JPH0191425A - Method and device for surface treatment - Google Patents

Abstract

PURPOSE:To make it possible to progress more preferentially a reaction on the surface of a specified material than a reaction on the surface of other material by a method wherein the conditions (the selection of a wavelength, the regulation of a polarizing state and the choice of an incident angle) of light irradiation to the surface of a substrate to be treated, in which a plurality of materials coexist with one another, are optimized. CONSTITUTION:A surface treating device is provided with a substrate position adjusting unit 8, on which a substrate 7 to be treated is placed and which is used for adjusting the polarizing state and incident angle of light to be incided in the surface of the substrate 7, and a processor 9, which is used for calculating the incident angle of light suitable for selective reaction on the basis of the complex indexes of refraction of a plurality of materials coexisting in the substrate 7 and the constants of the wavelength of light to be utilized for photochemical reaction and so on in order to transmit a control signal to the unit 8. Moreover, by choosing the wavelength, polarizing state and incident angle of the light to be incided in the substrate surface, a significant difference is given to the effect of a treating speed and so on due to a material. Thereby, such a surface treatment that a reaction on the surface of a specified material is generated more preferentially than a reaction on the surface of other material becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for surface treatment of a substrate to be treated using a photochemical reaction, and particularly to a semiconductor or an insulator.

The present invention relates to a method for surface treatment of a substrate to be treated which is made of a plurality of materials having different refractive indexes such as metals.

[Conventional technology]

Plasma processes are currently widely used in the manufacturing process of semiconductor integrated circuits and the like, and have become an indispensable technology in etching, cleaning, and even deposition processes. In such a surface treatment method using a plasma process, since the substrate to be processed is placed in a discharge vessel, there is a problem in that the substrate is damaged by charged particles or high-energy particles. As a new surface treatment method for reducing such damage, a photoexcitation process that utilizes photochemical reactions is attracting attention and active research and development is underway. Research on surface treatment using such a photoexcitation process is not limited to a so-called dry process in which a substrate to be treated is placed in a reactive gas (vapor phase), but also a wet process.

Normally, in the fabrication of semiconductor integrated circuits, various materials (e.g. SiOx, resist, metal films such as AQ, etc.) are formed on a substrate to be processed (e.g. Sx) in the process of device fabrication. be done. When performing surface treatment on a substrate to be treated in which a plurality of these materials coexist, a process method that induces a surface treatment reaction with high selectivity for a specific material is essential. For example, in a system where the base is silicon and a 5iOz film is formed on the silicon, a dry etching process is performed to leave a 5iOz film with a specific pattern, and the rest is etched using the underlying silicon. A method is used to expose the In this case, the etching selectivity between silicon and 5iOz becomes an important factor, and it is necessary to select conditions under which 5ift is selectively etched and silicon is hardly etched. In other words, 5if2 of 1 surface
It is desirable to set conditions such that once the film is removed and the underlying silicon is exposed, the etching reaction will hardly proceed.

Usually, when performing such selective reactions, a specific material (
A reaction medium (for example, 5iOz) that reacts efficiently with other materials (e.g., silicon) but hardly reacts with other materials (such as silicon)
For example, in the case of a gas phase reaction, a method was used in which an etching gas (etching gas) was found and utilized through trial and error. Also, even after finding a reactive gas, for example in a plasma process,
Methods have been used to improve selectivity by optimizing conditions such as gas pressure during discharge.

-Research on the surface treatment method using a photoexcitation process, which is the object of the Rikiki invention, has only recently begun, and there have been very few results regarding the control of selectivity.

[Problem that the invention seeks to solve]

An object of the present invention is to perform surface treatment using a photoexcitation process, in which reactions occur preferentially on the surface of a certain material of a substrate to be treated in which a plurality of materials coexist over reactions on the surface of other materials. The objective is to provide a new surface treatment method.

Another object of the present invention is to change the trial-and-error approach that has conventionally been taken to find conditions for allowing a reaction to proceed with good selectivity on a specific material surface among substrate surfaces where multiple materials coexist. The purpose of this invention is to provide a method for causing reactions with good selectivity based on the results of theoretical studies.

Still another object of the present invention is to improve light irradiation conditions (selection of wavelength) on the surface of a substrate to be processed where a plurality of materials coexist.

By optimizing the polarization state (definition of polarization state, selection of incident angle), we aim to provide a new surface treatment method that allows reactions on the surface of a specific material to proceed preferentially over reactions on the surface of other materials. be.

[Means for solving problems]

The above purpose is to expose a substrate to be processed consisting of multiple materials with different complex refractive indexes to an atmosphere of a reaction medium such as a reaction gas or a reaction solution, and to generate a wavelength component that induces a photochemical reaction in the reaction medium. This is achieved by optimizing the light irradiation conditions.

In other words, in the optical excitation surface treatment method, the incident wave and reflected wave of the light irradiating the surface of the substrate to be processed interfere, so the light energy density formed on the surface of the substrate to be processed differs for each material. becomes. Therefore, in a system where multiple materials coexist, if you want to preferentially proceed with a reaction on the surface of a certain material, the light energy density at the surface of the material for which preferential reaction is desired will cause the desired reaction to proceed. In addition to selecting light irradiation conditions (wavelength of the irradiated light, polarization state, and angle of incidence of the light on the substrate to be processed) that greatly exceed the light energy density on the surface of the material that does not react with the light of the above wavelength, This is accomplished by selecting a reaction medium that induces the desired surface reaction.

[Effect]

Generally, when light is incident on a solid surface, the optical energy density at the surface is
It changes depending on the complex refractive index of the solid material at a predetermined wavelength of the incident light and the angle of incidence and polarization direction of the incident light. When predicting the optical energy density on this solid surface, the polarization plane of the incident light is parallel to the incident plane (the plane that includes the normal to the substrate surface and the direction of propagation of the incident light) (hereinafter referred to as TM It is convenient to consider the vertical case (hereinafter referred to as TE wave) and the perpendicular case (hereinafter referred to as TE wave). When the substrate surface is irradiated with light with such a defined polarization direction, how the light energy density on the substrate surface changes by changing the incident angle of the light is described in the inventors' earlier invention ( Published Patent Publication 1986-45
035).

If such a calculation method is applied to various materials with different complex refractive indexes, when light of a certain wavelength is incident in a certain polarization state (TE wave or TM wave), the surface of different materials will be different. It is possible to predict what kind of significant difference will occur in the optical energy density at Even when irradiated in a polarized state and at a certain incident angle, if the complex refractive index of material A and material B is different, the light energy formed on the substrate surface as a result of interference between the incident wave and the reflected wave. The density differs between the surface of material A and the surface of material B. Reaction medium 1 that causes a photochemical reaction with light of such a wavelength For example, when performing photo-excited dry etching, if light irradiation is performed while exposing the etching gas to the substrate, the amount of radicals generated on the surface of the material with high optical energy density will be: The amount of radicals generated is larger than that generated on the surface of a material with low light energy density, and the ratio of the amount of radicals generated is approximately proportional to the ratio of light energy density. the result,
The etching rate ratio between material A and material 9B is a value that depends on the amount of radicals generated on the surface of each material. Accordingly, there are systems in which the light of the above-mentioned wavelength components is not irradiated onto the substrate surface but passes through the reaction gas atmosphere in parallel to the substrate surface, and light of the above-mentioned wavelength components is irradiated directly onto the substrate surface without specifying the polarization state. The etching rate ratio will be different from that obtained with the system. In other words, light of the wavelength with a defined polarization direction is passed through a reactive gas (etching gas) without directly irradiating the surface of the substrate to be processed, and the surface is treated by reactive species (radicals) generated by a photochemical reaction. The reaction rates on the surfaces of the materials A and B obtained in the system are ^1 and Kal, and the reaction rate ratio of both is Ks (K 1 = K^1/KB1)
, and the reaction rates on the surfaces of the material [A and B] obtained when light of the wavelength is irradiated onto the surface of the substrate to be processed without specifying the polarization direction. Kn'(Kt' = ^1'/KB back'), and the material A obtained in a system in which light of the wavelength with the polarization direction defined is irradiated onto the surface of the substrate to be processed at a predetermined incident angle. The reaction rate on the surface of B is expressed as KAz and KH2
, the reaction rate ratio of both is Kz (Kz=KA2/KBz), the reaction proceeds in the relationship Kl (and or Kl' ) ) Kz or Kl (and or Kx') < Kz.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. 1st
The figure shows the basic configuration of an apparatus implementing the present invention. In the figure, 1 is a light source that supplies light involved in photochemical reactions, and 2
3 is a polarization plane rotator for adjusting the polarization direction of light by rotating the polarization plane of the light in a horizontal plane; 4 is an optical window; 5
is a reaction container; 6 is a reaction gas supply device; 7 is a substrate to be processed made of a plurality of materials with different refractive indices; 8 is a substrate on which a substrate to be processed 7 is placed; A substrate position WM adjustment device 9 for adjusting the direction and angle of incidence is selected based on constants such as the complex refractive index of multiple materials coexisting in the substrate to be processed and the wavelength of light used for photochemical reaction. a processing device for calculating the incident angle of light suitable for the reaction and transmitting a control signal to the substrate position 1d adjustment device 8;
0 is an exhaust device.

Figure 2 shows an example of the results obtained using the calculation method that is the basis of the present invention, and shows how the optical energy density on the substrate surface changes when sodium D rays (589 nm) are irradiated onto the metal surfaces of gold and tungsten. Shows how different it is. The horizontal axis of the figure is the angle of incidence of light (the angle between the incident light and the normal line)
, the vertical axis represents the optical energy density in arbitrary units9
The figure shows the results when TM waves and TE waves were irradiated, respectively.

As is clear from this result, for example, when both TE and TM waves are incident perpendicularly to the substrate (incident angle 20), the optical energy density on the gold surface is approximately three times that on the tungsten surface. It shows that it is high. However, when both substrates are irradiated with a TM wave of, for example, 589 nm at an incident angle of about 70°, the optical energy densities on the gold and tungsten surfaces become comparable.

Based on this result, if both substrates are placed in a medium that induces a photochemical reaction to light in the 589 nm wavelength range, the TE
- In a system where both substrates are irradiated with TM waves perpendicularly, the photochemical reaction progresses approximately three times as much on the entire surface as on the tungsten surface, whereas when TM waves are irradiated at an incident angle of 70°, both substrates surface This means that photochemical reactions proceed at approximately the same level.

Next, even if the substrate to which light is irradiated is the same, if the irradiation wavelength is different, the intensity ratio of the light energy density will be significantly different.This example shows that silicon is an important material in the manufacturing process of LSI. ing. 5iOz and silicon were selected as subjects, and the results are shown in FIGS. 3 and 4. Figure 3 shows how the light energy density formed on the substrate surface occurs when 185 nm light emitted from a low-pressure mercury lamp, which is often used in research on the optical excitation process of semiconductors, is incident on the 5iOz and silicon surfaces. This shows whether the change occurs. Figure 4 also shows the wavelength (
This figure shows how the light energy density formed on the substrate surfaces changes when both substrate surfaces are irradiated with light (248 nm). Looking at the results in both figures, we can see that the substrate to be irradiated (Si
It is clear that even if the substrate (in which O2 and silicon coexist) is the same, the behavior will be different if the wavelength of light is different. This difference in behavior is due to the different wavelength dependence of the complex refractive index of each material. In both figures, the horizontal axis is the incident angle of light, and the vertical axis is the optical energy density at the substrate surface. Similarly to Figure 2, Figure 0 shows TM waves and T waves.
The results obtained when irradiating with E waves are shown.

As is clear from this result, if 248 nm light (both TE waves and TM waves) is incident from the vertical direction (incident angle = 0), the optical energy density on the SiOx surface will be approximately three times higher than on silicon. I understand.

Also, if the TE wave is incident at an incident angle of 75'' to 80''.

Since the optical energy density on the silicon surface becomes almost zero, optical energy with a density ten times higher than that on the silicon surface is generated on the 5iOz surface. On the other hand, when the TM wave is incident at an incident angle of around 65'', it can be seen that, on the contrary, the optical energy density on the silicon surface is about twice as high as on the 5iOz surface.

On the other hand, as shown in Fig. 3, when the same substrate is irradiated with light with a wavelength of 185 nm, in the entire incident angle region
No significant difference was found in the optical energy density formed at the s and silicon surfaces.

As is clear from the figure, the 185 nm TM wave is
When incident at around 0°, the optical energy density on the silicon surface is approximately 1.5 times the value on the 5iOz surface, but the difference in optical energy density obtained with the system irradiating 248 nm light in Figure 4 is much smaller than.

Based on this result, assuming that the substrate to be processed is a substrate in which SiOx and silicon coexist, we will create a difference in the rate of photochemical reaction on the surfaces of both materials, and change the reaction rate on the surface of a specific material (for example, 5iOz) to another. 248 nm light is more suitable than 185 nm light. Furthermore, even with light of 248 nm, it can be said that it is a better condition for improving selectivity to make the TE wave incident at an incident angle of 70'' or more than to make the TM wave incident.

Based on these results, we installed a substrate to be processed in which silicon and 5iOz coexist in a reactive gas atmosphere (for example, CBrzFz or a mixed gas of CQ z + N Fa, etc.) in which a photochemical reaction is induced by light with a wavelength of 248 nm. if,
Photolysis products (for example, radicals such as CQ, F, etc.) corresponding to the above-mentioned light energy density ratio are silicon and Si
The result is that it occurs on the Ox surface.

The reaction rate between the generated radicals and the painting material (silicon and 5iOz) is different when the substrate surface is irradiated with natural light with no specified polarization direction, or even when the light with a specified polarization direction is directly applied to the substrate surface. The reaction rate is significantly different from that obtained when the substrate is passed in parallel without irradiation, so data on the complex refractive index of each material in the substrate to be surface treated is also available. By preparing the transition of the optical energy density on the surface of each material for each wavelength, it is possible to determine the optimal wavelength and polarization state of the light, as well as the optimal polarization state, depending on the desired surface treatment. The incident angle can be set, and the reaction medium that reacts with light of the corresponding wavelength can also be selected in advance.

FIG. 5 shows a second embodiment of the present invention, which is applied to a system in which a plurality of materials with different complex box refractive indexes are distributed in layers in the three-dimensional (perpendicular) direction of the substrate surface to be processed. In Figure 6 shown, 11 is silicon, 12 is an oxide film of 5 iOz existing on the silicon surface, and 13 is a TE wave light beam with a wavelength of 248 nm, which irradiates the substrate surface at an incident angle of about 80°. . As is clear from the results shown in Figure 4, this system has 5iOz
The light energy density at the surface is 10% lower than that at the silicon surface.
This corresponds to conditions several times higher. In such a system, 248 nm
When a halogen element-containing gas (for example, the above-mentioned CB rzF2 or CQt+NFs mixed gas) that reacts with light of a wavelength is introduced, the 5iOz layer is etched by halogen radicals generated by a photochemical reaction. Finally, the underlying silicon layer is exposed, but as is clear from the results in Figure 2, the optical energy density on the surface where the silicon is exposed is about 10 times lower than that of SiOx. Since the etching reaction is reduced to one-fold, the etching reaction is suppressed. As a result, the 5iOz layer can be selectively removed.

Strictly speaking, in this case, 5i()z due to photochemical reaction
This means that more than 10 times more radicals are generated on the surface than on the silicon surface, but this does not mean that the etching rates of the two materials are different by more than 10 times. This is because the reaction probabilities between the generated radicals and 5iOz or silicon are different. However, to perform selective etching of 5jOz,
Reaction medium (fifth) that induces a photochemical reaction with 248 nm light
In the system shown in the figure, it is important to select a reaction medium in advance so that the radicals generated as a result of the photochemical reaction react with 5iOz with good selectivity.

In the above embodiments, the case where a substrate to be processed is etched with multiple materials coexisting is mainly described.
The present invention is not limited to etching.
It can also be applied to VD film formation, doping, etc. In that case, selective C on the surface of a specific material among multiple materials.
It becomes possible to perform VD film formation and doping.

FIG. 6 is a partial configuration diagram of a device showing a third embodiment of the present invention, and shows a method of extracting light with a defined polarization direction using the Brewster reflection angle. A light beam 14 emitted from a light source 1 is reflected by a reflective object 15 with a refractive index n,
When the angle of incidence of the light beam 14 on the reflecting object 15 is θ, the condition that satisfies tanθ = n (at this time, the angle θ
is called the Brewster angle), the reflected light beam 16 becomes a polarized light component (TE wave) perpendicular to the plane of incidence.The light whose polarization direction is thus defined is passed through the optical window 4 to adjust the substrate position in the reaction vessel 5. By irradiating the substrate to be processed 7 placed on the apparatus 8, the apparatus configuration can be relatively simplified. There is a polarizing beam splitter as an element that extracts a specific polarized light component by utilizing the reflection at the Brewster angle.
It can be used in place of the reflective object 15 shown in the figure.

FIG. 7 is a partial configuration diagram of a device showing a fourth embodiment of the present invention, which is characterized by the installation of a plurality of light sources (not shown). As mentioned above, each material has its own wavelength dependence of its complex refractive index, so if the combination of multiple materials that make up the substrate to be processed is different, the photochemical reaction on the surface of the desired material will be different. The wavelengths of light suitable for propagation vary. Therefore, in order to carry out the present invention, it is desirable to prepare a large number of light sources that emit light of various wavelengths over a wide wavelength range, or to prepare a light source whose wavelength is variable over a wide wavelength range. The example of FIG. 7 shows a device suitable for such purposes. In the embodiment shown in FIG. 7, the reaction vessel 5 is provided with four optical windows (18° 20.22, 24), and the light beams 17, 19, 21.2 pass through each window.
3 can each irradiate the substrate 7 to be processed inside the reaction container 5. In the figure, for 17 light beams,
A state in which the substrate to be processed 7 is irradiated at a certain incident angle is shown. If the light source that irradiates the light beam of 17 is an excimer laser light source, just by replacing the laser gas,
193nm (ArF), 222nm (KrCQ), 2
48nm (KrF), 308nm (XeCQ), 4
Light of 83 nm (XeF) can be extracted. Further, as a light source that emits the light beam 19, an Nz laser, an A
r+laser.

By using a wavelength tunable laser such as a ruby laser or a YAG laser that excites a dye solution, it is possible to irradiate light with a desired wavelength in the range of 430 nm to 800 nm by selecting a dye. In addition, the light beam 21
High-pressure (approximately 10 atmospheres or more) gas Co is used as a light source that emits
If a t-laser is used, a desired pulsed laser beam can be irradiated in a region of 9.2 to 10.7 μm. In addition to laser light, light beam 2 is emitted from a composite lamp that integrates a deuterium lamp and a tungsten lamp.
3, it is possible to select light of a desired wavelength from the visible to the ultraviolet region. Furthermore, although the scale of the device is large, if an optical window is separately installed to introduce the orbital synchrotron radiation, it can have the function of irradiating light of a desired wavelength from soft x 1 m to the ultraviolet and visible regions.

FIG. 8 is a schematic diagram showing a fifth embodiment of the present invention, and shows an example in which the present invention is applied to a substrate to be processed in which a plurality of materials are distributed in a striped manner. To make the explanation easier to understand, the materials constituting the substrate to be processed shown in FIG.
Similar to the embodiment shown in the figure, silicon and 5 iOz are assumed to be 11 and 12, respectively. When the TE acid component light beam 13 of 248 nm is incident parallel to the stripes of the substrate to be processed at an incident angle of about 80'', the 5 inch
The optical energy density at the surface of s is ten times higher than that at the surface of silicon. Therefore, it is a reaction medium that induces a photochemical reaction in response to 248 nm light.

For example, if the substrate to be processed is exposed to a mixed gas of CB rzFz or C84 and NFa, more than ten times as many radicals will be generated on the 5ioz surface, etching the substrate. As a result, if the surface treatment reaction continues for a certain period of time,
Regular unevenness is formed on the surface of the substrate to be processed, which initially had a flat edge. However, in the embodiment shown in FIG. 8, since the light beam 13 is incident approximately parallel to the stripes formed on the substrate to be processed, even when unevenness is formed on the substrate surface, the sidewalls with the step Since no complicated light reflection occurs at the surface, the ratio of optical energy densities at the surfaces of silicon 11 and 5iOz12 is almost the same as the ratio at the beginning of the reaction.

Therefore, the etching reaction rate on both surfaces proceeds in the same manner as at the beginning of the reaction.

Although the above embodiments have mainly been described using gas as one reaction medium, cases in which the reaction medium is a liquid can also be treated in the same manner. In this case, in the reaction liquid which is one reaction medium, a photochemical reaction proceeds according to the significant difference in the light energy density distribution formed on each material surface of the substrate to be processed, as in the case of a gas. As an example of a system in which the reaction medium is a liquid, a substrate to be processed made of n-type GaAs is immersed in a KOH solution (a KOH solution diluted to 1/10) and exposed to He-No laser light (632 nm). )of,
Another example is etching by immersing the same substrate in a mixture of iodine (approximately 0.1%) and potassium iodide (approximately 1 to 10%) and irradiating it with Kr laser light (413 nm). . Another example of a system in which the reaction medium is a liquid is an example of a photoinduced electrode reaction. In this case, in a system where a plurality of materials coexist on the electrode surface, it is possible to increase the photoinduced electrode reaction rate on the surface of a specific material compared to the reaction rate on the surface of other materials. When the substrate to be processed is used as an anode, an oxidation reaction (e.g. elatin reaction: dissolution at the light irradiated area) occurs on the electrode surface, and when the processed substrate is used as a cathode, a reduction reaction (e.g. plating formation) occurs at the light irradiated area. (precipitation reaction) proceeds.

The present invention can also be applied to surface treatment reactions that involve excitation of a substrate to be treated by light irradiation. For example, in a system in which light is irradiated to a substrate whose anode is made of n-type GaAs as the substrate to be treated in the photo-induced electrode reaction, GaAs
Light with a wavelength that has energy greater than the bandgap energy of s and that is in accordance with the spirit of the present invention (
When light with a specific polarization state is irradiated at a predetermined angle of incidence, G
It can be used to wet-etch the light irradiated area by irradiating it with a wavelength that provides a condition in which the light energy density formed on the a As surface is sufficiently higher than the energy density formed on the surface of other materials. At this time, the light energy density on the GaAs surface can be selectively increased by irradiating light with a wavelength consistent with the spirit of the present invention in a predetermined polarization state and at a predetermined incident angle. As a result, since the energy of light at this wavelength is higher than the bandgap energy of GaAs, electron-hole pairs are formed in accordance with the light energy density on the surface of the GaAs substrate.

As described above, since the substrate to be processed whose constituent material is GaAs is connected to the anode, the anodic oxidation reaction progresses on the electrode surface depending on the amount of holes generated. Then, the etching reaction of GaAs proceeds according to the optical energy density described above.

Such a surface treatment reaction accompanied by excitation of the substrate to be processed is not limited to the surface reaction at the solid-liquid interface shown in the above-mentioned etching of GaAs, but can be similarly applied to reactions at the solid-gas interface.

Figure 9 shows an example applied to such a system.

In this embodiment, which shows the sixth embodiment of the present invention, a system in which p-type silicon 25 and 5iOz12 coexist is irradiated with TM waves of XeCQ excimer laser light (308 nm) at an incident angle of 65''. In Figure 4, a KrF excimer laser (2
The graph shows the change in optical energy density distribution on the surfaces of both silicon and 5iOz surfaces obtained when light of 48 nm) is incident on the surfaces of silicon and 5iOz. shows almost the same tendency,
As a result, the optical energy density on the p-type silicon surface is 5i
It is about twice as large as the Oz surface. In such a system, CQz+N
When the Fs mixed gas is introduced, about twice as many radicals are generated on the surface of the p-type silicon substrate as on the 5iOz surface. On the other hand, since the energy of XeCQ laser light (308 nm) is larger than the band gap energy of silicon,
Electron-hole pairs are generated on the surface of the silicon substrate.The generated electrons transfer to the radicals (cn) and then combine with silicon, resulting in volatilization as SiCΩX and furthermore SiFx, thereby promoting the etching reaction. On the other hand, the amount of radicals generated on the 5ins surface is smaller than that on the silicon surface, and the band gap energy of 5iOz is
Since the energy is greater than that of eCQ excimer laser light, the etching reaction of 5 iOz can be significantly delayed compared to the etching reaction of silicon.

FIG. 10 shows an improved version of the embodiment shown in FIG. 9, with the addition of a function to generate radicals outside the reaction chamber in order to further speed up the etching reaction. Etching gas (for example, CQz+NFδ) is introduced into the reaction chamber 5 from the tube 27 via the microwave discharge section 28 . In the microwave discharge section 28, the etching gas is activated and a large amount of radicals are introduced into the reaction vessel 5 containing the substrate 7 to be processed.

The target group ui7 is made of p-type silicon and 5i shown in FIG.
Assuming that 0z is included as a constituent material, the light beam 26
is X e CQ excimer laser beam (308
nm), and has an incident angle of 6 nm with respect to the substrate 7 to be processed.
Assume that irradiation is performed at 5'.

In this case, in addition to radicals being generated by the photoexcitation reaction, radicals generated outside the reaction vessel 5 are also supplied at the same time, which is effective in speeding up the reaction. However, in this example, since the radicals generated in the microwave discharge section are also poured onto the 5ift, the selectivity of the reaction is slightly lowered.

The example shown in FIG.
The present invention may be combined with a method of irradiating a substrate to be processed with a hot molecular beam, which is known in Japanese Patent Application No. 113775. In such systems, reactant gases (e.g. CQz, SFs t
CQx+NFs, etc.) passes through a tube heated by a heater, is converted into a hot molecular beam, and is irradiated onto the substrate to be processed.At the same time, light with a wavelength component that matches the purpose of the present invention is also polarized in a predetermined state and in a predetermined state. Since it is irradiated at an incident angle and activates the reactive gas, it is effective in promoting the surface treatment reaction of the substrate to be treated.

As mentioned above, the surface treatment targeted by the present invention is as follows:
Removal of materials from a surface (etching, cleaning) or deposition of materials.

(epitaxial growth) or change the physical and chemical properties of the surface (such as M coating, nitriding, etc., or doping).

[Effects of the Invention] According to the present invention, by determining the wavelength and polarization state of the irradiated light, as well as the incident angle, for a processing target substrate made of a plurality of materials having different complex refractive indices, The ratio of light energy densities at can be predicted in advance. Based on this result, there is an effect that the photochemical reaction rate on the surface of a desired material from among a plurality of materials can be made faster or slower than the rate on the surface of other materials.

As described above, according to the present invention, the conditions for the optimal surface treatment method can be found based on the results of theoretical examination, without relying on the trial-and-error approach that has conventionally been taken to find a surface treatment method with good selectivity. It is now possible to do so.

In order to effectively carry out the present invention and advance selective photochemical reactions on surfaces of different materials, the light energy density formed on the surfaces of contrasting materials must be at least doubled or halved or less. It is necessary to select light incident conditions (selection of wavelength, regulation of polarization direction, selection of incidence angle) that will open the beam. Furthermore, in order to make the selective photochemical reaction more remarkable,
The light energy density formed on the contrasting material surface is 10
It is desirable to select light incident conditions that open up by more than twice as much or less than 1/10.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the basic device configuration of the present invention, FIG.
Figures 3 and 4 are explanatory diagrams showing an example of the transition of optical energy density calculated from the theoretical formula that is the basis of the present invention;
The figure is an explanatory diagram showing a second embodiment of the invention, FIG. 6 is a partial configuration diagram of an apparatus showing a third embodiment of the invention, and FIG. 7 is a partial diagram of an apparatus showing a fourth embodiment of the invention. 8 is an explanatory diagram showing the fifth embodiment of the present invention, FIG. 9 is an explanatory diagram showing the sixth embodiment of the present invention, and FIG. 10 is an explanatory diagram showing the seventh embodiment of the present invention. FIG. DESCRIPTION OF SYMBOLS 1... Light source, 2... Polarizing element, 3... Polarization plane rotator, 4°18.20, 22.24... Optical window, 5...
- Reaction container, 6... Reaction gas supply device, 7... Substrate to be processed, 8... Substrate position YJ adjustment device, 9... Processing device, 10... Exhaust device, 11... Silicon , 12・
・・SiOx −13+ 14 +16.17,19
, 21, 23. 26... Light beam, 15... Reflective object, 25... P-type silicon, 27... Tube. 28...Microwave discharge section.

Claims (1)

[Claims] 1. In surface treatment using light energy, by selecting the wavelength, polarization state, and angle of incidence of the light, significant differences can be brought about in effects such as processing speed depending on the material. surface treatment method. 2. By exposing a substrate to be processed made of a plurality of materials having different complex refractive indexes in a reaction medium and irradiating the substrate with light having the above-mentioned wavelength, polarization state, and incident angle, different 2. The surface treatment method according to claim 1, wherein a significant difference is created in the treatment speed on the surface of the ivy material. 3. a reaction vessel in which the substrate to be processed is placed; a means for introducing the reaction medium into the reaction vessel; 1. A surface treatment apparatus comprising: means for irradiating a substrate surface. 4. A and B as the plurality of materials with different complex refractive indexes
In a photochemical reaction treatment method in which a substrate to be processed made of a material containing A and B is exposed to an atmosphere of the reaction medium, the surface of the substrate to be processed is not directly irradiated with light with the polarization direction defined. When the surface of materials A and B obtained in a system in which surface treatment is performed by irradiating the surface of the substrate to be treated with light of the wavelength component without specifying the polarization direction, The reaction rate ratios at
The reaction rate ratio on the material surface of A and B obtained in a system in which the light of the wavelength component is defined in the specific polarization state and is irradiated onto the surface of the substrate to be processed at the predetermined incident angle is K_2( (K_2=K_A_2/K_B_2), the photochemical reaction rate is controlled under any of the following conditions: K_1 or K_1'>K_2 or K_1 or K_1'<K_2. and the surface treatment method according to item 2. 5. The light of the predetermined wavelength is defined in a predetermined polarization direction and irradiated at a predetermined incident angle onto the surface of the substrate to be processed, which has a flat end surface in which a plurality of materials including A and B are spread in the same plane direction. A surface treatment method according to claims 1, 2, and 4, characterized in that: 6. A predetermined incidence of light of a predetermined wavelength with the polarization direction defined on the substrate to be processed, in which a plurality of materials including A and B are present in layers in a three-dimensional (perpendicular) direction of the substrate to be processed; The surface treatment method according to claims 1, 2, 4, and 5, characterized in that the irradiation is performed at an angle. 7. By irradiating the surface of the substrate to be processed with light having the specified wavelength, polarization direction, and incident angle, conditions are set in which the light energy density on the surfaces of different materials is more than double or less than half. A surface treatment method according to claims 1, 2, and 4 to 6, characterized in that: 8. Means for calculating the ratio of light energy densities formed on the surface of each material when irradiating the surface of the substrate to be processed with the light having the specified wavelength, polarization direction, and incident angle; 4. The surface treatment apparatus according to claim 3, further comprising means for controlling the angle of incidence of the light onto the substrate to be treated. 9. As the means for defining the polarization direction, the substrate to be processed is irradiated with light that has passed through a polarization plane rotator or a light beam separated by a Brewster angle of a reflecting object. The surface treatment method according to any one of the following items: 1, 2, and 4 to 7. 10. As the means for defining the polarization direction, the substrate to be processed is irradiated with light that has passed through a polarization plane rotator or a light beam separated by a Brewster angle of a reflecting object. The surface treatment apparatus according to the scope items 3 and 8. 11. Claims 3, 8, and 10, characterized by comprising a light source group or a variable wavelength light source capable of emitting plural types of light having wavelengths that induce the surface treatment reaction. Surface treatment equipment. 12. Surface treatment is performed on a substrate to be processed whose constituent materials are silicon and SiO_2 as the plurality of materials.Claims 1, 2, 4 to 7 , and the surface treatment method according to item 9. 13. The surface treatment according to claims 1, 2, 4 to 7, 9, and 12, characterized in that a gaseous reaction gas is used as the reaction medium. Method. 14. The surface treatment method according to claims 1, 2, 4 to 7, 9, and 12, characterized in that a liquid is used as the reaction medium. 15. Using a liquid as the reaction medium, and irradiating the surface of the substrate to be treated through an electrochemical reaction with light of the predetermined wavelength in a predetermined polarization direction and at a predetermined incident angle. Claims 1, 2, 4 to 7, 9, 12,
and the surface treatment method according to item 14. 16. The surface treatment apparatus according to claims 3, 8, 10, and 11, further comprising means for performing surface treatment through the electrochemical reaction. 17. The light having a wavelength component having an energy greater than the band gap energy of the material constituting the substrate to be processed is the light of the predetermined wavelength, and the light of the wavelength is further defined in the predetermined polarization direction to obtain the predetermined polarization direction. The surface treatment method according to claim 1, 2, 4 to 7, 9, and 12 to 15, characterized in that the irradiation is performed at an incident angle of . 18. Claim 1, characterized in that a laser beam is used as the light for irradiating the surface of the substrate to be processed.
Section 2, Section 4 to Section 7, Section 9, Section 12 to Section 1
The surface treatment method according to Items 5 and 17. 19. The surface treatment according to claims 3, 8, 10, 11, and 16, characterized in that a laser light source is used as the light source for irradiating the surface of the substrate to be processed. Device. 20. Claim 1, characterized in that a gaseous reaction gas is used as the reaction medium, and a second activation means is added in addition to activation by light irradiation as means for activating the reaction gas. The surface treatment method described in Items 1, 2, 4 to 7, 9, 12, 13, 17, and 18. 21. A gaseous reaction gas is used as the reaction medium, and a second activation means is added in addition to an activation means by light irradiation as a means for activating the reaction gas. The surface treatment apparatus according to item 3, item 8, item 10, item 11, and item 19. 22. Light of the predetermined wavelength is defined in a predetermined polarization direction and irradiated at a predetermined incident angle onto the surface of the substrate to be processed, in which a plurality of materials constituting the substrate to be processed have a striped structure. Claims 1, 2, and 4
Surface treatment method described in section. 23. When irradiating the surface of the substrate to be processed having the striped structure with the light of the predetermined wavelength in a predetermined polarization direction and at a predetermined incident angle, the direction of incidence of the light is with respect to the stripe. The surface treatment method according to claims 1, 2, 4, and 22, characterized in that the irradiation is performed under substantially parallel conditions. 24. Claims 1, 2, 4 to 7, characterized in that as the second activation means, a discharge means such as a microwave discharge or a hot molecule irradiation means is used. , Section 9, Section 12, Section 13, Section 17, Section 18
The surface treatment method according to Items 1 and 20. 25. Claims 3, 8, 10, and 11, characterized in that a discharge means such as microwave discharge or hot molecule irradiation means is used as the second activation means. , the surface treatment apparatus according to items 19 and 21.