CN221352687U - Mass analysis magnet system - Google Patents

Abstract

The utility model relates to the field of ion implanters and discloses a mass analysis magnet system, which comprises an arc-shaped supporting cylinder, a first magnetic yoke and a first coil formed by 2n arc-shaped saddle windings, wherein the first magnetic yoke is sleeved on the periphery of the first coil; the 2n arc saddle windings are divided into two groups, the n windings of each group are sequentially reduced in size, two groups of windings are symmetrically arranged on the arc supporting cylinder to form two poles of the two-pole deflection magnet, two sides of the largest one of the windings are close to the symmetrical surface of the arc supporting cylinder, other windings of the group are sequentially arranged in the range of the largest one from large to small, the current of single-turn wires in each winding is the same in size, and the current density of each group of windings is distributed in an approximate cosine law along the circumferential angle of the cross section of the first coil in a mode of arranging wires with different turns for the windings in different positions. The two-pole deflection magnet can provide a highly uniform deflection magnetic field, thereby realizing high quality resolution, and the system has simple and compact structure.

Description

Mass analysis magnet system

Technical Field

The present utility model relates to a mass analysis magnet system for removing impurity ions in an ion beam extracted from an ion source in the field of ion implantation.

Background

The ion beam exiting the ion source typically contains one or more unwanted impurity ions, which are now standard practice to separate from the ion beam using a mass analysis magnet system to produce a highly pure ion beam of the desired doping, using a difference in ion mass to charge ratio. Such a mass spectrometry magnet system requires a magnetic field of high uniformity because the ion beam is deflected and separated with high accuracy.

For large-size, large-divergence angle ribbon beams extracted from an ion source, the analyzing magnet is required to have a pole gap sufficient to accommodate the large-size ribbon beam on the one hand, and to provide a suitable and uniform magnetic field across the ribbon beam size on the other hand. In the prior art, mass analysis magnet systems meeting this requirement have become difficult and expensive, bulky and difficult to meet magnetic field quality requirements.

Disclosure of utility model

In view of the above technical problems, the present utility model firstly provides a mass analysis magnet system capable of generating a highly uniform magnetic field.

The technical scheme adopted by the utility model is as follows: the mass analysis magnet system is a two-pole deflection magnet and comprises an arc-shaped supporting cylinder, a first magnet yoke and a first coil formed by 2n arc-shaped saddle windings, wherein the first magnet yoke is sleeved on the periphery of the first coil;

The 2n arc saddle windings are divided into two groups, the n windings of each group are sequentially reduced in size, the two groups of windings are symmetrically arranged on the arc supporting cylinder to form two poles of the two-pole deflection magnet, two sides of the largest one of the windings are close to the symmetrical surface of the arc supporting cylinder, other windings of the group are sequentially arranged in the range of the largest one from large to small, the current of single-turn wires in each winding is the same in size, and the current density is distributed in an approximate cosine rule along the circumferential angle of the cross section of the first coil in a mode of arranging wires with different turns for windings in different positions. The n is more than or equal to 4, and n is more preferably more than or equal to 4 and less than or equal to 6.

The current density of the two-pole deflection magnet coil is distributed in an approximate cosine law, a highly uniform pure two-pole magnetic field can be generated, the magnetic field uniformity can reach 1 per mill, and the two-pole deflection magnet coil has a larger effective area under the condition of the same size.

As a priority: the windings of the two-pole deflection magnet are in series connection.

The first magnetic yoke is cylindrical and is formed by connecting two pieces.

The deflection angle of the two-pole deflection magnet is between 45 degrees and 180 degrees.

In order to meet the application scene of large-size and large-divergence angle ion beams led out by an ion source, the mass analysis magnet system is further improved, and the specific scheme is as follows:

A quadrupole focusing magnet for focusing the ribbon ion beam extracted from the ion source in the long side direction and defocusing the ribbon ion beam in the short side direction is added at the upstream of the dipole deflection magnet.

The two-pole deflection magnet and the four-pole focusing magnet are combined, and the focusing effect of the four-pole focusing magnet is utilized, so that the loss of target ions can be reduced, and the gap of the magnet can be greatly reduced, thereby ensuring that the system structure is simpler and more compact, being beneficial to simplifying the manufacturing process and reducing the production cost.

The quadrupole focusing magnet preferably has the following structure: the ion beam comprises a second magnetic yoke and a second coil formed by four saddle windings, wherein the second magnetic yoke is sleeved on the periphery of the second coil, the four saddle windings are mutually connected in series and circumferentially distributed along the periphery of a strip-shaped ion beam channel, and the saddle windings are respectively and centrally distributed in four quadrants of a rectangular coordinate system which takes the center of the ion beam channel as an origin, is parallel to the short axis direction of the strip-shaped ion beam as an X axis and takes the long axis direction as a Y axis as a cross section.

The cross section of the ribbon ion beam is rectangular and is divided into a long side and a short side, and the width of the air gap between the two-pole deflection magnet and the four-pole focusing magnet is slightly larger than the width of the long side of the ribbon ion beam.

As a priority scheme: the mass analysis magnet system further comprises an analysis slit which is arranged at the downstream of the two-pole deflection magnet and has adjustable position and slit width.

The windings are all formed by winding oxygen-free copper wires.

And the magnetic yokes are made of DT4 materials.

The beneficial effects of the utility model are as follows:

1) The current density of the two-pole deflection magnet coil is distributed in an approximate cosine law, and a highly uniform pure two-pole magnetic field can be generated, so that the current intensity uniformity and the angle uniformity of an ion beam are remarkably improved, ions with different mass-to-charge ratios can be spatially separated better, and the ions can smoothly pass through a downstream analysis slit without distortion, and further the system has higher mass resolution;

2) The two-pole deflection magnet has a simple structure and a larger effective area under the condition of the same size, so that the structure is more compact, and compared with the prior art, the two-pole deflection magnet is beneficial to reducing the volume of the magnet and reducing the processing difficulty and the production cost;

3) In order to solve the problems of large, expensive and difficult magnet system caused by the requirement of large-size and large-divergence angle ion beams on large magnetic pole gaps and magnetic field uniformity in the prior art, the utility model adopts a combination scheme of a two-pole deflection magnet and a four-pole focusing magnet, reduces the loss of target ions, simultaneously greatly reduces the gaps of the magnets, further ensures that the system structure is simple and compact, further simplifies the manufacturing process and reduces the production cost.

Drawings

FIG. 1 is a schematic perspective view of a two-pole deflection magnet;

FIG. 2 is a schematic cross-sectional view of a two-pole deflection magnet;

FIG. 3 is a schematic plan view of an ion implanter including an ion beam mass analysis magnet system of the present utility model;

fig. 4 is a schematic illustration of a profile in the direction of travel of a ribbon ion beam;

FIG. 5 is a schematic perspective view of a quadrupole focusing magnet of the present utility model;

FIG. 6 is a schematic diagram of a cross section I-I of a quadrupole focusing magnet.

Detailed Description

The utility model will be described in further detail with reference to specific embodiments and drawings.

Fig. 1 and 2 show the structure of a two-pole deflection magnet of a mass analysis magnet system of the present utility model. Fig. 1 is a partial view of the diode deflection magnet 5, and fig. 2 is a schematic cross-sectional view of the diode deflection magnet 5.

As shown in fig. 1 and 2, the two-pole deflection magnet 5 mainly comprises a ferromagnetic yoke 16 along the deflection path and a magnet coil consisting of a plurality of arcuate saddle windings 17-24, and in order to obtain a magnetic field that is as uniform as possible, while being as simple and reliable in terms of implementation process, the quantitative distribution of the coil windings needs to be calculated. In this embodiment, as shown in fig. 1, the windings 17, 18, 19, 20, 21, 22, 23 and 24 are divided into two groups, the size of 4 windings in each group is sequentially reduced, the two groups of windings are symmetrically arranged on the surface of the arc-shaped supporting cylinder a for supporting, two sides of the largest one of the windings are close to the symmetry plane of the arc-shaped supporting cylinder a, the other windings of the group are sequentially arranged in the range of the largest one from large to small, the current of the single-turn coils in the windings is the same, preferably, each winding is in a serial connection relationship, and the current density of each group of windings is approximately cosine-regularly distributed along the circumferential angle of the cross section of the magnet coil by arranging wires with different turns for the windings in different positions. As shown in fig. 2, the current direction of the coils 17a,18a,19a,20a,21a,22a,23a,24a is inward toward the paper surface, and the current direction of the coils 17b,18b,19b,20b,21b,22b,23b,24b is outward toward the paper surface.

According to the principle that the diode deflection magnet 5 can generate a pure diode magnetic field according to the cosine law distribution of current density, the cosine law distribution of current density is approximately realized by arranging wires with different turns at 16 different theta positions (shown in how 2), wherein theta refers to an angle of anticlockwise rotation around a z axis by taking an x axis as a starting axis.

In this embodiment, the monopole in the two-pole deflection magnet 5 is composed of 4 windings, the 4 windings occupy 180 °, which is equivalent to that each winding has 22.5 ° on average on one side, and the distribution of winding turns is calculated as follows:

Where N _i represents the proportionality coefficient of the number of turns of the ith winding coil, the total number of turns N can be determined by ampere's loop law, and the corresponding number of winding coil turns is n×n _i. The specific winding method is recommended as follows: the method comprises the steps of arranging a fixed block and a positioning block on the surface of a stainless steel arc-shaped supporting cylinder a according to a set winding track, then winding each winding such as windings 17, 18, 19 and 20 according to respective turn number requirements, fixing the winding at corresponding positions on the surface of the cylinder a as shown in fig. 1, and finally connecting two ends of each winding in series as shown in fig. 2.

The magnetic field provided by the two-pole deflection magnet 5 is perpendicular to the bending plane of the passing ion beam, and is used for deflecting the ion beam along a certain curvature radius, wherein the deflection angle can be between 45 degrees and 180 degrees, and is 90 degrees in the embodiment. Compared with the prior art, the magnetic field device has the characteristics that the magnetic field device can provide a highly uniform deflection magnetic field for the band-shaped ion beam envelope region, so that the flow intensity uniformity and the angle uniformity of the ion beam are remarkably improved, ions with different mass-to-charge ratios can be subjected to better spatial separation and smoothly pass through an analysis slit at the downstream without distortion, the system further shows higher mass resolution, and based on the magnetic field device, the magnetic field device has the advantages of larger effective magnetic field region under the condition of the same size, and the mass analysis magnet system structure is more compact, so that the volume of the magnet system is reduced, and the processing difficulty and the production cost are reduced.

For ion implantation of larger photovoltaic panels and display screens, a mass analysis magnet system is generally required to meet the application scene of large-size and large-divergence-angle ion beams led out by an ion source, and the following improvement scheme can be adopted for the ion implantation.

Fig. 3 is a schematic diagram of some basic components of an ion implanter. In fig. 3, a ribbon ion beam 2 of a predetermined energy from an ion source 1 enters a quadrupole focusing magnet 3 and a dipole deflection magnet 5 in sequence, in which a vacuum ion beam passageway 4 is provided, the passageway 4 providing a curved path of the ion beam 2 and defining a curved trajectory of the ion beam.

The quadrupole focusing magnet 3 is used to provide a uniform quadrupole magnetic field perpendicular to the ion beam passing through. The ion beam extracted from the ion source 1 has a large size and a large divergence angle, and the quadrupole magnet 3 is used for providing a longitudinal focusing and a transverse defocusing for the ion beam 2 so as to reduce the expansion of the ion beam in the long-side direction, so that the magnetic pole gap of the rear required diode deflection magnet 5 is greatly reduced, and the transverse defocusing is equivalent to compensating for the transverse focusing of the ion beam by the rear diode deflection magnet 5, so that the ion beam coming out of the diode deflection magnet 5 can be prevented from being excessively focused.

The ion beam focused by the quadrupole focusing magnet 3 passes through the dipole deflection magnet 5 along a curved path, and for ions of different mass to charge ratios led out from the ion source, the deflection magnet effectively spatially separates the ions of different mass to charge ratios after leaving the dipole deflection magnet 5. And then collimated by the mass analysis slit 6 and target ions are selected to pass through the slit into the post-processing chamber 9. In the post-processing chamber 9, a target ion beam 7 is implanted onto a substrate 8 to be processed.

Wherein the position of the analysis slit 6 and the slit width are adjustable for precise control and real-time adjustment of ion beam density, ion beam uniformity and mass resolution.

Fig. 4 is a cross-sectional profile view of the ion beam 7, and the ion beam 7 is ribbon-shaped and rectangular, and has a long dimension L and a short dimension w of the cross-sectional profile. The long dimension of the ribbon beam is perpendicular to the plane of the bend, i.e., perpendicular to the plane of the paper in fig. 1. The vacuum channel 4 is of a size sufficient to accommodate the envelope dimensions during the travel of the ion beam; the air gap spacing of the magnets 3, 5 should also be large enough to accommodate the ribbon beam passing through. The deflection magnetic field should be highly uniform within the long dimension L of the ribbon ion beam so that the target ions within the long dimension are all subjected to the same deflection force; in addition, the magnetic field needs to be sufficiently uniform over a range in the short dimension direction perpendicular to the deflection path to simultaneously maintain the stability and uniformity of the target ion beam in the long and short dimension directions.

Fig. 5 shows a quadrupole magnet structure of the utility model, which consists of four saddle windings 12-15, a cylindrical magnet yoke 11 and a stainless steel cylinder in the middle for supporting, wherein the windings are fixed on the inner side of the magnet yoke through a fixed block, are integrally sleeved on the stainless steel cylinder in the middle, and are electrically connected in series. FIG. 6 is a view along section line I-I in FIG. 1. The cross-sectional schematic view of the quadrupole magnets is taken, the current direction in the conductors 12a,13a,14a,15a is inward toward the paper surface, the current direction in the conductors 12b,13b,14b,15b is outward toward the paper surface (12 a, 12b are two sides of the coil winding 12, and so on); the magnet structure is symmetrical along the x-axis and the y-axis respectively, and the arrangement angle alpha of the wires is optimized and calculated in order to obtain a uniform quadrupole field.

The windings in the above embodiments are all wound from oxygen free copper wire.

The number of windings in the above embodiment can be adjusted in real time according to the magnet aperture.

The cylindrical iron magnetic yoke is used outside the two-pole deflection magnet and the four-pole focusing magnet, and the ferromagnetic yoke has two purposes, namely, collecting the magnetic field outside the coil, and enhancing the magnetic field inside the aperture of the coil and improving the magnetic field uniformity in the aperture; the magnetic yoke is made of DT4 material and is formed by combining an upper half and a lower half.

The improvement scheme has the advantages that: the initial focusing of the quadrupole focusing magnet to the ions in the improved scheme can process large-size and highly divergent ion beams led out by an ion source, and can effectively reduce transmission pores required by the ions, so that the system has simple and compact structure; in addition, by utilizing the characteristic that the dipolar deflection magnet can provide a highly uniform deflection magnetic field (the magnetic field uniformity can reach 1 per mill), the high-quality resolution, the high ion beam injection (dosage and angle) uniformity and lower ion loss of the system are realized, and high-purity wide-width ion beams with the widths of 300 mm and 500 mm and the thicknesses of 40mm and 80mm are generated.

The foregoing examples are only for illustrating some embodiments of the present utility model, wherein the structures, connection modes, manufacturing processes, etc. of the components may be changed, and all equivalent changes, modifications, or improvements made on the basis of the present utility model should not be excluded from the protection scope of the present utility model.

Claims (9)

1. A mass analysis magnet system is characterized in that the mass analysis magnet system is a two-pole deflection magnet and comprises an arc-shaped supporting cylinder, a first magnet yoke and a first coil formed by 2n arc-shaped saddle windings, wherein n is more than or equal to 4, and the first magnet yoke is sleeved on the periphery of the first coil;

The 2n arc saddle windings are divided into two groups, the n windings of each group are sequentially reduced in size, the two groups of windings are symmetrically arranged on the arc supporting cylinder to form two poles of the two-pole deflection magnet, two sides of the largest one of the windings are close to the symmetrical surface of the arc supporting cylinder, other windings of the group are sequentially arranged in the range of the largest one from large to small, the current of single-turn wires in each winding is the same in size, and the current density is distributed in an approximate cosine rule along the circumferential angle of the cross section of the first coil in a mode of arranging wires with different turns for windings in different positions.

2. The mass analysis magnet system of claim 1, wherein each of the windings of the diode deflection magnet are in a series relationship.

3. The mass analysis magnet system according to claim 1, wherein the first yoke is cylindrical and is formed by connecting two pieces.

4. The mass analysis magnet system of claim 1, wherein the deflection angle of the two-pole deflection magnet is between 45 degrees and 180 degrees.

5. The mass analysis magnet system according to any one of claims 1 to 4, wherein a quadrupole focusing magnet for focusing a ribbon-shaped ion beam extracted from the ion source in a long side direction and defocusing the ribbon-shaped ion beam in a short side direction is added upstream of the dipole deflection magnet.

6. The mass analysis magnet system according to claim 5, wherein the quadrupole focusing magnet has the following structure: the ion beam comprises a second magnetic yoke and a second coil formed by four saddle windings, wherein the second magnetic yoke is sleeved on the periphery of the second coil, the four saddle windings are mutually connected in series and circumferentially distributed along the periphery of a strip-shaped ion beam channel, and the saddle windings are respectively and centrally distributed in four quadrants of a rectangular coordinate system which takes the center of the ion beam channel as an origin, is parallel to the short axis direction of the strip-shaped ion beam as an X axis and takes the long axis direction as a Y axis as a cross section.

7. The mass analysis magnet system of claim 6, further comprising an analysis slot disposed downstream of the diode deflection magnet and having an adjustable position and slot width.

8. The mass analysis magnet system according to claim 7, wherein the windings are each wound from oxygen-free copper wire.

9. The mass analysis magnet system according to claim 7, wherein the yokes are each made of DT4 material.