JPS62173763A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To improve the controllability of the width of a gate side wall residue and to prevent a source and a drain from being etched by forming a nitride film of an etch stopper on the surface of a silicon. CONSTITUTION:A gate oxide film 2 and a gate electrode 20 made of a polycrystalline silicon 3 are formed on a P-type silicon substrate 1. Then, with the electrode 20 as a mask P ions are implanted to form a low density N-type region 4. Then, a nitride film 11 is deposited by an LPCVD on the entire surface as an etch stopper. An oxide film 12 is further deposited thereon. The film 12 is anisotropically etched by RIE. Then, the film 11 is removed, with the electrode 20 and a gate side wall residue 13 of width L as masks As ions are implanted to form a high density N-type region 5, thereby obtaining an LDD structure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of manufacturing a semiconductor device, particularly a method of manufacturing a lightly doped drain.
ain :hereinafter referred to as LDD) structure insulated gate (M
(OS) relates to a method of manufacturing a field effect semiconductor device.

[Conventional technology]

FIGS. 2(a) to 2(c) are cross-sectional views showing the main stages of a conventional method for manufacturing a semiconductor device of this type. First, as shown in FIG. 2(a), a P-type silicon base F
A gate insulating film 2 and a gate electrode 3 are formed on i1, and using this gate electrode 3 as a mask, a low concentration of n is formed at a low acceleration voltage.
By ion-implanting a type impurity (N), low concentration n-type regions 4 for the source and drain are formed. Next, Figure 2(b)
As shown in , low pressure CV D (Loh Pressu
re Chemical Vapor Deposit
An oxide film 9 is deposited using LPCVD (hereinafter referred to as LPCVD). Furthermore, as shown in FIG. 2(C), RIE (
Reactive Ion Etching) The gate side wall is etched by anisotropic etching.
), the oxide film 10 is removed, leaving only the oxide film 10. Then, using the gate electrode 3 and the remaining gate sidewalls 10 as masks, high concentration n-type impurity (IT) is ion-implanted to form the high concentration n-type region 5. Form. In this way, an LDD structure is formed.

[Problem that the invention seeks to solve]

In the conventional LDD structure, since the oxide film 10 is used on the gate sidewall, it is difficult to detect the end point of anisotropic etching using RIE, and the width of the remaining gate sidewall 10 is insufficiently controllable. There was a possibility that the drain could be etched.

The present invention has been made to eliminate the above-mentioned drawbacks of the conventional method, and an object of the present invention is to provide a method for manufacturing a semiconductor device that can easily improve the controllability of the width of the remaining portion of the gate sidewall.

[Means for solving problems]

In the method for manufacturing a semiconductor device according to the present invention, after ion implantation is performed using a gate electrode as a mask, a nitride film is formed as an etch stopper on the silicon surface, an oxide film is deposited on top of the nitride film, and this is subjected to RIE anisotropic The oxide film is left on the side walls of the gate by etching.

[Effect]

In the present invention, since a nitride film is formed as an etch stopper on the silicon surface and an oxide film is formed thereon, the end point of RIE anisotropic etching of the oxide film can be detected.

,〔Example〕 Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1(a) to fd+ show a method for manufacturing a semiconductor device according to an embodiment of the present invention in the order of steps, and in the figures,
The same reference numerals as in FIG. 2 indicate the same or equivalent parts, 20 is a gate electrode made of a gate insulating film (oxide film) 2 and polycrystalline silicon 3, 11 is a low concentration n-type region 4 of the source/drain.
12 is an oxide film formed on the nitride 15!11, and 13 is an oxide film 12 formed on the silicon surface by RIE anisotropic etching to remove only the gate sidewalls. This is the remaining part of the gate side wall.

Next, the manufacturing method of this example will be explained step by step.

As shown in FIG. 1(a), a gate oxide film 2 and a gate electrode 20 made of polycrystalline silicon 3 are formed on a P-type silicon substrate 1 (first step). Next, the gate electrode 20
Using as a mask, 1×10 6 ions of, for example, PCI) are implanted at an acceleration voltage of 35 KeV to form a low concentration n-type region 4 (second step).

Next, as shown in FIG. 1(b), a nitride film 11 is deposited by 300 people on the entire surface by LPGVD, and this is made into 7 layers (third step). Furthermore, the nitride film 13 is
An oxide film 12 is deposited thereon (fourth step). and the first
As shown in FIG. (fifth step).

Next, as shown in FIG. 1+d), the etch stopper nitride film 11 is removed, and As (II) is deposited at 50Ke using the gate electrode 20 and the remaining gate sidewall 13 as a mask.
By implanting 4×10 4 ions at an acceleration voltage of V to form a heavily doped n-type region 5, an LDD structure is obtained (sixth step). Contact window opening and electrode wiring process (not shown)
By performing these steps, the device is completed.

In this example, after ion implantation using the gate electrode 20 as a mask, the nitride film 11 is formed on the silicon surface, the oxide film 12 is formed on the nitride film 11, and the oxide film 12 is implanted while monitoring the light emission. Since the RIE anisotropic etching of the film 12 is performed, it is possible to detect the end point of the RIE anisotropic etching, and as a result, it is possible to improve the controllability of 1t of the gate sidewall remaining portion 13, and to improve the etching of the source and drain. It can be prevented.

〔Effect of the invention〕

As described above, according to the method of manufacturing a semiconductor device according to the present invention, since the nitride film of the etch stopper is formed on the silicon surface, it is possible to improve the controllability of the width of the gate sidewall remaining portion 13 and to improve the width of the source and drain. It has the effect of preventing etching.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a method of manufacturing a semiconductor device according to an embodiment of the present invention in order of steps, and FIG. 2 is a diagram showing a method of manufacturing a conventional semiconductor device in order of steps. DESCRIPTION OF SYMBOLS 1... Semiconductor (P-type silicon) substrate, 2... Gate insulating film, 20... Gate electrode, 4... Low concentration (source/drain n-type) region, 5... High concentration n type area, 1
1... Nitride film, 12... Oxide film, 13... Gate side wall remainder. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) In a method for manufacturing a field effect semiconductor device, a first step of forming a gate insulating film and a gate electrode made of polycrystalline silicon on a silicon substrate, and using this electrode as a mask, attaching a conductive material different from that of the silicon substrate to the silicon substrate. The second step of forming the source/drain by ion-implanting type impurities, the third step of forming a nitride film on the entire surface, and the fourth step of forming an oxide film on the nitride film are different. a fifth step of leaving the oxide film only on the gate sidewalls and removing the other oxide films by directional etching; and ion-implanting impurities of a conductivity type different from that of the silicon substrate using the gate electrode and the rest of the gate sidewalls as a mask. a sixth step of forming the high concentration impurity regions of the source and drain.