JPH04171648A - Ion implanter - Google Patents

Abstract

PURPOSE:To improve the transfer efficiency of ion beams and shrink the device size by making the passages of the ion beams parallel with two pairs of deflecting plates, and implanting the ion beams into a wafer rotated at a constant speed at the fixed desired angle. CONSTITUTION:A scanning controller 17 stores the output wave-forms to make the radiation time of ion beams 1 constant at all points of a wafer 11 in synchronization with the linear speed at each point on the wafer 11 for each ion species and implantation condition. The voltage is amplified by a scanning voltage source 3 and applied to deflecting plates 2, likewise the voltage with the same quantity and the opposite direction to that of the deflecting plates 2 is applied to deflecting plates 4 from a scanning voltage source 5. The ion beams 1 scanned by the deflecting plates 2 and made parallel by the deflecting plates 4 are scanned on a straight line by about the radius of the wafer 11 within the range from the outer periphery to the center of the wafer 11. The transfer efficiency of the ion beams 11 is improved, and the device can be miniaturized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ion implantation apparatus for implanting impurity ions into a wafer to perform impurity diffusion in a semiconductor manufacturing process.

[Conventional technology]

Conventionally, this type of ion implantation equipment has four sets of deflection plates so that the ion beam, which has been mass analyzed and accelerated to a desired energy, has a constant incident angle within the wafer plane, and each deflection plate has a continuous A scanning voltage source generating a triangular waveform is electrically connected. Using the principle that the ion beam can be scanned in parallel by scanning the ion beam with one set of deflection plates in the front stage and applying a voltage of the same magnitude to the set of deflection plates in the rear stage in the opposite direction to that of the front stage, the ion beam can be scanned in parallel. A total of four sets of deflection plates, two in the horizontal direction, and a scanning voltage source were used to make the incident angle of the ion beam constant at every point on the wafer.

[Problem to be solved by the invention]

The above-described conventional ion implantation apparatus uses four sets of deflection plates, which has the drawbacks that the beam line becomes long, resulting in poor ion beam transmission efficiency and a large scanning dimension.

[Means to solve the problem]

The ion implantation apparatus of the present invention includes a wafer holter connected to a motor for holding the wafer and rotating it at a constant speed;
a mask provided on the front surface of the wafer holder and having a length of approximately equal to the radius of the wafer;
Two sets of deflection plates are installed in series to linearly scan the ion beam from the center of the wafer to the outer periphery of the wafer using this mask, and two sets of deflection plates are connected to the two sets of deflection plates, respectively. scanning voltage sources, and voltages of different intensities are applied in stages to the two sets of deflection plates in order to make the ion beam irradiation time approximately constant at each point of the rotating wafer connected to these scanning voltage sources. and a scan controller for the scan controller.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a schematic sectional view of an embodiment of the present invention.

A motor 14 for holding the wafer 11 and rotating it at a constant speed
A mask 6 having a slit with a length approximately equal to the radius of the wafer 5 is disposed on the front surface of the wafer holder 12 connected to the wafer holder 12 . Two sets of deflection plates 2.4 are installed in series to linearly scan the ion beam 1 in the range up to the outer periphery, and each of the two sets of deflection plates 2, 4 is provided with a scanning voltage source. 3 and 5 are connected.

Then, in order to make the ion beam irradiation time almost constant at each point of the rotating wafer 11 connected to these scanning voltage sources, voltages with different intensities are applied in stages to the two sets of deflection plates 2.4. Scanning controller for D7
It has a connected structure.

The ion beam 1 is subjected to mass analysis and accelerated to a desired energy. The deflection plate 2 is electrically connected to a scanning voltage source 3, and the deflection plate 4 is electrically connected to a scanning voltage source 5. The mask 6 has a slit-like hole with a length approximately equal to the radius of the wafer 11. The suppressor electrode 7 is electrically connected to a suppressor power source 8 . The ammeter 9 is electrically connected to the Faraday case 1-0, the wafer 1], and the wafer holder 12, and detects the amount of ion beam. The wafer 11 and the wafer holder] 2 are connected to a motor 14 via an insulator 13 and rotated at a constant speed.

The motor driver 18 controls the rotation speed of the motor 14, and the scan controller 17 includes a storage device, a control device, an arithmetic device, an input device, an output device, etc.
It controls the output voltage of the scanning voltage source 5, and also sends and receives signals to and from the motor driver 18.

The ion beam 1 is incident on the deflection plate and is scanned by the electric field in the direction of the wafer 1-, while the neutral beam 15 is not scanned and is incident on the beam stop 6. The scanned ion beam 1 enters the deflection plate 4 and becomes parallel to the deflection plate 2 due to an electric field of the same magnitude and in the opposite direction, and the mask 6
A necessary amount of the wafer is taken out at , and is incident on the wafer 11 which is rotating at a constant speed according to a signal from the scan controller 17 .

The scan controller 17 outputs the output waveform shown in FIG. 2 such that the irradiation time of the ion beam 1 is constant at all points on the wafer 11 so as to synchronize with the linear velocity at each point on the wafer 11. The voltage is stored for each injection condition, and the voltage is amplified by the scanning voltage source 3 and applied to the deflection plate 2. Similarly, a voltage of the same magnitude and opposite direction to the deflection plate 2 is applied from the scanning voltage source 5 to the deflection plate 4 .

The ion beam 1 scanned by the deflection plate 2 and parallelized by the deflection plate 4 is scanned in a straight line by approximately the radius of the wafer 11 from the outer periphery to the center of the wafer 11 as shown in FIG. be done.

In this way, according to this embodiment, the ion beam is parallelized by two sets of deflection plates, and it is only necessary to scan about half the length of the wafer, which improves the transmission efficiency of the ion beam and reduces the equipment cost. Can be made smaller.

〔Effect of the invention〕

As explained above, the present invention makes the paths of the ion beam parallel with two sets of deflection plates, and implants the ion beam into a wafer rotating at a constant speed at a certain desired angle, thereby shortening the beam line. Improve beam transmission efficiency,
Moreover, there is an effect that the size of the device can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of an embodiment of the present invention, and FIGS. 2 and 3 are diagrams showing the output waveform of a scanning power source and the relationship between time and beam position. ]... Ion beam, 2... Deflection plate, 3... Scanning voltage source, 4... Deflection plate, 5... Scanning voltage source, 6...
・Mask, 7. Suppressor, 8. Suppressor power supply,
9... Ammeter, 1-0... Faraday case, 11
...Wafer, 12...Wafer holder, 13.
...Insulator, 14...Motor, 15...Neutral beam, ]6...Beam stop.

Claims (1)

[Claims] A wafer holder connected to a motor to hold and rotate the wafer at a constant speed, a mask provided on the front of the wafer holder with a slit approximately equal in length to the radius of the wafer, and a wafer Two sets of deflection plates installed in series to linearly scan the ion beam in the range from the center to the outer periphery;
two sets of scanning voltage sources respectively connected to the sets of deflection plates;
a scan controller that is connected to these scan voltage sources and applies voltages of different strengths in stages to the two sets of deflection plates in order to make the ion beam irradiation time at each point of the rotating wafer substantially constant; An ion implantation device comprising: