JPS61239620A - Plasma chemical vapor deposition (cvd) device - Google Patents

Abstract

PURPOSE:To enable to form an interface under the condition which does not differ much from the internal part of each layer when a semiconductor junction is formed by performing a plasma CVD is performed by a method wherein a substrate mask, with which the substrate is shut off from plasma, is operated based on the signal sent from an analytical means with which the activating seed in the plasma is measured. CONSTITUTION:The emitted light of plasma 3 is condensed by a quartz lens 4 through the quartz window 2 of a CVD device 1, the light is made spectral analyzing using a grating 5, it is received by a detector 6, its electric signal is passed through an amplifier 7 and an A/D transformer 8, inputted into an electronic computer, and the analysis of the signal is performed. The determination of the normal condition of plasma is given based on the result of said analysis. A substrate mask 11 is removed from a substrate 12 through the intermediary of a substrate mask transmission, and after a film-forming work is performed for the prescribed period, the substrate mask is covered on the substrate 12, and the film-forming process is completed. As the film is formed when plasma chemical reaction is in normal state, each layer and the interface can be formed uniformly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a plasma CVD apparatus, and particularly to a plasma CVD apparatus suitable for forming a semiconductor film i with excellent controllability and reproducibility of an interface portion.

[Background of the invention]

In conventional plasma CVD apparatuses, p-type, n-type, and intrinsic semiconductor layers are formed in separate reaction chambers for the purpose of doping profile control.

As a device for this noodle, for example, Kuwano et al.'s 'Prepa'
ration and pro-perty of
Amorphous 5ilicon Product
ed by ”(a Con5ecutiv
e * 5eparated Reaction Ch
amberMethod' : Japanese
Journal of Applied Ph-ysi
ca * Vol, 21 r No, 3 + p41
Examples include devices described and described in the document No. 5. However, although the conventional equipment is difficult to form the interface between each semiconductor layer, the conventional method
No consideration was given to □＼. Therefore, since the interface between each semiconductor layer is formed under unique conditions, which are important for junction formation, immediately after the start of the discharge and when the discharge is stopped, the interface between the semiconductor layers becomes structurally and physically different from the inside. Control was difficult.

[Purpose of the invention]

An object of the present invention is to provide a plasma CVD apparatus that can form a semiconductor junction by plasma CVD under conditions that do not significantly differ from those inside each layer at the interface.

[Summary of the invention]

In order to form the interface portion under conditions that are not very different from those inside each layer, it is necessary to increase the temperature by +11. It is sufficient that the film formation is not performed until the chemical reaction within the battery reaches a steady state, and that the film formation is stopped before the end of the discharge.

To do this, a movable mask is provided that isolates the substrate from the 11° plasma, and this mask covers the substrate until the chemical reaction in the plasma reaches a steady state, and then opens. , and the substrate may be covered again before stopping the discharge. This invention is here.

This method was developed with a focus on the above points, and includes an analysis means for measuring active species in plasma and a substrate mask that is operated by a j signal from the analysis means to shield the substrate from the plasma. It is designed to make the user perform the following steps. , 1° To detect when the chemical reaction within the plasma reaches a steady state, it is desirable to use a method that can successively monitor the state of the plasma, such as plasma emission spectroscopy or CAR8. Steady state is determined by measuring the signal intensity from chemical species generated by reactions within the plasma, and (1) when the signal intensity exceeds a certain value, (11) when the time derivative of the signal intensity becomes 0. , by measuring signals from multiple chemical species, measuring when the relative ratio of intensities reaches a constant value, and determining a steady state based on the results.

Wear.

The material for the substrate mask is preferably an insulator to maintain plasma stability, such as glass or quartz R811N4.
+ Ceramic materials such as SiCr alumina are suitable because of their heat resistance.

[Embodiments of the invention]

Hereinafter, as an embodiment of the present invention, an example will be described in which a chemical reaction in plasma is monitored using plasma emission spectrometry and a substrate mask is controlled.

The configuration of this embodiment is shown in FIG. In the figure, a plasma CVD apparatus 1 is provided with a quartz window 2. Plasma emission 3 coming out of the apparatus through this is collected by a lens 4, and after the light is separated by a grating 5, it is received by a detector 6. and convert it into an electrical signal. Next, this electrical signal is amplified by an amplifier 7, converted into a digital signal by an A-D converter 8, and input into a computer 9 to analyze the signal. Based on the results, the substrate mask power 10 is is operated to remove the quartz substrate mask 11 from the substrate 12. Then, the substrate mask 11 is placed over the substrate 12 on the edge where the film is formed for a certain period of time, and the film formation is completed, and the discharge is further stopped. In addition, in the figure, the code|symbol 13 shows a high frequency power supply, and 14 shows a gas supply system.

Next, an example of an algorithm for information processing by a computer in the electronic meter 1 when using the apparatus of this embodiment will be described.

Let us take as an example the case of film formation of amorphous silicon, which is a typical semiconductor produced by the plasma CVD method.

This will be explained with reference to FIG. Amorphous silicon is
Decomposing monosilane gas in plasma 1. (It is made by precipitating it as an active species on a substrate heated to around 200°C. At that time, the light emitted from the plasma beam 3 is generated by the decomposition of monosilane.
z42on09, H(e*655nm), H2,
80: This is made from ゛St%SiH, etc. Therefore, especially
・Emission from SiH and H with high intensity 4
Steady state was determined by focusing on light of 20 nm and 655 nm.

In a steady state, the time change in the intensity of 420 nm light is less than 10 degrees of the total intensity per second, and the intensity of 420 nm light and 420 nm light are
When the intensity ratio of the nm light was greater than 4:1, it was judged under the 1 condition. The film forming conditions at this time were a pressure of 15.5 Pa.
, high frequency output 80W, monosilane gas flow rate S CCms
The substrate temperature was 200°C. Note that the determination conditions differ depending on the film formation conditions, and therefore it is necessary to observe the plasma reaction in advance under the same conditions and set the ratio of the respective emission intensities in accordance with the 1 degree condition.

If the above judgment conditions are satisfied, a command is issued to remove the mask from the substrate, film formation is started, and time measurement begins at the same time.

Then, a predetermined time elapses 1. .

Then, the mask is closed, film formation is stopped, and then the discharge is stopped.

Note that, according to this embodiment, it is possible to obtain the effect of accurately controlling not only the interface portion but also the film thickness.

〔Effect of the invention〕

According to the present invention, when forming a film by plasma CVD, the film formed on the substrate does not contain components that are formed under conditions other than the steady state of the chemical reaction in the plasma. Uniformity within each layer increases, especially at the interface between layers.

The effect of improving the reproducibility and controllability of physical properties and characteristics can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of a plasma CVD apparatus according to the present invention, and FIG. 2 is a flowchart showing an example of a film deposition control algorithm when one of the apparatuses of the embodiment is used. , >-y'5XwcVD device・2...Quartz window, 3...Plasma emission, 4...Lens,
5-mounted grating, 6...detector,
7...Amplifier, 8...A-D converter,
9...Electronic computer, 10...Substrate mask power, 11
...Substrate mask, 12...Substrate, 13.
...High frequency power supply, 14...Gas supply system.

Claims (1)

[Claims] 1. Plasma C consisting of a vacuum container for performing vacuum discharge, a substrate stand provided inside the container, and a raw material gas supply system.
1. A plasma CVD apparatus comprising: an analysis means for measuring active species in plasma; and a substrate mask operated by a signal from the analysis means to shield a substrate from the plasma. 2. The plasma CVD apparatus according to claim 1, wherein the analysis means for measuring active species in the plasma is a plasma emission spectrometer.