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Ion Beam Induced Mixing for Via Contact in MCP Module

IP.com Disclosure Number: IPCOM000038149D
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Chen, PC: AUTHOR [+4]

Abstract

In some structures it is desired to use a thin Cr layer to enhance adhesion of a metal, such as copper, to a polymer surface. In the area where there are metal vias (M1) in the polymer, the pressure of the Cr layer can create an interface Cr-oxide layer that affects the contact resistance of the via. Thus, when another metal layer (M2) is deposited on the M1 via, poor conductivity can result. To avoid this, the Cr layer is deposited to be discontinuous in the via area so that good M2-M1 metal contact can be made.

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Ion Beam Induced Mixing for Via Contact in MCP Module

In some structures it is desired to use a thin Cr layer to enhance adhesion of a metal, such as copper, to a polymer surface. In the area where there are metal vias (M1) in the polymer, the pressure of the Cr layer can create an interface Cr- oxide layer that affects the contact resistance of the via. Thus, when another metal layer (M2) is deposited on the M1 via, poor conductivity can result. To avoid this, the Cr layer is deposited to be discontinuous in the via area so that good M2-M1 metal contact can be made.

It is difficult to sputter a discontinuous Cr layer that is very thin (approximately 100Ao). This, plus the higher oxide concentration in the Cr film, affects the via resistance. This problem can be solved by using ion beam induced mixing to establish a low resistance via interface. This is illustrated in Figs. 1 and 2 in which the M1 and M2 layers are copper (Cu).

The key element of the method is to use a slow rate (N1o/ sec) at a moderate temperature (N200oC) to sputter the initial portion of the M2 Cu layer. As illustrated in Fig. 1, when Cu ions are sputtered onto the via covered with M2 Cr and M1 Cu, they carry a certain amount of kinetic energy (N10-15 eV) sufficient to produce defects or disorder in the near-surface layer 10. Such defects can enhance the rate of mixing of Cu with Cr by several orders of magnitude, even at a moderate temperature of about 200oC. In addition, the ion mixing will...