JPH0444322A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To certainly rinse the interior of a trench groove to improve quality and yield of a semiconductor element by forming the trench groove on a silicon substrate, then immersing the substrate into a cleaning solution under the reduced pressure and returning the environment to the atmospheric pressure or further rinsing the interior under the increased pressure. CONSTITUTION:A silicon substrate 2 on which a trench groove 3 is formed is placed within a chamber 1 and the chamber 1 is then hermetically sealed. Thereafter, the air in the chamber 1 is evacuated using a reduction pump from a reduction port 4. After the pressure is sufficiently reduced, pure water or cleaning solution is supplied from a supply port 5. After that the environment resumes the atmospheric pressure, and cleaning is carried out. In this case, the higher the vacuum degree the deeper the cleaning solution enters into the trench groove 3. Otherwise, after the pressure is reduced, the substrate is immersed into the cleaning solution. The interior of chamber 1 is made to have the atmospheric pressure again and the pressure is increased. Under this pressure condition, cleaning of the silicon substrate may be conducted.

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 an improvement in a cleaning process after a process of forming trenches in a silicon substrate.

[Conventional technology]

In a semiconductor device manufacturing method that includes a step of forming trenches in a silicon substrate, cleaning treatment is usually performed under normal pressure (atmospheric pressure).

That is, normally, a mask such as a resist is formed on the surface of the silicon substrate except for a part thereof, and a trench groove of a predetermined depth is formed in the silicon substrate by wet etching or dry etching. After removing the mask, as shown in FIG. 2, the silicon substrate 2 with trench grooves 3 formed thereon is immersed in pure water or cleaning solution 5 contained in a cleaning tank I at atmospheric pressure to clean the silicon substrate 2. The surface and the inside of the trench groove 3 are cleaned.

-C-wise, a trench groove of several μmφ to several hundred μmφ (or several μm opening to several hundred μm opening) is formed at a predetermined position on a silicon substrate using well-known photolithography technology, and then the trench groove is formed on the silicon substrate surface. A cleaning process is performed such as etching the formed natural oxide film and cleaning the inside of the trench with pure water.

[Problems to be Solved by the Invention] By the way, since the aspect ratio (depth/groove width) of the trench groove is relatively large, it is difficult for the cleaning liquid to enter the inside of the trench groove in the above-mentioned cleaning process. In particular, if foreign matter enters the trench groove, it may lead to a deterioration in the quality of the semiconductor device to be manufactured, so it is desirable that the cleaning liquid completely enters the trench groove.

However, due to the effect of the surface tension of the cleaning liquid, it was found that although it entered a little, it was not completely filled.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for manufacturing a semiconductor device that can reliably clean the inside of a trench groove.

[Means to solve the problem]

In the method for manufacturing a semiconductor device of the present invention, after a trench is formed in a silicon substrate, the trench and the surface of the silicon substrate are immersed in a cleaning solution under reduced pressure, and the atmosphere is returned to atmospheric pressure for cleaning. It is equipped with a process.

The method for manufacturing a semiconductor device according to the present invention includes, instead of the above-mentioned cleaning step, a pressure cleaning step in which the silicon substrate is immersed in a cleaning solution in a reduced pressure atmosphere, the atmosphere is returned to atmospheric pressure, and then further pressure is applied for cleaning. It is something that

[Effect]

In this invention, after the silicon substrate is immersed in the cleaning liquid under reduced pressure in the cleaning process, the atmosphere is returned to atmospheric pressure, so the cleaning liquid enters the trench groove due to the pressure difference, and the silicon substrate is immersed in the cleaning liquid under reduced pressure. The inside can be cleaned reliably.

In this invention, the silicon substrate is immersed in a cleaning solution in a reduced pressure atmosphere, and after the atmosphere is returned to atmospheric pressure, the cleaning is further applied under pressure, making it possible to clean deeper trench grooves.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram for explaining a method for manufacturing a semiconductor device according to an embodiment of the present invention. In the diagram, 1 is a chamber, 2 is a silicon substrate disposed in the chamber 1, and 3 is the silicon substrate. 2 is a trench groove formed in the chamber 1;
is the water inlet.

Next, the manufacturing method will be explained.

A silicon substrate 2 on which a trench groove 3 is formed is placed in a chamber 1, and the chamber 1 is sealed. after that,
The air inside the chamber 1 is released from the vacuum port 4 using a vacuum pump. After sufficiently reducing the pressure, pure water or cleaning liquid is poured from the water supply port 5. Water supply is continued until the silicon substrate 2 is sufficiently immersed.

Afterwards, the pressure is returned to atmospheric pressure and cleaning is performed. In this case, the cleaning liquid enters deeper into the trench groove 3 when the degree of vacuum is better.

To explain the reason for this, when the trench groove 3 is immersed in the cleaning liquid, the entrance of the trench groove 3 is blocked by the liquid level. In other words, bubbles are generated within the trench groove 3. These bubbles prevent the cleaning liquid from entering the trench. Therefore, by changing the pressure from reduced pressure to atmospheric pressure and using a pressure difference, the volume of the bubbles left in the trench groove 3 is caused to shrink. In other words,
If the pressure inside the trench 3 is reduced, the trench is immersed in a cleaning solution, the surface of the trench 3 is covered with the surface of the cleaning solution, and the atmosphere is then returned to atmospheric pressure, due to the pressure difference (Boyle's law), The liquid level will penetrate deep into the trench groove 3.

In this example, after the silicon substrate is immersed in the cleaning solution under reduced pressure, the atmosphere is returned to atmospheric pressure, so the cleaning solution enters the trench due to the pressure difference, and the inside of the trench is can be cleaned reliably. As a result, it is possible to form, for example, a film constituting a capacitor or the like in a high-quality state within the trench groove, which has the effect of improving the quality yield of semiconductor elements to be manufactured.

In this example, after depressurizing, the chamber 1 is immersed in a cleaning liquid, the atmosphere is returned to atmospheric pressure, and cleaning is performed at atmospheric pressure. The silicon substrate may be cleaned under pressure.

FIG. 3 shows a second embodiment of the present invention having such a configuration, and the difference from the embodiment shown in FIG. Pressure port) 1
4 has been set up.

Other details are exactly the same as in Figure 1. In this case, since the cleaning is performed twice under pressure, the cleaning liquid penetrates deeper into the trench grooves because the pressure difference from reduced pressure to increased pressure is large, making it possible to clean deeper trench grooves 3.

〔Effect of the invention〕

As described above, according to the present invention, after a trench groove is formed in a silicon substrate, the trench groove and the surface of the silicon substrate are immersed in a cleaning solution under reduced pressure, and the atmosphere is returned to atmospheric pressure for cleaning. This allows the cleaning solution to penetrate deep into the trench, making it possible to reliably clean the inside of the trench under appropriate processing conditions, improving the quality of the semiconductor devices to be manufactured.

This has the effect of improving yield.

In addition, according to this invention, the silicon substrate is immersed in a cleaning solution in a reduced pressure atmosphere, and after the atmosphere is returned to atmospheric pressure, further pressure is applied for cleaning, making it possible to clean deeper trenches and increase the amount of cleaning done. This type of semiconductor device can be cleaned.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram for explaining a method of manufacturing a semiconductor device according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing a conventional method of manufacturing a semiconductor device, and FIG. FIG. 3 is a schematic diagram for explaining a method of manufacturing a semiconductor device according to an embodiment of the present invention. In the figure, 1 is a chamber, 2 is a silicon substrate, 3 is a trench, 4 is a pressure reduction port, 5 is a water supply port, and 14 is a pressure reduction and pressurization port. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (2)

[Claims] (1) A method for manufacturing a semiconductor device including a first step of forming a trench in a silicon substrate and a second step of cleaning the trench and the surface of the silicon substrate, wherein the second step includes: A method for manufacturing a semiconductor device, characterized in that the cleaning step includes immersing it in a cleaning solution in a reduced pressure atmosphere, and then returning the atmosphere to atmospheric pressure for cleaning. (2) In the method for manufacturing a semiconductor device according to claim 1, in the second step, instead of the cleaning step, the silicon substrate is immersed in a cleaning solution in a reduced pressure atmosphere, and after the atmosphere is returned to atmospheric pressure, the silicon substrate is further heated. A method for manufacturing a semiconductor device, characterized by using a pressure cleaning process in which cleaning is performed under pressure.