Substrate Stack Thickness Equalization via Local Adhesive Compensation
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Solution Overview
Problem
The semiconductor industry faces challenges in reducing total thickness variation (TTV) in multi-substrate stacks, which can lead to inhomogeneous thickness and potential damage during thinning and etching processes, despite advancements in bonding technologies.
Innovation Solution
A method and device that measure and locally address thickness maxima in a bonded substrate stack using a combination of a measuring unit and an application device to equalize thickness variations, specifically reducing TTV by applying mechanical pressure through pin-like application units or a membrane to the adhesive layer between substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If temporary bonding is used to bond product substrate to carrier substrate, then the functional units are fully embedded in the adhesive and mechanical stabilization is achieved, but the total thickness variation (TTV) of the substrate stack becomes large
Solution Approach 1:
The patent measures the thickness distribution of the substrate stack before bonding and calculates the required additional adhesive thickness to compensate for thickness variations. This preliminary measurement and calculation enable the adhesive layer to be applied with the precise thickness needed to equalize the total thickness, thereby reducing TTV while maintaining mechanical stabilization.
Solution Approach 2:
The patent applies adhesive with locally varying thickness rather than uniform thickness. By adding adhesive preferentially at locations where the substrate stack is thinner, the method creates a compensated thickness distribution that equalizes the overall thickness of the bonded stack, resolving the contradiction between mechanical stabilization and thickness precision.
2Ease of manufacture
If large TTV is present in the substrate stack, then the bonding process can accommodate thickness variations, but the subsequent thinning and etching processes cause inhomogeneous thickness and potential substrate destruction
Solution Approach 1:
The method performs preliminary measurement of substrate thickness and calculates the required adhesive compensation before bonding occurs. This advance preparation ensures that the adhesive layer is applied with the exact thickness profile needed to equalize the substrate stack, preventing the TTV problems that would otherwise plague subsequent thinning and etching processes.
Solution Approach 2:
The patent uses measurement data from the substrate thickness inspection as feedback to determine the adhesive application thickness. The measured thickness distribution directly informs the compensation strategy, creating a closed-loop process where measurement results guide the bonding parameters to achieve uniform final thickness and ensure substrate integrity during processing.
3Productivity
If uniform adhesive thickness is applied during bonding, then the bonding process is simple and fast, but the thickness variations in the substrate stack are not compensated and TTV remains large
Solution Approach 1:
The patent performs thickness measurement and calculation of required adhesive compensation before the bonding process. This preliminary action enables the bonding step to apply adhesive with the precise locally-varying thickness needed for compensation, achieving both speed (by preparing parameters in advance) and precision (through calculated thickness distribution).
Solution Approach 2:
The method changes the adhesive layer thickness parameter from a uniform value to a spatially varying value based on measured substrate thickness. By adjusting the adhesive thickness parameter locally across different regions of the substrate stack, the system compensates for thickness variations while maintaining an efficient bonding process.
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
This approach significantly reduces TTV by up to 95%, enabling more uniform substrate stacks and preventing damage during subsequent processing steps, thereby improving the stability and processability of semiconductor components.
Implementation Method 1
The sensor is usually a laser interferometer. A laser interferometer can be used to detect and determine changes in thickness down to the nanometer range.
Implementation Method 2
equalize the position of local maxima by means of an application device (11) having at least one application unit (9), wherein the application of thickness maxima takes place by mechanically pressing on the surface (4o) of the product substrate (4) or on the adhesive layer (3) with the application unit (9)
Data Source
Figure 1a~1c
Figure 2~4
Figure 5a~5d
AI summary
The present invention relates to a method for evening out the thickness variation of a substrate stack (1) by locally impacting local thickness maxima (12) by means of at least one impacting apparatus (11, 11', 11") that has at least one impacting unit (9, 9', 9", 9''', 9IV, 9V, 9VI), said substrate stack consisting of a product substrate (4) and a carrier substrate (2) and said substrates being particularly connected by means of a connecting layer (3). The invention further relates to a corresponding device.