TWI769447B - Method and device for multi-frequency and multi-stage plasma radio frequency output - Google Patents
Method and device for multi-frequency and multi-stage plasma radio frequency output Download PDFInfo
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Abstract
一種用於電漿蝕刻的射頻功率輸出的方法,包括:提供複數個射頻產生器,每個射頻產生器輸出各自不同頻率的射頻功率,每個射頻產生器輸出的功率可變,提供控制器,控制器控制複數個射頻產生器在連續脈衝期間輸出射頻功率,連續脈衝的一個脈衝週期包括三個連續階段,在每個階段,至少一個射頻產生器輸出射頻功率,三個連續階段分別為產生電漿階段、蝕刻階段、維持電漿階段,脈衝週期的週期長度為50us-0.1s。該方法可以實現更快的切換速度,在脈衝模式下進行帶功率的射頻頻率切換。 A method for outputting radio frequency power for plasma etching, comprising: providing a plurality of radio frequency generators, each radio frequency generator outputting radio frequency power of respective different frequencies, the output power of each radio frequency generator being variable, providing a controller, The controller controls a plurality of radio frequency generators to output radio frequency power during the continuous pulse. One pulse period of the continuous pulse includes three continuous stages. In each stage, at least one radio frequency generator outputs radio frequency power. In the plasma stage, the etching stage and the sustaining plasma stage, the period length of the pulse period is 50us-0.1s. This method can achieve faster switching speed and perform RF frequency switching with power in pulsed mode.
Description
本發明係關於射頻脈衝輸出方法,更關於執行該方法的射頻源系統以及包括該射頻源系統的電漿蝕刻裝置。 The present invention relates to a radio frequency pulse output method, and more particularly to a radio frequency source system for implementing the method and a plasma etching apparatus including the radio frequency source system.
現有半導體加工中廣泛採用電漿蝕刻設備對半導體晶圓進行加工,以獲得微型尺寸的半導體裝置及導體連接。常見的電漿蝕刻設備是電容耦合型(CCP)及電感耦合型(ICP)蝕刻機,這些設備一般具有兩個射頻產生器,其中一個用來電離通入反應腔內的反應氣體使之產生電漿,另一個射頻產生器用來控制入射到晶圓表面的離子能量。 In existing semiconductor processing, plasma etching equipment is widely used to process semiconductor wafers to obtain micro-sized semiconductor devices and conductor connections. Common plasma etching equipment is capacitively coupled (CCP) and inductively coupled (ICP) etcher. These devices generally have two radio frequency generators, one of which is used to ionize the reactant gas introduced into the reaction chamber to generate electricity. slurry, another RF generator is used to control the ion energy incident on the wafer surface.
現在,很多電漿加工流程使用脈衝式電漿射頻產生器以取代持續式電漿射頻產生器。脈衝式電漿射頻產生器的特點是在整個加工時段,射頻電源不是持續供電而是交替進行開通及關閉供電或者交替進行高功率及低功率的射頻供電,其輸出功率的波形呈脈衝形式。開通-關閉的工作週期可以調整,一般在10%-90%範圍內。脈衝式電漿射頻的優勢是在關閉階段,矽片表面的鞘層消失,積聚在矽片表面以及在蝕刻出的深孔邊緣中的電子因鞘層的消失而與矽片中和,此時更多的電子能進入深孔的底部從而中和積聚在底部的離子,這樣在下一個開通階段有利於對深孔的進一步的蝕刻。並且,在同一個脈衝中,電漿產生器的頻率也可以切換以適用於不同的蝕刻製程。 Today, many plasma machining processes use pulsed plasma RF generators instead of continuous plasma RF generators. The characteristic of the pulsed plasma RF generator is that during the whole processing period, the RF power supply is not continuously powered, but alternately turns on and off the power supply or alternately performs high-power and low-power RF power supply, and the waveform of its output power is in the form of pulses. The open-close duty cycle can be adjusted, generally within the range of 10%-90%. The advantage of pulsed plasma radio frequency is that in the off stage, the sheath on the surface of the silicon wafer disappears, and the electrons accumulated on the surface of the silicon wafer and in the edge of the etched deep hole are neutralized with the silicon wafer due to the disappearance of the sheath. More electrons can enter the bottom of the deep hole to neutralize the ions accumulated at the bottom, which facilitates further etching of the deep hole in the next turn-on stage. And, in the same pulse, the frequency of the plasma generator can also be switched for different etching processes.
現有的可切換雙頻電漿系統利用繼電器進行具有不同頻率的射頻產生器之間的切換,其缺點有兩點:一是不能在有功率輸出情況下進行切換 或者只有在小功率下才能進行切換;二是在脈衝功率模式下不能進行切換,因為繼電器切換是機械動作,其反應時間遠大於脈衝週期。所以,現有的雙頻電漿切換技術只能用於小功率及脈衝時間較長(秒的量級)的功率輸出場合,而且不容易維持連續電漿運行。 The existing switchable dual-frequency plasma system uses relays to switch between radio frequency generators with different frequencies, which has two disadvantages: one is that the switching cannot be performed under the condition of power output. Or it can only be switched under low power; the second is that it cannot be switched in the pulse power mode, because the relay switching is a mechanical action, and its response time is much longer than the pulse period. Therefore, the existing dual-frequency plasma switching technology can only be used in power output occasions with low power and long pulse time (on the order of seconds), and it is not easy to maintain continuous plasma operation.
針對上述問題,在第一方面,本發明提出了一種用於電漿蝕刻的射頻功率輸出的方法,該方法包括:提供複數個射頻產生器,每個射頻產生器輸出各自不同頻率的射頻功率,用於輸出到一個電漿蝕刻器,每個射頻產生器輸出的功率可變,提供控制器,控制器控制複數個射頻產生器的輸出射頻功率在連續進行的複數個脈衝週期中變化,其中每個脈衝週期包括三個處理階段,在每個處理階段中至少一個射頻產生器輸出射頻功率,三個處理階段分別為依序進行的產生電漿階段、蝕刻階段、維持電漿階段,脈衝週期的週期長度為50us-0.1s,複數個射頻產生器至少包括三個射頻產生器,分別為高頻射頻產生器、中頻射頻產生器及低頻射頻產生器,其中高頻射頻產生器在產生電漿階段輸出第一高頻射頻功率到電漿蝕刻器以產生足夠濃度的電漿,在維持電漿階段輸出第二高頻射頻功率到電漿蝕刻器以維持電漿。 In view of the above problems, in a first aspect, the present invention proposes a method for outputting radio frequency power for plasma etching, the method comprising: providing a plurality of radio frequency generators, each radio frequency generator outputting radio frequency power of different frequencies, For output to a plasma etcher, the power output of each radio frequency generator is variable, and a controller is provided, and the controller controls the output radio frequency power of the plurality of radio frequency generators to change in a continuous plurality of pulse cycles, wherein each Each pulse cycle includes three processing stages. In each processing stage, at least one RF generator outputs RF power. The three processing stages are the plasma generation stage, the etching stage, and the maintenance plasma stage, which are performed in sequence. The cycle length is 50us-0.1s, and the plurality of RF generators include at least three RF generators, which are high-frequency RF generators, intermediate-frequency RF generators and low-frequency RF generators, among which the high-frequency RF generators are generating plasma. The stage outputs a first high frequency radio frequency power to the plasma etcher to generate a plasma of sufficient concentration, and a second high frequency radio frequency power is output to the plasma etcher to maintain the plasma in the sustaining plasma stage.
較佳地,在每個階段,至多兩個射頻產生器同時輸出射頻功率。 Preferably, at most two RF generators simultaneously output RF power at each stage.
較佳地,高頻射頻產生器的輸出頻率為40MHz-100MHz、中頻射頻產生器的輸出頻率為10MHz-20MHz、低頻射頻產生器的輸出頻率為200kHz-4MHz。 Preferably, the output frequency of the high frequency radio frequency generator is 40MHz-100MHz, the output frequency of the intermediate frequency radio frequency generator is 10MHz-20MHz, and the output frequency of the low frequency radio frequency generator is 200kHz-4MHz.
較佳地,在產生電漿階段,中頻射頻產生器輸出第一中頻射頻功率,用於產生電漿及反應基團。 Preferably, in the stage of generating plasma, the intermediate frequency radio frequency generator outputs first intermediate frequency radio frequency power for generating plasma and reactive groups.
較佳地,在蝕刻階段,中頻射頻產生器及低頻射頻產生器輸出第二中頻射頻功率及第一低頻射頻功率,用於進行高深寬比蝕刻。 Preferably, in the etching stage, the intermediate frequency radio frequency generator and the low frequency radio frequency generator output the second intermediate frequency radio frequency power and the first low frequency radio frequency power for performing high aspect ratio etching.
較佳地,在維持電漿階段,低頻射頻產生器停止輸出射頻功率以釋放加工工件的電荷累積。 Preferably, during the sustaining plasma phase, the low frequency RF generator stops outputting RF power to release the charge accumulation of the processed workpiece.
較佳地,高頻射頻產生器及中頻射頻產生器輸出的功率範圍是50W-10kW。 Preferably, the output power range of the high frequency radio frequency generator and the intermediate frequency radio frequency generator is 50W-10kW.
較佳地,低頻射頻產生器輸出的功率範圍是100W-20kW。 Preferably, the output power of the low frequency radio frequency generator is in the range of 100W-20kW.
本發明還提出了一種用於電漿蝕刻的射頻功率輸出的方法,該方法包括:提供複數個射頻產生器,每個射頻產生器向電漿蝕刻裝置輸出各自不同頻率的射頻功率,每個射頻產生器輸出的功率可變,提供控制器,控制器控制複數個射頻產生器的輸出射頻功率在連續進行的複數個脈衝週期中變化,其中每個脈衝週期包括三個處理階段,在每個處理階段中至少一個射頻產生器輸出射頻功率,其中,三個處理階段分別為依序進行的產生電漿階段、初蝕刻階段、主蝕刻階段,脈衝週期的週期長度為50us-0.1s,複數個射頻產生器至少包括三個射頻產生器,分別為高頻射頻產生器、中頻射頻產生器及低頻射頻產生器,其中高頻射頻產生器在三個處理階段分別輸出第一高頻射頻功率、第二高頻射頻功率及第三高頻射頻功率。 The present invention also provides a method for outputting radio frequency power for plasma etching. The method includes: providing a plurality of radio frequency generators, each radio frequency generator outputs radio frequency power of different frequencies to the plasma etching device, and each radio frequency generator outputs radio frequency power of different frequencies to the plasma etching device. The power output of the generator is variable, and a controller is provided, and the controller controls the output radio frequency power of the plurality of radio frequency generators to change in a continuous plurality of pulse cycles, wherein each pulse cycle includes three processing stages, and in each process At least one radio frequency generator in the stages outputs radio frequency power, wherein, the three processing stages are respectively a plasma generation stage, an initial etching stage, and a main etching stage, which are performed in sequence. The generator includes at least three radio frequency generators, which are a high frequency radio frequency generator, an intermediate frequency radio frequency generator and a low frequency radio frequency generator, wherein the high frequency radio frequency generator outputs the first high frequency radio frequency power and the third The second high frequency radio frequency power and the third high frequency radio frequency power.
較佳地,在產生電漿階段,中頻射頻產生器同時輸出第一中頻射頻功率,用於產生電漿及反應基團。 Preferably, in the stage of generating plasma, the intermediate frequency radio frequency generator simultaneously outputs the first intermediate frequency radio frequency power for generating plasma and reactive groups.
較佳地,在初蝕刻階段,低頻射頻產生器輸出第一低頻射頻功率。 Preferably, in the initial etching stage, the low frequency radio frequency generator outputs the first low frequency radio frequency power.
較佳地,在主蝕刻階段,中頻射頻產生器輸出第二中頻射頻功率。 Preferably, in the main etching stage, the intermediate frequency radio frequency generator outputs the second intermediate frequency radio frequency power.
在第二方面,本發明提出了一種電漿蝕刻裝置的射頻源系統,包括:複數個射頻產生器,用於輸出射頻功率,複數個射頻產生器中的每個射頻產生器輸出不同頻率的功率;控制器,用於控制複數個射頻產生器,使得複數個射頻產生器執行上述的方法。 In a second aspect, the present invention provides a radio frequency source system of a plasma etching device, comprising: a plurality of radio frequency generators for outputting radio frequency power, and each radio frequency generator in the plurality of radio frequency generators outputs power of different frequencies a controller for controlling a plurality of radio frequency generators, so that the plurality of radio frequency generators execute the above method.
在第三方面,本發明提出了一種電漿處理裝置,包括反應腔;基座,位於反應腔內,且用於支撐待處理的基片;以及在第二方面中的射頻源系統,用於向反應腔提供射頻功率。 In a third aspect, the present invention provides a plasma processing apparatus, comprising a reaction chamber; a base located in the reaction chamber and used to support a substrate to be processed; and a radio frequency source system in the second aspect, used for RF power is supplied to the reaction chamber.
本發明和透過繼電器進行頻率切換的現有技術相比,可以實現更快的切換速度,在脈衝模式下進行帶功率的射頻頻率切換。並且,可以根據不同的基片處理過程,在一個脈衝週期內劃分出任何階段,在每個階段中,靈活設置各種射頻產生器的參數,如輸出射頻產生器個數、功率大小等,以便更好地符合不同的處理過程要求。 Compared with the prior art of frequency switching through relays, the present invention can achieve faster switching speed, and can perform radio frequency switching with power in a pulse mode. In addition, any stage can be divided into a pulse cycle according to different substrate processing processes. In each stage, the parameters of various RF generators can be flexibly set, such as the number of output RF generators, the power level, etc. Well suited to different processing requirements.
10:氣體噴淋頭 10: Gas shower head
100,W:基片 100,W: substrate
101:通孔 101: Through hole
20:外部氣源 20: External air source
30:反應腔 30: reaction chamber
40:基座 40: Pedestal
50:處理裝置 50: Processing device
60:電漿約束裝置 60: Plasma Confinement Device
70:射頻電源裝置 70: RF Power Supply Unit
701,702,703,RF1,RF2,RF3:射頻產生器 701, 702, 703, RF1, RF2, RF3: Radio Frequency Generators
80:抽真空裝置 80: Vacuum device
90:控制器 90: Controller
第1圖示出了使用根據本發明的一個實施例的方法的CCP處理裝置的示意圖。 Figure 1 shows a schematic diagram of a CCP processing apparatus using a method according to an embodiment of the present invention.
第2圖示出了現有技術的雙頻可切換射頻電漿控制系統的射頻功率輸出示意圖。 FIG. 2 shows a schematic diagram of a radio frequency power output of a dual-frequency switchable radio frequency plasma control system in the prior art.
第3圖是根據本發明的一個實施例的多階段多頻可切換電漿射頻功率輸出示意圖。 FIG. 3 is a schematic diagram of multi-stage multi-frequency switchable plasma RF power output according to an embodiment of the present invention.
第4A圖及第4B圖是蝕刻過程中通孔側壁的形貌示意圖。 FIG. 4A and FIG. 4B are schematic diagrams of the topography of the sidewall of the through hole during the etching process.
第5圖是根據本發明的另一個實施例的多階段多頻可切換電漿射頻功率輸出的示意圖。 FIG. 5 is a schematic diagram of a multi-stage multi-frequency switchable plasma RF power output according to another embodiment of the present invention.
第6圖為根據本發明的一個實施例的具有多階段脈衝功率輸出的射頻產生器功率輸出示意圖。 FIG. 6 is a schematic diagram of the power output of a radio frequency generator with multi-stage pulse power output according to an embodiment of the present invention.
以下結合附圖,對本發明的實施例進行說明。需強調的是,這裡僅是示例型的闡述,不排除有其它利用本發明的實施方式。 Embodiments of the present invention will be described below with reference to the accompanying drawings. It should be emphasized that this is only an exemplary illustration, which does not exclude other embodiments utilizing the present invention.
以下結合附圖,對本發明的具體實施方式進行說明。 The specific embodiments of the present invention will be described below with reference to the accompanying drawings.
本發明提供了一種多頻率多階段的電漿射頻脈衝輸出的方法,其可應用於電漿處理裝置,諸如電容耦合式電漿(CCP)處理裝置、電感耦合式電漿(ICP)處理裝置等。第1圖示出了使用本發明的方法的CCP處理裝置的示意圖。該處理裝置50包括由反應腔外壁圍成的真空反應腔30,反應腔內部形成反應空間,以進行電漿蝕刻製程處理;真空反應腔內設置一基座40,用於固定待處理的基片W,基座40同時作為真空反應腔的下電極。反應腔內的頂部設置有一個平板形的氣體噴淋頭10,氣體噴淋頭10透過管道與外部氣源20相連通。氣體噴淋頭與基座位置相對應,同時作為真空反應腔的上電極。射頻電源裝置可包括複數個射頻產生器,這些射頻產生器中的一個或複數個可選擇性地施加到上電極或下電極之一。如第1圖中所示,射頻電源裝置包括三個射頻產生器701~703,且都施加到下電極上,其中每個射頻產生器輸出不同頻率的功率。例如,高頻射頻產生器701使得通入反應腔內的反應氣體電離產生電漿;中頻射頻產生器702施加到下電極,使得基片上表面鞘層中產生足夠的直流偏置電壓,加速電漿中的帶電離子快速地向基片轟擊,以進行蝕刻;低頻射頻產生器703輸出低頻功率以配合中頻射頻產生器進行蝕刻。環繞基座40設置一等離子體電漿約束裝置60,用於將電漿限制在電漿區內,一抽真空裝置80用於排出反應腔內的
未反應氣體及反應副產物氣體,以維持反應腔30的真空狀態。控制器90控制射頻電源裝置70以完成蝕刻製程。控制器90還監測處理裝置50的參數並且控制反應氣體的傳遞、維持及熄滅電漿、供應冷卻氣體等。
The present invention provides a multi-frequency and multi-stage plasma radio frequency pulse output method, which can be applied to plasma processing devices, such as capacitively coupled plasma (CCP) processing devices, inductively coupled plasma (ICP) processing devices, etc. . Figure 1 shows a schematic diagram of a CCP processing apparatus using the method of the present invention. The
第2圖示出了現有技術的雙頻可切換射頻電漿控制系統的射頻功率輸出示意圖。圖中示出了四個步驟,在每個步驟中有兩個頻率輸出,每個步驟時長為幾秒至數百秒。射頻產生器RF1持續工作在每個步驟中,但功率有所變化。射頻產生器RF2及RF3在不同的步驟中進行切換,射頻產生器RF2與RF3及RF1的輸出功率及時間的組合可以任意設定。圖中示出的是射頻產生器RF2佔據步驟1及3,射頻產生器RF3佔據步驟2及4。由於現有技術中的射頻產生器RF頻率切換利用繼電器,其只能在小功率的情況下進行切換並且切換需要以秒為量級的較長時間(如第2圖中每個步驟之間有較長時間的功率中斷),所以該電漿控制系統不適合用於脈衝式電漿射頻產生器以及脈衝式電漿射頻的製程。在本發明的應用中,蝕刻製程的脈衝頻率為10Hz-20KHz,即脈衝時長為1/20微秒-0.1秒。在如此短的脈衝時長中,以秒為量級的切換時間顯然不適用於本發明的製程中。
FIG. 2 shows a schematic diagram of a radio frequency power output of a dual-frequency switchable radio frequency plasma control system in the prior art. The figure shows four steps, with two frequency outputs in each step, each step is from a few seconds to hundreds of seconds long. The RF generator RF1 operates continuously in each step, but the power varies. The radio frequency generators RF2 and RF3 are switched in different steps, and the combination of output power and time of the radio frequency generators RF2, RF3 and RF1 can be arbitrarily set. The figure shows that the radio frequency generator RF2 occupies
透過控制器可實現射頻電源裝置內不同射頻產生器的快速的無功率中斷的切換。該控制器可以在外部連接至射頻電源裝置,也可以內置於射頻電源裝置中。或者,每個射頻產生器中都分別內置有控制器。控制器經預先編程設定參數以控制不同射頻產生器在連續脈衝週期內的不同階段輸出射頻功率。該參數包括但不限於:連續脈衝的頻率、階段個數、每個階段的時長、射頻產生器的輸出功率以及在一個階段中的輸出功率的射頻產生器個數。可根據蝕刻製程的要求改變不同參數的組合。 The controller can realize fast switching without power interruption of different RF generators in the RF power supply device. The controller may be externally connected to the RF power supply unit, or may be built into the RF power supply unit. Alternatively, a controller may be built into each RF generator individually. The controller is pre-programmed with parameters to control the different RF generators to output RF power at different stages within a continuous pulse cycle. The parameters include, but are not limited to, the frequency of continuous pulses, the number of stages, the duration of each stage, the output power of the RF generator, and the number of RF generators that output power in one stage. The combination of different parameters can be changed according to the requirements of the etching process.
在一個實施例中,控制器90外接至射頻電源裝置70。透過控制器90控制複數個射頻產生器在無功率中斷的情況下切換頻率能用於基片處理的多種應用中,例如製造三維記憶體的大深寬比的蝕刻步驟中。在現有技術中,源脈衝射頻產生器(通常是60MHz的高頻脈衝射頻產生器)大多採用連續工作模式或脈衝工作模式。在連續工作模式中,源脈衝射頻產生器的輸出功率保持不變。在脈衝工作模式中,源脈衝射頻產生器在一個脈衝週期內交替地輸出高低兩種功率或者交替地開啟及關閉功率輸出。本發明中,一個脈衝週期根據製程需求可分成複數個階段,源脈衝射頻產生器可選擇為在任意階段上輸出或不輸出功率,而不是如現有技術那樣只能在一個脈衝週期的兩個階段中進行功率調節,其更具有靈活性,也節省射頻產生器的能耗。
In one embodiment, the
第3圖示出了根據本發明的一個實施例的多階段多頻可切換電漿射頻功率輸出示意圖,該示意圖所示的脈衝輸出方法特別地用於製造記憶體的高深寬比蝕刻中。一電漿處理配置具有三種頻率的脈衝射頻產生器:高頻(40-100MHz)射頻產生器、中頻(10-20MHz)射頻產生器及低頻(200kHz-4MHz)射頻產生器。高頻射頻功率通常用於在腔體中產生電漿,但在蝕刻時腔體如存在高頻射頻功率會對蝕刻的均勻性產生不利影響。因此,引入中頻射頻功率,其既能保持電漿不熄滅又不會對蝕刻的均勻性產生較大影響。而低頻射頻功率主要作用是在基片上表面產生足夠的偏置電壓,以使得帶電離子轟擊基片進行蝕刻。因此,在一個實施例中,可以如第3圖所示配置各個射頻產生器的功率輸出情況。在每個脈衝的第(1)階段,即產生電漿階段,輸出第一高頻功率及第一中頻功率,以解離處理氣體,產生帶電離子及反應基團。輸出第一中頻功率是用於輔助第一高頻功率以產生電漿及反應基團。在另一個實施例中,也可以
只用第一高頻功率來產生電漿。第(2)階段,即蝕刻階段,輸出第一低頻功率及第二中頻功率,產生高偏置電壓,進行高深寬比蝕刻。在該階段中,關閉第一高頻輸出功率,而用中頻及低頻功率,一方面,能維持電漿,使其不熄滅;另一方面,不輸出高頻功率可以增加蝕刻的均勻性。在該階段關閉高頻功率的輸出還能起到節省功率的作用。第(3)階段,即維持電漿階段,只輸出第二高頻功率,第二高頻功率小於第一高頻功率,以維持電漿及釋放加工工件的電荷積累。在高深寬比的蝕刻過程中,隨著正電粒子不斷轟擊基片100,在通孔101的底部會積累正電荷,這些不均勻分佈的正電荷會使向下入射的正電粒子在長距離飛行中方向發生偏移,進一步地,蝕刻通孔101的蝕刻方向也會發生偏移,如第4A圖所示。因此,在本實施例的維持電漿階段,只輸出小功率的高頻功率而關閉中頻及低頻射頻功率產生器,既能維持電漿,又能釋放通孔底部的電荷積累,從而能准直蝕刻通孔,如第4B圖所示。
Figure 3 shows a schematic diagram of a multi-stage multi-frequency switchable plasma RF power output according to an embodiment of the present invention, and the pulse output method shown in the schematic diagram is particularly used in high aspect ratio etching for manufacturing memory. A plasma processing configuration has three frequency pulsed RF generators: high frequency (40-100MHz) RF generator, intermediate frequency (10-20MHz) RF generator and low frequency (200kHz-4MHz) RF generator. High frequency radio frequency power is usually used to generate plasma in the cavity, but the presence of high frequency radio frequency power in the cavity during etching will adversely affect the uniformity of etching. Therefore, the introduction of intermediate frequency radio frequency power can not only keep the plasma from extinguishing, but also will not have a great impact on the uniformity of etching. The main function of the low-frequency radio frequency power is to generate enough bias voltage on the upper surface of the substrate, so that charged ions bombard the substrate for etching. Thus, in one embodiment, the power output profile of each RF generator may be configured as shown in FIG. 3 . In the (1) stage of each pulse, that is, the stage of generating plasma, the first high-frequency power and the first intermediate-frequency power are output to dissociate the processing gas to generate charged ions and reactive groups. The output of the first intermediate frequency power is used to assist the first high frequency power to generate plasma and reactive groups. In another embodiment, it is also possible to
Only the first high frequency power is used to generate the plasma. The (2) stage, that is, the etching stage, outputs the first low frequency power and the second intermediate frequency power, generates a high bias voltage, and performs high aspect ratio etching. In this stage, the first high frequency output power is turned off, and the intermediate frequency and low frequency power are used. On the one hand, the plasma can be maintained so that it does not go out; on the other hand, the uniformity of etching can be increased by not outputting the high frequency power. Turning off the high-frequency power output at this stage can also save power. The (3) stage, namely the maintenance plasma stage, only outputs the second high frequency power, and the second high frequency power is smaller than the first high frequency power to maintain the plasma and release the charge accumulation of the workpiece. During the high aspect ratio etching process, as the positively charged particles continue to bombard the
在下一個脈衝週期的第(1)階段,再次輸出第一高頻功率。這是因為,在前一階段中,只有較小功率的第二高頻功率輸出,此時電漿濃度較低,只用於維持電漿不熄滅。而在下一個脈衝週期中,必須再次產生足夠濃度的電漿。因此,第一脈衝週期的第(1)階段用於在沒有電漿的腔室中產生電漿,其餘脈衝週期的第(1)階段用於在低濃度的電漿的腔室中產生足夠濃度的電漿。所以,脈衝週期的第(1)階段統稱為產生電漿階段。控制器90透過預先設置的參數控制三個階段的時長、三個射頻產生器的功率輸出,以及射頻產生器之間的切換。透過上述輸出功率的配置可以實現多頻射頻脈衝的切換,以增大蝕刻製程窗口,並且更有效地實現高深寬比蝕刻。
In the (1) stage of the next pulse cycle, the first high frequency power is output again. This is because, in the previous stage, only the second high-frequency power with lower power is output, and the plasma concentration is lower at this time, and it is only used to maintain the plasma from being extinguished. In the next pulse cycle, a plasma of sufficient concentration must be generated again. Therefore, phase (1) of the first pulse cycle is used to generate plasma in the chamber without plasma, and phase (1) of the remaining pulse cycle is used to generate sufficient concentration of plasma in the chamber of low concentration plasma. Therefore, the (1) stage of the pulse cycle is collectively referred to as the plasma generation stage. The
較佳地,高頻射頻產生器及中頻射頻產生器輸出的功率範圍是50W-10kW。低頻射頻產生器輸出的功率範圍是100W-20kW。 Preferably, the output power range of the high frequency radio frequency generator and the intermediate frequency radio frequency generator is 50W-10kW. The output power range of the low frequency RF generator is 100W-20kW.
第5圖是根據本發明的另一個實施例的多階段多頻可切換電漿射頻功率輸出示意圖。在本發明的另一個實施例中,如圖所示,高頻射頻產生器RF1為持續脈衝產生器,中頻射頻產生器RF2及低頻射頻產生器RF3之間進行頻率切換。每個脈衝週期的頻率例如可以是10-20kHz。每個脈衝內具有三個階段。高頻射頻產生器在每個階段都輸出射頻功率,但功率各不相同。在第(1)階段中,即產生電漿階段,射頻產生器RF1及RF2在各自頻率下輸出功率,射頻產生器RF1輸出第一高頻射頻功率,射頻產生器RF2輸出第一中頻射頻功率。在第(2)階段中,即初蝕刻階段,射頻產生器RF1轉為輸出較低功率,並且射頻產生器RF2關閉,射頻產生器RF3開啟工作。在第(3)階段中,即主蝕刻階段,射頻產生器RF1再次轉為在較高功率下工作。同時,射頻產生器RF3關閉,射頻產生器RF2開啟工作。在初蝕刻階段,射頻產生器RF1及RF3分別輸出第二高頻射頻功率及第一低頻射頻功率,由於低頻射頻功率的存在,此時電漿的離子的能量較大,用於初步的蝕刻。在主蝕刻階段,射頻產生器RF1及RF2分別輸出第三高頻射頻功率及第二中頻射頻功率,其中第三高頻射頻功率大於第二高頻射頻功率。在此階段中,使用中高頻的射頻功率,使得電漿的濃度變大但能量相對較低。因此,該實施例主要用於軟蝕刻(soft etching)的製程。控制器90控制上述三個射頻產生器在一個脈衝時間內的功率改變以及射頻產生器RF2及RF3之間的切換。
FIG. 5 is a schematic diagram of a multi-stage multi-frequency switchable plasma RF power output according to another embodiment of the present invention. In another embodiment of the present invention, as shown in the figure, the high frequency radio frequency generator RF1 is a continuous pulse generator, and frequency switching is performed between the intermediate frequency radio frequency generator RF2 and the low frequency radio frequency generator RF3. The frequency of each pulse period may be, for example, 10-20 kHz. There are three phases within each pulse. High-frequency RF generators output RF power at each stage, but the power varies. In stage (1), the plasma generation stage, the radio frequency generators RF1 and RF2 output power at their respective frequencies, the radio frequency generator RF1 outputs the first high frequency radio frequency power, and the radio frequency generator RF2 outputs the first intermediate frequency radio frequency power . In the (2) stage, that is, the initial etching stage, the radio frequency generator RF1 is turned to output lower power, the radio frequency generator RF2 is turned off, and the radio frequency generator RF3 is turned on to work. In stage (3), the main etch stage, the radio frequency generator RF1 is again turned to operate at a higher power. At the same time, the radio frequency generator RF3 is turned off, and the radio frequency generator RF2 is turned on to work. In the initial etching stage, the radio frequency generators RF1 and RF3 respectively output the second high frequency radio frequency power and the first low frequency radio frequency power. Due to the existence of the low frequency radio frequency power, the energy of the plasma ions is larger at this time, which is used for preliminary etching. In the main etching stage, the radio frequency generators RF1 and RF2 respectively output a third high frequency radio frequency power and a second intermediate frequency radio frequency power, wherein the third high frequency radio frequency power is greater than the second high frequency radio frequency power. In this stage, the RF power of the medium and high frequency is used, so that the concentration of the plasma becomes high but the energy is relatively low. Therefore, this embodiment is mainly used for the process of soft etching. The
以上僅作為示例示出了三個射頻產生器的輸出功率及頻率切換時間的組合。其中每個階段的時長、不同射頻產生器的功率大小以及切換的先
後次序可根據實際的蝕刻需要而改變。通常,控制器90控制射頻產生器的功率輸出以具有以下特徵:(1)在一個脈衝中的任一階段最多只有兩個射頻產生器有功率輸出;(2)三個頻率產生器的切換可任意組合;(3)可用於三個及以上階段的脈衝射頻產生器。
The combination of output power and frequency switching time of the three RF generators is shown above as an example only. The duration of each stage, the power of different RF generators, and the priority of switching
The latter order can be changed according to actual etching needs. Typically, the
作為一個實施例,表1列出了三個脈衝射頻產生器構成的系統的功率輸出組合方式,其中“ON”代表有功率輸出,“OFF”代表無功率輸出,每種模式下最多只有兩個射頻產生器進行功率輸出。 As an example, Table 1 lists the power output combinations of the system composed of three pulsed RF generators, where "ON" represents power output, "OFF" represents no power output, and there are at most two in each mode The RF generator performs power output.
作為另一個實施例,表2列出了四個脈衝射頻產生器構成的系統的功率輸出組合方式,其中“ON”代表有功率輸出,“OFF”代表無功率輸出,每種模式下最多只有兩個射頻產生器進行功率輸出。 As another example, Table 2 lists the power output combinations of the system composed of four pulsed RF generators, where "ON" represents power output, "OFF" represents no power output, and there are at most two power outputs in each mode. A radio frequency generator for power output.
第6圖為具有多階段脈衝功率輸出的射頻產生器功率輸出示意圖。圖示為4個階段的脈衝功率輸出,控制器90控制單個射頻產生器在每個脈衝的不同階段輸出不同的功率。其中,每個階段的輸出功率大小及時長可以由控制器預先設定。該脈衝的頻率可以例如為10-20kHz,其也可以透過控制器90來設定。
FIG. 6 is a schematic diagram of the power output of an RF generator with multi-stage pulse power output. 4 stages of pulsed power output are shown, and the
儘管本發明的內容已經透過上述較佳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。在發明所屬技術領域通常知識者閱讀了上述內容後,對於本發明的多種變更及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圍來限定。 Although the content of the present invention has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be construed as limiting the present invention. Various modifications and substitutions to the present invention will become apparent to those of ordinary skill in the art to which the invention pertains after reading the foregoing content. Therefore, the protection scope of the present invention should be defined by the appended claims.
10:氣體噴淋頭 10: Gas shower head
W:基片 W: substrate
20:外部氣源 20: External air source
30:反應腔 30: reaction chamber
40:基座 40: Pedestal
50:處理裝置 50: Processing device
60:電漿約束裝置 60: Plasma Confinement Device
70:射頻電源裝置 70: RF Power Supply Unit
701,702,703:射頻產生器 701, 702, 703: Radio Frequency Generators
80:抽真空裝置 80: Vacuum device
90:控制器 90: Controller
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