JP3196231B2 - Hydrogen plasma processing apparatus and hydrogen plasma processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrogen plasma processing apparatus and method for a TFT or the like formed of a non-single-crystal semiconductor previously formed on an insulating film such as an insulating transparent substrate.

[0002]

2. Description of the Related Art There are many dangling bonds in a non-single-crystal semiconductor thin film such as an amorphous silicon thin film or a polycrystalline silicon thin film. For example, in the case of a polycrystalline silicon thin film, defects such as dangling bonds existing at crystal grain boundaries become trap levels for carriers and function as barriers for carrier conduction. (JYW Set
o, J. et al. Appl. Phys. , P5247 (197)
5)). Therefore, in order to improve the performance of the polycrystalline silicon thin film transistor, it is necessary to reduce the defects. (J. Appl. Phys., 53 (2), P11.
93 (1982)). As the method, a hydrogen plasma processing method is best known. The apparatus for performing this is described below with reference to the drawings. FIG. 3 shows a schematic diagram of a conventional apparatus. Substrate holder 3 supporting substrate 2 in vacuum vessel 1
A high-frequency electrode 11 is mounted in parallel with the earth via an insulator 12. The high-frequency electrode 11
Is connected to a high-frequency power supply 5 via a high-frequency matching circuit 6. After evacuating from the evacuation port 7, the substrate 2
Is heated to a predetermined temperature by a heater 9, a process gas containing at least hydrogen is introduced into the vacuum vessel 1 from a gas inlet 8, and a high frequency is applied to the high-frequency electrode 11 to generate a plasma to perform processing. This is a system that can be performed in a normal PCVD apparatus or the like, and is a processing method.

[0003]

However, in the above-mentioned prior art, since the counter electrode for generating plasma is separated from the substrate, the plasma density near the substrate, which will most contribute to the improvement of the speed of hydrogen plasma processing, In addition, it is difficult to control the impact energy of electrons and ions for accelerating the dissociation of hydrogen molecules attached to the substrate, so that the processing speed is low.

Accordingly, the present invention is to solve such a problem, and an object of the present invention is to provide a hydrogen plasma processing apparatus and a hydrogen plasma processing method having a high processing speed.

[0005]

A hydrogen plasma processing apparatus according to the present invention is a hydrogen plasma processing apparatus for performing a hydrogenation process for hydrogenating a polycrystalline silicon TFT layer formed in advance on a substrate. A substrate holder for supporting the substrate also serves as a high-frequency electrode in a vacuum vessel filled with gas, and a high-frequency power is applied to the high-frequency electrode to generate plasma, thereby performing a hydrogenation process.

Further, in the hydrogen plasma processing method of the present invention, a substrate holder supporting a substrate also serves as a high-frequency electrode in a vacuum vessel filled with at least hydrogen gas, and a high-frequency power is applied to the high-frequency electrode to generate plasma. Then, a hydrogen treatment for hydrogenating a polycrystalline silicon TFT layer formed in advance on the substrate is performed.

[0007]

According to the above configuration of the present invention, by applying high-frequency power directly to the substrate holder supporting the substrate, the density of charged particles (electrons and ions) near the substrate and the density of the charged particles entering the substrate are reduced. Since the energy and the like can be controlled, the plasma density can be increased and the energy for the reaction on the substrate surface can be increased.
As a result, the processing speed of the hydrogen plasma processing of the polycrystalline silicon TFT layer on the substrate can be increased.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic view of an embodiment of the plasma processing apparatus of the present invention. A substrate holder 3 for supporting a substrate 2 is mounted in a vacuum vessel 1 via an insulator 4. A high frequency power supply 5 is connected to the substrate holder 3 via a high frequency matching circuit 6. Such a simple configuration is also a great advantage of the plasma processing apparatus of the present invention.

In the processing method, the substrate is first heated by the heater 9. A high frequency cut filter is inserted in the current supply line of the heater 9 so as not to be affected by high frequency. When the temperature reaches a predetermined temperature, the vacuum vessel 1 is evacuated from the evacuation port 7 and a process gas containing at least hydrogen is introduced from the gas introduction port 8. A flow control and an exhaust speed control (not shown) are performed so that a predetermined pressure is obtained. While maintaining this state, high-frequency power is applied to the substrate holder 3 from the high-frequency power supply 5 via the high-frequency matching circuit 6. After the plasma is generated, the plasma parameters (electron density, ion density, radical density, electron temperature, plasma potential, floating potential, self-bias generated on the surface of the substrate or the substrate holder, etc.) are constant, or the parameters in a combination thereof. The RF power applied to the substrate holder is controlled in order to make the data (for example, the difference between the plasma potential and the self-bias) constant. Alternatively, the high frequency power itself is made constant.

A poly-SiTF formed on a quartz substrate by using the above-described apparatus and by using the above-described processing method.
T was hydrogenated. As processing conditions, the substrate temperature was 250 ° C., the gas was 100% hydrogen, and the gas pressure was 100 Pa. 0.0 per square centimeter for substrate holder
A constant high-frequency power of 1 W was applied. The processing speed was doubled as compared with the conventional method in which the same power was applied to the high-frequency electrode 11 (FIG. 3) for processing. Even in the conventional example, if the applied high frequency power is greatly increased, a double processing speed can be obtained, but at the same time, adverse effects such as generation of sputtering and shift of TFT characteristics due to plasma damage are exerted. Is preferably smaller.

Another embodiment will be described. FIG. 2 shows a schematic diagram of another embodiment of the present invention. Vacuum container 1 and substrate holder 3
It is the figure which looked at from above. The substrate holder 3 has a substrate 2 mounted thereon, and has a so-called car-cell type apparatus structure for mass processing in which the substrate 2 rotates about a concentric axis with the cylindrical vacuum vessel 1 as a rotation axis. In the conventional hydrogen plasma processing apparatus, a high-frequency electrode is further provided in a part of the cylindrical vacuum vessel 1, and high-frequency power is applied thereto to perform the hydrogen plasma processing. However, in that case, since the substrate 2 is exposed to the plasma only when passing in front of the high-frequency electrode (not shown), the total time of exposure to the plasma per one substrate 2 is short, so that a long processing time is reduced. It costs. According to the hydrogen plasma processing apparatus of the present invention, a high-frequency power is applied to the substrate holder 3 supporting the substrate 2, not only for the same reason as in the above-described embodiment, but also a plasma is generated around the polygonal substrate holder 3. Because the substrate 2 is constantly exposed to the plasma, the processing time can be greatly reduced. Further, the device structure is simpler than the conventional one.

[0012]

As described above, according to the present invention, the density of charged particles (electrons and ions) near the substrate and the density of charged particles entering the substrate can be improved by applying high-frequency power directly to the substrate holder supporting the substrate. Since the energy and the like of the charged particles can be controlled, the plasma density can be increased, and the energy for the reaction on the substrate surface can be increased.

As a result, there is an effect that the processing speed of the hydrogen plasma processing can be increased.

Further, the effect of simplifying the apparatus itself is also obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view of an embodiment of a hydrogen plasma processing apparatus according to the present invention.

FIG. 2 is a schematic view of another embodiment of the hydrogen plasma processing apparatus of the present invention.

FIG. 3 is a schematic view of a conventional hydrogen plasma processing apparatus.

[Explanation of symbols]

 1: Vacuum container 2: Substrate 3: Substrate holder 4, 12: Insulator 5: High frequency power supply 6: High frequency matching circuit 7: Exhaust port 8: Gas inlet 9: Heater 11: High frequency electrode

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kazuo Oike 3-5-5 Yamato, Suwa-shi, Nagano Seiko Epson Corporation (56) References JP-A-59-35016 (JP, A) JP-A-63 -66970 (JP, A) JP-A-4-313271 (JP, A) JP-B-1-27570 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) C30B 25/02 H01L 21/336 H01L 29/786 H01L 21/205 H01L 31/04-31/06

Claims (2)

(57) [Claims] 1. A hydrogen plasma processing apparatus for performing a hydrogenation process for hydrogenating a polycrystalline silicon TFT layer formed in advance on a substrate, wherein the substrate is supported at least in a vacuum vessel filled with hydrogen gas. A hydrogen plasma processing apparatus, wherein a substrate holder to be used also serves as a high-frequency electrode, and performs a hydrogenation process by applying high-frequency power to the high-frequency electrode to generate plasma. In a vacuum vessel filled with at least hydrogen gas, a substrate holder for supporting a substrate also serves as a high-frequency electrode, and applies high-frequency power to the high-frequency electrode to generate plasma, and a plasma is formed on the substrate in advance. A hydrogen plasma processing method comprising performing hydrogen processing for hydrogenating a formed polycrystalline silicon TFT layer.