JPH0492349A - Ion implanting device - Google Patents

Abstract

PURPOSE:To carry out an even ion implanting in a simple and compact device by rotating a set magnet including plural magnetic ploes making the N and S poles opposite placing a substance to be implanted between the N and S poles around the substance to be implanted, and generating a magnetic field which has a specific inclination of intensity in a necessary direction. CONSTITUTION:A magnetic field generating means 2 furnishes a set magnet 4 made by combining three electromagnets 5, 5, 5 with magnetic poles 5a, 5b, and 5c whose N and S poles are opposed placing a semiconductor wafer 3 between them. The set magnet 4 is positioned to hold the whole body of the conductor wafer 3 from both sides, and provided close to the beam axial direction so as to generate a magnetic field close to the upper side of the wafer 3. The set magnet 4 is rotated around the semiconductor wafer 3 in the direction of the arrow by a rotation driving device, a magnetic field of a specific intensity inclination is generated in the direction square to the lines of magnetic force on the surface crossing square to the ion beams B, and the ion beams B are deflected by the magnetic field. Consequently, an even ion implanting is carried out in a simple and compact device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ion implantation apparatus that implants ions into an implanted object by curving the trajectory of an ion beam using a magnetic field.

[Conventional technology]

When implanting ions into an implanted object with an ion beam, if the ions are implanted perpendicularly to the implantation surface of the implanted object, a so-called channeling phenomenon occurs in which the ions are implanted deeper than the desired implantation depth. In order to prevent this channeling, it is useful to slightly tilt the implantation angle of the ion beam (about 7 degrees) with respect to the implantation surface of the implanted object. For this reason, in conventional ion implantation equipment, for example, a stage on which a semiconductor wafer, which is an object to be implanted, is placed is made to perform a grinding motion, thereby tilting the semiconductor wafer somewhat with respect to the ion beam, and removing shadows such as the gate electrode pattern. This is to prevent the formation of a region where ions are not implanted, that is, an offset region.

Furthermore, although the purpose is different, an ion implantation apparatus described in Japanese Patent Application Laid-open No. 61-233956 is known as one that similarly performs ion implantation into a semiconductor wafer at a fixed implantation angle. . This device implants ions into the inner wall of the groove in a semiconductor wafer by curving the trajectory of the ion beam using magnetic field generating means without tilting the semiconductor wafer itself. At the same time, the object to be implanted is horizontally rotated by a rotational drive device, so that ions can be uniformly implanted into the inner wall of the groove.

[Problem to be solved by the invention]

As described above, in the former conventional technique, since the semiconductor wafer is subjected to a grinding motion, the stage driving device has a complicated structure, making the entire device expensive.

On the other hand, in order to maintain a desired injection angle and to simplify the stage driving device, it is also possible to apply the latter conventional technique. However, with this technology, when implanting ions into large-diameter semiconductor wafers, which have been on the rise in recent years, it is difficult to obtain the desired implantation angle at the wafer periphery where the ion beam swing angle is large, making uniform ion implantation impossible. Problems are expected. However, if a sufficient distance is placed between the scanning means that emits this ion beam and the semiconductor wafer, the scanning angle will become smaller and this problem will be solved, but this will lead to the problem of increasing the size of the device. becomes.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an ion implantation device that enables uniform ion implantation with a simple and compact device.

[Means to solve the problem]

In order to achieve the above object, in the invention of claim 1, the ion source is arranged close to the object to be implanted, and the trajectory of the ion beam from the ion source is curved by the generated magnetic field, In an ion implantation apparatus equipped with a magnetic field generating means for implanting ions at an implantation angle somewhat tilted from perpendicular, the magnetic field generating means is a set of magnets including a plurality of magnetic poles with north and south poles facing each other with the object to be implanted sandwiched therebetween. and a rotational drive device that rotates the assembled magnet around the implanted object, the assembled magnet is configured to generate a magnetic field having a constant intensity gradient in the orthogonal direction on a plane intersecting the ion beam. In the invention of claim 2, the ion source is disposed close to the object to be implanted, and the trajectory of the ion beam from the ion source is curved by the generated magnetic field. In an ion implantation apparatus equipped with a magnetic field generating means for implanting ions at an implantation angle slightly tilted from perpendicular to the plane, the magnetic field generating means has a plurality of magnetic poles each sandwiching the implanted object and having N-8 poles facing each other. 3 or more assembled magnets are arranged uniformly in the circumferential direction so as to surround the implanted object, and each assembled magnet is energized to generate a constant beam in the orthogonal direction on a plane intersecting the ion beam. It is characterized by having a magnetic field rotation device that generates a magnetic field having an intensity gradient of In the invention of claim 3, the ion source is disposed close to the object to be implanted, and the trajectory of the ion beam from the ion source is curved by the generated magnetic field, so as to be slightly different from perpendicular to the implantation surface of the object to be implanted. In an ion implantation apparatus equipped with a magnetic field generation means for implanting ions at an implantation angle, the magnetic field generation means includes a plurality of magnetic poles each sandwiching the implanted object and having north and south poles facing each other, and the magnetic field generation means has a plurality of magnetic poles each sandwiching the implanted object and having north and south poles facing each other, and the magnetic field generation means has a plurality of magnetic poles that are disposed in the beam axis direction. It has two sets of assembled magnets arranged in a cross shape, and a rotational drive device that rotates both sets of magnets around the object to be implanted. It is characterized by being configured to generate a magnetic field having a constant intensity gradient in a direction perpendicular to the lines of magnetic force.

[Effect]

By constructing the ion beam as in claim 1, the ion beam is bent by the Lorentz force by the magnetic field, and the bending angle is proportional to the strength of the magnetic field. That is, when the strength of the magnetic field is large, the bending angle becomes large, and when the strength of the magnetic field is small, the bending angle becomes small. Therefore, when an ion beam passes through a magnetic field having a constant intensity gradient in the orthogonal direction, the bending angle becomes large at one end of the orthogonal direction, and conversely, the bending angle becomes small at the other end. If we capture this in terms of the angle with the injection surface of the implanted object, that is, the injection angle, at one end the injection angle is "bending angle - beam swing angle", and at the other end, "bending angle + beam swing angle" is the injection angle. "angle" is the injection angle. Further, in the middle thereof, that is, at a beam swing angle of 0 degrees (in the beam axis direction), the injection angle is "bending angle ±0".

Therefore, if the intensity gradient of the magnetic field is appropriately selected in accordance with the swing angle of the beam, the injection angle in the direction perpendicular to the magnetic field will be approximately the same angle.

If the assembled magnet is rotated in this state, ions are implanted into the entire region of the object to be implanted at a desired implantation angle.

If configured as in claim 2, the magnetic field can be continuously rotated while maintaining the magnetic field state that bends the ion beam to an appropriate injection angle by the magnetic field rotating device without mechanically rotating the magnetic field generating means itself. .

If configured as in claim 3, the ion beam can be
A magnetic field can be configured to bend the direction to an appropriate implantation angle, and the ion beam is implanted over the entire implantation surface of the implanted object at the desired implantation angle.

〔Example〕

Hereinafter, the invention of claim] is based on the embodiment shown in FIG. 1, the invention of claim 2 is based on the embodiment shown in FIG. 2, and the invention of claim 3 is based on the embodiment shown in FIG. 3. Each will be explained based on the following.

FIG. 1(a) is a side view for explaining the ion implantation apparatus of the first embodiment, and FIG. 1(b) is a plan view thereof. As shown in FIG. 1, this ion implantation apparatus includes a scanning means 1 (FIG. 1(a)) that scans an ion beam B from an ion source (not shown), and a magnetic field generating means 2 (FIG. 1(a)) that generates a magnetic field. (b)) in the same figure. The scanning means 1 swings the ion beam B and scans the semiconductor wafer 3, which is the object to be implanted, at an angle α in combination in the main scanning direction and the sub-scanning direction, and scans the (100) of the semiconductor wafer 3 at an angle α. surface(
The ion beam B can be implanted into the entire area (ion implantation surface). On the other hand, the semiconductor wafer 3 is mounted and fixed on a stage (not shown), and the (100) plane, which is the ion implantation surface, is perpendicular to the beam axis Ba, and the center of the semiconductor wafer 3 and the beam axis Ba are aligned. are placed so that they match. In this case, the implantation angle of the ion beam B is vertical at the center of the semiconductor wafer 3, and tilted at an angle of ±α/2 from the vertical at both ends, but in order to prevent so-called channeling, the implantation angle is approximately 7 degrees. It is useful to implant the ion beam B at the same time. For this reason, in this embodiment, a magnetic field is generated by the magnetic field generating means 2 in the oscillation range of the ion beam B, and its trajectory is curved to obtain a desired implantation angle.

The magnetic field generating means 2 includes a magnet assembly 4 in which three electromagnets 5, 5.5 are connected, each having magnetic poles 5a, 5b, and 5c with north and south poles facing each other with the semiconductor wafer 3 in between. set magnet 4
are positioned so as to sandwich the entire semiconductor wafer 3 from both sides, and are also disposed close to above in the beam axis direction so as to generate a magnetic field. In addition, the assembled magnet 4
is rotated three times around the semiconductor wafer in the direction of the arrow by a rotation drive device (not shown), so that the ion beam B is rotated 360 degrees while maintaining a desired implantation angle.

In this embodiment, the electromagnet 5 is arranged in a direction perpendicular to the scanning direction, and generates a magnetic field in the direction perpendicular to the scanning direction. The electromagnets 5 are connected so that the amount of current applied is adjusted so that the magnetic forces are arranged in the order of "strong, medium, and weak," and generate a magnetic field having a constant intensity gradient in the orthogonal direction. In other words, the magnetic field is strong at one end of the swing range during scanning, normal strength in the middle, and weak at the other end, creating a continuous or stepwise magnetic field strength gradient. . This means that the magnetic flux density is high in the magnetic field part of the electromagnet 5 with the "strong" magnetic pole 5a, the magnetic flux density is normal in the magnetic field part of the electromagnet 5 with the "medium magnetic pole 5b", and the "weak" magnetic field part has a high magnetic flux density. Electromagnet 5C with magnetic pole 5C
This means that the magnetic field part has a low density of magnetic flux, and the so-called Lorentz force that the ion beam B receives from the magnetic field corresponds to the "strong", "medium", and "weak" magnetic field parts. "Strong", "Medium", and "Weak". For this reason,
The trajectory of the ion beam B is largely curved in the "strong" magnetic field portion, slightly curved in the "weak" magnetic field portion, and curved to an intermediate degree between the two in the "medium" magnetic field portion.

Here, the implantation angle of ion beam B, which takes into account the beam swing angle during scanning, is θ1 (“strong”), θ
(“medium”), θ3 (“weak”), θ1
is the curved angle minus half the swing angle, that is, the curved angle (large) - α/2 [degrees], θ2 is the curved angle ±0 [degrees], and θ3 is the curved angle (small) + α/2
It becomes [degrees]. Therefore, if the intensity gradient of the magnetic field created by the electromagnets 5a, 5b, and 5c is appropriately selected in accordance with the swing angle of the ion beam B, the injection angle: θ
1-θ2-θ3. That is, the injection angles at any one point in the direction perpendicular to the magnetic field are all the same angle.

Next, in order to explain the above relationship more specifically, an example of calculating the required magnetic field strength will be shown below.

E2 acceleration voltage, m: mass of ion, v: speed of ion, then 1/2mv2-qE1/2,°, v-(2qE/m).

Here, B is the strength of the magnetic field, and the Lorentz force is calculated as follows: Fmqv B The lateral acceleration caused by this: A -q / m
・v *B, the resulting lateral velocity V', and the length of the magnetic field that the ion crosses (thickness of the magnet) as p, v - atwa, Q/v Therefore, v'/v-aρ /v2-q/mI+]/v·BI3 Therefore, B-v'/v (2qE/m) 1/2-'.

The ion species is boron, the acceleration voltage is 5×10' E
V), in order to tilt (implantation angle) approximately 7° at the center of the semiconductor wafer, v'/v = jan -'7°-0.12Here, assuming F-10cm, B-0,12X [f2X (1,6X10-27XI
O)X5X10')/ (1,6X10)
X (0,1) ”-1-1,0-1 (Tesla] -103C Gauss).

From this, when implanting ions into an 8-inch wafer in an apparatus where the distance between the scanning means and the implantation surface of the semiconductor wafer is 1.5 m, the magnetic field intensity gradient should be set at 5 to 7 x 10'C.
Gauss/cm) is appropriate. In this case, the strength of the magnetic field at the center of the wafer is 103 Gauss.

As described above, according to this embodiment, if the intensity gradient of the magnetic field is appropriately selected in accordance with the swing angle during scanning of the ion beam B, a desired implantation angle can be obtained in the direction perpendicular to the magnetic field. Even when ion implantation is performed into a semiconductor wafer 3 having a large diameter, this can be handled without increasing the distance between the scanning means 1 and the semiconductor wafer 3. Moreover, since the assembled magnet 4 is rotated in this state, ions can be uniformly implanted over the entire implantation surface of the semiconductor wafer 3 while maintaining an appropriate implantation angle in the direction perpendicular to the magnetic field.

Note that although the electromagnet 5 is used in this embodiment, it goes without saying that a permanent magnet may also be used.

Moreover, although the assembled magnet 4 is constructed by connecting three electromagnets 5a, 5b, and 5c, the number of electromagnets 5 is not limited to three, but may be any number as long as it is plural.

Next, an ion implantation apparatus according to a second embodiment of the present invention will be described with reference to FIG. FIG. 2(a) is a plan view for explaining the second embodiment, and FIG. 2(b) is a side view thereof.

This ion implanter has a scanning means (not shown) similar to that of the first embodiment, but the magnetic field generating means 2 is constructed using three sets of assembled magnets 4 used in the first embodiment. There is. That is, each set of magnets 4 is arranged in a hexagonal manner on the same plane in the circumferential direction of the semiconductor wafer 3 so as to surround the semiconductor wafer /X3. Then, using a magnetic field rotation device (not shown), three sets of assembled magnets 4, 4 are
Let the current flow with the phase shifted sequentially with respect to ゜4,
In a magnetic field state with a constant intensity gradient in the orthogonal direction,
The magnetic field is rotated around the semiconductor wafer 3 around the beam axis Ba.

Therefore, as in the first embodiment, the ion beam B is continuously rotated 360 degrees while maintaining the desired implantation angle in the direction orthogonal to the magnetic field. For this reason, the semiconductor wafer 3
Ion implantation can be performed uniformly over the entire implantation surface.

Next, an ion implantation apparatus according to a third embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 3, this ion implanter has the same scanning means 1 as in the first embodiment, or the magnetic field generating means 2 is constructed by using two sets of assembled magnets 4 used in the first embodiment. It looks like this.

These two sets of assembled magnets 4.4 are disposed in a cross shape with their positions shifted vertically in the beam axis direction so as to surround the semiconductor wafer 3 from all sides. Of course, each set of magnets 4 is designed to generate a magnetic field having a constant intensity gradient in the orthogonal direction.

Therefore, the injection state of the first embodiment shown in FIG. , an appropriate injection angle in the XY force direction can be obtained. Here, to explain this state in an easy-to-understand manner based on Fig. 4,
FIG. 4(a) shows the case without the magnetic field generating means 2, and the implantation angle of the ion beam B gradually increases toward the outside in the radial direction around the beam axis Ba. FIG. 4(b) shows the case of so-called Examples 1 and 2 in which the magnetic field generating means 2 acts in the X direction, and the ion beam B
Is the injection angle constant only in the X direction?
There is no improvement in the Y direction as in the case of FIG.

FIG. 4(c) shows the case of this embodiment. In this case, the magnetic field generating means 2 acts in the XY direction, and the ion beam B has a constant implantation angle in both the X7 directions. Also, both sets of magnets 4
4 is adapted to be rotated by a rotation drive device (not shown) as in the first embodiment.

Therefore, extremely uniform ion implantation can be performed over the entire implantation surface of the semiconductor weno\3.

〔Effect of the invention〕

As described above, according to the invention of claim 1, the assembled magnet generates a magnetic field having a constant intensity gradient in the orthogonal direction and is rotated, so that the intensity gradient is appropriately selected according to the swing angle of the ion beam. In this way, an appropriate implantation angle can be obtained in the direction perpendicular to the magnetic field of the implanted object, and a simple and compact device can be constructed regardless of the swing angle, and it has the effect of enabling uniform ion implantation.

Further, according to the invention of claim 2, since the magnetic field having a constant intensity gradient in the orthogonal direction is rotated, there is an effect that ion implantation can be performed uniformly as in the invention of claim 1.

Furthermore, according to the invention of claim 3, a magnetic field having a constant intensity gradient is obtained not only in the direction orthogonal to the magnetic field of each set of magnets but also in the magnetic field direction. An angle of implantation can be obtained, and the rotation has the effect of enabling more uniform ion implantation.

1... Scanning means, 2... Magnetic field generation means, 321. Semiconductor wafer, 4... Set of magnets, 5... Electromagnet, 5a,
5b, 5c...Magnetic pole, B...Ion beam.

Claims (3)

[Claims] 1. Arranged close to the object to be implanted, the trajectory of the ion beam from the ion source is curved by the generated magnetic field, and ions are implanted at an implantation angle that is somewhat tilted from perpendicular to the implantation surface of the object to be implanted. In an ion implantation apparatus including a magnetic field generating means, the magnetic field generating means includes a magnet assembly including a plurality of magnetic poles with N and S poles facing each other with the implanted object in between, and the assembled magnet,
a rotational drive device that rotates around the implanted object, and the assembled magnet is configured to generate a magnetic field having a constant intensity gradient in a direction perpendicular to the lines of magnetic force on a plane intersecting the ion beam. An ion implantation device characterized by: 2. Arranged close to the object to be implanted, the trajectory of the ion beam from the ion source is curved by the generated magnetic field, and ions are implanted at an implantation angle that is somewhat tilted from perpendicular to the implantation surface of the object to be implanted. In an ion implantation apparatus equipped with a magnetic field generating means, the magnetic field generating means includes a plurality of magnetic poles each having north and south poles facing each other with the implanted object in between, and extends in a circumferential direction so as to surround the implanted object. three or more assembled electromagnets uniformly arranged in the ion beam, and energizing each of the assembled electromagnets to generate a magnetic field having a constant intensity gradient in a direction perpendicular to the magnetic field lines on a plane intersecting the ion beam. An ion implantation apparatus comprising: a magnetic field rotation device that sequentially distributes power to the three or more sets of electromagnets in this magnetic field state to continuously rotate the magnetic field around the implanted object. 3. Arranged close to the object to be implanted, the trajectory of the ion beam from the ion source is curved by the generated magnetic field, and ions are implanted at an implantation angle that is somewhat tilted from perpendicular to the implantation surface of the object to be implanted. In an ion implantation apparatus equipped with a magnetic field generating means, the magnetic field generating means includes a plurality of magnetic poles, each of which has north and south poles facing each other with the implanted object in between, arranged in a cross shape with a positional shift in the beam axis direction. and a rotation drive device that rotates both sets of magnets around the implanted object, and each of the set magnets is arranged on a plane intersecting the ion beam.
An ion implantation device characterized by being configured to generate a magnetic field having a constant intensity gradient in a direction perpendicular to magnetic lines of force.