Browse Prior Art Database

Vertical interconnection between layers separated by thick isolation layers

IP.com Disclosure Number: IPCOM000010858D
Original Publication Date: 2003-Jan-28
Included in the Prior Art Database: 2003-Jan-28
Document File: 3 page(s) / 8K

Publishing Venue

IBM

Abstract

Disclosed is a new process sequence to create electrical interconnections through a thick separating layer. The interconnection consists of three parts. First, the electrical contact of the lower layer. Second, the separation material (e.g. Al2O3) which separates spatially the lower layer from the upper layer. Third, the interconnecting layer which is a thin film stripe of electrically conductive material. Here an idea is discussed where the interconnecting layer is thinner than the separating layer. For example, assuming a separating layer of 5 mu thickness, the interconnecting layer could be as thin as 0.1 mu. This is possible because the interconnecting layer is deposited onto a slope. The main part of the separation is overbridged by that slope.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 50% of the total text.

Page 1 of 3

Vertical interconnection between layers separated by thick isolation layers

  Disclosed is a new process sequence to create electrical interconnections through a thick separating layer. The interconnection consists of three parts. First, the electrical contact of the lower layer. Second, the separation material (e.g. Al2O3) which separates spatially the lower layer from the upper layer. Third, the interconnecting electric layer which is a thin film stripe of conductive material. Here an idea is discussed where the interconnecting layer is thinner than the separating layer. For example, assuming a separating layer of 5 mu thickness, the interconnecting layer could be as thin as 0.1 mu. This is possible because the interconnecting layer is deposited onto a slope. So, the main part of the separation is overbridged by that slope. Using this approach connector material is saved, which is beneficial in case of gold connectors.

Introduction

    Figure 1 illustrates the starting situation. Two layers are separated by a thick isolation. The isolation layer can serve for electrical isolation or mechanical protection. This layer can be in the thickness range of 1 to 100 mu. An example for such an isolation layer is the overcoat in thin film read/write heads for magnetic storage disk drives. Of course it is time and cost consuming to deposited such thick layers. In most cases, not only the separation is required but an interconnect is required, too. Consequently, two thick layers have to be deposited. This is illustrated in figure 2. The production of this kind of interconnection needs a third step. After deposition of the isolation layer, a via hole has to be etched through the full isolation. In the third step the interconnect is deposited, forming a 'plug' into the etched via hole. All three steps tend to require long deposition or removal times, respectively.

contact of top layer

Figure 1: definition of the layers

interconnect

Figure 2: The thickness of the interconnecting layer is similar to the isolation layer.

    Beside the deposition times, other disadvantages of the simple design in figure 2 are obvious. The top layer cannot be smaller than the top opening of the via hole. Typically, its horizontal dimensions are at least two times the thickness of the

       contact of low er layer isolation layer

[This page contains 4 pictures or other non-text objects]

Page 2 of 3

isolation layer. This is because the edges of the etched via hole are no...