JPH01138749A - Manufacturing method of semiconductor device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] Among the methods for manufacturing semiconductor devices, in particular, the method for forming element isolation bands on SOt structure silicon substrates is concerned with forming element isolation bands with minute widths to achieve high integration of IC devices. In a method for forming an isolation band of a silicon layer provided on an insulating substrate, a shielding mask is provided, and approximately half the film thickness of the exposed portion of the silicon layer is etched away to form a groove, and then a trench is formed. , the method is characterized in that oxygen ions are implanted into the groove portion while the shielding mask is left as is, and a heat treatment is performed to form an element isolation band made of a silicon oxide film produced by the treatment.

[Industrial Application Field] The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of forming an isolation band on a Sol structure silicon substrate.

Recently, S OI (Silicon On In5u
A method for forming a crystal substrate in which a non-single crystal semiconductor layer is recrystallized by irradiating a beam is known. This is intended to increase the integration and performance of conventional planar devices by arranging them into three-dimensional devices.

However, the SoL created by such Sol technology
It is extremely important for high integration to provide an element isolation band as narrow as possible on the substrate.

[Problems to be solved by conventional technology and invention] Now,
The Sol technology involves injecting oxygen deeply into the silicon substrate with high energy and then heat-treating (annealing) the buried 5i02.
The SIMOX method, which forms a (silicon oxide) film, and the FIPO8 method, which selectively makes a silicon substrate porous by anodization and oxidizes it, are known, but the most suitable method for three-dimensional devices is the stacking process of semiconductor elements. This is a deposited layer recrystallization method in which a non-single crystalline silicon layer deposited on an insulating substrate is recrystallized by beam irradiation or lamp irradiation due to its ease of use.

For example, using a continuous wave argon laser as the beam,
A method is used to recrystallize a polycrystalline silicon film or an amorphous silicon film (non-monocrystalline silicon layer).The feature of this method is that the silicon layer is melted once by irradiation with a beam, and then crystals grow when the silicon layer is cooled. Each time a single crystal is grown. To explain the method of forming the general SOI structure silicon substrate, Fig. 2 (al to (C)
A cross-sectional view of the process is shown in the figure.

FIG. 2 (see al; the surface of a silicon substrate 1 is thermally oxidized to form a 5i02 film 2 with a thickness of about 1 μm, making it an insulating substrate.

See Figure 2(b); then chemical vapor deposition (
A polycrystalline silicon layer 3' having a thickness of approximately 5,000 wafers is deposited by the CVD method.

FIG. 2 (see C1; next, the polycrystalline silicon layer 3° is irradiated with a continuous wave argon laser beam, and is scanned to transform it into a single crystalline silicon layer 3. At that time,
When scanning with a continuous argon laser (CW-^rLaser) beam, the polycrystalline silicon layer 3° is heated and melted,
It is transformed into a single crystal silicon layer 3 during solidification, but the laser annealing conditions are set to a laser spot diameter of 330-1O0pφ,
If the insulating substrate is heated to a temperature of 200 to 500°C with a laser output of 10 to 20 watts and a scanning speed of about 5 to 10 cm/sec, the melt width of the silicon layer will be about several tens of μm, and it will become a single crystal during solidification. Ru.

However, at this time, it is important that the molten silicon layer cools from the center of the melt width to form a nucleus in the center, and from that nucleus, the solidification gradually spreads to the surrounding areas and crystals grow, making the whole into a single crystal. Therefore, although not shown in Fig. 2, an antireflection film (for example, Si3N4 film) is coated on both sides of the laser scanning line and both sides are melted at a high temperature so that solidification starts from the center of the scanning line. The laser beam is a circular spot, and its energy distribution is normally Gaussian, but there are methods such as changing the beam shape and making it donut-shaped so that the energy at the center of the beam is lower than the surrounding area. is taken.

When creating an integrated circuit (IC) device on the silicon substrate having the Sol structure formed in this manner, it is necessary to form an element isolation band for electrically isolating the elements. As a method for forming this element isolation band, for example,
Conventionally, pn junction isolation has been used, but sufficient dielectric strength cannot be obtained unless the pn junction isolation is formed with a width of about 3 μm using a 5V power supply. On the other hand, 5i0
Insulating film isolation, such as a 2 (silicon oxide) film, allows for even higher integration by narrowing the width of the separation band, so insulating film isolation has recently been carried out.

This conventional method of forming device isolation bands using an insulating film is shown in the step-by-step cross-sectional views of FIGS. 3(a) to 3(C). Si
A protective film 13 made of an O2 film/Si3 N4 (silicon nitride) film is selectively formed to expose only the isolation band forming region.

Refer to FIG. 3(b); Next, after removing the device isolation band forming region from the surface by etching approximately 2,000 layers, the exposed single crystal silicon layer 12 is oxidized by heat treatment at 900° C. for 200 minutes in a wet oxygen atmosphere. , a SiO□ film 14 is formed to serve as an element isolation band.

See Figure 3(C): Next, 5i02 film/Si3 N4
The protective film 13 made of a film is removed.

By doing so, an element isolation band made of the 5i02 film 14 is formed, and this forming method is a very famous method called the LOCO3 method.

However, in this LOCO3 method, the oxidation of silicon proceeds simultaneously in both the vertical and horizontal directions.
For a single crystal silicon layer with a thickness of 5000, the minimum width is 0.
．． The SiO3 film has a thickness of 5 μm, and it is difficult to form an element isolation band narrower than that.

On the other hand, since the electric field strength of the 5i02 film is 50V or more at the thickness of Q, lmerrn, it is sufficient for devices driven by a 5V power source to have a width of the device isolation band made of the SiO□ film of about 0.1 μm. A high dielectric strength voltage can be obtained.

Therefore, the present invention proposes a manufacturing method for the purpose of highly integrating an IC by forming an element isolation band made of a SiO3 film with a width even smaller than the element isolation band formed by the LOCOS method. .

[Means for Solving the Problems] The purpose is to provide a shielding mask, remove approximately half the thickness of the exposed portion of the silicon layer to form a groove, and then leave the shielding mask as it is. This is achieved by a method of manufacturing a semiconductor device in which oxygen ions are implanted into the groove portion, heat treatment is performed, and an isolation band made of a silicon oxide film produced by the treatment is formed.

[Operation] That is, in the present invention, a shielding mask is provided in a region of a silicon layer provided on an insulating substrate where an element isolation band is to be formed, and approximately half of the film thickness of the exposed portion of the silicon layer is etched away, and the shielding mask is removed. Oxygen ions are implanted into the lower layer of the groove while the groove is left in place, and heat treatment is performed. Then, a 5i02 film is generated in the groove, and an element isolation zone filled with the SiO2 film is formed. Moreover, the width is regulated by the etching width and is 0.1
An element isolation band with a minute width of about μm can be formed.

[Example] Hereinafter, embodiments will be described in detail with reference to the drawings.

FIG. 1 (al to (dl) are sectional views in the order of steps of a method for forming an isolation band according to the present invention.

Refer to FIG. 1(a); First, a polycrystalline silicon film with a thickness of 5,000 wafers is grown on an insulating substrate 11 in which an insulating film is formed on a silicon substrate, and a monocrystalline silicon layer is formed by laser annealing with a continuous argon laser. Transforms into 12.

Refer to FIG. 1(b); Next, a protective film 15 (shielding mask) made of a 5i02 film/Si3N4 film, etc. is coated to expose only the device isolation band forming region with a width of 0°1 μm, and then a fluorine-based reactive gas is applied. Active ion etching (RI)
E) to form a single crystal silicon layer 12 by 2,500 people (
Etch to a depth of about half the thickness, and a width of 0.1
A groove portion 16 having a thickness of 0.25 μm and a depth of 0.25 μm is formed.

See Figure 1(e); Next, the entire substrate is heated to 600°C, and the oxygen ion beam is accelerated to 100 eV.
.

Inject into the groove 16 at a dose of 2.2 x 10/cat. Note that this oxygen ion is implanted with the protective film 15 provided.

See Figure 1(d); then in a nitrogen atmosphere
When heat-treated at 00 to 1400°C for 30 minutes, the lower layer of the groove is oxidized to become the 5iO7 film 17, and the 5i02 film 1
7, the volume has expanded to almost double, the groove is buried, and the width is 0.1
An element isolation zone made of a minute S i 02 film 17 of μm size is formed. At this time, if oxygen ions are implanted into the groove,
The oxygen ion concentration is high in the center and gradually becomes lower at the periphery, forming a mountain-shaped distribution, but when heat-treated to high temperatures, the oxygen in the high-concentration areas diffuses laterally, and the low-concentration areas attract oxygen to the high-concentration areas. As a result of the movement, the 5i02 film is shaped to match the shape of the groove.

Therefore, according to the manufacturing method according to the present invention, the conventional width is 0.
．． It is possible to form an element isolation band whose width is smaller than 5 μm to about 0.1 μm. Note that instead of the above method, it is also possible to remove the entire thickness of the single-crystal silicon layer 12 to form a groove, and bury an insulating film in the groove by vapor phase growth. Width 0.1μ
It is difficult to completely bury a groove of about 1 m in length. Therefore, the forming method according to the present invention is most suitable.

[Effects of the Invention] As is clear from the above description, according to the present invention, it is possible to form an IC device having an element isolation band with a width as small as 115 mm compared to the conventional device, and its RJn can be increased.

This greatly contributes to higher performance.

[Brief explanation of the drawing]

FIG. 1 (al to (dl) are step-by-step sectional views of the forming method according to the present invention, FIG. 2 (a) to (C) are step-by-step sectional views of the forming method of the So ) to (C) are step-by-step sectional views of the conventional forming method. In the figures, U is an insulating substrate, 12 is a single crystal silicon layer, 15 is a protective film (shielding mask), 16 is a groove, and 17 is a 5i02 film. (Element separation band) Misfire θ small: ?・P-3 type 8゛ method energy presentation 1 Figure 2 of inclined surface

Claims (1)

[Claims] In a method for forming an isolation band of a silicon layer provided on an insulating substrate, a shielding mask is provided and approximately half the film thickness of the exposed portion of the silicon layer is etched away to form a groove portion;
Next, oxygen ions are implanted into the groove portion with the shielding mask left as is, and heat treatment is performed to form an element isolation band made of a silicon oxide film produced by the treatment. manufacturing method.