Back-end A Low-k Materials And Reel Package Reliability Study

As the VLSI technology is developing rapidly, the electrical device are becoming more smaller and lighter in recent years, they consume less power but own more functions compared with that before. According to these requirements, it is necessary to introduce the low-dielectric-constant (k) dielectrics and Cu for interconnection, and on the other side, packaging technique and reliability are also facing great challenges. This thesis mainly focus on the interconnection and packaging technologies, including the following sections:1. Preparation and analysis of the Low-k films(1) First we use SiH₄, N₂O, C₂F₆ as precursors to deposit the SiCON films with PECVD under different precursor flow rate, temperature and RF powers. The deposited SiCON films are examined using XPS, SEM and CV for chemical and electrical properties. The obtained SiCON film is found to be desirable.(2) Based on the previous results, the influence of the RF power to the deposited films is further studied. With the analysis of XPS, CV, IV and FTIR, it could be found the k value of the SiCON film could be lowered with increasing RF power, while the leakage current still remain very low. The underlying mechanisms are also further addressed.2. Reliability study and FEA simulation of the Tape Carrier Package(1) The Inner lead bonding technique is used to electrically connect the driving IC and the outer circuit in TCP, so the failure and weakness of the IL have always been our concerns. Since many parameters can influence the ILB process (8 key parameters), so it will take a lot of time and cost to find the optimum parameter group by trying one by one. In this thesis, the method of DOE is introduced, and thus the optimized process parameters are obtained through only 18 orthogonal experiments; Then the peeling experiment is executed and the results show that the failure probability of the ILB is significantly decreased by using the extracted optimum parameters by DOE. In addition, the ANSYS FEA tool is introduced to study the reason therein.(2) The Darveaux model which is based on the energy accumulation principle is introduced to study the thermal fatigue life of the TCP. First using ANSYS, a three dimensional symmetric model for the TCP is established to simulate and calculate the deformation and the SED of inner leads of the model under thermal cycling loading. SED is then used to calculate the thermal fatigue life of the inner leads. The result is compared with the classic Manson-Coffin method to examine its availability.