KR20050071803A - Method of inhibiting degradation of gate oxide - Google Patents

Abstract

The present invention relates to a method for preventing deterioration of a transistor gate oxide film due to a high density plasma. According to the process of the present invention, an interlayer insulating film, which is essentially used for insulating other wirings after the formation of a gate electrode, is used for a high density plasma (HDP) method. By performing a low pressure chemical vapor deposition (LPCVD) process before or after the formation, the oxide film is also formed on the lower substrate of the semiconductor device, thereby effectively preventing the transistor gate oxide film from deteriorating.

Description

Method of inhibiting degradation of gate oxide

The present invention relates to a method for preventing the deterioration of a transistor gate oxide film due to a high density plasma (hereinafter, referred to as "HDP"), and more particularly, to insulate other wirings after the gate electrode is formed. A transistor gate is formed by performing a low pressure chemical vapor deposition process (hereinafter abbreviated as "LPCVD") before or after forming the interlayer insulating film to be used by the HDP method. The present invention relates to a method capable of effectively preventing deterioration of an oxide film.

The HDP process has a high plasma power, which inevitably generates ultraviolet (UV) light. UV basically has a specific wavelength range, which is known to range from about 200 to 800 nm. According to the Plank's Law on the wavelength of light and the amount of energy retained, the energy retained (E) is proportional to the frequency (E = hν; h = Frank's constant, ν = frequency of light). At this time, since the frequency ν is inversely proportional to the wavelength, E becomes larger as the wavelength of light becomes shorter. Therefore, UV having a wavelength of 200 to 800 nm has an energy of about 5 eV to 1.5 eV. When such energy reaches the silicon substrate, an electron-hole pair is formed, which is a general phenomenon that occurs when a larger energy is injected since the band-gap energy of silicon is 1.1 eV. to be. The formed electrons are trapped again on the gate oxide layer, thereby deteriorating the characteristics of the oxide layer.

The prior art provides a special way to control such plasma induced damage (HDP) or plasma induced radiation damage (hereinafter referred to as "PIRD") of HDP. Nonetheless, a method of reducing the power of the plasma has been used to suppress the use of HDP or to reduce the PID, but this has a problem of causing short circuits in subsequent processes by reducing the uniform deposition ability which is an advantage of using HDP.

Recently, a method of depositing an amorphous silicon thin film after forming a transistor to prevent the PID or PIRD from deteriorating the gate oxide film has been devised. However, this method has also been used to form a contact for interconnection in a subsequent process. There is a problem in that it cannot be formed by the etching process and there is a possibility that a short circuit between wirings due to the amorphous silicon thin film may occur.

It is an object of the present invention to provide a method for preventing degradation of a transistor gate oxide film by HDP.

In order to achieve the above object, in the present invention, an oxide film is formed on a lower portion of a substrate of a semiconductor device by performing an LPCVD process before or after forming an interlayer insulating film, which is essentially used for insulating other wirings after the formation of a gate electrode, by the HDP method. The present invention provides a method that can effectively prevent deterioration of the transistor gate oxide film.

Hereinafter, the present invention will be described in detail.

According to the present invention, a gate electrode is formed on a substrate of a semiconductor device, and an oxide film by low pressure chemical vapor deposition (LPCVD) is formed before or after forming an interlayer insulating film by high density plasma (HDP) over the entire gate electrode. It provides a method for manufacturing a semiconductor device comprising the step of.

The LPCVD process is carried out at a temperature of 50 ~ 1000 ℃, when the LPCVD process is deposited an oxide film on the silicon substrate below, that is, the back.

In the case where the LPCVD process is performed before HDP oxide film formation, the method of the present invention comprises a first step of forming a gate electrode on a substrate of a semiconductor device, and a method of forming an oxide film by LPCVD on the upper and lower substrates of the gate electrode. And a third step of forming an HDP oxide film on the LPCVD oxide film formed on the gate electrode.

In addition, when the LPCVD process is performed after the formation of the HDP oxide film, the method of the present invention comprises the steps of forming a gate electrode on the substrate of the semiconductor device, and forming a HDP oxide film on the gate electrode; And forming an oxide film by LPCVD on the HDP oxide film and the lower substrate.

Meanwhile, the method may further include depositing a nitride film or a polycrystalline silicon film on the LPCVD oxide film formed below the substrate so that the LPCVD oxide film formed below the substrate may not be removed in a subsequent process such as wet etching or wet cleaning.

Figure 1 schematically shows an example of such a method of the present invention.

First, a plurality of gate electrodes 12 in which silicides such as polysilicon and tungsten silicide are stacked are formed on a substrate 10 on which various elements for forming a semiconductor device are formed. Next, a gate oxide film (not shown) is formed at the contact interface between the substrate 10 and the gate electrode 12, and a hard mask for preventing the loss of the gate due to subsequent self-aligned etching or the like on the gate electrode 12. The insulating film 14 is formed.

Subsequently, a spacer (not shown) such as a nitride film is formed on the sidewall of the gate electrode 12, and then an LPCVD process is performed. An LPCVD oxide film 18 is formed not only on the substrate and the gate electrode but also on the bottom of the substrate by the LPCVD process. .

Next, the oxide film 16 is deposited by HDP.

LPCVD is a process of depositing an oxide film on the back surface of a silicon substrate, unlike other processes for depositing an oxide film, for example, plasma enhanced chemical vapor deposition (PECVD) or atmospheric pressure chemical vapor deposition (APCVD). Since the oxide film on the back of the substrate deposited by the LPCVD method is located between the metal chuck mounting the substrate and the back of the substrate in the HDP process, the effect of lowering the power applied between the source of the plasma and the support is generated. This lowering of the power increases the wavelength of the generated UV, which reduces the energy of the UV, thus generating only less energy than the silicon bandgap, so that even if UV is injected into the silicon substrate, it cannot form a pair of electrons and voids. It does not deteriorate the characteristics of the oxide film.

As described above, in the present invention, the degradation of the gate oxide film due to PID does not occur even at a very high antenna ratio, so that the yield can be improved in the integrated circuit manufacturing process, and also HCD (Hot Carrier Degradation) due to the degradation of the gate oxide film The deterioration of reliability such as) can also be prevented.

1 is a schematic diagram showing the principle of the present invention.

<Description of the symbols for the main parts of the drawings>

10 semiconductor substrate 12 gate electrode

14 hard mask insulating film 16 HDP oxide film

18: LPCVD oxide film 20: metal support of HDP process

Claims (5)

Forming a gate electrode on the substrate of the semiconductor device; And forming an oxide film by low pressure chemical vapor deposition (LPCVD) before or after the interlayer insulating film is formed by high density plasma (HDP) over the entire gate electrode. The method of claim 1, LPCVD process is carried out at a temperature of 50 ~ 1000 ℃, the method of manufacturing a semiconductor device, characterized in that the process of depositing an oxide film on the lower substrate. The method of claim 1 wherein the method is A first step of forming a gate electrode on a substrate of the semiconductor device, Forming an oxide film by LPCVD on the gate electrode and the lower substrate; And forming a HDP oxide layer on the LPCVD oxide layer formed on the gate electrode. The method of claim 1 wherein the method is A first step of forming a gate electrode on a substrate of the semiconductor device, Forming an HDP oxide layer on the gate electrode; And forming an oxide film by LPCVD on the HDP oxide film and the lower substrate. The method according to claim 3 or 4, And depositing a nitride film or a polycrystalline silicon film on the LPCVD oxide film formed under the substrate.