JP3657879B2 - Cleaning method for baking equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for forming an insulating thin film, and more particularly to a method for cleaning an apparatus for forming an insulating film by baking a coating film by irradiating it with an electron beam.
[0002]
[Prior art]
With the miniaturization and speeding up of semiconductor devices, the wiring structure has been increased from a single layer structure to a multilayer structure, and semiconductor devices having a metal wiring structure of five or more layers have been developed and produced. However, as the miniaturization progresses, signal transmission delay due to so-called parasitic capacitance between wirings and wiring resistance becomes a problem. In recent years, with the increase in the number of layers, the influence of signal transmission delay due to the wiring structure on the speeding up of the semiconductor device has increased, and various methods have been taken as a workaround. In general, the signal transmission delay can be expressed by the product of the inter-wiring parasitic capacitance and the wiring resistance. In order to reduce the wiring resistance, the transition from a conventional aluminum wiring to a copper wiring having a low resistance has been studied. Since it is extremely difficult to process copper into a wiring shape by dry etching as in the prior art, copper has an embedded wiring structure in the case of copper.
[0003]
Further, in order to reduce the capacitance between wirings, instead of the conventional insulating film by the CVD method using silicon oxide (SiO ₂ ), a SiOF film by the CVD method is used, or a so-called SOG (Spin on G1ass) by the spin coating method is used. ) The application of a low dielectric constant interlayer film formed by using a film or an organic resin (polymer) film has been studied. In general, it is said that the relative dielectric constant of SiOF film can be reduced to about 3.3 (the relative dielectric constant of the SiO ₂ film used in the past is 3.9), but the dielectric constant should be lowered below that. However, practical use is considered extremely difficult from the viewpoint of film stability. On the other hand, low dielectric constant coating films can be reduced to about 2.0 in relative dielectric constant, and are therefore being actively studied.
[0004]
A general method for forming a coating film is as follows:
(1) A thin film material (varnish) is dropped on a semiconductor substrate and rotated to uniformly coat the surface.
[0005]
(2) Heat in steps on a hot plate. (For example, 1 minute at 100 ° C, 1 minute at 200 ° C)
(3) Firing in an electric furnace. (For example, at 420 ° C. for 60 minutes)
It is formed through almost three steps.
However, a long time required for firing in the step (3) is a problem in the production of semiconductor devices.
[0006]
[Problems to be solved by the invention]
As a result of diligent research by the present inventors, it has been found that the firing time can be shortened to about 1/10 by irradiating the electron beam while firing the semiconductor substrate instead of the conventional electric furnace.
[0007]
Since the electron beam source employs a method of extracting only electrons from plasma through a mesh, the electron beam source and the firing chamber are always in the same atmosphere. For this reason, when applied to the above-described step (3), the gas containing the organic component is desorbed from the film to be fired, and the pressure in the discharge region changes suddenly. Due to sudden changes in pressure, the electron beam source becomes unstable, and as a result, problems such as inability to uniformly irradiate the electron beam and variations in the characteristics of the fired film occur.
[0008]
In particular, the influence of a large amount of degassing from the film to be fired cannot be ignored. In order to solve the problem, the present inventors provide a partition between the inside of the processing container in which the object to be irradiated is stored and the electron beam source, and irradiate the electron beam through the partition from the object to be irradiated. Has developed a firing device that uses a method to reduce the effects of degassing.
[0009]
Next, the baking apparatus developed by the present inventors will be described with reference to FIG. A plurality of electron beam forming units 9 are installed on the top of the processing container 8. Each electron beam forming unit 9 is separated from the processing container 8 by the partition wall 10, and the electron beam 13 passes through the partition wall and enters the processing container 8. be introduced. A silicon thin film is used for the partition walls. The electron beam 13 is irradiated while the semiconductor substrate 12 is placed on the sample support 11 installed in the processing container 8. The method for forming the SOG film is the same as the conventional example.
[0010]
In this apparatus, the presence of the barrier ribs eliminated the instability of electron beam irradiation due to the desorbed gas when firing the SOG film. However, when the product (organic matter) is deposited on the partition wall 10 or a part of the processing vessel 8 due to the desorbed gas and continuously used, a problem arises that the irradiation amount changes. Although it was possible to keep the electron irradiation amount effectively irradiated onto the wafer using the sensor constant, the burden on the electron beam forming unit 9 also increases in this case.
[0011]
Since the electron beam uses thermionic electrons generated by passing a current through the filament, there is a problem that if the amount of irradiation has to be increased, the amount of current flowing through the filament will increase and the life will be shortened. occured. Furthermore, as the amount of deposition on the partition wall increases, there is a problem that the product peels off and causes dust on the semiconductor substrate.
[0012]
Furthermore, the product deposited on the partition wall is peeled off, causing a problem of dust on the semiconductor substrate.
[0013]
The objective of this invention is providing the cleaning method of the baking apparatus which can remove the product deposited on the partition and a part of processing container.
[0014]
[Means for Solving the Problems]
[Constitution]
The present invention is configured as follows to achieve the above object.
[0015]
(1) The present invention (Claim 1) includes a processing container, a sample support base installed in the processing container on which a substrate to be processed is placed, a heating mechanism provided on the sample support base, An electron beam generating unit connected to a processing container, and a partition wall inserted between the processing container and the electron beam generating unit, and while heating the substrate to be processed, from the electron beam generating unit A firing apparatus for removing a product adhering to the partition walls and the processing vessel with respect to a firing apparatus for performing an annealing process on the substrate to be processed by irradiating the substrate to be processed with an electron beam through the partition walls. A cleaning method in which the inside of the processing container is made an oxidizing gas atmosphere, and the inside of the processing container is in an oxidizing gas atmosphere, and the inside of the processing container passes through the partition from the electron beam irradiation unit. A step of irradiating an electron beam, and in the processing container Said oxidizing gas excited by Isa electron beam, said a product that adheres to a portion of the partition wall and the processing vessel are reacted, characterized in that it comprises a step of removing the product.
[0016]
(a) removing the product adhering to the partition walls and a part of the processing container in a state where the temperature of the partition walls is raised to a temperature higher than room temperature by the heating mechanism;
(b) The distance between the partition wall and the sample support is different between the annealing process of the substrate to be processed and the removal process of the product.
(c) The heating mechanism is a resistance heater or a lamp heater.
(d) The electron beam generator is an assembly of a plurality of electron beam generators.
(e) The oxidizing gas contains at least one of oxygen gas, ozone gas, and nitrous oxide gas.
[0017]
[Action]
The present invention has the following operations and effects by the above configuration.
Controlling the inside of the processing vessel connected to the electron beam generator through the partition wall to an oxidizing gas atmosphere, and effectively oxidizing and removing deposits adhering to the partition wall and the processing vessel by irradiating the electron beam Can remove the cause of dust.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a schematic configuration of a firing apparatus according to an embodiment of the present invention. The configuration of this apparatus is the same as the apparatus configuration shown in FIG. 4 in the section “Problems to be Solved by the Invention”, and the same reference numerals are given to the same configurations, and the description thereof is omitted.
[0019]
However, in this apparatus, as shown in FIG. 1, a heating mechanism 19 composed of a resistance heater or a lamp heater is provided in the sample support 11. A gas cylinder 20 filled with an oxidizing gas such as oxygen gas or nitrous oxide gas is connected to the processing vessel 8. Note that an ozonizer may be inserted between the gas cylinder 20 filled with oxygen gas and the processing vessel 8 to excite the oxygen gas to generate ozone and introduce the ozone into the processing vessel 8. In addition, a mechanism for changing the distance between the partition wall 10 and the sample support 11 is provided (not shown).
[0020]
Next, a cleaning method for removing a product (organic matter) deposited on the partition wall 10 or a part of the processing container 8 will be described in detail.
[0021]
A dummy wafer 18 was placed on the sample support 11 placed in the processing container 8 and adjusted to a reduced pressure atmosphere while introducing, for example, oxygen as an oxidizing gas from the gas cylinder 20 into the processing container 8. By introducing the electron beam 13 from the electron beam generator 9 into the processing container 8, oxygen excitons are generated inside the processing container 8. The product deposited on the partition wall 10 and a part of the processing vessel 8 is effectively oxidized by the excitons of oxygen, so that the product can be removed.
[0022]
During the cleaning process, the heating mechanism 19 provided on the sample support 11 is operated, and the partition 10 facing the sample support 11 is heated to a normal room temperature or higher so that the cleaning rate (oxidation rate) on the partition 10 is increased. It was possible to raise. FIG. 2 shows the relationship between the partition wall temperature and the cleaning speed.
[0023]
Furthermore, it was possible to perform cleaning more effectively by changing the interval between the sample support 11 and the partition wall 10 during the cleaning process. As shown in FIG. 3, it was possible to improve the cleaning speed by changing the distance between the sample support 11 and the partition wall 10. This is affected by the gas flow, the temperature of the partition walls 10, the spatial distribution of oxygen gas excited by the electron beam, and so on, so various settings are required depending on the shape and configuration of the apparatus.
[0024]
FIG. 3 shows the relationship between the interval between the sample support 11 and the partition wall 10 and the cleaning speed when the temperature of the sample support 11 is kept at 300 ° C. It was also effective to change the distance between the sample support 11 and the partition 10 during cleaning.
[0025]
Although the method for removing the film deposited when forming the SOG film has been described here, the present invention is not limited to this method, and it is not limited to this film. It was also effective for cleaning an electron beam processing apparatus applied to a dielectric constant organic resin film. Although oxygen is used as a cleaning gas, the present invention is not limited thereto, and it is sufficient to use a gas having an oxidizing effect such as ozone gas or nitrous oxide gas, or a gas in which nitrogen or argon is mixed with these gases. The effect was obtained. At that time, an oxidizing gas excited in advance by a microwave or the like may be introduced.
[0026]
In this embodiment, the dummy wafer 18 is placed on the sample support 11 to perform cleaning, but the dummy wafer is not essential.
[0027]
In addition, this invention is not limited to the said embodiment, In the range which does not deviate from the summary, it can change and implement variously.
[0028]
【The invention's effect】
As described above, according to the present invention, the inside of the processing vessel connected to the electron beam generation unit via the partition wall is controlled to an oxidizing gas atmosphere, and the inside of the partition wall and the processing vessel is attached by irradiating the electron beam. Deposits can be effectively oxidized and removed.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a firing apparatus according to an embodiment of the present invention.
FIG. 2 is a characteristic diagram showing the relationship between the partition wall temperature and the cleaning speed.
FIG. 3 is a characteristic diagram showing the relationship between the cleaning speed and the distance between the sample support base 11 and the partition wall 10 when the temperature is kept at 300 ° C.
FIG. 4 is a diagram showing a schematic configuration of a firing apparatus developed by the present invention and the like.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 8 ... Processing container 9 ... Electron beam formation part 10 ... Partition 11 ... Sample support stand 18 ... Dummy wafer 19 ... Heating mechanism 20 ... Gas cylinder

Claims (6)

A processing container, a sample support installed in the processing container, on which a substrate to be processed is placed, a heating mechanism provided on the sample support, an electron beam generator connected to the processing container, A barrier rib inserted between the processing container and the electron beam generation unit, and heating the substrate to be processed while the electron beam generation unit heats the substrate from the electron beam generation unit via the partition wall A method for cleaning a baking apparatus that performs a removal process of a product adhered to the partition walls and the processing container with respect to a baking apparatus that irradiates a line and performs an annealing process on a substrate to be processed.
Making the inside of the processing vessel into an oxidizing gas atmosphere;
Irradiating the processing container with an electron beam from the electron beam irradiation unit through the partition wall in an oxidizing gas atmosphere inside the processing container;
A step of reacting the oxidizing gas excited by the electron beam irradiated in the processing container with a product adhering to a part of the partition wall and the processing container to remove the product. A method for cleaning a baking apparatus. The firing according to claim 1, wherein the heating mechanism removes a product adhering to a part of the partition wall and the processing container in a state where the temperature of the partition wall is raised to a temperature higher than room temperature. How to clean the device. 2. The cleaning method for a baking apparatus according to claim 1, wherein a distance between the partition wall and the sample support is different between an annealing process of the substrate to be processed and a removal process of the product. The method for cleaning a baking apparatus according to claim 1, wherein the heating mechanism is a resistance heater or a lamp heater. The method for cleaning a baking apparatus according to claim 1, wherein the electron beam generator is an assembly of a plurality of electron beam generators. The method for cleaning a baking apparatus according to claim 1, wherein the oxidizing gas includes at least one of oxygen gas, ozone gas, and nitrous oxide gas.

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