JPS6197975A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent high-melting point films from being diffused in the gate insulating films and to contrive to improve the gate withstand voltage by a method wherein, after a high-melting point metal film is deposited on the whole surface of the substrate using the gate electrode as the high-melting point metal silicide film, the high-melting point metal films on the side walls of the gate electrode are removed. CONSTITUTION:A gate oxide film 28 is formed, and after that, oxygen ions are implanted in the whole surface of the substrate. Subsequently, a heat treatment is performed in an atmosphere of oxygen, a molybdenum silicide film 29 is formed and an oxide film 30 is formed on the periphery thereof. After this, phosphorus ions are implanted through the silicon oxide film 30, and a source 31 and a drain 32 are formed. Subsequently, an oxide film 33 is made to remain on the sidewalls only of the molybdenum silicide pattern 29 using an anisotropic etching method. Then, a molybdenum film 34 is deposited on the whole surface. Then, unreacted molybdenum films on the sidewalls of the molybdenum silicide pattern and those on field oxide films 22 are removed using a reactive ion etching method, and molybdenum silicide patterns 35 and molybdenum silicide films 36 are respectively separated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a semiconductor, and more particularly to a method of manufacturing a semiconductor device having an electrode made of silicide, a high melting point metal.

In a conventional MO8 semiconductor device, a gate electrode and a source,
In order to lower the resistance of the drain region, high-melting point metal silicides have come to be used. In this case, in order to maintain the characteristics of the gate electrode, polycrystalline silicon is laid down as the base of the molybdenum silicide layer, and the gate electrode is formed with a 2M structure of molybdenum silicide layer and polycrystalline silicon. The molybdenum inside penetrates through the polycrystalline silicon layer and diffuses into the gate oxide film, which has the disadvantage of causing deterioration of gate breakdown voltage.

Purpose An object of the present invention is to provide an LDD structure that can prevent diffusion of metal into the gate insulating film and improve the gate withstand voltage, and in which the source, drain electrode, and gate electrode are provided with a high-melting point metal using a simple process. An object of the present invention is to provide a method for manufacturing a semiconductor device.

Structure An MO8 type semiconductor device which is an embodiment of the present invention will be described below with reference to FIGS. 1(a) to 1(h).

First, a field oxide film 22 was formed on the surface of a P-type silicon substrate 21 by selective oxidation, and then a thermal oxide film 23 with a thickness of 400 mm was formed on the surface of the element region surrounded by this field oxide film 22.

Next, a polycrystalline silicon film 24 with a thickness of 3000 μm is deposited.
Furthermore, a layer with a thickness of 2 is deposited on the polycrystalline silicon film 24 by sputtering.
1,000 molybdenum films 25 were deposited (FIG. 1a).

Next, using a photoresist pattern (not shown) as a mask, these molybdenum films 25. and polycrystalline silicon film 2
4 was subjected to reactive ion etching to form a molybdenum film pattern 26 and a polycrystalline silicon pattern 27.

Next, using these patterns as a mask, NH containing HF is
The thermal oxide film 23 was etched using a 4F solution to form a gate oxide film 28 (first time).

After this, oxygen ions were applied to the entire surface of the substrate at 30 K e V 1.
0"CXl implant. In the first round, oxygen ions were implanted over the field region, source and drain regions,
Also, from above the molybdenum film 25, the polycrystalline silicon film 24
It was injected so that it was injected inside.

In this case, the peak dose of oxygen ion implantation is
Inject near the interface between polycrystalline silicon and molybdenum. Note that it is preferable that the polycrystalline silicon contains oxygen uniformly throughout. Next, in the second time, oxygen ions.

Only the side walls of the molybdenum film and polycrystalline silicon film were implanted. In addition, oxygen ions may be implanted into the entire surface of the substrate and the side walls of the gate electrode at the same time (Fig. 1C). Subsequently, heat treatment is performed in an oxygen atmosphere at 800°C to cause the molybdenum and polycrystalline silicon to react, thereby forming molybdenum. Silicide 29 was formed. Through this heat treatment, an oxide film 30 was formed on the source and drain regions and around the molybdenum silicide.

After that, this molybdenum silicide film 29 is used as a mask, and phosphorus is applied at a dose of lX101LEI! , an acceleration energy of 25 K e V was implanted into the substrate in the source and drain regions through the silicon oxide film 30 to form a source 31 and a drain 32 (FIG. 1d).

Next, using anisotropic etching, the top surface of the source and drain and the top surface of the molybdenum silicide were etched to expose the surface, and the oxide film 33 was left only on the sidewalls of the molybdenum silicide pattern (Fig. 1e). .

Next, a molybdenum film 3.1 with a thickness of 500 mm was deposited on the entire surface. Using the pattern of this molybdenum film 34 as a mask, arsenic was applied to the source and drain regions at a dose of 5X.
The implantation was carried out at 10"cxl and an acceleration energy of 60KeV. Subsequently, heat treatment was performed for 30 minutes in a nitrogen atmosphere at 600°C to cause reactions between molybdenum and single crystal silicon and between molybdenum and molybdenum silicide. hand,
Molybdenum silicide to serve as source and drain electrodes was formed on the surfaces of the source and drain regions 31 and 32, and a molybdenum silicide film with a high molybdenum content was formed on the molybdenum silicide 29 (FIG. 1f).

Next, the side walls of the molybdenum silicide and the unreacted molybdenum film on the field oxide film 22 were removed using reactive ion etching to separate the molybdenum silicide pattern 35 and the molybdenum silicide 36 (
Figure 1g).

Subsequently, a CVD oxide film 37 was deposited on the entire surface, a contact hole 38 was opened, and an AJ film was further deposited on the entire surface, followed by patterning to form an A1 wiring 39, thereby producing an MO3 type semiconductor device.

In the embodiments described above, high melting point metals such as tungsten, titanium, tantalum, etc., or their silicides can be used instead of molybdenum silicide.

Further, in order to lower the resistance value of polycrystalline silicon, phosphorus may be doped before or after oxygen ion implantation, or in advance.

Effect The upper part of the molybdenum silicide deposited in the step shown in Figure 2 f has a high molybdenum content, but oxygen ions have been implanted into the polycrystalline silicon and molybdenum film in advance, and the distribution of oxygen content is Since it spreads around the interface between crystalline silicon and molybdenum, it can prevent molybdenum metal from entering the gate oxide film even if the molybdenum content is high, and it also prevents the formation of an oxide film on the sidewalls of molybdenum silicide. The gate electrode can be easily separated from the source and drain electrodes, and the thickness of the oxide film on the sidewalls can be made thicker through subsequent heat treatment, making the LD more effective.
A D structure can be formed. Furthermore, since an oxide film is formed on the source and drain in the oxygen ion implantation process, impurities can be implanted for the source and drain using this. Moreover, these effects can be obtained in the same process.

[Brief explanation of the drawing]

FIGS. 1(a) to 1(h) are cross-sectional views showing a method of manufacturing an MO3 type semiconductor device using refractory metal silicide in one embodiment of the present invention. 21 - Substrate 24 - Polycrystalline silicon film 25. 34 - Molybdenum film 29 - Molybdenum silicide gate electrode 3o - Oxide film 31. 32 - Source, train

Claims (3)

[Claims] (1) A gate electrode is formed with a laminated structure of a polycrystalline silicon film and a high melting point metal, oxygen ions are implanted into the entire surface of the gate electrode, the gate electrode is made into a high melting point metal silicide by heat treatment, and then the substrate is 1. A method of manufacturing a semiconductor device, characterized in that after depositing a high melting point metal on the entire surface, the high melting point metal on the side walls of the gate electrode is removed. (2) Manufacture of the semiconductor device according to claim 1, wherein the oxygen ion implantation is performed so that the peak dose thereof is at the interface between the polycrystalline silicon film and the high melting point metal. Method. (3) the oxygen ion implantation is performed at least twice;
2. The method of manufacturing a semiconductor device according to claim 1, wherein at least one of the steps is performed on a side wall of a gate electrode.