JP2000188082A - Ion implanting method and ion implanter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent creation of a pinhole to form a buried oxide film layer with no defect caused by the pinhole, even if particles deposit to a wafer surface. SOLUTION: This ion implanting method of an ion beam 1 to a wafer 3 comprises an ion implanting process wherein the ion beam 1 is implanted into a wafer surface at a slant angle and an ion implanting process wherein the ion beam 1 is implanted into the wafer surface at a different slant angle from the preceding slant angle. The respective processes are repeated with varying the slant angles in the respective processes such that a total ion implantation amount in the respective processes becomes a prescribed implantation amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ion implantation method and an ion implantation apparatus, and more particularly to an ion implantation method and an ion implantation apparatus for implanting ions into a wafer by an ion beam.

[0002]

2. Description of the Related Art As an example of a conventional ion implantation method, there is a method in which a wafer is arranged on the circumference of a rotating disk, the wafer is inclined from 0 to 14 degrees with respect to an ion beam, and ions are implanted from one direction. .

FIG. 6 shows a SIMOX (Separatio).
SOI (Silicon on Insulat) manufactured by n by Implanted Oxygen
or) shows a cross section of the wafer, the oxygen ion beam 1
, An SiO ₂ layer 4 (buried oxide film layer) is formed inside the Si wafer 3.

[0004]

In the above-described conventional ion implantation method, the ion beam 1 is blocked by the particles 2 attached to the surface of the Si wafer 3, so that the SiO ₂ layer 4 formed by ion implantation is Pinholes 5, which are uninjected portions, are generated, and the upper Si layer and the lower Si layer are partially in a conductive state, and are not completely insulated and defective. For this reason, there is a problem that the quality of the manufactured SOI wafer is deteriorated. SUMMARY OF THE INVENTION It is an object of the present invention to provide an ion implantation method and an ion implantation apparatus which do not generate pinholes even when particles adhere to a wafer surface and enable formation of a defect-free SiO ₂ layer.

[0005]

The present invention employs the following means in order to solve the above-mentioned problems.

In an ion implantation method for injecting an ion beam into a wafer, a step of injecting ions while tilting a wafer surface with respect to the ion beam is performed, and the angle of the wafer surface with respect to the ion beam is different from the angle of the tilt. Implanting ions obliquely at an angle, wherein the total implanted amount of ions implanted in each of the steps is a predetermined implanted amount.

In an ion implantation method for implanting an ion beam into a wafer, a step of injecting ions by tilting the wafer surface with respect to the ion beam, and the step of tilting the wafer surface with respect to the ion beam by the angle of the tilt are performed. Implanting ions at an angle different from the above, repeating each of the steps by changing the angle of each of the inclinations in each of the steps, and setting a total implantation amount of ions to be implanted in each of the steps at a predetermined value. It is characterized by the injection amount.

In the ion implantation method for injecting an ion beam into a wafer, a step of injecting ions while tilting the wafer surface with respect to the ion beam is performed, and the step of tilting the wafer surface with respect to the ion beam is opposite to the tilt. A step of implanting ions in a direction and inclined at substantially the same angle as the angle of inclination, and repeating each of the steps by changing the angle of each inclination in each of the steps; The total injection amount is a predetermined injection amount.

In an ion implantation method for implanting an ion beam into a wafer, a step of injecting ions by tilting a wafer surface with respect to the ion beam, and causing the wafer to rotate around a rotation axis perpendicular to the wafer surface. The method is characterized in that the steps are repeated while changing the rotation angle considerably from the step of rotating by an arbitrary rotation angle, and the total implantation amount of ions implanted in each step is set to a predetermined implantation amount.

In an ion implantation method for implanting an ion beam into a wafer, the wafer surface is inclined with respect to the ion beam while continuously rotating the wafer around a rotation axis perpendicular to the wafer surface. The method comprises the step of implanting ions, wherein the total implantation amount of ions implanted in the step is a predetermined implantation amount.

In the ion implantation method for implanting an ion beam into a wafer, the irradiation is performed while continuously changing the irradiation angle of the ion beam on the wafer surface.
Implanting ions by changing implantation energy so that the implantation depth in the vertical direction from the wafer surface at each of the irradiation angles is substantially the same. Is characterized by the injection amount.

Further, in the ion implantation method according to any one of claims 1 to 6, the ion beam is oxygen ions, and the energy of the ion beam is in a range of 30 to 250 keV. It is characterized by the following.

Further, in the ion implantation method according to any one of claims 1 to 7, the total amount of the implanted ions is 1 × 10 ¹⁸ / cm.
² or less.

In an ion implantation apparatus for injecting an ion beam into a wafer, a rotating disk rotatably provided and having a wafer disposed near a circumference thereof, and ion beam irradiation means for irradiating the wafer with the ion beam When,
And a wafer tilt angle varying means for tilting the wafer surface at an arbitrary angle with respect to the ion beam.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a first embodiment of the present invention will be described with reference to FIG.

FIGS. 1 (a) and 1 (b) show SIs manufactured by the ion implantation method according to the present embodiment, respectively.
FIG. 4 is a diagram showing a cross section of a wafer at the time of ion implantation of a MOX substrate.

In these figures, 1 is an oxygen ion beam, 2 is particles adhering on a Si wafer, 3
Is a Si wafer, 4 is an SiO ₂ layer formed by ion implantation of about half of the initial amount inside the Si wafer 3, 5 is a pinhole not ion-implanted formed at the time of ion implantation of about half of the initial amount, Reference numeral 9 denotes an SiO ₂ layer formed by ion implantation of the entire amount inside the Si wafer 3, 10 denotes an SiO ₂ layer in which the pin holes 5, which have not been ion-implanted, are formed by subsequent ion implantation, and 11 denotes an SiO ₂ layer formed by initial ion implantation. This is the SiO ₂ layer that has not been ion-implanted in the subsequent ion implantation.

First, the ion implantation method of this embodiment is as follows.
As shown in FIG. 1A, the Si wafer 3 is tilted and about half of the total implantation amount is implanted by the oxygen ion beam 1. The inclination angle of the Si wafer 3 with respect to the ion beam 1 at this time is, for example, when the horizontal direction in the drawing is 0 degree,
It is set in the range of 7 to 14 degrees. Next, the ion beam 1 is stopped, and then, as shown in FIG. 1B, the Si wafer 3 is tilted by the same angle in a direction opposite to the direction in which the Si wafer 3 was initially tilted, and the remaining Si wafer 3 is About half of oxygen ions are implanted. The inclination angle is set in a range from -7 degrees to -14 degrees with the horizontal direction in the figure being 0 degree.

According to the present embodiment, as shown in FIG. 1A, the SiO _{2 is} implanted into the Si wafer 3 to a depth corresponding to the ion implantation energy by ion implantation of about half of the total implantation amount.
Layer 4 is formed. At the time of this ion implantation, the Si wafer 3
If particle 2 is attached on top, particle 2
The pinhole 5 is formed because the portion in the shaded area is not injected. However, as shown in FIG. 1 (b), by inclining the Si wafer 3 in the opposite direction and performing the ion implantation of the remaining half, the pinhole 5 which has not been implanted first is obtained.
Also, the SiO ₂ layer 10 is formed by the subsequent ion implantation. In the later ion implantation, the SiO ₂ layer 11 is newly ion-implanted due to the shadow of the particles 2, but since the ion implantation is performed in the first ion implantation, there is no unimplanted portion as a whole. Although the above-described ion implantation is performed twice, the same effect can be obtained by repeating the ion implantation a plurality of times to obtain the final implantation amount.

Next, a second embodiment of the present invention will be described with reference to FIG.

FIGS. 2A and 2B are perspective views of the Si wafer at the time of ion implantation formed by the ion implantation method according to the present embodiment.

The reference numerals shown in these figures correspond to the parts shown in FIG.

First, the ion implantation method of the present embodiment
As shown in FIG. 2A, the Si wafer 3 is tilted and ion implantation of about half of the total implantation amount by the oxygen ion beam 1 is performed. Thereafter, the ion beam 1 is stopped, and as shown in FIG. 2B, the tilt angle of the Si wafer 3 is kept as it is, the Si wafer 3 is rotated around the Si wafer 3, and the other half is rotated. A quantity of ions is implanted.

According to the present embodiment, as shown in FIG. 2A, the SiO _{2 is} implanted into the Si wafer 3 at a depth corresponding to the ion implantation energy by ion implantation of about half of the total implantation amount.
When the layer is formed and the particles 2 adhere to the Si wafer 3, the portion shaded by the particles 2 is not injected, so that the pinhole 5 is formed. However, as shown in FIG. 2 (b), the remaining half of the ions are implanted by rotating the Si wafer 3, so that the pinholes 5, which had not been implanted first, are also implanted by later ion implantation.
An O ₂ layer 10 is formed. In the ion implantation after the rotation, the SiO ₂ layer 11 is newly ion-implanted due to the shadow of the particles 2. However, since the ion implantation is performed by the ion implantation before the rotation, the unimplanted portion is eliminated as a whole. Although the above-described ion implantation is performed twice, the same effect can be obtained by continuously rotating the Si wafer 3 during the ion implantation or by repeating implantation and stopping a plurality of times.

Next, a third embodiment of the present invention will be described with reference to FIGS.

FIG. 3 is a diagram showing the configuration of the ion implantation apparatus according to this embodiment.

In the figure, 20 is an ion source, 21 is a mass separator, 22 is a post-accelerator tube, 23 is a quadrupole lens, 2
4 is a deflecting magnet, 6 is a rotating disk on which a plurality of Si wafers 3 are placed and rotated, 28 is an angle adjuster, 27 is an angle sensor that measures the tilt angle of the rotating disk 6, 26 is a control device, 25 is This is a power supply 25 for post-acceleration. The same reference numerals as those shown in FIG. 1 indicate the same parts.

In FIG. 1, the ion beam 1 generated by the ion source 20 is accelerated to, for example, 50 kV, passes through the mass separator 21, and is further accelerated to, for example, 180 kV by the post-acceleration tube 22. Next, the quadrupole lens 23
The ion beam 1 is shaped by the
It is injected into the i-wafer 3. The rotating disk 6 on which a plurality of Si wafers 3 are arranged on the circumference moves left and right or up and down across the ion beam 1 while rotating. Here, the ion beam 1 may be moved right and left or up and down. At this time, by changing the inclination of the rotating disk 6 by the angle adjuster 28, the injection angle into the Si wafer 3 can be changed.

In general, in ion implantation, the distance at which ions enter the inside of the Si wafer 3 is determined by the energy of the ion beam 1.
The position of the SiO ₂ layer from the surface of the Si wafer 3 changes due to the inclination. For this reason, the thickness of the SiO ₂ layer is different from that in the normal injection from one direction. In SIMOX wafers, film thickness uniformity is also an important requirement relating to quality. For this reason, the angle at which the Si wafer 3 is tilted by the angle adjuster 28 is measured by the angle sensor 27, the implantation energy corresponding to the angle is determined by the control device 26, and the post-acceleration power supply 25 is controlled to control the energy of the ion beam 1. Control.

FIGS. 4A and 4B respectively show a plurality of Si wafers 3 arranged on the circumference of the rotating disk 6 of the ion implantation apparatus shown in FIG. It is a figure at the time of inclining to a position. After about half of the final injection amount is injected in the state shown in FIG.
As shown in (b), the entire rotating disk 6 is
Is moved to a position symmetrical with respect to and tilted, and control is performed so as to perform injection up to the final injection amount.

Note that the same effect can be obtained by repeating such control several times so that the final injection amount is obtained. Further, the injection amount from the inclination of the rotating disk to the next inclination may not be uniform.

As described above, according to the present embodiment, Si
Since the implantation angle of the wafer 3 changes, the wafer 3 is also implanted into the non-implanted portion, and pinholes are not generated. Further, the variation of the implantation depth due to the change of the angle can be suppressed. Although not shown, the same effect can be obtained even if the energy of the ion beam 1 is changed by controlling the power supply for the ion source 20 by the control device 26.

Next, a fourth embodiment of the present invention will be described with reference to FIG.

FIG. 5 shows a state in which a plurality of Si wafers 3 arranged on the circumference of the rotating disk 6 are tilted at symmetric positions with respect to the ion beam 1 by using an apparatus similar to the ion implantation apparatus shown in FIG. FIG. 4 is a diagram when the wafers are arranged and rotated, and each Si wafer 3 is rotated. In the present embodiment, while the third embodiment rotates the rotating disk 6 and tilts the rotating disk 6, the third embodiment rotates about the rotation axis of the rotating disk 6 and simultaneously rotates the rotating disk 6. The difference is that the Si wafer 3 is mounted on the inclined portion of the circumference of the plate 6 and is further rotated for each Si wafer 3.

In the figure, a Si wafer 3 is a rotating disk 6
A plurality of Si wafers 3 are inclined and arranged on the circumference of the circle, and each Si wafer 3 rotates around the center of the Si wafer 3. Further, the rotating disk 6 moves left and right or up and down for uniform injection while rotating. Further, the ion beam 1 may be moved right and left or up and down.

In this embodiment, each Si wafer 3 is arranged at a position inclined with respect to the ion beam 1, but the rotating disk 6 itself may be inclined. In this state, an operation is performed to perform ion implantation up to the final implantation amount.

As described above, according to the present embodiment, Si
Since the implantation angle of the wafer 3 changes, the wafer 3 is also implanted into the non-implanted portion, and pinholes are not generated. Further, the variation of the implantation depth due to the change of the angle can be suppressed. Note that the same effect can be obtained even if the Si wafer 3 is rotated continuously or repeatedly rotated and stopped.

In each of the above embodiments, the ion implantation energy is 30 to 250 keV, and the implantation amount is 2 × 10 5
^A remarkable effect was confirmed at ¹⁸ particles / cm ² or less.

When ions are implanted into a Si wafer, not all of them are implanted straight, but spread laterally due to the implantation energy. This spread depends on the implantation energy, the lower the energy, the greater the spread, and the higher the energy, the smaller the spread. Because of this spread, if the energy is too low, the pinholes will disappear due to the spread ions, so that the effects of the present invention cannot be achieved if the ion implantation energy is 30 keV or less. When the ion implantation energy is increased, a SiO ₂ layer is formed at a deep position.
The device to be actually formed is several hundred nanometers or less, and if it is larger than this, device formation becomes difficult. The ion implantation energy at this time is 250 keV.

Further, by injecting the amount of oxygen ions and 2 × 10 ¹⁸ / cm ² or less, it is proper SiO ₂ in chemical composition, it is possible to form a desired SiO ₂ layer.

In each of the above embodiments, the SIMO
The present invention can be used not only for manufacturing a wafer for X but also for forming other insulators such as a nitride film.

[0042]

As described above, according to the present invention, even if particles adhere to the wafer surface, pinholes do not occur and a defect-free SiO ₂ layer can be formed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cross section of a SIMOX substrate manufactured by an ion implantation method according to a first embodiment of the present invention at the time of ion implantation.

FIG. 2 is a perspective view of an Si wafer at the time of ion implantation created by an ion implantation method according to a second embodiment of the present invention.

FIG. 3 is a diagram illustrating a configuration of an ion implantation apparatus according to a third embodiment of the present invention.

FIG. 4 is a diagram showing a case where a plurality of Si wafers 3 arranged on the circumference of a rotating disk 6 of the ion implantation apparatus shown in FIG.

FIG. 5 shows that a plurality of Si wafers 3 arranged on the circumference of a rotating disk 6 according to a fifth embodiment of the present invention are arranged at a symmetrical position with respect to the ion beam 1 while being inclined with respect to the ion beam 1; FIG. 7 is a diagram when the wafer 3 is rotated.

FIG. 6 shows a SOI (Silicon on Ins) manufactured by an ion implantation method according to the related art.
FIG. 4 is a diagram showing a cross section of an ulrator wafer.

[Explanation of symbols]

1 ion beam 2 particles 3 Si wafer 4 SiO which is formed by ion implantation into both the SiO ₂ layer 5 pinhole 6 rotating disk 9 1,2 times
_Two layers 10 second SiO ₂ which is formed by ion implantation layer 11 once the SiO ₂ layer which is formed by ion implantation on day 20 the ion source 21 mass separator 22 post acceleration tube 23 quadrupole lens 24 bending magnets 25 Power supply for post-stage acceleration 26 Controller 27 Angle sensor 28 Angle adjuster

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/265 603D

Claims (9)

[Claims] 1. An ion implantation method for implanting an ion beam into a wafer, comprising: implanting ions by tilting a wafer surface with respect to the ion beam; and tilting the wafer surface with respect to the ion beam. And implanting ions at an angle different from the above, wherein the total implantation amount of ions implanted in each of the steps is a predetermined implantation amount. 2. An ion implantation method for implanting an ion beam into a wafer, comprising: implanting ions while tilting a wafer surface with respect to the ion beam; and tilting the wafer surface with respect to the ion beam. Implanting ions at an angle different from the above, repeating each of the steps by changing the angle of each of the inclinations in each of the steps, and setting a total implantation amount of ions to be implanted in each of the steps at a predetermined value. An ion implantation method characterized by using an implantation amount. 3. An ion implantation method for implanting an ion beam into a wafer, wherein the step of injecting ions by tilting the wafer surface with respect to the ion beam, and the step of tilting the wafer surface with respect to the ion beam opposite to the tilt A step of implanting ions in a direction and inclined at substantially the same angle as the angle of inclination, and repeating each of the steps by changing the angle of each inclination in each of the steps; An ion implantation method, wherein a total implantation amount is a predetermined implantation amount. 4. An ion implantation method for implanting an ion beam into a wafer, the method comprising: implanting ions while tilting a wafer surface with respect to the ion beam; and rotating the wafer around a rotation axis perpendicular to the wafer surface. An ion implantation method characterized in that the above-mentioned steps are repeated by changing the rotation angle considerably from the step of rotating by an arbitrary rotation angle, and the total implantation amount of ions implanted in each step is made a predetermined implantation amount. . 5. An ion implantation method for implanting an ion beam into a wafer, wherein the wafer surface is inclined with respect to the ion beam while continuously rotating the wafer around a rotation axis perpendicular to the wafer surface. An ion implantation method comprising the step of implanting ions, wherein a total implantation amount of ions implanted in the step is a predetermined implantation amount. 6. An ion implantation method for implanting an ion beam into a wafer, wherein the irradiation angle of the ion beam is continuously varied on the wafer surface, and the ion beam is vertically irradiated from the wafer surface at each irradiation angle. A step of implanting ions by changing implantation energy so that implantation depths in the directions are substantially the same, wherein a total implantation amount of ions implanted in the step is a predetermined implantation amount. Injection method. 7. One of claims 1 to 6
The ion implantation method according to claim 1, wherein the ion beam is oxygen ions, and the energy of the ion beam is in a range of 30 to 250 keV. 8. The method according to claim 1, wherein
In one embodiment, the total amount of the implanted ions is 1 × 10 ¹⁸ /
cm ² or less. 9. An ion implantation apparatus for implanting an ion beam into a wafer, comprising: a rotating disk provided rotatably and having a wafer disposed near a circumference thereof; and ion beam irradiation means for irradiating the wafer with the ion beam. And a wafer tilt angle changing means for tilting a wafer surface at an arbitrary angle with respect to the ion beam.