KR20070117263A - Bernas type implanter - Google Patents

Abstract

A Bernas-type ion implanting apparatus is provided to prevent thermal electrons from being lost through the walls of an arc chamber by removing a dead volume part to maintain a self-shielding effect. An arc power part receives power from an external power source to generate arc power. A filament power part receives the power supplied from the arc power part to generate filament power. A spiral block filament(46) receives power from the filament power part to generate heat wherein a dead volume part is removed to avoid loss of thermal electrons through the walls of an arc chamber, having a spiral type. A repeller prevents the thermal electrons accelerated by the arc power from disappearing to a chamber body without ionizing discharged gas, installed in an opposite portion to the spiral block filament. In the spiral block filament, the dead volume part can be removed in order to maintain self-shielding effect.

Description

Bernas type ion implanter {BERNAS TYPE IMPLANTER}

1 is a structural diagram of the arc chamber of the burner type ion source portion

2A is a structural diagram of a coil-type filament

2B is a structural diagram of a flat-type filament

3A is a block diagram of a conventional block filament

Figure 3b is another embodiment of a more improved conventional block filament

4 is a structural diagram of the arc chamber of the burner-type ion source unit according to an embodiment of the present invention;

5 is a perspective view of the spiral block filament 46 of FIG.

FIG. 6A shows a state before dead volume 56 is removed. FIG.

6B is a view illustrating a state in which all of the dead volume portions 56 are removed.

FIG. 6C is a view illustrating a state in which the dead volume portion 56 is removed in consideration of self-shielding.

             Explanation of symbols on the main parts of the drawings

40: external power supply 42: arc power supply unit

44: filament power supply 46: spiral block filament

48: repeller 50: chamber body

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Bernas-type ion implantation apparatus, and more particularly to a Bernas-type ion implantation apparatus which prevents high-temperature warpage and glitches due to the load of a srilar block filament in an ion implantation apparatus.

In general, the ion implantation process is a P-type impurity (eg, boron, aluminum, indium) having three appliances on a pure silicon (Si) wafer, and an N-type impurity (eg, antimony, phosphorus, arsenic) having five appliances It is a process of making the device of the conductivity type and the resistivity necessary by making the ion into a plasma ion beam state and penetrating into the semiconductor crystal.

An ion implantation apparatus for performing such an ion implantation process is disclosed in US Pat. No. 5,475,618. The ion implantation device can control the impurity concentration in the range of 10E14 to 10E18 atoms / cm 3 when manufacturing a semiconductor device, which is easier to control the concentration than using other impurity implantation techniques such as diffusion, and can accurately adjust the depth of ion implantation. Because of the advantage that the integration of the semiconductor device is increasing is more widely used.

Ion implantation refers to the implantation of atomic ions into a target with energy that is large enough to penetrate the surface of the target. The ion implanter was only a research device until 1971. Recently, there have been many changes in various aspects such as internal design, appearance, and performance.

The ion implanter consists of an ion source section, a beam line section, and a process chamber section. The ion source section includes an evaporator (gas box) and an arc chamber. It is composed of extraction.

The ion source portion is a place where molecules are ionized, the arc chamber forms free electrons in the filament, and the formed free electrons collide with the injected gas to form ions. Referring to the conventional arc chamber components, the top plate, which is a passage through which the generated cations are discharged, the ionization chamber, which forms a plasma formation space, a straight filament that generates electrons through electric current, and a filament insulator that serves as an insulation between the ionization reaction chamber and the filament And a filament clamp that secures the filament and serves as a passage of current. The central straight filament is enclosed so that the main body is spaced apart, the filament protrudes to the outside on both sides of the main body, and the insulation part is placed in the contact portion between the filament and the main body serves as an insulation role. However, a straight filament in which tungsten wire is used may have a relatively high temperature portion because the electrons emitted do not have uniform performance, and may break momentarily even when contacted with oxygen in the air. It costs around. If the filament is broken, it must be replaced immediately for normal ionization reaction, and unnecessary replacement time and reheating time are consumed. The main body is an integral type that cannot be separated, and even if a part is consumed, the whole should be replaced. If not replaced in a timely manner, a considerable amount of contamination may occur, causing unclean ionization.

1 is a structural diagram of an arc chamber of a burner-type ion source portion.

An external power source 10, an arc power unit 12 receiving the external power source 10 to generate arc power, a filament power source unit 14 generating a filament power by receiving power supplied from the arc power unit 12, and In addition, the filament 16 which receives power from the filament power supply unit 14 and generates heat, and the hot electrons installed on the opposite side of the filament 16 and accelerated by the arc power generated from the arc power supply unit 12 discharge the discharge gas. It consists of a repeller 18 which prevents annihilation of the chamber body 20 without ionization.

The Bernas type ion source utilizes a thermoionic emission phenomenon from the filament 16 to generate seed electrons for ionization of the process gas. This is achieved by generating a joule heat by allowing a high current to flow through the filament 16 by using the filament power source generated from the filament power supply unit 14. Joule has the symbol J. 1J = 1 Nm = 107 erg. 1J corresponds to the work done while moving the object 1m with 1N force and the amount that can be converted into the work, which is equivalent to the amount of work that consumes 1W of power in one second. At this time, in order to accelerate the hot electrons emitted from the filament 16 to obtain sufficient energy to ionize the reactor body, a strong positive potential (+60 ~ 150V) is applied to the chamber body 20 using an arc power source. In order to prevent the hot electrons accelerated by the voltage of the chamber body 20 in the arc power source from disappearing into the chamber body 20 without ionizing the discharge gas, the filament 16 On the opposite side of), a repeller 18 having a negative potential (-5 V) is provided, and a strong magnetic field is applied from the filament 16 to the repeller 18 by using a magnet coil.

As a result, the charged particles in the chamber body 20 receive the Lorentz force (F) by the electric field vector (E) and the magnetic field vector (B) distribution as shown in Equation (1). At this time, in the case of very small electrons, the rotation radius due to the Lorentz force becomes very small and eventually moves along the magnetic force line, which is called magnetic confinement of the electrons.

F = q (E + v × B)

Magnetic confinement of the electrons causes ionization or dissociation of the reactants in the arc chamber, and the generated cations move toward the extraction slit along the electric field gradient.

At this time, the cations generated around the filament 16 are incident toward the filament 16 along the potential gradient, so that the filament 16 undergoes a sputtering etch due to constant ion collision, and FIGS. 2A and FIG. As the ion implanter operates as in 2b, it becomes thinner and eventually breaks. FIG. 2A is a coil-type filament and FIG. 2B is a flat-type filament.

The shortening of the life of the filament 16 by the sputtering etching reduces the PM cycle of the ion implantation equipment and increases the down-time of the equipment, thereby lowering the productivity of the ion implantation equipment.

In order to solve this problem, block filaments as shown in FIGS. 3A and 3B have been developed.

An embodiment of a block filament will be described with reference to FIG. 3A.

The filament plate 120 is a rectangular contour with a generally rounded corner. The filament plate 120 includes two helical slits 122, 124 that penetrate the width W ′ of the plate. The slits 122, 124 extend helically from the respective sidewalls 126, 128 toward the central region C of the filament plate 120. Slits 122 and 124 are superimposed and mostly parallel over each length. The gap width or average distance between the opposing inner wall surfaces of the filament plate 120 defining each slit 122, 124 is uniform along the slit length. Also, the gap widths of the slits are substantially the same. Suitable dimensions for the length L1 'of the short sidewalls 126 and 128, the length L2' of the long sidewalls 132 and 134, the width W 'of the filament plate 120 and the gap width are as follows. Table 1 is as follows.

Table 1

The filament plate 120 includes two through holes spaced inwardly from the sidewalls 126, 128. A pair of spaced apart conductive posts 140, 142 are pressure-fitted into the opening. The power feed 88 is connected to the conducting posts 140, 142. When voltage is applied to the power feed 88, current flows through the plate 120 along the spiral labyrinth path I '.

The magnitude of the current I 'through the filament plate 120 is appropriately adjusted to raise the temperature of the plate through which the current I' flows to the hot electron emission temperature at which the plate emits free electrons. Top surface 144 of filament plate 120 provides a wide and efficient surface for hot electron emission.

The gap width of the slits 122, 124 is generally less than 10 times the debye shield length of the charged plasma resulting from conventional source material injected into the interior region 68 of the arc chamber. This minimizes penetration of the activated plasma into the gaps of the slits 122, 124 and thus minimizes erosion of the inner wall surfaces defining the slits. As noted with respect to the first embodiment, erosion by sputtering is substantially limited to the upper surface 144 of the filament plate 120. Sputtering does not occur at the bottom surface 146 of the filament plate 120, because formed between the filament plate bottom surface 146 and the arc chamber sidewall 66, through which the conductive posts 140, 142 extend. This is because the volume of the inner region of the arc chamber is too small to maintain the plasma.

Figure 3b is another embodiment of a more improved conventional block filament.

Referring to FIG. 3B, the filament plate 80 is composed of tungsten and in the form of an isosceles triangle with rounded corners. Two helical cuts or slits 96 and 98 are cut through the width W of the filament plate 80. Preferably, the slits 96 and 98 are formed in the filament plate 80 using wire elective discharge machining (EDM) methods well known to those skilled in the art. The slits 96, 98 extend from the side walls 92, 94, respectively, and are spiral inwardly with an increasingly smaller radius towards the common center region C of the filament plate 80. The slits 96 and 98 are superimposed and parallel to each other along most of their lengths. The gap width or average distance between the opposing inner wall surfaces of the filament plate 80 defining the respective slits 96 and 98 is uniform along the slit length. The gap widths of the slits are substantially the same. Suitable dimensions for the length L1 of the short sidewalls 90 and 92, the length L2 of the long sidewall 94, the width W of the filament plate 80 and the gap width are shown in Table 2 below.

Table 2

The filament plate 80 includes two through holes spaced inwardly from the corners 100, 102. A pair of spaced apart conductive posts 106, 108 are pressure fitted into each opening. As best shown in FIGS. 3 and 4, the filament plate 80 is disposed in the interior region 68 of the arc chamber away from the side wall 66, with the top surface 110 of the filament plate being repelled. 82 is also directed to be substantially parallel to the sidewall supporting it. Conductive posts 106, 108 extend through a pair of aligned holes in arc chamber sidewall 66. Insulators 109 are sandwiched between the conductive posts 106 and 108 and the sidewall openings to insulate the arc chamber 62 from the conductive posts. The protective plate 107 is located on the conductive posts 106, 108 between the insulators 109 and the filament plate 80. The protective plate 107 prevents the deposition of metal on the insulator 109.

Two power feeds 88 (one of which is shown in FIG. 2) are connected to the conducting posts 106, 108. When voltage is applied to the power feed 88, current flows through the plate 80 along the spiral labyrinth path I (FIG. 6). Where the slits 96 and 98 overlap, the current path I has a generally constant width from the outside of the filament plate 80 to the common center region C, ie extending radially outward from the common center region C. The spacing between adjacent slits measured along is generally constant.

The current flow I through the filament plate 80 is properly adjusted to raise the temperature of the plate to the hot electron emission temperature at which the plate will release free electrons. Top surface 110 (FIG. 6) of filament plate 80 provides a wide and efficient surface for hot electron emission. Preferably, the gap width of the slits 96 and 98 is no more than 10 times the length of the debye shielding length of the charged plasma generated from a common source material injected into the interior region 68 of the arc chamber. Debye shielding length for plasma with arsenic, phosphorous or antimony source material is 0.1-0.5 mm. Thus, the preferred gap width of 0.3 mm does not even exceed 10 times the deby shielding length of plasma with a deby shielding length of 0.1 mm. This slit gap width is so narrow that the activated plasma cannot be maintained in the gap, i.e. the energy of the activated plasma entering the slits 96, 98 is rapidly attenuated to define the filament plates defining each of the slits 96, 98. Plasma erosion of the inner wall surfaces of 80 is minimized.

Erosion by sputtering is substantially limited to the upper surface 110 of the filament plate 80. Sputtering does not occur on the bottom surface 112 of the filament plate 80 because it is formed between the filament plate bottom surface 112 and the arc chamber sidewall 66 and the conductive posts 106, 108 extend through. This is because the volume of the inner region of the arc chamber is too small to maintain the plasma.

The block filament as described above is capable of producing a thick filament in the direction of incidence of ions while maintaining a cross-sectional area by using electrical discharge machining or wire cutting, thereby greatly extending the life of the filament. It is possible.

In addition, since complex conductive path processing is possible, an area-type thermionic source can be obtained by greatly expanding the area where hot electrons are emitted. Particularly, spiral type block filaments having a conductive path having a spiral shape as shown in FIGS. 3A and 3B are easy to process, and thus have excellent mass productivity.

However, two existing problems exist in the existing spiral block filament.

The first problem is that heavy tungsten filaments have a high load as the conductive path shapes become complicated, and thus warpage occurs due to high heat generated during the ion implantation process.

The second problem is that as the size of the filament becomes larger than the conventional wire type, the closer to the wall of the arc chamber and the electric potential gradient applied to the surface of the filament increases, thereby increasing the rate of glitches. .

Accordingly, an object of the present invention is to provide a Bernas-type ion implantation apparatus for preventing high temperature warpage phenomenon to minimize the load of the spiral block filament in the ion implantation facility to solve the above problems.

Another object of the present invention is to provide a Bernas-type ion implantation apparatus that prevents glitches by minimizing an electric field gradient formed between the hot electron emission portion of the filament and the arc chamber.

The Bernas-type ion implantation apparatus of the present invention for achieving the above object comprises an external power source, an arc power unit for generating arc power by receiving the external power, and a filament for generating filament power by receiving power supplied from the arc power unit. Spiral block filaments are formed spirally and the spiral volume filament is removed from the filament power supply to remove heat from the filament power supply so that the dead volume is removed so as not to generate a thermal electron loss to the arc chamber wall, the arc is installed on the opposite side of the spiral block filament It characterized in that it comprises a repeller to prevent the hot electrons accelerated by the arc power generated from the power supply unit to disappear into the chamber body without ionizing the discharge gas.

The repeller is characterized in that to generate a negative potential of -5V.

The spiral block filament has a structure in which the dead volume portion is removed in consideration of self-sealing.

The spiral block filament is characterized in that the micro-glitch is prevented by preventing the loss of hot electrons from the arc chamber to the wall.

In order to achieve the above object, the spiral block filament of the Bernas-type ion implantation apparatus of the present invention includes first and second conductive posts, one end of which is connected to the first conductive post, and multiple stages of the second conductive post. It is made of a spiral, characterized in that the dead volume portion is removed to prevent the occurrence of hot electron loss to the arc chamber wall.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

4 is a structural diagram of the arc chamber of the burner-type ion source unit according to an embodiment of the present invention.

An external power source 40, an arc power source unit 42 receiving the external power source 40 to generate arc power, a filament power source unit 44 generating a filament power source by receiving power supplied from the arc power source unit 42, and Spiral block filament 46 is spirally formed and is heated by being supplied with power from the filament power supply 44 so that dead volume is removed to prevent thermal electron loss to the arc chamber wall. A repeller 48 installed on the opposite side of the filament 46 to prevent hot electrons accelerated by the arc power generated from the arc power supply 42 from disappearing into the chamber body 50 without ionizing a discharge gas. It consists of).

The Bernas type ion source uses a thermoionic emission phenomenon from the spiral block filament 46 to generate seed electrons for ionization of the process gas. This is achieved by generating a joule heat by allowing a high current to flow through the spiral block filament 46 using the filament power generated from the spiral block filament power supply unit 44. Joule has the symbol J. 1J = 1 Nm = 107 erg. 1J corresponds to the work done while moving the object 1m with 1N force and the amount that can be converted into the work, which is equivalent to the amount of work that consumes 1W of power in one second. At this time, in order to accelerate the hot electrons emitted from the filament 46 to obtain sufficient energy to ionize the reactor body, a strong positive potential (+60 ~ 150V) is applied to the chamber body 50 using an arc power source. In order to prevent the hot electrons accelerated by the voltage of the chamber body 50 in the arc power source from disappearing into the chamber body 50 without ionizing the discharge gas, a spiral block filament ( On the opposite side of 16), a repeller 48 having a negative potential (-5V) is installed, and a strong magnetic field is directed from the spiral block filament 46 to the repeller 48 by using a magnet coil. Is authorized.

As a result, the charged particles in the chamber body 20 are subjected to Lorentz force (F) by the distribution of the electric field vector (E) and the magnetic field vector (B). At this time, in the case of very small electrons, the rotation radius due to the Lorentz force becomes very small and eventually moves along the magnetic force line, which is called magnetic confinement of the electrons.

The magnetic confinement of the electrons causes ionization or dissociation of the reactants in the arc chamber, and the generated cations move toward the extraction slit along the electric field gradient.

5 is a perspective view of the spiral block filament 46 of FIG. 4.

The first and second conductive posts 52 and 54, one end is connected to the first conductive post, and a plurality of stages are connected to the second conductive post to form a spiral, and the dead volume portion is removed to form an arc chamber. The filament power supply unit 44 receives heat from the filament power supply unit 44 so as to prevent heat electron loss from being generated.

6A, 6B, and 6C illustrate distributions of temperature, electric potential, and electric gradient of the spiral block filament in which the dead volume portion is not removed and the spiral block filament in which the dead volume is removed. The figure shown.

Figure 6a is a view showing a state before the dead volume (dead volume) 56 removed,

6B is a view showing a state in which all the dead volume portions 56 are removed.

FIG. 6C is a view showing a state in which the dead volume portion 56 is removed in consideration of self-shielding.

It can be seen from FIG. 6B that when the dead volume portion 56 is removed, the region of the hot spiral block filament 46 where hot electrons are emitted is exposed to the strong potential gradient. This causes frequent micro glitch and adversely affects the productivity of ion implantation equipment.

FIG. 6C illustrates a case in which the spiral block filament 46 is optimized in consideration of self-shielding by the dead volume part 56, and the hot filament region is protected from a strong potential gradient. have.

The present invention extends the life of the spiral block filament 46 by minimizing the problem of high temperature warpage and the occurrence of glitch by the load while taking full advantage of the existing spiral block filament. First, in the existing spiral block filament (spiral block filament), as shown in Figure 6a there are a lot of dead volume (dead volume) 56, which does not act as a current path (dead volume) (dead volume) ( 56) serves to increase only the load of the spiral block filament 46 because the current density is low and thus does not contribute to hot electron emission by Joule heating. This shows an example of a spiral block filament 46 from which the dead volume 56 has been completely removed, and this spiral block filament 46 can reduce the load without degrading performance.

However, if the dead volume portion 56 of the spiral block filament 46 is removed as shown in FIG. 6B, the hot spiral block filament 46 in which hot electron emission occurs is directly exposed to a strong potential gradient caused by the arc chamber wall. As a result, the loss of hot electrons to the arc chamber wall occurs, causing micro glitch. Therefore, the spiral block filament 46 in which the dead volume portion has been removed to maintain the self-shielding effect by the dead volume portion 56 is shown in FIG. 6C. The spiral block filament 46 of FIG. 6C is precisely designed so as not to expose the strong potential purchase by the arc chamber wall while at the same time obtaining a load reduction effect.

As described above, the present invention eliminates the dead volume to maintain the self-shielding effect in the Bernas ion implantation device, thereby preventing the occurrence of hot electron loss to the wall of the arc chamber, thereby preventing the occurrence of micro glitches. In addition, there is an advantage that can minimize the high-temperature bending caused by the load.

Claims (6)

In the Bernas type ion implantation device,  External power, An arc power unit configured to receive the external power and generate arc power; A filament power supply unit for generating a filament power supply by receiving power supplied from the arc power supply unit; Spiral block filament is formed spirally and the dead volume portion is removed so that the thermal electron loss is not generated to the arc chamber wall is generated by receiving power from the filament power source; Bernas type ions which are installed on the opposite side of the spiral block filament and prevent the hot electrons accelerated by the arc power generated from the arc power supply unit to disappear into the chamber body without ionizing the discharge gas. Infusion device. The method of claim 1, The repeller is a Bernas-type ion implanter, characterized in that for generating a negative potential of -5V. The method according to claim 1 or 2, The spiral block filament has a structure in which the dead volume portion is removed in consideration of self-sealing. The method of claim 3, The spiral block filament prevents micro glitches by preventing thermal electron loss from the arc chamber to the wall. In the spiral block filament of the burner type ion implanter, The first and second conductive posts, one end is connected to the first conductive post, and a plurality of stages are connected to the second conductive post to form a spiral shape, and the dead volume portion is removed to prevent hot electron loss from occurring in the arc chamber wall. Spiral block filament of the Bernas type ion implantation device, characterized in that having a structure. The method of claim 5, The dead volume structure is the spiral block filament of the Bernas-type ion implantation device, characterized in that to prevent micro-glitch by preventing the loss of hot electrons from the arc chamber to the wall.

Images