201240529 六、發明說明： 【發明所屬之技術領域】 [0001] 本發明涉及一種等離子體發生器的射頻系統，特別涉及 一種用於等離子體發生器的可控制諧波的射頻系統。 【先前技術】 [0002] 目前，在半導體器件的製造過程中，一般在等離子體發 生器的真空處理腔室内，生成引入其中的反應氣體的等 離子體，對處理腔室内放置的基片進行蝕刻等處理。 ^ 現有如雙頻電容耦合等離子體發生器中，真空反應腔内 〇 平行設置有平板式的上電極與下電極。例如，在下電極 上同時施加相隔一定頻率的第一射頻源和第二射頻源， 其中頻率較高的第一射頻源（如60MHz)，用以控制反應 氣體中離子解離或等離子體密度；頻率較低的第二射頻 源（如2MHz)引入偏壓來控制入射到基片的離子能量和 能量分佈。 然而，由於等離子體與射頻源相互作用引起的非線性效 ^ 應，會有高頻的射頻源的二次、三次或其他的諧波產生201240529 VI. Description of the Invention: [Technical Field] [0001] The present invention relates to a radio frequency system for a plasma generator, and more particularly to a radio frequency system for controllable harmonics of a plasma generator. [Prior Art] [0002] At present, in the manufacturing process of a semiconductor device, generally, a plasma of a reaction gas introduced therein is generated in a vacuum processing chamber of a plasma generator, and a substrate placed in the processing chamber is etched, etc. deal with. ^ In the existing dual-frequency capacitively coupled plasma generator, the upper and lower electrodes of the flat plate are arranged in parallel in the vacuum reaction chamber. For example, a first RF source and a second RF source separated by a certain frequency are simultaneously applied to the lower electrode, wherein the first RF source with a higher frequency (such as 60 MHz) is used to control ion dissociation or plasma density in the reactive gas; A low second RF source (e.g., 2 MHz) introduces a bias voltage to control the ion energy and energy distribution incident on the substrate. However, due to the nonlinear effects caused by the interaction of the plasma with the RF source, there will be secondary, tertiary or other harmonic generation of the high frequency RF source.
Lj ，影響反應腔内等離子體分佈：使放置在下電極上的基 片，其中心位置上方的等離子體密度較高，而對應基片 邊緣位置的等離子體密度較低；射頻源的頻率越高，這 種等離子體分佈不均勻的現象越明顯，因而造成基片蝕 刻的不均勻。 【發明内容】 [0003] 本發明的目的是提供一種用於等離子體發生器的可控制 諧波的射頻系統，在射頻源與真空反應腔之間的匹配盒 100143520 表單編號A0101 第3頁/共17頁 1003488283-0 201240529 内設置可輪出調諧阻抗的諧波控制裝置，對高頻的射頻 源的諧波電流進行抑制或調節’以控制等離子體在基片 表面的分佈。 為了達到上述目的，本發明的技術方案是提供—種用於 等離子體發生器的可控制諧波的射頻系統，向驅動電極 施加射頻能量，在等離子體發生器的真空反應腔内，形 成反應氣體的等離子體對基片進行處理，其中，所述射 頻系統包含： 第一射頻源，其提供生成所述等離子體的射頻能量；以 及 匹配盒，其連接在所述第一射頻源與所述驅動電極之間 ，其中設置有匹配電路，使所述反應腔内等離子體的負 載阻抗與所述第一射頻源的輸出阻抗相匹配； 其特點是，所述匹配盒中還設置有諧波控制裝置，與所 述第一射頻源連接，所述諧波控制裝置產生一阻抗值可 裯的調諧阻抗，對所述第一射頻源的諧波阻抗進行調整 〇 所述第一射頻源的諧波電流與所述第一射頻源的功率成 疋比；在所述第一射頻源的功率一定時，其諧波電流與 所述諧波控制裝置輸出的調諧阻抗的阻抗值成反比。 所述基片放置在所述反應腔内底部； 該基片表面的所述等離子體，其密度在對應基片中心的 位置最大並向基片邊緣位置遞減； 所述等離子體對應基片中心及邊緣的該密度差’與所述 第/射頻源的諧波電流成正比’即與所述調諧阻抗的阻 抗值成反比。 ! 〇〇]4352〇 表草編號A_1 第4頁/共Π頁 1_88283~〇 201240529 所述諧波控制裝置是在所述第一射頻源與所述驅動電極 之間串聯設置的電感、低通濾波器或帶阻濾波器； 或者’所述諧波控制裝置是在所述第—射頻源與所述驅 動電極之間並聯接地的電容、高通濾波器或帶通濾波器 所述諧波控制裝置是所述串聯設置的電感，其電感值為 0. 1/zH ~100/zH。Lj, affecting the plasma distribution in the reaction chamber: the substrate placed on the lower electrode has a higher plasma density above the center position, and the plasma density at the edge position of the corresponding substrate is lower; the higher the frequency of the RF source, This phenomenon of uneven plasma distribution is more pronounced, resulting in uneven etching of the substrate. SUMMARY OF THE INVENTION [0003] It is an object of the present invention to provide a controllable harmonic radio frequency system for a plasma generator, a matching box between the RF source and the vacuum reaction chamber 100143520 Form No. A0101 Page 3 / Total On page 17 of 1003488283-0 201240529, a harmonic control device that can rotate the tuning impedance is set to suppress or adjust the harmonic current of the high-frequency RF source to control the distribution of the plasma on the surface of the substrate. In order to achieve the above object, the technical solution of the present invention provides a radio frequency system for controlling harmonics of a plasma generator, applying radio frequency energy to a driving electrode, and forming a reaction gas in a vacuum reaction chamber of the plasma generator. Plasma processing the substrate, wherein the radio frequency system comprises: a first RF source that provides RF energy to generate the plasma; and a matching box coupled to the first RF source and the driver Between the electrodes, a matching circuit is disposed to match the load impedance of the plasma in the reaction chamber with the output impedance of the first RF source; and the matching box is further provided with a harmonic control device And connecting to the first RF source, the harmonic control device generates a tuning impedance with a resistable value, adjusting a harmonic impedance of the first RF source, and a harmonic current of the first RF source Comparing with the power of the first RF source; when the power of the first RF source is constant, the harmonic current and the output of the harmonic control device are adjusted The impedance of the harmonic impedance is inversely proportional. The substrate is placed in the bottom of the reaction chamber; the plasma on the surface of the substrate has a density at a position corresponding to the center of the substrate and decreases toward the edge of the substrate; the plasma corresponds to the center of the substrate and The density difference 'is proportional to the harmonic current of the first/radio frequency source' is inversely proportional to the impedance value of the tuning impedance. !〇〇]4352〇草草号 A_1 Page 4/Total Page 1_88283~〇201240529 The harmonic control device is an inductor, low-pass filter arranged in series between the first RF source and the drive electrode Or a band rejection filter; or 'the harmonic control device is a capacitor, a high pass filter or a band pass filter that is grounded in parallel between the first RF source and the drive electrode, the harmonic control device is The inductance of the series is set to have an inductance value of 0.1/zH to 100/zH.
所述諧波控制裝置是所述低通濾波器，其進一步包含在 所述第一射頻源與所述驅動電極之間串聯設置的兩個電 感，以及在所述兩個電感之間並聯接地的電容；所述兩 個電感為66nH ;所述電容為53pF。 所述射頻系統還包含控制反應腔内離子能量和能量分佈 的第二射頻源；所述第二射頻源的頻率以一定的間隔差 小於所述第一射頻源的頻率。The harmonic control device is the low pass filter, further comprising two inductors arranged in series between the first RF source and the drive electrode, and grounded in parallel between the two inductors Capacitance; the two inductors are 66nH; the capacitance is 53pF. The radio frequency system further includes a second radio frequency source that controls ion energy and energy distribution within the reaction chamber; the frequency of the second radio frequency source is less than a frequency of the first radio frequency source by a certain interval.
所述第一射頻源的可選頻率包含27MHz ’ 40MHz，60MHz ，100MHz或120MHz ;所述第二射頻源的可選頻率包含 13MHz ， 2MHz或400KHZ 。 本發明尤其適用於頻率大於40 MHz的所述第一射頻源。 所述驅動電極包含在所述反應腔内平行設置的上電極和 下電極； 所述第一射頻源，通過所述匹配盒施加至所述上電極或 下電極之一；所述匹配盒中為所述第一射頻源配置有所 述匹配電路及諳波控制裝置； 所述第二射頻源，通過同一個或另外設置的匹配盒，施 加至所述上電極或下電極上，並與所述第一射頻源施加 在相同或不同的所述射頻電極上；所述匹配盒中為所述 100143520 表單編號A0101 1003488283-0 201240529 第二射頻源配置有所述匹配電路。 調整第-射頻源的譜波阻抗的所述諧波控制裝置，其設 置於所述第-射頻源的匹配電路的輸出端與所述射頻: 極之間； ' 或者，所述諧波控制裝置設置於所述第二__隨 電路的輸出端與所述射頻電極之間，並與所 /、 I弟~射頻 源連接； 第二射頻源 或者，所述諳波控制裝置設置於所述第一The selectable frequency of the first RF source comprises 27 MHz '40 MHz, 60 MHz, 100 MHz or 120 MHz; the selectable frequency of the second RF source comprises 13 MHz, 2 MHz or 400 KHz. The invention is particularly applicable to said first RF source having a frequency greater than 40 MHz. The driving electrode includes an upper electrode and a lower electrode disposed in parallel in the reaction chamber; the first RF source is applied to one of the upper electrode or the lower electrode through the matching box; The first RF source is configured with the matching circuit and the chopper control device; the second RF source is applied to the upper or lower electrode through a matching box provided with the same or separately, and The first RF source is applied to the same or different RF electrodes; the matching box is the 100143520 Form No. A0101 1003488283-0 201240529 The second RF source is configured with the matching circuit. The harmonic control device for adjusting the spectral impedance of the first-radio frequency source is disposed between the output end of the matching circuit of the first-radio frequency source and the radio frequency: pole; or alternatively, the harmonic control device And being disposed between the output end of the second __comprising circuit and the radio frequency electrode, and connected to the RF source; the second RF source or the chopper control device is disposed in the One
的匹配電路的公共輸出端與所述射頻電極之間 或者，所述第一射頻源的匹配電路的輸出端，和所述第 二射頻源的匹配電路的輸出端，分別連接有—諧波控制 裝置。The common output end of the matching circuit and the RF electrode or the output end of the matching circuit of the first RF source and the output end of the matching circuit of the second RF source are respectively connected with - harmonic control Device.
與現有技術相比，本發明所述用於等離子體發生器的可 控制諧波的射頻系統，其優點在於··本發明通過所述諧 波控制裝置，可以輸出一高阻抗的調諧阻抗來抑制第一 射頻源的二次、三次的諳波電流，使基片表面的等離子 體能均勻分佈；或者，通過使其輸出的調諧阻抗在高阻 抗至低阻抗之間可調，來控制諧波電流的大小，從而可 在基片中心及邊緣表面獲得不同的等離子體密度，並對 應產生不同的蝕刻效果。 【實施方式】 [0004] 以下結合附圖說明本發明的具體實施方式。 本發明所述用於等離子體發生器的可控制諧波的射頻系 統，在射頻源與射頻電極之間的匹配盒中設置諧波控制 裝置，其提供一調諧阻抗對高頻的射頻源的諧波電流進 100143520 行抑制或調節 表單編號A0101 以下結合具體實施例對本發明進行描 第6頁/共17頁 述 1003488283-0 201240529 第1圖疋根據本發明的一個具體實施例的用於等離子體發 生益的可控制請波的射頻系統的總體結構示意圖，如第1 圖所7^ ’在等離子體發生器中設置有真空的反應腔30， 在其底部的靜電吸盤33 (ESC)上放置基片40，該靜電吸 盤33中°又置有下電極31，在反應腔30内頂部設置有與下 電極1平行的上電極Μ。在射頻系統作用下，引入反應 腔30的反應氣體能夠解離形成等離子體50，從而進-少地對所述基>;4Q進行㈣等處理。 \ 所述射頻系統’包含以電纜等與所述下電極31電性連接 的一匹配盒20 (matching box) ’以及通過所述匹配盒 20施加至所述下電極31的第一射頻源11、第二射頻源12 〇 其中’所述第—射頻源11的頻率較高，通過在上下電極 之間形成射頻電場，對等離子體5〇的生成及密度進行控 制°所述第二射頻源丨2通過控制等離子體50鞠層自偏壓 ’對入射到基片40的離子能量和能量分佈進行控制。所 2 述第一射頻源11的頻率可以是27MHz，40MHz，60MHz， 100MHz或120MHz等；與之相匹配，所述第二射頻源12的 頻率可以是13MHz，2MHz或400KHZ等。 所述匹配盒20通過設置的匹配電路（圖中未示出），使 所述反應腔30内等離子體50的負載阻抗與所述第一、第 二射頻源的輸出阻抗相匹配，來減少所述第一、第二射 頻源的反射率，從而使第一、第二射頻源各自以最大的 輸出功率施加至所述下電極31。 為了實現諧波控制，本實施例所述射頻系統，在所述匹 ⑽麵 表料號删1 ^ 7 S/* 17 1 1003488283-° 201240529 配盒20的輸出端，即所述第…第二射頻源的匹配電路 的A八知之後，進一步設置有一諧波控制裝置2丨。所述 '•白波控制裝置21提供了一阻抗值可調的調諧阻抗，對其 中尚頻的第一射頻源11的諧波阻抗進行調整從而對該 第射頻源11的二次、三次的諧波電流進行控制。 需要說明的是，本發明尤其適用於第一射頻源11的射頻 為大於40 MHz的應用場合，在此情況下，本發明的發明 效果最佳’可以更好地通過輸出一高阻抗的所述調諧阻 抗來抑制第一射頻源11的二次、三次的諧波電流，使基 片40表面的等離子體50能均勻分佈；或者，更有效地通 過使其輸出的調諧阻抗在高阻抗至低阻抗之間可調，來 控制該諧波電流的大小，此時可在基片4 0中心及邊緣表 面獲得不同的等離子體密度，從而對應產生不同的蝕刻 效果。 可選地，所述諧波控制裝置21是在所述第一射頻源11與 所述驅動電極之間串聯設置的電感、低通濾波器或帶阻 濾波器；或者，所述諧波控制裝置21是在所述第一射頻 源11與所述下電極31之間並聯接地的電容、高通遽波器 或帶通濾波器。 可選地，可以配置〇.l"H〜100的串聯電感作為所述 諳波控制裝置21，其適用於調節，定頻率範圍内的第 射頻源11的諧波控制；優選的，所述電感值可以是2// H~3/zH。 # 可選地，如第2圖所示，可以配置低通濾波器作為所 波控制裝置2卜能夠針對某-特定的卜射頻源11頻: 產生的減進行精確調節。具體地’所述低通U器⑽ 100143520 表單編號A0101 第8頁/共17頁 201240529 含在所述第一射頻源1 1與所述下電極3 1之間串聯設置的 兩個電感，以及在所述兩個電感之間並聯接地的電容。 優選的，當所述第一射頻源11為60MHz時，所述兩個電感 為66nH，所述電容為53pF。Compared with the prior art, the radio frequency system of the controllable harmonics of the plasma generator of the present invention has the advantage that the present invention can output a high impedance tuning impedance to suppress by the harmonic control device. The second and third chopping currents of the first RF source uniformly distribute the plasma energy on the surface of the substrate; or, by adjusting the tuning impedance of the output from high impedance to low impedance, to control the harmonic current The size is such that different plasma densities can be obtained at the center and edge surfaces of the substrate, and correspondingly different etching effects are produced. [Embodiment] Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. The radio frequency system for controlling harmonics of the plasma generator of the present invention sets a harmonic control device in a matching box between the RF source and the RF electrode, which provides a harmonic of the tuning impedance to the high frequency RF source. Wave current into 100143520 line suppression or adjustment form number A0101 The following is a description of the present invention in conjunction with a specific embodiment. Page 6 of 17 1003488283-0 201240529 FIG. 1 is a plasma generation process according to an embodiment of the present invention. The overall structure of the radio frequency system of the control wave can be controlled, as shown in Fig. 1 ''. The reaction chamber 30 is provided with a vacuum in the plasma generator, and the substrate is placed on the electrostatic chuck 33 (ESC) at the bottom. 40. The lower electrode 31 is further disposed in the electrostatic chuck 33, and an upper electrode 平行 parallel to the lower electrode 1 is disposed at the top of the reaction chamber 30. Under the action of the radio frequency system, the reaction gas introduced into the reaction chamber 30 can be dissociated to form the plasma 50, thereby performing (four) and the like on the base >; 4Q. The radio frequency system 'includes a matching box 20 that is electrically connected to the lower electrode 31 by a cable or the like, and a first radio frequency source 11 that is applied to the lower electrode 31 through the matching box 20, The second RF source 12 〇 wherein the frequency of the first RF source 11 is relatively high, and the generation and density of the plasma 5 控制 are controlled by forming a radio frequency electric field between the upper and lower electrodes. The second RF source 丨 2 The ion energy and energy distribution incident on the substrate 40 is controlled by controlling the plasma 50 自 self-biasing'. The frequency of the first RF source 11 may be 27 MHz, 40 MHz, 60 MHz, 100 MHz or 120 MHz, etc., and the frequency of the second RF source 12 may be 13 MHz, 2 MHz or 400 KHZ or the like. The matching box 20 matches the load impedance of the plasma 50 in the reaction chamber 30 with the output impedance of the first and second RF sources through a matching circuit (not shown) to reduce the The reflectivity of the first and second RF sources is such that the first and second RF sources are each applied to the lower electrode 31 at the maximum output power. In order to realize the harmonic control, the radio frequency system in the embodiment has the output of the box 20 in the surface of the piece (10), and the second end of the box 20, that is, the second... After the A-knowledge of the matching circuit of the RF source, a harmonic control device 2 is further provided. The '• white wave control device 21 provides a tuning impedance with an adjustable impedance value, and adjusts the harmonic impedance of the first RF source 11 that is still frequency to the second and third harmonics of the first RF source 11. Current is controlled. It should be noted that the present invention is particularly applicable to applications in which the radio frequency of the first radio frequency source 11 is greater than 40 MHz. In this case, the invention of the present invention is optimally capable of better outputting a high impedance. The impedance is tuned to suppress the second and third harmonic currents of the first RF source 11, so that the plasma 50 on the surface of the substrate 40 can be uniformly distributed; or, more effectively, the tuning impedance of the output is high impedance to low impedance. It can be adjusted to control the magnitude of the harmonic current. At this time, different plasma densities can be obtained at the center and edge surfaces of the substrate 40, thereby correspondingly producing different etching effects. Optionally, the harmonic control device 21 is an inductor, a low pass filter or a band rejection filter disposed in series between the first RF source 11 and the driving electrode; or the harmonic control device 21 is a capacitor, a high-pass chopper or a band-pass filter that is grounded in parallel between the first RF source 11 and the lower electrode 31. Optionally, a series inductance of 〇.l "H~100 may be configured as the chopper control device 21, which is suitable for adjusting harmonic control of the first RF source 11 in a fixed frequency range; preferably, the inductance The value can be 2// H~3/zH. # Optionally, as shown in Fig. 2, a low-pass filter can be configured as the wave control device 2 to accurately adjust the generated frequency for a certain specific RF source. Specifically, the low-pass U-device (10) 100143520 Form No. A0101, page 8 / page 17 201240529 includes two inductors arranged in series between the first RF source 11 and the lower electrode 31, and A capacitor connected in parallel between the two inductors. Preferably, when the first RF source 11 is 60 MHz, the two inductors are 66 nH and the capacitance is 53 pF.
結合第1圖，第3圖示出了以第一射頻源11的頻率60MHz ’第二射頻源12的頻率2MHz的具體實施例中，所述諧波 控制裝置21對第一射頻源11的二次諧波電流的調製作用 :第3圖中橫坐標表示基片40的直徑*縱坐標表示對基片 40上氧化物蝕刻的速率。可見’在所述諧波控制裝置21 沒有輸出調諧阻抗或者輸出一低阻抗的調諧阻抗時，所 述二次諧波電流較大，即對應基片40中心位置的等離子 體50密度較高，邊緣位置較低’如起伏較大的曲線1所示 ，5400A/min以上的蝕刻基片40中心的速率，要遠遠快 於餘刻基片40最邊緣約4200A/min的速率。Referring to FIG. 1 , FIG. 3 shows a specific embodiment of the first RF source 11 with a frequency of 60 MHz of the first RF source 11 and a frequency of 2 MHz of the second RF source 12 . Modulation of subharmonic current: In Fig. 3, the abscissa indicates the diameter of the substrate 40. The ordinate indicates the rate at which the oxide on the substrate 40 is etched. It can be seen that when the harmonic control device 21 does not output the tuning impedance or outputs a low impedance tuning impedance, the second harmonic current is large, that is, the plasma 50 corresponding to the center position of the substrate 40 has a higher density, and the edge The position is lower, as shown by curve 1 where the undulation is larger, the rate at which the center of the substrate 40 is etched above 5400 A/min is much faster than the rate at which the outermost edge of the substrate 40 is about 4200 A/min.
與之相比，若所述諧波控制裝置21輪出一高阻抗的調諧 阻抗’則能使二次諧波電流變小’相應地使對應基片4〇 中心與基片40邊緣位置的等離子體5〇密度差變小，即蚀 刻基片40中心的速率減小至4700A/min左右，其與蝕刻 基片40邊緣的速率420〇A/miη左右之間的速率差明顯變 小，因此獲得的曲線2較為平坦。 因而，本發明所述諧波控制裝置21，可以通過輸出一高 阻抗的調諧阻抗來抑制第一射頻源u的二次、三次的諧 波電流’使基片40表面的等離子體5〇能均句分佈；或者 ，通過使其輸㈣_崎在高阻抗至録抗之間可調 ’來控制諧㈣流的大小，並對應在基片4{)中心及邊緣 100143520 獲得不同的等離子體密度，以產生不同的蝕刻效果。 表單編號A0101 第9頁/共17頁 1003488283-0 201240529 本發明的實施結構並不限於上述描述，例如，所述第一 射頻源還可以通過匹配盒施加到上電極上；所述第二射 頻源可以是施加在與所述第一射頻源相同或不同的上電 極或下電極上。上述給出了諧波控制裝置設置在第一、 第二射頻源的匹配電路公共端之後的結構（第1圖）；該 諧波控制裝置還可以僅在第一射頻源的匹配電路之後設 置，或者僅在第二射頻源的匹配電路之後設置；又或者 ，第一、第二射頻源的匹配電路之後分別設置一諧波控 制裝置，但所述諧波控制裝置只對高頻的第一射頻源的 諧波電流進行調整。 儘管本發明的内容已經通過上述優選實施例作了詳細介 紹，但應當認識到上述的描述不應被認為是對本發明的 限制。在本領域技術人員閲讀了上述内容後，對於本發 明的多種修改和替代都將是顯而易見的。因此，本發明 的保護範圍應由所附的申請專利範®來限定。 【圖式簡單說明】 [0005] 第1圖是根據本發明的一個具體實施例的用於等離子體發 生器的可控制諧波的射頻系統的總體結構示意圖； 第2圖是根據本發明的一個具體實施例的射頻系統中所述 諧波控制裝置是低通濾波器時的電路結構示意圖； 第3圖是根據本發明的一個具體實施例的射頻系統在不同 的阻抗下對基片不同位置的蝕刻速率的示意圖。 【主要元件符號說明】 [0006] 11 :第一射頻源 12 :第二射頻源 100143520 表單編號A0101 第10頁/共17頁 1003488283-0 201240529 20 :匹配盒 21 :諧波控制裝置 30 :真空反應腔 31 :下電極 32 :上電極 33 :靜電吸盤 40 :基片 50 :離子體 6 0 :反應氣體 〇 100143520 表單編號A0101 第11頁/共17頁 1003488283-0In contrast, if the harmonic control device 21 rotates a high-impedance tuning impedance ', the second harmonic current can be made smaller' correspondingly to the plasma of the center of the corresponding substrate 4 and the edge of the substrate 40. The difference in density of the body 5〇 becomes small, that is, the rate at which the center of the substrate 40 is etched is reduced to about 4700 A/min, and the rate difference between the rate of the edge of the substrate 40 and the edge of the substrate 40 is significantly reduced, so that Curve 2 is relatively flat. Therefore, the harmonic control device 21 of the present invention can suppress the secondary and tertiary harmonic currents of the first RF source u by outputting a high-impedance tuning impedance to make the plasma of the surface of the substrate 40 5 均. Sentence distribution; or, by adjusting its output (four)_sat between high impedance and recording resistance to control the magnitude of the harmonic (four) stream, and corresponding to different plasma densities at the center of the substrate 4{) and the edge 100143520, To produce different etching effects. Form No. A0101 Page 9 of 17 1003488283-0 201240529 The implementation structure of the present invention is not limited to the above description, for example, the first RF source may also be applied to the upper electrode through a matching box; the second RF source It may be applied to the upper or lower electrode that is the same or different from the first RF source. The above structure is given after the harmonic control device is disposed at the common end of the matching circuit of the first and second RF sources (Fig. 1); the harmonic control device may also be disposed only after the matching circuit of the first RF source, Or only after the matching circuit of the second RF source; or alternatively, a matching control circuit of the first and second RF sources is respectively provided with a harmonic control device, but the harmonic control device only applies to the first RF of the high frequency The harmonic current of the source is adjusted. Although the present invention has been described in detail by the preferred embodiments thereof, it should be understood that the foregoing description should not be construed as limiting. Various modifications and alterations of the present invention will be apparent to those skilled in the art. Accordingly, the scope of the invention should be defined by the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS [0005] FIG. 1 is a general structural diagram of a radio frequency system for controllable harmonics of a plasma generator according to an embodiment of the present invention; FIG. 2 is a diagram according to the present invention. FIG. 3 is a schematic diagram showing the circuit structure of the radio frequency system in the radio frequency system of the specific embodiment when the harmonic control device is a low-pass filter; FIG. 3 is a view showing the radio frequency system at different positions of the substrate under different impedances according to an embodiment of the present invention; Schematic of the etch rate. [Main component symbol description] [0006] 11: First RF source 12: Second RF source 100143520 Form No. A0101 Page 10 of 17 1003488283-0 201240529 20: Matching box 21: Harmonic control device 30: Vacuum reaction Cavity 31: Lower electrode 32: Upper electrode 33: Electrostatic chuck 40: Substrate 50: Ionic body 6 0: Reaction gas 〇100143520 Form No. A0101 Page 11 of 17 1003488283-0