High- dielectric gate oxide

As already mentioned, one possible way to eliminate the fundamental limitations of current field effect transistors would be to substitute the sihca by other high dielectric function oxides as gate materials. Unfortunately, the growth of high-quality oxide films on siUcon substrates is not a simple task, and much work is being devoted to develop appropriate methods. For example, it has been shown that the formation of thin films of alkaline-earth-met-... 

It has been determined that Si02 needs to be replaced with a physically thicker layer of oxides of a higher dielectric constant (K) material, or high K gate oxides [1-8]. The maximum current density in interconnects between transistors resulted in the replacement of aluminum with copper as the conductor. The FET gate stack, which is the gate electrode and the dielectric layer between the gate and the silicon channel, is now the most serious problem. 

Robertson, J. 2006. High dielectric constant gate oxides for metal oxide Si transistors. Rep. Prog. Phys. 69 327-396. 

Materials with better properties are also of interest as possible replacements for aSiO for gate oxide applications, since the ultrathin SiO layers required for low-voltage, high-drive logic is inherently too leaky to be employed. Instead, a thicker layer of a material with a higher dielectric constant is needed. As in capacitor appli-... 

In addition to requiring high dielectric films for DRAM capacitors (dynamic random access memories) and for the active memory elements in FRAMs, the microelectronics industry has a stated demand for a replacement for Si02 gate oxides very soon. The leading candidate is hafnia (Hf02), and there are significant opportunities for the ferroelectrics community to contribute to the solution of this problem. 

The discussion of potential benefits and drawbacks of using high-k dielectrics as a gate oxide for power SiC UMOS transistors has been made in several publications [8, 10, 11]. A comparative analysis of different insulating materials suitable as gate... 

A serious potential problem related to the use of high-k gate dielectrics in SiC power MOSEETs can be encountered due to the much smaller (sometimes-negative) conduction band offsets between SiC and high-k metal oxides compared with silicon dioxide (see Table 5.1). Time-dependent dielectric breakdown (TDDB) and hot... 

Figure 4.14. Cross-section high-resolution transmission electron microscopy (HRTEM) images of gate oxides for MOSFETs. Provided is an illustration of film thicknesses that result in identical capacitance for Si02( = 3.8), relative to a high- c dielectric k = 23.9) gate oxide. Hence, increased gate capacitance will result from thinner films comprising high- c dielectric materials. Reproduced with permission from Intel Corporation (http //www.intel.com).

Mabakal, A. et al., Inorganic oxide core, polymer shell nanocomposite as a high K gate dielectric for flexible electronics applications, J. Am. Chem. Soc. Ill (42), 14655-14662, 2005. 

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