Copper-selective electrochemical filling of macropore arrays for through-silicon via applications

Abstract

In this article, the physico-chemical and electrochemical conditions of through-silicon via formation were studied. First, macropore arrays were etched through a low doped n-type silicon wafer by anodization under illumination into a hydrofluoric acid-based electrolyte. After electrochemical etching, ‘almost’ through-silicon macropores were locally opened by a backside photolithographic process followed by anisotropic etching. The 450 × 450-μm² opened areas were then selectively filled with copper by a potentiostatic electrochemical deposition. Using this process, high density conductive via (4.5 × 105 cm−²) was carried out. The conductive paths were then electrically characterized, and a resistance equal to 32 mΩ/copper-filled macropore was determined.

Porous Silicon in Microelectronics: From Academic Studies to Industry

“…Recently, 6'' hybrid substrates compatible with industrial scale microelectronics processes were performed by our group. Deep PSi regions (> 100 µm) were locally fabricated by anodization through a fluoropolymer mask (18). The stress or mechanical issues attached to high thickness processing will be discussed in the next part.…”

Contactless bottom-up electrodeposition of nickel for 3D integrated circuits

“…[1][2][3][4] In conventional electrodeposition systems, ions in solution (e.g. 6 Semiconductor grade silicon is so sensitive to copper poisoning that nearly all fabrication centers have noncopper dedicated areas in which nothing that has contacted copper is permitted. The circuit is completed by means of using a sacricial anode which is typically made of the same metal that is being deposited and dissolves proportionally as the metal is deposited.…”

“…However, copper must be isolated from bulk silicon and dielectric materials by a diffusion barrier to prevent poisoning. 6 Semiconductor grade silicon is so sensitive to copper poisoning that nearly all fabrication centers have noncopper dedicated areas in which nothing that has contacted copper is permitted. Nickel has a lower conductivity than copper, but does not require a diffusion barrier to prevent poisoning of the substrate and exhibits a similar electroplating efficiency.…”

Porous silicon formation by hole injection from a back side p+/n junction for electrical insulation applications

“…Depending on reaction parameters, such as silicon type, resistivity and solution composition, various PS morphologies can be produced [1,2] determining the possible applications. For instance, ordered or random macroporous silicon can be used in through-silicon via technology [3] or for energy storage as electrode material [4,5]. Further, mesoporous silicon is expected to be an interesting material for electrical insulation of electronic devices [6][7][8][9] because of its dc and RF electrical properties (low dielectric constant and high resistivity) [10].…”