JP2800210B2 - Method for manufacturing field effect transistor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a gate insulating film of an electro-optic effect transistor such as an integrated circuit and a flat display.

[Related Art] In recent years, flat displays such as liquid crystal displays are expected to be applied in various fields due to their high mobility, and are being actively studied. In the case of the application, enlargement of a display area and improvement of image quality are important issues.

Liquid crystal displays can be broadly classified into a simple matrix type and an active matrix type. In the case of the simple matrix type, since the number of pixels is increased by processing in a time-division manner, there is a limit to improving image quality. Therefore, great expectations are placed on active matrix liquid crystal displays.

However, in the case of the active matrix type, as the display area is enlarged and the number of pixels is increased, the signal delay due to the influence of the capacitance of the active device and the like becomes remarkable. is there. To solve this, improvement of the characteristics of the field effect transistor is an important issue.

A conventional general method of manufacturing a silicon dioxide thin film uses a normal pressure or reduced pressure CVD method using monosilane and oxygen or air as raw materials.

[Problems and Object to be Solved by the Invention] However, a field-effect transistor using a silicon dioxide thin film manufactured by a conventional method for manufacturing a silicon dioxide thin film as a gate oxide film or an insulating film is not suitable for use in a thin film. The phenomenon that the threshold voltage shifts and the temporal stability of the electrical characteristics is deteriorated due to the slight mixing of the alkali metal is observed, and it is extremely difficult to improve the reliability of the device.

Therefore, the manufacturing method according to the present invention solves the instability of the electric characteristics of the field effect transistor due to the mixing of alkali metal by using a compound containing silicon, a halogen and an alkyl group as a raw material for forming a silicon dioxide thin film. Things.

[Means for Solving the Problems] The present invention relates to a method for manufacturing a field effect transistor having a gate insulating film and a channel, wherein a substrate introduced into a reaction tube is heated so that silicon, a halogen and an alkyl group are contained in the reaction tube. By introducing a compound containing, a gate insulating film made of a silicon dioxide thin film is formed on the substrate.

The present invention provides a method for manufacturing a field-effect transistor having a gate insulating film and a channel, by heating a substrate introduced into a reaction tube and introducing a compound containing silicon, halogen, and an alkoxyl group into the reaction tube.
A silicon dioxide thin film is formed on the substrate.

[Operation] The alkali metal mixed in forming the silicon dioxide thin film of the gate oxide film is trapped at the interface between the silicon of the channel portion of the field effect transistor and the silicon dioxide of the gate oxide film to become ions, and a voltage is applied to the gate. Each time it moves in the silicon dioxide thin film, the electrical characteristics of the field effect transistor become unstable.

Since halogen reacts with an alkali metal to form a stable compound, when a compound containing a halogen is used as a raw material when forming silicon dioxide, the mixed alkali metal reacts with the halogen and stabilizes, so that the field effect transistor can be formed. Electrical characteristics become stable.

 Further, the same effect is obtained when used for an insulating film.

FIG. 1 shows an example of a manufacturing apparatus for realizing a manufacturing method according to the present invention.

Compound 1, which is a raw material and contains silicon, a halogen, and an alkyl group, is a liquid or a solid at room temperature, and is sealed in bubbler 2. By introducing an inert gas 3 to the raw material, the bubbler 2 can take out the raw material as a gas containing the raw material in the form of steam. The flow rate of the inert gas 3 to the introduced raw material and the temperature of the bubbler , It is possible to take out a certain amount of raw material. The thermostat 4 serves to keep the compound 1 containing silicon, halogen and alkyl group in the bubbler 2 at a constant temperature. Further, the flow control device 5 serves to keep the flow rates of the gas 3 inert to the raw material to be introduced and the oxygen 6 as another raw material constant. Oxygen 6 is sealed in a cylinder. These raw materials are introduced into a reaction tube 7 and react on a substrate 10 on a susceptor 9 heated by a heater 8 to form a silicon dioxide thin film on the substrate.

In addition, as the compound 1, which is a raw material and contains silicon, a halogen and an alkyl group, for example, the following compounds can be used, and their boiling points are as follows.

Although the case where chloride ions are used as halogens has been described above, it is clear that similar effects can be expected even when other halogen compounds are used, and these are also included in the scope of the present invention.

[Effect of the Invention] By introducing a compound containing silicon, a halogen and an alkyl group or an alkoxyl group into a reaction tube and forming a gate insulating film composed of a silicon dioxide thin film on a substrate, the halogen reacts with an alkali metal, A stable gate insulating film can be formed, and a highly reliable field effect transistor can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a manufacturing apparatus for realizing a manufacturing method according to the present invention. DESCRIPTION OF SYMBOLS 1 ... Compound containing silicon, a halogen, and an alkyl group 2 ... Bubbler 3 ... Gas inert to raw materials 4 ... Constant temperature bath 5 ... Flow control device 6 ... Oxygen 7 ... Reaction tube 8 ... Heater 9 ... susceptor 10 ... substrate

Claims (4)

(57) [Claims] In a method for manufacturing a field effect transistor having a gate insulating film and a channel, a substrate introduced into a reaction tube is heated to introduce a compound containing silicon, a halogen and an alkyl group into the reaction tube. Forming a gate insulating film made of a silicon dioxide thin film on the substrate. 2. Compounds containing said silicon, said halogen and said alkyl group include trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, methyldichlorosilane, dimethylchlorosilane, dimethylvinylchlorosilane, methylvinyldichlorosilane, methylchlorodisilane, Triphenylchlorosilane, methyldiphenylchlorosilane, diphenyldichlorosilane,
Methylphenyldichlorosilane, phenyltrichlorodilan, chloromethyldimethylchlorosilane, vinyltrichlorosilane, γ-chloropropyltrimethoxysilane, γ-chloropropylmethyldichlorosilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropylmethyldiethoxysilane 2. The method for manufacturing a field-effect transistor according to claim 1, wherein one of these compounds or a compound obtained by replacing chloride ions of these compounds with another halogen element is used. 3. A method for manufacturing a field-effect transistor having a gate insulating film and a channel, comprising heating a substrate introduced into a reaction tube and introducing a compound containing silicon, a halogen and an alkoxyl group into the reaction tube. ,
A method for manufacturing a field effect transistor, comprising forming a silicon dioxide thin film on the substrate. 4. The method according to claim 1, wherein said alkoxyl group is any one of γ-chloropropyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropylmethyldiethoxysilane or a compound thereof. 4. The method for manufacturing a field-effect transistor according to 3.