Adhesion measurement of thin films to a porous low dielectric constant film using a modified tape test

Abstract

In the microelectronics industry, a simple tape test (ASTM 3359) is typically used to qualitatively study the adhesion of dielectric films. In this work, a novel approach to conduct the tape test is proposed. This new method eliminates the inconsistency in the results encountered in the traditional tape test, and, at the same time, it provides both qualitative and quantitative results. This approach employs a spring-loaded mechanism and eliminates the subjective interpretation of the results of the traditional tape test. It also provides quantitative measures of the peel rate and force, factors that are relevant in the characterization of the interfacial strength of thin films. We illustrate the use of this new, modified tape test (MTT) in the study of the adhesion of multi-layered thin film structures. This study is of significance to the understanding of the damascene interconnect process integration. Thus, the adhesion of various films (e.g. oxide, insulator and metallic films) on the sponon porous carbon-doped silicon dioxide low dielectric constant (k) material is examined. Also, the effects of surface treatments (ion implantation and N2 plasma) and curing temperature of the porous low-k films on the adhesion of the overlying oxide films are also described. An explanation of the adhesion strength with respect to the thickness of the cap layer (overlayer) is presented as well.