JPH07118475B2 - Substrate surface treatment method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to the surface treatment of substrates using the resonant reaction of microwaves and magnetic fields.

In addition, the present invention is to perform an ultraviolet cleaning using a resonant reaction between a microwave and a magnetic field in the same surface of a substrate to be processed by plasma etching or a photochemical reaction with these (UV cleaning or photo The present invention also relates to a surface treatment method for performing cleaning).

Further, the present invention intends to automate and simplify the process of a semiconductor integrated circuit (hereinafter referred to as LSI).

"Prior Art" As a gas phase reaction processing apparatus, a plasma etching method and a photo etching method in which a reactive gas is activated by light energy are known. The former is characterized by high processing speed, but has the drawback of damaging the substrate surface. On the other hand, the latter has a characteristic that the processing speed is slow, but the surface is not damaged. Each of these is an independent and separate device, and there has been no attempt to use each feature to create a synergistic effect.

Further, when these light treatment and plasma treatment are integrated, the photon number of the ultraviolet light source is too strong, and even if the ultraviolet light source and the plasma light are simultaneously generated, the effect of the ultraviolet light is hardly observed. Therefore, there has been a demand for a means for generating strong ultraviolet light.

[Problems of the prior art] In addition, using a photoresist as a mask, anisotropic etching of the substrate surface (removing concave portions on the surface having irregularities by a chemical reaction into concave portions) is performed in the same apparatus before these steps. There was no attempt in advance.

"Means for Solving the Problem" The present invention provides a substrate having a selectively provided processing surface, and a non-product gas (a non-product gas () in the resonance region where resonance interaction of a magnetic field and an electric field occurs on the substrate. Introducing a gas that produces only gas itself even if decomposed or reacted) to generate plasma and perform plasma etching with ionic species of the reactive gas generated to remove the member to be etched having the treated surface The substrate surface treatment method is characterized by

Further, the present invention introduces a non-product gas for etching into a resonance region where resonance interaction between a magnetic field and an electric field occurs, and plasmaizes the gas, and the gas that has been plasmatized is selectively used on the treated surface. A substrate surface treatment method characterized by anisotropically plasma-etching the treated surface using a provided photoresist as a mask, and removing the photoresist with an oxide gas plasmatized in the resonance region. .

[Operation] The present invention uses the interaction of a magnetic field and an electric field to perform plasma etching of a processing surface, particularly anisotropic plasma etching of the processing surface and plasma ashing of a photoresist.

A non-product gas (a gas that itself produces only a gas even when decomposed or reacted) is introduced into the plasma generation space under the cyclotron resonance used for plasma etching or ashing.

As non-product gas for etching or ashing,
In the case of oxide gas, oxygen, nitric oxide (N ₂ O, NO, NO ₂ ), carbon oxide (CO, CO ₂ ), water (H ₂ O), carbon fluoride (NF) as a halide gas for etching (NF Typical gas is ₃ , N ₂ F ₆ ), carbon chloride (CCl ₄ , H ₂ CCl ₂ ), or a mixture of these with a carrier gas.

These non-product gases are activated in the resonance region that causes cyclotron resonance and are guided according to a magnetic field onto the substrate having the treated surface. Thus, the treated surface can be plasma etched by the active non-product gas.

Further, at the same time as the plasma etching or ashing step, or as a step after that, ultraviolet light cleaning (UV cleaning using ultraviolet light) or UV is also performed using ultraviolet light generated by utilizing the interaction of magnetic field and electric field. Ultraviolet light treatment such as etching or UV ashing may be performed in the same reaction apparatus.

When isotropic etching is to be performed on the processing surface, the wavelength of 185
Irradiate with m (ultraviolet light having a wavelength of 300 nm or less) of ultraviolet light to spread a uniform active gas over the entire surface of the treated surface. Room temperature ~ 50
By heating the substrate at a temperature of 0 ° C., it is possible to promote the etching of the unwanted matter on the formation surface of the substrate.

That is, anisotropic plasma etching is performed when plasma etching is performed only under ECR conditions, but isotropic etching is performed when plasma etching under ECR conditions and photo etching by ultraviolet light irradiation are used together. However, the usage can be used depending on the purpose.

INDUSTRIAL APPLICABILITY The present invention has, in the same device, means for generating ultraviolet light by utilizing the interaction between a magnetic field and an electric field, and means for producing a reactive gas that is made into plasma by using the interaction between another magnetic field and an electric field. It is particularly effective in this case.

The present invention will be shown below according to Examples.

Example 1 In this example, a substrate surface treatment method using an ultraviolet light treatment type microwave excited etching apparatus will be described.

The ultraviolet light generates an electron cyclotron resonance (also referred to as ECR) condition due to the interaction between the magnetic field and the electrode, and uses this resonance region to generate a strong ultraviolet light source. Then, the generated ultraviolet light is used to perform optical processing such as optical cleaning, optical etching, or optical ashing. Therefore, for the generation of UV light under ECR conditions, argon in this plasma space,
One or more species of deuterium, krypton, or mercury have been introduced and the resonant emission of these gases has been used to generate intense ultraviolet light.

Since the ultraviolet light source that uses electromagnetic energy is strong light, it removes the natural oxides that have formed on the surface to be formed, and also adsorbs hydrocarbons on the surface to be processed by the reverse flow of oil vapor from the vacuum pump. Can be prevented. In addition, during the UV cleaning, a material on the surface of the substrate on which oxygen is particularly disliked, such as GaAs III-V
In the case of compounds, a reducing atmosphere gas such as ammonia and hydrogen is used as a reactive gas for cleaning, and this gas is irradiated with ultraviolet light to be excited, or this is also used in combination with microwave excitation for ECR etching. . When the surface to be processed is an organic material such as photoresist, oxygen is introduced and activated to etch (ash) the processed surface.

Further, as an ultraviolet light source, by mixing mercury vapor into the resonance space utilizing the ECR condition to emit light with a resonance emission wavelength of 185 nm (intensity is preferably 10 mW / cm ² or more),
The excited state of the excited reactive gas can be maintained.

A translucent window was provided between the region where the ultraviolet light was generated and the region where the substrate having the processing surface was arranged to block the generation of the ultraviolet light of the gas and the exchange of the processing space. As a result, even if mercury, deuterium, or the like exists in the generation space, an arbitrary type of gas atmosphere or an arbitrary pressure can be set in the processing space.

Argon is a typical inert gas. However, Helium, Neon or Krypton may be used.

Furthermore, in the optical treatment processes such as optical cleaning using only ultraviolet light, optical etching, and optical ashing, the active surface for etching is subjected to electrophoretic migration (surface migration) to perform isotropic cleaning, ashing or etching. Utilizes the characteristics that promote

Therefore, later, as an example of the three types of processing, by using a photoresist provided selectively, anisotropic etching of silicon oxide on a substrate, a semiconductor or other film is performed by ECR etching (also referred to as shower etching). carry out. After that, the kind of the reactive gas is changed, and the reactive gas is activated while being irradiated with the ultraviolet light to remove only the photoresist. Further, in order to remove the residual substance of the photoresist and other contaminants, only ultraviolet light is irradiated to perform ultraviolet light cleaning or ashing. Thus, it becomes possible to selectively anisotropically etch the substrate and continuously remove the photoresist and clean the surface.

FIG. 1 shows an outline of an etching apparatus of ultraviolet light processing type microwave excitation.

In the drawing, a reaction space (1) is formed in a stainless steel container (1 '). This container has a substrate (10) take-out port (1 ″), a substrate (10) is provided in the lower part of a substrate holder (10 ′), and a halogen lamp heater (7) is provided on the back side thereof for heating. On the other hand, in the upper part of the container (1 '), the first space (2) (plasma for generating ultraviolet light) using the interaction of the magnetic fields (5), (5') for generating the ultraviolet light source and the electric field is provided. Generation space, that is, ultraviolet light generation space) and a magnetic field (5 ') that turns reactive gas into plasma,
(5 ″) and interaction of electric field are used. Second space (space for obtaining active gas for plasma etching, that is, plasma generation space) (2 ′) is provided. These first and second spaces are micro Electric field energy is supplied from the wave power source (3), the tuning device (4), and the quartz window (18).
This electric field energy is supplied to the second space (2 ') at the same time as the first space through the window (18). Then, in the first space, the mercury bubbler (11) is bubbled with argon from the doping system (13), and mercury vapor and argon gas are introduced from, for example, (24) to generate ultraviolet light. In the second space, argon or oxygen (for ashing) or NF ₃ (for etching) is passed from the doping system (13) through (25).
Etc. are introduced to generate a reactive gas that is turned into plasma.

Thus, ultraviolet light is generated in the first space (2), and the activation of the etching gas is simultaneously or before or after using the plasma in the ECR resonance region to activate the etching gas in the second space (2 ').
It has become possible to use plasma etching, plasma ashing, photoetching, or a combination thereof on the processing surface of the substrate arranged in the space (1).

Example 1 In this experimental example, the apparatus of Example 1 was used to perform anisotropic etching of silicon oxide, etching of a photoresist thereon, and further cleaning of the surface with ultraviolet light. A group of vertical cross-sectional views of this processing step is shown in FIG.

A substrate (10) having a silicon semiconductor (21) formed on a silicon semiconductor and a photoresist (22) formed thereon was used. Using this photoresist as a mask, ECR of silicon oxide
Anisotropic etching was performed using plasma, and as shown in FIG. 2 (B), anisotropic etching (23) of silicon oxide could be performed at an etching rate of 2500Å / min. That is, the microwave has a frequency of 2.45 GHz and is adjusted with an output of 30 to 500 W, for example, 200 W. Magnets (5 '), (5 ")
The resonance magnetic field strength of was 875 Gauss. The magnetic field (5) is zero, the pressure in the second space (2 ') and the reaction space (1) is 0.002 torr, and nitrogen fluoride (NF ₃ ) is used as a non-product gas for etching from (25). Supplied at 20 cc / min.

After this etching is completed, the magnets (5), (5 '),
A magnetic field of 875 Gauss was applied by (5 ″), and mercury and argon were added from (24) to the second space (2) to generate strong ultraviolet light of 185 nm. Further, oxygen was introduced from (25). Then, the photoresist (22) was removed by ECR plasma etching, ie, ashing, as shown in Fig. 2 (C), but the surface where the photoresist was not formed was carbonized. Since hydrogen (28) is apt to adhere, the plasma etching and the ultraviolet light generated in the first space (2) were simultaneously turned on, and the entire surface of the substrate was irradiated with the ultraviolet light.

After that, only the ultraviolet light cleaning is performed, so that the magnet (5 ″) is set to zero and only the magnets (5) and (5 ′) are added,
Ultraviolet light was generated in (2). At this time, the pressure in the reaction chamber (1) was set to 10 to 100 torr to promote the reaction of ozone or oxygen radicals with the remaining organic matter (27).

Thus, as shown in FIG. 2D, the photoresist was completely removed, and the selectively etched silicon oxide was able to be continuously subjected to anisotropic etching.

The object to be etched is not only silicon oxide, but also silicon nitride, silicon semiconductors, metal silicides, alloys, and other electronic application equipment, such as semiconductor integrated circuits, which require a manufacturing process to change reactive gases for etching. It can be carried out.

[Effect] As is apparent from the above description, the present invention is one in which the treated surface of the substrate is subjected to ECR plasma etching, plasma etching (ashing) of an organic substance, and then the surface is subjected to ultraviolet light cleaning.

In particular, since the etching gas is introduced into the ECR resonance space of the present invention to generate plasma, the activity of plasma conversion is extremely high. Therefore, selective anisotropic etching of the substrate can be performed using the photoresist as a mask.

In addition to this anisotropic etching means, it is possible to perform isotropic plasma etching by irradiating with ultraviolet light, and anisotropic etching and isotropic etching can be selectively used by the same plasma etching means. became.

In the present invention, the space for ultraviolet light generation and the space for plasma generation are continuously provided, and when performed by using the interaction between the magnetic field and the electric field, the ultraviolet light source does not deteriorate due to long-term use, and The intensity of ultraviolet light can also be adjusted by changing the intensity of the magnetic field.

Further, according to the present invention, it is possible to remove the filth that has been attached or formed in advance, or the filth that is newly adsorbed immediately after the formation of the film or in the reaction furnace, by ultraviolet light cleaning.

In FIG. 1, etching treatment was performed on the upper surface side of the substrate. However, it is needless to say that the drawing may be turned upside down, the substrate may be arranged on the lower side or the lateral side (vertical direction), and the light source and the resonator may be arranged on the upper side or the lateral side.

In the present invention, the etching gas is introduced into the resonance region of the ECR to activate the reactive gas, and the etching, ashing and cleaning of the ECR are shown as an example.

Ultraviolet light treatment and plasma treatment are also effective. Further, in the present invention, when the reaction space and the ultraviolet light generation space have the same pressure, when the gas used for the ultraviolet light generation means is expensive or toxic, or the ultraviolet light generation gas enters the reaction space by pinching of the magnetic field. The window (Fig. 1 (18)) may be removed if it is difficult to release.

[Brief description of drawings]

FIG. 1 shows an ultraviolet light processing type cyclotron resonance type processing apparatus in an embodiment. FIG. 2 is a vertical sectional view showing a process in the example. 1 ... Reaction space 2 ... First space for generating ultraviolet light 2 '... Second space for generating etching plasma 3 ... Microwave power source 4 ... Tuning device 5,5', 5 "... Magnet 9 Exhaust pump 10 Substrate 11 Mercury bubbler 13 Doping system

Claims (2)

[Claims] 1. A substrate having a selectively provided processing surface is provided, and a non-product gas is introduced into a resonance region where resonance interaction between a magnetic field and an electric field occurs on the substrate to generate plasma. A step of removing the member to be etched having the treated surface by performing plasma etching with the generated ionic species of the reactive gas, and an ultraviolet ray generated by using an interaction of a magnetic field and an electric field simultaneously with or after the step. A step of treating the surface of the substrate with the above-mentioned or other reactive gas excited, decomposed or reacted with light. 2. A non-product gas for etching is introduced into a resonance region where resonance interaction between a magnetic field and an electric field occurs, and the gas is converted into a plasma. The plasmaized gas is used to selectively provide the gas on a surface to be treated. Using anisotropic etching of the treated surface with the photoresist as a mask, removing the photoresist with an oxide gas plasmatized in the resonance region, and resonance interaction of a magnetic field and an electric field. And a step of performing ultraviolet light cleaning by irradiating the surface for treatment with ultraviolet light generated by the above method.