JP2003188110A - Doping method and ion implantation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a doping method and ion implantation apparatus which can form a shallow p-type layer or n-type layer. <P>SOLUTION: The apparatus is equipped with 1st and 2nd ion sources 11a and 11b, a 1st mass separator 13a which performs mass separation of ions drawn out of the 1st ion source 11a, a 2nd mass separator 13b which performs mass separation of ions drawn out of the 2nd ion source 11b, and an introducing means of introducing the ions separated by the 1st and 2nd mass separator 13a and 13b into a substrate 20. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for doping a silicon substrate and an ion implantation apparatus.

[0002]

2. Description of the Related Art When manufacturing a semiconductor element or a semiconductor integrated circuit, impurity ions are implanted into a semiconductor substrate to p-type layer or n-type.
The technique for forming the shaping layer is important. Next-generation ultra-large scale integrated circuits require the formation of shallower junctions than conventional junctions. Currently, as a technique for forming a shallow junction on a silicon substrate, a technique combining a low energy ion implantation method and a short-time heat treatment technique is generally used.

[0003]

However, at the time of impurity ion implantation, lattice defects are introduced into the silicon substrate at a high density. Among them, interstitial silicon reacts with ion-implanted boron to increase the diffusion rate of boron,
Silicon vacancy lattices also increase the diffusion rate of ion-implanted arsenic (W. K. Holker et al., Ap.
pl. Phys. 4,125 (1974)). Therefore, even if impurities are implanted into the silicon substrate by the low energy ion implantation method to form the shallow p-type layer or the n-type layer, it is difficult to form the target shallow p-type layer or the n-type layer.

In view of the above situation, it is an object of the present invention to provide a doping method and an ion implantation apparatus capable of forming a p-type layer or an n-type layer shallower than the conventional method.

[0005]

In order to achieve the above object, the doping method of the present invention is a method of doping a silicon substrate, wherein a silicon substrate at a temperature of 100 ° C. or lower is 0.1 keV to 15 keV. Impurity ions are implanted with an energy within the range of 0.01 keV to 4 keV
And a second step of heat-treating the silicon substrate at a temperature in the range of 600 ° C to 900 ° C.

In the above doping method, the impurity ions may be at least one ion selected from boron, phosphorus, arsenic and hydrogen compounds thereof.

The ion implanter of the present invention is an ion implanter for implanting ions into a substrate.
And a second ion source, and a first mass separator that performs mass separation of the ions extracted from the first ion source,
A second mass separator for mass-separating the ions extracted from the second ion source; and an introducing means for introducing the ions separated by the first and second mass separators into the substrate. It is characterized by including.

The above ion implantation apparatus further comprises a stage on which the substrate is arranged, and a first measuring means connected to the stage for measuring the amount of ions implanted in the substrate, and the first measuring means. Further comprising second measuring means for measuring the amount of ions extracted from the second ion source, and third measuring means for measuring the amount of ions extracted from the second ion source. Good.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) In Embodiment 1, a doping method of the present invention will be described.

In the method of the first embodiment, first, impurity ions are implanted into a silicon substrate at a temperature of 100 ° C. or lower at an energy within a range of 0.1 keV to 15 keV (more preferably within a range of 0.1 keV to 5 keV). Then 0.01
Within the range of keV to 4 keV (more preferably 0.01
Hydrogen ions are implanted at an energy of keV to 1 keV) (first step). At this time, the implantation energy of the impurity ions is preferably larger than the implantation energy of the hydrogen ions. As the impurity ions, at least one ion selected from boron, phosphorus, arsenic, and hydrides thereof can be used. Examples of the above-mentioned hydride include B ₂ H ₆ , PH ₃ and As.
H _{3 and the} like can be mentioned. The temperature of the silicon substrate may be as low as room temperature (for example, 25 ° C. or lower). Impurity ions and hydrogen ions may be injected simultaneously or separately.

Next, the ion-implanted silicon substrate is heat-treated at a temperature in the range of 600 ° C. to 900 ° C. (second step). The heat treatment time is not particularly limited, but is, for example, about 20 minutes to 100 minutes. The heat treatment is preferably carried out at normal pressure in an inert gas atmosphere. By the heat treatment of the second step, the implanted ions are activated, and the lattice defects generated during the ion implantation disappear to recover the silicon crystal.

In the doping method of the first embodiment, in the first step, impurity ions and hydrogen ions are shallowly implanted into a low temperature substrate with low energy. Then, in the second step, the impurity ions can be activated without increasing the diffusion rate of the impurity ions by annealing the silicon substrate into which the impurity ions and the hydrogen ions are both implanted. Therefore, according to the doping method of Embodiment 1, the impurities can be activated in the semiconductor with a distribution that is almost the same as the impurity distribution at the time of ion implantation, and a shallow junction can be formed as compared with the conventional method.

(Embodiment 2) In Embodiment 2, an example of the ion implantation apparatus of the present invention will be described. In the description of the second embodiment, the same parts will be denoted by the same reference symbols and redundant description will be omitted.

As an example of the ion implanter of the second embodiment, the structure of the ion implanter 10 is schematically shown in FIG.
Referring to FIG. 1, an ion implanter 10 includes first and second ion sources 11a and 11b, first and second extractor / focusers 12a and 12b, and first and second mass separators. 13a and 13b, a converging device 14,
An XY direction deflector 15, a target chamber 17 in which a substrate stage 16 is arranged, first and second beam monitors 18a and 18b, and a measuring means 19 for measuring the amount of implanted ions are provided.

The ion implantation apparatus 10 is provided with an exhaust means (not shown) such as a turbo molecular pump so that the inside pressure can be reduced. A substrate 20 is arranged on the substrate stage 16. The substrate 20 is not particularly limited, but is generally a semiconductor substrate such as a silicon substrate.

First and second ion sources 11a and 1
1b is an ion source for generating different ion species. The type of these ion sources is not particularly limited, and for example, plasma type, Kauffman type, ECR plasma type ion sources can be used.

The first extractor / focuser 12a extracts the ions generated by the first ion source 11a by applying a voltage to the extraction electrode, and converges the ions at the entrance of the first mass separator 13a. Further, the second extractor / focuser 12b extracts the ions generated by the second ion source 11b by applying a voltage to the extractor electrode, and converges the ions at the entrance of the second mass separator 13b. At this time, the first and second beam monitors 18a and 18b monitor the amount of ions introduced from each ion source into the mass separator. In the first and second extraction / focusing units 12a and 12b, the voltage of the extraction electrode is controlled to control the energy of the ion beam.

The first and second mass separators 13a and 13b are used for the substrate 2 among the ions introduced from the ion source.
Ions to be injected into 0 are selected and introduced into the converging unit 14. The impurity ions, hydrogen ions, or mixed ions thereof converged by the concentrator 14 are introduced into the XY deflector 15 and injected into the substrate 20 in order to uniformly implant the ions into the substrate 20. To be done. Focuser 14 and X
The −Y direction deflector 15 functions as an introducing unit for introducing the ions separated by the mass separator into the substrate 20.

The measuring means 19 is a device for measuring the amount of ions implanted in the substrate 20. Specifically, a coulometer connected to the substrate stage 16 can be used. In the ion implantation apparatus 10, the beam intensities measured by the first and second beam monitors 18a and 18b can be calibrated using the measuring means 19. By this calibration, even when the impurity ions and the hydrogen ions are simultaneously implanted into the substrate 20, the amount of the impurity ions and the amount of the hydrogen ions can be individually obtained, and thus the amount of the ions implanted into the substrate 20 can be controlled.

The substrate stage 16 may include a heater for heating the substrate 20 or a cooling device for cooling the substrate 20.

The ion implanter 10 can implant different ion species into the substrate 20 simultaneously or individually by using two ion sources and two mass separators. Therefore, by using the ion implantation apparatus 10, the method described in the first embodiment, that is, the method of implanting impurity ions and hydrogen ions into the silicon substrate at low energy and then performing the heat treatment can be easily implemented. Therefore, by using the ion implantation apparatus 10, the impurities can be activated in the semiconductor without significantly changing the distribution of the impurities at the time of ion implantation, and a shallow junction can be formed as compared with the conventional apparatus. Furthermore, since the ion implanter 10 can implant two ion species simultaneously,
The operating rate of the device is increased, and the semiconductor device can be manufactured at low cost.

The ion implantation apparatus of the present invention may be any apparatus as long as it has two ion sources, two mass separators corresponding thereto, and introducing means for introducing ions into the substrate. Not only the configuration of the ion implantation apparatus 10 but various other configurations are possible. A plurality of examples will be described below, but the following examples have the same effects as the ion implantation device 10.

(Embodiment 3) In Embodiment 3, another example of the ion implantation apparatus of the present invention will be described. The configuration of the ion implantation apparatus 10a according to the third embodiment is schematically shown in FIG. The ion implanter 10 a is different from the ion implanter 10 in that the ion implanter 10 a includes a speed reducer 21.
Duplicated description of parts other than 1 will be omitted. Decelerator 21
Is a device for decelerating the ions separated by the mass separator, and by decelerating the ions using the device, it becomes possible to form a shallower junction.

(Embodiment 4) In Embodiment 4, another example of the ion implantation apparatus of the present invention will be described. The configuration of the ion implantation apparatus 10b of the third embodiment is schematically shown in FIG. Compared to the ion implanter 10, the ion implanter 10b includes a first ion source 11a and a second ion source 11a.
b, first and second extractor / convergers 12a and 1
2b, first and second mass separators 13a and 13
b, since only the arrangement of the first beam monitor 18a is different, duplicate description will be omitted.

In the ion implanter 10b, the first mass separator 13a, the second mass separator 13b, the concentrator 14, and X.
The −Y-direction deflector 15 and the target chamber 17 are arranged in this order in a line. And the first
The first ion source 11a is connected to the mass separator 13a, and the second ion source 11b is connected to the second mass separator 13b. The ions generated by the first ion source 11a are extracted by the first extractor / focuser 12a and sorted by the first mass separator 13a. Similarly, the ions generated by the second ion source 11b are extracted by the second extractor / focuser 12b and sorted by the second mass separator 13b. The ions selected by the first and second mass separators 13a and 13b are injected into the substrate 20 via the converging device 14 and the XY direction deflector 15. First beam monitor 18
As shown in FIG. 3, a is located at a position where the ions passing through the first mass separator 13a can be monitored.

(Fifth Embodiment) In a fifth embodiment, another example of the ion implantation apparatus of the present invention will be described. The configuration of the ion implantation apparatus 10c of the fifth embodiment is schematically shown in FIG. The ion implanter 10c is different from the ion implanter 10b only in that the ion implanter 10c is provided with a speed reducer 21, and therefore, the description other than that other than the speed reducer 21 will be omitted. The decelerator 21 is a device that decelerates the ions separated by the mass separator, and by decelerating the ions using the device,
It becomes possible to form a shallower junction.

[0028]

EXAMPLES The present invention will be described in more detail with reference to examples.

Example 1 In Example 1, an example of doping the silicon substrate with boron by the doping method of Embodiment 1 will be described.

First, room temperature (about 25 ° C.) is applied to a silicon substrate.
And impurity ions (B ₂ H ₅ ⁺ . Implantation energy: 10 k
eV) and hydrogen ions (H ³⁺ . Implantation energy 3.33k
eV) was injected. Impurity ions were generated by ionizing diborane. After that, with respect to the plurality of silicon substrates into which the ions have been implanted, 700 ° C., 80
Heat treatment was performed at an annealing temperature of 0 ° C. or 900 ° C. for 30 minutes. In this way, a silicon substrate in which the implanted boron was activated was obtained.

On the other hand, as a comparative example, only boron ions (B ⁺ ) were implanted into a silicon substrate without implanting hydrogen ions, and heat treatment was performed under the same heat treatment conditions as above. In this way, a silicon substrate of a comparative example in which the implanted boron was activated was obtained.

Secondary ion mass spectrometry (SIMS) was performed on the silicon substrate immediately after ion implantation and after heat treatment.
The relationship between the distance from the surface and the boron atom density was measured by. The measurement result is shown in FIG. In addition, in FIG.
The atomic density distribution of hydrogen atoms when ₂ H ₅ ⁺ and H ^{3 +} are injected (the vertical axis is the same as the boron atom density) is also shown.

As is clear from FIG. 5, the silicon substrate in which B ₂ H ₅ ⁺ ions and hydrogen ions were implanted was compared with the silicon substrate of the comparative example which was heat-treated at the same annealing temperature.
The distribution of boron was quite shallow. 800 ° C. for a silicon substrate in which B ₂ H ₅ ⁺ ions and hydrogen ions are implanted
The distribution of boron did not change much from the distribution immediately after ion implantation even after the heat treatment. Thus, the shallow junction could be formed by the method of Example 1.

Example 2 In Example 2, an example of doping the silicon substrate with boron by the doping method of Embodiment 1 will be described.

First, room temperature (about 25 ° C.) is applied to a silicon substrate.
Then, boron ions (B ⁺ ) and hydrogen ions (H ³⁺ ) were implanted. The dose amount of boron ions was 5 × 10 ¹⁵ cm ⁻² , and the implantation energy was 10 keV. Further, the dose amount of hydrogen ions was 6 × 10 ¹⁵ cm ⁻² , and the implantation energy was 2 keV. After that, regarding the plurality of silicon substrates into which the ions are implanted, 700 ° C., 800 ° C. or 9
Heat treatment was performed at an annealing temperature of 00 ° C. for 30 minutes. In this way, a silicon substrate in which the implanted boron was activated was obtained.

On the other hand, as a comparative example, only boron ions (B ⁺ ) were implanted into a silicon substrate without implanting hydrogen ions, and heat treatment was performed under the same heat treatment conditions as described above. In this way, a silicon substrate of a comparative example in which the implanted boron was activated was obtained.

Secondary ion mass spectrometry (SIMS) was performed on the silicon substrate immediately after ion implantation and after heat treatment.
The relationship between the distance from the surface and the boron atom density was measured by. The measurement result is shown in FIG.

As is clear from FIG. 6, the distribution of boron was considerably shallower in the silicon substrate in which boron ions and hydrogen ions were implanted, as compared with the silicon substrate of the comparative example which was heat-treated at the same annealing temperature. In the silicon substrate in which boron ions and hydrogen ions were implanted, the distribution of boron did not change much from the distribution immediately after the ion implantation even when heat-treated at 800 ° C. Thus, the shallow junction could be formed by the method of Example 2.

Although the embodiments of the present invention have been described above with reference to examples, the present invention is not limited to the above embodiments and can be applied to other embodiments based on the technical idea of the present invention. .

[0040]

As described above, according to the doping method of the present invention, a shallow p-type layer or n-type layer can be formed as compared with the conventional method.

According to the ion implantation apparatus of the present invention,
Since different ion species can be injected into the substrate alternately or simultaneously, the doping method of the present invention can be easily and inexpensively carried out.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an example of the configuration of an ion implantation device of the present invention.

FIG. 2 is a diagram schematically showing the configuration of another example of the ion implantation apparatus of the present invention.

FIG. 3 is a diagram schematically showing the configuration of another example of the ion implantation apparatus of the present invention.

FIG. 4 is a diagram schematically showing the configuration of still another example of the ion implantation apparatus of the present invention.

FIG. 5 is a diagram showing an example of a measurement result by SIMS of a silicon substrate which is doped by using the doping method of the present invention.

FIG. 6 is a diagram showing another example of measurement results by SIMS of a silicon substrate that is doped by using the doping method of the present invention.

[Explanation of symbols]

10, 10a, 10b, 10c Ion implanter 11a First ion source 11b Second ion source 12a First drawer / focuser 12b Second drawer / focuser 13a First mass separator 13b Second mass separator 14 Concentrator (introduction means) 15 X-Y direction deflector (introducing means) 16 substrate stage 17 Target room 18a First beam monitor (measuring means) 18b Second beam monitor (measuring means) 19 Measuring means 20 substrates 21 Reducer

Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01J 37/317 H01L 21/265 F

Claims (4)

[Claims] 1. A method for doping a silicon substrate, the method comprising:
A first step of implanting impurity ions at an energy in the range of 15 keV and hydrogen ions at an energy in the range of 0.01 keV to 4 keV; and heat treating the silicon substrate at a temperature in the range of 600 to 900 ° C. And a second step of carrying out the doping method. 2. The doping method according to claim 1, wherein the impurity ions are at least one ion selected from boron, phosphorus, arsenic, and hydrogen compounds thereof. 3. An ion implanter for implanting ions into a substrate, comprising first and second ion sources, and a first mass for mass-separating the ions extracted from the first ion source. A separator, a second mass separator that performs mass separation of the ions extracted from the second ion source, and to introduce the ions separated by the first and second mass separators into the substrate An ion implantation apparatus comprising: 4. A first measuring means connected to the stage for measuring the amount of ions implanted in the substrate, further comprising: a stage on which the substrate is arranged; The third measuring means for measuring the amount of extracted ions, and the third measuring means for measuring the amount of ions extracted from the second ion source. Ion implanter.