Fabrication system and a fabrication method of light emitting device

Abstract

An evaporation apparatus with high utilization efficiency for EL materials and excellent film uniformity is provided. The invention is an evaporation apparatus having a movable evaporation source and a substrate rotating unit, in which the space between an evaporation source holder and a workpiece (substrate) is narrowed to 30 cm or below, preferably 20 cm, more preferably 5 to 15 cm, to improve the utilization efficiency for EL materials. In evaporation, the evaporation source holder is moved in the X-direction or the Y-direction, and the workpiece (substrate) is rotated for deposition. Therefore, film uniformity is improved.

Description

[0001] 1. Field of the Invention[0002] The present invention relates to a fabrication apparatus having a deposition apparatus for use in deposition of materials allowed to be deposited by evaporation (hereafter, they are called evaporation materials). Particularly, the invention is an effective technique when organic materials are used as the evaporation materials.[0003] 2. Description of the Related Art[0004] In recent years, the research of light emitting devices having EL elements as self-luminous elements has been conducted actively. In particular, a light emitting device using organic materials as EL materials is receiving attention. The light emitting device is also called an organic EL display or an organic light emitting diode.[0005] In addition, the EL element has an anode, a cathode, and a layer containing organic compounds where an electric field is applied to obtain electroluminescence (hereafter, it is denoted by EL layer). Electroluminescence in the organic compounds h...

AI Technical Summary

Benefits of technology

[0017] In the invention, typically, the distance d between the substrate and the evaporation source is narrowed to 30 cm or below in evaporation, and the utilization efficiency for the evaporation materials and throughput are improved significantly. The distance d between the space between the substrate and the evaporation source is narrowed, and thus the size of the film-formation chamber can be small-sized. Downsizing reduces the capacity of the film-formation chamber. Therefore, the time required for vacuuming can be shortened, the total amount of impurities inside the film-formation chamber can be decreased, and impurities (moisture and oxygen) can be prevented from being mixed in the highly purified EL materials. According to the invention, a response to the realization of further highly purified evaporation materials in future is feasible.

[0018] In addition to this, the invention is characterized in that an evaporation source holder having a container sealed with an evaporation material is moved to a substrate at a certain pitch in a film-formation chamber. In this specification, a fabrication system having the evaporation apparatus equipped with the movable evaporation source holder is called a moving cell cluster system. A single evaporation source holder can hold two or more crucibles, preferably four or six crucibles. In the invention, the evaporation source holder is moved. Thus, when the movement speed is fast, a mask is barely heated. Therefore, deposition failure caused by a thermally deformed mask can be suppressed as well.

[0050] Moreover, even though the highly purified EL materials are provided by the material manufacturer, the traditional transfer operation in the light emitting device manufacturer always has the risk of mixing impurities not to keep the purity of EL materials, which has given a limit in the purity. According to the invention, the light emitting device manufacturer cooperates with the material manufacturer to seek the reduction in mixed impurities, which maintains the highly purified EL materials obtained by the material manufacturer. Accordingly, the light emitting device manufacturer can evaporate them without deteriorating the purity.

Problems solved by technology

The EL materials tend to be deteriorated extremely, which are easily oxidized and deteriorated by the existence of oxygen or moisture.

On this account, photolithography processes cannot be performed after deposition.

Moreover, because of the wide space between the substrate and the evaporation source, the deposition rate becomes slow, the time required to exhaust the inside of the film-formation chamber takes long time, and throughput drops.

In addition, in the traditional evaporation apparatus, the utilization efficiency for expensive EL materials is about one percent or below, which is extremely low to cause the fabrication costs of the light emitting device to be extremely high.

The EL materials are very expensive, and the unit price per gram is far more expensive than the unit price per gram for gold.

However, in the traditional evaporation apparatus, the utilization efficiency for expensive EL materials is low.

Downsizing reduces the capacity of the film-formation chamber.

It is also considered that the degree of sealing the container for storing the EL material is not enough.

More specifically, oxygen, moisture and other impurities are likely to be mixed, which are one cause of deteriorating the EL element.

However, when the pretreatment chamber is equipped with the gloves, the chamber cannot be vacuumed, and thus the operation is done at an atmospheric pressure.

Even though the operation is done in a nitrogen atmosphere, it has been difficult to reduce moisture and oxygen in the pretreatment chamber as much as possible.

However, the evaporation material is powder, and thus it is difficult to manufacture a transfer robot.

Therefore, it has been difficult to manufacture a total closed system allowing that the process steps from the step of forming the EL layer over a lower electrode to the step of forming an upper electrode are all automated to avoid impurities from being mixed.

Moreover, even though the highly purified EL materials are provided by the material manufacturer, the traditional transfer operation in the light emitting device manufacturer always has the risk of mixing impurities not to keep the purity of EL materials, which has given a limit in the purity.

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