JP3369240B2 - Semiconductor device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a thin film semiconductor device, a liquid crystal electro-optical device using the thin film semiconductor device, and its applied products.

[0002]

2. Description of the Related Art With the improvement in performance of thin film transistors, as a driving device for semiconductor elements such as image sensors,
It is also widely used in liquid crystal display panels and the like.

Image sensors are widely used in copiers, facsimiles, word processors, etc., and have become a part of the information industry that surrounds computers. Such products are always required to have higher performance and lower costs. In order to meet the demand, there is an increasing demand for more advanced technology such as driving an image sensor with a thin film transistor.

Liquid crystal display devices have become widespread as devices having an extremely simple structure such as a clock, and in recent years, efforts have been made to develop a device that sells information amount and clarity comparable to that of a high-definition television. Have been paid.

There is a strong tendency to increase the area as an indication of the improvement in the performance of image sensors and liquid crystal displays. Especially for liquid crystal displays, when aiming for a high-definition television, it may be necessary to use a 1-inch square substrate with a diagonal of 40 inches.

Further, considering the improvement of the yield and the improvement of the productivity, there is a case where a single panel is manufactured on a large-sized substrate even if the panel size is small, and then a multiple cutting method for cutting a large number of small panels is performed. .

[0007]

When a liquid crystal cell is manufactured using such a large-area substrate, various problems that have not occurred until now have occurred.

First, the substrate used is usually glass having a thickness of about 1 mm. When the substrate area is small, the rigidity is maintained, but when it is 1 m square, it flexes as if it were paper rather than rigidity. Even if two substrates are bonded together to form a liquid crystal cell with a certain distance, it is impossible to realize it in a state like paper.

When a 1 m square cell is manufactured using the specifications as it is currently manufactured, the panel weight is 9 kg and the amount of liquid crystal used is 60 g. Even if this cell is erected vertically, the lower part swells and the lower part becomes several tens to several hundred times as large as the upper substrate spacing.

On the other hand, if a substrate having a large thickness is used, the weight becomes large, resulting in difficulty in handling the substrate, causing various problems such as enormous production equipment and increased risk.

The manufacturing process of a thin film transistor is very long and complicated, and requires a large number of personnel and time. In the conventional substrate, cracks and chips are likely to occur in each process, and the manufacturing yield is likely to be reduced.

[0012]

The present invention is characterized by having an insulating substrate, a thin film transistor on one surface of the substrate, and a reinforcing material laminated on the other surface of the substrate. It is a semiconductor device. That is, according to the present invention, as shown in FIG. 1, a thin film transistor 111 is formed on an insulating substrate 110, and a reinforcing material 112 is laminated on a surface opposite to the surface of the insulating substrate on which the thin film transistor is formed. .

To manufacture this, the insulating substrate and the reinforcing material are laminated on the insulating substrate during or after the step of forming the thin film transistor.

The heat treatment temperature required in the thin film transistor forming step performed after the laminating step must be lower than the heat resistant temperature of the reinforcing material. In order to protect this, the type of lamination material and the order of lamination are determined.

[0015]

As shown in FIG. 1, a thin film transistor 111 is formed on an insulating substrate 110, and a reinforcing material 1 is formed on the surface opposite to the surface of the insulating substrate on which the thin film transistor is formed.
When 12 layers are stacked, the strength of the substrate increases. Furthermore, the same strength requires less weight than glass alone.

As the reinforcing material, epoxy resin, ultraviolet curable resin, nylon, polymethylmethacrylate (PM
MA), acrylic resin, PES, PET, polytetrafluoroethylene (PTFE), polyimide, polyetheramide, PEEK, EVA, glass, water glass, ceramic material, wood, printed circuit board, glass epoxy resin, etc. used.

When the step of stacking the reinforcing material is performed in the semiconductor device manufacturing step, the heat resistance temperature of the reinforcing material, the temperature required for stacking, the temperature during the manufacturing step of the semiconductor device, etc. should be taken into consideration. Then you need to decide.

That is, a considerably high processing temperature is required when forming a thin film transistor on an insulating substrate. In particular, when a crystallized transistor is manufactured, the tendency is more intense than when an amorphous silicon thin film transistor is manufactured. The highest temperature among them is the temperature required for crystallization of silicon, and is usually 450 ° C. or higher. After that, the gate insulating film forming temperature is 200 to 300 ° C., the laser annealing temperature is room temperature to 300 ° C., and the ITO film forming temperature is 300 ° C.

Therefore, it is natural that the lamination process before the crystallization cannot be performed unless the heat resistant temperature of the lamination material and the temperature required for the lamination are higher than the temperature required for the crystallization of silicon. Usually, in a series of steps, the processing temperature and the heat resistant temperature of the material have to change from high temperature to low temperature. If this is observed, there will be no problem when it comes to stacking.

However, contrary to this, the laminated materials are often melted, peeled off, pinholes are generated, or are distorted, so that a reliable product cannot be obtained at all.

Among the above-mentioned reinforcing materials, those having a heat resistant temperature of 450 ° C. or higher include, for example, PTFE, polyimide, polyetheramide, glass, water glass, and ceramic substrates.

These materials may be used alone and laminated with an insulating substrate as shown in FIG. 1, or further, as shown in FIG.
The insulating substrate 110, the resin 112, and the glass 113 may be stacked in three layers, and further in five layers.

As means for laminating, a method of printing a resin paste or a resin solution on the insulating substrate by a printing method such as screen printing, offset printing or gravure printing or a spin coating method, a laminating method, There are a method of laminating an insulating substrate and a plate or sheet-shaped substrate by a vacuum laminating method, a roll pressing method, a method of directly bonding a resin or the like to the insulating substrate, and the like. All of them can use the conventional method.

As a result, as a result of laminating the insulating substrate forming the thin film transistor with the amount of the reinforcing material according to the present invention, the substrate strength was improved several times to several tens of times. As a result, there was no cracking, chipping, or warpage of the substrate during the process, and the process could be passed through stably. Naturally, the yield was improved, and the safety of workers was also improved.

Furthermore, not only the substrate itself, but the impact resistance after being used as a liquid crystal display or an image sensor is improved,
Even when a large-area liquid crystal panel was used, the panel did not bulge.

Examples will be shown below.

[0027]

EXAMPLES Example 1 In this example, a liquid crystal electro-optical device having a diagonal of 14 inches was manufactured and the present invention was carried out. Therefore, description will be added. In this example, glass was used as the insulating substrate on which the thin film transistor was formed, and polyetheramide and a glass substrate were laminated on the side of the substrate where the thin film transistor was not formed to improve the strength.

In this embodiment, a liquid crystal panel is constructed by forming a device using a high mobility type thin film transistor by the low temperature process having the constitution of the present invention with a constitution of 640 × 480 pixels. FIG. 3 shows how active elements are arranged on the substrate of the liquid crystal display device used in this embodiment. A manufacturing process showing the AA ′ cross section and the BB ′ cross section of FIG. 3 is drawn in FIG. AA 'cross section shows NTFT, B-
B'section shows PTFT.

In FIG. 4A, an inexpensive glass substrate 5 that can withstand heat treatment at 700 ° C. or lower, for example, about 600 ° C.
1. A silicon oxide film as the blocking layer 52 is formed on the substrate 1 by using a magnetron RF (radio frequency) sputtering method in an amount of 1000 to 3
It is made to a thickness of 000Å. Process condition is oxygen 100
% Atmosphere, film forming temperature 150 ° C., output 400 to 800 W,
The pressure was 0.5 Pa. The deposition rate using quartz or single crystal silicon for the target was 30 to 100 Å / min.

A silicon film was formed thereon by LPCVD (Low Pressure Vapor Phase) method, sputtering method or plasma CVD method. When forming by the reduced pressure vapor phase method, it is 1
450-550 ° C, which is low by 00-200 ° C, for example, 530 ° C
CVD of disilane (Si ₂ H ₆ ) or trisilane (Si ₃ H ₈ )
The film was supplied to the apparatus to form a film. The reactor pressure is 30-300
It was Pa. The film forming rate was 50 to 250 Å / min.
Threshold voltage (Vt
In order to control the concentration to be substantially the same as that of h), boron may be added during the film formation with diborane at a concentration of 1 × 10 ¹⁵ to 1 × 10 ¹⁸ cm ⁻³ .

When the sputtering method is used, the back pressure before the sputtering is set to 1 × 10 ⁻⁵ Pa or less, the single crystal silicon is used as a target, and the atmosphere is mixed with hydrogen in an amount of 20 to 80%. For example, argon is 20% and hydrogen is 80%.
The film forming temperature was 150 ° C., the frequency was 13.56 MHz, the sputter output was 400 to 800 W, and the pressure was 0.5 Pa.

When a silicon film is formed by the plasma CVD method, the temperature is, for example, 300 ° C., and monosilane (SiH ₄ ) or disilane (Si ₂ H ₆ ) is used. These were introduced into a PCVD apparatus, and high-frequency power of 13.56 MHz was applied to form a film.

By the above method, an amorphous silicon film having a thickness of 500 to 5000 Å, for example 1500 Å, is formed, and then heat treatment at a medium temperature in a non-oxide atmosphere is performed at a temperature of 450 to 700 ° C. for 12 to 70 hours. Needed.

After the heat treatment process requiring the highest temperature in this TFT manufacturing process, the substrate and the reinforcing substrate were laminated. The processing temperature after this crystallization step is 3
Since the maximum temperature is 50 ° C, a heat resistant temperature of 350 ° C is required. Water glass, polyimide, polyetheramide, or a ceramic substrate can be used as a material satisfying this requirement. In this example, HL-1100 polyetheramide manufactured by Hitachi Chemical was used.

The polyetheramide solution was printed on the back surface of the substrate 51 by a screen printing method, and prebaked at 110 ° C. As another film forming method, a spin coating method, an offset printing method, or the like can be used. Next, the glass substrate similar to the thin film transistor manufacturing substrate and the substrate were laminated by a laminating method. An outline of the laminator (laminating device) is shown in FIG. A glass substrate 169 is formed by laminating the substrate on which the thin film transistor 166 is formed on the lower plate 162 forming the first chamber 161 of the laminator, and the above-described resin-coated substrate 170 on which the thin film transistor is formed is arranged thereon. Overlaid. Regarding the order of arranging the substrates, the thin film transistor substrate may be arranged at a position in contact with the lower plate, but it is better to contact a more flexible surface in order to prevent damage to an important element portion.

Next, the upper plate is placed on the lower plate via the O-ring 167. 2 vacuum chambers on top plate
A partition plate 165 that divides into two is attached. The partition plate is
It is made of rubber or a thin metal film and can be easily deformed by the pressure difference between the two chambers. The first chamber 161 and the second chamber 164 are simultaneously evacuated by the first pump 163 and the second pump 168. After evacuation is performed until the ultimate pressure becomes 0.1 Torr or less, nitrogen gas is introduced into the second chamber through the gas introduction port 172 to reach atmospheric pressure. As a result, the first chamber and the second chamber
When the chambers are evacuated at the same time, there is no pressure difference between the partition plates and the partition plates maintain the middle. However, when the pressure difference occurs, the partition plates move to the lower pressure side to pressurize the substrate. At the same time, about 30 from the lower side of the lower plate 162
The resin printed on the substrate was completely cured by heating to 0 ° C.
As a result, no air was mixed in between the two substrates, and the two substrates could be bonded well. Finally, gas was introduced through the gas introduction port 171 to bring the first and second chambers to atmospheric pressure, and the laminated substrates were taken out. After stacking the substrates, the thin film transistor manufacturing process was further continued.

A silicon oxide film serving as a gate insulating film is formed on this to a thickness of 500 to 2000 Å, for example, 1000 Å. This was performed under the same conditions as the production of the silicon oxide film as the blocking layer. A small amount of fluorine may be added during film formation to immobilize sodium ions.

After that, an aluminum film was formed on the upper side. This is patterned with a photomask, and FIG.
I got (B). The gate insulating film 55 for the NTFT and the gate electrode portion 56 are formed, and the length in the channel length direction of both is 10
μm, that is, the channel length was 10 μm. Similarly, P
A gate insulating film 57 for a TFT and a gate electrode portion 58 are formed, and the length of both of them is 7 μm, that is, the channel length is 7 μm. In addition, both gate electrode portions 56,
The thickness of both 58 was 0.8 μm. In FIG. 4C, boron (B) was added to the source 59 and the drain 60 for the PTFT by an ion implantation method at a dose amount of 1 to 5 × 10 ¹⁵ cm ⁻² . Next, as shown in FIG. 4D, a photoresist 61 was formed using a photomask. NTFT
As source 62 and drain 63 for phosphor,
It was added by an ion implantation method at a dose amount of 5 × 10 ¹⁵ cm ⁻² .

After that, the gate electrode portion was anodized. L-tartaric acid was diluted with ethylene glycol at a concentration of 5% and the pH was adjusted to 7.0 ± 0.2 with ammonia. The substrate was immersed in the solution, the + side of the constant current source was connected, the platinum electrode was connected to the − side, and a voltage was applied at a constant current state of 20 mA, and the oxidation was continued until 150 V was reached. Furthermore, at constant voltage at 150V, add 0.1mA
Oxidation was continued until: Thus, the aluminum oxide layer 64 was formed on the surfaces of the gate electrode portions 56 and 58, and the gate electrode 65 for NTFT and the gate electrode 66 for PTFT were obtained. Aluminum oxide layer 64 is 0.3
It was formed to a thickness of μm.

Next, heat annealing was performed again at 600 ° C. for 10 to 50 hours. The source 62 and the drain 63 of the NTFT and the source 59 and the drain 60 of the PTFT were produced as N ⁺ and P ⁺ by activating impurities. Channel forming regions 67 and 68 are formed as semi-amorphous semiconductors under the gate insulating films 55 and 57.

In this manufacturing method, the order of impurity ion implantation and anodic oxidation around the gate electrode may be exchanged. By forming the insulating layer made of metal oxide around the gate electrode in this manner, the substantial length of the gate electrode is twice the thickness of the insulating film rather than the channel length.
The length was shortened by 6 μm, and the leak current at the time of reverse bias could be reduced by providing the offset region where no electric field is applied.

In this embodiment, thermal annealing is performed as shown in FIG.
(E) performed twice. However, the annealing of FIG. 4A may be omitted depending on the desired characteristics, and both may be performed by the annealing of FIG. 4E to shorten the manufacturing time. In FIG. 4E, an interlayer insulator 69 was formed as a silicon oxide film by the above-described sputtering method. The silicon oxide film may be formed by using the LPCVD method, the photo CVD method, or the atmospheric pressure CVD method. The interlayer insulator is 0.2 to 0.6 μm, for example 0.3 μm
It was formed to a thickness of m, and then a window 70 for an electrode was formed using a photomask. Further, as shown in FIG. 4 (F), aluminum is formed on the whole by sputtering,
After the leads 71, 73 and the contacts 72 were formed using a photomask, an organic resin 74 for flattening the surface was formed by coating, and electrode holes were again formed using a photomask.

ITO (indium tin oxide film) was formed by the sputtering method in order to make the two TFTs have a complementary structure and to connect the output terminal thereof to the electrode of one pixel of the liquid crystal device as a transparent electrode. It was etched with a photomask to form the electrode 75. This ITO
Was formed at room temperature to 150 ° C. and was annealed at 200 to 300 ° C. in oxygen or air. In this way, the NTFT 76, the PTFT 77, and the transparent conductive film electrode 75 are formed.
And were manufactured on the same glass substrate 51. TFT obtained
The electrical characteristics of PTFT are mobility 20 (cm ² / Vs),
Vth is -5.9 (V), and mobility is 40 (cm) with NTFT.
² / Vs) and Vth were 5.0 (V).

One substrate for a liquid crystal device was manufactured according to the method as described above. The arrangement of electrodes and the like of this liquid crystal display device is shown in FIG. The NTFT 76 and the PTFT 77 are provided at the intersection of the first signal line 40 and the second signal line 41. A matrix structure using such C / TFT is provided. The NTFT 76 is connected to the second signal line 41 via the lead 71 at the input end of the drain 63, and is connected to the gate 5
Reference numeral 6 is connected to the signal line 40 on which the multilayer wiring is formed. The output end of the source 62 is connected to the pixel electrode 75 via a contact 72.

On the other hand, in the PTFT 77, the input end of the drain 60 is connected to the second signal line 41 via the lead 73,
The gate 58 is connected to the signal line 40, and the output end of the source 59 is connected to the pixel electrode 75 via the contact 72 like the NTFT. This embodiment is constructed by repeating such a structure horizontally and vertically.

Next, as a second substrate, ITO (indium tin oxide film) was formed also on the substrate in which the silicon oxide film was laminated in 2000 liters on the soda lime glass by the sputtering method. This ITO is room temperature to 150
The film was formed at a temperature of ℃ and annealed in oxygen or air at 200 to 300 ℃. Further, a color filter was formed on this substrate to obtain a second substrate.

Then, a 6: 4 mixture of an ultraviolet curable acrylic resin and a nematic liquid crystal composition was sandwiched between the first substrate and the second substrate, and the periphery was fixed with an epoxy adhesive. The pitch of the leads on the substrate is 46 μm
Therefore, the connection was made using the COG method. In this embodiment, the gold bumps provided on the IC chip are connected by an epoxy-based silver-palladium resin, and the IC chip and the substrate are embedded and fixed by epoxy modified acrylic resin for the purpose of fixing and sealing. I was there. After that, a polarizing plate was attached to the outside to obtain a transmissive liquid crystal display device.

The manufacturing process of a thin film transistor is very long and complicated. It actually takes a lot of personnel and time.
If a normal substrate is used, cracks and chips will occur in each process, and the manufacturing yield will be reduced. However, by laminating the reinforcing material on the substrate, it is possible to improve the strength and make the substrate strong, and the yield can be improved, and at the same time, a highly safe semiconductor device is completed.

[Embodiment 2] In this embodiment, the lamination process is performed after the ITO formation process in Embodiment 1 is completed. In the case of a substrate that has completed this step, a heat resistant temperature of 100 ° C. is sufficient in consideration of the subsequent steps. In this example, an EVA 50 μm sheet widely used as an adhesive layer was used, and a PET 200 μm plate was used as a laminated material.

EVA and then PET were laminated on the surface of the substrate on which the thin film transistor was not formed, and a heating roll press was used. The substrate and roll were heated to 120 ° C. and passed between two rolls. Pressurized by roll is 2-3kg
It was / cm ² . The glass substrate, the EVA sheet, and the PET plate adhered well. This increased the substrate strength by a factor of about 5. Moreover, it was possible to reduce the weight.

[0051]

EFFECTS OF THE INVENTION By laminating a reinforcing material on the side opposite to the surface of a substrate on which a thin film transistor is formed, it is possible to improve the strength of the substrate and substantially reduce the weight of the substrate. In addition, by stacking a reinforcing material during the manufacturing process, it was possible to improve work safety and yield. By using this for liquid crystal displays and image sensors, it is possible to manufacture inexpensive and high-performance products.

[Brief description of drawings]

FIG. 1 shows a structure of a semiconductor device of the present invention.

FIG. 2 shows a structure of a semiconductor device of the present invention.

FIG. 3 shows an arrangement of an active matrix type liquid crystal electro-optical device in Example 1.

FIG. 4 shows a process of manufacturing an active matrix type liquid crystal electro-optical device in Example 1.

5 shows an outline of the laminator used in Example 1. FIG.

[Explanation of symbols]

110 Insulating substrate 111 thin film transistor 112,113 Reinforcing material

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 29/786 H01L 21/336 G02F 1/1333 G02F 1/1368

Claims (3)

(57) [Claims] 1. A first insulating substrate, a second insulating substrate, and a thin film transistor on one surface of the first insulating substrate.
And a multi-layered structure on the other surface of the first insulating substrate .
A semiconductor device having a reinforcing material , wherein the reinforcing material is an epoxy resin, an ultraviolet curable resin, or a nylon.
Ron, Polymethylmethacrylate (PMMA), Ac
Lil resin, PES, PET, polytetrafluoroethylene
(PTFE), polyimide, polyetheramide, P
A semiconductor device comprising EEK or EVA . 2. A method according to claim 1, wherein on the reinforcing material, a polarizing plate is provided, wherein the first insulating substrate and between the second insulating substrate, narrow nematic liquid crystal material and the resin A semiconductor device characterized by being held. 3. The semiconductor device according to claim 2 , wherein the resin is an ultraviolet curable acrylic resin.