JPS62254421A - Method and device for surface treatment - Google Patents

Abstract

PURPOSE:To contrive the improvement in the accuracy of impurity diffusion by supplying a raw material gas into a container containing a substrate to be treated and projecting light into the substrate to be treated and applying an electric field in vertical direction to the treated substrate to introduce ions into the material of the treated substrate. CONSTITUTION:A light 9 from a light source 6 passes an optical path 7 and it is introduced into a reactor 1 where a vapor above a surface of a substrate 3 to be treated is irradiated. Furthermore, a discharge tube 10 connected with the reactor 1 is coupled with a cavity 12 in a microwave waveguide 11 and a power from a microwave source 13 is supplied. From another end 14 of the discharge tube, a material gas or the like can be supplied. The reactor 1 comprises an inlet 15 for introducing a gas from other gas supply systems into the reactor. Also the reactor comprises an optical window 16 thereby introducing a light 18 from another light source 17 and irradiating the treated substrate with the light vertically. Thus, the introduced gas is ionized by light irradiation and the generated ions are attracted by an electric field and introduced into the substrate 3 to be treated. Accordingly, the impurity diffusion into a semiconductor can be done with high accuracy at low temperature with few damages.

Description

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

(Conventional technology) Conventionally, when forming a diffusion layer on a semiconductor surface.

First, a thin film containing impurity elements is formed on a semiconductor.

A method has been used in which the temperature of the sample is raised to 500° C. or higher and thermal diffusion is performed. It is difficult to control the diffusion profile of this thermal diffusion, and if the depth is shallow, diffusion in a minute area will not occur. As a means of solving this problem, formation of a diffusion layer by ion implantation has come to be performed, but impurity ions are implanted with an energy of several tens of KeV.

Because this process causes damage to the crystal, thermal annealing at several hundred degrees Celsius must be performed. Although the diffusion profile is good due to thermal diffusion,
It is extremely difficult to form a junction depth of 2000 A or less, which is currently becoming an increasing demand.

[Structure of the invention]

(Problems to be Solved by the Invention) The present invention has been made to eliminate the above-mentioned drawbacks.
The purpose is to provide a surface treatment method and apparatus that can perform impurity diffusion with high precision over a large area at low temperatures.

(Rounding Means for Solving Problems) In the present invention, a gas containing an impurity element is introduced into a reaction vessel, and ions containing the impurity element are generated by light irradiation. These ions are made incident on the surface of the substrate to be processed, and the ions are introduced into the interior of the substrate due to the electric field directed inward from the surface of the substrate.

In this case, the diffusion of impurities is suitable for creating a shallow case.

[Effect]

Since optical excitation is used, ions can be introduced at low temperatures, and since ions are introduced into the substrate perpendicular to the electric field, accuracy is high.

〔Example〕 The present invention will be described in detail below using one drawing.

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

1 is a grounded reaction vessel that can be evacuated. A sample stage 2 is placed inside the reaction vessel 10), and the substrate 3 to be processed is placed on the sample stage 2. In addition, sample stage 2
A power source R4 for applying an electric field is connected to , and this power source generates an electric field in the vertical direction on the surface of the substrate 3 to be processed.

Further, the sample stage 2 includes a device 5 for heating the substrate to be processed. Further, the reaction vessel 1 is connected to the ion emitting device 6 by a vacuum optical path 7, and the optical path 7 has a vacuum system 8 that performs differential pumping between the 6 vessel and the light source. The light 9 from the light source 6 deviates from the optical path and is introduced into the reaction vessel, and irradiates the gas phase above the surface of the substrate 30 to be processed. Furthermore, one reaction vessel 1 is connected to a discharge tube 10, and the four discharge tubes are connected to a micro waveguide 10.
It is coupled with cavity 12 in l.

Power is supplied from a microwave power source 13. Raw material gas etc. can be supplied from the other end 14 of the discharge tube. Further, one reaction vessel l has an inlet 15 for introducing gas from another gas supply system into the reaction vessel.

In addition, one reaction vessel has an optical window 16 and another light source 1.
Light 18 from 7 can be introduced into the reaction vessel.

Light can be irradiated perpendicularly to the substrate to be processed. In this manner, the introduced gas is ionized by light irradiation, and the generated ions are attracted by an electric field and can be introduced into the substrate 3 to be processed.

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 18 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 cause ionization, and either % or 10,000 may be used.

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

Figure 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 numbers. What is different from the case in FIG. 1 is that the ionizing light 9 is perpendicularly incident on the surface of the substrate 30, and there is also a temperature adjustment device gt5' that can raise and cool the substrate temperature. .

@2 A method for diffusing impurities using the apparatus shown in Figure 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 the excited gas is introduced into the reaction vessel. This excited gas is adsorbed onto the cooled substrate surface, and a thin film containing impurity elements is formed on the substrate surface.

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 one reaction vessel.

Ions generated on the surface are stimulated by an electric field directed from the surface to the inside.
By being drawn inward, a diffusion layer is formed inside the substrate. In this case, since the single element is irradiated onto the surface of the substrate, the single surface itself is also excited by the light, helping to diffuse the impurity element. In diffusion using this method, the electric field is not very strong, the temperature is low, and the depth is extremely shallow. The purpose of discharging the source gas in this method is to facilitate adsorption, and when using a gas with high adsorption capacity.

In particular, it is not necessary to perform discharge. For example, n in silicon
When adding type impurities, use PClB, P as gas.
OCl, PH, AsHl, A3CJ1, etc.
Examples of P-type sources include BC1s嘗BFs, B-goon I (・, etc.).

Further, in diffusion by this method, the diffusion element is drawn in the direction of the electric field, so that the diffusion layer rarely spreads in the lateral direction. The third factor is the diffusion r-shape when the diffusion of the present invention is performed on a sample having a pattern formed by a mask material. Since ions are drawn from the surface only in the light irradiated area and drawn into the interior by the electric field, a diffusion layer with good directionality can be formed. In the figure, 36 is a base, 37 is a mask material, and 38 is a diffusion layer.

39 indicates the irradiated light.

Figure 4 shows an explanatory diagram showing another embodiment of the invention.@In the method of irradiating light onto the surface of a substrate, an optical mask is placed in the optical path, the mask image is formed on the surface of the substrate, and the light is irradiated. A pattern forming method is used by transferring, in which diffusion or the like is performed only in a portion. @4 In the figure, 41 is an optical mask, 42 is a substrate, and 43 is a light, which is a schematic diagram showing that diffusion corresponding to a deer mask image is occurring.

FIG. 5 is an explanatory diagram showing the diffusion of only the portion irradiated with light. In the figure, reference numeral 51 indicates bright and dark parts of the optical image formed on the surface of the base 420, and the black parts are the dark parts.

Generally, the wavelength of light that causes ionization is short, 100 OA or less, when this light is used for pattern transfer.

It has small diffraction effects and is suitable for forming fine patterns.

Furthermore, since the generated ions are given directionality by an electric field, it has extremely excellent microfabrication properties.

〔Effect of the invention〕

According to the present invention, impurities can be diffused into a semiconductor at low temperatures, with little damage, and with high precision. In this diffusion method, diffusion can be performed at a low temperature, so that it is suitable for making a shallow contact and is suitable as a manufacturing process for forming a multilayer a-element. Moreover, by performing selective diffusion, the conventional manufacturing process can be significantly shortened, and manufacturing costs can be significantly reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the apparatus according to the present invention, FIG. 2 is a schematic configuration diagram showing the included embodiment, FIG. 3 is an explanatory diagram showing the principle of forming a diffusion layer, and FIG. 4 FIG. 1 is an explanatory diagram showing an embodiment of the method according to the present invention. Diagram M5 is a diagram for explaining the principle of oxidation and diffusion. DESCRIPTION OF SYMBOLS 1... Reaction container, 2... Sample 萱, 3... Substrate to be processed. 4...Power supply, 6...Ionization light source. Agent Patent Attorney Noriyuki Ken Yudo Takehana KikuoFigure 2Figure 8Figure 4Figure 5

Claims (16)

[Claims] (1) A raw material gas is supplied into a container that houses a substrate to be processed, and light is irradiated within the substrate to be processed, and an electric field is applied in a direction perpendicular to the substrate to be processed to induce ions into the substrate material to be processed. A surface treatment method characterized in that it is introduced into. (2) The surface treatment method according to claim 1, wherein the introduction of ions into the substrate to be treated is by diffusion of impurities. (3) The surface treatment method according to claim 1, characterized in that a diffusion layer is formed on the substrate to be treated using a gas containing at least a diffusion impurity element as the gas. (4) As the gas containing the impurity element, PCl_3, P
OCl_2, PH_3, AsCl_3 or AsH_
3. The surface treatment method according to claim 1, wherein n-type impurities are introduced into the silicon surface using silicon as the substrate to be treated. (5) As the gas containing the impurity element, BCl_3,
2. The surface treatment method according to claim 1, wherein B_2H_6 is used, silicon is used as the substrate to be processed, and P-type impurities are introduced into the silicon surface. (6) The surface treatment method according to claim 1, wherein one of Kr, Ne, He, and Ar is used as the inert gas. (7) Is a mask patterned with resist, oxide film, metal film, etc. on the substrate to be processed, or
Claim 1, characterized in that a pattern is formed by selectively performing a diffusion process on a substrate to be processed by forming a patterned image having a contrast between light and dark on the surface of the substrate to be processed. Surface treatment method described. (8) The surface treatment method according to claim 1, characterized in that an inert gas is added to the gas. (9) The surface treatment method according to claim 1, wherein at least one of Rr, Ne, He, and Ar is used as the inert gas. (10) 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 surface treatment apparatus comprising: means for irradiating near a surface; and means for generating an electric field in a direction perpendicular to the surface of the substrate to be treated to introduce ions into the material of the substrate to be treated. (11) The surface treatment apparatus according to claim 10, further comprising means for dissociating the gas in advance in a separate vacuum vessel connected to the reaction vessel under vacuum. (12) The surface treatment apparatus according to claim 10, 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. (13) The surface treatment apparatus according to claim 10, further comprising means for irradiating the light from a vertical direction. (14) The surface treatment apparatus according to claim 10, 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. (15) The surface treatment apparatus according to claim 10, further comprising means for raising the temperature of the substrate to be treated. (16) The surface treatment apparatus according to claim 10, further comprising means for forming a patterned optical image having a contrast of brightness and darkness on the substrate to be treated.