JPH0779003A - Manufacture of semiconductor element - Google Patents

Abstract

PURPOSE:To suppress the generation of peeling of a transparent conductive film by forming the transparent film having ITO crystals, an average crystal grain diameter exceeding a specified value, and further forming a semiconductor film by a plasma containing reducing active species on this transparent conductive film. CONSTITUTION:A transparent conductive film having an ITO crystal is formed by a thin film forming means on a transparent substrate so that an average crystal grain diameter will be over 0.025mum. On this ITO transparent conductive film, another type of semiconductor film is formed by using a plasma which contains reducing active species such as a hydrogen radical. As a result, ruggedness is produced on the ITO surface, and this ruggedness relaxes stress inside the other type of semiconductor film and between the other type of semiconductor film and the ITO film. This enables the peeling of the ITO film to be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor element in which a transparent conductive film and a semiconductor film are laminated on a transparent substrate.

[0002]

2. Description of the Related Art In a semiconductor device formed on a transparent substrate, such as a liquid crystal display panel, an EL display panel, a contact type image sensor, an electrophotographic photosensitive member, etc., 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. As such a transparent conductive film, ITO (indium tin oxide) or In is usually used.
₂ O ₃ (indium oxide), SnO ₂ (tin dioxide) and the like 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. , And has excellent workability such as patterning by etching, but 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 transparency is likely to decrease due to roughness and discoloration. Further, when the plasma for forming the semiconductor film contains a reducing active species such as hydrogen, the adhesion between the ITO film and the substrate decreases, and after the semiconductor films are stacked, the stress of the semiconductor film causes IT
There is also a problem that peeling of the O film occurs.

As a measure for peeling such a transparent conductive film,
Japanese Unexamined Patent Publication (Kokai) No. 2-109294 discloses that a glass substrate on which a transparent electrode is formed is provided with irregularities to the extent of half the film thickness of the transparent electrode. It is technically and costly to uniformly perform fine processing, and there remains a problem that plasma is easily damaged. In addition, JP-A-2-15
No. 19 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, which improves the bonding characteristics of the Schottky barrier structure. However, the problems of peeling and damage have not been improved, and it has been technically difficult to uniformly control the degree of orientation of a specific crystal plane on a large-area substrate. Further, as a measure for reducing plasma damage on the ITO film surface, a thin layer of SnO ₂ that is resistant to plasma damage has been thinly stacked on the ITO film. However, it is not possible to stack two types of films in this way. , The structure and conditions of the apparatus for forming the transparent conductive film are complicated, which is disadvantageous in manufacturing, and light is reflected at the interface between the two kinds of films, or the light transmittance of the entire transparent conductive film is reduced. There is also a problem, and in addition, since SnO ₂ is inferior to ITO in workability by etching, it is disadvantageous in pattern formation.

The present invention is a method for manufacturing a semiconductor device, which has been made to solve the above problems by improving a transparent conductive film. The present invention relates to technical difficulties and film formation by controlling the surface state of the transparent conductive film. An object of the present invention is to suppress 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 increasing the cost.

[0006]

According to the method of manufacturing a semiconductor element of the present invention, a transparent conductive film having ITO crystals having an average crystal grain size of 0.025 μm or more is formed on a transparent substrate by a thin film forming means. In addition, a semiconductor film is formed on the transparent conductive film by plasma containing reducing active species.

[0007]

Operation: I formed on the transparent substrate by the thin film forming means
When a different type of semiconductor film is formed on the TO transparent conductive film by using plasma containing a reducing active species such as hydrogen radicals, stress is generated in the different type of semiconductor film and between the different type of semiconductor film and the ITO film. To do. When the stress becomes stronger than the adhesion between the ITO film and the transparent substrate, the ITO film is peeled off.

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

In addition, as the material forming the transparent conductive film, ITO, SnO ₂ , In ₂ O ₃ , lead oxide (ZnO), copper iodide (CuI), copper sulfide (CuS),
InOF, Cd ₂ SnO ₄ , Au, etc. are available. And
The thin film forming means for forming these transparent conductive films includes
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, thermal CVD method, plasma CVD method, catalyst C
There are a VD method, a spray method, a coating method, a dipping method and the like.

Here, when forming, for example, an ITO transparent conductive film on a transparent substrate, the formation conditions are controlled so that the orientation of the ITO crystal in the transparent conductive film becomes strong in a specific direction. The average grain size of the ITO crystal having the orientation in the specific direction becomes large, and irregularities are formed on the surface of the ITO film. When such unevenness is formed, the stress in the different semiconductor film and between the different semiconductor film and the ITO film when the different semiconductor film is formed on the ITO film can be relieved, so that the peeling of the ITO film is suppressed. can do.

The effect of stress relaxation due to such unevenness is not limited to the case of the ITO transparent conductive film, but SnO ₂ and In
It is considered to be applicable to the case where another kind of semiconductor film is laminated on another transparent conductive film such as ₂ O ₃ or another polycrystalline film.

[0012]

EXAMPLES Examples will be specifically described below. Example 1 FIG. 2 shows a schematic configuration diagram of the ion plating apparatus 1 used for forming the ITO film. The ion plating apparatus 1 also serves as an evaporation source 3 as a film forming ion supply source, a high frequency coil 4 for generating a reactive plasma, and a cathode base in a vacuum container 2 composed of a main body 2a and a bottom body 2b thereof. A substrate support 5, a substrate heating heater 6 including a halogen heater, and a shutter 7 for controlling the start and end of film formation are arranged. The evaporation source 3 includes an evaporation source power source 8 and a high-frequency coil. A high frequency power source 9 is connected to the base 4, and a direct current power source 10 is connected to the base support 5. Further, in the main body 2a of the vacuum container, a reaction gas introduction port 13 via a valve 11 and a gas flow rate controller 12, and a gas exhaust port connected to a vacuum exhaust unit (not shown) such as an ion pump or an oil diffusion pump. And 14 are provided. The arrows in the figure represent the flow of gas.

With this ion plating apparatus 1, I
In order to perform TO film formation, first, the film formation substrate 15 is mounted on the substrate support 5 and the inside of the vacuum container 2 is evacuated to 10
^The substrate 6 is evacuated to a vacuum degree of about ^-6 Torr and the substrate 15 is heated to a predetermined film forming temperature by the heater 6. Next, the valve 11 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 12 and introduced into the container 2 through the gas introduction port 13. The inside of the container 2 is set to a predetermined pressure. Next, the evaporation source power source 8 is turned on to evaporate the film forming material composed of oxides of indium (In) and tin (Sn) from the evaporation source 3 and apply a high frequency to the coil 4 from the high frequency power source 9. Reactive plasma is generated, and a negative voltage is applied to the substrate support 5 by the DC power source 10 to adjust and stabilize the film forming conditions. After that, by opening the shutter 7, the film forming material from the evaporation source 3 passes through the reactive plasma and reaches the substrate 15, and the ITO film is formed. Then, when the desired film thickness is obtained, the shutter 7 is pressed again.
Is closed to complete the film formation.

Using the above-mentioned ion plating apparatus 1, two kinds of ITO films having different film forming rates were formed under the following conditions. As a condition common to both, the outer diameter of the base is 30 m
m, glass tube of 260 mm in length, film formation temperature is 25
It was set to 0 ° C. Ar 5 sccm and O _{2 as} reactive gas
The mixed gas of 15 sccm was used, and the high frequency power applied to the coil 4 was 200 W. Further, tin oxide (Sn
O ₂₎ 5 wt% added indium oxide (In
_The deposition rate was controlled by adjusting the electric power applied to the evaporation source and changing the evaporation amount using a metal oxide target composed of ₂ O ₃ ). The amount of evaporation was confirmed by monitoring the pressure rise value in the vacuum container 2 before and after the evaporation source was evaporated with a vacuum gauge. Then, as two kinds of ITO films having different film forming speeds, a sample A having a film forming speed of 3 Å / sec and a sample B having a film forming speed of 1 Å / sec were respectively used.
It was manufactured with a thickness of 00Å.

The results of X-ray diffraction measurement and SEM (scanning electron microscope) photographs of the film surface of these samples A and B are shown in FIGS. 1 (a) and 1 (b), respectively. For X-ray diffraction measurement, using JEOL JDX-10RA type,
Applying a voltage of 50 kV and a current of 200 mA to a Cu tube as an X-ray source, and using a two-axis vertical goniometer to sample the angle.
The scanning speed was set to 0.010 degrees, the scanning speed was set to 2.00 degrees / minute, the scanning axis was set to 2θ / θ, the receiving slit width was set to 0.60 mm, and the divergence slit angle, the scattering slit angle, and the receiving slit angle were set to 1 degree. Moreover, the SEM photograph was taken at a tilt angle of 0 degree by performing Pt-Pd vapor deposition on the sample surface using a Hitachi S800 scanning electron microscope.

The average crystal grain size of the ITO transparent conductive film is a SEM photograph taken at a magnification of 50,000 times, and a line with a length of 50 mm is 1
Draw 0 and count the number of crystal particles on each line to 50 m
The average number of crystal grains per m was determined, and the average crystal grain size was calculated from the average number. When the average crystal grain size of Samples A and B was determined from the SEM photograph, the average number of crystal grains was 48.8 in Sample A having a high film formation rate of 3Å / sec, and the average crystal grain size was (50 mm / 4
8.8) ÷ 50,000 = 2.049 × 10 ⁻⁵ mm, that is, as small as 0.020 μm, and the film formation rate is 1Å / sec.
The average number of crystal grains is 28.6 in Sample B, which is slow, and the average crystal grain size is (50 mm / 28.6) ÷ 50,0.
00 = 3.497 × 10 ⁻⁵ mm or 0.035 μm
It was found that there was a correspondence with the film formation rate. In addition, since the peaks of (332), (521), (611), (541), etc. found in Sample A are not observed in the result of X-ray diffraction in Sample B having a slow film formation rate, 211),
It can be seen that crystals with (222), (400), (440) orientations in a particular direction are large. These results,
As can be seen from the SEM photograph, the unevenness formed on the surface of the ITO film is large.
It was confirmed that the crystal orientation of the TO film and the average grain size can be controlled, and thereby the size of the irregularities formed on the film surface can be controlled.

[Example 2] In the same manner as in [Example 1], an outer diameter of 30
mm glass, 260 mm long glass tube substrate having several ITO films with different average crystal grain sizes formed by changing the film forming speed were prepared, and a-Si was formed on the ITO film by the plasma CVD method.
The membrane was laminated.

Here, an example of a plasma CVD film forming reaction furnace for forming an a-Si film will be described with reference to FIG. FIG. 3 is a schematic configuration diagram of the plasma CVD film forming reaction furnace 16. Plasma CVD film forming reaction furnace 16 shown in FIG.
In the figure, 17 is a cylindrical metal reaction furnace, and 18 is ITO.
It is a cylindrical conductive support on which the glass tube substrate 15 on which the film is formed is mounted. The substrate 15 establishes electrical continuity between the ITO film and the support 18, and a non-film-forming portion is formed at the end of the substrate 15. It is held on the support 18 by a mask 19 for providing and a dummy ring 20. Reference numeral 21 is a heater for heating the substrate, 22 is a cylindrical glow discharge electrode plate used for film formation of a-Si, and a large number of gas ejection ports 23 are formed in this electrode plate 22. Further, 24 is a gas inlet for introducing gas into the reaction furnace, 25 is a gas outlet for exhausting residual gas of the gas exposed to glow discharge, and 26 is a conductive support 18 and a glow. Discharge electrode plate 2
It is a high frequency power supply for generating glow discharge between the two. Here, the arrows in the figure represent the flow of gas. Also,
The reactor 16 includes a cylindrical body 17a, a lid body 17b, and a bottom body 17a.
and an insulating ring 17d is provided between the cylindrical body 17a and the lid body 17b, and between the cylindrical body 17a and the bottom body 17c. The terminal is electrically connected to the glow discharge electrode plate 22 through the cylindrical body 17a, and the other terminal is electrically connected to the conductive support body 18 through the lid body 17b and the bottom body 17c and is grounded. In addition, the motor 27 attached on the lid 17b causes the conductive support 1 to pass through the rotary shaft 28.
8 is driven to rotate, and the base 15 also rotates accordingly.

When an a-Si film is formed using this plasma CVD film forming reaction furnace 16, the substrate 15 is used as the support 1.
8, the gas for a-Si generation is introduced into the reaction furnace through the gas introduction port 24, the gas is ejected toward the surface of the substrate 15 through the gas ejection port 23, and the substrate 15 is further heated by the heater 21. The temperature is set to a required temperature, high-frequency power is supplied from the high-frequency power source 26 to generate glow discharge between the support 18 and the electrode plate 22, and the base 15 is further rotated to a. -Form a Si film. In the glow discharge plasma for forming the a-Si film in this manner, hydrogen contained in silane gas or disilane gas as a raw material gas for generating a-Si, or the raw material gas or a-Si From the hydrogen gas used for dilution of the impurity gas added for characteristic adjustment,
Hydrogen radicals that are reducing active species are generated and included.

As an experiment, first, using the ion plating apparatus 1, as in [Example 1], the outer diameter was 30 mm and the length was 2 mm.
Five types of 60 mm glass tube substrates on which an ITO film was formed by changing the film formation rate and changing the average crystal grain size between 0.015 and 0.035 μm were prepared, and plasma CV was formed on the ITO film.
D film-forming reaction furnace 16 was used to perform film formation for 4 hours under the conditions of silane gas 700sccm, gas pressure 0.5 Torr, film formation temperature 250 ° C., and high-frequency power 700W.
-Si films were laminated to prepare samples C to G.

Next, in order to evaluate the adhesion of the ITO film with respect to these samples, the presence or absence of the peeling of the ITO film was visually confirmed at the time of taking out from the film forming reaction furnace after forming the a-Si film. As an accelerated test for adhesion evaluation, each sample was allowed to stand in water for 12 hours and then for another 88 hours (total 100
After standing, the presence or absence of peeling of the ITO film was visually confirmed. The evaluation results are summarized in Table 1 together with the conditions for the film formation rate of the ITO film and the average crystal grain size.

[0022]

[Table 1]

In Table 1, those without peeling are ◯.
When the peeling was observed, the result was indicated by x. As can be seen, there is a correspondence between the occurrence of film peeling, that is, the quality of adhesion and the average crystal grain size of the ITO film, and when the average crystal grain size exceeds about 0.025 μm, peeling Generation is suppressed and adhesion is improved.

Thus, the average crystal grain size is 0.025 μm.
Adhesion is improved by the above, 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 irregularities on the surface becomes insufficient and the stress cannot be absorbed completely and peeling occurs. Therefore, 0.012 μm or more is desirable. On the other hand, as the upper limit of the crystal grain size, the larger the grain size, the lower the conductivity, and the larger the variation in the characteristics due to the change in the environment. ．
It is preferably not more than 05 μm.

[0025]

As described above in detail, according to the present invention, I
In the case where the semiconductor film is laminated on the TO film by a simple method of controlling the film forming conditions, particularly the film forming speed, to control the average crystal grain size, the crystal orientation, the film surface irregularities, and the like. The adhesion of the ITO film could be increased.

Further, according to the present invention, the occurrence of peeling of the ITO film can be suppressed without causing technical difficulties and an increase in cost for forming the film.

[Brief description of drawings]

FIG. 1 (a) and (b) are the results of X-ray diffraction measurement and scanning electron micrographs of the film surface.

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 ... Ion plating device 3 ... Evaporation source 4 ... High frequency coil 9, 26 ... High frequency power supply 15 ... Base 16 ... Plasma CVD film forming reactor 22 ...- Glow discharge electrode plate

Claims (1)

[Claims] 1. A transparent conductive film having an ITO crystal having an average crystal grain size of 0.025 μm or more is formed on a transparent substrate by a thin film forming means, and a reducing active species is contained on the transparent conductive film. A method of manufacturing a semiconductor element formed by forming a semiconductor film with plasma.