Vanguard International Semiconductor Corporation

Ming-Hong Kuo

Fu-Liang Yang

Wei-Ray Lin

Ing-Ruey Liaw

Erik S Jeng

Chung-Ju Lee

Shye-Lin Wu

Hsi-Chuan Chen

Janmye Sung

Bi-Ling Chen

Rong-Wu Chien

Yu-Chun Ho

Hsu-Li Cheng

Jan Mye Sung

Meow-Ru Hsu

A method for forming planarized isolation using a nitride hard mask and two CMP steps is described. A first nitride layer is deposited over a pad oxide layer on the surface of a semiconductor substrate. The first nitride and pad oxide layers are etched through where they are not covered by a mask to provide at least one wide opening and at least one narrow opening where the surface of the substrate is exposed. Trenches are etched into the substrate where it is exposed. An oxide layer is deposited overlying the first nitride layer and within the trenches completely filling the narrow trench wherein a trough is formed over the wide trench. A second nitride layer is deposited over the oxide layer. The second nitride layer is polished away with a polish stop at the oxide layer whereby the second nitride layer is removed except: where it lies within the trough. The oxide layer is etched back where it is not covered by the second nitride layer wherein the oxide layer is planarized except where the oxide layer underlies the second nitride layer. The second nitride layer is removed within the trough whereby oxide horns forming the trough extend vertically upward from the planarized oxide surface. Thereafter, the oxide layer is polished away with a polish stop at the first nitride layer whereby the oxide horns are removed. The first nitride and the pad oxide layers are removed completing formation of the shallow trench isolation.

Method to solve the dishing issue in CMP planarization by using a nitride hard mask for local inverse etchback and CMP

A process for fabricating a DRAM capacitor structure, in which the capacitor upper plate structure is defined during the formation of bit line contact hole opening, and substrate contact hole opening procedure, eliminating the need for a specific upper plate, photolithographic masking procedure, has been developed. The process features isolating a polysilicon upper plate structure, during an isotropic RIE cycle, also creating an undercut polysilicon region, in the contact holes, which are opened simultaneously during the upper plate definition. Subsequent silicon nitride spacers, on the sides of the contact holes, provides insulation between the polysilicon upper plate structure, and bit line, and substrate contact plug structures, now located in the contact holes. The undercut polysilicon regions, allow the formation of thicker silicon nitride spacers, to be formed in this undercut region.

Method of fabricating a capacitor under bit line DRAM structure using contact hole liners

A method for implementing shallow trench isolation by using a non-critical chemical mechanical polishing method in an integrated circuit. After STI regions are etched and insulator oxide layer is deposited and etched back, a planarized insulator oxide layer is formed. The corners of silicon nitride layer over active area are exposed after the etch back step. Then, a silicon nitride cap layer is deposited. A non-critical photoresist patterning is used to expose the bigger active regions. Afterward, the cap layer on the bigger active regions is removed. Thereafter, a non-critical CMP process is used to polish the cap layer on the smaller active regions, then the insulator oxide layer under cap layer is removed by wet etch. Subsequently, a wet etch is used to remove the cap layer and silicon nitride layer. Finally, the shallow trench isolation process is completed after the pad oxide is removed.

Shallow trench isolator via non-critical chemical mechanical polishing

A process for fabricating a DRAM cell has been developed, in which two interlaced patterns, each comprised of capacitor node contact holes and bit line contact holes, are independently created, each using a specific photolithographic mask, and a specific photolithographic procedure. The two interlaced patterns allow the creation of the capacitor node contact images, and the bit line contact holes images, to be formed in a thin polysilicon layer, with minimum spacing between contact images. Capacitor node contact holes, as well as bit line contact holes, are than formed in an insulator layer, via a dry etching procedure, using the patterned thin polysilicon layer as a mask. The use of specific masks, or of the interlaced pattern, allows the minimum spacing, between a capacitor node contact hole, and a bit line contact hole, to be limited only by the overlay between photolithographic masks.

Design and a novel process for formation of DRAM bit line and capacitor

A method for forming planarized isolation by combining LOCOS and STI isolation processes is described. A first nitride layer is deposited over a pad oxide layer on the surface of a semiconductor substrate. The first nitride layer and pad oxide layer are etched through where they are not covered by a mask to provide openings where the surface of the semiconductor substrate is exposed wherein there is at least one wide opening and one narrow opening. A second nitride layer is deposited over the substrate and etched back to leave spacers on the sidewalls of the openings wherein the narrow opening is filled by the spacers. The exposed semiconductor substrate within the wide opening is oxidized wherein a field oxide region is formed within the wide opening. A portion of the first nitride layer and spacers is etched away whereby the semiconductor substrate within the narrow opening is exposed. A trench is etched into the semiconductor substrate where it is exposed within the narrow opening. An oxide layer is deposited overlying the first nitride layer and field oxide region and filling the trench wherein the oxide layer filling the trench forms a shallow trench isolation region. The oxide layer is polished away with a polish stop at the first nitride layer. The first nitride layer, the spacers, and the pad oxide layer are removed, completing formation of both a field oxide region and a shallow trench isolation region in the fabrication of an integrated circuit device.

Method to fabricate isolation by combining locos and shallow trench

A silicon dioxide layer and a silicon nitride layer are formed on the wafer. Subsequently, a plurality of shallow trenches are generated in the wafer. A HDP-CVD oxide having protruding portions is refilled into the trenches and formed on the silicon nitride layer for isolation. A wet etch is performed to etch the HDP-CVD oxide layer such that the corners of the silicon nitride layer formed on the active area will be exposed. A cap silicon nitride layer is then conformally formed on the surface of the oxide layer. Then, a chemical mechanical polishing (CMP) process is used to remove the top of the cap silicon nitride layer, thereby exposing the residual protruding portions of the oxide layer. The residual protruding portions of the oxide layer are next removed. Then, the silicon nitride layer and the cap silicon nitride layer are both removed by conventional methods. Finally, the pad oxide is removed.

Method of making a shallow trench isolation for ULSI formation via

A process for forming a damascene landing pad structure, used to connect a bit line structure, of a semiconductor memory device, to an underlying source and drain region, of a transfer gate transistor, has been developed. The process features the formation of a dual shaped, landing pad opening in an insulator layer, comprised of a first shaped opening, exposing an underlying source and drain region, and an enlarged, second shape opening, exposing non-active device regions. Polysilicon deposition and patterning result in the formation of the damascene landing pad structure, in the dual shaped, landing pad opening. Insulator deposition is followed by the opening of a bit line via hole, exposing the top surface of the damascene landing pad structure, in a region in which the damascene landing pad structure overlays a non-active device region. This is followed by the formation of the bit line structure, contacting the top surface of the damascene landing pad structure, exposed in the bit line via hole.

Method for fabricating a damascene landing pad

An improved local oxidation of silicon (LOCOS) method with recessed silicon substrate and double polysilicon/silicon nitride spacer is disclosed. The present invention includes forming a pad oxide layer on a semiconductor substrate and then forming a first silicon nitride layer on the pad oxide layer. An active region is defined by patterning and etching the pad oxide layer and the first silicon nitride layer using a photoresist mask. Thereafter, a silicon oxide layer and a second silicon nitride layer is formed. Next, a polysilicon layer is deposited over the second silicon nitride layer. The polysilicon layer, the second silicon nitride layer, and the silicon oxide layer are etched back to form a double polysilicon/silicon nitride spacer. Finally, an isolation region in the substrate is formed.

Locos method with double polysilicon/silicon nitride spacer

The invention provides a method of forming field oxide regions between active regions in a semiconductor substrate. The invention forms nitride feet on the sidewalls of a nitride oxidation mask to prevent formation of the bird's beak on the field oxide and reduce stress in the active areas. The invention begins by forming a first oxide layer and a masking block, over the active regions. A second nitride layer is deposited over the masking block and the substrate surface. The second nitride layer is anisotropically etched with a customized etch forming nitride spacers on the sidewalls of the masking block, and nitride spacer feet on the surface of the first oxide layer. The customized etch of the invention optimizes the microloading effects to properly form the nitride feet. The substrate is oxidized, using the masking block nitride spacers and the nitride spacer feet as an oxidation mask to form field oxide regions. The nitride feet eliminate bird's beak problem. In another embodiment, a trench is formed in the substrate and the trench is oxidized to form a field oxide region which is level with the substrate surface. Lastly, the masking block, the nitride spacer, and nitride spacer feet are removed.

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Ping-Tung, Taiwan

Ming-Hong Kuo