JPH11288682A - Doping device and doping processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To require only lengthwise directional uniformity for plasma, and process a substrate having the large area by forming a cross section of an ion flow in a linear or rectangular shape, and vertically moving a doping object material in the lengthwise direction of the ion flow at the time of doping. SOLUTION: An ion source accelerator 13 of an ion doping device generates an ion flow having a cross section of a linear or rectangular shape. A substrate holder 17 has a mechanism of moving while doping is performed. The length of the shorter one side of the substrate is equal to or smaller than the lengthwise directional length of a plasma space 4, and there is no restriction factor on the size of the other one side except for the size of a doping chamber. That is, a shape of the ion source accelerator 13 (L1 ×L2 ) is not restricted by a shape of the doping chamber 15 and a doping object material 17. Since a cross-sectional shape of the ion flow is a liner or rectangular shape, (L1 <L2 ) is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a doping apparatus and a doping method used for manufacturing a semiconductor integrated circuit or the like. In particular, the present invention relates to an ion doping apparatus and a doping method having a preferable configuration for processing a large-area substrate. For example, an impurity is imparted to a semiconductor material which is partially or entirely composed of an amorphous component or is irradiated with an ion beam on a substantially intrinsic polycrystalline semiconductor material. is there.

[0002]

2. Description of the Related Art In the manufacture of semiconductor integrated circuits and the like, when an N-type or P-type impurity region is formed in a semiconductor, an impurity (N-type impurity / P-type impurity) exhibiting N-type or P-type conductivity is used. A method of irradiating and implanting ions by accelerating ions at a high voltage is known. In particular, a method of separating the mass and charge ratio of ions is called an ion implantation method, and is widely used when manufacturing a semiconductor integrated circuit.

Another known method is to generate plasma having N / P type impurities, accelerate ions in the plasma by a high voltage, and implant the ions into a semiconductor as an ion stream. This method is called an ion doping method or a plasma doping method.

The structure of a doping apparatus using an ion doping method is simpler than that of a doping apparatus using an ion implantation method. For example, when boron is implanted as a P-type impurity, plasma is generated by RF discharge or another method in a gas such as diborane (B ₂ H ₆ ), which is a boron compound, and a high voltage is applied to the plasma. Ions containing boron are extracted and irradiated into the semiconductor. Since a gas-phase discharge is performed to generate plasma, the degree of vacuum in the doping apparatus is relatively high.

At present, an ion doping apparatus is often used to uniformly add impurities to a substrate having a relatively large area. This is because the ion doping apparatus does not perform mass separation, and a large-area ion beam can be obtained relatively easily. On the other hand, since the ion implantation apparatus needs to perform mass separation, it is difficult to increase the beam area while maintaining the uniformity of the beam. Therefore, the ion implantation apparatus is not suitable for a large-area substrate.

In recent years, research has been actively conducted on lowering the temperature of semiconductor device processes. The major reason is that a semiconductor element needs to be formed on an insulated substrate such as inexpensive glass. In addition, there is a demand accompanying miniaturization of elements and multilayering of elements.

An insulating substrate made of glass or the like has various merits, such as being more workable than a quartz substrate conventionally used in a high-temperature process, being easy to increase in area, and being inexpensive. However, with the increase in the area of the substrate, it is a fact that many difficulties have to be overcome technically, such as the need to develop an apparatus having different properties from the conventional high-temperature process.

In the production of an active matrix type liquid crystal display or the like that needs to process a large area substrate,
The ion implantation method is disadvantageous in this respect, and research and development on the ion doping method are being conducted for the purpose of compensating for the disadvantages.

[0009]

FIG. 1 and FIG. 2 show an outline of a conventional ion doping apparatus. FIG. 1 mainly shows an outline of an ion source and an ion accelerator. Also,
FIG. 2 shows the structure of the entire ion doping apparatus. First,
This will be described with reference to FIG. Ions are generated in the plasma space 4.

That is, high-frequency power is applied between the electrode 3 and the mesh electrode 6 by the high-frequency power supply 1 and the matching box 2 to generate plasma in the decompressed plasma space 4. At the initial stage of plasma generation, hydrogen or the like is introduced into the atmosphere, and after the plasma is stabilized, doping gas such as diborane or phosphine (PH ₃ ) is introduced.

The electrode 3 and the outer wall of the chamber (the same potential as the mesh electrode 6) are insulated by an insulator 5. The ion flow is extracted from the plasma generated in this way, and for this, the extraction electrode 10 and the extraction power supply 8 are used. After the ion current thus extracted is shaped by the suppression electrode 11 and the suppression power supply 9,
The required energy is accelerated by the acceleration electrode 12 and the acceleration power supply 7.

Next, FIG. 2A will be described. Ion doping equipment can be broadly divided into ion source / accelerator 1
3, doping chamber 15, power supply 14, gas box 1
9, the exhaust device 20. In FIG. 2, the ion source / accelerator shown in FIG. 1 is set aside. That is, FIG.
Then, the ion current flows from left to right (from top to bottom in FIG. 1). The power supply device 14 mainly integrates power supplies used for generating and accelerating ions, and includes the high-frequency power supply 1, the matching box 2, the acceleration power supply 7, the extraction power supply 8, and the suppression power supply 9 in FIG.

A substrate holder 17 is provided in the doping chamber 15, and a material 16 to be doped is placed thereon.
The substrate holder is generally designed to be able to rotate along an axis parallel to the ion flow. The ion source / accelerator 13 and the doping chamber 15 are exhausted by the exhaust device 20. Of course, the ion source / accelerator 13 and the doping chamber 15 may be evacuated by independent exhaust devices.

A doping gas is sent from the gas box 19 to the doping chamber 15 via the gas line 18. Although the gas supply port is provided between the ion source / accelerator 13 and the material 16 to be doped in the apparatus shown in FIG. 2, it may be provided near the plasma space 4 of the ion source. The doping gas is generally used after being diluted with hydrogen or the like.

In the conventional ion doping apparatus, the area of the substrate (material to be doped) that can be processed is equal to or smaller than the cross-sectional area of the plasma space 4 in the ion source 13. This is a condition required by doping uniformity. FIG. 2B illustrates a cross section perpendicular to the ion flow. That is, the size of the ion source / accelerator 13 is L ₁ and L ₂ , but the doping chamber 15 and the material to be doped 17 are small enough to fit therein. Then, L ₁ and L ₂ are of the same order of magnitude.

Therefore, as the size of the substrate increases, the size of the plasma space 4 must be further increased. Moreover, the plasma is required to be two-dimensionally uniform. However, it is difficult to make the plasma space infinitely large. This is because the generation of plasma is not uniform. This is mainly because the mean free path of molecules is sufficiently smaller than the cross section of the plasma space. Therefore, the length of one side of the plasma space is set to 0.
It is difficult to make it 6 m or more.

[0017]

According to the present invention, the cross section of the ion flow is made linear or rectangular, and the material to be doped is perpendicular to the longitudinal direction of the ion flow (ie, in the short direction) during doping. It is characterized by being moved. In this way, the plasma only needs to be uniform in the longitudinal direction, and a large-area substrate can be processed. Only the uniformity in the long direction of the plasma becomes a problem,
The reason why the two-dimensional uniformity does not matter is that, when focusing on an arbitrary portion of the material to be doped, ion irradiation is performed by scanning.

In the present invention, in principle, the length of one side of the substrate is limited by the length of the plasma, but the length of the other side has no limiting factor other than the size of the doping chamber. If the width of the discharge space is sufficiently small, plasma having uniformity in the longitudinal direction of about 2 m can be easily generated. Of course, the width of the ion beam at that time may be on the order of centimeters.

Therefore, such a linear ion doping apparatus is suitable for processing a large area substrate or a large number of substrates simultaneously. For example, doping can be performed relatively easily on a substrate having a maximum size of 2 m × xm. x is determined by the size of the doping device.

[0020]

FIG. 3A shows the concept of an embodiment of the present invention. The ion doping apparatus of the present invention also includes an ion source / accelerator 13, a doping chamber 15, a power supply 14, a gas box 19, and an exhaust device 20, as in the prior art.
However, unlike the conventional one, the ion source / accelerator 13 generates an ion current having a linear or rectangular cross section. Further, a mechanism is provided so that the substrate holder 17 moves during doping. The long direction of the ion flow is a direction perpendicular to the plane of the drawing.

In the ion doping apparatus of the present invention, the shape of the substrate (material to be doped) that can be processed is not related to the shape of the cross section of the plasma space 4 in the ion source 13. However, the length of one shorter side of the substrate is required to be equal to or less than the length of the plasma space 4 in the longitudinal direction. The size of the other side of the substrate has no limiting factor other than the size of the doping chamber.

FIG. 3B shows a cross section perpendicular to the ion flow. That is, the ion source / accelerator 13 (L ₁ ×
The shape of L ₂ ) is not limited by the shapes of the doping chamber 15 and the material 17 to be doped. Since the cross-sectional shape of the ion flow is linear or rectangular, L ₁ <L ₂ (= the length of the cross-section of the ion flow in the longitudinal direction).

Only when the ion flow is uniform in the longitudinal direction,
The fact that the uniformity in the short direction is not required means that there is no problem even if the ion intensity and the ion species distribution are present in the short direction, which means that specific light ions (for example, H ⁺ , H ₂ ⁺ ). Separation of the ions required a magnetic effect on the ion flow, which necessarily affected the required heavy ion distribution.

In the conventional ion doping apparatus, since two-dimensional uniformity is required, it is impossible to substantially separate ions. However, in the present invention, separation can be easily performed as shown in the second embodiment.

The fact that the ion flow is only uniform in the longitudinal direction and that the uniformity in the short direction is not required is advantageous for the structure of the electrode for accelerating and decelerating the ion flow. In a conventional ion doping apparatus, a mesh or porous electrode was used as an electrode.However, in such an electrode, some ions collide with the electrode body. Scattering / sputtering becomes a problem.

On the other hand, in the present invention, as shown in the first embodiment, since the electrodes are provided in a simple shape and at a position away from the ion flow, the above problem is solved.

In the conventional semiconductor manufacturing technology, an ion implantation technology is known. In this case, a technology is known in which an ion current is electromagnetically deflected to scan a fixed substrate. However, such a method is not appropriate when simultaneously doping ions having various mass / charge ratios as in the present invention, and it is better to fix the ion flow and move the substrate as in the present invention. preferable.

This is because, in the ion beam deflection technique, light ions are much more likely to be deflected than heavy ions, and therefore cannot be scanned uniformly. Even a slight difference in the mass number results in a distribution, so that it is not preferable to apply the present invention to the ion doping technique aimed at. Such an electromagnetic deflection technique can be used only when doping only a single ion species.

The ion doping apparatus of the present invention may be provided with an ion focusing apparatus or an ion mass separation apparatus known in the conventional ion technology.

Further, in the linear ion doping technique as in the present invention, the feature that mass separation of ions is easy may be advantageous in a subsequent annealing treatment. In general, when ion doping is performed, damage of an atomic lattice of an object to be irradiated and amorphization of a crystal lattice are caused due to incidence of ions on the object to be irradiated. Also, the dopant does not act as a carrier merely by being implanted into the semiconductor material. Several steps are needed after doping to eliminate these disadvantages.

In the above steps, the most common method is thermal annealing or optical annealing. These anneals can couple the dopant to the semiconductor material lattice. However, in the case of light annealing, the light must reach the above-mentioned lattice damage portion.

In addition, a process of adding hydrogen for eliminating a level (a dangling bond) that cannot be eliminated by the annealing is quite generally performed. This step is hereinafter referred to as hydrogenation.
Hydrogen easily enters the semiconductor material at a temperature of about 350 ° C. and functions to eliminate the above level.

In any case, providing these post-doping steps increases the number of steps and is not favorable in terms of cost and throughput. Omit the annealing and hydrogenation steps, shorten the processing time, or reduce the processing temperature by performing thermal annealing and hydrogenation at the same time as doping, or by performing part of those steps during doping. Etc. can be achieved.

It is relatively easy to simultaneously add hydrogen and a dopant to a semiconductor material. That is, doping may be performed by ionizing the hydrogen-diluted dopant together with the hydrogen. For example, if ions are implanted with phosphine (PH ₃ ) diluted with hydrogen using the doping apparatus shown in FIGS. 1 and 2, phosphorus-containing ions (for example,
Hydrogen ions (eg, PH ₃ ⁺ and PH ₂ ⁺ )
H ₂ ⁺ and H ⁺ ) are also implanted.

However, hydrogen is too light for ions containing dopants such as phosphorus and boron and is easily accelerated, so that it enters deep into the substrate. On the other hand, ions containing a dopant remain in a relatively shallow portion, so that the hydrogen must be moved by thermal annealing or the like in order for the hydrogen to repair a defect caused by the dopant.

By the way, if a linear ion beam is used,
As described above, it becomes possible to irradiate the substrate only with desired ions in the middle of the ion flow with the mass separator. If this idea is further developed, the following new doping method will be possible. That is, a doping method in which ions having different masses are separated, then accelerated at different voltages, and these beams are irradiated to a semiconductor material so that these ions are implanted at substantially the same depth.

For example, by separating into ions mainly containing hydrogen (light ions) and ions containing dopants (heavy ions) and accelerating only the latter, the penetration depth of the former and the latter is made substantially the same. This makes it possible to simultaneously perform a part or all of the annealing step and the hydrogenation step for the dopant due to the presence of the former.

That is, by making the incident speed of the hydrogen ion beam to the semiconductor material close to the incident speed of the ion beam containing the dopant to the semiconductor material, the distribution of hydrogen and the distribution of the dopant in the semiconductor film become closer. At this time, the dopant is immediately activated by the incident energy of the ions (converted to thermal energy by collision) and the supply of hydrogen. This effect eliminates the need for a subsequent dopant activation step.

In order to adjust the penetration depth, the angle of incidence of each ion beam may be changed. That is, if the incident angle is small, the penetration depth is also small. The angle of incidence may be changed by using a magnetic or electrical effect. If the incident angle is too small, ions will not enter the substrate and will be reflected. There is no problem if the incident angle is 40 ° or more.

For the above purpose, the mass separation device is preferably provided between the ion beam generator and the accelerator. For mass separation, an apparatus that applies a magnetic field parallel to the long direction of the ion beam to the ion beam may be used. For a semiconductor material, ions containing a dopant may be implanted first, and then ions containing hydrogen as a main component may be implanted, or vice versa.

It is also effective to provide the ion doping apparatus of the present invention and a laser annealing apparatus using linear laser light in the same chamber. That is, the present invention is characterized by the step of doping while scanning the substrate with the linear ion current, and the laser annealing method using linear laser light, which is another invention, requires a similar mechanism. If attention is paid to the fact that the steps using both devices are continuous, it is very effective to incorporate them into the same device, rather than using both devices as separate devices.

For example, JP-A-7-283151 discloses that
A multi-chamber vacuum processing apparatus having an ion doping chamber and a laser annealing chamber is disclosed. Conventional ion doping equipment is based on the simultaneous irradiation of an ion stream having a planar cross section. In some cases, the substrate must be rotated, so the idea of integrating the ion doping chamber and the laser annealing chamber is considered. There was no.

However, in the case where the ion doping apparatus performs the doping while moving the substrate by the same transport mechanism as the linear laser annealing apparatus as in the present invention, it is necessary to provide an ion doping chamber and a laser annealing chamber separately. But rather,
The integration is advantageous in terms of mass productivity. That is, the longitudinal direction of the cross section of the ion flow and the longitudinal direction of the cross section of the laser beam may be arranged in parallel, and the substrate may be moved vertically between them. By doing so, the ion doping step and the laser annealing step can be performed continuously.

The combination of the linear ion annealing apparatus and the linear laser annealing apparatus has an effect of reducing the number of steps by simultaneously performing the two steps and an effect of reducing the possibility of contamination of the substrate. .

Further, by using the ion doping apparatus of the present invention, it is possible to perform a doping process having the following features. That is, the first of the doping method according to the present invention is a step of generating a linear ion beam and separating the ion beam by mass,
Separating the ion beam into two ion beams, accelerating the ion beam with different voltages, and irradiating the substrate with the ion beams at different angles.

Second Method of Doping Process According to the Present Invention
Generating a linear ion beam, mass separating the ion beam into at least two types of ion beams, and accelerating one of the ion beams at an acceleration voltage different from the other. And irradiating at least two of the ion beams while moving the substrate in a direction substantially perpendicular to the line direction of the linearly processed ion beam.

The third of the doping method according to the present invention
Is a process of generating a linear ion beam containing hydrogen,
A step of mass-separating the ion beam into a hydrogen-based ion beam and a non-hydrogen-based ion beam; Applying energy, incident angle, etc., so that the penetration depth into the ion beam becomes substantially equal, and irradiating the ion beam while moving the substrate in a direction substantially perpendicular to the line direction of the linearly processed ion beam. It is characterized by doing. Examples are shown below,
The present invention will be described in more detail.

[0048]

[Embodiment 1] FIG. 4 shows this embodiment. FIG.
4A shows a schematic configuration of the ion source / accelerator of the present embodiment, and FIG. 4B shows a schematic shape of an electrode of the ion source / accelerator of the present embodiment. First, a description will be given with reference to FIG.

The plasma space 24 having a rectangular cross section
Then, high-frequency power is applied from the high-frequency power source 21 to the plasma generating electrodes 23 and 26 to generate plasma. This plasma is extracted by the extraction electrode 30 and the extraction power supply 28, and after the shape and distribution are adjusted by the suppression electrode 31 and the suppression power supply 29, the plasma is accelerated to the required energy by the acceleration electrode 32 and the acceleration power supply 27.
If the uniformity of the plasma in the longitudinal direction is sufficient, the suppression electrode 31 may not be provided.

The shapes of the plasma generation electrodes 23 and 26, the extraction electrode 30, the suppression electrode 31, and the acceleration electrode 32 are shown in FIG.
It is shown in (B). That is, the extraction electrode 30, the suppression electrode 31, and the acceleration electrode 32 are of a hollow type, and the ion current flows through the central portion. Therefore, the ions do not collide with the electrodes.

In this embodiment, the plasma generating electrodes 23 and 2
6, the interval is 1 to 10 cm, the length is 50 to 150 cm, the cross-section of the cavity of the extraction electrode 30, the suppression electrode 31, and the acceleration electrode 32 is 1 to 15 cm in the short direction, and 50 in the long direction. It is good to be ~ 170cm.

The configuration of the entire ion doping apparatus may be the same as that shown in FIG. In this embodiment, since ions are introduced without being subjected to mass separation, for example, when phosphine diluted with hydrogen is used as a doping gas, heavy ions (PH ₃ ⁺ , P ₃
Both H ₂ ^{+ and} light ions (eg, H ⁺ , H ₂ ^+, etc.) are introduced with the same areal density. The same occurs with boron or antimony implantation.

This has the advantage that crystallization is performed at a low temperature during recrystallization. That is, the Si-H bonds in the material undergo a condensation process of releasing hydrogen molecules,
This is for forming a Si-Si bond. This is different from the second or third embodiment in which the injection of hydrogen molecules is positively prevented.

However, in this embodiment, attention must be paid to the fact that the penetration depth varies depending on the mass and radius of the ions. Generally, light hydrogen-based ions are concentrated in a much deeper part. An embodiment for improving this point will be described later. (Examples 5 to 7)

[Embodiment 2] This embodiment shows an example in which a mass separator is provided in the ion source / ion accelerator of the ion doping apparatus shown in Embodiment 1. This embodiment will be described with reference to FIG. FIG. 5A schematically shows the configuration of the ion source / accelerator of the present embodiment. First, a description will be given with reference to FIG. In the plasma space 24 having a rectangular cross section, high frequency power is applied to the plasma generating electrodes 23 and 26 from the high frequency power supply 21 to generate plasma.

This plasma is extracted by the extraction electrode 30 and the extraction power supply 28 and accelerated by the acceleration power supply 27. Next, the ion flow passes through magnetic fields 34 and 35 in opposite directions and a slit 36 therebetween.
Due to the magnetic field 34, the ions are subjected to a lateral force, so that light ions (eg, H ⁺ , H ₂ ^+, etc., dotted lines in the figure)
Are heavy ions (eg, BH ₃ ⁺ , BH ₂ ⁺ , P
H ₃ ⁺ , PH ₂ ^+, etc.
It cannot pass through the slit 36. That is, the slit 36 is provided for mass separation.

FIG. 5B shows a conceptual diagram of the distribution of ions before entering the slit. The vertical axis is the ion density (ion intensity), and the horizontal axis is the short direction of the cross section of the ion flow. The ions reflect the distribution of the plasma and have a shape close to a Gaussian distribution, but light ions move to the left by the magnetic field 34. FIG. 5C shows the distribution of ions after passing through the slit. The slit 36 cuts the light ion peak on the left side of the ion flow. As a result, mass separation of the ion flow can be performed.

Although the distribution of the ion flow passing through the slit 36 in the short direction is strongly influenced by the magnetic field 34 and is different from the distribution in the plasma space, the ion flow moves as described above. There is no problem for doping.

The ion flow passing through the slit 36 receives a rightward force by a magnetic field 35 opposite to the magnetic field 34, and the trajectory is corrected. Since the force received by the magnetic field 34 and the force received by the magnetic field 35 are opposite in direction and equal in magnitude, the ion current eventually becomes parallel to the previous flow.

Thereafter, after the shape and distribution are adjusted by the suppression electrode 31 and the suppression power supply 29, the acceleration electrode 32 and the acceleration power supply 3 are adjusted.
3 accelerates to the required energy. If the uniformity of the plasma in the longitudinal direction is sufficient, the suppression electrode 31 may not be provided. Further, the device for applying a magnetic field and the slit as in this embodiment may be placed between the suppression electrode and the acceleration electrode or between the acceleration electrode and the material to be doped.

When light hydrogen-based ions are removed as in this embodiment, the hydrogen elimination-condensation reaction in the recrystallization as described in Embodiment 1 does not easily occur. In order to solve this problem, doping with only hydrogen may be performed before or after the step of doping with the target impurity so as to have the same depth.

[Embodiment 3] This embodiment shows an example in which an ion source / ion accelerator of an ion doping apparatus having a simple mass spectrometer is provided with an ion current focusing device. This embodiment will be described with reference to FIG. FIG. 6 (A)
1 schematically shows the configuration of the ion source / accelerator of the present embodiment.
First, a description will be given with reference to FIGS. 6A and 6B. Note that FIG. 6A is a view as viewed from the longitudinal direction of the cross section of the ion flow, and FIG. 6B is a view as viewed from a plane perpendicular to the longitudinal direction of the cross section of the ion flow.

Unlike the first and second embodiments, the ion source of this embodiment employs an inductively excited plasma generation method.
For that purpose, a quartz tube is used as a part of the gas line 58, and the induction coil 43 is wound around the quartz tube. Coil 4
3 is connected to the high frequency power supply 41. Note that one end of the coil is grounded. In Examples 1 and 2, grounding was performed downstream of the ions. On the other hand, in this embodiment, grounding is performed upstream of the ion flow.

The advantage of this is that the gas line 58 can be used near the ground level, especially in the case of inductive excitation in a thin tube. When the gas line is provided in the middle flow of the ions as in the first and second embodiments, the potential of the gas line does not matter so much. Since the potential near the line is as high as 100 kV and a conductive material is used for gas pipes and gas cylinders, it is necessary to strictly insulate even gas boxes and the like.

By grounding the upstream of the ions as in the present embodiment, on the contrary, the downstream has a (negative) high potential. However, since there are few objects downstream that communicate with the outside, insulation is a major problem. Does not.

The plasma generated by the induction coil 43 is introduced into the acceleration chamber 44. Fig. 6 shows the inlet to the acceleration chamber
As shown in (B), a characteristic shape is provided. Here, the pressure and density of the plasma and the doping gas are rapidly reduced by introducing the gas from the thin tube into the large-capacity reaction chamber.

This is preferable when the ion current is focused as in this embodiment. Generally, the pressure of the gas line 58 in the induction coil portion is 1/5 to 1/1 / the pressure of the acceleration chamber 44.
What is necessary is just to make it 100. In order to generate plasma, a pressure of 10 ^-4 Torr or more is required.

However, in a high pressure space, the mean free path of gas molecules and ions is small, which is disadvantageous in accelerating ions to high energy. In the case where the ion current is focused as in this embodiment, the degree of convergence is reduced due to scattering due to the collision of ions.

As in this embodiment, the pressure in the acceleration chamber 44 is
The above problem can be solved by greatly lowering the plasma source (in the vicinity of the induction coil 43). In order to make the focusing effect of the ion flow effective, it is preferable to set the pressure so that the distance from the focusing device to the doping object is equal to or less than the mean free path.

The plasma thus introduced into the acceleration chamber is extracted by the extraction electrode 50 (and the extraction power supply 48), and is extracted by the acceleration electrode 52 (and the acceleration power supply 47).
Accelerated by A coil 51 for focusing the ion current is provided between the extraction electrode 50 and the acceleration electrode 52.
The coil 51 has a shape different from a normal solenoid.

That is, in the direction in which the ion stream is focused, the diameter decreases as it goes downstream. On the other hand, the diameter is not changed in a direction perpendicular to the direction. By doing so, the ion flow can be focused in one direction. Coil 51
Can be replaced by a hollow permanent magnet having a similar shape.

The above is a plasma confinement or plasma focusing technique called a z-pinch method in principle.
In addition, a self-focusing method in which the ion stream is focused by a magnetic field generated by the ion stream itself can be used. In this case, a multi-stage accelerating electrode may be provided, and the electrode diameter may be reduced toward the downstream. In addition, when using the self-focusing method, when an electron flow is caused to flow in the opposite direction to the ion flow, the amount of current increases, and repulsion between ions is shielded by the electrons (shield effect).
Therefore, it is effective in focusing more.

Next, the ion current is applied to the magnetic fields 5 opposite to each other.
4, 55 and the slit 56 therebetween. Due to the magnetic field 54, the ions receive a leftward force. For this reason, light ions (dotted line in the figure) are replaced with heavy ions (thin line in the figure)
It is bent further to the left and cannot pass through the slit 56. This is the same as in the second embodiment, but in this embodiment, since the ion current is focused, a more remarkable effect can be obtained.

FIG. 6C shows a conceptual diagram of the distribution of ions that have passed through the accelerating electrode 52. The vertical axis is the ion density (ion intensity), and the horizontal axis is the short direction of the cross section of the ion flow. The ions reflect the distribution of the plasma and have a shape close to a Gaussian distribution, but lighter ions are more strongly focused and heavier than the heavy ions.

When the ion current having such a distribution passes through the magnetic field 54, light ions move to the left as in the second embodiment. FIG. 6D shows a conceptual diagram of the distribution of ions before entering the slit. FIG. 6E shows the distribution of ions after passing through the slit. The slit 56 cuts a light ion peak on the left side of the ion flow.
As a result, mass separation of the ion flow can be performed. A characteristic of this embodiment is that light ions have a higher degree of integration, so that the effect of separation by the slits is remarkably exhibited.

The ion current passing through the slit 56 receives a rightward force by the magnetic field 55, and its trajectory is corrected. Since the force received by the magnetic field 54 and the force received by the magnetic field 55 are opposite in direction and equal in magnitude, the ion flow eventually becomes parallel to the previous flow. In this way, an ion stream having a linear cross section can be obtained.

Embodiment 4 The present embodiment relates to an apparatus in which the ion doping apparatus of the present invention and a laser annealing apparatus using linear laser light are provided in the same chamber. That is, the present invention is characterized by the step of doping while scanning the substrate with the linear ion current, and the laser annealing method using linear laser light, which is another invention, requires a similar mechanism. It pays attention to.

For example, Japanese Patent Laid-Open No. 7-283151 discloses a multi-chamber vacuum processing apparatus having an ion doping chamber and a laser annealing chamber. Conventional ion doping equipment is based on the simultaneous irradiation of an ion stream having a planar cross section. In some cases, the substrate must be rotated, so the idea of integrating the ion doping chamber and the laser annealing chamber is considered. There was no.

However, when the ion doping apparatus performs the doping while moving the substrate by the same transport mechanism as the linear laser annealing apparatus as in the present invention, it is necessary to provide an ion doping chamber and a laser annealing chamber separately. But rather,
The integration is advantageous in terms of mass productivity. That is, the longitudinal direction of the cross section of the ion flow and the longitudinal direction of the cross section of the laser beam may be arranged in parallel, and the substrate may be moved vertically between them. By doing so, the ion doping step and the laser annealing step can be performed continuously.

This embodiment will be described with reference to FIG. FIG.
(A) is a conceptual diagram of a cross section of the device of the present embodiment,
FIG. 7B is a conceptual diagram of the apparatus of the present embodiment as viewed from above (the direction of introduction of the ion stream or the direction of introduction of the laser beam).

The ion doping / laser annealing apparatus of the present invention comprises an ion source / accelerator 63, a doping chamber 65, a power supply unit 64, a gas box 69, and an exhaust unit 70, like the ion doping apparatus of the other embodiments.
However, in addition thereto, a laser device 61 and an optical system 62 are provided. It also has a spare room 68. Of course, the doping chamber 65 is provided with a window 73 for introducing a laser beam. The window 73 for introducing a laser beam is provided in parallel with the window 72 for introducing an ion stream.

The substrate 66 is held by a substrate holder 67,
The substrate holder 67 moves the doping chamber 65 in at least one direction by the transfer mechanism 71. Substrate holder 6
7 may be provided with a heater or the like. The long direction of the ion flow is a direction perpendicular to the plane of the drawing.

[Embodiment 5] In this embodiment, a device having an ion forming means and a device having an ion accelerating means have the same configuration as the device shown in FIG. FIG. 8 shows a conceptual diagram of an ion doping apparatus used in this embodiment. The dopant gas is ionized by the plasma generating electrodes 82 and 83 to which the high frequency power is applied from the high frequency power supply 81. These ions are extracted by the extraction electrode 84.

Further, the doping apparatus of this embodiment is provided with a means 85 for applying a magnetic field to the ion beam. As a result, light ions (ions mainly composed of hydrogen) are largely deflected. On the other hand, heavy ions (ions containing dopants)
Is slightly deflected. In the apparatus of this embodiment, a suppression electrode 86 and an acceleration electrode 87 are provided in the passage of heavy ions, and the ion beam is selectively accelerated and irradiated on the substrate. However, with respect to light ions, since the accelerating electrode is not provided in the passage, the substrate 88 on the stage (not shown) is irradiated with the energy accelerated by the extraction electrode 84.

In this embodiment, the substrate 88 is irradiated with the ion beam in a curtain shape like a waterfall. The substrate 88 should be spread over the entire substrate.
While scanning, doping is performed. The dose is controlled by the scanning speed of the substrate and the ion current value. The scanning direction at this time is substantially perpendicular to the curtain surface formed by the dopant.

The ion waterfall formed by this device is 2 m wide.
You. This device uses phosphorous or boron as a dopant and
Used to add to conductor materials. The above ions are P
H_y ⁺Or B2H_x ⁺A large amount of H besides ions_Two ⁺Io
Is included. In this embodiment, the concentration is about 5% with hydrogen.
Diluted PH for semiconductor_ThreeOr B_TwoH₆Using gas
Was.

By forming a magnetic field in a direction perpendicular to the ion stream and including the ion curtain surface, a force in a direction perpendicular to the ion stream is applied to the ion stream. this is,
This is called Lorentz force. Equation of motion M a =
From qv B, it is easy to see that the acceleration a of the ion caused by the magnetic field B is inversely proportional to the ion mass M and proportional to the charge q of the ion. Note that the ion velocity component v after the magnetic field incidence in the direction of the ion flow before the magnetic field incidence depends on the ion mass M.

In the case of this embodiment, since the majority of the ions to be accelerated have one electric charge, it can be considered that the aforementioned acceleration depends only on the mass of the ions. The ion and H ₂ ⁺ ions contained in the gas used in this embodiment have a molecular weight of 2, PH
The molecular weight of the _y ⁺ ion is about 34, and the molecular weight of the B ₂ H _x ⁺ ion is about 24 to 26. In addition, the above velocity component v
Taking into account the mass dependence of H ₂ ⁺ , it can be seen that H ₂ ⁺ ions are subjected to an acceleration 10 to 100 times that of the ions containing the dopant in the vertical direction of the ion flow. Therefore, mass separation of the ion flow can be performed by applying a magnetic field to the ion flow.

In order to appropriately change only the flow of H ₂ ⁺ ions without changing the direction of the ion flow including the dopant, the extraction voltage should be about 1 to 10 kV and the direction of the magnetic field shown in FIG. It was good to apply a magnetic field of about 0.1 to 10 Tesla, preferably about 0.5 to 2 Tesla.

The place where the magnetic field is formed is immediately after the extraction electrode. If the ions are bent while the kinetic energy of the ions is still small, the ions can be greatly bent with a small energy. The H ₂ ⁺ ions bent immediately after the extraction electrode 84 reach the substrate 88 on the stage without passing through the suppression electrode 86 and the acceleration electrode 87. In this way, the velocity of H ₂ ⁺ ions at the time of incidence on the substrate can be suppressed.

The angle of incidence of H ₂ ⁺ ions upon reaching the substrate was about 50 °. The angle was sufficient for ions to enter the substrate. On the other hand, the ion stream containing the dopant was irradiated on the substrate after passing through the suppressing electrode and the accelerating electrode almost without being affected by the magnetic field. The angle of incidence was approximately 90 °.

By the above-described ion acceleration method, it has become possible to suppress the velocity of H ₂ ⁺ ions as much as possible and to implant a dopant to a desired depth. In an isoelectric field, the lighter the ions and the higher the charge, the easier they are to accelerate. Therefore, unless the ion flow is mass-separated, ions are injected into the substrate at a higher speed as light ions. That is,
Lighter ions are implanted deeper into the substrate.

However, when the method of this embodiment is employed, in this embodiment, the velocity of H ₂ ⁺ ions corresponding to light ions at the time of incidence on the substrate and the velocity of ions including heavy ions corresponding to dopants at the time of incidence on the substrate are considered. And the speed of light ions was comparable or slower than that of heavy ions.

By controlling such a speed,
H_Two ⁺In the substrate of ions containing ions and dopants
Can be made to resemble each other in the depth direction. This result
Fruit, H_Two ⁺Heat due to release of kinetic energy of ions
Can act on the dopant more directly
It became so. The heat is applied to the ions containing the dopant.
Repair of lattice defects formed by
Used for activation. Furthermore, the heat and a large amount of hydrogen
The end of the disjointed hand was used.

Generally speaking, since damage due to doping significantly degrades the properties of a semiconductor material, some repair must be made. Conventionally, the above-mentioned damage has been recovered by annealing means such as applying heat or irradiating light. Alternatively, a means for adding hydrogen to the damaged portion for the purpose of terminating the lattice defect portion and bonding the hydrogen to the lattice defect by annealing was also effective.

By the way, as described above, when all ions are vertically incident without performing mass separation, the incident velocity Vα of heavy ions and the incident velocity Vβ of light ions become Vα <<
Because of the relationship of Vβ, relatively light hydrogen ions are distributed deep in the semiconductor film (FIG. 10B), while relatively heavy ions are distributed in a shallow portion of the film (FIG. 10B).
(A)).

That is, there is a relationship d ₁ << d ₂ between the former center depth d ₂ and the latter center depth d ₁ . Therefore, a difference occurs between the distribution of hydrogen ions and the distribution of lattice defects due to the dopant, and the hydrogen ions are not efficiently used for repairing the defects.

However, when the mass separation of ions is performed by the method described in this embodiment and the incident speeds are substantially equal, the penetration depth of the hydrogen ions (FIG. 10D) and the distribution of the dopant (FIG. 10C )) Approached or matched, and as a result, the effect of repairing the damage was significantly improved. The repair effect is a terminating effect of lattice defects of the hydrogen ions and a thermal annealing effect caused by the loss of kinetic energy between the hydrogen ions and ions containing a dopant in the film.

This effect was comparable to that of the post-doping treatment (the one described in the preceding paragraph), which has been conventionally performed. The effect increases as the concentration of hydrogen ions in the plasma increases. However, considering the throughput, the concentration of the hydrogen ions in the plasma is preferably 50 to 90%.

When the substrate is scanned while being irradiated with ions, in this embodiment, first, H ₂ ⁺ ions are implanted into the substrate, and then ions containing a dopant such as PH _y ⁺ or B ₂ H _x ⁺ ions are applied. The direction of substrate scanning was determined to be driven. H ₂ ⁺ ions are smaller and lighter than the main atoms constituting the semiconductor film, so they are implanted into the substrate without significantly breaking the lattice of the semiconductor material, and the substrate temperature rises due to the kinetic energy lost by the H ₂ ⁺ ions. I do.

Thereafter, ions containing a heavy dopant are implanted. At this time, the elevated substrate temperature and hydrogen are used for repairing lattice defects and activating the dopant. Thus, annealing and hydrogenation could be performed simultaneously with doping.

[Embodiment 6] In this embodiment, the same apparatus as in Embodiment 5 was used, and only the scanning direction of the substrate was changed.
That is, when scanning the substrate while irradiating the ions, first, ions including a dopant such as PH _y ⁺ or B ₂ H _x ⁺ ions are implanted into the substrate, and then the substrate is scanned such that H ₂ ⁺ ions are implanted. Was scanned.

The ions containing the heavy dopant are as heavy as the main atoms constituting the semiconductor film, and thus have an effect on the lattice of the semiconductor material that significantly degrades the characteristics of the semiconductor. Then H ₂ ⁺ ions are implanted into the substrate,
The substrate temperature rises due to the kinetic energy lost by the H ₂ ⁺ ions. By supplying the temperature and the supply of hydrogen at this time, lattice defects are repaired and the dopant is activated.

This embodiment has almost the same effects of repairing lattice defects and activating dopants as in the fifth embodiment. This example shows that the order of implanting hydrogen ions and ions containing dopant into the substrate does not affect the effects of the present invention.

Embodiment 7 FIG. 9 is a conceptual diagram of an ion doping apparatus used in this embodiment. A different point from the doping apparatus described in the fifth and sixth embodiments is that the doping apparatus has means for applying a further electric field to a region where a magnetic field is applied to the ion flow. The above-mentioned means is also similar to the devices of the first and second embodiments,
This allows mass separation of the ion stream. The difference is that mass separation can be performed ideally without bending the flow of ions containing the dopant at all. This mass separator is E × B
Called the separator.

The dopant gas is ionized by the plasma generating electrodes 92 and 93 to which the high frequency power is applied from the high frequency power supply 91. These ions are extracted by the extraction electrode 94.

Further, ions are mass-separated by the means 95 for applying a magnetic field to the ion beam and the electrode 96, and light ions (ions mainly composed of hydrogen) are largely deflected. On the other hand, the deflection of heavy ions (ions including dopants) is slight. In the apparatus of this embodiment, a suppression electrode 97 and an acceleration electrode 98 are provided in the passage of heavy ions, and the ion beam is selectively accelerated and irradiated on the substrate. However, with respect to light ions, since the accelerating electrode is not provided in the passage, the substrate 99 on the stage (not shown) is irradiated with the energy accelerated by the extraction electrode 94.

Also in this embodiment, the ions are applied to the substrate 99 in a curtain shape like a waterfall. The doping is performed while scanning the substrate so that the dopant is evenly distributed over the entire substrate. The dose is controlled by the scanning speed of the substrate and the ion current value. The scanning direction at this time is substantially perpendicular to the curtain surface formed by the dopant.

The ion waterfall formed by this device is 2 m wide.
You. This device uses phosphorous or boron as a dopant and
Used to add to conductor materials. The above ions are P
H_y ⁺Or B_TwoH_x ⁺A large amount of H besides ions_Two ⁺Io
Is included. In this embodiment, the concentration is about 5% with hydrogen.
Diluted PH for semiconductor_ThreeOr B_TwoH₆Using gas
Was.

By forming a magnetic field in a direction perpendicular to the ion flow and including the ion curtain surface, a force perpendicular to the ion flow is applied to the ion flow. This is called Lorentz force. Equation of motion F = qv
From B-q E, the lateral force F applied to the ion flow is known. In order not to bend the ion flow, F may be set to 0.

Since the ion velocity component v after the magnetic field incidence in the direction of the ion flow before the magnetic field incidence depends on the mass M of the ion, the velocity v of the ion including the dopant is substituted into the above-mentioned equation of motion, and the force Magnetic field B and electric field E such that F becomes 0
Can be adjusted. At this time, since the hydrogen ions have a speed different from the speed v of the ions including the dopant, the hydrogen ions receive a non-zero force F. Therefore, it is understood that mass separation can be performed by the present apparatus.

To properly change the flow of H ₂ ⁺ ions,
The extraction voltage was set to about 1 to 10 kV, and a magnetic field of about 0.1 to 10 Tesla, preferably about 0.5 to 2 Tesla was preferably applied in the direction of the magnetic field shown in FIG.

The place where the magnetic field is formed is immediately after the extraction electrode 94. If the ions are bent while the kinetic energy of the ions is still small, the ions can be greatly bent with a small energy. The H ₂ ⁺ ions bent immediately after the extraction electrode 94 are suppressed by the suppression electrode 97 and the acceleration electrode 98.
Reaches the substrate on the stage without passing through. In this way, the velocity of H ₂ ⁺ ions at the time of incidence on the substrate can be suppressed.

The angle of incidence of H ₂ ⁺ ions upon reaching the substrate was about 45 °. The angle was sufficient for ions to enter the substrate. On the other hand, the ion stream containing the dopant was irradiated on the substrate after passing through the suppression electrode 97 and the acceleration electrode 98 without being substantially affected by the E × B separator.

The above-described ion accelerating method has the same effect as the methods shown in the fifth and sixth embodiments. The advantage of this embodiment over the fifth and sixth embodiments is that the ion including the dopant reaches the substrate almost straight, so that the extraction electrode 94, the suppression electrode 97, and the acceleration electrode 98 can be reduced. However, since the E × B separator has a slightly complicated structure, the fifth and sixth embodiments are superior in terms of design and maintenance. This embodiment is effective regardless of the scanning direction of the substrate as shown in the fifth and sixth embodiments.

[0116]

According to the present invention, an ion doping apparatus capable of processing a large area can be obtained. Further, the annealing step and the hydrogenation step are not required, or the processing time of those steps can be reduced, or the processing temperature can be reduced. The effects provided by the present invention are as described above. Thus, the present invention is industrially useful.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing an ion source / accelerator of a conventional ion doping apparatus.

FIG. 2 is a view schematically showing a configuration of a conventional ion doping apparatus.

FIG. 3 is a diagram schematically showing a configuration of an ion doping apparatus of the present invention.

FIG. 4 is a diagram schematically illustrating an ion source / accelerator of the ion doping apparatus according to the first embodiment and a schematic shape of an electrode.

FIG. 5 is a diagram showing an outline of an ion source / accelerator of the ion doping apparatus according to the second embodiment, an operation principle, and the like.

FIG. 6 is a diagram showing an outline of an ion source / accelerator of an ion doping apparatus according to a third embodiment, an operation principle, and the like.

FIG. 7 is a diagram schematically illustrating a configuration of an ion doping apparatus according to a fourth embodiment.

FIG. 8 is a diagram schematically illustrating an ion source / accelerator of the ion doping apparatus according to the fifth and sixth embodiments.

FIG. 9 is a diagram schematically illustrating an ion source / accelerator of an ion doping apparatus according to a seventh embodiment.

FIG. 10 is a diagram showing a relationship between an ion incident velocity and a penetration depth.

[Explanation of symbols]

 1, 21 High frequency power supply 2 Matching box 3, 23 Plasma generation electrode 4, 24 Plasma space 5 Insulator 6, 26 Plasma generation electrode 7, 27, 33 Acceleration power supply 8, 28 Extraction power supply 9, 29 Suppression power supply 10, 30 Extraction electrode 11, 31 Suppression electrode 12, 32 Acceleration electrode 13 Ion source / accelerator 14 Power supply 15 Doping chamber 16 Material to be doped 17 Substrate holder 18 Gas line 19 Gas box 20 Exhaust device 34, 35 Magnetic field 36 Slit

Claims (13)

[Claims] 1. A plasma space for generating plasma, an extraction electrode for extracting an ion flow from the plasma space, a device for applying a magnetic field to the ion flow, and a slit. A doping apparatus characterized in that the cross section of the passed ion stream is linear. 2. The doping apparatus according to claim 1, further comprising an accelerating electrode for accelerating an ion flow passing through the slit. 3. The doping apparatus according to claim 1, further comprising: means for moving the substrate in a direction perpendicular to a longitudinal direction of a cross section of the ion flow. 4. The doping apparatus according to claim 1, wherein the magnitude of the magnetic field is 0.1 to 10 Tesla. 5. An ion source containing ions of a dopant gas, an extraction electrode for extracting ions from the ion source and generating an ion current, a device for applying a magnetic field to the ion current, and accelerating the ion current. A doping apparatus, comprising: an accelerating electrode for causing the ion stream to have a linear cross section; and the magnetic field being formed between the extraction electrode and the accelerating electrode. 6. An ion source containing ions of a dopant gas, an extraction electrode for extracting ions from the ion source and generating an ion current, an acceleration electrode for accelerating the ion current, and a voltage between the extraction electrode and an acceleration voltage. And a coil provided in the doping device, wherein a cross section of the ion flow is linear. 7. The doping apparatus according to claim 5, further comprising: means for moving the substrate in a direction perpendicular to a longitudinal direction of a cross section of the ion flow. 8. The doping apparatus according to claim 5, wherein the magnitude of the magnetic field is 0.1 to 10 Tesla. 9. A process for generating a plasma of a dopant gas in a plasma generation space, a process for extracting and accelerating ions from the plasma space to generate an ion flow, and a process for generating an ion flow containing the dopant from the ion flow. Mass separating; and accelerating only the ion flow containing the dopant;
And a cross section of an ion stream containing ions of the dopant gas is linear. 10. The doping method according to claim 9, wherein the ion stream is irradiated while moving the substrate perpendicularly to a longitudinal direction of a cross section of the ion stream. 11. A process for generating a plasma of a dopant gas diluted with hydrogen in a plasma generation space; a process for extracting and accelerating ions from the plasma space to generate an ion flow; Mass-separating the ions of the above, and accelerating the ion stream from which the hydrogen ions have been separated, and irradiating the substrate with the ion stream, wherein the cross section of the ion stream applied to the substrate is linear. Characteristic doping method. 12. The doping method according to claim 11, wherein the ion stream is irradiated while moving the substrate perpendicularly to a longitudinal direction of a cross section of the ion stream applied to the substrate. 13. A process of generating a linear ion flow in a cross section containing ions of a dopant gas, and moving the substrate in a direction perpendicular to the longitudinal direction of the cross section of the linear ion flow. Irradiating the substrate with a flow, and irradiating the substrate with a linear laser beam while moving the substrate perpendicularly to the longitudinal direction of the cross section of the linear ion flow. Characteristic doping method.