Experimental evaluation of metallization quality of through holes in silicon wafers

Аuthors

Didyk P. I.^*, Zhukov A. A.^**, Podgorodetskii S. G.^***, Zabotin Y. M.^****, Golikov E. A.

,

*e-mail: Felix_engine@mail.ru
**e-mail: and_zhukov@mail.ru
***e-mail: rengokku5@mail.ru
****e-mail: zabotello@yandex.ru

Abstract

Metallization of through holes in silicon wafers has been investigated by electron microscopy methods. Dependences of the thicknesses of metallization at various depths of through holes in wafers for single-sidedand double-sided sputtering of chromium and copper, with thickness of 1 µm to 5 µm, as well as with successive galvanic deposition of layers of chrome and copper and chrome and SnBi alloy (tin 98-99%, bismuth 1-2%) on the films of chromium and copper were obtained by vacuum magnetron sputtering method. Optimal modes of through holes metallization in silicon wafers process with closest characteristics of film deposition along o all structure elements, consisting in performing the process in two stages were determined. Initially, employing vacuum magnetro n sputtering method prepare metallization with minimum thickness, ensuring formation of continuous metal film. With two-sided metallization by vacuum magnetron sputtering of chrome and copper, the derived films have minimum thickness in the middle of the through holes. The continuous film is formed at chrome and copper thickness more than 1.7 µm on the surface of the through holes. To ensure the thicknesses it is necessary to perform two-sided sputtering of chrome and copper by vacuum magnetron sputtering methods with thickness less than 4 µm. Then, by galvanic precipitation method refilling to the desired thickness should be performed by galvanic precipitation method. Thickness changing at one-sided metallization sputtering, obtained in through holes by vacuum magnetron sputtering method presents linear decreasing character with increase of the holes' depth.

The minimum thickness of metallization is determined, at which a continuous metal film is provided along the entire depth of the through holes in the wafers. With a thickness of less than 1 µm, the surface of the film in the through holes is not continuous, but an island one. When sprayed from the front side, a continuous film forms on the surface of the plate, but the metal structure it is not continuous on the chamfers and walls.

Keywords:

metallization of through holes, dusting of walls, holes in silicon wafers, thin-film technology

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