M279740 八、新型說明： 【新型所屬之技術領域】 本創作係有關於在汲取效率方面之改良，尤有關於在一 具有複數個泵之真空汲取裝置的功率消耗方面之降低。 【先前技術】 真空處理被經常使用於半導體裝置之製造，以便將薄膜 沉積在基板上。典型地，一處理室藉由使用一真空泵而被 排空至一非常低的壓力，其取決於製程之種類而可低至10_6 mbar，且饋送之氣體被引至該經排空之室，以致使所要的 材料可被沉積在位於該室中的一或多個基板上。當沉積完 成時，該基板隨即從該室處被移除，而另一基板被插入以 便重複進行沉積製程。 將該處理室排空至所要之壓力係必需顯著之真空汲取時 間。因此，為了在更換基板時維持該室内之壓力在該所需 之位準或在該位準附近，通常會使用移轉室及負載閘室。 該負載閘室藉由一第一窗口或通路而被連接至該移轉室， 該第一窗口或通路可被選擇性地打開，以容許諸基板被插 入该移轉室内並自該移轉室處被移除。該負載問室的答f 可為從正好數公升至數千公升之範圍，以供用於一些較大 型的平板顯示工具。該負載閘室亦具有一窗口，其可被選 擇性地打開至大氣以容許諸基板被插入該負載閘室内並自 該負載閘室處被移除。在使用時，該處理室藉由該處理室 真空泵而被維持在所要之真空下。當該第一窗口被關閉 時，該第二窗口被打開至大氣以容許該基板被插入該負載 96584-940714.doc M279740 閘室内。然後，該第二窗口被關閉，且該負載閘室藉由使 用一負載閘真空泵而被排空，直到該負載閘室之壓力大致 上與該移轉室之壓力相同為止。該第一窗口接著被打開以 容許該基板被移轉至該移轉室。然後，該移轉室被排空至 一大致上與該處理室相同之壓力，隨後該基板被移轉至該 處理室。 當真空處理巳被完成時，該經處理之基板被移轉回至該 負載閘室。當該第一窗口被關閉以維持該處理室中之真空 時，該負載閘室中之壓力藉由容許一諸如空氣或氮氣之非 活性氣體流入該負載閘室而被帶至大氣壓力。當該負載閘 室中之壓力處於或接近大氣壓力時，該第二窗口被打開以 容許該經處理之基板被予移除。因此，對於一負載閘室而 言，一從大氣排放空氣至一低度或中度真空之重複循環是 有必要的。 若干負載閘泵在其真空室中通常係無油狀態的，因為任 何存在於該等真空室中之潤滑劑將可能導致在其中執行真 空處理之該清洗環境受到污染。此諸’’乾式π真空泵通常係 使用交錯轉子之多級正向位移泵。該等轉子在各級中可具 有相同類形之構型，或該構型可逐級地改變。該一適合當 作一負載閘真空泵之泵範例係一 BOC Edwards乾式真空泵 niL”系列之產品。 由一真空泵所導致之功率的促成因素包括用以克服寄生 損失的功率、用以壓縮將予汲取之流體的功率、及由於馬 達之無效率所致的功率損失。為了降低壓縮該經汲取之流 96584-940714.doc M279740 體所需之功率， 已知可降低該泵之排放壓力而達成。例如M279740 8. Description of the new model: [Technical field to which the new model belongs] This creation relates to improvements in extraction efficiency, and in particular to reduction in power consumption of a vacuum extraction device with a plurality of pumps. [Prior art] Vacuum processing is often used in the manufacture of semiconductor devices in order to deposit thin films on substrates. Typically, a processing chamber is evacuated to a very low pressure by using a vacuum pump, which can be as low as 10-6 mbar depending on the type of process, and the feed gas is led to the evacuated chamber so that This allows the desired material to be deposited on one or more substrates located in the chamber. When the deposition is complete, the substrate is removed from the chamber, and another substrate is inserted to repeat the deposition process. Evacuating the processing chamber to the desired pressure is a significant vacuum draw time. Therefore, in order to maintain the pressure in the chamber at or near the required level when replacing the substrate, a transfer chamber and a load lock chamber are usually used. The load lock chamber is connected to the transfer chamber by a first window or passage, and the first window or passage can be selectively opened to allow substrates to be inserted into the transfer chamber and from the transfer chamber. Was removed. The answer to this load cell can range from just a few liters to thousands of liters for use with some larger flat panel display tools. The load lock chamber also has a window that can be selectively opened to the atmosphere to allow substrates to be inserted into and removed from the load lock chamber. In use, the processing chamber is maintained at the desired vacuum by the processing chamber vacuum pump. When the first window is closed, the second window is opened to the atmosphere to allow the substrate to be inserted into the load 96584-940714.doc M279740 gate. Then, the second window is closed, and the load lock chamber is evacuated by using a load lock vacuum pump until the pressure of the load lock chamber is substantially the same as that of the transfer chamber. The first window is then opened to allow the substrate to be transferred to the transfer chamber. Then, the transfer chamber is evacuated to a pressure approximately the same as that of the processing chamber, and then the substrate is transferred to the processing chamber. When the vacuum processing chamber is completed, the processed substrate is transferred back to the load lock chamber. When the first window is closed to maintain the vacuum in the processing chamber, the pressure in the load lock chamber is brought to atmospheric pressure by allowing an inert gas such as air or nitrogen to flow into the load lock chamber. When the pressure in the load lock chamber is at or near atmospheric pressure, the second window is opened to allow the processed substrate to be removed. Therefore, for a load lock chamber, a repeated cycle of exhausting air from the atmosphere to a low or moderate vacuum is necessary. Several load gate pumps are usually oil-free in their vacuum chambers, as any lubricant present in these vacuum chambers may cause contamination of the cleaning environment in which vacuum treatment is performed. These '' dry π vacuum pumps are usually multistage forward displacement pumps using staggered rotors. The rotors may have the same type of configuration in each stage, or the configuration may be changed step by step. An example of a pump suitable for use as a load-gate vacuum pump is a product of the BOC Edwards dry vacuum pump niL "series. The drivers of power caused by a vacuum pump include power to overcome parasitic losses, and compression to be drawn. The power of the fluid and the power loss due to the inefficiency of the motor. In order to reduce the power required to compress the pumped stream 96584-940714.doc M279740, it is known to reduce the pump discharge pressure. For example
排放之氣體的附加泵。Additional pump for exhaust gas.
他問題。 【新型内容】 本創作提供一種真空汲取裝置，其包含複數個真空泵， 各真空泵用於汲取來自一各別室處之流體；輸送裝置，其 用於將排自該等泵之流體輸送至一用於汲取該排放流體之 附加泵處；以及轉向裝置，其與該輸送裝置相連通且用於 選擇性地轉向該排放流體以遠離該附加泵。 藉由連接二或多個真空泵至一將排致自該泵之流體輸送 土一沒取該排放流體之附加泵處的共同排放泵，使得在該 流體出口處的流體壓力能從約1000 mbar(大氣壓力）降低至 一自例如10 mbar至100 mbar的壓力範圍内。以1〇或更大之 係數降低該泵入口及該泵出口間之壓力差將可顯著地降低 G % θ亥皇所沒取之流體所需的功率’及因而顯著地降低各 真空栗中之功率消耗。 在真空泵包含多個用於排空複數個負載閘室之負載閘栗 處’來自泵出口處之排放流體的質量流動速率將依據例如 96584-9407U.doc M279740 在多個基板被插入該等室内之後正由一相當高壓力處被排 空之負載閘室的數目而改變。結果，來自該等泵之排放流 體的質量流動速率及因而在進入該附加泵之入口處的壓力 將通常隨時間而顯著地改變。如果該等負載閘泵之產出必 須超出該附加泵之產出，也就是當四或多個負載閘室被同 時自一相當高的壓力下被予排空時，’’過量”之排放流體將 被轉向以遠離該泵，以防止來自該附加泵的上游之流體壓 力超過該附加泵下游的流體壓力，因此而可避免該附加泵 之入口級以及該等負載閘泵之排放級的過載。 因此，一單一且相當低容量及低功率之泵可被用作為從 所有該等真空泵處汲取排放流體之泵。結果，由此可預期 的是，提供及運轉此一附加泵之成本可能多於藉由降低該 等真空泵之功率消耗所節省之每年成本所補償者。 較佳地，該輸送裝置包含複數個第一導管，各導管用於 輸送來自一各別真空泵之排放流體至一第二導管，該第二 導管用於接收來自各第一導管處之排放流體，並將該排放 流體輸送至該附加泵。 較佳地，該轉向裝置包含一閥。該閥可包含一用於接收 排放流體之閥入口、一閥出口、及當該閥入口及該閥出口 間之壓力差超過一預定值，例如約50 mbar時，容許該排放 流體由閥入口流動至該閥出口處之裝置。為求便利，該閥 可為一球閥型式者，其包含一個球，該球被配置以便安裝 抵靠一閥座上，以避免流體從該閥出口流通至該閥入口， 且在使用時，可藉由加壓在該閥入口端處之排放流體而從 96584-940714.doc M279740 該閥座移開，以便容許該排放流體可從該閥入口流通至該 · 閥出口處。較佳地，該附加泵具有一與該閥出口相連通之 出口，以致使得該閥出口及該泵出口處於相同壓力下。 車父佳地’該輸送裝置在該附加泵之上游處包括分離裝 置，其用於將排放自該等泵處之流體分離成為一流向該附 加泵之第一流及一流向該閥之第二流。 在一實施例中，該分離裝置可包含一用於將來自該等泵 之排放流體流分開成二流。在另一實施例中，該分離裝置 亦包含一三通閥，該閥包含一用於接收排放自該等泵處之 _ 流體的閥入口、一用於將所接收到之排放流體輸出朝向該 附加泵之第一閥出口、及一用於將所接收到之遠離該附加 泵之排放流體的第二閥出口。可提供用於選擇性地控制該 . 三通閥，以便可輸出僅從該第一閥出口處所接收之排放流 體，或者輸出來自該第一閥出口及該第二閥出口兩者之排 放流體。例如，一感測器可提供用以感測位於該閥出口處 之藏排放流體的壓力，該控制裝置可被配置以依據該感測 器之輸出而控制該三通閥。如果該閥入口處之壓力超過—春 預定位準，例如超過三個室正從一相當高的壓力下被排 空，則此將使得該第二閥出口被予打開。當該壓力降到低 於孩預足壓力時，倘若該三通閥無法關閉該第二閥出口， 則位於孩第二閥出口下游處之該洩壓閥便可提供一 特性。 或者，或此外，可提供用於監視該真空泵之功率消耗之 裝置，該控制裝置被配置成可依據該監視裝置之輸出而控 96584-940714.doc -10- M279740 制該附加閥。如果該等泵之 淮，此、、~ 力羊4耗增加至高於一預定位 率，此將可使孩第二閥出口被打 Μ # 、、 打開其耶可表示許多室現 對正藉由該等泵而從一相卷* 相田同壓力處所進行之排空，及因 而表不一現時或預期在正被輸 .^^ ^ 排放泵處之排放氣體 的心動速率上芡增加。。在另— 罢-Τ软、曰4二密、、、 J曰代乾例中’該監視裝 置可aii視被設置於該等室及兮筌 、、 至夂巧寺泵間 < 閥的開啟及關閉。 與彡亥輪送裝置相連通之裝冒於彳 木石Γ 〈衮置車乂佳包含一用於藉使用該附He has problems. [New content] This creation provides a vacuum extraction device, which includes a plurality of vacuum pumps, each vacuum pump is used to extract fluid from a separate room; a conveying device, which is used to convey the fluid discharged from these pumps to a An additional pump that draws the discharged fluid; and a steering device that is in communication with the conveying device and is used to selectively turn the discharged fluid away from the additional pump. By connecting two or more vacuum pumps to a common drain pump at an additional pump that will drain fluid from the pump and remove the drain fluid, the fluid pressure at the fluid outlet can be from about 1000 mbar ( Atmospheric pressure) is reduced to a pressure range from, for example, 10 mbar to 100 mbar. Decreasing the pressure difference between the pump inlet and the pump outlet by a factor of 10 or greater will significantly reduce the power required by G% θ, the fluid not taken by the emperor, and thus significantly reduce the Power consumption. Where the vacuum pump contains a plurality of load gates for evacuating a plurality of load gate chambers, the mass flow rate of the discharged fluid from the pump outlet will be based on, for example, 96584-9407U.doc M279740 after multiple substrates are inserted into such chambers. The number of load lock chambers being evacuated at a relatively high pressure is changing. As a result, the mass flow rate of the discharged fluid from these pumps and therefore the pressure at the inlet to the additional pump will usually change significantly over time. If the output of such load gate pumps must exceed the output of the additional pump, that is, when four or more load gate chambers are simultaneously evacuated from a relatively high pressure, the `` excessive '' discharge fluid It will be steered away from the pump to prevent the fluid pressure upstream from the additional pump from exceeding the fluid pressure downstream from the additional pump, thus avoiding overload of the inlet stage of the additional pump and the discharge stage of the load gate pumps. Therefore, a single, relatively low-capacity and low-power pump can be used as a pump that draws exhaust fluid from all such vacuum pumps. As a result, it can be expected that the cost of providing and operating this additional pump may be more than The annual cost saved by reducing the power consumption of these vacuum pumps is compensated. Preferably, the conveying device includes a plurality of first ducts, each duct is used to convey the exhaust fluid from a respective vacuum pump to a second duct The second conduit is used to receive the discharged fluid from each of the first conduits and deliver the discharged fluid to the additional pump. Preferably, the steering device includes a valve. The valve may include a valve inlet for receiving the discharged fluid, a valve outlet, and allowing the discharged fluid to flow from the valve inlet to the valve when the pressure difference between the valve inlet and the valve outlet exceeds a predetermined value, such as about 50 mbar. Device at the valve outlet. For convenience, the valve may be a ball valve type that includes a ball that is configured to fit against a valve seat to prevent fluid from flowing from the valve outlet to the valve inlet And in use, it can be removed from the valve seat by pressurizing the discharge fluid at the inlet end of the valve from 96584-940714.doc M279740 to allow the discharge fluid to flow from the valve inlet to the valve outlet Preferably, the additional pump has an outlet communicating with the valve outlet, so that the valve outlet and the pump outlet are at the same pressure. Chevrolet 'The conveying device includes upstream of the additional pump A separation device for separating the fluid discharged from the pumps into a first flow to the additional pump and a second flow to the valve. In an embodiment, the separation device may include a device for separating From The discharge fluid flow of the pumps is split into two flows. In another embodiment, the separation device also includes a three-way valve that includes a valve inlet for receiving the fluid discharged from the pumps, A first valve outlet for directing the received exhaust fluid toward the additional pump and a second valve outlet for diverting the received drain fluid away from the additional pump may be provided for selectively controlling the Three-way valve so that it can output only the discharge fluid received from the first valve outlet, or the discharge fluid from both the first valve outlet and the second valve outlet. For example, a sensor may provide To sense the pressure of the hidden discharge fluid located at the valve outlet, the control device may be configured to control the three-way valve based on the output of the sensor. If the pressure at the valve inlet exceeds the predetermined level, For example, if more than three chambers are being evacuated from a relatively high pressure, this will cause the second valve outlet to be pre-opened. When the pressure drops below the pre-foot pressure, the pressure relief valve located downstream of the second valve outlet can provide a characteristic if the three-way valve cannot close the second valve outlet. Alternatively, or in addition, a device for monitoring the power consumption of the vacuum pump may be provided, and the control device is configured to control the additional valve based on the output of the monitoring device 96584-940714.doc -10- M279740. If these pumps are used, the power consumption of Liyang will increase above a predetermined rate, which will cause the outlet of the second valve of the child to be hit M #, and open it, which means that many rooms are now using the The pumps are evacuated from the same pressure space of a phase volume * Aita, and thus indicate that the heart rate of the exhaust gas at the pump is being increased or increased. . In another example-the "T-soft", "four-two-secret," and "j-generation" dry example, 'the monitoring device can be installed in these rooms and Xi'an, and to the Qiao Temple Temple's pump opening < valve opening And off. The equipment connected to the 彡 HAI rotation device is installed in 彳 木石 Γ 衮 衮衮 车 衮 佳 includes a
加泵以進行汲取之附加室。提 A 、 捉仏此一至將可在當該等負載 閘至中《或夕個至從一相當高之壓力下被排空時降低該 附加泵之入口處之壓力增加，，其將有助於避免該附 之過載。 該排放流體之最小壓力可藉由該真空泵所連續汲取之洗 務氣體的量而被予㈣。然而，在不使用洗務氣體之場合， 該排放流體則可被儘可能地降低至如該附加泵之最終真空 -般低之壓力，此壓力將視該附加菜的性質決定而可低於二 mbar。因為汲送該排放流體於低於例如5毫巴將會減低該汲 取裝置之整個效率，故該裝置較佳地包含用於控制該附加 泵之功率消耗的控制裝置。當為了避免該附加泵將一真空 拉低至例如低於5 mbar時，該功率消耗於是可因此而被降 低0 【實施方式】 參照圖1，一真空汲取裝置10之一實施例包含複數個真空 泵P1至P8 (雖然可設置任何適合數量的泵，但圖1中顯示設 有八個泵），各泵經由各別之閥V1至V8而被連接至一各別 96584-940714.doc -11 - M279740 之室C 1至C8。在此實施例中，該等室C 1至C8中之每一室係 一半導體處理系統中之一負載閘室，而該等真空泵中之每 一泵係一負載閘泵。適合用作一負載閘泵之泵範例包括 BOC Edwards iL70及 iL600型乾式泵。 該等負載閘泵P1至P8中之每一泵的出口被連接至一各別 之導管20。該等導管20將排放自該等負載閘泵之流體輸送 至一由導管32、34所構成之共同排放管30處。一分支N5具 有一用於接收排放自該等負載閘泵之所有流體的入口 40， 以及一用於將排出之流體輸向一排放泵Pexhaust之入口 50的 第一出口 42，以及一用於將排出之流體輸向一戍壓閥60之 入口 62的第二出口 44。該排放泵亦可為一乾式泵之形式 者，諸如BOC Edwards iL70型泵。該排放泵具有一出口 52， 其經由導管54及56而被連接至該洩壓閥60之出口 64。 在使用時，該等負載閘室C1至C8藉由該等負載閘泵P1至 P8而被維持於一低壓處，通常係於從10_2至10_3 mbar之範圍 内。排放自該等負載閘泵之流體被傳輸至該排放泵，其接 著將該流體排放至大氣。如圖1所示，一諸如氮氣之少量洗 滌氣體可例如以4 slpm被供應至該等負載閘泵中之每一 栗，在此情形下，由於存在此一洗條氣體，故排放自該等 負載閘泵之流體的量以及隨後被輸送至該排放泵之流體的 量將至少32 slpm。在此一流動速率下，該排放泵能降低該 等負載閘泵之出口處流體壓力至小於100 mbar，通常至約 12 mbar或更少。參照圖2，降低一負載閘泵之排放壓力從 1000 mbar(大氣壓力）至約12 mbar將可顯著地降低該泵的 96584-940714.doc -12- M279740 力率消耗。例如，一個單一 B0C Edwards匕6〇(^型泵在的 Hz下以一約為5 mbari排放壓力操作所能節省的平均功率 預估約為0.6 kW，此將可提供每年約$3〇〇之成本節約。對 於一個如圖1所示之包括五個江7〇型泵及三個化6〇〇型泵之 八泵系統而言，每年節省的成本預計將超過$1〇〇()。 在使用時，該等負載閘室（:丨至以中之每一室將藉由例如 使用一諸如空氣或氮氣之非活性氣體源而被週期性地加壓 回升至大氣壓力。考慮此一例如負載閘室C1之加壓，首先 閥VI被關閉以隔離該負載閘泵ρι與該室C1。氣體接著被供 應至IC1以便將該室帶回至大氣壓力，以使一處理基板可 從？系罜處被移除且一更新之基板可被插入以供後續之處 理。閥VI接著被打開以使得該室⑴可藉由該負載閘泵？1而 被排空。 當該室正在被排空時，將會有一在排自該泵？1之流體的 質量流動率上之增加，其將增加在該排放泵pexhaust之入口 50處之該排放流體的壓力。倘若在該排放泵之入口 5〇處的 壓力不超過在該排放泵之出口 52處的壓力，則該排放泵將 此有效率地;及送違排放流體。然而，取決於被連結至該等 負載閘室之各處理室（未示於圖）中所進行之處理過程長 度，將可能在同時排空該等負載閘室中之一個以上的室。 藉由提供一與該排放泵之入口 5〇連通之洩壓閥60，將可避 免使來自該等負載閘泵P1至P8之流體的流動速率大到使該 排放泵產生過載之情況。例如，如果在該洩壓閥6〇之該入 口 62及出口 64間之壓力差變得大於例如5〇 mbar，該經加壓 96584-940714.doc -13- M279740 之排放流體將導致該閥6〇之球66由閥座68處被移開，此致 使排放流體繞過該排放泵50並被排放至大氣中。一旦該壓 力差已經降回到低於50 mbar，該閥60則會關閉，且所有的 違排放流體將再次地經由該排放泵而被排放。 该排放 體之最小壓力係藉由真空泵所連續汲取之洗滌 氣體量而被予控制。然而，在不使用洗滌氣體之場合，該 排放流體則可被儘可能地降低至如該排放泵之最終真空一 般低之壓力，此壓力可低於1 mbar。因為汲送該排放流體 於低於例如5 mbar將會降低該汲取系統之整體效率，故一 控制系統可被設置以控制該排放泵之功率消耗。當必需避 免違排放泵將真芝拉至例如低於5 mbar時，該功率消耗則 可被予減低。 如圖1所示，一附加室70可被提供於該等負載閘泵卩丨至⑽ 之下游處，以供藉由使用該排放泵而進行汲取。當該等負 載閘室C1至C8中之一或多個室被排空時，提供此一室7〇將 可降低該排放泵之入口處之壓力增加，並可利於防止該排 放果之入口級及该等負載閘泵之排出級的過載。 所要瞭解的是，前述者代表本創作之一實施例，但其他 型式之實施例無疑地也能由熟習此項技藝者所思及，而不 偏離本創作在其請求項所定義的範圍。 例如，可取代該洩壓閥60，或是除了該洩壓閥6〇之外， 一二通閥也可被裝設在分支^^5處。此閥可經控制以如所需 地導引排放流體朝向及/或遠離該排放泵，以便防止該排放 泵之過載。例如，可提供—感測器以供感測位於該入口 4〇 96584-940714.doc -14· M279740 處之排放流體的壓力。如果該入口 40處的壓力超過一預定 位準，例如，如果超過三個負載閘室被同時排空，則該閥 將可依據感測器的輸出而被控制以以導引流體經過出口 44，亦即遠離該排放泵。或者，或是除此之外，該等負載 閘泵之功率消耗可受到監視，且如果該等泵之功率消耗增 加到高於一預定位準，該三通閥則可經控制以打開該第二 出口 44，其亦可表示許多室現對正藉由該等泵而從一相當 高壓力處所進行之排空，及因而表示一現時或預期在正被 輸送至該排放泵處之排放氣體的流動速率上之增加。在另 一可替代範例中，該三通閥可藉由監視該等閥VI至V8之狀 態而被予控制。當在該入口 40處之流體壓力降到低於該預 定位準時，假若該三通閥不能關閉該第二出口 44，則一位 於該出口 44下游處之洩壓閥60可提供一安全特性。 總之，一真空汲取裝置包含複數個真空泵，其每一個均 用於由一個別之負載閘室處汲取流體。為降低在該泵出口 處之流體壓力且因而減低該等泵之功率消耗，排放自該等 泵處之流體被輸送至一附加泵，該附加泵將汲送所有之排 放流體。為避免該附加泵在當許多室被同時排空時過載， 一洩壓閥選擇性地將一些排放流體轉向遠離該附加泵。 【圖式簡單說明】 本創作的較佳特性現在將僅利用範例並參考附圖加以說 明，其中： 圖1顯不 '一真空沒取系統；及 圖2顯示隨著一 BOC Edwards iL600型泵之排放壓力而變 96584-940714.doc -15- M279740 化之功率消耗。 【主要元件符號說明】 10 真空汲取裝置 20 、 32 、 34 、 54 、 56 導管 30 共用排放管 40、50、 62 入口 42 第一出口 44 第二出口 52、64 出π 60 洩壓閥 66 球 68 閥座 70 附加室 C1-C8 室 N5 分支 P1-P8 真空泵 P exhaust 排放泵 V1-V8 閥 96584-940714.doc -16-Additional chamber for pumping for extraction. The mention of A, will be able to reduce the increase in pressure at the inlet of the additional pump when the load gates are emptied, or emptied from a relatively high pressure, which will help Avoid this accompanying overload. The minimum pressure of the exhaust fluid can be predicated by the amount of washing gas continuously drawn by the vacuum pump. However, in the case where no washing gas is used, the exhaust fluid can be reduced to a pressure as low as the final vacuum of the additional pump. This pressure will be lower than two depending on the nature of the additional dish. mbar. Since pumping the discharge fluid below e.g. 5 mbar will reduce the overall efficiency of the pumping device, the device preferably includes control means for controlling the power consumption of the additional pump. In order to prevent the additional pump from pulling a vacuum down to, for example, less than 5 mbar, the power consumption can be reduced accordingly. [Embodiment] Referring to FIG. 1, an embodiment of a vacuum extraction device 10 includes a plurality of vacuum pumps P1 to P8 (although eight pumps are shown in Figure 1 although any suitable number of pumps can be provided), each pump is connected to a respective one via a respective valve V1 to V8 96584-940714.doc -11- Rooms C 1 to C8 of M279740. In this embodiment, each of the chambers C1 to C8 is a load gate chamber in a semiconductor processing system, and each of the vacuum pumps is a load gate pump. Examples of pumps suitable for use as a load gate pump include BOC Edwards iL70 and iL600 dry pumps. The outlet of each of the load gate pumps P1 to P8 is connected to a separate duct 20. The conduits 20 carry fluid discharged from the load gate pumps to a common discharge pipe 30 composed of conduits 32,34. A branch N5 has an inlet 40 for receiving all the fluid discharged from the load gate pumps, and a first outlet 42 for transferring the discharged fluid to the inlet 50 of a discharge pump Pexhaust, and a first The discharged fluid is delivered to a second outlet 44 of an inlet 62 of a pressure valve 60. The discharge pump can also be in the form of a dry pump, such as a BOC Edwards iL70 pump. The discharge pump has an outlet 52 which is connected to the outlet 64 of the pressure relief valve 60 via conduits 54 and 56. In use, the load lock chambers C1 to C8 are maintained at a low pressure by the load lock pumps P1 to P8, usually in the range from 10_2 to 10_3 mbar. The fluid discharged from the load gate pumps is transferred to the discharge pump, which then discharges the fluid to the atmosphere. As shown in FIG. 1, a small amount of scrubbing gas such as nitrogen can be supplied to each of the load gate pumps at, for example, 4 slpm. In this case, since the stripe scrubbing gas is present, it is discharged from the The amount of fluid that loads the gate pump and the amount of fluid that is subsequently delivered to the discharge pump will be at least 32 slpm. At this flow rate, the discharge pump can reduce the fluid pressure at the outlet of the load gate pump to less than 100 mbar, usually to about 12 mbar or less. Referring to Figure 2, reducing the discharge pressure of a load gate pump from 1000 mbar (atmospheric pressure) to about 12 mbar will significantly reduce the pump's 96584-940714.doc -12- M279740 power consumption. For example, the average power saved by a single BOC Edwards dagger pump at 60 Hz at a discharge pressure of about 5 mbari is estimated to be about 0.6 kW, which will provide a cost of about $ 300 per year Savings. For an eight-pump system including five Jiang 70-type pumps and three 600-type pumps as shown in Figure 1, the annual cost savings are expected to exceed $ 100 (). When used Each of these load lock chambers (: to each of them will be periodically pressurized back to atmospheric pressure by, for example, using an inactive gas source such as air or nitrogen. Consider this, for example, a load lock chamber The pressure of C1 is first closed by valve VI to isolate the load gate pump p1 from the chamber C1. The gas is then supplied to IC1 to bring the chamber back to atmospheric pressure so that a processing substrate can be removed from the system. The removed and a newer substrate can be inserted for subsequent processing. The valve VI is then opened so that the chamber can be evacuated by the load gate pump? 1. When the chamber is being evacuated, it will be There will be an increase in the mass flow rate of the fluid discharged from the pump? Increase the pressure of the discharge fluid at the inlet 50 of the discharge pump pexhaust. If the pressure at the inlet 50 of the discharge pump does not exceed the pressure at the outlet 52 of the discharge pump, the discharge pump will be efficient And discharge fluids. However, depending on the length of the processing performed in each processing chamber (not shown) connected to the load lock chambers, it may be possible to empty the load lock chambers at the same time. By providing a pressure relief valve 60 in communication with the inlet 50 of the discharge pump, it will be possible to avoid making the flow rate of the fluid from the load gate pumps P1 to P8 so large that the discharge pump generates Overload condition. For example, if the pressure difference between the inlet 62 and outlet 64 of the pressure relief valve 60 becomes greater than, for example, 50 mbar, the pressurized discharge fluid of 96584-940714.doc -13- M279740 will Causes the ball 66 of the valve 60 to be removed from the seat 68, which causes the discharge fluid to bypass the discharge pump 50 and be discharged to the atmosphere. Once the pressure difference has dropped back below 50 mbar, the valve 60 It will shut down and all illicit fluids will It is discharged through the discharge pump. The minimum pressure of the discharge body is controlled by the amount of scrubbing gas continuously drawn by the vacuum pump. However, when the scrubbing gas is not used, the exhaust fluid can be as much as possible Ground to a pressure that is generally as low as the final vacuum of the discharge pump, this pressure may be less than 1 mbar. Since pumping the discharge fluid below, for example, 5 mbar, will reduce the overall efficiency of the extraction system, a control system may It is set to control the power consumption of the discharge pump. When it is necessary to avoid pulling the real shiba to, for example, less than 5 mbar against the discharge pump, the power consumption can be reduced. As shown in FIG. 1, an additional chamber 70 can be Provided downstream of the load gate pumps 卩 丨 to ⑽ for extraction by using the discharge pump. When one or more of the load lock chambers C1 to C8 are evacuated, providing this one chamber 70 will reduce the increase in pressure at the inlet of the discharge pump, and may help prevent the inlet level and The discharge stage of these load gate pumps is overloaded. It is to be understood that the foregoing represents one embodiment of the present creation, but other types of embodiments can undoubtedly also be considered by those skilled in the art without departing from the scope of the creation as defined in its claims. For example, instead of the pressure relief valve 60, or in addition to the pressure relief valve 60, a two-way valve may be installed at the branch ^^ 5. This valve can be controlled to direct the discharge fluid towards and / or away from the discharge pump as needed in order to prevent overloading of the discharge pump. For example, a sensor may be provided to sense the pressure of the discharged fluid at the inlet 40 96584-940714.doc -14 · M279740. If the pressure at the inlet 40 exceeds a predetermined level, for example, if more than three load lock chambers are evacuated simultaneously, the valve will be controlled based on the output of the sensor to direct fluid through the outlet 44, That is, stay away from the drain pump. Alternatively, or in addition, the power consumption of the load gate pumps can be monitored, and if the power consumption of the pumps increases above a predetermined level, the three-way valve can be controlled to open the first The second outlet 44, which may also indicate that many chambers are currently evacuating from a fairly high pressure location by such pumps, and thus represents a current or expected discharge of gas being delivered to the discharge pump. Increase in flow rate. In another alternative example, the three-way valve can be controlled by monitoring the status of the valves VI to V8. When the pressure of the fluid at the inlet 40 drops below the pre-positioning level, if the three-way valve cannot close the second outlet 44, a pressure relief valve 60 located downstream of the outlet 44 may provide a safety feature. In summary, a vacuum extraction device includes a plurality of vacuum pumps, each of which is used to draw fluid from a different load lock chamber. To reduce the pressure of the fluid at the pump outlet and thus the power consumption of the pumps, the fluid discharged from the pumps is delivered to an additional pump, which will pump all the discharged fluid. To avoid overloading the additional pump when many chambers are evacuated simultaneously, a pressure relief valve selectively diverts some of the exhaust fluid away from the additional pump. [Schematic description] The best features of this creation will now be described using only examples and with reference to the drawings, in which: Figure 1 shows a 'vacuum extraction system'; and Figure 2 shows the characteristics of a BOC Edwards iL600 pump. The discharge pressure varies with the power consumption of 96584-940714.doc -15- M279740. [Description of symbols of main components] 10 Vacuum extraction devices 20, 32, 34, 54, 56 and 30 Ducts 30 Common discharge pipes 40, 50, 62 Inlet 42 First outlet 44 Second outlet 52, 64 Out π 60 Pressure relief valve 66 Ball 68 Valve seat 70 Additional room C1-C8 Room N5 branch P1-P8 Vacuum pump P exhaust V1-V8 Valve 96584-940714.doc -16-