摘要:
Various processes are provided for producing a p-channel and/or n-channel transistor. The present processes are thereby applicable to NMOS, PMOS or CMOS integrated circuits, any of which derive a benefit from having an asymmetrical LDD structure. The asymmetrical structure can be produced on a p-channel or n-channel transistor in various ways. According, the present process employs various techniques to form an asymmetrical transistor. The various techniques employ processing steps which vary depending upon the LDD result desired. First, the LDD implant can be performed only in the drain-side of the channel, or in the drain-side as well as the source-side. Second, the gate conductor sidewall surface adjacent the drain can be made thicker than the sidewall surface adjacent the source. Thickening of the drain-side sidewall spacer can be achieved either by depositing oxide upon a nitride-bearing film, or by growing additional oxide upon an exposed silicon surface having the source-side sidewall protected from growth. Third, the drain-side can be enhanced relative to the source-side by using an LTA implant. There may be numerous other modifications and alternative processing steps, all of which are described herein. Regardless of the sequence chosen, a barrier implant may be employed to prevent deleterious ingress of p-type implant species into the channel region. The present fabrication sequence reduces source-side resistance to enhance drive current--a desirable outcome for high speed circuits.
摘要:
Various processes are provided for producing a p-channel and/or n-channel transistor. The present processes are thereby applicable to NMOS, PMOS or CMOS integrated circuits, any of which derive a benefit from having an asymmetrical LDD structure. The asymmetrical structure can be produced on a p-channel or n-channel transistor in various ways. According, the present process employs various techniques to form an asymmetrical transistor. The various techniques employ processing steps which vary depending upon the LDD result desired. First, the LDD implant can be performed only in the drain-side of the channel, or in the drain-side as well as the source-side. Second, the gate conductor sidewall surface adjacent the drain can be made thicker than the sidewall surface adjacent the source. Thickening of the drain-side sidewall spacer can be achieved either by depositing oxide upon a nitride-bearing film, or by growing additional oxide upon an exposed silicon surface having the source-side sidewall protected from growth. Third, the drain-side can be enhanced relative to the source-side by using an LTA implant. There may be numerous other modifications and alternative processing steps, all of which are described herein. Regardless of the sequence chosen, a barrier implant may be employed to prevent deleterious ingress of p-type implant species into the channel region. The present fabrication sequence reduces source-side resistance to enhance drive current--a desirable outcome for high speed circuits.
摘要:
A semiconductor transistor which includes a silicon base layer, a gate dielectric formed on the silicon base layer, first and second silicon source/drain structures, first and second spacer structures, and a silicon gate structure is provided. A method for forming the semiconductor transistor may include a semiconductor process in which a dielectric layer is formed on an upper surface of a semiconductor substrate which includes a silicon base layer. Thereafter, an upper silicon layer is formed on an upper surface of the dielectric layer. The dielectric layer and the upper silicon layer are then patterned to form first and second silicon-dielectric stacks on the upper surface of the base silicon layer. The first and second silicon-dielectric stacks are laterally displaced on either side of a channel region of the silicon substrate and each include a proximal sidewall and a distal sidewall. The proximal sidewalls are approximately coincident with respective boundaries of the channel region. Thereafter, proximal and distal spacer structures are formed on the proximal and distal sidewalls respectively of the first and second silicon-dielectric stacks. A gate dielectric layer is then formed on exposed portions of the silicon base layer over a channel region of the base silicon layer. Portions of the first and second silicon-dielectric stacks located over respective source/drain regions of the base silicon layer are then selectively removed. Silicon is then deposited to fill first and second voids created by the selected removal of the stacks. The silicon deposition also fills a silicon gate region above the gate dielectric over the channel region. Thereafter, an impurity distribution is introduced into the deposited silicon. The deposited silicon is then planarized to physically isolate the silicon within the gate region from the silicon within the first and second voids resulting in the formation of a transistor including a silicon gate structure and first and second source/drain structures.
摘要:
Various processes are provided for producing a p-channel and/or n-channel transistor. The present processes are thereby applicable to NMOS, PMOS or CMOS integrated circuits, any of which derive a benefit from having an asymmetrical LDD structure. The asymmetrical structure can be produced on a p-channel or n-channel transistor in various ways. According, the present process employs various techniques to form an asymmetrical transistor. The various techniques employ processing steps which vary depending upon the LDD result desired. First, the LDD implant can be performed only in the drain-side of the channel, or in the drain-side as well as the source-side. Second, the gate conductor sidewall surface adjacent the drain can be made thicker than the sidewall surface adjacent the source. Thickening of the drain-side sidewall spacer can be achieved either by depositing oxide upon a nitride-bearing film, or by growing additional oxide upon an exposed silicon surface having the source-side sidewall protected from growth. Third, the drain-side can be enhanced relative to the source-side by using an LTA implant. There may be numerous other modifications and alternative processing steps, all of which are described herein. Regardless of the sequence chosen, a barrier implant may be employed to prevent deleterious ingress of p-type implant species into the channel region. The present fabrication sequence reduces source-side resistance to enhance drive current-a desirable outcome for high speed circuits.
摘要:
A semiconductor process in which a dielectric layer is formed on an upper surface of a semiconductor substrate which includes a silicon base layer. Thereafter, an upper silicon layer is formed on an upper surface of the dielectric layer. The dielectric layer and the upper silicon layer are then patterned to form first and second silicon-dielectric stacks on the upper surface of the base silicon layer. The first and second silicon-dielectric stacks are laterally displaced on either side of a channel region of the silicon substrate and each include a proximal sidewall and a distal sidewall. The proximal sidewalls are approximately coincident with respective boundaries of the channel region. Thereafter, proximal and distal spacer structures are formed on the proximal and distal sidewalls respectively of the first and second silicon-dielectric stacks. A gate dielectric layer is then formed on exposed portions of the silicon base layer over a channel region of the base silicon layer. Portions of the first and second silicon-dielectric stacks located over respective source/drain regions of the base silicon layer are then selectively removed. Silicon is then deposited to fill first and second voids created by the selected removal of the stacks. The silicon deposition also fills a silicon gate region above the gate dielectric over the channel region. Thereafter, an impurity distribution is introduced into the deposited silicon. The deposited silicon is then planarized to physically isolate the silicon within the gate region from the silicon within the first and second voids resulting in the formation of a transistor including a silicon gate structure and first and second source/drain structures.
摘要:
A process is provided for producing active and passive devices on various levels of a semiconductor topography. As such, the present process can achieve device formation in three dimensions to enhance the overall density at which an integrated circuit is formed. The multi-level fabrication process not only adds to the overall circuit density but does so with emphasis placed on interconnection between devices on separate levels. Thus, high performance interconnect is introduced whereby the interconnect is made as short as possible between features within one transistor level to features within another transistor level. The interconnect employs a via routed directly between the drain region of an upper level transistor to the gate of a lower level transistor so as to effect a direct coupling between the output of one transistor to the input of another. Direct coupling in this fashion affords a lower propagation delay and therefore achieves the benefit of a higher performance, faster switching circuit.
摘要:
An integrated circuit fabrication process is provided in which an interconnect having a least one vertical sidewall surface is formed. The interconnect thusly formed allows for higher packing density within the ensuring integrated circuit since the interconnect requires less space to accommodate the same current density as an interconnect having sloped (i.e., non-vertical) sidewall surfaces. A semiconductor topography is provided which includes transistors arranged upon and within a silicon-based substrate. A first interlevel dielectric is deposited across the semiconductor topography, and portions of the dielectric are removed to form vias to select portions of the transistors. Conductive plugs are formed exclusively within the vias. An insulating material patterned with vertical sidewall surfaces is then formed across the first interlevel dielectric and a portion of the plugs. The insulating material is then patterned. Conductive material is then deposited across the patterned insulating material, the plug upper surfaces, and the first interlevel dielectric. A portion of the conductive material is anisotropically removed to form interconnects which are laterally adjacent to the sidewall surfaces of the insulating material. Each interconnect includes two surfaces, one of which is vertical to the underlying topography and the other of which extends a distance from the fist surface and links with an upper region of the surface in an arcuate pattern. The first lateral surface of the interconnect is directly adjacent to a sidewall surface of the insulating material and is therefore intended to be vertical. The second lateral surface extends a distance from the first lateral surface, constrained the limitations of deposition and not lithography.
摘要:
A shallow junction MOS transistor comprising a semiconductor substrate having an upper region that includes a first and a second lightly doped region laterally displaced on either side of the channel region. The first and second lightly doped regions extend to a junction depth below the upper surface of the semiconductor substrate. A first and a second lightly doped impurity distribution are located within the first and second source/drain regions of the semiconductor substrate. The shallow junction transistor further includes a gate dielectric formed on an upper surface of the channel region of the semiconductor substrate. A conductive gate that includes a first and a second sidewall is formed on the gate dielectric. A gate insulator is formed in contact with the first and second sidewalls of the conductive gate. First and second source/drain structures are formed above the upper surface of the semiconductor substrate. The first and second source/drain structures are laterally displaced over the first and second lightly doped regions of the semiconductor substrate.
摘要:
An improved planarization process for a trench dielectric is presented. A shallow trench isolation structure is formed into the semiconductor substrate. A thin oxide layer is grown upon the trench floor and upon the trench sidewalls, and then a trench dielectric, preferably TEOS deposited using a chemical-vapor deposition CVD process, is deposited into the trench dielectric and upon the semiconductor substrate. The upper surface of the trench dielectric conforms to the underlying contour defined by the shallow trench and the semiconductor substrate. Subsequent device formation requires a substantially planar semiconductor. Conventionally, a combination of masking and etching are used, prior to chemical-mechanical polishing ("CMP"), to aid the planarization process. The extra steps add cost and unnecessary complexity to the process. An alternative planarization process is proposed which uses hydrogen silsequioxane-based flowable oxide ("HSQ"). The HSQ is spin-on deposited upon the conformal trench dielectric in liquid form. After deposition the HSQ is heated which causes it to reflow and produce a substantially planar upper surface. The reflow parameters (such as temperature and time) are chosen so that the HSQ has a polish rate which is approximately equal to the polish rate of the trench dielectric. A chemical-mechanical polish ("CMP") is then used to entirely remove the HSQ layer and a portion of the trench dielectric exterior to the shallow trenches. Since the HSQ is polished at the same rate as the trench dielectric, the upper surface of the trench dielectric after the polish is substantially planar and approximately at the same level as the upper surface of the semiconductor substrate.
摘要:
A method of forming source/drain regions in a semiconductor device is provided. In one illustrative embodiment, the method comprises forming a gate electrode above a semiconducting substrate, forming source/drain regions in the substrate adjacent the gate electrode by performing at least the following steps: performing two ion implantation processes to form source/drain extensions for the device and performing a third ion implantation process to further form source/drain regions for the device. Various N-type and P-type dopant atoms such as arsenic, phosphorous, boron and boron difluoride may be used with the present invention.