JP2004134675A - Soi substrate, manufacturing method thereof and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an adhered monocrystal silicon membrane from peeling off by improving the adhesion between a coating film on a substrate and the monocrystal silicon membrane to be coated. <P>SOLUTION: In an SOI substrate 1, an oxidized silicon film 3 on a light transmissive substrate 2 and an oxidized silicon film 4 formed over a monocrystal silicon membrane 5 are bonded. In ruggedness on a surface of the oxidized silicon film 3, a tangent of an angle formed with a surface of the light transmissive substrate 2 is ≤0.06. Besides, a contact angle of each of the oxidized silicon film 3 and the oxidized silicon film 4 with water is ≤10°. Further, an adhesive strength of the monocrystal silicon membrane 5 to the light transmissive substrate 2 is ≥0.6N/m, such that the adhered monocrystal silicon membrane 5 does not peel off. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an SOI (Silicon On Insulator) substrate, a display device, and a method for manufacturing an SOI substrate. More specifically, for example, a single crystal silicon piece into which hydrogen ions are implanted is bonded to the substrate, and hydrogen ions are implanted. The present invention relates to an SOI substrate provided with a single-crystal silicon thin film obtained by dividing layers, a display device using the same, and a method for manufacturing an SOI substrate.
[0002]
[Prior art]
The thin film transistor (Tin Film Transistor: TFT) technology is a technology in which a semiconductor film such as a silicon film is formed on a light-transmitting amorphous material such as a glass substrate and processed into a transistor. This TFT technology has been developed with the spread of personal information terminals using liquid crystal displays.
[0003]
In this TFT technology, for example, an amorphous silicon film on a substrate is melted by heat such as a laser to form a polysilicon (polycrystalline) film. The polysilicon film or the amorphous silicon film is processed to form a MOS type TFT as a switching element. Thus, a display panel such as a liquid crystal display panel or an organic EL panel is manufactured using a device (MOS TFT) formed from a silicon film. Then, the picture elements of the display panel are driven in an active matrix by the MOS type TFT.
[0004]
Such a configuration is used for a TFT-Liquid Crystal Display (LCD) device, a TFT-Organic Light Emitting Diode (OLED) display device, and the like.
[0005]
Here, in the active matrix driving of the switching elements, silicon devices with higher performance are required, and system integration of peripheral drivers, timing controllers, and the like is required.
[0006]
However, the target performance cannot be obtained with an amorphous silicon film or a polycrystalline silicon film used conventionally.
[0007]
This is because, in a polycrystalline silicon film or the like, there are localized levels in a gap due to imperfect crystallinity and localized levels in a defect gap near a crystal grain boundary. That is, when such a localized level exists, the mobility is reduced. In addition, an increase in the subthreshold coefficient (S coefficient) makes transistor performance insufficient, and a high-performance silicon device cannot be formed.
[0008]
In addition, if the crystallinity of the silicon film is incomplete, fixed charges are likely to be formed at the silicon-gate insulating film interface. Therefore, it becomes difficult to control the threshold voltage of the thin film transistor. In addition, a desired threshold voltage cannot be obtained.
[0009]
In a TFT-liquid crystal display, for example, a polycrystalline silicon film is obtained from an amorphous silicon film by heating with a laser beam or the like. Here, since the laser irradiation energy fluctuates to some extent, the grain size of the obtained polycrystalline silicon film is not constant. Therefore, large variations occur in the mobility and the threshold voltage.
[0010]
In the case where an amorphous silicon film formed by a plasma CVD (Chemical Vapor Deposition) method or the like is crystallized by heating with a laser beam, the melting point of silicon is instantaneously heated by heating around the silicon film. Increase to nearby temperature. Therefore, when alkali-free high-strain point glass is used as the substrate, alkali metals and the like diffuse from the glass into silicon. As a result, there is a problem that the obtained transistor characteristics deteriorate.
[0011]
On the other hand, apart from research for uniformity of crystallinity and high performance of polycrystalline silicon, research on devices using single crystal silicon has been conducted.
[0012]
An example of a device using such single crystal silicon is an SOI substrate. Here, SOI means Silicon @ on \ Insulator. The SOI technology for an SOI substrate mainly means a technology for forming a single crystal semiconductor thin film over an amorphous substrate. The term SOI technology is not often used when forming a polycrystalline silicon film. SOI technology is an area that has been actively studied since about 1980.
[0013]
As an example of the SOI substrate, there is a SIMOX (Silicon Implanted Oxygen) substrate. This SIMOX substrate is currently commercially available. The SIMOX substrate is formed by injecting oxygen into a silicon wafer. Here, since oxygen, which is a relatively heavy element, is implanted to a predetermined depth, the crystal of the silicon wafer is greatly damaged by the acceleration voltage at the time of implantation. Therefore, the SIMOX substrate has a problem that the properties of the single crystal obtained on the substrate are not sufficient. In addition, the insulation of the layer of the silicon dioxide film due to deviation from stoichiometry is incomplete. Further, since a large amount of oxygen implantation is required, there is a problem that the cost of ion implantation increases.
[0014]
On the other hand, in a method of manufacturing a thin semiconductor material film described in, for example, Japanese Patent Laid-Open Publication No. 5-211128 (publication date: August 20, 1993), a single-crystal silicon piece is used. On a silicon base substrate covered with a silicon oxide film to reduce the thickness of the substrate.
[0015]
According to this technique, an oxide film can be formed on a single crystal silicon base substrate, and a single crystal silicon thin film can be formed thereon.
[0016]
Japanese Patent Application Laid-Open Publication No. 2000-30996 (publication date: January 28, 2000) discloses a method of manufacturing an SOI wafer and an SOI wafer with respect to an oxide film thickness on a silicon wafer. The standard deviation of the film thickness variation is shown.
[0017]
In the method of manufacturing a semiconductor device described in Japanese Patent Laid-Open Publication No. Hei 6-268183 (publication date: Sep. 22, 1994), a semiconductor device is formed and thinned. A method for transferring a substrate to another supporting substrate is shown.
[0018]
In this method, after a semiconductor element is formed on one surface of the semiconductor layer, the thinned semiconductor layer and the supporting substrate are bonded by anodic bonding at room temperature.
[0019]
[Patent Document 1]
JP-A-5-211128
[0020]
[Patent Document 2]
JP-A-2000-30996
[0021]
[Patent Document 3]
JP-A-6-268183
[0022]
[Problems to be solved by the invention]
However, in the above-described configuration, unevenness caused by micro-roughness in the silicon oxide film on the substrate causes a problem of weakening the adhesive force, causing a problem such as film peeling.
[0023]
That is, according to the configuration disclosed in Japanese Patent Application Laid-Open No. 5-211128, when the oxide film on the silicon base substrate is thickened, the thickness variation becomes large. As a result, there is a problem that the surface unevenness becomes remarkable, which affects the adhesiveness at the time of bonding and the characteristics of the SOI substrate.
[0024]
JP-A-2000-30996 describes the film thickness uniformity of a single-crystal silicon thin film when the standard deviation of the film thickness variation becomes large. However, there is no mention of the problem that voids are generated at the time of bonding and that the silicon thin film is peeled at the time of separation / separation.
[0025]
Japanese Patent Application Laid-Open No. 6-268183 does not disclose the unevenness and flatness between the thinned semiconductor layer and the support substrate.
[0026]
As described above, the unevenness caused by the micro-roughness of the silicon oxide film coated on the light transmitting substrate becomes a factor of weakening the adhesive force. As a result, separation / separation occurs, resulting in a decrease in the non-defective product rate such as peeling of the film after the silicon film is formed on the substrate.
[0027]
The present invention has been made in view of the above problems, and an object of the present invention is to provide an SOI substrate, a display device, and a method of manufacturing an SOI substrate with improved adhesive strength.
[0028]
[Means for Solving the Problems]
The SOI substrate according to the present invention includes a bonding portion in which a coating film formed on a substrate and a coating film covering a single crystal silicon piece are bonded, and the single crystal silicon piece is formed by a hydrogen ion implanted layer. In an SOI substrate which is divided into a single-crystal silicon thin film, the substrate is a light-transmitting substrate, and the division is performed by heat treatment.
[0029]
In the SOI substrate, a single-crystal silicon piece is bonded to a substrate, and the single-crystal silicon piece is cut and separated by an injection layer to obtain a single-crystal silicon thin film. Thus, a single crystal silicon thin film having a constant crystal orientation of the silicon film can be formed. Further, a uniform and high-performance transistor having no variation can be obtained. In other words, a transistor in which a strict specification is required for variation and performance is achieved by achieving high performance such as suppression of non-uniformity of transistor characteristics (threshold voltage and mobility) and high mobility. can do.
[0030]
Further, since the substrate is a light-transmitting substrate, it can be used as an active matrix substrate of a display device.
[0031]
In addition, since hydrogen ions, whose mass is much lighter than oxygen ions, are implanted, the crystallinity of the entire surface of the single-crystal silicon piece is maintained so that it is not much different from that before implantation, and the problem of silicon crystallinity degradation due to oxygen ion implantation is solved. it can.
[0032]
In addition, the heat treatment can return the crystallinity of the single-crystal silicon thin film to a level equivalent to that before hydrogen ion implantation. This heat treatment is performed, for example, at a temperature of about 600 ° C. In this case, the adhesiveness of the joint does not deteriorate.
[0033]
In order to solve the above-mentioned problems, an SOI substrate according to the present invention includes a bonding portion formed by bonding a coating film formed on a substrate and a coating film covering a single-crystal silicon piece. In an SOI substrate in which a single crystal silicon thin film is cut off to form a single crystal silicon thin film, the bonding portion forms an unevenness having a height of 5 nm or less in a range of 1 to 5 μm square of the coating film surface with the substrate surface. It is characterized in that the above-mentioned coating film having a surface with an angle tangent of 0.06 or less is bonded.
[0034]
In the SOI substrate, a single-crystal silicon piece is bonded to a substrate, and the single-crystal silicon piece is cut and separated by an injection layer to obtain a single-crystal silicon thin film. Thus, a single crystal silicon thin film having a constant crystal orientation of the silicon film can be formed. Further, a uniform and high-performance transistor having no variation can be obtained. In other words, a transistor in which a strict specification is required for variation and performance is achieved by achieving high performance such as suppression of non-uniformity of transistor characteristics (threshold voltage and mobility) and high mobility. can do.
[0035]
Here, the tangent means a tangent, particularly an absolute value of the tangent. Therefore, the above configuration corresponds to the absolute value of the tangent being a value of 0 or more and 0.06 or less. The coating film has irregularities on the surface, and the tangent of the angle between the surface having the largest inclination of the irregularities and the substrate surface is 0.06 or less. More specifically, for example, for irregularities having a height of 5 nm or less measured in a range of 1 to 5 μm square on the surface of the coating film, the tangent of the angle formed by the largest inclined surface with the substrate surface may be about 0.06 or less. .
[0036]
When the irregularities are small as described above, the adhesive strength between the coating film and the coating film covering the single crystal silicon piece can be increased.
[0037]
It is more desirable that the tangent be a value of 0.04 or less. In this case, the adhesive strength between the coating film and the coating film covering the single crystal silicon piece can be further enhanced.
[0038]
This solves the problem that the micro-roughness of the light-transmitting substrate surface impairs the bonding between the light-transmitting substrate and the single-crystal silicon piece.
[0039]
Note that the surface state of the coating film for bonding the substrate and the single-crystal silicon piece in the SOI substrate is evaluated, for example, by using the AFM method for surface irregularities obtained by separating the substrate and the single-crystal silicon piece. be able to.
[0040]
In order to solve the above-mentioned problems, an SOI substrate according to the present invention includes a bonding portion formed by bonding a coating film formed on a substrate and a coating film covering a single-crystal silicon piece. Is divided into a single crystal silicon thin film, and the surface of the coating film and the surface of the coating film each have a contact angle with water of 10 ° or less.
[0041]
In the SOI substrate, a single-crystal silicon piece is bonded to a substrate, and the single-crystal silicon piece is cut and separated by an injection layer to obtain a single-crystal silicon thin film. Thus, a single crystal silicon thin film having a constant crystal orientation of the silicon film can be formed. Further, a uniform and high-performance transistor having no variation can be obtained. In other words, a transistor in which a strict specification is required for variation and performance is achieved by achieving high performance such as suppression of non-uniformity of transistor characteristics (threshold voltage and mobility) and high mobility. can do.
[0042]
Here, the coating film is, for example, a silicon oxide film coated on the substrate. The coating film is, for example, a silicon oxide film formed by oxidizing the single crystal silicon piece. Further, this water may be pure water or distilled water. Further, since the contact angle takes a value larger than 0 ° (in the case of complete wetting), the above configuration corresponds to a contact angle of 0 ° or more and 10 ° or less.
[0043]
The coating film and the coating film have a contact angle with water of 10 ° or less and have good wettability to water. Thus, surfaces with good wettability of water have good bonding properties to each other. Therefore, for example, even if the single crystal silicon piece is separated and separated by heat treatment after bonding the coating film and the coating film, the single crystal silicon thin film adhered to the substrate does not peel off. Therefore, an SOI substrate having excellent quality can be provided.
[0044]
More specifically, when joining the coating film and the covering film, the joining is performed without, for example, an adhesive. In such a case, the surface condition, surface cleanliness, and surface activity of each film are important. The bonding without the adhesive is realized by the contribution by the van der Waals force, the contribution by the electric dipole, and the contribution by the hydrogen bond. Then, when the surfaces to be bonded are similar in the balance of these contributions, it becomes easy to bond. According to the above configuration, the surfaces having good wettability to water are bonded to each other, so that the above-described contribution balance is similar, and the adhesiveness can be improved.
[0045]
In the above description, only the contact angle of each film with water is shown. Alternatively, the contact angle with ethylene glycol or a methylene iodide solution may be measured.
[0046]
The coating film and the coating film can be washed with, for example, a washing liquid obtained by diluting ammonia water and hydrogen peroxide solution with pure water. With such cleaning, particles on the surface can be removed before joining the coating film to the coating film, and a clean surface can be reliably obtained. Thereby, the contact angle with water on the surface can be more reliably suppressed to 10 ° or less.
[0047]
In order to solve the above-mentioned problems, an SOI substrate according to the present invention includes a bonding portion formed by bonding a coating film formed on a substrate and a coating film covering a single-crystal silicon piece. Wherein the coating film is a silicon oxide film formed by a plasma-enhanced chemical vapor deposition method using a mixed gas of TEOS gas and oxygen gas It is characterized by.
[0048]
In the SOI substrate, a single-crystal silicon piece is bonded to a substrate, and the single-crystal silicon piece is cut and separated by an injection layer to obtain a single-crystal silicon thin film. Thus, a single crystal silicon thin film having a constant crystal orientation of the silicon film can be formed. Further, a uniform and high-performance transistor having no variation can be obtained. In other words, it is possible to suppress the non-uniformity of the transistor characteristics (threshold voltage and mobility) and achieve high performance such as high mobility, and to manufacture a transistor in a part where strict specifications are required for variation and performance. can do.
[0049]
Here, TEOS gas means Tetra \ Ethyl \ Ortho \ Silicate gas.
[0050]
As described above, if the film is formed by the plasma enhanced chemical vapor deposition method using the TEOS gas and the oxygen gas, the obtained coating film can be easily bonded to the coating film. On the other hand, when a coating film is formed by, for example, a sputtering method, it becomes difficult to bond with the coating film.
[0051]
In order to solve the above-mentioned problems, an SOI substrate according to the present invention includes a bonding portion formed by bonding a coating film formed on a substrate and a coating film covering a single-crystal silicon piece. In the SOI substrate in which a single-crystal silicon thin film is cut off, the bonding portion is formed by bonding the coating film made of silicon oxide and having a thickness of 5 nm to 300 nm.
[0052]
In the SOI substrate, a single-crystal silicon piece is bonded to a substrate, and the single-crystal silicon piece is cut and separated by an injection layer to obtain a single-crystal silicon thin film. Thus, a single crystal silicon thin film having a constant crystal orientation of the silicon film can be formed. Further, a uniform and high-performance transistor having no variation can be obtained. In other words, it is possible to suppress the non-uniformity of the transistor characteristics (threshold voltage and mobility) and achieve high performance such as high mobility, and to manufacture a transistor in a part where strict specifications are required for variation and performance. can do.
[0053]
The coating film is a silicon oxide film having a thickness of 5 nm to 300 nm. The joining portion is formed by joining the coating films. According to this structure, since the silicon oxide film has a large thickness, the silicon oxide film is less susceptible to the fixed charges on the surface of the light transmitting substrate, and the characteristics of the transistor formed on the single crystal silicon thin film of the SOI substrate can be improved. More specifically, even if a fixed charge is formed at the silicon-gate insulating film interface, the fixed charge does not affect the single crystal silicon thin film, so that appropriate threshold voltage control of the thin film transistor can be performed, and Can be obtained.
[0054]
It is more desirable that the thickness of the coating film is 40 nm to 300 nm. With this thickness, the effect of the fixed charges on the surface of the light-transmitting substrate can be reliably suppressed, and the transistor characteristics can be reliably improved.
[0055]
In order to solve the above-mentioned problems, an SOI substrate according to the present invention includes a bonding portion formed by bonding a coating film formed on a substrate and a coating film covering a single-crystal silicon piece. In an SOI substrate in which a single crystal silicon thin film is divided to form a single crystal silicon thin film, the bonding strength of the bonding portion is 0.6 N / m or more.
[0056]
In the SOI substrate, a single crystal silicon piece is bonded to a substrate, and the single crystal silicon piece is separated and separated to obtain a single crystal silicon thin film. Thus, a single crystal silicon thin film having a constant crystal orientation of the silicon film can be formed. Further, a uniform and high-performance transistor having no variation can be obtained. In other words, it is possible to suppress the non-uniformity of the transistor characteristics (threshold voltage and mobility) and achieve high performance such as high mobility, and to manufacture a transistor in a part where strict specifications are required for variation and performance. can do.
[0057]
Here, the adhesive force is a force per unit length necessary for peeling a thin layer from an object against a surface traction force.
[0058]
Thus, if the adhesive strength is increased, the peeling of the adhesive can be prevented. Here, for example, according to the conventional configuration, the adhesive force of the above-mentioned joint has a value of about 0.2 N / m. However, according to the configuration of the present invention, the adhesive strength is 0.6 N / m or more, and peeling of the adhesive can be prevented.
[0059]
Here, the evaluation of the adhesive force is performed after the bonding and before the strengthening of the adhesive force by a heat treatment or the like. That is, for example, by further performing a heat treatment thereafter, the adhesive strength can be improved by several orders of magnitude.
[0060]
According to another embodiment of the invention, there is provided a display device including any one of the above-described SOI substrates on which a semiconductor element structure is formed.
[0061]
Since the SOI substrate is a light-transmitting substrate, if a semiconductor element structure is formed on this substrate, it can be suitably used as, for example, an active matrix substrate used for a display panel.
[0062]
In addition, since a uniform and high-performance transistor can be obtained without variation using the SOI substrate, a high-performance display device can be provided using the transistor.
[0063]
As described above, transistor characteristics can be made uniform, stable, and high-performance by using single-crystal silicon. For example, a high-performance MOS field-effect transistor device can be manufactured. Accordingly, a high-performance TFT-LCD display device, TFT-OLEDL display device, or integrated circuit can be manufactured using this.
[0064]
The semiconductor element structure means, for example, a structure as a switching element for a display. Further, for example, a data processing driver may be manufactured by forming a semiconductor element structure on an SOI substrate.
[0065]
In addition, the display device includes, for example, a light-transmitting substrate whose surface is coated with a silicon oxide film and a single-crystal silicon piece whose surface is oxidized, which are separated from each other by heat treatment. It can also be described as a display device provided with a display switching element, a data processing driver, and the like manufactured using the SOI substrate manufactured as described above.
[0066]
In order to solve the above problem, a method for manufacturing a semiconductor device according to the present invention includes a bonding step of bonding a coating film formed on a substrate and a coating film covering a single crystal silicon piece. The manufacturing method is characterized in that, prior to the bonding step, an adjusting step of adjusting the surface of the coating film so that a tangent of an angle between the coating film and the substrate surface is 0.06 or less is included.
[0067]
In the SOI substrate, after the bonding step, the single crystal silicon piece is cut and separated at the hydrogen ion implantation layer to form a single crystal silicon thin film, and the SOI substrate is manufactured.
[0068]
Here, according to the above-described manufacturing method, after adjusting the unevenness of the surface of the coating film so that the tangent of the angle between the coating film and the substrate surface is 0.06 or less, the coating film coated with the coating film and the single-crystal silicon piece is formed. Since the film is bonded to the cover film, good bonding properties can be provided, and the strength of this bonding can be increased. Therefore, when the single-crystal silicon piece is divided and separated after the bonding step to form a single-crystal silicon thin film, film separation does not occur.
[0069]
On the other hand, when those having a tangent of 0.06 or more were joined, the adhesive strength at the joint was 0.2 N / m or less. In this case, after peeling / separation annealing was performed, film peeling was partially observed.
[0070]
In the adjustment step, for example, it is desirable to appropriately set the film thickness of the coating film on the substrate and to appropriately set the film forming conditions. By appropriately setting these conditions, a state where the tangent of the angle between the coating film and the substrate surface is 0.06 or less can be realized more reliably. Note that it is preferable that the thickness of the coating film is relatively small. For example, when a silicon oxide film as a coating film is formed to be thicker than 500 nm, it is preferable to perform polishing after the formation. For example, the thickness of the silicon oxide film may be about 100 nm.
[0071]
It is also preferable that the tangent of the angle between the coating film and the substrate surface is 0.04 or less. According to this state, film peeling can be more reliably prevented.
[0072]
Further, in the above configuration, it is also preferable that the configuration further includes a step of setting the coating film and the coating film so that a contact angle with water is 10 ° or less.
[0073]
According to this configuration, it is possible to improve the adhesiveness between the coating film and the coating film, reliably increase the adhesive force, and realize a method for manufacturing an SOI substrate in which film peeling is less likely to occur.
[0074]
In addition, in the method for manufacturing an SOI substrate, the temperature of a hydrogen ion implantation region of a single crystal silicon piece is raised to a temperature higher than a temperature at which hydrogen is released from silicon by light irradiation including laser or the like, and the single crystal silicon piece is subjected to hydrogen ion irradiation. It can also be described as a method for manufacturing an SOI substrate including a step of dividing along an implantation surface.
[0075]
With the above structure, the temperature of the hydrogen ion implanted region of the single crystal silicon piece is further increased by light irradiation including a laser or the like. Can be suppressed.
[0076]
In addition, the method for manufacturing an SOI substrate is described as a method for manufacturing an SOI substrate including a step of performing lamp annealing including a peak temperature of approximately 850 ° C. or higher and dividing a single crystal silicon piece along a hydrogen ion implantation region. You can also.
[0077]
According to the above configuration, lamp annealing, which is an instantaneous thermal annealing (Rapid Thermal Anneal, hereinafter referred to as RTA) including a peak temperature of approximately 850 ° C. or more, is further performed, and the single crystal silicon piece is placed along the hydrogen ion implanted region. The separation can further improve the bonding strength, and can recover the damage due to hydrogen ion implantation at the separation interface and inside the single-crystal silicon thin film to improve the characteristics of the transistor.
[0078]
Note that the higher the peak temperature of the lamp annealing, the higher the characteristics of the transistor, but the larger the warpage and expansion / contraction of the substrate. Therefore, for example, when the substrate size is about 300 mm square, annealing is performed at a temperature of about 700 ° C. and a holding time of about 5 minutes.
[0079]
Further, the method for manufacturing an SOI substrate is characterized in that a hydrogen ion whose mass is much lighter than that of oxygen ions is implanted, so that the SOI substrate is kept not much different from before implanting crystalline material on the entire surface of the single crystal silicon piece. It can be described as a method.
[0080]
With the above structure, by performing a heat treatment at a temperature of about 600 ° C. in the TFT manufacturing process after the separation, the crystallinity of the single crystal silicon film can be returned to a level equivalent to that before hydrogen ion implantation. Therefore, the crystallinity of silicon does not decrease as in the case where oxygen ions are implanted.
[0081]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to FIGS.
[0082]
As shown in FIG. 1, a SOI (Silicon @ Insulator) substrate 1 of the present embodiment is formed by bonding a light-transmitting substrate (substrate) 2 and a single-crystal silicon thin film 5 to each other.
[0083]
More specifically, a silicon oxide film (coating film) 3 is laminated on the light transmitting substrate 2. The light-transmitting substrate 2 is, for example, a light-transmitting amorphous high-strain-point alkali-free glass substrate, and for example, uses an alkaline earth-aluminoborosilicate glass such as Corning (registered trademark) # 1737 glass manufactured by Corning. be able to. The single crystal silicon thin film 5 is covered with a silicon oxide film (coating film) 4. Then, a bonding portion in which the silicon oxide film 3 and the silicon oxide film 4 are bonded to each other is formed.
[0084]
A procedure for forming such an SOI substrate 1 will be described with reference to FIG.
[0085]
A silicon oxide film 3 is formed on the light transmitting substrate 2 shown in FIG. As a result, as shown in FIG. 2B, a state where the silicon oxide film 3 is laminated on the light transmitting substrate 2 is obtained. The silicon oxide film 3 is provided in this manner because the light-transmitting substrate 2 has insufficient wettability (hydrophilicity) as it is.
[0086]
The silicon oxide film 3 is formed to a thickness of about 100 nm. This silicon oxide film 3 is preferably formed to a thickness of, for example, about 40 to 300 nm. The method of film formation is not particularly limited. For example, TEOS (Tetra Ortho Silicate) gas and oxygen gas are mixed in a vacuum chamber by a plasma chemical vapor deposition method (plasma CVD (Chemical Vapor Deposition) method), and the plasma is discharged at a temperature of about 320 ° C. by plasma discharge. Forming about 100 nm (TEOS-O₂Plasma method).
[0087]
In addition, since the silicon oxide film 3 is formed under thermal non-equilibrium at a relatively low temperature (300 to 400 ° C.), the composition ratio between silicon and oxygen does not become exactly 1: 2, for example, 1: 2. It is about 1.9. That is, the silicon oxide film 3 of the present embodiment is a so-called silicon oxide film,₂This is a system insulating film. Note that, for example, when oxidized at about 900 ° C., the reaction occurs under thermal equilibrium, and the composition ratio between silicon and oxygen becomes 1: 2.
[0088]
At this time, as for the unevenness on the surface of the silicon oxide film 3, the tangent (tangent) of the angle between the maximum inclined surface of the unevenness and the substrate plane is 0.06 or less. More specifically, for example, for irregularities having a height of 5 nm or less measured in a range of 1 to 5 μm square on the surface of the silicon oxide film 3, the tangent of the angle between the maximum inclined surface and the surface of the light transmitting substrate 2 is about 0. 0.06 or less. The surface irregularities will be described later.
[0089]
On the other hand, the single-crystal silicon thin film 5 shown in FIG. 1 is formed from the single-crystal silicon piece 6 shown in FIG.
[0090]
The surface of the single-crystal silicon piece 6 is thermally oxidized, and is covered with a silicon oxide film 4 as shown in FIG. The oxide film thickness of the silicon oxide film 4 is about 100 nm. The oxide film thickness of the silicon oxide film 4 is preferably 5 nm to 300 nm. More preferably, the oxide film thickness is 40 to 300 nm. This silicon oxide film 4 is made of SiO₂This is a system insulating film.
[0091]
Next, as shown in FIG. 2E, hydrogen ions indicated by arrows are implanted into a predetermined surface (hydrogen ion implanted surface) of the single crystal silicon piece 6. Here, as shown in FIG. 2E, the hydrogen ion implantation implantation surface (hydrogen ion implantation layer) 10 is set to a predetermined depth.
[0092]
Next, as shown in FIG. 2 (f), the light transmitting substrate 2 shown in FIG. 2 (c) and the single crystal silicon piece 6 shown in FIG. After drying, attach. Here, each of the washing and the drying will be described.
[0093]
In this embodiment, the light-transmitting substrate 2 coated with the silicon oxide film 3 as a coating film and the single-crystal silicon piece 6 whose surface is oxidized to cover the silicon oxide film 4 are bonded without using an adhesive. Join. For this purpose, the surface condition, surface cleanliness, and surface activity of each film are extremely important.
[0094]
Such bonding without an adhesive is realized by contribution by van der Wals force, contribution by electric dipole, and contribution by hydrogen bonding. Here, when the surfaces of the substrates to be bonded are similar in the balance of the above three contributions, it is particularly easy to bond and join.
[0095]
Therefore, the light-transmissive substrate 2 coated with the silicon oxide film 3 and the single-crystal silicon piece 6 whose surface is oxidized to cover the silicon oxide film 4 are first washed with SC1 solution.
[0096]
SC1 solution is a commercially available ammonia water (NH₄OH: 30% solution) and hydrogen peroxide solution (H₂O₂: 30% solution) and pure water (H₂O) at a predetermined ratio. As an example, each of the above chemical solutions is mixed at a ratio of 5:12:60.
[0097]
The light transmitting substrate 2 and the single crystal silicon piece 6 are immersed in the SC1 liquid thus prepared for 10 minutes.
[0098]
As described in, for example, Ultra Clean ULSI Technology (Tadahiro Omi, Baifukan, p. 172), ammonia water slick-etches the silicon oxide surface, so it is not preferable to soak for a long time.
[0099]
Thereafter, washing is performed for 10 minutes with running water using pure water, and the washing is completed. This pure water has, for example, a specific resistance value of 10 MΩcm or more. Then, it is dried quickly by a spin dryer or the like.
[0100]
Next, when the single-crystal silicon piece 6 is cut to form the single-crystal silicon thin film 5, annealing at 600 ° C. for 30 minutes using an electric furnace or heat treatment by lamp annealing is performed. As a result, as shown in FIG. 2 (g), the single-crystal silicon piece 6a is separated and separated from the hydrogen ion implantation implantation surface 10, and the SOI substrate 1 including the single-crystal silicon thin film 5 is formed. In this case, the adhesiveness of the joint does not deteriorate.
[0101]
The single-crystal silicon thin film 5 on the surface of the SOI substrate 1 is set so that the silicon film thickness is preferably 300 nm. In addition, the orientation of the substrate surface of the single crystal silicon thin film 5 is set to be (100), (110), or (111). In this way, a sufficiently flat surface having a mirror surface can be obtained. That is, an SOI substrate having a silicon film surface that is so flat that surface polishing is not required can be manufactured.
[0102]
Here, the surface state of the silicon oxide film 3 shown in FIG. 2B will be described with reference to FIG.
[0103]
As shown in FIG. 3, the silicon oxide film 3 on the light transmitting substrate 2 has irregularities on the surface. This surface image is data obtained by extracting irregularities in a specific linear cross section from an AFM (Atomic Force Microscope) image of the surface of the silicon oxide film 3.
[0104]
In the silicon oxide film 3 of the present embodiment, the maximum inclination angle due to surface irregularities has a tangent (tangent) of 0.04 or less with respect to the angle formed with the substrate surface. Here, the surface of the light transmissive substrate 2 is parallel to a dotted line indicating a height of 0 in FIG.
[0105]
When the silicon oxide film 3 thus formed and the single crystal silicon piece 6 covered with the silicon oxide film 4 are dried and bonded after SC1 cleaning and pure water cleaning, the silicon oxide film 3 and the silicon oxide film 4 are bonded together. Was joined with a slight force. Here, at the time of bonding, if force was applied only at the beginning, spontaneous bonding took place thereafter. Such spontaneous bonding is hereinafter referred to as having self-bonding properties.
[0106]
Here, FIG. 7 shows an example of a cross section of a silicon oxide film on a substrate in a conventional configuration, for example. In this case, a silicon oxide film having a thickness of 500 nm or more was formed on the substrate. As shown in FIG. 7, the tangent of the angle formed by the maximum slope of the surface irregularities with the substrate surface is 0.06 or more. In this case, the absolute value of the surface irregularities of the conventional silicon oxide film (fluctuation in the vertical direction from the substrate surface) is, for example, about the same as the absolute value of the surface irregularities of the silicon oxide film 3 of the present embodiment shown in FIG. It is smaller.
[0107]
Here, when the substrate on which the silicon oxide film was stacked as shown in FIG. 7 was bonded to a single crystal silicon piece, the bonding was not successfully performed. That is, when the tangent of the angle formed by the maximum inclination angle of the surface irregularities to the substrate surface was 0.06 or more, the substrate did not have self-bonding property.
[0108]
The silicon oxide film 4 on the single crystal silicon piece 6 is obtained by forming a thermal oxide film on the originally flat single crystal silicon piece 6 by thermal equilibrium. That is, for example, a commercially available single crystal silicon piece 6 has flatness as a specification. For this reason, the flatness when a coating film having a predetermined thickness is formed can be predicted to some extent. The silicon oxide film 4 has a certain degree of flatness up to a thickness of about 500 nm.
[0109]
As described above, a sufficient adhesive force cannot be obtained even if a measure such as improving the washing conditions before the adhesive is taken against the decrease in the adhesive force caused by the surface unevenness due to the micro roughness. Therefore, peeling of the single crystal silicon thin film in peeling / separation cannot be avoided. That is, cleaning alone may not be sufficient.
[0110]
Next, such a substrate on which a silicon oxide film having a tangent of the maximum inclination angle of the surface unevenness of 0.06 or more is laminated is subjected to surface polishing by a chemical mechanical polishing (CMP) method or the like. went. This makes it possible to make the coated silicon oxide film have a tangent of the angle between the maximum inclination angle of the surface irregularities and the substrate surface smaller than 0.06, preferably 0.04. In this case, the substrate on which the silicon oxide film was laminated and the single crystal silicon piece were bonded and joined.
[0111]
Here, the wettability to water of the light transmissive substrate 2 coated with the silicon oxide film 3 of the present embodiment was measured after cleaning with the SC1 cleaning liquid. Specifically, as shown in FIG. 4, the contact angle θ with respect to water W was measured using a contact angle measuring device.
[0112]
Using a contact angle measuring device, an image at the moment when the water W was dropped on the surface of the silicon oxide film 3 was taken from the cross-section observation direction. Here, the angle formed by the tangent (dotted line) at the position where the end of the water droplet is in contact with the surface of the silicon oxide film 3 and the surface of the light transmitting substrate 2 was measured as the contact angle θ.
[0113]
The light transmitting substrate 2 and the dripping water W were set at 25 ° C. The contact angle θ was measured from the image immediately after dropping. The amount of water dropped was 1 microliter. As the water W to be dropped, “distilled water for injection” manufactured by Otsuka Pharmaceutical Co., Ltd. was used.
[0114]
In the light transmitting substrate 2 having the surface unevenness as shown in FIG. 3 and coated with the silicon oxide film 3 of the present embodiment, a contact angle θ of 10 ° or less with water W was measured after the SC1 cleaning. In this case, as described above, the tangent of the angle formed between the silicon oxide film 3 and the maximum inclination angle of the surface irregularities of the light transmitting substrate 2 was 0.04 or less.
[0115]
Further, the wettability of the single crystal silicon piece 6 subjected to the oxidation treatment and covered with the silicon oxide film 4 was measured in the same manner as in the light transmitting substrate 2. Also in this case, a contact angle θ of 10 ° or less with respect to water W was measured after SC1 cleaning.
[0116]
Then, as described above, when the silicon oxide film 3 and the silicon oxide film 4 were bonded to each other after drying, they were bonded with a small force and with a self-bonding property.
[0117]
Here, the adhesion (adhesion) after bonding can be estimated as follows. That is, the evaluation of the adhesive strength can be performed by a test in which the adhered thin film is peeled from the end portion. According to "Elasticity Theory" by Eri de Landau-Jem Lifshitz (translated by Tozo Satoh, Tokyo Book), a thin layer of thickness h is departed from the object against the surface traction on the peeling surface. When peeled off by an external force acting on this, the adhesive force α per unit length is
α = ｛Eh³/ 24 (1-σ²)｝ (∂²ζ / ∂x²)²
Is represented by
[0118]
Here, E: Young's modulus of the thin film, σ: Poisson's ratio of the thin film, h: Thickness of the thin film, x: Lateral axis of the plane where the thin film adheres, ζ: Peeling off in the normal direction of the thin film This is the displacement of the film that is about to be performed. This situation is shown in FIG. 8 as a schematic sectional view. As shown in FIG. 8, the gap thickness at coordinates that have moved laterally by a distance x from the end of the bonding surface (x = 0) is ζ, and ζ and x are variables. In FIG. 8, the tape T plays a role of giving a force for peeling the thin layer 29 from the object 28. That is, when the thin layer 29 is peeled off from the object 28 using, for example, the tape T, the second order differential of the displacement ζ from the bonding surface of the thin layer 29 contributes to the adhesive force. As described above, the adhesive force α can be obtained by calculating the second-order partial derivative of the displacement in the normal direction of ζ with respect to the x-axis.
[0119]
Here, as shown in FIG. 2 (f), the light-transmitting substrate 2 and the single-crystal silicon piece whose tangent (tangent) of the angle formed by the surface irregularities to the substrate surface is 0.06 or less are used. In the case where No. 6 was bonded, the adhesive strength was evaluated by the above method. In this case, a large value of 0.6 N / m or more was obtained as the adhesive force.
[0120]
On the other hand, for example, when the tangent (tangent) of the angle formed by the surface irregularities to the substrate surface is 0.06 or more, it is not self-joining, and the adhesive force in this case is 0.2 N / m. Only about a value was obtained.
[0121]
Here, the evaluation of the adhesive force is performed after the bonding and before the strengthening of the adhesive force by a heat treatment or the like. That is, for example, by further performing a heat treatment thereafter, the adhesive strength can be improved by several orders of magnitude. As described above, the SOI substrate 1 of the present embodiment has an adhesive strength of 0.6 N / m or more after the bonding of the silicon oxide film 3 and the silicon oxide film 4 and before the enhancement of the adhesive strength by heat treatment or the like. This is the configuration. Therefore, for example, a larger adhesive force can be obtained even after the heat treatment, as compared with a case where the heat treatment is performed on an SOI substrate having an adhesive force of about 0.2 N / m after bonding.
[0122]
Further, as described above, the silicon oxide film 3 which is a coating film of the light-transmitting substrate 2 is formed at a temperature of about 320 ° C. by a plasma chemical vapor deposition method in which a mixed gas of a TEOS gas and an oxygen gas flows to form a film. It was made. That is, the silicon oxide film 3 formed by the plasma-enhanced chemical vapor deposition method is a film that is easily bonded to the silicon oxide film 4 as the coating film.
[0123]
On the other hand, such a coating film was produced by a sputtering method in which an Ar gas and an oxygen gas were flowed through a silicon oxide target and RF reactive sputtering was performed. In this case, the tangent of the angle formed by the surface roughness due to the microroughness was about 0.06 or more. Further, the contact angle θ with water W was 10 ° or more. Further, in this case, even when the substrate on which the coating film is laminated and the single-crystal silicon piece are bonded to each other, no bonding was performed with self-bonding properties.
[0124]
As described above, in the SOI substrate 1 of the present embodiment, the silicon oxide film 3 having the surface irregularities whose tangent to the angle formed with the surface of the light transmitting substrate 2 is 0.06 or less is used as the coating film. And the silicon oxide film 4 of FIG.
[0125]
The SOI substrate 1 has a configuration in which the surface of the silicon oxide film 3 and the surface of the silicon oxide film 4 have a contact angle θ with water W of 10 ° or less.
[0126]
The SOI substrate 1 has a configuration in which the silicon oxide film 3 is formed by a plasma enhanced chemical vapor deposition method using a mixed gas of a TEOS gas and an oxygen gas.
[0127]
According to these configurations, the adhesive force between silicon oxide film 3 and silicon oxide film 4 can be made 0.6 N / m or more. Since the SOI substrate 1 has a configuration in which the adhesive strength is increased in this way, film peeling does not occur. In addition, since film peeling does not occur, the yield can be improved and the cost can be reduced.
[0128]
Here, in order to join the silicon oxide film 3 and the silicon oxide film 4, the surface condition, surface cleanliness, and surface activity of each film are important. Such a junction is realized by a contribution by van der Wals force, a contribution by electric dipole, and a contribution by hydrogen bonding. Then, when the surfaces to be bonded are similar in the balance of these contributions, it becomes easy to bond. According to the above configuration, the balance of these contributions can be made similar between the surfaces to be bonded. Therefore, the adhesive strength can be improved as described above.
[0129]
Modifications according to the embodiment of the present invention will be described below with reference to FIGS.
[0130]
Hereinafter, as a modified example of the above-described embodiment, an example of an SOI substrate including a polycrystalline silicon film in addition to a single crystal silicon thin film on a substrate will be described. In this case, for example, a polycrystalline silicon film is formed on a part of the substrate, and thereafter, a single crystal silicon is partially formed.
[0131]
To manufacture the SOI substrate as described above, first, a silicon oxide film 13 as an insulating film is laminated on the light transmitting substrate 2 shown in FIG. 5A as shown in FIG. 5B.
[0132]
Next, as shown in FIG. 5C, an amorphous silicon film 14 is formed by flowing a monosilane gas and a hydrogen gas by a plasma enhanced chemical vapor deposition method.
[0133]
Then, dehydrogenation annealing is performed, and thereafter, as shown in FIG. 5D, a portion where the polycrystalline silicon TFT is formed is melted by irradiation with an excimer laser indicated by an arrow. Thereafter, the melted region is polycrystallized, and a polysilicon film 14a is formed as shown in FIG.
[0134]
Next, the silicon film is etched to remove the polysilicon film 14b by photolithography in order to form a portion for mounting the single crystal silicon piece. The remaining polysilicon film 14a is used as the polysilicon region 12 as shown in FIG. Then, after washing with SC1 solution / pure water, it is dried.
[0135]
On the other hand, the surface of the single crystal silicon piece 6 is also oxidized to form a silicon oxide film 4, hydrogen ions are implanted, washed with SC1 solution / pure water, and then dried. Then, as shown in FIG. 5 (g), the silicon oxide film 4 of the single crystal silicon piece 6 is bonded to the silicon oxide film 13.
[0136]
Thereafter, similarly to the above-described embodiment, heat treatment is performed in an electric furnace or a lamp furnace to separate and separate the single-crystal silicon piece 6 from the hydrogen ion implantation implantation surface 10 as shown in FIG. Thus, a single-crystal silicon thin film 5 is obtained.
[0137]
Here, if the thickness of the single crystal silicon thin film 5 is set to be equal to that of the polysilicon region 12, it is very useful in a TFT forming process using the polysilicon region 12 and the single crystal silicon film 5. It is.
[0138]
Here, since the SOI substrates 1 and 11 prepared as described above are light-transmitting substrates, they can be particularly easily used for a display device. For example, a thin film transistor is formed using the single crystal silicon thin film 5. Then, the thin film transistor can be used for a display device such as a TFT liquid crystal display (LCD: Liquid Crystal Display) device, a TFT organic electroluminescence (OLED: Organic Light Emitting Diode) display device, and the like.
[0139]
As described above, when the SOI substrates 1 and 11 are used as the display panel driven by the active matrix, uniformity, stability, and high performance of the transistor can be achieved. Further, it becomes possible to integrate a system such as a peripheral driver and a timing controller from an active matrix driver.
[0140]
The procedure for manufacturing a thin film transistor (TFT) using the SOI substrates 1 and 11 is the same as that of a normal TFT process.
[0141]
For example, in order to make a coplanar transistor, a silicon film is made into islands from the SOI substrates 1 and 11, and as shown in FIG.₂A gate insulating film 22 which is a system insulating film is formed.
[0142]
Subsequently, after the gate electrode film 23 is formed and patterned, phosphorus or boron is ion-implanted to form the low-resistance silicon film 24 (n⁺Type or p⁺Mold silicon film) is partially obtained. After activation annealing by heat, SiO 2₂An interlayer insulating film 26 as a system insulating film is formed. The portion masked by the gate electrode film 23 becomes the channel region 25.
[0143]
After opening a contact hole in the interlayer insulating film 26, a source / drain metal film 27 is formed and patterned.
[0144]
In this manner, as shown in FIG. 6, a single crystal silicon TFT or a partial single crystal silicon TFT, which is the thin film transistor 21, can be manufactured.
[0145]
As described above, the present invention relates to a silicon semiconductor used for manufacturing an integrated circuit or a thin film transistor, and a single crystal silicon thin film or a single crystal as a semiconductor material forming a transistor among transistor devices manufactured from the silicon semiconductor. The present invention relates to a material for a transistor element using a silicon film and a non-single-crystal silicon film, and more particularly to a method for manufacturing an SOI substrate, a display device, and an SOI substrate.
[0146]
Here, an integrated circuit element technology for forming an element structure such as a transistor on a substrate by integration is developed with the spread of computers.
[0147]
In this integrated circuit device technology, for example, a single crystal silicon substrate is processed to form about several hundred million transistors on the substrate. Specifically, a commercially available single crystal silicon wafer having a thickness of less than 1 mm and a diameter of about 200 mm is processed, and a large number of transistors are formed thereon.
[0148]
The purpose of SOI substrates used in the field of integrated circuits is to fabricate good transistors and dramatically improve the function of semiconductor elements. Therefore, the substrate only needs to be an insulating film. May be opaque, crystalline or amorphous. In this field, when a transistor is formed using an SOI substrate, the elements are completely separated from each other, so that there are few restrictions on operation and good characteristics and high performance as a transistor are exhibited.
[0149]
On the other hand, when an SOI substrate is used for the display device according to the present invention, it is desirable that the SOI substrate be light-transmissive as described above.
[0150]
Further, in the configuration described in JP-A-2000-30996, when a single-crystal silicon film is formed on a light-transmitting substrate by bonding, separation, and separation, the size of the single-crystal silicon piece is not necessarily the size of the glass substrate. And the maximum diameter was about 12 inches (300 mm). Therefore, according to this configuration, there is a problem that a single-crystal silicon thin film cannot be formed on the entire surface of the substrate.
[0151]
On the other hand, in the SOI substrate according to the present invention, a single-crystal silicon thin film can be formed over almost the entire surface of the substrate, as in the above-described SOI substrate 1.
[0152]
The present invention is not limited to the above-described embodiments, but can be variously modified within the scope shown in the claims, and can be obtained by appropriately combining the technical means disclosed in the embodiments. Is also included in the technical scope of the present invention.
[0153]
The specific embodiments described above are merely for clarifying the technical contents of the present invention, and the present invention is not limited to such specific examples and should not be construed in a narrow sense. Various modifications are possible within the scope of the claims, and the modified embodiments are also included in the technical scope of the present invention.
[0154]
【The invention's effect】
As described above, the SOI substrate according to the present invention has a configuration in which the substrate is a light transmissive substrate and the division is performed by heat treatment.
[0155]
Therefore, there is an effect that a uniform and high-performance transistor without variation can be provided. Further, since the substrate is a light-transmitting substrate, an effect is obtained that the substrate can be used as an active matrix substrate of a display device. Also, there is an effect that the heat treatment does not deteriorate the adhesiveness of the joint.
[0156]
As described above, in the SOI substrate according to the present invention, as for the bonding portion, the tangent of the angle between the substrate surface and the unevenness having a height of 5 nm or less measured in the range of 1 to 5 μm square is 0. This is a configuration in which a coating film having a surface of not more than 06 is bonded.
[0157]
Therefore, since the surface unevenness is small, an effect that the adhesive strength between the coating film and the coating film covering the single crystal silicon piece can be enhanced can be obtained.
[0158]
As described above, the SOI substrate according to the present invention has a configuration in which the surface of the coating film and the surface of the coating film each have a contact angle with water of 10 ° or less.
[0159]
Therefore, since the coating film and the coating film have good wettability to water, there is an effect that they can be satisfactorily bonded to each other.
[0160]
As described above, the SOI substrate according to the present invention has a configuration in which the coating film is a silicon oxide film formed by a plasma enhanced chemical vapor deposition method using a mixed gas of TEOS gas and oxygen gas.
[0161]
Therefore, there is an effect that a coating film that can be reliably obtained can be easily bonded to the coating film.
[0162]
As described above, the SOI substrate according to the present invention has a configuration in which the bonding portion is formed by bonding a coating film of silicon oxide having a thickness of 5 nm to 300 nm.
[0163]
Therefore, since the thickness of the silicon oxide film is large, it is hardly affected by fixed charges on the surface of the light-transmitting substrate, and the effect of improving the characteristics of the transistor formed on the single crystal silicon thin film of the SOI substrate can be obtained.
[0164]
As described above, the SOI substrate according to the present invention has a configuration in which the bonding strength of the bonding portion is 0.6 N / m or more.
[0165]
Therefore, since the adhesive strength is high, there is an effect that the adhesive does not peel off.
[0166]
As described above, the display device according to the present invention is configured to include any one of the above-described SOI substrates on which the semiconductor element structure is formed.
[0167]
Therefore, it is possible to obtain a uniform and high-performance transistor with no variation, and it is possible to provide a high-performance display device using the transistor.
[0168]
As described above, the method for manufacturing a semiconductor device according to the present invention includes, before the bonding step, an adjusting step of adjusting the surface of the coating film so that the tangent of the angle between the coating film and the substrate surface is 0.06 or less. It is a configuration that includes.
[0169]
Therefore, since the bonding is performed after the coating film and the single-crystal silicon piece have good bonding properties, the strength of this bonding can be increased, and there is an effect that film peeling does not occur.
[Brief description of the drawings]
FIG. 1 is a sectional view showing one embodiment of an SOI substrate according to the present invention.
2A is a sectional view of a substrate included in the SOI substrate, FIG. 2B is a sectional view showing a state in which a coating film is laminated on the substrate, and FIG. 2C is a sectional view of a single crystal silicon piece. It is sectional drawing, (d) is sectional drawing which shows the state which covered the coating film on the single crystal silicon piece, (e) is sectional drawing which shows a mode that hydrogen ion is implanted in the state of (d). (F) is a cross-sectional view showing a state in which the single crystal silicon piece shown in (e) is bonded to the substrate shown in (b), and (g) is a section obtained by dividing and peeling the single crystal silicon piece. FIG. 6 is a cross-sectional view showing a state in which the device is manufactured.
FIG. 3 is a cross-sectional view showing a state of surface irregularities of the coating film laminated on the substrate.
FIG. 4 is a cross-sectional view illustrating a wet state of water on a surface of the substrate on which the coating film is laminated.
5A and 5B are diagrams showing a procedure for producing a modification of the SOI substrate according to the present invention, wherein FIG. 5A is a sectional view of a substrate included in the SOI substrate, and FIG. It is sectional drawing which shows the state which laminated | stacked, (c) is sectional drawing which shows the state which laminated | stacked the amorphous silicon film to the state shown to (b), (d) melt | dissolved the said amorphous silicon film by irradiation of an excimer laser. FIG. 4E is a cross-sectional view showing a state in which a polysilicon film is formed, and FIG. 4F is a cross-sectional view showing a state in which a region for mounting a single-crystal silicon piece is formed by photolithography. It is a sectional view, (g) is a sectional view showing the state where the above-mentioned single crystal silicon piece was put, and (h) is a section showing the situation where the above-mentioned single crystal silicon piece is divided and peeled to produce the above-mentioned SOI substrate. It is a diagram.
FIG. 6 is a cross-sectional view illustrating an example of a thin film transistor formed using the SOI substrate.
FIG. 7 is a cross-sectional view showing a state of surface irregularities of a silicon oxide film laminated on a substrate in a conventional configuration.
FIG. 8 is a schematic cross-sectional view showing a bonding strength evaluation method.
[Explanation of symbols]
1,11 SOI substrate
2) Light transmissive substrate (substrate)
3 Silicon oxide film (coating film)
4 Silicon oxide film (coating film)
5% single crystal silicon thin film
6 single crystal silicon piece
10 ° hydrogen ion implantation implantation surface (hydrogen ion implantation layer)
12 polysilicon area
13 silicon oxide film (insulating film)
14 amorphous silicon film
21 thin film transistor
22 gate insulating film
23 gate electrode film
24 ° low resistance silicon film (n⁺Type silicon film, p⁺Type silicon film)
25 channel area
26 interlayer insulation film
27 source / drain metal film
W water
θ contact angle

Claims (8)

It includes a bonding portion where a coating film formed on a substrate and a coating film covering a single crystal silicon piece are bonded, and the single crystal silicon piece is divided by a hydrogen ion implantation layer to form a single crystal silicon thin film. SOI substrate,
The substrate is a light-transmitting substrate,
An SOI substrate, wherein the division is performed by heat treatment. An SOI substrate including a bonding portion formed by bonding a coating film formed on a substrate and a coating film covering a single crystal silicon piece, wherein the single crystal silicon piece is divided into a single crystal silicon thin film,
The bonding film has a surface having a tangent of an angle of 0.06 or less with respect to the substrate surface with respect to unevenness having a height of 5 nm or less measured in a range of 1 to 5 μm square of the coating film surface. An SOI substrate characterized by being bonded to a SOI substrate. An SOI substrate including a bonding portion formed by bonding a coating film formed on a substrate and a coating film covering a single crystal silicon piece, wherein the single crystal silicon piece is divided into a single crystal silicon thin film,
An SOI substrate, wherein the surface of the coating film and the surface of the coating film each have a contact angle with water of 10 ° or less. An SOI substrate including a bonding portion formed by bonding a coating film formed on a substrate and a coating film covering a single crystal silicon piece, wherein the single crystal silicon piece is divided into a single crystal silicon thin film,
An SOI substrate, wherein the coating film is a silicon oxide film formed by a plasma enhanced chemical vapor deposition method using a mixed gas of a TEOS gas and an oxygen gas. An SOI substrate including a bonding portion formed by bonding a coating film formed on a substrate and a coating film covering a single crystal silicon piece, wherein the single crystal silicon piece is divided into a single crystal silicon thin film,
The SOI substrate, wherein the bonding portion is formed by bonding the coating film made of silicon oxide and having a thickness of 5 nm to 300 nm. An SOI substrate including a bonding portion formed by bonding a coating film formed on a substrate and a coating film covering a single crystal silicon piece, wherein the single crystal silicon piece is divided into a single crystal silicon thin film,
An SOI substrate, wherein the bonding strength of the joint is 0.6 N / m or more. A display device comprising the SOI substrate according to any one of claims 1 to 6, wherein a semiconductor element structure is formed. A method for manufacturing an SOI substrate, comprising a bonding step of bonding a coating film formed on a substrate and a coating film covering a single crystal silicon piece,
A method of manufacturing an SOI substrate, comprising, before the bonding step, an adjusting step of adjusting a surface of the coating film so that a tangent of an angle between the coating film and the substrate surface is 0.06 or less. .

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