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Chrome Studs for Continuous Chrome Barriers

IP.com Disclosure Number: IPCOM000038727D
Original Publication Date: 1987-Feb-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Smith, DM: AUTHOR

Abstract

In some bipolar semiconductor manufacturing processes there is a problem with Al penetration of the Cr barrier due to a discontinuity in the Cr at the periphery of a contact hole. A solution to the problem is described which eliminates the discontinuities with a two-step Cr deposition process using Pt to lift off the first Cr layer. The problem is illustrated in Fig. 1, which is a simulation of the shadow effect during Cr deposition. The basic structure consists of Si3N4 2, SiO2 3, an epi layer 4, and a PtSi deposition layer 5. As the Cr 1 builds up on the nitride ledge during deposition, it shadows the region below it. Cr deposition is prevented on the periphery of the (Image Omitted) contact, resulting in a discontinuous barrier through which Al penetration can occur.

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Chrome Studs for Continuous Chrome Barriers

In some bipolar semiconductor manufacturing processes there is a problem with Al penetration of the Cr barrier due to a discontinuity in the Cr at the periphery of a contact hole. A solution to the problem is described which eliminates the discontinuities with a two-step Cr deposition process using Pt to lift off the first Cr layer. The problem is illustrated in Fig. 1, which is a simulation of the shadow effect during Cr deposition. The basic structure consists of Si3N4 2, SiO2 3, an epi layer 4, and a PtSi deposition layer 5. As the Cr 1 builds up on the nitride ledge during deposition, it shadows the region below it. Cr deposition is prevented on the periphery of the

(Image Omitted)

contact, resulting in a discontinuous barrier through which Al penetration can occur. Shadowing has nothing to do with the nitride ledge, but is the cause of any step coverage problem [1,2]. In the two-step process, the first step is to create a Cr stud in the contact hole. Standard processing is followed to the Pt 6 deposition step (Fig 2). Sintering may take place here or wait until after Cr deposition [3]. Following Pt/Cr sinter, the device is as shown in Fig. 2. Aqua regia is next used to remove Pt from the nitride. Cr deposited on the Pt is removed at the same time, but the Cr on the PtSi remains unharmed (Fig. 3), with a Cr stud remaining. Standard photolithography takes place, and then the final Cr deposition. Since there is no Cr...