KR20010006278A - In situ getter pump system and method - Google Patents

Abstract

The wafer processing system is a processing chamber, a low pressure pump connected to the processing chamber for pumping noble and non-permanent gases, a valve mechanism for connecting a noble gas source to the processing chamber, arranged in the processing chamber, and which noble gas is introduced into the chamber. An in-situ getter pump for pumping non-permanent gas, and a processing mechanism for processing a wafer arranged in the processing chamber. In-situ getter pumps can operate at a number of different temperatures to selectively pump different gases at these temperatures. The gas analyzer adjusts the gas pumped from the chamber as it is used to automatically adjust the temperature of the getter pump. Another embodiment of the present invention includes an additional in-situ getter pump provided in the transfer chamber of the semiconductor manufacturing apparatus.

Description

In situ getter pump system and method

Many processes require ultra-high vacuum, such as 10 ^-7 to 10 ^-12 Torr, for example high vacuum physical machinery such as cyclotrons and linear accelerators require a vacuum of 10 ^-8 to 10 ^-12 Torr. In the semiconductor processing apparatus of the semiconductor manufacturing industry, ultra-high vacuum of approximately 10 ^-7 to 10 ^-9 Torr is required.

Typically, a series of pumps are used in series or in parallel to make the chamber extremely ultra vacuum. Generally, a mechanical pump (eg an oil pump) is used to reduce the pressure in the chamber to about 30-50 mTorr. They are often referred to as "high pressure" pumps because they only pump relatively high pressure gases. However, high or ultra high vacuum pump systems such as molecular pumps, ion pumps, cryopumps, turbo pumps, etc. are used to reduce the pressure to about 10 ^-7 to 10 ^-9 Torr. These pumps are often referred to as "low pressure" pumps because they pump low pressure gas. The pump-down time in a particular chamber depends on factors such as chamber size, pump capacity, conductance from chamber to pump, and the desired final pressure and may take several minutes to several days.

In ultra-high vacuum apparatuses, getter pumps have been used in combination with mechanical pumps, molecular pumps and cryopumps. The getter pump contains a getter material (metal alloy) which has affinity for non-aliphatic gases. For example, a getter pump is designed that selectively pumps non-permanent gases such as water vapor and hydrogen according to the composition and temperature of the getter material.

For example, a getter pump manufactured by SAES Getters of Linate, Italy, has been installed in a molecular accelerator for many years. The getter pump includes a getter material contained in a stainless steel container. The getter pump may be operated at room temperature to 450 ° C. depending on the type of gas to be pumped and the getter composition. The getter material used in the conventional SAES getter pump is ST707 ^TM getter material (Zr-V-Fe alloy) manufactured by SAES Getters of Linate, Italy. Another getter material is the ST101 ^TM getter alloy, Zr-Al alloy, available from SAES Getters. Any of these conventional getter pumps can be thought of as "in situ" pumps, which are disposed in high vacuum physics.

The getter pump can also be used for semiconductor processing equipment. For example, in Briesacher's article "Non-Evaporation Getter Pumps for Semiconductor Processing Devices," a getter is used to purify process gases for semiconductor processing and a non-evaporation getter pump can be used for in-situ purification and selective impurity pumping. It became.

The Briesacher document mentioned above discloses two operating scenarios in which a getter pump can be used in a sputtering system. The first is to add a getter pump to the system to work with conventional pumps (eg mechanical and cryopumps). This scenario allows the getter pump to be used only as an auxiliary pump, without changing the system operation, to lower the gas partial pressure of any component of the residual gas in the chamber. The second scenario is to pressurize the chamber to 3 x 10 ^-3 to 6 x 10 ^-3 Torr to prevent argon from entering the chamber and to seal the chamber. So the getter pump can be said to function as an argon "in-situ" purifier. However, as described below, the pump is in fact "in-situ" and the active material is not in the processing chamber. Experimental processing chambers using these getter pumps have been used for many years under the guidance of Dr. Ohmi at the Department of Electronics, Tohoku University, Japan.

The Briesacher document discloses a getter pump that can be used with a sputtering system, a semiconductor processing apparatus. In one example of a typical sputtering system, noble gases (usually argon) are pumped into the chamber and plasma is generated. This plasma accelerates the movement of argon ions toward the target causative and deposits on the wafer surface. The getter pump is suitable for use with a sputtering system because only a predetermined process gas is a noble gas which is not pumped by the getter pump. Therefore, the getter pump can remove the impurities gas from the sputtering chamber without affecting the flow of noble gas required in the sputtering process.

The Briesacher literature is an academic analysis of the practical use of non-evaporative getter pumps for semiconductor processing equipment. Therefore, practical application of this theory is hardly described. The Briesacher article also uses the term "in-situ" to describe a scenario for the use of a getter pump, whereas in this specification the getter pump is present outside the chamber to seal the chamber and prevent argon from entering the chamber. It can be considered "in-situ" only when it is thought that the volume can be connected to the chamber volume. But in fact this is an "in-situ" and the getter pump surface is in a volume that is connected to the chamber volume via a restrictive throat. The restrictive throat significantly limits the conductance between the chamber and the pump. For example, pumping through a pump throttle can reduce conductance by more than 25% and through the throat of a pump with a heat shield (to protect the active element in the cryopump from the heated member of the processing chamber). Pumping will reduce the conductance by more than 60%.

Sputtering systems used to fabricate integrated circuits have operational characteristics, which can be augmented by an in-situ getter pump in a manner not emphasized in the prior art. One of these features is the fact that production sputtering devices must be operated at various pressures and gas compositions. This feature is absent, for example, in the particle accelerators of Princeton University, ie, particle accelerators which are usually maintained at high vacuum. This feature is not emphasized in the Briesacher literature. In particular, sputter chambers of commercial sputtering machines are frequently exposed to three completely different environments. The first environment appears when the chamber is open to the atmosphere due to routine maintenance or repairs. Under these circumstances the chamber is contaminated with atmospheric gases and contaminants. The second environment occurs when the chamber is operated under conditions of 10 ^-7 Torr or less, such as when ultra-vacuum, eg when loading or unloading the chamber, when pumping down to the "reference pressure" before processing. A third environment is present during processing if the pressure of argon gas in the sputtering chamber is a fine mTorr.

In order to circulate these operating environments a conventional sputtering chamber is connected to a mechanical (high pressure) pump and a cryopump (low pressure pump). Mechanical pumps may be reducing the pressure in the chamber to about 30~50mTorr, cryopump (or other high vacuum pump such as a turbo pump) may be used to reduce the pressure in the pressure in the chamber to about 10 ^-7 Torr ~10 ^-9 .

It is desirable to minimize the "transient time" between these operating environments. For example, in the case of an ultra-high vacuum at atmospheric pressure, the conventional mechanical pump and cryopump take 600 to 700 minutes to make a predetermined volume. Therefore, after each routine maintenance or repair, it may take more than 10 hours for the sputter chamber to accept the wafer for processing. This can cost thousands to millions of dollars to extend the "downtime" of a sputtering machine beyond its lifetime.

Since the total "pumpdown" time depends on the cryopump rather than the mechanical pump, increasing the size and pump conductance of the cryopump is one of the solutions. By "conductance" is meant that fluid (in this state gas) is likely to flow from one volume (eg processing chamber) to another (eg pump chamber). Conductance is defined by the size of the opening between the two chambers, the throat cross-sectional area of the cryopump, and by the path direction between the atoms, molecules and particles to be pumped and the active area in the cryopump. Unfortunately, increasing the size and conductance of the cryopumps increases the amount of argon that must flow into the processing chamber to support the sputtering process. This leads to two undesirable side reactions. First, due to the high cost of argon gas, the unit cost is extremely increased. Second, the large amount of argon pumped by the cryopump will saturate the pump rapidly enough to require frequent regeneration (when trapped material is released from the pump), resulting in longer system downtime. In conclusion, increasing the size of a cryopump is not commercially viable.

It is generally desirable to have a large capacity cryopump because it allows the time interval between regeneration cycles to be as long as possible. However, large cryopumps have increased throat and conductance. In the prior art, the baffle plate comprises, for example, one or more holes or other openings, which can be placed on the mouse of the cryopump to reduce the conductance to an acceptable level. On the other hand, a small cryopump with a small conductance can be used without a baffle plate and other limiting mechanisms can be used. However, a small cryopump may reduce the time interval between regeneration cycles. In addition, the reference pressure according to any of these solutions is greater than with any large cryopump. This is undesirable because the lower the reference pressure, the cleaner the chamber.

Another solution to the problem of sputtering pumping chambers is to add a cryopump, one of which has a large conductance to pump down the chamber to the reference pressure, and the other cryopump The conductance is small enough to pump. But this solution also has its drawbacks. Since cryopumps have a significant amount of space, they require liquid helium cryogenics and liquid nitrogen cryogenics to operate. Therefore, it is not desirable to add a cryopump in a narrow space around the semiconductor manufacturing apparatus. Cryopumps are also very expensive, making them an expensive solution. Small cryopumps will also need to be rebuilt frequently. Each cryopump will also require an expensive and bulky gate valve and control system. Eventually the chamber will have to be redesigned to accommodate the two cryopumps.

Another solution would be to use baffle plates with orifices of various sizes. This is attractive in theory, but baffle plates for large cryopumps (eg, 20.3 cm) are not commercially available and will be very expensive and difficult to manufacture. Contamination problems may also arise with regard to the mechanism of the variable orifice.

Getter pumps are characterized by the ability to pump gases selectively. For example, other gases may be selectively pumped by changing the composition of the material (usually a metal alloy) and its operating temperature. For example, the above-mentioned ST707 alloy can selectively pump the non-permanent gas at about 350 ° C., and can selectively pump the halogen gas at room temperature (about 25 ° C.). This getter material feature is used to purify noble gases and nitrogen, as disclosed in US Pat. No. 5,238,469, which is hereby incorporated by reference from Brischer to SAES Pure Gas. However, the prior art does not describe the use of an in-situ getter pump which is operated to selectively pump some gas at some temperatures.

A problem with the prior art is the periodic maintenance with increasing "down time" of the semiconductor manufacturing apparatus (or "system"). For example, a device manufacturer must lift a semiconductor manufacturing device after cleaning, inspecting, changing parts, or performing regular calibrations, such as once a month or a given number of times for use. After periodic maintenance, the system must be "pumped down" to a pressure low enough before it can be used again. This includes pumping down the processing chamber and pumping down a transfer chamber containing a Robert arm that loads and unloads a wafer from the processing chamber.

The transfer chamber of the semiconductor processing apparatus should be placed under or under the pressure of the processing chamber. In the past, the transfer chamber was pumped down by combining a mechanical pump and a cryopump, but it took about 8 hours to pump down the transfer chamber. This pump down time results in thousands of dollars in production losses due to inability to process semiconductors.

The present invention relates to an ultra high vacuum system, and more particularly to an in situ getter pump for use in an ultra high vacuum system.

1 is a system diagram showing a semiconductor processing plant including an in-situ getter pump system according to the present invention;

2 is a cross-sectional view taken along line 2-2 of FIG.

3 is a side view of the getter module according to the present invention;

3A is a cross sectional view taken along line 3A-3A of FIG. 3 showing a single getter element of the present invention;

4 is a block diagram showing another embodiment of the in-situ getter pump system of the present invention;

Figure 5 shows another embodiment of the in-situ getter pump system of the present invention;

6 is a pressure graph in a chamber according to the first pump down process of the present invention;

7 is a pressure graph in a chamber according to a second pump down process of the present invention;

8 is a prochart showing a process according to the present invention;

9 is a flowchart detailing step 162 of FIG. 8; And

10 is a system diagram of another embodiment of the present invention showing a semiconductor preliminary value including an in-situ getter pump according to the present invention located in a transfer chamber of a semiconductor processing apparatus.

The wafer processing system of the present invention includes a processing chamber, a low pressure pump, and an in-situ pump located within the processing chamber. The low pressure pump is preferably a cryopump connected to the processing chamber by a throttle plate. The valve mechanism connects the noble gas source to the processing chamber so that the noble gas flows continuously into the processing chamber and is pumped out of the chamber by a low pressure pump. An in-situ pump, preferably a getter pump, pumps out non-permanent gas while pumping non-permanent gas while the noble gas flows into the chamber.

The getter pump includes one or more getter modules equipped with a heater. Some getter modules may be operated at a first temperature to selectively pump gases such as water vapor, while other modules may be operated at a second temperature to pump other gases such as halogens. A single module may also be provided that is heated to a first temperature to selectively pump the first gas and is heated to a second temperature to selectively pump the second gas. The heat shield is used to isolate the getter material from the heated or cooled surface in the chamber, so that the getter material can be independently temperature controlled.

The wafer processing system includes a gas analyzer connected to the chamber, and a controller having an input connected to the gas analyzer and an output connected to the heater. Automatic adjustment of the heater causes the first gas to be pumped as the getter pump is operated at the first temperature, and the second gas to be pumped as the getter pump is operated at the second temperature after the concentration of the first gas has dropped to a predetermined level. do. This allows the getter pump to selectively pump the gas in accordance with the gas composition in the chamber.

The processing chamber according to the invention comprises a sealable enclosure, wherein the in-situ getter pump system is arranged in an enclosure that can be operated at one or more temperatures to selectively pump other non-permanent gases at different temperatures. The in-situ pump includes a heater that is adapted to selectively pump non-organic gas (other than hydrogen) or hydrogen according to the temperature of the getter material. The processing chamber includes a gas analyzer and a controller having an input coupled to the gas analyzer and an output coupled to the heater.

The present invention also includes several wafer processing methods. In particular, placing the wafer in the processing chamber according to the present invention, encapsulating the chamber, pumping the chamber with an in-situ pump disposed in the chamber while introducing the noble gas into the chamber and simultaneously pumping the external low pressure pump and the non-permanent gas. And processing the wafer in the chamber while continuously introducing a noble gas. It is preferred that the method includes simultaneously pumping the chamber to reach a reference pressure with an external low pressure pump and an in-situ pump prior to introducing the noble gas into the chamber. It is also preferable to include the step of monitoring the gas composition and concentration in the chamber and adjusting the temperature of the getter material according to the analytical data. On the other hand, the temperature of the getter material can be adjusted in a pre-programmed or other non-feedback manner. In this way, the absorption characteristics of the getter material can be adjusted to pump the impurities in the noble gas stream.

In still another embodiment of the present invention, the getter pump is provided with a transfer chamber of the semiconductor manufacturing apparatus. The getter pump acts as an in-situ pump with a very high conductance in the inner product of the transfer chamber and works with the current cryopump to pump down the transfer chamber. Since the getter pump pumps some gases (especially hydrogen gas) very effectively, the total pumpdown time of the system is substantially reduced.

An advantage of the present invention is that it provides a system and method suitable for various operating conditions of a semiconductor manufacturing apparatus chamber. With an in-situ getter pump, the transient times in a semiconductor manufacturing device can be significantly reduced, resulting in reduced downtime and increased productivity and profitability.

In particular, there is an advantage in that one or more getter modules can be operated at different temperatures to selectively pump selected gases from within the sputtering system chamber. By using a gas analyzer to automatically adjust the temperature of the getter module, the pump down time can be significantly reduced.

In addition, there is an advantage that the in-situ getter pump can be used together with the cryopump. Since cryopumps are very effective at pumping noble gases such as argon, and getter pumps can pump non-permanent gases completely, the operation of the getter pump does not disturb the chamber and does not affect the flow of noble gases in the chamber. In-situ getter pumps can also assist with cryopumps to pump down chambers, allowing the use of low-capacity cryopumps or lower transient periods while using large baffle cryopumps.

These and other advantages of the present invention will become apparent from the following detailed description and drawings.

The wafer processing system 10 shown in FIG. 1 includes a first inclusion 12 for the Robert wafer handler 14 and a second inclusion 16 defining the processing chamber 18. The system 10 also includes a controller for controlling the operation of the mechanical pump 20, cryopump 22, gas exhaust system 24, plasma generator 26, and numerous wafer processes 10. 28) with a microprocessor. The invention also includes an in-situ getter system comprising a getter module 32, a shield 33, a variable power source 34, a residual gas analyzer (RGA) 36, and a microprocessor based on the controller 38. The wafer processing system 10 processes the semiconductor 40 mounted in the chamber 18 by the Robert wafer handler 14.

Detailed manufacturing methods of the first enclosure 12 and Robert wafer handler 14 are well known in the art. The enclosure 12 defines a Robert chamber 42 that can be accessed through the slit valves 44 and 46. Typically, the Robert chamber is maintained at ultra high vacuum of 10 ^-7 Torr or less. The purpose of the Robert 14 is to automatically position the wafer 40 into the processing chamber 18 through the open slit valve 46, and to process the wafer 40 processed through the slit valve 46 after completion of the chamber. 18). Immediately after the slit valve 46 is opened, the pressure in the processing chamber 18 and the Robert chamber 42 is preferably at a level that minimizes turbulence when the slit valve is opened. When the wafer 40 is processed, the slit valve 46 is closed. Robert wafer handler 14 and gate valves 44 and 46 are all controlled by system controller 28.

The second enclosure 16 defining the processing chamber 18 is the same as a conventional design. This is preferably made of a strong, rigid material such as stainless steel, such as the first enclosure 12. In addition to the slit valve 46, a pair of valves 48 and 50 connect the mechanical pump 20 and the cryopump 22 to the chamber 18, respectively. Once chamber 18 is vented to the atmosphere (for maintenance or repair), valve 48 opens and pumps the chamber down to about 30 mTorr using a mechanical pump. At this time the valve 48 is closed and the cryopump valve 50 is opened to pump the system down to about 10 ^-9 Torr. The getter pump 30 is preferably operated by operating the cryopump 22 (ie, continuously). Processing of the wafer 40 begins when the chamber reaches a sufficiently low " reference pressure ". The reference pressure is usually 10 ^-7 Torr or less.

The "pumpdown" process described above is simply described as can be expected by one skilled in the art. It demonstrates in more detail below. After the chamber 18 is partially pumped down by the mechanical pump 20, the mechanical pump 20 is turned off and separated by the valve 48 and the valve 50 is opened to the cryopump 22. The chamber is then "barked out" into a heat lamp (not shown), where water vapor and other gases are released from the wall and the internal components of chamber 18 pumped by cryopump 22 are released. In addition, the getter pump 30 is activated by heating the getter material of the getter pump to a high temperature, for example, 450 ° C. The activation of this getter pump 30 is necessary because the getter material is "passive" as soon as it is exposed to the atmosphere, and the activation period overlaps with the daylight period. However, the daylight period and the activation period do not have to occur at the same time. Once the chamber is sunshine and the getter material is activated, the getter pump 30 is turned on and pumped to the cryopump 22 so that the chamber 18 rapidly descends to the reference pressure. Then, as one skilled in the art predicts, semiconductor processing proceeds.

To begin processing in the sputter system, the controller 28 opens the valve 52 to allow noble gases (especially argon) to flow from the gas source 54 into the chamber 18. Since the cryopump 22 remains open, it draws in argon gas and some byproducts from the sputtering process from the chamber 18. The valve 52 is adjusted to bring the argon pressure in the chamber 18 to a small mTorr, for example 1 x 10 ^-3 to 6 x 10 ^-3 mTorr. Since the in-situ getter pump 30 does not pump argon (a noble gas), argon is introduced into the chamber 18 without substantially affecting it. However, the getter pump 30 will pump some non-permanent gas while argon gas is introduced through the chamber 18, as described in more detail below.

As used herein, an "in-situ getter pump" may be referred to as a getter pump when the active ingredient, ie, the active getter material, is located in the same space as the wafer is processed. In fact, the getter pump chamber can be a processing chamber and vice versa. The conductance between the in-situ getter material and the processing chamber is very high compared to connecting the external getter pump through the gate valve, conduit and pump throat to the chamber passing through the heat shield. For example, an in-situ getter pump of the present invention having a heat shield 33 can achieve at least 75% of the maximum theoretical pump speed (typically 85% or more), with an external getter connected to the processing chamber by a gate valve or the like. Compared to 75% (35% lower) of the pump's maximum theoretical pumping speed. It should be noted that conductance and pumping speed are directly related and that the pumping speed is referred to as the relative percentage of the theoretical maximum pumping speed as if there is no obstruction between the getter surface of the given module and the getter pump.

By adding the in-situ getter system of the present invention, the pumping speed can be doubled or tripled over conventional getter pumps connected to the processing chamber via a pump throat or valve throat. The heater maximum theoretical pumping speed can be reached without the heat shield 33. However, the heat shield 33 preferably blocks the getter material from the heated surface of the chamber 18 as in the above-mentioned daylight lamp. The heat shield assists in regenerating the temperature of the getter material by recovering heat radiated from the getter material and the heater.

Once argon gas enters the cryopump through chamber 18, plasma generator 26 is activated and a plasma discharge occurs in chamber 18 (“strike”). There are a number of ways to generate plasma in the chamber, including the application of radio frequency (RF) signals to sputter targets, as is well known to those skilled in the art. As is well known to those skilled in the art, the plasma generates positively charged argon ions, which impinge upon the negatively charged or grounded sputter targets to cause the mass of material to fall on the wafer 40. The form of the material depends on the composition of the sputter target. Typically, materials such as aluminum, titanium and titanium-tungsten are used as sputter targets for depositing aluminum, titanium and titanium-tungsten, respectively, on the wafer surface.

The in-situ getter pump system 30 according to the present invention includes a getter module 32, a shield 33, a voltage source 34, an RGA 36, and a controller 38. Only a portion of the overall system is substantially arranged in the chamber 18. However, the active portion of the system 30, ie the getter module 32, is arranged in the chamber 18. The heat shield 33 is preferably located in the chamber to protect the active surface of the getter module 32 from the heated surface in the chamber. The heat shield may be removed if the getter module is arranged or protected to prevent interference by heated surfaces in the chamber. The heat shield 33 may be, for example, a fixed shield made of stainless steel, and may be a variable shield that is opened during operation and closed in any state (when opening the chamber 18).

Under other circumstances, such as opening the chamber 18 during maintenance and repair, the getter system controller 38 is preferably communicated with the sputter system controller 28 via the interface bus 55 so that the in-situ pump does not operate. Do. The controllers 28 and 38, on the other hand, may be connected within a single controller, as one of ordinary skill in the art would expect.

The getter module 32 includes a heater 56 to allow the temperature of the getter material in the getter module 32 to be selected. The thermocouple 58 is used to feed back the temperature so as to accurately adjust the temperature of the getter material in the getter module 32. Voltage source 34 is connected to heater 56 by cable 60 and energizes heater 56. The voltage source is variable so it can be turned on or off, or various other voltages or voltage widths can be obtained. Voltage source 34 can be turned on or off, the voltage of which is regulated by a signal sent from controller 38 via bus 62.

Residual gas analyzer (RGA) 36 is connected to processing chamber 18 by sensor 64 and cable 66. “Connected” here means that the analyzer 36 can receive information about the gas composition and concentration within the chamber 18. For example, the analyzer can be optically connected to the chamber 18 by having a photodetector, which is capable of viewing the plasma in the chamber 18 through a quartz port hole (not shown). In a preferred embodiment, however, the analyzer is connected to the chamber 18 by sensors 64 and cables 66.

A suitable RGA 36 can be obtained from Raybold Inpicon, Inc., East Syracuse, NY. ). The purpose of the RGA 26 is to detect what gas is in the chamber 18 and to detect what its concentration is. This information is supplied to the controller 38 via the bus 68.

In operation, the controller 38 receives information about the gas composition and concentration from the RGA 36 into the chamber 18 via the bus 38. The controller also receives information about the current temperature of the getter material in the getter module 32 via the bus 70. The controller 38 then determines whether the temperature of the getter material in the getter module 32 should be adjusted to change the pumping characteristics of the getter module 32. For example, if the RGA 36 determines that there is a high concentration of hydrogen gas in the chamber 18, and the thermocouple 38 indicates that the getter module 32 is currently operating at high temperatures, the controller 34 may display the bus 62. A signal is sent to the voltage source 34 via the voltage source 34 to be turned off. This turns off the heater 56 which cools the getter module 32 to low temperature. At low temperatures, the getter material such as ST707 and ST101 absorbs hydrogen violently and rapidly reduces the hydrogen concentration in the chamber 18. In another example, if the RGA 36 detects high levels of water vapor and the temperature of the getter module 32 is low, the controller 38 causes the voltage source 34 to increase the heat output of the heater 56 so as to obtain the getter material. Is heated to 300-450 ° C. to allow water vapor to be pumped from the chamber 18 quickly and effectively.

As shown in FIG. 2, the cryopump 22 is preferably connected to the gate valve 50 by a throttle plate 72. As previously illustrated, the throttle plate 72 reduces the conductance between the processing chamber 18 and the cryopump 22. For example, if the mouse of the cryopump is 20.3 cm, the throttle plate 72 is slightly larger than 20.3 cm in diameter and may have one or more holes 74 (or other openings, such as slits), which are machined through the holes. Gas may be introduced into the cryopump 32 from the chamber 18. The conductance of the cryopump can typically be reduced to about 50-70% and can be reduced by almost 25% to the throttle plate design. This makes it possible to use a high capacity cryopump that does not need to be regenerated frequently, and because the conductance is low enough, no excessive amount of argon gas needs to be introduced into the chamber 18 during processing. It is also possible to use a much smaller cryopump 22 in balance without the throttle plate 72, and more often it will have to be regenerated until the cryopump is saturated with argon gas.

Thus, the in-situ getter pump system 30 has a special relationship with the cryopump 22. Since the conductance of the cryopump 22 should be limited, no excessive amount of argon gas (or other noble gas) is required during processing, and the insulator getter pump is pumped up during reference processing and boost pumping during semiconductor wafer processing. Can be used for speed. Since the insitu getter pump does not pump noble gases such as argon, it is ideally used as a cryopump 22 with intentionally limited conductance.

3 is a block diagram of the getter module 32. The getter module 32 includes a plurality of getter elements 74 arranged at regular intervals. Looking at the cross-sectional area of Figure 3a each getter element is provided with a central opening (hole) (76) accommodated in the long heater (56). Each getter element 74 is preferably substantially disk-shaped with a axial bore forming a central opening 76. Each getter element 74 has a pair of opposing faces 78 and 80, and may be any one of a plurality of getter materials (Italy, Linate, SAES Getters, trade name ST707 or ST101). These getter elements are preferably porous sintered getter elements as disclosed in US Pat. No. 5,320,496 (Manini et al., Assigned to SAES Getters) mentioned herein. Porous getter materials are sold under the trade name ST172 by SAES Getters. The preparation of the porous getter material is disclosed in British Patent No. 2,077,487, assigned to SAES Getters, which is mentioned herein.

In the embodiment of FIG. 3, adjacent getter elements 74, such as getter elements 74a and 74b, include exterior surfaces 82a and 82b. In the embodiment of FIG. 3, surfaces 82a and 82b are substantially flat and parallel. "Substantially flat" means that the surface is substantially flat although there is an acceptable difference from the complete plane. "Substantially parallel" means that there is some acceptable difference (eg, deviation ± 5 °) but is substantially parallel. In an embodiment of the invention, the getter element may have a non-planar surface or a non-parallel flat exterior surface. For example, the exterior surfaces (surfaces 82a, 82b, etc.) can be defined as a pair of planes (even under rather than complete planes) that intersect at an angle of 5 ° or less. This, in some instances, increases the absorption of the selected gas.

Heater 56 may be a suitable heating element. The requirement of the heater 56 should be able to heat the getter element 84 to a predetermined operating temperature range. This range is preferably uniform, but there may be temperature gradients or temperature discontinuities, depending on the length of the getter module.

For example, when the ST707 getter material is used, it is preferable that the heater can heat the getter element 74 to 25-30 占 폚 in operation and 450-500 占 폚 when activated. However, when the getter module 32 is used to pump hydrogen, it is usually not necessary to heat the heater 56. This is because the ST707 getter material pumps hydrogen very well at room temperature.

However, even if the heater 56 is not used to heat the getter element 74 to an operating temperature, it can be used to activate the getter material in the getter element 74. For example, the ST707 getter material can be activated (regenerated) by heating to 450 to 500 ° C, and the ST101 can be activated by heating to 600 to 700 ° C. However, regeneration may not be necessary because the getter module 32 may simply be thought of as a disposable or consumable item that is replaced during routine maintenance.

The heater 56 is described as a central axis that supports the getter element 74, while the getter element may be supported by an unheated axis or otherwise supported. Thus, the heater 56 can be separated from the structure for the getter element 74, such as a spin lamp positioned near the getter element.

As mentioned above, there are several techniques for providing the heater 56, for example, resistance heaters, induction heaters or radiant heaters. However, in a preferred embodiment of the present invention, the heater 56 is a resistance heater as shown in the Manini patent. The heater should be capable of heating at ambient or normal temperature to at least the operating temperature of the getter material. The heater should be able to heat the getter material to the active temperature.

The processing chamber 84 according to the present invention of FIG. 4 includes a hermetic enclosure 86 and two getter modules 88, 90 arranged in a chamber 92 defined by the enclosure 86. The system 84 includes an RGA 90 and a microprocessor controlled system 92. Of course, since this is the case with all controllers such as controller 92, controller functionality can be achieved with many of the same electrical or electronic systems. For example, the controller may include analog circuits, discrete digital logic, microprocessors, minicomputers, and the like. System 84 includes a pair of voltage sources 94 and 96. Although the enclosure 86 can be easily manufactured from welded stainless steel, it can be conventional. Since the enclosure 86 is equipped with a slit valve (not shown) or the equivalent, the workpiece can be easily inserted into and removed from the chamber 92. Once sealed, the enclosure 86 separates the chamber 92 from the environment.

There are several reasons why two or more (ie, multiple) getter modules, such as getter modules 88 and 90, are provided in chamber 92. For example, the two in-situ getter modules 88 and 90 can simply operate in parallel, doubling the capacity and pumping rate of the in-situ getter system. In addition, the getter modules 88 and 90 may be made of different getter materials, and may operate at different operating temperatures. For example, if the getter module 88 is made of ST707 getter material and operated at 300 to 400 ° C., most non-permanent gases except hydrogen may be selectively pumped. However, if the getter module 90 is made of ST101 getter material and placed at room temperature, hydrogen is selectively pumped. Thus, two getter modules can be combined to pump a wide range of non-protonal gases.

It is desirable to operate the system 84 in a closed loop manner, ie under feedback regulation. Thermocouples (or equivalents: 98, 100) can be used to monitor the temperature of the getter modules 88, 90, respectively, and the gas composition in the chamber 92 using the sensor 102 as the RGA circuit 91. And the concentration is detected. The controller 93 generates a signal using inputs from the RGA circuit 91 and the thermocouples 98 and 100, which signal source 94 is connected to each heater 104 and 106 of the getter modules 88 and 90. , 96).

The processing system 108 of FIG. 5 includes a sealable enclosure 110 defining a chamber 112 and three getter modules 114, 116, 118. It should be noted that each getter module 114 to 118 can be adjusted independently and can vary in size. For example, the getter module 114 may include a ST101 getter material and may not be heated to be maintained at room temperature, thereby selectively pumping hydrogen gas, and the getter 116 is heated to 300 to 450 ° C. It may include a non-permanent gas, and the getter module 118 may supplement the pumping capacity of the getter modules 114 and 116, including other getter material operated at different temperatures. For example, heaters 120, 122, 124 of getter modules 114, 116, 118 are connected to voltage source 126 by temperature controllers 128, 130, 132, respectively. The controllers 128-132 maintain the heaters 120-124 at a predetermined specific temperature sensed by the thermocouples 134, 136, 138. Thus, the temperature controller for each individual getter module 114-118 is a closed loop or feedback system, whereas the system 108 is a gas composition in the chamber 112 in which the getter modules 114-118 can always operate at the same temperature. And in terms of concentration, it is not a closed loop or feedback system. However, to get a good record of the process, the getter module and its operating parameters can be kept constant so that they can operate under the most common conditions.

6 shows a preferred example of a method for operating an in-situ getter pump according to the invention. The pressure P in the chamber on the graph is shown on the vertical axis and the time T is shown on the horizontal axis. The first line 140 represents the hourly partial pressure of water vapor in the chamber, and the second line 142 represents the hourly partial pressure of hydrogen in the chamber. Coupling water vapor 140 and hydrogen 142 results in a coupling pressure 144 in the processing chamber.

Referring to FIG. 6, a process using a single getter module such as getter module 32 of FIG. 1 as an in-situ getter pump after activation and at pump down will be described. The graph of FIG. 6 is for illustration only and the actual partial pressure curve will be different. In this case, the getter module 32 may be assumed to include an ST707 getter material which absorbs water vapor (H ₂ O) well in the range of 300 to 450 ° C, for example, at 350 ° C. The ST707 also absorbs hydrogen well at room temperature, for example 25 ° C or lower. In this case, the RGA 36 detects a high level of water vapor at time t = 0 and the controller 38 heats the getter module 32 to about 350 ° C. by turning on the heater of the voltage source 34. This drastically reduces the water vapor level until the time t = T1 when water vapor is completely removed from the chamber. However, the partial pressure of hydrogen remains virtually the same because the ST707 can absorb hydrogen well at high temperatures. Once the RGA 36 detects that the water vapor level in the chamber 18 is low and the hydrogen level 42 is high at time t = T1, the system 38 turns off the voltage source 34 to turn off the heater and the getter module ( Allow 32 to cool while absorbing hydrogen. Thus, as shown in FIG. 6, a single getter module operating at two different temperatures can rapidly and effectively remove non-elastic gas from chamber 18 without disturbing the flow of noble gas through the chamber. .

The graph of FIG. 7 illustrates the operation of a system with multiple getter modules, such as system 84 shown in FIG. The graph of FIG. 7 is for illustration only and the actual partial pressure curve will be different. In this case, the partial pressure due to water vapor is represented by line 146, and the partial pressure due to hydrogen partial pressure is shown by line 148. In this case the total pressure in chamber 92 is represented by line 150. Once the RGA 91 detects water vapor and hydrogen concentration, the microprocessor 93 turns on the voltage source 94 and turns off the voltage source 96. The getter module 88 will thus rapidly pump water vapor from the chamber 92 by heating to about 350 ° C., and the module 90 will rapidly pump hydrogen from the chamber 92 because it can be operated at ambient temperature.

It is noted that multi-module systems can achieve higher pump speeds due to the larger surface and can pump different kinds of gases simultaneously. However, multiple in-situ getter modules make the system more expensive than a single getter module system.

The process 152 for wafer processing according to the present invention of FIG. 8 begins at step 154 and in step 156 activates an in-situ getter pump along with the cryopump to raise the reference pressure of the chamber. In step 158 the wafer is then inserted into the chamber and the chamber is sealed. Argon is introduced into the chamber in step 160, argon gas continues to flow in step 162, and plasma is generated while maintaining the in-situ pump system and the cryo system. In step 164 the plasma is stopped and the argon gas is turned off so that the in-situ pump system and the cryopump system reduce the pressure in the chamber. The processed wafer is then removed from the chamber at step 166 and the process ends at step 168.

In FIG. 9, a process 162 corresponding to step 162 of FIG. 8 is shown. Process 162 begins at 170 and monitors gas composition and concentration in the chamber at step 172. Thereafter, in step 174, the operating parameters of the in-situ getter pump are adjusted according to the monitoring step and any process heuristics. Process 162 ends at 176.

The process 162 shown in FIG. 9 is an example of a closed loop or feedback process. Of course, open system processes are variable and may be desirable for any application. The operating parameters of the in-situ getter pump referred to in step 174 include activating one or more getter modules and changing the temperature of the getter module or the like. The process sequence is the system designer's rule of thumb for optimizing the process. For example, the system designer may decide to reach a certain level of partial pressure of water vapor or to drop the temperature of the getter module with getter material ST707 from 350 ° C to ambient temperature after a certain time.

In Fig. 10 another system 10 'according to the invention is shown. The components of the system 10 'are substantially the same as the components of the system 10 of FIG. 1, used the same numbers, and do not describe the system 10' again.

As shown in FIG. 10, an auxiliary in-situ pump 178 is disposed in the Robert chamber (or “transfer chamber”) 42 of the system 10 ′. The mechanical pump 180 is first used to "pump down" the transfer chamber 42 to roughly pump the transfer pump, for example, 30-50 mTorr. The in-situ getter pump 178 is then operated simultaneously with the cryopump 182 to pump down the transfer chamber 42. By pumping the in-situ getter pump 178 and the cryopump 182 in parallel, the pump down time of the transfer chamber 42 can be reduced, and the system 10 ' It allows you to operate very quickly after take down.

In the pump down operation, the slit valves 44 and 46 of the transfer chamber 42 are closed to seal the chamber 42, and the valve 184 is opened to connect the mechanical pump 180 to the transfer chamber 42. . After rough pumping by the mechanical pump 180, the valve 184 is closed and the valve 186 is opened to connect the cryopump 182 to the transfer chamber 42. The getter pump 178 and the cryopump 182 are then operated simultaneously to pump down the chamber 42 more quickly. If the chamber reaches its reference pressure to be sensed by the pressure sensor 188 in the chamber 42, the valve 186 will close and the transfer chamber 42 may be operated in a routine manner.

The cryopump 182 does not need to have a baffle plate, such as the baffle plate 72, since the argon is not pumped into the transfer chamber 42 so that the conductance of the cryopump 182 does not have to be throated. Because. However, the cryopump 182 preferably includes a screen 190. The screen is intended to protect the interior of the cryopump 182 from damage as a result of the small material falling into the cryopump orifice.

Getter pump 178 is similar in design to the getter pump described above. The getter pump 178 is preferably made of a plurality of porous getter disks (manufactured by SAES Getters, ITALY, Italy). The getter disk is preferably supported by a metal rod (eg, stainless steel) used to inject heat between the getter disks.

In the transfer chamber in-situ getter pump (as opposed to the processing chamber in-situ getter pump described above), the thermoshield will not be needed. This is because there is no heated surface in the transfer chamber 42 where the getter material may overheat during the pumping cycle. However, for example, the heat radiator 192 made of polished stainless steel is preferably located near the getter disc such that the heat energy from the heater 194 is reflected onto the getter disc during the regeneration cycle of the getter disc. However, it is desirable to configure the heat reflector 192 such that the conductance of the getter pump 178 is kept as high as possible, that is, at least 75% of the conductance to the chamber 42.

The heater 194 is preferably a radiant quartz mercury lamp positioned close to the getter element. The heater 194 thus heats the getter element by direct radiation, radiation reflected from the thermal radiator 192, and thermal conduction through the metal support rod. On the other hand, the heater 194 may be a resistance heater located near the getter disk or in a rod supporting the getter disk.

The temperature of the getter pump 178 is preferably controlled by the closed feedback loop. More preferably, the microprocessor based controller 196 regulates a variable voltage source 198 that powers the heater 194. The temperature sensor 200 provides temperature data to the controller 196. The controller 196 communicates with the system controller 28 to provide information to the system controller and to receive instructions from the system controller, that is, commands generated by the system software.

The simplified control system is shown with respect to transfer chamber in-situ pump 192. However, more complex systems related to the processing chamber in-situ pump 32 can also be applied to the transfer chamber in-situ pump. Thus, the transfer chamber in-situ pump can operate at different temperatures, allowing it to selectively pump other gases at these different temperatures, which can be controlled by a feedback loop including a gas analyzer.

The transfer chamber in-situ getter pump 178 may comprise multiple getter pumps and may include the same or different types of getter material as mentioned in connection with the processing chamber in-situ getter pump. Thus a discussion of the placement of such multiple pumps is discussed herein in connection with transfer-in-situ pumps.

While the invention has been described in some preferred embodiments, other variations or modifications are possible within the scope of the invention. It is also possible to implement the processes and apparatus of the present invention in other ways. For example, while ST707 and ST101 getter materials have been described in the preferred embodiments of the present invention, it will be apparent to those skilled in the art that other getter materials and compounds are also suitable for the present invention. In addition, although cryopumps were first described in connection with the present invention, it will be understood that molecular pumps, ion pumps, turbopumps and the like may also be used.

Accordingly, the appended claims are to be interpreted as being capable of other changes or modifications without departing from the true spirit and scope of the invention.

Claims (31)

Transfer chamber; A low pressure pump connected to the transfer chamber and selected from the group consisting of a molecular pump, an ion pump, a cryopump and a turbo pump; An in-situ getter pump disposed in the transfer chamber and including a getter module and a heater disposed near the getter module to heat the getter module; A temperature sensor disposed near the getter pump; And And a controller coupled to the temperature sensor and operative to selectively adjust the temperature of the heater. The wafer processing system of claim 1, further comprising a mechanical pump connected to the transfer chamber. The method of claim 1, wherein the first temperature of the getter module is selected to pump at least one non-permanent gas in addition to hydrogen, and the second temperature of the getter module is selected to pump hydrogen as controlled by the controller. Wafer processing system characterized in that. 4. The wafer processing system as recited in claim 3, wherein said heater is further capable of heating said getter module to a third temperature to regenerate said module. The wafer processing system according to claim 3, wherein the getter material is Zr-Al, the first temperature is 300 to 400 ° C, and the second temperature is 25 to 100 ° C. The wafer processing system of claim 1, wherein the getter pump comprises a plurality of getter modules. The wafer processing system of claim 6, wherein the plurality of getter modules include getter materials of essentially the same type. 7. The wafer processing system of claim 6, wherein at least two of the getter modules comprise at least two different getter materials. The wafer processing system of claim 6, wherein the getter pump includes a plurality of heaters coupled to the getter module to adjust a temperature of each getter module. Transfer chamber; An in-situ getter pump system disposed in the transfer chamber and provided with a heater to operate the pump system at one or more temperatures to selectively pump other non-protonal gases at different temperatures; And And a Robert Transfer Arm for transferring a wafer into and out of the transfer chamber. 11. The apparatus of claim 10, further comprising: a gas analyzer connected to the chamber; And And a controller having an input coupled to the gas analyzer and an output coupled to the heater, such that the temperature is adjusted in accordance with the gas mixture analysis in the chamber. The wafer processing system of claim 11, wherein the first temperature is selected to pump at least one non-permanent gas in addition to hydrogen, and the second temperature is selected to pump hydrogen. The wafer processing system according to claim 12, wherein the getter material is Zr-Al, the first temperature is 300 to 400 ° C, and the second temperature is 25 to 100 ° C. The wafer processing system of claim 10, wherein the getter pump system includes a plurality of getter modules, each of which may be coupled to a heater to adjust the temperature of the plurality of getter modules. 11. The apparatus of claim 10, further comprising: a gas analyzer connected to the chamber; And And a controller having an input coupled to the gas analyzer and an output coupled to the plurality of heaters, such that the temperature of the getter module is adjusted in accordance with the gas mixture analysis in the chamber. Sealable enclosures; And And an in-situ getter pump system having a getter material disposed in the inclusion, wherein the non-permanent gas can be pumped at a different temperature when the inclusion is enclosed. 17. The processing of claim 16 wherein the in-situ getter pump comprises a heater, wherein the first temperature is selected to pump at least one non-permanent gas in addition to hydrogen, and the second temperature is selected to pump hydrogen. system. 18. The apparatus of claim 17, further comprising: a gas analyzer connected to the chamber; And And a controller having an input coupled to the gas analyzer and an output coupled to the heater, such that the temperature is controlled by the heater in accordance with the gas mixture analysis in the chamber. 19. The processing system of claim 18, wherein said pump system comprises a plurality of getter modules and at least two of said getter modules are maintained at different temperatures by said heaters. Spaced apart so that adjacent getter elements do not contact, each getter element comprising: a getter element having an opening at its center; A metal support rod arranged through the opening of the getter element to support the getter element; And And a radiation correction lamp heater arranged near the getter element and the metal support rod to conductionally heat the getter element by radially heating the getter element and thermally conducting through the support rod. 21. The in-situ getter pump module according to claim 20, wherein each getter element is substantially disk-shaped with a shaft bore defining an opening located in the center. 21. The in-situ getter pump module according to claim 20, wherein each getter element has a pair of opposing surfaces. 21. The in-situ getter pump module according to claim 20, further comprising a heat reflecting surface to reflect radiant energy from the quartz lamp toward the getter element. Encapsulating the transfer chamber; The transfer chamber is pumped with an external low pressure pump for pumping noble gas and an in-situ getter pump having an active element disposed in the chamber for pumping non-permanent gas and having a pumping speed of at least 75% of the theoretical maximum pumping speed. Doing; Transferring the semiconductor wafer to at least one processing chamber through the transfer chamber; And Processing the wafer in the at least one processing chamber as an essential step in the fabrication of an integrated circuit device. Encapsulating the enclosure; And Pumping the enclosure into an in-situ getter pump system arranged in the enclosure and operable at one or more temperatures such that when the inclusion is encapsulated another non-permanent gas is pumped at a different temperature; How to pump the chamber. 27. The method of claim 25, further comprising adjusting the temperature of the getter pump system to selectively pump at least one gas. 27. The method of claim 26, wherein said adjusting step is a closed loop process. 27. The method of claim 26, wherein said adjusting step is an open loop process. 27. The method of claim 26, further comprising monitoring a gas composition in the chamber, and adjusting the temperature of the getter pump system in accordance with the analysis of the composition. 30. The method of claim 29, wherein the getter pump system comprises at least two getter modules, and wherein the temperature control step is capable of adjusting the relative temperature between the two modules. Processing chamber; A situgetter pump which is a processing chamber arranged in the processing chamber; Transfer chamber; Robert arms arranged in the transfer chamber to transfer wafers into and out of the processing chamber; A transfer chamber pump which is a transfer chamber arranged in the transfer chamber; And And a processing system for processing wafers arranged in the processing chamber.