Damascening

Application(s) Si stock polish tungsten damascene CMP Si final polish CMP post-CMP buff Si stock ILD CMP metal dual damascene ILD CMP shallow trench Isolation metal dual damascene... 

Sputtering- Deposition of copper doped (damascene) almninum interconnects, as well as diffusion barriers, and anti-reflective stacks of Ti/TiN is done by this technique. The metal is heated by an electron beam and "sputters" onto the target. Nitrogen gas is used when TiN is required. 

Damascus steel, also known in the Western world as Damascene steel, is a special type of steel that was and is still used to make sward and knifeblades. Apparently, Damascus steel was first made in India, where it was known as wootz or kuft, and later (during the second century b.c.e.) it was developed in Persia. The name "Damascus steel" was used by the Crusaders to describe the steel used by sword smiths of Damascus, Syria, famous for their ability to hammer and temper the steel into fine blades. The sword blades made from the steel had a reputation for their exceptional properties, especially their toughness, the retention of their cutting edge, as well as for a particular and characteristic decorative pattern on their surface (Figiel 1991). 

Essential oils are organic compounds derived from flowers, seeds, leaves, roots, resins, and citrus fruits. The structures of many fragrant compounds have been studied, and processes for making these valuable compounds in a laboratory have been developed. There are now approximately 5000 synthetically produced chemicals that are available to a perfumer. These chemicals include vanillin, rose oxides, and the damascenes, or rose ketones. 

A production process has recently been implemented by IBM. The aim was to reduce the electrical resistance of the interconnects in their chip to about one-third of the values attainable using aluminum and at the same time increasing the resistance against electromigration. This was made possible by employing electrodeposition of copper in a Damascene method. The manufacturing sequence is presented in Figure 17.11. 

Figure 17.11. Process steps for forming Cu interconnects using the single damascene process (dielectric patterning) (a) planarized substrate (b) dielectric deposition (c) dielectric RIE through photoresist mask (d) etched insulator (e) deposition of diffusion barrier (Ta) and Cu seed layer (/) electrodeposition of Cu into a via (vertical interconnection) ( ) CMP of Cu excess Qi) patterning and deposition of Cu line (wire).

Figure 19.3. Process steps for the dual damascene process (a) deposition of dielectric b) dielectric RIE to define via and line (c) deposition of diffusion barrier and Cu seed iayer (d) eiectrodeposition of Cu into via and trenches foiiowed by Cu CMP.

There is a basic difference between the damascene and through-mask plating processes in the way the trenches and vias are filled with electrochemically deposited Cu, through either an eiectrodeposition or an electroless technique. In multilevel metal structures, vias provide a path for connecting two conductive regions separated... 

Figure 19.6. Growth of deposit in vias and trenches during Cu electrodeposition in (a) damascene and (b) deposition through- mask process.

It s called a khanjar, my guide said cheerfully. Syrian. Made of damascene steel. It was collected in 1204 at the sack of Constantinople by one of theif —his smile faltered— m yancestors. Unfortunately he collected it between his ribs. Fortunately his son was there also and was able to salvage the dagger, if not save the situation. ... 

The acceptance of chemical mechanical planarization (CMP) as a manufacturable process for state-of-the-art interconnect technology has made it possible to rely on CMP technology for numerous semiconductor manufacturing process applications. These applications include shallow trench isolation (STI), deep trench capacitors, local tungsten interconnects, inter-level-dielectric (ILD) planarization, and copper damascene. In this chapter. 

The ideal deposition process would leave a perfectly flat surface. That does not happen, so a planarization process is required to maintain depth of field requirements. For a dielectric planarization process, the ideal planarization process would remove only material in the up areas and remove no material in the down areas. Metal CMP involves the removal of metal overburden, leaving filled plugs or vias (single damascene) or filled vias and inlaid metal lines (dual damascene) with no removal of metal in the inlaid region and no removal of dielectric. 

The second definition of the purpose of a carrier was to remove the overburden of material above a surface above the device plane. For present purposes, we define the device level as the boundary between the material one wishes to remove and the material one wants to keep. It is not necessarily planar, and it moves up with each layer. For oxide CMP, this layer lies within the topmost film layer. For metal CMP, this surface is defined by the topmost surface of the dielectric into which lines and vias are etched for a damascene process. This definition must accommodate a wafer with a modest amount of bow, tilt, warp, and total thickness variation. Furthermore, it must accommodate very modest amounts of bow, warp, tilt. 

D. T. Price, R. J. Gutmann, S. P. Murarka, Damascene copper interconnects with polymer ILDs, J. Thin Solid Films, 308-309, pp. 523-528, 1997. 

Fig. 5. Pattern dependent issues in oxide planarization and polishing of shallow trench isolation and metal damascene structures.

Elbel et al. [12] have studied the polish of tungsten lines in a damascene-style process. The focus of the study and model is to relate the degree of dishing and erosion to the layout patterns, including both density and line-width dependencies. A simple model is used to relate the amount of erosion (e) to the density of metal and the overpolishing time ... 

Fig. 2. Schematic illustrations of two back-end surface configurations after CMP. For the conventional technology, a simple oxide surface must be cleaned up, whereas for damascene structures, both outcropping metals and insulator must be processed together. The difficulty is to preserve the metal lines and the diffusion barriers.

Aluminum is a strong reducing agent ( oai/af+ = —1-66 V), that is, it can be very easily oxidized in cleaning solutions. This behavior could represent an additional limitation of the use of aluminum in the case of damascene structures for which post-CMP cleaning is required. Nevertheless aluminum oxide (AljOj) constitutes a very well known passivating layer but is only stable in relatively neutral pH (4-8.5). 

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