Optical Wafer Positioning for Holder Offset and Rotation Correction
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Solution Overview
Problem
Existing semiconductor manufacturing processes face challenges with misalignments between the wafer and the wafer holder, leading to issues such as within-wafer uniformity, wafer-to-wafer process variations, device defects, and reduced performance.
Innovation Solution
An apparatus and method for detecting and correcting the position of a wafer on a wafer holder in an ion exposure apparatus, using light emitter/detector pairs to determine x-direction, y-direction, and rotational misalignments, and adjusting the wafer stage to correct these misalignments before performing an ion exposure process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wafer positioning is performed without alignment detection, then the manufacturing process is simpler and faster, but misalignment occurs between the wafer and wafer holder causing within-wafer non-uniformity and device defects
Solution Approach 1:
The patent replaces complex mechanical alignment systems with an optical detection system using light emitter/detector pairs. The optical system detects wafer position and orientation non-contactly, substituting mechanical measurement mechanisms with optical fields, thereby achieving high precision alignment without complex mechanical structures.
Solution Approach 2:
The patent introduces light as an intermediary between the wafer and the detection system. The light emitter/detector pairs use light reflection and transmission to detect wafer position and orientation, serving as a mediator that transfers positional information without direct mechanical contact, thus simplifying the overall system while maintaining high precision.
2Reliability
If alignment detection and correction is performed, then within-wafer uniformity and device performance improve, but the process time and operational complexity increase
Solution Approach 1:
The patent performs alignment detection and correction before the ion exposure process begins. By detecting wafer position and orientation using light emitter/detector pairs and making necessary adjustments in advance, the system ensures proper alignment is established beforehand, preventing process interruptions and ensuring consistent results throughout the exposure process.
Solution Approach 2:
The patent implements a feedback mechanism where light emitter/detector pairs continuously monitor wafer position and orientation, and the system automatically adjusts the wafer stage based on detected deviations. This closed-loop feedback ensures real-time correction of alignment errors, maintaining high process consistency without requiring manual intervention or repeated measurements.
3Measurement precision
If multiple light emitter/detector pairs are used for comprehensive alignment detection, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent divides the alignment detection task into multiple independent light emitter/detector pairs, each responsible for detecting specific positional or orientational parameters. By segmenting the detection function across multiple simple optical units rather than using one complex detection system, the patent achieves high measurement precision while keeping individual components simple and manageable.
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
Correcting misalignments between the wafer and the wafer holder improves within-wafer uniformity, reduces wafer-to-wafer process variations, decreases device defects, and enhances overall device performance.
Implementation Method 1
Light emitter/detector pairs may be used to detect the x-direction misalignment and the y-direction misalignment of the wafer
Data Source
AI summary
A method of correcting a misalignment of a wafer on a wafer holder and an apparatus for performing the same are disclosed. In an embodiment, a semiconductor alignment apparatus includes a wafer stage; a wafer holder over the wafer stage; a first position detector configured to detect an alignment of a wafer over the wafer holder in a first direction; a second position detector configured to detect an alignment of the wafer over the wafer holder in a second direction; and a rotational detector configured to detect a rotational alignment of the wafer over the wafer holder.