JPH04314327A - Method and apparatus for manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To improve the film uniformity of a silicon layer which is formed by cooling and solidifying melted silicon dropped onto a semiconductor substrate. CONSTITUTION:While melted silicon 19 is dropped, the surface of a poly- crystalline silicon layer 6 formed by dropping is melted by a heat source such as a lamp to form a melted silicon layer 20. The heat source such as a lamp is attached to a melted silicon dropping apparatus (spray apparatus).

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for manufacturing a semiconductor element, in which molten silicon is dropped onto a semiconductor substrate and then cooled and solidified to form a silicon layer.

0002

[Prior Art] Conventionally, as a manufacturing method of this type, there is a method called a spray method.
It is disclosed in the publication No. 1, and is shown in FIGS. 3 and 4,
This will be explained below.

FIG. 4 shows a manufacturing method for forming a dielectric isolation substrate using a spray method.

First, as shown in FIG. 3(a), SiO2 is deposited on one main surface of a semiconductor substrate 1 having a (100) plane orientation.
A film 2 is formed, and a desired pattern is subjected to a normal photolithography/etching (hereinafter referred to as photolithography) process to form openings 3.

Next, as shown in FIG. 3(b), the Si
Using the O2 film 2 as a mask, perform anisotropic etching to form a V-shaped groove 4.
form.

Next, as shown in FIG. 3(c), the Si
After removing the entire O2 film 2, Si is deposited on the entire surface of one main surface.
An O2 film 5 is formed. Note that in order to improve wettability with molten silicon, which will be described later, on this SiO2 film 5,
A polycrystalline silicon film may also be formed. Next, the Si
Molten silicon is dropped onto the O2 film 5 and cooled and solidified to form a polycrystalline silicon layer 6 with a thickness of approximately 500 μm. As shown in FIG. 4, the spray device 10 used at this time has a melting tank 12 disposed on the upper side, which is entirely placed inside an inert gas atmosphere 11, and has a nozzle 12a at its lower end. The polycrystalline silicon 13 housed in the melting tank 12 can be heated and melted by a first heating source 14 such as a high-frequency heating coil on the side. A pressurized inert gas 15 is applied, and polycrystalline silicon melted by the pressurization is injected downward from the nozzle 12a.

Further, the apparatus 10 is provided with a turntable 17 which is also located in an inert gas atmosphere 11 and can be heated by a second heating source 16 directly below the melting tank 12. The substrate plate 17a in the state
The semiconductor substrate A is placed on the rotation axis thereof.

Therefore, in order to form the polycrystalline silicon layer 6 using the spray device 10, the semiconductor substrate A is placed in the center of the substrate plate 17a as described above, and it is heated to the second heating source 1.
The polycrystalline silicon 13 in the melting tank 12 is heated to 1,100 to 1,200°C by the first heat source 14 to 1,100 to 1,200°C, and the turntable 17 is rotated to melt the polycrystalline silicon 13 at about 1,400°C using the first heating source 14. Molten silicon having a particle diameter of several tens of micrometers to several hundred micrometers is injected from the nozzle 12a by the gas 15, and is thereby sprayed onto the rotating semiconductor substrate A. By this method, a polycrystalline silicon layer 6 having a thickness of approximately 500 μm is formed in several minutes.

Next, as shown in FIG. 3(c), after grinding the surface of the polycrystalline silicon layer 6 to a flat processing reference surface 7,
By removing the back side of the semiconductor substrate 1 by grinding and polishing until the tips of the V-shaped grooves 4 are exposed, a dielectric isolation substrate having so-called islands (single crystal islands) 8 is obtained as shown in FIG. 3(d). can get.

0010

However, in the method for forming a polycrystalline silicon layer using the spray method described above, the particle size of the dropped molten silicon is small, ranging from several tens of μm to several hundred μm, so the heat capacity is small; In addition, since it is sprayed under pressure by the pressurized inert gas, it adheres to the semiconductor substrate with considerable force. For this reason, the dropped molten silicon adheres to the semiconductor substrate, spreads due to the force of the adhesion, and is immediately cooled and solidified, so even if the turntable is rotated, the dropped molten silicon does not spread on the semiconductor substrate. Therefore, the state of dispersion greatly influences the thickness of the polycrystalline silicon layer. Furthermore, since the viscosity of the dropped molten silicon is high, it is difficult to make the particle size uniform, which further deteriorates the film uniformity of the polycrystalline silicon layer. Since the film uniformity of the polycrystalline silicon layer is closely affected by the warpage of the semiconductor substrate, conventional methods with poor film uniformity have the problem of increasing the warpage of the semiconductor substrate. This warpage of the semiconductor substrate may cause troubles in the device or deteriorate the device characteristics in the subsequent step of forming the semiconductor device.

[0011] Further, the V-shaped groove 4 has a depth of 20 to 100 μm.
, the width is small, 30 to 150 μm, so as shown in FIG.
When deposited, the molten silicon formed on the SiO2 film 5 does not spread within the V-shaped groove, and the number of times of adhesion is small. There was also the problem that unfilled portions 10 were left unfilled. This unfilled portion 10 is formed when the back surface of the semiconductor substrate is ground and polished to expose the tip of the groove, especially in the deep part of the V-shaped groove (see FIG. 5).
As shown in b), a depression 11 appears on the substrate surface. This causes disconnection of the wiring formed in a later process.

[0012] The present invention provides a method for manufacturing a semiconductor device that reduces the occurrence of warpage of a semiconductor substrate and unfilled portions of V-grooves caused by the poor film uniformity of the polycrystalline silicon layer described above. With the goal.

[0013]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention, in a method of manufacturing a semiconductor device, uses a polycrystalline silicon layer that is dropped when spraying molten silicon onto a semiconductor substrate to form a polycrystalline silicon layer. The surface of the silicon layer is irradiated with a tungsten halogen lamp to melt it.
A layer of molten silicon was formed. The semiconductor substrate is rotated in this molten silicon state, and the centrifugal force spreads the molten silicon on the semiconductor substrate and then solidifies it, thereby forming a polycrystalline silicon layer with good in-plane distribution.

Furthermore, as a method for effectively carrying out the above manufacturing method, an apparatus for dropping molten silicon in a spray form is used.
A tungsten halogen lamp is arranged to simultaneously drip molten silicon and melt the polycrystalline silicon layer by lamp irradiation.

[0015]

[Operation] As explained in the previous section, when forming a polycrystalline silicon layer, the surface of the deposited polycrystalline silicon layer is always kept in a molten state, so the molten silicon layer
A uniform distribution can be obtained by spreading over the semiconductor substrate. For this reason, the thickness distribution of the formed polycrystalline silicon layer is improved compared to the conventional one, and the warpage of the semiconductor substrate and the unfilled portion of the V-groove caused by the thickness distribution of the polycrystalline silicon layer are reduced compared to the conventional one. can do.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a manufacturing method for forming a dielectric isolation substrate as a first embodiment of the present invention.

First, as shown in FIG. 1(a), a SiO2 film 2 is formed on one main surface of a semiconductor substrate 1 having a (100) plane orientation, as in the conventional case, and a desired pattern is formed using normal photolithography. - Perform an etching process to form the opening 3.

Next, as shown in FIG. 1(b), the Si
Using the O2 film 2 as a mask, anisotropic etching is performed using, for example, an alkaline etching solution to form the V-shaped groove 4.

Next, as shown in FIG. 1(c), the Si
The O2 film 2 is completely removed, and a SiO2 film 5 is formed as an insulating film over the entire surface of one main surface.

Next, molten silicon 19 is sprayed onto the SiO2 film 5 to form a polycrystalline silicon layer with a thickness of about 500 μm. For example, the spray device 10 used at this time may be the device shown in FIG. use

As shown in FIG. 2, a first heat source 14 and a melting tank 12 for melting polycrystalline silicon, a second heat source 16 for heating a semiconductor substrate, and a semiconductor substrate A are mounted as in the conventional case.
A device consisting of a rotating turntable 17, etc.,
A tungsten halogen lamp 18 is arranged as a third heat source capable of melting several tens of micrometers of the surface of the polycrystalline silicon layer dropped onto the semiconductor substrate A at the same time as the molten silicon 19 is dropped.

Using this spray device 10, FIG.
), the semiconductor substrate A is heated to about 1300° C., and the dropped molten silicon 19 melted to about 1400° C. is dripped onto the semiconductor substrate A in the form of a spray. At this time, at the same time as the dropping starts, power of about 80 kW is continuously applied to the lamp 18, for example, to constantly melt several tens of micrometers of the surface of the deposited solidified polycrystalline silicon layer 6, thereby forming a molten silicon layer 20. In this way, the dropped molten silicon 19 is taken into the molten silicon layer 20. Furthermore, since the thickness of the molten silicon layer 20 is determined by the irradiation conditions of the lamp 18, the thickness increased by the dropped molten silicon 19 is the thickness of the solidified polycrystalline silicon layer 6.
and solidifies at the interface between the molten silicon layer 20 and the molten silicon layer 20. This process is repeated to form a solidified polycrystalline silicon layer 6 and a molten silicon layer 20.
When the thickness of the molten silicon 1 becomes about 500 μm,
9 is stopped, the irradiation of the lamp 18 is stopped, and the molten silicon layer 20 is solidified.

Next, as shown in FIG. 1(d), after the surface of the solidified polycrystalline silicon layer 21 is ground to a flat processing reference surface 7, the tip of the V-shaped groove 4 is formed on the back side of the semiconductor substrate 1. Figure 1 (
Using the solidified polycrystalline silicon layer 21 shown in e) as a support substrate, a dielectric isolation substrate consisting of a large number of islands 8 separated by SiO2 films 5 is obtained.

In the first embodiment, when forming the polycrystalline silicon layer by the spray method, the lamp was irradiated at the same time as the dropping of molten silicon started, but the molten silicon was dropped so as not to melt the semiconductor substrate 1. However, it goes without saying that the lamp irradiation may be applied from the time when the solidified polycrystalline silicon layer has been deposited to a thickness of 100 to 150 μm. Further, the lamp may not be irradiated continuously but may be irradiated intermittently.

Further, in the above embodiment, the dropping of molten silicon and the lamp irradiation were performed simultaneously, but it goes without saying that the dropping of the molten silicon and the lamp irradiation may be repeated separately.

Next, in the first embodiment, molten silicon was dropped onto the insulating film to form a polycrystalline silicon layer, but molten silicon was dropped onto the single crystal surface to form a second polycrystalline silicon layer, which was used to form an epitaxial layer. An example is shown in FIG. As shown in FIG. 6, molten silicon 19 is dropped in a spray form onto the semiconductor substrate 1 with the single crystal surface exposed, and the dropped silicon is irradiated with a lamp to constantly solidify the epitaxial layer 23 and the molten silicon layer 2.
form 4. At this time, the growth of the solidified epitaxial layer 23 progresses gradually and uniformly within the surface of the semiconductor substrate 1, so that an epitaxial layer with good film thickness distribution and good crystallinity can be obtained. Next, stop dripping the molten silicon 19, stop the lamp irradiation,
By turning the molten silicon layer 24 into a solidified epitaxial layer 23, an epitaxial layer can be obtained on a single crystal plane.

[0027]

[Effects of the Invention] As described above in detail, according to the first embodiment of the present invention, when forming a polycrystalline silicon layer, the surface of the deposited polycrystalline silicon layer is always kept in a molten state. Therefore, by rotating the turntable on which the semiconductor substrate is placed, the molten silicon layer spreads over the semiconductor substrate to obtain a uniform distribution. For this reason, the thickness distribution of the formed polycrystalline silicon layer is improved compared to the conventional one, and the occurrence of warping of the semiconductor substrate and unfilled portions of the V-groove caused by the thickness distribution of the polycrystalline silicon layer is improved compared to the conventional one. It can be made smaller.

Furthermore, when an epitaxial layer is formed according to the present invention as shown in the second embodiment, the epitaxial layer, which had poor film thickness distribution and crystallinity due to rapid solidification in the conventional method, gradually changes from molten silicon to Since it is solidified, an epitaxial layer with good thickness distribution and crystallinity can be thickened at high speed.

[Brief explanation of the drawing]

FIG. 1: Process diagram of the first embodiment of the present invention

FIG. 2: Spray device according to an embodiment of the present invention

[Figure 3] Process diagram of conventional example

[Figure 4] Conventional spray device

[Fig. 5] Diagram explaining the drawbacks of the conventional example

[Fig. 6] Explanatory diagram of the second embodiment of the present invention

[Explanation of symbols]

1 Semiconductor substrate 2 SiO2 film 3 Opening portion 4 V-shaped grooves 6, 21 Solidified polycrystalline silicon layer 7 Processing reference surface 8 Island 10 Spray device 18 Lamp 19 Dropping molten silicon

Claims (4)

[Claims] 1. In a method of manufacturing a semiconductor device in which a polycrystalline silicon layer is deposited on a semiconductor substrate via an insulating film, when forming the polycrystalline silicon layer, heating means is applied while molten silicon is dropped in a spray form. A semiconductor device characterized in that the surface of the deposited polycrystalline silicon is melted at least once to form a molten silicon layer, the semiconductor substrate is rotated in the molten state, and then the molten silicon layer is solidified. Production method. 2. The method is characterized in that the surface of the deposited single-crystal silicon layer is melted by a heating means while molten silicon is sprayed onto the semiconductor substrate in which at least a portion of the single-crystal surface is exposed. A method for manufacturing a semiconductor device. 3. A first heating source for melting polycrystalline silicon in order to drop molten silicon in a spray form onto a semiconductor substrate and solidify and cool it to form a polycrystalline silicon layer or a single crystalline silicon layer; In a manufacturing apparatus comprising a melting tank, a second heat source that heats the semiconductor substrate, and a turntable on which the semiconductor substrate is placed and rotated, the surface of a polycrystalline silicon layer or a single crystal silicon layer deposited on the semiconductor substrate 1. A semiconductor device manufacturing apparatus characterized in that a third heating source capable of melting the semiconductor element is provided. 4. The semiconductor device manufacturing apparatus according to claim 3, wherein the third heat source according to claim 3 is a tungsten halogen lamp.