TWI805126B - A system for controlling a plasma density and a method thereof - Google Patents

Abstract

The present application discloses a system for controlling a plasma density and a method thereof, including an ion source, a reaction chamber, a baffle mechanism, and a faraday cup group. The faraday cup group is arranged on a wall surface of the reaction chamber corresponding to a screen grid and includes a faraday cup mounting frame and at least N Faraday cups. The N faraday cups correspond to positions of N groups of the screen grid ring holes on the screen grid. The baffle mechanism includes a drive-device controller and at least two groups of baffle assemblies. Each group of the baffle assemblies includes a plurality of baffles and a baffle driving device. The plurality of baffles are evenly arranged in a circumferential direction of one end of a discharge chamber, and each baffle is rotatably extendable into the discharge chamber to block plasma entering a screen gird ring hole. Baffles between the baffle assemblies are alternately arranged, and the baffles between the baffle assemblies are in different shapes. The present application can measure a density of ion beams emitted by the ion source and control the plasma density in real time, thereby effectively solving the problem of uneven etching caused by changes in process conditions, and reducing production costs.

Description

Plasma Density Control System and Method

The invention relates to the field of ion beam etching, and in particular to a plasma density control system and method.

related application

This application claims the priority of the Chinese patent application with the application number 202110002170.3 and the application title "A Plasma Density Control System and Method" filed with the China Patent Office on January 4, 2021, the entire contents of which are incorporated by reference in this application middle.

Ion beam etching can be used for etching various metals (Ni nickel, Cu copper, Au gold, Al aluminum, Pb lead, Pt platinum, Ti titanium, etc.) and their alloys, as well as non-metals, oxides, nitrides, carbides, Materials such as semiconductors, polymers, ceramics, infrared and superconductivity. The principle is to use the principle of glow discharge to decompose argon gas into argon ions, and the argon ions are accelerated by the anode electric field to physically bombard the surface of the sample to achieve the effect of etching. The etching process is to fill the Argon gas into the discharge chamber of the ion source and ionize it to form a plasma, then the ions are drawn out and accelerated by the grid in a beam shape, and the ion beam with a certain energy enters the working chamber and shoots to the solid surface to bombard the solid surface atoms, making the material atoms Sputtering is used to achieve the purpose of etching, which is pure physical etching. Since the ions are not generated by glow discharge, but are emitted by an independent ion source, the inert gas ions are accelerated by an electric field and then enter the vacuum chamber where the sample is placed. The vacuum degrees of the ion beam source and the sample chamber can reach their respective optimal levels. State, the purity of the membrane is very high.

Ion sources are devices that ionize neutral atoms or molecules and extract ion beams from them. Existing ion sources mainly include Kaufmann ion sources, radio frequency ion sources, Electron Cyclotron Resonance (ECR) ion sources and Hall The gridless (End Hall) ion source, in which the radio frequency ion source is in a vacuum environment, the gas filled with the vacuum chamber is ionized through the interaction of the electric field and the magnetic field, and the ions are released through the action of the electric field and the magnetic field. Plasma is generated by induction, and ions are accelerated by static electricity. It has the characteristics of stepless discharge, long-term stability, large uniform area, precise control of ion beam density, and low pollution. It is widely used in ion beam etching.

In ion beam etching, when the ion source is working, due to the different process conditions, there are great differences in the etching results. Under the excitation of radio frequency power, the plasma density in the discharge chamber is high in the middle and low at the edge. Trend (see Figure 1), in order to ensure the uniformity of etching, the size of the small holes on the screen gradually increases from the middle to the edge, so as to ensure that the ion flux passing through the edge area is large (see Figure 2 and Figure 3), so that the extracted ion beam The density is evenly distributed, but when the process conditions change, the ion beam current density edge area extracted by the ion source will increase (see Figure 4), resulting in uneven etching of the wafer surface (see Figure 5(a)-5(b) ), affecting the etching effect. In FIG. 3 , the abscissa is the radial distance, and the ordinate is the size of the aperture of the Grid (grid), that is, the size of the annular hole of the screen.

Each exemplary embodiment of the present application provides a plasma density control system. The plasma density control system and method can measure the density of the ion beam drawn out by the ion source, and control the plasma density in real time, effectively solving the problem caused by changes in process conditions. The problem of uneven etching is caused, and the production cost is reduced.

Various exemplary embodiments of the present application provide a plasma density control system, including a reaction chamber; an ion source, including: an ion source chamber and a discharge chamber coaxially arranged from outside to inside; and a screen grid, the screen grid is arranged on the The tail end of the ion source cavity is provided with N groups of screen ring-shaped holes in the radial direction on the screen, wherein N is an integer and greater than or equal to 1; the Faraday cup set includes: a Faraday cup mounting frame, set On the wall of the reaction chamber directly corresponding to the screen grid; and at least N Faraday cups, the N Faraday cups correspond to the positions of the N groups of screen grid ring holes; and a shutter mechanism, It includes: a drive device controller and at least two sets of blanking components. Each shutter assembly includes a plurality of shutters and a shutter driving device. A plurality of baffles are evenly arranged along the circumference of the tail end of the discharge cavity. Each baffle can be driven by the baffle driving device to rotate and extend into the discharge chamber to block the plasma entering the corresponding screen grid annular hole. The baffles between the baffle components are arranged alternately, and the shapes of the baffles between the baffle assemblies are different. All shutter drives and all Faraday cups are connected to the drive controller. In one embodiment, the Faraday cup mounting frame is a straight frame, and the number of Faraday cups is N+1. One of the Faraday cups is located on the central axis of the reaction chamber, and the remaining N Faraday cups are collinearly installed on the straight bar frame and correspond to the positions of the N ring-shaped holes of the screen.

In one embodiment, the Faraday cup mount has an L-shaped frame, the corners of which are located on the central axis of the reaction chamber. One of the Faraday cups is installed on the corner of the L-shaped frame, and N Faraday cups are respectively installed on the two right-angle sides of the L-shaped frame. The 2N Faraday cups are located at different radial positions of the screen grid, and respectively correspond to the positions of the N screen grid annular holes.

In one embodiment, the shutter mechanism includes two groups of shutter assemblies, namely a first shutter assembly and a second shutter assembly. The first shutter assembly includes a plurality of first shutters and a first shutter driving device. The second shutter assembly includes a plurality of second shutters and a second shutter driving device. The cross-section of each first blocking plate is an inverted cone or an inverted trapezoidal structure with a wide center and narrow edges. The cross-section of each second blocking sheet is a tapered or trapezoidal structure with wide edges and narrow center.

In one embodiment, the discharge chamber is installed on the ion source chamber of the ion source through the discharge chamber support base. The edge ends of each first blocking sheet and each second blocking sheet are rotatably mounted on the end surface of the supporting seat of the discharge chamber.

In one embodiment, the lengths of each first blocking piece and each second blocking piece are the same, and the lengths of each first blocking piece and each second blocking piece are the same, which are 1/4r~1/2r; Among them, r is the radius of the screen grid.

In one embodiment, the shutter driving device is a rotary cylinder or a motor.

Each exemplary embodiment of the present application also provides a plasma density control method, including the following steps.

Step 1, detecting the plasma signal: wherein, before etching, the ion source is turned on, and the plasma in the discharge chamber is focused to form an ion beam after passing through the circular hole of the screen grid. A Faraday cup will detect the plasma signal at its own radial position. The detected plasma signal is converted into a current signal and fed back to the controller of the drive device.

Step 2, judging the uniformity of plasma density: Among them, the controller of the driving device reads the maximum current and the minimum current according to all the current messages received, and compares the maximum current with the minimum current. When the difference between the maximum current and the minimum current When the value is less than the set value, it is judged that the plasma density in the reaction chamber is uniform. Otherwise, it is judged that the plasma density is not uniform.

Step 3, controlling the plasma density, specifically includes the following steps.

Step 31 , determining the blocking opportunity: wherein, when it is determined in step 2 that the plasma density is not uniform, the controller of the driving device simultaneously reads the position of the Faraday cup corresponding to the maximum current.

Step 32, shielding: wherein, the controller of the driving device determines the activated shutter assembly according to the position of the Faraday cup corresponding to the maximum current, rotates the shutter of the shutter assembly under the control of the shutter driving device, and adjusts the density of the plasma High areas are blocked. When the baffle rotates to the radial direction, the width corresponding to the maximum current Faraday cup is the largest.

Step 33, detect the plasma density again: wherein, while the blocker rotates to block, the Faraday cup detects the plasma density in real time, and the controller of the drive device judges the uniformity of the plasma density according to step 2 until the plasma density is uniform, and the blocker The slice stops spinning.

In step 32, the step of occlusion includes.

Step 32A, when the Faraday cup corresponding to the maximum current is located at the edge, the driving device controller controls the second shutter driving device to drive the second shutter to shield.

Step 32, when the maximum current corresponds to the Faraday cup near the inner center , the driving device controller controls the first shutter driving device to drive the first shutter to block.

In step 33, when the edge plasma density is still maximum and the uniformity of the plasma density is determined to be uneven after the second shutter driving device rotates 90°, the driving device controller will control the first shutter driving device to move to Mask more edge plasma until the plasma density is uniform.

This application uses a Faraday cup set to measure the ion beam density drawn from the ion source, and controls the plasma density in real time through the rotation of the baffle in the baffle mechanism, effectively solving the problem of uneven etching caused by changes in process conditions, and Reduce production costs.

1: ion source

2: Reaction chamber

3: Faraday Cup Group

31: Faraday Cup

4: Bottom electrode

5: Wafer

6: Baffle

61: Baffle driving device

7: Drive controller

71: The first block drive device

72: The second shutter driving device

81: The first block

82:Second block

9: Discharge chamber support seat

11: discharge cavity

12: screen grid

13: Acceleration grid

14: Ion source controller

Fig. 1 shows a schematic diagram of plasma density distribution in a discharge chamber in the prior art.

Fig. 2 shows a schematic structural diagram of a screen grid in the prior art.

Fig. 3 shows a schematic diagram of the radial distribution positions of the screen grid annular holes in the prior art.

Fig. 4 shows a schematic diagram of the density distribution of ion beams in the reaction chamber in the prior art.

5(a) and 5(b) show two effect diagrams of wafer surface etching non-uniformity in the prior art.

Fig. 6 shows a schematic structural diagram of a plasma density control system according to an embodiment of the present application.

Fig. 7 shows a schematic diagram of the installation position of the baffle assembly in a plasma density control system according to an embodiment of the present application.

FIG. 8 shows a schematic structural diagram of a straight bar-shaped mounting frame for the middle Faraday cup according to an embodiment of the present application.

FIG. 9 shows a schematic structural diagram of a middle Faraday cup mounting frame in an L-shaped frame according to an embodiment of the present application.

Fig. 10 shows a schematic diagram of the distribution of the middle blocking pieces according to an embodiment of the present application.

Fig. 11 shows a schematic structural view of the first blocking sheet when rotating and blocking according to an embodiment of the present application.

Fig. 12 shows a schematic structural view of the second blocking sheet when rotating and blocking according to an embodiment of the present application.

Fig. 13 shows a schematic diagram of the structure of the second shutter for main blocking and the first shutter for auxiliary blocking according to an embodiment of the present application.

The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. The attached drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to these attached drawings without creative efforts. The embodiments described below are some of the embodiments of the present application, but not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts belong to the protection of this application. range of protection.

It should be understood that the terms "comprising" and "comprising" used in the specification and claims of the present application indicate the presence of described features, integers, steps, operations, elements and/or components, but do not exclude one or more other Presence or addition of features, integers, steps, operations, elements, components and/or collections thereof.

In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "left side", "right side", "upper", "lower" etc. is based on the orientation or positional relationship shown in the drawings, and is only for convenience describe the application and simplify the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and "first", "second", etc. do not indicate the degree of importance of parts , and therefore cannot be construed as limiting the application. The specific dimensions used in this embodiment are only for illustrating the technical solution, and do not limit the scope of protection of the present application.

At present, there are two traditional methods to obtain good beam density uniformity, one is to adjust the parameters and design structure of the ion source; the other is to establish a special-shaped physical shielding mechanism between the ion source etching samples, and continuously adjust the physical shielding mechanism The geometric shape of the ion beam is offset with the ion beam density characteristics. After each shielding device is designed, the uniformity needs to be tested. If the correction effect is not achieved, the geometric shape of the physical shielding device will be processed in a targeted manner. The test period is long , high production cost. Therefore, it is very necessary to measure the ion beam density drawn from the ion source and to control the plasma density in real time. The present application proposes a plasma density control system, which can effectively solve the above-mentioned problem of uneven etching caused by changes in process conditions, and reduce production costs.

The present application will be further described in detail below in conjunction with the accompanying drawings and specific preferred embodiments.

As shown in FIG. 6 , a plasma density control system includes an ion source 1 , a reaction chamber 2 , a baffle mechanism, a baffle 6 and a Faraday cup set 3 .

The ion source 1 is coaxially arranged on one side of the reaction chamber 2 , and the ion source 1 includes an ion source controller 14 , and an ion source chamber and a discharge chamber 11 coaxially arranged from outside to inside.

The ion source controller 14 is used to control the process parameters of the ion source.

In one embodiment, the discharge chamber 11 is installed on the inner wall of the ion source chamber through the discharge chamber support base 9 .

A Grid grid assembly is arranged at the end of the ion source cavity, and the Grid assembly includes a screen grid 12 and an acceleration grid 13 .

Both the screen grid 12 and the acceleration grid 13 are arranged with N groups of screen ring-shaped holes along the radial direction. In order to ensure the uniformity of etching, the radial height of the ring holes of the N groups of screen grids gradually increases from the middle to the edge, so as to ensure a large ion flux passing through the edge area, as shown in Figure 8. In Fig. 8, N=6, the radial heights of the annular holes of the six groups of screen grids are 2.35mm, 2.47mm, 2.63mm, 2.72mm, 2.91mm and 3.13mm respectively from the middle to the edge. The screen grid 12 is charged with positive electricity to focus the plasma, and the acceleration grid 13 is charged with negative electricity to extract and accelerate ions in the form of beams, and the plasma is extracted in the form of ion beams.

The baffle 6 is installed at the head of the reaction chamber located downstream of the Grid assembly, and is used to block N sets of screen grid annular holes. A lower electrode 4 for placing a wafer 5 is provided in the reaction chamber 2 .

The shutter mechanism includes a drive device controller 7 and at least two groups of shutter assemblies.

Each shutter assembly includes a plurality of shutters and a shutter driving device. A plurality of baffles are evenly arranged along the circumferential direction of the tail end of the discharge cavity. Each baffle can be driven by the baffle driving device to rotate and extend into the discharge chamber 11 to block the plasma entering the annular hole of the screen grid. The baffles between the baffle components are arranged alternately, and the shapes of the baffles between the baffle components are different.

In an embodiment, there are preferably two groups of shutter assemblies, namely a first shutter assembly and a second shutter assembly.

The first flap assembly includes a plurality of first flaps 81 and a first flap driving device 71 .

As shown in FIG. 10 , the cross section of each first blocking piece 81 is preferably an inverted tapered or inverted trapezoidal structure with a wide center and narrow edges.

As shown in FIG. 7 , the edge end of the first blocking piece 81 is preferably rotatably mounted on the rear end of the discharge chamber support base through a hinge shaft.

As shown in Figure 12, each first blocking plate 81 can be rotated under the driving of the first blocking plate driving device 71, and the first blocking plate driving device 71 can be one or two, that is, the first blocking plate 81 can be Driven independently, there may also be one or more first barrier drive devices 71 driven synchronously.

The second shutter assembly includes a plurality of second shutters 82 and a second shutter driving device 72 . As shown in FIG. 10 , the cross section of each second blocking piece 82 is a tapered or trapezoidal structure with wide edges and narrow center. The edge end of the second blocking piece 82 is preferably rotatably mounted on the rear end of the discharge chamber support base 9 through a hinge shaft.

The above-mentioned first baffles 81 and second baffles 82 are arranged alternately along the circumferential direction at the tail end of the discharge chamber support base 9, which may be uniform or uneven.

Each first blocking piece 81 and each second blocking piece 82 have the same length, which is 1/4r˜1/2r, more preferably 1/3r; wherein, r is the radius of the screen grid.

The axial spacing L between each baffle and the screen grid 12 is preferably 1 mm to 10 mm; avoid the baffle being located in the sheath of the screen 12, causing damage to the ion source 1 device, and avoid large distances, causing plasma diffusion .

As shown in Figure 11, each second blocking plate 82 can be rotated under the drive of the second blocking plate driving device 72, and the second blocking plate driving device 72 can be one or two, that is, the second blocking plate 82 can Driven independently, there may also be one or more second shutter drive devices 72 driven synchronously.

Alternatively, there may be three groups, four groups, etc. of the shutter components.

The shutter driving device is preferably a rotary cylinder or a motor.

The Faraday cup set includes a Faraday cup mounting frame and at least N Faraday cups 31 .

The Faraday cup mounting frame is arranged on the wall of the reaction chamber corresponding to the screen grid. The N Faraday cups correspond to the positions of the N sets of screen grid annular holes.

In this application, the Faraday cup mounting frame has the following two preferred embodiments.

Embodiment 1: The Faraday cup mounting frame is a straight frame

The Faraday cup mounting frame is a straight frame, and the number of Faraday cups 31 is N+1. In this embodiment, since there are six groups of annular holes in the screen grid, that is, N=6, the number of Faraday cups is 7, as shown in Figure 8, from the center to the outside are Faraday cup 1 and Faraday cup 2 , Faraday Cup 3, Faraday Cup 4, Faraday Cup 5, Faraday Cup 6, and Faraday Cup 7.

One of the Faraday cups 31 (that is, the Faraday cup 1) is located on the central axis of the reaction chamber 2, and the remaining N Faraday cups 31 are collinearly installed on the straight bar frame, and are aligned with the positions of the N screen grid annular holes. correspond.

That is, Faraday cup 2, Faraday cup 3, Faraday cup 4, Faraday cup 5, Faraday cup 6 and Faraday cup 7 are respectively connected with the screen grid ring holes of 2.35mm, 2.47mm, 2.63mm, 2.72mm, 2.91mm and 3.13mm Correspondingly, it is ensured that the plasma densities in the regions of different apertures on the screen grid 12 can be effectively measured.

Example 2

As shown in FIG. 9 , the Faraday cup mounting frame has an L-shaped frame (which may be a cross-shaped frame), and the corners of the L-shaped frame are located on the central axis of the reaction chamber. The number of Faraday cups is preferably 2N+1.

One of the Faraday cups 31 (that is, the Faraday cup 1) is installed on the corner of the L-shaped frame, and N Faraday cups 31 are respectively installed on the two right-angled sides of the L-shaped frame.

The N Faraday cups 31 on one of the right-angled sides are respectively Faraday cup 2, Faraday cup 3, Faraday cup 4, Faraday cup 5, Faraday cup 6 and Faraday cup 7.

The N Faraday cups 31 on the other right-angled side are Faraday cup 8 , Faraday cup 9 , Faraday cup 10 , Faraday cup 11 , Faraday cup 12 and Faraday cup 13 .

The 2N Faraday cups 31 are located at different radial positions of the screen 12 and correspond to the positions of the N ring holes of the screen respectively. That is, Faraday cup 2 and Faraday cup 8 correspond to the 2.35mm screen grid annular hole, and Faraday cup 3 and Faraday cup 9 correspond to The 2.47mm screen grid annular hole corresponds, Faraday cup 4 and Faraday cup 10 correspond to the 2.63mm screen grid annular hole, Faraday cup 5 and Faraday cup 11 correspond to the 2.72mm screen grid annular hole, Faraday Cup 6 and Faraday cup 12 correspond to the annular hole of the screen grid of 2.91 mm, and Faraday cup 7 and Faraday cup 13 correspond to the annular hole of the screen grid of 3.13 mm. In this embodiment, multi-point sampling measurement can be performed, so that the uniformity adjustment is more accurate.

All above-mentioned shutter driving devices and all Faraday cups 31 are connected with the driving device controller.

A plasma density control method includes the following steps.

Step 1, plasma signal detection:

Before etching, the baffle plate 6 is driven by the baffle plate driving device 61 to leave the annular hole of the screen grid.

The ion source 1 is turned on by the ion source controller 14, and under the action of the ion source controller 14, the Ar charged in the discharge chamber 11 is ionized to form a plasma, the screen grid 12 is charged with a positive charge to focus the plasma, and the acceleration grid 13 is charged with a negative charge The ions are extracted and accelerated in the form of a beam, and the plasma is extracted in the form of an ion beam, which is incident on the Faraday cup group 3. There are several Faraday cups 31 distributed on the Faraday cup group 3. The Faraday cups 31 convert the injected ion beam quantity into a current signal, And feed back to the drive device controller 7.

Step 2, plasma density uniformity judgment:

When the Faraday group 3 feeds back the current signal to the driving device controller 7, the driving device controller 7 compares the current signals, and the plasma density is higher in the area with high current, and the plasma density in the area with low current is low.

The drive device controller 7 selects the maximum current and the minimum current for comparison. When the difference between the maximum current and the minimum current is less than the set value, it means that the density of the extracted ion beam is uniform. In this state, it can ensure good uniformity when etching the wafer 5 , under the action of the baffle driving device 61, the baffle 6 blocks the ion beam, and when the wafer is placed on the lower electrode 4 and rotates to the etching position, the baffle 6 falls, and the ion beam etches the wafer 5.

When the difference between the maximum current and the minimum current is greater than the set value, it means that the density distribution of the extracted ion beam is not uniform.

Step 3, plasma density control, specifically includes the following steps:

Step 31 , determine the timing of shielding: when step 2 determines that the plasma density is not uniform, the drive device controller 7 simultaneously reads the Faraday cup 31 corresponding to the maximum current.

Step 32, shielding: the controller 7 of the driving device determines the activated shutter assembly according to the position of the Faraday cup 31 corresponding to the maximum current, rotates the shutter under the control of the shutter driving device, and conducts a check on the area with high plasma density block. Among them, when the baffle rotates to the radial direction, the width corresponding to the maximum current Faraday cup is the largest. The width here refers to the width of the baffle to block the plasma density.

That is, the driving device controller 7 will control the first baffle driving device 71 or the second baffle driving device 72 to drive the first baffle 81 or the second baffle 82 to shield the area with high plasma density and reduce the local plasma density , so that the wafer can be etched uniformly.

In this embodiment, the specific preferred occlusion method is:

Step 32A, when the Faraday cup 31 corresponding to the maximum current is located at the edge, the driving device controller 7 controls the second shutter driving device 72 to drive the second shutter 82 Do occlusion.

Step 32B, when the Faraday cup 31 corresponding to the maximum current is close to the inner center, the driving device controller 7 controls the first shutter driving device 71 to drive the first shutter 81 to block.

Step 33, the plasma density is detected again: while the blocker rotates to block, the Faraday cup 31 detects the plasma density in real time, and the drive device controller 7 judges the uniformity of the plasma density according to step 2 until the plasma density is uniform and the block The slice stops spinning.

As shown in Figure 13, when the Faraday cup 31 corresponding to the maximum current is located at the edge, after the second shutter driving device 72 rotates 90°, the edge plasma density is still the largest and the plasma density uniformity is judged to be uneven, the drive The device controller 7 will control the movement of the first shutter driving device 71 to shield more edge plasma until the plasma density is uniform.

From the perspective of theory and process, the etching rate of wafer 5 in the middle area is smaller than that of the edge area, and the current density within Faraday cup 2 is the lowest, and the area with a faster etching rate is generally concentrated in the radius range from Faraday cup 3 to Faraday cup 7. , when the Faraday group 3 feeds back the current signal to the drive device controller 7, the drive device controller 7 simultaneously reads the Faraday cup corresponding to the maximum current, and when the Faraday cup 31 corresponding to the maximum current is at the edge, such as the Faraday cup 7, The driving device controller 7 controls the second blocking plate driving device 72 to drive the second blocking plate 82 to block until the plasma density is uniform. If the edge plasma density cannot be reduced after the second baffle driving device 72 is rotated by 90°, the driving device controller 7 will sequentially control the first baffle driving device 71 to move to shield more plasma. The form of the second baffle 82 should be wide at the edges and narrow at the center style.

When the Faraday cup 31 corresponding to the maximum current is close to the inside, such as the Faraday cup 3, the drive device controller 7 controls the first shutter drive device 71 to drive the first shutter 81 to block until the maximum current area is not within this range . At this time, the style of the first blocking piece 81 should be selected as a style with a wide middle and a narrow edge. The number and size of the baffles can be designed according to the process test results.

The preferred embodiments of the present application have been described in detail above, but the present application is not limited to the specific details in the above-mentioned embodiments. Within the scope of the technical concept of the present application, various equivalent transformations can be performed on the technical solutions of the present application, and these equivalent transformations are all Belong to the protection scope of this application.

1: ion source

2: Reaction chamber

3: Faraday Cup Group

31: Faraday Cup

4: Bottom electrode

5: Wafer

6: Baffle

61: Baffle driving device

7: Drive controller

71: The first block drive device

11: discharge cavity

12: screen grid

13: Acceleration grid

14: Ion source controller

Claims (10)

A plasma density control system comprising: reaction chamber; Ion sources, including: The ion source chamber and the discharge chamber are arranged coaxially from outside to inside; and A screen grid, the screen grid is arranged at the tail end of the ion source chamber, and N groups of screen grid annular holes are arranged radially on the screen grid, wherein N is an integer and greater than or equal to 1; Faraday Cup set, including: a Faraday cup mounting frame, arranged on the wall of the reaction chamber corresponding to the screen grid; and at least N Faraday cups, the N Faraday cups corresponding to the positions of the N groups of screen annular holes; and Shutter mechanism, including: drive controller; and At least two groups of baffle assemblies, each group of baffle assemblies includes a plurality of baffles and a baffle driving device, and the plurality of baffles are evenly arranged along the circumference of the tail end of the discharge chamber, wherein each baffle is Driven by the corresponding shutter driving device, it can rotatably extend into the discharge chamber and block the plasma entering the corresponding screen grid annular hole; Wherein, the baffles between the baffle assemblies are arranged alternately, the shapes of the baffles between the baffle assemblies are different, and all the baffle drive devices and all the Faraday cups are connected to the drive device controller. connect. The plasma density control system according to claim 1, wherein the Faraday cup mounting frame is a straight frame, and the number of the Faraday cups is N+1; one of the Faraday cups is located in the reaction chamber On the central axis of the chamber, the remaining N Faraday cups are collinearly installed on the straight bar frame, and correspond to the positions of the N sets of grid ring holes. The plasma density control system according to claim 1, wherein the Faraday cup mounting frame has an L-shaped frame, and the corners of the L-shaped frame are located on the central axis of the reaction chamber, and one of the Faraday cups Installed on the corner of the L-shaped frame, N Faraday cups are respectively installed on the two right-angled sides of the L-shaped frame, and the 2N Faraday cups are located at different radius positions of the screen grid, and respectively Corresponding to the positions of the N groups of screen grid annular holes. The plasma density control system according to claim 1, wherein the shutter mechanism includes two sets of shutter assemblies, namely a first shutter assembly and a second shutter assembly, and the first shutter assembly It includes a plurality of first blocking plates and a first blocking plate driving device; the second blocking plate assembly includes a plurality of second blocking plates and a second blocking plate driving device; the cross section of each of the first blocking plates is centered The shape of an inverted cone or trapezoid with wide edges and narrow edges; the cross-section of each of the second blocking pieces is in the shape of a cone or trapezoid with wide edges and narrow centers. The plasma density control system according to claim 4, wherein, the discharge chamber is installed on the ion source chamber of the ion source through a discharge chamber support base; each of the first baffles and each of the The edge end of the second blocking piece can be rotatably installed on the end face of the discharge chamber support seat. The plasma density control system according to claim 5, wherein the lengths of each of the first baffles and each of the second baffles are the same, 1/4r~1/2r, where r is The radius of the screen grid. The plasma density control system according to claim 1, wherein the shutter driving device is a rotary cylinder or a motor. A plasma density control method, comprising: Step 1, detect the plasma signal, wherein, before etching, turn on the ion source, the plasma in the discharge chamber passes through the screen ring hole of the screen grid, and then focuses to form an ion beam, and each Faraday cup will detect its own radial position the plasma signal at the place; and convert the detected plasma signal into a current signal, and feed it back to the drive device controller; Step 2, judging the uniformity of the plasma density, wherein the drive device controller reads the maximum current and the minimum current according to the received current information, and compares the maximum current and the minimum current In contrast, when the difference between the maximum current and the minimum current is less than a set value, it is judged that the plasma density in the reaction chamber is uniform; otherwise, it is judged that the plasma density is uneven; and Step 3, controlling the plasma density, including: Step 31, determining the blocking opportunity, wherein, when the plasma density is judged to be uneven in step 2, the drive device controller simultaneously reads the position of the Faraday cup corresponding to the maximum current; Step 32, shielding, wherein the controller of the driving device determines the activated shutter assembly according to the position of the Faraday cup corresponding to the maximum current, and rotates the shutter under the control of the shutter driving device The baffle of the assembly shields the region with high plasma density; when the baffle rotates to the radial direction, the width corresponding to the Faraday cup of the maximum current is the largest; and Step 33, detect the plasma density again, wherein the Faraday cup detects the plasma density in real time while the shutter rotates to block, and the drive device controller performs the plasma density according to step 2. Judgment of the uniformity of density, until the plasma density is uniform, the baffle stops rotating. The plasma density control method as claimed in item 8, wherein, in step 32, the step of shielding includes: Step 32A, when the Faraday cup corresponding to the maximum current is located at the edge, the driving device controller controls the second shutter driving device to drive the second shutter to block; Step 32B, when the Faraday cup corresponding to the maximum current is close to the inner center, the driving device controller controls the first shutter driving device to drive the first shutter to block. The plasma density control method according to claim 8, wherein, in step 33, after the second shutter driving device rotates 90°, the edge plasma density is still the largest and the uniformity of the plasma density is judged as not When uniform, the driving device controller controls the first shutter driving device to move to shield more of the edge plasma until the plasma density is uniform.

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