Advanced Micro Devices Corporation

Other

Fujitsu Corporation

Kent Kuohua Chang

John JianShi Wang

Yuesong He

David H Chi

Hao Fang

Yue-Song He

Kenneth Wo-Wai Au

Ken Au

Allen U Huang

Fuodoor Gologhlan

Hector Serrato

Lu You

Jiahua Huang

Chin-Yang Sun

Mark S Chang

Effiong Etukudo Ibok

Narbeh Derhacobian

Jayendra D Bhakta

Masaaki Higashitani

Kelwin Ko

Salvatore F Cagnina

Masaatzi Higashitani

R Lee Tan

Wei-Wen Ou

Toru Ishigaki

Maria Chow-Chan

Bill Cox

In a first aspect of the present invention, a method of fabricating a flash memory device is disclosed. The method comprises the steps of providing a portion of a dual gate oxide in a periphery area of the memory device and then simultaneously providing a dual gate oxide in a core area of the memory device and completing the dual gate oxide in the periphery area. Finally, a nitridation process is provided in both the core and periphery areas subsequent to the previous steps. In a second aspect of the present invention, a flash memory device is disclosed. The flash memory device comprises core area having a plurality of memory transistors comprising an oxide layer, a first poly layer, an interpoly dielectric layer, and a second poly layer. The flash memory device further comprises a periphery area having a plurality of transistors comprising an oxide layer, a portion of the first poly layer, and the second poly layer. According to the present invention, the method for fabricating the flash memory device is a simplified process that results in a significant improvement in the oxide reliability in the core and periphery areas and also eliminates the nitrogen contamination problem in the periphery area.

Flash memory device and a method of fabrication thereof

Dopant of an n-type is deposited in the channel area of a p-type well of isolated gate floating gate NMOS transistors forming the memory cells of a memory device array connected in a NAND gate architecture. The dopant is provided by a tilt angle around the existing floating gate/control gate structure at the stage of the fabrication process where the floating gate/control structure is in existence, the field oxidation step may also have occurred, and implantation of the source and drain dopants may also have occurred. This forms a retrograde n-type distribution away from the direction of the surface of the substrate in the channel, which is also concentrated laterally toward the centerline axis of the gate structure and decreases towards the opposing source and drain regions. This deposition promotes buried-channel-like performance of the NMOS transistors connected in series in the NAND gate memory architecture. This reduces series resistance of the series-connected floating gate MOS devices, allowing the desired reduction in source/drain dopant levels in order to combat short channel effects.

Method and apparatus for improved performance of flash memory cell devices

The present invention makes use of ion bombardment to amorphize the source and drain regions of a short channel FET prior to implanting. The source/drain implants are then localized to a shallow depth by appropriate choice of implanting conditions, typically employing rather low bombardment voltages of approximately 10 KeV. Amorphous source/drain regions substantially hinder the diffusion of source/drain dopants and thereby reduce the possibility of punchthrough and loss of FET function. Such devices are preferably used in NAND type flash memory devices maintaining proper self-boosting voltages and FET functions even when short channel lengths are employed.

Method of reducing program disturbs in NAND type flash memory devices

In one embodiment, the present invention relates to a method of cleaning a low pressure chemical vapor deposition apparatus having TEOS material build-up therein involving contacting the low pressure chemical vapor deposition apparatus with a composition containing at least one lower alcohol. In another embodiment, the present invention relates to a system for cleaning a low pressure chemical vapor deposition apparatus having TEOS material build-up therein, containing a supply of a composition comprising at least one lower alcohol; an injection port for introducing the composition including at least one lower alcohol into the low pressure chemical vapor deposition apparatus; and a pump/vacuum system for removing crystallized TEOS material build-up from the low pressure chemical vapor deposition apparatus.

Method of in-situ cleaning for LPCVD TEOS pump

One aspect of the present invention relates to a tetraethylorthosilicate chemical vapor deposition method, involving the steps of forming a film on a substrate using tetraethylorthosilicate in a chemical vapor deposition chamber; and removing tetraethylorthosilicate byproducts from the chemical vapor deposition chamber via a pump system and an exhaust line connected to the chemical vapor deposition chamber, the exhaust line comprising a mesh filter having a conical shape. Another aspect of the present invention relates to an exhaust system for removing tetraethylorthosilicate byproducts from a chemical vapor deposition chamber, containing an exhaust line connected to the chemical vapor deposition chamber, the exhaust line comprising a mesh filter having a conical shape via a pump system; and a pump system connected to the exhaust line for removing tetraethylorthosilicate byproducts from the processing chamber.

Mesh filter design for LPCVD TEOS exhaust system

The present invention provides a method for monitoring for a second gate over etch in a flash memory device. The method includes providing at least one select transistor stack structure in the core area of the substrate and at least one monitor structure in the monitor area of the substrate; determining a thickness of a select gate layer of the at least one monitor structure; and determining if a second gate over etch occurred upon the thickness of the select gate layer of the at least one monitor structure. The select gate layer of the monitor structure is the same select gate layer of the select transistor stack structure. The select gate thickness of the select transistor stack structure may be determined by measuring the thickness at the monitor structure. This measurement is possible at the monitor area because the monitor structures are placed far enough apart to support measuring instruments. With the method in accordance with the present invention, a second gate over etch and its extent can be monitored without destroying the device. The method requires less time than conventional monitoring methods and is also less costly.

Flash memory device with monitor structure for monitoring second gate over-etch

In one embodiment, the present invention relates to a method of forming a flash memory cell, involving the steps of forming a tunnel oxide on a substrate; forming a first polysilicon layer over the tunnel oxide; forming an insulating layer over the first polysilicon layer, the insulating layer comprising a first oxide layer over the first polysilicon layer, a nitride layer over the first oxide layer, and a second oxide layer over the nitride layer; forming a second polysilicon layer over the insulating layer; forming a tungsten silicide layer over the second polysilicon layer by chemical vapor deposition using WF and SiH Cl ; etching at least the first polysilicon layer, the second polysilicon layer, the insulating layer, and the tungsten silicide layer thereby defining at least one stacked gate structure; and forming a source region and a drain region in the substrate, thereby forming at least one memory cell.

Method of forming ono stacked films and DCS tungsten silicide gate to improve polycide gate performance for flash memory devices

In one embodiment, the present invention relates to a method of forming a NAND type flash memory device capable of more than about 1&times;10 program/erase cycles without significant read disturb problems involving the steps of growing a first oxide layer over at least a portion of a substrate, the substrate including a flash memory cell area and a select gate area; removing a portion of the first oxide layer in the flash memory cell area of the substrate; growing a second oxide layer over at least a portion of the substrate in the flash memory cell area and over at least a portion of the a first oxide layer in the select gate area; annealing the first oxide layer and the second oxide layer under an inert gas and at least one of N O and NO for a period of time from about 1 minute to about 15 minutes; depositing a first in situ doped amorphous silicon layer over at least a portion of the second oxide layer; depositing a dielectric layer over at least a portion of the first in situ doped amorphous silicon layer; depositing a second doped amorphous silicon layer over at least a portion of the dielectric layer; and forming a flash memory cell in the flash memory cell area of the substrate and a select gate transistor in the select gate area substrate, the flash memory cell comprising the second oxide layer, the first in situ doped amorphous silicon layer, the dielectric layer, and the second doped amorphous silicon layer, and the select gate transistor comprising the first oxide layer, the second oxide layer, the first in situ doped amorphous silicon layer, the dielectric layer, and the second doped amorphous silicon layer.

Process to improve read disturb for NAND flash memory devices

The present invention provides a method for reducing the gate aspect ratio of a flash memory device. The method includes forming a tunnel oxide layer on a substrate; forming a polysilicon layer on the tunnel oxide layer; forming an insulating layer on the polysilicon layer; forming a control gate layer on the polysilicon layer; etching at least the tunnel oxide layer, the insulating layer, and the control gate layer to form at least two stack structures; forming a plurality of spacers at sides of the at least two stack structures; and filling at least one gap between the at least two stack structures with an oxide, where the control gate layer provides a gate aspect ratio which allows for a maximum step coverage by the oxide. In a preferred embodiment, the method uses nickel silicide instead of the conventional tungsten silicide in the control gate layers of the cells of the device. Nickel silicide has higher conductivity than conventional silicides, thus a thinner layer of nickel silicide may be used without sacrificing performance. Nickel silicide also has a lower barrier height for holes, thus maintaining a low contact resistance. With a thinner nickel silicide layer, the gate aspect ratio of the cells are lowered, allowing for a maximum step coverage by the gap-filling oxide. The reliability of the device is thus improved.

Method for reduced gate aspect ratio to improve gap-fill after spacer etch

A semiconductor process for fabricating NAND type flash memory devices in a first embodiment includes step which can be performed on a production line which manufactures NOR type flash memory products. A NAND flash memory fabrication process according to a second embodiment simplifies the process and uses fewer masks, thus reducing costs and errors to produce higher yields.

High yield performance semiconductor process flow for NAND flash memory products

In one embodiment, the present invention relates to a method of forming a flash memory cell, involving the steps of forming a tunnel oxide on a substrate; forming a first polysilicon layer over the tunnel oxide by chemical vapor deposition using a silicon containing gas and a mixture of a phosphorus containing gas and a carrier gas, the first polysilicon layer having a thickness from about 800 &angst; to about 1,000 &angst;; forming an insulating layer over the first polysilicon layer, the insulating layer comprising a first oxide layer over the first polysilicon layer, a nitride layer over the first oxide layer, and a second oxide layer over the nitride layer; forming a second polysilicon layer over the insulating layer; forming a tungsten silicide layer over the second polysilicon layer by chemical vapor deposition using WF and SiH Cl ; etching at least the first polysilicon layer, the second polysilicon layer, the insulating layer, and the tungsten silicide layer thereby defining at least one stacked gate structure; and forming a source region and a drain region in the substrate, thereby forming at least one memory cell.

Effect of doped amorphous Si thickness on better poly 1 contact resistance performance for nand type flash memory devices

Method for monitoring second gate over-etch in a semiconductor device

In one embodiment, the present invention relates to a method of forming a flash memory cell, involving the steps of forming a tunnel oxide on a substrate; forming a first polysilicon layer over the tunnel oxide; forming an insulating layer over the first polysilicon layer, the insulating layer comprising an oxide layer over the first polysilicon layer, and a tantalum pentoxide layer over the oxide layer, wherein the tantalum pentoxide layer is made by chemical vapor deposition at a temperature from about 200&deg; C. to about 650&deg; C. using an organic tantalum compound and an oxygen compound, and heating in an N,O atmosphere at a temperature from about 700&deg; C. to about 875&deg; C.; forming a second polysilicon layer over the insulating layer; etching at least the first polysilicon layer, the second polysilicon layer and the insulating layer, thereby defining at least one stacked gate structure; and forming a source region and a drain region in the substrate, thereby forming at least one memory cell.

Method of forming high K tantalum pentoxide Ta2O5 instead of ONO stacked films to increase coupling ratio and improve reliability for flash memory devices

Method for reduced gate aspect ration to improve gap-fill after spacer etch

In one embodiment, the present invention relates to a method of forming a NAND type flash memory device involving the steps of growing a first oxide layer over at least a portion of a substrate, the substrate including a flash memory cell area and a select gate area; removing a portion of the first oxide layer in the flash memory cell area of the substrate; growing a second oxide layer over at least a portion of the substrate in the flash memory cell area and over at least a portion of the a first oxide layer in the select gate area; annealing the first oxide layer and the second oxide layer under an inert gas and at least one of N,O and NO for a period of time from about 1 minute to about 15 minutes; depositing a first in situ doped amorphous silicon layer over at least a portion of the second oxide layer, the first in situ doped amorphous silicon layer having a thickness from about 400 &angst; to about 1,000 &angst;; depositing a dielectric layer over at least a portion of the first in situ doped amorphous silicon layer; depositing a second doped amorphous silicon layer over at least a portion of the dielectric layer; and forming a flash memory cell in the flash memory cell area of the substrate and a select gate transistor in the select gate area substrate, the flash memory cell comprising the second oxide layer, the first in situ doped amorphous silicon layer, the dielectric layer, and the second doped amorphous silicon layer, and the select gate transistor comprising the first oxide layer, the second oxide layer, the first in situ doped amorphous silicon layer, the dielectric layer, and the second doped amorphous silicon layer.

Growing community of inventors

Cupertino, CA, United States of America

Kent Kuohua Chang