An ion source device with adjustable plasma density

Abstract

The present invention relates to an ion source device with adjustable plasma density, belonging to the field of semiconductor equipment. A coil is wound around the outside of a discharge chamber of the ion source device with adjustable plasma density; a radio frequency module is connected to the coil; a gas duct is introduced into the ion source chamber and communicates with the discharge chamber; a grid is provided on the same-direction open end faces of the ion source chamber and the discharge chamber; the discharge chamber is composed of two large-diameter discharge chambers and a small-diameter discharge chamber of non-uniform diameters; the large-diameter discharge chamber and the small-diameter discharge chamber are communicated; one end face of the large-diameter discharge chamber is an open end face, and the open end face faces the grid. The present invention relates to an ion source device with adjustable plasma density, which can bombard the middle area and edge area of ​​a wafer independently and as a whole by using coils at different positions, so as to adjust the plasma density distribution of the discharge chamber and ensure etching uniformity.

Description

Technical Field

[0001] The invention relates to an ion source device with adjustable plasma density, belonging to the field of semiconductor equipment. Background Art

[0002] An ion source is a device that ionizes neutral atoms or molecules and draws out ion beams from them. It is an indispensable component of various types of ion accelerators, mass spectrometers, electromagnetic isotope separators, ion implanters, ion beam etching devices, ion thrusters, and neutral beam injectors in controlled fusion devices.

[0003] Radio frequency inductively coupled plasma (RFICP) sources have developed rapidly in recent years due to their simple structure, ability to produce high-density pure plasma, long service life, and good performance-price ratio. The RF ICP sources currently used are mainly cylindrical. The RF coil of the RF ICP source is wound around the outside of an electrically insulating quartz discharge chamber. When RF power is added to the coil through a matching network, RF current flows through the coil, thereby generating RF magnetic flux and inducing an RF electric field along the axial direction inside the discharge chamber. The electrons therein are accelerated by the electric field, thereby generating plasma, and the energy of the coil is coupled into the plasma.

[0004] The ion source chamber and the discharge chamber in the existing ion source device or ion source quartz chamber structure form a mutually nested structure, and the coil is arranged on the outer wall of the discharge chamber; because the RF ICP source is cylindrical, when the RF power is loaded on the RF coil, due to the skin effect of the current, the current mainly flows through the wall of the discharge chamber and gradually decays in the skin layer, so the plasma density in the discharge chamber generally shows a trend of high on both sides and low in the middle. Affected by the RF power and working pressure, the plasma density distribution in the discharge chamber will also show a saddle-shaped trend. Due to the uneven distribution of plasma density, the etching rate is uneven, which affects the etching uniformity. Summary of the invention

[0005] The present invention provides an ion source device with adjustable plasma density, which performs multi-stage adjustment on the plasma density and improves etching uniformity.

[0006] The present invention adopts the following technical solution:

[0007] The ion source device with adjustable plasma density of the present invention comprises an ion source chamber and a radio frequency module; a discharge chamber is arranged in the ion source chamber; a coil is wound around the outside of the discharge chamber; the radio frequency module is connected to the coil; an air intake pipe passes through the ion source chamber and is connected to the discharge chamber; a grid is arranged on the same-direction open end faces of the ion source chamber and the discharge chamber;

[0008] The discharge cavity is a convex cavity structure formed by combining a large-diameter discharge cavity and a small-diameter discharge cavity; the large-diameter discharge cavity and the small-diameter discharge cavity are connected and their central axes are consistent; one end face of the large-diameter discharge cavity is an open end face, and the open end face faces the grid.

[0009] In the ion source device with adjustable plasma density described in the present invention, the coil wound outside the discharge chamber includes coil one and coil two; coil one is wound around the closed bottom end surface of the large-diameter section discharge chamber; and coil two is wound around the outer peripheral wall of the small-diameter section discharge chamber.

[0010] In the ion source device with adjustable plasma density of the present invention, the winding diameter of the coil one is greater than the winding diameter of the coil two.

[0011] In the ion source device with adjustable plasma density described in the present invention, the coil 1 is a double-layer planar coil, and an axial gap L is provided between the coil 1 and the closed bottom end surface of the large-diameter section discharge chamber, wherein the axial gap L is 2 mm to 20 mm.

[0012] In the ion source device with adjustable plasma density of the present invention, the coil 2 is a double-layer spiral coil, and a radial gap R is provided between the coil 2 and the outer peripheral wall of the cylinder of the discharge chamber of the small diameter section, wherein the radial gap R is 2 mm to 20 mm.

[0013] In the ion source device with adjustable plasma density described in the present invention, the inner diameter of the discharge cavity of the small diameter section is 1 / 4 to 1 / 2 of the inner diameter of the discharge cavity of the large diameter section.

[0014] The ion source device with adjustable plasma density described in the present invention, the radio frequency module includes: a plurality of radio frequency columns, a radio frequency power supply and a radio frequency matcher arranged on the ion source chamber, the radio frequency power supply is connected to the radio frequency matcher, the radio frequency matcher is connected to the power distribution module, the power distribution module is respectively connected to coil one and coil two through the radio frequency columns; the power distribution module is used to allocate the power of coil one and coil two.

[0015] In the ion source device with adjustable plasma density described in the present invention, a plurality of the radio frequency columns are located at the closed end of the ion source chamber; and a plurality of the radio frequency columns penetrate the closed end of the ion source chamber.

[0016] In the ion source device with adjustable plasma density described in the present invention, the distribution ratio of the power distribution module is r=P1:P2; P1 is the radio frequency power entering coil one, P2 is the radio frequency power entering coil two, and the distribution ratio r=1:20~20:1.

[0017] In the ion source device with adjustable plasma density described in the present invention, the grid is provided with two layers, and the two layers of the grid are respectively connected to the input end of the filter through radio frequency columns, and the input end of the filter is connected to an AC power supply.

[0018] Beneficial Effects

[0019] The invention relates to an ion source device with adjustable plasma density, which can bombard the middle area and edge area of ​​a wafer independently and as a whole by using coils at different positions, so as to adjust the plasma density distribution of a discharge chamber and ensure etching uniformity.

[0020] The invention relates to an ion source device with adjustable plasma density. The small-diameter end coil of the discharge cavity is used alone or with high power distribution, and the plasma density distribution in the middle area can be adjusted, which is suitable for the situation where the middle plasma density is low.

[0021] The invention relates to an ion source device with adjustable plasma density. The large-diameter end coil of the discharge cavity is used alone or with high power distribution to adjust the plasma density distribution in the edge area, which is suitable for the situation of low edge plasma density. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the prior art structure;

[0023] Figure 2 It is a schematic diagram of the structure of the quartz chamber of the ion source in the prior art;

[0024] Figure 3 It is a schematic structural diagram of the ion source device of the present invention;

[0025] Figure 4 It is a three-dimensional schematic diagram of the discharge chamber structure in the present invention;

[0026] Figure 5 It is a schematic cross-sectional view of the discharge chamber structure in the present invention;

[0027] Figure 6 It is a schematic diagram of the three-dimensional structure of the coil winding of the present invention;

[0028] Figure 7 It is a schematic diagram of the three-dimensional structure of the coil winding and the discharge chamber of the present invention;

[0029] Figure 8 For the present invention Figure 7 Schematic diagram of the cross-sectional structure.

[0030] In the figure: grid one 1, grid two 2, discharge chamber 3, coil one 4, coil two 5, power distribution module 6, RF power supply 7, RF matcher 8, air inlet pipe 9, RF column one 12, RF column two 13, bottom end surface of ion source chamber 14, ion source chamber 15, AC power supply one 10, AC power supply two 101, RF column 121. DETAILED DESCRIPTION

[0031] In order to make the purpose and technical solution of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] like Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 As shown: an ion source device with adjustable plasma density, comprising an ion source chamber 15, a radio frequency module; a discharge chamber 3 in the ion source chamber 15, a coil wound on the outside of the discharge chamber 3; the radio frequency module is connected to the coil; an air intake pipe 9 is introduced into the ion source chamber 15 and communicated with the discharge chamber 3; a grid is provided on the same-direction end face of the ion source chamber 15 and the discharge chamber 3; the grid is provided with two layers, namely, grid 1 1 and grid 2 2, and the two layers of grids are respectively connected to the input end of the filter through radio frequency columns, and the input end of the filter is connected to the AC power supply. The advantages of this scheme are: the discharge chamber 3 is a convex cavity structure formed by the combination of a large-diameter discharge chamber and a small-diameter discharge chamber; the large-diameter discharge chamber and the small-diameter discharge chamber are communicated and the central axis is consistent; one end face of the large-diameter discharge chamber is an open end face, and one end face of the large-diameter discharge chamber faces the grid 1 1 and the grid 2 2. The large-diameter discharge chamber and the small-diameter discharge chamber can be bombarded on the wafer surface in different areas, ensuring the uniformity of the bombardment and the uniformity of etching.

[0033] A plurality of radio frequency columns 121 are arranged on the bottom end surface 14 of the ion source chamber, the radio frequency power supply is connected to the radio frequency matcher, the radio frequency matcher 8 is connected to the power distribution module 6, and the power distribution module is connected to the coil 1 4 and the coil 2 5 through the radio frequency column; the radio frequency column is divided into radio frequency column 12, radio frequency column 2 13, and radio frequency column 3 121; radio frequency column 12 is connected to coil 1 4, radio frequency column 2 13 is connected to coil 2 5, and the power distribution module 6 adjusts the power of coil 1 4 and coil 2 5 through radio frequency column 12 and radio frequency column 2 13. The outer winding coil of the discharge cavity is composed of coil 1 4 and coil 2 5; coil 1 4 is wound at the bottom end of the large diameter section discharge cavity; coil 2 5 is wound at the outer peripheral wall of the small diameter section discharge cavity. Coil 1 4 is a double-layer planar coil, and there is an axial gap L between coil 1 4 and the bottom of the large diameter section discharge cavity, and the axial gap L is 2mm~20mm. The coil 2 5 is a double-layer spiral coil, and there is a radial gap R between the coil 2 5 and the outer peripheral wall of the cylinder of the small-diameter section discharge cavity, and the radial gap R is 2mm~20mm. The radio frequency module is composed of a power distribution module 6, a radio frequency power supply 7, and a radio frequency matching device 8;

[0034] Several radio frequency columns, radio frequency power supply 7 and radio frequency matching device 8 are arranged on the ion source chamber 15. Radio frequency power supply 7 is connected to radio frequency matching device 8, radio frequency matching device 8 is connected to power distribution module 6, and power distribution module 6 is connected to coil 1 4 and coil 2 5 respectively through radio frequency columns; power distribution module 6 is used to allocate the power of coil 1 4 and coil 2 5. The advantages of this scheme are: by connecting other control modules respectively through several independent radio frequency columns, a sub-control system is established, and different components can be controlled independently. If a fault occurs, they can be replaced or repaired separately, which reduces maintenance time and reduces operating costs.

[0035] The power distribution module 6 can distribute the RF power entering the coil 1 4 and the coil 2 5, and adjust the distribution rate r to adjust the plasma density distribution in the discharge chamber; wherein, the distribution rate r=P1:P2, P1 is the RF power entering the coil 1, P2 is the RF power entering the coil 2, and the distribution rate r=1:20~20:1. The advantages of this scheme are: the coil 1 4 and the coil 2 5 are set with different powers through the power distribution module 6, and in the actual processing technology, the ion density can be regulated. The large-diameter end coil of the discharge chamber is used alone or allocated with high power, and the plasma density distribution in the edge area can be adjusted, which is suitable for the situation where the edge plasma density is low, and further ensures the uniformity of the ion bombardment area and the corrosion uniformity.

[0036] In the above scheme, coil 1 4 and coil 2 5 are spiral coils and planar coils, the discharge chamber adopts a two-stage structure, and different power loading is performed on the two coils to correct the plasma density in the discharge chamber so that the plasma density in the discharge chamber tends to be uniform, which is beneficial to improving the etching uniformity.

[0037] As a preferred solution of the ion source device with adjustable plasma density described in the present invention, the inner diameter of the small diameter section discharge cavity is 1 / 4 to 1 / 2 of the inner diameter of the large diameter section discharge cavity. The small diameter section discharge cavity is adjusted proportionally based on the size of the large diameter section discharge cavity, which meets the etching process requirements and is easy to process and shape.

[0038] Based on the ion source device with adjustable plasma density provided by the present invention, its processing technology is as follows:

[0039] When etching is required, start AC power supply 10, AC power supply 2 101, filter 11, filter 111; start AC power supply 10, AC power supply 2 101 and connect to filter 11, filter 111 respectively; filter 11, filter 111 are connected to grid 1 1 and grid 2 2 through independent RF column 3 121;

[0040] Ar, The plasma gas enters the discharge chamber 3 through the air inlet pipe 9, and the gas in the discharge chamber 3 is ionized to generate plasma under the action of the coil 1 4 and the coil 2 5. The plasma in the discharge chamber 3 is led out through the grid 1 1 and the grid 2 2, and bombards the target material in the form of an ion beam to etch the wafer.

[0041] Outside the skin depth, the plasma density gradually decays. Experiments have shown that when the discharge cavity is large, the spiral coil has little effect on adjusting the plasma density in the middle area, and the plasma density is difficult to adjust evenly. The planar coil has a good effect on density adjustment in the central area. Therefore, a two-stage discharge cavity is used, with a spiral coil in the small diameter area and a planar coil in the large diameter area, which is more conducive to adjusting the plasma density and making the plasma density distribution uniform.

[0042] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. An ion source device with adjustable plasma density, comprising an ion source chamber (15) and a radio frequency module; a discharge chamber (3) is provided in the ion source chamber (15); a coil is wound around the outside of the discharge chamber (3); the radio frequency module is connected to the coil; an air intake pipe (9) passes through the ion source chamber (15) and is connected to the discharge chamber (3); grids are provided on the same-direction open end surfaces of the ion source chamber (15) and the discharge chamber (3); the characteristics are as follows: The discharge cavity (3) is a convex cavity structure formed by combining a large-diameter discharge cavity and a small-diameter discharge cavity; the large-diameter discharge cavity and the small-diameter discharge cavity are connected and their central axes are consistent; one end face of the large-diameter discharge cavity is an open end face, and the open end face faces the grid; The outer winding coil of the discharge chamber comprises a coil 1 (4) and a coil 2 (5); the coil 1 (4) is wound around the closed bottom end surface of the large-diameter section discharge chamber; the coil 2 (5) is wound around the outer peripheral wall of the small-diameter section discharge chamber; The inner diameter of the small-diameter section discharge cavity is 1 / 4 to 1 / 2 of the inner diameter of the large-diameter section discharge cavity; The radio frequency module comprises: a plurality of radio frequency columns, a radio frequency power supply (7) and a radio frequency matcher (8) arranged on an ion source chamber (15); the radio frequency power supply (7) is connected to the radio frequency matcher (8); the radio frequency matcher (8) is connected to a power distribution module (6); the power distribution module (6) is respectively connected to the coil 1 (4) and the coil 2 (5) through the radio frequency columns; the power distribution module (6) is used to adjust the power of the coil 1 (4) and the coil 2 (5); A plurality of the radio frequency columns are located at the closed end of the ion source chamber (15); and a plurality of the radio frequency columns penetrate the closed end of the ion source chamber (15).

2. The ion source device with adjustable plasma density according to claim 1, characterized in that: The winding diameter of the coil one (4) is greater than the winding diameter of the coil two (5).

3. The ion source device with adjustable plasma density according to claim 1, characterized in that: The coil 1 (4) is a double-layer planar coil, and an axial gap L is provided between the coil 1 (4) and the closed bottom end surface of the large-diameter section discharge cavity, wherein the axial gap L is 2 mm to 20 mm.

4. The ion source device with adjustable plasma density according to claim 1, characterized in that: The coil 2 (5) is a double-layer spiral coil, and a radial gap R is provided between the coil 2 (5) and the outer peripheral wall of the cylinder body of the discharge chamber of the small diameter section, wherein the radial gap R is 2 mm to 20 mm.

5. The ion source device with adjustable plasma density according to claim 1, characterized in that: The distribution ratio of the power distribution module (6) is r=P1:P2; P1 is the radio frequency power entering the coil one (4), and P2 is the radio frequency power entering the coil two (5), and the distribution ratio r=1:20~20:

1.

6. The ion source device with adjustable plasma density according to claim 1, characterized in that: The grid is provided with two layers, and the two layers of the grid are respectively connected to the input end of the filter through radio frequency columns, and the input end of the filter is connected to an AC power supply.

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