Plasma chamber and wafer etching method using plasma chamber

Abstract

The present invention relates to a plasma chamber and a wafer etching method using the plasma chamber, the plasma chamber of the present invention comprising: a housing having a reaction space therein for etching a wafer by plasma; a base plate which is provided inside the case and on which the wafer is placed; a wafer etching method using a plasma chamber, according to the present invention, comprises: a pressure adjustment step for adjusting the pressure inside a housing, and a pressure adjustment unit for adjusting the pressure inside the housing to 50 to 500 millitorr (mTorr), the method comprising: a pressure adjustment step for adjusting the pressure inside the housing; and a source power adjustment step of adjusting the plasma source.

Description

Technical Field

[0001] The present invention relates to a plasma chamber and a wafer etching method using the plasma chamber, and more particularly, to a plasma chamber capable of improving selectivity while maintaining a high etching rate and a wafer etching method using the plasma chamber. Background Art

[0002] Generally speaking, in a process of manufacturing a semiconductor, it is very important to ensure uniformity. The uniformity of the semiconductor can be ensured or adjusted in an etching process in the process of manufacturing the semiconductor.

[0003] The semiconductor etching process can be performed inside a plasma chamber. The plasma chamber forms plasma in an internal reaction space and uses the plasma to perform the semiconductor etching process.

[0004] A plasma source for forming plasma is provided at the upper portion of the plasma chamber. Typical examples of the plasma source include a capacitively coupled plasma (CCP) source and an inductively coupled plasma (ICP) source.

[0005] A capacitively coupled plasma (CCP) source utilizes an electric field and can generally perform etching at a slightly higher pressure than an inductively coupled plasma (ICP). It is known that a capacitively coupled plasma (CCP) source has a slow etching rate but excellent selectivity and process reproducibility.

[0006] However, the capacitively coupled plasma (CCP) source has a plasma density non-uniformity characteristic in which the plasma density in the center of the wafer is relatively higher than that at the edge of the wafer. In addition, the overall plasma density is low, so there is a problem that high RF power needs to be applied to increase the plasma density.

[0007] Inductively coupled plasma (ICP) uses an induced magnetic field and has the advantage of having a higher overall plasma density than a capacitively coupled plasma (CCP) source. Although ICP can increase the etching rate at a pressure lower than that of a capacitively coupled plasma (CCP) source, the plasma density in the center of the wafer is relatively higher than that in the edge of the wafer, and there are problems such as a low selectivity and poor process reproducibility despite a high etching rate.

[0008] As described above, conventional plasma sources such as capacitively coupled plasma (CCP) and inductively coupled plasma (ICP) have a problem in that it is difficult to simultaneously increase both the etching rate and the selectivity, and the etching rate and the selectivity have been considered to be in a trade-off relationship. Summary of the invention

[0009] Technical issues

[0010] The present invention aims to solve the above-mentioned problems. More specifically, the present invention relates to a plasma chamber capable of improving selectivity while maintaining a high etch rate and a wafer etching method using the plasma chamber.

[0011] Problem Solving Solutions

[0012] The plasma chamber of the present invention, which is intended to solve the above-mentioned problem, is a plasma chamber for forming plasma, and is characterized in that it includes: a shell having a reaction space inside for etching a wafer by plasma; a base plate, which is provided inside the shell and on which the wafer is placed; and a pressure regulating unit, which regulates the pressure inside the shell, wherein the pressure regulating unit regulates the pressure inside the shell to 50 to 500 mTorr.

[0013] The plasma chamber of the present invention for solving the above-mentioned problem further comprises a plasma source provided on the upper portion of the shell and forming plasma inside the shell. The source power of the plasma source may be 500 to 3000W.

[0014] The pressure regulating unit of the plasma chamber of the present invention, which is intended to solve the above-mentioned problem, can regulate the pressure inside the shell at a pressure that is the same as or greater than the resonance pressure, wherein the resonance pressure causes the driving frequency (Driving frequency) of the plasma source to be formed identically to the collision frequency between particles inside the shell.

[0015] With regard to the plasma chamber of the present invention which is intended to solve the above-mentioned problem, the etching gas is supplied to the interior of the shell, and the etching gas supplied to the interior of the shell is discharged to the outside of the shell after the reaction, and the etching gas may remain in the shell for 1 second to 4 seconds.

[0016] In the plasma chamber of the present invention for solving the above-mentioned problems, the density of the plasma formed in the reaction space of the housing is expressed in cm3. -3 ) can be from 2E11 to 5E11.

[0017] The plasma chamber of the present invention, which is intended to solve the above-mentioned problem, further comprises a bias RF source connected to the above-mentioned base plate and capable of applying a bias voltage (Bias) to the above-mentioned base plate. The bias power (Bias power) of the above-mentioned bias RF source can be 500 to 5000W.

[0018] In the plasma chamber of the present invention for solving the above-mentioned problems, the plasma formed in the reaction space of the housing includes ions and radicals, and the wafer can be etched by the synergy effect of the ions and the radicals.

[0019] The wafer etching method using a plasma chamber of the present invention, which is intended to solve the above-mentioned problem, is a wafer etching method for etching a wafer through a plasma chamber, wherein the plasma chamber comprises: a shell having a reaction space inside for etching the wafer through plasma; a bottom plate, which is provided inside the shell and on which the wafer is placed; a pressure regulating unit, which regulates the pressure inside the shell; and a plasma source, which is provided on the upper part of the shell and forms plasma inside the shell. The wafer etching method using a plasma chamber is characterized in that it comprises: a pressure regulating step of regulating the pressure inside the shell to 50 to 500 mTorr by the pressure regulating unit; and a source power regulating step of regulating the source power of the plasma source to 500 to 3000 W by the plasma source.

[0020] With regard to the wafer etching method using a plasma chamber of the present invention which is intended to solve the above-mentioned problem, in the above-mentioned pressure adjustment step, the pressure inside the above-mentioned shell can be adjusted by the above-mentioned pressure adjustment unit at a pressure which is the same as or greater than the resonance pressure, wherein the above-mentioned resonance pressure causes the driving frequency (Driving frequency) of the above-mentioned plasma source to be formed identically to the collision frequency between particles inside the above-mentioned shell.

[0021] With regard to the wafer etching method using a plasma chamber of the present invention which is intended to solve the above-mentioned problem, the etching gas is supplied to the interior of the shell, and the etching gas supplied to the interior of the shell is discharged to the outside of the shell after the reaction, and the etching gas may remain in the shell for 1 second to 4 seconds.

[0022] In the wafer etching method using a plasma chamber of the present invention for solving the above-mentioned problems, the density of the plasma formed in the reaction space of the housing is expressed in cm3. -3 ) can be from 2E11 to 5E11.

[0023] As for the wafer etching method using a plasma chamber of the present invention which is intended to solve the above-mentioned problems, the above-mentioned plasma chamber includes a bias RF source connected to the above-mentioned base plate and capable of applying a bias (Bias) to the above-mentioned base plate, and the above-mentioned wafer etching method may further include a bias power adjustment step of adjusting the bias power (Biaspower) of the above-mentioned bias RF source to 500 to 5000W by the above-mentioned bias RF source.

[0024] In the wafer etching method using a plasma chamber of the present invention to solve the above problems, the plasma formed in the reaction space of the shell contains ions and radicals, and the wafer can be etched by the synergy effect of the ions and radicals.

[0025] Effects of the Invention

[0026] The present invention relates to a plasma chamber and a wafer etching method using the plasma chamber, which forms the pressure inside the chamber to be relatively higher than that of an existing chamber, so that ions and free radicals can be used simultaneously to etch the wafer, thereby having the advantage of maintaining a high etching rate while improving the selectivity (PRselectivity).

[0027] In addition, the present invention has the advantage of being able to obtain a high etch rate and a high selectivity while using lower power for the plasma source and the bias RF source than in the prior art chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a diagram showing ions and radicals etching a wafer.

[0029] Figure 2 is a diagram illustrating a plasma chamber according to an embodiment of the present invention.

[0030] Figure 3 is a diagram illustrating a wafer etching method using a plasma chamber according to an embodiment of the present invention.

[0031] Figure 4 is a diagram illustrating a process region for utilizing ions and radicals according to an embodiment of the present invention.

[0032] Figure 5 is a graph showing changes in the etching rate as a function of the bias power and pressure when etching a wafer using ions.

[0033] Figure 6 is a graph showing changes in the etching rate with the bias power and pressure when etching a wafer using ions and radicals according to an embodiment of the present invention. DETAILED DESCRIPTION

[0034] This specification explains the principles of the present invention and discloses various embodiments to clarify the scope of the present invention and enable those skilled in the art to implement the present invention. The disclosed embodiments can be implemented in various ways.

[0035] The expressions "including" or "may include" etc. that can be used in various embodiments of the present invention refer to the existence of the corresponding functions, actions or constituent elements of the invention (disclosure), and do not limit the additional one or more functions, actions or constituent elements, etc. In addition, in various embodiments of the present invention, the terms "including" or "having" etc. are intended to specify the existence of the features, numbers, steps, actions, constituent elements, parts or combinations thereof recorded in the specification, and should be understood as not excluding in advance the existence or additional possibility of one or more other features or numbers, steps, actions, constituent elements, parts or combinations thereof.

[0036] When it is mentioned that a certain component is "connected or coordinated" with another component, although the above-mentioned certain component may be directly connected or directly coordinated with the above-mentioned other component, it should be understood that there may be other new components between the above-mentioned certain component and the above-mentioned other component. On the contrary, when it is mentioned that a certain component is "directly connected" or "directly coordinated" with another component, it should be understood that there are no other new components between the above-mentioned certain component and the above-mentioned other component.

[0037] The terms "first", "second", etc. used in this specification can be used to describe various components, but each component should not be limited by each term. Each term is used only to distinguish one component from other components.

[0038] The present invention relates to a plasma chamber and a wafer etching method using the plasma chamber, and relates to a plasma chamber capable of improving selectivity while maintaining a high etching rate and a wafer etching method using the plasma chamber.

[0039] Reference Figure 1 , plasma is generally composed of electrons, ions 21, and radicals 22. Looking at the existing method of etching a wafer by plasma, during the plasma etching process, the dominant species is formed by one of ions or radicals.

[0040] Specifically, in the existing method of etching a wafer using plasma, metal etching mainly uses radicals, and oxide etching mainly uses ions.

[0041] According to the plasma chamber and the wafer etching method using the plasma chamber according to the embodiments of the present invention, during the plasma etching process, the dominant species are not formed by one of ions or free radicals, but ions 21 and free radicals 22 can be used simultaneously.

[0042] That is, according to the plasma chamber and the wafer etching method using the plasma chamber of the embodiment of the present invention, during the plasma etching process, rather than performing a reaction dominated by ions or a reaction dominated by free radicals, it is better to use a process area where ions 21 and free radicals 22 work together to produce a synergy effect.

[0043] More specifically, the plasma chamber and the wafer etching method using the plasma chamber according to the embodiment of the present invention utilize the resonance phenomenon generated by the applied source frequency and the collision between particles, and can improve the selectivity while maintaining a high etch rate through the synergistic effect of ions and free radicals.

[0044] The plasma chamber and the wafer etching method using the plasma chamber according to the embodiments of the present invention can solve the problems of the method using the existing inductively coupled plasma (ICP) source and improve it.

[0045] The plasma chamber and the wafer etching method using the plasma chamber according to the embodiment of the present invention may be a synergistic resonance ICP (SRICP) using a resonance phenomenon and a synergy effect.

[0046] According to the plasma chamber and the wafer etching method using the plasma chamber according to the embodiment of the present invention, the conditions of the plasma chamber can be adjusted in order to use ions and radicals at the same time.

[0047] The plasma chamber according to the embodiments of the present invention and the wafer etching method using the plasma chamber can adjust the pressure inside the chamber, the source power of the plasma source, the plasma density inside the chamber, the bias power of the bias RF source, etc. The plasma chamber according to the embodiments of the present invention and the wafer etching method using the plasma chamber change the above conditions in the plasma chamber, so that ions and free radicals can be used at the same time.

[0048] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0049] Figure 2 Referring to the plasma chamber 100 according to the embodiment of the present invention, the plasma chamber 100 includes a housing 110 , a base plate 111 , and a pressure adjusting portion 120 .

[0050] The housing 110 has a reaction space inside for etching the wafer 10 by plasma. The housing 110 may be an outer wall of the plasma chamber 100 according to an embodiment of the present invention, and has a space inside. If the wafer 10 is loaded into the housing 110, the wafer 10 may be etched by the plasma formed inside the housing 110.

[0051] The bottom plate 111 is provided inside the housing 110 and the wafer 10 is placed thereon. The bottom plate 111 may be a plate provided inside the housing 110 and the wafer 20 is placed thereon.

[0052] More specifically, the base plate 111 may be a wafer chuck for placing and supporting the wafer 10 . If the wafer 10 is placed on the base plate 111 , the wafer 10 may be etched.

[0053] The pressure regulating unit 120 regulates the pressure inside the housing 110. The pressure regulating unit 120 may be a pressure regulating device for regulating the pressure inside the housing 110, and may be a device having various structures as long as the pressure inside the housing 110 can be regulated.

[0054] According to an embodiment of the present invention, the pressure adjusting unit 120 may adjust the pressure inside the housing 110 to 50 to 500 mTorr. As described above, the plasma chamber according to an embodiment of the present invention can utilize the ions 21 and the radicals 22 simultaneously.

[0055] According to the plasma chamber of the embodiment of the present invention, in order to use the ions 21 and the radicals 22 simultaneously, the pressure inside the housing 110 can be adjusted to 50 to 500 mTorr by the pressure adjusting unit 120 .

[0056] In the plasma chamber according to the embodiment of the present invention, if the pressure inside the housing 110 is less than 50 mTorr, it is difficult to expect to utilize the synergy effect of the ions 21 and the radicals 22 at the same time.

[0057] More specifically, if the pressure inside the housing 110 is less than 50 mTorr, an etching reaction dominated by ions 21 may occur. In addition, when ions 21 and radicals 22 are used simultaneously, if the pressure inside the housing 110 is less than 50 mTorr, there is a risk that the etching rate may decrease.

[0058] If the pressure inside the housing 110 becomes greater than 500 mTorr, the reaction between the particles becomes excessive, so the reaction time becomes short, and thus the etching rate decreases.

[0059] Therefore, the plasma chamber according to the embodiment of the present invention preferably adjusts the pressure inside the housing 110 to 50 to 500 mTorr through the pressure adjusting unit 120 .

[0060] In addition, according to another embodiment of the present invention, the pressure inside the housing 110 may be adjusted to 100 to 150 mTorr, 200 to 500 mTorr, or 300 to 500 mTorr through the pressure adjusting unit 120 .

[0061] The plasma chamber according to the embodiment of the present invention may further include a plasma source 130 provided on an upper portion of the housing 110 and forming plasma inside the housing 110 .

[0062] The plasma source 130 may form plasma and may include a coil 131 and a radio frequency power generator 132. According to an embodiment of the present invention, the source power of the plasma source 130 may be adjusted to 500 to 3000W.

[0063] If the source power (Source power) formed by the above-mentioned plasma source 130 is less than 500W, the etching rate will decrease. Therefore, the source power (Source power) formed by the above-mentioned plasma source 130 is preferably greater than 500W.

[0064] As described above, the plasma chamber according to the embodiment of the present invention adjusts the pressure inside the housing 110 to 50 to 500 mTorr through the pressure adjusting unit 120 , so that the pressure inside the housing 110 is higher than that of the conventional plasma chamber.

[0065] If the source power of the plasma source 130 is greater than 3000 W, the plasma density becomes too high due to the relatively high internal pressure of the housing 110. If the plasma density becomes too high, the reaction between particles becomes too much, so the reaction time becomes short, and thus the etching rate decreases.

[0066] Therefore, the plasma chamber according to the embodiment of the present invention preferably adjusts the source power of the plasma source 130 to 500 to 3000 W. In addition, according to another embodiment of the present invention, the source power of the plasma source 130 can also be adjusted to 500 to 1500 W.

[0067] The pressure adjusting unit 120 of the plasma chamber according to the embodiment of the present invention may adjust the pressure inside the housing 110 at a pressure equal to or greater than the resonance pressure.

[0068] Here, the resonance pressure may be a pressure formed by making the driving frequency of the plasma source 130 and the collision frequency between particles inside the housing 110 equal to each other.

[0069] If, when the driving frequency (Driving frequency) of the above-mentioned plasma source 130 is 13.56 MHz, the resonance pressure formed by making the driving frequency (Driving frequency) of the above-mentioned plasma source 130 and the collision frequency between the particles inside the above-mentioned shell 110 the same can be 52 mTorr in the case of Ar (argon) gas, and when the driving frequency (Driving frequency) of the above-mentioned plasma source 130 is 27.12 MHz, the resonance pressure can be 104 mTorr in the case of Ar (argon) gas.

[0070] The pressure regulating unit 120 according to the embodiment of the present invention may regulate the pressure inside the housing 110 at a pressure that is equal to or greater than a resonance pressure determined by a driving frequency of the plasma source 130 .

[0071] According to an embodiment of the present invention, the collision frequency between particles inside the housing 110 may be determined by the product of the number of particles per unit volume and the rate constant for the collision reaction.

[0072] The plasma chamber according to the embodiment of the present invention may include a collision frequency analysis unit for analyzing the collision frequency between particles occurring inside the housing 110. The collision frequency analysis unit may be used to derive a resonance pressure that makes the driving frequency of the plasma source 130 the same as the collision frequency.

[0073] According to the embodiment of the present invention, the pressure regulating unit 120 may receive data on the resonance pressure through the collision frequency analyzing unit, thereby the pressure regulating unit 120 may regulate the pressure inside the shell 110 at a pressure equal to or greater than the resonance pressure.

[0074] According to an embodiment of the present invention, the density of the plasma formed in the reaction space of the housing 110 is expressed in cubic centimeters (cm -3 ) is preferably 2E11 to 5E11.

[0075] If the density of the plasma formed in the reaction space of the housing 110 is less than cm -3 )2E11, the expected etching rate cannot be obtained.

[0076] On the contrary, if the density of the plasma formed in the reaction space of the housing 110 is greater than cm -3 )5E11, the ions 21 and the free radicals 22 are separated, which will have a bad influence on the selectivity.

[0077] That is, according to the plasma chamber of the embodiment of the present invention, the ions 21 and the radicals 22 are simultaneously used to increase the etching rate, and the density of the plasma formed in the reaction space of the housing 110 is formed to be 1000 μm / cm3 in order to increase the selectivity. -3 ) is calculated as 2E11 to 5E11.

[0078] According to an embodiment of the present invention, the density of the plasma formed in the reaction space of the housing 110 can be adjusted by the plasma source 130. Specifically, the plasma source 130 can form a plasma density suitable for simultaneously utilizing ions 21 and radicals 22 inside the housing 110.

[0079] Reference Figure 2 The plasma chamber 100 according to the embodiment of the present invention may further include a bias RF source 140 connected to the bottom plate 111 and capable of applying a bias to the bottom plate 111 .

[0080] The bias RF source 140 applies a bias voltage (Bias) to the base plate 111 , so that a bias voltage can be applied to plasma during the etching process.

[0081] According to an embodiment of the present invention, the bias power of the bias RF source 140 is preferably adjusted to 500 to 5000 W. The bias power directly affects the ions 21 .

[0082] If the bias power of the bias RF source 140 is less than 500 W, the activity of the ions 21 is restricted, so that the free radicals 22 can be dominantly active, and the synergy effect of the ions 21 and the free radicals 22 cannot be expected.

[0083] On the contrary, if the bias power of the bias RF source 140 is greater than 5000 W, the ions may be dominantly active, and thus the synergy effect of the ions 21 and the free radicals 22 cannot be expected.

[0084] As a result, in order to induce a synergy effect through the ions 21 and the radicals 22 in the plasma chamber 100 according to the embodiment of the present invention, the bias power of the bias RF source 140 must be adjusted to 500 to 5000W.

[0085] An etching gas for etching a wafer may be supplied into the housing 110 of the plasma chamber 100 according to an embodiment of the present invention. The etching gas supplied into the housing 110 may be exhausted to the outside of the housing 110 through a pump or the like after reaction.

[0086] According to an embodiment of the present invention, the etching gas may remain in the housing 110 for 1 to 4 seconds. Here, the etching gas may remain in the housing 110 for 1 to 4 seconds. Here, the etching gas may remain in the housing 110 for 1 to 4 seconds.

[0087] If the etching gas remains in the housing 110 for less than 1 second, the etching gas does not flow smoothly and thus cannot fully react.

[0088] On the contrary, if the etching gas remains in the housing 110 for more than 4 seconds, byproducts are randomly accumulated in the housing 110 due to polymerization of byproducts, which may adversely affect the process curve, etching rate, and etching rate uniformity.

[0089] Therefore, the etching gas preferably remains in the housing 110 for 1 second to 4 seconds.

[0090] According to an embodiment of the present invention, the plasma formed in the reaction space of the housing 110 includes ions 21 and radicals 22 , and the wafer 10 may be etched by a synergistic effect of the ions 21 and the radicals 22 .

[0091] In addition, according to an embodiment of the present invention, the plasma formed in the reaction space of the housing 110 includes electrons, and an electron energy relaxation length (EERL) of the electrons may be smaller than a diameter of the housing.

[0092] The plasma chamber 100 according to an embodiment of the present invention can be performed in a process region of local electron kinetics. Existing etching processes are performed in a process region of nonlocal electron kinetics where the electron energy relaxation length (EERL) is always greater than the diameter of the process chamber.

[0093] However, the plasma chamber 100 according to the embodiment of the present invention can be performed in a local electron dynamics (LEK) process region where the electron energy relaxation length (EERL) is smaller than the diameter of the process chamber (the diameter of the housing 110 ).

[0094] Therefore, the plasma chamber 100 according to the embodiment of the present invention can make the plasma density at the edge of the shell 110 higher than the plasma density at the center of the shell 110 , and the etching rate at the edge of the shell 110 can also be higher than the etching rate at the center of the shell 110 .

[0095] In the conventional etching process, a problem of weak etching performance at the edge of the wafer (low edge yield problem) may occur. However, the plasma chamber 100 according to an embodiment of the present invention is formed so that the etching rate at the edge of the shell 110 is higher than the etching rate at the center of the shell 110, thereby preventing the above problem from occurring.

[0096] In addition, in the conventional etching process, in order to solve the problem of low edge yield of etching at the edge of the wafer, independent RF power is applied or a heater or a lifting device for preventing edge ring erosion is used.

[0097] However, the plasma chamber 100 according to the embodiment of the present invention is formed such that the etching rate at the edge of the shell 110 is higher than the etching rate at the center of the shell 110, so that a separate device is not required, thereby having the advantage of reducing manufacturing costs and improving profitability.

[0098] The wafer etching method using a plasma chamber according to an embodiment of the present invention relates to a method of etching a wafer 10 by using the plasma chamber 100 according to an embodiment of the present invention as described above.

[0099] In the above description, the plasma chamber 100 according to the embodiment of the present invention is described in detail, and the detailed description of the plasma chamber 100 according to the embodiment of the present invention is omitted below.

[0100] Reference Figure 3 , the wafer etching method using a plasma chamber according to an embodiment of the present invention includes a pressure adjustment step S110 and a source power adjustment step S120.

[0101] The pressure adjustment step S110 is a step of adjusting the pressure inside the housing 110 to 50 to 500 mTorr through the pressure adjustment unit 120 .

[0102] In the plasma chamber according to the embodiment of the present invention, if the pressure inside the housing 110 is less than 50 mTorr, it is difficult to expect to utilize the synergy effect of the ions 21 and the radicals 22 at the same time.

[0103] More specifically, if the pressure inside the housing 110 is less than 50 mTorr, an etching reaction dominated by ions 21 may occur. In addition, when ions 21 and radicals 22 are used simultaneously, if the pressure inside the housing 110 is less than 50 mTorr, there is a risk that the etching rate may decrease.

[0104] If the pressure inside the housing 110 becomes greater than 500 mTorr, the reaction between the particles becomes excessive, so the reaction time becomes short, and thus the etching rate decreases.

[0105] Therefore, in the pressure regulating step S110, the pressure inside the housing 110 is preferably regulated to 50 to 500 mTorr by the pressure regulating unit 120. In addition, according to another embodiment of the present invention, in the pressure regulating step S110, the pressure inside the housing 110 may be regulated to 100 to 150 mTorr, 200 to 500 mTorr, or 300 to 500 mTorr by the pressure regulating unit 120.

[0106] The source power adjustment step S120 is a step of adjusting the source power of the plasma source 130 to 500 to 3000W through the plasma source 130 .

[0107] If the source power (Source power) formed by the above-mentioned plasma source 130 is less than 500W, the etching rate will decrease. Therefore, the source power (Source power) formed by the above-mentioned plasma source 130 is preferably greater than 500W.

[0108] As described above, in the pressure adjustment step S110 , the pressure inside the housing 110 is adjusted to 50 to 500 mTorr by the pressure adjustment unit 120 , so the pressure inside the housing 110 is higher than that of a conventional plasma chamber.

[0109] If the source power of the plasma source 130 is greater than 3000 W, the plasma density becomes too high due to the relatively high internal pressure of the housing 110. If the plasma density becomes too high, the reaction between particles becomes too much, so the reaction time becomes short, and thus the etching rate decreases.

[0110] Therefore, in the source power adjustment step S120, the source power of the plasma source 130 is preferably adjusted to 500 to 3000W.

[0111] In the pressure adjustment step S110 according to the embodiment of the present invention, the pressure inside the housing 110 may be adjusted by the pressure adjustment unit 120 at a pressure equal to or greater than the resonance pressure.

[0112] Here, the resonance pressure may be a pressure formed by making the driving frequency of the plasma source 130 and the collision frequency between particles inside the housing 110 equal to each other.

[0113] If, when the driving frequency (Driving frequency) of the above-mentioned plasma source 130 is 13.56 MHz, the resonance pressure formed by making the driving frequency (Driving frequency) of the above-mentioned plasma source 130 and the collision frequency between the particles inside the above-mentioned shell 110 the same can be 52 mTorr, and when the driving frequency (Driving frequency) of the above-mentioned plasma source 130 is 27.12 MHz, the resonance pressure can be 104 mTorr.

[0114] In the pressure adjustment step S110 according to an embodiment of the present invention, the pressure adjustment unit 120 may adjust the pressure inside the housing 110 at a pressure that is equal to or greater than a resonance pressure determined by a driving frequency of the plasma source 130 .

[0115] According to an embodiment of the present invention, the collision frequency between particles inside the housing 110 may be determined by the product of the number of particles per unit volume and the rate constant for the collision reaction.

[0116] The plasma chamber according to the embodiment of the present invention may include a collision frequency analysis unit for analyzing the collision frequency between particles occurring inside the housing 110. The collision frequency analysis unit may be used to derive a resonance pressure that makes the driving frequency of the plasma source 130 the same as the collision frequency.

[0117] In the pressure regulating step S110 according to an embodiment of the present invention, the pressure regulating unit 120 may receive data on the resonance pressure through the collision frequency analyzing unit, whereby the pressure regulating unit 120 may regulate the pressure inside the shell 110 at a pressure that is the same as or greater than the resonance pressure.

[0118] According to an embodiment of the present invention, the density of the plasma formed in the reaction space of the housing 110 is expressed in cubic centimeters (cm -3 ) is preferably 2E11 to 5E11.

[0119] If the density of the plasma formed in the reaction space of the housing 110 is less than cm -3 )2E11, the expected etching rate cannot be obtained.

[0120] On the contrary, if the density of the plasma formed in the reaction space of the housing 110 is greater than cm -3)5E11, the ions 21 and the free radicals 22 are separated, which will have a bad influence on the selectivity.

[0121] That is, according to the plasma chamber of the embodiment of the present invention, the ions 21 and the radicals 22 are simultaneously used to increase the etching rate, and the density of the plasma formed in the reaction space of the housing 110 is formed to be 1000 μm / cm3 in order to increase the selectivity. -3 ) is calculated as 2E11 to 5E11.

[0122] According to an embodiment of the present invention, the density of the plasma formed in the reaction space of the housing 110 may be adjusted in the source power adjustment step S120. In the source power adjustment step S120, the source power of the plasma source 130 may be adjusted to form the density of the plasma formed in the reaction space of the housing 110 to be 100 cm3. -3 ) is calculated as 2E11 to 5E11.

[0123] Reference Figure 3 According to an embodiment of the present invention, the wafer etching method using a plasma chamber may further include a bias power adjustment step S130 of adjusting the bias power (Bias power) of the bias RF source 140 to 500 to 5000 W through the bias RF source 140.

[0124] The bias RF source 140 applies a bias voltage (Bias) to the base plate 111 , so that a bias voltage can be applied to plasma during the etching process.

[0125] The bias power will directly affect the ions 21. If the bias power of the bias RF source 140 is less than 500W, the activity of the ions 21 will be restricted, resulting in the free radicals 22 being able to dominate the activity, and the synergy effect of the ions 21 and the free radicals 22 cannot be expected.

[0126] On the contrary, if the bias power of the bias RF source 140 is greater than 5000 W, the ions may be dominantly active, and thus the synergy effect of the ions 21 and the free radicals 22 cannot be expected.

[0127] Therefore, in order to induce a synergy effect through the ions 21 and the radicals 22 , the bias power of the bias RF source 140 may be adjusted to 500 to 5000 W in the bias power adjustment step S130 .

[0128] An etching gas for etching a wafer may be supplied into the housing 110 of the plasma chamber 100 according to an embodiment of the present invention. The etching gas supplied into the housing 110 may be exhausted to the outside of the housing 110 through a pump or the like after reaction.

[0129] According to an embodiment of the present invention, the etching gas may remain in the housing 110 for 1 to 4 seconds. Here, the etching gas may remain in the housing 110 for 1 to 4 seconds. Here, the etching gas may remain in the housing 110 for 1 to 4 seconds.

[0130] If the etching gas remains in the housing 110 for less than 1 second, the etching gas does not flow smoothly and thus cannot fully react.

[0131] On the contrary, if the etching gas remains in the housing 110 for more than 4 seconds, byproducts are randomly accumulated in the housing 110 due to polymerization of byproducts, which may have an adverse effect on the process.

[0132] Therefore, the etching gas preferably remains in the housing 110 for 1 second to 4 seconds.

[0133] According to the embodiment of the present invention, the pressure adjustment step S110, the source power adjustment step S120, and the bias power adjustment step S130 of the wafer etching method using a plasma chamber do not need to be performed sequentially, and each process can be performed regardless of the order.

[0134] In addition, the pressure adjustment step S110, the source power adjustment step S120, and the bias power adjustment step S130 of the wafer etching method using a plasma chamber according to an embodiment of the present invention may also be performed simultaneously.

[0135] In this way, the plasma chamber and the wafer etching method using the plasma chamber according to the embodiment of the present invention can adjust the pressure inside the shell 110 through the pressure regulating part 120; adjust the source power through the plasma source 130; and adjust the bias power through the bias RF source 140.

[0136] According to the plasma chamber and the wafer etching method using the plasma chamber according to the embodiments of the present invention, the pressure inside the shell 110, the source power, and the bias power are adjusted to generate a resonant pressure effect caused by the number of particle collisions and simultaneously utilize the ions 21 and the free radicals 22 to generate a synergistic effect, thereby maintaining a high etching rate while improving the selectivity.

[0137] According to an embodiment of the present invention, the plasma formed in the reaction space of the housing 110 includes ions 21 and radicals 22 , and the wafer 10 may be etched by a synergistic effect of the ions 21 and the radicals 22 .

[0138] In addition, according to an embodiment of the present invention, the plasma formed in the reaction space of the housing 110 includes electrons, and an electron energy relaxation length (EERL) of the electrons may be smaller than a diameter of the housing.

[0139] The plasma chamber 100 according to an embodiment of the present invention can be carried out in a process area of ​​local electron dynamics (Local Electron Kinetics) where the electron energy relaxation length (EERL) is smaller than the diameter of the process chamber (the diameter of the above-mentioned shell 110), which is different from the existing etching method which is carried out in a process area of ​​nonlocal electron dynamics (Nonlocal electron kinetics) where the electron energy relaxation length (EERL) is larger than the diameter of the process chamber.

[0140] Therefore, the plasma chamber 100 according to the embodiment of the present invention can make the plasma density at the edge of the shell 110 higher than the plasma density at the center of the shell 110 , and the etching rate at the edge of the shell 110 can also be higher than the etching rate at the center of the shell 110 .

[0141] The plasma chamber 100 according to the embodiment of the present invention is formed such that the etching rate at the edge of the shell 110 is higher than the etching rate at the center of the shell 110, thereby being able to solve the problem of weak etching execution at the edge of the wafer (low edge yield problem), and having the advantage of not using a separate device for solving the above problem.

[0142] Reference Figure 4The plasma chamber and the wafer etching method using the plasma chamber according to the embodiment of the present invention seek to find a process area that can use ions 21 and free radicals 22 for etching at the same time.

[0143] exist Figure 4 In the embodiment, region A is in a stable plasma regime, which may be a region where the plasma maintains stability that does not change over time. Figure 4 The B region is where excessive byproducts are generated. Figure 4 The C region is the region where the plasma etch profile is distorted. Figure 4 Areas B and C cannot be appropriate process areas.

[0144] Figure 4 The middle D region is a region with a center low etch rate. Figure 4 The middle E region is a region where the process results do not change over time and are reproducible. In order to avoid edge yield loss of the wafer while improving reproducibility over time, a region that satisfies both the D region and the E region can become an ideal process region.

[0145] As a result, although it is included in the A area, it does not belong to the B area and the C area and satisfies the D area and the E area at the same time. Figure 4 The F area can become a suitable process area.

[0146] The plasma chamber and the wafer etching method using the plasma chamber according to the embodiment of the present invention can adjust the pressure, source power, bias power and other conditions inside the shell 110 in order to adjust the wafer etching process in the F region where ions 21 and radicals 22 can be used simultaneously.

[0147] That is, according to the plasma chamber of the embodiment of the present invention and the wafer etching method using the plasma chamber, the pressure inside the shell 110, the source power, and the bias power are adjusted, so that the process area can be formed into an F area that can simultaneously utilize the ions 21 and the free radicals 22, thereby generating a synergistic effect of the ions 21 and the free radicals 22, thereby maintaining a high etching rate while improving the selectivity.

[0148] Thus, the plasma chamber and the wafer etching method using the plasma chamber according to the embodiment of the present invention utilize the ions 21 and the radicals 22 at the same time, thereby being able to maintain a high etching rate.

[0149] Reference Figure 5 In the case of using only ions as in the conventional etching method, the etching rate tends to decrease as the pressure increases. Ions are independent of temperature and mainly exert their performance at low pressures. When etching with ions, the bias power needs to be increased in order to increase the etching rate (see Figure 5 , the greater the bias power, the greater the etching rate will be).

[0150] However, free radicals increase exponentially with temperature, and the greater the pressure, the more active the reaction, thereby increasing the etching rate. Therefore, if ions and free radicals are used simultaneously as in the embodiments of the present invention, the pressure will be increased even without increasing the bias power, thereby increasing the etching rate.

[0151] Specifically, refer to Figure 6 It can be seen that when ions and free radicals are used simultaneously as in the embodiment of the present invention, if the pressure increases, the etching rate decreases until a certain point, and if it passes the critical point, the etching rate increases with the increase of pressure.

[0152] From the critical point where the etching rate increases with the increase of pressure, ions and radicals produce a synergy effect to increase the etching rate. According to the plasma chamber and the wafer etching method using the plasma chamber of the embodiment of the present invention, the pressure of the housing 110 is formed to be above the critical point (50 mTorr).

[0153] However, if the pressure continues to increase, the surface reaction time is too short, and thus the etching rate may not increase normally. Therefore, according to the plasma chamber and the wafer etching method using the plasma chamber of the embodiment of the present invention, the pressure of the housing 110 is formed to be 50 mTorr to 500 mTorr.

[0154] exist Figure 6 In the etching rate-pressure curve, the dotted line is the curve when the bias power is lower than the solid line. Figure 6 If the bias power is adjusted to an appropriate size, a high etching rate can be obtained at a pressure above the critical point.

[0155] Therefore, the plasma chamber and the wafer etching method using the plasma chamber according to the embodiment of the present invention can set the bias power to 500 to 5000W and the source power to 500 to 3000W.

[0156] That is, in the plasma chamber and the wafer etching method using the plasma chamber according to the embodiment of the present invention, ions and free radicals produce a synergistic effect to form a pressure that can increase the etching rate, and by adjusting the bias power and the source power, a process area with an optimal etching rate can be specifically realized.

[0157] The plasma chamber according to the embodiment of the present invention may include a control unit for controlling operations of the pressure regulating unit 120 , the plasma source 130 , the RF power generator 132 , and the bias RF source 140 .

[0158] According to an embodiment of the present invention, the pressure regulating unit 120, the plasma source 130, the RF power generator 132, and the bias RF source 140 are regulated by the control unit to form conditions for simultaneously utilizing ions 21 and free radicals 22.

[0159] In addition, the pressure adjustment step S110 , the source power adjustment step S120 , and the bias power adjustment step S130 of the wafer etching method using the plasma chamber according to the embodiment of the present invention may be controlled and performed by the control unit.

[0160] The plasma chamber and the wafer etching method using the plasma chamber according to the embodiment of the present invention have the following effects.

[0161] According to the plasma chamber and the wafer etching method using the plasma chamber of the embodiments of the present invention, the pressure inside the chamber is formed to be relatively higher than the pressure of the existing chamber, so that the wafer can be etched using ions and free radicals at the same time, thereby having the advantage of maintaining a high etching rate while improving the selectivity (PRselectivity).

[0162] The plasma chamber and the wafer etching method using the plasma chamber according to the embodiment of the present invention can be performed within the pressure range (50 to 500 mTorr) applicable to local electron dynamics. In this case, the etching rate at the edge is higher than the etching rate at the center.

[0163] Therefore, the plasma chamber and the wafer etching method using the plasma chamber according to the embodiment of the present invention have the advantage of being able to prevent the uniformity at the edge of the wafer from being reduced.

[0164] The plasma chamber and the wafer etching method using the plasma chamber according to the embodiment of the present invention are suitable for a high aspect ratio etching (HARC) process, and can obtain a high etching rate and a high selectivity at low power even in other processes.

[0165] Although the plasma chamber and the wafer etching method using the plasma chamber according to the embodiment of the present invention are described with the etching process as the center, they are not limited thereto. The plasma chamber and the wafer etching method using the plasma chamber according to the embodiment of the present invention can be applied to deposition, ashing, PR stripping, doping and other processes in addition to the etching process.

[0166] The plasma chamber and the wafer etching method using the plasma chamber according to the embodiment of the present invention can be applied to etching processes or deposition processes that require etching rates, but are not limited thereto. Of course, they can also be applied to various processes that require low power and high etching rates or improved selectivity.

[0167] The plasma chamber and the wafer etching method using the plasma chamber according to the embodiment of the present invention can improve and use inductively coupled plasma (ICP), but are not limited thereto and can also be used for various types of plasma.

[0168] Thus, although the present invention has been described with reference to one embodiment illustrated in the accompanying drawings, this is merely illustrative, and those skilled in the art will appreciate that various modifications and variations of the embodiment are possible. Therefore, the true technical protection scope of the present invention should be determined by the technical ideas of the appended claims.

Claims

1. A plasma chamber is a plasma chamber for forming plasma, wherein the plasma chamber is characterized in that it comprises: A housing having a reaction space therein for etching the wafer by plasma; a bottom plate, which is provided inside the housing and on which the chip is placed; and a pressure regulating unit for regulating the pressure inside the housing; The pressure adjustment unit adjusts the pressure inside the housing to 50 to 500 mTorr.

2. The plasma chamber according to claim 1, characterized in that further comprising a plasma source provided on the upper portion of the housing and forming plasma inside the housing, The source power of the plasma source is 500 to 3000W.

3. The plasma chamber according to claim 2, characterized in that: The pressure regulating unit regulates the pressure inside the housing at a pressure equal to or greater than a resonance pressure, wherein the resonance pressure is formed so that a driving frequency of the plasma source and a collision frequency between particles inside the housing are equal.

4. The plasma chamber according to claim 1, characterized in that The etching gas is supplied into the housing, and the etching gas supplied into the housing is discharged to the outside of the housing after reaction. The etching gas remains in the shell for 1 second to 4 seconds.

5. The plasma chamber according to claim 1, characterized in that The density of the plasma formed in the reaction space of the shell is expressed in cubic centimeters (cm -3 ) is calculated as 2E11 to 5E11.

6. The plasma chamber according to claim 1, characterized in that further comprising a bias RF source connected to the base plate and capable of applying a bias voltage to the base plate, The bias power of the bias RF source is 500 to 5000W.

7. The plasma chamber according to claim 1, characterized in that The plasma formed in the reaction space of the housing includes ions and free radicals. The wafer is etched by a synergy effect of the ions and the radicals.

8. A wafer etching method using a plasma chamber, which is a wafer etching method for etching a wafer using a plasma chamber, wherein: The plasma chamber comprises: a shell having a reaction space inside for etching a wafer by plasma; a bottom plate provided inside the shell and on which the wafer is placed; a pressure regulating part for regulating the pressure inside the shell; and a plasma source provided on the upper part of the shell and forming plasma inside the shell. The wafer etching method using the plasma chamber is characterized by comprising: A pressure regulating step of regulating the pressure inside the housing to 50 to 500 mTorr by the pressure regulating unit; and A source power adjustment step of adjusting the source power of the plasma source to 500 to 3000W by the plasma source.

9. The wafer etching method using a plasma chamber according to claim 8, characterized in that: In the above pressure adjustment step, The pressure inside the housing is adjusted by the pressure adjustment unit at a pressure equal to or greater than a resonance pressure, wherein the resonance pressure is formed so that a driving frequency of the plasma source and a collision frequency between particles inside the housing are equal.

10. The wafer etching method using a plasma chamber according to claim 8, characterized in that: The etching gas is supplied into the housing, and the etching gas supplied into the housing is discharged to the outside of the housing after reaction. The etching gas remains in the shell for 1 second to 4 seconds.

11. The wafer etching method using a plasma chamber according to claim 8, characterized in that: The density of the plasma formed in the reaction space of the shell is expressed in cubic centimeters (cm -3 ) is calculated as 2E11 to 5E11.

12. The wafer etching method using a plasma chamber according to claim 8, characterized in that: The plasma chamber includes a bias RF source connected to the bottom plate and capable of applying a bias to the bottom plate. The wafer etching method further includes a bias power adjustment step of adjusting the bias power of the bias RF source to 500 to 5000W by the bias RF source.

13. The wafer etching method using a plasma chamber according to claim 8, characterized in that: The plasma formed in the reaction space of the housing includes ions and free radicals. The wafer is etched by a synergy effect of the ions and the radicals.

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