Advanced Micro Devices Corporation

Globalfoundries Inc.

Falk Graetsch

Karsten Wieczorek

Sven Beyer

Berthold Reimer

Lutz Herrmann

Richard Carter

Martin Trentzsch

Gunter Grasshoff

Stephan Kruegel

Robert Binder

Boris Bayha

Fabian Koehler

Katy Schabernack

Stephan Krügel

In sophisticated semiconductor devices, the encapsulation of sensitive gate materials, such as a high-k dielectric material and a metal-containing electrode material, which are provided in an early manufacturing stage may be achieved by forming an undercut gate configuration. To this end, a wet chemical etch sequence is applied after the basic patterning of the gate layer stack, wherein at least ozone-based and hydrofluoric acid-based process steps are performed in an alternating manner, thereby achieving a substantially self-limiting removal behavior.

Superior integrity of a high-K gate stack by forming a controlled undercut on the basis of a wet chemistry

Sophisticated gate electrode structures for N-channel transistors and P-channel transistors are patterned on the basis of substantially the same configuration while, nevertheless, the work function adjustment may be accomplished in an early manufacturing stage. For this purpose, diffusion layer and cap layer materials are removed after incorporating the desired work function metal species into the high-k dielectric material and subsequently a common gate layer stack is deposited and subsequently patterned.

Uniform high-k metal gate stacks by adjusting threshold voltage for sophisticated transistors by diffusing a metal species prior to gate patterning

A gate electrode structure may be formed on the basis of a silicon nitride cap material in combination with a very thin yet uniform silicon oxide based etch stop material, which may be formed on the basis of a chemically driven oxidation process. Due to the reduced thickness, a pronounced material erosion, for instance, during a wet chemical cleaning process after gate patterning, may be avoided, thereby not unduly affecting the further processing, for instance with respect to forming an embedded strain-inducing semiconductor alloy, while nevertheless providing the desired etch stop capabilities during removing the silicon nitride cap material.

Enhanced etch stop capability during patterning of silicon nitride including layer stacks by providing a chemically formed oxide layer during semiconductor processing

Encapsulation of a gate stack comprising a high-k dielectric material may be accomplished on the basis of a silicon nitride material that is deposited in a sequence of two deposition processes, in which the first process may be performed on the basis of a moderately low process temperature, thereby passivating sensitive surfaces without unduly contaminating the same, while, in a second deposition process, a moderately high process temperature may be used to provide enhanced material characteristics and a reduced overall cycle time compared to conventional ALD or multi-layer deposition techniques.

Method for encapsulating a high-K gate stack by forming a liner at two different process temperatures

A method for forming a reliable and ultra-thin oxide layer, such as a gate oxide layer of an MOS transistor, comprises an annealing step immediately performed prior to oxidizing a substrate. The annealing step is performed in an inert gas ambient to avoid oxidation of the semiconductor surface prior to achieving a required low oxidizing temperature. Preferably, the annealing step and the oxidizing step are carried out as an in situ process, thereby minimizing the thermal budget of the overall process.

Method of forming a thin oxide layer having improved reliability on a semiconductor surface

A highly localized diffusion barrier is incorporated into a polysilicon line to allow the doping of the polysilicon layer without sacrificing an underlying material layer. The diffusion barrier is formed by depositing a thin polysilicon layer and exposing the layer to a nitrogen-containing plasma ambient. Thereafter, the deposition is resumed to obtain the required final thickness. Moreover, a polysilicon line is disclosed, having a highly localized barrier layer.

Methods for producing a highly doped electrode for a field effect transistor

A method of forming a dielectric layer that may be used as a dielectric separating a gate electrode from a channel region of a field effect transistor is provided which allows a high capacitive coupling while still maintaining a low leakage current level. This is achieved by introducing a dopant, for example nitrogen, that increases the resistance of the dielectric layer by means of low energy plasma irradiation, wherein an initial layer thickness is selected to substantially avoid penetration of the dopant into the underlying material. Subsequently, dielectric material is removed by an atomic layer etch to finally obtain the required design thickness.

Method of forming a low leakage dielectric layer providing an increased capacitive coupling

For aggressively scaled field effect transistors, nitrogen is incorporated into a base oxide layer, wherein, at an initial phase of a plasma nitridation process, the nitrogen ion density is maintained at a value so that incorporation of nitrogen into the channel region is minimized. Subsequently, when the thickness of the base oxide layer has increased, due to residual oxygen in the plasma ambient, the nitrogen ion density is increased, thereby increasing the nitridation rate. Preferably, the nitrogen ion density is controlled by varying the pressure of the plasma ambient. Moreover, a system is disclosed that allows control of the nitridation rate in response to an oxide layer thickness.

Technique for forming an oxide/nitride layer stack by controlling the nitrogen ion concentration in a nitridation plasma

A method of forming oxide layers of different thickness on a substrate is described, wherein the oxide layers preferably serve as gate insulation layers of field effect transistors. The method allows to form very thin, high quality oxide layers with a reduced number of masking steps compared to the conventional processing, wherein the thickness difference can be maintained within a range of some tenths of a nanometer. The method substantially eliminates any high temperature oxidations and is also compatible with most chemical vapor deposition techniques used for gate dielectric deposition in sophisticated semiconductor devices.

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Dresden, Germany

Falk Graetsch