JPH08274035A - Thin film transistor manufacturing device - Google Patents

Abstract

PURPOSE: To provide a device, which can manufacture a thin film transistor of a constitution, wherein the interfacial level and interfacial level density between a semiconductor layer and a gate insulating film are low and the reliability of the electrical characteristics of the gate insulating film is high, and to use treat simultaneously a plurality of sheets of flat plate-shaped substrates, which are respectively constituted using the thin film transistor as its main constituent element and have sizes different from each other. CONSTITUTION: A vacuum through flat plate-shaped thin film formation device consists of a substrate sample feeding load lock chamber 1, a preliminary evacuation and preliminary heating chamber 2, semiconductor thin film formation chambers 5 and 17, an ultrahigh-vacuum heating surface treating chamber 13, insulating film formation chambers 18, 19 and 20, a cooling chamber 24 and a sample selecting/delivering load lock chamber 26. The formation device is a substrate holding jig capable of mounting a plurality of sheets of flat plate- shaped substrates for thin film transistor, which have sizes different from each other.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a low temperature of 600 ° C. or lower,
The present invention relates to a semiconductor and insulating film forming apparatus for manufacturing a surface field effect thin film transistor (TFT) on an insulating substrate such as glass or plastic. In particular, the present invention relates to a semiconductor device manufacturing apparatus that can be used for an active matrix type liquid crystal display device (hereinafter referred to as AMLCD).

[0002]

2. Description of the Related Art A semiconductor device having a thin film transistor (TFT) on an insulating substrate such as glass or plastic is an active matrix type liquid crystal display device (AMLCD).
Image sensors and the like are known. The MIS (metal, insulator, semiconductor) type surface field effect transistor is mainly used for the TFT used in these devices, and amorphous silicon is generally used as the semiconductor. Amorphous silicon TFTs are excellent in coping with the increase in the area of the device, and the OFF characteristics of the TFTs are also good. However, since the field effect mobility is low, it is difficult to apply it to a device having a large current capacity and a large capacitive load, for example, a large area AMLCD of 40 inches or more, or a drive circuit. In addition, there is a drawback that the characteristics deteriorate with the irradiation of strong light.

In recent years, when the evolution of AMLCD is required,
Attempts to overcome these weaknesses with polycrystalline silicon TFTs are active. Unlike amorphous, polycrystal possesses the regularity of atomic arrangement, so it can be expected to increase the mobility of charges and reduce the level density in the forbidden band. However, unlike single crystals, polycrystals contain a large number of lattice defects such as grain boundaries, twins, stacking faults, dislocations, etc., which hinder the transfer of charges and generate a forbidden band level. It provides a place for the generation, disappearance, or trapping of charges, which in turn deteriorates the TFT characteristics. In order to reduce this defect, for example, it is widely practiced to inject hydrogen atoms into polycrystalline silicon to cause unpaired electrons resulting from lattice defects to contribute to the bond with hydrogen atoms and to remove the above-mentioned defective factors. ing. This method is in principle identical to what is done with amorphous silicon, and therefore has the same advantages and disadvantages. That is, the bond between silicon and hydrogen atoms is relatively easily broken by irradiation of strong light,
It deteriorates the TFT characteristics.

On the other hand, what is important in the MIS type device is that the periodicity of atomic arrangement at the interface between the semiconductor and the insulating film is broken,
Alternatively, it is to reduce the density of electron and hole energy levels (interface level) in the forbidden band caused by local mismatch as much as possible. It not only lowers the operating voltage of the TFT, but also reduces the frequency of scattering of mobile charges by the electrostatic potential and increases the field effect mobility.

For the above reasons, in the development of a TFT using polycrystalline silicon, the device characteristics of crystal growth have been intensified to reduce the crystal grain boundaries and lattice defects, and the TFT characteristics have been improved. ing. However, the auxiliary effect for improving the TFT characteristics by the implantation of hydrogen atoms is still generally used, and an effective means for reducing the interface state density in a low temperature process of 600 ° C. or lower has not been found yet. is the current situation. As one of the causes, there are restrictions from the thin film manufacturing apparatus.

The first is a gate insulating film forming apparatus. Plasma CV is required because formation at low temperature (600 ° C or less) is required.
D is mainly used, and the method is a parallel plate electrode type. Therefore, the sample is placed adjacent to the plasma, and the gate insulating film is formed while being bombarded by the ions accelerated by the self-bias. This impairs the quality of the interface between the semiconductor layer and the insulating film and deteriorates the performance of the field effect transistor as described above. There is a remote plasma CVD method as a method for solving this problem. This is a method of shielding the ions by disposing the sample and the plasma at a distance equal to or more than the mean free path of the ions, or by applying a positive bias between the plasma and the sample to avoid the impact. However, if the distance between the plasma and the sample is increased with a parallel plate, the uniformity of the film thickness is impaired, and it is not suitable for a field requiring a large area such as a display. On the other hand, in the ion shielding method using the third electrode, electrons are accelerated in exchange for ion traps and the momentum impact is small, but the electrostatic effect is large and the damaging effect on the sample cannot be ignored.

The second is a semiconductor surface treatment apparatus. It is desirable that the gate insulating film be formed while keeping the semiconductor surface clean. One of the ideal ways to do that is IC
Although it is a thermal oxidation method found in the process, this method cannot be used when the semiconductor is polycrystalline silicon and the low temperature treatment at 600 ° C. or less is a condition. The reason is that defects in the polycrystal are preferentially oxidized, the interface is not flat, and the oxidation rate is slow and unsuitable for production. The second of the ideal methods is surface treatment in ultra-high vacuum. For example, 10 ⁻¹⁰ T
It is known that the heat treatment at 800 ° C. orr causes the surface of the single crystal silicon to exhibit a superstructure (structure unique to the surface), and a clean surface can be obtained. However, in the case of an AMLCD which is intended for a large-area substrate and is required to use a glass substrate having poor heat resistance, this method using a conventional device cannot be used.

On the other hand, in the manufacture of AMLCD, the size of a sample substrate called a mother substrate is fixed with respect to the completed manufacturing process, and a plurality of AMLCDs are obtained by cutting out from the mother substrate in the final process. . Therefore, it is impossible to discriminate according to the size of AMLCD during the process, and it is the current situation that a large mother board with a plurality of AMLCDs of the same size is integrated.

[0009]

[Problems to be Solved by the Invention] As described above, 6
In the development of a low temperature process polycrystalline silicon TFT of 00 ° C. or lower, improvement in TFT characteristics can be achieved by reducing the interface state density without depending on the effect of hydrogen atom implantation, and for example, 30 cm × 30 cm or more. The first problem to be solved by the present invention is to provide a thin film forming and processing apparatus capable of producing a large substrate. On the other hand, in the manufacturing process, different size A
It is a second problem to be solved by the present invention to provide a means capable of simultaneously processing a plurality of MLCD substrates.

[0010]

The problem of interface state in a silicon MOS (metal, oxide insulating film, semiconductor) type transistor is firstly how to remove a natural oxide film which is easily formed on a silicon surface. Come to a problem. That is,
The natural oxide film does not consist of silicon oxide having a stoichiometric composition, and it is considered that unsaturated bonds of silicon generate interface states and fixed charges at the interface. Secondly, it relates to impurities existing at the interface. This is mixed in after the silicon film is formed and before the oxide insulating film is deposited and formed, and is greatly affected by the handling of the sample. Thirdly, it relates to electrostatic impact due to ion bombardment and electron flow. This is a problem that must be taken into consideration when performing plasma processing.

These problems are caused by the large glass substrate 600
It is likely to occur because it is formed by a low temperature process in which it cannot be heated above ℃. Therefore, forming a clean and thermodynamically stable interface between silicon and an insulating film while maintaining a large substrate glass at 600 ° C. or lower is a basic problem to be solved. In order to solve this, we carry out from the chemical vapor deposition of the silicon thin film to its surface treatment in a high vacuum,
In particular, they have invented an apparatus which can use ultra-high vacuum, local heating of silicon by light, and chemical reaction of silicon and gas as the basic means of the surface treatment. Especially in chemical vapor deposition, the remote plasma method, which is less likely to be damaged by ions or electrons, was used.

A means for solving this problem is, for example, AMLC.
It should not be against D's productivity. Therefore, the height of the ultra-high vacuum surface treatment chamber and the chemical vapor deposition chamber is, for example, 30 c.
The flatness of m or less was set so that the glass plates could be continuously processed one by one, and the internal volume was minimized to shorten the time required to reach the ultrahigh vacuum and a predetermined atmosphere. Further, the lamp or laser installed in the reaction chamber shortens the treatment process time together with the local heating of the surface. Further, in order to cope with a large-sized substrate, the vapor deposition material supply port and the energy supply port are linear, and the large-sized substrate is made to reciprocate a plurality of times below or above the linear supply port. In order to process multiple AMLCDs of different sizes at the same time and to distinguish them by size during the process, the diagonal is 1.5m or more and the thickness is 1
A sample holder of 5 cm or less was used. The holding device is processed so that a plurality of AMLCDs of various sizes can be individually held, and after completion of the thin film forming step, the AMLCD is held.
Are separated into each size and used for a photo process, an etching process, and the like.

[0013]

The silicon surface has a very high activity with respect to oxygen, and silicon oxide is easily formed. This spontaneously formed oxide film (natural oxide film) is accompanied by oxygen defects, and must be eliminated as a device that deteriorates the characteristics of a MOS device such as a TFT. According to the present invention, a desired dielectric film such as silicon dioxide or silicon nitride can be formed on the surface of polycrystalline silicon without including this natural oxide film. Furthermore, a stoichiometric composition of silicon nitride (Si ₃ N ₄ ) is formed on a clean polycrystalline silicon surface by the action of ultra-high vacuum, light heating, and ammonia or nitrogen.
Layers can be formed. After that, a silicon dioxide film is chemically vapor-deposited to a desired thickness to produce a MOS-type polycrystalline thin film transistor having a small number of interface states, and a transistor having excellent characteristics as compared with the conventional one can be obtained.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (FIG. 1) is an overall view of the device of the present invention. 1,
Reference numeral 26 is a sample supply and storage device. The sample is transferred to the preliminary evacuation and heating chamber 2 by the supply device 1 and is evacuated to 10 ⁻⁷ Torr by the turbo molecular pump 3, and at the same time, it is heated to 500 ° C. by the built-in sample supporting and heating holder. In this example, aluminosilicate glass having a strain point temperature of 600 ° C. or higher was used as a sample substrate. The size is two 10 cm, 25 cm, and 1.5 cm diagonals, each consisting of one substrate with an aspect ratio of 4: 3,
There was one 16: 9 substrate each. After heating for 5 minutes, the gate valve 4 was opened and the CVD chamber 5 was opened by the transfer device commonly installed in each of the processing chambers 2, 5, 9, 13, 17 and 24.
Place the sample on. The substrate temperature is kept at 500 ° C., and the initial vacuum degree is also kept at 10 ⁻⁷ Torr by the turbo molecular pump 6.

Next, an active species of silane (mainly SiH ₃ system) is supplied onto the sample substrate by the remote plasma device 7.
At this time, the degree of vacuum is in the range of 0.01 Torr to 1 Torr and is determined by the desired film quality and deposition rate of amorphous silicon. During the amorphous silicon deposition, the sample is reciprocated multiple times under the linear remote plasma device by the transfer device. After a predetermined film thickness (1000 Å in this embodiment) is obtained, the gate valve 8 is opened and the sample is introduced into the heat treatment chamber 9. The atmosphere is maintained at high vacuum by the turbo pump 10. At this time, an atmosphere adjusting gas such as nitrogen, argon or hydrogen may be introduced, if necessary. The heat source 11 is a linear tungsten / halogen lamp light linearly condensed by a reflecting mirror. The substrate temperature is 500 ° C., and the transport speed and light intensity are determined so that the amorphous silicon is transformed into polycrystalline silicon by linear light irradiation. In the case of the present embodiment, the degree of vacuum is 10 ⁻⁷ Torr, the transport speed is 1 cm / sec, and the light intensity is 8.
The line width was 0 W / cm ² and 1 cm.

Next, the gate valve 12 is opened, and the sample is transferred and set in the ultrahigh vacuum processing chamber 13. Reference numeral 15 is a cryopump, which lowers the partial pressure of water, and achieves an ultrahigh vacuum of 10 ⁻⁸ Torr or more. Then, the flat lamp heating device 1
In 4, the polycrystalline silicon surface is instantaneously heated to a temperature of 800 ° C. or higher. In this embodiment, 1 × 10 ⁻⁸ Torr, 200
Light irradiation was performed for W / cm ² for 2 seconds. Substrate temperature is 50
0 ° C. In this process, the polycrystalline surface is cleaned. Subsequently, ammonia was introduced into the chamber up to 1 × 10 ⁻⁶ Torr, and light irradiation was performed again to bring the polycrystalline silicon surface to 800 ° C.
Heated for seconds. At this time, the polycrystalline silicon surface is thinly nitrided.

Next, the gate valve 16 is opened, and the CVD chamber 1
Transfer the substrate to 7. Reference numerals 21 and 22 denote turbo molecular pumps for maintaining the chamber 17 at a desired degree of vacuum. 18, 19,
Reference numeral 20 is a linear remote plasma generator. In this embodiment, 18 and 20 are 19 for forming a silicon oxide thin film.
Was used for forming a silicon nitride thin film. That is, in this example, a three-layer insulating film layer of silicon oxide, silicon nitride, and silicon oxide was formed. Substrate temperature remains at 50
It was 0 ° C.

After that, the gate valve 23 is opened, the sample is introduced into the chamber 24, and the turbo pump 25 is used for 1 × 10 ⁻⁶ Torr.
While maintaining the above degree of vacuum, the heater is turned off and the sample substrate temperature is cooled to room temperature. Storage sample for cooled sample 26
Then, it is stored according to its size.

(FIG. 2) has a diagonal of 1.5 cm to 25 cm
FIG. 3 is a plan view of a sample support substrate to which a plurality of AMLCD substrates can be mounted. 27 is the entire support substrate. 28 is an AMLCD substrate having a diagonal of 10 cm and an aspect ratio of 4: 3, and 29 is an ALCD substrate having a diagonal of 1.5 cm and an aspect ratio of 16: 9.
The MLCD substrate has a diagonal size of 1.5 cm and an aspect ratio of 4: 3 in 30, an AMLCD substrate having a diagonal length of 25 cm and an aspect ratio of 4: 3, and a diagonal length of 25 c in 32.
AMLCD substrate with m: 16: 9 aspect ratio, and 33
An AMLCD substrate with a diagonal of 10 cm and an aspect ratio of 16: 9 is mounted on each. FIG. 3 is a plan view of a sample support substrate for a large AMLCD substrate. Reference numeral 34 denotes the entire support substrate. 35 is A with a diagonal of 120 cm and an aspect ratio of 16: 9
The MLCD board is mounted. The sample support substrate shown in (FIG. 2) and (FIG. 3) is mounted therein according to demand.
The MLCD substrate size can be changed.

[0020]

According to the present invention, AM of high quality and high reliability
A polycrystalline silicon thin film transistor for LCD can be formed on a large-area substrate, and a plurality of AMLCD substrates of various sizes can be simultaneously produced in the same apparatus according to demand.

[Brief description of drawings]

FIG. 1 is a perspective view of an entire thin film transistor manufacturing apparatus.

FIG. 2 is a plan view of a substrate support for mounting an AMLCD substrate of various sizes.

FIG. 3 is a plan view of a large-sized AMLCD substrate mounting substrate support.

[Explanation of symbols]

1 ... Substrate supply load lock chamber 2 ... Preheating vacuum evacuation chamber 3, 6, 10, 21, 21, 25 ... Turbo molecular pump 4, 8, 12, 16, 23 ... Gate valve 5, 17 ... CVD chamber 7, 18 , 19, 20 ... Remote plasma source 9 ... Heat treatment chamber 11, 14 ... Lamp and focusing mirror 13 ... Ultra high vacuum surface treatment chamber 15 ... Cryopump 24 ... Cooling chamber 26 ... Substrate sorting load lock chamber 27, 34 ... AMLCD substrate Support substrate 28, 29, 30, 31, 32, 33, 35 ... AMLC
D board mounting location

Claims (5)

[Claims] 1. At least two vacuum chambers each having a planar shape and having a height shorter than a depth and a width, and capable of moving a sample and a heating holder between the chambers without exposing them to the atmosphere. A thin film forming apparatus capable of continuously forming a thin film by plasma, surface treatment by plasma, etching by plasma, and heat treatment. 2. The ultimate vacuum of the vacuum chamber is 1 × 10 ⁻⁹ Tor.
2. The thin film forming apparatus according to claim 1, wherein the thickness is equal to or greater than r, local heating of a flat plate sample by a linear lamp or a linear laser can be performed, and plasma active species can be linearly supplied. 3. A rectangular flat plate having a diagonal length of 1 m or more and a thickness shorter than the vertical and horizontal lengths, in which a plurality of rectangular sample substrates having various diagonal lengths can be mounted. A flat plate sample holding device used for the thin film forming apparatus according to claim 1. 4. A vacuum chamber having a planar shape whose height is shorter than its depth and width and capable of reaching an internal pressure of 1 × 10 ⁻⁹ Torr or less at 600 ° C., and a vacuum chamber installed in said vacuum chamber. The active molecules or active atoms excited by the plasma can be linearly supplied onto the flat sample, and the length of the flat sample is equal to or longer than one side of the flat sample. Source and active species supply system, a gas introduction system for supplying silane gas, oxygen gas, inert gas and the like into the vacuum chamber, and the vacuum chamber 10 at the time of gas introduction.
Exhaust system that can be kept below Torr and 60
A heat source capable of heating up to 0 ° C., a drive device capable of reciprocating the flat plate sample a plurality of times together with the heat source under a supply port for linearly supplying active molecules and atoms to the surface of the flat plate sample, and to the vacuum chamber. The flat plate type plasma thin film forming apparatus constituting a part of the apparatus according to claim 1, further comprising a carrying system for inserting and carrying out the flat plate sample and a preliminary exhaust chamber. 5. A flat shape having a height shorter than a depth and a width and a room pressure of 1 × 10 ⁻⁹ Torr at 600 ° C.
A vacuum chamber that can reach the following, a substrate holder / heater that can be heated up to 600 ° C. that is installed in the vacuum chamber, and a plate sample that is installed outside the vacuum chamber and scans in a plane parallel to the sample A linear light source lamp heater capable of annealing, emitting infrared rays that are efficiently absorbed by silicon, or a linearly shaped excimer laser;
It is characterized by having a hole for introducing a gas such as nitrogen, nitrous oxide, or ammonia into the vacuum chamber, and a transfer system and a preliminary exhaust chamber for inserting and ejecting a flat sample into the vacuum chamber. Item 2. An ultra-high vacuum flat plate silicon surface treatment apparatus constituting the apparatus according to item 1.