JPS62174969A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a substrate with an SOI structure having a highcrystal quality, by forming an insulation film over a single crystal semiconductor substrate on which a layer of a different type of semiconductor has been formed, bonding a supporting substrate thereto, and etching away the semiconductor substrate so as to leave the layer of the different type of semiconductor only. CONSTITUTION:A p-type silicon layer 11 having a thickness of about 1mum is epitaxially grown on an n<+> type silicon substrate 10 (wafer) and the surface of the p-type silicon layer 11 is heated in oxidizing atmosphere at high temperature of about 1,000-1,200 deg.C so as to produce an SiO2 film 12 having a thickness of about 0.3mum. After another silicon substrate or quartz substrate 13 (supporting substrate) is bonded thereon, only the n<+> type silicon layer 11 is left. The p-type silicon layer 11 thus obtained is a single 11 is left. The p-type silicon layer 11 thus obtained is a single crystal thin film formed on the insulating layer and this single crystal silicon film has a high quality with reduced defects. Accordingly, a semiconductor element formed on such silicon film is allowed to have a high quality with reduced parasitic capacitance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] After forming a heterogeneous semiconductor layer on a single crystal semiconductor substrate, an insulating film is formed thereon, and a support substrate is bonded to the insulating film.

Next, the semiconductor substrate is removed by etching, leaving only the foreign semiconductor layer to form a semiconductor substrate with a Sol structure. In this way, a substrate having an SOI structure with good crystal quality can be obtained.

[Industrial Applications] The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of forming a single crystal semiconductor substrate of an S01 structure semiconductor device.

Recently, S OI (Silicon On In5u
Semiconductor devices with a lator structure are attracting attention because of their high-speed operation.

This is because a semiconductor device that is advantageous in radiation resistance and high-temperature operation can be produced. For example, if devices are stacked three-dimensionally (three-dimensionally) and highly integrated, the effect of reducing the parasitic capacitance of the insulating substrate will combine to provide high-speed operation.

However, such a semiconductor device having an S○■ structure is required to be formed on a substrate with as good a crystalline quality as possible from the viewpoints of improved performance and quality.

[Problems to be solved by conventional technology and invention] Now,
SOS
A (Silicon On 5apphire) substrate is known, and as shown in the cross-sectional view of FIG. 2, it is a substrate in which silicon is epitaxially grown on a sapphire substrate 1 to form a single crystal silicon film 2. That is,
Since the sapphire substrate is a material with a high melting point, approximately 1200
℃ and grow a silicon film thereon, a crystalline silicon film along the sapphire crystal is formed.

However, sapphire substrates are very expensive, and although sapphire and silicon have similar crystal structures, they are still crystallographically different, resulting in a mismatch in the crystal lattice. The formed silicon film 2 contains many crystal defects.

Therefore, when compared with silicon substrates produced by conventional pulling methods or zone refining methods, the crystal quality is by no means good, and as a result, SO8 substrates are not widely used.

On the other hand, one of the Sol structure substrates that has been proposed recently is a Sol substrate prepared by beam annealing, and the method for forming it will be explained with reference to FIGS. 3(a) and 3(g). First, let's start with the same figure (
As shown in a), a silicon dioxide (SiO2) film 4 is formed on a silicon substrate 3, and a polycrystalline silicon film 5 is deposited thereon by chemical vapor deposition (CVD). Also, at this time, silicon nitride (Si) was used instead of the 5i02 film.
a N4 ) film may be formed, or an amorphous silicon film may be grown instead of the polycrystalline silicon film.

Next, as shown in FIG.
5er), the polycrystalline silicon film is scanned with a beam and heated and melted (this is beam annealing (this example is laser annealing)), and the polycrystalline silicon film is transformed into a single crystal silicon film 5.

However, in the SOI substrate created by this method, it is difficult to completely convert the polycrystalline silicon film 5 into a single crystal, and
Even if it is made into a single crystal, the crystal quality is not very good. Therefore, the current situation is that semiconductor elements are unavoidably formed in a crystalline silicon film 5 that has many defects and is of poor quality.

Various methods have also been attempted to improve the crystal quality of the crystalline silicon film 5 by improving the basic formation method shown in FIG. A method is known in which a seed is set and lateral epitaxial growth is performed from the seed. However, even when formed in this manner, it is extremely difficult to remove defects near the interface with the insulating film, and as a result, a silicon thin film with excellent crystal quality has not yet been created.

The present invention solves these problems and proposes a method for forming a Sol structure substrate that allows a single crystal thin film with good crystal quality to be obtained.

[Means for Solving Problem c] The purpose is to add a semiconductor layer having an impurity concentration different from the impurity concentration or a different conductivity type to a semiconductor substrate of one conductivity type (for example, an n-type silicon substrate) with a predetermined impurity concentration. forming a type semiconductor layer (e.g., a p-type silicon layer);
A step of forming an insulating film (for example, a SiO2 film) on the semiconductor layer, and then, after adhering a support substrate on the insulating film, the semiconductor substrate except for the semiconductor layer is removed by etching (for example, using halogen gas). This is achieved by a method of manufacturing a semiconductor device, which includes a step of etching away using a photo-excited etching method.

[Operation] In the present invention, after forming a heterogeneous semiconductor layer on a single crystal semiconductor substrate, an insulating film is formed thereon, and a support substrate is bonded to the insulating film. The semiconductor substrate is then etched away, leaving the foreign semiconductor layer. So! formed in this way! A semiconductor substrate with this structure has good crystal quality.

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

FIGS. 1A to 1D show cross-sectional views in the order of the formation steps of the formation method according to the present invention. First, as shown in FIG. A p-type silicon layer 11 with a thickness of about 1 μm is epitaxially grown. This p-type silicon layer 11 needs to have a donor impurity concentration sufficiently lower than that of the silicon substrate 10.
It does not necessarily have to be a p-type layer, but may be an n-type layer.

Next, as shown in FIG. 1(b), about 1000 to 12
The surface of the p-type silicon layer 11 is heated in a high-temperature oxidizing atmosphere at 00° C. to form a 5i02 film 12 with a thickness of about 0.3 μm. The 5i02 film 12 produced by this high-temperature oxidation has good insulation and extremely few crystal defects at the interface.

Next, as shown in FIG.
Glue. The bonding method is, for example, by layering a thin layer of phosphorus silicate glass (PSG) on the 5i02 film 12 using a CVD method, and then melting and bonding this. This phosphorus silicate glass melts at a low temperature of about 900°C. Furthermore, the 5i02 film 12 itself may be melted at high temperature and bonded.

Next, as shown in FIG. 1(d), only the n+ type silicon substrate 10 is removed by etching, and the p type silicon layer 11 is removed.
remain. The etching method uses a halogen-containing gas, such as chlorine gas, as a reaction gas and irradiates ultraviolet rays onto the reaction area, ie, a so-called photoexcited dry etching method.

The etching conditions were a gas pressure of 1O in the reaction chamber.
Set the temperature to around Torr and emit ultraviolet light with a wavelength of around 300 nm at an intensity of 300 mW/co? irradiated with C12 gas flow rate of 200
Flow approximately m1/min. Then, the n+ type silicon substrate 10 is etched at an etching rate of about 1100 n/min. However, the etching rate of the p-type silicon layer is 2.
Since it is smaller by more than an order of magnitude, only the p-type silicon layer 11 can remain.

In addition, for etching the silicon substrate 11, wet etching using a caustic potash solution is also possible.
Moreover, both may be used together. Furthermore, if polishing is applied to the initial etching, the etching time will be reduced.

The p-type silicon layer 11 thus formed is a single-crystal thin film on an insulating film, and is a high-quality single-crystal silicon film with as few defects as a conventional bulk crystal.

Therefore, if a semiconductor element is formed on such a single crystal silicon layer 11, a high quality element with less parasitic capacitance can be produced.

[Effects of the Invention] As is clear from the above explanation, according to the present invention, a substrate with an SOI structure of the highest quality can be obtained, and a semiconductor device fabricated on the substrate can have extremely high performance, quality, and reliability. Become.

[Brief explanation of drawings]

Figures 1 (a) to (d) are cross-sectional views of a Sol structure substrate according to the present invention in the order of the formation process, Figure 2 is a cross-sectional view of a conventional SOS substrate, and Figures 3 (al to b) are cross-sectional views of a conventional SOI substrate. 1 is a cross-sectional view of the substrate in the order of forming steps. In the figure, 1 is a sapphire substrate, 2 is a single crystal silicon film, 3 is a silicon substrate, 4 and 12 are 5i02 films, and 5 is l
10 is an n+ type silicon substrate, 11 is a p-type silicon layer, and 13 is a silicon substrate or a quartz substrate (supporting substrate). 74 EMt = car or asor, potato) L revised] Fq 7 Otsuro nFiTJ-Znl &#@E@ 1 Figure following ptq 5osJ Thorn Δ Ruins map 2nd Kokusha C U SO Yu” 71 me ＾ 罎已 りノFig. 3

Claims (4)

[Claims] (1) A semiconductor layer having an impurity concentration different from the impurity concentration or a semiconductor layer of a different conductivity type is formed on a semiconductor substrate of one conductivity type with a predetermined impurity concentration, and an insulating film is further formed on the semiconductor layer. A method for manufacturing a semiconductor device, comprising the steps of: bonding a support substrate onto the insulating film, and then etching away the semiconductor substrate except for the semiconductor layer. (2) The method of manufacturing a semiconductor device according to claim 1, wherein the semiconductor substrate is a silicon substrate, and the insulating film is a silicon oxide film produced by thermal oxidation. (3) The method for manufacturing a semiconductor device according to claim 1, wherein the semiconductor substrate is an n-type silicon substrate, and the semiconductor layer is a p-type silicon layer. (4) The method of manufacturing a semiconductor device according to claim 1, wherein the etching method for etching away the semiconductor substrate is a photoexcitation etching method in a gas containing halogen.