KR20030049086A - System and method for dry cleaning of substrate - Google Patents

Abstract

PURPOSE: A dry cleaning apparatus and method of a substrate are provided to be capable of simultaneously removing an oxide layer and a damaged layer of the surface of the substrate by using active species of plasma. CONSTITUTION: An oxide layer of the surface of a substrate(90) is removed by using a dry cleaning apparatus. The dry cleaning apparatus is provided with a carrier gas inlet port(20) for supplying carrier gas containing hydrogen and nitrogen, a plasma generating part(30) for generating plasma by ionizing the carrier gas, a reactive gas inlet port(40) for supplying reactive gas containing fluorine or chlorine, a substrate support part(60) for supporting the substrate, and a process lamp part(80) installed opposite to the substrate for supplying ultraviolet or infrared rays. Polymers containing fluorine or chlorine, hydrogen, and nitrogen, are formed on the substrate by activating active species of the plasma using the ultraviolet or infrared rays, wherein the polymers are capable of removing the oxide layer of the surface of the substrate. Preferably, the active species contains atomic fluorine or chlorine for removing a damage layer of the surface of the substrate.

Description

Substrate dry cleaning apparatus and method {SYSTEM AND METHOD FOR DRY CLEANING OF SUBSTRATE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry cleaning method and apparatus for a substrate, and more particularly, to a natural oxide film and / or a chemical oxide film on a surface of a substrate during a manufacturing process of a semiconductor device, a liquid crystal display, or an electroluminescent device (hereinafter referred to as a semiconductor device). And / or to provide a surface treatment method and apparatus by plasma for removing a surface damage layer.

In general, a process for manufacturing a semiconductor device includes a process of forming a contact hole 2 by etching an intermediate insulating film in order to connect a lower substrate and a line layer (hereinafter referred to as a contact etching process). do. At this time, the lower substrate 9 (for example, a silicon substrate) exposed as shown in FIG. 1 has a thin oxide layer 7 made of a native oxide and / or a chemical oxide. And a damaged layer 6 due to the incidence of high energy ions during contact etching. If the oxide film layer 7 and the damage layer 6 are left intact or poorly removed, a subsequent process such as metal wiring is performed to increase the resistance of the contact hole, thereby degrading device characteristics. Therefore, after the contact etching process, a process for removing the oxide layer 7 and the damage layer 6 on the substrate surface is necessary.

The conventional technique for removing such an oxide film layer and damage layer is described below.

The simplest method is wet cleaning using a chemical solution containing hydrofluoric acid (HF). In this method, since hydrofluoric acid reacts with the oxide layer, it is possible to remove the oxide layer, but it is difficult to control the oxide etch amount, the Si surface damage layer cannot be removed, and the hole diameter of the contact hole is also reacted with the oxide layer on the sidewall of the contact hole. It has a fatal problem such as increasing (hereinafter referred to as CD). In particular, in the case of ultra-high density integrated circuits, in which CD is gradually decreasing, such an increase in CD becomes a fatal problem and may cause a significant decrease in yield.

Next, as shown in FIG. 2, a technique of activating HF and CH3OH and removing a natural oxide film on the silicon surface by irradiating ultraviolet (UV) light onto the wafer surface in HF and CH3OH atmospheres is commercially available. When the oxide film is removed, polymer does not occur and there is no risk of damage due to charged particles because plasma is not used. However, only the oxide film on the surface can be removed. There is a disadvantage that the damage layer of the Si substrate cannot be removed.

In addition, in another conventional technique shown in FIG. 3, plasma is generated by ionizing H2 / N2 gas using microwaves at a plasma generating unit spaced apart from a position where a substrate (wafer, etc.) is placed (i.e., a remote). Using a plasma), an NF ₃ gas is injected into the path that introduces the above plasma near the wafer to activate the NF ₃ gas by the high energy electrons in the plasma. Therefore, an N _x H _y F _z series polymer is formed on the wafer, which is then subjected to heat treatment such as annealing, ultraviolet treatment, infrared treatment or washing with deionized (DI) water. It is known to remove the oxide film by reacting with the oxide film on the surface. This process has the advantage that the oxide film can be selectively removed with respect to the nitride film or silicon when the surface oxide film is removed, and a passivation layer with hydrogen is formed on the silicon surface to prevent subsequent oxidation. This is a process that requires stacking polymers on the wafer surface, which requires additional steps to remove them (heat treatment such as annealing, UV treatment, infrared treatment, or water washing treatment as mentioned above). This results in a decrease in productivity and an increase in required process equipment, and also has a problem in that the silicon damaged portion of the bottom of the contact hole after contact etching cannot be removed.

In addition, as shown in FIG. 1, a structure such as a self align contact (SAC), which is currently employed in most high density integrated circuits, is used for the gate line 5 and the bit line. The wiring is wrapped with the silicon nitride film 4 and the interlayer insulating film 8 between the wirings is a silicon oxide film, so that selective etching of the silicon nitride film 4 is performed during the etching of the contact hole, thereby providing a margin of overlay. It aims to secure. At this time, after the contact hole 2 is etched, the silicon nitride film 4 surrounding the gate wiring 5 or the wiring of the bit line is necessarily exposed. Therefore, in the dry cleaning process for removing the oxide film 7 and the damage layer 6 on the bottom of the contact hole, the silicon nitride film 4 exposed on the wall of the contact hole as described above should not be etched or damaged. Additionally required. If the silicon nitride film 4 is damaged in the dry cleaning process, a short may occur between the metal film and the gate line 5 or the bit line, which will later fill the contact hole 2, and become a problem.

The present invention is to overcome the above problems, to remove the oxide layer on the surface of the substrate and at the same time to remove the damaged layer on the surface of the substrate to provide a method and apparatus for dry cleaning the substrate having a high selectivity to the silicon nitride film It is for.

1 is a schematic view showing a damaged layer and an oxide layer during dry contact hole etching.

2 is a schematic view showing a substrate dry cleaning method using ultraviolet rays of the prior art.

3 is a schematic view showing a substrate dry cleaning method using a plasma of the prior art.

4 is a schematic view showing the dry cleaning apparatus of the present invention.

5 is a flowchart illustrating a dry cleaning method of the present invention.

<Signs of main parts in the drawing>

10: vacuum chamber 20: carrier gas inlet

30: plasma generating unit 32: microwave source

34: waveguide 36: impedance matching circuit

40: reaction gas inlet 50: cut off

60: substrate support 70: reaction chamber

80: processing lamp unit 90: substrate

Dry cleaning apparatus according to an aspect of the present invention for achieving the above object, the carrier gas introduction unit for introducing a carrier gas containing hydrogen and nitrogen; A plasma generator for generating plasma by ionizing the carrier gas; A reaction gas inlet for introducing a reaction gas containing fluorine or chlorine; A substrate support part supporting the substrate; And a processing lamp unit mounted opposite to the substrate to provide ultraviolet or infrared rays, wherein active species in the plasma generated by the plasma generating unit are activated by ultraviolet or infrared rays supplied from the processing lamp unit to A polymer containing (1) fluorine or chlorine, (2) hydrogen, and (3) nitrogen, which reacts with the oxide film on the substrate surface and removes the oxide film, is formed on the substrate, wherein the active species is formed of the oxide film. It includes atomic fluorine or atomic chlorine to simultaneously remove the damage layer on the surface of the substrate.

Dry cleaning method according to another aspect of the present invention, the carrier gas introduction step of introducing a carrier gas containing hydrogen and nitrogen; Generating a plasma by ionizing the carrier gas; A reaction gas introduction step of introducing a reaction gas containing fluorine or chlorine; And providing ultraviolet or infrared light to the substrate surface, wherein the active species in the plasma are activated by the ultraviolet or infrared light to react with the oxide film on the surface of the substrate to remove the oxide film (a) fluorine Or a polymer containing chlorine, (b) hydrogen, and (c) nitrogen is formed on the substrate, wherein the active species is atomic fluorine such that the damage layer on the surface of the substrate is removed simultaneously with etching of the oxide film. Or atomic chlorine.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

4 shows a schematic view of the dry cleaning apparatus of the present invention. The dry cleaning apparatus of the present invention includes a carrier gas introducing unit 20, a plasma generating unit 30, a reactive gas introducing unit 40, a charged particle blocking unit 50, a substrate support unit 60, and a processing lamp unit 80. do. Detailed descriptions of well-known elements such as the vacuum chamber 10 and the substrate 90 will be omitted.

It is preferable to use a mixed gas of H ₂ / N _{2 as} the carrier gas, but it is also possible to use NH ₃ containing hydrogen and nitrogen. Alternatively, a gas for supplying hydrogen, such as Ar, steam, or CH ₃ OH, which is an inert gas, may be added to the above gas. That is, since the carrier gas serves as a background gas for generating plasma and a source for supplying hydrogen and nitrogen active species, it is possible to use a mixture of the above gases in order to achieve this. For example, it is also possible to use a mixed gas of N ₂ / NH ₃ or a mixed gas of N ₂ / CH ₃ OH. Alternatively, when the reaction gas is HF, for example, activated hydrogen can be supplied from the reaction gas depending on the type of reaction gas, it is also possible to use N ₂ alone or a mixed gas of N ₂ / Ar. That is, as long as it is a combination of the above-mentioned action of the background gas of plasma generation and a gas capable of supplying hydrogen and nitrogen active species for forming a polymer on the surface of the substrate, the technical scope of the present invention cannot be exceeded.

The plasma generator 30 ionizes the injected carrier gas to generate plasma. In order to generate plasma, it is necessary to supply electromagnetic energy from the outside. In FIG. 1, a case of using microwave as an energy transfer means is illustrated. In this case, the microwave generator 32, the waveguide 34, and the impedance matching circuit 36 are required. Since the plasma generator itself using microwaves as an energy transfer source is already known, a detailed description thereof will be omitted. However, the above case using the microwave is only an example, and many known plasma generators can replace it. For example, plate capacitively-coupled plasma generators, electron cyclotron resonance (ECR), inductively-coupled plasma (ICP), surface wave plasma devices (surface wave plasma) There may be various variations, such as: SWP, helical resonator or Helicon source.

In addition, as the reaction gas, a gas containing fluorine or chlorine is used, and the plasma generated in the plasma generator 30 is injected from the reaction gas introduction part 40 installed in a path through which the plasma generated in the lower substrate direction is transferred. The role of the reaction gas is to supply active species for the formation of polymers that can react with the oxide film on the substrate. In this case, as the fluorine-containing gas, one or more of gases such as HF, NH ₄ F, NF ₃ , CF ₄ , SF ₆ , ClF ₃ , F _2, and XeF ₂ may be mixed and used for dilution and discharge at an appropriate concentration. It is also possible to add other gases, such as Ar and nitrogen, for the sake of stability. Further, as the gas containing chlorine, it is possible to use Cl ₂ , HCl, ClF ₃ and the like by mixing one or more of the gases. Also in this case, it is possible to add other gases, such as Ar and nitrogen.

The action of the carrier gas and reactant gas above is to produce a polymer containing hydrogen, nitrogen and fluorine (or chlorine) that can react with the oxide film on the substrate 90. The polymer may remove the oxide film formed on the bottom surface of the contact hole on the substrate. In the case of the related art of FIG. 3, the polymer having the above components is used as in the present invention. Polymers containing hydrogen, nitrogen, and fluorine on the substrate continued to accumulate and required further processing such as subsequent heat treatment or ultraviolet or infrared treatment. This is because in the prior art, there is no means for supplying the activation energy required for the reaction in order for the polymer to react with the oxide film, and the polymer accumulated on the surface of the substrate may react with the oxide film by UV or infrared treatment. It was not possible to remove the oxide film until the activation energy was obtained. Therefore, the upper polymer layer acts as a protective film, so that the damage layer under the polymer cannot be exposed to atomic fluorine in the plasma, and thus there is a problem in that it remains without being etched.

In order to overcome this problem, the present invention performs ultraviolet or infrared treatment to provide activation energy on the wafer surface at the same time as the above polymer deposition, and immediately reacts with the oxide film to remove the oxide film in-situ. Therefore, the damaged silicon under the oxide film may be etched by exposure to atomic fluorine or chlorine.

In addition, since atomic fluorine or chlorine does not etch the oxide film or nitride film, the oxide film on the contact hole wall or the nitride film exposed on the contact hole wall is not damaged, thereby increasing the contact hole CD, which has been a problem in the conventional cleaning process, and It is possible to overcome the problem of the interlayer short caused by the nitride film damage of the self-aligned contact.

Figure 5 shows a preferred flow chart of a substrate dry cleaning method according to another aspect of the present invention. In the method of the present invention, a carrier gas containing hydrogen and nitrogen is first introduced into a vacuum chamber (S10) and introduced into a plasma generating unit. At this time, the carrier gas is ionized by supplying electromagnetic energy (S20). The generated plasma is transferred toward the substrate according to the flow of the gas, and the reaction gas containing fluorine or chlorine is introduced into the vacuum chamber in the path (S30). The reaction gas is dissociated and activated by the high energy electrons in the plasma to supply atomic fluorine or chlorine, and electrons, ions, and active species of various energies are mixed in the plasma. The charged particles are blocked by a baffle to prevent damage that may be caused to the surface of the substrate by the charged particles in the plasma. The above baffle may comprise a grid or mesh and may be supplied with an appropriate voltage, or maintained at ground or floating potential.

Although the above embodiment has been described taking the case of a silicon substrate as an example, even in the case of a liquid crystal display (LCD) using a thin film transistor (TFT), it is basically used for cleaning the surface after etching and removing the damaged layer. Even if used, it should be considered that it is included in the scope of the technical idea of the present invention, it can be applied to the manufacturing process of the electroluminescent device that the concept of the semiconductor process is applied as a matter of course.

The above embodiments and drawings are merely for the purpose of describing the contents of the invention in detail, and are not intended to limit the scope of the technical idea of the invention. The present invention described above has ordinary knowledge in the technical field to which the present invention pertains. Various substitutions, modifications, and changes are possible in the present invention without departing from the spirit of the present invention, and the present invention is not limited to the above-described embodiments and the accompanying drawings. It should be judged including the scope.

The dry cleaning apparatus and method of the present invention allow simultaneous removal of the oxide film and the damaged layer on the substrate surface, thereby eliminating the need for subsequent steps for removing the polymer layer, thereby simplifying the process steps, It is possible to remove only the damage layer while minimizing the etching of the nitride film. In addition, the selectivity to the nitride film is good, it is possible to provide a dry cleaning method particularly suitable for cleaning the substrate after the self-aligned contact process.

Claims (14)

In the dry cleaning device for removing the oxide film on the substrate surface, A carrier gas introducing unit for introducing a carrier gas containing hydrogen and nitrogen; A plasma generator for generating plasma by ionizing the carrier gas; A reaction gas inlet for introducing a reaction gas containing fluorine or chlorine; A substrate support part supporting the substrate; And A processing lamp unit mounted to face the substrate and providing ultraviolet or infrared rays, Wherein the active species in the plasma generated by the plasma generating unit is activated by the ultraviolet or infrared rays supplied from the processing lamp unit (a) fluorine or chlorine to react with the oxide film on the surface of the substrate to remove the oxide film, a polymer containing (b) hydrogen and (c) nitrogen is formed on the substrate, And wherein the active species comprises atomic fluorine or atomic chlorine such that the damaged layer on the surface of the substrate is removed simultaneously with etching the oxide film. The method of claim 1, The plasma generator includes a microwave, a plate capacitively coupled plasma generator, an inductively coupled plasma (ICP) generator, an electron cyclotron resonance (ECR) generator, a helical resonator, a surface wave plasma (SWP) generator, or a helicon source. Dry cleaning apparatus using any one of (Helicon source) for plasma generation. The method of claim 1, And the carrier gas comprises a mixed gas of N ₂ and H ₂ or an NH ₃ gas. The method of claim 3, wherein The carrier gas further comprises at least one of CH ₃ OH, Ar, and water vapor. The method of claim 1, And said fluorine-containing reaction gas is at least one of HF, NH ₄ F, NF ₃ , CF ₄ , SF ₆ , ClF ₃ , F _2, and XeF ₂ . The method of claim 1, The chlorine-containing reaction gas is at least one of Cl ₂ , HCl and ClF ₃ . The method of claim 1, And a blocking unit for blocking the charged particles in the plasma to supply only the active species in the plasma to the substrate. In the dry cleaning method for removing the oxide film on the substrate surface, A carrier gas introduction step of introducing a carrier gas containing hydrogen and nitrogen; Generating a plasma by ionizing the carrier gas; A reaction gas introduction step of introducing a reaction gas containing fluorine or chlorine; And Providing ultraviolet or infrared light to the substrate surface, Wherein the active species in the plasma contains (a) fluorine or chlorine, (b) hydrogen, and (c) nitrogen, which are activated by the ultraviolet or infrared rays and react with the oxide film on the surface of the substrate to remove the oxide film. A polymer is formed on the substrate, And wherein the active species comprises atomic fluorine or atomic chlorine such that the damaged layer on the surface of the substrate is removed simultaneously with etching the oxide film. The method of claim 8, The plasma generating step includes a microwave, a plate capacitively coupled plasma generator, an inductively coupled plasma (ICP) generator, an electron cyclotron resonance (ECR) generator, a helical resonator, a surface wave plasma (SWP) generator or a helicon. Dry cleaning method using one of the source (Helicon source) for plasma generation. The method of claim 8, And the carrier gas comprises a mixed gas of N ₂ and H ₂ or NH ₃ gas. The method of claim 10, The carrier gas further comprises one or more of CH ₃ OH, Ar, water vapor. The method of claim 8, And said fluorine-containing reaction gas is at least one of HF, NH ₄ F, NF ₃ , CF ₄ , SF ₆ , ClF ₃ , F _2, and XeF ₂ . The method of claim 8, The chlorine-containing reaction gas is at least one of Cl ₂ , HCl and ClF ₃ . The method of claim 8, And a step of supplying an active species for blocking charged particles in the plasma to supply only active species in the plasma to the substrate.