JPH02851B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for planarizing a wafer for semiconductor devices. In particular, for semiconductor devices immediately after the vapor phase growth process of polycrystalline silicon (Si) layers, silicon nitride (Si ₃ N ₄ ) layers, silicate glass layers, etc., which are often used in the manufacturing process of semiconductor devices. Removes protrusions that often occur on the wafer surface,
The present invention relates to a method for planarizing the wafer surface.

Generally, the process of vapor phase growth of a desired substance onto a wafer for semiconductor devices is performed in a clean vacuum container, so macroscopically there is no possibility of foreign matter entering.
Since the reaction conditions are delicate, the surface is often not necessarily flat when microscopically inspected. That is, the presence of protrusions of silicon (Si), silicon nitride (Si ₃ N ₄ ), etc. with a height of 5 to 10 μm, and sometimes the presence of pieces of completely different substances.

In the past, due to the fact that the details of such flatness defects were not necessarily clear and the fact that there was no effective method to repair such flatness defects, it was not necessary to proceed to the next process as is. This resulted in a decrease in yield and further a decrease in reliability.

An object of the present invention is to provide a method for flattening the surface of a semiconductor device wafer having such poor flatness, by applying a thin layer of a viscous coating film to the surface after the completion of the vapor phase growth process. After the layer is first formed, a flat and smooth plate with high hardness is pressed to physically destroy the protrusions that cause poor flatness and turn them into fine particles, which are then treated with a cleaning agent. The gist is the process of rinsing and drying using an inert gas.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to the drawings to clarify the structure and unique effects of the present invention.

See Figure 1. The first step is to deposit silicon (Si) on which a desired vapor growth film 2 such as a polycrystalline silicon (Si) layer, silicon nitride (Si ₃ N ₄ ) layer, or silicate glass layer is provided.
A substance with high viscosity, chemical stability, and easy to wash away with water, such as polyvinyl alcohol (CH ₂ CHOH), etc., is applied to the surface of the semiconductor device wafer 1 made of ethyl alcohol (C ₂ H ₅ OH).
In this process, a liquid diluted with a suitable solvent (hereinafter referred to as lubricant 3) is applied thinly to a thickness of several μm to form a coating film. In addition to polyvinyl alcohol (CH ₂ CHOH), it is also possible to use rubber-based polymers typified by negative photoresists. Since the function of this liquid is as a lubricant or buffering agent in the next process, it is necessary to apply it as evenly as possible. Therefore, it is desirable to adopt a spin coating method. Therefore, the equipment used to carry out this step is
It is sufficient to connect to a wafer feeding device such as a normal wafer cassette type wafer feeding device or a belt conveyor type wafer feeding device and provide an anti-friction agent coating device having exactly the same structure as a normal spin coating device. However, it goes without saying that any other type of lubricant applicator may be used to carry out this step. Furthermore, in order to sufficiently increase the function as an anti-friction agent or a buffer material while limiting the adhesion with the press plate 4 used in the next step, the surface of the anti-friction agent 3 is baked at 150°C for about 10 minutes. It is desirable to leave only a dry coating film.

See Figure 2 The second step involves making silicon (Si), which is dry on the surface and covered with a thin layer of liquid lubricant inside.
A flat plate 4 (hereinafter referred to as a pressing plate) having high hardness, such as an etching mask, is pressed against the surface of the semiconductor device wafer 1, for example, to impede the flatness of the surface of the semiconductor device wafer 1. This is a process in which the protrusions 20 and the like that are present are destroyed and made into fine particles. Since the wafer 1 for semiconductor devices is generally a thin layer of 1 mm or less, it is important to press with enough pressure to not destroy the wafer 1 but also to destroy the protrusions 20 and the like. In this process, only the surface is in a dry state and the inside is filled with a liquid anti-friction agent, so that the surface of the semiconductor device wafer 1 is
The press plate 4 will not be damaged by the granules created by the destruction of the 0 etc., and the press plate 4 will not be contaminated with the anti-friction agent 3. The pressure plate pressing device used to carry out this process has a structure similar to the alignment device for etching, but has been modified so that a slight pressure can be applied between the mask, that is, the pressure plate and the wafer. That's enough. However, it goes without saying that any other type of press plate pressing device may be used to carry out this step.

In the third step, foreign particles floating in an anti-friction agent on the surface of the semiconductor device wafer 1 whose flatness has been achieved by destroying protrusions etc. are removed using a highly fluid chemical such as pure water. This is a process of rinsing with an inert liquid (cleaning agent). Even if the semiconductor device wafer 1 is rotated at high speed in a horizontal plane and the cleaning agent is sprayed vertically onto the surface at high speed,
Further, the purpose can also be achieved by holding the semiconductor device wafer 1 at an almost vertical angle and spraying the cleaning agent horizontally. The cleaning equipment used to carry out this process has a structure similar to a normal spin coating equipment, and the only features are that the cleaning agent can be sprayed from above at high speed, and it can be scattered in the normal direction. It is sufficient to provide a discharge system for the cleaning agent. It goes without saying that other devices can be used.

In the fourth step, the semiconductor device wafer 1, which has been planarized and from which the lubricant has been washed away, is heated to a relatively high temperature of about 150°C in a chemically inert dry gas such as dry nitrogen (N ₂ ) gas. This is a process of baking at a low temperature for an appropriate time of about 5 to 10 minutes and drying while preventing surface oxidation. This step is important because there is a risk of surface oxidation when using pure water as a cleaning agent. It is sufficient that the drying device used to carry out this step has the same structure as a baking oven normally used in the manufacturing process of semiconductor devices. It goes without saying that a wafer delivery device is also connected.

After completing the series of steps described above, it is sufficient to proceed to the next normal step in the semiconductor manufacturing process, such as an etching step.

As explained above, according to the present invention, a polycrystalline silicon (Si) layer, a silicon nitride (Si ₃ N ₄ ) layer,
This method is an extremely simple method for removing the protrusions that often occur on the surface of semiconductor device wafers that have been subjected to a vapor-phase growth process such as silicate glass layers, but does not require specially designed and complicated equipment. It is possible to provide a method for flattening the surface of a wafer for a semiconductor device by completely removing it without removing it. By using the present invention, the manufacturing yield of semiconductor devices can be improved, and furthermore, the reliability of semiconductor devices can be improved, which is a very large benefit.

In addition, the anti-friction agent, pressing plate,
It goes without saying that the cleaning agent and the like are merely examples, and can be replaced with other substances having similar functions.

[Brief explanation of drawings]

1 and 2 are sectional views for explaining one embodiment of the present invention. In the figure, 1: wafer for semiconductor device, 2: vapor growth film, 3: anti-friction agent, 4: press plate.

Claims (1)

[Scope of Claims] 1. (a) A step of forming a coating film having a high viscosity by coating on the surface of a semiconductor device wafer provided with a vapor-grown film having protrusions on the surface; (b) The coating a step of pressing a pressing plate having a flat and smooth surface against the surface of the semiconductor device wafer having a thin film layer on its surface to destroy the protrusions; (c) cleaning the surface to remove the destroyed protrusions; 1. A method for planarizing a wafer for semiconductor devices, the method comprising: removing particles.