JPH04307735A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To polish a thick-film SOI film and to make it into a thin film having the good uniformity in its film thickness. CONSTITUTION:A second SiO2 film 5 is deposited on an opening part 4 formed in a semiconductor film 3 on a first insulator 2. The film thickness of the second SiO2 film 5 is set to a target film thickness for an SOI. After that, resist is left only in the opening part by a resist coating operation and by an etching- back method, and the second SiO2 film 5 other than the bottom part of the opening part 4 is removed by a wet etching operation or a dry etching operation. After that, the SOI film is polished and made into a thin film by using an abrasive material until the second SiO2 film 5 on the bottom part of the opening part 4 comes into contact with an abrasive plate. When a material whose polishing rate is large with reference to Si and very small with reference to SiO2 is selected as the abrasive material, the second SiO2 film 5 at the bottom part of the opening part 4 acts as a polishing stopper, and the SOI film can be polished over the whole surface of a wafer and can be made a thin film so as to make the uniformity of its film thickness good.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to SOI (Silicon
The present invention relates to a method of manufacturing a high-performance semiconductor device of the on-insulator type.

0002

2. Description of the Related Art In recent years, SOI type semiconductor devices have been studied for practical use because they have advantages over semiconductor devices formed on Si substrates in terms of radiation resistance and high speed. Generally, the thickness of the Si film in SOI type semiconductor devices is 0.2μ.
Unless it is thinner than about m, it has little advantage over a semiconductor device formed on a Si substrate. However, ZMR (Zon
e Melting Recrystallizati
SOI substrates formed using the on) method and the bonding method generally have a film thickness of 0.5 μm or more, and the film thickness is not uniform, so reducing the film thickness by polishing is extremely difficult in terms of film thickness control. It was difficult. Therefore, a polishing stopper pattern is formed in advance, and then S
There is a method in which an OI film is formed and the film is made thinner by polishing.

An example of a method for manufacturing a semiconductor device for forming the above-mentioned conventional thin film SOI will be described below with reference to the drawings. FIG. 2 shows a method of forming a thin film SOI using a polishing stopper pattern and the ZMR method.

First, in FIG. 1A, a SiO2 film 10 having a polishing stopper pattern 103 on a Si substrate 101 is shown.
2 is formed, and a non-single crystal Si film 104 is further formed thereon. Next, in FIG. 3B, the non-single crystal Si film 104 is melted and recrystallized by the linear heater 106 to form a single crystal Si film 105.

Next, in FIG. 1C, the single crystal Si film 105 is polished using a non-abrasive material and a polishing plate.
03 Polish the surface until it touches the polishing plate to form a thin film. By selecting an abrasive whose polishing rate is fast for Si and very slow for SiO2, polishing stopper pattern 1
03 When the surface comes into contact with the polishing plate, the polishing speed decreases extremely,
A single-crystal Si film with good thickness uniformity can be formed over the entire surface of the wafer, as shown in FIG. 3(c).

FIG. 3 shows a method for forming a thin film SOI using a polishing stopper pattern and a bonding method.

First, in FIG. 2(a), a first Si substrate 20
1, a recess 204 is formed using a photomask method and a dry etching method.
is formed, and then a SiO2 film 202 and a polycrystalline Si film 202 are formed.
Deposit film 203. The depth of the recess 204 is the target S
Set it to be the same as the OI film thickness.

Next, in FIG. 2B, the polycrystalline Si film 203 is polished using a polishing plate and an abrasive to remove the polycrystalline Si film 203 other than the recessed portion 204.

Next, in FIG. 2(c), the first Si substrate 20
The first and second Si substrates 205 are bonded and bonded together.

Next, as shown in FIG. 2D, the first Si substrate 201 is polished from the back side using a polishing plate and a polishing material until the SiO2 film 202 in the recess 204 is exposed. Finally, the SOI thin film 206 is formed with good film thickness uniformity.

[0011]

[Problems to be Solved by the Invention] However, in the above structure, for example, in the case of the ZMR method, the polishing stopper pattern exists as a step on the base during recrystallization, so that the polishing stopper pattern around the polishing stopper pattern in the recrystallized SOI layer is Crystal defects may occur, and since the polishing stopper pattern is formed before recrystallization, the device layout will be restricted by the polishing stopper pattern after recrystallization, so recrystallization must be done after designing the device layout. The problem was that it could not be done.

[0012] Also, after forming the polishing stopper pattern,
When thinning the film by bonding and polishing, there were problems in that the polishing process had to be performed twice, and the device layout design had to be completed and a polishing stopper pattern had to be formed before bonding. . Furthermore, when there is no polishing stopper pattern, there is a problem in that the Si film thickness varies greatly due to polishing.

In view of the above-mentioned problems, the present invention forms a polishing stopper pattern afterwards, so it does not affect the crystallinity of the SOI layer when recrystallizing by the ZMR method, and recrystallization can be performed even when the element layout is not yet designed. Thick film S
It is an object of the present invention to provide a method for manufacturing a semiconductor device, which can perform up to OI formation, and which can thin the film with good controllability even on an SOI substrate without a polishing stopper pattern.

[0014]

[Means for Solving the Problems] A method for manufacturing a semiconductor device of the present invention includes the steps of providing an opening in a semiconductor film formed on a first insulating film, and depositing a second insulating film in the opening. a step of removing the second insulating film in a portion other than the bottom surface of the opening, and using a polishing plate and an abrasive material with the second insulating film remaining on the bottom surface of the opening as a polishing stopper. and a step of thinning the semiconductor film.

[0015]

[Operation] With the above-described structure, the present invention forms a polishing stopper pattern after forming the SOI layer, so even if the element layout design has not been completed, it is possible to proceed with the formation of a thick film SOI. It becomes possible to form a polishing stopper pattern later on an SOI substrate that does not have one, thereby making it a thin film.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing a semiconductor device according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a partial process cross-sectional view showing a method for manufacturing a semiconductor device in an embodiment of the present invention.

FIG. 1A is a cross-sectional view of a substrate 1 in which a semiconductor film 3 is formed on a first insulating film 2, that is, an SOI substrate. The substrate 1 is, for example, a Si substrate, the first insulating film 2 is, for example, a SiO2 film, and the semiconductor film 3 is, for example, a Si single crystal film. This SOI substrate is formed using a ZMR method, a bonding method, a SIMOX method, an epitaxial growth method, an anodizing method, a laser/electron beam recrystallization method, etc., and the thickness of the semiconductor film 3 is from 0.1 μm to 0.1 μm. Appropriately, the thickness of the first insulating film 2 is approximately 3 μm, and the thickness of the first insulating film 2 is approximately 0.01 μm to 5 μm.

FIG. 1(b) shows an SOI substrate having such a structure.
As shown in FIG. 3, an opening 4 is formed in the semiconductor film 3 by a photomask method and a dry etching method. Although the shape and size of the openings 4 are not limited, if they are formed in a lattice shape, it is easier to obtain uniformity in film thickness in the subsequent polishing process. Appropriately, one side of the grating is several μm to several 100 μm. Also, the width is 1μ
It is set to be about m to several tens of μm.

Next, in FIG. 1(c), a second insulating film 5 is deposited over the entire surface including the opening 4. Then, as shown in FIG. The second insulating film 5 is, for example, a SiO2 film formed by CVD. What is important here is to select the deposition conditions and deposition apparatus so that the thickness of the second insulating film 5 is equal on the bottom of the opening 4 and on the semiconductor film 3. The thickness of the second insulating film 5 is also the polishing target thickness of the semiconductor film 3, and is therefore suitably 0.3 μm or less and 0.01 μm or more.

Next, in FIG. 1(d), a resist is applied to the entire surface including the opening 4. Then, as shown in FIG. 1(e), the entire resist is etched back, leaving the resist only in the opening 4. Note that although an etch-back method is used here as a method for leaving the resist in the opening 4, a photomask exposure process may also be used.

Next, in FIG. 1(f), the second insulating film 5 other than the bottom of the opening 4 is removed by dry etching or wet etching.

Next, in FIG. 1G, the semiconductor film 3 is polished and thinned using a polishing plate 6 and an abrasive material until the second insulating film 5 at the bottom of the opening 4 is exposed. Polishing rate is semiconductor film 3
By selecting an abrasive that is large for the second insulating film 5 and very small for the second insulating film 5, the semiconductor film 3 is polished as shown in FIG. 1(h).
The film thickness of the second insulating film 5 at the bottom of the opening 4 is equal to that of the second insulating film 5 at the bottom of the opening 4, and the surface of the second insulating film 5 at the bottom of the opening 4 is
When the polishing rate comes into contact with the semiconductor film 3, the polishing rate decreases significantly and the polishing of the semiconductor film 3 stops progressing, and the semiconductor film 3 having the same thickness as the second insulating film 5 is obtained over the entire surface of the substrate 1 as shown in FIG. 1(i). For example, an amine aqueous solution is used as the polishing material.

In this embodiment, the semiconductor film 3 is made of Si.
Although a single crystal film is used, a Si polycrystal film, a Ge film, or a GaAs film may be used.

[0024]

Effects of the Invention As described above, the present invention provides a polishing stopper pattern after forming an SOI layer.
It does not adversely affect the crystallinity of the layer, and even an SOI substrate without a polishing stopper pattern can be polished into a thin film.

[Brief explanation of the drawing]

FIG. 1 is a process cross-sectional view of a method for manufacturing a semiconductor device in an embodiment of the present invention.

FIG. 2 is a process sectional view illustrating a conventional example.

FIG. 3 is a process cross-sectional view illustrating a conventional example.

[Explanation of symbols]

1 Board 2 First insulating film 3 Semiconductor film 4 Opening 5 Second insulating film 7. Polishing plate

Claims (1)

[Claims] 1. A step of forming an opening in a semiconductor film formed on a first insulating film, a step of depositing a second insulating film in the opening, and a step of depositing a second insulating film in the opening. A semiconductor device comprising: removing a second insulating film; and using a polishing plate and an abrasive material to thin the semiconductor film using the second insulating film remaining on the bottom surface of the opening as a polishing stopper. Method of manufacturing the device.