TW201525184A - Plasma processing device - Google Patents

Abstract

A plasma processing device comprises: a reaction chamber comprising therein a base on which an electrostatic chuck is disposed, a substrate to be processed being provided on the electrostatic chuck; an adjustment ring surrounding the periphery of the electrostatic chuck; an edge compensation ring surrounding the periphery of the electrostatic chuck or the base and below the adjustment ring, characterized in that the edge compensation ring is embedded with an electrode; a power distribution circuit receives a first and a second radio frequency power through a first and a second input end and outputs the first and second radio frequency power to the base through a first output end, and outputs the first or second radio frequency power to the electrode in the edge compensation ring through a second output end. The power distribution circuit further comprises a third input end for receiving a firs DC voltage source and outputting the DC voltage to the electrode in the edge compensation ring through the second output end.

Description

Plasma processing device

The present invention relates to the field of semiconductor manufacturing technology, and in particular to an edge compensation ring applied to a plasma processing apparatus.

Semiconductor processing processes for the fabrication of integrated circuits include chemical vapor deposition processes, plasma etching processes, etc. Typical etching of tantalum or insulating material tantalum oxide requires the use of plasma etching equipment. As shown in the plasma etching apparatus shown in Fig. 1, the plasma etching apparatus comprises a reaction chamber 1, and the bottom of the reaction chamber includes a base 33 to which an RF power source is connected. An electrostatic chuck 34 is disposed on the susceptor for fixing the substrate 30 to be processed placed above the electrostatic chuck. The periphery of the electrostatic chuck also includes a uniform adjustment ring 36 which improves the uniformity of processing of the edge region relative to the neutral region by designing the material, shape or even thickness of the adjustment ring. The top of the reaction chamber opposite the substrate includes a gas distribution device such as a gas showerhead 40 that is coupled to an external source 50. The design of the adjustment ring in plasma etching plays a very important role in the processing effect of the substrate. For example, the selection of the adjustment ring material is different, especially the difference in the conductivity characteristics causes the RF power fed into the pedestal 33 to be distributed to the central area of the substrate. The ratio of the edge area is different, and the further plasma distribution will be different;

Due to the spatial structure at the edge position of the substrate, there is a gap between the edge of the substrate and the adjustment ring, and the intensity and temperature of the RF electric field between the base 33 and the adjustment ring 36 are also different. There is a flowing cooling gas such as helium between the upper surface of the electrostatic chuck 34 and the lower surface of the substrate 30, so that the substrate 30 has a stable and suitable temperature. The periphery of the electrostatic chuck 34 is surrounded by an adjustment ring 36. The adjustment ring 36 is heated to a higher temperature by the heat generated by the upper plasma. This higher temperature causes a sudden change in the chemical reaction rate, and also causes reaction products such as polymerization. The objects gather in the edge regions of the substrate. At the same time, since the RF electric field is only passed into the reaction chamber through the pedestal 33 in the prior art, the electric field intensity of the corresponding edge region of the adjustment ring 36 is lower than that of the central reaction region, so the plasma concentration in the edge region is low, and the sheath formed by the plasma is formed. The layer is also thinner and therefore also causes unevenness in the plasma treatment effect on the entire surface of the substrate. Therefore, the industry needs a new design that can achieve the same processing effect as the central region in the edge region of the substrate while effectively controlling the temperature of the edge region.

The problem to be solved by the present invention is to provide a plasma processing apparatus capable of compensating for the plasma concentration and the thickness unevenness of the sheath layer in the edge region of the substrate, and at the same time adjusting the temperature of the adjusting ring surrounding the periphery of the substrate to solve the above problem. The inventors provide a plasma processing apparatus, comprising: a reaction chamber, the reaction chamber includes a base, the base is provided with an electrostatic chuck, and the substrate to be processed is disposed on the electrostatic chuck; an adjusting ring surrounds An edge compensation ring surrounds the periphery of the susceptor or the electrostatic chuck and is located under the adjustment ring, and the electrode is embedded in the edge compensation ring, and a power distribution circuit passes through the periphery of the electrostatic chuck. The first and second input terminals receive the first and second RF power sources and output the first and second RF power sources to the base through the first output terminal, and output the first or second RF frequency through the second output end Powering the electrode to the edge compensation ring, the power distribution circuit further comprising a third input receiving the first DC voltage source, and outputting the DC through the second output Voltage is applied to the electrodes within the edge compensation ring.

Wherein the power distribution circuit includes a fourth input terminal receiving the second DC voltage source and outputting the second DC voltage through the first output terminal, wherein the first and second DC voltages can respectively implement the adjustment ring and the substrate to be processed Electrostatic clamping.

The edge compensation ring includes a cooling gas passage that passes the cooling gas into the contact surface between the edge compensation ring and the adjustment ring to further improve heat transfer between the adjustment ring and the edge compensation ring.

The power distribution circuit includes a plurality of matching circuits to achieve matching of the first and second RF power sources with the impedance of the reaction chamber. The switching circuit is further included between the second output end and the first input end, so that the first RF power source is selectively connected to the second output end through an inductor.

An edge compensation ring is disposed on the outwardly extending portion of the base, or the edge compensation ring is secured to the ring of insulating material (52) that is secured to the outwardly extending portion of the base. The outer side of the edge compensation ring may also be arranged in sequence including an insulating ring and a conductive mask layer. The edge compensation ring includes a lower vertical sidewall and an upper annular plate extending from an outer side of the annular plate, and the adjustment ring is located on the annular plate.

The edge compensation ring is made of alumina, has good thermal conductivity while achieving insulation, and achieves better temperature control of the adjustment ring.

Please refer to FIG. 2a, 2b for understanding the solution of the present invention, and FIG. 2a is an enlarged structural view of the base 33 of FIG. The susceptor 33 of the present invention includes a plurality of coolant conduits for maintaining the temperature of the susceptor, and the susceptor 33 is coupled to the A output of the circuit shown in FIG. The top of the base 33 is protected from an electrostatic chuck 34, and the substrate 30 to be processed is fixed above the electrostatic chuck 34. An adjustment ring 36 surrounds the outer periphery of the electrostatic chuck and has a gap with the electrostatic chuck 34 and the substrate. The material of the adjusting ring 36 may be quartz or tantalum, tantalum carbide, aluminum oxide, etc., and the shape and material are selected for a more uniform electric field distribution, and may have different designs according to different applications. The adjustment ring 36 is placed on the extension of the base 33 by an edge compensation ring 32. An insulating ring 38 made of an insulating material is also disposed around the base 33 and the outer side of the focus ring. The insulating ring 38 further includes a conductive mask layer 39. The insulating layer and the conductive mask layer can limit the RF electric field only in the reaction area. The internal diffusion does not diffuse to the area between the outer side wall of the susceptor and the inner wall of the reaction chamber. The edge compensation ring 32 of the present invention may be made of a ceramic material, typically such as alumina. The edge compensation ring 32 also includes an electrode 321 inside which is connected to the B output terminal of the circuit shown in FIG.

FIG. 3 is a structural diagram of an optional power supply circuit according to the present invention. The power supply circuit of the present invention includes a first RF power source. As shown in the figure, RF1 outputs RF power to the A output terminal through the first matching circuit M1 and an isolation circuit 20. The first matching circuit M1 includes a variable capacitor Cv1 and a fixed capacitor C1, and an inductor L1. By adjusting the variable capacitor Cv1, the RF power output from the RF power source RF1 is output as much as possible to the A or B output terminal in the reaction chamber. . The invention also includes the second RF power source RF2 being coupled to the A output via a matching circuit M2. The second matching circuit M2 includes a second variable capacitor Cv2 and a second inductor L2 and a second capacitor C2 connected in series. The second matching circuit M2 has a similar function to the first matching circuit, except that the second RF is adjusted. The matching impedance of the power supply. The isolation circuit 20 includes a third inductor L3 and a third capacitor C3. The isolation circuit can prevent the output power of the second RF power source RF2 from flowing backward into the first RF power source to cause overheating to burn the power source. A first DC power source DC1 is connected to the A output through an RF filter circuit. The first RF power source RF1 is also connected to the output terminal B through a distribution capacitor Ca, and the ratio of the RF power output between A and B can be distributed by adjusting the variable distribution capacitance. The first RF power source RF1 and the B output end further includes an inductor L4 and a switching circuit S0. The switching circuit S0 can selectively connect the output end of the inductor L4 to one of the output terminals B and Lp, and can switch to the output terminal Lp. The phase of the RF electric field outputted to the output terminal B is different from that of the RF power supply RF1, and the phase adjustment of the RF electric field between the output of the A and the output of the B is realized. The input of the inductor L4 is also connected to the second DC power source DC2 through an RF filter circuit. The first DC power source DC1 can provide a DC voltage of up to several hundred or even thousands of volts so that the electrodes in the electrostatic chuck 34 can induce a charge on the substrate, and the substrate is firmly adsorbed on the electrostatic chuck by electrostatic attraction. The second DC power source DC2 provides a DC voltage of similar magnitude such that the electrodes 321 in the edge compensation ring 32 generate sufficient DC voltage and the adjustment ring 36 is firmly attracted to the edge compensation ring 32.

The first RF power source RF1 in the power supply circuit of the present invention can supply a radio frequency electric field having a higher frequency, such as 13Mhz, 27Mhz, 60Mhz, and 100Mhz for generating and maintaining a plasma. The second RF power source RF2 can provide a radio frequency electric field with a lower frequency, such as 2Mhz, for controlling the thickness of the sheath on the upper surface of the pedestal or the upper surface of the substrate, and finally controlling the energy of the incident ions. It is also possible to interchange the two RF power supply locations, the RF power supply RF1 is connected to the input of the second matching circuit M2 and the RF power supply RF2 is connected to the input of the first matching circuit M1, which does not affect the implementation of the object of the present invention.

As shown in FIG. 4, the pattern 101 is a plasma concentration distribution curve in the prior art. It can be seen from the figure that the plasma concentration starts to decrease at the edge of the substrate (at 150 mm), which affects the uniformity of the plasma treatment, and the application of the present invention The special power supply circuit shown in FIG. 3 not only applies the source RF power with higher frequency and the bias RF power with lower frequency to the pedestal 33 below the substrate, but also one of the RF power sources, such as A source RF power source is applied to the edge compensation ring 32 that surrounds the periphery of the substrate. The amount of power output to the edge compensation loop can be adjusted by adjusting the size of the distribution capacitor to adjust the plasma concentration formed by the electric field generated in the edge compensation loop. As shown by 103 in Fig. 4, the plasma concentration distribution generated by the edge compensation ring is complementary to the plasma concentration distribution curve generated in the susceptor, and the superposition of the two can produce a more uniform plasma distribution. When the bias RF power is applied to the electrode in the edge compensation loop, although the plasma concentration distribution cannot be directly changed, the thickness of the sheath can be changed, and the thickness of the sheath can also change the morphology of the plasma. The distribution of the plasma can also be partially changed even when the concentration is constant. At the same time, when the method of the invention is used, since the thickness of the sheath layer is adjustable, and the radio frequency phase applied to the edge compensation ring can also be different from that applied to the susceptor, the ion incident angle and energy of the edge region of the substrate can be greatly changed, thereby improving The edge region of the substrate is etched such that the via holes are not vertical.

Since the present invention additionally adds an RF electrode to the edge region and transmits RF power, more heat is generated in the edge region than in the prior art, and a higher concentration of the plasma in the edge region also heats the adjustment of the surface of the pedestal. Ring 36, ultimately causing the regulation ring 36 to overheat, affects the uniformity of the plasma treatment. The electrode 321 in the edge compensation ring below the adjustment ring 36 is simultaneously connected to the high voltage DC power source DC2, so that the edge compensation ring 32 forms an electrostatic clamp ring, and the adjustment ring 36 is closely attached to the upper surface of the edge compensation ring, and more Heat is conducted to the base below and is guided away. In the prior art, since there is no additional clamping device, there is only gravity between the adjusting ring 36 and the edge compensating ring 32 to make the contact faces of the two close to each other, but since the adjusting ring is not heavy, the actual contact surface between the two is There are a large number of voids on the surface, and only some of the regions are in direct contact and have high thermal conductivity. Since these contact areas are related to the flatness of the contact surface between the adjustment ring 36 and the compensation ring 32, and the two parts cannot achieve a very uniform flatness during processing, between the two plasma processing devices The distribution of the contact area over the entire lower surface of the adjustment ring 36 is different, so the temperature distribution of the adjustment ring on the different plasma processing devices is also slightly different. The application of the high-voltage direct-current power supply in the edge compensation ring of the present invention enables a large force to be applied between the adjustment ring and the edge compensation ring 32, thereby greatly increasing the heat conduction efficiency between the two. Optionally, in order to further increase the heat conduction efficiency, a cooling gas such as helium gas may be introduced between the two bonding surfaces, and excess heat is carried by the flowing cooling gas. Cooling gas may enter the upper surface of the compensating ring 32 from bottom to top through the edge compensating ring 32. Since the electrostatic suction force is applied downward, the air pressure of the cooling gas can be selected to be large, and the adjustment ring 36 disposed above is not lifted up.

2b is an enlarged structural view of the susceptor 33 according to the second embodiment of the present invention. The insulating material ring 52 and the insulating ring 58 are made of the same insulating material as the material of the first embodiment, but have different shapes and are surrounded by Around the protrusion of the base 33, the top surface and the side surface of the protrusion are covered. A cover ring 35 covers the periphery of the insulating material ring 52 and the insulating ring 58. The cover ring 35 includes an annular flat plate extending in the lower vertical side wall and the upper direction. An intermediate ring 37 surrounds the outside of the cover ring 35, and a conductive cover The cover layer 39 is wrapped around the outside of the base. Wherein the cover ring includes an electrode extending inwardly within the top plate. The adjustment ring 36 is placed on the cover ring 35. In the second embodiment of the present invention, the edge-compensated RF electric field and the DC voltage for electrostatic adsorption are applied to the electrode 351 in the cover ring 35, since the electrode 351 and the susceptor 33 have an insulating material ring 52 and an insulating ring 58 therebetween. Isolation is so that the electrodes in the electrode 351 are not easily affected by the RF electric field generated in the pedestal, and the individual control of the output RF power can be realized.

Although the present invention has been disclosed above, the present invention is not limited thereto. Any changes and modifications may be made without departing from the spirit and scope of the invention, and the scope of the invention should be determined by the scope of the claims.

1‧‧‧reaction chamber
101‧‧‧ graphics
103‧‧‧ Plasma concentration distribution
20‧‧‧Isolation circuit
30‧‧‧Substrate
32‧‧‧Edge compensation ring
321‧‧‧electrode
33‧‧‧Base
34‧‧‧Electrostatic chuck
35‧‧‧ Coverage ring
351‧‧‧electrode
36‧‧‧Adjustment ring
37‧‧‧Intermediate ring
38‧‧‧Insulation ring
39‧‧‧ Conductive mask
40‧‧‧ gas sprinkler
50‧‧‧External air source
52‧‧‧Insulation ring
58‧‧‧Insulation ring
A‧‧‧ output
B‧‧‧output
C1‧‧‧ fixed capacitor
C2‧‧‧second capacitor
C3‧‧‧ third capacitor
Ca‧‧‧Distribution capacitor
Cv1‧‧‧Variable Capacitor
Cv2‧‧‧Second variable capacitor
DC1‧‧‧DC power supply
DC2‧‧‧ DC power supply
L1‧‧‧Inductance
L2‧‧‧second inductance
L3‧‧‧ third inductance
L4‧‧‧Inductance
Lp‧‧‧ output
M1‧‧‧ matching circuit
M2‧‧‧ matching circuit
RF filter‧‧‧RF filter circuit
RF1‧‧‧RF power supply
RF2‧‧‧RF power supply
S0‧‧‧Switching circuit

1 is a schematic structural view of a semiconductor processing apparatus of the prior art; FIG. 2a is a pedestal structure diagram of a first embodiment having an edge compensation ring of the present invention; FIG. 2b is a pedestal structure diagram of a second embodiment having an edge compensation ring of the present invention; Figure 3 is a circuit diagram showing the supply of radio frequency and direct current power to the susceptor and the edge compensation ring of the present invention; and Figure 4 is a graph showing the plasma concentration distribution after the application of the present invention.

30‧‧‧Substrate

32‧‧‧Edge compensation ring

321‧‧‧electrode

33‧‧‧Base

34‧‧‧Electrostatic chuck

36‧‧‧Adjustment ring

38‧‧‧Insulation ring

39‧‧‧ Conductive mask

A‧‧‧ output

B‧‧‧output

Claims (10)

A plasma processing apparatus comprising: a reaction chamber, the reaction chamber includes a base, the base is provided with an electrostatic chuck, and the substrate to be processed is disposed on the electrostatic chuck; an adjusting ring surrounds the static electricity An edge compensation ring surrounds the periphery of the susceptor or the electrostatic chuck and is located under the adjustment ring; wherein: an edge is embedded in the edge compensation ring; a power distribution circuit passes through the first The second input receives the first and second RF power sources and outputs the first and second RF power sources to the base through the first output terminal, and outputs the first or second RF power source to the second output terminal The electrode in the edge compensation loop; the power distribution circuit further includes a third input receiving the first DC power, and outputting the DC voltage to the electrode in the edge compensation ring through the second output. The plasma processing apparatus of claim 1, wherein the power distribution circuit includes a fourth input receiving the second DC voltage source and outputting the second DC voltage through the first output. The plasma processing apparatus of claim 1, wherein the edge compensation ring includes a cooling gas passage that passes the cooling gas into a contact surface between the edge compensation ring and the adjustment ring. The plasma processing apparatus of claim 1, wherein the power distribution circuit comprises a plurality of matching circuits to achieve matching of the first and second RF power sources to the reaction chamber impedance. The plasmonic processing apparatus of claim 1, wherein the second output end and the first input end further comprise a switching circuit for selectively connecting the first RF power source to the second output through an inductor end. The plasma processing apparatus of claim 1, wherein the edge compensation ring is disposed on the pedestal outward extension. The plasma processing apparatus of claim 1, wherein the edge compensation ring is made of alumina. The plasma processing apparatus of claim 1, wherein the edge compensation ring is fixed to a ring of insulating material, the ring of insulating material being fixed to the outward extension of the base. The plasma processing apparatus of claim 6 or 8, wherein the outer side of the edge compensation ring further comprises an insulating ring and a conductive mask layer. The plasma processing apparatus according to claim 8, wherein the edge compensation ring includes a lower vertical side wall and an upper annular plate, and the embedded electrode extends inward from the outer side of the annular plate, the adjustment The ring is located on the annular plate.