Scan Stage Vacuum Adsorption for Wafer Stability
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Solution Overview
Problem
Conventional semiconductor wafer pollutant measurement apparatuses face challenges with unstable wafer loading and scanning due to the structure of the scan stage, which lacks precise control and flexibility in handling different wafer sizes and vacuum-based adsorption.
Innovation Solution
A scan stage with a rotatable adsorption plate and vacuum-controlled adsorption unit, integrated with a step motor for precise rotation and a base plate that can move up and down, along with independent support jigs for 12-inch and 8-inch wafers, and sensors for load detection, ensuring stable and precise wafer handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional scan stage structure is used, then the apparatus is simpler, but wafer loading stability and scanning precision deteriorate
Solution Approach 1:
The scan stage is divided into separate functional modules: a rotating body for wafer rotation, an adsorption plate for vacuum-based wafer holding, a base plate for vertical movement, and support jigs for wafer positioning. This segmentation allows each module to be optimized independently, improving overall reliability without creating an uncontrollably complex system.
Solution Approach 2:
The scan stage incorporates dynamic elements including a step motor for precise rotational control, a cylinder mechanism for base plate vertical movement, and vacuum-controlled adsorption. These dynamic components enable adaptive adjustment and precise positioning, significantly improving wafer loading stability and scanning precision.
2Reliability
If vacuum-based adsorption is implemented, then wafer holding stability improves, but device complexity increases
Solution Approach 1:
The vacuum adsorption system is integrated directly into the rotating body structure, with the adsorption plate forming an inherent part of the rotation mechanism. This merging eliminates the need for separate vacuum holding devices, reducing overall system complexity while maintaining reliable vacuum-based wafer holding.
Solution Approach 2:
The adsorption plate automatically engages with the wafer through vacuum pressure when the wafer is placed on it, and automatically releases when vacuum is discharged. This self-service mechanism eliminates the need for additional actuators or complex control systems, simplifying the device while ensuring stable wafer holding during rotation.
3Ease of operation
If the base plate can move up and down, then accessibility to wafer lower portion improves, but structural complexity increases
Solution Approach 1:
A cylinder mechanism is used to provide controlled vertical movement of the base plate. This pneumatic/hydraulic actuation offers smooth, controlled motion with precise positioning capability, improving accessibility to the wafer lower portion while maintaining a relatively simple and reliable mechanical structure.
4Adaptability or versatility
If independent support jigs are used for different wafer sizes, then adaptability improves, but device complexity increases
Solution Approach 1:
The support jigs are designed with adjustable features that allow them to accommodate multiple wafer sizes (12-inch and 8-inch wafers) using the same basic structure. This universal design approach provides adaptability for different wafer sizes while avoiding the need for completely separate jig systems, thereby controlling device complexity.
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
The solution provides a stable and precise mechanism for wafer adsorption and scanning, enabling persistent vacuum-based adsorption and rotation, facilitating accurate pollutant collection and analysis while accommodating different wafer sizes.
Implementation Method 1
a vacuum port which is connected to a vacuum line at the bottom of the rotating body
Implementation Method 2
an adsorbing unit which is formed on the upper surface of the rotating body so that a wafer is adsorbed under the vacuum condition
Data Source
AI summary
Provided is a scan stage for a semiconductor wafer pollutant measurement apparatus, which includes: a stage main body which comprises: a circular fixed housing; an adsorption plate which is rotatably installed in the inside of the fixed housing, at the center of which an adsorption path is formed, at the bottom of which a vacuum port is connected, and which is rotated by an external rotating force; and a step motor which is placed at the bottom of the fixed housing and connected with the adsorption plate; a base plate that is supported by pillars to form a lower space between the fixed housing of the stage main body and the base plate; a cylinder at the bottom of which a cylinder load is connected so that the base plate moves up and down; and support jigs that hold up a wafer in the outer side of the stage main body, in which three support jigs are disposed in proximity with the outer circumference of the stage main body.