Measuring die tilt using shadow moiré optical measurements; new techniques for discontinuous and semi-reflective surfaces — Phase 2

Abstract

When dealing with production of Flip Chip Packages in semiconductor packaging the angle between the die and package substrate is critical for maintaining product yield and reliability. Current outgoing quality checks for die tilt can be time consuming to measure heights via point to point measurement techniques. Existing die tilt measurement approaches can also have reproducibility issues from user to user. Shadow moire technology is a full field optical inspection technique commonly used for flatness characterization in the semiconductor industry, particularly at elevated temperatures. Two limitations to shadow moire apply when discussing outgoing QC of die tilt: 1) shadow moire requires a diffuse reflective surface for measurement; 2) shadow moire is unable to measure sudden step heights. This paper focuses on case study data for samples with two or more separated planes. Die tilt measurement techniques from phase 1 of this study are applied to the case study data. Using shadow moire for this measurement technology can reduce measurement and user time as well as improve consistency of measurements from user to user. As shadow moire tools are often used for at temperature flatness measurements, this added application can reduce the number of different measurement tools needed in QA labs.