechanisms using elastic deformation elements and piezo-elements, along with displacement sensors and servo-control, allows for precise positioning and error correction, enabling independent operation of the X, Y, and Z axes without interference, and direct observation of the probe and sample surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a tubular three-dimensional driving mechanism or tri-pod three-dimensional driving mechanism is used to position the probe accurately, then positioning accuracy is improved, but circular arc errors occur and straightness of probe-driving axes deteriorates
Solution Approach 1:
The probe-driving mechanism is divided into three independent linear driving mechanisms, each responsible for one axis (X, Y, or Z). This segmentation eliminates the structural coupling that causes circular arc errors in tubular or tri-pod mechanisms, allowing each axis to move independently in a straight line without affecting the others.
Solution Approach 2:
The invention transitions from a coupled three-dimensional mechanism (tubular or tri-pod) to three separate one-dimensional linear mechanisms. By decomposing the 3D movement into three independent 1D movements, the system achieves both high positioning accuracy and maintained straightness without circular arc errors.
2Measurement precision
If the force needed to drive one scanning axis is applied, then positioning on that axis is achieved, but the other two axes are affected due to structural reasons
Solution Approach 1:
The driving mechanism is segmented into three independent linear driving mechanisms, each with its own drive source (such as a voice coil motor or piezoelectric actuator). This allows each axis to be driven independently without mechanical coupling, eliminating the cross-axis interference that occurs in tubular or tri-pod mechanisms where force application on one axis affects the others.
Solution Approach 2:
The invention employs dynamic control of three independent linear mechanisms, allowing real-time adjustment of each axis without affecting the others. This dynamic independence enables precise positioning on one axis while maintaining stability on the other two axes, overcoming the structural coupling limitations of traditional mechanisms.
3Measurement precision
If SPM is used to measure surface profile data with high resolution, then measurement precision is improved, but measuring throughput decreases due to time-consuming operations
Solution Approach 1:
The SPM system continuously scans the sample surface by moving the probe in a systematic pattern across the entire inspection region. The linear driving mechanisms enable smooth, continuous movement without the positioning delays and re-adjustments required by conventional systems, maintaining high measurement precision while significantly improving throughput to meet in-line manufacturing requirements.
Solution Approach 2:
The system pre-positions the probe using the high-speed linear driving mechanisms before beginning the detailed surface profile measurement. This preliminary rapid positioning, followed by continuous scanning, reduces the time required for determination of measuring positions while maintaining the high resolution measurement capability, thereby increasing overall measuring throughput.
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 configuration enhances the accuracy and throughput of SPMs, enabling rapid and precise in-line measurements that can be fed back to processing parameters, thereby improving semiconductor manufacturing yield and reducing industrial waste.
Implementation Method 1
a probe-driving mechanism uses three voice coil motors to drive a tri-axis stage
Implementation Method 2
all resilient members connecting the Y-stage to the outer frame equally undergo elastic deformation and thus prevent unnecessary force from being applied to operation axes other than the Y-axis
Implementation Method 3
a probe-driving mechanism uses three voice coil motors to drive a tri-axis stage constructed by forming, in a Y-stage connected to an outer frame via resilient members, an XZ stage (X-Z combination stage) connected to the Y-stage via resilient members
Implementation Method 4
This probe-driving mechanism is constructed so that regardless of the displacement of the associated stage, each spindle is always pressed against the stage in parallel to the operating direction thereof
Data Source
AI summary
A scanning probe microscope for measuring a surface profile of a sample by bringing a probe into close proximity to or contact with the surface of the sample and scanning the sample surface includes: a sample stage movable in at least one axis direction; the probe which is brought into close proximity to or contact with the surface of the sample mounted on the sample stage and scans the sample surface; a probe-driving unit for moving the probe three-dimensionally; a probe deflection detector for detecting a deflection of the probe; and an observation optical system which has an objective lens and observes the probe disposed on substantially the optical axis of the objective lens, and the sample. The probe-driving unit is disposed with three sets of paired drive sources arranged essentially with symmetry with respect to the optical axis of the objective lens.