TWI670785B - Plasma processor and etching uniformity adjusting system and method - Google Patents

Abstract

The invention discloses an etching uniformity adjustment system, which includes a plurality of feedback adjustment devices and a calculation control unit connected to the feedback adjustment devices. Each feedback adjustment device includes a current monitor, a restriction ring installed in a plasma reaction chamber, and a ground. The calculation control unit is connected between the loops and is connected to the calculation control unit; the active lifter is installed between the restriction ring and the grounding ring of the plasma reaction chamber and is located at the corresponding position of the current monitor; the calculation control unit obtains the limit through the plurality of current monitors The current distribution in each area between the ring and the grounding ring controls the gap between the limiting ring and the grounding ring by the active elevator. Its advantage is: by the active action of the active lifter and the current monitor, real-time active feedback control of the plasma uniformity is realized.

Description

Plasma processor and etching uniformity adjustment system and method

The invention relates to the technical field of plasma etching, in particular to a plasma processor and an etching uniformity adjusting system and method.

An object of the present invention is to provide a plasma processor and an etching uniformity adjusting system and method, which realize the real-time active feedback on the plasma uniformity and the symmetry of the etching process through the cooperation of an active lifter and a current monitor. Control (PID control).

In order to achieve the above object, the present invention is achieved by the following technical solution: an etching uniformity adjustment system connected to a plasma processor, the plasma processor includes a plasma sub-reaction chamber, and the plasma reaction chamber has A pedestal for placing a wafer, with a confinement ring and a grounding ring between the pedestal and the side wall of the reaction chamber, wherein the confinement ring has a plurality of gas channels for confining the plasma above the confinement ring, and the grounding ring is made of a conductor And is electrically grounded, characterized in that the etching uniformity adjustment system includes a plurality of feedback adjustment devices and a calculation control unit connected to the feedback adjustment device; wherein each of the feedback adjustment devices includes: a current monitor, an installation Between the limiting ring and the grounding ring of the plasma reaction chamber, and connecting the computing control unit, which is used to monitor the current flowing between the limiting ring and the grounding ring in the area in which it is located; An active lifter is installed between the limiting ring and the grounding ring of the plasma reaction chamber and is located at the corresponding position of the current monitor, and is used to adjust the gap between the limiting ring and the grounding ring in the area where the current monitor is located; , The calculation control unit controls the gap between the limiting ring and the grounding ring of the active lifter according to the current distribution of each area between the limiting ring and the grounding ring obtained by the obtained complex current monitor.

In the above-mentioned etching uniformity adjusting system, three or more feedback adjusting devices are provided between the limiting ring and the ground ring.

In the above-mentioned etching uniformity adjusting system, the complex feedback adjusting device is evenly distributed in each region between the limit ring and the ground ring.

In the above-mentioned etching uniformity adjusting system, the limiting ring includes a limiting ring body and a supporting portion provided on the outer ring of the limiting ring body, and the feedback adjusting device is installed between the supporting portion and the ground ring.

In the above-mentioned etching uniformity adjusting system, the current monitor in each feedback adjusting device is located at the center of the corresponding active lifter.

In the above-mentioned etching uniformity adjusting system, the range of the distance between the ground ring and the limiting ring is: 0.2 mm or more.

An etching uniformity adjusting method is completed by using an etching uniformity adjusting system. The etching uniformity adjusting system is connected to a plasma processor. The plasma processor includes a plasma sub-reaction chamber. The plasma reaction chamber has A limiting ring and a ground ring for transmitting radio frequency electric power by a capacitive coupling method are characterized in that the adjustment method includes: A complex feedback adjusting device is provided between the limit ring and the ground ring, and the complex feedback adjusting device is connected to a calculation control unit. Each of the feedback adjusting devices includes a current monitor installed between the limit ring and the ground ring, and Active elevator; the complex current monitor monitors the current flowing between the limit ring and the ground ring in its area in real time, and feeds back the monitoring result to the calculation control unit; the calculation control unit actively takes the current value of the complex through the received current distribution value The lifts each issue active continuous adjustment instructions; the plural active lifts adjust the gap and distributed capacitance between the restriction ring and the ground ring in their area according to the active adjustment instructions, thereby completing the current flow between the restriction ring and the ground ring in the area. Adjustment.

A plasma processor is characterized by comprising any one of the above-mentioned etching uniformity adjustment systems.

Compared with the prior art, the present invention has the following advantages: it realizes the real-time active feedback control (PID control) of the plasma uniformity and the symmetry of the etching process through the combined action of an active lifter and a current monitor, and this kind of Feedback control has universal applicability to different cavities and different etching technology processes.

An object of the present invention is to provide a plasma processor and an etching uniformity adjusting system and method, which realize the real-time active feedback on the plasma uniformity and the symmetry of the etching process through the cooperation of an active lifter and a current monitor. Control (PID control).

In order to achieve the above object, the present invention is implemented by the following technical solutions: An etching uniformity adjustment system is connected to a plasma processor. The plasma processor includes a plasma sub-reaction chamber. The plasma reaction chamber has a pedestal for placing a wafer, the pedestal, and a reaction. There is a confinement ring and a ground ring between the side walls of the cavity. The confinement ring has multiple gas channels for confining the plasma above the confinement ring. The ground ring is made of a conductor and is electrically grounded. The feature is that the etching is uniform The adjustment system includes a plurality of feedback adjustment devices and a calculation control unit connected to the feedback adjustment device. Each of the feedback adjustment devices includes a current monitor installed between a limit ring and a ground ring of the plasma reaction chamber. And connected to the calculation control unit for monitoring the current flowing between the restriction ring and the grounding ring in the area where it is located; the active lifter is installed between the restriction ring and the grounding ring of the plasma reaction chamber and is located above the current The corresponding position of the monitor is used to adjust the gap between the limit ring and the ground ring in the area where the current monitor is located. ; Wherein the calculation control unit acquires limit between the ring and ground ring current size of the control region of each active lift adjustable restricted gap between the ring and ground ring according to obtain a plurality of current monitor obtained.

In the above-mentioned etching uniformity adjusting system, three or more feedback adjusting devices are provided between the limiting ring and the ground ring.

In the above-mentioned etching uniformity adjusting system, the complex feedback adjusting device is evenly distributed in each region between the limit ring and the ground ring.

The above-mentioned etching uniformity adjusting system, wherein: The restriction ring includes a restriction ring body and a support portion provided on the outer ring of the restriction ring body, and the feedback adjustment device is installed between the support portion and the ground ring.

In the above-mentioned etching uniformity adjusting system, the current monitor in each feedback adjusting device is located at the center of the corresponding active lifter.

In the above-mentioned etching uniformity adjusting system, the range of the distance between the ground ring and the limiting ring is: 0.2 mm or more.

An etching uniformity adjusting method is completed by using an etching uniformity adjusting system. The etching uniformity adjusting system is connected to a plasma processor. The plasma processor includes a plasma sub-reaction chamber. The plasma reaction chamber has A limiting ring and a ground ring for transmitting radio frequency electric power by capacitive coupling are characterized in that the adjustment method includes: setting a complex feedback adjusting device between the limiting ring and the ground ring, and connecting the complex feedback adjusting device to a calculation A control unit, each of the feedback adjusting devices includes a current monitor and an active lifter installed between the limit ring and the ground ring; the plurality of current monitors perform instantaneous current flow between the limit ring and the ground ring in the area where the current monitor flows. Monitor and feed the monitoring results back to the calculation control unit; the calculation control unit sends active continuous adjustment instructions to the plural active lifts respectively based on the received current distribution value; the plural active lifts adjust the restriction ring and ground of its area according to the active adjustment instructions Gaps between loops and distributed capacitance to complete Adjusting the current flowing between the ground ring and the confinement ring area.

A plasma processor is characterized by comprising any one of the above-mentioned etching uniformity adjustment systems.

Compared with the prior art, the present invention has the following advantages: it realizes the real-time active feedback control (PID control) of the plasma uniformity and the symmetry of the etching process through the combined action of an active lifter and a current monitor, and this kind of Feedback control has universal applicability to different cavities and different etching technology processes.

1‧‧‧ restriction ring

11‧‧‧ Restriction ring body

12‧‧‧ support

2‧‧‧ ground ring

3‧‧‧ Computing Control Unit

41‧‧‧Current Monitor

42‧‧‧Active Lift

FIG. 1 is a schematic diagram of a connection relationship of an etching uniformity adjusting system of the present invention; FIG. 2 is a schematic diagram of an installation structure of a feedback adjusting device in the etching uniformity adjusting system of the present invention.

The present invention will be further described below in detail with reference to the accompanying drawings by describing a preferred embodiment in detail.

The invention discloses an etching uniformity adjusting system, which is connected to a plasma processor to improve the etching unevenness caused by different factors of the plasma processor. The plasma processor usually includes a plasma sub-reaction chamber. A pedestal for placing wafers is provided at the bottom of the plasma reaction chamber. A FEIS ring 1 is provided on the side wall of the pedestal. The inner ring of the restricted ring 1 is connected to the pedestal, and the outer ring of the restricted ring 1 is connected. To the inner wall of the plasma reaction chamber, filling the space between the pedestal and the inner wall of the plasma reaction chamber, and preventing the plasma exhaust gas from leaking from the plasma reaction chamber to the exhaust space below the restriction ring 1. The restriction ring 1 is made of an insulating material such as alumina ceramics. The restriction ring 1 is provided with a large number of air flow channels penetrating the upper and lower surfaces of the restriction ring 1. The opening size and depth of these channels are designed to ensure the plasma gas formed above the base. When passing through the restriction ring 1, all the ions in it are extinguished, and the neutral gas flows downward. The base includes an electrode connected to at least one RF power source. The RF power source applies RF power to the electrodes in the base and is capacitively coupled to the reaction chamber. The upper electrode opposite to the pedestal, the side walls of the reaction chamber, and surrounding components such as the confinement ring 1. The impedance distribution of the confinement ring closest to the wafer to be processed on the pedestal will affect the RF electric field distribution around the pedestal, and then affect the plasma distribution and the uniformity of the etching effect. In order to prevent the radio frequency electric field in the base from propagating below the limiting ring 1, the reaction gas that has been restored to neutral is ignited again to form a secondary plasma and contaminate the inner wall and the exhaust pipe below the reaction chamber. A large amount of accumulated charge also needs to be conducted to the grounding terminal. Therefore, a grounding ring 2 (MGR ring) is provided under the limiting ring 1. The grounding ring 2 is made of a conductor and is electrically grounded. This shields RF energy above the grounding ring , To avoid the generation of secondary plasma, while conducting away the accumulated charge on the confinement ring 1. Since the restriction ring 1 is made of an insulating material, the contact surface between the ground ring 2 and the restriction ring 1 is an insulating contact surface. Limiting ring 1 is at floating potential, grounding ring 2 is at zero potential, and the RF electric power is transmitted between grounding ring 2 and limiting ring 1 by capacitive coupling (no DC conduction). Therefore, between grounding ring 2 and limiting ring 1 The transmission impedance is mainly determined by the capacitance between its insulating contact surfaces. In the prior art, the contact distance between the grounding ring 2 and the limiting ring 1 is zero (or very close to zero). When the gap between the two rings is not adjusted, the capacitance of the limiting ring 1 to ground is as high as> 5nf, and Increase the distance between the ground ring 2 and the limit ring 1 to 0.2mm or more, and reduce the ground capacitance of the limit ring 1 to <2nf. It can be seen that the slight disturbance (<0.2mm) of the separation distance between the ground ring 2 and the limit ring 1 will greatly affect the contact capacitance, and when the separation distance is greater than 0.2mm, it will not have a significant impact on the contact capacitance. It can be seen that actively adjusting the gap between the two loops has a great impact on the capacitance between the loops. Studies have shown that the capacitance between the loops is a key factor affecting the symmetry of the etching technology.

As shown in FIGS. 1 and 2, the etching uniformity adjustment system disclosed in the present invention includes a plurality of feedback adjustment devices and a calculation control unit 3 connected to the feedback adjustment device. The calculation control unit may be composed of a computer system. ; Wherein each of the feedback adjustment devices includes: a current monitor 41 (Current Sensor), a restriction ring 1 and a ground ring 2 installed in the plasma reaction chamber And connected to the calculation control unit 3 for monitoring the current flowing between the restriction ring 1 and the ground ring 2 in its area; an active lift 42 (Spacer Lift) installed in the plasma reaction chamber The restriction ring 1 and the ground ring 2 are located at the corresponding positions of the current monitor 41, and are used to adjust the gap between the restriction ring 1 and the ground ring 2 in the area where the current monitor is located. Among them, the calculation control unit 3 The active lifter 42 is controlled by the multiple current monitor 41 to adjust the gap between the restriction ring 1 and the ground ring 2 according to the current distribution of each area between the obtained restriction ring 1 and the ground ring 2.

Preferably, the plurality of feedback adjusting devices are evenly distributed in each area between the restriction ring 1 and the ground ring 2, and it is foreseeable that when three and With the above feedback adjustment device, the symmetry adjustment of the etching technology will become more fine and uniform.

In an embodiment of the present invention, the restriction ring 1 includes a restriction ring body 11 and a support portion 12 provided on an outer ring of the restriction ring body 11. The feedback adjustment device is installed between the support portion 12 and the ground ring 2. The thickness of the support portion 12 is greater than the restriction ring body 11. When the restriction ring 1 is provided on the ground ring 2, the support portion 12 contacts the ground ring 2 and erects the restriction ring 1 so that the restriction ring body 11 does not contact the ground ring 2. For contact, the limiting ring 1 is in contact with the ground ring 2 through the supporting portion 12, so that the contact surface between the ground ring 2 and the limiting ring 1 is an insulating contact surface.

In another embodiment of the present invention, the current monitor 41 in each feedback adjustment device is located at the center of the corresponding active lifter 42 to ensure the accurate correlation between the current monitoring and the gap adjustment. In addition, the installation manner of the feedback adjustment device may be various. In this embodiment, the feedback adjustment device is installed and fixed in the installation grooves of the restriction ring 1 and the ground ring 2.

The invention also discloses an etching uniformity adjustment method, which is completed by using the above-mentioned etching uniformity adjustment system. The adjustment method includes: S1. A complex feedback adjustment device is provided between the restriction ring 1 and the ground ring 2, and the complex feedback adjustment device is connected to a calculation control unit 3. Each of the feedback adjustment devices includes a restriction ring 1 and a ground ring 2 respectively. Current monitor 41 and active elevator 42; S2, the multiple current monitor 41 monitors the current flowing between the restriction ring 1 and the ground ring 2 in its area in real time, and feeds the monitoring result back to the calculation control unit 3 ; S3. The calculation control unit 3 sends active continuous adjustment instructions to the plurality of active lifters 42 respectively according to the received current distribution value; specifically, according to the monitoring result of the plurality of current monitors 41, the current distribution of each area of the limit ring 1 is obtained, and the current The size means the magnitude of the change in the capacitance to the capacitance and the capacitance ratio, and determines whether the distance between the two rings in each area needs to be increased or decreased or unchanged, and actively sends continuous adjustment instructions to the corresponding active elevators 42; S4, plural The active lifter 42 adjusts the gap and distributed capacitance between the restriction ring 1 and the ground ring 2 in its area according to the active adjustment instruction , Thereby completing the adjustment of the current flowing between the restriction ring 1 and the ground ring 2 flowing through the area.

Although the content of the present invention has been described in detail through the above-mentioned preferred embodiments, it should be recognized that the above description should not be considered as limiting the present invention. After reading the above content by a person having ordinary knowledge in the art, various modifications and alternatives to the present invention will be apparent. Therefore, the protection scope of the present invention should be defined by the scope of the attached patent application.

Claims (8)

An etching uniformity adjusting system includes: a plasma processor is connected; the plasma processor includes a plasma sub-reaction chamber; the plasma reaction chamber has a pedestal for placing a wafer; There is a restriction ring (1) and a grounding ring (2) between the base and a side wall of the reaction chamber; wherein the restriction ring (1) has a plurality of gas channels for restricting a plasma above the restriction ring, The ground ring is made of a conductor and is electrically grounded, and includes: the etching uniformity adjustment system includes a plurality of feedback adjustment devices and a calculation control unit (3) connected to the feedback adjustment devices; wherein each of the feedback adjustment devices is respectively Including: a current monitor (41) installed between the restriction ring (1) and the ground ring (2) of the plasma reaction chamber, and connected to the calculation control unit (3) for convection flow The current between the limiting ring (1) and the grounding ring (2) in the area is monitored; an active lift (42), the limiting ring (1) and the grounding ring (2) installed in the plasma reaction chamber And in the corresponding position of the current monitor (41) It is used to adjust the gap between the limit ring (1) and the ground ring (2) in the area where the current monitor is located; wherein, the calculation control unit (3) is based on a plurality of the current monitor (41) according to The obtained current distribution in each area between the restriction ring (1) and the ground ring (2) controls the active lifter (42) to adjust the gap between the restriction ring (1) and the ground ring (2). The etching uniformity adjustment system according to item 1 of the scope of patent application, which includes: three or more feedback adjustment devices are provided between the restriction ring (1) and the ground ring (2). The etching uniformity adjustment system according to item 1 of the scope of patent application, comprising: a plurality of the feedback adjustment devices evenly distributed in each area between the restriction ring (1) and the ground ring (2). The etching uniformity adjusting system according to item 1 or 3 of the patent application scope, comprising: the restriction ring (1) includes a restriction ring body (11) and a first ring provided on the outer ring of the restriction ring body (11). A support portion (12), the feedback adjustment device is installed between the support portion (12) and the ground ring (2). The etching uniformity adjusting system according to item 1 of the scope of patent application, wherein the current monitor (41) in each of the feedback adjusting devices is located at the center corresponding to the active lifter (42). The etching uniformity adjusting system according to item 1 of the scope of patent application, comprising: a range of a separation distance between the ground ring (1) and the limiting ring (2) is: 0.2 mm or more. An etching uniformity adjusting method is completed by using an etching uniformity adjusting system. The etching uniformity adjusting system is connected to a plasma processor. The plasma processor includes a plasma sub-reaction chamber. The plasma reaction chamber has A limiting ring (1) and a grounding ring (2) for realizing the transmission of radio frequency electric power by means of capacitive coupling. The adjusting method includes: setting a complex feedback adjustment between the limiting ring (1) and the grounding ring (2). Device, and the plurality of feedback adjustment devices are connected to a calculation control unit (3), and each of the feedback adjustment devices includes a current monitor (41) installed between the limit ring (1) and the ground ring (2). And an active lifter (42); the plurality of current monitors (41) monitor the current flowing between the restriction ring (1) and the grounding ring (2) in real time through its area, and feed back the monitoring result to the The calculation control unit (3); the calculation control unit (3) sends active continuous adjustment instructions to the plurality of active lifts (42) respectively according to the received current distribution value; the plurality of active lifts (42) adjusts them according to the active adjustment instructions Where The field limiting ring (1) and the grounding ring and the gap between the distributed capacitance (2), thereby completing the loop flowing through the restriction region (1) and the ground current between the adjusting ring (2). A plasma processor includes the etching uniformity adjusting system according to any one of claims 1 to 5.