KR19990027899A - Ion Implanters for Semiconductor Device Manufacturing - Google Patents

Abstract

An ion implanter for manufacturing a semiconductor device is disclosed. The present invention has a means for generating a plurality of current waveforms having two or more current magnitudes to the ion generator for generating ions, an electromagnet and an electromagnet, and a mass spectrometer for simultaneously extracting ions of the same element having multiple charges among the generated ions; Means for scanning the extracted ions into the semiconductor substrate. At this time, the means for multiplely supplying the current waveform includes a power supply for supplying current to the electromagnet and a trig generating device for triggering the power supply to supply multiple current waveforms having two or more current magnitudes. In addition, the current waveform has a current waveform that is maintained at a predetermined current magnitude for a predetermined time and then at a current magnitude different from the predetermined current magnitude. In addition, the means for scanning the extracted ions into the semiconductor substrate includes a magnetic lens that focuses the extracted ions and an accelerator that accelerates the ions.

Description

Ion Implanters for Semiconductor Device Manufacturing

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to devices for manufacturing semiconductor devices, and more particularly to ion implanters.

The ion implanter used for manufacturing a semiconductor device is composed of an ion source, a mass analyzer, a magnetic lens, or the like. In this case, the ion generator ionizes gas molecules to generate various kinds of ions. The mass spectrometer also extracts ions of the type required in the generated ions. In addition, the magnetic lens is composed of a magnetic quadrupole doublet and a dipole lens magnet, etc., and accelerates and adjusts the extracted ions. That is, it focuses. In addition, a resolving slit for resolving the beam of extracted ions, an electrostatic deflector and an acceleration column for separating neutrons, and the like are further included.

At this time, the mass spectrometer, as shown in Figure 1, the electromagnet 11 and the power supply 13 for supplying current to the electromagnet 11 and the "b" shaped beam guide (beam guide) 15 Is made of. At this time, the supplied current has a constant size determined according to the mass of the ion 16 to be extracted from the generated ions. For example, in order to apply an extraction voltage of 40 KeV and extract P ⁺ ions having an atomic weight of 31 and a charge of 1, a current of approximately 56.3 A is supplied by the power supply. In this way, the supplied current is a current having a constant magnitude without changing its magnitude along a time axis during which the ion implantation process proceeds, that is, the time axis such as T, which is the X axis of the graph enlarged in reference numeral 12 of FIG. Supplied.

Accordingly, the ions implanted into the semiconductor substrate by the ion implanter are limited to one kind, and the concentration profile C _p of the implanted ions exhibits a distribution as shown in FIG. 2. At this time, the curve of reference B in FIG. 2 is a profile immediately after ion implantation, and the curve of reference C is a concentration profile of implanted ions after the heat treatment. As shown in FIG. 2, the profile of ions immediately after ion implantation does not show uniform concentration according to the depth of B. FIG. In addition, the profile C immediately after the heat treatment also shows a relaxed shape as compared to the profile B, but does not implement a uniform concentration depending on the depth. Such a non-uniform concentration profile of implanted ions can degrade the reliability of the formed transistor.

In addition, a method of ion implanting extracted ions several times under different acceleration energy conditions has been proposed to improve the concentration profile as described above. However, problems in surface damage and reproducibility of semiconductor substrates have been derived. In addition, problems arise that make it difficult to control the required ion concentration at the required depth.

An object of the present invention is to provide an ion implanter of a device for manufacturing a semiconductor that can perform an ion implantation process that can implement a uniform concentration profile on the semiconductor substrate according to the ion implantation depth.

1 is a diagram schematically illustrating a mass spectrometer of a conventional ion implanter.

FIG. 2 is a diagram illustrating a concentration profile of ions implanted into a semiconductor substrate by a conventional ion implanter.

3 is a view schematically illustrating the ion implanter according to the present invention.

4 is a schematic view for explaining a mass spectrometer of an ion implanter according to the present invention.

5 is a view for explaining a concentration profile of ions implanted into a semiconductor substrate by the ion implanter according to the present invention.

In order to achieve the above technical problem, the present invention has an ion generator for generating ions, an electromagnet and means for supplying multiple current waveforms having two or more current magnitudes to the electromagnet, and having multiple charges among the generated ions. A mass spectrometer that simultaneously extracts ions of the same element and means for scanning the extracted ions onto a semiconductor substrate. In this case, the means for multi-supplying the current waveform includes a power supply for supplying a current to the electromagnet and a trig generating device for trigging the power supply to supply a multi-current waveform having two or more current magnitudes. Further, the current waveform has a current waveform that is maintained at a current magnitude different from the predetermined current magnitude after being maintained at a predetermined current magnitude for a predetermined time. In addition, the means for scanning the extracted ions into a semiconductor substrate includes a magnet lens that focuses the extracted ions and an accelerator that accelerates the ions.

According to the present invention, it is possible to more uniformly implement the concentration profile according to the depth of the ions injected into the semiconductor substrate. That is, ions can be implanted into the semiconductor substrate to have a constant concentration depending on the depth. As a result, higher reliability in electrical characteristics of the formed transistor can be realized.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 is a diagram schematically illustrating an ion implanter according to the present invention, and FIG. 4 is a diagram schematically illustrating a mass analyzer of the ion implanter shown in FIG. 3.

Specifically, the ion implanter according to the present invention, the ion generator 200 for generating ions, the electromagnet 110 and the means for supplying multiple current waveforms having two or more current magnitudes to the electromagnet 110 (130, 170) A mass spectrometer 100 for simultaneously extracting ions having multiple charges from the generated ions and means 300, 400, 500, 600, 700 for scanning the extracted ions onto the semiconductor substrate 800. Include. In this case, the means for supplying the current waveform in multiple (130, 170), the power supply 130 for supplying a current to the electromagnet and the power supply 130 so that the tree to supply multiple current waveforms having more than two current magnitudes A trig generating device 170 is included. Further, the current waveform has a current waveform that is maintained at a current magnitude different from the predetermined current magnitude after being maintained at a predetermined current magnitude for a predetermined time. In addition, the means for scanning the extracted ions (300, 400, 500, 600, 700), a resolving slit (300) for decomposing the beam of extracted ions, a quadrupole double magnet lens (means for focusing) 400, an electrostatic classifier 500 for separating neutrons, a dipole magnet lens 600, an accelerator 700, and the like.

In this case, the mass spectrometer 100, for example, the mass spectrometer 100 using a 100 ° analyzing magnet, may include multiple charge ions having different charges from the same ions, for example, a single charge ion, Ions of the same element having multiple charges, such as double charge ions and triple charge ions, are simultaneously extracted. The principle is explained as follows.

The mass spectrometer 100 according to the present invention, as schematically shown in FIG. 2, includes an electromagnet 110, a power supply 130, and a trig generator 170. In addition, it further comprises a beam guide 150 of the "a" shape to guide the ions to pass through the magnetic field formed by the electromagnet 110. Reference numeral 150a denotes a planar shape of the beam guide 150. At this time, the ions passing through the magnetic field is affected by the following equation 1 by the magnetic field.

In this case, R denotes a radius of the orbit where the ions are bent under the force of the magnetic field, as indicated by reference numeral 155. In addition, B represents the force of the magnetic field expressed by the electromagnet 110, V represents the extraction voltage applied, M represents the mass of ions extracted. q means the number of charges. By the force according to Equation 1, only the ions bent through a constant radius of the ions passing through the electromagnet 110 can pass through the mass spectrometer 100, the rest of the mass spectrometer 100 Will be filtered out.

In addition, the magnitude of the current to be applied to extract the required ions is obtained according to the following equation (2).

In this case, the unit of the current I is ampere (A). For example, a current of approximately 56.3 A is required to extract 31 P ⁺ ions at an extraction voltage of 40 KeV. In addition, a current of 39.8A is required to extract 31P ⁺⁺ ions. In addition, 32.5A of current is required to extract 31P ⁺⁺⁺ ions. In the present invention, the trig generating device 170 generates a trig signal to the power supply 130 so as to continuously supply the current of the current magnitude as described above to the electromagnet 110. Therefore, the power supply 130 supplies the current waveform as shown by reference numeral 120 to the electromagnet 110 by the trig signal. That is, a current waveform having two or more current magnitudes, for example, is maintained at a predetermined current magnitude for a predetermined time, and then multiplely supplied to the electromagnet 110 a current waveform having a shape that is maintained at a current magnitude different from the predetermined current magnitude.

For example, according to the time T at which ions are implanted into the semiconductor substrate 800 as shown by reference numeral 120, first, a current of 56.3 A is supplied during a time t, and a current of 39.8 A is supplied during a t '. , 32.5A current during t˝. Currents having respective current magnitudes are supplied branched by the trig generating device 170. According to this, in the above during the entire ion implantation time T, time 31P ⁺ ions orbiting radius is about 0.885 while this t, the time t'31P ⁺⁺ ion orbital radius is about 0.885 long, time orbiting radius while the t˝ Approximately 0.885 31P ⁺⁺⁺ ions are extracted. In other words, ions of the same element having different charges are simultaneously extracted by the mass spectrometer 100.

The beam of ions thus extracted is then accelerated and injected into the semiconductor substrate 800. In this case, since the ions have different numbers of charges, the accelerated energy is different when the ions are accelerated. That is, since the charge amount and the energy have a relationship of E = qeV (E; energy, q; charge amount V; potential), the triple charge ions have three times as much energy as the single charge ions, and the double charge ions You will have twice as much energy. For example, in the above example using 31P ⁺ ions as the single charge ion, while implanting with energy of approximately 40KeV, 31P ⁺⁺ ions, which are double charge ions, are implanted with energy of approximately 80KeV, and 31P ⁺⁺⁺ , which are triple charge ions Ions are implanted at an energy of approximately 120 KeV. Therefore, depths of the ions injected into the semiconductor substrate 800 are different from each other.

By simultaneously ion implanting ions having multiple charges, a concentration profile according to the implanted depth as shown in FIG. 5 can be obtained. At this time, the peak of the ion concentration profile by the single charge ion is shown by reference D, the peak of the ion concentration profile by the double charge ion is shown by reference E, and the peak of the ion concentration profile by the triple charge ion is referenced by It is shown by the symbol F. In this manner, the curves of the three peaks overlap to form the concentration profile G immediately after the ion implantation. Therefore, the attainment of the thermal equilibrium by the subsequent heat treatment can be easily proceeded, so that an ion concentration profile such as reference numeral H can be realized. That is, it is possible to implement a concentration profile having a uniform ion concentration according to the depth. As a result, reliability in electrical characteristics of the formed transistor is further secured.

As mentioned above, although this invention was demonstrated in detail through the specific Example, this invention is not limited to this, It is clear that the deformation | transformation and improvement are possible by the person of ordinary skill in the art within the technical idea of this invention.

According to the present invention described above, by simultaneously extracting multiple charge ions of the same element and ion implantation into the semiconductor substrate, the implanted ions are accelerated to different sizes by different charge amounts of the ions. Therefore, since the energy of the implanted ions is dependent on the amount of charge, the implanted depth is also changed. Therefore, the concentration profile according to the depth of the ions implanted in the semiconductor substrate can be more uniformly implemented. That is, ions can be implanted into the semiconductor substrate to have a constant concentration depending on the depth. As a result, higher reliability in electrical characteristics of the formed transistor can be realized.

Claims (4)

An ion generator for generating ions; A mass spectrometer having means for multiplely supplying an electromagnet and a current waveform having two or more current magnitudes to the electromagnet, wherein the mass spectrometer simultaneously extracts ions of the same element having multiple charges among the generated ions; And And means for scanning the extracted ions onto a semiconductor substrate. 2. The apparatus of claim 1, wherein the means for multifeeding the current waveform is A power supply for supplying current to the electromagnet; And And a trig generator configured to trig the power supply to supply multiple current waveforms having two or more current magnitudes. The ion implanter of claim 1, wherein the current waveform is maintained at a predetermined current magnitude for a predetermined time, and then at a current magnitude different from the predetermined current magnitude. The device of claim 1, wherein the means for scanning the extracted ions into a semiconductor substrate comprises: A magnetic lens for focusing the extracted ions; And And an accelerator for accelerating the ions.