JPH04106954A - Manufacture of semiconductor device using liquid phase cvd method - Google Patents

Abstract

PURPOSE:To prevent a corner part of a substrate from being exposed, by providing a dummy layer which has a low wettability for a reactive species of a liquid phase state, and by performing an embedment. CONSTITUTION:On a semiconductor substrate 1, a film is formed using the material to form a dummy layer, and therein, a trench 2 is formed. Thereby, the dummy layer 4, which has a low wettability for a reactive species of a liquid phase state, is provided on the periphery of a opening 21 of the trench 2. Then, the reactive species is embedded into the trench 2, in the liquid phase state, and is defined as an embedded part 3. Thereafter, the dummy layer 4 is removed by etching, and a embedment structure is obtained. In this case, the embedment is formed, somewhat protruding from the top face of the substrate 1, and therefore, the corner part of the substrate 1 can be prevented from being exposed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor device using a liquid phase CVD method. The present invention can be used, for example, as a technique for forming fine trench isolation for semiconductor devices.

[Summary of the invention]

The invention of claim 1 of the present application provides that when a groove formed in a semiconductor substrate is filled with a reactive species in a liquid phase, the area around the opening of the groove is wettable with respect to the reactive species in a liquid phase. By providing a low dummy layer and removing the vaginal dummy layer after embedding, embedding is performed to at least above the substrate surface.

The invention of claim 2 of the present application embeds a reactive species in a liquid phase in a groove formed in a semiconductor substrate, and, following the embedding, continuously fills a groove formed in a semiconductor substrate with an Ohaag hole, which is a portion where an excess of the reactive species is formed. By etching and hacking the welt portion, the margin for forming the large portion of O-Her Glow is increased, and the portion is removed and heated to prevent condensation.

[Prior Art] Conventionally, in the field of semiconductor device manufacturing, the CVD method has been used to deposit on a substrate by activating reactive species in the gas phase, thereby forming a film or filling trenches. Are known.

In contrast, a technique has been proposed in which similar deposition is performed by bringing the reactive species into a liquid phase. This is called liquid phase CVD method. Placing the reactive species in a liquid phase can be accomplished, for example, by cooling the substrate on which the deposition is to occur to a temperature at which the reactive species liquefies under the atmospheric pressure at which the deposition occurs.

Regarding liquid phase CVD technology, for example, 5i (CH).

A technique for depositing SiO□ using tetramethylsilane (abbreviated as TMS) as a reactive species has been proposed (Extended Abstracts of th
e 19th Conference on 5
olid 5tate Devices and
Materials.

Tokyo, 1987, pp. 451-454 “Liq
uid Phase Oxidation Employ
ing O^toms Produced by
Microwave Dis-charge a
nd 5i (see “CLL”).

Although the effect of liquid phase CVD is not necessarily clear, the above T
Using MS, for example, S is deposited in a trench formed in a silicon substrate.
When forming an iO□ film, the inside of the reaction chamber is set at 1O-5 Torr.
When the pressure is reduced to below and the substrate is cooled to below -23°C, T
The MS condenses into a liquid phase and gradually accumulates from the bottom of the groove. When oxygen atoms excited using, for example, microwaves are supplied to the atmosphere in this state, TMS reacts with the oxygen atoms to form a SiO□ film. This mechanism is not necessarily clear, and TMS is probably converted to SiO□ through an intermediate such as hexamethyldisiloxane (Si (CH3):+)zO, but the oxidation reaction proceeds at least in the liquid phase state. It is estimated that

On the other hand, in the field of semiconductor device manufacturing, with the miniaturization of elements, isolation (separation between elements) has been changed from conventional LOGOS.
Instead, there is a movement toward practical use of trench isolation, especially glossy trench isolation, in which element isolation insulators are buried in trenches.

Trench burying technology is one of the key processes in forming a resilient shallow trench isolation structure. Regarding this, the present inventor has proposed various methods using bias ECRCVD.

Regarding this trench filling technology, the above-mentioned liquid phase CVD
The law is attracting attention. Due to the miniaturization of elements, for example, 6
For example, 0.2 μ of a 4 mega focus class SRAM.
For m-rule trench filling, bias EC
This is difficult to deal with even with the RCVD method; on the other hand, with the liquid phase CVD method, the reactive species is buried in a liquid phase, so even if the aspect ratio of the trench becomes severe, the trench can be buried.

[Problem that the invention seeks to solve]

As mentioned above, in the liquid phase CVD method, reactive species in a liquid state are embedded in the grooves to cause a reaction.
Even fine trenches with a large aspect ratio can be filled well, and can be advantageously used, for example, for forming trench isolation structures.

However, if this is to be put to practical use, there are some specific problems that must be solved in order to achieve good embedding using the liquid phase CVD method.

The first problem is that a part of the corner of the semiconductor substrate is exposed as the reactive species are removed from the overgrowth portion. That is, when filling a trench, in order to ensure uniformity within the trench filling surface using liquid phase CVD, the deposited film should be placed in the trench 2, including the margin, as shown in FIG.
overgrowth (O
νer growth). This is because if a margin is not provided, there may be a portion where the groove 2 is not completely filled in, so it is necessary to form the groove 2 as much as possible beyond the upper surface of the opening. This overgrowth part, which is formed in excess of the margin, is shown in Figure 3 (a).
) is indicated by the reference numeral 32. In the figure, 1 is a substrate, and 3 is a buried portion formed from buried reactive species.

The above-mentioned Oha growth part 32 must be removed,
Etch hacking is generally required. At the time of this etch bank, in order to ensure the uniformity of the etch bank, the margin must be taken into account and the etch bank must be oat 7 inches.

If the etching is not completely removed with sufficient margin, oats will be present on the parts of the substrate 1 that should be exposed other than the grooves 2.
- This is because the growth portion 32 remains and there is a risk that the portion that should be exposed will be covered by this.

When over-etching is performed in this manner, a part of the corner 10 of the substrate 1 comes out as shown in FIG. 3(b). Therefore, if a gate oxide film is formed here,
Problems such as deterioration of withstand voltage occur.

The second problem is that dew condensation may occur. That is, if a material subjected to liquid phase CVD is directly taken out into the atmosphere, there is a problem in that moisture on the surface condenses. This is because liquid CVD is generally performed at low temperatures.

The purpose of the present invention is to solve the above-mentioned various practical problems in liquid phase CVD technology, and the first purpose of the present invention is to prevent part of the corner of the substrate from being exposed as described above, It is an object of the present invention to provide a method for manufacturing a semiconductor device using a liquid phase CVD method that solves the problem associated with partial corner exposure. Liquid phase C solves the problem of dew condensation even when taken out.
An object of the present invention is to provide a method for manufacturing a semiconductor device using the VD method.

(Means for solving the problem) The invention of claim 1 of the present application forms a groove in a semiconductor substrate,
A method for manufacturing a semiconductor device using a liquid phase CVD method comprising a step of filling the trench with a reactive species in a liquid phase, the method comprising: filling the groove with a reactive species in a liquid phase; The method is characterized in that the embedding is performed by providing a dummy layer with low properties.

The invention of claim 2 of the present application forms a groove in a semiconductor substrate,
A method for manufacturing a semiconductor device using a liquid phase CVD method comprising a step of burying the groove with reactive species in a liquid phase state, the method comprising: etch-hacking the overgrowth portion of the reactive species continuously following the embedding. It is characterized by:

In the invention of claim 1 of the present application, the dummy layer refers to a layer that is formed when embedding is performed using reactive species in a liquid phase, and is ultimately removed.

In this invention, the reactive species is embedded so as not to exceed the upper surface of the dummy layer, that is, to about the middle of the dummy layer, and after embedding, the dummy layer is removed so that the layer formed by liquid phase CVD protrudes from the substrate surface. The way to do this is to
This is a preferred embodiment.

In this invention, the dummy layer has low wettability with respect to reactive species in a liquid phase;
This means that the adhesion between the dummy layer and the reactive species in the liquid phase is small. The wettability will be explained with reference to FIGS. 5(a) and 5(b) as follows. In Fig. 5(a), when a liquid is deposited on the surface of the solid S and ~L3 is attached, if the wettability is high (good wettability), the liquid wets the surface of the solid S widely like Ll, and at that time Contact angle θ.

is small. When the wettability is low (wetting property is bad), the adhesion area of the liquid becomes small as shown in L2, and the contact angle θ2 becomes large. When the wettability further decreases, the liquid becomes like L3, and the contact angle θ3 becomes even larger. Regarding burying the groove, if the wettability is high, a meniscus like LI' will form, but if the wettability is low and it is 2', it can be filled almost horizontally, but if the wettability is quite low like L3', a meniscus will form. Although it becomes somewhat convex, it can be embedded well. The wettability should be as low as possible to achieve good and flat embedding, and the preferable wettability varies depending on the material of the dummy layer and the type of liquid-phase CVD material, so it cannot be stated unconditionally, but in general, it is Therefore, the range of 70°<θ<110' is preferable, and it is more preferable that θ is approximately 90°.

The dummy layer can be preferably formed from poly-Si (polysilicon) when forming 5i02 by liquid phase CVD, for example.

In the invention of claim 2 of the present application, it is preferable to provide a stopper layer during the etch bank, and when forming SiO□ by liquid phase CVD, such a stopper layer is made of polysilicon or amorphous silicon. layers can be preferably employed.

In addition, the etch bank is stopped in the middle of this stopper layer, and after the stopper layer is removed, the liquid phase CV of the SiO2 layer, etc.
A preferred embodiment is to make the layer formed by D protrude from the substrate surface.

[Effect]

According to the invention of claim 1 of the present application, a reactive species in a liquid phase is buried in a groove having a dummy layer above the opening and reacted;
Since embedding is achieved, if the dummy layer is removed after removing the overgrowth portion, embedding will be done above the dividing groove of the dummy layer, which will solve the problem of exposing a part of the corner of the substrate. can be avoided. In addition, since the dummy layer has low wettability with respect to the reactive species in the liquid phase,
Flat and good embedding can be achieved.

According to the invention of claim 2 of the present application, the O-Her growth portion is removed by etch hacking, and at the same time, the temperature is raised thereby, and dew condensation can be prevented from occurring even after the film is taken out into the atmosphere.

〔Example〕

Embodiments of each invention of the present application will be described below with reference to the drawings. However, it goes without saying that each invention is not limited to the examples described below.

Example 1 This example applies the invention of claim 1 of the present application to the manufacturing of semiconductor devices, particularly to 64 megabit class SRAMs.
The present invention is applied to the manufacture of ultra-fine and integrated semiconductor integrated circuit devices, and a trench isolation structure is formed according to the present invention.

In this example, a film is formed using a material for forming a dummy layer on a semiconductor substrate l, and grooves 2 are formed in the film by photolithography, as shown in FIG.
As shown in a), a dummy layer 4 having low wettability with respect to reactive species in a liquid phase is provided around the opening 21 of the groove 2 (trench). Next, a reactive species is embedded in the cough groove 2 in a liquid phase,
That is, liquid phase CVD is performed to produce the result as shown in FIG. 1(b).

The embedded part formed from the reactive species in the liquid phase is designated by the symbol 3.
Indicated by At this time, in this embodiment, the reactive species are buried to a depth of about the middle of the dummy layer 4, as shown in the figure, to form the buried portion 3. After that, the dummy layer 4 is removed by etching.
The embedded structure shown in FIG. 1(C) is obtained. In this example, as shown in the figure, the embedding is formed to slightly protrude from the top surface of the substrate 1,
Part of the corner of the substrate 1 is prevented from coming out.

More specifically, in this embodiment, a silicon substrate 1 is used as the semiconductor substrate 1, and SiO□ is formed by liquid phase CVD and is embedded.

In this example, a dummy layer is provided on the substrate 1 using a material such as poly-Si that has low wettability to SiO□.
For example, a groove 2 (trench) with a film thickness of 1,100 mm) and a width of 0.2 μm is formed using lithography and dry etching (the depth of the groove 2 is, for example, 1 μm).

As a result, the structure shown in FIG. 1(a) is obtained.

Next, this groove 2 is filled using a liquid phase CVD method. At this time, a time is set in advance so that the reaction occurs exactly between the poly S1 layers, which are the dummy layers 4.

As a result, the structure shown in FIG. 1(b) is obtained.

Specifically, as a liquid phase CVD method for forming 5rOz, a method can be used in which, for example, tetramethylsilane is used, it is buried in the groove 2 in a liquid phase state, and reacted to form Sin. .

Next, the poly-Si layer which is the dummy layer 4 is removed using a KOH solution or the like. As a result, the structure shown in FIG. 1(C) can be obtained. That is, if this is done, the SiO□ layer, which is the buried portion 3, will necessarily protrude, so that the substrate 1 as described above
Exposure of the corner of the gate is avoided, and even if a gate oxide film is formed here, there will be no problem of deterioration of breakdown voltage.

According to this embodiment, since the embedded SiO□ protrudes,
The corners of the substrate 1 do not appear, and when the silicon surface of the substrate 1 is subsequently oxidized, the breakdown voltage of the oxide film does not deteriorate.

In addition, by using the dummy layer 4 with low wettability, the fourth
As shown in Figure (A), the shape of the embedded 5in2 can be improved. If the wettability is high, a meniscus is formed as shown in Figure 4 (B), whereas in this example, a meniscus is formed as shown in Figure 4 (A).
It is possible to achieve embedding with a good shape such as.

Example 2 This example embodies the invention of claim 2 of the present application, and the present invention is applied to the formation of a trench isolation structure during the manufacture of a miniaturized semiconductor device similar to Example 1. It is the embodiment of

In this embodiment as well, SiO2 is placed in the groove 2 formed in the silicon substrate 1.
□ is configured to be embedded by liquid phase CVD method.

In this embodiment, S is formed on the substrate 1 by liquid phase CVD.
An etching stopper layer 5 is provided as a stopper during etching of iO□, and a groove 2 (trench) is formed in this layer by photolithography as shown in FIG. 2(a). The reactive species of the state are embedded in an overgrowth manner that includes the margin, resulting in the structure shown in FIG. 2(b). Continuing with the above steps, the overgrowth portion 32 is then removed by etching to form the structure shown in FIG. 2(c).

The etching stop layer 5 is removed to obtain the structure shown in FIG. 2(d).

More specifically, in this embodiment, an etching stop layer 5 such as polysilicon is formed on a silicon substrate 1.
Using lithography and dry etching, the desired groove 2 (
trench). As a result, the structure shown in FIG. 2(a) is obtained.

Next, process 2 (trench) by liquid phase CVD, for example, Si.
Embed n. This specific method can be used, for example, in Examples to 1.
The one explained in can be used.

Next, in this embodiment, the above structure is etched in an etch bank chamber that is continuously provided through a gate valve. For example, perform etch banking under the following conditions.

Gas system used: CHF5=50SCCM pressure 2Pa HF electric 0.23W/all Under these conditions, if the etch stop layer 5 is made of polysilicon, for example, etch hacking can be performed with a sufficient selectivity. Furthermore, the end point of the etch bank can be determined by monitoring the light emission of SiF.
Needless to say, the temperature has risen sufficiently due to heating by the plasma, and dew condensation can be prevented.

Next, the etching stop layer 5 made of polysilicon or the like is removed using a KOH aqueous solution or the like. This results in Figure 2 (
The structure d) is obtained. According to this embodiment, the formed SiO□ has a protruding shape, so that the problem of breakdown voltage deterioration caused by the first problem mentioned above does not occur.

According to this embodiment, since the excess SiO□ which is the overgrowth portion 32 is removed following the deposition by liquid phase CVD, there is no problem even if the overgrowth is performed by liquid phase CVD with a sufficient margin. Therefore, liquid phase CVD can be performed with sufficient margin. Gah, that Oha growth part 32
When removing the etchant, the etch bank also serves as a heating device to prevent dew condensation.

Furthermore, in this example, since SiO2 is removed in the etch bank and the etching stop layer 5 is provided, the margin of the etch bank is wide, and the SiO□
Since the layers can be made to protrude, protrusion of the corners of the substrate 1 can be avoided, and problems caused by this can also be prevented.

Furthermore, throughput can be improved by using continuous multi-chambers.

〔Effect of the invention〕

As described above, according to the invention of claim 1 of the present application, there is provided a semiconductor device using a liquid phase CVD method, which prevents part of the corner of the substrate from being exposed and solves the problems associated with part of the corner being exposed. According to the invention of claim 2, there is provided a manufacturing method for a semiconductor device using a liquid phase CVD method, which solves the problem of condensation even when taken out into the atmosphere after performing liquid phase CVD. We can provide manufacturing methods, both of which are liquid phase CVD.
It solves the practical problems of the technology.

[Brief explanation of the drawing]

Figures 1 (a) to (C) and Figures 2 (a) to (d) are
The steps of Example-1 and Example-2 are sequentially shown in cross-sectional views of the material to be deposited. FIGS. 3(a) and 3(b) are diagrams showing problems. Figure 4 (A) and (B) are Example-1
FIG. FIG. 5 is an explanatory diagram of wettability. ■...Semiconductor substrate, 2...Groove (trench), 3...
- Embedded part, 4... dummy layer. Problem voice, Σ diagram W diagram 3 洟゛Glossy-2 artificial shin Figure 2 (A) Large Z leaf i1 tally 1σ) 1 4th (B) π for n S E1 month Ea diagram

Claims (1)

[Scope of Claims] 1. A method for manufacturing a semiconductor device using a liquid phase CVD method comprising the steps of forming a groove in a semiconductor substrate and filling the groove with a reactive species in a liquid phase, the method comprising: A method of manufacturing a semiconductor device using a liquid phase CVD method, characterized in that a dummy layer having low wettability with respect to the reactive species in a liquid phase is provided around the opening and the filling is performed. 2. A method for manufacturing a semiconductor device using a liquid phase CVD method comprising the steps of forming a groove in a semiconductor substrate and burying a reactive species in a liquid phase in the groove, following the embedding,
A method for manufacturing a semiconductor device using a liquid phase CVD method, characterized in that an overgrowth portion of a reactive species is continuously etched back.