JPH088341A - Fabrication of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a method for fabricating a semiconductor substrate in which an oxide can be deposited reliably with high flatness. CONSTITUTION:In the method for fabricating a semiconductor device having a protective film on the surface of a substrate provided with protrusions and recesses, a first oxide 3 is deposited, at first, on the substrate until the opening C of at least the smallest recess in the surface of a substrate 1 is closed. The oxide is then etched back to open the recess in the surface of the substrate again. Subsequently, an SOG film 4 is applied to the surface in order to till the opening and then a second oxide 5 is deposited thereon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for forming an oxide film for flattening a semiconductor substrate having a step.

[0002]

2. Description of the Related Art Conventionally, as a method for flattening a semiconductor substrate having a step shape, a method according to the process shown in FIG. 2 is known. In this method, first, as shown in FIG. 2A, a metal wiring 2 is formed on a semiconductor substrate 1, and then a first oxide film 3 having an appropriate film thickness (for example, 300 nm) is formed by a chemical vapor deposition method. To do. Since the step coverage of the oxide film formed by the chemical vapor deposition is low, the step difference of the wiring cannot be alleviated, and there is a problem that the wiring is broken when the aluminum wiring is formed. As shown in -b, the SOG film 4 is formed by a coating method to reduce the step portion. Thereafter, as shown in FIG. 2C, the second oxide film 5 is formed by a chemical vapor deposition method at a required film pressure (for example, 600 n).
Only m) is formed and flattening is performed.

[0003]

When the planarization is performed by the above-mentioned conventional method, as shown in FIG. 3A, the step coverage of the first oxide film 3 formed by the chemical vapor deposition method is low. The thickness of the oxide film 3 of the first layer becomes thin at the bottom of the step, and the SOG film 4
There is a problem that the stress of the SOG film 4 may cause cracks 6 in the oxide film 3 in the first layer when the film is formed, resulting in impaired reliability.

In order to prevent cracks 6 from occurring in the oxide film 3 of the first layer, the oxide film 3 of the first layer may be thickened, but as shown in FIG. If the thickness is too thick, there is a problem in that the oxide film formed by the chemical vapor deposition method has a poor step coverage, so that the cavity 7 is formed in the step portion.

The present invention was devised in order to improve such disadvantages of the prior art, and its main purpose is to:
It is an object of the present invention to provide a method for manufacturing a semiconductor substrate, which is capable of forming an oxide film having good flatness and high reliability.

[0006]

According to the present invention, such an object is a method of manufacturing a semiconductor device comprising a protective film on the surface of a substrate on which unevenness is formed, and at least the most of the surface of the substrate is provided. Depositing a first oxide film on the substrate until the opening of the small recess is closed; etching back the oxide film to reopen the recess on the surface of the substrate; and including the opening. Achieved by providing a method of manufacturing a semiconductor device, comprising: a step of applying an SOG film on a surface of a substrate to fill the opening; and a step of depositing a second oxide film on the surface of the substrate. To be done.

[0007]

When the flattening is performed by the method according to the present invention, the insulating film at the bottom of the step can be thickened, so that the SOG film formed on this insulating film will not cause cracks in the insulating film. .

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the embodiments shown in the accompanying drawings. FIG. 1 is a schematic diagram showing a preferred embodiment of the present invention. First, after forming a metal wiring layer on the semiconductor substrate 1, the metal wiring layer is selectively etched using a photoresist pattern (not shown). Then, since the uneven shape due to the metal wiring 2 is formed on the surface of the semiconductor substrate 1, the oxide film 3 is formed on the semiconductor substrate 1 by the chemical vapor deposition method until the surface of the semiconductor substrate 1 becomes flat in this state. That is, as shown in FIG. 1A, the oxide film 3 is deposited on the semiconductor substrate 1 until the opening C of the smallest recess on the surface of the semiconductor substrate 1 is closed. In this state, the portion not covered with the oxide film 3 becomes the cavity 7 and remains in the step portion.

Next, as shown in FIG. 1B, the entire surface of the oxide film 3 is etched away by etching back in order to leave a film thickness required as an interlayer insulating film, and a concave portion is opened again on the surface of the oxide film 3. . That is, etching back is performed until the opening C of the cavity 7 that has occurred in the step portion is exposed.

Next, as shown in FIG. 1-c, the opening C, which has appeared by cutting the surface of the oxide film 3, is filled by applying the SOG film 4. That is, when the cavity 7 generated at the step portion has a steep step, S
It is filled with OG film.

Thereafter, as shown in FIG. 1-d, an oxide film 5 having a required film thickness is formed by a chemical vapor deposition method.

Through the above process, the reliable oxide film 3
The steps were alleviated.

[0013]

As described above, according to the present invention,
It is possible to form a highly reliable oxide film for step relief, which does not cause a crack due to stress in the SOG film.

[Brief description of drawings]

FIG. 1 is a process diagram illustrating a method of forming an oxide film for reducing a step according to the present invention.

FIG. 2 is a process diagram illustrating a conventional flattening method.

FIG. 3 is an explanatory view of problems of the conventional flattening method.

[Explanation of symbols]

 1 Semiconductor Substrate 2 Metal Wiring 3 Oxide Film (First Layer) 4 SOG Film 5 Oxide Film (Second Layer) 6 Crack 7 Cavity

Claims (1)

[Claims] 1. A method of manufacturing a semiconductor device comprising a protective film on a surface of a substrate on which unevenness is formed, the method comprising: first forming a protective film on the substrate until at least the smallest concave opening on the surface of the substrate is closed. A step of depositing an oxide film, a step of etching back the oxide film to reopen a concave portion on the surface of the substrate, and a step of applying an SOG film to the surface of the substrate including the opening to fill the opening. And a step of depositing a second oxide film on the surface of the substrate, the method for manufacturing a semiconductor device.