JP2511810B2 - Processing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to photo-plasma etching of a photo-processed surface by using plasma which is generated in the same plasma generator on the process surface of a substrate and ultraviolet light cleaning (ultraviolet light) using photochemical reaction. Is also referred to as UV cleaning or photocleaning), and an apparatus for performing light treatment such as photogas phase reaction or plasma gas phase reaction. Further, the present invention intends to automate and simplify the process of a semiconductor integrated circuit (hereinafter referred to as LSI).

[0002]

2. Description of the Related 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 independent device, and there have been no attempts to achieve synergistic effects by using their respective features, and no device has achieved it. In addition, there was no apparatus for performing anisotropic etching of the substrate surface in advance in the same apparatus using these photoresists as a mask prior to these steps.

[0003]

Further, when the optical processing and the plasma processing are to be integrated, individual parts are required for each, and reduction cannot be achieved. Further, when a low-pressure mercury lamp is used as the ultraviolet light source, the light emission intensity is not sufficient, and as a result, the light processing speed is low, which is a problem. Therefore, there has been a demand for a means for generating strong ultraviolet light.

[0004]

In order to meet such a demand, the present invention utilizes a magnetic field and an electric field interaction to generate ultraviolet light, and another magnetic field and an electric field interaction to generate a plasma. The means for generating the converted reactive gas is arranged by using the same apparatus, particularly the same plasma generation chamber. Using this apparatus, plasma etching of the processing surface using the interaction of the magnetic field and the electric field of the present invention, particularly anisotropic plasma etching of the processing surface and plasma ashing of photoresist, is performed simultaneously with this step. Alternatively, as a subsequent step, ultraviolet light cleaning (UV cleaning using ultraviolet light) or ultraviolet light such as UV etching or UV ashing is also performed using ultraviolet light generated by utilizing the interaction between the magnetic field and the electric field. It is possible to carry out the light treatment in the same reactor.

Further, in the present invention, the interaction between the magnetic field and the electric field causes an electron cyclotron resonance (also referred to as ECR) condition, and a strong ultraviolet light source is generated by utilizing this resonance region. Then, the generated ultraviolet light can be used to perform an optical treatment such as optical cleaning, optical etching or optical ashing. Therefore, for the generation of ultraviolet light under ECR conditions, one or more of argon, deuterium, krypton, or mercury are introduced into this plasma space, and strong ultraviolet light is generated by using the resonance emission of these gases. It is being generated.

When "acting", due to the strong light of the ultraviolet light source utilizing this electromagnetic energy, the natural oxides formed on the surface to be formed are removed, and further, the hydrocaul is produced by the reverse flow of oil vapor from the vacuum pump. -It is also possible to prevent the adsorption of the bon on the surface to be treated. In addition, in the case of the ultraviolet light cleaning, in the case of a material whose surface on which the substrate is to be formed particularly dislikes oxygen, such as 3-5 compound such as GaAs, a reducing atmosphere such as ammonia or hydrogen is used as a cleaning reactive gas. This gas is excited by irradiating it with ultraviolet light, or by using it 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.

In the present invention, by using the ECR condition as an ultraviolet light source and irradiating light with a resonance emission wavelength of mercury of 185 nm (intensity is preferably 10 mW / cm ² or more),
The excited state of the excited reactive gas can be maintained. Between the space for generating the ultraviolet light and the reaction space for arranging the substrate having the processing surface, a translucent window is provided, if necessary, so that the generation of the ultraviolet light of the gas and the exchange with the processing space can be performed. It was shielded so that it would not exist. 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.

An inert gas or a non-product gas (a gas that itself produces only a gas even if decomposed or reacted) is introduced into the plasma generation space under the cyclotron resonance used for plasma etching. Argon is a typical inert gas. However, helium, neon or krypton may be used. Non-product gases include oxygen and nitric oxide (N ₂ O, NO, N in the case of oxide gases).
O ₂ ), carbon oxide (CO, CO ₂ ), water (H ₂ O) or nitrogen as a nitride gas (N ₂ ), ammonia (NH ₃ ), hydrazine (N ₂ H ₄ ), carbon fluoride (NF ₃ , N ₂ F ₆ ), carbon chloride (CCl ₄ , H ₂ CCl ₂ ), or a gas obtained by mixing these with a carrier gas is typical.
These non-product gases are activated by cyclotron resonance and guided according to a magnetic field onto the substrate with the treated surface. Thus, the treated surface can be plasma etched by the active non-product gas. If isotropic etching is to be performed on the processing surface, the pressure in the reaction chamber in which plasma etching is performed may be increased to reduce the mean free path of the reactive gas. Then, a uniform active gas may be spread over the entire treated surface. Further, by heating the substrate at a temperature of room temperature to 500 ° C., it is possible to promote the etching of the unwanted matter on the formation surface of the substrate.

The present invention can perform anisotropic etching when performing plasma etching only under ECR conditions. Further, by generating ultraviolet light in the plasma generation chamber, in an optical treatment process such as optical cleaning using only ultraviolet light, optical etching, and optical ashing, the active gas for etching migrates on the surface to be treated ( Surface migration) and utilizes properties that promote isotropic cleaning, ashing or etching. Therefore, for example, as an example of the three kinds of treatments, 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 type of reactive gas is changed and the pressure in the reaction chamber is increased (0.1 to 10 torr) to remove only the photoresist. Further, in order to remove the residue of the photoresist and other contaminants, ultraviolet light is generated in the plasma generation chamber, and only ultraviolet light is irradiated to perform ultraviolet light cleaning or ashing. Thus, the substrate can be selectively anisotropically etched, and the removal of the photoresist and the cleaning of the surface can be continuously performed.

The present invention will be described below with reference to examples.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an outline of an apparatus for microwave irradiation type microwave excitation of the present invention. In the drawing, stainless steel container
The reaction space (1) is formed in (1 '). This container is
It has a substrate (10) take-out port (1 ''), the substrate (10) is provided in the lower part on the substrate holder (10 '), and a halogen lamp heater (7) is provided on the back side for heating. . On the other hand, in the upper part of the container (1 '), a plasma generation chamber (2) (plasma generation space for generating ultraviolet light) that uses interaction of magnetic field (5), (5') and electric field for generating an ultraviolet light source. That is, the ultraviolet light generation space). The gas to be introduced is changed using this plasma generation chamber (2) to activate the gas for plasma treatment. Electric field energy is supplied to the plasma generating space from a microwave power source (3), a tuning device (4) and a quartz window (18). This electric field energy is also supplied to the space (2 ') through the window (18). And when generating ultraviolet light, the doping system
From (13), the mercury bubbler (11) is bubbled with argon, and mercury vapor and argon gas are introduced from, for example, (24) to generate ultraviolet light. When generating gas for plasma etching, argon or oxygen (for ashing) or NF ₃ (for etching) or the like was introduced from the doping system (13) through (25) to generate plasma. Generate a reactive gas. In this plasma etching, a reactive gas for etching or ashing of the doping system (13) is introduced from (26), argon is introduced from (25), and the reactive gas is activated by plasmanized argon. May be used.
The window (19) is transparent to ultraviolet light. Thus, UV light was generated in the window (2) using ECR plasma, and it was possible to perform photoetching on the processing surface of the substrate arranged in the reaction space (1) using these.

[Experimental Example] This experimental example is an application example in which anisotropic etching of silicon oxide, etching of a photoresist thereon, and ultraviolet light cleaning of the surface were performed using the apparatus of the example. A group of vertical cross-sectional views of this processing step is shown in FIG. A substrate (10) having silicon oxide (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 had a frequency of 2.45 GHz according to (3) and was supplied with an output of 30 to 500 W, for example, 200 W. The ultraviolet light transmissive window (19) is housed in the auxiliary chamber (19 '), the chamber (2) and the reaction chamber (1) are in an open state, and gas can freely flow in and out. The resonance magnetic field strength of the magnets (5) and (5 ') was 875 Gauss. Plasma generation space (2)
The pressure in the reaction space (1) was 0.002 torr, and argon was supplied as a non-product gas from (25) at 50 cc / min. In addition, nitrogen fluoride (NF ₃ ) was supplied from (26) at 20 cc / min.

Further, oxygen was introduced from (25). Then, as shown in FIG. 2 (C), the photoresist (22) was removed by ECR plasma etching, that is, ashing to remove the resist at the portion (27). However, the hydrocarbon (28) is likely to adhere to the surface where the photoresist is not formed. Therefore, after this, only ultraviolet light cleaning was performed. That is, after this etching is completed, a magnetic field of 875 Gauss is applied by the magnets (5) and (5 '), the window (19) is closed, and the chamber (2) and the reaction chamber are closed.
(1) and (2) were made transparent and the gases could not enter and leave each other. Then, mercury and argon were added from (24) to the plasma generation space (2) to generate 185 nm strong ultraviolet light. Unnecessary argon was exhausted through valves (14 ') and (15').

At this time, the pressure in the reaction chamber (1) is 10 to 100 torr.
As organic matter (2
7) promoted reaction with. 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 objects to be etched are not only silicon oxide, but also silicon nitride, silicon semiconductors, metal silicides,
Alloys and other electronics applications, such as all those requiring manufacturing processes for semiconductor integrated circuits, can be carried out by changing the reactive machine for etching.

[0014]

As is apparent from the above description, the present invention is one in which plasma etching (ashing) of an organic substance on a treated surface of a substrate and subsequent ultraviolet light cleaning of the surface are performed. Furthermore, in addition to selective anisotropic etching of the substrate using the photoresist as a mask and this anisotropic etching means, it is possible to perform isotropic plasma etching by irradiating ultraviolet light, and the same plasma etching means is used. It has become possible to selectively use anisotropic etching and isotropic etching.

The present invention has a plasma generation space for generating ultraviolet light and a plasma generation space for plasma etching in the same manner, and both have been carried out by using the interaction between a magnetic field and an electric field. For this reason, since the mercury lamp is not used unlike the conventional light processing devices, the ultraviolet light source is not deteriorated by long-term use, and the intensity of the ultraviolet light can be adjusted by changing the intensity of the magnetic field.

Further, according to the present invention, the filth previously attached or formed, or the filth newly adsorbed immediately after the film formation or in the reaction furnace is removed by ultraviolet light cleaning. In FIG. 1 of the present invention, the 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.

The present invention is an ultraviolet and ECR etching,
Ashing and cleaning are shown as examples. However, conversely, the film formation using ultraviolet light or the film formation using ECR conditions may be performed at the same time as, before, or after the film formation. 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 not toxic, or the ultraviolet light generation gas is released into the reaction space by magnetic field pinching. If it is difficult to do so, the window (Fig. 1 (19)) may be removed.

[Brief description of drawings]

FIG. 1 shows a cyclotron resonance type processing apparatus of ultraviolet light processing and plasma processing of the present invention.

FIG. 2 is a group of vertical cross-sectional views showing an example of a process using the present invention.

[Explanation of symbols]

 1 ... Reaction space 2 ... UV light generation and plasma generation space 3 ... Microwave power source 4 ... Tuning device 5, 5 '... Magnet 9 ...・ ・ Exhaust pump 10,10 '・ ・ Substrate, substrate holder 11 ・ ・ ・ ・ Mercury bubbler 13 ・ ・ ・ ・ Dope system 14,15 ・ ・ Valve 14', 15 '・ Valve

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H01L 21/302 N

Claims (1)

(57) [Claims] 1. A plasma generation chamber maintained under reduced pressure,
Introducing an oxide gas in a resonance region generated by resonance interaction of a magnetic field and an electric field in a processing apparatus having a magnetic field generating means provided around the generating chamber and a means for supplying a microwave to the plasma generating chamber. The treatment method characterized in that the photoresist is removed by using the plasma-oxidized oxide gas obtained by the above, and then the photoresist is irradiated with ultraviolet light to perform cleaning.