Bonded Substrate Grinding Using Thickness-Derived Tilt Control
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Solution Overview
Problem
Conventional grinding methods for thinning semiconductor substrates in combined substrates face challenges in achieving uniform thickness due to non-uniform thickness distributions in the second substrate, especially when a device layer or metal film is present, which obstructs proper thickness measurement and affects the grinding process.
Innovation Solution
A substrate processing method that involves measuring the total thickness distribution of the combined substrate, determining the thickness distribution of the second substrate by subtracting the first substrate's thickness distribution, and adjusting the relative inclination of the substrate holder and grinder based on the second substrate's thickness distribution to grind the first substrate uniformly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional grinding methods are used to thin the first substrate, then the grinding process can be performed, but the thickness uniformity deteriorates due to non-uniform thickness distribution in the second substrate
Solution Approach 1:
The patent segments the thickness measurement problem into two separate measurements: total thickness of the combined substrate and thickness of the first substrate alone. By measuring these separately and calculating the second substrate's thickness distribution through subtraction, the system overcomes the limitation of direct measurement obstruction caused by device layers or metal films.
Solution Approach 2:
The patent introduces an intermediary calculation approach where the thickness distribution of the second substrate is derived indirectly through mathematical subtraction rather than direct measurement. This intermediary method allows accurate determination of the second substrate's thickness profile even when direct measurement is blocked by device layers or metal films.
2Manufacturing precision
If the relative inclination between substrate holder and grinder is not adjusted, then the grinding process is simpler to operate, but the flatness of the first substrate deteriorates
Solution Approach 1:
The patent applies preliminary action by adjusting the relative inclination between the substrate holder and grinder before the grinding process based on pre-measured thickness distributions. This preliminary adjustment ensures that the grinding process will achieve uniform thickness and flatness without requiring complex real-time control during grinding.
Solution Approach 2:
The patent implements feedback by using measured thickness distribution data of the second substrate to determine the appropriate relative inclination setting. The measurement results feed into the inclination adjustment process, creating a closed-loop system that optimizes grinding parameters based on actual substrate characteristics.
Data Source
AI summary
A substrate processing method of grinding a first substrate in a combined substrate in which the first substrate and a second substrate are bonded to each other includes measuring a total thickness distribution of the combined substrate; measuring a thickness distribution of the first substrate; calculating a thickness distribution of the second substrate by subtracting the thickness distribution of the first substrate from the total thickness distribution of the combined substrate; deciding a relative inclination between a substrate holder configured to hold the combined substrate and a grinder configured to grind the combined substrate, based on the thickness distribution of the second substrate; and grinding the first substrate while holding the combined substrate at the inclination which is decided.