JPH1093090A - Semiconductor device, its manufacture, and organic resin substrate for semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable forming a coating, having a sufficient barrierability, even if a general resin material is used, by forming a semiconductor film in which an active layer for a semiconductor device has been formed, on an inorganic insulating film containing specified impurities on an organic resin substrate. SOLUTION: An acrylic resin substrate containing Na being an alkaline metal of a sufficient concentration is used. First, SiO2 2 of 30nm is deposited on a substrate 1 by 100 deg.C plasma CVD, using SiH4 and N2 O as materials. The formation condition is 120 deg.C. Following this, this substrate 1 is dipped in a 5% NaCl aqueous solution 3, put in a glass container 5 for 48 hours, is washed simply after that, and is dried subsequently to form a plastic substrate sufficiently polluted by Na. An SiO2 film 4 is deposited by 200nm with CVD, similarly to the SiO2 2 forming process. Next, As ions are used and implanted to a specified concentration with an acceleration energy of 40keV, it is possible to obtain a blocking ability with respect to alkaline metals by this coating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device, a method for manufacturing a semiconductor device, and an organic resin substrate for a semiconductor device.

[0002]

2. Description of the Related Art In a liquid crystal display device, to reduce its weight,
There is a movement to adopt a resin substrate or a film with respect to a conventional glass substrate, and some of them have been commercialized. In order to form a semiconductor film on a resin substrate, it is usual to deposit an insulating film of an inorganic material typified by silicon oxide as a base coat film on the surface of the resin substrate. This is performed in order to prevent outgassing when resin is put in a vacuum device frequently used in semiconductor manufacturing and to reduce the influence of moisture permeation on the display device. This is because the organic resin inevitably contains various volatile gases, and has a significantly lower barrier property to water than glass materials.

However, these inorganic material films formed on the resin substrate cannot be expected to have a barrier property against alkali metals. A material used for the coating film;
In particular, this is because the diffusion coefficient of the alkali metal in the silicon oxide is large. Needless to say, alkali metals must be removed for stable operation of the semiconductor device. Therefore, non-alkali glass or low-alkali glass is usually used in a conventional liquid crystal display device formed on a glass substrate. On the other hand, removing the alkali metal impurities from the resin substrate requires a review of the production itself in order to achieve a higher purity of the material based on the aliphatic base, and causes an increase in the production cost, if not impossible. The resin substrate material was originally a general structural material, and there was a problem that it was not always advantageous to set up a special high-purity production line for a liquid crystal display device with a small usage fee.

[0004]

The conventional liquid crystal display device using an organic substrate material has a problem in that there is no high-performance liquid crystal display device capable of performing a stable operation due to an alkali metal present in the organic substrate material. .

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and an organic resin substrate having a coating film having a sufficient barrier property against alkali metals even when a general resin material is used. It is an object of the present invention to provide a high-performance semiconductor device using the substrate and a method for manufacturing the same.

[0006]

In order to achieve the above object, according to the present invention, there is provided an organic resin substrate, an inorganic insulating film formed on the organic resin substrate and containing a predetermined impurity, and A semiconductor film formed on an inorganic insulating film and having an active layer of a semiconductor element formed thereon.

Further, the invention of claim 2 is a step of forming an inorganic insulating film on an organic resin substrate, a step of injecting a predetermined impurity into the inorganic insulating film, and a step of injecting the impurity into the inorganic insulating film. Forming a semiconductor film on which an active layer of a semiconductor element is formed on the film.

Further, according to a third aspect of the present invention, in the second aspect of the present invention, the inorganic insulating film comprises an oxide, a nitride,
At least one material selected from fluorides, and in the impurity implantation step, the impurity ions are implanted by an ion implantation method and accelerated to remain in the inorganic insulating film to have a dose of 1 × 10 14 / cm 2 or more. A method for manufacturing a semiconductor device is provided.

The invention according to claim 4 is the method according to claim 3, wherein the oxide, the nitride and the fluoride are silicon oxide,
An object of the present invention is to provide a method for manufacturing a semiconductor device, which is selected from silicon nitride, magnesium oxide, magnesium fluoride, zirconium oxide, zirconium nitride, and calcium fluoride.

Further, according to a fifth aspect of the present invention, there is provided an organic resin substrate for use in a semiconductor device, comprising: an organic resin substrate; and an inorganic insulating film containing predetermined impurities formed on the organic resin substrate. A resin substrate is provided. Here, the organic resin substrate is not limited to a plate-shaped one such as a resin substrate, but may be a film-shaped one such as a resin film.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention provides an inorganic insulating layer, particularly an oxide, a nitride or a fluoride, on an organic resin substrate, particularly a transparent organic resin substrate, such as an organic plastic substrate or an organic film, on which a display device is to be formed. The main point is to use a substrate formed by forming a surface coat film of a compound and implanting predetermined impurities, preferably ions, on the surface of the coat film.

In the present invention, the alkali metal in the transparent organic resin substrate utilizes the property of diffusing between lattices in the substrate material and gathering in defects. When ion implantation is performed on the surface coat film, the molecular bond of the material of the surface coat film is broken.
Either the interstitial diffusion is suppressed by the broken bond, or the alkali metal gathers at the broken bond, that is, the defect, or by both effects, a coat film having a high diffusion blocking ability against the alkali metal. Take advantage of

[0013]

【Example】

(Embodiment 1) FIG. 2 is a sectional view in the order of processes for explaining an embodiment of the present invention. In this embodiment, the cheapest plastic substrate containing a sufficient concentration of alkali metal Na was used. This is usually the case for structural plastics produced without control over alkali metals. In this embodiment, an acrylic resin substrate was used as the substrate material.

First, a 30 nm SiO2 film was formed on a substrate 1 by plasma CVD at 100 ° C. using SiH4 and N2O as raw materials.
2 was deposited. The forming conditions were 120 ° C. (FIG. 2)
(A)). Then, the substrate 1 was immersed in a 5% aqueous solution of NaCl 3 in a glass container 5 for 48 hours, washed briefly with water, and dried to obtain a plastic substrate sufficiently contaminated with Na (FIG. 2B).

Again, a 200 nm SiO2 film 4 was deposited by the same CVD method as in the SiO2 2 forming step described above (FIG. 2).
(C)). Next, a predetermined concentration was implanted at an acceleration energy of 40 KeV using As ions 5a, which is a main step of this embodiment. In the embodiment, As ions are used, but the present invention is not particularly limited thereto. However, ions having a light mass are deeply implanted, and it is not preferable that the ions reach the resin substrate. In this case, As was used for this substrate (FIG. 3A).

Further, SiO2 6 was deposited to a thickness of 100 nm by the same CVD method as in the above-described SiO2 2 forming step. The deposition temperature is 100 ° C., and at a temperature lower than 350 ° C., the bond broken by the ion implantation is not recovered by annealing. Originally, this embodiment is intended to be applied to a resin substrate, and since the heat resistance of the resin substrate is at most 150 ° C., the effect of ion implantation is not reduced by the temperature in the manufacturing process. No (Fig. 3
(B)).

Thereafter, in order to find a change in Na that can be analyzed, the substrate was treated in an inert gas at 150 ° C. for 168 hours (FIG. 3C). Finally, sodium near the outermost surface was measured by secondary ion mass spectrometry. For comparison, a sample not immersed in the NaCl solution was also analyzed (FIG. 3D).

FIG. 1 shows the results of analysis of the samples manufactured according to the steps shown in FIGS. This result is 150 ° C
168 hours. The results in FIG. 1 can be understood as an accelerated durability test. In the figure, the concentration of As
Is 5 × 10 15, B is 5 × 10 14, C is 1 × 10 14, D is 5 × 10 13, E is an impurity-implanted state, and NaCl
The sample was not immersed in the solution.

As apparent from FIG. 1, it was found that the amount of Na found on the surface of the sample subjected to the ion implantation at a high concentration tended to be small. The signal of Na is also seen in the sample not immersed in NaCl, because Na actually exists as a contamination on the sample surface. As a result, the effect becomes remarkable around the implantation of 1.times.10.sup.14 As ions / cm.sup.2, and it is understood that the coating film of the present invention has an ability to block alkali metals.

In the present embodiment, As ions are used. However, the present invention is not limited thereto. As the implanted ions, in addition to the insoluble gas such as Ar, O, N, F, and Si, the elements constituting the inorganic insulating film may be used. For example, P, B, etc. may be used. In particular, when P is injected in a large amount, an effect of gettering an alkali metal can be expected. It is also necessary to note that B has a large ion implantation depth due to a small mass number and a small lattice breaking ability.

Using the above-mentioned organic resin substrate, a reflection type liquid crystal display device was formed. As the active element, a thin film diode was employed. Except for the thin film diode, it is the same as the second embodiment.

In a transmissive liquid crystal display device having a backlight or the like, when ions reach an organic resin substrate, organic molecules are destroyed, and the substrate which should be transparent is colored, and the transmittance is deteriorated.・ Problems come up. On the other hand, in the reflection type liquid crystal display device formed on the resin substrate, even if the ions reach the resin substrate, it does not cause an essential defect. Therefore, the organic resin substrate of this embodiment is suitable for the reflection type liquid crystal display device. I have. Further, the reflection type is often used for a portable display device because of its light weight and low power consumption. Therefore, a lighter, non-breakable resin substrate is more suitable for a reflection type than a liquid crystal display device using a conventional glass substrate.

(Embodiment 2) This embodiment is different from Embodiment 1 in that the organic resin substrate, the impurities to be implanted and the like are changed. FIG. 4 shows an actual manufacturing method. First, an allyl resin 7 which is a thermosetting resin is formed by a so-called chemical conversion sputtering method using Ar2 and O2 plasma with SiO2 as a target.
An SiO2 film 8 is deposited to a thickness of 1000 nm on the substrate formed by the method described above. The substrate temperature inevitably rises during sputter deposition, but the temperature was kept below 100 ° C. because of the resin substrate (FIG. 4A).

Further, in the embodiment, the Ar ions 9 are accelerated 2
6 × 10 14 / cm 2 were implanted at an energy of 0 KeV. However, in consideration of the substrate temperature rise,
It was held low so that it did not exceed. In addition to the sputtering method, deposition may be performed using a plasma CVD method (FIG. 4).
(B)).

Next, an MgF film 10 was deposited to a thickness of 20 nm by the same sputtering method as that for the SiO 2 film 8 in the step of FIG. The MgF film is not essentially related to the present invention. It is contained as an impurity in the resin. As described in Example 1, the barrier property against the alkali metal is sufficient even without the MgF film. The reason why MgF was deposited is that the film quality of amorphous Si formed in the subsequent steps is improved. A group II fluoride such as CaF may be used instead of MgF (FIG. 4).
(C)).

Thereafter, a thin film transistor as an active element was formed on the above-described amorphous silicon film on the resin substrate in the following manufacturing process order. That is, Mo is applied on the allyl resin substrate 7.
After the W film is formed by the sputtering method, unnecessary portions are removed by etching to form a gate electrode, and then a two-layered gate insulating film 42 of silicon oxide silicon oxide is formed on the gate electrode. Further, an undoped amorphous silicon film, n
A + type amorphous silicon film and a MoW film are sequentially formed, and unnecessary portions are removed by etching.
The thin film transistor is completed by forming the contact layer 44 and the channel forming layer 43. However, in the case of this embodiment, the maximum temperature in the same step was suppressed to 130 ° C. (FIG. 4).
(D)).

This thin film transistor (TFT) can be used as a pixel electrode switching TFT of a reflection type liquid crystal display device as in the first embodiment. The present invention is not limited to this liquid crystal display device, and can be applied as a switching element of a plasma display. In any case, T
In order for the FT to withstand practical use, it is required that the threshold value does not easily fluctuate under high gate bias conditions.

This performance will be described below with reference to FIG.
A long-time voltage load at 50 ° C. is applied to the TFT manufactured according to the second embodiment, and the metal wiring in the figure is used as an earth potential.
Transistor threshold change (ΔVth) after applying ± 15 V as a bias to the gate metal electrode. a and d are the conditions of no ion implantation and a gate bias of +15 V and-
15 are applied, and b and c are applied with a gate bias of +15 V and -15, respectively, under the condition of ion implantation. From this figure, it was found that a transistor formed on a substrate on which no ion implantation was performed had a larger Vth change attributed to an alkali metal than a transistor formed by ion implantation.

The transistor having the ion-implanted coat film of this embodiment is more excellent in long-term stability.
In the first and second embodiments, the present invention is applied to one surface of the organic resin substrate. Needless to say, it is necessary to coat both the front and back surfaces for the purpose of barrier of volatile gas from the resin. Further, the ion implantation of the present invention is desirably performed on both surfaces. Even if the alkali metal diffuses from the resin on the back side, it is not necessary to consider the effect on the device characteristics of the front side formed. However, it is necessary to sufficiently consider the possibility that the contamination from the resin back surface may accumulate and contaminate the manufacturing apparatus in the manufacturing process.

Further, it is advantageous to form a coating film of silicon oxide or the like on the surface with a high degree of flaws caused by transport. In addition, the reflection type liquid crystal display device using this TFT is significantly different from the conventional structure without ion implantation in the characteristics centering on reliability such as in-plane uniformity of image quality and maintenance of contrast for a long time. Performance improvement was seen.

[0031]

According to the present invention, a core having a sufficient barrier property against alkali metals even when an organic resin material substrate is used.
It is possible to provide an organic resin substrate for forming a semiconductor device having a thin film, and to provide a high-performance semiconductor device which could not be obtained conventionally by using this substrate, and a method for manufacturing the same. .

[Brief description of the drawings]

FIG. 1 illustrates a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a manufacturing process of the semiconductor device according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a manufacturing process of a semiconductor device according to a second embodiment of the present invention.

FIG. 4 is a diagram illustrating a manufacturing process of a semiconductor device according to a second embodiment of the present invention.

FIG. 5 is a diagram illustrating a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 plastic substrate 2 SiO2 film 3 NaCl solution 4 SiO2 film 5 glass container 6 amorphous silicon film 7 allyl resin base material 8 SiO2 film 9 Ar ion 10 MgF film

Claims (5)

[Claims] An organic resin substrate, an inorganic insulating film formed on the organic resin substrate and containing predetermined impurities, and a semiconductor film formed on the inorganic insulating film and having an active layer of a semiconductor element formed thereon. A semiconductor device comprising: A step of forming an inorganic insulating film on the organic resin substrate; a step of injecting a predetermined impurity into the inorganic insulating film; and a step of forming a semiconductor element on the impurity-implanted inorganic insulating film. Forming a semiconductor film on which an active layer is to be formed. 3. The inorganic insulating film is made of at least one material selected from oxides, nitrides and fluorides, and in the impurity implanting step, the impurity ions are implanted by ion implantation. 3. The method of manufacturing a semiconductor device according to claim 2, wherein the dose is increased to 1.times.10@14 / cm @ 2 or more by accelerating in the insulating film. 4. The oxide, nitride or fluoride is selected from silicon oxide, silicon nitride, magnesium oxide, magnesium fluoride, zirconium oxide, zirconium nitride and calcium fluoride. The method for manufacturing a semiconductor device according to claim 3. 5. An organic resin substrate for a semiconductor device, comprising: an organic resin substrate; and an inorganic insulating film formed on the organic resin substrate and containing a predetermined impurity.