JPH03105916A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enable sufficient flow without oxidizing a silicon layer exposed to an opening section by terminating the bonding hands of silicon atoms existing on the surface of the silicon layer or a silicide layer by halogen or a halide and replacing halogen or the halide with nitrogen. CONSTITUTION:An opening section 4 is formed in a PSG film 2 through a dry etching method while using a photo-resist film 3 as a mask. The surface of a silicon substrate 1 exposed into the opening section 4 is treated in hydrogen fluoride gas. The surface of the silicon substrate 1 exposed into the opening section 4 is bonded with fluorine, and an SiFx layer 5 is formed. F dissociates from the surface of the silicon substrate 1 through nitriding treatment at a temperature of 600 deg.C in the plasma of ammonia gas, the surface of the silicon substrate 1, from which F dissociates, easily captures plasma-excited nitrogen, and a silicon nitride film 6 is formed onto the surface of the silicon substrate 1. The PSG film 2 is made to reflow, and the acute upper end section of the opening section is smoothed. The silicon nitride film 6 is removed, and an aluminum film 7 is deposited, thus forming an electrode.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for manufacturing a semiconductor device.

[Conventional technology]

In the conventional manufacturing method of semiconductor devices, the surface of the silicon layer or the surface of the silicide layer is nitrided by nitriding in nitrogen (N2) or ammonia (NH3).
A method of heat treatment at a high temperature of .degree. C. or higher and a method of nitriding with N2 or NH3 gas plasma have been used.

[Problem to be solved by the invention]

In the conventional semiconductor device manufacturing method described above, the method of nitriding the surface of a silicon layer or the surface of a silicide layer involves forming a layer on the surface of a silicon layer or a silicide layer in a hydrofluoric acid (HF) solution before nitriding. This was done after removing the naturally formed silicon oxide film and drying the wafer. However, conventional methods have the disadvantage that it is difficult to avoid the formation of a native oxide film after hydrofluoric acid (HF) treatment, making it extremely difficult to form a uniform and stable silicon nitride film on the surface of the silicon layer. There is.

[Means to solve the problem]

The method for manufacturing a semiconductor device of the present invention includes a step of selectively etching an insulating film provided on a surface of a silicon layer or a silicide layer to form an opening, and a step of forming an opening in the silicon layer or silicide layer exposed in the opening. a step of treating the surface of the silicon layer or silicide layer with a halogen-based compound to terminate the bonds of silicon atoms present on the surface of the silicon layer or silicide layer with a halogen or a halogen compound; and nitriding the surface of the silicon layer or silicide layer. The method includes the step of replacing halogen or a halogen compound on the surface of the silicon layer or silicide layer with nitrogen to form a silicon nitride film on the surface of the silicon layer or silicide layer.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIGS. 1(a) to 1(f) are cross-sectional views of a semiconductor chip shown in order of steps for explaining a first embodiment of the present invention.

As shown in FIG. 1(a), after depositing phosphorus-silicate glass M (hereinafter referred to as PSG film) to a thickness of 0.5 μm on a silicon substrate 1, a positive photoresist film 3 is applied. 1μm×1μ for contact hole formation by photolithography.
Then, using the photoresist film 3 as a mask, the PSG film 2 is removed by dry etching using CF4/H2 gas to form the openings 4.

Next, as shown in FIG. 1(b), the photoresist film 3
is removed, and the surface of the silicon substrate 1 exposed in the opening 4 is treated in hydrogen fluoride (HF) gas at a temperature of 30'C and atmospheric pressure for 30 seconds. At this time, the surface of the silicon substrate 1 exposed in the opening 4 combines with fluorine (F),
A SiFx layer 5 with a thickness of about 0.5 nm is formed.

Next, as shown in Figure 1(c), ammonia (NH3
) Nitriding treatment is performed at a temperature of 600° C. in gas plasma. At a temperature of about 600°C, F dissociates from the surface of the silicon substrate 1, and the surface of the silicon substrate 1 from which F is removed easily captures plasma-excited nitrogen, and 0. A uniform silicon nitride film 6 with a thickness of 5 nm is formed.

Next, as shown in Figure 1(d), H2-0 at 850°C
2, the PSG film 2 is reflowed to smooth the sharp upper end of the opening. At this time, since the surface of the silicon substrate 1 in the opening 4 is protected by the silicon nitride film 6, the PSG
82-02 at 850'C for smoothing membrane 2
It is not oxidized during processing.

Next, as shown in FIG. 1(e), the silicon nitride film 6 is removed by CF4/H2 dry etching.

Next, as shown in FIG. 1(f), an aluminum film 7 is deposited on the surface including the opening 4 by a sputtering method to form an electrode to be connected to the silicon substrate 1.

Here, the bonds of silicon atoms existing on the surface of the silicon substrate 1 in the opening 4 may be terminated with a halogen such as C{ or a halide such as NF2 or BF instead of F. Further, for the nitriding treatment, a thermal excitation method or an optical excitation method may be used instead of the plasma excitation method. Furthermore, a silicide layer may be used instead of the silicon layer.

FIG. 2 is a cross-sectional view of a second embodiment of the invention.

In this embodiment, the present invention is applied to an n-channel MOS transistor having a gate electrode made of a polycrystalline silicon layer and a molybdenum silicide layer.

As shown in FIG. 2, the film thicknesses of the polycrystalline silicon layer 13 and the molybdenum silicide layer 14 forming the gate electrode are 0 and 2, respectively.
It is μm. The gate oxide film 12 of this transistor has a film thickness of 20 nm, and the n+ type diffusion layer 15 for source/train is made by accelerating arsenic ions into a p-type silicon substrate 11 with a resistivity of 1 Ω·cm at an energy of 50 k e V and a dose amount. It is formed by ion implantation at 1×1 ( ) 16 cm −2 .

PS with a thickness of 0.5 μm deposited on the surface including the gate electrode
After providing an opening 16 for contact in one G film, the first
The surface of the molybdenum silicide layer 14 exposed in the bid opening part 16 was
Nitrid at 0 0'C. Next, after nitriding, the film thickness is 1
An aluminum electrode wire 8 of .mu.m is selectively provided and connected to the gate electrode.

Uniform on the side layer surface 1. When an extremely thin silicide nitride film with a thickness of less than nm is formed, this silicide nitride film has high barrier properties and prevents an increase in contact resistance due to silicon precipitation at the contact area between the aluminum electrode wiring and the silicide layer. It's also effective.

〔Effect of the invention〕

As explained above, the present invention terminates the bonds of silicon atoms existing on the surface of a silicon layer or silicide layer with halogen or halide, and then replaces them with nitrogen, thereby converting the natural oxide film into a silicon layer or silicide layer. Since the nitriding process is performed without formation on the surface of the layer, a uniform silicon nitride film or a mixed film of metal nitride and silicon nitride that form silicide can be easily obtained. Therefore, even if the PSG film is smoothed by the H2-02 process in the contact opening, sufficient flow is possible without oxidizing the silicon layer exposed in the opening. Also, Siri

[Brief explanation of drawings]

1(a) to 1(f) are cross-sectional views of a semiconductor chip shown in the order of steps for explaining the first embodiment of the present invention;
The figure is a sectional view of a second embodiment of the invention. 1...Silicon substrate, 2...PSGI1g, 3...
・Photoresist film, 4... Opening part, 5... SiF
x layer, 6... silicon nitride film, 7... aluminum film, 11... P-type silicon substrate, l2... gate oxide film, 13... polycrystalline silicon layer, 14... molybdenum silicide layer, 15... N+ type diffusion layer, 16... Opening portion, 17... Nitrided molybdenum silicide layer, 18...
Aluminum electrode wiring, l9...PSG film.

Claims (1)

[Claims] selectively etching an insulating film provided on the surface of the silicon layer or silicide layer to form an opening, and treating the surface of the silicon layer or silicide layer exposed in the opening with a halogen compound. A step of terminating the bonds of silicon atoms present on the surface of the silicon layer or silicide layer with a halogen or a halogen compound, and nitriding the surface of the silicon layer or silicide layer to remove halogen or halogen on the surface of the silicon layer or silicide layer. A method for manufacturing a semiconductor device, comprising the step of replacing a halogen compound with nitrogen to form a silicon nitride film on the surface of the silicon layer or silicide layer.