1. Field of the Invention
The present invention generally relates to a FINFET transistor structure and a method for forming various FINFET transistor structures. In particular, the present invention is directed to a method for forming various FINFET transistor structures by different possibilities of formation of oxide layers to reduce the leak current of the FINFET transistor structure or to maintain the heat-dissipating of the FINFET transistor structure.
2. Description of the Prior Art
One of the purposes of the development of the semiconductor industry is to enhance the efficiency of the semiconductor devices and to reduce the energy consumption of the semiconductor devices. When it comes to enhancing the efficiency of the semiconductor devices, it is already known in the prior art that different lattice structures may facilitate the mobility of the electrons or the holes.
For example, a higher carrier mobility can be observed when a metal-oxide-semiconductor (MOS) is constructed on an n-channel of a (100) lattice of Si, and similarly a higher carrier mobility can be observed when a metal-oxide-semiconductor (MOS) is constructed on a P-channel of a (110) lattice of Si. As a result, when a planar complementary MOS is constructed, Si of different lattices is formed together to get a substrate so that MOS of n-channel is constructed on a (100) lattice, and MOS of P-channel is constructed on a (110) lattice to get a better performance.
However, as the critical dimension of the devices shrinks, in particular for the generations after 65 nm, the multi-gate devices such as a fin field effect transistor (FinFET) is proposed to replace the planar complementary MOS since it is getting harder and harder to reduce the physical dimension of the conventional planar complementary MOS. However, in one aspect, because some of the bottom of the fin field effect transistor is directly connected to the substrate, inevitable leak current is always a serious problem. In another aspect, should the fin field effect transistor be constructed on an SOI substrate to solve the problem of inevitable leak current, another problem arises because of a higher production cost due to much more expensive SOI substrates.
Given the above, a novel method for forming a FINFET transistor structure as well as a novel FINFET transistor structure are still needed to bring a resolution to the dilemma.