JPH11329336A - Ion implanter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize plasma potential to heighten stability of ion beam current measurement by a Faraday device, in a device performing both ion implantation into a substrate, and generation of plasma in the area including the vicinity of the surface of the substrate. SOLUTION: A cylindrical lining electrode 32a is arranged along the inside wall of a vacuum container 8 so as to cover the inside wall in the area from the periphery of a substrate holder 12 to the vicinity of a mounting hole 9 of an ion source 2. The lining electrode 32a is electrically insulated from the vacuum container 8 and supported by insulators 40. Further, the lining electrode 32a is impressed with negative direct-current voltage by a direct-current power supply 44.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for irradiating a substrate with an ion beam to perform ion implantation, a Faraday apparatus for measuring a beam current of the ion beam, and a plasma generation in a region including the vicinity of the surface of the substrate. More specifically, the present invention relates to a means for stabilizing the potential of plasma and improving the stability of ion beam current measurement by a Faraday apparatus.

[0002]

2. Description of the Related Art A conventional example of this type of ion implantation apparatus is shown in FIG.
Shown in The ion implantation apparatus includes a vacuum container 8 that is evacuated by a vacuum exhaust device (not shown), and a substrate holder that is provided in the vacuum container 8 and that holds a substrate (for example, a semiconductor substrate or a glass substrate for a liquid crystal display) 10. An ion source 2 is provided above the vacuum vessel 8 and irradiates the substrate 10 on the substrate holder 12 with an ion beam 6 having a larger area (larger area). The cross-sectional shape of the ion beam 6 is, for example, circular in accordance with the shape of the substrate 10.

[0003] An ion source gas 4 is introduced into the ion source 2 through, for example, a gas inlet 3, and the ion source gas 4 is ionized to extract an ion beam 6. In this example, the ion beam 6 extracted from the ion source 2 is directly irradiated onto the substrate 10 without passing through the mass separator to perform ion implantation. The same applies to the ion implantation apparatus shown in FIGS. 1 and 3 described later. Such an ion implantation apparatus is also called a non-mass separation type ion implantation apparatus or an ion doping apparatus.
The vacuum vessel 8 and the substrate holder 12 are electrically grounded in this example.

In the vacuum vessel 8, at a position near the substrate holder 12 and avoiding the substrate 10, specifically, in this example, near the rear side of the substrate holder 12, the ion source 2 transfers the substrate 10 to the substrate 10. A Faraday device 16 that receives a part of the irradiated ion beam 6 and measures the beam current is provided. The beam current measured by the Faraday device 16 is used for, for example, measuring the ion implantation amount (dose amount) into the substrate 10 by integrating the beam current with the current integrator 18 over time.

Further, in this ion implantation apparatus, the degree of vacuum (gas pressure) near the substrate 10 at the time of ion implantation is set to 10 ^-4 to 1 in order to prevent charge-up (charging phenomenon) of the substrate 10.
The substrate 10 on the substrate holder 12 is kept at 0 ^-5 Torr, and the ion beam 6 extracted from the ion source 2 collides with atmospheric gas molecules to ionize the gas.
Means for generating the plasma 14 in a region including the vicinity of the surface. That is, the ion source 2 also serves as a means for generating the plasma 14 in this example. The atmosphere gas is mainly the ion source gas 4 leaking from the ion source 2 into the vacuum vessel 8.

When the substrate 10 is irradiated with the ion beam 6,
Positive charges of ions (all ions mean positive ions in this specification) in the ion beam 6 accumulate on the surface of the substrate 10, and particularly when the substrate 10 is non-conductive, charge-up occurs to cause various charges. Although it causes a defect, the substrate 1
When the plasma 14 is generated near the surface of the
Since the electrons in 4 are attracted by the positive charges on the substrate surface and supplied to the substrate 10 to neutralize the positive charges, the charge-up of the substrate 10 can be prevented.

[0007]

The above-mentioned Faraday device 1
Numeral 6 generally suppresses the flow of charged particles other than the ion beam 6 to be measured, specifically, the flow of electrons or ions from the plasma 14, so that no error occurs in the beam current measurement of the ion beam 6. A configuration is employed. One example is shown in FIG.

In the Faraday device 16, a mask 22 is provided at the entrance of the container 20, two suppression electrodes 23 and 24 are provided at the back of the mask 22, and a Faraday cup 26 is further provided at the back.
It has a structure where is arranged. A positive suppression voltage is applied to the suppression electrode 23 from the suppression power supply 28, and a negative suppression voltage is applied to the suppression electrode 24 from the suppression power supply 30. The positive suppression electrode 23 suppresses ions from flowing in from the upstream side. The negative suppression electrode 24 suppresses the inflow of electrons from the upstream side and the secondary electrons from the Faraday cup 26 from jumping out to the upstream side. Thereby, the beam current of the ion beam 6 can be accurately measured. In addition,
Although the positive suppression electrode 23 may not be provided in some cases, the provision of the positive suppression electrode 23 can also suppress the inflow of ions, so that the beam current measurement becomes more accurate.

However, the plasma 14 contains neutral molecules or atoms formed by decomposing the ion source gas 4 in addition to the charged particles. The molecules or atoms are deposited on the inner wall of the vacuum vessel 8, particularly on the inner wall facing the region where the plasma 14 is generated, so that a film is formed. In the case of this example, since the density of the plasma 14 is particularly high in the space where the ion beam 6 travels, more films are deposited on the inner wall at the periphery of the space where the ion beam 6 travels.

For example, in order to generate ions containing boron for producing a thin film transistor (TFT) constituting a liquid crystal display, diborane (B) is used as an ion source gas 4.
_{When 2} H ₆ ) gas or its hydrogen dilution gas is used, diborane ions B ₂ H _x ⁺ (x = 0 to 6) and hydrogen ions H _x ⁺
(X = 1 to 2) and the collision and decomposition of diborane B ₂ H ₆ molecules deposit a boron thin film on the inner wall of the vacuum vessel 8.

It has been found that the potential of the plasma 14 changes depending on whether such an insulating film such as a boron thin film is deposited on the inner wall of the vacuum vessel 8 or not. Specifically, the potential of the plasma 14 which was slightly positive with respect to the ground potential becomes higher to the positive potential side when the film is deposited on the inner wall of the vacuum vessel 8.

It is considered that the reason is as follows. That is, the potential of the plasma 14 is simply determined by the difference between the amount of electrons and the amount of ions incident from the plasma 14 on an object surrounding the plasma 14 (in this case, the vacuum vessel 8). Has a higher mobility and the amount of incident electrons is larger, so that the plasma potential becomes a positive potential with respect to the vacuum vessel 8 at the ground potential. In this case, when no film is deposited on the inner wall of the vacuum vessel 8, the plasma 14
Secondary electrons are emitted from the vacuum vessel 8 in accordance with the incidence of ions from the plasma, and the secondary electrons jump into the plasma 14, so that the secondary electrons cancel the positive potential of the plasma and suppress the rise of the plasma potential. . As a result, the potential of the plasma becomes slightly positive as described above.

However, when the above-mentioned insulating film is deposited on the inner wall of the vacuum vessel 8, even if ions are incident on the insulating film from the plasma 14, the insulating film becomes more secondary than the inner wall of the metal vacuum vessel. Since the amount of emitted electrons is much smaller, the action of the secondary electrons to suppress the increase in plasma potential is weakened, and it is considered that this causes the plasma potential to increase.
Even if the conductive film is deposited, the amount of secondary electron emission is somewhat reduced, but the conductive film can freely move electrons and replenish electrons, so it is difficult to move electrons and there is almost no replenishment of electrons. The decrease in the amount of secondary electron emission is far less than that of the insulating film. Therefore, the above-mentioned phenomenon becomes particularly remarkable when the deposited film is an insulating film.

As a result, as the plasma potential increases,
The energy of the ions in the plasma 14 increases, and the ions exceed the positive suppression voltage applied to the suppression electrode 23 of the Faraday device 16 and enter the Faraday device 16 (more specifically, into the Faraday cup 26). 3) The ion beam 6 comes to flow, and an error occurs in the measurement of the beam current of the ion beam 6. Consequently, for example, an error also occurs in controlling the injection amount into the substrate 10 based on the beam current measurement by the Faraday device 16. In this case, if the positive suppression voltage applied to the suppression electrode 23 is too high in order to suppress the inflow of ions from the plasma 14,
Since the secondary electrons emitted from the Faraday cup 26 flow into the suppression electrode 23 to cause a measurement error, the positive suppression voltage applied to the suppression electrode 23 cannot be made too high.

The collision between the plasma 14 and gas molecules
The film deposition rate due to decomposition can be simply stated as (gas concentration)
² × (gas pressure) It is proportional to ² × (ion beam current). Therefore, for example, if the condition of the ion source gas 4 introduced into the ion source 2 is changed in order to change the beam current of the ion beam 6 extracted from the ion source, the beam generated by the Faraday device 16 with the elapse of operation time The time at which the current measurement begins to change significantly changes. More specifically, for example, if the concentration or flow rate of the ion source gas 4 introduced into the ion source 2 is increased in order to increase the beam current of the ion beam 6 extracted from the ion source 2, The concentration and pressure of the gas leaking into the inside 8 also increase, thereby increasing the film deposition rate on the inner wall of the vacuum vessel, and shortening the time when the beam current measurement by the Faraday device 16 starts to have an adverse effect.

Since the ion implantation into the substrate 10 and the generation of plasma in a region including the vicinity of the surface of the substrate 10 are used in combination, the above-mentioned problem is caused by that the atmosphere gas is generated by the ion beam 6 as in the above-described example. In addition to the case where a means for converting a gas is used, there is also a case where a means for generating a plasma in a region including the vicinity of the surface of the substrate by ionizing a gas by discharge decomposition by high-frequency discharge or the like is used.

Therefore, the present invention provides an apparatus that combines ion implantation into a substrate and generation of plasma in a region including the vicinity of the surface of the substrate by stabilizing the plasma potential and measuring the ion beam current by a Faraday apparatus. The main purpose is to increase the stability of

[0018]

According to the present invention, there is provided an ion implantation apparatus which is electrically insulated from a wall for generating plasma as described above so as to separate the wall from a wall of the vacuum vessel facing the region for generating plasma. And a DC power supply for applying a negative DC voltage to the lining electrode.

By applying a negative DC voltage from a DC power supply to the lining electrode, it is possible to suppress a rise in plasma potential with the elapse of operation time and to stabilize the plasma potential. The reason is as follows. That is, as described above, the potential of the plasma is determined by the relative relationship with the potential of the object surrounding the plasma. In other words, the potential of the object surrounding the plasma V _0, when the potential difference between the object and the plasma and [Delta] V, potential V _P of the plasma is represented by the following formula.

[0020]

## EQU1 ## V _P = V ₀ + ΔV

In the conventional example, since the object surrounding the plasma is a vacuum vessel at the ground potential, the above V ₀ = 0 and V _P =
ΔV. In contrast, the provision of the lining electrodes as described above, potential V _P of the plasma consists of potential V ₀ The lining electrode only up potential [Delta] V. Therefore, when the potential V ₀ which is applied a negative DC voltage to the lining electrode negative, that amount can lower the plasma potential V _P.

As a result, the influence of the plasma on the Faraday device is stabilized, and the stability of the ion beam current measurement by the Faraday device can be improved.

[0023]

FIG. 1 is a longitudinal sectional view showing an example of an ion implantation apparatus according to the present invention. Parts that are the same as or correspond to those in the conventional example of FIG. 7 are denoted by the same reference numerals, and differences from the conventional example will be mainly described below.

This ion implantation apparatus is an improvement of the ion implantation apparatus shown in FIG. 7, and includes a region in which a plasma 14 is generated by colliding an ion beam 6 with atmospheric gas molecules in a vacuum vessel 8 and a region in which a plasma 14 is generated. A planar lining electrode 32a is arranged electrically insulated from the vacuum container 8 so as to partition between the wall surface of the vacuum container 8 and the facing wall surface. The lining electrode 32a may be a cylindrical electrode or a combination of plate electrodes.

More specifically, in this example, the density of the plasma 14 is particularly high in the space where the ion beam 6 travels from the ion source 2 toward the substrate 10 on the substrate holder 12 as described above. A cylindrical lining electrode 32 is provided so as to cover the inner wall of the vacuum vessel around the space in which the vehicle 6 runs.
a is arranged along the inner wall of the vacuum vessel 8. More specifically, a cylindrical lining electrode 32a is arranged along the inner wall of the vacuum vessel 8 so as to cover the inner wall of the vacuum vessel in a region from the vicinity of the substrate holder 12 to the vicinity of the mounting opening 9 of the ion source 2. ing. Moreover, in this example, the lining electrode 3
The upper portion of 2a is inserted to the vicinity of a later-described ground electrode of the ion source 2. In this example, the lining electrode 32a is supported electrically insulated from the inner wall of the vacuum vessel 8 by the insulator 40.

Further, a DC power supply 44 for applying a negative DC voltage to the lining electrode 32a is provided outside the vacuum vessel 8. In this specific example, a changeover switch 42, a DC power supply 44, and a high-frequency power supply 46 are provided outside the vacuum vessel 8, and the lining electrode 32a is changed by the changeover switch 42 between the negative electrode of the DC power supply 44 and one of the high-frequency power supply 46. The connection is selectively switched to the output end side. The positive terminal of the DC power supply 44 and the other output terminal of the high frequency power supply 46 are grounded.

The magnitude of the output voltage of the DC power supply 44 may be, for example, in the range of about 10V to 200V. This is because the potential of the plasma 14 rises at most 150 V
Since it is experimentally confirmed that the voltage rises only to the extent, the potential of the plasma 14 can be sufficiently controlled by setting the output voltage of the DC power supply 44 as described above. Although the DC power supply 44 may be of a fixed output voltage, a variable output voltage as in this example is preferable because the controllability of the potential of the plasma 14 is excellent.

By applying a negative DC voltage of, for example, about -10 V to -200 V from the DC power supply 44 to the lining electrode 32a, an increase in the potential of the plasma 14 due to the elapse of the operation time of the ion implantation apparatus is suppressed. In addition, the potential of the plasma 14 can be stabilized. The reason is as described above with reference to Equation 1. As a result, the amount of ions flowing from the plasma 14 into the Faraday device 16 beyond the positive suppression voltage is reduced and the flow is stabilized, so that the error of the beam current measurement of the ion beam 6 by the Faraday device 16 is reduced. The measurement current becomes stable as the number decreases. Thereby, for example, the accuracy of controlling the injection amount into the substrate 10 based on the beam current measurement by the Faraday device 16 is improved, and the yield of the injected product is also improved.

Further, as in this example, there is provided a non-mass separation type ion implantation apparatus which irradiates the substrate 10 with the ion beam 6 extracted from the ion source 2 without passing through the mass separator. Also serves as a means for generating the plasma 14, the plasma 14 is also generated in the vicinity of the extraction electrode system of the ion source 2, and the potential of the plasma 14 extends to the extraction electrode system of the ion source 2 as described above. By lowering and stabilizing the potential of the plasma 14, the effect of improving the stability of extracting the ion beam 6 from the ion source 2 is also obtained. This will be described below.

First, an example of the structure of the ion source 2 is shown in FIG. The ion source 2 is provided near the opening of the plasma source unit 60 for generating a plasma 68 by ionizing the above-mentioned ion source gas 4 by discharge, and is provided with an electric field from the plasma 68. And an extraction electrode system 70 for extracting the ion beam 6.

In this example, the plasma source section 60 has a plasma chamber container 62 and a filament 64 provided therein. While the inside of the plasma chamber container 62 is evacuated through the extraction electrode system 70, the plasma chamber container 6
When the ion source gas 4 is introduced into the filament 2 and the filament 64 is heated by the filament power supply 80 and a DC voltage is applied between the filament 64 and the plasma chamber container 62 from the arc power supply 82, the filament 64 and the plasma chamber container 62 An arc discharge occurs and the ion source gas 4 is ionized to generate a plasma 68.

In this example, a large number of permanent magnets 66 are provided around the plasma chamber container 62, and a cusp magnetic field (multipole magnetic field) is formed near the inner wall of the plasma chamber container 62, which confines the plasma 68. To contribute. Such an ion source is also called a bucket type ion source.

The extraction electrode system 70 is composed of one or more electrodes, usually a plurality of electrodes. In this example, the plasma electrodes 7 arranged from the most plasma side to the downstream side
1. Extraction electrode 72, suppression electrode 73, and ground electrode 74
It is composed of 76 is an insulator. Each electrode 71
Reference numerals 74 denote a porous electrode in this example, but may have an ion extraction slit.

The plasma electrode 71 is an electrode for determining the energy of the ion beam 6 to be extracted. A positive acceleration voltage is applied from an acceleration power supply 84 with reference to the ground potential. The extraction electrode 72 is an electrode that causes a potential difference between the plasma electrode 71 and the ion beam 6 from the plasma 68 by an electric field caused by the electric potential difference, and a negative extraction voltage from the extraction power supply 86 with reference to the potential of the plasma electrode 71. Applied. The suppression electrode 73 is an electrode for suppressing backflow of electrons from the downstream side, and a negative suppression voltage is applied from the suppression power supply 88 with reference to the ground potential. The ground electrode 74 is grounded.

The plasma 14 generated by the collision between the ion beam 6 and the atmospheric gas molecules naturally occurs near the downstream side of the ground electrode 74. When the potential of the plasma 14 rises for the reason described above, the plasma 14
The ions therein enter the negative potential suppressing electrode 73 through the hole of the ground electrode 74 (backflow), which triggers a discharge between the ground electrode 74 and the suppressing electrode 73.
Further, when this discharge occurs, backflow electrons from the downstream side by the suppression electrode 73 cannot be blocked, and a discharge also occurs between the extraction electrode 72 or the plasma electrode 71 and the suppression electrode 73 or the ground electrode 74. Therefore, it is difficult to stably extract the ion beam 6.

On the other hand, as in this embodiment, the lining electrode 32a and the DC power
When the potential is lowered and stabilized, ions flowing backward from the plasma 14 into the extraction electrode system 70 can be suppressed, so that the extraction stability of the ion beam 6 is improved. As a result, the stability of ion implantation into the substrate 10 is improved, and the yield of implanted products is also improved.

When the lining electrode 32a is provided, a film such as an insulating film is deposited also on the surface facing the plasma 14. However, if a negative voltage is applied to the lining electrode 32a, the film can be expected to be removed by sputtering due to the incidence of ions from the plasma 14, so that the deposition rate of the film is lower than that of the conventional vacuum vessel 8. . However, if the film deposition is left for a long time, the above-described action of stabilizing the plasma potential by the lining electrode 32a and the DC power supply 44 is reduced. This is the lining electrode 3
This is because, when a film adheres to 2a, especially when an insulating film adheres, the amount of secondary electrons emitted from the lining electrode 32a decreases, and the action of lowering the plasma potential by the secondary electrons decreases. Also, if a film adheres to the lining electrode 32a, particularly if an insulating film adheres, the potential of the lining electrode 32a is not reflected on the plasma 14 as it is.

For example, in order to remove the film deposited on the lining electrode 32a, if the inside of the vacuum container 8 is opened to the atmosphere and the cleaning operation is manually performed, the cleaning operation and the vacuum container 8 are evacuated again. It takes a long time, and the operation rate of the ion implantation apparatus is greatly reduced.

Therefore, in order to remove the film deposited on the lining electrode 32a, it is preferable to employ the following cleaning method. That is, the cleaning gas 50 is introduced into the vacuum vessel 8 through, for example, the cleaning gas introduction port 48, and the switch 42 is switched to the high frequency power supply 46 side.
A high-frequency electric power is supplied between the inner electrode 32a and the vacuum vessel 8 to generate a high-frequency discharge between the inner electrode 32a and the vacuum vessel 8, whereby the cleaning gas 50 is ionized and the cleaning plasma is generated inside the inner electrode 32a. Is generated, and this cleaning plasma causes the lining electrode 3
The film deposited on the inner surface of 2a, that is, the surface on the plasma 14 side is removed. This cleaning is performed when the substrate 10 is not implanted with ions.

The cleaning gas 50 is, for example, hydrogen gas, a mixed gas of hydrogen gas and an inert gas such as argon,
Oxygen-based gas, halogen-based gas and the like. The cleaning gas pressure in the vacuum vessel 8 at the time of cleaning, more specifically, inside the lining electrode 32a is, for example, 0.2 mTorr.
The pressure may be set to about 10 to 10 mTorr.

The high frequency power supply 46 is, for example, 13.56 MH
It outputs high-frequency power of frequency z, but is not limited to this. Usually, the high frequency power supply 46 and the lining electrode 32
Although a matching circuit is provided between a and a, the illustration is omitted here. The input high frequency power at the time of cleaning may be, for example, about 500 W to 2 kW.

The tubular lining electrode 32 as described above is used.
When a high-frequency power is supplied between the inner electrode 32a and the vacuum container 8, the cleaning gas pressure as described above does not normally cause a high-frequency discharge between the outer surface of the inner electrode 32a and the vacuum container 8, and the inner electrode 32a A high-frequency discharge is generated between the inner surface of the electrode and the vacuum vessel 8, and cleaning plasma can be successfully generated inside the lining electrode 32a. This is because the distance between the outer surface of the lining electrode 32a and the vacuum vessel 8 is very short (for example, about 2 to 5 mm), and only an equipotential surface almost parallel to both is generated between the two. The distance is short and the cleaning gas 5
While the action of ionizing 0 is very weak, the distance between the inner surface of the lining electrode 32a and the vacuum vessel 8 is relatively long, and a curved equipotential surface is formed between the two. This is because the traveling distance of the electrons becomes relatively long in the direction intersecting with the cleaning plasma 50, and the cleaning plasma 50 can be effectively ionized by the electrons.

According to the above-described cleaning method,
Since it is not necessary to open the inside of the vacuum vessel 8 to the atmosphere and perform a cleaning operation by hand, the film deposited on the lining electrode 32a can be removed in a short time, and the operation rate of the ion implantation apparatus can be improved. it can.

Next, FIG. 3 shows an example of an ion implantation apparatus having a structure in which an ion beam 6 having a rectangular cross section is extracted from the ion source 2 and the substrate 10 is reciprocally scanned mechanically across the ion beam 6. The same or corresponding parts as in the example of FIG. 1 are denoted by the same reference numerals, and the following mainly describes differences from the example of FIG.

The ion implantation apparatus shown in FIG. 3 is also a non-mass separation type ion implantation apparatus, and has a vacuum vessel 8 which is evacuated to a vacuum by a vacuum evacuation device (not shown).

The vacuum vessel 8 has two wall surfaces 8a and 8b facing each other, and the ion source 2 is mounted on one wall surface 8a. This ion source 2 also has, for example, a structure as shown in FIG. 2, but in this example, emits an ion beam 6 having an elongated rectangular shape (also referred to as a ribbon shape or a line shape) (see FIGS. 4 to 4). 6). The length L ₁ of the long sides of the ion beam 6, as shown in FIG. 4, greater than the length L ₂ of the side corresponding to the length L ₁ of the substrate 10 (that is, L _1> L ₂ )doing.
The substrate 10 has a rectangular shape in the example of FIG. 3, but is not limited thereto.

In this example, the inside of the other wall surface 8b of the vacuum vessel 8 receives the ion beam 6 emitted from the ion source 2 so as to face the ion source 2 and measures the beam current as described above. A Faraday device 16 is provided. The Faraday device 16 also has a structure as shown in FIG. 8, for example. However, the Faraday device 16 may be mounted outside the wall surface 8b. That is, an opening is provided in a portion of the wall surface 8b facing the ion source 2, and the Faraday device 16 is mounted outside the opening so that the mask 22 (see FIG. 8) communicates with the opening. good.
The Faraday device 16 is connected to, for example, the current integrator 18 (see FIG. 1 and the like) as described above, and is used for injection amount control.

The substrate 1 as described above is placed in the vacuum container 8.
A substrate holder 12 for holding 0 is provided. In this example, the substrate holder 12 is provided with a drive shaft 53 of the scanning mechanism 52.
, And is mechanically reciprocally scanned with the substrate 10 by the scanning mechanism 52 so as to cross the ion beam 6 as shown by an arrow A. Accordingly, the ion beam 6 can be made incident on the entire surface of the substrate 10 also in the relationship of L ₁ > L ₂ described above.

Also in this ion implantation apparatus, in order to prevent charge-up of the substrate 10 due to ion beam irradiation, etc., the gas in the vacuum vessel 8 at the time of ion implantation, more specifically, near the front of the ion source 2 is used. Pressure is 10 ^-4 to 10 ^-5 T
A means for generating a plasma 14 in a region including the surface of the substrate 10 at a position where the ion beam 6 is incident by collision of the ion beam 6 with the atmospheric gas molecules is maintained on the orr level. That is, also in this example, the ion source 2 also serves as a means for generating the plasma 14. As described above, the atmosphere gas is mainly supplied from the ion source 2 to the vacuum container 8.
The ion source gas 4 leaked into the inside.

Even in such an ion implantation apparatus, there is a problem similar to that of the conventional apparatus shown in FIG. 7 as it is. Therefore, the region for generating the plasma 14 and the wall surface 8a of the vacuum vessel 8 facing the region are generated. And 8b, two planar lining electrodes 32b and 32c are arranged electrically insulated from the vacuum vessel 8.

More specifically, in this example, the lining electrode 32b is arranged along the wall surface 8a so as to cover the area around the ion source on the wall surface 8a on the ion source 2 side of the vacuum container 8, and the vacuum container A lining electrode 32c is arranged along the wall surface 8b so as to cover an area around the Faraday device on the wall surface 8b on the side of the Faraday device 6 in FIG. Both lining electrodes 32
In this example, b and 32c are electrically insulated and supported from the wall surfaces 8a and 8b by the insulator 40, respectively. The two lining electrodes 32b and 32c are electrically connected in parallel to each other by, for example, a conducting wire 33.

Each of the both lining electrodes 32b and 32c is a plate-like electrode having an opening 34 through which the ion beam 6 passes as shown in FIG. 4, for example. Alternatively, each of the two lining electrodes 32b and 32c may be composed of two electrode plates arranged side by side with a gap 35 through which the ion beam 6 passes, as in the example shown in FIG. 5, for example. The two electrode plates may be electrically connected by the conducting wire 36.

The two lining electrodes 32 as described above are used.
Instead of b and 32c, for example, as shown in FIG. 6, the front and rear surfaces 38 and 39 have openings 34 through which the ion beam 6 passes, respectively. A box-shaped lining electrode 32d having an opening 37 passing therethrough may be provided. The surfaces 38 and 39 correspond to the lining electrodes 32b and 32c, respectively. The substrate holder 12 holding the substrate 10 is reciprocally scanned in the box-shaped lining electrode 32d as shown by the arrow A. Since the lining electrode 32d can more completely surround the region where the plasma 14 is generated than the two lining electrodes 32b and 32c, the plasma 1
The effect of stabilizing the potential of No. 4 is further enhanced.

The above-mentioned lining electrodes 32b to 32d are
As in the case of the example, the negative electrode side of the DC power supply 44 and one output terminal side of the high frequency power supply 46 are connected via the changeover switch 42. For the lining electrodes 32b to 32d,
At the time of ion implantation, a negative DC voltage of about -10 V to -200 V is applied from the DC power supply 44, for example, as described above. At the time of cleaning, high frequency power of 13.56 MHz and about 500 W to 2 kW is supplied from the high frequency power supply 46 in the same manner as described above.

Also in this ion implantation apparatus, by applying the above-described negative DC voltage from the DC power supply 44 to the lining electrodes 32b to 32d, the operation time of the ion implantation apparatus is reduced by the above-described operation. It is possible to stabilize the potential of the plasma 14 by suppressing an increase in the potential of the plasma 14 due to this. As a result, the amount of ions flowing from the plasma 14 into the Faraday device 16 is reduced and the flow is stabilized, so that the error of the beam current measurement of the ion beam 6 by the Faraday device 16 is reduced and the measurement current is stabilized. I do. Thereby, for example, the accuracy of controlling the injection amount into the substrate 10 based on the beam current measurement by the Faraday device 16 is improved, and the yield of the injected product is also improved.

In particular, the ion implanter having the structure as shown in FIG. 3 has a larger size than the ion implanter having the structure shown in FIG.
Even when the same ion implantation is performed on the substrate 10, the current density of the ion beam 6 is about one digit higher because the cross-sectional shape of the ion beam 6 is an elongated rectangle. The deposition rate of the film such as the insulating film on the inner wall of the vacuum vessel is high, and the Faraday device 16 is adversely affected by the increase in the potential of the plasma 14 quickly. The effect of stabilizing the potential of the plasma 14 by suppressing the rise of the potential of the plasma 14 by providing the 32d and the DC power supply 44 and thereby stabilizing the measurement of the beam current of the ion beam 6 by the Faraday device 16 becomes remarkable. .

Also in this example, the non-mass separation type ion implantation apparatus irradiates the substrate 10 with the ion beam 6 extracted from the ion source 2 without passing through the mass separator. Since it also serves as a means for generating the plasma 14, the plasma 14 is also generated near the extraction electrode system 70 (see FIG. 2) of the ion source 2, and the potential of the plasma 14 reaches the extraction electrode system. By lowering and stabilizing the potential of the plasma 14 as described above, the effect of improving the stability of extracting the ion beam 6 from the ion source 2 can be obtained for the same reason as described above in detail.

The lining electrode may be provided only inside one of the two wall surfaces 8a and 8b of the vacuum vessel 8.
Although the above-described operation and effect of suppressing and stabilizing the potential of the plasma 14 is achieved, both the wall surfaces 8a as in this embodiment are provided.
And 8b are more preferably provided inside. this is,
This is because the area of the lining electrode that exerts the above-described action on the plasma 14 becomes larger when both are provided. In the case where the Faraday device 16 is provided on only one side, the main purpose is to prevent the Faraday device 16 from being adversely affected. Therefore, it is better to provide the Faraday device 16 on the wall surface 8b side. By doing so, at least the Faraday device 16
This is because the potential of the plasma 14 in the vicinity of can be reduced.

In order to remove the deposited film of the lining electrodes 32b to 32d, it is preferable to employ the same high-frequency discharge cleaning method as described above in the case of this ion implantation apparatus. That is, for example, the cleaning gas 5 described above is inserted into the vacuum container 8 through the cleaning gas inlet 48.
0, and the changeover switch 42 is
6 and the high-frequency power supply 46 supplies the above-described high-frequency power between the lining electrodes 32b to 32d and the vacuum vessel 8 to supply the high-frequency power between the lining electrodes 32b to 32d and the vacuum vessel 8. A high-frequency discharge is generated between the electrodes, whereby the cleaning gas 50 is ionized and the liner electrode 3
A cleaning plasma is generated inside 2b to 32d,
By this cleaning plasma, the lining electrode 32b
The film deposited inside .about.32d, that is, on the surface on the plasma 14 side is removed. The cleaning gas pressure in the vacuum vessel 8 at the time of cleaning, that is, in the vicinity of the inside of the lining electrodes 32b to 32d is, for example, 0.2 mTorr to 10 mTorr as described above.
It is set to about mTorr.

According to such a cleaning method, it is not necessary to open the inside of the vacuum vessel 8 to the atmosphere and perform the cleaning operation manually, so that the film deposited on the lining electrodes 32b to 32d can be removed in a short time. The operation rate of the ion implantation apparatus can be improved.

The structure of other parts of the ion implantation apparatus shown in FIG. 3 will be briefly described. When predetermined ion implantation for the substrate 10 is completed, the substrate holder 12 is turned over by the scanning mechanism 52 as shown by the arrow B. Make it horizontal (2
The substrate 10 having been injected is carried out through the vacuum valve 56 into the pre-vacuum chamber 54 as shown by the arrow C, and is further carried out through the vacuum valve 58 to the atmosphere side as shown by the arrow D. The mounting of the uninjected substrate on the substrate holder 12 is performed in the reverse process. The transfer and the like of the substrate 10 are performed by a transfer mechanism (not shown).

As means for generating the plasma 14 in a region including the vicinity of the surface of the substrate 10 on the substrate holder 12, means other than the means also serving as the ion source 2 may be used. For example, the substrate 1 on the substrate holder 12 (the substrate holder 12 at the ion beam irradiation position in the example of FIG. 3)
A high-frequency electrode, a high-frequency antenna, and the like are arranged near the surface of the substrate 0, and high-frequency power is supplied from the high-frequency power supply to generate high-frequency discharge near the surface of the substrate 10 on the substrate holder 12 to ionize the atmosphere gas. Means for generating the plasma 14 may be employed.

The purpose of generating the plasma 14 is not limited to the prevention of charge-up of the substrate 10,
Other purposes may be used. For example, a plasma 14 of a source gas is generated near the surface of the substrate 10 to deposit a thin film on the surface of the substrate 10, and the thin film is irradiated with an ion beam 6 to form a thin film and perform ion implantation (or ion beam irradiation). It is also possible to generate the plasma 14 in order to use together.

[0064]

Since the present invention is configured as described above, it has the following effects.

According to the first aspect of the present invention, by applying a negative DC voltage from a DC power supply to the lining electrode,
It is possible to stabilize the plasma potential by suppressing an increase in the plasma potential with the elapse of the operation time. As a result, the amount of ions flowing from the plasma to the Faraday device is reduced and the flow is stabilized, so that errors in the beam current measurement of the ion beam by the Faraday device are reduced, the measurement current is stabilized, and stable measurement is possible. become. As a result, for example, the accuracy of controlling the injection amount into the substrate based on the beam current measurement by the Faraday device is improved, and the yield of the injected product is also improved.

According to the second aspect of the present invention, since the inner wall of the vacuum vessel facing the plasma is covered over a wider area with the lining electrode, the plasma potential is stabilized and the ion beam current measurement by the Faraday device is stabilized. And the like can be further enhanced.

According to the third aspect of the present invention, by applying a negative DC voltage from a DC power supply to the lining electrode,
It is possible to stabilize the plasma potential by suppressing an increase in the plasma potential with the elapse of the operation time. As a result, the amount of ions flowing from the plasma to the Faraday device is reduced and the flow is stabilized, so that errors in the beam current measurement of the ion beam by the Faraday device are reduced, the measurement current is stabilized, and stable measurement is possible. become. As a result, for example, the accuracy of controlling the injection amount into the substrate based on the beam current measurement by the Faraday device is improved, and the yield of the injected product is also improved.

According to the fourth aspect of the present invention, since the inner wall of the vacuum vessel facing the plasma is covered over a wider area with the lining electrode, the plasma potential is stabilized and the ion beam current measurement by the Faraday device is stabilized. And the like can be further enhanced.

According to the fifth aspect of the present invention, it is not necessary to open the inside of the vacuum vessel to the atmosphere and perform a cleaning operation manually, so that the film deposited on the lining electrode can be removed in a short time. The operation rate of the injection device can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an example of an ion implantation apparatus according to the present invention.

FIG. 2 is a sectional view showing an example of an ion source together with its power source.

FIG. 3 is a cross-sectional view showing another example of the ion implantation apparatus according to the present invention.

FIG. 4 is a front view showing an example of a lining electrode provided in the apparatus of FIG.

FIG. 5 is a front view showing another example of the lining electrode provided in the apparatus shown in FIG. 3;

FIG. 6 is a perspective view showing still another example of the lining electrode provided in the apparatus of FIG. 3;

FIG. 7 is a longitudinal sectional view showing an example of a conventional ion implantation apparatus.

FIG. 8 is a sectional view showing an example of a Faraday device together with its power supply.

[Explanation of symbols]

 2 Ion source 6 Ion beam 8 Vacuum container 10 Substrate 12 Substrate holder 14 Plasma 16 Faraday device 32a-32d Lining electrode 44 DC power supply 46 High frequency power supply 50 Cleaning gas 52 Scanning mechanism

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[Procedure amendment]

[Submission date] April 28, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Name of invention

[Correction method] Change

[Correction contents]

[Title of the Invention] Ion implanter

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

Holding and 1. A vacuum vessel is evacuated to a vacuum, an ion source section and attached to the wall surface of the vacuum vessel is emitted elongated rectangular ion beam, a substrate provided in the vacuum chamber A substrate holder, a scanning mechanism that reciprocally scans the substrate holder with the substrate and traverses the ion beam so that the ion beam is incident on the entire surface of the substrate, and a wall surface of the vacuum container that faces the ion source. A Faraday device which is provided inside or outside so as to face the ion source, receives an ion beam emitted from the ion source, and measures the beam current, and near the surface of the substrate at a position where the ion beam is incident Contact and means for generating a plasma in a region including the
In addition, with the generation of this plasma, the electrically insulating film
In the ion implantation apparatus that will be operated in an environment that is deposited on the inner wall of the vacuum vessel, electrically insulating arranged from the wall surface so as to delimit between the wall surface of the vacuum vessel facing thereto and a region for generating the plasma And a DC power supply for applying a negative DC voltage to the lining electrode, and the lining electrode is provided with the vacuum capacity.
The region around the ion source on the inner wall of the
Around the Faraday device on the inner wall of the vacuum vessel on the Faraday device side
Ion implantation apparatus characterized that you have been placed along the inner wall so as to cover the region of the edges.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0065

[Correction method] Deleted

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0066

[Correction method] Deleted

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0067

[Correction method] Change

[Correction contents]

[0067] That is, according to this invention, by applying a negative DC voltage from the DC power supply to the lining electrode, by suppressing the increase of the plasma potential over the course of a operation time, it is possible to stabilize the plasma potential Will be possible. As a result, the amount of ions flowing from the plasma to the Faraday device is reduced and the flow is stabilized, so that errors in the beam current measurement of the ion beam by the Faraday device are reduced, the measurement current is stabilized, and stable measurement is possible. become. As a result, for example, the accuracy of controlling the injection amount into the substrate based on the beam current measurement by the Faraday device is improved, and the yield of the injected product is also improved.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name]

[Correction method] Change

[Correction contents]

Moreover , the inner wall of the vacuum vessel facing the plasma is lined with an inner electrode ,
Since the plasma is covered more extensively in both the peripheral region of the Faraday device and the Faraday device, the effects of stabilizing the plasma potential and stabilizing the ion beam current measurement by the Faraday device can be further enhanced. Furthermore, the cross section of the ion beam
Is an elongated rectangle. In this case, the ion beam
If the current density is high and there is no lining electrode,
The deposition rate of the edge film on the inner wall of the vacuum vessel is high,
The rise in the potential has a negative effect on the Faraday device
The lining electrode and the
And DC power supply to suppress the rise in plasma potential,
Stabilization of the zuma potential, and eventually a Faraday device
The effect of stabilizing the beam current measurement of the ion beam
Become noticeable.

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0069

[Correction method] Deleted

Claims (5)

[Claims] 1. A vacuum container evacuated to vacuum, a substrate holder provided in the vacuum container and holding a substrate,
An ion source for irradiating the substrate on the substrate holder with an ion beam having a larger area, and an ion source for irradiating the substrate from the ion source, which is provided near the substrate holder and at a position avoiding the substrate. In an ion implantation apparatus including a Faraday device that receives a part and measures the beam current and a unit that generates plasma in a region including the vicinity of the surface of the substrate on the substrate holder, the region that generates the plasma and the region facing the plasma A planar liner electrode electrically insulated from the wall surface so as to partition between the wall surface of the vacuum vessel and a DC power supply for applying a negative DC voltage to the liner electrode. Ion implanter. 2. A cylinder arranged along the inner wall of the vacuum vessel so as to cover the inner wall of the inner wall of the vacuum vessel from the vicinity of the substrate holder to the vicinity of the mounting opening of the ion source. The ion implantation apparatus according to claim 1, wherein the ion implantation apparatus is a shaped electrode. 3. A vacuum container to be evacuated to vacuum, an ion source attached to a wall surface of the vacuum container to emit an ion beam having a rectangular cross section, and a substrate provided in the vacuum container to hold a substrate. A substrate holder, a scanning mechanism that reciprocally scans the substrate holder with the substrate so as to cross the ion beam and causes the ion beam to be incident on the entire surface of the substrate, and an inner side of a wall opposed to a wall of the vacuum vessel on which an ion source is mounted. Or a Faraday device which is provided on the outside so as to face the ion source and receives the ion beam emitted from the ion source and measures the beam current, and the vicinity of the surface of the substrate at the position where the ion beam is incident Means for generating plasma in a region including the plasma generating device, wherein the plasma generating region and a vacuum vessel facing the region are generated. Ion implantation, comprising: a planar lining electrode arranged electrically insulated from the wall surface so as to partition between the wall surface and a DC power supply for applying a negative DC voltage to the lining electrode. apparatus. 4. The inner lining electrode extends along the inner wall of the vacuum vessel so as to cover an area around the ion source on an inner wall of the vacuum vessel on the ion source side and an area around the Faraday apparatus on an inner wall of the vacuum vessel on the Faraday apparatus side. Claim 3 which is arranged
An ion implanter according to any one of the preceding claims. 5. The ion implantation apparatus according to claim 1, wherein a cleaning gas is introduced into the vacuum vessel and a high-frequency power is supplied between the lining electrode and the vacuum vessel. A high-frequency discharge is generated between the lining electrode and the vacuum vessel to ionize the cleaning gas to generate cleaning plasma, and the cleaning plasma removes a film deposited on the surface of the lining electrode. How to clean the injection device.