JPH10241589A - Plasma generator and ton implanting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain high plasma drawing efficiency by providing at least two or more plate materials having opening parts in a front plate and setting the opening of the plate material arranged in the inner side to be narrower than that of the adjacent plate material in the outer side. SOLUTION: A plasma generator 100 includes a coil filament 70 in one of a pair of opposing side wall surfaces and a repeller plate 80 in the other side wall surface, these being fixed by insulating fasteners 55 and 65. Filament and repeller plate drawing electrodes 50 and 60 are removed to the outside from the plasma generator via the insulating fasteners 55 and 65. A front plate is made of two plate materials, i.e., inner and outer slit plates 30 and 40. The opening of a slit 20 provided in the inner slit plate 30 is formed to be narrower than that of a slit 20 provided in the outer slit plate 40. Thus, the diffusion angle of ion beams emitted from the device to the outside is drawn and, by preventing the ion beams from entering the ring part of the drawing electrode part, the amount of leaked around ion beams is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor manufacturing apparatus, and more particularly, to an ion implantation apparatus used for an impurity diffusion step and the like, and a plasma generation apparatus which is an ion source of the ion implantation apparatus.

[0002]

2. Description of the Related Art The impurity doping method using an ion implanter can control the number and depth of impurities to be implanted accurately and with good reproducibility. Most of the steps are performed using this equipment.

The ion implantation apparatus includes a plasma generation apparatus serving as an ion source, an extraction electrode section for extracting an ion beam from plasma generated by the plasma generation apparatus, and a selective ion beam further required from the extracted ion beam. And a scanning unit for scanning the ion beam.

In order to improve the ion beam generation efficiency of an ion implantation apparatus, it is necessary to efficiently extract an ion beam from plasma generated by a plasma generation apparatus serving as an ion source.

FIG. 6A is an external perspective view of a conventional plasma generator. As shown in the figure, a slit 530 is provided at the center of the front plate 510 of the plasma generation device 500. The plasma generated inside the plasma generation device 500 is drawn out from the slit 530 to the outside.

FIG. 6B is a sectional view of a conventional plasma generating apparatus. As shown in the figure, in the plasma generating apparatus, a coil-shaped filament 580 is fixed to one of a pair of opposed inner wall surfaces, and a repeller plate 590 is fixed to the other by insulating stoppers 550 and 560, respectively. Further, an ion source gas supply port 60 is provided at the bottom of the plasma generating apparatus.
0 is provided, from which gas serving as an ion source is supplied.

FIG. 7 is a conceptual view showing a state in which an ion beam is extracted from a plasma generating apparatus. The plasma 610 mainly includes the filament 580 and the repeller plate 5.
90 and 90. The slit 530 is formed at the upper center of the plasma generation region. Plasma 610 is
The slit 530 is pulled out along the inner wall shape of the slit 530 so as to rise upward in the figure. The ionized atoms are emitted upward in the drawing by the action of the electric field provided by the extraction electrode 630. Leader electrode 6
Only the ion beam 620 captured in the ring 30 further passes through the mass analyzer and the scanner, and is output from the ion implanter to the outside.

FIG. 6C is an enlarged sectional view showing the shape of the wall portion b of the slit 530 surrounded by a broken line in FIG. 6B. In the figure, the lower side corresponds to the inside of the plasma generation device. If the inner wall surface of the slit opening is provided with a taper that spreads outward, plasma generated in the apparatus can be easily extracted to the outside. As the amount of extracted plasma increases, the amount of emitted ion beam also increases.
Therefore, a taper is generally provided on the opening wall surface of the slit.

However, if the inner tip 510e of the inner wall of the slit opening surrounded by the broken line in FIG. 6 (c) is sharp, the spire portion is easily deformed by the heat of the plasma. Therefore, in order to suppress this deformation, as shown in FIG. 6C, the inside tip of the slit is usually cut perpendicular to the front surface. Thus, the inner wall surface of the slit has the inner vertical opening 510p and the outer tapered opening 510s.

For example, the slit wall surface of the front plate of the current plasma generating apparatus has a height hp of an inner front end portion, which is a vertical opening, in most cases 0.3 mm, and an opening angle θ0 of a tapered opening is 90 degrees. . Note that the opening angle of the tapered opening is twice as large as the angle formed by the perpendicular to the front surface and the tapered surface.

As a material of the front plate of the plasma generating apparatus, molybdenum (Mo) having high heat resistance is used.

[0012]

In order to reduce the running cost in using the ion implantation apparatus and obtain higher production efficiency, it is desired to increase the ion beam generation efficiency. In order to obtain high ion beam generation efficiency, first, plasma is efficiently extracted from the plasma generated in the plasma generator, which is the ion source, and ions are efficiently extracted from the extracted plasma into the electrode ring. It is necessary to incorporate a beam.

The amount of plasma extracted from the plasma generator to the outside largely depends on the slit shape of the front plate of the plasma generator. Generally, in order to increase the plasma extraction efficiency, it is said that firstly, the height hp of the vertical opening on the slit wall surface should be kept lower, and second, the opening angle θs of the tapered opening on the slit wall surface should be made larger. ing.

However, the first and second methods described above have limitations. First, when the height hp of the vertical portion is made smaller based on the first method, the inner end portion 510e of the slit is formed.
Is thin, the local heat capacity of this portion is reduced, and the portion is easily deformed by the heat of the plasma. The opening of the slit becomes wider with the frequency of use. Normally, at the start of use of the apparatus, the shape of the slit and the opening area of the slit are set so that the plasma extraction efficiency is the highest, so if the shape of the slit is deformed over time, the plasma extraction efficiency is deteriorated due to this deformation. I do. In order to maintain the plasma extraction efficiency, it is necessary to increase the frequency of replacing the front plate, which increases the running cost of the apparatus.

Further, based on the second method, even if the inclination angle θs of the tapered portion of the slit wall surface is made smaller, the effect is small as long as the height hp of the vertical portion of the slit wall surface cannot be reduced.

An object of the present invention is to provide a plasma generating apparatus capable of maintaining high plasma extraction efficiency.

Another object of the present invention is to provide an ion implantation apparatus having the above-described plasma generation apparatus and having high ion beam generation efficiency.

[0018]

According to a first aspect of the present invention, there is provided a plasma generating apparatus having means for generating plasma from an ion source gas in the apparatus, wherein a front plate of the apparatus generates the plasma. In a plasma generation device having an opening for drawing out to the outside, the front plate includes:
Having at least two or more plate members having the opening,
That is, the opening of the inner plate is narrower than the opening of the adjacent outer plate.

According to the first aspect of the present invention, the deformation of the opening due to an increase in the frequency of use mainly occurs in the innermost plate. Therefore, since only the innermost plate needs to be replaced, the running cost can be reduced. In addition, since the front plate is composed of a plurality of plate members, each plate member can be made thin, and processing of the plate member becomes easy.

According to a second aspect of the present invention, in the plasma generating apparatus according to the first aspect, each of the plate members is formed of a different material, and the innermost one of the plate members is formed of a different material. High plasma resistance.

According to the feature of the second aspect, the damage caused by the high temperature of the plasma generated in the apparatus is large in the innermost plate, but since a plate having high plasma resistance is used as this plate. In addition, the service life of the front plate can be increased. The feature of the plasma generating apparatus according to the third aspect of the present invention is the first or second aspect.
In the plasma generating apparatus described above, the innermost plate is made of tungsten.

According to the third aspect of the present invention, since the material which is more plasma-resistant than molybdenum which has been conventionally used as the front plate is used as the innermost plate material, the front plate has a long service life. Can be reliably increased.

According to a fourth aspect of the present invention, in the plasma generating apparatus of the third aspect, the opening of the innermost plate has an inner wall surface inside the opening and a wall surface. It has a vertical opening perpendicular to the front surface, has a tapered opening on the inner wall surface outside the opening, the wall surface is inclined with respect to the front surface, and the height of the vertical opening is less than 0.3 mm It is to be.

According to the fourth aspect of the present invention, by setting the height of the vertical opening of the innermost plate material to be less than 0.3 mm, the plasma generated in the apparatus is drawn out to the outside as compared with the related art. Therefore, the effective extraction efficiency of plasma can be increased.

According to a fifth aspect of the present invention, in the plasma generating apparatus of the fourth aspect, an opening angle of the tapered opening of the innermost plate is at least 90 degrees. It is big.

According to the fifth aspect of the present invention, since the opening angle of the tapered opening is wider than in the prior art, the plasma generated in the apparatus can be easily extracted to the outside, and the effective extraction efficiency of the plasma can be increased. . Claim 6 of the present invention
The feature of the plasma generation apparatus according to the above, in the plasma generation apparatus having means for generating plasma from an ion source gas in the apparatus, wherein the front plate of the apparatus has an opening for extracting the plasma to the outside, A front plate having an inner first plate member formed of tungsten and an outer second plate member formed of molybdenum;
An opening of the first plate is formed on an inner inner wall surface of the opening, a vertical opening having a wall surface perpendicular to the front surface, and a tapered opening having a wall surface inclined with respect to the front surface on an outer inner wall surface of the opening. And the height of the vertical opening of the first plate is less than 0.3 mm, the opening angle of the tapered opening of the first plate is greater than at least 90 degrees, and the opening of the second plate is However, the opening inner wall surface has a tapered opening in which the wall surface is inclined with respect to the front surface, and the opening angle of the tapered opening of the second plate material is 70 degrees or more and 90 degrees or less.

According to the feature of the sixth aspect, in addition to the same effects as those of the plasma generating apparatus according to the first to fifth aspects,
The second plate is made of molybdenum, and the angle of the tapered opening is made smaller than the opening of the first plate, thereby increasing the amount of ion beam picked up in the ring of the extraction electrode. Can be done.

According to a seventh aspect of the present invention, there is provided an ion implantation apparatus comprising: a plasma generation apparatus; an extraction electrode unit for extracting an ion beam from plasma generated by the plasma generation apparatus; and an extracted ion beam. 2. A mass spectrometer for selectively extracting a beam of a required ion species from the semiconductor device, and a scanning unit for scanning the selectively extracted ion beam, wherein the plasma generation device is configured to perform the following steps.
6. The plasma generation device according to any one of items 1 to 6, above.

According to the feature of the seventh aspect, since the plasma generating apparatus according to any one of the first to sixth aspects is used as the plasma generating apparatus which is the heart of the ion implantation apparatus, the ion beam intensity is stabilized. As a result, an ion implanter with low running cost can be provided. In particular, the use of the plasma generator according to any one of claims 4 to 6 can increase the effective ion beam intensity.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An ion implanter according to an embodiment of the present invention and a plasma generator as an ion source of the ion implanter will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of an ion implantation apparatus according to an embodiment of the present invention. The ion implantation apparatus according to the present embodiment includes a plasma generation apparatus 10 serving as an ion source.
0, an extraction electrode unit 1 for extracting an ion beam from the plasma generated by the plasma generation apparatus 100 to the outside.
20, an accelerating unit 13 for accelerating the extracted ion beam
0, a mass spectrometer 1 for selectively extracting only an ion beam of a necessary ion species from the extracted ion beam
40, and the selected ion beam 110 to the wafer 1
It has a scanning unit 150 for scanning on 80, a beam correction unit 160 for adjusting the injection angle of the ion beam 110 with respect to the wafer surface, and a susceptor 170 capable of holding and rotating the wafer 180. All of these components are provided in a vacuum chamber and used under high vacuum conditions.

FIG. 2A is a front view of a plasma generator 100 serving as an ion source of the ion implanter according to the present embodiment. FIG. 2B is a sectional view taken along the line A in FIG.
A cross-sectional view at A 'is shown.

As shown in FIGS. 2A and 2B, in the plasma generating apparatus 100, a coil-shaped filament 70 is provided on one of a pair of opposed side walls, and a repeller plate 80 is provided on the other. They are fixed by insulating stoppers 55 and 65, respectively. Extraction electrode 50 of filament 70
In addition, the extraction electrode 60 of the repeller plate is taken out of the plasma generation device via the insulating stoppers 55 and 65. An ion source gas supply port 90 is provided at the bottom of the plasma generation device. These configurations are almost the same as those of the conventional plasma generator.

One of the features of the plasma generating apparatus according to the present embodiment is that, as shown in FIGS. 2A and 2B, the front plate of the plasma generating apparatus includes an inner slit plate 30 and an outer slit plate 40. Is constituted by the two plate members.

The outer slit plate 40 is formed of molybdenum (Mo) as in the prior art, and the inner slit plate 30 is formed of a material having higher plasma resistance than molybdenum, for example, tungsten (W) having a higher melting point than molybdenum. . The opening of the slit 20 provided in the inner slit plate 30 is formed to be narrower than the opening of the slit 20 provided in the outer slit plate 40.

The outer size of the plasma generator is as follows.
Although not particularly limited, for example, a width of about 40 mm and a length of about 10
It is about 0 mm in height and about 46 mm in height. The size of the slit 20 formed in the inner slit plate is, for example, about 2.5 mm in width and about 40 mm in length. This slit size is usually selected experimentally from various conditions so that the plasma extraction efficiency is the highest.

FIG. 2C is an enlarged sectional view of the slit wall portion a of the front plate, which is surrounded by a broken line in FIG. 2B. As shown in FIG. 2C, a vertical opening 30p whose wall surface is perpendicular to the front surface is formed on the inner inner wall surface of the inner slit plate 30, and the wall surface is inclined with respect to the front surface on the outer inner wall surface. It has a tapered opening 30s. A tapered opening is formed on the inner wall surface of the outer slit plate 40.

The thickness of the inner slit plate 30 is about 2 mm, the thickness h1 of the vertical opening 30p is less than 0.3 mm,
Preferably, it is 0.2 mm or less. Tapered opening 30s
Is the thickness obtained by subtracting the thickness h1 of the vertical opening 30p from the thickness of the inner slit plate 30. The thickness h3 of the outer slit plate 40 is not particularly limited.
mm.

As shown in FIG. 2 (c), the opening angle θ1 of the tapered opening 30s of the inner slit plate 30 is desirably at least larger than 90 degrees, preferably 120 degrees or more. Also, the opening angle θ2 of the outer slit plate 40
Is 70 degrees or more and 90 degrees or less, for example, 80 degrees, which is smaller than the opening angle θ1 of the inner slit plate 30.

FIG. 3 shows a configuration of a power supply circuit necessary for generating plasma in the plasma generating apparatus. The plasma generation device 100 in the figure shows a cut surface cut in parallel with the front surface at the center of the plasma generation device.

A filament power supply 210 is provided between the extraction electrodes 50 of the two filaments. An arc power supply 220 is provided between one of the filament power supplies 210 and the plasma generator.

When generating plasma, first, a filament power supply is turned on, a current is applied to the filament, the filament is heated, and thermoelectrons are emitted. Thereafter, the arc power supply is turned on, a voltage is applied between the filament and the repeller plate, and thermoelectrons are drawn to the repeller plate 80.
For example, assume that the arc voltage is 70 to 75 V and the arc current is 3 A. When an ion source gas is supplied from the gas supply port 90 to the plasma generating apparatus 100, the electrons collide with these gases to generate plasma. Plasma is mainly generated between the filament 70 and the repeller plate 80.

As shown in FIG. 2B, the plasma generated in the plasma generating device is generated at the center of the front surface by the operation of the extraction electrode portion 120 (see FIG. 1) provided outside the plasma generating device 100. It is pulled out from the slit. The filament temperature during plasma generation is about 2000 ° C., and the plasma generator temperature is about 1000 ° C.
High temperature of ℃. The opening of the slit, particularly the inner tip 30e of the slit surrounded by the broken line in the figure, is heated to a high temperature because it is in direct contact with the plasma.

The front plate of the conventional plasma generator is
When the thickness of the tip of the inner wall of the slit, that is, the thickness of the vertical opening is smaller than 0.3 mm, the tip of the slit is easily deformed by the heat of the contacting plasma. The area of the part was expanding. As the plasma density that can be extracted is reduced, the amount of ion beams leaking to the surroundings without being picked up by the extraction electrode is increased, so that the effective ion beam extraction efficiency is reduced.

However, the front plate of the plasma generating apparatus according to the present embodiment is composed of two slit plates made of tungsten and molybdenum. Particularly, the inner slit plate 30 which is in direct contact with the plasma is more heat-resistant than molybdenum. Made of tungsten with good properties. Since the vaporization rate of tungsten is extremely low, about one thousandth of that of molybdenum, the vertical opening 30 which is the inner tip of the slit wall surface is used.
Even if the thickness of p is smaller than 0.3 mm, for example, 0.2 mm or less, the deformation of the slit is smaller than that of the conventional slit plate composed of one molybdenum plate.

When the height of the vertical opening is high, even if the opening angle of the tapered opening is widened, the effect of extracting plasma cannot be increased so much. However, when the inner slit plate 30 made of tungsten is used, the vertical opening 3
Since the height of 0p can be made smaller than 0.3 mm, the plasma extraction effect can be increased by increasing the opening angle θ1 of the tapered opening 30s to more than 90 degrees, for example, 120 degrees or more as described above. .

Since the opening angle θ2 of the outer slit plate 40 is smaller than the opening angle θ1 of the inner slit plate 30, the divergence angle of the ion beam emitted from the plasma generator to the outside can be reduced. Thus, the amount of ion beams leaked to the periphery without being taken into the ring of the extraction electrode portion can be reduced.

Further, by forming the inner slit plate 30 of tungsten, the deformation of the slit is suppressed.
The frequency of replacing the slit plate can be reduced. Moreover, since only the inner slit plate 30 needs to be replaced while the outer slit plate 40 made of molybdenum is kept as it is, the running cost can be further reduced.

FIG. 3 and FIG. 4 show an example of a plasma generating apparatus according to another embodiment of the present invention. If there is a front plate (30a, 30b, 40a, 40b) as shown in FIG. 2 having a configuration similar to that of the above-described embodiment, the means for generating thermoelectrons in the plasma generating apparatus is not limited. For example, as shown in FIG. 3, a plasma generating apparatus having a so-called Freeman type structure in which a single filament wire is disposed inside may be used. Further, the shape of the opening formed in the front plate is not limited to a slit shape.
As shown in FIG.

The above-described sizes such as the thickness of the inner slit plate, the height of the vertical opening, and the opening angle of the tapered opening have substantially the same effect even when the size of the plasma generating apparatus itself is slightly different. Bring.

The increase in the plasma extraction efficiency increases the amount of ion beams taken into the ring of the extraction electrode section, and as a result, the ion beam intensity that can be output from the ion implantation apparatus to the outside can be increased. For example, by using the above-described plasma generation apparatus shown in FIG. 2, the intensity of an ion beam that can be output from the ion implantation apparatus can be approximately doubled under the conventional plasma generation conditions.

The present invention has been described in connection with the preferred embodiments. However, the present invention is not limited to these embodiments. In the above-described embodiment, the front plate of the plasma generation chamber is composed of two plates, but it is also possible to use two or more plates. It will be obvious to those skilled in the art that various changes, improvements, combinations, and the like can be made.

[0053]

As described above, according to the plasma generating apparatus of the present invention, the front plate is constituted by a plurality of plate members. Since the deformation of the opening due to the increase in the frequency of use mainly occurs in the innermost plate, only the innermost plate needs to be replaced. Therefore, the running cost of the apparatus can be reduced.

If a material having high plasma resistance, such as tungsten, is used as the innermost plate, the life of the opening can be increased.

Further, since a slit having a thinner vertical opening and a tapered opening having a larger opening angle can be formed by using a material having high plasma resistance as the plate material disposed inside, the plasma generating apparatus The plasma generated inside can be more easily extracted to the outside of the apparatus, and the effective use efficiency of the plasma can be increased.

According to the ion implantation apparatus of the present invention,
Since the plasma generator having the above-described effects is used as the ion source, the ion beam intensity is stable, and the running cost can be reduced. The use of a plasma generating apparatus having a front plate having a slit having a thinner vertical opening and a tapered opening having a larger opening angle can increase the effective ion beam generation efficiency.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an ion beam device according to an embodiment of the present invention.

FIG. 2 is a front view, a cross-sectional view, and an enlarged cross-sectional view of a slit portion of the plasma generation device according to the embodiment of the present invention.

FIG. 3 is a circuit configuration diagram of the plasma generation device according to the embodiment of the present invention.

FIG. 4 is a cross-sectional view of another plasma generator according to the embodiment of the present invention.

FIG. 5 is a front view of another plasma generator according to the embodiment of the present invention.

FIG. 6 is an external perspective view, a cross-sectional view, and an enlarged cross-sectional view of a slit portion of a conventional plasma generation device.

FIG. 7 is a cross-sectional view of a plasma generating device and an extraction electrode for describing a state of a plasma beam extracted from a conventional plasma generating device.

[Explanation of symbols]

 Reference Signs List 20 slit 30 inner slit plate 40 outer slit plate 50 filament extraction electrode 60 repeller plate extraction electrode 70 filament 80 repeller plate 90 ion source gas Supply port 100 Plasma generator 120 Extractor electrode 130 Accelerator 140 Mass analyzer 150 Ion beam scanner 160 Beam corrector 170 Susceptor 180 ···substrate

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroshi Uchida 25-1, Ekimae Honcho, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Toshiba Microelectronics Corporation

Claims (7)

[Claims] 1. A plasma generating apparatus having means for generating plasma from an ion source gas in an apparatus, wherein a front plate of the apparatus has an opening for extracting the plasma to the outside, wherein the front plate has the A plasma generator comprising at least two or more plate members having an opening, wherein an opening of a plate member arranged inside is narrower than an opening of an adjacent outer plate member. 2. The plasma generating apparatus according to claim 1, wherein each of the plate members is formed of a different material, and a plate member disposed on the innermost side has the highest plasma resistance. 3. The plasma generating apparatus according to claim 1, wherein the innermost plate is formed of tungsten. 4. The opening of the innermost plate member has a vertical opening on the inner wall surface of the opening, the wall surface is perpendicular to the front surface, and the inner wall surface of the opening has a wall surface on the inner wall surface. The plasma generation device according to claim 3, further comprising a tapered opening inclined with respect to a front surface, wherein a height of the vertical opening is less than 0.3 mm. 5. The plasma generating apparatus according to claim 4, wherein an opening angle of the tapered opening of the innermost plate is at least larger than 90 degrees. 6. A plasma generating apparatus having means for generating plasma from an ion source gas in an apparatus, wherein a front plate of the apparatus has an opening for extracting the plasma to the outside, wherein the front plate is made of tungsten. And an outer second plate formed of molybdenum. The opening of the first plate is formed on the inner inner wall surface of the opening, and the wall is perpendicular to the front surface. A vertical opening, and a tapered opening in which the wall surface is inclined with respect to the front surface on the outer inner wall surface of the opening, wherein the height of the vertical opening of the first plate material is less than 0.3 mm. The opening angle of the tapered opening of the first plate is greater than at least 90 degrees, and the opening of the second plate has a tapered opening on the inner wall surface of the opening, the wall surface being inclined with respect to the front surface. Plasma generating apparatus the opening angle of the tapered apertures is less than 90 degrees 70 degrees of the second plate member. 7. A plasma generating apparatus, an extraction electrode section for extracting an ion beam from plasma generated by the plasma generating apparatus, and a section for selectively extracting a beam of a required ion species from the extracted ion beam. 7. A mass spectrometer, and a scanning unit for scanning the selectively extracted ion beam, wherein the plasma generation device is any one of claims 1 to 6.
An ion implantation apparatus characterized in that it is the plasma generation apparatus according to (1).