JP4827303B2 - Photovoltaic element, TFT, and method for forming i-type semiconductor layer - Google Patents

Description

【０１３８】
【表２】

光電変換効率は、比較例1-3の値を１に規格化したもの。
はがれ試験は、剥れたます目の数が◎0、○1〜2、△3〜10、×10〜100を意味する
【０１３９】
【表３】

【０１４０】
【表４】

光電変換効率、光劣化率は実施例2-1の値を１に規格化したもの。
【０１４１】
【表５】

【０１４２】
【表６】

【０１４３】
【表７】

【０１４４】
【表８】

【０１４５】
【表９】

【０１４６】
【表１０】

【０１４７】
【表１１】

それぞれの値は、導電性基板と高周波導入部間の距離3mmのときの値を１に規格化したもの。
【０１４８】
【表１２】

光電変換効率は、半導体形成容器213内の圧力が50Ｐａのときの値を１に規格化した値
はがれ試験は、剥れたます目の数が◎0、○1〜2、△3〜10、×10〜100を意味する
温湿度試験は、（試験後の光電変換効率）／（試験前の光電変換効率）の値
【０１４９】
【表１３】

光電変換効率は、半導体形成容器212、213内の滞留時間が0.008秒のときの値を１に規格化した値
はがれ試験は、剥れたます目の数が◎0、○1〜2、△3〜10、×10〜100を意味する
温湿度試験は、（試験後の光電変換効率）／（試験前の光電変換効率）の値
【０１５０】
【表１４】

【図面の簡単な説明】
【図１】本発明の半導体素子を含む光起電力素子の一例を示す模式的な断面図である。
【図２】本発明の半導体素子及び光起電力素子を製造する堆積膜形成装置の一例を示す模式的な断面図である。
【図３】本発明の半導体素子を含む半導体層の一例を示す模式的な断面図である。
【図４】本発明の半導体素子を含む光起電力素子の一例を示す模式的な断面図である。
【図５】本発明の半導体素子を含む光起電力素子の一例を示す模式的な断面図である。
【図６】本発明の半導体素子及び光起電力素子を製造する堆積膜形成装置の一例を示す模式的な断面図である。
【図７】本発明の半導体素子を含む光起電力素子の一例を示す模式的な断面図である。
【図８】本発明の半導体素子を含むＴＦＴの一例を示す模式的な断面図である。
（符号の説明）
１０１ 基板、
１０１−１ 基体、
１０１−２ 金属層、
１０１−３ 第一の透明導電層、
１０２ 半導体層、
１０２−１ 第一の導電型を示す半導体層、
１０２−１Ａ アモルファスｎ型半導体層、
１０２−２ ｉ型半導体層、
１０２−２Ａ 微結晶ｉ型半導体層、
１０２−３ 第二の導電型を示す半導体層、
１０２−３Ａ 微結晶ｐ型半導体層、
１０２−４ アモルファスｎ型半導体層、
１０２−５ アモルファスｉ型半導体層、
１０２−６ 微結晶ｐ型半導体層、
１０２−１０ 非晶質シリコン層、
１０３ 透明電極、
１０４ 集電電極、
２０１ 堆積膜形成装置、
２０２ 基板送り出し容器、
２０３ 基板巻き取り容器、
２０４ 導電性基板、
２１１〜２１８ 半導体形成用真空容器、
２２１〜２２９ ガスゲート、
２３１〜２３８ ガス導入管、
２３３−１、２３３−２ ガス導入管、
２４１〜２４８ 高周波導入部、
２５１〜２５８ 高周波電源、
３０１ ガラス基板、
３０２ ゲート電極、
３０３ ゲート絶縁膜、
３０４ 活性層、
３０５ オーミックコンタクト層、
３０６ ソース、ドレイン電極。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor device comprising a silicon-based thin film and having a semiconductor junction. Photovoltaic element that is , TFT And silicon-based thin films I-type semiconductor layer comprising It is related with the formation method of this.
[0002]
[Prior art]
When an i-type semiconductor layer that substantially functions as a light absorption layer in a photovoltaic device having a pin junction is used as an i-type semiconductor layer containing a crystal phase, the Stebler-Lonsky (Staebler- Since there is a merit capable of suppressing the light deterioration phenomenon due to the Wronski effect, it is effective to make the i-type semiconductor layer include a crystal phase. In addition, high-mobility TFTs are required for high-definition, high-brightness liquid crystal panels, but crystalline silicon TFTs have a mobility that is two orders of magnitude greater than amorphous-phase silicon TFTs. In addition, the TFT characteristics are greatly improved, and even if the gate width of the TFT is reduced, the current value necessary for circuit operation can be sufficiently secured, and the pixel pitch is made smaller than that of an amorphous silicon TFT. Therefore, downsizing and high definition of the device are relatively easy.
[0003]
Against this background, various efforts have been made on silicon-based thin films containing crystal phases.
[0004]
The high-frequency plasma CVD method is one of excellent methods for mass production of silicon-based thin films from the viewpoint of easy area enlargement and low-temperature formation and improved process throughput. Examples of the application of silicon-based thin films to products include solar cells and color liquid crystal TFTs, but further cost reduction and higher performance are necessary in order to promote widespread use. For that purpose, the establishment of the technology relating to the high-frequency plasma CVD method has become one of the important technical issues.
[0005]
With respect to the crystalline silicon-based thin film layer, the (220) plane is assumed to be the growth plane, and JP-A-11-310495 discloses that the ratio of the diffraction intensity of (220) is 30% or more of the ratio of the total diffraction intensity. A silicon-based thin film characterized by this is disclosed.
[0006]
In addition, as an example of an i-type semiconductor layer having a semiconductor layer having a pin junction made of microcrystalline silicon, a photovoltaic element in which the crystal orientation in the i-type semiconductor is changed in the depth direction of the layer is provided. This is disclosed in Japanese Patent Laid-Open No. 11-233803.
[0007]
[Problems to be solved by the invention]
As described above, the silicon-based thin film already disclosed exhibits excellent characteristics, but the former silicon-based thin film is a silicon-based thin film in which the (220) plane is preferentially oriented. Not touched. In the latter silicon thin film, the silicon thin film preferentially oriented in the (220) plane is not mentioned.
[0008]
In order to provide a silicon-based thin film having excellent performance at a lower cost, the present invention provides a silicon-based thin film having a short tact time and excellent characteristics at a further high deposition rate, and a semiconductor device including the same . It is another object of the present invention to provide a semiconductor element having excellent adhesion and environmental resistance using the silicon-based thin film.
[0009]
[Means for Solving the Problems]
The present invention is a photovoltaic device including at least one set of a pin-type semiconductor junction including a p-type semiconductor layer containing silicon atoms as a main component, an i-type semiconductor layer, and an n-type semiconductor layer on a substrate. The i-type semiconductor layer is microcrystalline and 1.0 × 10 ¹⁹ atoms / cm ³ 2.5 × 10 or more ²⁰ atoms / cm ³ Including the following fluorine atoms, An interface region between the i-type semiconductor layer and the p-type semiconductor layer or the n-type semiconductor layer which is a base layer of the i-type semiconductor layer, the i-type semiconductor layer and the p-type semiconductor layer or the n-type semiconductor layer; The crystallites in the interface region from 1.0 nm to 20 nm from the interface are preferentially oriented in the (100) plane, The orientation of the (220) plane, which is the ratio of the diffraction intensity of the (220) plane by the X-ray or electron beam of the microcrystal in the layer thickness direction of the i-type semiconductor layer to the total diffraction intensity, is an underlayer of the i-type semiconductor layer There is provided a photovoltaic element characterized in that it is small on the p-type semiconductor layer or n-type semiconductor layer side, and changes so as to increase with distance from the base layer.
The present invention also provides a TFT having a gate electrode, a gate insulating film, an active layer, a contact layer, a source electrode, and a drain electrode on a substrate, wherein the gate insulating film is interposed between the gate electrode and the active layer. And the contact layer is disposed between the active layer and the source electrode or the drain electrode, the active layer comprising microcrystals, 1.0 × 10 ¹⁹ atoms / cm ³ 2.5 × 10 or more ²⁰ atoms / cm ³ Including the following fluorine atoms, There are microcrystals in an interface region between the active layer and the gate insulating layer which is an underlayer of the active layer, the interface region being 1.0 nm or more and 20 nm or less from the interface between the active layer and the gate insulating layer (100 ) Is preferentially oriented to the surface, The orientation of the (220) plane, which is the ratio of the diffraction intensity of the (220) plane by X-rays or electron beams of the microcrystal in the layer thickness direction of the active layer to the total diffraction intensity, is small on the gate insulating film side, and the gate Provided is a TFT characterized in that it changes so as to increase with distance from an insulating film.
[0010]
According to the present invention, in a semiconductor device having a semiconductor junction made of a silicon-based thin film, at least one of the silicon-based thin films contains microcrystals, and the silicon-based thin film containing the microcrystals is contained in a silicon hydride in a vacuum vessel. Introducing at least one of a fluorinated silicon gas and a source gas containing hydrogen, introducing a high frequency into a high frequency introducing portion in the vacuum vessel, and introducing the high frequency into the vacuum vessel using a high frequency plasma method A silicon-based thin film containing microcrystals formed, wherein the substrate heating means is disposed on the opposite side of the substrate from the surface on which the silicon-based thin film containing microcrystals is formed, and the output of the heating means is Provided is a semiconductor device characterized in that the semiconductor element is lowered with the formation of the silicon-based thin film containing the microcrystal.
[0011]
The present invention relates to a method for forming an i-type semiconductor layer containing silicon atoms containing microcrystals as a main component on a base layer selected from a p-type semiconductor layer, an n-type semiconductor layer, or an insulating layer, and a vacuum vessel At least one of silicon hydride and fluorinated silicon gas and a source gas containing hydrogen are introduced, and at least one of the silicon hydride and fluorinated silicon gas or the ratio of the flow rate of the source gas containing hydrogen is changed. Then, by supplying hydrogen to the growth surface in an atmosphere having a low etching effect, the i-type semiconductor layer becomes 1.0 × 10 6. ¹⁹ atoms / cm3 or more 2.5 × 10 ²⁰ atoms / cm ³ Containing the following fluorine atoms, An interface region between the i-type semiconductor layer and the p-type semiconductor layer or the n-type semiconductor layer which is a base layer of the i-type semiconductor layer, the i-type semiconductor layer and the p-type semiconductor layer or the n-type semiconductor layer; The crystallites in the interface region from 1.0 nm to 20 nm from the interface are preferentially oriented in the (100) plane, The orientation of the (220) plane, which is the ratio of the diffraction intensity of the (220) plane by the X-ray or electron beam of the microcrystal in the film thickness direction of the i-type semiconductor layer to the total diffraction intensity, is at the initial stage of formation of the silicon-based thin film. The method of forming an i-type semiconductor layer is characterized in that it is small and is changed so as to increase as the film is deposited.
[0012]
The present invention is a method for forming a silicon-based thin film containing microcrystals, wherein the silicon-based thin film containing microcrystals contains hydrogen in at least one of silicon hydride and fluorinated silicon gas in a vacuum vessel. A method of forming a silicon-based thin film including microcrystals formed on a substrate introduced into a vacuum vessel by introducing a source gas, introducing a high frequency into a high frequency introduction portion in the vacuum vessel, and introducing the high frequency plasma method into the vacuum vessel The heating means for the substrate is disposed on the opposite side of the substrate from the formation surface of the silicon-based thin film containing the microcrystals, and the output of the heating means is used to form the silicon-based thin film containing the microcrystals. The present invention also provides a method for forming a silicon-based thin film, which is characterized by being lowered together.
[0013]
The semiconductor element has a pin-type semiconductor junction in which a semiconductor layer having a first conductivity type mainly composed of silicon atoms, an i-type semiconductor layer, and a semiconductor layer having a second conductivity type are sequentially stacked on a substrate. A photovoltaic device comprising at least one set, wherein at least one of the i-type semiconductor layers includes a silicon-based thin film containing microcrystals, and the orientation of the microcrystals in the silicon-based thin film is It is preferable to change in the film thickness direction. It is preferable that an amorphous silicon layer is disposed between the silicon-based thin film containing the microcrystals and the semiconductor layer having a conductivity type disposed on the light incident side with respect to the silicon-based thin film. It is preferable to dispose an amorphous silicon layer between the silicon-based thin film containing microcrystals and the semiconductor layer exhibiting the second conductivity type. The thickness of the amorphous silicon layer is preferably 30 nm or less. The change in orientation of the microcrystal is that the ratio of the diffraction intensity of the (220) plane by the X-ray or electron beam of the microcrystal to the total diffraction intensity changes in the film thickness direction of the silicon-based thin film. preferable. The change in the orientation of the microcrystal is such that the ratio of the diffraction intensity of the (220) plane by the X-ray or electron beam of the microcrystal to the total diffraction intensity in the silicon-based thin film containing the microcrystal is relatively small in the initial stage of film formation. Is preferably small. The change in orientation of the microcrystals is preferably continuous. It is preferable that the silicon-based thin film containing the microcrystal includes a region where the ratio of the diffraction intensity of the (220) plane by the X-ray or electron beam of the microcrystal to the total diffraction intensity is 80% or more. In the silicon-based thin film containing the microcrystals, it is preferable that the microcrystals having a preferential orientation of the (110) plane have a columnar shape extending in the vertical direction with respect to the substrate. It is preferable that the microcrystal in the interface region of the silicon-based thin film containing the microcrystal has a (100) plane preferential orientation. It is preferable that the crystallites in the interface region have a substantially spherical shape. It is preferable that the thickness of the interface region is 1.0 nm or more and 20 nm or less. The silicon-based thin film containing the microcrystal contains at least one of oxygen atom, carbon atom, and nitrogen atom, and the total amount thereof is 1.5 × 10 5. ¹⁸ atoms / cm ^Three 5.0 × 10 or more ¹⁹ atoms / cm ^Three The following is preferable. The silicon-based thin film containing the microcrystal is 1.0 × 10 ¹⁹ atoms / cm ^Three 2.5 × 10 or more ²⁰ atoms / cm ^Three It preferably contains the following fluorine atoms. The silicon-based thin film containing microcrystals introduces a source gas containing at least one of silicon hydride and fluorinated silicon gas and hydrogen into a vacuum vessel, and introduces a high frequency into a high frequency introduction portion in the vacuum vessel. It is preferable that the etching be performed by a high-frequency plasma CVD method for forming the silicon-based thin film on a substrate introduced into the vacuum vessel. In the process of forming the silicon-based thin film containing the microcrystals, it is preferable to change the ratio of the gas flow rate in the source gas. It is preferable that the source gas is introduced into the vacuum vessel using a plurality of gas introduction units, and at least one of the plurality of gas introduction units flows a source gas having a gas flow ratio different from the others. The high frequency is preferably 10 MHz or more and 10 GHz or less. The high frequency is preferably 20 MHz or more and 300 MHz or less. It is preferable that a distance between the high-frequency introducing portion and the substrate is 3 mm or more and 30 mm or less. The pressure for forming the silicon-based thin film containing the microcrystals is preferably 100 Pa (0.75 Torr) or more and 5000 Pa (37.5 Torr) or less. The residence time of the source gas when forming the silicon-based thin film containing the microcrystals is preferably 0.01 seconds or more and 10 seconds or less. The residence time of the source gas when forming the silicon-based thin film containing the microcrystals is preferably 0.1 seconds or more and 3 seconds or less.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
As a result of intensive research in order to solve the above-described problems, the present inventor has found that in a semiconductor element having a semiconductor junction made of a silicon-based thin film, at least one of the silicon-based thin films contains a microcrystal, and the microcrystal The semiconductor element characterized in that the orientation of the microcrystals in the silicon-based thin film containing silicon changes in the film thickness direction in the silicon-based thin film containing the microcrystals. The present inventors have found that it is possible to form a semiconductor element having excellent properties and environmental resistance at low cost.
[0015]
The above-described configuration has the following effects.
[0016]
Crystalline silicon has a lower defect density of Si-Si bonds than amorphous phase silicon, and carrier transfer compared to amorphous silicon in thermodynamic non-equilibrium state. It has the characteristics that it has a large degree of recombination and has a long recombination life, and is excellent in stability of characteristics over a long period of time. In addition, it has the characteristics that the characteristics hardly change even in an environment such as high temperature and high humidity. Therefore, in semiconductor elements having a semiconductor junction made of a silicon-based thin film, for example, by using a silicon-based thin film containing a crystal phase in a photovoltaic element or a TFT, it has better characteristics and excellent stability. There is a possibility that a semiconductor element can be formed.
[0017]
On the other hand, as a problem when a silicon-based thin film containing a crystal phase is adopted for the i-type semiconductor layer, it is conceivable that the crystal grain boundary affects both the majority carrier and the minority carrier to deteriorate the performance. In order to suppress the influence of the crystal grain boundary, it is considered that one of effective means is to increase the crystal grain size in the i-type semiconductor layer and reduce the crystal grain boundary density.
[0018]
As a means for increasing the crystal grain size, it is preferable to suppress the generation of crystal nuclei and improve the crystal orientation. When film formation proceeds with random crystal orientation, each crystal grain collides with each other during the growth process, and the size of the crystal grain is considered to be relatively small. By controlling the formation of nuclei and aligning the growth direction, random collisions between crystal grains can be suppressed, and as a result, the crystal grain size can be increased. On the other hand, when internal stress occurs in the silicon-based thin film, distortion of the band profile occurs, a region where the electric field in the carrier generation layer decreases during light irradiation occurs, and in TFT, switching occurs. There arises a problem such as an increase in leakage current flowing at the off time. Here, in the interface region of the silicon-based thin film, particularly the silicon-based thin film, the internal stress in the silicon-based thin film can be further reduced by changing the orientation in the film thickness direction in the process of forming the deposited film. This is preferable because it is possible. The reason why internal stress can be reduced is that the orientation can be changed and the direction of the Si-Si bond can be changed for different mechanical stress environments in the interface region and the internal region of the silicon-based thin film. It is believed that there is.
[0019]
Here, in crystalline silicon having a diamond structure, the (220) plane has the highest in-plane atomic density, and the silicon atoms in the outermost surface of growth have three of the four bonds in the other silicon. A structure in which a silicon-based thin film with good adhesion and weather resistance in microcrystals and between microcrystals can be formed when this plane is used as a growth plane because of the structure in which atoms are covalently bonded. It is considered that it is preferable. In addition, when an inverted stagger type TFT is used as a device of an active matrix liquid crystal device, a region in contact with the ohmic contact layer of the active layer is a silicon thin film containing microcrystals preferentially oriented in the (220) plane, During the dry etching of the ohmic contact layer during the formation process, it is possible to completely remove the ohmic contact layer without etching the active layer without using an etching stopper material such as a nitride film. This is because the (220) plane is rich in etching resistance. From the ASTM card, in the non-oriented crystalline silicon, the ratio of the diffraction intensity of the (220) plane to the sum of the diffraction intensity of 11 reflections from the low angle side is about 23%, and the ratio of the diffraction intensity of the (220) plane A structure having more than 23% has orientation in this plane direction. In particular, in a structure including a region where the ratio of the diffraction intensity of the (220) plane is 80% or more, the above effect is further promoted, which is particularly preferable.
[0020]
In summary, the orientation of the microcrystal contained in the silicon-based thin film changes in the film thickness direction of the silicon-based thin film, and the microcrystal includes a region preferentially oriented in the (220) plane. Seems to be preferable.
[0021]
In a pin-type semiconductor junction photovoltaic device in which a semiconductor layer having a first conductivity type, an i-type semiconductor layer, and a semiconductor layer having a second conductivity type are sequentially stacked, a silicon-based thin film containing the microcrystals, It is preferable to dispose an amorphous silicon layer between the semiconductor layers showing the conductivity type arranged on the light incident side with respect to the silicon-based thin film, because there is an effect of increasing the open-circuit voltage. . At the same time, there is an effect that the band profile near the interface is improved, carrier recombination is prevented, and more carriers can be taken out. Furthermore, the dopant atoms from the conductive type layer are prevented from diffusing into the i-type semiconductor layer. In addition, it is preferable that the concentration of hydrogen contained in the amorphous silicon layer is increased in the interface direction with the silicon-based thin film containing the microcrystals, so that it is considered that there is an effect of relieving stress generated in the vicinity of the interface. It is. This is considered to be because a cluster region containing hydrogen atoms is formed in a region having a high hydrogen concentration, and the function of absorbing internal stress due to the mismatch between both structures sandwiching the interface is enhanced. Here, if the film thickness of the amorphous silicon layer is too large, the influence of film deterioration due to light irradiation appears as a characteristic of the photovoltaic element, so the film thickness of the amorphous silicon layer is 30 nm or less. It is preferable that.
[0022]
The method of forming a silicon-based thin film containing a crystalline phase by plasma CVD using high frequency can shorten the process time and lower the process temperature compared to the solid-phase reaction. Since it becomes possible to use inexpensive materials such as glass substrates and stainless steel substrates, it is advantageous for cost reduction. In particular, in a photovoltaic element having a pin junction, this effect is greatly exerted when applied to an i-type semiconductor layer having a large film thickness. In particular, it is preferable that the i-type semiconductor layer can be formed at a deposition rate of 2.0 nm / second or more.
[0023]
Here, when forming an oriented silicon-based thin film by the high-frequency plasma CVD method, the formation is performed in an atmosphere where there are active species contributing to etching in addition to active species contributing to the deposition of the silicon-based thin film. Can be considered. Then, by depositing the film while etching the Si-Si bond having a relatively weak bonding force on the surface of the formed film, it becomes possible to form a silicon-based thin film having a specific plane as a preferential orientation plane. it is conceivable that. Here, the degree of orientation can be controlled by controlling these active species.
[0024]
When the film is formed by such a reaction mechanism, it is desired that the crystal nucleus density having (220) orientation is small at the initial stage of film formation. When the density of crystal nuclei having (220) orientation is high, the formation of a silicon-based thin film starting from the crystal nuclei is considered to result in relatively small crystal grains in the entire silicon-based thin film. . In addition, when the film is formed in an atmosphere in which the degree of orientation is high in the interface region, that is, when the film is formed in an atmosphere having a high etching effect, the underlying layer is also damaged. Concerned about giving. Therefore, in the initial stage of formation of the silicon-based thin film containing microcrystals, it is preferable that the orientation of the (220) plane is relatively small while ensuring high crystallinity.
[0025]
Here, in an atmosphere with a relatively small etching effect, the growth of the (100) plane seems to have a higher growth rate than the (220) plane, and thus the density of crystal nuclei oriented in the (220) plane It is preferable that the microcrystals in the interface region of the silicon-based thin film containing the microcrystals have a (100) plane preferential orientation. is there. In particular, a TFT is particularly preferable because a region with high conductivity can be formed in a region in contact with the gate insulating film and a surface with high smoothness can be formed. In order to exhibit the above effect, the film thickness of the interface region is preferably 1.0 nm or more and 20 nm or less.
[0026]
In order to alleviate adhesion and internal stress at the interface, it is preferable that the outer shape of the microcrystal in the interface region has a substantially spherical shape having no specific orientation.
[0027]
The microcrystal in the silicon-based thin film in the region subsequent to the interface region has a larger (220) plane orientation than the interface region using the crystal nucleus oriented in the (220) plane of the interface region as a seed crystal. Is preferred. In the photovoltaic element, it is more preferable that the microcrystals have a columnar structure in the carrier traveling direction because the carrier traveling property is improved.
[0028]
Further, when the silicon-based thin film containing microcrystals contains at least one of an oxygen atom, a carbon atom, and a nitrogen atom, it is preferable for increasing the structural stability by being disposed in a void-like space at the grain boundary. is there. In addition, it is possible to suppress the occurrence of leakage current by increasing the resistance of the crystal grain boundary. Furthermore, although the details of the reason are not clear, it is preferable because it has the effect of improving the uniformity of the cross-sectional size of the microcrystals in order to suppress the generation of new crystal nuclei on the growth surface. These effects are obtained when the total amount of oxygen atoms, carbon atoms, and nitrogen atoms is 1.5 × 10 5. ¹⁸ atoms / cm ^Three Appears effectively. Here, when there are too many total amounts of an oxygen atom, a carbon atom, and a nitrogen atom, it will be taken in into the bulk of a microcrystal and crystallinity will be reduced. The total amount of oxygen, carbon, and nitrogen atoms is 5.0 × 10 ¹⁹ atoms / cm ^Three A preferable range is as follows.
[0029]
In addition, when the silicon-based thin film containing microcrystals contains fluorine atoms, passivation of the grain boundaries of the microcrystals is efficiently performed, and silicon that is manifested in the crystallite grain boundaries by fluorine atoms having a large electronegativity This is preferable because dangling bonds of atoms are inactivated. The amount of fluorine atoms is 1.0 × 10 ¹⁹ atoms / cm ^Three 2.5 × 10 or more ²⁰ atoms / cm ^Three The following is mentioned as a preferable range.
[0030]
In a method of forming a silicon-based thin film using a high frequency plasma CVD method on a substrate introduced into the vacuum vessel by introducing a source gas into the vacuum vessel, the discharge space is reduced by reducing the distance between the high frequency introduction portion and the substrate. It is considered that the plasma density per volume increases, and reactive species contributing to the formation of the deposited film can be formed at a high density, so that the film formation rate can be further increased.
[0031]
On the other hand, it is conceivable that when the distance between the high-frequency introducing portion and the substrate is reduced, the electron density in the plasma increases and the amount of ions generated increases accordingly. Since ions are accelerated by electrostatic attraction in the sheath region in the discharge space, it causes distortion of the atomic arrangement in the bulk as an ion bombardment and causes voids to be formed in the film. It may be a hindrance to the surface, adhesion to the underlying layer, and environmental resistance may be reduced. Here, by increasing the pressure in the film formation space, ions in the plasma are reduced in impact force by increasing the chance of collision with other ions and active species, and the amount of ions. It is considered that it is possible to reduce the ion bombardment, and it can be expected that ion bombardment is relatively lowered.
[0032]
Here, in the high-frequency plasma CVD method using a source gas containing silicon hydride, silicon fluoride and hydrogen as a source gas, SiF _n H _m The generation of active species such as (0 ≦ n, m ≦ 4), HF, F, and H is conceivable. The plasma atmosphere containing these active species seems to be characterized in that there are active species that contribute to etching in addition to active species that contribute to the deposition of silicon-based thin films. For this reason, it is considered that the formation of a silicon-based thin film with a small degree of crystallinity and a small amorphous region is possible by depositing the film while etching Si-Si bonds having a relatively weak bonding force on the film surface. . Moreover, in the process of etching, radicals are formed as the bonds are broken, and structural relaxation is promoted. Therefore, it is considered that a high-quality silicon-based thin film can be formed at a lower process temperature. .
[0033]
Here, in the high-frequency plasma CVD method using a source gas containing fluorinated silicon and hydrogen as a source gas, SiF formed by adding hydrogen to fluorinated silicon. ₂ H, SiFH ₂ It is considered that high-speed film formation becomes possible by forming a fluorinated silane-based active species containing hydrogen. SiF ₂ H, SiFH ₂ In order to form a hydrogen-containing fluorinated silane-based active species, it is important to efficiently decompose fluorinated silicon to form SiF, and further active by the formed SiF and activated hydrogen. The reaction process is considered to be important. In particular, it is considered that the presence of sufficient SiF in the plasma is particularly important.
[0034]
Controlling the plasma process is an important technical issue in order to achieve the formation of a silicon-based thin film having the above-described orientation and crystallinity by high-speed film formation as a whole while depositing and etching. . Here, in order to perform an active reaction process with SiF and activated hydrogen, it is important to increase the plasma density per discharge space volume as described above, but in an atmosphere with an increased electron density in the plasma. Among them, in order to form more activated hydrogen, it is necessary to introduce a source gas so as to suppress depletion of hydrogen molecules. Furthermore, SiH and SiH in plasma ₂ When the radical density increases, crystallization with this as the nucleus is likely to occur in the discharge space and on the surface of the deposited film. SiH and SiH to work as an obstructive factor ₂ It is also necessary to suppress the radical density. In order to achieve these things, while promoting the decomposition of the raw material gas, the supply of new raw material gas is activated, and SiH and SiH ₂ It is considered effective to actively carry out secondary reactions that promote extinction of radicals such as.
[0035]
Here, as a plasma parameter, the volume of the discharge space in which the plasma is generated is expressed as V (m ^Three ), The flow rate of the source gas is Q (cm ^Three / min (normal)), when the pressure in the discharge space is P (Pa), the residence time τ (seconds) defined by τ = 592 × V × P / Q and the emission intensity of the plasma are controlled by plasma. It is considered that plasma having a desired plasma atmosphere can be generated by paying attention as a parameter of. In order to obtain a high-quality silicon-based thin film, it is considered important to control the residence time in addition to the above parameters such as the distance between the high-frequency introducing portion and the substrate and the pressure.
[0036]
In view of the above, as a result of extensive studies by the inventor, in order to form a silicon-based thin film having a low defect density and excellent characteristics at a higher speed, the distance between the high-frequency introducing portion and the substrate Is 3 mm or more and 30 mm or less, and the pressure in the discharge space is 90 Pa (0.68 Torr) or more and 1.5 × 10 6 ^Four Pa (113 Torr) or less, and the volume of the discharge space in which the plasma occurs is V (m ^Three ), The flow rate of the source gas is Q (cm ^Three / min (normal)), where the discharge space pressure is P (Pa), the residence time τ defined by τ = 592 × V × P / Q is in the range of 0.01 seconds to 10 seconds. SiH and SiH ₂ It has been found that the radical density such as can be suppressed and a desired silicon-based thin film can be formed. Here, a method of forming by a CVD method using a high frequency of 10 MHz to 10 GHz is preferable. Furthermore, a method of forming by a CVD method using a high frequency of 20 MHz to 300 MHz is particularly preferable because an electron temperature in the plasma is suppressed and a uniform plasma with a large area is easily formed.
[0037]
In addition, when forming devices such as photovoltaic elements, it is possible to suppress the deterioration of the composition, film quality, characteristics, etc. of the underlying layer due to the reducing action of hydrogen in the plasma atmosphere within the above-mentioned range. Can be eliminated. In the case where a transparent conductive film made of a metal oxide such as zinc oxide is used as the underlayer, it is possible to prevent a decrease in the transmittance of the transparent conductive film due to the reduction, and a decrease in the characteristics of the photovoltaic element due to the reduction. It is effective.
[0038]
Another effect is that the adhesion between the silicon-based thin film and the underlying layer is improved. This is SiF ₂ H, SiFH ₂ It is thought that this effect appears because the deposited film is formed while the stress strain near the surface is always relaxed by the active surface diffusion of radicals. This is particularly effective in a configuration in which the degree of orientation in the silicon-based thin film changes in the film thickness direction. In addition, since the hydrogen partial pressure is relatively increased, the passivation effect of the crystal grain boundary is increased, the inactivation of the crystal grain boundary is promoted, and the rapid detachment of hydrogen atoms incorporated in the silicon network is suppressed, and silicon Since it is possible to prevent plastic flow due to the occurrence of irregular regions in the network and the occurrence of cracks and aggregation, it is possible to form silicon-based thin films with excellent film quality and adhesion. It is considered that a photovoltaic device excellent in environmental resistance can be provided by adopting a configuration including a system thin film.
[0039]
In view of the influence on the groundwork, adhesion, environmental resistance, and the effect of reducing the light deterioration rate, the pressure is 100 Pa (0.75 Torr) or more and 5000 Pa (37.5 Torr) or less, and the residence time is 0.1 seconds or more and 3 seconds. The following are more preferable ranges.
[0040]
By changing the ratio of the gas flow rate in the raw material gas during the formation of the silicon-based thin film, it becomes possible to control the ratio of active species that contribute to deposition in plasma and active species that contribute to etching, It becomes possible to control the orientation of the microcrystals in the silicon-based thin film. In order to form a highly oriented plasma atmosphere, in the fluorinated silicon gas and hydrogen system, the partial pressure of the fluorinated silicon gas in the source gas is increased, and in the silicon hydride gas and hydrogen system, in the source gas In the mixed system of fluorinated silicon gas and silicon hydride gas, the hydrogen partial pressure can be realized under the condition of increasing the partial pressure of fluorinated silicon gas. As a means of changing the plasma atmosphere in the process of depositing the film, a method in which the substrate moves in the plasma space, such as a method of changing the flow rate ratio in the introduced source gas or a roll-to-roll method, is used. In the method, it is also possible to distribute the density of each active species in the plasma. As such a method, a method of introducing a raw material gas from a plurality of gas introduction portions into one plasma space and flowing a raw material gas having a gas flow rate ratio different from that of at least one of them is preferable.
[0041]
When a silicon-based thin film containing a crystalline phase is formed by plasma CVD using high frequency, a deposited film is formed to favor the reaction process such as adsorption, detachment, drawing, implantation, and surface diffusion on the deposited film formation surface. The surface temperature must be properly controlled. For this purpose, it is necessary to heat the substrate surface directly or indirectly using a heating means such as a resistance heater or a lamp heater before forming a silicon-based thin film containing a crystal phase. On the other hand, the generation of plasma is a factor that raises the substrate surface temperature due to the impact of active species from the plasma. This is particularly noticeable when the high frequency power is increased so that the distance between the high frequency introducing portion and the substrate is reduced or the plasma density per discharge space volume is increased. If the temperature of the substrate deposition surface becomes too high, the balance of the reaction processes on the surface will be disturbed, the crystal grain boundary density will increase due to the formation of crystal nuclei, the crystallinity will decrease, and the inactivation of grain boundaries due to passivation will be insufficient. Happen. In addition, when the control of active species contributing to film formation is disturbed, the control of crystal phase orientation is also disturbed.
[0042]
Here, when the temperature of the substrate is controlled using a heating unit disposed on the opposite side of the surface of the silicon-based thin film containing the microcrystals with respect to the substrate, the output of the heating unit is Decreasing with the formation of a silicon-based thin film containing microcrystals is preferable because excessive heating of the film formation surface can be suppressed. Here, in the film forming method in which the substrate moves in the plasma space, such as the roll-to-roll method, the outputs of the plurality of heating means arranged in the transport direction of the substrate depend on the process of forming the deposited film. It is preferable to change them. Specifically, the output of the heater at the position immediately before the start of film formation is the highest, and a method of gradually reducing the output of the heater arranged in the downstream direction of conveyance, or at least a part of the heater during film formation For example, a method of making the output of zero is zero.
[0043]
Next, taking a photovoltaic element as an example of the semiconductor element of the present invention, its constituent elements will be described.
[0044]
FIG. 1 is a schematic cross-sectional view showing an example of the photovoltaic element of the present invention. In the figure, 101 is a substrate, 102 is a semiconductor layer, 103 is a second transparent conductive layer, and 104 is a collecting electrode. Reference numeral 101-1 denotes a substrate, 101-2 denotes a metal layer, and 101-3 denotes a first transparent conductive layer. These are constituent members of the substrate 101.
[0045]
(Substrate)
As the substrate 101-1, a plate-like member or sheet-like member made of metal, resin, glass, ceramics, semiconductor bulk, or the like is preferably used. The surface may have fine irregularities. It is good also as a structure which light injects from the base | substrate side using a transparent base | substrate. Moreover, continuous film formation using a roll-to-roll method can be performed by making the base into a long shape. In particular, a flexible material such as stainless steel or polyimide is suitable as the material of the base 101-1.
[0046]
(Metal layer)
The metal layer 101-2 has a role as an electrode and a role as a reflection layer that reflects light reaching the base 101-1 and reuses it in the semiconductor layer 102. As the material, Al, Cu, Ag, Au, CuMg, AlSi or the like can be suitably used. As the formation method, methods such as vapor deposition, sputtering, electrodeposition, and printing are suitable. It is preferable that the metal layer 101-2 has an uneven surface. Thereby, the optical path length of the reflected light in the semiconductor layer 102 can be extended, and the short circuit current can be increased. When the base 101-1 has conductivity, the metal layer 101-2 may not be formed.
[0047]
(First transparent conductive layer)
The first transparent conductive layer 101-3 has a role of increasing the irregular reflection of incident light and reflected light and extending the optical path length in the semiconductor layer 102. In addition, the element of the metal layer 101-2 has a role of preventing the photovoltaic element from being shunted due to diffusion or migration to the semiconductor layer 102. Furthermore, it has a role of preventing a short circuit due to a defect such as a pinhole in the semiconductor layer by having an appropriate resistance. Furthermore, it is desirable that the first transparent conductive layer 101-3 has irregularities on the surface thereof, like the metal layer 101-2. The first transparent conductive layer 101-3 is preferably made of a conductive oxide such as ZnO or ITO, and is preferably formed using a method such as vapor deposition, sputtering, CVD, or electrodeposition. A substance that changes the conductivity may be added to these conductive oxides.
[0048]
Moreover, as a formation method of a zinc oxide layer, it is preferable to form it combining methods, such as sputtering and electrodeposition, or these methods.
[0049]
The conditions for forming a zinc oxide film by sputtering are greatly affected by the method, gas type and flow rate, internal pressure, input power, deposition rate, substrate temperature, and the like. For example, when a zinc oxide film is formed using a zinc oxide target by a DC magnetron sputtering method, the gas types are Ar, Ne, Kr, Xe, Hg, O ₂ The flow rate varies depending on the size of the apparatus and the exhaust speed. However, for example, when the volume of the film formation space is 20 liters, 1 sccm to 100 sccm is desirable. The internal pressure during film formation is 1 × 10 ^-Four From Torr to 0.1 Torr is desirable. The input power depends on the size of the target, but is preferably 10 W to 100 KW when the diameter is 15 cm. Further, the preferred range of the substrate temperature varies depending on the film forming speed, but when the film is formed at 1 μm / h, it is preferably 70 ° C. to 450 ° C.
[0050]
As a condition for forming the zinc oxide film by the electrodeposition method, it is preferable to use an aqueous solution containing nitrate ions and zinc ions in a corrosion-resistant container. The concentration of nitrate ions and zinc ions is preferably in the range of 0.001 mol / l to 1.0 mol / l, more preferably in the range of 0.01 mol / l to 0.5 mol / l, and More desirably, it is in the range of 1 mol / l to 0.25 mol / l. The source of nitrate ions and zinc ions is not particularly limited, and zinc nitrate, which is the source of both ions, may be used, or water-soluble nitrates such as ammonium nitrate, which is the source of nitrate ions, and zinc ions. It may be a mixture of zinc salts such as zinc sulfate as a supply source. Furthermore, it is also preferable to add carbohydrates to these aqueous solutions in order to suppress abnormal growth or improve adhesion. The type of carbohydrate is not particularly limited, but monosaccharides such as glucose (fructose) and fructose (fructose), disaccharides such as maltose (malt sugar) and saccharose (sucrose), polysaccharides such as dextrin and starch, etc. Or what mixed these can be used. The amount of carbohydrate in the aqueous solution is generally preferably in the range of 0.001 g / l to 300 g / l, more preferably in the range of 0.005 g / l to 100 g / l, depending on the type of carbohydrate. Desirably, it is further desirable to be in the range of 0.01 g / l to 60 g / l. When depositing a zinc oxide film by the electrodeposition method, it is preferable to use the substrate on which the zinc oxide film is deposited in the aqueous solution as a cathode and zinc, platinum, carbon, or the like as an anode. At this time, the density of the current flowing through the load resistance is preferably 10 mA / dm to 10 A / dm.
[0051]
(substrate)
The substrate 101 is formed by laminating the metal layer 101-2 and the first transparent conductive layer 101-3 on the base 101-1, as necessary, by the above method. In order to facilitate the integration of elements, an insulating layer may be provided as an intermediate layer on the substrate 101.
[0052]
(Semiconductor layer)
Si is used as a main material of the semiconductor layer 102 that constitutes a part of the silicon-based thin film of the present invention. In addition to Si, an alloy of Si and C or Ge may be used. To make the semiconductor layer a p-type semiconductor layer, a group III element is contained. To make the semiconductor layer an n-type semiconductor layer, a group V element is contained. As electrical characteristics of the p-type layer and the n-type layer, those having an activation energy of 0.2 eV or less are preferable, and those having an activation energy of 0.1 eV or less are optimal. The specific resistance is preferably 100 Ωcm or less, and most preferably 1 Ωcm or less. In the case of a stack cell (photovoltaic element having a plurality of pin junctions), the pin junction i-type semiconductor layer close to the light incident side has a wide band gap, and the band gap is preferably narrowed as the far pin junction is formed. . The doped layer (p-type layer or n-type layer) on the light incident side is preferably a crystalline semiconductor with little light absorption or a semiconductor with a wide band gap.
[0053]
To further explain the semiconductor layer 102 which is a component of the present invention, FIG. 3 is a schematic cross-sectional view showing a semiconductor layer 102 having a pair of pin junctions as an example of the photovoltaic element of the present invention. . In the figure, reference numeral 102-1 denotes a semiconductor layer having a first conductivity type, and further, an i-type semiconductor layer 102-2 made of a silicon-based thin film of the present invention and a semiconductor layer 102-3 having a second conductivity type are stacked. To do. In a semiconductor layer having a plurality of pin junctions, at least one of them preferably has the above structure.
[0054]
As an example of a stack cell in which two pairs of pin junctions are stacked, as a combination of i-type silicon-based semiconductor layers, from the light incident side (amorphous silicon semiconductor layer, silicon semiconductor layer including microcrystals), (including microcrystals) A silicon semiconductor layer or a silicon semiconductor layer containing microcrystals). In addition, as an example of a photovoltaic element in which three pairs of pin junctions are stacked, as a combination of i-type silicon-based semiconductor layers, from the light incident side (amorphous silicon semiconductor layer, silicon semiconductor layer including microcrystals, including microcrystals Silicon semiconductor layer), (amorphous silicon semiconductor layer, silicon semiconductor layer containing microcrystals, amorphous silicon germanium semiconductor layer), and the like. As an i-type semiconductor layer, the absorption coefficient (α) of light (630 nm) is 5000 cm. ^-1 Above, solar simulator (AM1.5, 100mW / cm ² ) Has a photoconductivity (σp) of 10 × 10 ^-Five S / cm or more, dark conductivity (σd) is 10 × 10 ^-6 It is preferable that S / cm or less and the Urbach energy by the constant photocurrent method (CPM) is 55 meV or less. As the i-type semiconductor layer, even a slightly p-type or n-type layer can be used. When a silicon germanium semiconductor layer is used for the i-type semiconductor layer, germanium is contained in at least one of the p / i interface and the n / i interface for the purpose of reducing the interface state and increasing the open-circuit voltage. A configuration in which no i-type semiconductor layer is inserted may be employed.
[0055]
(Method for forming semiconductor layer)
A high frequency plasma CVD method is suitable for forming the silicon-based thin film and the semiconductor layer 102 of the present invention. Hereinafter, a preferred example of a procedure for forming the semiconductor layer 102 by the high-frequency plasma CVD method will be described.
[0056]
The inside of the vacuum chamber for semiconductor formation that can be in a reduced pressure state is reduced to a predetermined deposition pressure.
[0057]
A material gas such as a source gas or a dilution gas is introduced into the deposition chamber, and the deposition chamber is set to a predetermined deposition pressure while the deposition chamber is evacuated by a vacuum pump.
[0058]
The substrate 101 is set to a predetermined temperature by a heater.
[0059]
A high frequency oscillated by a high frequency power supply is introduced into the deposition chamber. When the high frequency is microwave, the introduction method into the deposition chamber is guided by a waveguide and introduced into the deposition chamber through a dielectric window such as quartz, alumina, aluminum nitride, or the high frequency is VHF or RF. In this method, there is a method in which the light is guided by a coaxial cable and introduced into the deposition chamber through a metal electrode.
[0060]
Plasma is generated in the deposition chamber to decompose the source gas, and a deposited film is formed on the substrate 101 disposed in the deposition chamber. This procedure is repeated a plurality of times as necessary to form the semiconductor layer 102.
[0061]
As conditions for forming the semiconductor layer 102, the substrate temperature in the deposition chamber is 100 to 450 ° C., and the pressure is 0.067 Pa (0.5 mTorr) to 1.5 × 10 6. ^Four Pa (113 Torr), high frequency power density is 0.001 to 2 W / cm ^Three Is a suitable condition. Furthermore, when the silicon-based thin film of the present invention is formed, the distance between the high-frequency introducing portion and the substrate is 3 mm to 30 mm, the pressure is 100 Pa (0.75 Torr) to 5000 Pa (37.5 Torr), and plasma is generated. The volume of the discharge space is V (m ^Three ), The flow rate of the source gas is Q (cm ^Three / min (normal)), when the pressure in the discharge space is P (Pa), the residence time τ defined by τ = 592 × V × P / Q seems to be not less than 0.01 seconds and not more than 10 seconds. It is necessary to make it. The high frequency power density is 0.05 to 2 W / cm. ^Three Is a suitable condition.
[0062]
As a source gas suitable for forming the silicon-based thin film and the semiconductor layer 102 of the present invention, SiF _Four , SiH ₂ F ₂ , SiH _Three F, Si ₂ F ₆ Fluorinated silicon such as SiH _Four , Si ₂ H ₆ In the case of using a silicon hydride compound or alloy system such as GeH _Four And CH _Four It is desirable to introduce a gasifiable compound containing Ge or C into the deposition chamber after being diluted with hydrogen gas. Further, an inert gas such as He may be added. Further, a gasifiable compound containing nitrogen, oxygen or the like may be added as a source gas or a dilution gas. B as a dopant gas for making the semiconductor layer a p-type layer ₂ H ₆ , BF _Three Etc. are used. As a dopant gas for making the semiconductor layer an n-type layer, PH _Three , PF _Three Etc. are used. In the case of depositing a crystal phase thin film or a layer with low light absorption or wide band gap such as SiC, it is preferable to increase the ratio of the dilution gas to the source gas and introduce a high frequency with a relatively high power density.
[0063]
(Second transparent conductive layer)
The second transparent conductive layer 103 is an electrode on the light incident side, and can also serve as an antireflection film by appropriately setting its film thickness. The second transparent conductive layer 103 is required to have a high transmittance in the wavelength region that can be absorbed by the semiconductor layer 102 and to have a low resistivity. The transmittance at 550 nm is preferably 80% or more, and more preferably 85% or more. Resistivity is 5 × 10 ^-3 Ωcm or less, more preferably 1 × 10 ^-3 It is preferable that it is below Ωcm. As the material of the second transparent conductive layer 103, ITO, ZnO, In ₂ O _Three Etc. can be used suitably. As the formation method, methods such as vapor deposition, CVD, spraying, spin-on, and immersion are suitable. You may add the substance which changes electrical conductivity to these materials.
[0064]
(Collector electrode)
The collecting electrode 104 is provided on the transparent electrode 103 in order to improve the collecting efficiency. As the formation method, a method of forming a metal of an electrode pattern by sputtering using a mask, a method of printing a conductive paste or a solder paste, a method of fixing a metal wire with a conductive paste, and the like are suitable.
[0065]
In addition, a protective layer may be formed on both surfaces of the photovoltaic element as necessary. At the same time, a supplementary teaching material such as a steel plate may be used together on the back surface (light incident side and reflection side) of the photovoltaic element.
[0066]
【Example】
In the following examples, the present invention will be specifically described by taking solar cells and TFTs as examples of semiconductor elements, but these examples do not limit the contents of the present invention.
[0067]
[Example 1]
Using the deposited film forming apparatus 201 shown in FIG. 2, the photovoltaic element shown in FIG. 4 was formed by the following procedure. FIG. 4 is a schematic cross-sectional view showing an example of a photovoltaic element having the silicon-based thin film of the present invention. In the figure, members similar to those in FIG. The semiconductor layer of this photovoltaic element is composed of an amorphous n-type semiconductor layer 102-1A, a microcrystalline i-type semiconductor layer 102-2A, and a microcrystalline p-type semiconductor layer 102-3A. That is, this photovoltaic element is a so-called pin type single cell photovoltaic element.
[0068]
FIG. 2 is a schematic cross-sectional view showing an example of a deposited film forming apparatus for producing the silicon-based thin film and the photovoltaic element of the present invention. The deposited film forming apparatus 201 shown in FIG. 2 includes a substrate delivery container 202, semiconductor formation vacuum containers 211 to 218, and a substrate winding container 203 that are connected through gas gates 221 to 229. In this deposited film forming apparatus 201, a strip-shaped conductive substrate 204 is set through each container and each gas gate. The strip-shaped conductive substrate 204 is unwound from a bobbin installed in the substrate feed container 202 and is wound on another bobbin by the substrate take-up container 203.
[0069]
Each of the semiconductor forming vacuum vessels 211 to 218 has a deposition chamber for forming a plasma generation region. In the general deposition chamber, the discharge space in which the plasma is generated is limited by the conductive substrate and the high-frequency introduction part, and the horizontal direction is limited by a discharge plate installed so as to surround the high-frequency introduction part. It is configured.
[0070]
Glow discharge is caused by applying high-frequency power from high-frequency power sources 251 to 258 in the plate-like high-frequency introduction portions 241 to 248 in the deposition chamber, thereby decomposing the source gas and forming a semiconductor layer on the conductive substrate 204. To deposit. The high frequency introducing portions 241 to 248 are opposed to the conductive substrate 204 and are provided with a height adjusting mechanism (not shown). The height adjustment mechanism can change the distance between the conductive substrate and the high-frequency introduction unit, and can simultaneously change the volume of the discharge space. Further, gas introduction pipes 231 to 238 for introducing a source gas and a dilution gas are connected to the respective semiconductor forming vacuum vessels 211 to 218.
[0071]
The deposited film forming apparatus 201 shown in FIG. 2 includes eight semiconductor forming vacuum vessels. However, in the following embodiments, it is not necessary to cause glow discharge in all the semiconductor forming vacuum vessels. The presence or absence of glow discharge in each container can be selected according to the layer structure of the photovoltaic element to be manufactured. Each vacuum chamber for semiconductor formation is provided with a film formation region adjusting plate (not shown) for adjusting the contact area between the conductive substrate 204 and the discharge space in each deposition chamber.
[0072]
First, prior to the formation of the photovoltaic element, an experiment for confirming the orientation of the silicon thin film was performed. A strip-shaped substrate (width 50 cm, length 200 m, thickness 0.125 mm) made of stainless steel (SUS430BA) is sufficiently degreased and washed, and mounted on a continuous sputtering apparatus (not shown), with an Ag electrode as a target and a thickness of 100 nm. An Ag thin film was deposited by sputtering. Further, using a ZnO target, a ZnO thin film having a thickness of 1.2 μm was sputter-deposited on the Ag thin film to form a strip-shaped conductive substrate 204.
[0073]
Next, the bobbin around which the conductive substrate 204 is wound is mounted on the substrate delivery container 202, and the conductive substrate 204 is loaded into the gas gate, semiconductor forming vacuum containers 211, 212, 213, 214, 215, 216, 217, and 218. Then, the tension was adjusted so that the belt-shaped conductive substrate 204 would not sag through the gas gate on the carry-out side to the substrate winding container 203. Then, the substrate delivery container 202, the semiconductor formation vacuum containers 211, 212, 213, 214, 215, 216, 217, 218, and the substrate winding container 203 are 6.7 × by a vacuum exhaust system including a vacuum pump (not shown). 10 ^-Four Pa (5 × 10 ^-6 Torr) was sufficiently evacuated to below.
[0074]
Next, the source gas and the dilution gas were supplied from the gas introduction pipe 232 to the semiconductor formation vacuum vessel 212 while operating the vacuum exhaust system. Here, the deposition chamber in the semiconductor forming vacuum vessel 212 was 1 m in length in the longitudinal direction and 50 cm in width. In addition, a semiconductor forming vacuum vessel other than the semiconductor forming vacuum vessel 212 is 200 cm from the gas inlet tube. ^Three / min (normal) H ₂ Gas is supplied and at the same time from each gate gas supply pipe (not shown) to each gas gate as a gate gas of 500 cm. ^Three / min (normal) H ₂ Gas was supplied. In this state, the exhaust capacity of the vacuum exhaust system was adjusted to adjust the pressure in the semiconductor formation vacuum vessel 212 to a predetermined pressure. The formation conditions are as shown in the formation conditions of 212 in Table 1.
[0075]
When the pressure in the semiconductor formation vacuum vessel 212 was stabilized, the movement of the conductive substrate 204 in the direction from the substrate delivery vessel 202 to the substrate take-up vessel 203 was started.
[0076]
Next, a high frequency is introduced from a high frequency power source 252 into the high frequency introducing portion 242 in the semiconductor forming vacuum vessel 212, and the distance between the conductive substrate and the high frequency introducing portion is set to 9 mm by a height adjusting mechanism. A glow discharge was generated in the deposition chamber in the vacuum vessel 212, and a 1 μm silicon-based thin film was formed on the conductive substrate 204. Here, the semiconductor forming vacuum vessel 212 has a high frequency of 60 MHz and a power density of 400 mW / cm. ^Three It was introduced from a high-frequency introduction portion 242 made of an Al metal electrode while being adjusted so as to be (Comparative Example 1-1).
[0077]
Next, a high frequency is introduced from a high frequency power source 253 into the high frequency introducing portion 243 in the semiconductor forming vacuum vessel 213, and the distance between the conductive substrate and the high frequency introducing portion is set to 9 mm by a height adjusting mechanism. A glow discharge was generated in the deposition chamber in the vacuum vessel 213, and a 1 μm silicon-based thin film was formed on the conductive substrate 204. The forming conditions are as shown in the forming conditions 213 in Table 1. Here, the semiconductor forming vacuum vessel 213 has a high frequency of 60 MHz and a power density of 300 mW / cm. ^Three It was introduced from a high-frequency introduction part 243 made of an Al metal electrode while being adjusted so as to be (Comparative Example 1-2).
[0078]
When the diffraction peak of each formed silicon-based thin film was measured with an X-ray diffractometer, the silicon-based thin film of Comparative Example 1-1 had a maximum diffraction intensity of (400) and 11 reflections from the low angle side. The ratio of the diffraction intensity of (400) to the total diffraction intensity of 80 minutes was 80%, and it was confirmed that the silicon-based thin film of Comparative Example 1-1 was preferentially oriented in the (100) plane. Further, the silicon-based thin film of Comparative Example 1-2 has the maximum diffraction intensity of (220), and the ratio of the diffraction intensity of (220) to the sum of the diffraction intensity of 11 reflections from the low angle side is 90%. It was confirmed that the silicon-based thin film of Comparative Example 1-2 was preferentially oriented in the (110) plane.
[0079]
Next, a photovoltaic element was prepared. The source gas and the dilution gas were supplied from the gas introduction pipes 231, 232, 233, and 235 to the semiconductor forming vacuum vessels 211, 212, 213, and 215 while operating the vacuum exhaust system. Here, the discharge chambers in the semiconductor forming vacuum vessels 212 and 213 are those having a length of 1 m in the longitudinal direction and a width of 50 cm. Further, the semiconductor forming vacuum vessels other than the semiconductor forming vacuum vessels 211, 212, 213, and 215 are 200 cm from the gas introduction tube. ^Three / min (normal) H ₂ At the same time, 500 sccm of H as a gate gas is supplied from each gate gas supply pipe (not shown) to each gas gate. ₂ Gas was supplied. In this state, the evacuation capacity of the evacuation system was adjusted to adjust the pressure in the semiconductor formation vacuum vessels 211, 212, 213, and 215 to a predetermined pressure. The formation conditions are as shown in Table 1.
[0080]
When the pressure in the semiconductor forming vacuum vessels 211, 212, 213, and 215 was stabilized, the movement of the conductive substrate 204 was started in the direction from the substrate delivery container 202 to the substrate winding container 203.
[0081]
Next, a high frequency is introduced from the high frequency power sources 251, 252, 253, 255 into the high frequency introducing portions 241, 242, 243, 245 in the semiconductor forming vacuum vessels 211, 212, 213, 215, and the semiconductor forming vacuum vessel 211, A glow discharge is generated in the deposition chambers 212, 213, and 215, and an amorphous n-type semiconductor layer (thickness 30 nm), an i-type semiconductor layer (thickness 1.5 μm), and microcrystalline p-type are formed on the conductive substrate 204. A semiconductor layer (film thickness: 10 nm) was formed to form a photovoltaic element. Here, the i-type semiconductor layer has a total film thickness of 1.5 μm, and the film formation region adjusting plates in the semiconductor forming vacuum vessels 212 and 213 are adjusted to form respective semiconductors as shown in Table 2. The film thickness of the silicon-based thin film formed in the vacuum container for use was adjusted. (Comparative Example 1-3, Examples 1-1, 1-2, 1-3, 1-4).
[0082]
Here, the vacuum vessel 211 for semiconductor formation has a frequency of 13.56 MHz and a power density of 5 mW / cm. ^Three From the high-frequency introduction portion 241 made of an Al metal electrode, the semiconductor formation vacuum vessel 212, 213 has the same frequency as that of the silicon-based thin film, and the semiconductor formation vacuum vessel 214 has a frequency of 13.56 MHz. Density 30mW / cm ^Three The high frequency power was introduced from a high frequency introducing portion 244 made of an Al metal electrode.
[0083]
Next, the formed strip-shaped photovoltaic device was processed into a 36 cm × 22 cm solar cell module using a continuous modularization apparatus (not shown).
[0084]
The photoelectric conversion efficiency of the solar cell module created as described above was measured using a solar simulator (AM1.5, 100 mW / cm ² ). In addition, the adhesion between the conductive substrate and the semiconductor layer was examined using a cross-cut tape method (a gap between cuts of 1 mm, a number of squares of 100). The results are shown in Table 2.
[0085]
Further, when a cross-sectional TEM observation of the photovoltaic element of Example 1-1 was performed, in the region formed by the semiconductor formation container 212 in the i-type semiconductor layer, the shape of the microcrystal was spherical, and the semiconductor formation container In the region formed by 213, it was found that the shape of the microcrystals was a columnar shape extending perpendicularly to the substrate. Moreover, in each photovoltaic device, it can be confirmed from the RHEED pattern of the sample formed up to the i-type semiconductor layer that the surface layer of each i-type semiconductor layer is preferentially oriented in the (110) plane. It was.
[0086]
From the above, it can be seen that the solar cell including the semiconductor element of the present invention has excellent characteristics. The region in which the (100) plane is preferentially oriented is particularly excellent when the region is 1.0 nm or more and 20 nm or less.
[0087]
[Example 2]
Using the deposited film forming apparatus 201 shown in FIG. 2, the photovoltaic element shown in FIG. 5 was formed by the following procedure. FIG. 5 is a schematic cross-sectional view showing an example of a photovoltaic element having the silicon-based thin film of the present invention. In the figure, members similar to those in FIG. The semiconductor layer of this photovoltaic element is composed of an amorphous n-type semiconductor layer 102-1A, a microcrystalline i-type semiconductor layer 102-2A, an amorphous silicon layer 102-10, and a microcrystalline p-type semiconductor layer 102-3A. ing. That is, this photovoltaic element is a so-called pin type single cell photovoltaic element.
[0088]
Next, a high frequency is introduced from the high frequency power sources 251 to 255 into the high frequency introducing portions 241 to 245 in the semiconductor forming vacuum vessels 211 to 215 to cause glow discharge in the deposition chamber in the semiconductor forming vacuum vessels 211 to 215, An amorphous n-type semiconductor layer (thickness 30 nm), a microcrystalline i-type semiconductor layer (thickness 1.5 μm), an amorphous silicon layer, and a microcrystalline p-type semiconductor layer (thickness 10 nm) are formed over the conductive substrate 204. A photovoltaic element was formed.
[0089]
Here, the conditions in the semiconductor forming vacuum vessels 211, 212, 213, and 215 are the same as in Example 1-2, and the conditions in the semiconductor forming vacuum vessel 214 are shown in Table 3. Further, the semiconductor forming vacuum vessel 214 has a high frequency of 100 MHz and a power density of 100 mW / cm. ^Three It was introduced from a high-frequency introduction part 245 made of an Al metal electrode while adjusting so as to be. Here, a photovoltaic element was formed for each film thickness in Table 4 using a film formation region adjusting plate in the semiconductor forming vacuum vessel 214. Next, the formed strip-shaped photovoltaic element was processed into a 36 cm × 22 cm solar cell module using a continuous modularization apparatus (not shown) (Examples 2-1, 2-2, 2-3, 2-4). ).
[0090]
The photoelectric conversion efficiency of the solar cell module created as described above was measured using a solar simulator (AM1.5, 100 mW / cm ² ). In addition, with the solar cell module whose initial photoelectric conversion efficiency was measured in advance being kept at 50 ° C., AM 1.5, 100 mW / cm ² Table 4 shows the results of measuring photoelectric conversion efficiency again after irradiating the artificial sunlight of 500 hours and examining the change in photoelectric conversion efficiency by the light degradation test.
[0091]
From the above, it can be seen that the solar cell including the semiconductor element of the present invention has excellent characteristics. The amorphous silicon layer having a thickness of 30 nm or less was particularly excellent.
[0092]
[Example 3]
The photovoltaic element shown in FIG. 4 was formed using the deposited film forming apparatus 201 shown in FIG.
[0093]
The forming method is SiF introduced into the vacuum vessel 213 for semiconductor formation. _Four The same procedure as in Example 1-2 was performed, except that a gas into which oxygen was introduced as shown in Table 5 was used. Next, the formed strip-shaped photovoltaic element was processed into a 36 cm × 22 cm solar cell module using a continuous modularization apparatus (not shown) (Examples 3-1, 3-2, 3-3, 3-4). ).
[0094]
The photoelectric conversion efficiency of the solar cell module created as described above was measured using a solar simulator (AM1.5, 100 mW / cm ² ). Also, the solar cell module whose initial photoelectric conversion efficiency has been measured in advance is placed in a dark place at a temperature of 85 ° C. and a humidity of 85% and held for 30 minutes, and then lowered to −20 ° C. over 70 minutes and held for 30 minutes. The temperature was returned to 85 ° C. and the humidity was 85% over 70 minutes. After repeating this cycle 100 times, the photoelectric conversion efficiency was measured again, and the change in the photoelectric conversion efficiency by the temperature and humidity test was examined. Moreover, SIMS measurement of each solar cell module was performed, and the oxygen concentration contained in the silicon-type thin film formed with the vacuum vessel 213 for semiconductor formation was evaluated. These results are shown in Table 6.
[0095]
Further, when a cross-sectional TEM observation of each solar cell module was performed, in the region formed by the semiconductor formation vessel 212 in the i-type semiconductor layer, the shape of the microcrystal was spherical and formed by the semiconductor formation vessel 213. In the region, the shape of the microcrystal is a columnar shape extending perpendicularly to the substrate, and the approximate columnar shape of the solar cell modules of Examples 3-1, 3-2, and 3-3 is Example 1. -2, It was found that the uniformity of the columnar shape size was particularly excellent as compared with that of Example 3-4.
[0096]
From the above, it can be seen that the solar cell including the semiconductor element of the present invention has excellent characteristics. The oxygen concentration in the film is 1.5 × 10 ¹⁸ atoms / cm ^Three 5.0 × 10 or more ¹⁹ atoms / cm ^Three The following were particularly excellent:
[0097]
[Example 4]
The photovoltaic element shown in FIG. 4 was formed using the deposited film forming apparatus 201 shown in FIG.
[0098]
The forming method was performed in the same manner as in Example 1-2, except that the source gas introduced into the semiconductor forming vacuum vessel 213 was the one shown in Table 7. Next, the formed strip-shaped photovoltaic device was processed into a 36 cm × 22 cm solar cell module using a continuous modularization apparatus (not shown) (Examples 4-1, 4-2, 4-3, 4-4). 4-5).
[0099]
The photoelectric conversion efficiency of the solar cell module created as described above was measured using a solar simulator (AM1.5, 100 mW / cm ² ). Also, the solar cell module whose initial photoelectric conversion efficiency has been measured in advance is placed in a dark place at a temperature of 85 ° C. and a humidity of 85% and held for 30 minutes, and then lowered to −20 ° C. over 70 minutes and held for 30 minutes. The temperature was returned to 85 ° C. and the humidity was 85% over 70 minutes. After repeating this cycle 100 times, the photoelectric conversion efficiency was measured again, and the change in the photoelectric conversion efficiency by the temperature and humidity test was examined. Moreover, SIMS measurement of each solar cell module was performed, and the fluorine concentration contained in the silicon-based thin film formed in the vacuum vessel 213 for semiconductor formation was evaluated. These results are shown in Table 7.
[0100]
From the above, it can be seen that the solar cell including the semiconductor element of the present invention has excellent characteristics. Fluorine concentration in the film is 1.0 × 10 ¹⁹ atoms / cm ^Three 2.5 × 10 or more ²⁰ atoms / cm ^Three The following were particularly excellent:
[0101]
[Example 5]
The photovoltaic element shown in FIG. 4 was formed using the deposited film forming apparatus 201 shown in FIG.
[0102]
Table 8 shows the flow rate ratio of gases introduced into the semiconductor forming vacuum vessel 213 by stopping the transport of the conductive substrate when forming the i-type semiconductor layer in the semiconductor forming vacuum vessel 213. The method was performed in the same manner as in Example 2-2, except that the orientation of (220) was gradually increased in the film forming direction. Here, the flow rate of each gas during film formation was changed linearly from the flow rate at the start of film formation to the flow rate at the end of film formation. Next, using the continuous modularization apparatus not shown, the formed strip-shaped photovoltaic element was processed into a 36 cm × 22 cm solar cell module (Example 5).
[0103]
The photoelectric conversion efficiency of the solar cell module created as described above was measured using a solar simulator (AM1.5, 100 mW / cm ² ). The solar cell module of Example 5 was found to have a photoelectric conversion efficiency 1.1 times that of the solar cell module of Example 2-2.
[0104]
From the above, it can be seen that the solar cell including the semiconductor element of the present invention has excellent characteristics.
[0105]
[Example 6]
The photovoltaic element shown in FIG. 4 was formed using the deposited film forming apparatus 201 shown in FIG.
[0106]
The forming method consists of two gas introduction pipes connected to the semiconductor forming vacuum vessel 213 (gas introduction pipes 233-1 and 233-2), and the gas introduction pipe 233-1 is connected to the gas introduction pipe 233-2. Active in the plasma in the vacuum chamber 213 for semiconductor formation is arranged upstream of the transport direction of the conductive substrate, and the flow rate ratio of each source gas flowing from each gas introduction pipe is changed as shown in Table 9. The seed density was changed in the direction of conveyance of the conductive substrate, and the other processes were performed in the same manner as in Example 2-2. The formed strip-shaped photovoltaic element was processed into a 36 cm × 22 cm solar cell module (Example 6).
[0107]
The photoelectric conversion efficiency of the solar cell module created as described above was measured using a solar simulator (AM1.5, 100 mW / cm ² ). The solar cell module of Example 6 was found to have a photoelectric conversion efficiency 1.15 times that of the solar cell module of Example 2-2.
[0108]
From the above, it can be seen that the solar cell including the semiconductor element of the present invention has excellent characteristics.
[0109]
[Example 7]
The photovoltaic element shown in FIG. 4 was formed using the deposited film forming apparatus 201 shown in FIG.
[0110]
In the formation method, the temperature of the lamp heater in the semiconductor formation vacuum vessel 213 is adjusted to increase the film formation temperature in the semiconductor formation vacuum vessel 213 at the start of film formation (the temperature at the upstream position of the transfer is high), and the film formation ends. It was performed in a manner similar to Example 2-2 except that the temperature was sometimes lowered (the temperature at the downstream position of the conveyance was low). Table 10 shows the forming conditions in the semiconductor forming vacuum vessel 213. The formed strip-shaped photovoltaic element was processed into a 36 cm × 22 cm solar cell module (Example 7).
[0111]
The photoelectric conversion efficiency of the solar cell module created as described above was measured using a solar simulator (AM1.5, 100 mW / cm ² ). The solar cell module of Example 6 was found to have a photoelectric conversion efficiency of 1.25 times that of the solar cell module of Example 2-2.
[0112]
From the above, it can be seen that the solar cell including the semiconductor element of the present invention has excellent characteristics.
[0113]
[Example 8]
The photovoltaic device shown in FIG. 4 was formed using the deposited film forming apparatus 201 shown in FIG.
[0114]
The formation method is performed while changing the distance between the conductive substrate and the high-frequency introduction part as shown in Table 11 by the height adjustment mechanism in the semiconductor formation vacuum vessels 212 and 213, and otherwise the embodiment 2 Performed in the same manner as -2. The formed strip-shaped photovoltaic element was processed into a 36 cm × 22 cm solar cell module.
[0115]
The photoelectric conversion efficiency of the solar cell module created as described above was measured using a solar simulator (AM1.5, 100 mW / cm ² ). The results are shown in Table 10. Here, the i-type semiconductor layer with a distance of 2 mm had a poor film thickness uniformity and a large variation in photoelectric conversion efficiency for each solar cell module. And the photoelectric conversion efficiency of the solar cell module whose distance between a conductive substrate and a high frequency introduction part is 3 mm or more and 30 mm or less was excellent.
[0116]
From the above, it can be seen that the solar cell including the semiconductor element of the present invention has excellent characteristics.
[0117]
[Example 9]
The photovoltaic element shown in FIG. 4 was formed using the deposited film forming apparatus 201 shown in FIG.
[0118]
The formation was performed while changing the pressure in the semiconductor vacuum vessel 213 as shown in Table 12, and the other methods were performed in the same manner as in Example 2-2. The formed strip-shaped photovoltaic element was processed into a 36 cm × 22 cm solar cell module.
[0119]
The photoelectric conversion efficiency of the solar cell module created as described above was measured using a solar simulator (AM1.5, 100 mW / cm ² ). In addition, the adhesion between the conductive substrate and the semiconductor layer was examined using a cross-cut tape method (a gap between cuts of 1 mm, a number of squares of 100). Also, the solar cell module whose initial photoelectric conversion efficiency has been measured in advance is placed in a dark place at a temperature of 85 ° C. and a humidity of 85% and held for 30 minutes, and then lowered to −20 ° C. over 70 minutes and held for 30 minutes. The temperature was returned to 85 ° C. and the humidity was 85% over 70 minutes. After repeating this cycle 100 times, the photoelectric conversion efficiency was measured again, and the change in the photoelectric conversion efficiency by the temperature and humidity test was examined. These results are shown in Table 12.
[0120]
From Table 12, the solar cell module including the photovoltaic element produced at a pressure in the semiconductor formation container 213 of 90 Pa or more and 15000 Pa or less is excellent in each item of photoelectric conversion efficiency, peeling test, temperature and humidity test, In particular, it can be seen that a solar cell module including a photovoltaic device manufactured at 100 Pa or more and 5000 Pa or less has excellent characteristics particularly in a peeling test. From the above, it can be seen that the solar cell module including the semiconductor element of the present invention has excellent features.
[0121]
[Example 10]
The photovoltaic element shown in FIG. 4 was formed using the deposited film forming apparatus 201 shown in FIG.
[0122]
The formation was carried out in the same manner as in Example 2-2, except that the residence time in the semiconductor vacuum vessels 212 and 213 was changed as shown in Table 13. The formed strip-shaped photovoltaic element was processed into a 36 cm × 22 cm solar cell module.
[0123]
From Table 13, the solar cell module including the photovoltaic element produced in the residence time in the semiconductor formation container 212 of 0.1 second or more and 10 seconds or less has each of photoelectric conversion efficiency, peeling test, temperature / humidity test, and photodegradation rate. It is excellent in terms of items, and in particular, it can be seen that the solar cell module including the photovoltaic element manufactured in 0.2 seconds to 3.0 seconds has particularly excellent characteristics in the peeling test. From the above, it can be seen that the solar cell module including the semiconductor element of the present invention has excellent features.
[0124]
[Example 11]
Using the deposited film forming apparatus 201 shown in FIG. 2, the photovoltaic element shown in FIG. 5 was formed by the following procedure. FIG. 7 is a schematic cross-sectional view showing an example of a photovoltaic device having the silicon-based thin film of the present invention. In the figure, members similar to those in FIG. The semiconductor layers of this photovoltaic element are amorphous n-type semiconductor layers 102-1A and 102-4, a microcrystalline i-type semiconductor layer 102-2A, and an amorphous i-type semiconductor layer 102-5. It consists of an amorphous silicon layer 102-10 and microcrystalline p-type semiconductor layers 102-3A and 102-6. That is, this photovoltaic element is a so-called pinpin type double cell photovoltaic element.
[0125]
Similarly to the first embodiment, a strip-shaped conductive substrate 204 is prepared and mounted on the deposition film forming apparatus 201, and the substrate delivery container 202, semiconductor forming vacuum containers 211, 212, 213, 214, 215, 216, 217, 218. The substrate winding container 203 is 6.7 × 10 6 by an evacuation system including a vacuum pump (not shown). ^-Four Pa (5 × 10 ^-6 Torr) was sufficiently evacuated to below.
[0126]
Next, the source gas and the dilution gas were supplied from the gas introduction pipes 231 to 238 to the semiconductor forming vacuum vessels 211 to 218 while operating the vacuum exhaust system. Here, the discharge chambers in the semiconductor forming vacuum vessels 212 and 213 are those having a length of 1 m in the longitudinal direction and a width of 50 cm. Further, from each gate gas supply pipe (not shown), 500 sccm of H as a gate gas is supplied to each gas gate. ₂ Gas was supplied. In this state, the exhaust capacity of the vacuum exhaust system was adjusted to adjust the pressure in the semiconductor forming vacuum vessels 211 to 216 to a predetermined pressure. The formation conditions for the semiconductor forming vacuum vessels 211 to 215 are the same as in Example 2-2, and the semiconductor forming vacuum vessels 216 to 218 are as shown in Table 14.
[0127]
When the pressure in the semiconductor formation vacuum vessels 211 to 218 was stabilized, the conductive substrate 204 started to move from the substrate delivery container 202 toward the substrate take-up container 203.
[0128]
Next, a high frequency is introduced from the high frequency power sources 251 to 258 into the high frequency introducing portions 241 to 248 in the semiconductor forming vacuum vessels 211 to 218 to cause glow discharge in the deposition chambers in the semiconductor forming vacuum vessels 211 to 218, On the conductive substrate 204, an amorphous n-type semiconductor layer (thickness 30 nm), a microcrystalline i-type semiconductor layer (thickness 2.0 μm), a microcrystalline p-type semiconductor layer (thickness 10 nm), an amorphous n-type semiconductor layer ( A photovoltaic element was formed by forming an amorphous i-type semiconductor layer (film thickness 300 nm) and a microcrystalline p-type semiconductor layer (film thickness 10 nm). Here, 10 nm of the microcrystalline i-type semiconductor layer was formed in the semiconductor forming vacuum vessel 212. Here, the vacuum vessels 211 and 216 for forming semiconductors have a frequency of 13.56 MHz and a power density of 5 mW / cm. ^Three From the high-frequency introduction portions 241 and 246 made of metal electrodes made of Al to the vacuum vessel 212 for semiconductor formation, a high-frequency power of 60 MHz and a power density of 400 mW / cm ^Three From the high-frequency introduction part 242 made of an Al metal electrode while adjusting so that a high frequency with a frequency of 60 MHz is applied to the vacuum vessel 213 for semiconductor formation, the power density is 300 mW / cm. ^Three From the high-frequency introducing portion 243 made of an Al metal electrode while adjusting so that a high frequency with a frequency of 100 MHz is applied to the semiconductor forming vacuum vessels 214 and 217, the power density is 100 mW / cm. ^Three From the high-frequency introducing portions 244 and 247 made of Al metal electrodes to the semiconductor forming vacuum vessels 215 and 218, the frequency is 13.56 MHz and the power density is 30 mW / cm. ^Three The high frequency power was introduced from high frequency introducing portions 245 and 248 made of metal electrodes made of Al. Next, the formed strip-shaped photovoltaic device was processed into a 36 cm × 22 cm solar cell module using a continuous modularization apparatus (not shown).
[0129]
The photoelectric conversion efficiency of the solar cell module created as described above was measured using a solar simulator (AM1.5, 100 mW / cm ² ), The photoelectric conversion efficiency value was 1.2 times that of the single solar cell module in Example 2-2. Or a favorable result was shown also in the peeling test and the temperature / humidity test, and it can be seen from the above that the solar cell module including the semiconductor element of the present invention has excellent features.
[0130]
[Example 12]
An inverted stagger type TFT was formed by the following procedure. FIG. 8 is a schematic cross-sectional view showing an example of an inverted stagger type TFT having the semiconductor element of the present invention. A glass substrate 301 is used as an insulating substrate, a gate electrode 302 is formed thereon, a gate insulating film 303, an active layer 304 made of an undoped silicon layer, and a low resistance in the source and drain regions on the active layer 304 n ⁺ An ohmic contact layer 305 made of type amorphous silicon and a source / drain electrode 306 are formed.
[0131]
First, a Mo—Ta alloy film layer was formed on a glass substrate 301 by a sputtering method and patterned to form a gate electrode 302. Next, a gate insulating film 303 made of a silicon oxide film was formed by a CVD method. Thereafter, a glass substrate is set in the semiconductor forming vacuum vessel 212 of FIG. 2 to form a 15 nm thick silicon-based thin film preferentially oriented on the (100) plane of Example 1, and then in the semiconductor forming vacuum vessel 213. A glass substrate was set, a silicon-based thin film preferentially oriented on the (110) plane of Example 1 was formed to 65 nm, and an active layer 304 of 80 nm was formed together. Next, a glass substrate is set in the vacuum chamber 211 for semiconductor formation and n ⁺ An ohmic contact layer 305 made of type amorphous silicon was deposited and patterned through a lithography process. Further, a metal film was formed and patterned to form a source / drain electrode 306. Finally, CF _Four And O ₂ Using the mixed gas, the ohmic contact layer 305 exposed between the source and drain electrodes 306 was etched to form a TFT (Example 12).
[0132]
A TFT was formed in the same manner as in Example 12 except that the active layer 304 was formed of an amorphous silicon layer with a thickness of 80 nm (Comparative Example 12-1).
[0133]
A TFT was formed in the same manner as in Example 12 except that the active layer 304 was formed to be 80 nm only from a silicon-based thin film preferentially oriented on the (100) plane (Comparative Example 12-2).
[0134]
In the TFT of Example 12, overetching of the active layer 304 did not occur when the ohmic contact layer 305 was etched, but in the TFT of the comparative example, overetching occurred and the active layer was thinned and the film thickness was not uniform. Happened. In particular, excessive etching occurred greatly in the TFT of Comparative Example 12-1. Further, due to etching damage, a leak path was generated in the active layer, and the value of the off current was larger than that in Example 12.
[0135]
From the above, it can be seen that the TFT including the semiconductor element of the present invention has excellent features.
[0136]
【The invention's effect】
In a semiconductor element having a semiconductor junction made of a silicon-based thin film, at least one of the silicon-based thin films contains microcrystals, and the orientation of the microcrystals in the silicon-based thin film containing the microcrystals is determined by the microcrystals. In a semiconductor element characterized by changing in the film thickness direction in a silicon-based thin film containing silicon, it is possible to form a semiconductor element having good electrical characteristics and excellent adhesion and environmental resistance at low cost. it can.
[0137]
[Table 1]

[0138]
[Table 2]

Photoelectric conversion efficiency is normalized to 1 in Comparative Example 1-3.
The peeling test means that the number of peeled eyes is ◎ 0, ○ 1-2, △ 3-10, × 10-100
[0139]
[Table 3]

[0140]
[Table 4]

The photoelectric conversion efficiency and the light deterioration rate are those obtained by standardizing the value of Example 2-1 to 1.
[0141]
[Table 5]

[0142]
[Table 6]

[0143]
[Table 7]

[0144]
[Table 8]

[0145]
[Table 9]

[0146]
[Table 10]

[0147]
[Table 11]

Each value is normalized to 1 when the distance between the conductive substrate and the high-frequency introduction part is 3 mm.
[0148]
[Table 12]

The photoelectric conversion efficiency is a value obtained by standardizing the value when the pressure in the semiconductor formation container 213 is 50 Pa to 1.
The peeling test means that the number of peeled eyes is ◎ 0, ○ 1-2, △ 3-10, × 10-100
Temperature / humidity test is (photoelectric conversion efficiency after test) / (photoelectric conversion efficiency before test)
[0149]
[Table 13]

The photoelectric conversion efficiency is a value obtained by standardizing the value when the residence time in the semiconductor formation containers 212 and 213 is 0.008 seconds to 1.
The peeling test means that the number of peeled eyes is ◎ 0, ○ 1-2, △ 3-10, × 10-100
Temperature / humidity test is (photoelectric conversion efficiency after test) / (photoelectric conversion efficiency before test)
[0150]
[Table 14]

[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing an example of a photovoltaic element including a semiconductor element of the present invention.
FIG. 2 is a schematic cross-sectional view showing an example of a deposited film forming apparatus for manufacturing a semiconductor element and a photovoltaic element of the present invention.
FIG. 3 is a schematic cross-sectional view showing an example of a semiconductor layer including a semiconductor element of the present invention.
FIG. 4 is a schematic cross-sectional view showing an example of a photovoltaic element including the semiconductor element of the present invention.
FIG. 5 is a schematic cross-sectional view showing an example of a photovoltaic element including the semiconductor element of the present invention.
FIG. 6 is a schematic cross-sectional view showing an example of a deposited film forming apparatus for manufacturing a semiconductor element and a photovoltaic element of the present invention.
FIG. 7 is a schematic cross-sectional view showing an example of a photovoltaic element including the semiconductor element of the present invention.
FIG. 8 is a schematic cross-sectional view showing an example of a TFT including the semiconductor element of the present invention.
(Explanation of symbols)
101 substrate,
101-1 substrate,
101-2 metal layer,
101-3 first transparent conductive layer,
102 semiconductor layer,
102-1 a semiconductor layer exhibiting a first conductivity type,
102-1A amorphous n-type semiconductor layer,
102-2 i-type semiconductor layer,
102-2A microcrystalline i-type semiconductor layer,
102-3 a semiconductor layer exhibiting a second conductivity type,
102-3A microcrystalline p-type semiconductor layer,
102-4 amorphous n-type semiconductor layer,
102-5 amorphous i-type semiconductor layer,
102-6 microcrystalline p-type semiconductor layer,
102-10 amorphous silicon layer,
103 transparent electrode,
104 current collecting electrode,
201 deposited film forming apparatus,
202 substrate delivery container,
203 substrate winding container,
204 conductive substrate,
211-218 Vacuum containers for semiconductor formation,
221 to 229 gas gates,
231 to 238 gas introduction pipes,
233-1, 233-2 gas introduction pipe,
241 to 248, high-frequency introduction section,
251 to 258 high frequency power supply,
301 glass substrate,
302 gate electrode,
303 gate insulating film,
304 active layer,
305 ohmic contact layer,
306 Source and drain electrodes.

Claims (9)

A photovoltaic device comprising at least one pin-type semiconductor junction comprising a p-type semiconductor layer containing silicon atoms as a main component, an i-type semiconductor layer, and an n-type semiconductor layer on a substrate, The type semiconductor layer contains microcrystals and fluorine atoms of 1.0 × 10 ¹⁹ atoms / cm ³ or more and 2.5 × 10 ²⁰ atoms / cm ³ or less,
An interface region between the i-type semiconductor layer and the p-type semiconductor layer or the n-type semiconductor layer which is a base layer of the i-type semiconductor layer, the i-type semiconductor layer and the p-type semiconductor layer or the n-type semiconductor layer; The crystallites in the interface region from 1.0 nm to 20 nm from the interface are preferentially oriented in the (100) plane,
The orientation of the (220) plane, which is the ratio of the diffraction intensity of the (220) plane by the X-ray or electron beam of the microcrystal in the layer thickness direction of the i-type semiconductor layer to the total diffraction intensity, is an underlayer of the i-type semiconductor layer The photovoltaic element according to claim 1, wherein the photovoltaic element is small on the p-type semiconductor layer or n-type semiconductor layer side and changes so as to increase with distance from the base layer.   An amorphous silicon layer is disposed between the i-type semiconductor layer containing microcrystals and a semiconductor layer having a conductivity type disposed on the light incident side with respect to the i-type semiconductor layer. The photovoltaic device according to claim 1. The photovoltaic element according to claim 2 , wherein the amorphous silicon layer has a thickness of 30 nm or less.   The i-type semiconductor layer including the microcrystal includes a region in which the ratio of the diffraction intensity of the (220) plane by the X-ray or electron beam of the microcrystal to the total diffraction intensity is 80% or more. The photovoltaic element as described in.   The microcrystal having a preferential orientation of (110) plane in the i-type semiconductor layer including the microcrystal has a columnar shape extending in a vertical direction with respect to the substrate. Item 2. The photovoltaic device according to Item 1.   The photovoltaic element according to claim 1, wherein the crystallites in the interface region have a substantially spherical shape. The i-type semiconductor layer including the microcrystal includes at least one of an oxygen atom, a carbon atom, and a nitrogen atom, and the total amount thereof is 1.5 × 10 ¹⁸ atoms / cm ³ or more and 5.0 × 10 ¹⁹ atoms / cm ^3. The photovoltaic element according to claim 1, wherein: A TFT having a gate electrode, a gate insulating film, an active layer, a contact layer, a source electrode, and a drain electrode on a substrate,
The gate insulating film is disposed between the gate electrode and the active layer, and the contact layer is disposed between the active layer and the source electrode or the drain electrode,
The active layer includes microcrystals and fluorine atoms of 1.0 × 10 ¹⁹ atoms / cm ³ or more and 2.5 × 10 ²⁰ atoms / cm ³ or less,
There are microcrystals in an interface region between the active layer and the gate insulating layer which is an underlayer of the active layer, the interface region being 1.0 nm or more and 20 nm or less from the interface between the active layer and the gate insulating layer (100 ) Is preferentially oriented to the surface,
The orientation of the (220) plane, which is the ratio of the diffraction intensity of the (220) plane by X-rays or electron beams of the microcrystal in the layer thickness direction of the active layer to the total diffraction intensity, is small on the gate insulating film side, and the gate A TFT that changes so as to increase with distance from an insulating film. A method of forming an i-type semiconductor layer containing silicon atoms containing microcrystals as a main component on a base layer selected from a p-type semiconductor layer, an n-type semiconductor layer, or an insulating layer, and hydrogenating the vacuum container Introducing at least one of silicon and fluorinated silicon gas and a source gas containing hydrogen;
By changing the ratio of the raw material gas flow rate containing at least one of the silicon hydride and fluorinated silicon gas or the hydrogen, and supplying hydrogen to the growth surface in an atmosphere having a low etching effect,
The i-type semiconductor layer contains 1.0 × 10 ¹⁹ atoms / cm ³ or more and 2.5 × 10 ²⁰ atoms / cm ³ or less fluorine atoms;
An interface region between the i-type semiconductor layer and the p-type semiconductor layer or the n-type semiconductor layer which is a base layer of the i-type semiconductor layer, the i-type semiconductor layer and the p-type semiconductor layer or the n-type semiconductor layer; The crystallites in the interface region from 1.0 nm to 20 nm from the interface are preferentially oriented in the (100) plane,
The orientation of the (220) plane, which is the ratio of the diffraction intensity of the (220) plane by the X-ray or electron beam of the microcrystal in the film thickness direction of the i-type semiconductor layer to the total diffraction intensity, is at the initial stage of formation of the silicon-based thin film. The method for forming an i-type semiconductor layer is characterized in that it is small and changes so as to increase as the film is deposited.

Images