JP2002299235A - Semiconductor thin-film forming method and thin-film semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of a crystalline silicon film being formed at low temperatures, e.g. by a high density plasma, etc., without having to use a crystallizing means such as a laser, but a transition layer exists between a substrate and the crystalline silicon film to result in deterioration of the characteristics/reliability and productivity of thin-film semiconductor elements. SOLUTION: After previously forming a layer or thin film containing an element constituting a semiconductor as a main component on or near the surface of a substrate in a separate apparatus or the same apparatus forming the crystalline semiconductor film, a step of etching the layer or thin film containing the element constituting the semiconductor as the main component to produce crystal nuclei, a step of growing the crystal nuclei produced in the layer or thin film containing the element constituting the semiconductor as the main component and a step of growing the crystalline semiconductor film are executed in the same apparatus, thereby forming the crystalline semiconductor film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor thin film device in the semiconductor industry and a method for manufacturing the same.
The present invention relates to a high-performance semiconductor thin film on a surface of a substrate that melts at a low temperature and a low-temperature formation technology of a semiconductor element using the same. In particular, the present invention relates to a thin film transistor (TFT) formed on a surface of a glass substrate or the like and used for an active matrix type liquid crystal display or the like, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In an active matrix type liquid crystal display, a TFT used as a TFT is a pixel transistor for switching each pixel, and a high shift of a peripheral circuit for sending a control signal based on image information to be displayed to each pixel transistor. There is a degree control transistor. Conventionally, among these, a TFT using an active layer of hydrogenated amorphous silicon (a-Si: H) has been used for a pixel transistor, and a plasma-enhanced chemical vapor deposition (PCVD) is applied as a manufacturing method thereof. It had been. This a-Si: H TFT
Can be manufactured at a substrate temperature of about 300 ° C., so that there is an advantage that an inexpensive translucent glass substrate can be used. However, the mobility of the n-type TFT is as small as 1 cm ² / Vs or less, and the p-type TFT cannot provide practical mobility and cannot be used as a control transistor of a peripheral circuit. Was fabricated on a substrate.

On the other hand, a TFT using polycrystalline silicon (poly-Si) as an active layer has high mobility in both n-type and p-type.
There is an advantage that it can be applied to a control transistor. However, poly-Si is usually used for film formation by low pressure CVD method.
There is a problem that a high-temperature process of 00 ° C. or more is required, and an inexpensive glass substrate cannot be applied.

[0004] In order to solve the above problems, low-temperature production poly
Research and development of -Si (low-temperature poly-Si) technology has been actively carried out in recent years, and practical application has been promoted. The technology is a-Si: H
Irradiating the a-Si: H film with excimer laser light having a wavelength in the ultraviolet region where absorption by the film is extremely large (E
A method of manufacturing a polycrystalline film by recrystallization by rapid heating and melting / cooling by LA (excimer laser annealing method) (patent: 2725669, etc.) is generally used. However, this method is applicable to glass substrates at 600 ℃
Although a high mobility TFT can be formed at the following low temperature, a large area and high productivity can be achieved by using a laser.
It is difficult to form poly-Si. In general, the a-Si: H film contains hydrogen of 10 atom% or more, and as it is, sudden heating by excimer laser light causes bumping of hydrogen, which causes film peeling and surface roughness. In addition, there is a problem that a heat treatment step for desorbing hydrogen in the film must be added in advance.

To solve this problem, a method of forming a crystalline silicon film directly on a glass substrate without using ELA has been studied. Among these methods, as a method of forming a crystalline silicon film over a large area by PCVD using high-density plasma, for example, high-density plasma of a source gas by high-frequency inductive coupling (JP-A-10-265212, JP-A-11-74204) )
There is a technique in which a raw material gas is more actively decomposed and excited than in the conventional parallel plate high-frequency PCVD to form a crystalline silicon film.

[0006]

When the above technique is adopted, it is possible to produce a crystalline silicon film over the entire surface of a large-area substrate at a temperature at which a glass substrate can be applied.
There were the following issues.

As a method of forming a crystalline silicon film by PCVD using high-density plasma, for example, high-density plasma of a source gas by high-frequency inductive coupling (Japanese Patent Laid-Open No. 10-2)
65212, Japanese Patent Application Laid-Open No. H11-74204), there is a technique in which a raw material gas is more actively decomposed and excited than a conventional parallel plate high frequency PCVD to form a crystalline silicon film. However, there was a problem that the obtained film was not obtained with sufficient crystallinity and film quality. Further, in PCVD using high-density plasma, a polycrystalline silicon film can be formed depending on conditions, and the cross-sectional structure of the formed film is, as shown in FIG. 8, a substrate 28 or an insulating film ( Approx. 10 from the surface (not shown)
A layer with poor crystallinity called a transition layer (incubation layer) exists over 0 nm or more. When the thickness of the transition layer 29 increases with the deposition time, crystal nuclei are generated and grow in the thickness direction. When the number of crystal nuclei in the transition layer 29 reaches a certain number and size, a crystalline silicon film 30 such as microcrystalline silicon or polycrystalline silicon grows on the transition layer 29. Therefore, PC using high-density plasma
In VD, a polycrystalline silicon film can be formed on a substrate such as glass at a low temperature of 200 to 300 ° C.
In addition to the above-mentioned problem, the thickness is about 500 nm.
Unless the above deposition is performed, there is a problem that a polycrystalline silicon film having good crystallinity cannot be formed.

The present invention solves the above-mentioned problems of the prior art, and forms a crystalline silicon film and a transition layer on a substrate such as glass which is inexpensive but requires low-temperature processing. By providing a crystalline silicon film of excellent quality with a minimum required film thickness,
It is an object of the present invention to manufacture a highly reliable TFT with good productivity at low cost.

[0009]

In order to achieve the above object, a method of manufacturing a semiconductor thin film according to the present invention comprises forming a layer or a thin film mainly composed of an element constituting a semiconductor on or near a surface of a substrate. A step of generating a crystal nucleus while etching a layer or a thin film containing an element constituting the semiconductor as a main component after forming the semiconductor in a separate apparatus or in the same apparatus for forming a crystalline semiconductor film in advance; The step of growing a crystal nucleus generated in a layer or a thin film mainly composed of constituent elements and the step of growing a crystalline semiconductor film are performed in the same apparatus to form a crystalline semiconductor thin film.

When the thickness of a layer or thin film mainly composed of an element constituting a semiconductor formed on or near the surface of a substrate is set to 1 nm or more and 50 nm or less, crystal nuclei are formed directly above the underlayer or the surface of the substrate. Is preferred to make the transition layer extremely thin or almost nonexistent.

Top gate type T with excellent characteristics and productivity
As a thin film semiconductor device such as FT, a structure in which a crystalline semiconductor thin film formed through a transition layer having a thickness of 50 nm or less on an insulating film formed on part or the entire surface of a substrate is used as an active layer. Take.

Bottom gate type T with excellent characteristics and productivity
As a thin film semiconductor device such as an FT, a 50 nm layer is formed on a laminate of a conductor film and an insulating film formed on a part or the entire surface of a substrate.
A configuration is adopted in which a crystalline semiconductor thin film formed via a transition layer having the following thickness is used as an active layer.

A part or all of a layer or a thin film mainly composed of an element constituting a semiconductor formed on or near the surface of the substrate is removed, and a transition layer between the crystalline semiconductor thin film and the insulating film is removed. Setting the thickness to 50 nm or less is preferable in terms of the characteristics and reliability of the thin-film semiconductor device because unnecessary transition layers are as thin as 50 nm or less or hardly exist.

Further, it is preferable that at least one kind of an insulating layer and a conductor layer is formed on a part or the entire surface of the substrate, and a crystalline semiconductor thin film is formed on the insulating film or the conductor film. When manufacturing a semiconductor device on an inexpensive substrate such as glass, the influence of impurities from the substrate such as glass is reduced, and for example, the bottom gate type T
It is preferable because the structure of the semiconductor device can be variously designed according to the purpose, such as FT.

It is preferable that the thickness of the transition layer is substantially 0 or the transition layer is electrically inactive in order to obtain good characteristics in a thin film semiconductor device such as a TFT.

The thickness of the crystalline semiconductor thin film is 5 nm or more and 300 nm
The following is preferable because it can be applied to a thin film semiconductor device such as a TFT with the same film thickness without adding etching or film formation.

The fact that the crystalline semiconductor thin film formed on the substrate is a film containing Si as a main component and having a hydrogen content of 10 atm% or less means that the characteristics and reliability of the semiconductor thin film and the thin film semiconductor device are improved. In addition, when high quality such as laser recrystallization is required, dehydrogenation treatment is not required.

During the formation of the crystalline semiconductor, the temperature of the substrate is set at 10
The temperature of 0 ° C. or more and 600 ° C. or less is preferable because an inexpensive substrate such as glass or plastic can be used. Also, 10
The temperature of 0 ° C. or higher is preferable because impurities such as moisture adsorbed on the substrate can be removed and a highly pure semiconductor thin film can be formed.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described more specifically with reference to examples.

FIG. 1 is a schematic view of a first embodiment of a method of manufacturing a semiconductor thin film according to the present invention. First, a substrate 1 such as glass
A film 2 of silicon oxide or the like formed thereon by a normal pressure CVD method or the like.
Is formed to a thickness of 50 to 400 nm. The method of forming the coating 2 is a plasma CVD method, a vapor deposition method, and a low pressure CV method.
Other means such as D method and sputtering method may be used.

An amorphous silicon (a-Si) film 3 is formed on the surface of this film by a plasma CVD method (FIG. 1).
(A)). The substrate temperature was 200 ° C. and the film thickness was 20 nm. The amorphous silicon film 3 may be formed by other means such as a sputtering method and a vapor deposition method. The material of the thin film 3 mainly composed of an element constituting a semiconductor is not limited to amorphous silicon, but may be a microcrystalline silicon film, a silicon-rich silicon nitride film, a silicon germanium film, or a p-type or n-type doped film. Silicon film or silicide film may be used. Further, instead of the film, the vicinity of the surface of a previously formed film such as a silicon oxide film may be modified into a layer containing a large amount of silicon by an ion implantation method, a plasma doping method, an ion doping method, or the like. Further, it may be performed continuously by an apparatus used for the subsequent film formation.

Thereafter, in a plasma CVD apparatus using inductively coupled plasma (ICP), plasma processing is performed under conditions where the silicon film formed in advance is easily etched. The substrate temperature was set to 200 ° C., and 0.5% SiH ₄ / H ₂ was used at a high frequency power of 500 W and a substrate bias of −20 V. Under these conditions, the amorphous silicon film 3 is etched by a large amount of hydrogen ions and radicals, and crystal nuclei are formed in the amorphous silicon film 3 by the energy of the etching reaction and ion irradiation. 4 (FIG. 1B). The thickness of the silicon film 3 is set according to the etching rate and the position where the crystal nucleus is generated. In order to form a crystal nucleus immediately above the base film, the thickness of the silicon film 3 is 1 nm, although it depends on the conditions.
About 50 nm is preferable. The growth rate of the crystalline semiconductor thin film is D (nm / s), and the etching rate of the layer or thin film mainly composed of the elements constituting the crystalline semiconductor thin film is E.
If (nm / s) and a are constants exceeding 1, this corresponds to the processing condition of E> aD.

Subsequently, in the same apparatus, the gas was changed to 1% SiH ₄ / H ₂
With high frequency power: 500W, substrate bias: -10V,
Plasma treatment is performed. Under these conditions, amorphous silicon is etched, but crystalline silicon that grows with the generated crystal nuclei as nuclei is difficult to etch. By this process, a silicon film 5 containing the grown crystal nuclei is formed (FIG. 1C). In this process, aD ≧ E ≧ 1
/ aD.

Thereafter, plasma processing is performed with a gas of 2% SiH ₄ / H ₂ , high frequency power: 500 W, substrate bias: floating potential. Under this condition, crystalline silicon grows faster with the grown crystal nucleus as a nucleus than the previous condition, and is placed on the silicon film 5 containing the grown crystal nucleus via the transition layer 6 having a thickness of 10 nm or less. Then, a crystalline silicon film 7 is formed (FIG. 1D). This processing corresponds to processing conditions that satisfy 1 / aD> E (D> aE). The condition at this time is D ≦
It is preferable to set the conditions such as increasing the concentration of the source gas constituting the semiconductor such as SiH4, lowering the substrate bias, and increasing the discharge frequency, rather than the 1 / aE condition. Note that by setting conditions in accordance with the purpose, the crystallinity of the crystalline silicon film is changed to microcrystalline or polycrystalline.

The above conditions are appropriately set according to the plasma generation method, gas concentration, discharge power, substrate temperature, and substrate bias. It should be noted that etching, nucleation and the like may be controlled not only by plasma generation conditions but also by irradiation with light such as a laser or an excimer lamp. In this embodiment, ICP is described as a method of generating plasma, but plasma such as ECR plasma, helicon wave plasma, surface wave plasma, and VHF plasma may be used. Further, depending on the size and number of crystal nuclei required depending on the conditions, a process of generating crystal nuclei with etching and a process of growing the generated crystal nuclei may be performed alternately a plurality of times.

FIG. 2 shows a Raman spectrum of the crystalline silicon film formed by the above steps. From the Raman spectrum, it was confirmed that the sample was a polycrystal having few amorphous components. Also, by measuring the infrared absorption spectrum,
It was also confirmed that the hydrogen concentration of the obtained film was as low as 5 atom%.

FIG. 3 shows the relationship between the thickness of the previously formed silicon film 3 and the thickness of the newly formed transition layer 6 in the first embodiment of the method of manufacturing a semiconductor thin film according to the present invention. FIG. At this time, the time t1 for the process of generating the crystal nuclei along with the etching and the time t2 of the process for growing the generated crystal nuclei are constant. For the thickness of the newly formed transition layer, see section TEM
(Transmission electron microscope) Determined by an image. In FIG. 3, it was confirmed that the thickness of the newly formed transition layer 6 decreased according to the thickness of the silicon film 3 formed in advance, and was saturated at a certain thickness or more. This is because, when the thickness of the silicon film 3 formed in advance increases, the size and number of crystal nuclei formed by etching increase, so that the thickness of the transition layer 6 required until the polycrystalline film 7 grows is increased. When the thickness of the silicon film 3 is more than a certain thickness, the size and the number of crystal nuclei formed during the time t1 are saturated, so that the thickness of the transition layer 6 is saturated. The thickness of the silicon film 3 formed in advance varies depending on the setting of t1, but is preferably in the range of 5 to 50 nm in consideration of productivity and the like.

FIG. 4 shows that, in the method of manufacturing a semiconductor thin film according to the present invention, the time t 1 of the process of generating a crystal nucleus together with the etching is the time when the silicon film 3 formed in advance is almost etched. FIG. 4 is a diagram showing a relationship between a time t2 of a process of growing a crystal nucleus and a thickness of a transition layer 6; It was confirmed that the thickness of the transition layer 6 was reduced by increasing t2. As described above, according to the present invention, the crystalline silicon film 7 having almost no transition layer 6 is formed.
It can be formed on a substrate.

According to the method for manufacturing a semiconductor thin film according to the present invention, a thin film semiconductor device such as a top gate type TFT can be formed.
Similarly, it is possible to easily produce a high-performance, low-temperature condition. FIG. 5 is a process schematic diagram of a top gate type TFT as one embodiment in a thin film semiconductor device according to the present invention.

First, normal pressure CVD is performed on a substrate 8 such as glass.
A film 9 of silicon oxide or the like is formed to a thickness of 50 to 400 nm by a method or the like (FIG. 5A). The method of forming the coating 9 may be other means such as a plasma CVD method, a vapor deposition method, a low pressure CVD method, and a sputtering method.

An amorphous silicon (a-Si) film 10 is coated on the surface of the
It is formed with a thickness of about nm (FIG. 5B). Instead of the film, the vicinity of the surface of the silicon oxide film may be modified to a layer containing a large amount of silicon by a plasma doping method or the like. Further, it may be performed continuously by an apparatus used for the subsequent film formation.

Thereafter, a plasma process is performed in a plasma CVD apparatus using inductively coupled plasma (ICP) under conditions that the amorphous silicon film formed in advance is easily etched. In this process, the amorphous silicon film is etched, and crystal nuclei are formed in the amorphous silicon film by the energy of the etching reaction and ion irradiation, thereby forming a silicon film containing many crystal nuclei. The thickness of the amorphous silicon 10 to be formed in advance is set in accordance with the etching rate and the position where the crystal nucleus is generated. As described in the first embodiment, the thickness is preferably about 1 nm to 50 nm.

Subsequently, in the same apparatus, processing is performed under the condition that the amorphous silicon is easily etched and the crystalline silicon that grows with the generated crystal nuclei as nuclei is hardly etched to grow the crystal nuclei. Depending on the size and number of required crystal nuclei, the conditions for generating crystal nuclei with etching and the conditions for growing the generated crystal nuclei may be alternately performed a plurality of times.

Thereafter, a process is performed under the condition that the crystalline silicon grows faster than the above condition with the crystal nucleus as a nucleus, and a polycrystalline silicon film 12 having almost no transition layer 11 is formed (FIG. 5C). ).

Next, an insulating layer 13 such as a silicon oxide film is formed.
Is formed with a thickness of 50 to 300 nm. The method of forming the insulating layer 13 includes sputtering, normal pressure CVD, plasma CVD,
Other means such as a vapor deposition method, a low pressure CVD method, a plasma oxidation method, and a radical oxidation method may be used. The insulating film is not limited to silicon oxide, but may be an insulating material such as silicon nitride, aluminum oxide, tantalum oxide, or strontium titanate, or a stacked film of these materials.

Next, a metal film made of Ti, Mo, W, Al, Ta or the like is formed to a thickness of 50 to 300 nm by a sputter deposition method, and the metal film is etched using a photoresist patterned by photolithography as a mask. Thus, the gate electrode 14 is formed (FIG. 5D). The material of the gate electrode 14 is not limited to metal, but may be a transparent conductive film or a silicon film.

Using the gate electrode 14 as a mask, ions containing impurities are implanted to form an impurity doping layer to be the source / drain regions 15 (FIG. 5E). This doping layer is formed by, for example, ion doping using 5% PH ₃ diluted with hydrogen as an ion source gas in the case of forming an n-type layer. Conditions for applying ion doping are as follows: acceleration voltage: 5 to 100 kV, total ion implantation amount: 10
¹⁴ to 10 ¹⁶ cm ^-2 . For these conditions, optimal conditions and gas concentrations are appropriately selected according to the thickness of the mask, the thickness of the doping layer to be formed, and the like. The formation of the p-type layer is performed by ion doping using hydrogen diluted 5% B ₂ H ₆ or the like as an ion source gas. In addition, in the ion doping method, impurities serving as a dopant and hydrogen are simultaneously implanted, so that implantation defects are compensated for by hydrogen, activation and crystallization are promoted, and a doping layer with low resistance is formed at a low temperature. You. In this embodiment, the ion implantation is performed by removing the insulating layer in the region to be implanted. However, the ion implantation may be performed by leaving the insulating layer on the surface of the region to be implanted. In that case, the acceleration voltage of the ions is preferably 10 kV or more, depending on the conditions such as the film thickness. In addition to the source / drain regions 15, doping for forming the LDD and doping of the channel portion are performed as necessary.

Next, an insulating film 16 serving as an interlayer insulating film is
It is formed to a thickness of 100 to 500 nm by a sputtering method, a normal pressure CVD method, a plasma CVD method, or the like.
Is opened by photolithographic etching to form a source / drain electrode 17, and a TFT is manufactured (FIG. 5).
(F)).

FIG. 6 is a process schematic diagram of a bottom gate type TFT as one embodiment in a thin film semiconductor device according to the present invention.

First, a normal pressure CV is placed on a substrate 18 such as glass.
100 g of silicon oxide film as insulating film 19 by D method or the like.
After being formed to a thickness of about 500 nm, Ti, Mo, W, Al,
A gate electrode 20 is formed by forming a metal film made of Ta or the like to a thickness of 100 to 500 nm and etching the metal film using a photoresist patterned by photolithography as a mask (FIG. 6A).

Next, a silicon nitride film having a thickness of 50 to 300 nm is formed as the gate insulating layer 21 by plasma CVD. The method for forming the silicon nitride film is as follows.
Other means such as a sputtering method, a normal pressure CVD method, a thermal evaporation method, and a reduced pressure CVD method may be used. The material of the gate insulating film 21 is not limited to silicon nitride, but may be an insulating material such as silicon oxide, silicon oxynitride, aluminum oxide, tantalum oxide, strontium titanate, or a laminated film of these materials.

Next, an amorphous silicon (a-Si) film 22 is formed on the surface of this film to a thickness of about 20 nm by a plasma CVD method (FIG. 6B). Not a membrane,
The vicinity of the surface of the gate insulating film 21 may be modified into a layer containing a large amount of silicon by a plasma doping method or the like. Further, it may be performed continuously by an apparatus used for the subsequent film formation.

Thereafter, plasma processing is performed in a plasma CVD apparatus using inductively coupled plasma (ICP) under conditions that the amorphous silicon film 22 formed in advance is easily etched. In this process, the amorphous silicon film 22 is etched, and crystal nuclei are formed in the amorphous silicon film 22 by the energy of the etching reaction and the ion irradiation. The thickness of the amorphous silicon film 22 to be formed in advance is set according to the etching rate and the position where the crystal nucleus is generated. As described in the first embodiment, the thickness is preferably about 1 nm to 50 nm.

Subsequently, in the same apparatus, processing is performed under conditions that the amorphous silicon film 22 is easily etched and the crystalline silicon that grows with the generated crystal nuclei as nuclei is hardly etched, thereby growing crystal nuclei. Depending on the size and number of required crystal nuclei, the conditions for generating crystal nuclei with etching and the conditions for growing the generated crystal nuclei may be alternately performed a plurality of times.

Thereafter, a process is performed under the condition that the crystalline silicon grows faster than the above condition using the grown crystal nucleus as a nucleus, and the crystalline silicon film 2 having almost no transition layer 23 is formed.
4 is formed (FIG. 6C). As for the crystallinity of the crystalline silicon film 24, formation conditions are set so as to be microcrystalline or polycrystalline according to required characteristics.

Next, an n-type amorphous silicon film 25 is deposited by a plasma CVD method or the like (FIG. 6).
(D)). At this time, using a photoresist patterned by photolithography as a mask, ions containing impurities may be implanted into the crystalline silicon thin film to form an impurity doping layer serving as source / drain regions.

Thereafter, a metal film 26 serving as a source / drain electrode is formed. As the electrode material, Ti, Al, C
u, Mo, W, an alloy, a laminated material thereof, or the like is used. Then, using the photoresist patterned by photolithography as a mask, portions of the metal film 26, the n-type amorphous silicon film 25, and the crystalline silicon film 24 are removed by etching to form source / drain electrodes 27 (FIG. 6 ( e)), completing the TFT. Note that a protective film made of silicon nitride, silicon oxide, or the like is formed as necessary.

FIG. 7 shows the gate voltage-drain current characteristics of the top gate type TFT according to the prior art and the present invention. The conventional TFT has a transition layer thickness of about 200 n.
m, the thickness of the crystalline silicon film is 500 nm, whereas the TFT according to the present invention has a transition layer thickness of about 5 nm or less and a crystalline silicon film thickness of 70 nm. TFT according to the present invention
Is larger in the ON / OFF ratio and the field-effect mobility than in the prior art, and has excellent characteristics.

As described above, in the method of manufacturing a semiconductor device according to the present invention, a crystalline silicon thin film having a thin transition layer can be formed within a temperature range in which a glass substrate or a plastic substrate can be applied without increasing the substrate temperature. By adopting a structure of a thin film semiconductor device having a crystalline silicon thin film having a thin transition layer as an active layer, it is possible to provide a thin film semiconductor device having excellent productivity and characteristics. A liquid crystal display or the like having excellent characteristics can be manufactured with high yield and high productivity.

[0050]

As described above, according to the structure of the present invention, a transition layer that lowers the characteristics and reliability can be suppressed, and a crystalline semiconductor thin film can be formed at a low temperature. And the like can be manufactured with high productivity. Therefore, even when TFTs are manufactured on a glass substrate or a plastic substrate having a large area, such as an active matrix type liquid crystal display, a TFT having excellent characteristics and reliability can be manufactured with high productivity.

When the thickness of the layer or thin film mainly composed of an element constituting the semiconductor formed on or near the surface of the base is 1 nm or more and 50 nm or less, the crystal nuclei are formed immediately above the base film or the surface of the base. Is preferred to make the transition layer extremely thin or almost nonexistent.

By adopting a configuration in which a crystalline semiconductor thin film formed through a transition layer having a thickness of 50 nm or less is formed as an active layer on an insulating film formed on a part or the entire surface of a substrate, And a thin film semiconductor device such as a top gate type TFT having excellent productivity can be manufactured.

A structure in which a crystalline semiconductor thin film formed on a laminate of a conductor film and an insulating film formed on a part or the entire surface of a substrate via a transition layer having a thickness of 50 nm or less is used as an active layer. By doing so, a thin-film semiconductor device such as a bottom-gate TFT having excellent characteristics and productivity can be manufactured.

Part or all of a layer or a thin film mainly composed of a semiconductor element formed on or near the surface of the substrate is removed, and is formed between the crystalline semiconductor thin film and the insulating film. Setting the thickness of the transition layer to 50 nm or less has an effect that the characteristics and reliability of the thin film semiconductor device are excellent because unnecessary transition layers are thin or almost 50 nm or less.

In a preferable configuration in which the thickness of the transition layer is substantially 0 or the transition layer is electrically inactive, better characteristics and reliability can be obtained in a thin film semiconductor device such as a TFT. .

When the thickness of the crystalline semiconductor thin film is 5 nm or more and 300 nm
According to the preferred configuration described below, the film thickness can be applied to a thin film semiconductor device such as a TFT without adding etching or film formation, and productivity is further improved.

With the preferred structure in which the crystalline semiconductor thin film formed on the substrate has a hydrogen content of 10 atm% or less and a film containing Si as a main component, the characteristics and reliability of the semiconductor thin film and the thin film semiconductor device are improved. In addition, when high quality such as laser recrystallization is required, dehydrogenation treatment is not required.

During the formation of the crystalline semiconductor, the temperature of the substrate is set at 10
With a preferable structure in which the temperature is 0 ° C. or more and 600 ° C. or less, an inexpensive substrate such as glass or plastic can be used. When the temperature is higher than or equal to 100 ° C., impurities such as moisture adsorbed on the substrate are removed, and a highly pure semiconductor thin film can be formed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a method for manufacturing a semiconductor thin film according to the present invention.

FIG. 2 is a diagram showing a Raman spectrum of a crystalline silicon film manufactured by a method for manufacturing a semiconductor thin film according to the present invention.

FIG. 3 is a view showing the thickness of a newly formed transition layer with respect to the thickness of a silicon film formed in advance in a crystalline silicon film manufactured by the method for manufacturing a semiconductor thin film according to the present invention.

FIG. 4 shows a method for manufacturing a semiconductor thin film according to the present invention.
FIG. 5 is a diagram showing the transition layer thickness with respect to the time t2 of the process of growing the generated crystal nuclei.

FIG. 5 is a schematic process diagram of a top gate type TFT in the thin film semiconductor device according to the present invention.

FIG. 6 is a schematic process diagram of a bottom gate type TFT in the thin film semiconductor device according to the present invention.

FIG. 7 is a diagram showing a gate voltage-drain current characteristic of the thin film semiconductor device according to the related art and the present invention.

FIG. 8 is a schematic view of a method for manufacturing a semiconductor thin film according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Coating 3 Silicon film 4 Silicon film containing crystal nucleus 5 Silicon film containing grown crystal nucleus 6 Transition layer 7 Crystalline silicon film 8 Substrate 9 Silicon oxide film 10 Silicon film 11 Transition layer 12 Crystalline silicon film Reference Signs List 13 gate insulating film 14 gate electrode 15 source / drain region 16 interlayer insulating film 17 source / drain electrode 18 substrate 19 silicon oxide film 20 gate electrode 21 gate insulating film 22 silicon film 23 transition layer 24 crystalline silicon film 25 n-type silicon Film 26 metal film 27 source / drain electrode

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masashi Goto 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. Term (Reference) 2H092 JA24 KA04 MA08 MA17 MA28 MA37 NA22 4K030 AA06 AA17 BA29 BB04 CA06 DA04 FA01 JA01 JA10 LA11 5F052 AA11 DA01 DA02 DA10 DB03 DB04 DB07 EA11 EA15 FA07 HA06 JA01 5F110 AA17 AA30 BB01 DD02 FF01 DD02 FF03 FF09 FF22 FF25 FF28 FF29 FF30 FF32 GG01 GG02 GG13 GG15 GG19 GG33 GG34 GG42 GG43 GG45 GG57 GG60 HJ01 HJ12 HJ13 HJ23 HK02 HK03 HK04 HK09 HK16 HK21 NN22 NN15

Claims (12)

[Claims] 1. A layer or a thin film mainly composed of an element constituting a semiconductor is formed on a surface of a base or in the vicinity thereof in advance, and then a layer mainly composed of the element constituting the semiconductor is formed in the same vacuum apparatus. Alternatively, through a step of generating crystal nuclei while etching the thin film, a step of growing a crystal nucleus generated in a layer or a thin film mainly composed of the elements constituting the semiconductor, and a step of growing a crystalline semiconductor film, A method for forming a semiconductor thin film, comprising forming a conductive semiconductor thin film. 2. A layer or a thin film mainly containing an element constituting a semiconductor is formed on or near a surface of a base in the same vacuum apparatus, and a layer or a thin film mainly containing an element constituting the semiconductor is formed. Generating a crystal nucleus while etching the semiconductor; growing a crystal nucleus generated in a layer or a thin film containing the element constituting the semiconductor as a main component;
A method for forming a semiconductor thin film, comprising forming a crystalline semiconductor thin film through a step of growing a crystalline semiconductor film. 3. The method according to claim 1, wherein the thickness of the layer or thin film formed on the surface of the substrate or in the vicinity thereof and containing the element constituting the semiconductor as a main component is 1 nm or more and 50 nm or less. Item 3. The method for forming a semiconductor thin film according to Item 2. 4. A substrate having an insulating film formed partially or entirely on a substrate, and a crystalline semiconductor thin film formed on the substrate via a transition layer having a thickness of 50 nm or less as an active layer. Thin film semiconductor device. 5. A substrate on which a laminate of a conductor film and an insulating film is partially or entirely formed as a base, and a substrate is provided on the base.
A thin film semiconductor device using a crystalline semiconductor thin film formed through a transition layer having a thickness of nm or less as an active layer. 6. A part or all of a layer or a thin film mainly composed of an element constituting a semiconductor formed on or near a surface of a substrate is removed, and a 50 nm film is formed between the crystalline semiconductor thin film and the substrate. 6. The thin-film semiconductor device according to claim 4, wherein a crystalline semiconductor film formed through a transition layer having the following thickness is used as an active layer. 7. The thin-film semiconductor according to claim 4, wherein the thickness of the transition layer is substantially zero, or the transition layer is electrically inactive. apparatus. 8. The crystalline semiconductor thin film has a thickness of 5 nm or more and 300 nm or more.
7. The thin film semiconductor device according to claim 4, wherein the thickness is equal to or less than nm. 9. The method according to claim 1, wherein the crystalline semiconductor thin film formed on the substrate is a film having a hydrogen content of 10 atm% or less and containing Si as a main component. The method for forming a semiconductor thin film according to any one of the above. 10. The method according to claim 1, wherein the temperature of the base is set to 100 ° C. or higher and 600 ° C. or lower during the formation of the crystalline semiconductor.
The method for forming a semiconductor thin film according to claim 1. 11. The crystalline semiconductor thin film formed on a substrate is a film having a hydrogen content of 10 atm% or less and containing Si as a main component. A thin-film semiconductor device according to any of the above. 12. The method according to claim 1, wherein the temperature of the base is set to 100 ° C. or more and 600 ° C. or less during the formation of the crystalline semiconductor.
The thin-film semiconductor device according to claim 4.