JPS6383286A - Etching device - Google Patents

Abstract

PURPOSE:To carryout high-purity etching without contaminating the surface of a substrate by providing a vacuum conveying means between an isotropic chamber and an anisotropic chamber, and carrying out continuous treatment in both chambers without exposing the substrate to the external air. CONSTITUTION:An electric discharge gas is introduced into a discharge chamber 1 from a valve 9, a voltage is impressed on a discharge coil 7 from a high-frequency power supply 8 to produce plasma 2, and the surface of the substrate 5 in a treating chamber 3 is etched. The etching device is used as the isotropic etching chamber I, and a magnetic field-excited reactive etching device is used as the anisotropic etching chamber A to chamfer a contact hole. In this case, the substrate 5 is put in the isotropic etching chamber I, and then taper-etched by the radiation of LTE plasma. The substrate is then transferred to the anisotropic etching chamber A by vacuum conveyance to anisotropically etch an Si film. Subsequently, the substrate 4 is again transferred to the isotropic etching chamber I by vacuum conveyance, and a resist is etched and removed by the radiation of the LTE plasma.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention uses plasma to create synchrotron radiation and reactive active species, and uses this to create insulating films, protective films, semiconductor films, metal films, etc. of semiconductor devices. This invention relates to improvements in etching equipment systems that perform etching such as thin film formation, etching, surface cleaning, and surface modification.

(Prior art and its problems) First, to explain the meaning of the terms used in this application, "isotropic etching" is an etching process that is not faithful to the resist pattern in the manufacturing of semiconductor devices.
"Anisotropic etching" is a process that is faithful to that. The difference between these is obvious when explained in terms of the cross-sectional shape of the workpiece after processing, which is shown in FIG.

"Surface cleaning" literally means cleaning the surface of the substrate, and includes removing natural oxide films on the surface of the substrate.

"Surface modification" refers to changing the properties of the substrate surface, and includes surface oxidation and surface nitridation due to heat.

One example of the use of isotropic etching is ``cutting corners.'' Current CVD technology uses metal films, insulating films,
There is a problem with step coverage when forming thin films such as protective films and semiconductor films, and these thin films do not adhere well to the corners of sharp holes, so it is necessary to remove these corners.

A method to obtain the r angle other than this isotropic etching is to damage the resist while performing RIE and then etching while receding the resist.
This method is difficult to control properly.

In addition to the above, isotropic etching is used to remove damaged layers, clean substrate surfaces, and modify substrate surfaces.

On the other hand, anisotropic etching is an indispensable technique where highly precise and micro-fabrication is required, as the etching process is carried out faithfully to the resist.

FIG. 7 shows a conventional system of this type of device. Conventionally, even when it is necessary to perform isotropic etching and anisotropic etching on a substrate in succession, isotropic etching equipment (■) and anisotropic etching equipment (A) are installed separately. The etching process and anisotropic etching process were performed independently in the atmosphere. Therefore, it is necessary to take the substrate out into the atmosphere, which poses a serious problem in that the surface of the substrate is contaminated with various substances in the atmosphere. Moreover, since the etching apparatus is duplicated, it is uneconomical and time-consuming. Furthermore, when wet etching is used for isotropic etching, cleaning and drying steps are required after the etching process, which is not only contaminated with various substances but also wasteful in terms of economy and time.

(Objective of the Invention) The present invention aims to provide an apparatus that can economically perform etching with high purity by eliminating inevitable surface contamination during both isotropic etching and anisotropic etching processes. purpose.

(Structure of the Invention) The present invention comprises: a discharge chamber provided with a discharge body introduction system and a power application means; a processing chamber provided with an exhaust system and installed with a substrate; In an etching apparatus that etches the surface of the substrate using both reactive species and synchrotron radiation or only reactive species (hereinafter simply referred to as radiation), there is an isotropic etching chamber, an anisotropic etching chamber, and an etching chamber between them. The above object has been achieved by an etching apparatus that is equipped with a vacuum conveyance mechanism and can perform continuous isotropic etching and anisotropic etching without exposing the substrate to the outside air.

(Example) Fig. 9 shows a conventional etching apparatus using LTE plasma (as it is a new technology, there are few documents. , reference) is a schematic front sectional view. First, to explain this, a predetermined discharge body is guided from a gas supply device (not shown) through a valve 9 into a discharge chamber 1 made of a quartz glass tube (other materials may be used), and is connected to the discharge chamber 1. Exhaust valve 11 (connected to an exhaust pump not shown) provided in the processing chamber 3 that communicates with
Exhaust the gas in both chambers to maintain the gas pressure at the specified value, and
The output voltage of the 3.56 MHz high frequency power supply 8 is applied to the discharge chamber 1.
The voltage is applied to the discharge coil 7 wound around 0, and the plasma 2 of the discharge electric body is generated in the discharge chamber 1.

(Instead of using the discharge coil 7, it is also possible to provide a pair of electrode plates facing each other with the discharge space in between, and apply an alternating voltage such as a high frequency voltage or a direct current voltage between these electrodes to generate plasma discharge.) The frequency of the high frequency power source 8 is selected to be between 10 kHz and several hundred GHz.
When using a frequency higher than around GHz, a microwave cavity that wraps around the discharge chamber 1 is installed in place of the discharge coil 7 and the pair of electrode plates described above, thereby making it possible to generate plasma discharge. be. ) The substrate holder 4 that holds the substrate 5 in the processing chamber 3 is provided with a heating and cooling mechanism (not shown) that can adjust the temperature of the substrate 5 to a desired value as necessary.

Now, the discharge that occurs in the discharge chamber 1 varies depending on the type of gas in the discharge chamber 1, the pressure, and the magnitude of the applied high-frequency power, but generally, in areas where the pressure is high and the power is low, high-frequency glow discharge occurs. In the region where the pressure is low and the power is large, L T E (Local Thermal Equ
ilibrium) plasma discharge (strictly speaking, it is a quasi-thermal equilibrium plasma discharge, but the term LTE is commonly used).

However, the high-frequency glow discharge referred to here is a state in which plasma with not very high brightness is generated almost uniformly and widely within the discharge chamber 1, whereas LTE plasma discharge is a state in which plasma with very high brightness is discharged. This refers to a discharge state in which a glow 200 in the form of a high-frequency glow discharge exists surrounding a locally confined state within the chamber 1.

The apparatus shown in FIG. 9 utilizes this LTE plasma discharge, and guides the reactive species generated in the plasma 2 into the processing chamber 3 to perform predetermined processing on the surface of the substrate 5. For example, NF3 gas (or fluorine gas, fluorine compound gas, or a mixed gas containing them) is LT
When passed through E plasma discharge, it decomposes very well and generates a large amount of fluorine-based reactive species, which has the advantage of allowing high-speed etching processing.

In the apparatus shown in FIG. 9, a shielding plate 10 (-dashed line) made of a transparent insulator (for example, quartz glass) may be provided, leaving a gas flow gap 100. This shielding plate 1
By providing 0, damage to the substrate due to charged particles is eliminated, reactive species can be uniformly supplied to the processing surface of the substrate 5, and high-quality etching is possible.

Next, FIG. 10 is a conceptual diagram of a magnetic field excitation type reactive ion etching apparatus (hereinafter abbreviated as MERIE apparatus). A pair of solenoid coils is installed outside of the cathode to form an alternating magnetic field parallel to the cathode surface so as to be orthogonal to the electric field applied to the cathode, causing magnetron discharge. It is something. In the alternating magnetic field,
This has the advantage of eliminating the need for mechanical magnet scanning or insertion of a magnet into the cathode surface.

The MERIE device has the following problems that hinder the speeding up of conventional low-pressure RIE devices: (1) high-density plasma cannot be changed, (2) temperature rises when high power is applied, and (3) ion energy rises. This is an RIE device that solves the following problems and enables use in megabit processes.It uses a magnetic field to improve ionization efficiency and reduces damage due to low ion energy. This achieved a reduction in

FIG. 1 is a schematic diagram of an etching apparatus according to an embodiment of the present invention, and the same members as in FIG. 7 are designated by the same reference numerals and their explanations will be omitted.

The apparatus shown in FIG. 1 connects the isotropic etching chamber (1) and the anisotropic etching chamber (A) to carry out vacuum conveyance between them. Here, the LTE plasma apparatus shown in FIG. 9 is used as the isotropic etching chamber (2). LTE plasma contains a large amount of active species and strong synchrotron radiation, so etching, deposition, etc. are performed only with electrically neutral active species and synchrotron radiation, excluding charged particles (ions, electrons, etc.) in the plasma. It is possible. In the case of etching, the etched shape is isotropic. On the other hand, M in Figure 10
An ERIE apparatus is used as an anisotropic etching chamber A.

As a result, the isotropic etching step and the anisotropic etching step are performed consecutively, and since the substrate does not need to be taken out into the atmosphere, etching processing with high purity can be performed economically.

An example of application of the process using the apparatus shown in FIG. 1 is the chamfering of a contact hole shown in FIG. In this method, first, the substrate 5 is placed in an isotropic etching chamber (1), and the 5i02 film is taper-etched using LTE plasma radiation. Next, the base 5
is transported to the MERIE chamber by vacuum transport, where the Si film is anisotropically etched, and then returned to the isotropic etching chamber.
The substrate 5 is transferred by vacuum transport, and the resist is removed by ashing with LTE plasma radiation.

Thus, when using this apparatus, by moving the substrate 5 back and forth between the isotropic etching chamber I and the anisotropic etching chamber A, the process of chamfering the contact hole, which requires multiple steps, can be continuously performed with high purity. It can be done with

FIG. 2 is a schematic diagram of an etching apparatus according to another embodiment of the present invention. In the apparatus of this embodiment, by providing a load lock chamber between the two chambers, the isotropic etching chamber
Both the anisotropic etching chamber A and the anisotropic etching chamber A can be maintained in a vacuum, so that high-purity processing can be performed with good reproducibility.

FIG. 4 is a schematic diagram of an etching apparatus according to another embodiment of the present invention. Examples of applications of this device include: .

That is, first, the substrate 5 is placed in the isotropic etching chamber (2), and the LT
There is a "RIE treatment after surface cleaning" in which the natural oxide film and dirt on the Si surface are cleaned using E plasma, and then the substrate 5 is vacuum-transferred to an anisotropic etching chamber A, subjected to tE heat treatment, and the substrate 5 is taken out. . Further, the substrate 5 is placed in the anisotropic etching chamber A and subjected to RIE processing, but during the RIE processing, the substrate 5 is damaged by the impact of charged particles in the plasma. This damage may appear as deterioration of the electrical characteristics of the semiconductor device on the substrate 5. This deterioration is caused by, for example, variations in vth in MO8 type semiconductor devices and Vth in bipolar type semiconductor devices.
This appears strongly as fluctuations in fe, etc. Therefore, after that process, the substrate 5 is vacuum-transferred and placed in an isotropic etching chamber (2), the damaged layer received from the plasma during the RIE process is removed using LTE plasma, and then the substrate 5 is taken out. There is a "damage layer removal process".

FIG. 5 is a schematic diagram of an etching apparatus according to another embodiment of the present invention. This apparatus is equipped with a load-lock chamber similar to the apparatus shown in FIG. 4, and can improve the maintainability of each processing chamber and perform high-purity processing with good reproducibility.

FIG. 6 is a schematic diagram of an etching apparatus according to another embodiment of the present invention. This apparatus has a load cock chamber between the isotropic etching chamber I and the anisotropic etching chamber A of the apparatus shown in FIG.

As described above, the present invention provides an isotropic etching chamber (2) and an anisotropic etching chamber (A) and a vacuum conveyance mechanism therebetween,
The feature is that continuous processing of isotropic etching and anisotropic etching can be performed without exposing the substrate to the outside air.
The structure of the processing chamber, the arrangement of the substrate, the structure of the exhaust system, etc. are not limited to those described above, and various structures can be used.

(Effects of the Invention) According to the etching apparatus of the present invention, highly pure etching can be economically performed with no surface contamination that conventionally exists between the isotropic etching and anisotropic etching steps. Equipment is provided.

[Brief explanation of the drawing]

1.2, 4, and 5.6 are schematic cross-sectional views of etching apparatuses according to 13th embodiment of the present invention, respectively. FIG. 3 is a cross-sectional view of a substrate treated with the apparatus of the present invention. FIG. 7 is a similar diagram of a conventional etching apparatus. 1...Discharge chamber, 2...Plasma,
3... Processing chamber, 4... Substrate holder, 5... Substrate, 7... Discharge coil, 8... High frequency power supply, 9...Introduction valve, 10...Shielding plate, 11...
Exhaust valve, 100... Gap, 200...
...Glow, A...Anisotropic etching chamber, ■...Isotropic etching chamber, L...Load lock chamber.

Claims (1)

[Claims] (1) A discharge chamber provided with an introduction system for a discharge electric body and a power application means; a processing chamber provided with an exhaust system and installed with a substrate;
In an etching apparatus that etches the surface of the substrate using both the reactive active species in the plasma generated in the discharge chamber and the synchrotron radiation, or only the reactive active species (hereinafter simply referred to as radiation), isotropic etching is performed. An etching apparatus characterized in that a vacuum transfer mechanism is provided between an isotropic etching chamber, an anisotropic etching chamber, and continuous processing of isotropic etching and anisotropic etching without exposing the substrate to the outside air. .