JPH02283061A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To make the outside of a nitride film equal in size to the inside of a channel stopper and to miniaturize it while maintaining the pressure resistance of the stopper by forming any of an SiO2 and Al on the nitride film, and ion implanting with it as a mask to form the stopper. CONSTITUTION:With an SiO2 film 32 as an ion stopping film and a resist 17 as masks boron is ion implanted by a CVD method, and a N-MOS channel stopper 18 for preventing inversion to a nonactive region is formed in a P-well 13. Similarly, a P-MOS channel stopper is formed. In order to form the channel stopper 33, the resist 17 is first peeled. In order to peel it, the film 32 of SiO2 remains as it is without removing it. Thereafter, it is coated with an organic resist 19, the nonactive region of a silicon substrate 10 remains by a lithography by using a mask, the resist 19 except it is removed, phosphorous ions are implanted to form the stopper 33.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method of manufacturing a semiconductor device having a semiconductor element on a silicon substrate, and particularly to a method of manufacturing a semiconductor device suitable for microfabrication.

<Prior Art> FIG. 2 is a process diagram showing an outline of the steps of a conventional semiconductor device manufacturing method, which is the basis of the improvement of the present invention. This process diagram is based on a CMOS transistor.

Using an n-type silicon substrate 10, an oxide film 11 is first formed on the silicon substrate 10 by thermal oxidation (FIG. 2(a)). Next, a P-type well is formed by lithography using a first mask. An opening 12 is formed by removing the oxide film in that portion (FIG. 2(b)).

Oxidation Jg! Boron (B+), which is a p-type impurity, is ion-implanted through the opening 12 using II as a mask (Fig. 2(c)).
) After this, boron is diffused into the silicon substrate 10 by heat treatment at a high temperature for a long time to form a p-type well 13 (FIG. 2(d)).

Next, after removing the thick oxide film 11, the thin oxide film 11 is removed.
4 is formed, and a nitride film 15 is further formed on it by C1) (Ch
chemical vapor deposition
) method (Fig. 2(e)).Furthermore, by phosphorography using a second mask, the nitride film 15 in the part that will become the active region is left, and the nitride film in other parts is removed (Fig. 2(e)). (f
)) In this case, an organic resist 16 used in this lithography is attached on top of the nitride film 15.

Next, the process moves to the step of forming an N-MOS channel stopper shown in FIG. 2(g). In this step, an organic resist 17 is applied over these, and by lithography using a third mask, the inactive region of the p-type well 13 is left and the other portions of the resist 17 are removed. After this, resist 16.
Using 17 as a mask, boron (B+) ions are implanted to form a channel stopper 18 in the p-type well 13 to prevent inversion to an inactive region.

In FIG. 2 (h>), a P-MOS channel stopper is formed in the same way. To form this channel stopper, the resist 17 is once removed, an organic resist 19 is applied again, and phosphorography is performed using a fourth mask. In this step, the resist 19 is removed from the rest of the silicon substrate 10 while leaving the non-active region.In this case, the resist 16 is also removed.
Since resists 7 and 7 are both organic resists, when resist 17 is removed, resist 16 is also removed.

Since the nitride Jl 115 and the oxide film 14 are too thin to function as a mask for phosphorus (P+) ion implantation for forming a channel stopper, a resist 20 is applied again on the nitride film 15, but in this case, the nitride film 14 is The coating is applied with a width slightly larger than the width of the film 15. On the other hand, channel stopper 2
1 requires a certain width to ensure crucible pressure, so
The size of the opening of the fourth mask is set large in advance by the margin of the resist 20.

Next, a thick oxide film 22 connected to the oxide film 14 is formed in the field (inactive) region by thermal oxidation (see FIG.
i)).

In the gate oxidation step shown in FIG. 2(j), after the oxide film 14, nitride film 15, etc. in the gate portion are once removed, a new thin gate oxide film 23 is formed.

After this, as shown in FIG. 2(k), in a polysilicon film forming step, polysilicon 24 is deposited on the oxide Jl 122 and the gate oxide film 23, and a gate electrode 25 is formed using a fifth mask ( Figure 2 <1> After this, Figure 2 (m)
As shown in FIG. 2, the resist 26 is opened at a predetermined location using the fifth mask, and phosphorus (P+) is injected through the gate oxide film 23.
Ions are implanted into the active region of the p-type well 13 to form a source 27 and a drain 28, forming a ρ-MO3 portion.

Similarly, for the n-MO3 portion, as shown in FIG. 2(n), the resist 29 is opened at a predetermined location using the sixth mask, and boron (B+) ions are applied to the silicon substrate through the gate oxide film 23. A source 30 and a drain 31 are formed by injecting 11 into the 10 active regions.

Thereafter, a C-MOS (C-MOS) transistor is formed by completing various steps such as forming an insulating film between eyebrows, contact holes, aluminum thin film deposition, electrode wiring pattern, protective film, and pad opening.

<Problem to be solved by the invention> However, in such a conventional manufacturing process, as shown in Fig. 2 (
In the steps from g) to (h), when the resist 17 is removed, the resist 16 is also removed at the same time, so
It becomes necessary to apply the resist 20 again, but in this case, the resist 20 needs to be formed larger than the nitride film 15 with some margin. For this reason, the channel T to the brim 21 has to be moved to the outside, resulting in a large size, which poses a problem in that it becomes an obstacle to miniaturization.

Means for Solving the Problems> In order to solve the above problems, the present invention forms a well on a silicon substrate, covers these with a first oxide film and a nitride film, and further covers the nitride film. forming either a second oxide film or a metal film as an ion-blocking film on the film, and patterning the nitride film and the ion-blocking film in a pattern corresponding to an active region to be formed in the well and the silicon substrate; ,
After that, leaving the inactive region of the well 111 and covering the other parts with an organic resist, a first ion is implanted into the inactive region of the well to form a first channel stopper, and then the silicon A second ion is implanted into the non-active region of the silicon substrate to form a second channel stopper, and the rest of the substrate is covered with an organic resist, leaving the non-active region of the silicon substrate. Oxidize to form a thick oxide film on the well and non-active regions of the silicon substrate connected to the first oxide film, and then oxidize the first oxide film on the active region. The method includes a step of once removing the I-oxide film and the nitride film and then forming a new thin gate oxide film.

Function> Instead of forming an organic resist on a nitride film as a mask when forming a channel stopper, an oxide film or an A
! Form one of the films and use this as a mask to implant ions into channels! Form a hetsuba. By taking this step, the outer 1° dimension of the nitride film and the inner dimension of the channel stopper can be made the same, and miniaturization becomes possible.

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

FIG. 1 is an eleventh diagram showing the main parts of one embodiment of the present invention. Note that the same reference numerals are used for parts having the same functions as those shown in FIG. 2, and the description thereof will be omitted as appropriate.

2. Since the steps from J(a) to (e) are the same as the steps of this example, the first step corresponding to the step of FIG. 2(f)
The explanation will start from the process shown in Figure (a).

FIG. 1 (a> shows the process of forming a selective oxidation pattern. A ρ-shaped well 13 is formed on a part of the upper surface of a silicon substrate 10, and an oxide film 14 and a nitride film 15 are formed on these wells. (corresponding to FIG. 2(e)), oxide JI 132 is formed as an ion-blocking film by CVD. After this, the silicon substrate 10 and the portion corresponding to the active region of the well 13 are separated using a mask. nitride film 15 and oxide film 3, leaving
Remove 2.

Next, the process moves to the step of forming an N-MOS channel stopper as shown in FIG. 1(b). In this step, an organic resist 17 is applied after step (a), and the resist 17 is removed from the rest of the inactive region of the ρ-shaped well 13 by phosphorography using a third mask. After this, boron (B+) is ion-implanted using the oxide film 32 and the resist 17 as a mask to form a channel stopper 1 to prevent inversion to the inactive region.
8 is formed in a p-type well 13.

In FIG. 1C, a P-MOS channel stopper is formed in the same manner. In forming this channel stopper 33, first, the resist 17 is once removed, but during this removal, the inorganic oxide film 32 is not removed but remains as it is. After this, an organic resist 19 is applied again, and the resist 19 is removed from the other portions of the silicon substrate 10 by phosphorography using a mask, leaving an inactive region, and phosphorus ions (P+) are implanted into the channel. A stopper 33 is formed.

Next, after removing the ion element film, a thick oxide pattern 22 connected to the oxide film 14 is formed in the non-active region by thermal oxidation (FIG. 1(d)).

In the gate oxidation step shown in FIG. 1(e), after the oxide film 14, nitride film 15, etc. in the gate portion are once removed, a new thin gate oxide film 23 is formed.

The subsequent steps are the same as those shown in FIGS. 2(k) to (n).

In this embodiment, the ion blocking layer 32 is made of SiO2 formed by CVD, but the ion blocking layer may also be a metal film of Al'PAu formed by vapor deposition or sputtering. That is, although the ion-blocking film is removed during the steps (c) to (d) in Figure 1, the contrast with the nitride film is small when determining whether S i 02 has been completely removed. There is a risk of oversight during visual inspection. In this respect, since AI has a large contrast with respect to the nitride film, it has the effect of not being overlooked by visual inspection.

<Effects of the Invention> As described above in detail with the embodiments, according to the present invention, instead of forming an organic resist on a nitride film as a mask when forming a channel stopper, S i 0
Since the channel stopper is formed by ion implantation using this as a mask, the outer dimension of the nitride film and the inner dimension of the channel stopper can be made the same, and the predetermined It becomes possible to miniaturize the channel stopper while maintaining its breakdown voltage.

[Brief explanation of drawings]

FIG. 1 is a process diagram showing essential parts of an embodiment of the present invention, and FIG. 2 is a process diagram showing a conventional process for manufacturing a semiconductor device. 10... Silicon substrate, 11... Oxide film, 13...
- P-type well, 14...first oxide film, 15...nitride film, 16.17...resist, 18...channel stopper 19...resist, 20...resist, 21
... Channel stopper, 23 ... Gate oxide film, 2
4... Polysilicon, 25... Gate electrode, 32.
...Ion blocking membrane, 33...Channel stopper. Figure 311: lb<)

Claims (1)

[Claims] Wells are formed on the silicon substrate, and a first
Covering with an oxide film and a nitride film, further forming either a second oxide film or a metal film as an ion blocking film on the nitride film,
The nitride film and the ion blocking film are patterned into a pattern corresponding to the active region formed in the well and the silicon substrate, and then the non-active region of the well is left and the other parts are covered with an organic resist. First ions are implanted into the non-active region of the well to form a first channel stopper, and then the non-active region of the silicon substrate is left and the rest is covered with an organic resist. After implanting second ions into the region to form a second channel stopper, the ion blocking film is removed and field oxidation is performed to form a thick oxide in the well and non-active regions of the silicon substrate connected to the first oxide film. A method for manufacturing a semiconductor device comprising the steps of: forming a gate oxide film, then once removing the first oxide film and the nitride film on the active region, and then forming a new thin gate oxide film.