JPH07106614A - Production of semiconductor element - Google Patents

Abstract

PURPOSE:To provide a transparent conductive film and semiconductor element having enhanced adhesion and environmental resistance. CONSTITUTION:A first transparent conductive film of ITO crystal having average grain size of 0.025mum or above and a second transparent conductive film of ITO crystal having grain size of 0.025mum or less are formed sequentially on a transparent substrate 1 by a thin film deposition means. A semiconductor film 4 is then formed thereon by means of plasma containing reductive active species thus producing a semiconductor element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent conductive film and a semiconductor element formed by forming a semiconductor film on the transparent conductive film, and more particularly to a transparent conductive film formed on a transparent substrate, which further has a semiconductor film formed thereon. The present invention relates to a method of manufacturing a semiconductor element formed by stacking.

[0002]

2. Description of the Related Art In a semiconductor element formed on a transparent substrate such as a liquid crystal display panel, an EL display panel, a contact type image sensor, and an electrophotographic photosensitive member, the transparent substrate has conductivity such as glass or resin film. Often, non-use materials are used, but in most cases, the substrate is required to have conductivity as well as transparency. In that case, a transparent conductive film is generally formed on the substrate by means of a thin film forming means in order to have conductivity while maintaining transparency on the surface of the transparent substrate on which the semiconductor film is formed. Such a transparent conductive film is usually ITO (indium tin oxide) or In ₂ O ₃
(Indium oxide), SnO ₂ (tin dioxide), etc. are used.

[0003]

ITO, which is widely used as a transparent conductive film, can be formed on a large area by a thin film forming method such as a sputtering method, an ion plating method, or an active reaction vapor deposition method. Although it has excellent properties such as good patternability by etching, on the other hand, when a semiconductor film is laminated on the film by a plasma CVD method, it is easily damaged by plasma and the film surface There is also a problem that the transparency is likely to be deteriorated due to the roughness and discoloration.

If the plasma for forming the semiconductor film contains reducing active species such as hydrogen radicals, I
There is also a problem that the adhesion between the TO film and the substrate is lowered, and after the semiconductor films are laminated, the stress of the semiconductor film causes the peeling of the ITO film. The occurrence of such peeling is
The reliability of the product is high because peeling pieces may scatter during the formation of the semiconductor film, which may cause defects in the product in which the semiconductor film is formed and peeling may occur during use of the product. It becomes a serious problem for.

As a measure against peeling of the transparent conductive film as described above, Japanese Patent Laid-Open No. 2-109294 discloses that a glass substrate on which a transparent electrode is formed is provided with irregularities of a size comparable to half the film thickness of the transparent electrode. However, it has been technically and costly difficult to uniformly perform such fine processing on a large-area substrate, and there is a problem that plasma is easily damaged. .

Further, Japanese Patent Laid-Open No. 2-1519 discloses that the degree of orientation of the (222) plane of the transparent conductive layer containing indium oxide as a main component is set to 50% or more. This is a Schottky barrier. This is to improve the bonding characteristics of the structure, the problems of peeling and damage described above have not been improved, and it is technically impossible to uniformly control the degree of orientation of a specific crystal plane on a large-area substrate. It was difficult. Furthermore, as a measure to reduce the damage caused by the plasma on the ITO film surface,
Although it has been practiced to thinly deposit SnO ₂ which is resistant to plasma damage on the ITO film, it is necessary to stack two kinds of films made of different materials in this way to form a transparent conductive film forming device. with the production resulted in complication of or disadvantaged, there is also a problem that two types of film interface in the light transmittance of the entire transparent conductive film or resulting reflection of light is reduced, by addition SnO ₂ by etching Workability is I
Since it is inferior to TO, it was also disadvantageous in pattern formation.

Further, in JP-A-3-261005, a transparent conductive film having a two-layer film structure in which a low-resistance second ITO film is laminated on the surface of a high-resistance first ITO film can be formed by a sputtering method. Although disclosed, this is to obtain a transparent conductive film having low resistance and improved etching characteristics at the time of patterning, and the problems of peeling and damage have not been similarly improved.

Further, since the stress of the semiconductor film can be relieved and the film peeling can be suppressed by providing irregularities on the surface of the ITO transparent conductive film, the present inventor has disclosed the average crystal grain size in Japanese Patent Application No. 5-161270. A specified ITO transparent conductive film was proposed. However, it was found that if the irregularities formed on the surface of the transparent conductive film were too large, the environment resistance of this transparent conductive film would deteriorate, and the inventors of the present invention continued diligent research to improve this point. I've been

The present invention is a method for producing a transparent conductive film and a semiconductor element, which has been made to solve the above-mentioned problems by improving a transparent conductive film. The improvement of the transparent conductive film causes technical difficulties and film formation. A transparent conductive film that suppresses the deterioration of the transparency due to the surface roughness and discoloration of the transparent conductive film and the peeling of the transparent conductive film after the semiconductor films are laminated without further increasing the cost, and further improves the environmental resistance. An object is to provide a film and a semiconductor device.

[0010]

A method of manufacturing a semiconductor device according to the present invention comprises a first step of forming an ITO crystal having an average crystal grain size of 0.025 μm or more on a transparent substrate by a thin film forming means.
And a second transparent conductive film having ITO crystals having an average crystal grain size of less than 0.025 μm are sequentially formed, and a plasma containing a reducing active species is formed on the second transparent conductive film. It is characterized in that a semiconductor film is formed.

[0011]

Operation: I formed on the transparent substrate by the thin film forming means
When another type of semiconductor film is formed on the TO transparent conductive film using plasma containing a reducing active species such as hydrogen radicals, stress is generated in the another type of semiconductor film and between the other type of semiconductor film and the ITO film. . When the stress becomes stronger than the adhesion between the ITO film and the transparent substrate, the ITO film is peeled off. FIG. 1 is a sectional view showing the layer structure of a semiconductor element manufactured by the manufacturing method of the present invention in order to suppress the occurrence of such peeling and further improve the environment resistance. According to the figure, the first transparent conductive film 2 and the second transparent conductive film 3 are sequentially laminated on the transparent substrate 1, and the semiconductor film 4 is further formed thereon. .

As the transparent substrate 1 used for such a semiconductor device, glass such as Pyrex glass, soda glass, borosilicate glass, transparent inorganic materials such as quartz and sapphire, and fluororesin, polyester, polycarbonate, polyethylene. Examples thereof include transparent organic resin materials such as terephthalate, vinylon, epoxy, mylar, etc., and they are used in a flat plate shape, a sheet shape, a drum shape or a belt shape.

The materials for the first transparent conductive film 2 and the second transparent conductive film 3 include ITO, SnO ₂ , In ₂ O ₃ , lead oxide (ZnO), and copper iodide (CuI). ), Copper sulfide (CuS), InOF, Cd ₂ Sn
O ₄ etc. can be used. The thin film forming means for forming these transparent conductive films include ion plating method, active reaction vapor deposition method, vacuum vapor deposition method, RF sputtering method, DC sputtering method, RF magnetron sputtering method, DC magnetron sputtering method, and thermal CV.
D method, plasma CVD method, catalytic CVD method, spray method,
There are a coating method and a dipping method.

Here, the first ITO is first formed on the transparent substrate 1.
When the transparent conductive film 2 is formed, its forming conditions are controlled, and for example, the ITO film is formed at a slow film forming speed to strengthen the orientation of the ITO crystals in the transparent conductive film 2 in a specific direction. When manufactured in this manner, the average grain size of the ITO crystals having the orientation in the specific direction increases, and
Irregularities are formed on the surface of the O film. By providing irregularities on the surface of the ITO transparent conductive film 2 in this manner, stress in the different semiconductor film and between the different semiconductor film and the transparent conductive film when the different semiconductor film is formed on the transparent conductive film is relaxed. Therefore, peeling of the transparent conductive film can be suppressed.

According to the knowledge obtained by the present inventor, the size of the unevenness provided on the surface of the first transparent conductive film 2 in order to suppress the peeling depends on the average crystal grain size of ITO in the film. When expressed, good results were obtained by setting the thickness to 0.025 μm or more.

Then, a second film is formed on the first transparent conductive film 2.
Transparent conductive film 3 is formed. When the second transparent conductive film 3 is formed, if the conditions for forming the second transparent conductive film 3 are controlled and the second transparent conductive film 3 is formed at a higher film forming speed than that of the first transparent conductive film 2, the average crystal grain size of ITO is increased. Therefore, a transparent conductive film having a small surface roughness is formed. However, since the unevenness of the surface of the transparent conductive film after the second transparent conductive film 3 is laminated reflects the size of the unevenness of the first transparent conductive film 2, the large unevenness is maintained, The effect of suppressing peeling is maintained. On the other hand, since the irregularities and the average crystal grain size of the second transparent conductive film 3 itself are small, the ITO having the excellent environmental resistance and the improved stability of the characteristics is thereby obtained.
It becomes a transparent conductive film.

According to the knowledge obtained by the inventor of the present invention, the surface of the second transparent conductive film 3 provided in order to improve the environment resistance and the stability of the characteristics while maintaining the effect of suppressing the peeling. Good results were obtained by setting the size of the irregularities to less than 0.025 μm when expressed by the average crystal grain size of ITO in the film.

Thus, the average crystal grain size is 0.025 μm.
By the above, the stability of the characteristics is improved, but as the lower limit of the variation of the crystal grain size at that time, if the grain size is too small, the formation of surface irregularities becomes insufficient and the stress cannot be completely absorbed. Since peeling occurs, 0.012 μm or more is desirable. On the other hand, the upper limit of the crystal grain size is preferably 0.05 μm or less because the electrical conductivity decreases as the crystal grain size increases, and the fluctuation of the characteristics with respect to environmental changes increases.

The thickness of the first transparent conductive film is 250.
Å or more, and more preferably 250 to 2000Å. Within this range, the crystal grain size of ITO can be grown to 0.025 μm or more, which is necessary to relieve the stress between the transparent conductive film and the semiconductor film, and the adhesion can be most significantly improved. it can. However, if it exceeds 2000 Å, the resistance or the light transmittance may change greatly due to the environment such as temperature and humidity, and the resistance of the entire transparent conductive film in which this film and the second transparent conductive film are laminated is increased. Although environmental properties may not be sufficiently enhanced, this upper limit is not critical and is appropriately set in consideration of desired properties. The thickness of the second transparent conductive film is 50.
It is desirable to set it in the range of 0Å, more preferably in the range of 500 to 2000Å. Within this range, the resistivity becomes low and good conductivity is easily obtained. If it exceeds 2000 Å, the film thickness of the entire transparent conductive film tends to increase and the light transmittance tends to decrease. However, this upper limit is not critical and is appropriately set in consideration of desired characteristics.

The action of stress relaxation and environmental resistance improvement by the combination of the two kinds of films having different average crystal grain sizes as described above is as follows.
Not limited to the case of ITO transparent conductive film, SnO ₂ or In ₂ O
It is considered that the invention can be similarly applied to the case where another kind of semiconductor film is laminated on another transparent conductive film such as ₃ or other polycrystalline film.

The application of the semiconductor device having the structure of the present invention is, for example, an electrophotographic photosensitive member, a solar cell, or TF.
There are various thin film devices such as T (thin film transistor), optical sensor, reading sensor, and photodiode.

[0022]

EXAMPLES Examples will be specifically described below. Example 1 FIG. 2 shows a schematic configuration diagram of an ion plating device 5 used for forming the ITO transparent conductive film of the present invention.
The ion plating device 5 includes a main body 6a and a bottom body 6 thereof.
In a vacuum container 6 consisting of b, an evaporation source 7 as an ion supply source for film formation, a high-frequency coil 8 for generating a reactive plasma, a substrate support 9 also serving as a cathode base, and a substrate heating comprising a halogen heater or the like. A heater 10 for heating and a shutter 11 for controlling the start and end of film formation are arranged. An evaporation source power source 12 is provided for the evaporation source 7, a high frequency power source 13 is provided for the high frequency coil 8, and a substrate support 9 is provided. Are connected to DC power supplies 14, respectively. Further, in the main body 6a of the vacuum container, a reaction gas introduction port 17 via a valve 15 and a gas flow rate regulator 16 and a gas exhaust port connected to a vacuum exhaust unit (not shown) such as an ion pump or an oil diffusion pump. And 18 are provided. The arrows in the figure represent the flow of gas.

With this ion plating device 5, I
In order to perform TO film formation, first, the film formation transparent substrate 19 is mounted on the substrate support 9, the inside of the vacuum container 6 is evacuated to a vacuum degree of about 10 ⁻⁶ Torr, and the heater 10 is used. The base 19 is heated to a predetermined film forming temperature by. Next, the valve 15 is opened, and a reaction gas composed of a mixed gas of argon (Ar) and oxygen (O ₂ ) or the like is set to a predetermined flow rate by the flow rate controller 16 and introduced into the container 6 through the gas introduction port 17. , The inside of the container 6 is set to a predetermined pressure. Next, the evaporation source power supply 12 is turned on, an electron beam current is passed through the evaporation source 7 to apply power, and a film forming material composed of an oxide of indium (In) and tin (Sn) is applied from the evaporation source 7. While evaporating, a high frequency power is applied to the coil 8 from the high frequency power supply 13 to generate reactive plasma, and a negative voltage is applied to the substrate support 9 by the DC power supply 14,
Adjust film formation conditions to stabilize. After that, shutter 1
By opening 1, the film forming material from the evaporation source 7 passes through the reactive plasma and reaches the substrate 19 to form an ITO film. Then, when the desired film thickness is obtained, the shutter 11 is closed again to complete the film formation.

Using the ion plating device 5 described above, a Pyrex glass tube having an outer diameter of 30 mm and a length of 260 mm was used as a transparent substrate, and the first and second Pyrex glass tubes having different average crystal grain sizes were used under the conditions shown in Table 1. An ITO transparent conductive film was formed. The average crystal grain size was changed by changing the film formation rate, and the film formation rate was controlled by adjusting the electric power applied to the evaporation source according to the magnitude of the electron beam current and changing the evaporation amount. The amount of evaporation was confirmed by monitoring the pressure rise value in the vacuum container 6 before and after the evaporation source was evaporated with a vacuum gauge.

[0025]

[Table 1]

The average crystal grain size of these first and second ITO transparent conductive films was determined by SEM (scanning electron microscope) photographs of the film surface. These SEM photographs were taken using a Hitachi S800 scanning electron microscope, and Pt-Pd on the sample surface.
After vapor deposition, an image was taken at a tilt angle of 0 degree and a magnification of 50,000 times. In each SEM photograph thus taken, 10 lines with a length of 50 mm were drawn, the number of crystal grains per line was counted, the average number of crystal grains per 50 mm was calculated, and the average crystal grain size was calculated from the average number. Was calculated and calculated.
Table 1 also shows the calculation results of these average crystal grain sizes. When the average crystal grain size of the first and second transparent conductive films was determined as described above, the electron beam current was 3.
First to reduce the film formation rate by reducing it to 0 A (ampere)
In the transparent conductive film of, the average number of crystal grains is 33.2, and the average crystal grain size is (50 mm / 33.2) ÷ 50,
000 = 3.010 × 10 ^-5 mm or 0.030μ
On the other hand, in the second transparent conductive film in which the electron beam current was increased to 6.0 A and the film formation rate was increased, the average number of crystal grains was 49.3.
The average crystal grain size is (50 mm / 49.3) ÷ 50,000
= 2.028 × 10 ⁻⁵ mm, that is, 0.020 μm. Therefore, it was confirmed that the average crystal grain size of each sample was changed by changing the evaporation rate according to the magnitude of the electron beam current and changing the film formation rate. It was also confirmed that the size of the irregularities formed on the film surface could be controlled thereby.

Next, an a-Si film was laminated by the plasma CVD method on the two-layered ITO transparent conductive film formed as described above. The plasma CVD film forming reaction furnace for forming the a-Si film used in this embodiment will be described with reference to FIG. FIG. 3 is a schematic configuration diagram of the plasma CVD film forming reaction furnace 20. Plasma CVD shown in FIG.
In the film forming reaction furnace 20, 21 is a cylindrical metal reaction furnace, 22 is a cylindrical conductive support on which a glass tube substrate 19 having an ITO film is mounted, and the substrate 19 is ITO.
A mask 23 for establishing electrical continuity between the film and the support 22 and providing a non-film-forming portion at the end of the base body 19, and the dummy ring 2
It is held by the support 22 by means of 4. Reference numeral 25 is a heater for heating the substrate, 26 is a cylindrical glow discharge electrode plate used for film formation of a-Si, and a large number of gas ejection ports 27 are formed in this electrode plate 26. And 28
Is a gas inlet for introducing gas into the reactor, 29
Is a gas outlet for exhausting the residual gas of the gas exposed to the glow discharge, and 30 is a high frequency power source for generating glow discharge between the conductive support 22 and the glow discharge electrode plate 26. . Here, the arrows in the figure represent the flow of gas. Further, the reaction furnace 20 includes a cylindrical body 21a and a lid body 2.
1b and a bottom body 21c, and an insulating ring 21d is provided between the cylinder body 21a and the lid body 21b, and between the cylinder body 21a and the bottom body 21c, respectively. One terminal of the power supply 30 is electrically connected to the glow discharge electrode plate 26 through the cylindrical body 21a, and the other terminal is electrically connected to the conductive support 22 through the lid 21b and the bottom body 21c and is grounded. ing. Also, the lid 2
The conductive support 22 is rotatably driven by the motor 31 attached above 1b via the rotary shaft 32, and the base 19 is also rotated accordingly.

When an a-Si film is formed using this plasma CVD film forming reaction furnace 20, the substrate 19 is used as the support 2.
The silane gas or disilane gas as a raw material gas for generating a-Si, or the diborane gas or phosphine gas or phosphine gas as an impurity gas added to adjust the characteristics of a-Si, methane gas, acetylene gas, ammonia gas, nitrogen gas. Further, a gas obtained by mixing hydrogen gas, helium gas, argon gas, etc. used as a diluting gas at a predetermined composition ratio is introduced into the reaction furnace through the gas inlet port 28, and this gas is introduced through the gas jet port 27. The base material 19 is jetted toward the surface of the base material 19, the base material 19 is set to a required temperature by the heater 25, and high frequency power is supplied from the high frequency power supply 30 to generate glow discharge between the support body 22 and the electrode plate 26. Then, the base 19 is further rotated to form an a-Si film on the peripheral surface of the base 19. Thus, during the glow discharge plasma for forming the a-Si film,
Hydrogen contained in the a-Si generating gas exists as hydrogen radicals that are reducing active species.

On the glass tube substrate on which the two-layered ITO transparent conductive film shown in Table 1 was formed, the a-Si film was laminated under the conditions shown in Table 2 using the plasma CVD film forming reaction furnace 20. A semiconductor device having the constitution of the present invention was produced.

[0030]

[Table 2]

Then, an environment resistance test was conducted on the two-layered ITO transparent conductive film and the semiconductor element obtained as described above. As the environment resistance test, heat resistance, alkali resistance, humidity resistance and hydrogen process resistance tests were conducted on the transparent conductive film, and an adhesion test was conducted on the semiconductor element. The characteristic measurement for pass / fail judgment is
Sheet resistance and wavelength of 550 to 790 for transparent conductive film
The light transmittance in nm and the change rate before and after the test were calculated and judged. Further, the adhesion to the semiconductor element was visually determined. Table 3 shows these test conditions and the criteria for determining excellent products.

[0032]

[Table 3]

As a result of these environment resistance tests, the transparent conductive film showed a change rate of sheet resistance of 5% in heat resistance.
Within, the rate of change in sheet resistance in alkali resistance (hereinafter abbreviated as resistance change rate) is 1.5%, the rate of resistance change in humidity resistance is 2%, the rate of resistance change in hydrogen plasma resistance is 1%, and the light transmittance. Is 90% and the change rate of light transmittance is 4
%, And no peeling of the film was observed in the adhesion test of the semiconductor element, and each showed excellent environment resistance.

[Example 2] In the same manner as in [Example 1], an outer diameter of 30
mm and length 260 mm, the first and second I are obtained by changing the average crystal grain size and thickness and changing the film formation rate.
Several kinds of TO transparent conductive films are formed and plasma C is formed on them.
The semiconductor elements A to W are formed by stacking a-Si films by the VD method.
Was produced. Further, as comparative examples, semiconductor elements X to Z in which a-Si films were laminated without forming the second transparent conductive film were also manufactured.

Tables 4 and 5 summarize the average crystal grain size and thickness of the transparent conductive films of these samples, and the results of the environmental resistance test conducted on each sample in the same manner as in [Example 1].
The results of the environmental resistance test in both tables include the change rate of resistance or light transmittance in each test of heat resistance, alkali resistance, moisture resistance and hydrogen process resistance for the transparent conductive film, and hydrogen plasma resistance test. Shows the light transmittance of the film and the rate of occurrence of film peeling in the adhesion test for semiconductor elements, and as a result of these judgments, the above-mentioned excellent product level is indicated by ○, and although slightly lower than that, it is a practical problem. △ is shown for a non-defective product level, and × is shown for a practically problematic level. In addition, * was additionally written in the sample number column for those outside the scope of the present invention.

[0036]

[Table 4]

[0037]

[Table 5]

As a result of these environmental resistance tests, the semiconductor elements E and J to W of the present invention were found to have heat resistance and alkali resistance in the transparent conductive film, a change rate of sheet resistance or light transmittance with respect to moisture resistance, and hydrogen resistance. Both the rate of change in resistance with respect to the plasma property and the rate of change in light transmittance were good, and no film peeling was observed in the adhesiveness in the semiconductor element, and each showed excellent environment resistance.

[0039]

As described above in detail, according to the present invention, I
A simple method of controlling the average particle size and the unevenness of the film surface by controlling the film forming conditions of the TO transparent conductive film, particularly the film forming speed, which brings about technical difficulties and an increase in the film forming cost. In addition, it was possible to provide a semiconductor element in which the deterioration of the transparency due to the roughness or discoloration of the surface of the transparent conductive film was suppressed.

Further, according to the present invention, it is possible to provide a semiconductor element in which the occurrence of peeling of the transparent conductive film and the semiconductor film after the semiconductor film is laminated on the transparent conductive film is suppressed and the adhesion is improved.

Further, according to the present invention, it is possible to provide a transparent conductive film having improved environmental resistance and a semiconductor element having a semiconductor film formed thereon, and various thin films such as electrophotographic photoreceptors and reading sensors. Now it can be applied to devices.

Since film peeling during the manufacture of semiconductor elements is eliminated, film formation defects are reduced, which improves the yield rate of elements and ensures high quality.
The element characteristics were stable, and it was possible to secure excellent stability as a thin film device product.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a layer structure of a semiconductor element manufactured by a manufacturing method of the present invention.

FIG. 2 is a schematic configuration diagram of an ion plating apparatus used in this example.

FIG. 3 is a schematic configuration diagram of a plasma CVD film forming reaction furnace used in this example.

[Explanation of symbols]

 1, 19 ... Transparent substrate 2 ... First transparent conductive film 3 ... Second transparent conductive film 4 ... Semiconductor film 5 ... Ion plating device 7 ... Evaporation source 8 ... High-frequency coil 13, 30 ... High-frequency power source 20 ... Plasma CVD film forming reactor 26 ... For glow discharge Electrode plate

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G02F 1/1343 H01L 29/786 21/336

Claims (1)

[Claims] 1. A first transparent conductive film having an ITO crystal having an average crystal grain size of 0.025 μm or more and a ITO crystal having an average crystal grain size of less than 0.025 μm on a transparent substrate by a thin film forming means. A method of manufacturing a semiconductor device, comprising: forming a second transparent conductive film sequentially and forming a semiconductor film on the second transparent conductive film by plasma containing reducing active species.