Abstract:
A semiconductor-containing heterostructure including, from bottom to top, a IH-V compound semiconductor buffer layer, a III-V compound semiconductor channel layer, a HI-V compound semiconductor barrier layer, and an optional, yet preferred, IH-V compound semiconductor cap layer is provided. The barrier layer may be doped, or preferably undoped. The HI-V compound semiconductor buffer layer and the HI-V compound semiconductor barrier layer are comprised of materials that have a wider band gap than that of the πi-V compound semiconductor channel layer. Since wide band gap materials are used for the buffer and barrier layer and a narrow band gap material is used for the channel layer, carriers are confined to the channel layer under certain gate bias range. The inventive heterostructure can be employed as a buried channel structure in a field effect transistor.
Abstract:
Hybrid orientation substrates allow the fabrication of complementary metal oxide semiconductor (CMOS) circuits in which the n-type field effect transistors (nFETs) are disposed in a semiconductor orientation which is optimal for electron mobility and the p-type field effect transistors (pFETs) are disposed in a semiconductor orientation which is optimal for hole mobility. This invention discloses that the performance advantages of FETs formed entirely in the optimal semiconductor orientation may be achieved by only requiring that the device's channel be disposed in a semiconductor with the optimal orientation. A variety of new FET structures are described, all with the characteristic that at least some part of the FET's channel has a different orientation than at least some part of the FET's source and/or drain. Hybrid substrates into which these new FETs might be incorporated are described along with their methods of making.
Abstract:
A method is disclosed for forming a strained Si layer on SiGe, where the SiGe layer has improved thermal conductivity. A first layer (41) of Si or Ge is deposited on a substrate (10) in a first depositing step; a second layer (42) of the other element is deposited on the first layer in a second depositing step; and the first and second depositing steps are repeated so as to form a combined SiGe layer (50) having a plurality of Si layers and a plurality of Ge layers (41-44). The respective thicknesses of the Si layers and Ge layers are in accordance with a desired composition ratio of the combined SiGe layer. The combined SiGe layer (50) is characterized as a digital alloy of Si and Ge having a thermal conductivity greater than that of a random alloy of Si and Ge. This method may further include the step of depositing a Si layer (61) on the combined SiGe layer (50); the combined SiGe layer is characterized as a relaxed SiGe layer, and the Si layer (61) is a strained Si layer. For still greater thermal conductivity in the SiGe layer, the first layer and second layer may be deposited so that each layer consists essentially of a single isotope.
Abstract:
A method of forming a silicon germanium on insulator (SGOI) structure. A SiGe layer (104) is deposited (300) on an SOI wafer (102, 100). Thermal mixing of the SiGe and Si layers is performed (302) to form a thick SGOI (106) with high relaxation and low stacking fault defect density. The SiGe layer (110) is then thinned (306) to a desired final thickness. The Ge concentration, the amount of relaxation, and stacking fault defect density are unchanged by the thinning process. A thin SGOI film is thus obtained with high relaxation and low stacking fault defect density. A layer of Si (112) is then deposited on the thin SGOI wafer. The method of thinning includes low temperature (550°C-700°C) HIPOX or steam oxidation, in-situ HCI etching in an epitaxy chamber, or CMP. A rough SiGe surface resulting from HIPOX or steam oxidation thinning is smoothed with a touch-up CMP, in-situ hydrogen bake and SiGe buffer layer during strained Si deposition, or heating the wafer in a hydrogen environment with a mixture of gases HCI, DCS and GeH4.
Abstract:
The present invention provides a method of fabricating a SiGe-on-insulator substrate in which lattice engineering is employed to decouple the interdependence between SiGe thickness, Ge fraction and strain relaxation. The method includes providing a SiGe-on-insulator substrate material comprising a SiGe alloy layer having a selected in-plane lattice parameter, a selected thickness parameter and a selected Ge content parameter, wherein the selected in-plane lattice parameter has a constant value and one or both of the other parameters, i.e., thickness or Ge content, have adjustable values; and adjusting one or both of the other parameters to final selected values, while maintaining the selected in-plane lattice parameter. The adjusting is achieved utilizing either a thinning process or a thermal dilution process depending on which parameters are fixed and which are adjustable.
Abstract:
A method of forming a thin, high-quality relaxed SiGe-on-insulator substrate (10) material is provided which first includes forming a SiGe or pure Ge layer on a surface of a first single crystal Si layer (14) which is present atop a barrier layer (12) that is resistant to the diffusion of Ge. Optionally forming a Si cap layer (18) over the SiGe or pure Ge layer (16), and thereafter heating the various layers at a temperature which permits interdiffusion of Ge throughtout the first single crystal Si layer (14), the optional Si cap (18) and the SiGe or pure Ge layer (16) thereby forming a substantially relaxed, single crystal SiGe layer atop the barrier layer (12). Additional SiGe regrowth and/or formation of a strained epi-Si layer may follow the above steps. SiGe-on-insulator substrate materials as well as structures including at least the SiGe-on-insulator substrate material are also disclosed herein.
Abstract:
A photovoltaic device and method for fabricating a photovoltaic device include forming a light-absorbing semiconductor structure on a transmissive substrate including a first doped layer (406) and forming an intrinsic layer (410) on the first doped layer, wherein the intrinsic layer includes an amorphous material. The intrinsic layer is treated (412) with a plasma to form seed sites. A first tunnel junction layer is formed (414) on the intrinsic layer by growing microcrystals from the seed sites.
Abstract:
A method for improving the minority lifetime of silicon containing wafer having metallic contaminants therein is described incorporating annealing at 1200°C or greater and providing a gaseous ambient of oxygen, an inert gas and a chlorine containing gas such as HCl.
Abstract:
In the claimed mixed-crystal-orientation channel FET, source/drain regions above the bonded interface 360 have the orientation of the upper semiconductor 350 and source/drain regions below the bonded interface 360 have the orientation of the lower semiconductor 370, so that each part of the source/drain has the same crystal orientation as the semiconductor material laterally adjacent to it. Optional source/drain extensions 392 are disposed entirely in the upper semiconductor layer 350. Optionally, the bonded interface 360 is situated towards the bottom of source/drain regions 380, leaving source/drains 380 mostly in upper semiconductor layer 350.
Abstract:
A method of fabricating silicon-on-insulators (SOIs) having a thin, but uniform buried oxide region beneath a Si-containing over-layer is provided. The SOI structures are fabricated by first modifying a surface of a Si-containing substrate to contain a large concentration of vacancies or voids. Next, a Si-containing layer is typically, but not always, formed atop the substrate and then oxygen ions are implanted into the structure utilizing a low-oxygen dose. The structure is then annealed to convert the implanted oxygen ions into a thin, but uniform thermal buried oxide region.