United Microelectronics Corp.

Cheng-Yu Hung

Tri-Rung Yew

Chih-Hung Chen

Fu-Tai Liou

Chien-Chung Lin

Chien-Mei Wang

The present invention is directed to a structure of a gradient barrier layer. The gradient barrier with a composite structure of metal/metal salt of different composition/metal such as Ta/TaN/TaN/TaN/Ta (tantalum/tantalumnitride/tantalum nitride/tantalumnitride/tantalum) is proposed to replace the conventional barrier for copper metallization. The gradient barrier can be formed in a chemical vapor deposition (CVD) process or a multi-target physical vapor deposition (PVD) process. For CVD process, using the characteristics of well-controlled reaction gas injection, the ratio of tantalum (Ta) and nitrogen (N) can be modulated gradually to form the gradient barrier. For the multi-target PVD process, the gradient barrier is formed by depositing multi-layers of different composition TaNfilms. After subsequent thermal cycle processes such as metal alloy, the inter-layer diffusion occurs and a more smooth distribution of Ta and N is achieved for the gradient barrier. The advantages of forming the gradient barrier include a well-controlled process, a strong adhesion between via and landing metal, more uniform step coverage, and less brittle to reduce crack.

Gradient barrier layer for copper back-end-of-line technology

A metal interconnect structure generally includes a lower-layer metal wiring, an upper-layer metal wiring partially overlapping with the lower-layer metal wiring to define a via region thereof, a dielectric layer disposed between the lower-layer metal wiring and the upper-layer metal wiring, a plurality of via plugs arranged in the dielectric layer within a first area of the via region for electrically connecting the lower-layer metal wiring and the upper-layer metal wiring, and a plurality of first dielectric structures embedded in the upper-layer metal wiring within a second area of the via region, in which the first area does not overlap with the second area.

Growing community of inventors

Taipei, Taiwan

Cheng-Yu Hung