JPH0636732A - Ion implanter - Google Patents

Abstract

PURPOSE:To provide an ion implanter having high precision and good in-plane uniformity regardless of the energy level of an ion beam to be implanted. CONSTITUTION:An ion implanter is provided with the second suppressor electrodes 12, 13 suppressing the expansion of an ion beam 3 caused during the scanning process by scanning electrodes 6, 7. The voltage of a voltage variable power source 14 feeding the voltage to the second suppressor electrodes 12, 13 is regulated and controlled by a control device 15 in response to the voltage of the voltage variable power source 17 of an acceleration system 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion implantation apparatus used when forming an impurity layer on a semiconductor wafer in a semiconductor process.

[0002]

2. Description of the Related Art FIG. 5 is a diagram showing the structure of a conventional ion implantation apparatus. In the figure, 1 is an ion source for generating ions, 2 is an acceleration / deceleration electrode system for accelerating or decelerating an ion beam 3 from the ion source 1, and 4 is a target from among various ions generated by the ion source 1. A mass analyzer 5 for selecting ions to be injected into the semiconductor wafer 11, which is an injection sample, is necessary for ion injection into the semiconductor wafer 11 with respect to the ion beam 3 selected and emitted by the mass analyzer 4. An accelerating system for accelerating the energy beam to give energy, 6 and 7 are Y-axis scanning electrodes for scanning the ion beam 3 in the Y-axis direction and the X-axis direction, respectively, for irradiating the ion beam 3 to a required portion on the semiconductor wafer 11, An X-axis scanning electrode 8 is a first suppressor electrode to which a constant negative potential is applied, and secondary electrons generated on the upstream side move to the downstream side or are generated on the downstream side. To prevent the next electrons move to the upstream side. Reference numeral 9 is a mask that masks the ion beam 3 so that it is irradiated onto a desired portion of the semiconductor wafer 11, and 10 is a Faraday cup that detects the current of the ion beam 3 injected into the semiconductor wafer 11.

Next, the operation will be described. The speed of the ion beam 3 generated by the ion source 1 is adjusted by the acceleration / deceleration electrode system 2 and enters the mass analyzer 4, where only the ions necessary for implantation are selected. The selected ion beam 3 is accelerated to a required level by the acceleration system 5, and further the Y axis and X
It is scanned by the axial scanning electrodes 6 and 7 and irradiated onto a required portion of the semiconductor wafer 11. The first suppressor electrode 8 suppresses unnecessary movement of secondary electrons generated by the ion beam 3 in the implanter by applying a negative potential to the first suppressor electrode 8.

In this case, an alternating voltage is applied to the scan electrodes 6 and 7, and a negative voltage is applied to the first suppressor electrode 8, which are always kept at a predetermined value.
The voltage applied to the acceleration system 5 needs to be adjusted according to the required energy level for ion implantation into the semiconductor wafer 11.

[0005]

Since the conventional ion implantation apparatus is constructed as described above, particularly when the voltage applied to the acceleration system 5 is lowered and the ion beam 3 is ion-implanted at a low energy level. Depending on the energy level, the ion beam 3 itself may be affected by the electric field effect due to the potential applied to the first suppressor electrode 8. In addition, when the ion implantation is performed at a low energy level, the ion beam tends to spread in the scanning process by the scanning electrode, and the in-plane uniformity of the implanted semiconductor wafer deteriorates.

The present invention is intended to realize ion implantation performance with high precision and good in-plane uniformity, regardless of the energy level of the ion beam to be implanted.

[0007]

An ion implantation apparatus according to claim 1 of the present invention is arranged on the downstream side of a scanning electrode, and a secondary electron generated from the portion on the upstream side by applying a negative potential. Of movement of the secondary electrons to the downstream side and movement of secondary electrons generated on the downstream side from the portion to the upstream side
This suppressor electrode is provided, and the magnitude of the potential applied to this first suppressor electrode is made variable in relation to the voltage applied to the acceleration system.

An ion implanter according to a second aspect of the present invention is arranged on the downstream side of the scan electrode and applies a voltage having a waveform obtained by inverting the voltage applied to the scan electrode, thereby performing the scanning process. The second suppressor electrode for suppressing the spread of the ion beam generated in 1. is provided, and the magnitude of the voltage applied to the second suppressor electrode is made variable in relation to the voltage applied to the acceleration system.

[0009]

In the ion implanter according to the present invention, the potential applied to the first suppressor electrode is adjusted so as to decrease in accordance with the decrease in the voltage applied to the acceleration system.
As a result, the first suppressor electrode suppresses unnecessary movement of secondary electrons without affecting the behavior of the ion beam.

Further, the voltage applied to the second suppressor electrode is adjusted so that the voltage applied to the accelerating system decreases and the voltage increases accordingly. As a result, the spread of the ion beam due to scanning is suppressed.

[0011]

【Example】

Example 1. 1 is a diagram showing the configuration of an ion implantation apparatus according to a first embodiment of the present invention. In the figure, 3, 5 and 8 are the same as the conventional ones, and the explanation thereof is omitted. Further, the components 1, 2, 4, 9 to 11 described in FIG. 5 are not shown because they are out of the essential portion of the present invention.

Reference numerals 12 and 13 denote second suppressor electrodes arranged on the downstream side of the first suppressor electrode 8, and like the scanning electrodes 6 and 7, each pair forms a pair of electric fields in the Y-axis direction and the X-axis direction. It is composed of electrodes. Reference numeral 14 denotes a voltage variable power supply that supplies a voltage to the second suppressor electrodes 12 and 13, and the output voltage thereof is controlled by a control device 15 described later. Reference numeral 16 is a voltage variable power supply that supplies a voltage to the first suppressor electrode 8, and 17 is a voltage variable power supply that supplies a voltage to the acceleration system 5.

FIG. 2 shows the relationship between the voltage waveform applied to the second suppressor electrodes 12 and 13 and the voltage applied to the scan electrodes 6 and 7. Each voltage waveform shows the waveform of the voltage applied between the electrodes arranged in pairs in each direction.
The upper part of the figure shows the applied voltage to the scan electrodes 6 and 7, both of which are alternating voltages, but the applied voltage to the X-axis scan electrode 7 is shifted to the negative side because there is an offset in the scan in this direction. Because it is required.

The lower part of the figure shows the second suppressor electrodes 12, 1.
3 shows the waveform of the voltage applied to No. 3. As can be seen from the figure, the waveforms are such that the voltages applied to the scan electrodes 6 and 7 are inverted. The peak values p and q of the voltage applied to the second suppressor electrodes 12 and 13 are lower than the peak values m and n of the voltage applied to the scan electrodes 6 and 7, respectively (p <m. , Q <n), and the voltage applied to the acceleration system 5, that is, the voltage of the voltage variable power supply 17 decreases, the voltage increases accordingly. The controller 15 controls the adjustment according to a preset relationship.

When the voltage applied to the acceleration system 5 is set low and the energy level of the ion beam 3 is set low, the spread of the ion beam 3 due to the scanning of the scanning electrodes 6 and 7 cannot be ignored. The second suppressor electrodes 12 and 13 act in the direction of narrowing the ion beam 3 and keep the in-plane uniformity of the semiconductor wafer 11 based on the spread of the ion beam 3 in a good state. In this case, the lower the energy level of the ion beam 3 is, the wider the beam spreads at the scanning electrodes, and therefore the voltage applied to the second suppressor electrodes 12 and 13 also needs to be increased. However, the electric field applied by the second suppressor electrodes 12 and 13 does not affect the trajectory of the ion beam 3.

FIG. 3 shows a specific example of the electrode structure of the second suppressor electrodes 12 and 13 for effectively narrowing the spread ion beam 3. Although FIG. 3 (3) has the simplest configuration, each electrode has long sides in the traveling direction of the ion beam 3 ((1) in the same figure), or is similarly divided into a plurality of portions in the traveling direction ( The device shown in FIG. 2 (2) is devised. By applying different finely adjusted voltages to the divided electrodes, it becomes possible to irradiate the semiconductor wafer 11 without breaking the cross-sectional shape of the ion beam 3.

Example 2. FIG. 4 is a diagram showing the configuration of the ion implantation apparatus according to the second embodiment of the present invention. The difference from the case of FIG. 1 is that the control device 18 also adjusts and controls the voltage of the voltage variable power supply 16 to the first suppressor electrode 8.

That is, when the voltage applied to the acceleration system 5 is set low and the energy level of the ion beam 3 is set low, the electric field of the negative potential applied to the first suppressor electrode 8 causes the ion beam 3 to move. There is a possibility that the ion beam 3 itself may be affected due to a deviation of the trajectory. Control device 18
In order to eliminate this adverse effect, the voltage of the voltage variable power supply 17 is input to the acceleration system 5, and when this voltage becomes low, the voltage applied to the first suppressor electrode 8 also decreases accordingly. Therefore, regardless of the energy level of the ion beam 3, the first suppressor electrode 8 is
It properly achieves only its original purpose of preventing unnecessary movement of secondary electrons.

[0019]

As described above, the ion implanter according to the present invention is provided with the first suppressor electrode which makes the voltage variable in relation to the voltage applied to the accelerating system as described above. Regardless of the above, it becomes possible to suppress unnecessary movement of secondary electrons without affecting the ion beam itself.

The ion implanter according to claim 2 is
As described above, since the second suppressor electrode that changes the voltage related to the voltage applied to the acceleration system is provided, the spread of the ion beam due to scanning is suppressed regardless of the energy level of the ion beam. The in-plane uniformity of the ion beam on the sample to be implanted is kept in a good state.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an ion implantation apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing waveforms of voltages applied to second suppressor electrodes 12 and 13 of FIG.

FIG. 3 is a perspective view showing a specific example of an electrode configuration of second suppressor electrodes 12 and 13 of FIG.

FIG. 4 is a configuration diagram showing an ion implantation device according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram showing a conventional ion implantation apparatus.

[Explanation of Codes] 1 ion source 3 ion beam 5 acceleration system 6,7 scanning electrode 8 first suppressor electrode 11 semiconductor wafer as a sample to be injected 12,13 second suppressor electrode 14,16 voltage variable power supply 15,18 Control device

Claims (2)

[Claims] 1. An ion implantation apparatus for scanning an ion beam accelerated by an accelerating system with a scanning electrode to irradiate a sample to be implanted, the portion being disposed downstream of the scanning electrode and applying a negative potential to the portion. A suppressor electrode that suppresses the movement of secondary electrons generated on the upstream side from the downstream side to the downstream side and the movement of secondary electrons generated on the downstream side from the portion to the upstream side, and the first suppressor electrode is provided. An ion implanter characterized in that the magnitude of the potential applied to is variable in relation to the voltage applied to the acceleration system. 2. An ion implantation apparatus for scanning an ion beam accelerated by an accelerating system with a scanning electrode to irradiate a sample to be implanted, the ion implantation apparatus being arranged on the downstream side of the scanning electrode and inverting the voltage applied to the scanning electrode. By applying a voltage of different waveform,
A second suppressor electrode that suppresses the spread of the ion beam that occurs during the scanning process is provided, and the magnitude of the voltage applied to the second suppressor electrode is variable in relation to the voltage applied to the acceleration system. An ion implanter characterized by the above.