JPH03110825A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To make it hard to pose the thermal problem such as diffusion, etc., while forming a recrystallized silicon film in excellent crystallinity by a method wherein an underneath film is heattreated so that the crystalline directions may be made even and then the underneath film whereon a polysilicon film is formed at the deposition temperature of 400 deg.C-500 deg.C is heat-treated at the temperature of 800 deg.C-1100 deg.C for a short time not exceeding 30sec. CONSTITUTION:Grooves 3a, 3b are formed respectively in an underneath substrate 1 and an insulating film 4 so that the crystalline directions may be made even. The thermal problem such as diffusion etc., by the heat generated during the deposition process of a polysilicon film 6 can be hardly posed by forming the polysilicon film 6 at the low deposition temperature of 400 deg.C-500 deg.C. Furthermore, since the polysilicon film 6 as it is deposited is in the amorphous state, it is heat-treated at high temperature of 800 deg.C-1100 deg.C for a short time not exceeding 30sec. The recrystallized polysilicon films in excellent crystallinity in even crystalline directions can be formed by the heat treatment at such a high temperature for a short time. Through these procedures, the thermal problem such as diffusion etc., can be hardly posed so that the said recrystallized silicon film in excellent crystallinity as well as even crystalline directions may be formed.

Description

[Detailed Description of the Invention] [Summary] Regarding a semiconductor manufacturing method, it is possible to make it difficult to cause thermal problems such as diffusion, and it is possible to form a recrystallized silicon film with good crystallinity by aligning the crystal orientation. The purpose is to provide a semiconductor manufacturing method, which includes a step of performing treatment to align the crystal orientation of the underlying film;
A step of forming a polysilicon film on the rise of the base at a deposition temperature of 400°C to 500°C, and a step of heat-treating the base film on which the polysilicon film is formed at 800°C to 1100°C for 30 seconds or less. Configure it to include.

[Industrial application field]

The present invention relates to a semiconductor manufacturing method, and can be applied to a technique for forming a recrystallized silicon film in the production of three-dimensional devices. In particular, the present invention relates to a method for forming a recrystallized silicon film with uniform crystal orientation and good crystallinity. The present invention relates to a semiconductor manufacturing method that can be used.

With the integration of semiconductors in recent years, 301 (Silic
There are very high expectations for the structure. A method for forming this SOt structure is called the recrystallization method, in which a laser, electron beam, heater, etc. are used as a light source to heat a polysilicon thin film to melt the silicon and recrystallize it. . A common goal of these methods is to form a recrystallized silicon film with uniform crystal orientation and good crystallinity.

[Conventional technology]

Conventionally, as shown in FIG. 3, in a semiconductor manufacturing method using a Sol structure consisting of an insulating film 32 of 5 in 2 formed on a base substrate 31 of bulk silicon and a polysilicon film 33 formed on the insulating film 32, In order to recrystallize the polysilicon and align the crystal orientation, the insulating film 32 is etched and the base substrate 3 is etched.
1 was exposed and that portion was used as a seed crystal portion 34 to be recrystallized from there. The reason for recrystallizing the polysilicon here is that if the top layer of polysilicon B'J33 is simply deposited, it will be in an amorphous state with varying crystal orientations, and if a three-dimensional device is formed in this state, the device characteristics will vary. It is. Here, the condenser lens 35
The polysilicon film 33 deposited in advance is irradiated with a laser beam 36 to melt it, and the underlying substrate 31 is exposed by utilizing the characteristic that the crystal orientation is aligned in an energetically stable direction when solidified. The seed crystal portion 34 is pulled in the X direction (the direction of growth of the jl crystal) and recrystallized.

In addition, as shown in FIGS. 4(a) and 4(b), Si3N (
The growth direction of recrystallization has been controlled by selectively forming a laser beam antireflection film 38 with directionality, such as a film made of a material such as Sin or 5t3N4.

Here, a laser beam antireflection film 38 is formed to delay crystallization in that portion compared to other portions.

In addition to these methods, there is a method using a recrystallization technique called graphoepitaxy, as shown in FIGS. 5(a) to 5(C). In this method, the underlying insulating film 3
2, and a polysilicon film 3 deposited thereon.
3 is melted using a laser beam or the like. Then, depending on the shape of the groove formed in the base, the polysilicon film 33 thereon can be selectively grown in an energetically stable plane orientation.

In both methods, it is common that the deposited polysilicon film 33 is melted. Further, here, there is no seed crystal portion 34 penetrating the insulating film 32 as shown in FIG.
A groove is formed only in 2.

Specifically, when they are in contact with each other on the (100) plane shown in FIG. 5(a), the (100) direction is aligned as a plane, but it is difficult to align the rotation direction. In order to align this direction of rotation, as shown in Figure 5 (
In b), a rectangular groove is formed in the insulating film 32, and as shown in FIG.
In c), a triangular groove is formed in the insulating film 32. and,
In FIG. 5(b), the upper surface of the polysilicon film 33 is (100
) plane, but in FIG. 5(c), the upper surface of the polysilicon film 33 is a (110) plane.

By controlling the shape of the underlying insulating film 32 in this manner, the plane orientation of the polysilicon film 33 can be made uniform.

[Problem to be solved by the invention]

The deposition temperature of the polysilicon film 33 mentioned above is 600 to 70°C.
Previously, it was performed at a high temperature of 0°C, but as semiconductor processes require lower temperatures, higher integration, and thinner films, polysilicon film 33
It is necessary to keep the deposition temperature low. The reason for the trend toward lower temperatures is that the diffusion layer formed at a predetermined position by ion implantation and annealing is diffused by the subsequent annealing process and the high-temperature heat treatment of the substrate during film deposition. This is because there is a risk that they will not stay in their position. In addition, when carrying out at a high temperature of 600 to 700°C,
Although it is possible to take into account the amount that will spread in advance,
There is also the advantage that such wasteful prospects are eliminated if the process is carried out at low temperatures. Therefore, in order to solve problems such as diffusion,
The polysilicon film 33 is formed at a low deposition temperature of 00 to 500°C.
is known to form. However, if deposited, the crystalline state is amorphous as described above and the crystal grain size is small, so that a device cannot be formed unless recrystallization is performed by some method. The conventional method of melting polysilicon has a problem in that the vicinity of the molten silicon is affected by heat.

Since heat treatment for silicon melting (1415°C or higher) as described above is added for recrystallization to improve crystallinity, even if the polysilicon film 33 is formed at a low temperature of 400 to 500°C, This is because problems such as diffusion may occur after all.

Furthermore, it is extremely difficult to align the crystal orientation over a wide range from a seed crystal portion 34 attached to one location of a polysilicon film 33 as shown in FIG. There was a problem in that it was difficult to form.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a method for manufacturing a semiconductor device, which can make it difficult to cause thermal problems such as diffusion, and can form a recrystallized silicon film with good crystallinity by aligning the crystal orientation. The purpose is

[Means to solve the problem]

In order to achieve the above object, the method for manufacturing a semiconductor device according to the present invention includes a step of performing a treatment to align the crystal orientation of the underlying film, and forming a polysilicon film on the underlying film at a deposition temperature of 400°C to 500°C. The step of forming the polysilicon film and the underlying film on which the polysilicon film is formed are heated at 800°C to 1100°C for 30 minutes.
The method includes a step of performing heat treatment for less than a second.

The base film according to the present invention includes a substrate, a coating such as an insulating film formed on the substrate, or both.

In the present invention, the step of performing treatment to align the crystal orientation of the underlying film refers to a coating such as an insulating film formed on a substrate,
It includes the process of forming grooves such as rectangular grooves and triangular grooves in which the desired surface orientation is the most energetically stable on the substrate, or both. Examples include electron beams, ion beams, and etching solutions.

In the present invention, the upper limit of the deposition temperature of the polysilicon film is set to 5
The reason for setting the temperature at 00℃ is to prevent thermal problems such as diffusion of the pre-formed diffusion layer due to the heat generated when depositing the polysilicon film.If the temperature is higher than 500℃, the pre-formed diffusion layer This is because thermal problems such as diffusion of the diffused layer occur, which is not practical. Further, the lower limit is set at 400° C. because if the temperature is lower than 400° C., it is difficult to form a polysilicon film, which is not preferred in practice.

In the present invention, the lower limit of the heat treatment temperature is set at 800°C because heat treatment at a temperature lower than 800°C for a long time (for example, several hours) has almost no effect on restoring the crystallinity of polysilicon, so it is not practical. This is because it is not desirable,
Further, the reason why the upper limit is set to 1100° C. is because it is difficult to control the time and the diffusion layer is easily diffused, which is not preferred in practice.

In the present invention, the upper limit of the heat treatment time is set to 30 seconds or less because heat treatment at 800°C to 1100°C for longer than 30 seconds has little effect on restoring the crystallinity of polysilicon, and furthermore, diffusion and other This is because problems arise and are not practical.

In the present invention, preferred embodiments of heat treatment conditions that can preferably restore the crystallinity of polysilicon and prevent problems such as diffusion include, for example, heat treatment at 800°C for 30 seconds. , 11
This is a case of heat treatment at 00°C for 5 seconds.

[Effect]

The operation of the method of the present invention will be explained. Polysilicon films deposited at low temperatures are in an amorphous state as they are, but by performing heat treatment at 800 to 1100°C for 30 seconds or less as described above, the crystallinity of polysilicon rapidly changes, although the cause is not necessarily clear. Although the crystal grain size is small (<10 μm), recrystallization occurs and a recrystallized polysilicon film with good crystallinity and uniform crystal orientation is formed.

Note that even if a polysilicon film is formed at a high temperature of 600 to 700° C. and then subjected to high temperature heat treatment for a short time as described above, a recrystallized polysilicon film with good crystallinity cannot be formed. This is thought to be because seed crystals are formed randomly because the polysilicon film is formed at high temperatures, and when heat treatment is applied afterwards, the seed crystals grow abnormally. On the other hand, since seed crystals are not formed when the polysilicon film is formed at a low temperature according to the present invention, the seed crystals will not grow abnormally even if heat treatment is applied thereafter. Further, although the heat treatment temperature of the present invention is high, the time is extremely short, so that the influence of heat on the vicinity of the recrystallization region can be reduced. However, if the underlying film is not processed, the direction of rotation of the crystal grains will be random, as explained with reference to FIG. 5(a).

Therefore, in order to align the plane orientation, the underlying film, for example, the substrate, the insulating film formed on the substrate, or both are processed in advance. When a liquid or solid comes into contact with a different substance, the area near the contact surface is in a higher energy state than the other parts. The surface energy of a solid differs depending on its plane orientation. When rearrangement occurs from the amorphous state through the heat treatment described above, crystallization proceeds in such a way that the planes are oriented in a manner that lowers this energy.

By changing the shape of the groove processed into the underlying film, the most energetically stable surface corresponding to that shape will grow. As this processing means, for example, an electron beam, an ion beam, or an etching liquid may be used.

〔Example〕

Hereinafter, the present invention will be explained based on the drawings.

1 and 2 are diagrams explaining one embodiment of the semiconductor manufacturing method according to the present invention, and FIGS. 1(a) to (f) are diagrams explaining the manufacturing method of one embodiment, and The figure is a diagram illustrating the effects of one embodiment. The illustrated semiconductor manufacturing method is sor
This is a case where it is applied to a semiconductor manufacturing method in a structure.

In these figures, ■ is a base substrate made of, for example, bulk silicon, 2a and 2b are ion beams, 3a and 3b are grooves, and 4 is a substrate made of, for example, 5i02. 5 is an opening, and 6 is a polysilicon film.

Next, the manufacturing method will be explained.

First, using a base substrate 1 made of bulk silicon as shown in FIG. 1(a), ion beam 2a is irradiated onto the base substrate l as shown in FIG. For example, a groove 3a of 0.5 μm is formed.

Next, as shown in FIG. 1(c), SiO2 is deposited by, for example, the CVD method so as to cover the groove 3a, thereby forming an insulating film 4 having a thickness of, for example, 1 μm.

Next, as shown in FIG. 1(d), the insulating film 4 is irradiated with the ion beam 2b to form a groove 3b having the same shape as the groove 3a. At this time, the groove 3b has a width of, for example, 4 μm and a depth of, for example, 0.1 μm.

Next, as shown in FIG. 1(e), the insulating film 4 is selectively etched by, for example, RIE so that the portion of the base substrate l where the groove 3a is formed is exposed, thereby creating an opening 5.
form. At this time, the groove 3a is exposed below the opening 5, and the base substrate 1 is exposed because 5i02 in the groove 3a is also etched.

Next, as shown in FIG. 1 ( ), polysilicon is deposited by CVD, for example, to cover the trenches 3a, 3b and the opening 5 to form a polysilicon film 6.The deposition temperature at this time is Bring to 400-500℃.

The polysilicon film 6 thus formed is in an amorphous state. Next, the base substrate 1 on which the polysilicon film 6 is formed is further annealed by lamp annealing, for example.
A recrystallized silicon film (recrystallized film) can be obtained by heat treatment at 0 to 1100° C. for 5 to 30 seconds.

That is, in the above embodiment, since the grooves 3a and 3b are formed in the base substrate 1 and the insulating film 4 to align the crystal orientation, the rotating direction of the crystal orientation is random as explained in FIG. can be made less likely to occur. And 4
Since the polysilicon film 6 is formed at a low deposition temperature of 00 to 500° C., thermal problems such as diffusion due to heat when depositing the polysilicon film 6 can be made less likely to occur.

Since the polysilicon film 6 here is in an amorphous state as it is deposited, heat treatment is performed at a high temperature of 800 to 1100° C. for a short time of 30 seconds or less. A recrystallized polysilicon film with good crystallinity and uniform crystal orientation can be formed by such heat treatment at a high temperature for a short time. This could be confirmed by observation using a TEM or the like. That is,
In the case of the present invention, crystals were grown in a pattern similar to a dead leaf, and a good recrystallized silicon film was obtained.

In addition, when examined by X-ray diffraction, when a polysilicon film was deposited at the conventional high temperature of 650°C, a donut-shaped pattern A was vaguely formed relative to the central point X1, as shown in Figure 2 (a). On the other hand, in the case of the present invention, which was deposited at 450°C and heat-treated at 1000°C for 10 seconds, it was in an amorphous state and the crystallinity had not recovered.
As shown in b), beak B1,
It was confirmed that B2 and B3 appeared regularly at predetermined positions, the crystal orientation was aligned, and the crystallinity was recovered and good.

In addition, in the case of conventional laser annealing, it took more than 30 minutes to melt the polysilicon film deposited by laser annealing, but in the present invention, the polysilicon film is deposited at a low temperature and requires only a heat treatment of 30 seconds or less. This has a great time saving effect. Moreover, since the present invention uses low-temperature deposition and high-temperature, short-time heat treatment, compared to conventional laser annealing, the influence of heat applied to the surrounding area is less, making it difficult to cause thermal problems such as diffusion. .

Therefore, it is possible to support a device manufacturing process with better controllability.

Note that in the above embodiment, the base substrate 1 and the polysilicon film 6
Although the case has been described in which the application is applied to a semiconductor manufacturing method in an SO1 structure having an insulating film 4 between them, the present invention is not limited to this. The present invention may be applied to a semiconductor manufacturing method having a structure including a deposited polysilicon film 6.

〔Effect of the invention〕

According to the present invention, thermal problems such as diffusion can be made difficult to occur, and a recrystallized silicon film with good crystallinity can be formed by aligning the crystal orientation.

[Brief explanation of drawings]

1 and 2 are diagrams for explaining an embodiment of the semiconductor manufacturing method according to the present invention. FIG. 1 is a diagram for explaining the manufacturing method of the embodiment, and FIG. 3 to 5 are diagrams illustrating a conventional manufacturing method. ...Base substrate, a, 2b...Ion beam, a, 3b...Groove, ...Opening, ...Polysilicon film . A diagram explaining the manufacturing method of the first embodiment.A diagram explaining the manufacturing method of the first embodiment.A diagram explaining the effects of the first embodiment.A diagram explaining the manufacturing method of the conventional example.Diagram 3.Distance Manufacturing the conventional example. Diagram for explaining the method Diagram for explaining the conventional manufacturing method

Claims (1)

[Scope of Claims] A step of performing treatment to align the crystal orientation of a base film, a step of forming a polysilicon film on the base film at a deposition temperature of 400°C to 500°C, and the polysilicon film. The base film on which is formed is heated to 800℃~
A method for manufacturing a semiconductor, comprising the step of performing heat treatment at 1100° C. for 30 seconds or less.