JPS62277732A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form a groove section having an excellent shape by selectively shaping a substance layer having different etching characteristics onto a single crystal semiconductor base body, selectively growing a single crystal semiconductor layer to an exposed section in an epitaxial manner and optionally removing the substance layer through etching. CONSTITUTION:A substance layer having etching characteristics different from silicon such as an SiO2 layer 5 is shaped onto one main surface of a single crystal semiconductor base body such as a single crystal silicon base body 1 in uniform thickness corresponding to the depth of a groove to be formed through a CVD method. The SiO2 layer 5 is patterned through anisotropic etching such as reactive ion etching, and the SiO2 layer 5 having equal width in the thickness direction is left only in a section to which the groove section is shaped. An silicon layer 6 is grown selectively only on the silicon base body 1 with no SiO2 layer 5 in an epitaxial manner by using the mixed gas of SiH4+ HCl or the mixed gas of SiH2Cl2+HCl. The SiO2 layer 5 is removed through etching by a solution such as an HF solution, thus forming the groove section 7 to the surface of the single crystal silicon base body.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of forming a required groove in a semiconductor substrate.

[Summary of the Invention] The present invention provides a method for forming a desired groove on the surface of a single crystal semiconductor substrate by selectively etching a portion of the single crystal semiconductor substrate where the groove is to be formed. After forming material layers with different properties, a single crystal semiconductor layer is epitaxially grown selectively on the exposed portion of the single crystal semiconductor substrate, and then the material layer is selectively etched away to improve the surface of the single crystal semiconductor substrate. A well-shaped groove is formed in the groove.

[Conventional technology]

Recently, in semiconductor integrated circuits, trenches have been used to isolate elements or to form so-called I-wrench capacitors. Conventionally, such grooves have been formed by reactive ion etching (RIE). That is, as shown in FIGS. 3A and 3B, an etching layer 21 is selectively formed on the surface of a single crystal semiconductor substrate, such as a single crystal silicon substrate (1), and then the surface of the substrate is etched by reactive ion etching. A groove (3) was formed.

[Problem that the invention seeks to solve]

By the way, with the miniaturization of semiconductor integrated circuits, the groove (3)
However, when forming a deep m section using reactive ion etching technology, the shape tends to deteriorate as shown in FIGS. 3A and 3B. Furthermore, since the ions directly hit the silicon surface, the inner surface of the groove (3) is damaged. Reactive ion etching of silicon causes significant damage, and subsequent light solution etching cannot remove crystal defects caused by the damage.

In view of the above-mentioned points, the present invention provides a method for manufacturing a semiconductor device, which enables formation of a groove portion of an excellent shape in a semiconductor substrate.

[Means for solving problems]

In the present invention, a material layer (5) having etching characteristics different from that of the single crystal semiconductor substrate is selectively formed in a portion of the single crystal semiconductor substrate (1) where a groove is to be formed, and then a material layer (5) having etching characteristics different from that of the single crystal semiconductor substrate (1) is formed. ) is selectively applied to the exposed portion of the single crystal semiconductor layer (6).
) is epitaxially grown, the material layer (5) is selectively etched away to form a groove (5) on the surface of the single crystal semiconductor substrate.
7).

[Effect]

In this manufacturing method, the shape of the material layer (5) selectively formed on the semiconductor substrate (11) becomes the shape of the groove (7).The material layer (5) is formed by patterning to have a uniform width in the thickness direction. In order to be able to
) is removed by selective etching, grooves (7) of excellent shape are formed on the surface of the single crystal semiconductor substrate. Also, the material layer (5) is removed by solution etching to form the groove (7).
Therefore, the inner surface of the groove (7) is not damaged as in the conventional method described above.

〔Example〕

Embodiments of the method for manufacturing a semiconductor device according to the present invention will be described below with reference to the drawings.

As shown in FIG. 1A, a material layer (5) having etching properties different from that of silicon, such as a 5i02 layer (5), is formed by CVD on the entire surface of a single crystal semiconductor substrate, such as a single crystal silicon substrate fil.
(chemical vapor deposition) method. SiO at this time
Two layers (formed with a uniform thickness corresponding to the depth of the groove to be formed after 51WI).

Next, as shown in FIG. 1B, the 5i02 layer is patterned by a different etching method such as reactive ion etching (RIE) to form a SiO2 layer with a uniform width in the thickness direction only in the portion where the groove is to be formed. Leave layer (5). Here, in the case of reactive ion etching for S io2'PI (5), there is little damage to the silicon surface, and crystal defects due to damage are removed by subsequent light solution etching.

Next, as shown in FIG. 1C, so-called selective epitaxial growth is performed using a mixed gas of 5IH4+HCfl or a mixed gas of SiH2σ2+HCl2. At this time,
Due to the use of HCn, no silicon layer is formed on the 5i02 layer (5), and therefore the silicon layer (6) is selectively formed only on the silicon substrate (1) without S102Fi (s+).
grows epitaxially.

Next, as shown in the first diagram, the 5i02 layer (5) is removed by etching with, for example, HFf6 solution to form a groove (7) on the surface of the single crystal silicon substrate.

In this manufacturing method, the 5i02 layer (5) is patterned by reactive ion etching, so that a well-shaped 5i02 layer (5) with a uniform width in the thickness direction remains. Then, in selective epitaxial growth, a silicon layer (6) is formed along the side surfaces of the 5i02 layer (5), and then the 5i02 layer (5) is etched away to form a groove (7), resulting in a very shaped etching. Good grooves (7) can be formed. Further, since the 5i02 layer (5) is removed by solution etching, crystal defects due to damage do not occur on the inner surface of the formed groove (7), unlike when reactive ion etching is used.

On the other hand, for example, a trench capacitor for a 4M bit dynamic RAM requires a trench with a depth of 3 to 4 μm.
In the example shown in the figure, it is difficult to form the SiO2 layer (5) so thickly. FIG. 2 shows an example of a manufacturing method used when deeper grooves are required.

First, as shown in FIG. 2A, a polycrystalline silicon layer (10) having a thickness corresponding to the depth of the groove to be formed is formed on the main surface of a single crystal semiconductor substrate, for example, a single crystal silicon substrate (1). Adhesion is formed.

Next, as shown in FIG. 2B, a polycrystalline silicon layer (10) is formed.
After patterning the polycrystalline silicon layer (10) to leave only the portion where the groove is to be formed, thermal oxidation is performed as shown in FIG. 2C. In this thermal oxidation process, polycrystalline silicon 1 (10
) and the surface of the silicon substrate (1) are oxidized to form 5i02
5 (11).

Next, as shown in the second diagram, the 5i02 layer (11) is patterned to form a groove.
).

Then, as shown in the 21st page, Si)! 4+HCJ! Perform selective epitaxial growth using a mixed gas of 5i8202+H or a mixed gas of 5i8202+H to form a single crystal silicon layer (6) with a thickness similar to that of the 5i02 layer (11) on the surface of the silicon substrate other than the 5i02 layer (11). do.

Thereafter, 5iO2fi (11) is removed by etching with an HF solution to form a required groove (7) on the surface of the substrate.

In this example, instead of 5i02, polycrystalline silicon, which can be formed thickly, is used and thermally oxidized to form SiO2, so that the SiO2 layer (11) that is finally etched away can be formed thickly, and the deep grooves (7 ) can be formed.

〔Effect of the invention〕

According to the present invention, a deep and well-shaped groove can be formed on the surface of a single crystal semiconductor substrate. Further, when forming the groove, the inner surface of the groove is not damaged (and the groove can be formed with good crystallinity).

Therefore, the present invention is particularly suitable for forming grooves for isolation between elements or trench capacitors in semiconductor integrated circuits that are miniaturized and highly integrated.

[Brief explanation of drawings]

1A to 1D are process diagrams showing an example of the method for manufacturing a semiconductor device according to the present invention, FIGS. 2A to 2F are process diagrams showing another example of the method for manufacturing a semiconductor device according to the present invention, and FIG. 3A and B are cross-sectional views showing examples in which grooves are formed using the conventional reactive ion etching method. (1) is a single crystal silicon substrate, (5) is a Si02 layer,
(6) is a single crystal silicon layer, (7) is a groove portion, (10) is a polycrystalline silicon layer, and (11) is a SiO7 layer. (e-embedded Italy) Sadado Hei Matsukuma Hidemori A B Figure 3

Claims (1)

[Scope of Claims] A step of selectively forming a layer of material having etching characteristics different from that of the single crystal semiconductor substrate in a portion of the single crystal semiconductor substrate where a groove is to be formed; and a portion where the single crystal semiconductor substrate is exposed. 1. A method for manufacturing a semiconductor device, comprising: selectively epitaxially growing a single crystal semiconductor layer; and selectively etching away the material layer to form a groove on a surface of a single crystal semiconductor substrate.