Freescale Semiconductor,inc.

Alexander L Barr

Mariam G Sadaka

Ted R White

Bich-Yen Nguyen

Voon-Yew Thean

Marius K Orlowski

Shawn George Thomas

Dejan Jovanovic

Chun-Li Liu

Da Zhang

Venkat Kolagunta

Victor H Vartanian

Olubunmi O Adetutu

Marius Orlowski

Qianghua Xie

A semiconductor substrate having a silicon layer is provided. In one embodiment, the substrate is a silicon-on-insulator (SOI) substrate having an oxide layer underlying the silicon layer. An amorphous or polycrystalline silicon germanium layer is formed overlying the silicon layer. Alternatively, germanium is implanted into a top portion of the silicon layer to form an amorphous silicon germanium layer. The silicon germanium layer is then oxidized to convert the silicon germanium layer into a silicon dioxide layer and to convert at least a portion of the silicon layer into germanium-rich silicon. The silicon dioxide layer is then removed prior to forming transistors using the germanium-rich silicon. In one embodiment, the germanium-rich silicon is selectively formed using a patterned masking layer over the silicon layer and under the silicon germanium layer. Alternatively, isolation regions may be used to define local regions of the substrate in which the germanium-rich silicon is formed.

Method for making a semiconductor structure using silicon germanium

A wafer having a silicon layer that is strained is used to form transistors. The silicon layer is formed by first forming a silicon germanium (SiGe) layer of at least 30 percent germanium that has relaxed strain on a donor wafer. A thin silicon layer is epitaxially grown to have tensile strain on the relaxed SiGe layer. The amount tensile strain is related to the germanium concentration. A high temperature oxide (HTO) layer is formed on the thin silicon layer by reacting dichlorosilane and nitrous oxide at a temperature of preferably between 800 and 850 degrees Celsius. A handle wafer is provided with a supporting substrate and an oxide layer that is then bonded to the HTO layer. The HTO layer, being high density, is able to hold the tensile strain of the thin silicon layer. The relaxed SiGe layer is cleaved then etched away to expose the thin silicon layer. A low temperature silicon layer is then epitaxially grown with tensile strain, correlated to the tensile strain of the thin silicon layer, on the thin silicon layer using trisilane at a temperature preferably not in excess of 500 degrees Celsius. The resulting tensile strain, correlated to the strain of the thin silicon layer, is thus also correlated to the germanium concentration of the relaxed SiGe layer. The thickness of the low temperature silicon layer, using the trisilane at low temperature, is significantly greater than what would normally be expected for a silicon layer of that tensile strain.

Method for forming a semiconductor structure having a strained silicon layer

Two different transistors types are made on different crystal orientations in which both are formed on SOI. A substrate has an underlying semiconductor layer of one of the crystal orientations and an overlying layer of the other crystal orientation. The underlying layer has a portion exposed on which is epitaxially grown an oxygen-doped semiconductor layer that maintains the crystalline structure of the underlying semiconductor layer. A semiconductor layer is then epitaxially grown on the oxygen-doped semiconductor layer. An oxidation step at elevated temperatures causes the oxide-doped region to separate into oxide and semiconductor regions. The oxide region is then used as an insulation layer in an SOI structure and the overlying semiconductor layer that is left is of the same crystal orientation as the underlying semiconductor layer. Transistors of the different types are formed on the different resulting crystal orientations.

Semiconductor device structure

According to the embodiments to the present disclosure, the process of making a dual strained channel semiconductor device includes integrating strained Si and compressed SiGe with trench isolation for achieving a simultaneous NMOS and PMOS performance enhancement. As described herein, the integration of NMOS and PMOS can be implemented in several ways to achieve NMOS and PMOS channels compatible with shallow trench isolation.

Method of making a dual strained channel semiconductor device

A process for forming a semiconductor device. The process includes forming a template layer for forming a layer of strained silicon. In one example a layer of graded silicon germanium is formed where the germanium is at a higher concentration at the lower portion and at a lower concentration at a top portion. When subject to a condensation process, the germanium of the top portion of the layer diffuses to a remaining portion of the silicon germanium layer. Because the silicon germanium layer has a higher concentration of germanium at lower portions, germanium pile up after condensation may be reduced at the upper portion of the remaining portion of the silicon germanium layer.

Graded semiconductor layer

Semiconductor device structure and method therefor

A process for forming a strained semiconductor layer. The process includes implanting ions into a semiconductor layer prior to performing a condensation process on the layer. The ions assist in diffusion of atoms (e.g. germanium) in the semiconductor layer and to increase the relaxation of the semiconductor layer. After the condensation process, the layer can be used as a template layer for forming a strained semiconductor layer.

Template layer formation

A first semiconductor structure has a silicon substrate, a first silicon germanium layer grown on the silicon, a second silicon germanium layer on the first silicon germanium layer, and a strained silicon layer on the second silicon germanium layer. A second semiconductor structure has a silicon substrate and an insulating top layer. The silicon layer of the first semiconductor structure is bonded to the insulator layer to form a third semiconductor structure. The second silicon germanium layer is cut to separate most of the first semiconductor structure from the third semiconductor structure. The silicon germanium layer is removed to expose the strained silicon layer where transistors are subsequently formed, which is then the only layer remaining from the first semiconductor structure. The transistors are oriented along the &#x3c;100&#x3e; direction and at a 45 degree angle to the &#x3c;100&#x3e; direction of the base silicon layer of the second silicon.

Semiconductor structure having strained semiconductor and method therefor

P channel transistors are formed in a semiconductor layer that has a (110) surface orientation for enhancing P channel transistor performance, and the N channel transistors are formed in a semiconductor layer that has a (100) surface orientation. To further provide P channel transistor performance enhancement, the direction of their channel lengths is selected based on their channel direction. The narrow width P channel transistors are preferably oriented in the &#x3c;100&#x3e; direction. The wide channel width P channel transistors are preferably oriented in the &#x3c;110&#x3e; direction.

Channel orientation to enhance transistor performance

A semiconductor device () is formed by positioning a gate () overlying a semiconductor layer () of preferably silicon. A semiconductor material () of, for example only, SiGe or Ge, is formed adjacent the gate over the semiconductor layer and over source/drain regions. A thermal process diffuses the stressor material into the semiconductor layer. Lateral diffusion occurs to cause the formation of a strained channel () in which a stressor material layer () is immediately adjacent the strained channel. Extension implants create source and drain implants from a first portion of the stressor material layer. A second portion of the stressor material layer remains in the channel between the strained channel and the source and drain implants. A heterojunction is therefore formed in the strained channel. In another form, oxidation of the stressor material occurs rather than extension implants to form the strained channel.

Double gate device having a heterojunction source/drain and strained channel

A process for forming strained semiconductor layers. The process include flowing a chlorine bearing gas (e.g. hydrogen chloride, chlorine, carbon tetrachloride, and trichloroethane) over the wafer while heating the wafer. In one example, the chorine bearing gas is flowed during a condensation process on a semiconductor layer that is used as a template layer for forming a strain semiconductor layer (e.g. strain silicon). In other examples, the chlorine bearing gas is flowed during a post bake of the wafer after the condensation operation.

Semiconductor layer formation

A semiconductor fabrication process includes forming a transistor gate overlying an SOI wafer having a semiconductor top layer over a buried oxide layer (BOX) over a semiconductor substrate. Source/drain trenches, disposed on either side of the gate, are etched into the BOX layer. Source/drain structures are formed within the trenches. A depth of the source/drain structures is greater than the thickness of the top silicon layer and an upper surface of the source/drain structures coincides approximately with the transistor channel whereby vertical overlap between the source/drain structures and the gate is negligible. The trenches preferably extend through the BOX layer to expose a portion of the silicon substrate. The source/drain structures are preferably formed epitaxially and possibly in two stages including an oxygen rich stage and an oxygen free stage. A thermally anneal between the two epitaxial stages will form an isolation dielectric between the source/drain structure and the substrate.

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Crolles, France

Alexander L Barr