JPS62254432A - Surface treatment and device therefor - Google Patents

Abstract

PURPOSE:To make the formation of an excellent thin film possible by a method wherein raw gas is introduced into a reaction chamber, ions are grown by projecting a light having the energy more than the ionizing potential of gas on the region located in the vicinity of the substrate to be treated, and said ions are made incident on the surface of the substrate to be treated using an electric field. CONSTITUTION:Oxygen gas is introduced from a gas introducing hole 14, the gas is electrically discharged by performing a microwave discharge, and the generated activating species of oxygen is introduced into a reaction chamber. Silicon is used as the substrate to be treated, and the temperature of substrate is set at about 300 deg.C. Also, an electric field is generated on the surface of the substrate to be treated, and the light having the photo-beam energy of about 15 eV or above is made to irradiate thereon. The light of a lamp using lean gas discharge or SOR and the like is used as the source of light 6. As a result, the substrate surface is oxidized, and an oxide film of high quality can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a surface treatment method and apparatus for forming a thin film used in the manufacture of semiconductor integrated circuits and the like.

(Conventional technology) Semiconductors and insulating films in the manufacture of semiconductor integrated circuits.

Metal thin film formation is an extremely important process.

For example, as a method for forming an insulating film, the St coated surface StO! Taking the method of forming a film as an example, the substrate is 800 to 100
Heating to 0°C, flowing O and gas in the furnace, the Si surface-! i
-The most common method is oxidation. A method of forming a thin film by oxidizing and nitriding the surface at high temperatures,
Furthermore, thin film formation methods based on thermal decomposition reactions, such as epitaxial growth of single crystal Si and vapor phase deposition of polycrystalline Sl, have been widely used in the past. However, in recent years, the miniaturization of devices has progressed, and the fine impurity profile is sometimes disturbed by high-temperature processes. This has led to the fact that the high-temperature process determines the limits of miniaturization. There is a strong desire to lower process temperatures.

In response to this demand, plasma CVD using discharge chemistry
The development of optical CVD techniques using light is underway. For example, 8i01.8i3N4, amorphous 8
Plasma CVD method such as i, 8i0. .

5isN, -Amorphous Si-Photoexcitation CVD of metal film
There are laws, etc. All of these methods can form films at low temperatures. However, thin films formed by plasma CVD have problems such as damage to the substrate to be processed due to irradiation with charged particles, and it is not possible to form a thin film of good quality. for example,
The 8i0 film formed by the plasma CVD method has poor electrical and physical properties compared to StO films formed by thermal oxidation, and cannot be used for gate oxide films of MO8 devices, etc., where a high quality film is required. I can't. The same can be said of other thin films (8'IN4, etc.). Furthermore, although thin films formed using the conventional photo-CVD method are formed at a low temperature of 300 to 400°C, the quality of the film is far inferior to that of thin films formed at high temperatures, similar to the plasma CVD method. There is a problem.

Furthermore, in the conventional thin film forming method, it is difficult to selectively deposit a thin film on the surface. Therefore, when forming a thin film pattern on the surface, a complicated method has been used in which a film is once formed on the entire surface, patterned with resist or the like, and then etched to form the pattern.

Simplifying the manufacturing process leads to lower manufacturing costs.

Highly desired. A method of forming a metal film by irradiation with light is a good selective deposition method of 9 degrees. However, in this case, the film is formed by condensing light and scanning the light beam, and the manufacturing throughput is poor at the first stage, and no reduction in cost can be expected.

[Structure of the invention]

(Problems to be Solved by the Invention) The present invention was made in order to eliminate the above-mentioned drawbacks, and its purpose is to be able to form a thin film of good quality at a low temperature, and to provide a substrate with a good 90° angle over a large area. A surface treatment method and device for forming a compound with a material.

The aim is to provide a

(Means for Solving the Problems) The gist of the present invention is to generate ions by optical excitation and to direct the ions by an electric field in order to form a thin film made of a chemical substance using the substrate material to be processed as the bottom material of the bath. The purpose of this method is to form a thin film by waiting for the properties to develop.

That is, a gas containing a source gas is introduced into a reaction vessel, and, for example, light having an energy higher than the ionization potential of the gas is irradiated near the substrate to be processed.

Thin film formation is performed by generating ions near a substrate to be processed and making the ions incident on the surface of the substrate to be processed using an electric field.

The electric field is not limited to the gas phase near the surface of the substrate to be processed, but may also be an electric field directed from the surface to the inside. In this case, particles adsorbed in the gas phase or on the surface are ionized and the ions are drawn from the surface to the inside. become.

Formation of a thin film here refers to oxidation, nitridation, etc. of the surface.

We will discuss the case of oxidizing and nitriding of mass and silicon. Oxygen or nitrogen molecules are ionized by light of 20 eV or more. By accelerating these rR elementary ions (0+ or 0+) or nitrogen ions (Nl+ or N+) by an electric field and making them incident on the silicon surface, the silicon surface is oxidized or nitrided, and the silicon surface is oxidized or nitrided. An oxide film or nitride film is formed on the surface. At this time,! I! element, nitrogen'1
There is also a method in which chlorine atoms react with silicon by mixing gVc salt atoms to form an etching product, and the etching product is reacted with oxygen or nitrogen ions to perform oxidation or nitridation. In this case, the chain degree of the substrate is 300
℃ or lower, and film formation can be performed at low temperatures. Further, the acceleration of ions due to the electric field must be suppressed to a level that does not damage crystallinity or the like due to ion incidence.

(Function) According to the present invention, the generated ions are attracted to the substrate to be processed, and a compound of the elements constituting the ions and the substrate material is formed.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1X1 is a schematic diagram of an apparatus illustrating an embodiment of the present invention.

1 is a grounded reaction vessel that can be vacuum pumped. There is a sample stage 2 inside the reaction vessel 1, and the substrate 3 to be processed is placed on the sample stage 2. In addition, sample stage 2
A power source 4 for applying an electric field is connected to the source 4, and this power source generates an electric field in the vertical direction on the surface of the substrate 30 to be processed. Furthermore, the sample stage 2 is equipped with a device 5 for raising the temperature of the substrate to be processed.
have. Further, the reaction vessel 1 is connected to the ionization light TA6 by a vacuum optical path 7, and the optical path 7 has a vacuum system 8 that performs differential pumping between the reaction vessel and the light source. 5'f: Light 9 from the source 6 is introduced into the reaction vessel 9 through the optical path 7, and irradiates the gas phase above the surface of the substrate 30 to be processed. Furthermore, the reaction vessel 1 is connected to a discharge tube 10 , which is coupled to a cavity 12 in a microwave waveguide 11 and supplies power from a microwave radio wave 13 . Raw material gas and the like can be supplied from the other end 14 of the discharge tube. Moreover, one reaction vessel l has a round inlet port 15 for introducing gas from another gas supply system into the reaction vessel.

Moreover, one reaction vessel has an optical window 16, and the other element [1
Light 18 from 7 can be introduced into the reaction vessel, and the light can be irradiated perpendicularly to the substrate to be processed.

A method of forming a silicon oxide film using the above-mentioned apparatus will be described. First, oxygen gas is introduced through the gas inlet 14 and discharged by microwave discharge, and the active species (excited species) of oxygen generated therein are introduced into the reaction vessel. Silicon (single crystal, polycrystal, or amorphous) is used as the substrate to be processed, and the substrate temperature is approximately 300°C. Further, an electric field is generated on the surface of the substrate to be processed, and light having a photon energy of about 15 eV or more capable of ionizing active species of oxygen is irradiated as shown at 9 in the figure. As the light source 6, a lamp using a rare gas discharge or light from an 80R or the like may be used. As a result, the surface of the substrate is oxidized and a high quality oxide film is formed. In this case, oxidation occurs even if oxygen is not excited by the discharge.

When oxygen is not excited by discharge, it is desirable that the photon energy of light is *20 eV or more. That is, this is because #1, which ionizes particles in the ground state, requires greater energy than ionization of excited particles.

The ionization referred to herein is not limited to ionization as a primary reaction due to absorption of light, but may be anything in which ions are generated as a result of light irradiation, such as ions being generated as a secondary reaction. Also.

When oxidizing, t! Oxidation can also be carried out by mixing chlorine with the R element. This is a method in which the etched surface of silicon is oxidized by mixing chlorine. In this case, oxygen,
It would be a good idea to discharge either of the chlorine or both. Moreover, it is not necessary to discharge both. However, as the light to be irradiated, it is sufficient that the light has energy to ionize at least either oxygen or chlorine.

In addition, in the above method, from the direction perpendicular to the substrate surface,
The light source 17 is an ultraviolet light source (H11 lamp).

By irradiating light using an excimer laser or the like, it is possible to excite the surface of the substrate or promote migration of particles on the surface of the substrate, and it is possible to form a higher quality oxide film. It also contains oxygen as a substitute for % oxygen gas, N! O, NO,, Co.

Co, O, etc. may also be used.

When forming a silicon nitride film, a method similar to the above-mentioned oxidation process can be used.

However, instead of the oxygen-containing gas, a nitrogen-containing gas may be used, such as N, , N, and O.

Any gas containing N, such as No, NH, etc., may be used.

Furthermore, as a method of introducing impurity elements into the oxide film, it is possible to form an oxide film containing a negative element by introducing a gas containing impurities into the introduction gas of oxygen or a mixture of oxygen and halogen gas (for example, chlorine). can.

For example, when adding P, PCj.

When attempting to add B by introducing a gas such as POCl, PH, etc., it is sufficient to introduce a gas such as BCIs=BtHs.

In the apparatus shown in Figure 1, we have mainly described the light 9 that irradiates above the surface of the substrate to be processed as the light that ionizes the gas, but the light 9 that irradiates perpendicularly to the substrate surface is the light that ionizes. It is clear that it is possible. Both of 9 and 18 may be lights that perform ionization, or either one of them may be used.

If the light 18 is for ionization, the light 9 is not particularly required. Furthermore, it is clear that even when the positions of the light source 6 and the light source 17 are exchanged, one surface treatment can be performed using the same concept.

FIG. 2 shows a schematic diagram of an apparatus for explaining another embodiment of the invention. The same parts as in FIG. 1 are given the same reference numerals. What is different from the case in FIG. 1 is that the ionizing light 9 is perpendicularly incident on the surface of the substrate 3, and that there is a temperature adjustment device 5' that can raise and cool the substrate temperature. .

First, the characteristics when the ionizing light is made incident parallel to the substrate surface and when it is made perpendicular to the substrate surface will be explained with reference to FIG. FIG. 3(a) shows the case where light is made parallel to the surface of the substrate. In the case of parallel incidence, ionization occurs in the gas phase and is attracted by the electric field ears from the substrate surface into the gas phase and impinges on the substrate surface to cause a reaction or deposition. However, as shown in Figure 3(b).

In the S case where light is incident perpendicularly to the substrate surface, there is ionization at the substrate surface in #1 of ionization in the gas phase. Particles ionized on the surface of the substrate are drawn into the substrate by an electric field generated inside the substrate.

Further, when light is incident on the surface of the substrate, the S reaction causes excitation of the surface of the substrate, resulting in effects such as activation of a reaction and promotion of migration. What is shown in Figure 2 is a device for irradiating light onto the surface of such a substrate.

In the figure, 31 is the base substrate, 32 is the surface reaction layer or deposit, and 3
3 is light that performs ionization, 33 is ion generated by the light, and 34 is neutral particle.

A method for forming a thin film and diffusing impurities using the apparatus shown in FIG. 2 will be described. First, the substrate in one reaction vessel is cooled, and a gas containing an impurity element is introduced from the gas inlet 14. This gas is discharged and excited and introduced into the reaction vessel.

This excited gas is adsorbed on the cooled substrate surface.

A thin film made of a substrate material containing impurity elements and gas constituent elements is formed on the surface of the substrate. At the same time, ionizing light is irradiated onto the adsorption layer to ionize impurity elements in the adsorption layer. An electric field is applied to the substrate to an extent that no discharge occurs within the reaction vessel. Ions generated at the surface are drawn inward by an electric field directed from the surface to the inside, thereby forming a diffusion layer inside the substrate. In this case, since the surface of the substrate is irradiated with light, the surface itself is also excited by the light, helping to diffuse the impurity elements. In diffusion using this method, the electric field is not very strong and the temperature is low, so the depth is extremely shallow. In this method, the purpose of discharging the raw material gas is to facilitate adsorption, and when using a gas with high adsorption capacity, it is not necessary to perform discharging. For example, when adding n-type impurities into silicon, the gas is PctIPH@, AsHl, AsC1B, etc., and the P-type impurity source is BCl3. B.P., B.H.
etc.

In the method of irradiating the substrate surface with light, an optical mask is placed in the optical path, and the mask image is condensed onto the substrate surface to form a thin film only on the light irradiated portions, using a pattern forming method by transfer. In Fig. 4, 41 is an optical mask;
42 is a substrate, 43 is a light beam, and is a schematic diagram showing that deposition corresponding to a mask image is occurring.

Figure 5 shows the state of diffusion, and 51 in Figure 1 is the base 42.
0 indicates the bright and dark parts of an optical image formed on the surface,
The black part is the dark part. FIG. 5 shows that oxidation or nitridation occurs only in the portions exposed to light. Generally, the wavelength of light that causes ionization is 100OA.
When this light is used for pattern transfer, the single diffraction effect and the like are small, making it suitable for forming fine patterns. moreover.

Since the directionality is determined by the generated ion Kffi field, the microfabricability is extremely excellent.

〔Effect of the invention〕

By using the present invention, a thin film can be formed at a low temperature.
APL-A? No. 71 Mt
y-shi J-11? )-k Th # JP
J/l f # Mackerel is of high quality. Furthermore, since the thin film is formed by the injection of ions, it has excellent microfabrication properties, and because it uses short wavelength light irradiation, it has excellent selectivity, making it suitable for use in VLSI manufacturing. It was.

Since slow ions are used, there is no damage to the substrate. Also by performing selective film formation.

The conventional manufacturing process can be significantly shortened, and manufacturing costs will be significantly reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram showing an embodiment of the apparatus according to the present invention, @2 is a schematic block diagram showing an embodiment of the same device, and FIG. 3 is an explanatory diagram showing the principle of photoionization reaction. FIG. 4 is an explanatory diagram showing one embodiment of the method according to the present invention, and FIG. 5 is a diagram for explaining the principle of oxidation. DESCRIPTION OF SYMBOLS 1... Reaction container, 2... Sample stand, 3... Substrate to be processed. 4...Electric @, 6...Ionization light source. Agent Patent Attorney Nori Chika Kikuo Takehana Figure 2, Figure 3

Claims (21)

[Claims] (1) Supplying a raw material gas into a container that houses a substrate to be processed, irradiating light inside the substrate and applying an electric field in a direction perpendicular to the substrate to attract ions to the substrate to be processed. A surface treatment method comprising: forming a compound of an element constituting the ion and the substrate material to be treated. (2) The surface treatment method according to claim 1, wherein the compound is generated by oxidation or nitridation. (3) An oxide film is formed on the surface of the substrate to be processed by using at least oxygen or a mixed gas of each gas containing at least oxygen and halogen as the gas. Surface treatment method. (4) The surface treatment method according to claim 3, wherein the substrate to be treated is single crystal, polycrystal, or amorphous silicon, and a silicon oxide film is formed. (5) The surface treatment method according to claim 3, wherein the substrate to be treated is a semiconductor material other than silicon. (6) Using Cl_2 as the halogen-containing gas,
4. The surface treatment method according to claim 3, wherein O_2 is used as the oxygen-containing gas, silicon is used as the substrate to be treated, and a silicon oxide film is formed. (7) As the gas, in addition to oxygen or a mixed gas of each gas containing at least oxygen and halogen, a gas containing impurities is added to form an oxide film containing impurities on the surface of the substrate to be processed. A surface treatment method according to claim 3, characterized in that: (8) As the gas, at least nitrogen or a mixed gas containing at least nitrogen and chlorine is used, and the surface of the substrate to be treated is single crystal silicon, polycrystalline silicon, or amorphous silicon, and silicon and nitrogen are used. 2. The surface treatment method according to claim 1, wherein a silicon nitride film is formed on the surface by the reaction. (9) The surface treatment method according to claim 1, wherein a gas containing at least an impurity element is used as the gas to form an impurity diffusion layer on the substrate to be treated. (10) As the gas containing the impurity element, PCl_3
, POCl_3, PH_3, AsCl_3 or As
10. The surface treatment method according to claim 9, wherein n-type impurities are introduced into the silicon surface using silicon as a substrate to be treated using H_3. (11) As the gas containing the impurity element, BCl_3
, B_2H_6, silicon is used as the substrate to be processed, and P-type impurities are introduced into the silicon surface. (12) A mask is patterned with a resist, an oxide film, a metal film, etc. on the substrate to be processed, or a patterned image having a contrast of light and dark is formed on the surface of the substrate to be processed, 2. The surface treatment method according to claim 1, wherein a pattern is formed by selectively performing a diffusion treatment on a substrate to be treated. (13) The surface treatment method according to claim 1, characterized in that an inert gas is added to the gas. (14) Kr, Ne, He, Ar as the inert gas
14. The surface treatment method according to claim 13, characterized in that at least one of the following is used. (15) A reaction vessel for storing a substrate to be processed, a means for introducing a gas containing a raw material gas into the reaction vessel, a means for irradiating the gas with light, and a means for applying an electric field in a direction perpendicular to the surface of the substrate to be processed. A surface treatment apparatus comprising a means for generating a gas and forming a compound of an element constituting the gas and the substrate material to be treated. (16) The surface treatment apparatus according to claim 15, further comprising means for dissociating the gas in a separate vacuum container connected to the reaction container in a vacuum state. (17) The surface treatment apparatus according to claim 15, further comprising means for perpendicularly irradiating the substrate to be treated with light in a wavelength range other than the light that causes ionization of the gas. (18) The surface treatment apparatus according to claim 15, further comprising means for irradiating the light from a vertical direction. (19) The surface treatment apparatus according to claim 15, wherein the electric field generated on the surface of the substrate to be treated is equal to or lower than a threshold electric field at which discharge occurs within the reaction vessel. (20) The surface treatment apparatus according to claim 15, further comprising means for raising the temperature of the substrate to be treated. (21) The surface treatment apparatus according to claim 15, further comprising means for forming a patterned optical image having a contrast between brightness and darkness on the substrate to be treated.