Advanced Spin Coating Film Transfer and Hot-Pressing Process for Global Planarization with Dielectric-Material-Viscosity Control

A novel method of controlling the viscosity of dielectric material was developed for global planarization by the spin coating film transfer and hot-pressing (STP) technique. In the STP technique, a base film is spin-coated with a dielectric, the dielectric is hot-pressed to a wafer in vacuum. and the base film is then peeled off from the dielectric. For global planarization in the above steps, the viscosity of the dielectric material is one of the most important factors. We propose controlling the viscosity by vacuum drying in the process chamber. The relationship between viscosity and vacuum drying was investigated experimentally, and the effect of viscosity on gap-filling was clarified by analytical modeling. We applied the control method to STP experiments using patterned wafers and a low-k organic material, and found that it achieves complete gap-filling and good uniformity in film thickness. STP planarized line-and-spaces as large as 100 mum wide achieving a small variation in planarity of 0.43%. With this viscosity-control method, the STP technique is applicable to low-k materials.