Semiconductor Overlay Inspection Using Variable-Angle Bright and Dark Fields
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Solution Overview
Problem
Existing methods for measuring overlay between multiple circuit pattern layers in semiconductor substrates are inefficient, requiring different overlay keys for each layer and increasing measurement time and cost.
Innovation Solution
A substrate inspection apparatus using a light irradiator with an objective lens and optical fibers to simultaneously measure overlay between multiple circuit pattern layers by irradiating light at varying angles, combining bright and dark fields to enhance image resolution and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If different overlay keys are required for each layer to measure overlay between multiple circuit pattern layers, then measurement precision is improved, but device complexity and measurement time increase
Solution Approach 1:
The patent applies a single overlay key structure that can measure overlay between multiple circuit pattern layers simultaneously. The overlay key includes multiple first overlay keys and second overlay keys arranged at different positions, allowing one key structure to serve multiple measurement functions across different layers, thereby reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The patent extends the measurement approach from measuring only adjacent layers to measuring multiple layers simultaneously by utilizing the vertical dimension. The overlay key is designed with multiple keys at different heights and positions, enabling the system to capture overlay information across multiple circuit pattern layers in a single measurement operation, thus reducing the number of separate measurements needed.
2Measurement precision
If different overlay keys are required for each layer, then measurement precision is improved, but measurement time increases
Solution Approach 1:
The patent performs preliminary arrangement of multiple overlay keys at different positions and heights before measurement. This pre-configured structure allows the system to capture overlay information for multiple layers simultaneously in a single measurement operation, eliminating the need for sequential measurements and thereby reducing measurement time while maintaining precision.
Solution Approach 2:
The multi-functional overlay key structure enables one measurement operation to serve multiple purposes by measuring overlay between different circuit pattern layers simultaneously. This universality reduces the total number of measurements required, thereby reducing measurement time while maintaining the precision needed for reliable overlay assessment.
3Difficulty of detecting and measuring
If data from upper circuit pattern layers decreases to lower layers, then measurement focus is on adjacent layers, but overlay measurement completeness is reduced
Solution Approach 1:
The patent addresses the information loss by extending measurements into the vertical dimension. The overlay key includes multiple first overlay keys and second overlay keys at different heights, enabling the system to capture overlay information for multiple circuit pattern layers simultaneously. This dimensional extension ensures complete overlay measurement across all layers rather than focusing only on adjacent layers.
Solution Approach 2:
The patent performs preliminary configuration of multiple overlay keys at different positions and heights to ensure comprehensive coverage of all circuit pattern layers. This pre-arranged structure enables the system to detect and measure overlay information for every layer before the measurement process begins, preventing information loss and ensuring measurement completeness.
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
Accurately measures overlay between circuit pattern layers with high resolution and in a short time, reducing the need for multiple overlay keys and minimizing measurement time and cost.
Implementation Method 1
a light analyzer 400 that measures the overlay of the semiconductor substrate 20 through light L1 that is reflected from the semiconductor substrate 20
Implementation Method 2
a light generator 100 that generates the light L0 and changes an irradiation angle of the light L0 to selectively irradiate the light L0 to one or more of the objective lens 310 and the optical fibers 320
Implementation Method 3
a light analyzer 400 configured to measure the overlay of the semiconductor substrate 20 through light L1 that is reflected from the semiconductor substrate 20
Data Source
AI summary
A substrate inspection apparatus includes a light irradiator including an objective lens and a plurality of optical fibers. The objective lens is configured to irradiate light to an illumination area on a semiconductor substrate having a plurality of circuit pattern layers, the plurality of optical fibers are adjacent a periphery of the objective lens and are configured to irradiate the light to a peripheral area adjacent the illumination area. A light generator is configured to generate the light. The light generator is configured to change an irradiation angle of the light to selectively irradiate the light to one or more of the objective lens and the plurality of optical fibers. A light analyzer is configured to obtain images of the circuit pattern layers from the light reflected from the illumination area and the peripheral area. The light analyzer is configured to model each of the circuit pattern layers of the semiconductor substrate to obtain image models and to measure an overlay between the circuit pattern layers through the images and the image models.