Wafer Prober Full-Wafer Contacter Coplanarity
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Solution Overview
Problem
In semiconductor testing, wafers often fail to achieve coplanarity with the tester interface due to small irregularities in the chuck's planar profile, leading to inconsistent electrical connections, especially at higher pin counts and larger diameters.
Innovation Solution
A wafer prober is adapted to use a full-wafer contacter, where the wafer is aligned and removably attached to a translator with a pattern of terminals matching the integrated circuits, allowing electrical contact through a surface facing away from the wafer, ensuring consistent connections by conforming to the translator's surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a wafer is mounted on a moveable chuck for positioning and testing, then accurate positioning and wafer holding are achieved, but small irregularities in the chuck's planar profile cause the wafer to fail achieving coplanarity with the tester interface, leading to inconsistent electrical connections
Solution Approach 1:
Instead of making the wafer conform to the chuck surface (traditional approach), the patent inverts the relationship by making the chuck conform to the wafer surface through a compliant layer. This reversal allows the rigid wafer to maintain its original planarity while the chuck adapts to it, solving the coplanarity issue caused by chuck irregularities
Solution Approach 2:
The patent changes the physical parameter of the chuck surface by introducing a compliant layer that can deform elastically. This allows the chuck surface to dynamically adjust its shape to match the wafer's planar profile, ensuring consistent coplanarity across the entire wafer surface during testing
2Reliability
If pressure is applied through vertical chuck movement and vacuum to form contacts between the membrane and wafer, then electrical contacts are formed, but this same pressure causes the wafer to conform to chuck irregularities rather than maintaining its own planar profile
Solution Approach 1:
The patent changes the compliance parameter of the chuck surface by adding a deformable layer, allowing it to adapt to the wafer's planar profile under pressure rather than forcing the wafer to conform to the chuck's irregularities. This maintains both contact reliability and wafer planarity
Solution Approach 2:
The compliant layer acts as an intermediary between the rigid chuck structure and the wafer, absorbing the irregularities of the chuck while maintaining reliable contact pressure on the wafer surface without transmitting the chuck's planar defects to the wafer
Data Source
AI summary
Methods and apparatus for testing unsingulated integrated circuits on a wafer include adapting a wafer prober for use with full-wafer-contacter disposed on the wafer. Some embodiments include placing wafer on a chuck of the prober, aligning the wafer to a full-wafer contacter incorporated in the wafer prober; removably attaching the wafer to the full wafer contacter, separating the wafer from the chuck, and making electrical contact to one or more integrated circuits of the wafer by making physical contact with a surface of the full-wafer contacter that faces away from the wafer.