JP3395719B2 - Method for manufacturing semiconductor device - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to relates to a method of manufacturing a semiconductor equipment, in particular, less pattern dependency, a method of manufacturing a suitable semiconductor equipment to form the accurate isolation region.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor device having trench element isolation, it has been an important factor to obtain a good burying property of an oxide film inside a trench.

For this reason, Si for forming trenches is usually used.
In the etching of the substrate, the side wall of the trench is formed with a taper angle of 85 ° or less with respect to the surface of the Si substrate so as to improve the filling property when the inside of the trench is filled with the CVD oxide film.

FIG. 5 is a process sectional view of the method for manufacturing a semiconductor device in this case. As shown in FIG. 5, when the trench sidewall is tapered by etching, the etching gas system is controlled to form the oxide-based deposit on the trench sidewall while etching is performed to taper the trench sidewall. However, due to the size of the element isolation width, so-called
Due to the microloading effect, as shown in FIG.
There is a problem that the size of the taper angle changes.

For this reason, device characteristics, particularly, fluctuations in the threshold value of the MOS transistor are adversely affected.
This problem has been a serious problem in a fine device that forms an element separation of 0.2 μm or less.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned drawbacks of the prior art, and in particular, trench element isolation having a good filling property by tapering the trench sidewalls due to the difference in the thickness of the inner wall oxide film. forming a there is provided a novel process for producing a semiconductor <br/> equipment.

Furthermore, another object of the present invention does not depend on the pattern has a stable taper angle, thereby to provide an electrical characteristic stability is novel process for producing a semiconductor equipment was the .

[0008]

In order to achieve the above-mentioned object, the present invention basically adopts the technical constitution as described below.

[0009]

[0010] or, a first aspect of the manufacturing method of the semiconductor device according to the present invention is a manufacturing method of a semiconductor device having an element isolation region of a trench shape, the SiO ₂ film is formed on the semiconductor substrate, the SiO ₂ First forming a SiN film on the film
And step, after forming the SiN film, and a second step of injecting a <br/> nitrogen ions into the substrate table surface, the nitrogen ions
After pouring, a third step of forming a trench in a predetermined region of the substrate, wherein the third step in forming the trench surface is thermally oxidized, the fourth that allowed to form a first oxide film on the surface of the trench A fifth step of filling a trench covered with the first oxide film with a second oxide film, and a sixth step of removing the second oxide film deposited on the entire surface of the substrate, And a second aspect.
It is a step for forming a trench in a predetermined region before Symbol substrate relative to the substrate surface, which is characterized by forming a trench having sidewalls of 90 degrees, or, a third aspect, the substrate In the step of forming the trench in the predetermined region of, the trench is formed so that the side wall of the trench forms a taper at a predetermined angle of 90 degrees or less with respect to the substrate surface. The fourth aspect is characterized in that the surface of the first oxide film formed in the trench has a taper of 85 degrees or less with respect to the surface of the substrate.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A semiconductor device according to the present invention is a semiconductor device having a trench-shaped element isolation region, wherein a trench shape having a small pattern dependence is obtained by using nitrogen ion implantation and trench inner wall oxidation. It is in.

As shown in FIG. 1, before etching the SiN film and the Si substrate, as shown in FIG. 1B, nitrogen ions are introduced so that the implantation range Rp of the ion implantation reaches the surface of the Si substrate. Implantation is performed to oxidize the inner wall of the trench after etching the trench to form a taper of 85 ° or more on the side wall of the trench.

By thus tapering the inner wall of the trench, as shown in FIG.
In the case of burying with a VD oxide film, good burying property can be obtained, and moreover, shape variation due to the microloading effect due to the separation width and the density of the pattern can be suppressed.

Therefore, variations in electrical characteristics such as the threshold value of the transistor due to variations in trench shape can be reduced, and a semiconductor device having stable characteristics can be obtained.

[0015]

EXAMPLES Hereinafter, specific examples of the manufacturing method of the semiconductor equipment according to the present invention with reference to the drawings will be described in detail.

(First Specific Example) FIGS. 1 and 2 are views showing the structure of a first specific example of a semiconductor device and a method of manufacturing the same according to the present invention. In these figures, trench shapes are shown. And a bottom portion 1B of the trench 21 having a thin film thickness on the inner wall 21a of the trench 21 on the front surface 1A side of the substrate 1.
A semiconductor device is shown in which a first oxide film 4 having a large film thickness is formed on the side, and a portion surrounded by the first oxide film 4 is filled with a second oxide film 5, and The substrate 1
The interface 14 between the first oxide film 4 and the first oxide film 4 forms approximately 90 degrees with respect to the surface 1C of the substrate 1, and the interface 45 between the first oxide film 4 and the second oxide film 5 is the substrate surface. A semiconductor device is shown in which a taper T is formed so as to form a predetermined angle θ with respect to 1C, and the first oxide film 4 is also shown.
The semiconductor device is characterized in that the angle θ of the interface 45 between the second oxide film 5 and the second oxide film 5 is 85 degrees or less with respect to the substrate surface 1C.

Furthermore, in a method of manufacturing a semiconductor device having a trench-shaped element isolation region, the semiconductor substrate 1 is made of Si.
A first step of forming an O ₂ film 2, forming a SiN film 3 on the SiO ₂ film 2, and implanting nitrogen ions so that the surface of the substrate has a predetermined concentration; Second step of forming the trench 21 in the region of 2 and the surface of the trench 21 formed in the second step is thermally oxidized to form the trench 2
A third step of forming the first oxide film 4 on the first surface,
A fourth step of filling the trench 21 covered with the first oxide film 4 with a second oxide film 5, and a fifth step of removing the second oxide film 5 deposited on the entire surface of the substrate, There is shown a method for manufacturing a semiconductor device, which comprises:

The first specific example will be described in more detail below.

FIG. 1 is a sectional view in each step of this example, and FIG. 2 is a graph showing a profile of nitrogen ion implantation.

Si is formed on the Si semiconductor substrate 1 by thermal oxidation.
The O ₂ film 2 is formed with a thickness of, for example, 10 nm, and the SiN film 3 is formed with a thickness of, for example, 150 nm by the CVD method (FIG. 1).
(A)). Then, for example, the implantation energy 60 is set so that the implantation range Rp of the ion implantation comes near the surface of the Si substrate.
Nitrogen ions are implanted with keV and an implantation dose of 5E14 / cm ² (FIG. 1B). The profile of ion implantation in this case is as shown in FIG.

Then, using a lithography process, S
The iN 3, the SiO ₂ film 2, and the Si substrate 1 are etched by anisotropic etching to form a trench 21 having a depth of 400 nm, for example (FIG. 1C). The etching is performed so that the side wall 21a of the trench 21 has a shape perpendicular to the surface of the Si substrate. Then, the inner wall oxide film 4 is formed by thermal oxidation. When nitrogen ion implantation is performed as described above, the nitrogen concentration becomes high on the substrate surface as shown in FIG. Since the nitrogen concentration is low, the side wall 21a at the bottom of the trench 21 has an oxide film thickness of 65 nm, while the upper portion of the trench 21 has an oxide film thickness of about 40 nm. Therefore, the inner wall oxide film 4 is 85 ° or less (in this case, 84 °). The shape has a taper T of (°) (FIG. 1 (d)). The inner wall oxide film 4
Is formed at a high temperature of 1000 ° C., for example, and has a function of rounding the shape of the upper portion of the trench and a function of protecting the element formation region from metal impurities from the trench-buried oxide film, which is performed thereafter.

After this, HDP (High Densit)
y plasma) and the like to form a CVD oxide film 5 to fill the inside of the trench 21 (FIG. 1).
(E)).

Since the surface T of the inner wall oxide film 4 is tapered, the burying property of the CVD oxide film 5 is improved. After that, the excess CVD oxide film 5 on the SiN film 3 is removed by the CMP method (FIG. 1 (f)). Then, although not shown, the SiN film 3 and the SiO ₂ film 2 are removed by wet etching, and a MOS device is formed by a known method.

In this specific example, the Si substrate for forming the trench is etched so that the side wall 21a of the trench has a vertical shape, and the inner wall oxide film 4 formed by thermal oxidation forms a taper T on the inner wall of the trench. As compared with the case where the side wall of the trench is tapered by the trench etching, there is no difference in the trench shape due to the size of the element isolation space, and a stable shape and device characteristics can be obtained.

(Second Specific Example) FIG. 3 is a diagram showing a structure of a second specific example of the present invention. In these drawings, a method of manufacturing a semiconductor device having a trench-shaped element isolation region is shown. And the first step of implanting nitrogen ions so that the surface of the semiconductor substrate 1 has a predetermined concentration.
And step, said SiO ₂ film 2 is formed on the semiconductor substrate, the formed second step of forming a SiN film 3 is formed on the SiO ₂ film 2, a trench 21 in a predetermined area of the substrate 1 3 and the trench 21 formed in the third step
A fourth step of thermally oxidizing the surface to form the first oxide film 4 on the surface of the trench 21, and a fifth step of filling the trench covered with the first oxide film 4 with the second oxide film 5. A method for manufacturing a semiconductor device is shown, which includes a step and a sixth step of removing the second oxide film 5 deposited on the entire surface of the substrate.

The second specific example will be described in more detail below.

In this example, the ion implantation is performed before the SiN film is formed. The process sectional view is shown in FIG.

As shown in FIG. 3A, for example, an implantation energy of 5 keV and a dose of 5E1 are applied to the surface of the Si substrate.
Ion implantation of 4 / cm ² is performed, and nitrogen ion implantation is performed so that the peak of concentration comes to the substrate surface. After that, SiO
₂ film 2 and SiN film 3 are formed (FIG. 1B). After that, the inner wall oxide film 4 having the taper T is formed through the same steps as in the first specific example, and the trenches are filled (FIGS. 3C to 3F).

In this example, since the ion implantation is performed before the SiN film 3 is formed, the above-mentioned low energy shallow ion implantation is required in order to have a concentration peak on the Si substrate surface. Although it causes a decrease in throughput,
Since the steep concentration profile is obtained as compared with the first specific example, there is an advantage that the taper T of the inner wall oxide film 4 can be formed more easily.

In this specific example, nitrogen ions are directly implanted into the Si substrate, but after the SiO ₂ film 2 is formed,
Even if nitrogen ion implantation is performed before forming the SiN film 3,
For example, in the case of passing a thin film of about 10 nm, it can be performed under substantially the same implantation conditions as in the case of directly implanting into the Si substrate.
The same effect as above can be obtained.

(Third Concrete Example) FIG. 4 is a diagram showing the structure of a third concrete example of the present invention. In these figures, the boundary surface between the substrate 1 and the first oxide film 4 is shown. 14, a taper T14 having a first angle θ1 with respect to the substrate surface 1C is formed, and a boundary surface 45 between the first oxide film 4 and the second oxide film 5 has a taper T14 with respect to the substrate surface 1C. 1
There is shown a semiconductor device in which a taper T45 having a second angle θ2 equal to or less than the angle θ14 is formed.

The third specific example will be described in more detail below.

In the above specific example, the side wall 21a of the trench is formed so that the angle is 90 degrees with respect to the surface of the substrate. In this specific example, however, the side wall 21a of the trench is tapered to facilitate the filling of the trench. FIG. 4 is a process sectional view in this case.

As shown in FIG. 4 (a), as in the first specific example, after nitrogen ion implantation is performed, as shown in FIG. 4 (b),
As shown in (c), the inner wall of the trench is etched to a degree such that an etching defect of, for example, about 86 ° is unlikely to occur, and the shape difference due to the element separation distance does not become too large. The inner wall oxide film 4 is formed. Therefore, a large taper angle θ2 of about 80 ° can be obtained, and the trench filling property is further improved.

Therefore, not only the object of the present invention that the difference in the shape of the trench is unlikely to occur can be achieved, but also the trench having a larger taper angle can be formed by the effects of both the etching shape and the difference in the thermal oxide film thickness. This is advantageous for embedding a miniaturized pattern.

[0036]

The method of manufacturing a semiconductor equipment according to the present invention is, since it is configured as described above, it is possible to form a buried with good trench isolation.

Further, it is possible to form a trench element isolation having a stable taper angle and stable electrical characteristics without depending on the pattern.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first specific example according to the present invention.

FIG. 2 is a graph showing a profile of nitrogen ion implantation.

FIG. 3 is a sectional view showing a second specific example according to the present invention.

FIG. 4 is a sectional view showing a third specific example according to the present invention.

FIG. 5 is a cross-sectional view showing a conventional example.

FIG. 6 is a cross-sectional view showing a conventional example.

[Explanation of symbols]

1 the side walls of the semiconductor substrate 1A substrate surface portion 1B trench bottom 1C substrate surface 2 Si0 ₂ film 3 SiN film 4 inner wall oxide film 5 CVD oxide film 14, 45 the boundary surface 21 trenches 21a trenches T, T14, T45 taper θ, θ14, θ45 Taper angle

Claims (4)

(57) [Claims] 1. A half having a trench-shaped element isolation region
A method of manufacturing a conductor arrangement, the SiO ₂ film is formed on a semiconductor substrate, in the SiO ₂ film
A first step of forming a SiN film, and nitrogen ions on the surface of the substrate after forming the SiN film.
And a second step of implanting nitrogen ions, and then implanting a predetermined region of the substrate after implanting the nitrogen ions.
A third step of forming a trench, the third forming trenches surface process is thermally oxidized, DOO
Fourth step of forming first oxide film on wrench surface
And a second oxide film inside the trench covered with the first oxide film.
And a fifth step of removing the second oxide film deposited on the entire surface of the substrate.
6. A method of manufacturing a semiconductor device, comprising: 2. Forming a trench in a predetermined region of the substrate
In the step of forming, a side wall of 90 degrees with respect to the substrate surface is provided
A half according to claim 1, characterized in that a trench is formed.
A method for manufacturing a conductor device. 3. Forming a trench in a predetermined region of the substrate
In the step of performing, the side wall of the trench is
Train to form a taper with a predetermined angle of 0 degrees or less.
2. The semiconductor device according to claim 1, wherein
Manufacturing method. 4. The first acid formed in the trench
The surface of the oxide film has a taper of 85 degrees or less with respect to the surface of the substrate.
The semiconductor device according to claim 1, further comprising:
Manufacturing method.