KR101659156B1 - Structure for electronic device, plasma cvd apparatus and film forming method - Google Patents

Abstract

[PROBLEMS] To provide a technique for forming a thin film on a substrate which has no interface with the film and which is not single in film quality.
The gas supply unit 6A supplies the first material gas to the upstream side of the discharge space 615 in the transport direction of the processing space V and the gas supply unit 6B supplies the first material gas to the processing space V rather than the discharge port 625. [ The second material gas is supplied to the downstream side in the carrying direction of the first material gas. Thus, in the interior of the processing space V, a continuously changing atmosphere is formed from the upstream side to the downstream side, from the space filled with the first material gas to the space filled with the second material gas. A plasma CVD process is carried out while the substrate 9 is transported at a position opposed to the process space (V). The composition of the CVD film 110 formed on the main surface of the substrate 9 becomes a composition which continuously changes from the first material composition to the second material composition in the normal direction away from the main surface.

Description

TECHNICAL FIELD [0001] The present invention relates to a structure for an electronic device, a plasma CVD apparatus, and a deposition method.

 TECHNICAL FIELD [0001] The present invention relates to a plasma CVD apparatus, a film forming method by a plasma CVD process, and a plasma CVD process.

The plasma process plays a large role in various electronic device manufacturing processes such as a silicon-based solar cell manufacturing process. For example, Patent Document 1 describes an apparatus for forming a thin film on a substrate by plasma enhanced chemical vapor deposition (plasma CVD).

Japanese Patent Application Laid-Open No. 11-214729

More specifically, in Patent Document 1, an apparatus in which a plurality of plasma sources are arranged along a substrate carrying direction, and a plasma CVD process is sequentially performed on the substrates conveyed in a roll-to-roll manner, . As a result, a multilayer thin film corresponding to the plurality of plasma sources is formed on the substrate.

However, when a multilayer thin film is formed on a substrate, since an interface is formed between the respective layers, various problems arise due to the presence of an interface. For example, in a solar cell, it is preferable to put more light into the device without reflecting the light emitted from the outside. However, if there is an interface between the respective layers of the thin film on the substrate, light is reflected at the interface, The amount of light that is present is reduced.

As a constitution in which the interface is not formed in the thin film, it is conceivable to form a thin film of a single layer on a substrate. This can be considered as various problems due to a single film quality (for example, a uniform refractive index) Lt; / RTI > For example, in a solar cell, there is a difference in refractive index in a thin film on a substrate, so that a phase difference is generated in each reflection light in the film, thereby reducing the internal reflection as a whole and increasing the amount of light that can be accommodated in the device , And this effect can not be obtained in a single-layer thin film.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a technique for forming a thin film on a substrate which has no film interface and which is not single in film quality.

The invention according to claim 1 is characterized in that it comprises a substrate and a CVD film formed on the main surface of the substrate by a plasma CVD method, wherein in the normal direction away from the main surface, the composition of the CVD film is changed from a first material composition to a second material composition And the second electrode layer is continuously changed from the first electrode layer to the second electrode layer.

The invention according to claim 2 is the electronic device structure as set forth in claim 1, wherein the first material composition and the second material composition are such that the plural kinds of composition elements contained in each are common to each other, Characterized in that the content ratios of the elements are different from each other.

According to a third aspect of the invention, there is provided an electronic device structure as set forth in the first aspect, wherein a composition element included in the first material composition and a composition element included in the second material composition are different from each other.

According to a fourth aspect of the present invention, in the structure for an electronic device according to any one of the first to third aspects, the substrate is a semiconductor substrate for a solar cell, and the CVD film is a protective film for the solar cell.

According to a fifth aspect of the present invention, in the structure for an electronic device according to the fourth aspect, the CVD film includes a silicon nitride film.

According to a sixth aspect of the present invention, there is provided a plasma processing apparatus comprising: a chamber; a holding and conveying section that holds the substrate to be processed and relatively conveys the substrate along the conveying path; A plurality of inductively coupled antennas each of which has a number of turns of less than one week; a first gas supply unit for supplying a first material gas to an upstream portion of the processing space along the conveyance path; And a second gas supply part for supplying a second material gas having a composition different from that of the first material gas to the downstream part along the transfer path, wherein the first material gas is supplied from the first gas supply part, The second material gas is supplied from the gas supply unit, and the high frequency power is supplied to the plurality of inductively coupled antennas to generate plasma , The substrate is conveyed along the conveying path by the holding and conveying section so that on the main surface of the substrate, with respect to the normal direction away from the main surface, the first material corresponding to the first material gas Wherein a CVD film having a composition continuously changed from a composition of the first material gas to a second material composition corresponding to the second material gas is formed.

According to a seventh aspect of the present invention, there is provided a plasma CVD apparatus according to the sixth aspect, further comprising: a first partitioning member disposed on an upstream side of the plurality of inductively coupled antennas with the plate- And a second partitioning member disposed on a downstream side of the plurality of inductively coupled antennas along the conveying path with a plate member perpendicular to the conveying path, wherein the first partitioning member and the second partitioning member are arranged in the conveying direction of the processing space Is defined by the width of the wing.

The invention according to claim 8 is the plasma CVD apparatus according to claim 6, wherein the first material gas and the second material gas each have a plurality of kinds of composition elements common to each other, Are different from each other.

According to a ninth aspect of the present invention, in the plasma CVD apparatus according to the sixth aspect, the composition element included in the first material gas and the composition element included in the second material gas are different from each other.

The invention described in claim 10 is the plasma CVD apparatus according to any one of claims 6 to 9, wherein the substrate is a semiconductor substrate for a solar cell, and the CVD film is a protective film of the solar cell.

The invention according to claim 11 is the plasma CVD apparatus according to claim 10, wherein at least one of the first material gas and the second material gas contains silane and ammonia, and the CVD film includes a silicon nitride film do.

According to a twelfth aspect of the present invention, there is provided a film forming method for forming a CVD film on a main surface of a substrate to be subjected to plasma processing in a processing space in which a plurality of inductively coupled antennas each having fewer than one turn are arranged, A first gas supply step of supplying a first material gas to an upstream part of the processing space along the conveyance path; and a second gas supply step of supplying a first material gas to a second part of the processing space, A second gas supply step of supplying a material gas to the plurality of inductively coupled antennas; and a second gas supply step of supplying a high frequency electric power to the plurality of inductively coupled antennas to generate plasma, and chemical vapor deposition by plasma decomposition of the first and second material gases, And a transferring step of transferring the substrate along the transfer path, And a second material composition corresponding to the first material gas and a second material composition corresponding to the second material gas, the composition of the first material corresponding to the first material gas and the composition of the second material corresponding to the second material gas, And a film is formed.

In the structure according to any one of claims 1 to 5, a CVD film which continuously changes from a first material composition to a second material composition in a normal direction away from the main surface is formed on the main surface of the substrate. Since the change of the material composition in the CVD film is continuous, various problems (for example, reduction in the amount of light that can be put into the device in the solar cell due to reflection at the interface) due to the presence of the interface do not occur . Further, since the composition of the material in the CVD film is continuously changed, there are various problems caused by the single film quality (for example, a high refractive index difference in the thin film does not exist, The amount of light is reduced, etc.) does not occur.

The plasma CVD apparatus described in claims 6 to 11 is an apparatus particularly suitable for obtaining the structure for an electronic device according to claim 1.

The film forming method according to claim 12 is a film forming method particularly suitable for obtaining the electronic device structure described in claims 1 to 5.

1 is a YZ side view schematically showing a schematic configuration of a plasma processing apparatus.
2 is an XZ side view schematically showing a schematic configuration of a plasma processing apparatus.
3 is a diagram for explaining an arrangement relationship of a plurality of inductively coupled antennas.
4 is a side view of the structure 10 and a view for explaining the refractive index of the CVD film 110. FIG.
5 is a diagram showing the spectral reflectance of the CVD film in the structures 10, 10Y, and 10Z.
6 is a view for explaining the refractive index of the CVD film 110 according to the modification.

Hereinafter, embodiments will be described with reference to the drawings. The following embodiments are illustrative of the present invention and do not limit the technical scope of the present invention. In the drawings, for the sake of easy understanding, the dimensions and numbers of the respective parts are exaggerated or simplified.

<Overall Configuration of Plasma CVD Apparatus 100>

1 is a YZ side view schematically showing a schematic configuration of a plasma CVD apparatus 100. As shown in Fig. 2 is a cross-sectional view taken along the line A-A in Fig. 1 and is an XZ side view schematically showing a schematic configuration of the plasma CVD apparatus 100. Fig. In the drawings, XYZ orthogonal coordinate axes with the X axis as the horizontal plane and the Z axis as the vertical axis are appropriately attached for the sake of clarifying the directional relationship. In order to prevent the city from becoming complicated, the gas supply unit 6C, which will be described later, is omitted in Fig.

The plasma CVD apparatus 100 is a plasma CVD apparatus in which a CVD film (for example, a silicon oxide film) is formed on a substrate 9 (for example, a semiconductor substrate for a solar battery) Protective film).

The plasma CVD apparatus 100 includes a processing chamber 1 for forming a processing space V therein and a substrate 9 (specifically, a substrate 9 disposed on the carrier 90) A heating unit 3 for heating the substrate 9 to be transported and a plasma generating unit 4 for generating plasma in the process space V And two partition members 5A and 5B that define the width of the processing space V in the carrying direction.

The plasma CVD apparatus 100 further includes gas supply units 6A to 6C for supplying gas to the process space V and an exhaust unit 7 for exhausting gas from the inside of the process chamber 1. [ The plasma CVD apparatus 100 further includes a control unit 8 for controlling the above-described components.

&Lt; Process chamber (1) >

The processing chamber 1 is a hollow member having a processing space V therein. Here, the processing space V is a space in which plasma CVD processing is performed by the inductively coupled antenna 41 described later. In this embodiment, one processing space V is provided in the section of the partitioning members 5A and 5B Respectively.

The top plate 11 of the processing chamber 1 is disposed such that the bottom surface 111 thereof is in a horizontal posture and the inductively coupled antenna 41 and the partition member (All of which will be described later) protrude. A heating unit 3 is disposed in the vicinity of the bottom plate of the processing chamber 1. [ On the upper side of the heating section 3, a conveying path (a path along the Y direction) of the substrate 9 by the holding and conveying section 2 is defined. On the side wall of the processing chamber 1 on the + Y side, for example, an unloading inlet (not shown) opened and closed by a gate valve is provided.

<Holding and conveying section (2)>

The holding and conveying section 2 holds the carrier 90 in a horizontal posture and conveys the carrier 90 along a conveying path through an exit opening formed in the processing chamber 1. [ On the upper surface of the carrier 90, a plurality of substrates 9 (nine substrates 9 in total, that is, 3x3 in the X direction and Y direction in this embodiment) as objects to which the film is attached are arranged. A processing space V for plasma CVD processing is formed at a position above the conveying path and at a position opposite to the plurality of substrates 9 conveyed on the conveying path.

More specifically, the holding and conveying section 2 includes a pair of conveying rollers 21 disposed opposite to each other with a conveying path therebetween, and a driving section (not shown) for rotationally driving the conveying rollers 21 in synchronism with each other. A pair of conveying rollers 21 are provided, for example, in a plurality of pairs in the extending direction (the Y direction in the drawing) of the conveying path. In this configuration, the carrier 90 is conveyed along the conveying path by rotating the conveying rollers 21 while coming into contact with the lower surface of the carrier 90. As a result, the substrate 9 held by the carrier 90 is moved relative to the processing space V having the inductively coupled antenna 41. [

&Lt; Heating part (3) >

The heating portion 3 is a member for heating the substrate 9 held and conveyed by the holding and conveying portion 2 and is provided below the holding and conveying portion 2 (that is, below the conveyance path of the substrate 9) . The heating section 3 can be constituted by, for example, a ceramic heater. Further, the plasma CVD apparatus 100 may be further provided with a mechanism for cooling the substrate 9 and the like held by the holding and conveying section 2.

&Lt; Plasma Generating Section (4)

The plasma generating section 4 generates a plasma in the process space V. The plasma generating section 4 includes a plurality of (in this embodiment, four) inductively coupled antennas 41 which are inductively coupled type high-frequency antennas. Specifically, each inductively coupled antenna 41 is formed by bending a metal pipe-shaped conductor into a U-shape and covering it with a dielectric such as quartz.

The plurality of inductively coupled antennas 41 are arranged at intervals (preferably equidistantly) along the predetermined direction and are fixed with respect to the top plate 11. 3 is a partially enlarged view showing an arrangement of a plurality of inductively coupled antennas 41 in the present embodiment. 3, the plurality of inductively coupled antennas 41 are arranged such that the center point C of a line segment L connecting the both ends of each of the plurality of inductively coupled antennas 41 is arranged on a predetermined virtual axis K, As shown in FIG. It is to be noted that this imaginary axis K is formed in a direction intersecting the carrying direction (Y direction) of the substrate 9 (particularly preferably in a direction perpendicular to the carrying direction of the substrate 9 ), And is preferably a shaft extending parallel to the side walls of the processing chamber 1 on the + Y side.

In the illustrated example, the line segment L connecting the both ends of the inductively coupled antenna 41 and the imaginary axis K are parallel (that is, each of the plurality of inductively coupled antennas 41 is arranged in the array direction And the line segment L and the imaginary axis K are not necessarily in parallel with each other. That is, the angle formed by the line segment L and the virtual axis K may be zero or more. For example, the line segment L and the virtual axis K may be orthogonal. In this case, the respective inductively coupled antennas 41 are arranged in a posture orthogonal to the arrangement direction.

In the illustrated example, four inductively coupled antennas 41 are provided along the virtual axis K, but the number of the inductively coupled antennas 41 arranged along the imaginary axis K must be four The number of the processing chambers 1 can be appropriately selected depending on the dimensions of the processing chamber 1 and the like. The inductively coupled antenna 41 may be arranged in a matrix or zigzag shape. That is, a plurality of virtual axes K arranged at intervals along the Y direction may be defined, and a plurality of inductively coupled antennas 41 may be arranged along each of the plurality of imaginary axes K.

One end of each inductively coupled antenna 41 is connected to the high frequency power source 44 through the feeder 42 and the matching box 43. The other end of each inductively coupled antenna 41 is grounded. In this configuration, when a high-frequency current (specifically, a high-frequency current of, for example, 13.56 MHz) flows from the high-frequency power supply 44 to each of the inductively coupled type antennas 41, Electrons are accelerated by an electric field (high frequency induction electric field), and a plasma (inductively coupled plasma (ICP)) is generated.

As described above, the inductively coupled antenna 41 has a U-shape. The U-shaped inductively coupled antenna 41 corresponds to an inductively coupled antenna having a number of turns of less than one week, and has an inductance lower than that of the inductively coupled antenna having a number of turns of one or more times. And the high frequency oscillation of the plasma potential accompanying the electrostatic coupling to the generated plasma is suppressed. As a result, the excessive electron loss accompanying the fluctuation of the plasma potential on the ground potential is reduced, and the plasma potential is particularly suppressed to be low. Such an inductively coupled high frequency antenna is disclosed in Japanese Patent No. 3836636, Japanese Patent No. 3836866, Japanese Patent No. 4451392, and Japanese Patent No. 4852140.

<Partition members 5A and 5B>

The partitioning member 5A (first partitioning member) is a plate-like member perpendicular to the conveying path and fixed to the top plate 11 downward at a position on the upstream side along the conveying direction with respect to the four inductively-coupled antennas 41 Respectively. The partitioning member 5B (second partitioning member) is a plate-like member perpendicular to the conveying path and is fixed downward relative to the top plate 11 at a downstream position along the conveying direction than the four inductively coupled antennas 41 Respectively.

The X direction width of the partition members 5A and 5B is longer than the X direction width in which the four inductively coupled type antennas 41 are disposed and the Z direction width of the partition members 5A and 5B is four inductively coupled type antennas Is longer than the width in the Z direction in which the first electrode 41 is disposed. Since the four inductively coupled antennas 41 are sandwiched by the two partition members 5A and 5B each having a larger occupied area than the four inductively coupled antennas 41 in the XZ plane, The width of the processing space V in which the processing is performed in the carrying direction (Y direction) is a section between the partitioning member 5A and the partitioning member 5B.

&Lt; Gas supply units 6A to 6C >

The gas supply unit 6A (first gas supply unit) includes a supply source 611 for the first material gas and a plurality of discharge openings 611, one end of which is connected to the supply source 611 and the other end opens toward the upstream side in the transport direction, And a pipe 612 connected to the pipe 615. Further, a valve 613 is interposed in the middle of the path of the pipe 612 (Fig. 1). The valve 613 is preferably a valve capable of automatically regulating the flow rate of the gas flowing through the pipe 612. Specifically, it is preferable that the valve 613 is configured to include, for example, a mass flow controller.

In this configuration, when the valve 613 is opened, the first material gas supplied from the supply source 611 is discharged to the upstream side of the processing space V in the transport direction with respect to the plurality of discharge ports 615. As the first material gas, for example, a mixed gas obtained by mixing silane (SiH4) gas and ammonia (NH3) gas in the first material composition may be used.

The gas supply section 6B (the second gas supply section) includes a supply source 621 for the second material gas and a plurality of discharge ports 621, 622, 623, And a pipe 622 connected to the pipe 625. Further, a valve 623 is interposed in the middle of the path of the pipe 622 (Fig. 1). The valve 623 is preferably a valve capable of automatically regulating the flow rate of the gas flowing through the pipe 622. Specifically, it is preferable that the valve 623 is configured to include, for example, a mass flow controller.

In this configuration, when the valve 623 is opened, the second material gas supplied from the supply source 621 is discharged to the downstream side of the processing space V in the transport direction with respect to the plurality of discharge ports 625. As the second material gas, for example, a mixed gas obtained by mixing silane gas and ammonia gas in a second material composition having a different ratio from the first material composition may be used. Hereinafter, the case where the first material composition has a higher content of silane gas and a lower content of ammonia gas than the second material composition will be described.

3, a plurality of discharge ports 615 (four in this embodiment) in the gas supply portion 6A and a plurality of discharge ports 625 in the gas supply portion 6B (Four in this embodiment) are arranged so as to sandwich a plurality of inductively coupled antennas 41 (four in this embodiment) along the Y direction.

The gas supply unit 6C includes a supply source 631 for supplying inert gas (nitrogen gas in this embodiment), one end connected to the supply source 631 and the other end connected to a plurality of inductively coupled antennas 41 in the processing space V, And a pipe 632 connected to a plurality of discharge members 635 located above the discharge pipe 635. [ Further, a valve 633 is interposed in the middle of the path of the pipe 632 (Fig. 2). The valve 633 is preferably a valve capable of automatically regulating the flow rate of the gas flowing through the pipe 632. Specifically, it is preferable that the valve 633 includes, for example, a mass flow controller.

A plurality of discharge members 635 are arranged in a line at intervals and fixed to the lower surface 111 of the top plate 11 of the processing chamber 1. [ Concretely, for example, the plurality of discharge members 635 are arranged in a position corresponding to the inductively coupled type antenna 41 (for example, a virtual axis K, a U- (I.e., the center point C)) at both ends of the top plate 41, and is hermetically mounted to the top plate 11. [ It is considered that the protruding dimension of each of the discharge members 635 from the lower surface 111 is sufficiently smaller than the protruding dimension of the inductively coupled type antenna 41 from the lower surface 111.

In this configuration, when the valve 633 is opened, the nitrogen gas supplied from the supply source 631 is discharged from each of the discharge members 635 toward the respective inductively coupled type antennas 41. As a result, since the atmosphere around each inductively coupled antenna 41 is filled with the nitrogen gas, even if the plasma CVD process described later is performed in the process space V, the CVD film is formed on each inductively coupled antenna 41 Can be prevented.

As described in the embodiment, in the present embodiment, the mixed gas of the silane gas and the ammonia gas is supplied from the gas supply unit 6A and the gas supply unit 6B, and the nitrogen gas is supplied from the gas supply unit 6C. The type of the gas to be discharged from each of the supply portions 6A to 6C at what flow rate is determined by the kind of the thin film to be formed on the substrate 9 and the processing conditions such as the temperature, ) And the like. Each of the valves 613, 623, and 633 is electrically connected to the control unit 8. [ This allows the operator to control the respective components based on the values specified by the operator or the like so that the desired kind of gas is supplied from the discharge port 615, the discharge port 625, and the discharge member 635 desired by the operator, The operator is introduced into the processing space V at a desired flow rate.

&Lt; Exhaust part 7 >

The exhaust part 7 is a high vacuum exhaust system and is specifically provided with, for example, a vacuum pump 71, an exhaust pipe 72, and an exhaust valve 73. One end of the exhaust pipe 72 is connected to the vacuum pump 71 and the other end is connected to the processing space V in a communicative manner. The exhaust valve 73 is provided in the middle of the path of the exhaust pipe 72. Specifically, the exhaust valve 73 includes, for example, a mass flow controller, and is a valve capable of automatically regulating the flow rate of gas flowing through the exhaust pipe 72. In this configuration, when the exhaust valve 73 is opened while the vacuum pump 71 is operated, the processing space V is exhausted.

&Lt; Control unit (8) >

The control unit 8 is electrically connected to the respective constituent elements of the plasma CVD apparatus 100 (shown schematically in FIG. 1), and controls these elements. Specifically, for example, the control unit 8 is constituted by a CPU for executing various arithmetic processing, a ROM for storing programs and the like, a RAM serving as a work area for arithmetic processing, a hard disk for storing programs and various data files, And a data communication unit having a data communication function through a LAN or the like are connected to each other by a bus line or the like. The control unit 8 is connected to an input unit including a display for performing various displays, a keyboard, a mouse, and the like. In the plasma CVD apparatus 100, processing specified for the substrate 9 is performed under the control of the control section 8.

<Flow of 2 Processing>

Next, the flow of processing executed in the plasma CVD apparatus 100 will be described with reference to Fig. The processing described below is executed under the control of the control unit 8. [

When the carrier 90 on which the substrate 9 is placed is brought into the processing chamber 1 through the take-out inlet of the processing chamber 1, the holding and conveying portion 2 holds the carrier 90. The exhaust part 7 exhausts the gas in the processing chamber 1 to bring the processing chamber 1 into a vacuum state. At the predetermined timing, the holding and conveying section 2 starts to convey the carrier 90 (conveying step), and the heating section 3 starts heating the substrate 9 placed on the carrier 90.

When the interior of the processing chamber 1 is evacuated, the gas supply unit 6A starts supplying the first material gas to the upstream side (-Y side) in the transport direction of the processing space V with respect to the discharge port 615 The gas supply unit 6B starts supply of the second material gas to the downstream side (+ Y side) of the processing space V in the transport direction of the processing space V (the first gas supply step) fair). Thus, in the interior of the processing space V, a continuously changing atmosphere is formed from the upstream side to the downstream side, from the space filled with the first material gas to the space filled with the second material gas.

The gas supply unit 6C supplies the inert gas from the discharge member 635 toward each of the inductively coupled type antennas 41. [ Thereby, the ambient atmosphere of each inductively coupled antenna 41 in the processing space V is filled with the inert gas.

At the same time when such gas supply is started, a high-frequency current (specifically, a high-frequency current of, for example, 13.56 MHz) flows from the high-frequency power supply 44 to each of the inductively coupled type antennas 41. Then, electrons are accelerated by the high frequency induction electric field around the inductively coupled antenna 41, and inductively coupled plasma is generated. When the plasma is generated, the first material gas and the second material gas (mixed gas of the silane gas and the ammonia gas in the present embodiment) are decomposed by the plasma in the processing space V, (Plasma processing step).

Thus, the substrate 9 on which the CVD film (silicon nitride film in this embodiment) is formed on the main surface can be used for various electronic devices such as solar cells as the structure 10 (Fig. 4) for an electronic device. In this embodiment, since the ambient atmosphere of each inductively coupled antenna 41 is filled with the inert gas supplied from the gas supply unit 6C, the CVD film is not formed on the surface of each inductively coupled antenna 41 , It is possible to prevent degradation of the antenna performance due to the formation of the CVD film on the surface of each inductively coupled antenna 41. [

&Lt; 3 Structure (10) >

4 (a) is a side view showing the structure 10 produced by the plasma CVD apparatus 100 of the present embodiment. 4B is a diagram showing the relationship between the distance from the main surface S1 in the normal direction (Z direction) and the refractive index with respect to the CVD film 110 of the structure 10.

A continuously changing atmosphere is formed from the space filled with the first material gas to the space filled with the second material gas from the upstream side to the downstream side inside the processing space V as the technique described above, A plasma CVD process is carried out while conveying a position opposed to the process space V.

The composition of the CVD film 110 formed on the main surface of the substrate 9 becomes a composition which continuously changes from the first material composition to the second material composition in the normal direction away from the main surface.

In the present embodiment, the first material composition has a higher content of silane gas and a lower content of ammonia gas than the second material composition. The main surface S1 side of the substrate 9 with respect to the normal line direction is positioned on the side of the substrate 9 in the normal direction with respect to the normal direction, The refractive index becomes higher than the side opposite to the main surface S1 (Fig. 4 (b)). More specifically, the CVD film 110 obtained in the present embodiment has a point P1 (refractive index of 2.5) in the normal direction away from the main surface S1 of the substrate 9 and has a first refractive index A first section D1 and a second section D1 having a first section D1 and a second section D2 having a relatively low refractive index and a point P3 (refractive index 2.3) having a point P2 and a refractive index of 1.8, And a third section D3 having a refractive index corresponding to the middle of D2.

As described above, in the present embodiment, the CVD film 110 formed on the main surface S1 of the substrate 9 has a structure in which the material composition continuously changes in the normal direction away from the main surface, CVD film or a CVD film in which an interface of a material composition and a material composition different from that of the material composition is not present (the change in material composition is not continuous).

Hereinafter, an example of the effect of the structure 10 of the present embodiment will be described taking the reflectance of the structure 10 when light is irradiated from the outside as an example.

5 shows a structure 10 of the present embodiment, a substrate on which a single-layer CVD film is formed on the surface (hereinafter referred to as a structure 10Y), and a substrate on which two CVD films having different refractive indices are formed on the surface (Hereinafter referred to as &quot; structure 10Z &quot;) in which the CVD film is irradiated with light from the outside of each structure. The calculation of the spectral reflectance shown in Fig. 5 is performed in the structures 10, 10Y and 10Z in such a manner that the CVD film formed on each main surface is a silicon nitride film of the same thickness, and the refractive index of the CVD film It is presupposed that the integral values in the thickness direction are the same.

As shown in FIG. 5, the structure 10 of the present embodiment has a lower reflectance than the structure 10Z having a two-layer CVD film at a wavelength range of 250 nm (nanometer, the same applies below) to 1050 nm. This is due to the absence of an interface of different material compositions in the CVD film 110 as a composition in which the composition of the CVD film 110 continuously changes from a first material composition to a second material composition. That is, when light of a wavelength range of 250 nm to 1050 nm is irradiated from the outside of the structure, part of the light is reflected at the interface of the two-layer CVD film having different refractive indexes in the structure 10Z. In the structure 10, The reflectance of the light decreases because there is no reflection of light due to the presence.

As described above, the structure 10 of the present embodiment is superior in reflectance to light from the outside in comparison with the structure 10Z (more generally, a structure in which a CVD film is formed in multiple layers) on which a CVD film of two layers is formed on the substrate 9 Is low, and a low reflectance such as a solar cell is an advantage.

In addition, as shown in Fig. 5, the structure 10 of the present embodiment has a lower reflectance than the structure 10Y having a monolayer CVD film in a wavelength range of 300 nm to 700 nm. This is considered to be due to the existence of a difference in refractive index in the CVD film 110. In this type of thin film, internal reflection occurs in the film other than the surface of the thin film or reflection at the interface between the film and the film. However, since there is a difference in refractive index in the film, a phase difference is generated in each reflection light in the film, It is known that the reflection is reduced. That is, when light of a wavelength range of 300 nm to 700 nm is irradiated from the outside of the structure, the action of reducing the internal reflection of light does not occur in the structure 10 Y. However, in the structure 10, The reflectance of the light decreases as the internal reflection of light is reduced. In the wavelength range of 250 nm to 300 nm and 700 nm to 1050 nm, the structure 10Y having a single-layer CVD film than the structure 10 of the present embodiment has a low reflectance. The reason for this point is not clarified.

As described above, the structure 10 of the present embodiment has an advantage in that the reflectance for light in a wavelength range of 300 nm to 700 nm is lower than that of the single-layer structure 10Y, and the reflectance is low in the wavelength range as in a solar cell Lt; / RTI &gt; devices.

The plasma CVD apparatus 100 according to the present embodiment is a plasma CVD apparatus 100 according to the present embodiment in which an atmosphere changing continuously from the upstream side to the downstream side in the processing space V is formed in one processing space V It is possible to form the CVD film 110 on the substrate 9 by means of the inductively coupled antenna 41). Therefore, in the plasma CVD apparatus 100 of the present embodiment, it is necessary to form a plurality of processing spaces V along the carrying direction of the substrate 9, as in the case of forming a plurality of CVD films on the substrate 9 So that space saving and energy saving can be realized.

<Four Modifications>

The embodiments of the present invention have been described above. However, the present invention can make various modifications other than the above-described ones as long as it does not deviate from the purpose.

In the above embodiment, the process chamber V is formed only in the process chamber 1. However, the present invention is not limited to this, and a plurality of process spaces V may be formed in the process chamber 1 Or the like. Also in this case, when gas having different material compositions is supplied to the upstream side and the downstream side in at least one of the processing spaces V among the plurality of processing spaces V, The CVD film 110 in which the material composition is continuously changed along the normal direction on the main surface S1 of the substrate 100 can be formed.

In the above-described embodiment, the first kind of material gas and the second type material gas contain a plurality of kinds of composition elements (silane and ammonia) which are common to each other. On the other hand, But the present invention is not limited thereto.

For example, when the composition element contained in the first material gas is silane and nitrogen monoxide, and the composition element contained in the second material gas is silane and ammonia, The constituent elements included in the material gas may be different from each other. In this case, the material composition of the CVD film formed on the main surface S1 of the substrate 9 continuously changes from the silicon oxide film to the silicon nitride film in the normal direction away from the main surface S1.

In the above embodiment, a CVD film is formed on the inductively coupled antenna 41 by discharging an inert gas (nitrogen gas) from the discharge member 635 and filling the ambient atmosphere of the inductively coupled antenna 41 with an inert gas However, the present invention is not limited thereto. The gas discharged from the discharge member 635 may be a material gas in the plasma CVD process or an additive gas. It is also possible that the discharge member 635 does not discharge the gas.

4 (b), the first section D1 having a relatively high refractive index and the second section D1 having a relatively large refractive index in the normal direction away from the main surface S1 of the substrate 9 The CVD film 110 has a low second section D1 and a third section D3 having a refractive index intermediate between the first section D1 and the second section D2. But is not limited thereto.

Even when the plasma CVD process is performed in a state where the material composition to be formed with the first material gas is higher than the material composition to be formed with the second material gas, as in the above embodiment, the temperature, pressure, 6, by adjusting various conditions such as the width of the space V (the space between the partitioning members 5A and 5B), the output from the inductively coupled antenna 41, and the supply amount of the material gas, A CVD film having no section corresponding to the second section D2 may be formed.

Although the structure for an electronic device, the plasma CVD apparatus, and the film forming method according to the embodiment and its modified examples have been described above, they are examples of preferred embodiments of the present invention and do not limit the scope of the present invention. The present invention can be freely combined with each embodiment, or a modification of any component of each embodiment within the scope of the invention, or omit any component in each embodiment.

1 processing chamber
2 maintenance conveying section
3 heating section
4 plasma generator
5A, 5B partition members
6A to 6C gas supply unit
7 times donation
8 control unit
9 substrate
41 Inductive Coupling Antenna
44 High frequency power
90 carrier
100 plasma processing apparatus

Claims (12)

delete delete delete delete delete A chamber,
A holding and conveying unit that holds the substrate to be processed and relatively conveys the substrate along the conveying path,
A plurality of inductively coupled antennas arranged in a processing space defined in the chamber opposite to the conveying path and each having a number of turns of less than one week;
A first gas supply part for supplying a first material gas to an upstream part of the processing space along the conveyance path,
And a second gas supply part for supplying a second material gas having a composition different from that of the first material gas to a downstream part of the processing space along the transfer path,
Wherein the first gas supply unit supplies the first material gas, the second gas supply unit supplies the second material gas, and the high-frequency power is supplied to the plurality of inductively coupled antennas to generate plasma, And the substrate is transported along the transport path by the holding and transporting unit,
Wherein a composition of the first material corresponding to the first material gas and a composition of the second material corresponding to the second material gas are continuously changed with respect to a normal direction away from the main surface, Wherein a film is formed. The method of claim 6,
A first partitioning member disposed on an upstream side of the plurality of inductively coupled antennas along the conveying path to a plate member perpendicular to the conveying path,
And a second partitioning member disposed on a downstream side of the plurality of inductively coupled antennas along the conveying path with a plate member perpendicular to the conveying path,
And the width of the processing space in the transport direction is defined by the first and second partition members. The method of claim 6,
Wherein the first material gas and the second material gas each have a plurality of kinds of composition elements that are common to each other and a composition ratio of the plurality of composition elements that are different from each other. The method of claim 6,
Wherein a composition element included in the first material gas and a composition element included in the second material gas are different from each other. The method according to any one of claims 6 to 9,
Wherein the substrate is a semiconductor substrate for a solar cell,
Wherein the CVD film is a protective film of the solar cell. The method of claim 10,
Wherein at least one of the first material gas and the second material gas contains silane and ammonia,
Wherein the CVD film comprises a silicon nitride film. A method for forming a CVD film on a main surface of a substrate carried along a transport path by performing a plasma process in a process space in which a plurality of inductively coupled antennas each having a number of turns of less than one week are disposed,
A first gas supply step of supplying a first material gas to an upstream part of the processing space along the transport path,
A second gas supply step of supplying a second material gas having a composition different from that of the first material gas to a downstream portion of the processing space along the transfer path,
A plasma processing step of generating plasma by supplying a high frequency power to the plurality of inductively coupled antennas and performing chemical vapor deposition on the substrate by plasma decomposition of the first and second material gases;
And a transporting step of transporting the substrate along the transport path,
Wherein a composition is continuously changed from a first material composition corresponding to the first material gas to a second material composition corresponding to the second material gas with respect to a normal direction away from the main surface on the main surface of the substrate Wherein a CVD film is formed.

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