JPH09148427A - Composite semiconductor substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lessen the warp of a substrate by providing a processing distortion layer on the main face on the side of a support substrate out of both main faces. SOLUTION: A separation groove is made on the surface of a semiconductor substrate 10 to become a semiconductor single crystal region 11, and next, an insulating film 12 is made on the surface of the semiconductor substrate 10. Soot-form matter 3 is made, and a support substrate 14 is laid on it, and they are heat-treated to laminate the semiconductor substrate 10 and the support substrate 14. The produced soot- form matter accumulates immediately on the surface of the semiconductor substrate 10 to be laminated. The soot-form matter is gasified when sintered, and laminates the semiconductor substrate 10 and the support substrate 14 with each other. Then, the support substrate 14 is mechanically polished to the line A from the opposite side of the lamination face, and a processing distortion layer 15 is left in the vicinity of the surface layer of polishing without performing a polishing process such as mechanochemical polishing, etc. For the thickness of the processing distortion layer 15, it is good to be 10μm or under, preferably, to be about 1-5μm in case that the thickness of the semiconductor single crystal region 11 is 0.1-300μm, and that the thickness of the glass matter layer is 0.5-100μm.

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 A dielectric isolation technique known as a method for isolating semiconductor single crystal regions from each other is a standard P / N method.
The isolation technique between devices is extremely good as compared with the junction isolation technique, and since there are few restrictions on the applied circuit, it is suitable for power ICs with high breakdown voltage and large current. A typical dielectric isolation method is EPIC (Epitaxial Passivated Integ
The rated circuit) method is known, but various methods are being studied in consideration of the large wafer diameter and manufacturing cost. 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. In a conventional substrate having a plurality of semiconductor single crystal regions manufactured by this kind of bonding method, a semiconductor single crystal island normally covered with an insulating film such as SiO ₂ is bonded to a supporting substrate by a glass material layer. Has been done.

[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.

Various methods are conceivable for reducing this warpage. 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.

[0007]

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. The present invention relates to a composite semiconductor substrate having a working strain layer on the main surface portion on the supporting substrate side of both main surfaces constituting the composite semiconductor substrate.

An advantage of the present invention is a structure capable of reducing the warpage of the dielectric isolation substrate having a structure in which glass substrates are bonded together.

The structure of the 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 usually covered with an insulating film 12. The semiconductor single crystal region 11 is bonded to the supporting substrate 14 via the glass material layer 13. According to the present invention, the warp of the substrate, which is caused by the difference in the thermal expansion coefficient between the semiconductor single crystal region 11, the glass material layer 13, and the supporting substrate 14, which has been a problem in the conventional technique, can be avoided. By providing the work strain layer 15 in the portion, the work strain layer 15 can be freely balanced and designed so as to eliminate the warp. The work strained layer 15 in the figure is shown in an enlarged manner.

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

The glass material layer 13 is preferably composed mainly of silicon, boron and oxygen. If the thickness of the glass material layer is too thin, it may not be completely joined, and if it is too thick, the joining strength will decrease, 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.

Needless to say, the same material as the semiconductor single crystal region 11 is suitable for the substrate 14 constituting the support substrate, but the support substrate 14 need not be the same material as the semiconductor single crystal region 11. , Good bondability with glass materials, no deterioration or deformation occurs during the bonding process,
A material that does not easily cause distortion in the joint surface after joining is selected.

In the present invention, in particular, as the supporting substrate 14, it is also a great feature that a material which gives a large warp to the substrate due to a difference in thermal expansion coefficient in the prior art or a material which is easily deteriorated during a device process can be used. Examples of usable materials include quartz glass, sapphire,
Alumina, a silicon carbide sintered body, magnesia, silicon nitride, heat resistant glass, etc. are mentioned.

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 the above description, the semiconductor single crystal regions are separated from each other, but in FIG.
1 is one, the insulating layer 12 and the glass material layer 13
It may be bonded to the support substrate 14 via.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an example of a method for manufacturing a 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. 2, it may be a trench or the like, and can be selected in consideration of a target device and manufacturing cost. As a manufacturing method, it 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 about 0.1 to 300 μm. Here, the semiconductor substrate 10
Since it 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, after the soot-like substance layer 3 is formed, the support substrate 14 is overlaid and then heat-treated to bond the semiconductor substrate 10 and the support substrate 14 together. The glass material layer 13 contains silicon, boron and oxygen as main components,
If desired, a phosphorus compound or a germanium compound may be contained therein. Although the composition and the manufacturing method of the glass material layer 13 may be different from each other, it is preferable that they are the same 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 mainly uses 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. This is a method in which a soot-like substance as a component is deposited on the surface of the semiconductor substrate 10, superposed on the support substrate 14, and then heat-treated and sintered to bond the semiconductor substrate 10 and the support substrate 14 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
No. ) 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 produce oxides of phosphorus and germanium by burning in an oxyhydrogen flame. Any compound may be used. Examples of the phosphorus compound include phosphorus pentachloride, phosphorus oxychloride (POCl ₃ ), phosphine (PH ₃ ), and the germanium compound includes 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 to 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. The deposition is preferably performed by directly spraying an oxyhydrogen flame onto the semiconductor substrate 10.

Next, the soot-like substance is sintered by heat treatment. Sintering is preferably carried out substantially in oxygen gas so that vacancies are not formed in the valleys of the grooves formed in the semiconductor substrate 10 as much as possible. That is, oxygen gas is 90% or more and helium gas is 2% or more.
% Or less, and other gases having no reactivity with the semiconductor substrate or the like are 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 support substrate 14 are bonded together.

After that, the support substrate 14 is mechanically ground from the side opposite to the bonding surface to the line A in FIG. 2, and a working strained layer is formed in the vicinity of the ground surface layer without performing a polishing process such as mechanochemical polishing that is usually performed. Leave 15 Then, the composite semiconductor substrate is manufactured by grinding the semiconductor substrate 10 from the side opposite to the bonding surface to the line B in FIG. 2 and further performing polishing such as mechanochemical polishing. If the semiconductor substrate used for bonding is a grooved substrate such as a V-shaped groove or trench groove, an island-shaped separated semiconductor single crystal region 11 is obtained through a grinding / polishing process.

The method of providing the processing strained layer 15 on the back surface of the support substrate 14 is not particularly limited, but a method by mechanical grinding, an ion implantation method, a plasma irradiation method, an ion beam processing method or the like is preferable. As a method of mechanical grinding, for example, a grindstone having a fine grain size or a surface plate to which abrasive grains having a fine grain size are attached is used for grinding. The grain size of the grindstone or grain used is preferably 200-2000.
Although the thickness of the work strained layer 15 is not particularly limited, when the thickness of the semiconductor single crystal region 11 is about 0.1 to 300 μm and the thickness of the glass substance layer is about 0.5 to 100 μm, the work strained layer 15 is not formed. The thickness is 10 μm or less, preferably 1 to
About 5 μm is good. Examples of the mechanical grinding method include a method using a rotary surface grinding machine using a cup grindstone constant-size cutting method.

Grinding of the semiconductor substrate 10 up to line B,
The polishing is performed by performing mechanical grinding in the same manner as in the case of the supporting substrate 14 described above, and then, by the mechanochemical polishing, the end portion is exposed where the tip of the V-shaped groove has a predetermined width and is exposed. .

[0031]

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. 1 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, thermal oxidation was performed to form SiO ₂ as an insulating film 12 on the surface of the V groove in a thickness of 1.5 μm.

Then, the gaseous S is adjusted so that the atomic ratio (Si / B) a of silicon to 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 substances obtained by decomposition are 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 silicon substrate 14 having a 6-inch diameter and a thickness of 625 μm having a plane orientation (100) plane separately prepared was stacked on the deposition of the soot-like substance 3, and 1280 ° C. in an oxygen atmosphere in a heating furnace.
When the temperature of the soot-like substance 3 was increased to 20 μm, the soot-like substance 3 volumetrically contracted to vitrify at the same time, and the two silicon substrates were evenly bonded to each other.

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. Further, when the cleaved surface of this substrate was observed with a scanning electron microscope, it was found that the 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, in consideration of the finished thickness of the support substrate 14, mechanical grinding was performed using a No. 1200 cup grindstone so as to have a thickness of 560 μm. Then, mechanical grinding was performed from a surface opposite to the surface where the silicon substrate 10 was bonded using a cup grindstone No. 1200 to obtain a predetermined thickness, and further polishing processing was performed using a mechanochemical polishing method, and the pieces were isolated from each other. The island-shaped semiconductor region 11 was formed. When the processing strained layer 15 on the ground surface of the support substrate 14 was obtained from the measurement value of the etching rate with the hydrofluoric nitric acid solution, the processing strained layer 15 was 1.5 μm in the depth direction, and the warp at this time was the semiconductor single crystal. When it was placed on a flat surface with the region facing upward, the central portion was convex to the upper side by 81 μm from the surroundings. Therefore, there is no trouble during transportation,
The yield in the photolithography process was also good.

Example 2 A composite semiconductor substrate was produced in the same manner as in Example 1 except that the back surface of the supporting substrate 14 was mechanically ground by lapping using a No. 1200 lapping platen. The warp at this time is
When placed on a flat surface with the semiconductor single crystal region facing up,
The central portion was convex to the upper side by 67 μm from the surroundings. Therefore, there was no trouble at the time of transportation, and the yield in the photolithography process was good.

Comparative Example 1 The same as Example 1 except that the back surface of the supporting substrate 14 was mechanically ground using a No. 1200 polishing cloth, and then the work strained layer 15 was removed by mirror polishing by the mechanochemical polishing method. A composite semiconductor substrate was manufactured in the same manner. When the work strain layer 15 on the ground surface of the support substrate 14 was measured, the work strain layer 15
Is almost zero in the depth direction, and the warp at this time is such that when placed on a plane with the semiconductor single crystal region facing upward, the central part is convex upward by 147 μm from the periphery. It was Therefore, there was no trouble at the time of transportation, and the yield in the photolithography process was good.

[0038]

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 the drawings]

FIG. 1 is a vertical cross-sectional view showing one embodiment of a composite semiconductor substrate of the present invention.

FIG. 2 is a diagram showing a manufacturing process of the composite semiconductor substrate of the present invention.

[Explanation of symbols]

 3 Soot Material Layer 10 Semiconductor Substrate 11 Semiconductor Single Crystal Region 12 Insulating Film 13 Glass Material Layer 14 Support Substrate 15 Processing Strained 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 support substrate supporting the semiconductor single crystal regions are bonded together by a glass substance. A composite semiconductor substrate having a work strain layer on the main surface portion of the surface on the side of the supporting substrate.