JP2000173935A - Plasma treating device and gas-feeding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number and the amount of foreign matters existing on the path from a gas bomb, which is introduced in a treating chamber along the flow of treatment gas to a gas introducing vent and the number and the amount of foreign matters in the vicinity of a gas-feed opening by a method wherein the flow rate at the gas feed opening in the treating chamber of the treatment gas is reduced. SOLUTION: In order to remove residual gas between valves 26, 29 and a massflow controller 27, an exhaust pump 15 is connected to an exhaust side via a change-over valve 30, and the timing when the valves 26, 29 and the controller 27 are opened is shifted. That is, after the opening of the valve 26 is completed, the valve 29 is opened with Δt1. A command that the controller 27 is gradually opened is sent from a CPU simultaneously with the time when the opening of the valve 29 is started, or in a time difference Δt2, and a voltage is applied to an electrostatic cluck electrode with a Δt3. At this time, at least either of the valves 26 and 29 is used as a valve of a variable valve travel and the inflow rate of treatment gas into a treating chamber 21 is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a plasma processing apparatus,
More particularly, the present invention relates to a plasma processing apparatus suitable for a plasma etching apparatus, a plasma CVD apparatus, an ion implantation apparatus, a sputtering apparatus, and the like used for manufacturing a semiconductor, a liquid crystal display, and the like, and a gas supply method.

[0002]

2. Description of the Related Art Generally, a processing gas supply device for forming a film on a substrate such as a semiconductor wafer using a CVD device or performing an etching process using an etching device is generally a gas cylinder, a mass flow controller (hereinafter referred to as a mass flow controller). MFC
), A valve, a filter, and the like.

[0003]

In the prior art,
As a gas supply method during substrate processing, the MFC, valves, etc. were simultaneously opened and the processing gas was supplied to the plasma processing chamber, so that foreign matter remaining near the gas supply port or in the gas introduction path adhered to the blow-out substrate, etc. Was. Further, since the voltage was applied to the electrostatic chuck at the same timing when the MFC and the valve were turned on, foreign matter was attached to the substrate due to the dust collection effect.

In addition, there is no means for removing foreign matter near the gas supply port in the processing chamber generated during the processing.

Furthermore, there is no means for releasing foreign matter into the processing chamber during a time period other than the time of substrate processing. As a result, foreign matter adheres to the wafer, causing defects and characteristic deterioration of the processing film, resulting in quality deterioration. In particular, in a plasma CVD apparatus, a thin film adhered to the inner wall of a chamber is removed by cleaning plasma after film formation, but it cannot be removed uniformly, and a large amount of residual foreign matter is present near a gas supply port.

[0006] The residual foreign matter is introduced into the chamber by the transport of the residual foreign matter due to a sufficiently large speed fluctuation at the gas supply port, and has been attached to the wafer surface.

[0007] Focusing on the above points, the purpose is
An object of the present invention is to provide a plasma processing apparatus and a gas supply method capable of obtaining a high-quality processed substrate by reducing foreign substances adhering to a substrate surface.

[0008]

Means for Solving the Problems To solve the above problems, the present invention is provided with the following means.

(1) The flow velocity of the processing gas at the gas supply port in the processing chamber is reduced, and foreign matter and gas present in the path from the gas cylinder introduced into the processing chamber to the gas introduction port along the flow are generated in the vicinity of the gas supply port. To reduce the number and amount of foreign substances

(2) When the above-mentioned foreign matter is not processed at the time of substrate processing,
A cleaning plasma generator having a cleaning plasma generator for removal, an introduction pipe for introducing the plasma generator into a processing chamber, a switching valve, and the like.

(3) A means for supplying a clean gas in the form of an air curtain onto the upper surface of the substrate from a position where foreign matter does not adhere or hardly adheres, separately from the processing gas supply unit.

(4) A gas supply operating means for releasing residual foreign matter near the gas supply port of the plasma processing chamber and residual foreign matter in the gas introduction path into the processing chamber when the substrate is not in the processing chamber.

Regarding (1), specific means will be described below.

(5) In the gas supply unit, an MFC whose opening degree is variable with time is used, and the timing of issuing a valve opening command, the timing of the MFC opening command, and the application of a voltage to the electrostatic chuck electrode A means for arbitrarily setting the timing and the like is provided.

(6) Means for minimizing the volume (dead space) of the processing gas existing between the MFC and the valve is provided.

(7) A means for evacuating the gas path between the MFC and the valve is provided.

(8) A valve whose opening degree can be varied in addition to the operation of simply opening and closing and a valve whose Cv value is as small as possible are used.

(9) A porous filter and a gas reservoir are provided between the MFC, the valve and the processing chamber. (10) The gas supply pressure on the secondary side of the gas cylinder is 1 kgf / cm
² or less.

Since the flow rate of the processing gas at the gas supply port in the processing chamber can be reduced by employing the above-mentioned means (1), the flow from the gas cylinder introduced into the processing chamber to the gas supply port follows this flow. The number and amount of the residual foreign substances existing in the path and the residual foreign substances near the gas supply port can be reduced.

By employing the above-mentioned means (2), the source of foreign matter can be removed, so that the number and amount of foreign matter adhering to the processing substrate can be reduced.

By employing the above-mentioned means (3), the number of foreign substances adhering to the processing substrate can be reduced because foreign substances are unlikely to adhere to the substrate before processing the substrate.

By adopting the above-mentioned means (4), the number and amount of foreign particles remaining before and after the substrate processing can be reduced, so that the number and amount of foreign particles adhering to the processing substrate can be reduced.

[0023]

Embodiments of the present invention will be described below. FIG. 1 is a sectional view of a plasma processing apparatus according to a first embodiment of the present invention. Hereinafter, a plasma CVD apparatus will be described as an example.

A substrate 1 such as a wafer is placed on a substrate holder such as an electrostatic chuck 2. The electrostatic chuck 2 is fixed to the substrate holder 3. The internal electrode 4 of the electrostatic chuck is connected to a bias power supply 5 outside the processing chamber,
Are electrically connected via

The processing chamber 21 mainly includes the top plate 10, the side walls 11,
Vacuum chamber section such as processing chamber (lower) chamber 12, gate valve 13, exhaust pump such as turbo molecular pump 14, dry pump 15, vacuum exhaust section such as diaphragm vacuum gauge 16 for measuring pressure in processing chamber 21, top plate 10, an RF power supply 20 (including a matching box and a controller) connected to the substrate holder 3, a power supply unit (not shown) such as a microwave power supply, a gas nozzle 23 for introducing a processing gas to the vicinity of the substrate, and a gas reservoir 24. A filter 25 for removing foreign substances in the processing gas, a mass flow controller 27 for adjusting the flow rate or pressure, a controller power supply 28, valves 26 and 29 for controlling the presence or absence of gas flow, a switching valve 30,
CPU for controlling the power supply of the mass flow controller and controlling the solenoid valve unit (not shown) of the valve.
(Not shown), and gas supply units such as gas cylinders 31 and 32. Under appropriate conditions,
A plasma 22 is present. Although the gas introduction section shown in FIG. 1 is only one place, it is needless to say that there may be a plurality.

For the gas cylinder 31, a gas such as SiH ₄ , Ar, O ₂ gas used at the time of the film forming process is used.
The gas cylinder 32 is used at the time of the cleaning process.
NF ₃ , C ₃ F ₈ gas or the like is used.

FIG. 2 shows the structure of the gas introduction section inside the processing chamber 21.
A to E show. The cross section of the gas reservoir 24 formed on the inner circumference of the side wall 11 is, for example, about 10 mm square. Approximately 10 screw holes and small holes are formed in this. The shape of the gas reservoir and the number and shape of the gas supply ports are determined by the conductance of the flow path and the uniformity of the required gas supply amount.

FIGS. 2A and 2B show an example of the structure of the gas nozzle portion when the tapered screw 40 is used as the screw hole.
(The tapered screw is used to reduce the amount of gas leakage from the screw portion.) Inside the nozzle 41, a hole 42 is formed to uniformly supply gas into the processing chamber. And the flow rate of gas introduced from each nozzle 41 is made uniform. B has a structure in which an alumina tube 43 is placed over the gas nozzle 41 in order to improve maintainability, and only the alumina tube 43 is replaced during maintenance. C cuts the metric screw 44 on the side wall of the processing chamber,
Nozzle 41 with 5 is attached. D is
The gas introduction hole 42 is simply formed in the side wall 11. E
Indicates a gas supply ring 49.

At the tip of the gas nozzle 41, near the tip of the alumina tube 43, and near the gas introduction hole 42,
During the film forming process, the side wall 11 is exposed to the film forming plasma.
A denser film is formed as compared to the inner wall surface. Therefore, even if the cleaning process is performed,
Although cleaning can be sufficiently performed and the thin film can be removed, the foreign matter 47 (for example, AlF ₃ ) remains in the above-described portion.

The prior art will be described with reference to FIG. Since the valve 26, the valve 29, and the MFC 27 are simultaneously opened, the processing gas remaining between the valve 26, the MFC 27, and the valve 29 flows into the processing chamber 21 at a stretch.
The foreign matter 47 such as AlF ₃ remaining in the gas nozzle 41 or in the vicinity of the outlet shown in FIG. 2 was introduced into the processing chamber 21 by the jet stream shown in FIG.

In fact, when the pressure in the processing chamber was measured, a pressure increase (ΔP) indicating a large gas inflow shown in FIG. 3 was observed. It is considered that the volume of the pressure increase was introduced into the processing chamber. The inflow volume ΔV is approximately expressed by the following equation, and is equal to the residual gas volume between the valves 26, 29 and the MFC 27.

ΔV = ΔP (Torr) / 760 (Torr) × V where ΔP: pressure rise in the processing chamber V: volume of the processing chamber In the prior art, as shown in FIG. Since the substrate 1 such as a wafer is attracted by the electrostatic chuck 2 in a state where it is wound up inside the processing chamber 21 and remains, the residual foreign matter 47 is also attracted and a large amount of the residual foreign matter 47 is left on the substrate 1. Was transcribed.

In order to prevent the above problem, as one solution, the exhaust pump 15 is connected to the exhaust side via a switching valve 30 in order to remove residual gas between the valves 26 and 29 and the MFC 27. Of course, it may be connected to the intake side of the exhaust pump 15 or to a separately prepared exhaust pump.

As another solution, the timing of opening each valve and MFC is shifted. This is shown in FIG. After the opening of the valve 26, the valve 29 is opened at Δt1. MF at the same time as the start of valve 29 or at time difference Δt2
The CPU 33 issues a command to gradually open C. next,
At Δt3, a voltage is applied to the electrostatic chuck electrode. Δt
1, Δt2, Δt3 are processing chamber volume, supply gas pressure, processing chamber pressure, gas pipe diameter, valves 26, 29, MFC 27,
Residual gas volume between gas cylinders 31, 32, valve 26,
29, the optimum value is experimentally determined under the influence of the Cv value of the MFC 27. FIG. 5 shows a flow of opening the valves 26 and 29 and gradually opening the MFC 27 at the same time.
In this method, the pressure of the processing chamber 21 slightly increases due to the inflow of the residual gas between the valve 26 and the MFC 27.
The flow rate is not as large as shown in FIG. FIGS. 6, 7 and 8 show a case where at least one of the valves 26 and 29 has a variable opening degree. Since the opening degree can be changed, the flow rate of the processing gas into the processing chamber 21 can be reduced. In any case, the voltage applied to the electrode portion 4 of the electrostatic chuck 2 is applied after the pressure in the processing chamber 21 is constant, so that the amount and number of the remaining foreign particles 47 adhering to the substrate 1 are significantly reduced. It becomes possible.

In any of the above inventions, the flow rate at the gas supply port is reduced to reduce the amount and number of foreign substances introduced into the processing chamber.

The same effect is obtained simply by reducing the gas cylinders 31 and 3.
It is also achieved to some extent by reducing the lowering of the secondary gas supply pressure. At this time, the supply pressure on the secondary side of the gas cylinder is desirably 1 kgf / cm ² or less. 1 can be achieved by using a porous filter 25 as the filter 25 and by providing a gas reservoir 24 to reduce the flow velocity at the gas supply port.

Further, in order to minimize the residual gas volume between the valve and the MFC, a valve having a small dead space,
The same effect can be obtained by using an MFC, making the distance between the valve and the MFC as short as possible, and making the piping diameter between the valve and the MFC as small as possible.

Similarly, by using a valve having a very small Cv value as the valve, the flow rate of the gas can be reduced, so that the flow velocity can be reduced, and the effect of reducing the number and amount of adhered foreign substances can be obtained as described above.

FIG. 9 shows a case where a cleaning plasma device is installed outside the processing chamber in order to locally clean the residual foreign matter 47 at the tip of the gas nozzle 41. The cleaning plasma device includes a microwave power supply 50.
, A plasma chamber 53, a cleaning gas (for example, NF ₃ , C ₃ F ₈ or the like) supply unit, a switching valve 52,
It comprises a plasma reservoir 56, a plasma supply pipe 55 for supplying plasma to the vicinity of the gas nozzle 41, and the like. Since the gas nozzle 41 is exposed to the film forming plasma during the film forming process, the gas nozzle 41 becomes a denser film than the thin film such as SiO ₂ formed on the side wall. The foreign matter remains in the gas introduction hole 42 near the tip of the alumina tube 43 and the gas introduction hole 42. Film formation process using SiH ₄ →
The above-mentioned cleaning plasma is locally supplied in order to remove the residual foreign matter at the tip of the gas nozzle and inside after the cleaning process by NF ₃ or the like.

FIG. 10 is a diagram showing a state in which residual foreign matter is unlikely to be generated between the time when the substrate 1 is transported and placed on the electrostatic chuck 2 and the time when the plasma 62 is generated and the film forming process is started. Shows a device for supplying a clean gas 61 in the form of an air curtain to prevent the remaining foreign matter 47 from adhering to the substrate 1 surface. The plasma 62 is generated in a range as shown in FIG. Since the lower side of the electrostatic chuck 2 is not directly exposed to plasma, deposition of a thin film which causes foreign matter such as SiO ₂ and Al generated at the time of the cleaning process are performed.
The generation of F _{3 and the} like is sufficiently small as compared with other parts. Here, the gas reservoir 24 and the gas nozzle 41 are arranged. As a gas used as an air curtain, an ultrahigh-purity Ar, N ₂ gas or the like having an extremely small number of foreign substances is used.
This gas is constituted by a gas supply section 63 and a switching valve 64. FIG. 11 shows an AA cross section of FIG. The clean gas 61 supplied from one direction forms a flow on the wafer surface as an air curtain on the substrate, so that the transfer of the residual foreign matter 47 to the substrate 1 is prevented.

The above is a case where the present invention is applied to plasma CVD. FIG. 12 shows an example in which another application is performed for an ion implanter.

In the ion implanter, a gas such as H ₂ , Ar or the like is introduced into the ion beam 65 (for example, O ₂ + beam) immediately before the substrate 1 as a measure for preventing foreign matter from being generated by charging and discharging of a wafer to be ion-implanted. Neutralization is performed, and the substrate 1 such as a wafer is irradiated as a neutral beam. The substrate 1 is held by a substrate holding rotating body 66, and is rotated or scanned to uniformly irradiate a beam.

Since the gas is introduced at a position immediately before the wafer, in the prior art, there is a problem of adhesion of foreign matter on the wafer surface. According to the present invention, it is possible to prevent wafer contamination due to residual foreign matter.

[0044]

As described above, according to the present invention, the amount and number of foreign substances adhering to a substrate can be reduced, so that deterioration of film quality and characteristics which occur during processing such as film formation can be prevented. High quality substrates can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory cross-sectional view including a first embodiment of a plasma processing apparatus according to the present invention.

FIG. 2 is an enlarged detailed view of a gas introduction unit in FIG.

FIG. 3 is a diagram showing a gas supply operation method according to the related art.

FIG. 4 is a view showing a gas supply operation method according to the present invention.

FIG. 5 is a diagram showing a gas supply operation method according to the present invention.

FIG. 6 is a diagram showing a gas supply operation method according to the present invention.

FIG. 7 is a diagram showing a gas supply operation method according to the present invention.

FIG. 8 is a diagram showing a gas supply operation method according to the present invention.

FIG. 9 is an explanatory sectional view including a second embodiment of the plasma processing apparatus according to the present invention.

FIG. 10 is an explanatory sectional view including a third embodiment of the plasma processing apparatus according to the present invention.

FIG. 11 is a sectional view of FIG. 10;

FIG. 12 is an explanatory cross-sectional view including a fourth embodiment of the plasma processing apparatus according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Electrostatic chuck, 3 ... Substrate holder, 4 ...
Electrodes, 5: Bias power supply, 6: Current introduction terminal, 7: Connection plate, 10: Top plate, 11: Side wall, 12: Processing chamber (lower) chamber, 13: Gate valve, 14: Turbo molecular pump, 15
... Exhaust pump, 16 ... Diaphragm vacuum gauge, 20 ... RF
Power source, 21: processing chamber, 22, 62: plasma, 23, 4
1 ... gas nozzle, 24 ... gas reservoir, 25 ... filter,
26, 29, 52 ... valve, 27 ... mass flow controller, 28 ... controller power supply, 30 ... switching valve, 31, 32, 51 ... gas cylinder, 40 ... taper screw, 42 ... gas introduction hole, 43 ... alumina tube, 44 ... meter Screws, 45 O-ring, 47 residual foreign matter, 48 gas introduction ring, 50 microwave power supply, 53 plasma chamber, 55 plasma supply pipe, 61 clean gas, 65
... Ion beam, 66 ... Substrate holding rotator.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Katsumi Oyama 1-1-1, Kokubuncho, Hitachi City, Ibaraki Prefecture Inside Kokubu Plant, Hitachi, Ltd. (72) Masayuki Hachiya 1-1, Kokubuncho, Hitachi City, Ibaraki Prefecture No. 1 Inside Hitachi Kokubu Plant (72) Inventor Hiroyuki Shida 1-1-1 Kokubuncho, Hitachi City, Ibaraki Prefecture Inside Company Hitachi Kokubu Plant (72) Inventor Eiji Setoyama 1, Kokubuncho, Hitachi City, Ibaraki Prefecture No. 1-1 F-term in the Kokubu Plant of Hitachi, Ltd. (Reference) 4K029 BD01 DA04 DA09 EA04 JA05 4K030 DA06 EA03 5F004 AA14 AA15 BA04 BB28 BC03 BD04 CA01 CA02 DA17 EB08 5F045 AA08 AC01 AC02 AC11 AC15 AC16 BB14 EB06 EE01 EE20 EF03

Claims (12)

[Claims] When introducing a processing gas into a processing chamber, a gas flow device is provided between the processing gas cylinder controlled at a constant pressure and the processing chamber and installed to control the flow rate or pressure of the processing gas. , Filter, processing gas supply unit composed of a valve for controlling the flow of gas, a path for introducing the processing gas into the processing chamber, a processing chamber part having a gas supply port, and holding the substrate in the processing chamber In a plasma processing apparatus provided with a substrate holding unit, a flow rate of a processing gas at a gas supply port in a processing chamber is reduced to reduce the number of foreign substances near a gas supply port introduced into the plasma processing chamber and a gas introduction path. A plasma processing apparatus comprising a foreign matter reducing means for reducing foreign matter. 2. A cleaning plasma generating chamber, a path for introducing cleaning plasma into the processing chamber, a valve for controlling the flow of the plasma, etc., separately from the processing chamber for removing foreign substances present in the vicinity of the gas supply port. 2. The plasma processing apparatus according to claim 1, further comprising a cleaning plasma generator configured from: 3. When introducing the processing gas into the processing chamber, a valve on the processing chamber side of the mass flow controller in the middle of the processing gas introduction path is opened, and then, with a certain time delay, the valve on the mass flow controller or the gas cylinder side. And supplying a processing gas by opening the opening. 4. When introducing the processing gas into the processing chamber, the valves before and after the mass flow controller in the processing gas introduction path are opened, and thereafter, with a time delay, the opening degree of the mass flow controller is gradually increased. A processing gas supply method, comprising supplying a processing gas. 5. When introducing the processing gas into the processing chamber, the valve on the processing chamber side of the mass flow controller in the middle of the processing gas introduction path is gradually opened, and thereafter, with a certain time delay, the mass flow controller or the gas cylinder side. A process gas is supplied by gradually opening at least one of the valves. 6. When a processing gas is introduced into a processing chamber, a voltage is applied to an electrostatic chuck that holds a substrate in the processing chamber with a certain time delay with respect to the operation of a mass flow controller and a valve in the middle of the processing gas introduction path. Is applied to supply a processing gas. 7. The plasma processing apparatus according to claim 1, further comprising an exhaust unit capable of evacuating a gas path between the gas flow device and the valve. 8. The plasma processing apparatus according to claim 1, further comprising a gas reservoir between said gas flow device and said valve and a processing chamber. 9. The plasma processing apparatus according to claim 1, further comprising a porous filter in a path for introducing the processing gas into the processing chamber. 10. A gas supply method comprising supplying a clean gas in the form of an air curtain to the upper surface of a substrate separately from a processing gas at a time other than performing a plasma processing. 11. A gas for supplying foreign matter near a gas supply port of a processing chamber and residual foreign matter existing in a gas path into a processing chamber when the substrate is not in the processing chamber. Supply method. 12. The gas supply pressure on the secondary side of the gas cylinder is 1 kgf / cm ² or less.
Or the process gas supply method according to 5.