Wafer-Level Embedded Antenna Testing via Wireless Loopback

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Solution Overview

Problem

Current methodologies for testing embedded antennas on integrated circuits during the wafer testing stage are ineffective due to the Faraday cage effect created by probes, which isolates the antenna and prevents the transmission of electromagnetic signals, requiring post-wafer dicing and encapsulation for testing, thereby increasing costs and inefficiency.

Innovation Solution

A test circuit with a wireless loopback connection is implemented, using test antennas associated with embedded antennas to create a wireless channel for testing, transforming electromagnetic signals into electric signals readable by a test apparatus, allowing for the evaluation of embedded antenna functionality without the need for physical contact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If probes are used to electrically connect the tester to the chip pads during wafer testing, then electrical connection is established, but the Faraday cage effect isolates the embedded antenna and prevents electromagnetic signal transmission

Engineering Contradiction:

Improveantenna functionalityVSAvoidFaraday cage effect

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A test antenna is introduced as an intermediary element between the embedded antenna and the testing system. The test antenna is positioned in close proximity to the embedded antenna to enable electromagnetic coupling, allowing signals to be transmitted and received without direct electrical contact. This intermediary structure enables antenna testing while avoiding the Faraday cage effect created by traditional probe connections.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If wafer dicing and encapsulation are performed before antenna testing, then the antenna can be tested without Faraday cage interference, but production costs and time increase

Engineering Contradiction:

Improveantenna testing accuracyVSAvoidproduction cycle time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The testing structure (test antenna and associated circuitry) is prepared in advance on the wafer before dicing and encapsulation. By pre-positioning the test antenna in close proximity to the embedded antenna during the wafer stage, the system enables immediate electromagnetic coupling and testing capability. This preliminary setup allows antenna testing to be performed at the wafer level, eliminating the need to wait until after dicing and encapsulation, thus reducing production cycle time while maintaining testing accuracy.

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If traditional probing methods are used for antenna testing, then electrical connection is established, but the antenna cannot be tested due to electromagnetic isolation

Engineering Contradiction:

Improvetesting accessibilityVSAvoidelectromagnetic signal transmission

Core Design Contradiction:

Ease of operationVSDifficulty of detecting and measuring

Solution Approach 1:

The traditional mechanical probing system that relies on direct electrical contact is replaced with an electromagnetic coupling system. Instead of using physical probes to establish electrical connections, the system uses electromagnetic fields to transmit signals between the test antenna and the embedded antenna. This substitution eliminates the Faraday cage effect while maintaining ease of operation, as the test antenna can be positioned close to the embedded antenna without requiring complex probe positioning and electrical connection establishment.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Enables the testing of embedded antennas on integrated circuits during the wafer stage, reducing costs and inefficiencies by facilitating contactless evaluation, thereby improving the testing process and identifying faulty antennas earlier in the production cycle.

Implementation Method 1

transforming electromagnetic signals into electric signals readable by a test apparatus

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a conductive layer, which is possible to be defined so as to surround with a closed loop the first and second embedded antennas

Methodology Applied

Scientific EffectElectromagnetic coupling: Electromagnetic Induction

Data Source

PatentUS8941401B2Test circuit of an integrated circuit on a wafer

Publication Date: 2015.01.27 STMICROELECTRONICS SRL

AI summary

A test circuit is described of a circuit integrated on wafer of the type comprising at least one antenna of the embedded type comprising at least one test antenna associated with said at least one embedded antenna that realizes its connection of the wireless loopback type creating a wireless channel for said at least one embedded antenna and allows its electric test, transforming an electromagnetic signal of communication between said at least one embedded antenna and said at least one test antenna into an electric signal that can be read by a test apparatus.