TW200406818A - Control of a gaseous environment in a wafer loading chamber - Google Patents

Abstract

A gaseous flow control method and system. The flow control system monitors and controls gaseous levels and gas flow into and out of an enclosed space by using a proportional/integral/derivative (PID) controller to manipulate gas flow into and out of the chamber. The proportional term of the controller is applied to gas density, while the integral term is applied to either chamber pressure or gas density. Gas density is adjusted only if chamber pressure is maintained within acceptable levels.

Description

200406818 (1) 发明. Description of the invention [Technical field to which the invention belongs] Refer to this application for a temporary assignment of the United States Patent entitled "Thermal Processing System" filed on July 15, 2002, filed on July 15, 2002 No. 60 / 396,536 and US Patent Provisional Application No. 60 / 428,526 entitled "Thermal Processing System and Method for Using the Same" filed on November 22, 2002 Priority, both of which are incorporated herein by reference in their entirety. The present invention relates to semiconductor manufacturing equipment, and more specifically, to a method and apparatus for controlling a gas environment in a wafer loading chamber. [Prior Art] Furnaces are commonly used in a wide variety of industries, including in the manufacture of integrated circuits or semiconductor devices from semiconductor substrates or wafers. Thermal processing of semiconductor wafers includes, for example, heat treatment, annealing, diffusion or driving of dopant materials, deposition or growth of material layers (including chemical vapor deposition), and etching or removal of materials from substrates. These processes often require wafers to be heated to temperatures between 250 and 1200 degrees Celsius before and during the process. In addition, these processes typically require that the wafer be maintained at a uniform temperature throughout the entire process', even if the temperature of the process gas or its introduction flow rate into the processing chamber inside the furnace varies. When manufacturing semiconductor wafers, the presence of -4- (2) 200406818 of oxygen during a decisive manufacturing step may render the wafer useless. Specifically, when a wafer is thermally processed in a furnace, free oxygen or water vapor on or near the wafer surface may bond with silicon in the wafer to form an oxide, such as silicon dioxide. The oxide is a non-conductive film. In the event that this reaction occurs on the part where the wafer must be conductive, the functionality of the wafer will be completely destroyed. As a result, even trace amounts (in the order of ten parts per million) of oxygen can disrupt semiconductor processes. Oxygen in unwanted manufacturing areas can cause production delays and excessive costs. In addition, oxygen must be restricted or removed in areas other than the furnace. In staging or processing areas such as wafer ship processing units (BHU), the oxygen concentration must be minimized to prevent gas from moving into the furnace with the wafer. When a wafer carrier (or "boat") is preheated before entering the furnace, oxidation may begin even before the wafer is moved into the processing chamber. The movement of a boat or wafer carrier into the furnace is known as a "boat push". The conventional technology system minimizes the oxygen in the φ section transportation area by introducing a large amount of nitrogen into the sealed container. Nitrogen is typically introduced via a manually set mass flow controller that maintains a steady flow of nitrogen into the chamber. While the pressurized nitrogen is pumped into the containment chamber, the ambient gas inside the containment chamber is evacuated through a purge or bypass valve. When nitrogen sufficiently dilutes the oxygen inside the volume (as measured by an oxygen sensor), the vent valve is closed. However, oxygen may sometimes migrate into the chamber through cracks or other flow paths. This may cause the oxygen level to rise above the maximum limit. In this case -5 · (3) (3) 200406818 'The bypass valve is opened again until the oxygen concentration drops. As such, the bypass valve may cycle indefinitely in an attempt to maintain the correct oxygen density. In addition, because the mass flow controller is manually set, it is fixedly introduced into the BHU. This causes two problems. First, nitrogen is quite expensive. Fixed airflow increases manufacturing costs. Second, because nitrogen is pressurized, the chamber pressure may slowly increase when the bleed valve is closed. In addition, although this system can control the oxygen density, there is only a little or no control over the pressure in the chamber. Overpressurizing the BHU may cause panel distortion ' and this accelerates the migration of oxygen. In other words, the high pressure results in a larger oxygen concentration and requires further valve cycling. Generally speaking, conventional technology solutions have always ignored the pressure control in this case because only a single control variable (nitrogen flow) exists in the system. Most traditional systems cannot use a single variable to control the two outputs, namely pressure and oxygen density. Therefore, pressure control is ignored to minimize the chance of oxidizing the crystal circle. Therefore, there is a need for equipment and methods that overcome the above problems. [Summary of the Invention] Generally speaking, an embodiment of the present invention takes the form of a gas flow control system. This flow control system monitors and controls the gas level and gas flow into and out of an enclosed space such as a ship processing unit (BHU) in a semiconductor manufacturing environment. In one embodiment, the control system minimizes the oxygen density in the ship's processing unit, but other embodiments can monitor and minimize the concentration of other gases. -6-(4) (4) 200406818 The first sensor monitors the first gas density in the volume, and the second sensor monitors the pressure in the volume. The sensors can be discrete or integrated. Each sensor transmits its monitoring data to the controller. The controller can manipulate the flow controller to adjust the oxygen density or chamber pressure. Generally speaking, the flow controller takes the form of a mass flow controller, which adjusts the nitrogen flow into the chamber. By turning on the flow controller, more nitrogen enters the ship's processing unit, thereby minimizing the oxygen concentration inside the BHU. However, because nitrogen is pressurized, this also increases the internal pressure of B HU. In one embodiment, the mass flow controller can assume various positions between fully open and fully closed. Similarly, the controller can open or close a bleed valve. The bleed valve controls the evacuation of gas from inside the BHU. When the bleed valve is open, a low-pressure vent vents gas from inside the BHU. When the bleed valve is closed, there is no escape path for the gas. Therefore, opening the bleed valve reduces the pressure inside the BHU, while keeping the bleed valve closed increases the pressure. In addition, because the oxygen level inside the ship's processing unit remains fairly static (except that some oxygen moves in through cracks or gaps in the BHU wall), flushing the gas mixture inside the BHU through the vent valve can quickly reduce the oxygen density in the BHU . This is especially true when the evacuated gas is replaced by nitrogen flowing through the mass flow controller. The invention also contemplates a method for adjusting the operating parameters of the chamber. Generally speaking, this method includes the steps of monitoring the density of the first gas; monitoring the pressure in the chamber; calculating a proportional basis 値 (proportional c ο ntributi ο η) based on the first gas density; determining whether the pressure in the chamber is within the normal pressure range ; In the case that the pressure of the chamber is not within the normal pressure range, calculate an integral contribution based on the first gas density; and adjust based on the ratio of -7- (5) (5) 200406818. Operating parameters. The operating parameters may include the chamber pressure and the first gas density. More specifically, this method can be implemented by a proportional / integral / derivative (PID) controller ', and the PID controller is implemented by software. Other embodiments may use different types of controllers (such as fuzzy logic), or may use hardware implementations. The PID controller regulates the amount of nitrogen flowing into the chamber, and can operate to adjust the chamber pressure or oxygen density. In general, the proportional term of the g 'controller is applied to the oxygen density, and the integral term of the controller is applied to the oxygen density or the chamber pressure. Typically, the integral term is applied to the oxygen density only if the pressure is within acceptable levels. The proportional and integral terms are used to calculate the ratio and integral basis, respectively. The proportional and integral constants can then be used to adjust the nitrogen flow into the volume. If the BHU pressure exceeds a maximum pressure, the oxygen density is ignored to facilitate the application of the integral direction to reduce the pressure. [Embodiment] 1. General overview An embodiment 100 of the present invention generally takes the form of a gas flow control system as shown in FIG. Embodiment 100 monitors and controls the gas level and the gas flow into and out of the container 120 or another enclosed space. Embodiment 100 can monitor the level of the same type of gas and control the flow of the same type of gas, or can monitor the level of the first gas and control the flow of the second gas. This embodiment monitors the oxygen (0 2) level and controls the nitrogen (N 2) gas flow level. (6) (6) 200406818 The operations of this embodiment 100, including monitoring and flow control functions, are generally performed by the controller η 0. The controller 110 is operatively connected to one or more sensors 130, which monitor the pressure and gas level in the chamber 120. Typically, the sensor 130 is electrically connected to the controller 110. Other embodiments may use different connections, such as pressure or other mechanical connections. The gas and pressure data are relayed from the sensor 130 to the controller 110. The controller 1 10 is also operatively connected to the flow controller 1 65. The controller 110 can open, close, or throttle the flow controller 165, thereby changing the flow rate of the gas flowing into the chamber 120 through the inlet port 140. The flow controller 165 is placed in a gas pipe or line 160 connecting the gas source 150 to the chamber 120. In addition, the controller 110 may be operatively connected to a bleed or outlet valve 170 (herein referred to as a "bleed valve"). Typically, the controller is electrically connected to the bleed valve, so that the controller 110 can transmit electrical control signals to the bleed valve 170. The bleed valve 170 is placed in-line along the pipe 190 leading from the outlet 180 of the container 120 to the vent 195 or other low pressure area. When the bleed valve 170 is opened, the gas escapes from the chamber 120, passes through the pipe 190, and finally reaches the vent 195. As with the flow controller 1 65, the controller 1 10 can open or close the purge valve 170 as needed to ensure the correct gas level inside the chamber 120. In this embodiment, the valve has only two states. In other embodiments, an adjustable valve or a throttle may be used as the purge valve. In this embodiment 1000, the controller 1 10 takes the form of a proportional / integral / derivative (PID) software controller. The operation of a PID controller is known to those skilled in the art. The software controller 1 I 0 of this embodiment assigns the proportional term of the PID algorithm to the gas flow rate (7) 200406818 via the flow controller 1 65. Unlike the standard PID controller, the software controller 1 ι includes two integral terms instead of only one integral term. The first integral term adjusts the pressure (ie, "pressure variable") of the chamber 120, and the second integral term is assigned to the monitored gas level of the chamber. The i software controller 110 neither associates the variable with the differential term, nor calculates the differential term. In another embodiment, a variable may be assigned to a differential term, such as a pressure change rate in the chamber 120, a gas level in the chamber, and the like. In other embodiments, the proportional (P) and / or differential (D) terms may be assigned to the pressure variable. Although this embodiment 100 includes a software controller 110, other embodiments may use various PID controls. For example, PID controllers can be implemented as hardware solutions, such as programmable logic controllers (PLC), custom control boards, and so on. In addition, other embodiments may use different control designs other than PID logic, such as pure proportional (or error) control or fuzzy logic implementations. Returning to the discussion of this embodiment 100, the software implementing the controller 110 is typically residing on a computer located at a monitoring station or in a control room. The computer may be of any type known to those skilled in the art, including a mini computer, a microcomputer, a personal or desktop computer, a NUIX station, a SUN station, a web server, etc. Still referring to FIG. 1, in this embodiment 1 In 〇〇, the sensor 130 is a combined oxygen level and pressure sensor. Of course, other embodiments may use two discrete sensors, one of which detects the gas level, and the other of which detects the pressure of the chamber 120. Generally speaking, the oxygen level is detected and expressed in parts per million (pprn), and the pressure is detected and expressed in Torr. -10- (8) (8) 200406818

Torr is a pressure unit equal to 1/7 60 of atmospheric pressure, or approximately a pressure applied by one millimeter of mercury. As described above, the sensor 1 30 is electrically connected to the controller 1 1 0. The flow controller 165 of this embodiment 100 is typically a mass flow controller, but other embodiments may use different types of flow controllers, such as a pressure flow controller, a volume flow controller, or a flow rate controller. The mass flow controller 165 receives commands from the PID controller 110 and adjusts the mass flow of the gas flowing into the chamber 120 accordingly. In this embodiment 100, the flow controller 165 may be fully opened, fully closed, or throttled between the two states. Unlike the bleed valve 1 70 discussed above, the flow controller 1 65 can variably adjust the gas flow. Other embodiments may use one or more two-state (ie, on and off) mass flow controllers. In this way, the embodiment 100 monitors two variables, that is, the oxygen level and pressure in the chamber 120. Similarly, the embodiment 100 can change the two variables only through a single input (that is, the gas flow rate through the mass flow controller 165 to the chamber 120). It should be noted that the term "container" as used in this case refers inclusively to a generally sealed area or enclosure rather than a specific reference to a room. By changing the gas flow rate through the mass flow controller 165, the embodiment 100 can change the pressure and gas density of the chamber 120 measured by the sensor 130. In this embodiment 1), nitrogen is fed through the mass flow controller 165. Generally, the more nitrogen is introduced into the chamber 120, the lower the oxygen density. When the operation of Example 100 was started at the beginning, the chamber 120 contained a relatively high oxygen level. This is measured by the oxygen sensor 130, which in turn replaces the data with the controller Π0. In response to this, the PID controller 1 10 opens the mass flow 200406818 〇) the controller 16 5 and introduces nitrogen into the system. Feeding nitrogen into the container chamber 120 forcibly pressurizes the container chamber, so that the gas already in the container chamber is evacuated via the bleed valve 170. Since nitrogen is continuously fed into the chamber 120 while the gas mixture is evacuated, the nitrogen concentration inside the chamber increases with time and the oxygen concentration decreases. The nitrogen flow rate is maintained by applying the calculated proportional term of the PID software controller 1 1 0 to the nitrogen flow rate. Once the sensor 130 detects that the oxygen concentration has reached a nominal level, the controller 110 closes the air release valve 170. Once the interior of the chamber 120 has reached the correct oxygen level, the integral term of the PID software controller 110 will maintain the nitrogen flow through the mass flow controller 165 as needed to stabilize the gas mixture inside the chamber. This depends on the type of mass flow controller 165 used. This can be achieved in one of two ways. First, the software controller 1 10 can "flutter" the mass flow controller 1 6 5 to swing it between the fully open position and the fully closed position. Generally, this is only used under the immutable MFC (mass flow controller). Alternatively, the PID controller 1 10 can throttle the mass flow controller 1 6 5 as needed to ensure a fixed flow. φ At this time, ideally, the pressure of the chamber 120 should be about 2 to 4 Torr above the atmospheric pressure. By slightly forcibly pressurizing the chamber 120, oxygen and other gases can be removed from the atmosphere and moved into the interior of the chamber. However, if the container 120 is excessively pressurized too much, the walls of the container may begin to distort and bend. When the walls of the chamber are distorted, stress is placed on the seals between the walls and / or around the inflow and outflow areas of the chamber. This stress causes the seal to degrade faster, and may eventually lead to the formation of unwanted air flow paths into and out of the container 120. -12- (10) (10) 200406818 To avoid excessive pressure, the sensor 130 continuously monitors the pressure of the chamber 120. If the sensor 130 detects that the chamber 120 is over-pressurized, it will pass this data to the P1D controller 110 instead. The controller 110 may in turn reduce the pressure of the chamber 120 by reducing the gas flow through the mass flow controller 1 65 and secondly by opening the bleed valve 170. Although the oxygen content of the chamber is monitored during decompression, it is ignored until the pressure of the chamber 120 returns to an acceptable state. That is, even if the decompression process causes the oxygen concentration to exceed the acceptable threshold determined by the PID controller 110, the nitrogen flow through the mass flow controller 1 65 is not increased until the correct pressure is reached. Example 100 effectively treats an over-pressurized state as a priority over a peroxygen state. Other embodiments can reverse this classification. 2. Operating Environment FIG. 2 shows an exemplary operating environment for Embodiment 200 of the present invention. Specifically, the operating environment is a ship processing unit (BHU) container 220 in a semiconductor manufacturing environment. The ship processing unit 220 receives and stores semiconductor wafers before the wafers are processed in the semiconductor furnace 2005. The term "wafer" is used broadly herein to refer to any substrate containing multiple integrated circuits, one or more flat panel displays, and the like. Generally speaking, the front-opening unified pod (FOUP) 201 or wafer cassette is loaded into the BHU220. The wafer is removed from the FOUP 201 by the robotic arm 202 and inserted into the wafer carrier 203. The carrier 203 is lifted through the BHU 220 and into the furnace 205 by an elevator 204 positioned below the carrier. Then, the wafer placed in the furnace 205 by this boat push is processed according to a method known to those skilled in the art (11) (11) 200406818. For example, vapor deposition is used to form a film on the wafer surface without causing a chemical reaction with the underlying wafer layer. Prior to loading the carrier 203 into the furnace 205, the carrier 203 and associated wafers can be preheated to speed up the process. In the event that oxygen remains on the wafer surface during deposition and / or preheating in the furnace 2005, a dielectric film may be formed on the wafer. This destroys some or all of the functionality of the wafer. Oxygen may be attached to the wafer under the wafer storage in the BHU container 220. Therefore, before processing, the oxygen content of BHU220 should be minimized. Embodiment 200 operates in the same manner as previously described to reduce the oxygen (or surrounding atmosphere) concentration in BHU220. The sensor 230 monitors both the pressure of the BHU container 220 and the oxygen concentration. This data is continued to the software PID controller 210, which in turn adjusts the nitrogen flow through the mass flow controller 265 to BHU220. The PID controller 210 may also open or close the bleed valve 270 to evacuate oxygen from the containment chamber or avoid over-pressurization. In addition, the PID controller 2 10 is connected to a control system (not shown) of the elevator 204. The lifter 204 does not push the wafer carrier 203 into the furnace 205 until the oxygen level inside the BHU chamber 220 falls below the maximum threshold. This threshold can be adjusted by changing the set point in the PID software controller 210. 3. Operating parameters In the embodiment 200 discussed in relation to FIG. 2, the operation of the controller 210 is controlled by one or more chirps that can be set by the user. In the embodiment of FIG. 2, the user-settable includes (1) the desired oxygen level in the BHU220 (12) (12) 200406818 '(2) the warning oxygen level in the BHU, (3) BHU The maximum allowable oxygen level inside the chamber 220, (4) the minimum pressure inside the BHU, (5) the maximum allowable pressure inside the BHU, and (6) the safe pressure inside the BHU. Each of these variables is described below. Typically, these variables are implemented as software, but other embodiments may use a hardware implementation for each variable. The "desired oxygen level" variable indicates the oxygen level in the BHU container 220 that the controller 2 10 ideally maintains by adjusting the positions of the MFC265 and the air release valve 270. In this embodiment 200, this variable is set to ten parts per million (10 p p m). The "warning oxygen level" variable is set to an oxygen concentration higher than the desired oxygen level while still acceptable for the BHU container 220. In this embodiment 200, this variable is set to twenty ppm. The "maximum oxygen level" variable indicates the maximum allowable oxygen concentration in the BHU220 during the push of the boat. In this embodiment 200, this volume is nominally set at 30 parts per million (30 ppm). The next user-settable variable in this example 200 is the "minimum chamber pressure" variable. The 値 of this variable indicates the bottom line of the standard or normal pressure range maintained by the controller 2 10 inside the BHU chamber 220. Regarding this embodiment, the minimum pressure variable is nominally set to 2 Torr above atmospheric pressure. Another user-settable variable is the "maximum chamber pressure" variable, where 値 represents the acceptable pressure inside the BHU chamber 220. The upper limit of the standard or normal range. In this embodiment 2000, this variable is set to be 4Torr or more than atmospheric pressure (13) (13) 200406818. The last user-selectable variable in this embodiment is the "safety chamber pressure" variable. In general, this variable indicates the safety threshold of the pressure in the BHU container 220. The controller 210 operates to maintain the pressure below the safety chamber pressure variable 变. In this embodiment, this chirp is set to 9 Torr above atmospheric pressure. Generally speaking, in this embodiment 200, these variables are used by the controller 210 to control both the oxygen level and the pressure level inside the BHU 220. The oxygen and pressure levels are typically sampled by the sensor 230. The following is an example given to this embodiment for the purpose of illustration. At the beginning of the example, when the oxygen concentration exceeds 最大 of the maximum oxygen level quasi-variable, the controller 210 opens the bleed valve 27 to allow a larger nitrogen flow through the system. This in turn helps to quickly reduce the oxygen concentration in the BHU220. In some embodiments, the air release valve may be opened when the oxygen concentration is equal to the maximum oxygen level. Similarly, if the oxygen level falls below the warning oxygen level, the air release valve 270 is closed by the controller 210, Because the oxygen level approaches the desired level, and any path that allows oxygen to move back into the BHU 220 should be minimized. In this way, if the oxygen density in BHU220 exceeds the maximum oxygen level, the bleed valve 270 is opened, and if the oxygen concentration is less than the warning oxygen level, the bleed valve 270 is closed. Continue this example, if the oxygen density of BHU220 is less than or equal The desired oxygen level (ie, the desired oxygen level variable 値), and the B HU pressure is between the minimum chamber pressure variable 値 and the maximum chamber pressure variable 値, -16- (14) ( 14) 200406818 The operation of Βίίϋ220 is generally in the typical or normal range. Therefore, the controller 2 10 closes the bleed valve 2 7 0 (if the bleed valve is open) and maintains a pressure sufficient to maintain the chamber pressure in a normal range and to maintain the oxygen density at the desired oxygen level quasi-variable 値The amount of gas below or above is passed through MFC265. Typically, the MFC2 65 remains partially open to restore nitrogen that has been lost from the inside of the BHU 220 to the outside via a crack or other pathway. Another part of this example is that if the pressure of the BHU220 exceeds the maximum chamber pressure variable, the calculation of the flow through the MFC265 (as implemented by the controller 2 10) will emphasize reducing the nitrogen flow to reduce the BHU pressure downwards. Bring back to the normal range, even if the oxygen level is higher than desired. In other words, the controller 210 emphasizes maintaining the desired pressure over the desired oxygen level. Similarly, if the pressure in the chamber 2 2 0 falls below the minimum B HU pressure variable 値, the controller 210 increases the gas flow through the MFC265 to bring the chamber pressure back up to the normal range, even if this Affects the oxygen concentration in the chamber. The last part of this example is that if the pressure of the BHU220 exceeds the pressure of the safety chamber pressure variable, the controller 210 closes the MFC265 and opens the air release valve 270. Therefore, when there is no gas inflow and the bleed valve is opened, excessive pressure should be quickly released. In this embodiment 200, such a situation rarely occurs even during normal operation. However, the controller 2 still provides this function to ensure the safety of the system. It should be understood that the specific variables described above and the specific numbers given are merely illustrative. Other embodiments may use different variables, or use different chirps for such variables. In addition, other embodiments may change the 値 of one or more variables according to the circumstances or other circumstances of the change of -17- (15) (15) 200406818. Therefore, the above information is provided by way of example rather than limitation. 4. Operation of the embodiment Fig. 3 is a table 300 showing an exemplary constant set used by the proportional / integral / derivative controller 110 of the embodiment 100 of Fig. 1. These constants can also be used by the embodiment 200 of FIG. 2. It should be understood that these constants may be changed in other embodiments, and may be zero or non-zero chirp as desired. ‘In general, the zero 任何 of any given variable inhibits the operation of that part of the controller 2 1 0 (i.e. proportional, integral, or derivative). Generally, the table 300 is divided into three rows and six columns. The top row represents the constant 値 when the pressure of the chamber 120 is below the minimum chamber pressure variable. The middle row represents the constant 値 when the chamber pressure is between the minimum and maximum chamber pressure variables. The bottommost row represents the constant 値 when the pressure of the chamber 120 exceeds the maximum chamber pressure variable.

In general, the columns represent different constants. For example, the "02-P" column represents the proportional oxygen band discussed below in relation to step 435 of FIG. 4. The "02-1" column represents the oxygen integral constants discussed below in relation to step 450 of FIG. The "02-D" column represents the oxygen differential constant, which may be used by the controller 110 in some embodiments to adjust the gas flow through the MFC 165. The "Pressure-P" column represents the proportional pressure constant. Like the oxygen differential constant, this constant can be used by embodiments of the present invention to control the gas flow through the MFC 165, and to control the oxygen density and overall pressure within the chamber 120 accordingly. The "Pressure-1" column represents the pressure integral constant, which can be used by the controller 1 10 for similar control calculations. Finally, the "Pressure-D (16) (16) 200406818" column represents the differential pressure constant, which can also be used by the controller 110 to calculate the gas flow through the MFC.値 shown in Table 3 00 in FIG. 3 is illustrative for Example 100. A zero 中 in all three rows of the "02-D", "Pressure-P", and "Pressure-D" columns indicates that these specific constants are not used by the embodiment. However, other embodiments may use such constants. Fig. 4 is a flowchart showing the general operation details of the embodiment 100 shown in Fig. 1. This flowchart can also be applied to the embodiment shown in FIG. 2. The steps shown in Figure 4 are typically performed by software or hardware system logic. This system logic is usually (though not always) implemented as part of the proportional / integral / derivative controller 1 1 0. Operation begins at step 400, where the PID controller 110 opens the purge valve 170 and nitrogen begins to flow through the MFC 165. Once step 400 is completed, embodiment 100 executes a loop containing steps 405 to 465. This is typically performed on a set time period or on a periodic basis after a certain time period has elapsed, for example, in one embodiment, the 'loop is executed approximately every four seconds. Another embodiment includes responding to a trigger to execute a loop, such as responding to changes in environmental variables. Exemplary triggers may include variables that are exceeded or commands initiated by the user. In another alternative embodiment, this loop may be executed only once, or it may be executed a set number of times. First, in step 405, the embodiment 100 determines whether the pressure of the chamber 120 exceeds the pressure of the safety chamber pressure variable 値. If it exceeds', the embodiment executes step 41. In step 4 10, the controller Π0 closes -19- (17) (17) 200406818 MFC1 65 and opens the air release valve 170. After completing step 410, the embodiment 100 performs step 465, where the embodiment waits for the next iteration of the loop. If the embodiment 100 determines that the pressure of the chamber 120 is equal to or lower than the setting of the pressure variable of the safety chamber, steps 4 to 15 are performed. In step 4 1 ', it is determined whether the oxygen concentration exceeds the maximum oxygen variable 値, and if it is exceeded, step 420 is performed so that the purge valve 1 70 is opened (if its 尙 is not opened). After step 420, the embodiment performs step 435, the details of which are as follows. If the oxygen density does not exceed the maximum oxygen level variability in step 4 1 5, step 4 2 5 is performed. In this step, Example 100 determines whether the oxygen concentration in the chamber 12 is smaller than the warning oxygen level 警. If the oxygen concentration is higher than this value, proceed to step 4 3 5. Otherwise, step 430 is performed. In step 43 0, the controller 1 10 closes the purge valve 170 if it is in an open state. In step 435, Example 100 determines the "proportional contribution" to the gas flow through MFC165. This proportional basis is based on the current oxygen concentration in the chamber. The proportional basis is generally equal to the difference between the current oxygen level and the desired oxygen level divided by the size of the "oxygen proportional band". The oxygen proportional band is a user-changeable parameter that defines the range in which the proportional term of the controller 110 responds proportionally. Expressed mathematically, the proportional basis 値 can be determined in the following ways:

Pc = (〇2C-〇2D) / 02P; where P c = proportional basis 値; 〇2C = the current oxygen concentration of the chamber 120; 02D = the desired oxygen concentration of the chamber 120 (that is, as discussed above) (18) (18) 200406818 ("desired oxygen level" variable); and 〇2P = oxygen proportional band (in this example 100, shown in the "02-P" column above). For example, the proportional band in an embodiment of the present invention may be 1,000 ppm (relative to 5,000 shown in FIG. 3), and the desired oxygen level variable may be 10 ppm. Therefore, the oxygen concentration in the current chamber at 1 Oppm will result in a proportional basis of 10% of the maximum flow rate of the MFC: (1 1 0- 1 0) / 1 000 = 10% of the MFC flow capacity. After step 43 5 is completed, The embodiment 100 determines in step 445 whether the pressure of the current chamber 120 is between the minimum chamber pressure variable and the maximum chamber pressure variable. If the pressure is within this normal range, step 450 is performed. In step 450, the embodiment 100 calculates an "integral contribution". The integral base is used by the controller 110 to at least partially control the flow of gas through the MFC 165. In general, the integral base 値 represents the flow rate of the gas flowing into the chamber 120, and is expressed here as a percentage of the maximum gas flow rate through the MFC 165. The integral and proportional basis are generally used to maintain operating parameters in the chamber 120. The "operating parameter" here generally refers to the oxygen density of the chamber 1 20 and the pressure of the chamber. Proportion and integral basis together help determine the gas flow through the MFC 165, as explained in more detail in step 460. Continuing the discussion at step 4 50, the embodiment finds the difference between the (19) (19) 200406818 oxygen concentration of the current chamber 1 2 0 and the desired oxygen concentration in the chamber and then multiplies it by the oxygen Integrate the constant to calculate the integral basis 値. This formula can be expressed mathematically as follows:

Ic = (〇2C-02D) * 〇21; where IC = integral basis 値; 〇2C = current oxygen concentration of the chamber 120; 〇2D = desired oxygen concentration of the chamber 120 (ie, discussed above) The "desired oxygen level" variable); and φ 〇2l == oxygen integral constant (in this embodiment 100, shown in the "02-1" column of FIG. 3). For example, if the current oxygen level of the chamber 120 is 110 ppm, and the embodiment uses an oxygen integral constant of 0.01 and a desired oxygen level variable of 10 ppm, the integration basis 値 is: (110 -10) * 0.01 = 10/00 of the flow capacity of the MFC If the pressure of the chamber 12 is determined to be outside the normal range in step 4 45 in Example 100, step 440 is performed. In step 440, the embodiment calculates the integration basis 値 to be repeatedly added to the loop based on the pressure of the chamber (as opposed to making the integration basis 値 according to the oxygen density in step 450). In step 44, the embodiment 100 calculates the current pressure of the chamber 120 and the minimum pressure (if the current chamber pressure is below the minimum pressure variable) or the maximum pressure (if the current chamber pressure is at the maximum pressure Above) and multiply this difference by the pressure integral constant. The resulting number is the integral basis 値. With the number -22- (20) (20) 200406818 ’when the current pressure in the chamber is less than the minimum chamber pressure variable, the formula for the integral constant is as follows:

Ic (Cvar-Ccurr) * PI; where

Ic = integral basis 値;

Cvai · == exceeded chamber pressure variable (minimum or maximum chamber pressure variable discussed in section 3 above);

Ccurr = current pressure of the chamber 120; and pI = pressure integral constant (in this example 100, it is shown in the "pressure-1" column of FIG. 3). For example, in an embodiment having a current chamber pressure of 1.9 Torr, a minimum chamber pressure variable of 2 Torr, and a pressure integral constant of 〇1, the integration basis 値 is: (2-1.9) * 0.1 = 1% of MFC flow capacity Another example may help. In an embodiment with a maximum chamber pressure variable set to 4 Torr, a current pressure of 4.2 Torr of the current chamber 120, and a pressure integral constant of 0.1, the integration basis 値 is: (4.0-4.2) * 0.1 = -2% of MFC flow capacity Once the integration basis 値 is determined in step 440 or step 45, step 4 5 5 is performed. In this step, 'Example 100' adds the calculated integral base 値 to the "point total". The integral sum is the sum of all integral bases 値 calculated in the previous loop repeat -23- (21) (21) 200406818. Therefore, the sum of the integrals repeats the integral basis for successive loops. Using the above example with an integral base 値 of -2%, and assuming the previous total of 65%, the new total of 63%. Generally speaking, an increase in the integral sum represents an increase in the gas flow through the MFC 165, while a decrease in the integral sum represents a decrease in the flow through the FMC. After step 4 5 5 is completed, step 4 60 is executed. In step 460, the embodiment 100 determines the final flow rate (or "percentage of operation") of the MFC that is repeated for a specific circuit. The flow controller 165 in turn operates the percentage by adjusting the position of the MFC. Generally speaking, the flow of M F C 1 6 5 is obtained by adding the proportional term calculated in step 4 3 5 to the sum of the points calculated in step 4 5 5. Continuing the above example, the proportional term is set to 10% in step 4 3 5 and the total point is set to 63% in step 4 5 5. Therefore, the operating percentage of the new MFC165 is 73% of its maximum possible flow. In this way, the flow controller 16 5 is set to M F C 7 3% on. After step 460 is completed, step 465 is performed. In this step, Example 100 waits for the one-hour meter to terminate to start the next loop cycle. In another embodiment where the loop response trigger is performed, such as in response to a change in oxygen density or pressure inside the chamber 120, once the trigger is detected, the loop starts again at step 405. This change typically occurs because the positioning of the MFC 165 is adjusted by the controller 110. 5. Conclusions As will be appreciated by those skilled in the art from the above description of the sample embodiments of the present invention, without departing from the spirit and scope of the present invention, it is possible to describe the subject-24-(22) (22) 200406818 The embodiment makes a lot of changes. For example, gas control systems can use different set points, flow controllers, implementations of PID / PI controllers, etc. In addition, although the present invention has been described in terms of specific embodiments and processes, such description is for illustration only and not for limitation. Therefore, the correct scope of the present invention is defined by the scope of the accompanying patent application rather than the previous examples. [Brief Description of the Drawings] FIG. 1 shows an embodiment of the present invention. FIG. 2 shows an exemplary operating environment for an embodiment of the invention. FIG. 3 is a table showing exemplary operating parameters of the embodiment of FIGS. 1 and 2. FIG. 4 is a flowchart showing details of the operation of the embodiment of FIGS. 1 and 2. FIG. [Explanation of drawing number] 1 00 Embodiment 110 Controller 120 Container 130 Sensor 140 Inlet port 1 50 Gas source 160 Gas pipe or pipeline

165 Flow controller, MFC 17 0 Bleed valve or outlet valve 180 Out □ 1 90 Pipe fitting-25- (23) 200406818 195 Vent 200 Example 201 Unified front pod (FOUP) 202 Robotic arm 2 03 Wafer carrier 204 lifts

205 Semiconductor furnace 2 10 Controller 220 Ship processing unit (BHU) chamber, ship processing unit (BHU) 23 0 Sensor 26 5 Mass flow controller (MFC) 270 Purge valve

-26-

Claims (1)

(1) (1) 200406818 Scope of patent application 1. A device for controlling the pressure and the first gas density of a chamber, comprising: a first gas density sensor; a second pressure sensor; control A mechanism connected to the first and second sensors, the control mechanism receiving data related to the first gas density and pressure from the first and second sensors; and a flow controller connected to the control mechanism The flow controller regulates the flow of a second gas into the chamber. 2. The device according to item 1 of the scope of patent application, further comprising: an air bleed valve connected to the control mechanism, the air bleed valve regulating the atmospheric air flow from the chamber; wherein the control mechanism is operable to respond to The signal of one of the first and second sensors adjusts the position of the flow controller. 3. The device according to item 2 of the patent application scope, wherein the control mechanism is further operable to adjust the position of the air release valve in response to a signal from one of the first and second sensors. 4. The device according to item 1 of the scope of patent application, wherein the control mechanism includes a proportional / integral / derivative controller. 5. The device according to item 4 of the patent application scope, wherein the first and second sensors are integrated with each other. 6. The device according to item 4 of the patent application scope, wherein the flow controller is a mass flow controller. -27- (2) (2) 200406818 7. The device according to item 6 of the scope of patent application, wherein the mass flow controller can be partially adjusted between the open position and the closed position. 8. The device according to item 2 of the scope of patent application, wherein the signal is a signal indicating that the first gas density is already above a threshold and signals indicating that the first gas density is below a threshold Groups formed 9. The device according to item 8 of the patent application, wherein the operation position of the air release valve can be continuously changed between opening and closing; and the operation position of the air release valve follows The signal changes. 10. The device according to item 7 of the patent application scope, wherein the first gas and the second gas are different gases. 11. The device according to item 10 of the patent application scope, wherein the first gas contains oxygen. 1 2. The device according to item 11 of the patent application scope, wherein the second gas contains nitrogen. 13. The device according to item 4 of the scope of patent application, wherein the control mechanism further comprises: a system logic operatively connected to the controller; and first and second set points operatively connected to the system logic. 1 4 · The device according to item 13 of the scope of patent application, wherein the first set point includes a first chamber pressure set point; the second set point includes a second chamber pressure set point; the first set point And the second chamber pressure set point define a first chamber pressure range extending from zero to the first -28- (3) (3) 200406818 the chamber pressure set point, extending from the first chamber pressure set point A second chamber pressure range to the second chamber pressure set point, and an infinitely large third chamber pressure range extending from the second chamber pressure set point; the controller includes a ratio / integral / Differential controller; the system logic additionally includes first, second, and third sets of tuning constants operatively connected to the proportional / integral / differential controller; and the first, second, and third sets of tuning constants Corresponding to the first, second, and third chamber pressure ranges. 15. The device according to item 14 of the scope of patent application, wherein one of the tuning constants in one of the first, second, and third tuning constants is zero. 16 · The device as described in item 15 of the scope of patent application, wherein a first integral term of the proportional / integral / derivative controller is assigned to the chamber pressure; It is not zero when it is within the pressure range of the second chamber, otherwise the first integral term is zero. 17. The device according to item 16 of the scope of patent application, wherein a second integral term of the proportional-integral / derivative controller is assigned to the oxygen level of the chamber; It is not zero when it is within the pressure range of the second chamber, otherwise the second integral term is zero. 18. The device according to item 16 of the scope of patent application, wherein the container is a ship processing unit in a semiconductor manufacturing environment. -29- (4) 200406818 1 9 · A method for adjusting the operating parameters of a containment chamber, comprising: monitoring a first gas density; monitoring a chamber pressure; calculating a proportional basis 値 based on the first gas density; determining the chamber pressure Whether it is within the normal pressure range; in the case that the pressure of the chamber is not within the normal pressure range, calculate an integral basis 値 based on the first gas density; Adjust the operating parameters based on the proportional basis and the integral basis. 2 0. The method of adjusting the operating parameters of the container as described in item i 9 of the scope of the patent application 'additionally includes the calculation of an integral basis based on the pressure of the container when the pressure of the container is within the normal pressure range. step. 2 1 · The method for adjusting the operating parameters of a container as described in item 20 of the scope of the patent application, wherein the step of adjusting the operating parameters includes: summing the integral base 値 with the sum of the previously calculated integral ratios to calculate an integral sum; Sum the proportional base and the total of the points to determine an operating percentage; and adjust the operating parameters based on the operating percentage. 22. The method for adjusting the operating parameters of a container according to item 21 of the scope of the patent application, wherein the operating parameter is a group consisting of a free-gas density and a chamber pressure. 23. The method for adjusting the operand of a storage chamber as described in the item "Scope of the Patent Application", wherein the step of adjusting the operation parameter according to the operation percentage includes ~ the flow path to the chamber to be equal to the operation percentage- 30-(5) (5) 200406818 open. 24. The method for adjusting the operating parameter of the chamber as described in item 22 of the scope of the patent application, wherein the step of adjusting the operating parameter according to the operating percentage includes a second gas Introduced into the chamber. 2 5. The method for adjusting the operating parameters of the chamber as described in item 24 of the scope of patent application, wherein the first gas is oxygen; and the second gas is nitrogen. Φ 2 6. As claimed in the patent The method for adjusting an operating parameter of a chamber according to item 21 of the scope, further comprising: determining whether the first gas density exceeds a maximum first gas density; and when the first gas density exceeds the maximum first gas density In order to reduce the first gas density, 2 7. The method for adjusting the operating parameters of the chamber according to item 21 of the patent application scope, further comprising: ® determining the first gas density If it is less than a warning first gas density; and when the first gas density is less than the warning first gas density, reduce the first gas density. 2 8. The regulating chamber according to item 20 of the scope of patent application The method of operating parameters further includes: determining whether the pressure in the chamber exceeds a safety threshold; in a case where the pressure in the chamber exceeds the safety threshold, reducing the chamber pressure -31-(6) 200406818 chamber pressure And further responding to the pressure of the chamber exceeding the safety threshold, the operating parameters are not adjusted based on the proportional basis and the integral basis.