JPH11261073A - Semiconductor element and its heating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To conduct a great amount of heat values by an amorphous semiconductor layer, by a method wherein a second insulation layer is arranged between the amorphous semiconductor layer and a heat generation layer, and the amorphous semiconductor layer is heated by the heat generation layer via the second insulation layer. SOLUTION: First, a silicon oxide film is formed as a first insulation film 2 on a surface of a glass substrate 1. Next, a film of Pt, etc., having resistivity of 5 to 250 μΩ.cm as a heat generation layer 3 is formed on the first insulation film 2, and the film of a portion corresponding to a pixel is removed. Thereafter, a silicon oxide film is provided as a second insulation film 4 on the heat generation layer 3 provided with an opening part. Further, a silicon film 5 is formed as an amorphous semiconductor layer on the second insulation film 4. The silicon film 5 is locally heated and fused by laser beams to be crystallized, and a current flows from an external power supply electrically connected to the heat generation layer 3 to heat the heat generation layer 3, and the heat preheats the silicon film 5. Therefore, it is possible to prevent an increase in temperature of the glass substrate 1 and preheat effectively a silicon film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device such as a thin film transistor array used for an active matrix type liquid crystal display device and the like, and a method of heating the same.

[0002]

2. Description of the Related Art At present, in a thin film transistor array as a semiconductor element used in an active matrix type liquid crystal display device, a strain point of the substrate is 990.degree. It is required to use a non-alkali glass having a strain point of 610 ° C. to 670 ° C. instead of quartz glass having a temperature of from 1000 ° C. to 1000 ° C.

As a method of crystallizing an amorphous silicon film as an amorphous semiconductor layer, a method of locally melting and crystallizing the amorphous silicon film using a laser beam has been adopted. ing. It is known that in crystallization using this laser beam, the preheating temperature of the amorphous silicon film affects the state of crystallization, and the higher the temperature, the larger the crystal grains and the better the crystallization. There is a tendency to show sex.

[0004]

However, conventionally, as shown in FIG. 6, the preheating of the silicon film 5 is performed by bringing the back surface of the glass substrate 1 into contact with the heating plate 17 and conducting heat through the glass substrate 1. When the preheating temperature approaches the strain point of the glass substrate 1, warpage of the glass substrate 1 occurs, and so on.
There is a problem that the silicon film 5 cannot be sufficiently preheated.

An object of the present invention is to provide a polycrystalline semiconductor layer which can heat an amorphous semiconductor layer to a higher temperature than conventional ones, has excellent crystallinity, and provides a high-performance semiconductor device and a heating method therefor. And

[0006]

According to a first aspect of the present invention, there is provided a substrate, a first insulating layer provided on the substrate,
A heating layer provided on at least a portion of the first insulating layer; a second insulating layer provided to cover the heating layer; and a second insulating layer provided on the second insulating layer, and at least a portion of the second insulating layer is provided on the second insulating layer. A semiconductor element comprising: an amorphous semiconductor layer facing the heat generating layer with two insulating layers interposed therebetween.

According to the first aspect of the present invention, the second insulating layer is provided between the amorphous semiconductor layer and the heat generating layer, and the amorphous semiconductor layer is provided with the second insulating layer. Heated by the heating layer through the layers. For this reason, unlike the related art, it is not necessary to consider the strain point of the substrate in a form in which the amorphous semiconductor layer is heated through the substrate, so that a larger amount of heat is applied to the amorphous semiconductor layer than in the related art. It is possible to conduct.

Further, according to the first aspect of the present invention, the first insulating layer is provided between the substrate and the heat generating layer.
The amount of heat conducted to the substrate can be reduced as compared with the conventional case where the heating plate is directly in contact with the substrate.

As described above, according to the first aspect of the invention, the amorphous semiconductor layer can be heated to a higher temperature while minimizing the softening of the substrate, and the polycrystalline semiconductor layer having excellent crystallinity can be provided. A semiconductor device is obtained.

According to the fourth aspect of the present invention, since the heat generating layer is a transparent conductive film, the heat generating layer can be provided on the entire surface of the substrate without providing an opening for transmitting light in the heat generating layer. This simplifies the manufacturing process.

According to the invention of claim 6, the first insulating layer and the second insulating layer are made of the same material, and the second insulating layer has a smaller thickness than the first insulating layer. Therefore, of the heat generated in the heat generating layer, the heat transferred to the amorphous semiconductor layer is larger than the heat transferred to the substrate. Thus, the amorphous semiconductor layer can be more efficiently heated to a high temperature while the softening of the substrate is prevented, and a semiconductor element having a polycrystalline semiconductor layer with more excellent crystallinity can be obtained.

According to the eighth aspect of the present invention, the second insulating layer is made of a material having a higher thermal conductivity than the first insulating layer. The rate of heat conduction of the heat conducted to the layer is greater than the rate of heat conducted to the substrate. Thus, the amorphous semiconductor layer can be more efficiently heated to a high temperature while the softening of the substrate is prevented, and a semiconductor element having a polycrystalline semiconductor layer with more excellent crystallinity can be obtained.

According to the tenth aspect of the present invention, since the current used to heat the heat generating layer is generated by electromagnetic induction, heat can be generated without electrically connecting the heat generating layer to the outside. Can be simplified.

A twelfth aspect of the present invention is a heating method for crystallizing an amorphous semiconductor layer in a semiconductor device having a substrate and an amorphous semiconductor layer. A method for heating a semiconductor element, characterized in that an amorphous semiconductor layer can be heated by a heat generating layer without interposing a substrate by causing a heat generating layer disposed between the heat generating layers to generate heat.

According to the twelfth aspect of the present invention, the heat generating layer disposed between the substrate and the amorphous semiconductor layer is caused to generate heat, so that the amorphous semiconductor layer is formed by the heat generating layer without the substrate. Since it is possible to heat, it is not necessary to consider the strain point of the substrate in the form in which the amorphous semiconductor layer is heated through the substrate as in the conventional case.
A larger amount of heat can be conducted to the amorphous semiconductor layer. Thus, the amorphous semiconductor layer can be more efficiently heated to a high temperature.

A thirteenth aspect of the present invention is a heating method for crystallizing an amorphous semiconductor layer in a semiconductor device having a substrate and an amorphous semiconductor layer. The first conductive heat transmitted from the heat generating layer to the amorphous semiconductor layer is larger than the second conductive heat transmitted from the heat generating layer to the substrate. A method for heating a semiconductor element, characterized in that:

According to the thirteenth aspect of the present invention, the heat generation layer disposed between the substrate and the amorphous semiconductor layer generates heat,
The first conductive heat transmitted from the heat generating layer to the amorphous semiconductor layer is larger than the second conductive heat transmitted from the heat generating layer to the substrate. This makes it possible to more efficiently heat the amorphous semiconductor layer to a high temperature while preventing softening of the substrate.

According to a fourteenth aspect of the present invention, there is provided a heating method for crystallizing an amorphous semiconductor layer in a semiconductor device having a substrate and an amorphous semiconductor layer, wherein heat generated in the semiconductor device is provided. Is a first conductive material that is conducted to the amorphous semiconductor layer.
And a second conduction heat conducted to the substrate. The method for heating a semiconductor element comprises the steps of:

According to the fourteenth aspect of the present invention, the amorphous semiconductor layer is heated by the first conduction heat different from the second conduction heat conducted to the substrate. Does not need to be considered, and it becomes possible to conduct more heat to the amorphous semiconductor layer than before. This makes it possible to more efficiently heat the amorphous semiconductor layer to a high temperature while preventing softening of the substrate.

According to the fifteenth aspect of the present invention, the amount of heat of the first conductive heat is larger than that of the second conductive heat, so that the amorphous semiconductor layer can be more efficiently formed while preventing the substrate from softening. Can be heated to a high temperature.

[0021]

Next, a specific example of the present invention will be described.

(Embodiment 1) FIG. 1 is a sectional view of a semiconductor device according to a first embodiment of the present invention, and FIG. 2 is an explanatory view showing a crystallization method of the first embodiment of the present invention. .

Hereinafter, the configuration and the manufacturing process of the semiconductor device shown in FIG. 1 will be described. First, a silicon oxide film serving as the first insulating layer 2 is formed on the surface of the glass substrate 1 by CVD or the like at 700 nm to 1 μm.

Next, on the first insulating layer 2, as the heat generating layer 3, Pt, W, Mo, Ni—Cr alloy, Fe—Cr—Al having a resistivity of 5 μΩ · cm to 250 μΩ · cm.
One of an alloy, SiC, MoSi2, and TaN is formed by sputtering, and a portion of the film corresponding to the pixel is removed by photolithography. Each of the above-mentioned materials for the heat generating layer 3 is widely used as an electrothermal resistance material, and has a maximum operating temperature of at least 1,100.
Exceeds ° C.

Then, on the heat generating layer 3 provided with the opening,
A silicon oxide film is provided as the second insulating layer 4 using CVD. The film thickness of the first insulating film 2 is set to be large in order to increase the amount of heat conduction to the silicon film 5 and to prevent the material forming the heat generating layer 3 from diffusing into the silicon film 5. 1% of thickness
５０50%, preferably around 100 nm in film thickness.

Further, on the second insulating layer 4, a plasma C
The silicon film 5 as an amorphous semiconductor layer is
It is formed at a temperature of 00 ° C. or less. Silicon film 5 formed
Is locally heated and melted by a laser beam 6 to be crystallized. At this time, the heating layer 3 is heated by flowing a current from an external power supply 7 electrically connected to the heating layer 3, and the heat is converted to a silicon film. The silicon film 5 is preheated by conducting to the side 5.

Here, the heat generated in the heat generating layer 3 is divided into a first conductive heat conducted to the silicon film 5 through the second insulating film 4 and a glass substrate 1 through the first insulating film 2. And the second heat is conducted separately to the second heat.

In this case, the first and second insulating films are both silicon oxide films, and the first insulating film 2 has a thickness of 700 nm to 1 nm.
μm, the second insulating film 4 has a thickness of 100 nm.
More will be conducted. That is, the first conductive heat has a larger heat quantity than the second conductive heat.

As a result, the temperature of the glass substrate 1 can be prevented from rising, and the silicon film 5 can be effectively preheated.

As described above, after crystallizing the silicon film 5, unnecessary portions of the silicon film 5 are removed by photolithography to form a silicon pattern. After forming the silicon pattern, a silicon oxide film is formed as the gate insulating film 8. After forming an Al film as a gate metal,
A gate pattern 9 is formed by using photolithography. After the formation of the gate pattern 9, the transparent conductive film IT
A pixel electrode 10 is formed using O, a silicon oxide film is provided as an interlayer insulating film 11, a contact hole at a connection portion is formed, an Al film is provided as a wiring layer, and a wiring pattern 12 is formed by photolithography. Form.

Finally, a portion other than the pixel electrode is formed on the silicon nitride film 1.
3 and the TFT array is completed.

In the TFT array manufactured as described above, when preheating when crystallizing a silicon film using a laser beam, the entire glass substrate is preheated from the back surface of the glass substrate as in the conventional case. The amount of heat conducted to the glass substrate can be reduced by the first insulating layer without increasing the temperature of the first insulating layer, and more amorphous silicon patterns can be formed through the second insulating film which is relatively thinner than the first insulating layer. Because it conducts heat, the amorphous silicon pattern can be more efficiently preheated to a high temperature without softening the glass substrate, and a silicon film with excellent crystallinity can be obtained, and a high performance thin film transistor array Can be realized.

When used for a light valve of a projection type liquid crystal display device, there is a secondary effect that the pattern of the heat generating layer can be used as a light shielding film.

In this embodiment, a silicon oxide film is used as the first and second insulating films made of the same material. However, the present invention is not limited to this. For example, another insulating film such as silicon nitride may be used. It is also possible to apply

Further, in the present embodiment, in order to make the first conduction heat larger than the second conduction heat,
The first and second insulating films are made of the same material, and the first insulating film 2 has a larger thickness than the second insulating film 4. However, the present invention is not limited to this. For example, the first and second insulating films may be used. The film is made of a different material, a material having higher thermal conductivity than the first insulating film 2 is applied as the second insulating film 4, and the film thicknesses of the first and second insulating films are appropriately set. Is also good. As an example, the first
Silicon oxide is applied as the first insulating film 2, silicon nitride is applied as the second insulating film, and the first insulating film 2 is formed as the second insulating film 4.
A larger film thickness may be used.

The substrate material is not limited to non-alkali glass, but other materials having a relatively low strain point can be used. Of course, materials such as quartz glass having a relatively high strain point can be used. It does not prevent the application of.

(Embodiment 2) FIG. 3 is a sectional view of a semiconductor device according to a second embodiment of the present invention, and FIG. 4 is an explanatory view showing a crystallization method of the second embodiment of the present invention. .

Here, the configuration and the manufacturing process of the semiconductor device shown in FIG. 3 will be described. First, a silicon oxide film as the first insulating layer 2 is formed on the surface of the glass substrate 1 by CVD or the like at 700 nm to 1 μm.

Next, a transparent conductive film is formed as the heat generating layer 3 on the first insulating layer 2. As the transparent conductive film, tin oxide and ITO are known, but it is desirable to use ITO used as a material of a pixel electrode of a TFT array. In the case where an opaque film is used for the heat generating layer 3, it is necessary to remove the film corresponding to the pixel by using photolithography. And the process is simplified.

The following manufacturing process is the same as in the first embodiment. In the TFT array manufactured in this way, the use of a transparent conductor as the material of the heat generating layer makes it unnecessary to provide an opening unlike the case of using an opaque material, so that the process is simplified. In addition to having the effect, as in the first embodiment, when preheating when crystallizing the silicon film of the thin film transistor using a laser beam, as in the case of performing preheating from the back surface of the glass substrate as in the related art, Without increasing the temperature of the entire substrate, the amount of heat conducted to the glass substrate by the first insulating layer is reduced, and more heat is transferred to the silicon film through the second insulating film, which is relatively thinner than the first insulating layer. Since it conducts, the amorphous silicon pattern can be more efficiently preheated to a high temperature without causing the glass substrate to soften, and the silicon having excellent crystallinity can be obtained. Film is obtained, it is possible to realize a high-performance thin-film transistor array.

The secondary effect that a storage capacitor is formed between the heat generating layer and the pixel electrode by electrically grounding the heat generating layer can be obtained.

(Embodiment 3) FIG. 5 shows a third embodiment of the present invention.
It is explanatory drawing which shows the crystallization method of embodiment.

Here, a case where the crystallization method of the present invention is applied to the semiconductor device having the structure of the second embodiment will be described with reference to FIG.

The heat generating layer 3 made of a transparent conductive material and formed on the first insulating film 2 alternates by applying an alternating current from an external power supply 7 to a coil 14 located in a position close to the glass substrate 1. When the magnetic field 15 is generated, the eddy current 16
Is induced, and the eddy current 16 flows, so that the heating layer 3
Generates heat. The generated heat is conducted to the silicon film 5 through the second insulating film 4 to preheat the silicon film 5. At the same time, the surface of the silicon film 5 is irradiated with a laser beam 6 to crystallize the silicon film 5.

When the silicon film is preheated by using the induction heating as described above, the silicon film can be preheated without electrically connecting the heat generating layer to an external power supply, so that the effect of simplifying the manufacturing process can be obtained. Can be

[0046]

As described above, according to the present invention, an amorphous semiconductor layer can be heated to a higher temperature than before, and a polycrystalline semiconductor layer having excellent crystallinity can be obtained to provide a high-performance semiconductor device. can do.

[Brief description of the drawings]

FIG. 1 is a sectional view of a first embodiment of a semiconductor device according to the present invention;

FIG. 2 is an explanatory view showing a crystallization method according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a second embodiment of the semiconductor device according to the present invention;

FIG. 4 is an explanatory view showing a crystallization method according to a second embodiment of the present invention.

FIG. 5 is an explanatory view showing a crystallization method according to a third embodiment of the present invention.

FIG. 6 is an explanatory view showing a conventional crystallization method.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 glass substrate 2 first insulating layer 3 heating layer 4 second insulating layer 5 silicon film 6 laser beam 14 coil 15 magnetic field 16 eddy current 17 heating plate

Claims (15)

[Claims] 1. A substrate, a first insulating layer provided on the substrate, a heating layer provided on at least a part of the first insulating layer, and a second heating layer provided so as to cover the heating layer. A semiconductor element comprising: an insulating layer; and an amorphous semiconductor layer provided on the second insulating layer, at least a portion of which is opposed to the heat generating layer with the second insulating layer interposed therebetween. 2. The heat-generating layer has a thickness of 5 μΩ · cm to 250 μΩ · cm.
The semiconductor device according to claim 1, wherein the semiconductor device is made of a material having a resistivity of about 1 cm. 3. The heating layer is made of Pt, W, Mo, Ni.
-Cr alloy, Fe-Cr-Al alloy, SiC, MoSi
2. It is any one of TaN.
A semiconductor device according to item 1. 4. The semiconductor device according to claim 1, wherein the heat generating layer is a transparent conductive film. 5. The semiconductor device according to claim 4, wherein the material of the heat generating layer is ITO. 6. The method according to claim 1, wherein the first insulating layer and the second insulating layer are made of the same material, and the second insulating layer has a smaller thickness than the first insulating layer. The semiconductor element as described in the above. 7. The semiconductor device according to claim 1, wherein the second insulating layer is 1% to 5% of the first insulating layer.
7. The semiconductor device according to claim 6, having a layer thickness of 0%. 8. The semiconductor device according to claim 1, wherein the second insulating layer is made of a material having higher thermal conductivity than the first insulating layer. 9. The material of the first insulating layer is silicon oxide,
The semiconductor device according to claim 8, wherein the material of the second insulating layer is silicon nitride. 10. The semiconductor device according to claim 1, wherein the heat generating layer is heated by induction heating by flowing an eddy current generated by electromagnetic induction. 11. The amorphous semiconductor layer is crystallized by using both induction heating by flowing an eddy current generated by electromagnetic induction to the heating layer and heating by beam irradiation. The semiconductor device according to claim 10, wherein 12. A heating method for crystallizing an amorphous semiconductor layer in a semiconductor device having a substrate and an amorphous semiconductor layer, wherein the heating element is provided between the substrate and the amorphous semiconductor layer. A method for heating a semiconductor element, characterized in that an amorphous semiconductor layer can be heated by a heat generating layer without passing through a substrate by causing the layer to generate heat. 13. A heating method for crystallizing an amorphous semiconductor layer in a semiconductor device having a substrate and an amorphous semiconductor layer, wherein the heating element is disposed between the substrate and the amorphous semiconductor layer. The layer generates heat so that the first conductive heat transmitted from the heat generating layer to the amorphous semiconductor layer is larger than the second conductive heat transmitted from the heat generating layer to the substrate. A method for heating a semiconductor element. 14. A heating method for crystallizing an amorphous semiconductor layer in a semiconductor device having a substrate and an amorphous semiconductor layer, wherein heat generated in the semiconductor device is an amorphous semiconductor layer. A first conductive heat conducted to the substrate and a second conductive heat conducted to the substrate, wherein the heat is divided and conducted. 15. The method according to claim 14, wherein the first conduction heat is set to be larger than the second conduction heat.