Wafer Position Detection Using Reference Comparison
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Solution Overview
Problem
Conventional semiconductor manufacturing apparatuses fail to accurately detect wafer positional deviations, leading to potential damage during transport and increased costs due to the need for multiple sensors, especially when dealing with light-transmissive materials like quartz, and accumulate errors as the number of wafers increases, resulting in incorrect judgment of wafer positions.
Innovation Solution
A semiconductor manufacturing apparatus equipped with a substrate detecting sensor that compares the maximum and minimum positional information of substrates with their averages, allowing for accurate detection of deviations and deformation, and outputs failure signals for abnormal conditions, using a control section to manage and correct positional data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional wafer state detecting mechanism compares intervals between adjoining wafers with preset position information, then judgment of normal wafer states can be made, but accumulated errors occur as the number of detected wafers increases leading to incorrect position detection
Solution Approach 1:
The patent segments the wafer detection process into two independent parts: (1) detecting interval between each wafer and its adjacent wafer, and (2) detecting absolute position of each wafer from a reference position. This segmentation allows each detection method to address its specific function without the accumulated errors that occur when using only relative interval comparisons across multiple wafers.
Solution Approach 2:
The patent introduces a reference position as an intermediary for absolute position measurement. By comparing each wafer's position against this fixed reference point rather than against previous wafers, the system eliminates error accumulation. The reference position acts as a stable mediator that provides a consistent baseline for all position measurements.
2Measurement precision
If multiple sensors are used to detect wafer positions and boat states, then detection accuracy improves, but apparatus cost increases
Solution Approach 1:
The patent makes the wafer state detecting sensor multi-functional by enabling it to perform both wafer position detection and boat state detection. The sensor detects wafer positions by measuring intervals from a reference position, and simultaneously detects boat states (such as inclination or deformation) by analyzing the spatial relationships between detected wafer positions. This universality eliminates the need for separate boat detecting sensors, reducing apparatus complexity and cost.
Solution Approach 2:
The patent merges the functions of wafer detection and boat detection into a single integrated system. By combining the detection of wafer positions and boat states into one unified detection mechanism, the patent reduces the total number of sensors required while maintaining comprehensive monitoring capabilities.
3Ease of operation
If conventional relative comparison method is used for adjoining wafers, then detection can be performed, but correct position detection cannot be made unless wafers are placed in all slots
Solution Approach 1:
The patent establishes a reference position before wafer detection begins. This preliminary action creates a fixed baseline that allows each wafer's position to be determined independently of whether other wafers are present. The reference position is set in advance, enabling the system to calculate absolute positions even when slots are empty, thus maintaining detection operation capability while ensuring measurement precision.
Data Source
AI summary
A processing furnace for performing prescribed heat treatment on plural substrates, a boat for carrying the plural substrates that are laid one over another in the boat into and out of the processing furnace, a substrate detecting sensor for detecting the plural substrates laid one over another in the boat by changing a relative position of the substrate detecting sensor with respect to each of the plural substrates, and a control section for registering reference positions of the plural substrates and an allowable range of positional deviations from the reference positions of the plural substrates are provided. The control section receives pieces of position information of the plural substrates measured by the substrate detecting sensor, compares a maximum value of pieces of position information of substrates with an average thereof and compares a minimum value of pieces of position information of substrates with an average thereof if the pieces of position information of the plural substrates are out of the allowable range of positional deviations from the reference positions of the plural substrates, and judges that deviation has occurred in a boat stop position if differences determined by the respective comparisons are within the allowable range of deviations of the substrates.