Multilayer aluminum nitride

Ellice Y. Yuh, John W. Lau, Debra S. Horn, and William T. Minehan, Current Processing Capabilities for Multilayer Aluminum Nitride, International Journal of Microelectronics and... 

L. E. Carpenter, Single and Multilayer Coatings Containing Aluminum Nitride. U.S. Patent No. 5,183,684, Feb. 2, 1993. Dow Coming Corporation USA. 

Aluminum nitride may be used in composite structures containing aluminum for either structural or electronic applications, due to its attractive thermal, electronic, and mechanical properties [176-178]. AlN ceramics are also known to have a sufficiently high-temperature compatibility with refractory metals. Finally, AlN is an ecologically safe material. The structure of AlN as a ceramics layer of the multilayer Al/AlN composites has been investigated to only a limited degree [179]. 

Table 1.1.1 shows properties of the new and standard aluminum nitride compositions, compared with multilayer alumina [1]. The main difference between... 

Example 1 Kurokawa et al. used SEM and TEM to investigate the mechanism of adhesion between aluminum nitride (AIN) and tungsten (W) electrodes in a multilayer capacitor. Several investigators have reported the absence of a chemical reaction interlayer between W and AIN, but the mechanical strength of the interface is still considerable (>20 MPa). Electron microprobe analysis using an... 

HTCC is an all-inclusive term to describe ceramic substrates that are consolidated at temperatures above about 1000°C. Applied to electronic packaging, this descriptor includes aluminum oxide, aluminum nitride (AIN), and a variety of other developmental or seldom-used materials. Until recently, discriminating between HTCC and low-temperatme cofired ceramics (LTCC) was elementary, as the firing temperatures differed by roughly 600°C. To confoimd that difference, an intermediate-firing multilayer ceramic, or medimn-temperature cofired ceramic (MTCC), has recently been introduced. Details on the processing and properties of this material will be discussed in Section 6.2 and Section 6.4. 

Substrates made by the multilayer process from tape cast alumina have received considerable attention in recent years for multichip module (MCM) applications. An MCM consists of an array of closely packed chips on an interconnect board several inches on a side. Cofired ceramic is attractive relative to organic laminates because its thermal conductivity is almost 2 orders of magnitude higher, an important consideration in high-density circuitry. In addition both alumina and aluminum nitride ceramics are more closely matched to silicon in CTE than are organic boards. For similar reasons, alumina and AIN are attractive for ball grid array (EGA) mounting of chips. ... 

Aluminum nitride has been demonstrated to be suitable for blank substrates for high power and high frequency applications. Substrates from many sources are available for thick or thin film metaUization. Thick film paste manufacturers now supply pastes formulated for aluminum nitride. The multilayer process described in the previous section has also been adapted for aluminum nitride. Both multilayer substrates and packages are available commercially. 

Ceramic-glass composite materials may be used to economically fabricate very complex multilayer interconnection structures. The materials in powder form are mixed with an organic binder, a plasticizer, and a solvent and formed into a slurry by ball or roll milling. The slurry is forced under a doctor blade and dried to form a thin sheet, referred to as green tape or greensheet. Further processing depends on the type of material. There are three basic classes of materials high temperature cofired ceramic (HTCC), low temperature cofired ceramic (LTCC), and aluminum nitride. 

Aluminum Nitride. Aluminum nitride multilayer circuits are formed by combining AIN powder with yttria or calcium oxide. Glass may also be added. Sintering may be accomplished in three ways ... 

Transition metal carbides can be used as diffusion barriers like transition metal nitrides in multilayer metallization schemes for integrated circuits. Layers on the order of lOOnm are applied and are produced by sputtering methods. The high chemical stability of these transition metal carbides, especially those of group 4, are exploited to prevent interaction of metal or component layers such as silicon, aluminum, and silicides upon thermal load in production processes. This load would cause electrical or even structural deterioration of the multilayer packages. 

---