Wafer Thinning Feedback Control via Inductive Coils
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Solution Overview
Problem
The challenge in wafer thinning for integrated circuit (IC) devices is the risk of over-thinning, which can cause circuit component failure, and existing methods lack effective monitoring and control to prevent this.
Innovation Solution
A system and method that includes a support structure with inductive coils to transmit power and receive feedback signals from the IC wafer, using a process controller to monitor characteristics such as resistance or thickness, and control the substrate removal mechanism to prevent over-thinning by stopping the process when threshold levels are reached.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wafer thinning is performed to reduce thickness, then the desired thickness level is achieved, but over-thinning may occur causing circuit component failure
Solution Approach 1:
The patent implements a feedback mechanism where an RC oscillator circuit on the wafer generates a signal whose frequency changes as the wafer thickness changes during thinning. The process controller monitors this frequency signal and automatically stops the thinning process when a predetermined frequency threshold is reached, corresponding to the desired thickness. This closed-loop feedback control prevents over-thinning while achieving the target thickness precision.
Solution Approach 2:
The patent incorporates a threshold frequency setting that represents the target thickness level before the thinning process begins. The RC oscillator circuit is pre-configured with resistance and capacitance values that correspond to the desired final wafer thickness. This preliminary configuration allows the system to automatically stop at the correct thickness without requiring real-time manual intervention.
2Reliability
If monitoring and control mechanisms are added to prevent over-thinning, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent makes the wafer itself serve as the monitoring device by integrating an RC oscillator circuit directly onto the wafer. The wafer's own physical properties (thickness) automatically modulate the oscillator frequency, which is then read by the process controller. This self-service approach eliminates the need for separate external sensors or complex monitoring equipment, reducing overall system complexity while maintaining reliability.
Solution Approach 2:
The RC oscillator circuit serves multiple functions: it acts as both a timing element for the thinning process and a thickness sensor simultaneously. The same circuit that generates the process timing signal also provides the feedback signal for thickness measurement, combining multiple functions into a single integrated system that reduces complexity.
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 ensures precise control of the wafer thinning process, preventing over-thinning and ensuring the IC wafer is thinned to a desired thickness or resistance, thereby maintaining the integrity and functionality of the circuit components.
Implementation Method 1
The support structure includes one or more inductive coils configured to transmit a power signal to the IC wafer and receive a feedback signal from the IC wafer
Data Source
AI summary
A system and method for thinning an integrated circuit (IC) wafer. The system includes a support structure to hold the IC wafer and a mechanism to operate on the IC wafer. The support structure includes one or more inductive coils configured to transmit a power signal to the IC wafer and receive a feedback signal from the IC wafer. The system further includes a process controller to control the operation based at least in part on the feedback signal received from the IC wafer.