TY - THES

T1 - Interface adhesion measurement of industrially processed layers on polyimide

AU - Gutnik, Dominik

N1 - embargoed until 23-02-2028

PY - 2023

Y1 - 2023

N2 - With the continuous development of electronics and the need for more efficient electronic devices, it is necessary to investigate the mechanic response of different material systems in use. Since poor adhesion can be detrimental to the lifetime and functionality of electronic devices, it is important to study adhesion in different material combinations. In this thesis, the adhesion of Silicon nitride (SiNx) and WTi deposited onto polyimide (PI) were evaluated. On the WTi/PI interface, the effect of a controlled plasma treatment on the adhesion was investigated as well. The processing of the specimens was quite unique since they were produced on a wafer level and released by etching of a sacrificial layer. While the WTi film with untreated WTi/PI broke spontaneously upon lifting from the wafers and demonstrated some delamination, the other two film systems needed to be strained to induce cracks and buckles. To gain insight into the adhesion, the resulting buckles were measured, and the dimensions were used to estimate the respective adhesion energies using a model for spontaneous buckling and tensile induced delamination. The results showed a significant improvement of the adhesion of WTi on PI after the pre-treatment of PI. The SiNx films also demonstrated superior bonding in comparison to the untreated WTi/PI interfaces. Transmission electron microscope (TEM) investigations showed a more diffuse transition of the SiNx to the PI in comparison to the WTi, which could explain this difference in adherence to the PI.

AB - With the continuous development of electronics and the need for more efficient electronic devices, it is necessary to investigate the mechanic response of different material systems in use. Since poor adhesion can be detrimental to the lifetime and functionality of electronic devices, it is important to study adhesion in different material combinations. In this thesis, the adhesion of Silicon nitride (SiNx) and WTi deposited onto polyimide (PI) were evaluated. On the WTi/PI interface, the effect of a controlled plasma treatment on the adhesion was investigated as well. The processing of the specimens was quite unique since they were produced on a wafer level and released by etching of a sacrificial layer. While the WTi film with untreated WTi/PI broke spontaneously upon lifting from the wafers and demonstrated some delamination, the other two film systems needed to be strained to induce cracks and buckles. To gain insight into the adhesion, the resulting buckles were measured, and the dimensions were used to estimate the respective adhesion energies using a model for spontaneous buckling and tensile induced delamination. The results showed a significant improvement of the adhesion of WTi on PI after the pre-treatment of PI. The SiNx films also demonstrated superior bonding in comparison to the untreated WTi/PI interfaces. Transmission electron microscope (TEM) investigations showed a more diffuse transition of the SiNx to the PI in comparison to the WTi, which could explain this difference in adherence to the PI.

KW - Dünnschichten

KW - Adhäsion

KW - zuginduzierte Delamination

KW - spontane Delamination

KW - Grenzschichten

KW - Thin films

KW - adhesion

KW - tensile induced delamination

KW - spontaneous delamination

KW - interfaces

M3 - Master's Thesis

ER -