JPH0936221A - Composite semiconductor substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite semiconductor substrate which does not warp much even when the wafer diameter is large. SOLUTION: In a composite semiconductor substrate constituted by sticking one or a plurality of single-crystal semiconductor areas 11 separated from each other to a supporting substrate which supports the areas 11 with a vitreous material 13, the bottom and side faces of the areas 11 are coated with insulating films 12 and a layer 17 composed of a polycrystalline or amorphous semiconductor is provided immediately below the insulating films 12. The supporting substrate is composed of two substrates 14 and 16 stuck to each other with a vitreous material 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor substrate, and more particularly to a composite semiconductor substrate including a dielectric isolation substrate for a semiconductor device suitable for manufacturing a highly functional or high performance semiconductor device.

[0002]

2. Description of the Related Art Dielectric isolation technology, which is known as a method for isolating semiconductor single crystal regions from each other, has an extremely good isolation technology between devices as compared with a standard junction isolation substrate, and limits application circuits. It is suitable for power ICs with high withstand voltage and large current because it has a small amount. EPIC (Epitaxial Passivated Integrated C) is a typical dielectric isolation method.
The ircuit) method is known, but various other methods are being studied due to problems with large wafer diameters and manufacturing costs. One of them is SOI (Silicon On Insulator) technology for manufacturing a substrate by bonding a plurality of semiconductor substrates together. Among them, as an excellent method for bonding substrates, for example, there is a method disclosed in JP-A-61-242033.

In the above-mentioned publication, a soot-like substance obtained by burning a raw material containing silicon tetrachloride as a main component with an oxyhydrogen flame is deposited on the surface of a semiconductor substrate, and after superposing a supporting substrate, helium gas and oxygen are added. A method of joining a semiconductor substrate by sintering a soot-like substance which is heat-treated in a mixed gas atmosphere is disclosed. This method is excellent in that a large-diameter composite semiconductor substrate having few crystal defects can be manufactured at a relatively low cost. As shown in FIG. 1, a conventional substrate having a plurality of semiconductor single crystal regions manufactured by a bonding method of this kind is usually a semiconductor single crystal island 11 covered with an insulating film 12 such as SiO _2. Are bonded to the support substrate 14 by the glass material layer 13. Also, the semiconductor single crystal island 11 and the glass material layer 1 covered with the insulating film 12 such as SiO ₂
In some cases, a semiconductor polycrystal layer or the like may be interposed between the above and 3.

[0004]

However, recently,
A semiconductor substrate having a larger wafer diameter has been demanded, and internal stress remains in the glass substance layer, the insulating layer, the supporting substrate, and their interface in the semiconductor substrate bonded by the conventional method described in the above publication. Therefore, the warpage (the difference in height between the outer peripheral portion and the central portion) accompanying a large-sized wafer becomes large, and as a result, it becomes difficult to carry it on a production line where various devices are built on a semiconductor substrate, or fine photolithography is performed. The problem is that it is difficult to increase the accuracy.

In Japanese Patent Publication No. 58-45182, a semiconductor polycrystalline layer is provided between an insulating layer and a glass layer,
Although a dielectric isolation substrate having an effect of preventing impurities from the glass layer from diffusing into the semiconductor single crystal island is described, the presence of the semiconductor polycrystalline layer may increase the warp. In such a case, Also, a means for controlling the warp was required.

Various methods are conceivable for reducing the warp. For example, a method of depositing a film that gives an opposite warp on the exposed surface of the support substrate is considered to be most effective. However, in many cases, the film that gives the opposite warp is removed during the device process step, and as a result, the warp of the substrate becomes large, which may cause troubles such as stopping in the middle of the production line. is there.

An object of the present invention is to solve the above-mentioned problems in the conventional composite semiconductor substrate and to provide a composite semiconductor substrate having a large wafer diameter and a small warpage.

[0008]

The present invention provides a composite semiconductor substrate in which one or a plurality of semiconductor single crystal regions separated from each other and a supporting substrate supporting the same are bonded by a glass material. A bottom surface and a side surface of the semiconductor single crystal region are covered with an insulating film, a layer made of a semiconductor polycrystal or an amorphous semiconductor is provided in contact with the insulating film, and the supporting substrate is two substrates bonded with a glass material. It relates to a composite semiconductor substrate comprising:

A feature of the present invention is a structure capable of fundamentally eliminating the warp of a dielectric isolation substrate having a structure in which glass substrates are laminated together, regardless of the thickness or composition of the glass.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The structure of a composite semiconductor substrate of the present invention will be described with reference to FIG. The plurality of semiconductor single crystal regions 11 are separated from each other and are electrically insulated from each other. As shown in the figure, the periphery of the semiconductor single crystal region 11 is covered with an insulating film 12. Further, a layer 17 made of a semiconductor polycrystal or an amorphous semiconductor is provided so as to be in contact with the insulating film 12 so as to connect the plurality of semiconductor single crystal regions 11 with each other. It has the effect of preventing impurities from diffusing into the semiconductor single crystal islands and the effect of reducing the deviation of the semiconductor single crystal region 11 during the device process. The semiconductor single crystal region 11 and the above-mentioned respective layers connecting these are bonded to the supporting substrate through the glass material layer 13. The support substrate in the present invention has a structure in which the substrate 14 and the substrate 16 are joined by the glass material layer 15. According to the present invention, the warp, which has been a problem in the conventional technique, is eliminated by the glass material layer 15 and the substrate 16.
It can be freely designed so as to be fundamentally solved by and. Further, the substrate 16 covers the surface of the glass substance layer 15 and also has an effect of preventing the glass substance layer 15 from being removed during the device process.

Silicon is a typical material for the semiconductor single crystal region 11, but GaAs, GaAlAs, In
Various compound semiconductors such as P and SiC and single element semiconductors such as Ge may be used.

The insulating film 12 is not particularly limited,
A SiO ₂ film is preferably used. The thickness of the insulating film is usually 0.5 to 2.0 μm.

The semiconductor polycrystalline layer 17 provided in contact with the insulating film 12 is a polycrystalline layer of a single element semiconductor such as silicon or Ge, or GaAs, GaAlAs, In.
Examples of the amorphous semiconductor layer 17 include a polycrystalline layer of various compound semiconductors such as P and SiC, and examples of the amorphous semiconductor layer 17 include an amorphous semiconductor layer made of amorphous silicon, silicon germanium, or the like. The thickness of the semiconductor polycrystalline layer or amorphous semiconductor layer is usually 0.1 to 100.
μm, preferably 1 to 50 μm.

The glass material layers 13 and 15 are silicon,
Those containing boron and oxygen as main components are preferable. If the glass material layer is too thin, it may not be completely bonded, and if it is too thick, the bonding strength will be reduced, so 0.5.
˜500 μm, preferably 0.5 to 100 μm.
Note that a phosphorus compound or a germanium compound can be added to lower the sintering temperature of the glass material layer.

The substrate 14 and the substrate 1 which constitute the supporting substrate.
The material of 6 is preferably the same as that of the semiconductor single crystal region 11, but the material is not necessarily the same as the material of the semiconductor single crystal area 11. It has good bondability with a glass substance and does not undergo alteration or deformation during the bonding process. It is also possible to select a material in which strain does not easily occur on the surface.

In the present invention, particularly the supporting substrates 14 and 1
As a sixth feature, it is also a great feature that a material that gives a large warp to a substrate due to a difference in thermal expansion coefficient or a material that easily deteriorates during a device process can be used in the conventional technology.
Examples of materials that can be used include quartz glass, sapphire, alumina, and a silicon carbide sintered body for the support substrate 14.
Magnesia, silicon nitride, heat resistant glass, etc.,
Examples of the support substrate 16 include sapphire, alumina, sintered silicon carbide, silicon nitride and the like.

The semiconductor single crystal region 11 in the above description
May be different from each other between the semiconductor single crystal regions. Further, a part of the semiconductor single crystal region 11 may be directly bonded to the supporting substrate 14, or a part of the supporting substrate 14 may appear on the device surface.

In FIG. 2, the semiconductor single crystal region 11
Are separated from each other, but the semiconductor single crystal region 11 is one, and the insulating layer 12 and the layer 17 made of a semiconductor polycrystalline or amorphous semiconductor and the glass material layer 13 are provided.
It may be bonded to the support substrate 14 via the.

Next, an example of the method for manufacturing the composite semiconductor substrate of the present invention will be described with reference to FIG. First, an isolation groove is formed on the surface of the semiconductor substrate 10 to be the semiconductor single crystal region 11.
Although it is a V-shaped groove in FIG. 3, it may be a trench or the like, and can be selected in consideration of a target device and manufacturing cost. The V-shaped groove can be manufactured by a commonly used method such as wet anisotropic etching using KOH or dry etching using SF ₆ gas. The depth of the groove is preferably a little deeper than the thickness of the semiconductor single crystal region 11, and is usually 0.1 to 300 μm.
It is a degree. Since the semiconductor substrate 10 finally becomes the semiconductor single crystal region 11, the material is the same semiconductor as the semiconductor single crystal region.

Next, the insulating film 12 is formed on the surface of the semiconductor substrate 10. A SiO ₂ film is preferably used as the insulating film. The SiO ₂ film is formed by a CVD method or the like, but when the semiconductor substrate 10 is silicon, SiO ₂ obtained by thermally oxidizing the surface is preferably used.

Next, a semiconductor polycrystal or amorphous semiconductor layer 17 is formed on the insulating film 12. The method for forming the semiconductor polycrystalline or amorphous semiconductor layer 17 is not particularly limited, but for example, in the case of polycrystalline silicon, CVD is used.
It can be manufactured by a (chemical vapor deposition) method or the like, and in the case of an amorphous semiconductor, it can be manufactured by a plasma CVD method or the like.

Next, after the soot-like substance layer 3 is formed, the supporting substrate 14 is superposed, the soot-like substance layer 4 is further formed on the supporting substrate 14, the supporting substrate 16 is further superposed, and then the substrate is heated. By the treatment, the soot-like substance layers 3 and 4 are sintered into the glass substance layers 13 and 15, and the semiconductor substrate 1
0 and the supporting substrates 14 and 16 are bonded together. The glass material layers 13 and 15 contain silicon, boron and oxygen as main components, and can optionally contain a phosphorus compound or a germanium compound. Glass material layer 1
The compositions and manufacturing methods of 3 and 15 may be different from each other, but the same composition is preferable in terms of manufacturing equipment and steps. The glass material layer can be manufactured by a soot deposition method, a CVD method, a spin coating method, or the like. Among them, the soot deposition method is particularly preferable because it is filled with the glass material to the every corner of the groove.

The soot deposition method is based on SiO ₂ and B ₂ O ₃ obtained by burning a raw material containing a silicon compound such as SiCl ₄ and a boron compound such as BCl ₃ as main components in an oxyhydrogen flame. Soot-like substance 3
Is deposited on the surface of the semiconductor substrate 10 and superposed on the support substrate 14, and then the soot-like substance 4 is further deposited,
This is a method in which the semiconductor substrate 10 and the supporting substrates 14 and 16 are bonded to each other by stacking the supporting substrate 16 on top of each other, and then performing heat treatment and sintering. The sintering of the soot-like substance does not have to be performed at the same time, and the soot-like substance 3 is deposited on the semiconductor substrate 10 and the soot-like substance 4 previously deposited on the supporting substrate 14 or 16 is sintered to bond them together. After mounting the supporting substrate on the soot-like substance 3, the soot-like substance 3
It can also be stuck by sintering. In addition, the soot-like substance 3 is deposited on the semiconductor substrate 10 in advance,
After the supporting substrates 14 are superposed on each other, the supporting substrates 14 are laminated by sintering, and then the soot-like substance 4 is formed on the exposed surface of the supporting substrate 14.
Alternatively, the support substrate 16 may be placed on the support substrate 16 and the soot-like substance 4 may be sintered to bond them together.

Manufacture of composite semiconductor substrate by soot deposition method
The silicon compound used in the oxyhydrogen flame
By burning with SiO_TwoIs a compound that produces
And the general formula SiR¹R^TwoR^ThreeR^FourCompound represented by
(Substituent R¹, R^Two, R^ThreeAnd R^FourAre identical to each other
May be different, halogen, hydrogen, an alkyl group,
It is a substituent selected from an alkyloxy group. );
Containing two or more silicon atoms such as siloxane and polysiloxane.
Having siloxanes; silicon such as disilane and polysilane
Examples include silanes containing two or more atoms.
You. Among them, the obtained SiO_TwoQuality and particle size etc.
From a viewpoint, a compound represented by the general formula SiR¹R^TwoR^ThreeR^Fourso
A compound represented by the substituent R¹, R^Two, R^ThreeAnd
And R^Four(R¹~ R^FourMay be the same or different from each other
Yes. ) Is chlorine, hydrogen, an alkyl group having 1 to 3 carbon atoms,
A substituent selected from an alkyloxy group having a prime number of 1 to 3
It is. Among these, particularly preferred are the above substituents
R¹, R^Two, R^ThreeAnd R ^Four(R¹~ R^FourAre identical to each other
But they may be different. ) Is chlorine or hydrogen
It is. Specific examples of these silicon compounds include SiCl
_Four, SiH_Four, Si _TwoH₆, SiHCl_Three, Si (OE
t)_FourAnd Si (OMe)_FourEtc.
You.

As the boron compound, boron trichloride, boranes (BH ₃ , B ₂ H ₆ ), BHCl ₂ , B (OE
t) ₃ and B (OMe) _3. Among them, boron trichloride is preferable because of easy supply.

The phosphorus compound and the germanium compound, which are optionally added to lower the sintering temperature of the soot-like substance, are those which generate oxides of phosphorus and germanium by burning in an oxyhydrogen flame. Any compound may be used, and examples of phosphorus compounds include phosphorus pentachloride, phosphorus oxychloride (POCl ₃ ), phosphine (PH ₃ ), and germanium compounds include germanium tetrachloride and germane (GeH _4). ) Etc. can be mentioned. Of these, phosphorus pentachloride and phosphorus oxychloride (P
OCl ₃ ) and germanium tetrachloride.

If the raw material is a gas, the raw material is supplied directly into the oxyhydrogen flame or while being mixed with hydrogen or oxygen while the oxyhydrogen flame is mixed by adjusting the flow rate with a valve or the like. To supply. If the raw material is a liquid, it is supplied by a spray device, or by using a hydrogen gas, an oxygen gas or an inert gas such as an argon gas or a nitrogen gas as a carrier and accompanying the vapor of the raw material,
Alternatively, it can be supplied by a method such as heating the raw material and pumping it by the vapor pressure of the raw material itself.

The above-mentioned raw material supplied in the oxyhydrogen flame was subjected to flame addition.
Hydrolyzed, SiO_TwoAnd B_TwoO _ThreeThe main component
Produces soot. This soot-like substance is ultra-fine particles of glass
It is a child and has a particle size of about 0.05 to 0.2 μm.
Oxy-hydrogen flame refers to the simultaneous supply of oxygen and hydrogen.
It is a combustion flame obtained by:

The generated soot-like substance is immediately deposited on the surface of the semiconductor substrate 10 to be bonded and the surface of the supporting substrate 14. Deposition of oxyhydrogen semiconductor substrate 1
It is preferable to carry out the process by directly spraying on 0 and the supporting substrate 14.

Next, the soot-like substance is heat-treated to be sintered. The sintering is preferably performed substantially in oxygen gas in order to prevent the formation of voids in the valleys of the grooves provided in the semiconductor substrate 10 as much as possible. That is, it is preferable that the oxygen gas is 90% or more and the helium gas is 2% or less, and the other gas that is not reactive with the semiconductor substrate or the like is used. In particular, the oxygen gas content is 95% or more, and more preferably 99% or more.
The heat treatment temperature during sintering is 800 to 1400 ° C. The soot-like substance is vitrified when sintered, and the semiconductor substrate 10 and the supporting substrates 14 and 16 are bonded to each other.

After that, the support substrate 16 and the semiconductor substrate 1
A composite semiconductor substrate is manufactured by grinding and polishing 0 from the side opposite to the bonding surface to the lines A and B in FIG. If the semiconductor substrate used for bonding is a grooved substrate such as a V-shaped groove or trench groove,
Through the grinding / polishing step, island-shaped separated semiconductor single crystal regions 11 are obtained.

[0032]

EXAMPLES The present invention will be described more specifically below, but the present invention is not limited thereto. Example 1 The composite semiconductor substrate shown in FIG. 2 was manufactured as follows. A substrate having a V-shaped recess was manufactured as follows. First, as shown in FIG.
V-grooves were formed at a depth of 50 μm by photolithography and anisotropic etching on the surface of a silicon substrate 10 having a diameter of 6 inches and a thickness of 625 μm having a (0) plane. The V groove is formed by forming a mask of SiO ₂ by photoetching, and exposing the region of Si to a 20% aqueous solution of KOH 9
0 parts by weight, isopropyl alcohol 5 parts by weight and n-
It was prepared by etching at a temperature of 80 ° C. using a so-called anisotropic etching solution containing 5 parts by weight of butyl alcohol.

Subsequently, SiO ₂ was formed on the surface of the V groove as the insulating film 12 to a thickness of 1.5 μm by thermal oxidation.
Next, polycrystalline silicon was formed to a thickness of 20 μm on the surface where the V-groove was formed by CVD.

Then, the gaseous S is adjusted so that the atomic ratio (Si / B) a of silicon and boron of the glass substance becomes 2.5.
iCl ₄ (supply rate of 250 ml / min) and gaseous BCl ₃ (supply rate of 100 ml / min) were replaced with hydrogen (supply rate of 850 ml / min) and oxygen (supply rate of 5000 ml / m).
in), and soot-like substance 3 obtained by decomposition is deposited on the surface of the semiconductor substrate 10 in which the V groove is formed. The amount of soot-like substance 3 deposited was adjusted to 20 μm when it was sintered. A 6-inch diameter, 460 μm-thick silicon substrate 14 having a plane orientation (100) plane, which was separately prepared, was superposed on the deposition of the soot-like substance 3, and subsequently, the above-mentioned method was repeated on the silicon substrate 14. The soot-like substance 4 was deposited by The amount of soot-like substance 4 deposited was adjusted to 22 μm when it was sintered. Further, a 6-inch diameter, 625 μm-thick silicon substrate 16 having a plane orientation (100) plane, which was separately prepared, was superposed on the deposition of the soot-like substance 4, and 1280 ° C. in an oxygen atmosphere in a heating furnace. After heating for 48 hours, the soot-like substances 3 and 4 each had a thickness of 2
The three glass substrates were evenly bonded to each other by vitrification at the same time when the volume contracted to 0 μm and 22 μm.

The substrate thus bonded is subjected to an ultrasonic image exploration apparatus (UH Pulse20 manufactured by Olympus Corporation).
When the groove filling state was examined in 0), it was confirmed that no holes were present. Furthermore, when the cleaved surface of this substrate was observed with a scanning electron microscope, it was found that glass was filled in every corner of the V-shaped groove. Using a sample prepared under the same conditions to determine the composition ratio of the glass substance, the glass substance was dissolved in an aqueous solution of hydrogen fluoride and quantitatively analyzed by ICP. The atomic ratio a of Si / B was 2. It was 5.

Next, the support substrate 16 was ground and polished so as to have a thickness of 50 μm in consideration of the finished thickness. Then, polishing is performed from the surface opposite to the bonding of the silicon substrate 10 to a predetermined thickness, and further polishing is performed using a mechanochemical polishing method to remove unnecessary portions until the polycrystalline silicon layer appears on the surface. Then, the island-shaped semiconductor regions 11 which are insulated from each other are formed. The warp at this time was such that when the semiconductor single crystal region was placed on a flat surface and was placed on a plane, the central portion was convex upward by 45 μm from the periphery. Therefore, there was no trouble at the time of transportation, and the yield in the photolithography process was good.

The sample 1 obtained by cutting this substrate into 5 mm square chips was observed for the sintered state of the chip cross section using a scanning electron microscope. As a result, the semiconductor substrate of the sample 1 and the supporting substrate were uniformly bonded. And the bonded state was good. Further, when the filling state of the groove was observed, no minute holes were generated, and no damage such as scuffing was observed.

Example 2 A substrate was prepared in the same manner as in Example 1 except that the supporting substrate 14 was made of quartz glass having a thickness of 460 μm. The warp at this time was such that, when the semiconductor single crystal region was placed on a flat surface and was placed on a plane, the central portion was convex upward by 47 μm from the periphery. Therefore, there was no trouble at the time of transportation, and the yield in the photolithography process was good.

Example 3 A substrate was prepared in the same manner as in Example 1 except that the supporting substrate 14 was sapphire having a thickness of 460 μm. The warp at this time was such that, when the semiconductor single crystal region was placed on a flat surface, the warp was such that the central portion was convex upward by 39 μm from the periphery. Therefore, there was no trouble at the time of transportation, and the yield in the photolithography process was good.

Example 4 A substrate was prepared in the same manner as in Example 1 except that the supporting substrate 14 was an alumina sintered body having a thickness of 460 μm. The warp at this time was such that, when the semiconductor single crystal region was placed on a flat surface and was placed on a plane, the central portion was convex upward by 47 μm from the periphery. Therefore, there was no trouble at the time of transportation, and the yield in the photolithography process was good.

Example 5 A substrate was produced in the same manner as in Example 1 except that the supporting substrate 14 was a 460 μm thick silicon carbide sintered body. The warp at this time was such that, when the semiconductor single crystal region was placed on a flat surface, the warp was such that the central portion was convex upward by 41 μm from the periphery. Therefore, there was no trouble at the time of transportation, and the yield in the photolithography process was good.

Example 6 A substrate was produced in the same manner as in Example 1 except that the semiconductor polycrystal layer 17 was an amorphous semiconductor layer 17. The warp at this time was such that, when the semiconductor single crystal region was placed on a flat surface and was placed on a plane, the central portion was convex upward by 44 μm from the periphery. Therefore, there was no trouble at the time of transportation, and the yield in the photolithography process was good.

[0043]

As described in detail above, the composite semiconductor substrate of the present invention has a small warp even when it has a large wafer diameter, and can be put into a device manufacturing line where strict standards are required. The accuracy of photolithography can be increased and the yield can be improved, which is practically useful.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a composite semiconductor substrate manufactured by a conventional dielectric isolation technique.

FIG. 2 is a longitudinal sectional view showing one embodiment of the composite semiconductor substrate of the present invention.

FIG. 3 is a diagram showing a manufacturing process of the composite semiconductor substrate of the present invention.

[Explanation of symbols]

 3 Soot Material Layer 4 Soot Material Layer 10 Semiconductor Substrate 11 Semiconductor Single Crystal Region 12 Insulating Film 13 Glass Material Layer 14 Support Substrate 15 Glass Material Layer 16 Support Substrate 17 Semiconductor Polycrystalline or Amorphous Semiconductor Layer

Claims (1)

[Claims] 1. A composite semiconductor substrate in which one or a plurality of semiconductor single crystal regions separated from each other and a supporting substrate supporting the semiconductor single crystal regions are bonded by a glass material, and a bottom surface and a side surface of the semiconductor single crystal region. Is covered with an insulating film, a layer made of a semiconductor polycrystalline or amorphous semiconductor is provided in contact with the insulating film, and the supporting substrate is composed of two substrates bonded by a glass material. Semiconductor substrate.