摘要:
The present invention provides a process for fabricating a floating gate of a flash memory. First, an isolation region is formed in a semiconductor substrate and the isolation region has a height higher than the substrate. A gate oxide layer and a first polysilicon layer are then formed. The first polysilicon layer is formed according to the contour of the isolation region to form a recess in the first polysilicon layer. A sacrificial insulator is filled into the recess. The first polysilicon layer is then selectively removed in a self-aligned manner using the sacrificial insulator as a hard mask to expose the isolation region. A polysilicon spacer is formed on the sidewalls of the first polysilicon layer. A first mask layer is formed on the isolation region, the sacrificial insulator in the recess is removed, and a floating gate region is defined. Then, the surfaces of the first polysilicon layer and polysilicon spacer in the floating gate region are oxidized to form a polysilicon oxide layer. Finally, the polysilicon oxide layer is used as a mask to pattern the underlying first polysilicon layer and polysilicon spacer in a self-aligned manner to form a floating gate. During the oxidation process, the polysilicon spacer of the present invention serves as a buffer layer, which is oxidized and protects the floating gate from being oxidized. Thus, the floating gate and STI overlay, and current leakage caused by insufficient overlay is prevented.
摘要:
A floating gate and fabrication method thereof. A semiconductor substrate is provided, on which an oxide layer, a first conducting layer, and a patterned hard mask layer having an opening are sequentially formed. A spacer is formed on the sidewall of the opening. A second conducting layer is formed on the hard mask layer. The second conducting layer is planarized to expose the surface of the patterned hard mask layer. The surface of the second conducting layer is oxidized to form an oxide layer. The patterned hard mask layer and the oxide layer and the first conducting layer underlying the patterned hard mask layer are removed.
摘要:
A floating gate and fabrication method thereof. A semiconductor substrate is provided, on which an oxide layer, a first conducting layer, and a patterned hard mask layer having an opening are sequentially formed. A spacer is formed on the sidewall of the opening. A second conducting layer is formed on the hard mask layer. The second conducting layer is planarized to expose the surface of the patterned hard mask layer. The surface of the second conducting layer is oxidized to form an oxide layer. The patterned hard mask layer and the oxide layer and the first conducting layer underlying the patterned hard mask layer are removed.
摘要:
A method for manufacturing a split-gate flash memory cell, comprising the steps of forming an active region on a semiconductor substrate; forming a buffer layer on the semiconductor substrate; forming a first dielectric layer on the buffer layer; removing part of the first dielectric layer; defining an opening; removing the buffer layer within the opening; forming a gate insulating layer and floating gates; forming a source region in the semiconductor substrate; depositing a conformal second dielectric layer on the opening; removing the buffer layer outside the first dielectric layer and the floating gates; and forming an oxide layer and control gates.
摘要:
A method for fabricating a memory unit with T-shaped gate. A semiconductor substrate forming a dielectric layer, a first opening, and a second opening is provided in a CMOS process. A silicate glass spacer is formed on the sidewall of the first opening and is thermally oxidized to form a light doped area under the silicate glass spacer. The silicate glass spacer is removed. An insulating spacer is formed on the sidewall of the first opening. A first spacer is formed on a sidewall of the second opening. N-type conducting spacers are formed respectively on sidewalls of the insulating spacer and the first spacer. Gate dielectric layers are formed respectively in the first opening and the second opening. A P-type conducting layer fills with the first opening and the second opening, and a second spacer is formed on a sidewall of a conducting spacer of the second opening.
摘要:
A method for fabricating a split gate flash memory cell. First, a substrate having a doped region covered by a first conductive layer is provided. A floating gate and a first insulating layer are successively formed over the substrate on both sides of the first conductive layer. Thereafter, a conformable second insulating layer and a conformable second conductive layer are successively formed on the substrate and the first insulating layer, and then a third insulating layer is formed thereon. The third insulating layer and the second conductive layer are successively etched back to expose the second insulating layer. The third insulating layer is removed using a cap layer formed on the second conductive layer as a mask to form an opening. Finally, the second conductive layer under the opening is removed to form a control gate underlying the cap layer.
摘要:
A method for fabricating a source line of a flash memory cell. First, a substrate covered by a first insulating layer, a first conductive layer, and a second insulating layer successively is provided. Next, the second insulating layer is patterned to form an opening over the substrate and expose the first conductive layer. Next, a first spacer is formed over the sidewall of the lower opening and a second spacer is formed over the sidewall of the upper opening and the first spacer to make the opening has a “T” profile. Next, the exposed first conductive layer under the opening is removed, and a third spacer over the sidewall of the first spacer and the second spacer is formed. Finally, a source region is formed in the substrate under the opening and the opening is filled with a second conductive layer to form a source line.
摘要:
A method for fabricating a floating gate with multiple tips. A semiconductor substrate is provided, on which an insulating layer and a patterned hard mask layer are sequentially formed. The patterned hard mask layer has an opening to expose the surface of the semiconductor substrate. A conducting layer is conformally formed on the patterned hard mask layer, and the opening is filled with the conducting layer. The conducting layer is planarized to expose the surface of the patterned hard mask layer. The conducting layer is thermally oxidized to form an oxide layer, and the patterned hard mask layer is removed.
摘要:
A stacked gate flash memory device and method of fabricating the same. A cell of the stacked gate flash memory device in accordance with the invention is disposed in a cell trench within a substrate and source and drain regions are formed in the same substrate side of the adjacent isolation trenches. Thus, the stacked gate flash memory device of the invention can achieve high integration of memory cells.
摘要:
The present invention provides a process for fabricating a self-aligned split gate flash memory. First, a patterned gate oxide layer, a first patterned polysilicon layer, and a first patterned mask layer are successively formed on a semiconductor substrate, and a first insulating spacer is formed on their sidewalls. Then, shallow trench isolation (STI) is formed in the substrate using the first patterned mask layer and the first insulating spacer as a mask. Then, the first patterned mask layer and a part of the first insulating spacer are removed to expose the first patterned polysilicon layer. A floating gate region is defined on the first patterned polysilicon layer, and the surface of the first polysilicon layer in the floating gate region is selectively oxidized to form polysilicon oxide layer. Then, the polysilicon oxide layer is used as a mask to remove the underlying first polysilicon layer in a self-aligned manner to form a floating gate. Finally, an intergate insulating layer and a second patterned polysilicon layer as a control gate are succesively formed on the polysilicon oxide layer. The present invention forms a floating gate in a self-aligned manner, which can decreases critical dimension. When an oxidation process is conducted to form the above polysilicon oxide layer, the nitride liner layer and the insulating spacer formed in the trench protect the sides of floating gate from oxygen invasion. This prevents the line width of floating gate from size reduction. Current leakage is also be avoided.