Measurement of Thermal Deformation of IC Packages Using the AFM Scanning Moire Technique

摘要

The scanning moire method was suggested in 1980's. A scanning moire method using optical method was proposed in 1993. The scanning lines in the SEM monitor or CCD video camera were utilized as the reference grating to form a scanning moire pattern. The available results are limited to the deformation measurement by using a grating with a frequency less than 250 lines/mm. Thus it is impossible to apply this method to measure deformation in nanometer scale. With the development of micro-mechanics and the appearance of nanometer mechanics, new techniques for deformation measurement from micrometer to nanometer scales are in urgent need. An AFM (atomic force microscope) scanning moire technique has been developed in this study to measure deformation in both micrometer and nanometer scales. The scanning lines in the AFM monitor are used as the reference grating. The reference grating interferes with the specimen grating, and forms a moire pattern on the monitor. The condition of forming scanning moire with an AFM is derived. The grating replication method is described. The deformation measurement principle using AFM scanning moire is discussed in detail. The AFM scanning moire technique was used to measure thermal deformation in QFP (quad flat pack) packages. The experiment results verify the feasibility of the AFM scanning moire method and show its ability to measure the in-plane deformation.