TWI767618B - Plasma reactor and method for adjusting radio frequency power distribution - Google Patents

Abstract

The present invention provides a plasma reactor and a method for adjusting radio frequency power distribution thereof. The plasma reactor includes: a reaction chamber, the inner bottom of which is provided with a conductive base, the conductive base is connected to the first radio frequency power supply device through a first matcher circuit, an electrostatic chuck is arranged on the conductive base, and the electrostatic chuck absorbs the substrate to be treated a plasma environment on the substrate to be processed; an insertion ring, arranged around the conductive base; a focusing ring, arranged above the insertion ring, the focusing ring surrounds the electrostatic chuck and is exposed to the plasma environment; a coupling ring, including a bottom ring and the protruding part, the protruding part is located between the insertion ring and the conductive base, the bottom ring is located under the insertion ring, the gap between the inner wall of the insertion ring and the outer wall of the conductive base is greater than 0.02 mm and less than 10 mm; the device board is located below the conductive base; A wire with a first end electrically connected to the conductive base or device board and a second end electrically connected to the insertion ring, with the variable impedance device connected in series with the wire. The radio frequency of the plasma reactor is adjustable and can reduce arcing.

Description

Plasma reactor and method for adjusting radio frequency power distribution

The invention relates to the technical field of semiconductor processing, in particular to a plasma reactor and a method for adjusting radio frequency power distribution thereof.

Semiconductor wafers are increasingly used in various electronic devices, wherein semiconductor wafer processing requires the use of a large number of plasma reactors for performing plasma etching or chemical vapor deposition processes on substrates to be treated. 1a is a typical plasma reactor, including: a reaction chamber 10, the top of the reaction chamber 10 includes an insulating material window, an inductive coil 7 is arranged above the insulating material window, and the inductive coil 7 is connected to a high The radio frequency (13MHz and above) radio frequency power supply 6 also includes at least one reaction gas source 11 to send the reaction gas into the reaction chamber through the valve 95 and the gas shower head 90 to form plasma to etch the substrate. The bottom of the reaction chamber 10 includes a base 20. The base 20 is connected to a bias RF source 4 through a bias RF power matcher 5, wherein the low frequency RF frequency output by the bias RF source 4 is generally lower than 2 MHz. The base 20 is usually anodized on the surface of an aluminum alloy to form an anodized layer, or an insulating corrosion-resistant material layer is coated on the surface of the aluminum alloy to avoid a series of problems such as being corroded by the etching gas in the reaction chamber 10 and causing particle pollution and the like . An electrostatic chuck 21 is provided on the upper surface of the base 20 for fixing the substrate 22 . The periphery of the lower part of the base 20 also includes a protruding step part, and a coupling ring 25 is arranged on the step part. The coupling ring 25 is provided with a poly A focus ring 23, wherein the inner wall of the focus ring 23 surrounds and is close to the substrate 22, and the upper surface of the focus ring 23 is exposed to the plasma above. Since the focus ring 23 is exposed to the plasma for a long time, the surface material of the focus ring 23 will inevitably be corroded after a period of plasma treatment, so the height of the focus ring 23 will decrease accordingly, which will seriously affect the edge of the substrate The distribution and shape of the regional sheath layer can easily cause the difference in etching rate and edge tilting between the edge region of the substrate and the central region of the substrate, reducing the processing uniformity of the substrate and affecting the yield of the final wafer.

Fig. 1b is a schematic diagram of the low frequency radio frequency power distribution in the plasma processor in Fig. 1a, please refer to Fig. 1b, the input low frequency radio frequency power P0 is coupled to P1' through the equivalent capacitance C11 between the base 20 and the substrate 22 (see Fig. 1a). The power goes to the substrate, and is coupled P2 ′ to the focus ring 25 through the equivalent capacitance C12 of the base 20 to the coupling ring 25 and the focus ring 23 . The value of the equivalent capacitance C12 is difficult to adjust, so P2' will be much smaller than P1' and the power ratio is difficult to adjust.

In addition, with the conventional plasma reactor, the arc discharge is serious, so the industry needs to develop a new plasma reactor to dynamically and precisely adjust the RF power distribution of the low-frequency RF power in the center of the substrate and the edge of the substrate, thereby Improve the uniformity of the substrate processing process, and reduce the phenomenon of arcing. Preferably, the adjusting device needs to be simple in structure and low in cost, and can be applied to various plasma processing devices.

The invention provides a plasma reactor, which can simply and effectively adjust the radio frequency power in the edge region of the substrate, compensate the edge tilting of the substrate caused by the loss in the long-term use of the focus ring, and reduce arc discharge.

The invention discloses a plasma reactor, comprising: a reaction chamber, the inner bottom of which is provided with a conductive base, the conductive base is connected to a radio frequency power supply device through a matching circuit, the An electrostatic chuck is arranged on the conductive base, and the upper surface of the electrostatic chuck is used for adsorbing the substrate to be processed, and the reaction chamber above the substrate to be processed is a plasma environment; an insert ring is arranged around the conductive base the periphery of the seat; a focus ring, disposed above the insert ring, the focus ring surrounding the electrostatic chuck and exposed to the plasma environment; a coupling ring, including a bottom ring and a protrusion, the protrusion The outgoing part is located between the insertion ring and the conductive base, the bottom ring is located below the insertion ring and the protruding part, and the gap between the inner side wall of the insertion ring and the outer side wall of the conductive base is greater than 0.02 mm less than 10 mm; equipment board, located under said conductive base; wire, its first end is electrically connected to said conductive base or equipment board, its second end is electrically connected to said insert ring, variable impedance device is connected in series on the wire.

Preferably, the frequency range of the radio frequency signal output by the radio frequency power supply device is 10KHz~300MHz.

Preferably, the conductive base and the coupling ring also have a transmission pin hole penetrating the conductive base and the coupling ring; the wire between the variable impedance device and the insertion ring is also connected in series with an adapter and a transmission pin, so The transmission pin is electrically connected with the insertion ring, the transmission pin is located in the transmission pin hole, and an insulating sleeve is provided on the outer casing of the transmission pin; the adapter is located below the equipment board.

Preferably, a ring-shaped RF buffer is also arranged between the variable impedance device and the adapter, the ring-shaped RF buffer is located under the device board, and the variable impedance device is connected to the ring-shaped RF buffer through a wire. The number of the adapters is at least one; when the number of the adapters is more than one, the multiple adapters are evenly distributed along the circumferential direction of the annular radio frequency buffer and are all electrically connected to the annular distributor. The adapters are electrically connected to different regions of the insert ring through different transmission pins.

Preferably, the variable impedance device is located on the central axis of the insertion ring, and the number of the adapters is at least one; when the number of the adapters is more than one, the variable impedance device passes through. A plurality of wires are respectively electrically connected to each of the adapters, and each of the adapters is electrically connected to different regions of the insertion ring through different transmission pins.

Preferably, the outer sidewall of the conductive base includes at least one layer of insulating material resistant to plasma corrosion.

Preferably, the material of the plasma corrosion-resistant insulating material layer includes aluminum oxide or yttrium oxide.

Preferably, the variable impedance device shown includes at least one variable impedance device or variable inductance.

Preferably, the variable impedance device is located in the atmospheric environment below the device board.

Preferably, the side wall of the reaction chamber is composed of ground metal, the ground metal surrounds to form an electric field shield space, and the variable impedance device is located in the electric field shield space.

Preferably, the material of the coupling ring includes: at least one of silicon oxide or aluminum oxide.

Preferably, there is a gap between the protruding portion and the conductive base.

Preferably, the gap between the protruding portion and the conductive base is less than 3 mm.

Preferably, the material of the focus ring includes: conductor material or semiconductor material, no insertion ring is provided between the focus ring and the coupling ring; the second end of the wire is electrically connected to the focus ring.

Preferably, the bottom of the focus ring is coated with a conductive layer, and no insertion ring is provided between the focus ring and the coupling ring; the second end of the wire is electrically connected to the conductive layer.

Preferably, the insertion ring is embedded in the coupling ring or in the focusing ring.

Preferably, it also includes: a gas shower head, located at the top of the reaction chamber, the gas shower head is arranged opposite the conductive base, and is used to deliver the reaction gas into the reaction chamber, and the reaction gas is in the radio frequency power supply. Plasma is formed under the action of the device.

Correspondingly, the present invention also provides a method for adjusting the radio frequency power distribution of the above-mentioned plasma reactor. If the etching hole on the edge of the substrate is inclined beyond the preset angle, enter the variable impedance device adjustment step; the variable impedance adjustment step: adjust the impedance parameters of the variable impedance device, The RF power delivered to the focus ring at the edge of the substrate is changed, and the step of monitoring the etching effect of the substrate is entered again.

Compared with the prior art, the technical solution of the present invention has the following beneficial effects: in the plasma reactor provided by the present invention, the first end of the wire is electrically connected to the conductive base or the device board, and the second end of the wire is electrically connected To the insertion ring, a variable impedance device is connected in series with the wire. Since the gap between the inner sidewall of the insertion ring and the outer sidewall of the conductive base is greater than 0.02 mm, so that the gap between the inner sidewall of the insertion ring and the outer sidewall of the conductive base is not too small, the coupling to the focusing The radio frequency power on the ring will not be too large, so by adjusting the capacitance value of the variable impedance device, the radio frequency power delivered to the focus ring can be effectively adjusted, thereby changing the height of the sheath above the focus ring, so that the Treating the central area of the substrate with a sheath having the same height above the focus ring is beneficial for improving etch uniformity. At the same time, the inside of the insert ring The gap between the wall and the outer side wall of the conductive base is less than 10 mm, so that the gap between the inner side wall of the insert ring and the outer side wall of the conductive base is not too large, so that the radio frequency power reaches the center area of the substrate to be processed and The difference in phase difference reaching above the focus ring is small, which is beneficial to reduce arcing.

10,100: reaction chamber

11: Reactive gas source

120: Conductive base

121,21: Electrostatic chuck

122: substrate to be processed

123, 123', 23: focus ring

124: Variable Impedance Device

125,25: Coupling Ring

125a: Bottom ring

125b: Projection

126: Equipment board

127: Insert Ring

128: Wire

130: Gas sprinkler head

140: Transmission pin hole

141: Adapter

142: Transmission pin

145: Ring RF Buffer

146: Insulating sleeve

190: Conductive layer

20: Pedestal

22: Substrate

4: Bias RF source

40: RF power supply unit

5: Bias RF power matcher

50: Matcher

6: High frequency RF power supply

7: Inductor coil

8: RF matcher

90: Gas nozzle

95: Valve

C11, C12, C21, C22: Equivalent capacitance

Fig. 1a is a schematic structural diagram of a plasma processor in the prior art; Fig. 1b is a schematic diagram of a low frequency radio frequency power distribution in the plasma processor of Fig. 1a; Fig. 2 is a schematic structural diagram of a plasma processor of the present invention; Fig. 3 is a plasma processor of Fig. 2 Figure 4 is a schematic diagram of the cross-sectional structure along the line A-A1 of Figure 3; Figure 5 is a schematic diagram of the radio frequency power distribution in the plasma processor of Figure 2; Figure 6 is another type of adjustment device in the plasma processor of Figure 2 Figure 7 is a schematic structural diagram of another embodiment of the plasma processor of the present invention; Figure 8 is a schematic structural diagram of another embodiment of the plasma processor of the present invention; Figure 9 is a schematic diagram of another embodiment of the plasma processor of the present invention; FIG. 10 is a flow chart of the method for adjusting the radio frequency power distribution of the plasma processor of the present invention.

The present invention proposes a new plasma reactor, comprising: a reaction chamber, the inner bottom of which is provided with a conductive base, the conductive base is connected to a radio frequency power supply device through a matching circuit, and an electrostatic clip is arranged on the conductive base The upper surface of the electrostatic chuck is used for adsorbing the substrate to be processed, and the reaction chamber above the substrate to be processed is a plasma environment; an insertion ring is arranged around the periphery of the conductive base; a focusing ring is arranged Above the insert ring, the focus ring surrounds the electrostatic chuck and is exposed to the plasma environment; a coupling ring, including a bottom ring and a protrusion the protruding part is located between the insertion ring and the conductive base, the bottom ring is located below the insertion ring and the protruding part, and between the inner side wall of the insertion ring and the outer side wall of the conductive base The gap is greater than 0.02 mm and less than 10 mm; the device board is located under the conductive base; the wire, the first end of which is electrically connected to the conductive base or the device board, and the second end of which is electrically connected to the insertion ring, A variable impedance device is connected in series with the wire. The radio frequency of the plasma reactor is adjustable and reduces the risk of arcing.

In order to make the above objects, features and beneficial effects of the present invention more clearly understood, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 2 is a schematic diagram of a plasma processor of the present invention.

Please refer to FIG. 2 , the inner bottom of the reaction chamber 100 is provided with a conductive base 120 , the conductive base 120 is electrically connected to the radio frequency power supply device 40 through the matching device 50 , and the conductive base 120 is provided with an electrostatic chuck 121 , the upper surface of the electrostatic chuck 121 is used for adsorbing the substrate 122 to be processed, and the reaction chamber 100 above the substrate 122 to be processed is a plasma environment; a ring 127 is inserted around the periphery of the conductive base 120 ; a focus ring 123, disposed above the insert ring 127, the focus ring 123 surrounding the electrostatic chuck 121 and exposed to the plasma environment; a coupling ring 125, including a bottom ring 125a and a protrusion 125b , the protruding portion 125b is located between the inserting ring 127 and the conductive base 120, the bottom ring 125a is located below the inserting ring 127 and the protruding portion 125b, and the inner sidewall of the inserting ring 127 is connected to the conductive base 120. The gap between the outer side walls of the base 120 is greater than 0.02 mm and less than 10 mm; the device board 126 is located under the conductive base 120 ; the first end of the wire 128 is electrically connected to the conductive base 120 or the device board 126 , the second end of which is electrically connected to the insertion ring 127 , and the variable impedance device 124 is connected to the wire 128 in series.

In this embodiment, the plasma reactor is a capacitively coupled plasma processor (CCP), and the capacitively coupled plasma processor further includes: a gas shower head 130 located on the top of the reaction chamber 100, the gas The shower head 130 is disposed opposite to the conductive base 120 and is used to deliver the reaction gas into the reaction chamber 100, and the reaction gas forms plasma under the action of the radio frequency power supply device 40; the gas shower head 130 serves as a capacitively coupled plasma The upper electrode of the processor, the conductive base 120 is used as the lower electrode.

In other embodiments, the plasma reactor is an Inductively Coupled Plasma Processor Outer (ICP), and the Inductively Coupled Plasma Processor Outer (ICP) includes: an insulating window at the top of the reaction chamber; Inductor coil on window.

In the capacitively coupled plasma processor, high-frequency power (above 13.56Mhz, such as 27MHz, 60MHz, etc.) can be delivered to the conductive base 120 as the lower electrode, and the upper electrode is electrically grounded at this time, and the above-mentioned high-frequency power can also be delivered To the upper electrode, the high-frequency power is used to convert the reactive gas into plasma, and the plasma is used to perform plasma treatment on the substrate to be treated. The capacitively coupled plasma processor further includes: low frequency power applied to the lower electrode for deflecting the plasma toward the surface of the wafer to be processed.

In this embodiment, the insertion ring 127 is arranged above the bottom ring 125a, the focusing ring 123 is arranged on the insertion ring 127, one end of the wire 128 is electrically connected to the insertion ring 127, and the other end is electrically connected to the conductive base 120 , a variable impedance device 124 is also connected in series in the middle of the wire 128 . Since the gap between the inner side wall of the insertion ring 127 and the outer side wall of the conductive base 120 is greater than 0.02 mm, the gap between the inner side wall of the insertion ring 127 and the outer side wall of the conductive base 120 will not be too small, Then, the amount of RF power coupled to the focus ring 123 will not be too much. Therefore, the RF power delivered to the focus ring 123 can be adjusted by adjusting the capacitance value of the variable impedance device 124. At the same time, the gap between the inner side wall of the insertion ring 127 and the outer side wall of the conductive base 120 is less than 10 mm, so that the gap between the inner side wall of the insertion ring 127 and the outer side wall of the conductive base 120 is less than 10 mm. If it is too large, it is beneficial to reduce the discharge phenomenon between the insertion ring 127 and the conductive base 120 . Moreover, after the gap between the insertion ring 127 and the conductive base 120 is used to accommodate the protruding portion 125b of the coupling ring 125, there is still a small gap between the protruding portion 125b and the conductive base 120. Specifically, The gap between the protruding portion 125b and the conductive base 120 is less than 3 mm, and the gap between the protruding portion 125b and the conductive base 120 is also beneficial to allow the protruding portion 125b and the conductive base 120 to change in temperature There is enough room for expansion to occur.

A protruding portion 125b is provided between the insertion ring 127 and the conductive base 120, so that the gap between the protruding portion 125 and the conductive base 120 is small, which is beneficial to reduce the phenomenon of arc discharge.

In addition, the protruding portion 125b is provided between the insertion ring 127 and the conductive base 120, so that the distance between the insertion ring 127 and the conductive base 120 not only includes the distance between the protruding portion 125b and the conductive base 120 The gap between the protruding parts 125b and the height of the protruding part 125b also includes the top size of the protruding part 125b and the height of the protruding part 125b. When the gap between the protruding part 125b and the conductive base 120 at different phase angles changes slightly The distance difference between the insertion ring 127 and the conductive base 120 is small, and the capacitance difference between the insertion ring 127 and the conductive base 120 at different phase angles is small, so it is beneficial to reduce the asymmetry problem at different phase angles .

The material of the insert ring 127 is a conductive material, such as aluminum or graphite. The insertion ring 127 can be a complete ring, or can be divided into a plurality of arc segments, which together form the insertion ring 127, and there are gaps or isolation parts between each arc segment to achieve electrical isolation from each other.

The variable impedance device 124 includes a variable inductance, a hybrid circuit composed of capacitors, or a circuit composed of other components to realize the function of impedance adjustment, such as a motor capacitor.

The variable impedance device 124 is arranged in the vacuum space under the conductive base 120, and the variable impedance device 124 can also be arranged in the atmospheric environment under the equipment plate 126 in the reaction chamber, as long as both ends of the wire 128 pass through the equipment The plate 126 and the variable impedance device 124 arranged in the atmospheric environment are easier to dissipate heat and maintain. In addition, the variable impedance device 124 is disposed immediately below the device board 126, so that the length of the wire 128 is short to ensure that the phase of the RF signal applied to the conductive base 120 and that applied to the insertion ring 127 is approximately the same, so that the The central and edge regions obtain approximately the same DC potential, enabling uniform processing of the central and edge regions of the substrate. The wall of the reaction chamber 100 is made of grounded metal, and the grounded metal is surrounded to form an electric field shielding space. The variable impedance device 124 can be avoided even in the atmospheric environment below the equipment board 126 in the electric field shielding space of the reaction chamber. The variable impedance device 124 radiates a low frequency electric field to the external environment. Compared with the necessity of disposing liquid inlet and outlet pipes and mechanical driving devices in the coupling ring 125, the variable impedance device 124 is small in size, low in cost, and simple in installation structure.

The plasma processor further includes an adapter and a transmission pin. The variable impedance device 124 , the adapter and the transmission pin constitute an adjustment device. The adjustment device will be described in detail below with reference to FIGS. 3 and 4 : please refer to FIGS. 3 and 4 4 is a schematic diagram of the cross-sectional structure of FIG. 3 along the line A-A1, the conductive base 120 and the coupling ring 125 also have a transmission pin hole 140 (see FIG. 4) that penetrates the conductive base 120 and the coupling ring 125; the An adapter 141 electrically connected to the variable impedance device 124 and a transmission pin 142 are also connected in series on the wire 128 between the variable impedance device 124 and the insertion ring 127. The transmission pin 142 is electrically connected to the insertion ring 127, and the transmission Pin 142 is located in the transmission pin hole 140 Inside, the transmission pin 142 is provided with an insulating sleeve 146 (see FIG. 4 ); the adapter 141 is located below the device board 126 .

FIG. 5 is a schematic diagram of the radio frequency power distribution in the plasma processor in FIG. 2 .

No matter the frequency of the radio frequency power supply device 40 is high or low, the equivalent capacitance C21 coupled to the substrate to be processed 122 is large, but: when the frequency of the radio frequency power supply device 40 is 10KHz~13.56MHz, the conductive The equivalent capacitance C22 from the base 120 to the focus ring 123 through the sidewall corrosion-resistant insulating layer and the coupling ring 125 is relatively small, and cannot transmit high-power radio frequency power. The variable impedance device 124 does not transmit the radio frequency power through the traditional coupling method, but directly guides the radio frequency power in the conductive base 120 to the lower surface of the target focusing ring 123 by means of direct electrical connection, thus bypassing serious problems. Impedance affecting the coupling of low frequency RF power. The variable impedance device 124 can select the value range and adjustment range according to the needs. The variable impedance device 124 can effectively adjust the RF power delivered to the focus ring 123 by simply adjusting the capacitance value, thereby changing the focus The height of the sheath above the ring 123 is such that the central area of the substrate to be processed has the same height as the sheath above the focus ring 123, thus, it is beneficial to improve the uniformity of etching.

When the frequency of the radio frequency power supply device 40 is 10KHz~13.56MHz, in an embodiment, the number of the adapters 141 is one, the number of the transmission pins 142 is also one, and the variable The impedance device 124 is electrically connected to the insertion ring 127 through the adapter 141 and the transmission pin 142 in turn. Since the frequency of the radio frequency power supply device 40 is relatively small, the radio frequency power is input to the insertion ring 127 through an adapter 141 and a transmission pin 142, and the radio frequency power drop is less, which can meet the requirements, and there will be no asymmetry in different phase angles. .

When the frequency of the radio frequency power supply device 40 is 10KHz~13.56MHz, in another embodiment, the number of the adapters 141 is plural, the number of the transmission pins 142 is also plural, and one adapter 141 is electrically connected to the different areas of the insertion ring 127 through a transmission pin 142 . The RF power is input to the insertion ring 127 through the plurality of adapters 141 and the transmission pins 142, the RF power drop is less, the requirements are better met, and there is no asymmetry in different phase angles.

In this embodiment, when the number of the adapters 141 is multiple, a ring-shaped radio frequency buffer 145 (see FIG. 3 ) is further included between the variable impedance device 124 and the adapter 141 . 145 is located under the device board 126 (see FIG. 2 ), and the variable impedance device 124 is located under the edge area of the device board 126. The variable impedance device 124 is electrically connected to the annular RF buffer 145 through a wire 128. connected, the annular RF buffer 145 is electrically connected to the adapter 141 . The plurality of adapters 141 are evenly distributed along the circumferential direction of the annular radio frequency buffer member 145 , and the annular radio frequency buffer member 145 is used for buffering radio frequency.

When the frequency of the radio frequency power supply device 40 is 13.56MHz~300MHz, the equivalent capacitance C22 from the conductive base 120 to the focus ring 123 through the sidewall corrosion-resistant insulating layer and the coupling ring 125 is relatively large, but not too large, so , by adjusting the size of the variable impedance device 124, the RF power delivered to the focus ring 123 can be adjusted to change the height of the sheath at the focus ring 123, so that the central area of the substrate to be processed is close to the focus ring 123. There is a sheath of the same height above, therefore, it is beneficial to improve the etch uniformity.

When the frequency of the RF power supply device 40 is 13.56MHz to 300MHz, the number of the adapters 141 is plural, the number of the transmission pins 142 is also plural, and one adapter 141 passes through one transmission pin 142 The insertion ring 127 is electrically connected. Via multiple adapters 141 and transfer pins 142 inputs the radio frequency power to the insertion ring 127, and the radio frequency power drops less, which can meet the requirements, and there will be no asymmetry in different phase angles.

In an embodiment, an annular RF buffer 145 is further included between the variable impedance device 124 and the adapter 141 , the annular RF buffer 145 is located under the device board 126 , and the variable impedance device 124 passes through A wire 128 is electrically connected to the annular radio frequency buffer 145 , the plurality of adapters 141 are evenly distributed along the circumferential direction of the annular radio frequency buffer 145 , and the annular radio frequency buffer 145 is used for buffering radio frequency.

It should be noted that: when the number of the variable impedance devices 124 is one, all the adapters 141 are electrically connected to the variable impedance device 124; when the number of the variable impedance devices 124 is multiple, When the number of the adapters 141 is multiple, different adapters 141 can be electrically connected to different variable impedance devices 124 .

Meanwhile, the gap between the inner sidewall of the insertion ring 127 and the outer sidewall of the conductive base 120 is less than 10 mm, so that the difference in the phase difference between the radio frequency power reaching the central area of the substrate to be processed 122 and reaching the top of the focusing ring 123 is small. , which helps reduce the risk of arcing.

FIG. 6 is a top view along the X direction of another adjusting device in the plasma processor of FIG. 2 .

Referring to FIG. 6 , the variable impedance device 124 is located on the central axis of the insertion ring 127 (see FIG. 2 ). They are respectively electrically connected with each of the adapters 141 .

In other embodiments, the number of the adapters is one.

In this embodiment, if there is enough space under the equipment plate 126 to place the adjusting device, the adjusting device is placed on the central axis of the inserting ring 127, A wire 128 electrically connects the variable impedance device 124 and each of the adapters 141, and the phase difference difference between the variable impedance device 124 and each of the adapters 141 is smaller, which is beneficial to further reduce the occurrence of arc discharge risks of.

FIG. 7 is a schematic structural diagram of another embodiment of the plasma processor of the present invention.

Referring to FIG. 7 , the bottom of the focus ring 123 is coated with a conductive layer 190 , one end of the variable impedance device 124 is connected to the conductive base 120 , and the other end is connected to the conductive layer 190 .

In this embodiment, since the gap between the conductive layer 190 and the conductive base 120 is not too small, so that the RF power coupled to the focus ring 123 is not too large, the variable impedance device 124 can be adjusted by adjusting the It can effectively adjust the RF power delivered to the focus ring 123, and change the height of the sheath above the focus ring 123, so that the central area of the substrate to be processed has the same height as the sheath above the focus ring 123, which improves etching. uniformity. At the same time, the gap between the inner sidewall of the conductive layer 190 and the outer sidewall of the conductive base 120 is less than 10 mm, so that the difference between the phase difference between the radio frequency power reaching the central area of the substrate to be processed and the phase difference reaching the top of the focusing ring 123 is small, Helps to reduce the risk of arcing.

FIG. 8 is a schematic structural diagram of another embodiment of the plasma processor of the present invention.

In this embodiment, the material of the focus ring 123 ′ includes: conductor material (eg, aluminum, etc.) or semiconductor material (eg, silicon or silicon carbide, etc.). The focus ring 123 ′ serves as the insertion ring 127 of the present invention, Therefore, there is no need to additionally dispose the insertion ring 127, so the second end of the wire 128 is directly connected to the focus ring 123' at this time.

In this embodiment, since the gap between the focus ring 123' and the conductive base 120 is not too small, so that the RF power coupled to the focus ring 123' is not too large, the variable impedance can be adjusted by adjusting the variable impedance. The capacitance value of the device 124 can effectively adjust the transmission to the focus ring The RF power of 123' changes the height of the sheath above the focus ring 123', so that the central area of the substrate to be processed has the same height of the sheath as the top of the focus ring 123', which is beneficial to improve the uniformity of etching. At the same time, the gap between the inner sidewall of the focusing ring 123' and the outer sidewall of the conductive base 120 is less than 10 mm, so that the difference in phase difference between the radio frequency power reaching the central area of the substrate to be processed and reaching the top of the focusing ring 123' is relatively small. small, which is beneficial to reduce the risk of arcing.

FIG. 9 is a schematic diagram of another embodiment of the plasma processor of the present invention.

2 The value of the variable impedance device 124 is shown, but it is also much larger than C12 in the prior art shown in FIG. 1 . Therefore, by adjusting the size of the variable impedance device 124 , the magnitude of the RF power delivered to the focus ring 123 can be adjusted. , to change the height of the sheath at the focus ring 123, so that the central area of the substrate to be processed and the top of the focus ring 123 have a sheath of the same height, thereby improving the etching uniformity.

In other embodiments, the insertion ring 127 is embedded in the focus ring 123 .

FIG. 10 is a flow chart of the method for adjusting the radio frequency power distribution of the plasma processor of the present invention.

Please refer to FIG. 10, step S1: substrate etching effect monitoring step: detecting the etching effect in the edge area of the substrate, if the inclination angle of the etching hole at the edge of the substrate is within the preset angle range, then continue to perform the substrate etching effect monitoring step, if If the etching hole on the edge of the substrate is inclined beyond the preset angle, the variable impedance device adjustment step is entered; Step S2: the variable impedance adjustment step: the impedance parameter of the variable impedance device is adjusted so that the variable impedance device is transported to the edge of the substrate. The RF power is changed, and the substrate etching effect monitoring step is entered again.

When the reaction chamber is in the initial state, the variable impedance device is at the initial value. After a long time of plasma treatment, it is detected that the processing effect of the edge area of the substrate is different from that of the center. The controller can automatically change the variable impedance device in real time according to the set parameters. , so that more low-frequency RF power is delivered to the focus ring on the edge of the substrate, and then the height of the sheath at the focus ring is changed, so that the central area of the substrate to be processed has the same height as the sheath above the focus ring, improving etching uniformity sex. Among them, the most typical processing effect is the edge tilting of the etching hole in the edge area of the substrate. Once the upper surface of the focus ring is not lost, the height will decrease, and the sheath layer in the edge area will be reduced accordingly. The etched holes exhibit an inclination angle that slopes inward. Continue to detect the effect of the substrate processing until the uniformity of the processing effect again shifts beyond the preset threshold, and adjust the capacitance value of the variable impedance device again according to the detected data. In this way, the present invention can maintain the stability of the plasma effect for a long time without changing the focus ring for a long time, only need to change the parameter setting of the variable impedance device without liquid pipeline or mechanical driving device in the vacuum environment.

Although the content of the present invention has been described in detail by way of the above preferred embodiments, it should be appreciated that the above description should not be construed as limiting the present invention. Various modifications and substitutions to the present invention will become apparent to those of ordinary skill in the art upon reading the foregoing disclosure. Therefore, the protection scope of the present invention should be defined by the appended claims.

S1, S2: Steps

Claims (18)

A plasma reactor, comprising: a reaction chamber, the inner bottom of which is provided with a conductive base, the conductive base is connected to a radio frequency power supply device through a matching circuit, and an electrostatic chuck is arranged on the conductive base, The upper surface of the electrostatic chuck is used for adsorbing a substrate to be processed, and the reaction chamber above the substrate to be processed is a plasma environment; an insert ring is arranged around the periphery of the conductive base, the insert ring The gap between the inner sidewall of the conductive base and the outer sidewall of the conductive base is greater than 0.02 mm and less than 10 mm; a focus ring is arranged above the insert ring, the focus ring surrounds the electrostatic chuck and is exposed to the plasma environment ; a coupling ring, including a bottom ring and a protruding part, the protruding part is located between the insert ring and the conductive base, the bottom ring is located below the insert ring and the protruding part; a device board, Below the conductive base; a wire, the first end of which is electrically connected to the conductive base or the device board, the second end of which is electrically connected to the insertion ring, and a variable impedance device is connected in series on the wire. The plasma reactor of claim 1, wherein the frequency range of the radio frequency signal output by the radio frequency power supply device is: 10KHz~300MHz. The plasma reactor of claim 1, wherein the conductive base and the coupling ring further have a transmission pin hole passing through the conductive base and the coupling ring; between the variable impedance device and the insertion ring The wire is also connected in series with an adapter and a transmission pin, the transmission pin is electrically connected with the insertion ring, the transmission pin is located in the transmission pin hole, and an insulating sleeve is provided on the outer casing of the transmission pin; the adapter is located on the device board below. The plasma reactor of claim 3, wherein the variable impedance device A ring-shaped radio frequency buffer is also arranged between the adapter and the ring-shaped radio frequency buffer. The ring-shaped radio frequency buffer is located below the equipment board. The variable impedance device is electrically connected to the ring-shaped radio frequency buffer through a wire. The number of the adapter is at least 1; when the number of the adapters is multiple, the multiple adapters are evenly distributed along the circumferential direction of the annular radio frequency buffer and are all electrically connected to an annular distributor, and each of the adapters is electrically connected through different transmission pins to different regions of the insertion loop. The plasma reactor of claim 3, wherein the variable impedance device is located on the central axis of the insertion ring, and the number of the adapters is at least one; when the number of the adapters is multiple, the The variable impedance device is electrically connected to each of the adapters through a plurality of the wires, and each of the adapters is electrically connected to different regions of the insertion ring through different transmission pins. The plasma reactor of claim 1, wherein the outer sidewall of the conductive base includes at least one layer of insulating material resistant to plasma corrosion. The plasma reactor according to claim 6, wherein the material of the insulating material layer resistant to plasma corrosion comprises: aluminum oxide or yttrium oxide. The plasma reactor of claim 1, wherein the variable impedance device comprises at least one variable capacitance or variable inductance. The plasma reactor of claim 1, wherein the variable impedance device is located in the atmosphere below the equipment board. The plasma reactor of claim 1, wherein the side wall of the reaction chamber is composed of a ground metal, the ground metal surrounds an electric field shielding space, and the variable impedance device is located in the electric field shielding space. The plasma reactor of claim 1, wherein the material of the coupling ring comprises: at least one of silicon oxide or aluminum oxide. The plasma reactor of claim 1, wherein a gap is formed between the protruding portion and the conductive base. The plasma reactor of claim 12, wherein the gap between the protruding portion and the conductive base is less than 3 mm. The plasma reactor according to claim 1, wherein the material of the focus ring comprises: conductor material or semiconductor material, the insertion ring is not provided between the focus ring and the coupling ring; the second end of the wire is electrically connected to the focus ring. The plasma reactor according to claim 1, wherein the bottom of the focus ring is coated with a conductive layer, the insertion ring is not disposed between the focus ring and the coupling ring; the second end of the wire is electrically connected to the conductive layer Floor. The plasma reactor of claim 1, wherein the insertion ring is embedded in the coupling ring or in the focusing ring. The plasma reactor according to claim 1, further comprising: a gas shower head located at the top of the reaction chamber, the gas shower head is disposed opposite the conductive base, and is used for spraying into the reaction chamber A reactive gas is delivered, and the reactive gas forms plasma under the action of the radio frequency power supply device. A method for adjusting the radio frequency power distribution of a plasma reactor according to any one of claims 1-17, comprising the following steps: a substrate etching effect monitoring step: detecting the etching effect in the edge region of the substrate, if the substrate is If the inclination angle of the edge etching hole is within the preset angle range, continue to perform the substrate etching effect monitoring step. If the substrate edge etching hole inclination exceeds the preset angle, enter the variable impedance device adjustment step; the variable impedance adjustment step: adjust The impedance parameter of the variable impedance device changes the RF power delivered to the focus ring at the edge of the substrate, and then enters the step of monitoring the etching effect of the substrate again.

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