JP2684475B2 - Atomic beam injector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an atomic beam implanter,
More specifically, the present invention relates to an atomic beam implanter for implanting a dopant into a semiconductor wafer using a high speed atomic beam.

[0002]

2. Description of the Related Art In the semiconductor industry, a process of doping a semiconductor wafer with a small amount of impurities (dopants) such as phosphorus and arsenic to make the surface of the wafer a p-type semiconductor or an n-type semiconductor is essential. A thermal diffusion method, an ion implantation method, and the like have been proposed as a dopant implantation method in the related art. At present, however, the ion implantation method is becoming the mainstream because the implantation amount or the dopant distribution to be implanted can be precisely controlled. FIG. 8 is a configuration diagram showing an example of an ion implantation apparatus used in this ion implantation method. In the figure, 1 is an ion source, 2 is a mass separation device, 3 is a semiconductor wafer, 4 is a disk on which the wafer 3 is mounted, 5 is a Faraday cup, and 6 is an ion beam. The Faraday cup 5 is movable and is movably provided on the front surface of the disk 4 irradiated with a beam. Further, each of the above components is arranged in a vacuum container (not shown).

In this ion implanter, an ion source 1 ionizes and accelerates a dopant to be implanted in a semiconductor wafer 3 to emit an ion beam 6. Impurities are separated from the ion beam 6 while passing through the mass separation device 2, and bombard the surface of the wafer 3 on the disk 4.
At that time, since the kinetic energy of the ion beam 6 is very large, the ionic dopant penetrates into the inside of the wafer 3 to form a p-type or n-type semiconductor wafer. In such a semiconductor wafer, it is important that the dopant is always implanted in a constant amount. Therefore,
In the conventional technique, the Faraday cup 5 is moved immediately before the disk before the start of the dopant injection, the ion beam 6 is received by the Faraday cup 5, and the electric quantity of the beam is measured. The ion source 1 is controlled so that Next, the Faraday cup 5 is moved again to retract from the path of the ion beam 6, and then ion implantation is started to bombard the ion beam 6 to stabilize the dose of the dopant.

[0004]

However, in such a conventional method, since the ion beam 6 is charged, when the ions enter the wafer 3, the insulating structure of the element previously formed on the wafer is charged with ionic charges. Dielectric breakdown may occur due to discharge and / or discharge. Moreover, the Joule heat generated by the ion beam current may destroy the wiring in the element. Therefore, in the prior art, the yield of element manufacturing is significantly reduced due to these troubles. The present invention has been made in view of the above circumstances, and provides an atomic beam implanting apparatus for implanting a dopant using an uncharged beam in order to prevent destruction of an element due to charging / discharging or Joule heat. The purpose is.

[0005]

The above object of the present invention is to hold a fast atom beam source for generating at least an electrically neutral atomic or molecular dopant, and a semiconductor wafer to which a fast atom beam is implanted. And a high-speed atom beam counter for measuring the dose of the high-speed atom beam, and the dose of the dopant injected by feeding back the dose of the atom beam measured by the high-speed atom beam counter to the high-speed atom beam source. Achieved by a controlled atomic beam implanter.

[0006]

By performing the dopant implantation using an electrically neutral high-speed atomic beam, it is possible to prevent the dielectric breakdown of the element due to the charging or discharging of ionic charges. Further, prior to the implantation, the high-speed atomic beam counter measures the dose of the atomic beam and controls the high-speed atomic beam source based on the measurement result, whereby the implantation amount of the dopant to be implanted can be precisely controlled.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an atomic beam implanter according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic diagram for explaining the configuration of an atomic beam implanting apparatus according to an embodiment of the present invention, and FIG. 2 is a configuration diagram of a high speed atomic beam counting apparatus applied to the apparatus of FIG. 1, respectively. In each of the following embodiments, the same symbols are used for the configurations having the same functions and actions as those of the conventional device of FIG. In FIG. 1, this atom beam implanter implants a fast atom beam source 21 that accelerates and emits an electrically neutral fast atom beam 23 with a dopant such as phosphorus or arsenic, and the fast atom beam 23. Disk 4 on which the semiconductor wafer 3 can be mounted, and a high-speed atomic beam counting device 22 having a moving mechanism (not shown). The high-speed atomic beam counting device 22 can be inserted into or retracted from the position immediately before the disk front surface facing the atomic beam source between the high-speed atomic beam source 21 and the disk 4 by its moving mechanism. It is provided in.

As shown in FIG. 2, the high-speed atomic beam counting device 22 has an inlet 24 through which the high-speed atomic beam 23 is introduced.
And a solid-state target 31 and a vibrator-type film thickness meter 32 are arranged inside the structure. The solid target 31 is an incident fast atom beam 23.
So as to be impacted by the vibrator type film thickness meter 3
Reference numerals 2 are arranged so that the sputtered particles adhere to the surface thereof, and the vibrator-type film thickness meter 32 measures the adhered amount from the change amount of the resonance frequency caused by the adhered sputtered particles. Although not shown in FIG. 1, the high-speed atomic beam source 21 is fed back with the measurement result of the vibrator-type film thickness meter 32, and the configuration thereof is, for example, Japanese Patent Application No. 3860/1990.
In No. 7, the one already proposed by the applicant can be used. That is, this fast atom beam source introduces a reaction gas from the anode side of a plate-shaped anode and a plate-shaped cathode which are arranged to face each other, and gas ions generated by plasma discharge performed under a low discharge voltage are fast-atomized. After being converted into a line, the atomic beam is emitted from the emission hole provided in the cathode.

Next, the operation of the atomic beam implanter having the above-described structure will be described. In this implanter, the high-speed atomic beam counter 22 is used for the disk 4 before the dopant is implanted.
Moved to the front. The fast atom beam counter 22 receives the fast atom beam 23 emitted by the fast atom beam source 21 through its inlet 24. As a result, the solid target 3
The surface constituent substance of No. 1 is sputtered by the incident high-speed atomic beam 23, and the sputtered particles are accumulated on the surface of the vibrator-type film thickness meter 32. The frequency of the vibrator-type film thickness meter 32 changes due to the accumulated sputtered particles, which causes the amount of the sputtered substance on the target 31 to be
As a result, the fast atom beam 23 incident on the target 31
Calculate the dose of

Generally, it can be considered that the sputtering phenomenon of a solid surface hit by a high-speed atomic beam is exactly the same as the sputtering by a high-speed ion beam bombardment. Therefore, the target 31 is bombarded with an ion beam whose dose is known in advance. Then, if the amount of sputter is calibrated, the dose of the fast atom beam 23 can be measured.
The fast atom beam source 21 can be controlled so that the amount of the fast atom beam 23 incident on is always constant. Therefore, the measurement result is fed back to the fast atom beam source 21, and the dose of the fast atom beam 23 incident on the wafer 3 is controlled to be always constant. Then, the counting device 22
Is evacuated from just before the disk 4, and the fast atom beam source 2
1 emits a dopant such as phosphorus or arsenic as an electrically neutral high-speed atomic beam 23 and bombards the wafer 3 mounted on the disk 4. As a result, the dopant is injected inside the wafer.

FIG. 3 shows another embodiment of the high speed atomic beam counting apparatus applied to the present invention. The atomic beam implanter is
The parts other than the high-speed atomic beam counting device are configured in the same manner as in FIG. 1, and therefore only the high-speed atomic beam counting device will be described here. This high-speed atomic beam counting device 40 is a solid target 4 that is bombarded by a high-speed atomic beam 23 incident on the inside of a structure having a shape similar to that of FIG.
1 and secondary electron detection means, and the solid target 4
The secondary electron collecting electrodes 42 for detecting the secondary electrons emitted from the No. 1 are respectively arranged. The target 41 is kept at a higher negative potential than the secondary electron collecting electrode 42.

Next, the operation of the high speed atomic beam counter 40 will be described. The solid target 41 receives the impact of the fast atom beam 23 and emits secondary electrons. The secondary electrons are collected by the secondary electron collecting electrode 42 having a high electric potential.
Here, if the target 41 is bombarded with an ion beam whose dose is known in advance and the secondary electron flow flowing into the secondary electron collecting electrode 42 is calibrated, high speed is achieved as in the case of the previous embodiment. The dose of the atomic beam 23 can be measured. After measuring the dose of the fast atom beam 23 in this way, the measurement result is fed back to the fast atom beam source 21 and controlled so that the dose of the fast atom beam 23 is always constant.

FIG. 4 shows still another embodiment of the high speed atomic beam counting apparatus applied to the present invention. Also in this embodiment, the atomic beam implanter is configured as shown in FIG. 1 in the same manner as in the previous embodiment except for this high-speed atomic beam counter, except for the high-speed atomic beam counter. Only the injection device will be described. This high-speed atomic beam counter 50
Is a solid target 51 that is bombarded by an incident high-speed atomic beam 23 inside a structure having a shape similar to that shown in FIG.
And a thermocouple 52 which is a temperature detecting means in contact with the solid target 51. In the fast atom beam counter 50, when the solid target 51 receives the impact of the fast atom beam 23 and rises in temperature, the thermocouple 52 measures this temperature.

Generally, it is said that the temperature rising phenomenon of a solid surface hit by a high-speed atom beam is exactly the same as the temperature rising by a high-speed ion beam bombardment. Impact the thermocouple 52
If the temperature is measured and calibrated by the
A dose of 3 can be measured. Therefore, the fast atom beam source 21 is controlled so that the measured dose is fed back to keep the dose of the fast atom beam 23 incident on the wafer 3 constant. When the inflowing dose is controlled to be constant, the counting device 50 is retracted from the front surface of the disc as in the embodiment of FIG. Then, the fast atom beam source 21 emits the dopant as a fast atom beam 23 which is electrically neutral and bombards the wafer 3.

FIG. 5 shows still another embodiment of the high speed atomic beam counting apparatus applied to the present invention. Also in this embodiment, the atomic beam implanter is configured in the same manner as the embodiment of FIG. 1 except for the high-speed atomic beam counter.
In the high-speed atomic beam counting apparatus 60, a thermoelectron emission filament 61 and an ion collecting electrode 63 are arranged to face each other with an electron accelerating grid 62 sandwiched inside a structure having a shape similar to that of FIG. . An ammeter 64, which is an ion current detecting means, is connected to the ion collecting electrode 63. The electron acceleration grid 62 is kept at a higher positive potential than the thermionic emission filament 61, and the filament 6
1 accelerates the emitted electrons. On the other hand, the ion collecting electrode 63 is kept at a higher negative potential than the electron acceleration grid 62.

The high-speed atomic beam counter 60 bombards the incident high-speed atomic beam 23 with the electrons generated in the filament 61 and accelerated in the grid 62 to be ionized.
The ions thus generated are collected by the ion collecting electrode 63. Therefore, by measuring the ion current collected by the collecting electrode 63, the amount of ionized fast atom beam 23 can be known. In this way, the high-speed atomic beam 23
If the ionization efficiency of is measured, the dose of the fast atom beam 23 can be measured.

FIG. 6 shows another embodiment of the atomic beam implanter according to the present invention. This atomic beam implanting apparatus includes a high-speed atomic beam source 21 that accelerates and emits a dopant such as phosphorus or arsenic as an electrically neutral high-speed atomic beam 23, and a semiconductor wafer 3 into which the high-speed atomic beam 23 is implanted. A disk 14 that is mountable and rotatably provided;
It is composed of a high-speed atomic beam counter 71. As shown in the front view of FIG. 7, the disk 14 is provided with an appropriate number of slits 7 through which the high-speed atomic beam 23 is transmitted, in the basin other than the area where a plurality of semiconductor wafers 3 are mounted. In this embodiment, two are provided in the diameter direction. Behind the disk 14, the high-speed atomic beam counting device 71 for measuring the dose of the high-speed atomic beam transmitted through the disk 14 is fixedly arranged.

In the atomic beam implanter having the above-described structure, when implanting the dopant, the disk 14 first rotates so that the slit 7 is directed in the direction in which the high speed atomic beam 23 enters.
At this time, the high-speed atomic beam counter 71 and the slit 7 are arranged so as to be aligned, and the high-speed atomic beam 23 that has passed through the slit 7 flows into the high-speed atomic beam counter 71. The high-speed atomic beam counter 71 uses the high-speed atomic beam 23
Is measured and the measurement result is fed back to the fast atom beam source 21. Then the disk 14 rotates again,
The wafer 3 is oriented in the direction of the fast atom beam 23. Then, the high-velocity atomic beam 23 can impact the wafer 3 and penetrate the inside of the wafer to inject the dopant. The high-speed atomic beam counting apparatus 71 is the same as that of FIG.
The one shown in FIG. 5 is appropriately selected, and the dose of the fast atom beam is measured based on the process described above.

[0019]

As described above, according to the atomic beam implanting apparatus of the present invention, the incident beam for ion implantation is made non-chargeable, so that the element previously formed on the semiconductor wafer is charged with ion charges and / or charged. Dielectric breakdown does not occur. In particular, due to the non-charging property of the incident beam, it is possible to completely prevent the dielectric breakdown due to the decrease in the dielectric strength caused by the extreme miniaturization of the element and the thinning of the wiring in the element in recent years. Also, the atomic beam implanter is a semiconductor
A high-speed atomic beam counter installed separately from the wafer
Irradiate the target with a high-speed atomic beam to predict its dose in advance.
Impact the semiconductor wafer after measuring and controlling
Therefore, the dose of the dopant to be implanted is precise and
The dopant can be injected with stabilization. Further, the destruction of the wiring portion due to the Joule heat accompanying the inflow of the ion current can be completely prevented, and the production yield of the device can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration of an atomic beam implanter according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a high-speed atomic beam counter used in the atomic beam injector of FIG.

3 is a configuration diagram of a high-speed atomic beam counter according to another embodiment used in the atomic beam implanter of FIG.

FIG. 4 is a configuration diagram of a high-speed atomic beam counting apparatus according to still another embodiment used in the atomic beam implanting apparatus of FIG.

5 is a configuration diagram of a high speed atomic beam counting apparatus according to still another embodiment used in the atomic beam implanting apparatus of FIG.

FIG. 6 is a schematic configuration of an atomic beam implanter according to another embodiment of the present invention.

FIG. 7 is a front view illustrating a state of a disk used in the atomic beam implanting apparatus of FIG.

FIG. 8 is a configuration diagram of a conventional ion implantation device.

[Explanation of symbols]

 3 Semiconductor wafer 4, 14 Disk 7 Slit 21 High-speed atomic beam source 22, 40, 50, 60 High-speed atomic beam counter 23 High-speed atomic beam 31, 51, 51 Solid target 32 Transducer type film thickness meter 42 Secondary electron collecting electrode 52 thermocouple 61 thermionic emission filament 62 electron acceleration grid 63 ion collection electrode

Continuation of front page (56) Reference JP-A-3-152848 (JP, A) JP-A-62-40369 (JP, A) JP-A-2-276145 (JP, A) JP-A-2-249947 (JP , A)

Claims (5)

(57) [Claims] 1. A high-speed atomic beam source for generating at least an electrically neutral atomic or molecular dopant, a disk on which a semiconductor wafer on which a high-speed atomic beam is implanted is mounted, and a movably arranged front surface of the disk. And a high-speed atom beam counter for measuring the dose of the high-speed atom beam, wherein the high-speed atom beam source is controlled based on the dose of the high-speed atom beam measured by the high-speed atom beam counter. Atomic beam injector. 2. A high-speed atomic beam source for generating at least an electrically neutral atomic or molecular dopant, and a semiconductor wafer on which a high-speed atomic beam is implanted are mounted,
A rotatable disk provided with a slit that transmits the high-speed atomic beam in an area excluding the semiconductor wafer,
A high-speed atom beam counter arranged behind the disk for measuring the dose of the high-speed atom beam, and the high-speed atom beam source is controlled based on the dose of the high-speed atom beam measured by the high-speed atom beam counter. An atomic beam implanter characterized by the above. 3. The high-speed atomic beam counter comprises a solid target bombarded by an incident high-speed atomic beam, and secondary electron detection means for detecting secondary electrons emitted from the solid target. The atomic beam implanter according to claim 1 or 2. 4. The high-speed atomic beam counting device comprises a solid target bombarded by an incident high-speed atomic beam, and a temperature detecting means for detecting a temperature rise of the solid target. 2. The atomic beam implanter according to 2. 5. The high-speed atomic beam counting apparatus comprises an ionization mechanism for ionizing an incident high-speed atomic beam and an ion current detecting means for detecting a current of ionized ions. The atomic beam implanter described.