JPS61196529A - Thin film forming apparatus - Google Patents

Abstract

PURPOSE:To avoid any formation of reactive product on windows of armour type sheet in case films are to be formed by photo CVD process by a method wherein the first armour type light transmissive shielding sheet and the second light transmissive shielding sheet are arranged between a reaction chamber and a light source chamber. CONSTITUTION:The first shielding sheet 10 arranged with multiple armour type ultraviolet ray transmissive shielding sheets as well as the second shielding sheet 10' outside the first shielding sheet 10 are formed into a structure to lead out non-productive gas (a gas producing no solid by reaction or decomposi tion) from the space 43 between the first and the second shielding sheets 10 and 10'. In such a structure, a light source chamber 40 may be arranged on a position exposed to atmosphere while preventing any needless reactive product from sticking on the surface of shielding sheets 10, 10'.

Description

Detailed Description of the Invention: Field of Application of the Invention The present invention is an apparatus for forming a thin film by photochemical reaction, and the present invention is an apparatus for forming a thin film by a photochemical reaction. The present invention relates to a CVD (vapor phase reaction) device having means for forming a film without coating it with oil or the like.

"Prior Art and its Problems" As a technique for forming thin films through gas phase reactions, a photo-CVD method is known in which a reactive gas is activated by light energy.

This method is superior to the conventional thermal CVD method or plasma CVD method in that it is possible to form a film at a low temperature and does not damage the surface on which it is formed.

When carrying out such a photo-CVD method, an example of the apparatus is shown in FIG.
), heating means (3) for the substrate, and a low-pressure mercury lamp (9) for irradiating light onto the substrate. Doping system (7
) is equipped with a mercury bubbler (13) for excitation of reactive gases and a rotary pump (I9) in the exhaust system (8). When a reactive gas such as disilane from the doping system is introduced into the reaction chamber (2) and a reaction product such as amorphous silicon is formed on the substrate (substrate temperature 250°C), the ultraviolet light transmitting portion of the reaction chamber is At the same time, a large amount of silicon film is also formed on the shielding plate (10), typically a quartz window. Therefore, in order to prevent the formation of a film on this window, apply Fomblin oil (an example of fluorine-based oil) (16) to this window.
coated with a thin layer of

However, although this oil has the effect of preventing the formation of a film on the window (10), it ends up being mixed into the film as an impurity. Furthermore, a reaction product is simultaneously formed little by little on this oil, and the thickness of the film formed is limited due to light absorption there.

Means for Solving Problems j In order to solve these problems, the present invention uses a plurality of shielding plates for transmitting ultraviolet light, which is a problem in the optical CVD method.
Armor plate (a device in which multiple narrow plates are attached to one chamber (reaction chamber) at a constant angle for ventilation)
A first shielding plate is disposed inside the shielding plate, and a light-transmitting second shielding plate is provided on the outside of the first shielding plate. The space between the first and second shielding plates (hereinafter referred to as a buffer chamber) is designed to prevent reaction products from accumulating on the upper surface of the first light-transmitting shielding plate and blocking ultraviolet light, or to prevent ultraviolet light from being blocked. ) to non-product gases (gases that do not form solids by reaction or decomposition, e.g. He+Ar+Hz, N21NH:llN2
The structure is such that O, O□ or a mixture thereof can be extracted.

With such a structure, the light source can be placed at an atmospheric pressure location. In addition, the pressure difference between the buffer chamber and the reaction chamber is such that the buffer chamber has a positive pressure and the reaction chamber has a negative pressure.
300μ, typically about 50μ). A second shielding plate outside the buffer chamber ensured a pressure difference between the light source, such as an excimer laser, located at atmospheric pressure and the buffer chamber.

r Effect j Due to these features, when trying to form a film by photo-CVD, no or very few reaction products are formed on the shroud-like window.

As a result, the irradiated light is sufficiently transmitted through the "shroud" window,
Sufficiently excite (including decomposition and reaction) reactive gases,
Reaction products may accumulate on the formed surface. At that time, the same reaction product also flies to the top surface of the transparent shielding plate,
This product is inhibited by the non-product gas discharged into the reaction chamber through the gap between the shutter plates and cannot adhere to the upper surface of the window.

Therefore, no reaction products are formed on the surface of the "armor plate-like" light-transmitting shielding plate (also called a window), and as a result, ultraviolet light is emitted with sufficient intensity into the reaction chamber indefinitely to excite the reactive gas. Let's continue. Then, a film can be formed to a sufficient thickness on the surface of the substrate. And the conventionally known 1
Instead of forming a film with a thickness of 100 to 1000 times (when oil coating is performed), it is repeated 500 to 50 times.
It is possible to form a film with a desired thickness of 0.000 people.

Further, in the present invention, after CVD, it is possible to fabricate films of the same type or different types on this film in the same batch by a plasma CVD method using the same reaction chamber.

Further, according to the present invention, unnecessary products deposited on the window due to an insufficient amount of non-product gas being discharged can be removed by plasma etching without exposing the reaction chamber to the atmosphere. Furthermore, since the apparatus of the present invention is an oil-free reaction system, the background level of vacuum could be kept at 10-'torr or less. A photo-CvD film can be formed by photoexcitation of a non-oxide reaction product such as a semiconductor film such as silicon, silicon carbide, silicon nitride, aluminum nitride, or metal aluminum.

``Example'' The present invention will be described in detail below using an example shown in FIG.

In FIG. 2, a substrate (1) having a surface to be formed is held in a holder (l), and is placed close to a halogen heater (3) (the upper surface of which is water-cooled (32)) on a reaction chamber (2). ing. A reaction chamber (2), a buffer chamber (43) through which an ultraviolet light source (40) passes, and a heating chamber (
11), each pressure was maintained at approximately the same degree of vacuum of 100 torr or less by the gap between the piping (12) and the first shielding plate. For this purpose, a non-product gas (here nitrogen, argon or hydrogen) that does not interfere with the reaction (28
) was supplied to the flow meter (21), and the valve (22) was supplied to the buffer chamber (43) and heating chamber (11). The gas was then led out (14) into the reaction chamber through the gap in the first "armor plate-like" light-transmitting shielding plate (10), thereby preventing unnecessary reaction products from adhering to the upper surface of the shielding plate.

Further, the light source (40) transmitted coherent ultraviolet light (60 nm to 300 nm) (41) from an excimer laser into the reaction chamber (2) through the second and first light-transmitting shielding plates.

Even if the light from this laser comes from a simple laser tube, in order to spread the light onto the irradiation surface, the inside (vertical direction in the drawing) is
1011II11, and it is effective to enlarge it to a width of 30 cm and irradiate it as pulsed light. This laser beam is applied to the upper surface of the object to be formed or its vicinity (1 point from the surface to be formed).
(within 0III), the film formation rate was increased.

The reactive gases in the thin film forming apparatus of the present invention include ammonia (NH3), nitrogen fluoride (NF3), silane gas (SinHzn-g) + silicon fluoride (Sing, 5
iF415izF6゜HzStFz) + Methyl77
It is possible to use hydrogen, argon or helium as a non-product gas when producing a semiconductor such as silicon as a reaction product. Nitride (nitride) Nitrogen or hydrogen was used to make aluminum (silicon, aluminum nitride).Hydrogen, argon or helium was used to make metallic aluminum.

The doping system (7) includes a valve (22) and a flow meter (2).
A reactive gas consisting of 1) and forming a solid product after the reaction was supplied from (23) to 26). The pressure in the reaction chamber is controlled via a control valve (17) using a turbo molecular pump (PG550 made by Osaka Vacuum) (18).
) was achieved by exhausting the air through a rotary pump (19).

When vacuuming the preliminary chamber, use another turbo molecular pump (18
”) and a rotary pump (19”) were used.

The film formation process used a load-lock method in which no pressure difference was created in moving the substrate from the preliminary chamber to the reaction chamber. First, the substrate (1) and holder (1″) are inserted and arranged in the preliminary chamber (4), and after vacuuming,
Open the gate valve (6) between the reaction chamber (2) which has been evacuated to 10-'torr or lower in advance,
Transfer the substrate (1) and holder (1゛) to the reaction chamber (2), close the gate valve (6), and separate the reaction chamber (2) and the preliminary chamber (
4) and were separated from each other.

After that, in order to prevent reaction products from adhering to the upper surface of the shielding plate due to backflow into the buffer chamber (43), first, non-product gas is introduced into the buffer chamber (43) from (28) at a flow rate of 100 to 500 cc/min. A heating chamber (11
) was also released. They are then exhausted through gaps between a plurality of "armor plate-like" shielding plates (10). Thereafter, reactive gas (31) was supplied from the nozzle (3o).

The heater (3) is a "day-position amplifier" type located above the reaction chamber (2) to prevent flakes from adhering to the surface to be formed and causing pinholes, and to prevent the flakes from adhering to the substrate (
1) was heated from the back side to a predetermined temperature (room temperature to 500°C) using a halogen heater.

Further, specific examples according to the present invention are shown in Experimental Examples 1 to 4 below.

Experimental Example 1...Ammonia was supplied from (25) at a rate of 50 cc/min and disilane was supplied from (23) at a rate of 8 cc/min as reactive gases on the silicon nitride film formation side, and the substrate temperature was 350.
℃. The substrates were four 5-inch diameter wafers. The internal pressure of the reaction chamber (2) was 3.0 torr.

Nitrogen, a non-product gas, was added at 200 cc/ from (28).
to prevent silicon nitride from adhering to the upper surface of the first "armor plate-like" shielding plate.

A 1,500-layer film was formed on the substrate in a 5-minute reaction.

The film formation speed was 7 minutes for 300 people. The present invention uses direct optical excitation using an excimer laser without using mercury vapor or the like. The variation in the five points of the coating was within ±10%.

Furthermore, in order to stop the reaction after this, a reactive gas (3
Stop the introduction of 1), evacuate the inside of the reaction chamber (2),
Furthermore, after stopping the introduction of the non-product gas (14) using the valve (22), the Dito valve was opened and the substrate on which the film was formed was transferred to the preliminary chamber.

In this example, after the film was formed, the reaction chamber was opened and the state of the silicon nitride biofilm on the upper surface of the "armor plate-like" shielding plate was examined. However, there was almost no biofilm. Of course “armor plate”
When the non-product gas was not led out from the gap in the shielding plate, a silicon nitride film of about 200 layers was formed on the shielding plate, completely blocking ultraviolet light. As a result, only a silicon nitride film with a thickness of 200 mm could be obtained on the surface of the substrate.

Experimental Example 2 Formation example of amorphous silicon film Disilane (SiJh) was supplied from (23) at a flow rate of 100 cc/min. Further, hydrogen was supplied from (28) at a flow rate of 200 cc/min to prevent it from adhering to the upper surface of the "armor plate-like" shielding plate. The temperature was 210° C. and the reaction chamber pressure was 3 torr. A film of 1,200 layers thick could be formed on the surface to be formed in 8 minutes of deposition.

Even if the same process is repeated, the same film thickness of 1000~1
We were able to get 200 people.

Experimental example 3... Formation example of aluminum nitride ^1 (C
H3) Methyl aluminum with s as a representative example (2
3) at a rate of 30 cc/min. (24), ammonia was diluted at 300 cc/min. Further, hydrogen was supplied from (28) at a rate of 50 cc/min. As a result, methyl aluminum was able to create an aluminum nitride film with a thickness of 1,300 mm. Film formation speed is 30 people/min (pressure 3 to
rr+ temperature 350°C). Other alkyl compounds such as ethylaluminum AI (CzHs):+ may also be used.

Experimental Example 3: Formation of metallic aluminum In Experimental Example 2, hydrogen was added at a flow rate of 200 cc/min from (28) to eliminate ammonia. Then, metal aluminum was deposited on the surface to be formed to a thickness of about 5,000 mm after 30 minutes of deposition. The rest is the same as in Experimental Example 2.

"Effects" As is clear from the above description, the present invention, when forming a film on a substrate, removes the unnecessary reaction-generated film on a light-transmitting shielding plate by using a plurality of "armor plate-like" shielding plates. By doing so, it can be removed more completely. Therefore, there is no need to use any oil on the top surface of the window. Therefore, it is difficult for impurities such as carbon to enter the coating, and the exhaust pressure can be set to a high vacuum of 10-7 torr, making it possible to produce an oil-free coating with high purity.

Furthermore, in addition to coating formation by this photo-CVD method, the same or different coatings are layered on top of this by a pair of electrodes (see Figure 2).
High frequency energy (13) is applied between the
, 56 MHz) by a plasma vapor phase method. In such a case, it is also possible to form a film using the photo-CVD method without causing any spatter on the surface on which it is formed, and then to form the same or another similar film on top of it using the plasma vapor phase method. That is, it was possible to form a film with good reproducibility without slowing down the film formation rate.

Furthermore, flakes adhering to the upper surface of the window or the reaction chamber were similarly removed by plasma etching, creating a completely oil-free environment in the reaction chamber, making continuous formation possible for the first time.

Although the present invention has shown experimental examples using silicon, silicon nitride, aluminum nitride, and metal aluminum, M(CHs) - that is, M as In, Sn,
A silicide such as MSiz may be produced by using Cr, Sn, Mo, Ga, or -, and introducing the metal M or an oxide gas into it. It is also effective to use a carbonylated product of iron, nickel, or cobalt as a reactive gas to form a film of iron, nickel, cobalt, or a compound thereof, or a compound of silicide and these.

In the experimental examples described above, dopants can be added at the same time when forming a silicon semiconductor. Also, the light source should not be a low-pressure mercury lamp (other light sources can also be used).

For example, excimer laser (wavelength 100-300 nm),
ArC1 (175nm), h (157nm)
, ArF (193nm), rcl (222n
m), KrF (249 nm) is typical. However, in combination with this, low-pressure mercury or the like may be irradiated from below.

In the present invention, the rate of film growth may be improved by passing the film through a mercury bubbler.

In the present invention, the "armor plate-like" shielding plate was disposed in the reaction chamber at a position sufficiently distant from the reaction section.

However, this distance may be determined by design. In addition, the excimer light was irradiated parallel to the substrate surface in order to increase the irradiation area. However, it goes without saying that it may be applied perpendicularly or diagonally perpendicularly to the substrate.

[Brief explanation of the drawing]

FIG. 1 shows a conventionally known photoexcited CVD apparatus. FIG. 2 shows a CVO device of the present invention.

Claims (1)

[Claims] 1. A light source for excitation of a reactive gas and a reaction chamber in which a substrate having a surface to be formed is disposed, and a first plurality of light sources are provided between the reaction chamber and the light source. 1. A thin film forming apparatus comprising: a light-transmitting shielding plate; and a second light-transmitting shielding plate, wherein the first light-transmitting shielding plate is arranged in the shape of a shroud. 2. In claim 1, non-product gas is led into the reaction chamber from between the first and second shielding plates so that reactive gases do not accumulate or are difficult to accumulate on the upper surface of the armor plate on the reaction chamber side. A thin film forming apparatus characterized by comprising means. 3. The thin film forming apparatus according to claim 1, wherein the first and second light-transmitting shielding plates are made of quartz.