KR100292052B1 - Method for manufacturing semiconductor device - Google Patents

Abstract

PURPOSE: A fabrication method of a semiconductor device is provided to prevent a damage of a silicon substrate due to a decreasing of a thickness of a gate oxide layer according to an increasing of an integration degree of the semiconductor device. CONSTITUTION: A gate insulating layer(23) is formed on a substrate(21) of a first conductive type. A conductive layer is formed on the gate insulating layer. A gate(24) composed of the remaining conductive layer is formed by removing any portion of the conductive layer to expose the gate insulating layer. A remaining material of the conductive layer is oxidized by performing an oxidizing process on an entire surface. An active region is formed on the substrate of a lower end portion of the gate.

Description

Manufacturing Method of Semiconductor Device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to a morse of a semiconductor device, which minimizes damage to a surface of a silicon substrate during an overetch for forming a gate according to a trend of decreasing thickness of a gate oxide film of a semiconductor device. A method of manufacturing a field effect transistor (MOSFET).

Semiconductor devices have been scaled down in submicron units as a result of efforts to reduce the size of MOSFETs constituting integrated circuits in order to obtain good circuit operation performance and integration. Therefore, the gate line width becomes narrow in a single MOSFET which is a component of an integrated circuit. As a result, the gate resistance of the gate is increased not only, but also the thickness of the gate oxide film becomes thinner.

As a result, an overetch is performed to remove the remaining polysilicon in the etched portion of the gate forming polysilicon layer in order to pattern the gate, so that the thickness of the thin gate oxide film adversely affects the reliability of the device.

1A to 1D are manufacturing process diagrams of a semiconductor device according to the prior art.

Referring to FIG. 1A, a field oxide film 2 is formed on a predetermined portion of a surface of a silicon substrate 1, which is a semiconductor substrate 1, by a selective oxidation method such as LOCOS (Local Oxidation of Silicon) to form an active region and a field of a device. Define the area. In the above, a field oxide film 2 defining an active region and a field region of the device may be formed in the semiconductor substrate 1 by filling trenches and filling silicon oxide.

The surface of the semiconductor substrate 1 is thermally oxidized to form a gate oxide film 3.

Referring to FIG. 1B, a polycrystalline silicon layer 4 doped with impurities at high concentration on the field oxide film 2 and the gate oxide film 3 is deposited by chemical vapor deposition (hereinafter, referred to as CVD). do.

Next, after the photoresist is applied to the surface of the polysilicon layer 4, a photoresist is performed to define a photoresist pattern 10 that protects only a portion where the gate is to be formed.

Referring to FIG. 1C, the gate 4 is patterned by performing an etching process using the photoresist pattern 10 as an etching mask to remove the polysilicon layer 4 in a portion not protected by the photoresist pattern. . At this time, etching is performed until the surface of the gate oxide film 3 is exposed. However, when the gate 4 is patterned, the over-etching is performed to prevent the polysilicon layer except for the gate 4 from remaining.

Referring to FIG. 1D, the gate oxide film is also etched together so that the gate oxide film 30 is non-uniformly remaining on the surface of the substrate 1 because the transient etching is performed to completely remove the remaining polysilicon as described above.

Although not shown thereafter, a source / drain is formed in the lower substrate on the side surface of the gate through ion implantation using a gate 4 to form a MOS type transistor.

However, in the method of manufacturing the semiconductor device according to the related art described above, when the gate is formed by etching the polysilicon layer, an active region of the transistor may be formed at the time of the transient etching to completely exclude the possibility of remaining of the polysilicon at a portion except the gate. There is a problem that the gate oxide film of the portion is etched to damage the silicon surface of the silicon substrate.

Accordingly, an object of the present invention is to provide a gate forming method for preventing damage to the surface of a silicon substrate due to a decrease in the thickness of the gate oxide film due to the high integration of the semiconductor during gate patterning for manufacturing a transistor during a semiconductor device manufacturing process.

A semiconductor device manufacturing method according to the present invention for achieving the above object is a step of forming a gate insulating film on a first conductive semiconductor substrate, a step of forming a conductive layer on the gate insulating film, and a predetermined portion of the conductive layer Forming a gate formed of the remaining conductive layer, performing an oxidation process on the entire surface of the substrate, and forming an active region on the substrate at the lower end of the gate side surface.

1A to 1D are manufacturing process diagrams of a semiconductor device according to the prior art.

2A to 2D are manufacturing process diagrams of a semiconductor device according to the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

2A through 2D are diagrams illustrating a process of manufacturing a semiconductor device according to an embodiment of the present invention.

Referring to FIG. 2A, a field oxide film 22 is formed on a predetermined portion of a surface of a silicon substrate 21, which is a semiconductor substrate 21, by a selective oxidation method such as LOCOS (Local Oxidation of Silicon) to form an active region and a field of a device. Define the area. In the above description, the field oxide film 22 defining the active region and the field region of the device may be formed in the semiconductor substrate 21 by filling trenches and filling silicon oxide.

The surface of the semiconductor substrate 21 is thermally oxidized to form a gate oxide film 23.

Referring to FIG. 2B, a polycrystalline silicon layer 24 doped with a high concentration of impurities on the field oxide film 22 and the gate oxide film 23 is deposited by chemical vapor deposition (hereinafter, referred to as CVD). do.

Next, a photoresist is applied to the surface of the polysilicon layer 24 and then a photolithography process is performed to define the photoresist pattern 20 that protects only the portion where the gate is to be formed.

Referring to FIG. 2C, the gate 24 is patterned by performing an etching process using the photoresist pattern 20 as an etching mask to remove the polysilicon layer 24 in a portion not protected by the photoresist pattern. . At this time, etching is performed until the surface of the gate oxide layer 23 is exposed. However, when the gate 24 is patterned, the polysilicon layer except for the gate 24 remains, so that the remaining polysilicon layer 240 remains on the gate oxide layer 23.

Therefore, the present invention does not perform the excessive etching to remove this, so the surface of the silicon substrate 21 is not damaged by the gate oxide film (23).

Referring to FIG. 2D, in order to completely remove the residual polysilicon layer (240 in FIG. 2C), a thermal oxidation process is performed on the residual polysilicon layer 240 instead of the conventional transient etching method, so that the remaining polysilicon layer 240 is completely removed. By oxidizing, a new oxide film 234 composed of the original gate oxide film and the oxidized residual polysilicon layer is formed on the surface of the active region of the substrate.

Thereafter, although not shown, the photoresist pattern 20 is removed, followed by ion implantation using a gate 24 to form a source / drain in the lower side substrate of the gate to form a MOS type transistor.

Accordingly, the present invention provides an advantage of preventing damage to the surface of the silicon substrate due to the reduction of the gate oxide film thickness due to the high integration of the semiconductor during gate patterning for manufacturing transistors of the semiconductor device.

Claims (5)

Forming a gate insulating film on a first conductive semiconductor substrate, forming a conductive layer on the gate insulating film, and removing a predetermined portion of the conductive layer so that the surface of the gate insulating film is exposed. Forming a gate formed of a layer, and oxidizing the residue of the conductive layer remaining on the gate insulating film exposed in addition to the remaining conductive layer forming the gate by performing an oxidation process on the entire surface of the substrate; And forming an active region on the substrate at the lower end portion of the gate side surface. The method of claim 1, wherein the conductive layer is formed of polycrystalline silicon doped with impurities. The method of claim 1, wherein the gate insulating film is formed of silicon oxide. The method of claim 1, wherein the gate is formed by a photolithography process using a photoresist. The method of claim 4, wherein the photolithography process is performed until the surface of the gate insulating film is exposed.