Texas Instruments Corporation

Puneet Kohli

Manoj Mehrotra

Manfred Ramin

Sameer Kumar Ajmera

Jin Zhao

Theodore Warren Houston

Mark Stephen Rodder

Amitava Chatterjee

Amitabh Jain

Antonio L P Rotondaro

Rick L Wise

Shaoping Tang

Song Zhao

Craig Henry Huffman

Nandakumar Mahalingam

An integrated circuit having an SRAM cell includes a pair of cross-coupled inverters with first driver and load transistors connected to provide a first storage node and second driver and load transistors connected to provide a second storage node. The SRAM cell also includes first and second pass gate transistors controlled by at least one word line and respectively connected between a first bit line and the first storage node and a second bit line and the second storage node; wherein a first driver transistor threshold voltage is different than a second driver transistor threshold voltage and one of the first and second driver threshold voltages is different than a pass gate transistor threshold voltage. Alternately, a threshold voltage of the first and second driver transistors is different than a symmetrical pass gate transistor threshold voltage. Additionally, methods of manufacturing an integrated circuit having an SRAM cell are provided.

SRAM cell parameter optimization

Complementary MOS (CMOS) integrated circuits include MOS transistors, resistors and bipolar transistors formed on a common substrate. An emitter region of a bipolar transistor is implanted with a first dopant in an implantation process that implants source/drain regions of an MOS transistor, and is also implanted with a second dopant of same conductivity type in another implantation process that implants a body region of a resistor. The first and second dopants may optionally be the same dopant. The source/drain regions are implanted with the resistor body region covered by a first patterned mask; and the resistor body region is implanted with the MOS transistor source/drain regions covered by a second patterned mask. The implantations of the MOS transistor source/drain regions and of the resistor body region the source/drain regions can occur in any order, with the emitter region implanted during both implantations.

Bipolar transistors with resistors

An integrated circuit (IC) includes at least one NMOS transistor, wherein the NMOS transistor includes a substrate having a semiconductor surface, and a gate stack formed in or on the surface including a gate electrode on a gate dielectric, wherein a channel region is located in the semiconductor surface below the gate dielectric. A source and a drain region are on opposing sides of the gate stack. An In region having a retrograde profile is under at least a portion of the channel region. The retrograde profile includes (i) a surface In concentration at a semiconductor surface interface with the gate dielectric of less than 5&#xd7;10cm, (ii) a peak In concentration at least 20 nm from the semiconductor surface below the gate dielectric, and wherein (iii) the peak In concentration is at least two (2) orders of magnitude higher than the In concentration at the semiconductor surface interface. A method to form an IC including at least one NMOS transistor includes implanting a first In implant at a first energy and a second In implant at a second energy, wherein the first In implant together with the second In implant form an In region having a retrograde profile under at least a portion of the channel region, and wherein the second energy is at least 5 keV more than the first energy.

Multiple indium implant methods and devices and integrated circuits therefrom

Semiconductor doping techniques, along with related methods and structures, are disclosed that produce components having a more tightly controlled source and drain extension region dopant profiles without significantly inducing gate edge diode leakage. The technique follows the discovery that carbon, which may be used as a diffusion suppressant for dopants such as boron, may produce a gate edge diode leakage if present in significant quantities in the source and drain extension regions. As an alternative to placing carbon in the source and drain extension regions, carbon may be placed in the source and drain regions, and the thermal anneal used to activate the dopant may be relied upon to diffuse a small concentration of the carbon into the source and drain extension regions, thereby suppressing dopant diffusion in these regions without significantly inducing gate edge diode leakage. The increased concentration of carbon in the source and drain regions may permit heavier doping of the source/drain region, leading to improved gate capacitance.

Semiconductor doping with reduced gate edge diode leakage

A process of fabricating an IC is disclosed in which a polysilicon resistor and a gate region of an MOS transistor are implanted concurrently. The concurrent implantation may be used to reduce steps in the fabrication sequence of the IC. The concurrent implantation may also be used to provide another species of transistor in the IC with enhanced performance. Narrow PMOS transistor gates may be implanted concurrently with p-type polysilicon resistors to increase on-state drive current. PMOS transistor gates over thick gate dielectrics may be implanted concurrently with p-type polysilicon resistors to reduce gate depletion. NMOS transistor gates may be implanted concurrently with n-type polysilicon resistors to reduce gate depletion, and may be implanted concurrently with p-type polysilicon resistors to provide high threshold NMOS transistors in the IC.

Use of poly resistor implant to dope poly gates

A simple and cost effective method of forming a fully silicided (FUSI) gate of a MOS transistor is disclosed. In one example, the method comprises forming a nitride hardmask overlying a polysilicon gate, forming an S/D silicide in source/drain regions of the transistor, oxidizing a portion of the S/D silicide to form an oxide barrier overlying the S/D silicide in the source/drain regions, removing the nitride hardmask from the polysilicon gate, and forming a gate silicide such as by deposition of a gate silicide metal over the polysilicon gate and the oxide barrier in the source/drain regions to form a fully silicided (FUSI) gate in the transistor. Thus, the oxide barrier protects the source/drain regions from additional silicide formation by the gate silicide metal formed thereafter. The method may further comprise selectively removing the oxide barrier in the source/drain regions after forming the fully silicided (FUSI) gate.

Formation of fully silicided gate with oxide barrier on the source/drain silicide regions

Pipe defects in n-type lightly doped drain (NLDD) regions and n-type source/drain (NDS) regions are associated with arsenic implants, while excess diffusion in NLDD and NSD regions is mainly due to phosphorus interstitial movement. Carbon implantation is commonly used to reduce phosphorus diffusion in the NLDD, but contributes to gated diode leakage (GDL). In high threshold NMOS transistors GDL is commonly a dominant off-state leakage mechanism. This invention provides a method of forming an NMOS transistor in which no carbon is implanted into the NLDD, and the NSD is formed by a pre-amorphizing implant (PAI), a phosphorus implant and a carbon species implant. Use of carbon in the NDS allows a higher concentration of phosphorus, resulting in reduced series resistance and reduced pipe defects. An NMOS transistor with less than 1&#xb7;10cmarsenic in the NSD and a high threshold NMOS transistor formed with the inventive method are also disclosed.

High threshold NMOS source-drain formation with As, P and C to reduce damage

There is presented a method of forming a semiconductor device. The method comprises forming gate structures including forming gate electrodes over a semiconductor substrate and forming spacers adjacent the gate electrodes. Source/drains are formed adjacent the gate structures, and a laminated stress layer is formed over the gate structure and the semiconductor substrate. The formation of the laminated stress layer includes cycling a deposition process to form a first stress layer over the gate structures and the semiconductor substrate and at least a second stress layer over the first stress layer. After the laminated layer is formed, it is subjected to an anneal process conducted at a temperature of about 900&#xb0; C. or greater.

Semiconductor device manufactured using a laminated stress layer

In one aspect, the invention provides a method of fabricating a semiconductive devicethat comprises forming a raised layer [] adjacent a gate [] and over a source/drain [], depositing a silicidation layer [] over the gate [] and the raised layer [], and moving at least a portion of the silicidation layer [] into the source/drain [] through the raised layer [

Semiconductive device fabricated using a raised layer to silicide the gate

The invention relates to a method of forming a shallow junction. The method () comprises forming source/drain extension regions with a non-amorphizing tail implant () which is annealed conventionally (spike/RTP) and amorphizing implant which is re-grown epitaxially (SPER) (). The non-amorphizing tail implant is generally annealed () before a doped amorphous layer for SPE is formed (). SPE provides a high active dopant concentration in a shallow layer. The non-amorphizing tail implant () expands the source/drain extension region beyond the range dictated by the SPE-formed layer and keeps the depletion region of the P-N junction away from where end-of-range defects form during the SPE process. Thus, the SPE-formed layer primarily determines the conductivity of the junction while the tail implant determines the location of the depletion region. End-of-range defects form, but are not in a position to cause significant reverse bias leakage.

Highly conductive shallow junction formation

The invention provides a method for manufacturing a semiconductor device. The method for manufacturing the semiconductor device, among others, may include forming one or more layers of material within an opening in a substrate, the opening and the one or more layers forming at least a portion of an isolation structure, and subjecting at least one of the one or more layers to an energy beam treatment, the energy beam treatment configured to change a stress of the one or more layers subjected thereto, and thus change a stress in the substrate.

Method for manufacturing an isolation structure using an energy beam treatment

The present invention provides a method for manufacturing a semiconductor device. The method for manufacturing the semiconductor device, among other steps, may include forming a gate structure over a substrate, forming at least a portion of gate sidewall spacers proximate sidewalls of the gate structure, and subjecting the at least a portion of the gate sidewall spacers to an energy beam treatment, the energy beam treatment configured to change a stress of the at least a portion of the gate sidewall spacers, and thus change a stress in the substrate therebelow.

Method for manufacturing a gate sidewall spacer using an energy beam treatment

In one aspect, the present invention provides a method of forming junctions in a silicon-germanium layer (). In this particular embodiment, the method comprises implanting a dopant () into the silicon-germanium layer () and implanting fluorine () into the silicon-germanium layer ().

Growing community of inventors

Austin, TX, United States of America

Puneet Kohli