Overlay Error Compensation Using Similar Layer Feedback
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Solution Overview
Problem
In semiconductor manufacturing, the initial batches of wafers often experience inaccurate overlay error compensation due to limited feedback data, leading to reworking and increased production costs in the photoetching process.
Innovation Solution
A method and apparatus that determine an overlay error compensation value for a present batch of wafers by referencing the overlay error values of similar layers aligned to the same reference layer, either from the present batch or previous batches, to improve overlay accuracy and reduce reworking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If overlay error compensation is performed using limited feedback data from initial batches of wafers, then the photoetching process can proceed, but the overlay accuracy is insufficient leading to reworking
Solution Approach 1:
The patent applies preliminary action by using overlay error data from previously processed similar layers (from the same or different wafers) to pre-determine compensation values before the current photoetching process. This allows the system to prepare accurate compensation values in advance rather than waiting for limited feedback data from the current batch, thereby improving overlay accuracy from the start and avoiding reworking.
Solution Approach 2:
The patent uses copying by replicating the successful overlay compensation approach from similar layers that have already been processed. Instead of relying on limited feedback from the current batch, the system copies the overlay error characteristics and compensation strategies from previously processed similar layers, applying these learned patterns to improve the current photoetching process accuracy.
2Reliability
If overlay error compensation relies on feedback data from the first batch of wafers, then the process can start, but the compensation values are not accurate enough causing reworking
Solution Approach 1:
The patent enhances feedback by systematically collecting and utilizing overlay error data from multiple sources including previously processed similar layers from the same wafer, different wafers, and different batches. This expanded feedback mechanism provides much more data than relying solely on the first batch, enabling more accurate determination of compensation values while maintaining high production efficiency through automated processing.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting overlay compensation parameters based on accumulated data from processing multiple similar layers. Instead of using fixed or initially limited compensation values, the system continuously refines compensation parameters using feedback from each processed layer, thereby improving reliability and compensation accuracy over time without sacrificing productivity.
3Manufacturing precision
If reworking is performed on wafers with inaccurate overlay compensation, then overlay accuracy can be improved, but production costs increase
Solution Approach 1:
The patent prevents the need for reworking by performing preliminary overlay compensation using data from previously processed similar layers. This advance preparation ensures that the first photoetching process achieves the required overlay accuracy, eliminating the need for costly reworking operations and associated energy consumption.
Solution Approach 2:
The patent avoids reworking costs by copying proven compensation strategies from successfully processed similar layers. This approach ensures that the current photoetching process achieves accurate overlay from the first attempt, preventing the need for reworking and the associated increase in production costs.
Data Source
AI summary
In a control method for overlay accuracy, whether a similar layer of a present layer exists is determined first, where both the present layer and the similar layer are aligned relative to a same reference layer, and overlay accuracy requirements of both the present layer and the similar layer are relative to the reference layer; if so, an overlay error compensation value of a present batch of wafers at the present layer is determined according to an overlay error value of the present batch of wafers at the similar layer and/or an overlay error value of a previous batch of wafers at the similar layer; and a photoetching process is performed on the present layer of the present batch of wafers by means of the overlay error compensation value of the present batch of wafers at the present layer.