JPH02268441A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent a transistor from deteriorating and improve the reliability by etching sidewall insulating films and a conductive layer thereunder simultaneously to form sidewalls incorporating the conductive layer under the insulating films. CONSTITUTION:A gate oxide film 2 is adhered on to a semiconductor substrate 1 and polycrystalline silicon is adhered to form a gate electrode 3. A silicon- oxide film is adhered and silicon oxide and a conductive film thereunder are etched by full-face etching to form sidewall insulating films 6. An impurity is implanted and heat treatment is performed to form thick impurity diffusion layers 8, a layer insulating film 9 is adhered, contact windows are made, and then aluminum wirings 10 are formed to complete a transistor. Thereby hot carriers are not captured by the films 6, the effect of the hot carriers captured by the film 2 on the transistor characteristic decreases, the transistor slightly deteriorates, and the reliability improves.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a semiconductor device, and particularly to a method for forming a highly reliable semiconductor element.

(Prior art) In recent years, with the increasing integration and miniaturization of semiconductor devices, L D
Transistors having a D (Lightly Doped Drain) structure are widely used. There is a phenomenon (hot carrier phenomenon) that exceeds the electronic band gap energy and collides with the silicon (Si) lattice to generate electron-hole pairs, which are captured by the gate oxide film and deteriorate transistor characteristics. Hot carriers are generated by a high electric field, so maintaining the same power supply voltage will cause problems in miniaturized transistors. Therefore, in order to alleviate the high electric field, an LDD structure is developed in which a low concentration impurity region is placed near the drain where the electric field is highest. It becomes necessary.

FIG. 2 shows the manufacturing process of a conventional semiconductor device. In FIG. 2, 1 is a semiconductor substrate, 2 is a gate oxide film, 3 is a gate electrode, 4 is an impurity ion (Po), 5 is a thin impurity diffusion layer (n-), 6 is a sidewall insulating film,
6' is a silicon oxide film, 7 is an impurity ion (As''), 8 is a dense impurity diffusion layer (n9), 9 is an insulating film between the eyebrows, and 10 is an aluminum wiring.

Next, the conventional manufacturing process will be explained. In FIG. 2(a), a gate oxide film 2 is deposited on a semiconductor substrate (p type) 1 and a gate t443 is formed. Next, impurity ions 4 of, for example, Pl are implanted using an ion implantation method. A thin impurity diffusion layer 5 is formed.

Thereafter, as shown in FIG. 2(b), a silicon oxide film of about 2,500 layers is deposited on the entire surface.Next, as shown in FIG. 2(e), the entire surface is etched by anisotropic dry etching to remove the side surfaces. A wall insulating film 6 is formed. Next, as shown in FIG. 2(d), impurity ions 7 such as As+ ions are implanted by an ion implantation method, and heat treatment is performed in a nitrogen atmosphere to form a dense impurity diffusion layer 8. Next, an interlayer insulating film 9 is deposited by a vapor phase epitaxy (CVD) method, a contact window is opened using a resist pattern, and an aluminum wiring 10 is formed and completed (FIG. 2(e)).
).

(Problem M to be solved by the invention) However, in the conventional manufacturing method described above, hot carriers generated near the drain are captured in the insulating film forming the sidewall, and the device cannot be used for a long time. However, there is a fnR problem in that transistor characteristics such as threshold voltage fluctuation are degraded.

The present invention solves these conventional problems,
It is an object of the present invention to provide a method for manufacturing a highly reliable semiconductor device.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a method for manufacturing a semiconductor device that includes a step of performing etching halfway when forming a gate electrode using a resist pattern, and a step of performing sidewall insulation. When forming the film, the sidewall insulating film and the conductive layer below the sidewall insulating film are etched at the same time to form a sidewall having a structure including the conductive layer below the sidewall insulating film.

(Function) Therefore, in the semiconductor device manufactured by the manufacturing method of the present invention, pot carriers are not captured in the sidewall insulating film, and since the conductive layer in the sidewall portion is connected to the gate electrode, the conductive layer is connected to the gate electrode. The effect of pot carriers trapped in the silicon oxide film on transistor characteristics is also eliminated.

(Embodiment) FIG. 1 shows a semiconductor manufacturing process in an embodiment of the present invention. In Figure 1, 1 is a semiconductor substrate (p-type silicon), 2 is a gate oxide film, 3 is a metal electrode, 4 is an impurity ion (Pl), and 5 is a thin impurity diffusion layer (n-).
, 6 is a sidewall insulating film, 7 is an impurity ion (As
''), 8 is a dense impurity diffusion layer (n''), 9 is an interlayer insulating film, and 10 is an aluminum wiring.

Next, the manufacturing process will be explained. In FIG. 1(a), a gate oxide film 2 is deposited on a semiconductor substrate (P type) 1,
Further, approximately 4,000 layers of polycrystalline silicon 3 are deposited, and a photoresist pattern is etched by dry etching using SF and gas until approximately 500 layers of polycrystalline silicon 6 remain, thereby forming a gate electrode. Furthermore, P
+ ions and other impurity ions 4 to 2.0XIO">-"
In order to form a thin impurity diffusion layer 5, approximately 2,500 silicon oxide films 6' are deposited as shown in FIG. 1(b). Furthermore, Figure 1 (c
) As shown in FIG. ), impurity ions such as As” ions are added to 5.OXlo
The dense impurity diffusion layer 8 is implanted by ion implantation method to the extent of lfm-'' and heat-treated at 900°C for 30 minutes in a nitrogen atmosphere.
form. Next, as shown in FIG. 1(a), an interlayer insulating film 9 is deposited, a contact window is opened using a resist pattern, and an aluminum wiring 10 is formed to complete the process.

In this embodiment, the conductive layer under the sidewall insulating film is made of polycrystalline silicon, but silicide or other conductive film may also be used.

(Effects of the Invention) As is clear from the above embodiments, the present invention is characterized in that hot carriers are not captured in the sidewall insulating film, and that the polycrystalline silicon layer under the sidewall is connected to the gate electrode. 8 For example, in the conventional example, when the gate voltage is 5V and the drain voltage is 5V, the transistor threshold voltage will decrease within a few years to 10 years. While the variation is about 10%, in the example it is only a few percent, which improves the deterioration of transistor characteristics during long-term use and solves the reliability problem.

[Brief explanation of drawings]

FIG. 1 is a process diagram of a method for manufacturing a semiconductor device according to an embodiment of the present invention, and FIG. 2 is a process diagram of a conventional method for manufacturing a semiconductor device. 1... Semiconductor substrate, 2... Gate oxide film, 3
...gate electrode, 4 ...impurity ion, 5.
... Thin impurity diffusion layer, 6 ... Sidewall insulating film, 7 ... Impurity ion. 8...Dense impurity diffusion layer, 9...Interlayer insulating film, 10...Aluminum metal layer. Figure Figure Figure

Claims (1)

[Claims] a step of depositing a gate oxide film on a semiconductor substrate; a step of depositing a conductive film on the gate oxide film; a step of etching the conductive film halfway using a photoresist as a mask; and a step of etching the conductive film halfway using the conductive film as a mask. a step of implanting impurity ions onto the semiconductor substrate; a step of depositing an insulating film on the conductive film; and a step of etching the gate oxide film and the insulating film to leave them along sidewalls of the conductive film. ,
A method for manufacturing a semiconductor device, comprising the step of implanting impurity ions onto the semiconductor substrate using the conductive film and the insulating film as masks.