JPS63108723A - Apparatus and method for treating substrate surface - Google Patents

Abstract

PURPOSE:To simplify the treating process, by providing an ultraviolet light emitting means and a plasma etching means within a single apparatus so that UV cleaning is performed simultaneously with or after ashing of photoresist. CONSTITUTION:A substrate 10 is disposed on a holder 10' in a stainless container 1' and heated by a heater 7 from the rear thereof, while 185 nm ultraviolet light is applied through a quartz window 20 by a spiral low-pressure mercury lamp 6 at 10-100 mW/cm<2>. A non-product gas, which is supplied from an etching system 13 to a resonance space 2, is activated and excited by the irradiation of the ultraviolet light and plasma etch the surface of the substrate. Simultaneously, any contaminant adsorbed on the substrate is photochemically reacted as well as is cleaned by the ultraviolet light. Then, the supply of microwaves is stopped or decreased substantially and the surface of the substrate is irradiated with ultraviolet light only or ultraviolet light weakened relatively, whereby the surface of the substrate can be UV cleaned without damaging it since there is no or an insignificant amount of ion species. In this manner, the cleaning can be performed by using isotropic plasma etching by irradiation of ultraviolet light and anisotropic plasma etching (ashing), properly and independently from each other.

Description

Detailed Description of the Invention "Field of Application of the Invention J The present invention relates to optical cleaning (called UV cleaning or photocleaning because ultraviolet light is used) of the processing surface of a substrate using plasma etching and photochemical reaction in the same apparatus. The present invention also relates to an apparatus for performing etching and a surface treatment method using the apparatus.Furthermore, the present invention relates to anisotropic etching using electromagnetic energy, for example, cyclotron resonance, using a photoresist as a mask, in the same reaction system prior to the above-mentioned steps. The aim is to automate and simplify the process of semiconductor integrated circuits (hereinafter referred to as St).

rPrior Art J As a gas phase reaction treatment apparatus, a plasma etching method and a photoetching method in which a reactive gas is activated by light energy are known. The former has the feature of high processing speed, but there is a concern that it may damage the substrate surface. On the other hand,
The latter has a slow processing speed, but has the characteristic that it does not damage the surface.

Each of these is an independent device, and there has been no attempt to create a synergistic effect using their respective features.

In addition, there has been no attempt to perform anisotropic etching of the substrate surface using a photoresist as a mask in the same apparatus prior to these steps.

In order to solve these problems, the present invention performs plasma etching of the surface to be formed, particularly plasma ashing of the photoresist, and further irradiates ultraviolet light at the same time as this step or as a subsequent step. The UV cleaning (cleaning using ultraviolet light) used is to be performed in the same reaction apparatus. In particular, an ultraviolet light emitting means and a plasma etching means are provided in one reaction apparatus having the same reaction system.

Furthermore, in the present invention, ultraviolet light is applied during plasma etching including plasma ashing, and this activated gas is introduced into an atmosphere irradiated with ultraviolet light, and while the electromagnetic energy of plasma etching resonates, the active gas is Gives light energy to last. Furthermore, the activated reactive gas can be directed to the surface to be formed, and the reactive gas can be caused to "surface migrate" over the surface, resulting in isotropic etching.

``Effect: Along with this plasma etching, the photoexcitation technology removes the natural oxide on the surface to be formed, and furthermore prevents the adsorption of hydrocarbons from the backflow of oil vapor from the vacuum pump onto the surface to be formed. In addition, during this UV cleaning, if the surface of the substrate to be formed is made of a material that particularly dislikes oxygen, such as a ■-■ compound such as GaAs, ammonia or ammonia may be used as a cleaning reactive gas.
This is carried out using a gas for a reducing atmosphere such as hydrogen, and excitation of this gas by ultraviolet light or in combination with microwave excitation. If the surface to be formed is an organic material such as photoresist, oxygen is introduced and activated to perform etching (ashing) on the treated surface.

In the present invention, an ultraviolet light source is used. A low-pressure mercury lamp is used to produce light with a wavelength of 185 nm (the intensity is preferably 51/c11).
12 or more), the excited state of the excited reactive gas can be maintained.

For UV cleaning, the inside of the reactor is kept under atmospheric pressure or reduced pressure. When carried out in a reducing atmosphere, ammonia was mainly used. This ammonia is then decomposed by 185 nm ultraviolet light, easily releasing active hydrogen, and forming natural oxides such as SiO□ + 4 H→ 51+ 211□0↑Cn
This is because the surface can be cleaned as Hz6B + mH-+ n'clIa↑. Further, when UV cleaning was performed in an oxidizing atmosphere, oxygen was used. Then, CnHz+++z + mO−” n'coz +
Vaporization can be removed with n”820 ↑.

Furthermore, cyclotron resonance using plasma etching uses an inert gas or a non-product gas (a gas that itself produces only a gas when decomposed or reacted). Argon is a typical inert gas. However, helium, neon, or krypton may also be used. In the case of oxide gases, non-product gases include oxygen, nitrogen oxide (
N20. No.

NO, ), carbon oxide (CO, COz), water (H□0), and as nitride gases, nitrogen (NZ), ammonia (NH3
), hydrazine (!'hH4), carbon fluoride (NF:l,
NZF&) or these with a carrier gas or hydrogen (H
A typical example is a gas mixture of □).

These non-product gases are activated by cyclotron resonance and directed onto a substrate having a treated surface. Thus, the active non-product gas can etch the treated surface. In particular, since the treated surface is isotropically etched,
From above this etching chamber, the wavelength of 185nn+ is etched simultaneously.
(ultraviolet light with a wavelength of 300 nm or less) is irradiated,
Spread the activated gas uniformly over the entire surface to be treated. Further, by heating the substrate at a temperature of room temperature to 500° C., etching of unnecessary materials on the surface of the substrate to be formed can be promoted.

In the present invention, anisotropic etching is performed when only ECR is used, and isotropic etching is performed when ECR and ultraviolet light are used together. Furthermore, UV cleaning using only ultraviolet light utilizes isotropic removal of surface residue. This is direct to the gas flow of the etching gas for F, CR etching, and is suitable for anisotropic etching. When U7 is irradiated with ultraviolet light, the active gas for etching migrates on the surface to be etched (surface migration), utilizing the property of promoting isotropic etching.

For this purpose, selectively applied photoresist is used to perform anisotropic etching of silicon oxide, semiconductor, and other films on the substrate by ECR etching (also called sheer etching). Thereafter, the type of reactive gas is changed and activated while irradiating with ultraviolet light to remove only the photoresist. Further, in order to remove photoresist residue and other dirt, UV cleaning is performed by irradiating only ultraviolet light.

In this way, it has become possible to perform selective anisotropic etching of the substrate, and to perform subsequent removal of the photoresist and cleaning of the surface continuously.

The present invention will be illustrated below with reference to Examples.

Embodiment 1 FIG. 1 shows an outline of a UV cleaning type microwave excitation etching apparatus of the present invention.

In the drawing, there is a reaction space (1°) inside a stainless steel container (1°).
1) is configured. This container has an outlet (1'') for taking out the substrate (10), the substrate (10) is placed in a substrate holder (10'') at the bottom, and a halogen lamp heater (7) is installed on the back side to heat the container. ing. On the other hand, the container (1')
The upper part has a spiral-shaped synthetic quartz window (20
) with a low-pressure mercury lamp (6) that emits ultraviolet light with a wavelength of 185 nm onto the substrate at a rate of 5 mW/cm2 or more (preferably 10 mW/cm2 or more).
˜ioomW/cm”).

In addition, non-product gas is supplied from the etching system (13) to the resonance space (2) made of stainless steel (2').

Then, even if this gas is not supplied with microwaves, it passes through the resonance space (2) and reaches the reaction space (1), where it is irradiated by the ultraviolet light source (6) and is activated and excited. This activated gas then comes into contact with the surface of the substrate (10) to perform plasma etching or plasma ashing on the surface. The dirt adsorbed here by the simultaneously irradiated ultraviolet light is directly irradiated with the ultraviolet light, causing a photochemical reaction, and UV cleaning is also performed.

Thereafter, the supply of microwaves is stopped or made very weak, and the treatment surface of the substrate is irradiated with only ultraviolet light or with sufficiently weak ultraviolet light.

Then, since there were no or sufficient ion species turned into plasma, so-called UV cleaning could be performed without damaging the substrate surface.

Experimental Example 1 This experimental example uses the apparatus of Example 1 to perform anisotropic etching of silicon oxide, isotropic etching of photoresist thereon,
Furthermore, the surface was subjected to UV cleaning. A group of longitudinal cross-sectional views of this treatment step is shown in FIG.

A substrate (10) in which silicon oxide (21) was formed on a silicon semiconductor and a photoresist (22) was formed thereon was used. ECR etching was performed using this photoresist as a mask, and as shown in FIG. 2(B), silicon oxide was anisotropically etched (
23). That is, the microwave is 2.4
It has a frequency of 5 GHz and is regulated with a power of 30 to 500 GHz, for example 200 W. The resonance intensity of the magnetic fields (5) and (5") was set to 875 Gauss. The pressure in the reaction space was 0°0
02 torr, and argon was supplied from (18) at 50 cc/min as a non-product gas. In addition, nitrogen fluoride (NF3
) was supplied from (16) at 20 cc/min.

After this etching was completed, ultraviolet light was introduced and oxygen was introduced from (13). Then photoresist (22)
The resist at the portion (24) was removed by ECR plasma etching, ie, ashing. However, hydrocarbons (25) tend to adhere to surfaces where photoresist is not formed. Therefore, this plasma etching and UV
The lamp was turned on and the entire surface of the substrate was irradiated with ultraviolet light.

As the ultraviolet light (6), a low-pressure mercury lamp was used to emit light of 185 nm.

To perform this UV cleaning, the pressure inside the reaction chamber is 1
The pressure was set at 0 to 100 torr to promote the reaction between ozone or oxygen radicals and the remaining organic matter (25).

In this way, as shown in FIG. 2(D), the photoresist was completely removed and the selectively etched silicon oxide became able to be sharply anisotropically etched.

The object to be etched is not only silicon oxide, but also silicon nitride, silicon semiconductors, metal silicides, and all other materials that require the manufacturing process of semiconductor integrated circuits.

``Effect J'' As is clear from the above description, the present invention involves plasma etching (ashing) of organic matter on the treated surface of a substrate and subsequent UV cleaning of the surface. In addition to selective anisotropic etching and this anisotropic etching method, it is possible to perform isotropic plasma etching by irradiating ultraviolet light, and the same plasma etching method can perform anisotropic etching and isotropic etching. It became possible to use them properly.

Furthermore, in the present invention, dirt that has been attached or formed in advance, or dirt that is newly adsorbed immediately after the film is formed or in the reactor, is removed by UV cleaning.

A film is formed in the reaction system by microwave-excited CVD.

As an ultraviolet light source for UV cleaning in the present invention,
Excimer laser (wavelength 100-40
Needless to say, an argon laser, a nitrogen laser, etc. may also be used.

In FIG. 1 of the present invention, etching treatment was performed on the upper surface side of the substrate. However, it goes without saying that this drawing may be turned upside down, the substrate may be placed on the bottom or on the side (vertical portion), and the light source and the resonator may be placed on the top or sideways.

[Brief explanation of the drawing]

FIG. 1 shows an optical cleaning type cyclotron resonance type optical etching apparatus of the present invention. FIG. 2 is a longitudinal sectional view showing the steps of the present invention.

Claims (1)

[Claims] 1. A substrate having a treated surface, a means for treating the treated surface of the substrate by plasma etching using ion species of a reactive gas turned into plasma, and a means for causing excitation, decomposition or reaction with ultraviolet light. A substrate surface treatment apparatus comprising: means for treating the treatment surface of the substrate with the reactive gas. 2. A substrate surface treatment apparatus according to claim 1, wherein the plasma etching processing means uses an electron cyclotron resonance method. 3. A step of disposing a substrate having a treated surface and performing plasma etching with ion species turned into plasma on the substrate, and at the same time or after this step, a reactive gas excited, decomposed or reacted by ultraviolet light is removed. A substrate surface treatment method comprising the steps of activating the treatment layer and treating the treatment layer with the gas. 4. A photoresist selectively provided on the surface of the substrate having the treated surface, a step of applying anisotropic plasma etching to the treated surface of the substrate using the photoresist as a mask, and plasma etching using ultraviolet light in combination. A method for treating a surface of a substrate, the method comprising: removing the photoresist by performing isotropic etching; and performing ultraviolet cleaning by irradiating ultraviolet light.