JPS618942A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To contrive the improvement in productivity by ensuring a burying sufficiently by a method wherein a thin film is formed on a semiconductor substrate and an aperture is opened on said thin film after which a recess communicating with said aperture is formed on the semiconductor substrate and particulate insulating substances are stuck to the overall surface under that condition and then the particulate insulating substances on a surface of the thin film are removed and are filled in the recess and said substances are heated to fill the recess. CONSTITUTION:As shown in FIG. (a), a thin film 9 (e.g. a thermal oxidation Si film and a polysilicon film on that) is formed on a surface of a semiconductor substrate 1 and a photoresist film 2 is formed over the overall surface. Then an aperture 2a is formed in the necessary position. Etching of the substrate 1 is done to the necessary depth and the photoresist film 2a is removed. Then a recess 3 is formed under the condition as shown in FIG. (c) and particulate insulating substances 10 (e.g. SiO2 powder) are stuck to the overall surface. Subsequently, the particulate insulating substances are contained only in the recess 3 and the semiconductor substrate 1 is put in the atmosphere which is so heated that the substances 10 can be fused. The processes of the second overall adhesion of particulate insulating substances 10, removal of the substances 10 on the surface, containing those in the recess 3 as shown in FIG. (g), and fusing the substances are repeated. Then the thin film 9 is subjected to the overall etching to be removed and the burying process is finished.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a semiconductor device, in which a recess S formed in a semiconductor substrate is filled with an insulating material in a manufacturing process of the semiconductor device.

[Prior art]

A recess is formed on the surface of the semiconductor substrate, for example, in order to separate left and right elements or regions M. These recesses are filled with an insulator to eliminate voids and prevent device characteristics from deteriorating.

The conventional manufacturing method of this type of semiconductor device is shown in FIG. 1(a).
-(f) are cross-sectional views of the main parts of the substrate shown in the order of steps. First, as shown in FIG. 1(a), a semiconductor substrate (
A photoresist film (2) is formed on the surface of the photoresist film (2), and through a normal mask pattern transfer process, a portion of the photoresist film (2) at a desired position is removed to form an opening (2a). Using this photoresist film (2) as a mask, the semiconductor substrate fil is etched to the required depth, and then
．． When the photoresist film (2) is removed, a recess 5 (3) is formed as shown in FIG. 1(b). Next, in order to fill this recess with an insulating material, a first
As shown in Figure (C), an insulating film (4) (for example, a silicon oxide film) is formed over the entire surface. Then, the entire surface is etched by, for example, a dry etching method that utilizes the linearity of reactive ions, so-called reactive ion etching method.
As shown by the button in FIG. 1, when the insulating film (4) outside the recess (3) is removed, a residual insulating film (5) remains on the side surfaces of the recess (3). If the recess (3) is not filled with such a residual insulating film (5), as shown in FIG. 1(e), immediately form a second insulating film (6) and then Etch the entire surface again.

By repeating this insulating film formation and etching, the first
As shown in Figure (f), the buried insulating layer (7) has a recess (3).
) can be filled in.

However, in the above conventional method, the process ' is complicated and the productivity is low.
There was a risk of creating a cavity (8) in the buried insulating layer ('') and deteriorating the device characteristics.Furthermore, if there are concave portions of various widths on the same substrate surface, the time required to complete the filling may be reduced. Therefore, a recess with a large width is more difficult to fill than a recess with a small width.

Furthermore, if the width of the recess is extremely narrow and the depth is considerably larger than the width, it becomes difficult to form a film in the recess, and embedding may not be possible. Next, a thin film is formed on the semiconductor substrate, a recess is formed in the semiconductor substrate through which the thin film is opened and communicated by photolithography and etching, and a granular insulating material is attached to the entire surface of this state, and the granular insulating material on the surface is removed. The granular insulating material is removed and filled into the recess, and the granular insulating material is heated and melted to fill the recess. As a result, a large amount of granular insulating material can be accommodated in the recess corresponding to the thickness of the thin film, and the number of repetitions of filling and melting the granular insulating material can be reduced, allowing for faster filling, ensuring reliable embedding, and increasing productivity. It is an object of the present invention to provide a method for manufacturing a semiconductor device, in which recesses of different sizes and shapes on the same plane can be filled uniformly and reliably.

[Embodiments of the invention]

Hereinafter, a method for manufacturing a semiconductor device according to an embodiment of the present invention will be described with reference to sectional views of main parts of a substrate shown in the order of steps in FIGS. 2(a) to 2(1). First, as shown in FIG. 2(a), a thin film (9) (for example, a thermally oxidized silicon film and a polycrystalline silicon film thereon) is formed on the surface of the semiconductor substrate fl1. This thin film (9) is then formed on the substrate (3) of the recess (3).
11 to maintain a certain height above the surface, and is made of a material that can be easily removed by etching after use. Next, as shown in FIG. 2(b), a photoresist film (2) is formed on the entire surface, and openings (2&) are formed at desired positions in the photoresist film (2) through a normal mask pattern transfer process. do.

A thin film (9) is used as a mask for this photoresist film (2).
is etched by, for example, a dry etching method using a Freon gas to form a Sekiguchi portion (9a) (indicated by a chain line). Using these photoresist film (2) and thin film (9) as masks, the semiconductor substrate fl+ is etched to the required depth, and then the photoresist film (2) is removed.
A recess (3) is formed in the state shown in FIG. 2(Q).

Thereafter, as shown in FIG. 2(+1)K, a granular insulating material (10) (for example, silicon dioxide powder) is deposited on the entire surface. Next, the granular insulating material (10) on the surface of the thin film (9) is removed by a method such as centrifugation or air blowing, and the granular insulating material is placed in the recesses (as shown in FIG. 2(e)).
3). Next, when the semiconductor substrate (11) is placed in an atmosphere heated to a temperature of 900° C. or higher to the extent that the granular insulating material (lO) melts, the granular insulating material It f
In the case of No. 101, the recess (3) cannot be filled sufficiently with one deposition and melting, so a second deposition is performed on the entire surface of the granular insulating material (10) and the granular insulating material (10) on the surface is removed. By repeating the step of accommodating VC in the recess (31) and melting it as shown in the figure (-), the metal part inside the recess (3) is filled with a buried insulating layer (121) as shown in FIG. 2(h).

As shown in FIG. 2(g), the opening (9a) of the thin film (9) allows the recess (3) to reach a position higher than the surface of the substrate (1).
The upper surface of the buried insulating layer opening 21 can be aligned with the surface of the substrate (11) after being melted by adding t, as shown in FIG. 2(h). As shown in FIG. 2 (1), the embedding process is completed by etching away the entire surface of the thin film (9). It is determined by the rate of decrease. Based on this rate, the granular insulating material is The thickness of the thin film (9) is set so that the required amount of (10) is accommodated.

In the above example, the particle size of the insulating material (lO) was the same in the first and second and subsequent adhesion processes, but the particle size was gradually decreased from the second time onwards. It's okay.

Further, in the above embodiment, the granular insulating material +101 is spherical;
It may also be a polyhedron such as a polyhedron.Also, silicon dioxide may be used as a thin film material.

〔Effect of the invention〕

As described above, according to the method of the present invention, a thin film is formed on a semiconductor substrate, a recess is formed in the semiconductor substrate by opening the thin film by photolithography and etching, and communicating with the recess, and the entire table in this state is The granular insulating material is attached, the granular insulating material on the surface of the thin film is removed to fill the recess, and the granular insulating material is melted by heating to fill the recess, so the granular insulation fills the recess through the opening of the thin film. A large amount of material can be accommodated, the number of repetitions of filling and melting the granular insulating material can be reduced, and embedding can be performed sufficiently and reliably.

Furthermore, the process is simplified and productivity is improved, and even if the recesses on the same plane have different sizes and shapes, they can be filled uniformly and reliably.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of a substrate showing a conventional method for manufacturing a semiconductor device in the order of steps, and FIG. 2 shows a method for manufacturing a semiconductor device according to an embodiment of the present invention in order of steps. This is a decisive picture. 1... Semiconductor substrate, 2... Photoresist film, 3...
・Concave portion, 9... thin film, 9a... opening, 10...
Particulate insulating material, 11... Filled insulating film, 12... Buried insulating layer Note that the same reference numerals in the drawings indicate the same or corresponding parts.

Claims (4)

[Claims] (1) Form a thin film on the surface of the semiconductor substrate, form an opening in the thin film by photolithography and etching, and form a recess in the semiconductor substrate communicating with the opening, and form grains on the entire surface of the thin film and in the recess. 1. A method for manufacturing a semiconductor device, comprising: depositing an insulating material, removing particulate insulating material on the thin film surface to fill the recess, and heating and melting the filled insulating material to fill the recess. (2) The method for manufacturing a semiconductor device according to claim 1, wherein the granular insulating material is made of silicon dioxide powder. (3) A method of manufacturing a semiconductor device according to claim 1 or 2, wherein the thin film is composed of a thermally oxidized silicon film and a polycrystalline silicon film on the upper surface thereof. (4) A method for manufacturing a semiconductor device according to claim 1 or 2, wherein the thin film is made of silicon dioxide.