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THICK Al-W STACKS WITH TiN BARRIER FOR BEOL APPLICATIONS

IP.com Disclosure Number: IPCOM000039552D
Original Publication Date: 1987-Jun-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Ahn, KY: AUTHOR [+4]

Abstract

The multilevel interconnection structure, shown in Fig. 1, has been discussed in the prior art. The vertical studs may be made of metals other than W, but W is preferred for the reason of its electromigration performance. Such vertical studs may either fill vias (e.g., selective W) or form a column which is subsequently covered by insulator and planarized back to the stud. It is the second-type process which is described here. (Image Omitted) As can be seen in Figs. 2 and 3, the ability to pattern the W studs is clearly demonstrated. For this process, it is required to have a thickness of 1 mm W films on the 1 mm thick Al film for the upper level studs and lines. Figs. 2, 3, 4, 5 and 6 describe the processes, and the steps of Figs. 2, 3, and 4 are the subject of this publication.

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THICK Al-W STACKS WITH TiN BARRIER FOR BEOL APPLICATIONS

The multilevel interconnection structure, shown in Fig. 1, has been discussed in the prior art. The vertical studs may be made of metals other than W, but W is preferred for the reason of its electromigration performance. Such vertical studs may either fill vias (e.g., selective W) or form a column which is subsequently covered by insulator and planarized back to the stud. It is the second-type process which is described here.

(Image Omitted)

As can be seen in Figs. 2 and 3, the ability to pattern the W studs is clearly demonstrated. For this process, it is required to have a thickness of 1 mm W films on the 1 mm thick Al film for the upper level studs and lines. Figs. 2, 3, 4, 5 and 6 describe the processes, and the steps of Figs. 2, 3, and 4 are the subject of this publication. The processes of sputtering W on SiO2 or thin Al (0.1 mm) film cannot be applied to sputtering W on Al film with 1 mm thickness. The large amount of heat generated during the sputtering deposition causes the material reaction between the Al and W films and results in mechanical failure, such as cracking and peeling. The stress is so high that the cracking in the SiO2 substrate was often observed. It is proposed that a process which has a thin layer of diffusion barrier between Al and W be employed. A thin layer of metallic diffusion barrier layer (e.g., TiN, ZrN) can prevent the reaction between Al and W. This does not increase the...