TWI236055B - Plasma apparatus and method capable of adaptive impedance matching - Google Patents

Abstract

A plasma apparatus capable of adaptive impedance matching comprises a plasma reactor which can produce plasma to proceed with CVD (chemical vapor deposition) process, a bi-polar electrostatic chuck which locates inside the plasma reactor and is used to support and secure a wafer, an alternating current bias power supply which connects to the bi-polar electrostatic chuck supplies the voltage potential bias for ion-bombardment from plasma, and an impedance-matching circuit which connects the alternating current bias power supply to the bi-polar electrostatic chuck is used to balance the inner-electrode power output and the outer-electrode power output of the bi-polar electrostatic chuck.

Description

1236055 V. Description of the invention (1) 1. [Technical field to which the invention belongs] A device for semiconductor manufacturing, especially a bipolar electrostatic chuck in a high-density plasma chemical vapor deposition process, which can reduce gate oxide layer damage Semiconductor manufacturing equipment. 2. [Previous technology] After the main body of the Metal Oxide Semiconductor (M0S) device on the wafer is completed, the next step is to make the multiple metal conductor layers and interconnects above the M0S device. With the evolution of technology, the size of components has become smaller and smaller, so the gaps between metal conductors have become smaller and smaller, and high-aspectrati (0) gaps have been created between metal conductors, resulting in the deposition of dielectric layers between metal-to-metal gaps. It will be difficult to deposit completely and form holes in it, which will destroy the electrical properties of the components and cause wafer scrap. In order to solve the above-mentioned problem of incomplete deposition, U.S. Patent No. 6, 2 3 9, 〇18 and U.S. Patent No. 6, 2 1 8, 284 proposed the use of high density plasma chemical vapor dep0si t ion (HDPCVD for short) to deposit a dielectric layer (such as silicon dioxide) between metals. US Patent No. 6,11,3,45 also details the HDPCVD process, which is mainly using the HDPCVD process and chemical gas. Characteristics of phase deposition and anisotropic etching, as shown in Figure A, the etching comes from

1236055 V. Description of the invention (2) The use of AC plasma in HDPCVD machine 10 to generate power 12 The use of plasma 16 and electrostatic attraction? ^ Bu Lei you ϋ you + Said electricity and the potential on the plate 20 so that the ions in the plasma bombarded the surface of the sundial 18, non-isotropically engraved above the metal wire: and then ^ formed no holes between metal conductors ( V0ld free) dielectric layer is deposited on the surface of the ion bombardment B, circle 18 surface, often because of the uneven distribution of the potential difference between the plasma 16: wafer: 8 board surface and cause electricity on the wafer surface ", If the surface potential difference of the right wafer 18 is too large, the gate oxide layer that has been fabricated will be damaged and the gate oxide layer will collapse. Plasma 16 and possibly from stage 10, electrostatic e1ectros tat i el ectrostat i The electrostatic force will have a single electrode on the wafer, which will not cause the above problem. However, when the discharge circuit is connected to the induced charge, it will be neutralized due to movement. Wafer 1 8 plate electrostatic chuck 2 0 chuck 2 0 type c chuck) and c chuck) 2 1 8 attracted to static electrostatic chuck 2 0 plasma 16 and crystal process, you must wait for electricity before moving the wafer The potential difference upper potential fraction over time includes single and bipolar electrostatic types, electric chucks, 20 disk surface potential circles, 18 plate surfaces, and wafers in the static slurry 16. If the distribution is too early, it may cause uneven distribution. In the HDPCVD machine, the electrostatic suction (mono-pollar suction (bi ~ pollar) is used because the electrostatic chuck 20 is used. If only the distribution in the electrostatic chuck 20 can be considered as a uniform distribution and the potential difference is unevenly distributed. The non-electric particles on the wafer 18 on the electric chuck 20 and the surface of the wafer 18 will affect the speed of mass production even if the wafer 18 is broken. The bipolar electrostatic chuck 20 1 uses bipolar electrostatic as shown in the first figure b. It can be used after the end of the process when it is inhaled The electrode itself generates a discharge current and 1236055 V. Description of the invention (3) To accelerate the removal of the electrostatic force of the bipolar electrostatic chuck 021 on the wafer 18, and to move the wafer 18 too slowly and prematurely Fragmentation problems, a moment; the parental bias bias power 22 of the ion bombardment also passed through the bipolar electrostatic chuck 201 inner ring electrode 28 and outer ring electrode 30 to generate a potential difference that attracts ion bombardment 'as shown in Figure -C' at high frequencies In the process of alternating current transmission, the power output of the internal and external electrodes is often different due to the different impedances of the internal and external electrode transmission lines, which leads to uneven potential distribution on the bipolar electrostatic chuck 201. As shown in Figure A, the wafer 丨After the upper, inner and outer sides are bombarded by ions, different potentials are generated to cause surface currents on the wafer i 8. As shown in y of the second B, the accumulated charge on the polycrystalline stone conductor layer 36 passes through the stone substrate 4. On the gate oxide layer 38, which in turn damages the gate oxide layer 38. In order to solve the above-mentioned problem of gate oxide layer damage, US No. 5 Question: 13 140 and US Patent No. 5, 843, m mentioned adding process steps To change the deposition The appearance of the component after the electrical layer solves the problem of the gate oxide layer being damaged by the plasma 16. However, it does not mention how to avoid the problem of uneven distribution of the potential difference attracting ion bombardment on the bipolar electrostatic chuck 20m. The uneven potential distribution of 201 attracting ion bombardment on the bipolar electrostatic chuck will be uneven, which is very important in the HDPCVD process using the bipolar electrostatic chuck 201. SUMMARY OF THE INVENTION The main purpose of the present invention is to solve the bipolar On electrostatic chuck

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The problem of uneven distribution of potential difference attracting ion bombardment. The present invention proposes to add an impedance matching circuit between the AC bias power source generating the ion bombardment and the double electrostatic chuck, and use the impedance matching circuit to adjust the impedance of the inner and outer electrodes of the bipolar electrostatic chuck so that The internal and external electrode impedances are the same, resulting in the same power output for the internal and external electrodes of the bipolar electrostatic chuck, which further makes the potential difference of the attracted ion bombardment on the bipolar electrostatic chuck uniform and prevents the plasma from damaging the gate oxide layer. Data comparison shows that the failure rate (fai 1 rate) of wafers on wafers is improved from 30% to 60% before the impedance matching circuit is added to 0% to 2% after the impedance matching circuit is added. The impedance matching circuit provided by the present invention includes a power measuring device that can measure the voltage and current of the internal and external electrodes in a bipolar electrostatic chuck. The power comparator compares the output power difference between the internal and external electrodes to generate a control signal output. After receiving this control signal, the logical drive motors (10gic drive motors) change the impedance value of each variable impedance element so that the internal and external electrodes have the same power output. Fourth, [implementation] Some implementation examples described in this description will be described in detail as follows. However, in addition to the detailed description, the present invention can be widely implemented in other embodiments. In other words, the scope of the present invention is not limited by the proposed embodiment, but should be based on the scope of the patent application filed later.

1236055 V. Description of the invention (5) As shown in Figure 3A, the plasma device with impedance matching function mentioned in the present invention is mainly applied to a high density plasma chemical vapor deposition HDPCVD (high density plasma chemical In the vapor deposition) machine, the HDPCVD machine used in the present invention is an inductively coupled plasma reactor 101. The plasma generation method is to use an AC plasma to generate power 12 to the induction coil 1 4 and use the induction coil 1 4 The generated electromagnetic field generates a high-concentration and low-energy plasma 16. In this embodiment, the AC plasma generates a power source 12. The operating frequency is between about 20 kHz and 3 50 kHz, which is reflected in the HDPCVD process (such as metal (Electrical layer deposition), before carrying out the deposition reaction, it is necessary to first adsorb the wafer 18 on which a dielectric layer is to be deposited on a bipolar electrostatic chuck 201. The bipolar electrostatic chuck 201 is generated by using a direct current power source 24. The electrostatic adsorption force will attract the wafer 18 to the bipolar electrostatic chuck 201; when the process is finished, the bipolar electrostatic chuck 20 1 will provide a discharge circuit to make static electricity faster than a unipolar electrostatic chuck. eliminate To remove the wafer from the reaction chamber. When depositing a dielectric layer in a high-aspect-ratio line gap, 'it often results in incomplete deposition and voids (vo id) in the line gap. At this time, it is necessary to use ion bombardment etching in the plasma. Simultaneously with chemical vapor deposition, this method is used to solve the problem of incomplete deposition. 1 In the present invention, an ion bombardment is generated by using an AC bias power source 2 2 connected to a carrier. Wafer 丨 8 bipolar

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Electricity and phoenix 201 and the use of bipolar electrostatic chuck 201 plate surface area to reduce the consumption of surface area of the plasma reactor 01I φ will be 1 difference between Detian know I, between the plasma 16 and the bipolar electrostatic chuck Generates a DC potential self-adjusting function. This DC potential self-adjusting function that generates a bipolar electrostatic chuck 001 due to the different surface area of the plate will cause positively charged ions in the electropolymerization 16 to go to the surface of the wafer 18. 56MHz。 Click to etch the lines to block the excess deposits deposited between the lines to form a dielectric layer without voids (void free), where the AC bias power supply 22 operates at about 13.56MHz. As shown in Figure 2B, the aforementioned bipolar electrostatic chuck 201 has an inner ring electrode 28 and an outer ring electrode 30, and the inner ring electrode 28 and the outer ring electrode 30 are respectively connected to a DC power source 24 and The AC bias power source 22 is connected. The inner ring electrode isolation capacitor impedance 321 and the outer ring electrode isolation capacitor impedance 322 are used to block the direct current from entering the AC bias power source 22, because the capacitive element is open circuit for DC power (capacitive impedance Zc = l / joC, DC frequency 6j = 0, Zc is 〇〇); In addition, the inner loop electrode isolation inductance impedance 34 1 and the outer loop electrode isolation inductance impedance 3 4 2 are not used to prevent the parent current from entering the DC power supply 2 4, because the power reduction element is approximately open to high-frequency AC power (inductance impedance ZL = j 6JL, when the high-frequency AC power frequency ω is large, ZL is also large). The impedance of the inner ring electrode isolation capacitor impedance 321 and the outer ring electrode isolation capacitor impedance 3 2 2 in the third B figure have different impedance values due to different transmission lines, which will cause the inner ring electrode 28 and the outer ring in the bipolar electrostatic chuck 201 There are different power outputs on the ring electrode ^ (power output Pout is AC bias power supply 2 2 work

V. Description of the invention (7) Rate ^ generator minus rate loss Pimpedance In order to conduct ion bombardment and damage the gate, the bipolar 30 must have the same power and the same impedance value for the inner ring electrode isolation. The electrical and AC bias power sources 22 have the same impedance value, and thus the power output to prevent the gate impedance power loss P impedance, whose impedance work is the square of the current multiplied by the impedance value I2 * Z). A wafer will be produced in the surface] 8 surface oxide layer, in order to prevent the gate oxide layer from breaking, the inner ring electrode 28 and the outer ring electrode in the electrostatic chuck 201 are output, that is, the inner ring electrode 28 and the outer ring electrode μ have this. The present invention adds an impedance matching circuit 42 between the capacitor impedance 321 and the outer ring electrode isolation capacitor impedance 322 so that the inner ring electrode 28 and the outer ring electrode 30 are in phase, so that the inner ring electrode 28 and the outer ring electrode 30 are the same. Destruction of polar oxide layer. Containing -in ;; pole figure can be; capacity ^ 阻抗 impedance adjuster 52, impedance matching circuit 42 its /-ratio terminal ^ 51 to the two automatic power supply 22 'impedance matching circuit 42 the other end is connected to the U voltage impedance as external Ring electrode isolation capacitor impedance 32 2. The underwear electrode isolation capacitor is as shown in the fourth figure. Power measurement = ΐ: Γ: Γ value, and then converted into the power of the inner robe of Shuangguang and the output of an outer ring electrode. 1236055 V. Description of the invention (8 ) Rate comparison block 5 1 0, through a power comparator 5 丨 compare the power output difference between the internal and external electrodes of the bipolar electrostatic chuck 2 0 1 to generate a control signal, as shown in the automatic impedance adjustment block 5 2 〇, automatic The impedance adjuster 5 2 can receive this control signal to adjust the inner loop electrode variable capacitance element 441, the outer loop electrode variable capacitance element 442, the inner loop electrode variable inductance element 461 and the outer loop electrode by a plurality of logic driving motors. Change the impedance of the inductive element 462, so that the impedance value of the inner loop electrode 28 and the impedance value of the outer loop electrode 30 are the same impedance value: so that the inner loop electrode 28 and the outer loop electrode 30 have the same power input, The high-density electro-chemical forging chemical vapor deposition process consists of: 2 ° ”the inner ring electrode 28 has the same power output as the outer ring. When the sub-bombing wafer 18 does not generate internal and external voltages on the wafer 18 to damage the gate oxidation I. And the above is only the present invention Compared with the scope of patents applied for each invention. Ten shells 1 are not used to limit the scope of this invention and can still be changed and implemented. February = the scope of the Beibei Valley. Therefore, the scope of the present invention # # 催 又 化The targets that should still be within the scope of the present invention are defined by the following patent applications.

$ 12 页 1236055 Brief description of the diagram 5. [Simplified illustration of the diagram] The first diagram A shows a schematic diagram of an HDPCVD machine in the prior art; the first diagram B shows the inner and outer electrodes of a bipolar electrostatic chuck in the prior art Top view of the electrical distribution; Figure 1C shows the equivalent circuit diagram of the connection between an AC bias power supply that provides ion bombardment and a DC power supply that provides the electrostatic attraction of a bipolar electrostatic chuck in the prior art;

The second diagram A shows a schematic diagram of the electron flow on the surface of the wafer generated by the power difference between the internal and external electrodes of a bipolar electrostatic chuck in the prior art. The second diagram B shows a polycrystalline silicon conductor layer caused by plasma ions bombarding the wafer in the prior art. Excessive accumulated charge causes the gate oxide layer to collapse and become unintentional. Figure 3A shows a schematic diagram of an inductively coupled plasma reactor. Figure 3B shows an ion bombardment circuit with an impedance matching circuit. Equivalent circuit diagram of the connection between an AC bias power source and a DC power source that provides the electrostatic attraction of a bipolar electrostatic chuck; Figure 3C shows an equivalent circuit diagram inside an impedance matching circuit; and

The fourth figure shows a flow chart for adjusting the impedance values of the inner and outer electrodes of the bipolar electrostatic chuck. Symbol Description:

Page 12 1236055 &] Short description 10 HDPCVD machine 101 Inductively coupled plasma reactor 12 AC plasma power 14 Induction coil 16 Plasma 18 Wafer 20 Electrostatic chuck 201 Bipolar electrostatic chuck 22 AC bias power 24 DC power supply 2 8 inner ring electrode 30 outer ring electrode 321 inner ring electrode isolation capacitor impedance 322 outer ring electrode isolation capacitor impedance 341 inner ring electrode isolation inductance impedance 342 outer ring electrode isolation inductance impedance d6 polycrystalline silicon conductor layer 38 gate oxide layer 40 silicon Substrate 42 Impedance matching circuit 441 Inner ring electrode variable capacitance element 442 Outer ring electrode variable capacitance element 461 Inner ring electrode variable inductance element

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1236055 Brief description of drawings 46 2 Variable inductor element of outer ring electrode 50 Power measuring device 5 0 0 Power measuring block 51 Power comparator 510 Power comparing block 52 Automatic impedance adjuster 5 2 0 Automatic impedance adjusting block

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Claims (1)

1236055 Scope of patent application: 1 · A bipolar static reactor with impedance-plasma anti-chemical vapor deposition and a bipolar static matching function, the electric process; an electric chuck, the electric chuck is used for the sucker to contain an inner The ring electrode and the ions in the inner ring slurry of a parent flow partial chuck collide with an impedance power source and the bipolar voltage source of the inner ring electrode, the electrode and the external bias circuit of the wafer, and the output of the electrostatic chuck A power and plasma device includes: a plasma reactor can generate a plasma for a plasma bipolar electrostatic chuck located in the plasma reactor to carry and adsorb a wafer, the bipolar electrostatic outer ring electrode; a parent-flow bias power connection A voltage is provided at the bipolar electrostatic ring electrode and the AC bias power supply; and an impedance matching circuit is connected between the AC bias voltage and the impedance matching circuit is used to balance the output power of the outer ring electrode. 2 · Plasma device with impedance matching function as in item 1 of the patent application range, wherein the above plasma reactor contains an AC plasma to generate power. 3. If the plasma device with impedance matching function in item 2 of the patent application scope, wherein the above-mentioned AC plasma generates a power frequency between about 200 KHz and 350 KHz. 4. If the plasma matching device with impedance matching function in item 1 of the patent application range, wherein the operating frequency of the above-mentioned AC bias power supply is about 13.56 MHz. Page 16 1236055 VI. The scope of the patent application for the installation of the energy and power matching anti-impedance items are listed in the P electric power line and the range of anti-impact. Please refer to the application above for details. The number of components includes the power and the power, the resistance can be changed, the number of units can be adjusted, and the resistance can be adjusted. Measurable number of digital resistors can be adjusted. The ratio-to-value device sends the reactance to the transmission resistance ratio. The control reactance is changed from one resistance to the other. After the output is obtained, the output and output rate are compounded. A phase-enveloping device and a rl · t-th measuring range Waidanli vibration rate fluent power generator are used to measure the power phase of the installed power and match the impedance of the impedance device. Please refer to the application of the measurement as described above and 6. The calculation includes the wrapper LA J, the comparison ratio, the rate of power, and the special application. Please describe the application of the application, such as the energy and power matching impedance of the installed plasma power. The item sender sends 1gu I # signal control and the first anti-containment I. Pa Lee self-explanation, please apply for the application, such as the I-its device equipped with the energy and matching anti-impedance item receiver ^ υ f The information control and control of a package containing power and matching anti-impedance items installed in the Dama District horse series logic number inclusive of package device adjustment _ adjust the anti-impact containment ^^ Λ please describe for your own benefit The number of 9-terminal 1-element transformers that can be applied in the application is as follows: including the package, Inductive power distribution Page 17 1236055 /, the scope of patent application f-external circuit connection, the current bias power supply connection, and the two ends of the inductor element and a plurality of variable capacitance elements, which can be & The second terminal of the first element of the variable inductance element is grounded; and when connected, the plurality of variable capacitance elements are first-power / measurement devices, and the power measurement device is connected to the plurality of electric reduction devices. The Λ /// comparator is connected to the power measuring device and can generate an automatic impedance adjustment control signal; and an automatic impedance adjuster, which includes the variable inductance element and the plurality of variable ## We have prepared 4 pieces of equipment to connect with the power ratio, and the automatic impedance adjuster receives 誃 · σσ to integrate the impedance values of the plurality of inductive elements, -2-1. The signal is being controlled to dim. The impedance value and the impedance value of the plurality of capacitive elements are 0. 11. As in the impedance matching circuit of item 10 of the patent application scope, the power measuring device of the straight middle and upper includes a voltmeter for measuring the amplitude and phase of the voltage and a current amplitude and Phase of the ammeter. '12. The impedance matching circuit according to item 10 of the patent application range, wherein the upper power comparison includes a control signal transmitter. 1 3. The impedance matching circuit according to item 10 of the patent application range, wherein the automatic impedance adjustment includes a control signal for receiving signals. 1236055 6. Patent application scope-An impedance matching circuit is connected between the AC bias power source and the isolation circuit and the impedance matching circuit is used to balance the output power of the inner ring electrode and the outer ring electrode. Output power. The impedance matching circuit includes a plurality of variable impedance elements, a power measuring device, a power comparator, and an automatic impedance adjuster. The plurality of variable impedance components are measured by the power measuring device. After the power output of the variable impedance element, the power comparator compares the power output of the plurality of variable impedance elements to obtain a comparison result and sends the comparison result to the automatic impedance adjuster to adjust the impedance value of the plurality of variable impedance elements. 1 6. The plasma device with impedance matching function according to item 15 of the scope of patent application, wherein the power measuring device includes a voltmeter for measuring voltage amplitude and phase and a current meter for measuring current amplitude and phase. 1 7. The plasma device with impedance matching function according to item 15 of the patent application scope, wherein the power comparator includes a control signal transmitter. 1 8. The plasma device with impedance matching function according to item 15 of the scope of patent application, wherein the above-mentioned automatic impedance adjuster includes a control signal receiver. 19. The plasma device with impedance matching function according to item 15 of the patent application scope, wherein the automatic impedance adjuster described above includes a plurality of logic driving motors. 2 0. —A method for impedance matching of a plasma device, including: Page 20 1236055 6. Scope of patent application Use the electrostatic force of a bipolar electrostatic chuck to adsorb a wafer onto the bipolar electrostatic chuck; generate ion bombardment on the surface of the wafer on the bipolar electrostatic chuck; measure The power output of an inner ring electrode and the power output of an outer ring electrode of one of the bipolar electrostatic chucks; comparing a power output difference between the inner ring electrode and the outer ring electrode of the bipolar electrostatic chuck to generate a control signal; The signal adjusts the impedance value of the inner ring electrode of one of the bipolar electrostatic chucks to the same impedance value as the outer ring electrode, so that the inner ring electrode and the outer ring electrode have the same power output; and a high-density plasma is performed. Chemical vapor deposition process. Page 21