JP2001053066A - Ozone processor and ozone processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress contamination in a substrate by installing a water removal part upstream in a passage where oxygen gas flows of an ozone generation part. SOLUTION: An ozone processor has an ozone generation unit 3, a processing gas passage 4 being the passage of ozone gas generated in the unit and a processing unit 5 which is connected to the down stream side of the processing gas passage 4 and executes ozone processing of a substrate. A piping 71 supplying raw material gas formed of oxygen gas and nitrogen gas is connected to the upstream side of the ozone generation part 3, namely, a raw material gas supply port 64. A valve V1 and a water removal part 72 are installed in order in the piping 71 from the upstream side. The water removal part 72 is constituted to remove water to not less than 1 ppb by combining a filter using stainless steel and chemisorption agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ozone treatment apparatus and a method for treating a substrate using ozone.

[0002]

2. Description of the Related Art A substrate used for manufacturing a semiconductor device is provided with a film of a type improved by a treatment using activated oxygen atoms (oxygen radicals) such as a tantalum oxide (TaOx) film. There are things. Such a process for improving the film quality of the substrate is performed by an ozone generation unit using ozone (O
3) This is performed using oxygen radicals generated by generating a gas and activating the gas with an ultraviolet (UV) lamp or the like.

The above processing (ozone processing) is conventionally performed by an apparatus as shown in FIG. Reference numeral 1 denotes an ozone generation unit.
1, an ozone concentration sensor 12 and a pressure adjusting unit 13 are provided. First, a raw material gas in which oxygen and nitrogen are mixed is supplied to the ozone generator 11, where a high-frequency high voltage is applied to the raw material gas to generate ozone gas. Then, the ozone gas is sent to the processing unit 21 via the pipe 14. Here, the ozone gas is activated by ultraviolet rays from the UV lamp 22 to generate oxygen atoms (oxygen radicals), and the wafers W on the mounting table 23 are processed by the oxygen radicals. It is evacuated by a vacuum pump 24 from a pipe connected to the bottom inside.

[0004]

The nitrogen (N2) gas contained in the ozone source gas is used to prevent oxygen atoms (O) generated when oxygen is converted into ozone from returning to O2. Some of these react with the oxygen atoms to form nitrogen oxides (NOx), and the processing unit 2
Sent to 1.

However, if water adheres to the piping when the piping is disassembled due to maintenance of the equipment, NOx reacts with the water to form nitric acid, and reacts with the stainless steel constituting the piping to form chromium (Cr), iron, or the like. A metal compound such as (Fe) is generated and scatters in the ozone gas. In the future, as semiconductor devices become finer and thinner, chromium,
Even a small amount of a metal compound such as iron is not preferable because it causes a reduction in the quality of the semiconductor device.

Japanese Patent Application Laid-Open No. 6-163480 describes the use of PTFE (polytetrafluoroethylene: trade name: Teflon, etc.) which is not corroded by nitric acid. If water is adsorbed on the PTFE inside the pipe, it takes a considerably long time to dry. If the moisture adhering to the PTFE is not sufficiently dried, the moisture is carried into the processing gas to generate nitric acid. If the chamber of the processing unit 21 is stainless steel, a metal compound such as chromium or iron is used. Is generated.

Further, Japanese Patent Application Laid-Open No. Hei 8-117068 discloses that
It is described that aluminum or nickel is used. However, if the chamber of the processing unit 21 is made of stainless steel, a similar problem occurs. Even if the material is made of such a material, corrosion is unavoidable, and also causes contamination of the wafer W.

[0008] Furthermore, if the moisture concentration in the high-purity N2 gas is negligible, it cannot be avoided in the O2 gas in a small amount during the production process, and this moisture reacts with NOx. And produce nitric acid. Further, since the gas flow path portion of the ozone concentration sensor 12 is made of a metal such as stainless steel, if nitric acid is generated, it may corrode and cause contamination of the wafer W.

In view of the circumstances described above, an object of the present invention is to provide an ozone treatment apparatus and an ozone treatment method which suppress the generation of contamination on a substrate.

[0010]

An ozone processing apparatus according to the present invention supplies a raw material gas containing at least oxygen gas to an ozone generating section, and applies the ozone generated here to a substrate via a processing gas flow path. An apparatus for supplying a processed processing vessel to the substrate and performing processing on the substrate is characterized in that a moisture removing section is provided at least in a flow path where oxygen gas flows upstream of the ozone generating section. Another invention is
Means is provided for supplying the heated dry gas into at least the processing gas flow path downstream of the ozone generation unit, and drying the processing gas flow path with the drying gas before processing the substrate. Still another invention relates to an ozone treatment apparatus,
The processing gas flow path is provided with a branch path whose branch end is not connected to the processing vessel, and an ozone concentration meter for measuring the concentration of ozone is provided in the branch path.
In this case, the processing gas flow path has a double structure in which an outer pipe is provided via a space outside the inner pipe made of a non-metal, and an inert gas is provided in a space between the inner pipe and the outer pipe. And a means for discharging the inert gas. In the above invention, for example, an ozone activating means for applying energy to the ozone gas to activate the ozone gas, for example, an ultraviolet irradiation means or a heating means is used.

In the ozone treatment method according to the present invention, a step of opening a processing gas flow path to the atmosphere for maintenance of the apparatus, and after assembling the ozone processing apparatus, heating and drying the processing gas flow path. And a step of supplying ozone to the processing container and thereafter performing ozone treatment on the substrate.

[0012]

FIG. 1 is a schematic view showing an embodiment of an ozone treatment apparatus according to the present invention. This apparatus includes an ozone generation unit 3, a processing gas flow path 4 that is a flow path of ozone gas generated here, and a processing unit 5 connected to the downstream side of the processing gas flow path 4 and performing ozone processing on a substrate. Have. The ozone generation unit 3 has a configuration in which an internal device is surrounded by a housing 31, and an exhaust pipe 32 connected to a factory exhaust path (not shown) is provided on an upper wall surface of the housing 31. An ozone generator 33 is provided inside the housing 31.
And a pressure regulator 34 are provided via a pipe 35, and a branch path 36 is provided in the middle of the pipe 35.
The pressure adjusting unit 34 is made of a nonmetallic material having corrosion resistance to NOx, for example, PTFE. A flow meter 37 and an ozone concentration meter 38 are interposed in the branch passage 36, and the branch end thereof is configured to be able to discharge to, for example, the factory exhaust passage.

FIG. 2 is an explanatory view of the ozone generator 33.
(A) is a plan view and (b) is a side sectional view. The ozone generator 33 is configured so that the upper and lower sides of a gasket 61 made of a fluorine-based rubber are sandwiched between a pair of electrodes 62 and 63 each having a contact surface of a raw material gas coated with ceramic. A supply port 64 and a processing gas outlet 65 are provided, and the processing gas outlet 65 is connected to the pipe 35. Electrode 6
A high-frequency voltage is applied from a high-frequency power supply 66 between the terminals 2 and 63, and this voltage is controlled by a voltage controller 67. On the other hand, the output of the ozone concentration meter 38 (the detected value of the ozone concentration) is input to the voltage controller 67, and the magnitude of the high-frequency voltage applied between the electrodes 62 and 63 according to the deviation between the detected value of the ozone concentration and the set value. Is controlled.
Since the ozone concentration depends on the magnitude of the voltage, the ozone concentration is controlled so that the ozone concentration becomes a set value as a result.

An oxygen gas (O2) and a nitrogen gas (N
2) is connected to a pipe 71 for supplying a raw material gas, and the pipe 71 is provided with a valve V1 and a moisture removing section 72 in order from the upstream side. The upstream side of the valve V1 in the pipe 71 is connected to an oxygen gas supply pipe 71a and a nitrogen gas supply pipe 71b. As the ratio of the source gas, for example, a mixed gas in which oxygen is 99.5% and nitrogen is 0.5% is used.

The water removing section 72 is constructed so as to be able to remove water to, for example, 1 ppb or less by combining a filter using stainless steel and a chemical adsorbent, for example, a product name “Wafer Pure Mega” manufactured by Nippon Millipore Co., Ltd. Line "can be used. A pipe 73 for supplying a dry gas to the processing gas flow path 4 via the ozone generation unit 3 is connected between the ozone generation unit 3 and the water removing unit 72 in the pipe 71. The pipe 73 is connected to a supply source of a dry gas (not shown) via a valve V2. As the dry gas, a gas obtained by heating an inert gas such as nitrogen and argon to about 180 ° C. is used.

In the processing gas flow path 4, a portion between the ozone generation unit 3 and the valve V3 provided near the processing gas supply port of the processing unit 5 is a double pipe comprising an inner pipe 41 and an outer pipe 42. The space between the inner tube 41 and the outer tube 42 communicates with the inside of the housing 31 via a hole 43 formed in the side wall of the housing 31. On the other hand, the downstream side of the processing gas flow path 4 is branched at a location near the valve V3, and the branch end is connected to the exhaust pipe 8 of the processing unit 5 via the valve V4 to form a bypass 44. . For example, valves V3 and V4
, Pipes 45a and 45b for supplying inert gas to the space between the outer pipe 42 and the inner pipe 41 are provided with valves V5 and V5.
Each is connected via V6. Note that, for example, nitrogen gas is used as the inert gas.

The inner tube 41 is made of a nonmetallic material having corrosion resistance to NOx, for example, PTFE, and the outer tube 42 is made of, for example, stainless steel. By adopting such a configuration, it is possible to prevent the ozone gas from leaking into the work area by the outer tube 42 even if the gas leaks from the inner tube 41, and the inert gas is supplied to the space between the inner tube 41 and the outer tube 42. Is supplied, and flows out of the exhaust pipe 32 through the inside of the housing 31 of the ozone generation unit 3, so that high safety is ensured.

FIG. 3 is a vertical sectional view of the processing unit 5. Reference numeral 51 denotes a processing container formed of a vacuum chamber,
A mounting table 52 is provided at the center of the bottom in the processing chamber 51, and the wafer W is mounted on the upper surface (mounting surface) thereof.
Near the mounting surface inside the mounting table 52, the wafer W on the mounting surface
A heating means for heating the heater, for example, a heater 53 composed of a resistance heating element is embedded and connected to a power supply unit (not shown). A UV lamp 54, which is an ultraviolet irradiation means for activating a processing gas (ozone), is provided on an upper side facing the mounting surface, and is provided through a transmission window 55 made of, for example, quartz on a lower side. The processing container 51 is configured to irradiate ultraviolet rays. A gate valve 56 for loading / unloading the wafer W is provided on the side wall surface of the processing container 51.
Is provided. An exhaust pipe 8 is connected near the bottom surface of the processing container 51, and a vacuum pump 81 is connected to the exhaust pipe 8 via a valve V7. The valve V7
Is provided so as to be located on the upstream side closer to the processing unit 5 than the place where the aforementioned detour 44 is connected to the exhaust pipe 8.

Next, the operation of the above-described apparatus will be described. The processing step of performing ozone treatment on the substrate and the drying step of the apparatus performed after maintenance of the apparatus will be described separately.

First, the processing steps will be described.
1, the raw material gas supplied from the pipe 71 is supplied to the ozone generator 33 through the moisture removing unit 72. The oxygen gas contained in this source gas usually has a purity of 99.995.
%, And the remaining 0.005% contains moisture. Therefore, the moisture is removed by passing the moisture through the moisture removing section 72 to increase the purity of the oxygen gas. Here, since the water removing section 72 is provided upstream of the ozone generating section 33, NOx generated when ozone is generated in the ozone generating section 33 reacts with water contained in the raw material gas to form nitric acid. And metal materials such as aluminum and stainless steel used for the inner wall surface of the processing unit 5 are prevented from being corroded.

For example, 8% by volume of the oxygen gas in the raw material gas is changed to the ozone gas by the voltage applied in the ozone generating section 3. The processing gas containing ozone generated in this manner is sent to the pressure adjusting unit 34 via the pipe 35. The inside of the ozone generating section 33 is adjusted to a pressurized atmosphere of about 0.1 MPa (G). However, since the process pressure in the processing unit 5 is a reduced pressure atmosphere of, for example, about 5 kPa (A), the pressure adjusting section 34 The pressure of the process gas is adjusted.

Here, the processing gas flows out of the ozone generator 33 at, for example, 10 liters / minute, and a part thereof is, for example, 500 liters.
A flow rate of about cc / min flows to the branch path 36 side, and the flow meter 37
And exhausted to the outside via the concentration meter 38. Fork 36
The concentration of ozone in the processing gas flowing through is measured by the densitometer 38, and based on the measured value, the voltage in the ozone generator 33 is controlled as described above.

A metal material such as stainless steel is generally used for the concentration meter 38. As shown in the present embodiment, these flow meters (for example, PTFE 37) and a concentration meter 38, and the processing gas for measurement flowing through the branch path 36 is prevented from flowing into the processing unit 5, so that the metal when nitric acid is generated as described above. Corrosion can be prevented from adversely affecting the wafer W. The flow meter 37 also has the effect of preventing the backflow of the processing gas, further enhancing the above effect.

After the supply of the raw material gas is started, the valve V3 is closed and the valve V4 is opened until the ozone generation amount is stabilized, and the processing gas is exhausted from the bypass 44 to the exhaust pipe 8, and then the valves V3 and V4 are opened. Switching to process gas 51
Supply to The wafer W, which is a substrate, has been mounted on the mounting table 52 by this time, and is modified (annealed) by oxygen radicals generated by activating ozone by ultraviolet energy from the UV lamp 54. Here, for example, if the film quality of the tantalum oxide film (TaOx) is to be improved, the oxygen radicals enter the gaps in the tantalum oxide film (TaOx) formed on the surface of the wafer W and become oxygen ions. And oxygen ions form a chemically stable structure in the film, resulting in improved film quality.

The conditions of this annealing process are controlled by a control unit (not shown). For example, the irradiation time of the UV lamp is determined in accordance with the supply amount of ozone, and at the same time, the heat generation of the resistance heater is controlled.
The reforming process is performed so that the set temperature is selected within the range of 800 ° C. In this example, the heater 53 and the UV lamp 54 can be used together as the ozone activating means, but either one may be used.

Next, the drying process of the apparatus according to the present embodiment will be described in detail. In this step, for example, the ozone generation unit 3 and the processing gas flow path 4 are separated to open the processing gas flow path 4 to the atmosphere for maintenance. Adheres, so that a drying gas is caused to flow through the moisture adhering portion to attempt drying. Specifically, first, the valve V2 and the valve V4 are opened with the valve V1 and the valve V3 closed, and the pipe 73 is opened.
From the primary side of the ozone generation unit 3 and is discharged from the ozone generation unit 3 to the exhaust pipe 8 via the inner pipe 41 and the bypass 44. . The supply of the drying gas is performed, for example, for about one hour. If the processing gas flow path 4 is heated in this manner, the moisture adhering to the processing gas flow path 4 during maintenance is quickly evaporated. For example, when a porous material such as PTFE is used for the inner tube 41, moisture enters into the holes, so that a dry gas is flowed into the inner tube 41 to allow the inner tube 41 to flow.
It is effective to directly heat the gas, the processing gas flow path 4 can be dried in a short time, and the operation efficiency of the apparatus can be improved. Note that the heated dry gas may be supplied into the inner pipe 41 from immediately downstream of the ozone generation unit 3.

An inert gas supplied from the pipe 45 to the space between the inner pipe 41 and the outer pipe 42 may be heated, or a heating means such as a tape heater may be provided around the outer pipe 42 or the inner pipe 41. And indirectly conduct heat to make the inner tube 41
May be dried, and these methods may be used in combination with the above-mentioned method of drying.

As described above, according to the present embodiment, since the water removing section 72 is provided on the upstream side of the ozone generating section 33, the amount of water in the processing gas is made extremely small or substantially zero. Therefore, even if NOx is contained, the generation of nitric acid is suppressed, so that corrosion of the inner wall of the processing container 51 is suppressed, and contamination of the wafer W is reduced. And as described above, it is unavoidable that a small amount of water is mixed in the oxygen from the oxygen gas supply source. On the other hand, in the ozone treatment device, a small amount of water causes metal corrosion, so this technique is an effective means. is there. The processing gas flow path 4 may have a single-tube structure made of, for example, stainless steel. Even in this case, it is effective because corrosion is suppressed.

Further, by providing an apparatus using a metal having a possibility of corrosion, such as a concentration meter 38, in the branch path 36 of the processing gas, contamination of the wafer W due to metal corrosion can be suppressed. After the maintenance, the heated dry gas is flown into the processing gas flow path 4, so that the moisture that has entered the pores of the porous PTFE can be quickly evaporated. By exhausting, moisture does not flow into the processing unit 5. After drying, it is allowed to flow into the processing unit 5 via the valve V3,
The whole including the processing unit 5 can be dried.

In the above, the water removing section 72 may be provided in the supply path 72a for the oxygen gas. As a part of the raw material gas, CO gas may be used in place of nitrogen gas. In this case, it is necessary to remove water because CO2 is expected to be generated.

The processing unit 5 described above may be configured as shown in FIG. The processing unit 5 includes a processing container 90
A rotatable heating lamp 91 serving as a heating means is provided below
Are provided with a UV lamp 92 as an ultraviolet irradiation means on the upper side. Although the processing vessel 5 is not shown,
An exhaust port is provided at the bottom. As the heating lamp 91, for example, a halogen lamp or an arc lamp is used. 93 in the figure
Is a mounting table for the wafer W, and 94 and 95 are transmission windows made of, for example, quartz. In such an embodiment, the heating lamp 91 and the UV lamp 92 can be used together as the ozone activating means, but either one may be used, for example, from 400 ° C. to 800 ° C. By performing the ozone treatment at the selected set temperature, the gate oxide film on the surface of the wafer W is modified.

[0032]

According to the present invention, in processing a substrate using ozone gas, it is possible to suppress the occurrence of corrosion in the gas flow path and the processing container due to components in the processing gas, and to reduce contamination of the substrate. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an ozone treatment apparatus for carrying out the present invention.

FIG. 2 is a plan view and a longitudinal sectional view of an ozone generation unit.

FIG. 3 is a vertical sectional view of a processing unit for performing ozone processing on a substrate.

FIG. 4 is a longitudinal sectional view showing another embodiment of the processing unit.

FIG. 5 is a schematic explanatory view showing a conventional ozone treatment apparatus.

[Explanation of symbols]

 W wafer 1 Ozone generation unit 11 Ozone generation unit 12 Sensor 13 Pressure adjustment unit 14 Pipe 21 Processing unit 22 UV lamp 23 Mounting table 3 Ozone generation unit 33 Ozone generation unit 34 Pressure adjustment unit 36 Branch line 37 Flow meter 38 Ozone concentration meter 4 Processing gas flow path 41 Inner pipe 42 Outer pipe 43 Hole 44 Detour 5 Processing unit 51 Processing container 52 Mounting table 53 Heater 54 UV lamp 61 Gasket 62, 63 Electrode 67 Voltage controller 71, 73 Pipe 72 Moisture remover 8 Evacuation tube

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D052 AA02 CA01 FA01 GA03 GB03 4G042 AA07 CA01 CB09 CE04 5F004 AA16 BA19 BB05 BB18 BC08 BD04 CA01 DA25 DA26 DA27 5F045 AB31 AC11 BB10 BB14 EC07 EC08 EC09 EE14 EK10 HA06 HA06

Claims (8)

[Claims] 1. A source gas containing at least oxygen gas is supplied to an ozone generator, and the generated ozone gas is supplied to a processing vessel on which a substrate is mounted via a processing gas flow path. An ozone treatment apparatus characterized in that a water removal unit is provided at least in a flow path of an oxygen gas upstream of an ozone generation unit. 2. An apparatus for supplying a raw material gas to an ozone generating section, supplying the generated ozone gas to a processing vessel on which a substrate is mounted via a processing gas flow path, and performing processing on the substrate. Wherein a means for supplying a heated drying gas to at least a processing gas flow path on the downstream side of the ozone generation unit is provided, and the processing gas flow path is dried by the drying gas before processing the substrate. Ozone treatment equipment. 3. The processing gas flow path has a double structure in which an outer tube is provided outside of an inner tube made of a non-metal through a space, and an inert space is provided between the inner tube and the outer tube. 3. An ozone treatment apparatus according to claim 2, further comprising means for supplying gas and means for discharging said inert gas. 4. An apparatus for supplying a raw material gas to an ozone generating section, supplying the generated ozone gas to a processing vessel on which a substrate is mounted via a processing gas flow path, and performing processing on the substrate. The ozone according to any one of claims 1 to 3, further comprising: a branch path branched from the processing gas flow path, the branch end of which is not connected to the processing vessel; and an ozone concentration meter provided in the branch path for measuring the concentration of ozone. Processing equipment. 5. The ozone treatment apparatus according to claim 1, further comprising an ozone activating unit for activating the ozone gas by adding energy thereto. 6. An ozone treatment apparatus according to claim 5, wherein said ozone activating means includes an ultraviolet irradiation means. 7. The ozone treatment apparatus according to claim 5, wherein the ozone activating means includes a heating means. 8. An apparatus for supplying a raw material gas to an ozone generating section, supplying the generated ozone gas to a processing vessel on which a substrate is mounted via a processing gas flow path, and performing processing on the substrate. A step of opening the processing gas flow path to the atmosphere for maintenance, a step of heating and drying the processing gas flow path after assembling the ozone processing apparatus, and then supplying ozone to the processing container and Performing an ozone treatment on the ozone.