JPH07176526A - Thin film forming device - Google Patents

Abstract

PURPOSE:To enable material gases to be uniform in concentration distribution in a reaction chamber just after material gases are fed to the reaction chamber and prevented from being separated from each other due to a specific gravity difference between them by a method wherein the material gases are fed to the reaction chamber through its bottom. CONSTITUTION:A mounting pad 15 is provided to the lower part of a reaction chamber 10. A ring-shaped material gas supply nozzle 16 is provided surrounding the mounting pad 15. A large number of fine holes are provided to the upper part of the gas supply nozzle 16. Material gases are made to blow upwards from them. Material gases are supplied to the reaction chamber 10 from below, whereby they can be set uniform in concentration distribution. By this setup, an anti-reflection film uniform in thickness and excellent in processability can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film manufacturing apparatus for manufacturing an antireflection film, and more particularly to a thin film forming apparatus capable of obtaining a uniform film thickness even when there are steps on a substrate.

[0002]

2. Description of the Related Art In the manufacture of semiconductors, with the increase in capacity of semiconductor memories, finer processing techniques continue to be required. A lithography technique is generally used for the fine processing.

Here, a general lithography technique will be described. A radiation sensitive resist is formed on a semiconductor substrate, and radiation is selectively irradiated so that a desired resist pattern can be obtained, and then development is performed to form a resist pattern. Using the resist pattern as a mask material, processes such as etching, ion implantation and vapor deposition are performed, and these steps are repeated to manufacture a semiconductor.

Currently, a resist pattern having a size of about 0.5 μm is being industrially put into practical use.
Further miniaturization is required. As a method of miniaturizing the resist pattern, for example, there is a method of pattern exposure by using light of a single wavelength as radiation and reducing and projecting the original image. Especially for the purpose of microfabrication, it is required to shorten the wavelength of light, and the technology of irradiating with a wavelength of 436 nm has already been established.
Development of a technique for irradiating with light in the deep ultraviolet region of m or less is under study.

Such a lithographic technique has the following problems. First, due to reflection from the substrate, radiation interference occurs in the radiation-sensitive resist film, and as a result, the amount of radiation energy imparted to the radiation-sensitive resist film changes due to fluctuations in the thickness of the radiation-sensitive resist film. It will have varying characteristics. That is, the dimension of the resist pattern obtained by the slight change in the thickness of the radiation-sensitive resist is likely to change. Further, as the wavelength of the radiation is shortened for the purpose of miniaturization of processing, radiation reflection from the substrate generally increases, and this characteristic becomes remarkable. In addition, the change in the thickness of the resist layer is caused by the characteristic change of the radiation-sensitive resist material over time or the difference between lots and the change of the coating conditions of the radiation-sensitive resist. A change in thickness occurs. As described above, the dimensional change of the resist pattern due to the change of the thickness of the resist layer reduces the process tolerance at the time of manufacturing, which is an obstacle to finer processing.

Further, when the substrate is highly reflective and the steps are arranged in a complicated manner, diffuse reflection of radiation occurs, so that the shape of the desired resist pattern tends to locally change. is there.

In order to solve such a problem, a method of suppressing reflection on the substrate is proposed. For example, a method of performing lithography after forming an antireflection film on a substrate by a vacuum thin film forming method such as plasma CVD or sputtering of a low-reflective inorganic compound, but the peeling process is complicated because it is an inorganic material This method is used only in a limited number of processes because there are some manufacturing processes that do not allow such treatment because of concerns about the influence on semiconductor characteristics.

Another method is to apply a solution in which carbon particles are dispersed onto a substrate and heat-treat it to form an antireflection film. In this case, since carbon is the main component, the difficulty of peeling and adverse effects on semiconductor characteristics when the above-described inorganic compound is used as the antireflection film are reduced, but the size of the carbon particles of the raw material is reduced. However, there is a problem that it is not possible to form a thin film having a uniform film thickness that is larger than the desired film thickness.

Similarly, a method of forming an antireflective film by providing an organic compound on a substrate and performing heat treatment can be mentioned. In that case, the heat treatment temperature is generally high, the change in semiconductor characteristics, the shape of the substrate. There is a problem that adverse effects such as changes are exerted.

Further, in any of the above methods, when a fine hole or a stepped portion of an aluminum wiring pattern has a three-dimensional shape, the wraparound property into the fine hole or the side surface of the step is poor, and uniform reflection is prevented. There was a drawback that a film could not be formed.

Therefore, in order to solve the above-mentioned problems, a thin film forming apparatus capable of forming an antireflection film having a uniform film thickness even when there is a complicated step on the substrate is mounted on the substrate to be coated. In a reaction vessel having a mounting table, exhaust means for exhausting the gas inside the reaction vessel to a predetermined degree of vacuum, inert gas supply means for supplying an inert gas into the reaction vessel, raw material gas inside the reaction vessel After the source gas supply means for supplying the catalyst and the monomer and the temperature control means for controlling the substrate to a predetermined temperature are respectively provided, the gas inside the reaction vessel is exhausted by the exhaust means to adjust to a predetermined vacuum degree. , The catalyst and the monomer are sequentially or simultaneously supplied into the reaction vessel by the raw material gas supply means, and finally the inert gas is supplied into the reaction vessel by the inert gas supply means. Devised was a thin film forming apparatus.
(See Japanese Patent Application No. 5-0294353, but this application was filed on October 28, 1993, and has not yet become a known technique.)

[0012]

However, in the thin film forming apparatus as described above, since the source gas is generally supplied from the upper part of the reaction vessel, a gas having a large specific gravity is accumulated below immediately after the supply. On the contrary, the gas with a small specific gravity accumulates in the upper part. As described above, a concentration gradient of the source gas is generated in the height direction in the reaction vessel, which causes unevenness in the film thickness.

Further, a coated substrate such as a silicon wafer is
By simply fixing it on the mounting table with a jig, the raw material gas can flow around easily, and a thin film is formed even on the peripheral edge of the back surface of the silicon wafer, impairing the flatness of the silicon wafer. There is a risk that it will become an obstacle in case of.

Furthermore, if the volume of the reaction vessel is too large,
Manufacturing cost increases due to excessive supply of the raw material gas, such as catalyst and monomer, and the raw material gas is cooled by adiabatic expansion immediately after the raw material gas is supplied, and the raw material gas is condensed on the substrate surface or is a mist-like raw material gas. Is attached to the film surface. Further, since the thin film is formed not only on the substrate surface but also on the inner surface of the reaction container, the thin film formed on the inner surface of the reaction container causes dust generation.

Therefore, an object of the present invention is to provide a thin film forming apparatus capable of manufacturing an antireflection film or the like having a uniform film thickness and excellent workability in order to solve the above-mentioned inconvenience.

[0016]

In order to solve the above problems, the present invention is directed to a reaction container having a mounting table for a substrate to be coated, and a gas inside the reaction container is exhausted to a predetermined degree of vacuum. Exhaust means, inert gas supply means for supplying an inert gas to the inside of the reaction vessel, source gas supply means for supplying a catalyst and a monomer as a source gas to the inside of the reaction vessel, and the substrate to a predetermined temperature. Temperature control means for controlling,
The gas inside the reaction vessel is exhausted by the exhaust means to adjust to a predetermined vacuum degree, and then the catalyst and the monomer are sequentially or simultaneously supplied into the reaction vessel by the raw material gas supply means, and finally the inert gas supply means. A thin film forming apparatus comprising: a control means for controlling the exhaust means, the raw material gas supply means, and the inert gas supply means so as to supply the inert gas into the reaction vessel by the raw material into the reaction vessel. The gas supply port was provided at the bottom of the reaction vessel.

Further, a jig for fixing the outer edge portion of the coating substrate by sandwiching it between the upper edge of the outer periphery of the coating substrate and the upper surface of the mounting table is provided. By providing a packing for sealing the outer edge of the coated substrate and the outside of the coated substrate in between, it is possible to prevent the raw material gas from flowing around to the back side of the substrate.

Further, the internal volume of the reaction vessel is 700c.
When it is set to be c or less, it is possible to prevent mist formation due to adiabatic expansion, and it is more preferable to provide a discharge electrode for cleaning in the reaction vessel.

[0019]

In the thin film forming apparatus configured as described above, since the raw material gas is supplied from the lower part of the reaction container, the concentration distribution in the reaction container becomes uniform immediately after the supply, and the raw material gas is separated due to the difference in specific gravity. There is nothing to do.

In the case where the packing is provided between the jig, the mounting table and the substrate to be coated, the raw material gas does not circulate to the back side of the substrate to be coated, so that the back surface of the substrate to be coated is No thin film is formed on the peripheral portion.

Further, in the case where the inner volume of the reaction vessel is set to 700 cc or less, the adiabatic expansion immediately after the supply of the raw material gas is reduced, and the excess gas is prevented from becoming mist. Further, in the case where the discharge electrode is provided in the reaction container, when a high frequency voltage is applied to the discharge electrode in a state where oxygen gas is supplied into the reaction container, a thin film formed on the inner surface of the reaction container is formed. To be removed.

[0022]

EXAMPLES Examples will be described below with reference to the drawings. As shown in FIG. 1, the thin film forming apparatus 1 includes a reaction container 10 having a mounting table 15 for a substrate A to be coated, and an exhaust unit 20 for exhausting gas inside the reaction container 10 to a predetermined vacuum level. An inert gas supply means 30 for supplying an inert gas into the reaction vessel 10, a source gas supply means 40 for supplying a catalyst and a monomer as a source gas into the reaction vessel, and the coated substrate A. Substrate temperature control means 50 for controlling the temperature of the reaction vessel 10 to a predetermined temperature, a reaction vessel temperature control means 60 for controlling the reaction vessel 10 to a predetermined temperature, the exhaust means 20, an inert gas supply means 30, a source gas supply means 40. And a control means (not shown) for controlling each of them as will be described later.

The reaction vessel 10 is, as shown in FIG.
It comprises a bottom portion 11, a body portion 12, and a lid portion 13. The inside of the body portion 12 is closed by O-rings 14 provided between the body portion 12 and the lid portion 11 and the bottom portion 13, respectively. Further, the internal volume of the reaction container 10 is preferably 700 cc or less. If the internal volume of the reaction vessel 10 is too large, the catalyst and the monomer that are the raw material gas are excessively supplied, which increases the manufacturing cost, and the raw material gas is cooled to the substrate surface by the adiabatic expansion immediately after the raw material gas is supplied. This is because problems such as the condensation of the raw material gas and the mist-like raw material gas adhering to the film surface occur.

Therefore, the reaction vessel may be, for example, as shown in FIG. As shown in FIG. 3A, the reaction container 10a includes a bottom portion 11a that shares a mounting base for the coated substrate A and a recess 13b that forms a minimum accommodation space for the coated substrate A. It is composed of the lid portion 13a, and there is no body portion such as the reaction container 10 or an independent mounting table.

Further, as shown in FIG. 2B, a groove 11b into which the O-ring 14a as a packing is fitted is formed in the bottom portion 11a, and the groove 11b is formed on the outer side of the substrate A to be coated. A large number of fine holes 11c for supplying the raw material gas are circumferentially provided.

Here, the internal volume of the reaction vessel 10 is 70 cc.
The results of comparative experiments conducted with the No. 1 and the No. 3000 cc are shown below. The polymer thin film was formed under the same conditions except that the inner volume of the reaction container was different. Also,
The pressure in the container when supplying the catalyst was 15 Torr, and the pressure in the container when supplying the monomer was 75 Torr,
The polymerization reaction time from monomer supply to exhaust is 60 seconds.

When the utilization rate of the raw material gas was examined in the state where the polymer thin films each having a film thickness of 2000 angstrom were formed, the internal volume of 70 cc was 6%, while the internal volume of 3000 cc was found. Is 1.2%,
It can be seen that the smaller the inner volume of the reaction vessel 10, the higher the utilization rate of the raw material gas. The utilization rate of the raw material gas here means the ratio of the actual film forming amount to the film forming amount when the raw material gas supplied for one silicon wafer is completely polymerized.

If the internal volume is 3000 cc,
Granular projections presumed to be caused by the raw material gas mist formed on the surface of the polymer thin film were observed, but the internal volume was 70 cc.
No such granular projections were found in the product No. 1.

The mounting table 15 is installed in the lower part of the reaction vessel 10, and a ring-shaped raw material gas supply nozzle 16 is installed around it. A large number of fine holes 16a are provided above the raw material gas supply nozzle 16,
The source gas can be blown upward.

The lower portion of the reaction vessel 10 referred to here means a portion of the height dimension of the reaction vessel 10 or less, but the raw material gas supply nozzle 16 is 1/3 of the height dimension of the reaction vessel.
It is preferably installed in the following parts. This is because if the source gas is supplied from the lower side of the reaction vessel 10 as much as possible, the concentration distribution of the source gas in the reaction vessel 10 becomes more uniform.

FIG. 4 shows the substrate A to be coated on the mounting table 15 when the source gas is supplied from the lower part of the reaction container 10 and when it is supplied from the upper part of the reaction container 10.
A thin film is formed in a state in which (a silicon wafer is cut into a rectangular shape) is set upright, and the respective film thicknesses at the height position from the mounting table 15 are examined. It can be seen that the supply from the upper portion of the container 10 is larger than that from the lower portion. The conditions are the same except that the feed position of the raw material gas is different. The pressure in the reaction vessel 10 at the time of supplying the catalyst is 15 Torr and the pressure in the reaction vessel 10 after supplying the monomer is 75 Torr.
The polymerization reaction time from the monomer supply to the exhaust was 60 seconds.

The fine holes 16a do not necessarily have to be provided above the raw material gas supply nozzle 16, but their positions need to be determined so that the direction of the raw material gas blowout includes the upward component. This is because blowing out the source gas in the upward direction has a greater effect of making the concentration distribution of the source gas in the reaction vessel 10 uniform.

Further, the fine holes 16a do not necessarily have to be formed in the raw material gas supply nozzle 16 as described above, and if they can be supplied from the lower part of the reaction vessel 10, for example,
You may form in the bottom part 11, the mounting base 15, the trunk | drum 12, etc.

As shown in FIG.
A jig 17 for fixing the coated substrate A is provided. The jig 17 is formed in a ring shape so that the peripheral edge of the disk-shaped substrate A to be coated can be pressed and fixed, and the inner surface of the jig 17 serves as packing to form the substrate A to be coated.
A groove 18 into which an O-ring 19a for pressing the peripheral edge of the substrate and an O-ring 19b for pressing the outside of the coated substrate A are fitted.
a and 18b are formed.

Therefore, when the substrate A to be coated is fixed on the mounting table 15 by the jig 17, the peripheral edge of the substrate A to be coated is completely sealed, so that the raw material gas is transferred to the substrate A to be coated A.
The formation of a thin film on the back side is prevented without wrapping around to the back side.

The packing does not necessarily have to be the two O-rings 19a and 19b as described above, but a gasket 19 having a certain width as shown in FIG.
It is also possible to use c so that it is overlapped from the outer edge of the coated substrate A to the mounting table 15. The material of the packing is not particularly limited, but fluorocarbon resin such as Viton is preferable because it does not release or store the raw material gas, and DuPont's "Kalrez" or the like is more preferable in terms of corrosion resistance.

When a polymer thin film is formed on the substrate A to be coated in the reaction container 10 as described above, the thin film also adheres to the inner surface of the reaction container 10. Therefore, as shown in FIG. 7 and FIG. 10 is provided with a discharge electrode 80, an oxygen gas cylinder 71, an oxygen gas supply pipe 72, and an opening / closing valve 73.
If the oxygen gas supply means 70 consisting of is connected, the thin film attached to the inner surface of the reaction vessel 10 can be removed by plasma cleaning.

The exhaust means 20 is, as shown in FIG.
An exhaust device 21 such as a dry pump or a rotary pump is connected to the lid 11 of the reaction container 10 by an exhaust pipe 22, and an opening / closing valve 23 is provided in the exhaust pipe 22.

The inert gas supply means 30 is formed by connecting a gas cylinder 31 filled with an inert gas such as nitrogen or helium to the reaction vessel 10 by an air supply pipe 32, and in the middle of the air supply pipe 32. An open / close valve 33 is provided.

The source gas supply means 40, as shown in FIG. 1, is a catalyst supply means 40a and a monomer supply means 40b.
And each of them is connected to the raw material gas supply nozzle 16 through the reaction vessel 10.

The catalyst supply means 40a and the monomer supply means 40b are obtained by connecting a catalyst container 41a and a monomer container 41b to the source gas supply nozzle 16 by supply pipes 42a and 42b, respectively. On the way, mass flow controllers 43a and 43b for controlling the flow rates of the catalyst and the monomers and opening / closing valves 44a and 44b are provided. The catalyst container 41a and the monomer container 41b are provided with constant temperature layers 45a and 45a.
In order to control the film formation rate, it is preferable to keep the vapor pressure constant while keeping the temperature constant at b and the like.

The substrate temperature control means 50 keeps the coating substrate A at a constant temperature by cooling the mounting table 15 and supplies cold water from the water chiller 51 to the mounting table 15. The pipe 52 is provided. The temperature of the mounting table 15 is preferably maintained at a low temperature for adsorbing the monomer on the substrate. When the temperature of the substrate is high, the film forming rate is remarkably reduced, and when it is too low, the catalyst and the monomer are condensed.
C is preferred.

The reaction vessel temperature control means 60 heats the reaction vessel 10 to prevent a thin film from adhering to the inner surface of the reaction vessel 10. A hot water pipe 62 for flowing hot water is attached. The reaction vessel 10
The temperature is preferably higher than the temperature of the mounting table 15, and more preferably set to the boiling point of the monomer used or higher.

In the thin film forming apparatus 1 configured as described above, first, the coated substrate A such as a silicon wafer is placed on the mounting table 15, and then the gas in the reaction vessel 10 is removed by the exhaust means 20. The inside of the reaction container 10 is depressurized by evacuating. When the inside of the reaction container 10 reaches a predetermined pressure, the opening / closing valve 23 is closed to stop the exhaust.

Next, the opening / closing valve 44a is opened to start supplying the catalyst to the reaction vessel 10. When the supply amount reaches a predetermined amount, the opening / closing valve 44a is closed to stop the supply of the catalyst. Then, the opening / closing valve 44b is opened to supply a predetermined amount of the monomer into the reaction vessel 10 to form a polymer thin film on the coated substrate A.

At this time, as described above, the film thickness of the formed thin film is also constant, and the thin film is not formed on the back surface side of the coated substrate A.

In this embodiment, the method of forming the polymer thin film with the exhaust stopped is described, but the polymer thin film can be formed with the exhaust continued. However, in that case, the catalyst and the monomer are simultaneously added to the reaction vessel 10.
Need to supply in.

The pressure in the reaction vessel 10 before supplying the catalyst and the monomer is preferably 1 Torr or less, and in order to prevent impurities in the atmosphere such as water from adversely affecting the film formation rate, The pressure in 10 is 0.1
It is desirable to set it to Torr or less.

The pressure inside the reaction vessel 10 at the time of supplying the catalyst and the monomer is 1 Torr in consideration of the film forming rate.
A pressure exceeding r is preferable, and it is particularly preferable to set the pressure in the range of 10 Torr to 500 Torr.
This is because if the pressure is 1 Torr or less, the film formation rate is too slow to be practical.

After the polymer thin film is formed, the opening / closing valve 2 is again provided.
3 is opened and the raw material gas remaining in the reaction vessel 10 is exhausted. After exhausting for a predetermined time, the opening / closing valve 23
Is closed to stop the exhaust, and then the opening / closing valve 33 is opened to supply an inert gas such as nitrogen gas into the reaction vessel 10 to return the inside of the reaction vessel 10 to the normal pressure. Finally, the substrate on which the polymer thin film is formed is taken out of the reaction container 10 and heat-treated. The heat treatment is effective in improving chemical resistance in the lithography process and the like, and is preferably performed in an inert gas atmosphere or under vacuum, and the heat treatment temperature is preferably 200 ° C. or lower.

In order to perform plasma cleaning on the inside of the reaction container 10 after taking out the substrate, first, the gas remaining in the reaction container 10 is exhausted by the exhaust means 20,
The pressure inside the reaction vessel 10 is reduced. At this time, the pressure in the reaction vessel 10 is preferably 0.1 Torr or less,
In particular, 0.01 Torr or less is more preferable.

Then, the reaction vessel 10 is continuously evacuated.
Oxygen gas is supplied by the oxygen gas supply means 70 until the internal pressure reaches about 1 Torr. At this time, the pressure in the reaction vessel 10 is preferably in the range of 0.5 to 3 Torr.

Next, a high frequency of 13.56 MHz is applied to the discharge electrode 80 to generate plasma in the reaction vessel 10. As a result of continuing the discharge for 1 minute, the polymer thin film adhering to the inner surface of the reaction vessel 10 and the like could be removed.

In this embodiment, the high frequency power is 5
Although it was carried out at 00 W, it may be appropriately selected within the range of 100 to 1000 W, and the discharge time may be selected according to the film thickness of the polymer thin film adhered in the reaction vessel 10.
Further, it is also possible to use CF ₄ gas as a mixture with the oxygen gas used during plasma cleaning.

[0055]

As described above, in the thin film forming apparatus of the present invention, the source gas is supplied from the lower part of the reaction vessel, so that the concentration distribution of the source gas in the reaction vessel is uniform even immediately after the source gas is supplied. Therefore, there is no unevenness in the film thickness.

Further, in the case where a packing for sealing the outer edge of the coated substrate and the outside of the coated substrate is provided between the jig, the mounting table and the coated substrate, the coated film is Since the thin film is not formed on the back surface of the substrate and the flatness is not impaired, there is no obstacle to patterning the resist on the silicon wafer, for example.

Further, if the inner volume of the reaction vessel is set to 700 cc or less, the utilization efficiency of the raw material gas is increased and the mist of the surplus gas is prevented, so that a high quality product can be manufactured at low cost. You can

If a discharge electrode is provided in the reaction vessel, the thin film attached to the inner surface of the reaction vessel can be removed by plasma cleaning.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment according to the present invention.

FIG. 2 is a schematic view showing the reaction container of the same.

FIG. 3 is a view showing a modified example of the above reaction container.

FIG. 4 is a graph showing how the film thickness varies depending on the size of the inner volume of the reaction container.

FIG. 5 is a partial cross-sectional view showing a jig for fixing a coated substrate.

FIG. 6 is a partial cross-sectional view showing a modified example of a jig for fixing a coated substrate.

FIG. 7 is a schematic view showing a state in which a discharge electrode is attached to a reaction container.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Coating-film forming apparatus 10 Reaction container 15 Mounting table 16 Raw material gas supply nozzle 16a Micropore 17 Jig 19a, 19b O-ring 20 Exhaust means 30 Inert gas supply means 40 Raw material gas supply means 50 Substrate temperature control means 60 Reaction vessel Temperature control means 70 Oxygen gas supply means 80 Discharge electrode

Claims (4)

[Claims] 1. A reaction vessel having (a) a mounting table for a substrate to be coated, (b) an exhaust means for exhausting gas inside the reaction vessel to a predetermined vacuum degree, and (c) the reaction vessel. An inert gas supply means for supplying an inert gas to the inside; (d) a source gas supply means for supplying a catalyst and a monomer as a source gas into the reaction vessel; (e) controlling the substrate to a predetermined temperature (F) The gas inside the reaction vessel is evacuated by the evacuation means to adjust to a predetermined degree of vacuum, and then the catalyst and the monomer are sequentially or simultaneously fed into the reaction vessel by the raw material gas supply means. Finally, the exhaust means for supplying an inert gas into the reaction vessel by the inert gas supply means,
A thin film forming apparatus comprising a source gas supply means and a control means for controlling an inert gas supply means, respectively, characterized in that a source gas supply port into the reaction vessel is provided in a lower portion of the reaction vessel. Thin film forming equipment. 2. A jig for sandwiching and fixing the outer edge portion of the coated substrate between the upper edge of the outer periphery of the coated substrate and the upper surface of the mounting table is provided between the jig and the mounting table and the coated substrate. The thin film forming apparatus according to claim 1, further comprising a packing for sealing the outer edge of the coating substrate and the outside of the coating substrate. 3. The thin film forming apparatus according to claim 1, wherein the inner volume of the reaction container is 700 cc or less. 4. The thin film forming apparatus according to claim 1, wherein a discharge electrode is provided in the reaction container.