Novel Trench Wiring Formation Process using Photosensitive Insulation Film for Next Generation Packaging

Abstract

As there is an increasing demand for advanced electronic devices, high-density and fine circuit is required more than ever before. However, it is difficult to fabricate fine Cu wiring below 5 μm on an organic substrate using current processes such as semi-additive process (SAP). In this paper, the trench wiring formation process with photosensitive organic materials was studied to make fine Cu wiring below 5 μm. Photosensitive organic materials were mainly used as protection and insulation layers of very large scale integrated circuit because they simplify via formation processing by photolithography. We newly developed film-type photosensitive insulation material for high-density interposer. The photosensitive insulation film (PIF) showed high resolution (L/S = 3/3μm for 10 μm-thick film) and suitability to novel trench Cu wiring formation process. Cu embedded wiring (L/S = 3/3 μm for 10 μm-thick Cu) was enabled by trench Cu wiring formation process.

Trench Wiring Process Applying Electroless Nickel Plating for Fine and High-Aspect-Ratio Pattern

“…In the previous report, we developed a photosensitive material as insulation layer and found that it was suitable to trench process with good controllability of pattern shape by photolithography. We also reported that the aspect ratio of Cu wiring by the trench process was 3.3 (line/space = 3 μm/3 μm) [7]. Figure 1 shows trench wiring formation process with the photosensitive material.…”

“…To overcome the issues with Cu wiring formation below 5 μm, embedded Cu wiring formation process, called "trench process," was reported [6][7][8][9]. One of advantages of the process is no collapse of fine wiring since the wiring is supported by insulation material in three directions.…”

Novel Photoresist using Photodeprotectable <i>N</i>-Alkoxybenzyl Aromatic Polyamide

“…Photosensitive heat-resistant materials, such as polyimides (PI) or polybenzoxazole (PBO), exhibit excellent mechanical properties and are used in microelectronics application [4][5][6][7][8][9][10] to simplify via formation processing by photolithography. We have developed film-type photosensitive heatresistant materials for high-density packaging, such as phenolic-resin-based negative tone resist containing cross-linkers and photo acid generator (PAG), and these materials provide high resolution (10 μm via for 25 μm-thick film), high adhesion to Ti/Cu sputtering seed layer, and capability to fabricate Cu wiring of less than 5 μm [11,12]. The sputtering method can enhance adhesion strength, but increase in throughput and high cost is problematic.…”