Abstract:
Semiconductor device manufacturing equipment includes a plurality of process chambers in which one or more fabrication processes takes place, a transfer chamber selectively communicating with the process chambers by means of doors, a vacuum pump and a source of vent gas which are connected to the transfer chamber via vacuum/vent lines to regulate the (vacuum) pressure in the transfer chamber, and a respective diffuser connected to at least one of the vacuum/vent lines. The diffuser includes a tube connected in series with the line and having a plurality of radial through-holes, a case including a cylindrical support surrounding the tube as spaced from the tube, and a particulate filter extending along an inner surface of the case. The cylindrical support has a plurality of pores smaller than the holes in the tube. The filter, on the other hand, has a plurality of micro pores smaller than the pores of the support.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to equipment for manufacturing a semiconductor device. More particularly, the present invention relates to a diffuser for diffusing gas introduced into a vacuum transfer chamber and to semiconductor device manufacturing equipment having the same.  
         [0003]     2. Description of the Related Art  
         [0004]     In general, a semiconductor device is manufactured by selectively and repeatedly carrying out fabrication processes on a wafer. These fabrication processes include deposition, photolithography, etching, diffusion, and ion implantation processes and the like. To this end, the wafer is transferred from a cassette, loaded with several of the wafers, to respective units for performing the fabrication processes. Accordingly, semiconductor device manufacturing equipment typically has a multi-chamber structure comprising a plurality of processing chambers in which the wafers are processed.  
         [0005]     Conventional semiconductor device manufacturing equipment having a multi-chamber structure will be described with reference to  FIG. 1 . This semiconductor device manufacturing equipment is of a cluster-type that includes a cluster of process chambers  10  in which at least one type of fabrication process is performed on wafers, and a common transfer chamber  20  to which the process chambers  10  are connected. In the case in which one or more fabrication processes such as plasma reaction, etching, and CVD are performed in the process chambers  10 , a vacuum is established in the process chambers  10  by means of a high performance vacuum pump (for example, a turbo pump).  
         [0006]     In addition to the process chambers  10 , the transfer chamber  20  is connected to load lock chambers  30 , an aligning chamber  40  disposed adjacent to the load lock chambers  30  for aligning the wafers before the wafers are processed in the process chamber  10 , a cooling chamber  50  for cooling the wafers that have been processed in the process chambers  10 , and a cleaning chamber  60  for ashing or cleaning the wafers that have been processed in the process chambers  10 . The wafer cassettes are loaded into the load lock chambers  30 . The wafers are thus introduced into and withdrawn from the semiconductor manufacturing equipment via the load lock chambers  30 .  
         [0007]     A respective door  70  is installed between the transfer chamber  20  and each of the chambers  10 ,  30 ,  40 ,  50  and  60  connected thereto. Each door  70  is opened and closed by a controller. A robotic arm  80  is disposed in the transfer chamber  20  for unloading the wafers one-by-one from a wafer cassette and transferring the wafers to desired positions in the equipment. One or more wafer supports  82 , e.g., vacuum chucks, are connected to the robotic arm.  
         [0008]     The transfer chamber  20  is maintained at almost atmospheric pressure when a wafer is transferred by the robotic arm  80  from or into a load lock chamber  30 . On the other hand, the transfer chamber  20  is maintained in a low vacuum state when a wafer is transferred by the robotic arm  80  into a process chamber  10 . At that time, the transfer chamber  20  is evacuated by means of a vacuum pump (for example, a dry pump) communicating with a vacuum hole  24  at the bottom of the transfer chamber  20 . In addition, once the door  70  interposed between the transfer chamber  20  and the process chamber  10  is opened, air flows from the transfer chamber  20  to the process chamber  10  because the internal pressure of the process chamber  10  is lower than that of the transfer chamber  20 . Consequently, fine particles are prevented from entering the transfer chamber  20  from the process chamber. Moreover, the transfer chamber  20  is supplied with a vent gas (for example, nitrogen gas) via a vent hole  22  at the bottom of the transfer chamber  20  to maintain the internal pressure of the transfer chamber  20  above that of the process chamber  10 .  
         [0009]     However, fine particles adhering to the wafer can separate from the wafer as the wafer is being transferred from the process chamber  10  into the transfer chamber  20 . In this case, the particles may remain in the transfer chamber  20  or migrate to the load lock chamber(s)  30 . In particular, the fine particles are likely to separate from the wafer if the vent gas flowing into the transfer chamber  20  is turbulent.  
         [0010]     Therefore, a diffuser  200  ( FIG. 2 ) is installed over the vent hole  22  to prevent eddies from occurring in the vent gas flowing into the transfer chamber  20 . Such a diffuser for regulating the flow of gas into a vacuum chamber is disclosed in U.S. Pat. No. 6,663,025.  
         [0011]     As shown in  FIG. 2 , the diffuser  200  includes a body  202 , a deflector  204 , a spider  206 , and a pair of guide vanes  210  and  212 . The body  202  has a nozzle  302  at a central portion thereof. The nozzle  302  is connected to a vacuum/vent line through which a vent gas flows. The deflector  204  is disposed over the central portion of the body  202  for deflecting the vent gas flowing through the nozzle  302 . The guide vanes  210  and  212  are interposed between the body  202  and the deflector  204  so as to guide the vent gas deflected back towards the body  202  by the deflector  204 .  
         [0012]     The nozzle  302  is a unitary part of the body  202  or may be a discrete member that is connected to the body  302 . In either case, the nozzle  302  has a nozzle opening that tapers; the portion of the nozzle opening adjacent the body  202  is wider than the portion of the nozzle opening that is connected to the vacuum/purge line. Also, the body  202  has a rounded upper surface. In this respect, a portion of the upper surface adjacent the nozzle  302  has a relatively steep slope compared to the portion of the upper surface that is remote from the nozzle  302 .  
         [0013]     The deflector  204  covers the nozzle  302  and a portion of the body  202  adjacent the nozzle  302  and is configured to reverse the direction of flow of the vent gas issuing from the nozzle  302 . Also, the deflector  204  protrudes toward the center of the nozzle  302  so as to uniformly distribute the vent gas issuing from the nozzle  302  towards the entire portion of the upper surface of the body  202  adjacent the nozzle  302 .  
         [0014]     More specifically, as the gas is injected into the transfer chamber  20  through the nozzle  302 , the gas is first allowed to expand within the nozzle  302  and at the deflector  204 , and is secondarily allowed to expand as it passes over the upper surface of the body  202 . As a result, eddies are prevented from occurring in the vent gas introduced into the transfer chamber  20 . Similarly, when the vacuum pump operates to create a vacuum in the transfer chamber  20 , eddies are prevented from being generated in the gas flowing from the transfer chamber  20 . In addition, there is a difference between the pressure of the vent gas flowing over the portion of the body  202  adjacent the deflector  204  and the pressure of the vent gas flowing over the portion of the body  202  remote from the nozzle  302 . However, the guide vanes  210  and  212  prevent such a pressure difference from producing eddies in the vent gas.  
         [0015]     Nonetheless, the diffuser  200  of the prior art has the following problems. First, a wafer may be misaligned on or released from the robotic arm  80  by the vent gas as the robotic arm  80  passes over the diffuser  200  in the transfer chamber  20 . This causes a reduction in the production yield. Second, the pressure in the transfer chamber  20  is periodically changed from a low degree of vacuum pressure to a high degree of vacuum pressure. During this time, any fine particles that are present in the transfer chamber  20  enter the vacuum/vent line through the diffuser  70 , and re-enter the transfer chamber  20  when the transfer chamber  20  is vented. As a result, any wafer that is present in the transfer chamber  20  at this time is contaminated.  
       SUMMARY OF THE INVENTION  
       [0016]     Therefore, an object of the present invention is to provide a diffuser, and manufacturing equipment comprising the same, that help maximize the yield of products fabricated in a vacuum atmosphere.  
         [0017]     A more specific object of the present invention is to provide a diffuser capable of preventing a substrate disposed above the diffuser on a robotic arm from being misaligned or released by vent gas supplied through the diffuser. Likewise, an object of the present invention Is to provide manufacturing equipment comprising such a diffuser.  
         [0018]     Another more specific object of the present invention is to provide a diffuser capable of preventing pollutants from entering or exiting a vacuum chamber, such as a transfer chamber, via a vacuum and/or a vent line connected to the vacuum chamber. Similarly, another specific object of the present invention is to provide manufacturing equipment comprising such a diffuser.  
         [0019]     According to one aspect of the present invention, there is provided a diffuser comprising: a tube having a plurality of radial through-holes, a case having a cylindrical support that encloses the tube, is radially spaced apart from the tube by a desired interval, and has a plurality of pores smaller than the holes in the tube in terms of their cross-sectional areas, and at least one filter extending over an inner surface of the case and defining a plurality of micro pores smaller than the pores of the case in terms of their average diameters.  
         [0020]     According to another aspect of the invention, there is provided manufacturing equipment for use in processing a substrate, comprising: a vacuum chamber, and a pressure regulating system connected to the chamber so as to regulate the pressure within the chamber, wherein the pressure regulating system includes a gas flow line extending into the chamber and having a distal end through which gas is forced, and a diffuser as described above disposed within the chamber and connected to the distal end of the gas flow line. In this case, the tube of the diffuser extends in series with the gas flow line.  
         [0021]     According to yet another aspect of the present invention, there is provided equipment for processing a substrate, comprising: a plurality of process chambers in which at least one type of process is carried out on a substrate, a transfer chamber that can be selectively placed in communication with the process chambers by respective doors, a vacuum pump and a vent gas supply source connected to the transfer chamber via vacuum/vent lines to regulate the (vacuum) pressure in the transfer chamber, and a respective diffuser as described above disposed within the transfer chamber and connected to at least one of the vacuum/vent lines. In this case as well, the tube of the diffuser extends in series with the line.  
         [0022]     According to still yet another aspect of the present invention, there is provided equipment for processing a substrate, comprising: a plurality of process chambers in which at least one type of process is carried out on a substrate, a transfer chamber that can be selectively placed in communication with process chambers by respective doors, a vacuum pump and a vent gas supply source connected to the transfer chamber via vacuum/vent lines to regulate the (vacuum pressure) in the transfer chamber, and a respective diffuser disposed in the transfer chamber as connected to at least one of the vacuum/vent lines, wherein the diffuser includes a filter.  
         [0023]     The filter of the diffuser according to the present invention preferably preferably comprises a film of aluminum oxide. Also, the filter preferably has a first layer whose pores have an average diameter of substantially 0.2 μm, 0.5 μm, or 0.8 μm, and a second layer whose pores have an average diameter of substantially 1 μm. Also, the first layer of the filter preferably has a thickness of about 20 μm. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]     The above and other features and advantages of the present invention will become more apparent to those of ordinary skill in the art from the following detailed description of the preferred embodiments thereof made with reference to the attached drawings in which:  
         [0025]      FIG. 1  is a top schematic view of conventional semiconductor device manufacturing equipment having a multi-chamber structure;  
         [0026]      FIG. 2  is a cross-sectional view of a diffuser of the prior art;  
         [0027]      FIG. 3  is a top schematic view of semiconductor device manufacturing equipment according to the present invention;  
         [0028]      FIG. 4  is a cross-sectional view of a transfer chamber, vacuum system and venting system of the semiconductor device manufacturing equipment shown in  FIG. 3 ; and  
         [0029]      FIG. 5  is a cross-sectional view of a diffuser of the semiconductor device manufacturing equipment according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0030]     The present invention will now be described more fully hereinafter with reference to  FIGS. 3-5 .  
         [0031]     The semiconductor device manufacturing equipment according to the present invention includes a plurality of process chambers  110  in which at least one type of semiconductor device fabrication process, such as an etching or deposition process, is carried out, a transfer chamber  120  to which the process chambers  110  are connected, a robotic arm  180  disposed in the transfer chamber for transferring wafers to and from predetermined positions in the equipment, doors  170  that can be opened and closed to selectively place the process chambers  110  in communication with the transfer chamber, and a pressure regulating system for regulating the pressure in the transfer chamber  120 .  
         [0032]     The pressure regulating system includes both a vacuum system for evacuating the transfer chamber  120 , and a venting system for increasing the pressure within the transfer chamber  120 . The vacuum system includes a vacuum line  121  terminating at the bottom of the transfer chamber  120 , a vacuum pump  123  connecting to the transfer chamber  120  via the vacuum line, and a diffuser  190   a  protruding into the transfer chamber  120  at a distal end of the vacuum line  121 . The venting system includes a vent line  122  terminating at the bottom of the transfer chamber  120 , a vent gas supply source  124  connected to the transfer chamber  120  via the vent line  121 , and a diffuser  190   b  protruding into the transfer chamber  120  at a distal end of the vent line  122 , the diffusers  190   a ,  190   b  serve to attenuate the pressure of vent gas and exhaust gas and filter pollutants contained in the vent gas and the exhaust gas.  
         [0033]     The semiconductor manufacturing equipment may also include load lock chambers  30  connected to the transfer chamber  120  and through which wafers are introduced into and unloaded from the equipment, an aligning chamber  140  disposed adjacent a load lock chamber  130  for aligning the wafers before the wafers are processed in a process chamber  110 , a cooling chamber  150  for cooling the wafers processed in the process chambers  110 , and cleaning chambers  160  for ashing or cleaning wafers that have been processed in the process chambers  110 . Also, the semiconductor manufacturing equipment includes a pressure sensor (not shown) for measuring the degree of vacuum in the transfer chamber  120 , and a controller (not shown) for controlling the doors  170  and various valves provided in the vacuum/vent lines  121  and  122  in accordance with signals output from the pressure sensor.  
         [0034]     The robotic arm  180  unloads the wafers one-by-one from a wafer cassette disposed in a load lock chamber  130  and transfers them to desired positions under the command of the controller. One portion or end of the robotic arm  180  is rotatably supported at the center of the transfer chamber  120 , and one or more wafer supports, e.g., wafer chucks, are connected to other end or portions of the robotic arm  180 . Each wafer support  182  is configured to support a wafer and hold the wafer steady during its transfer. The robotic arm  180  has a working envelope that encompasses the various chambers so that it may loading or unload a wafer into or from the chamber that is communicating with the transfer chamber  120 .  
         [0035]     The pressure in the transfer chamber  120  is maintained at almost atmospheric pressure when the wafer is loaded into or unloaded from a wafer cassette disposed in a load lock chamber  130 . On the other hand, a low vacuum state is maintained in the transfer chamber  120  when the wafer is loaded from the transfer chamber  120  into a process chamber  110  in which a high vacuum state exists.  
         [0036]     Specifically, the transfer chamber  120  is evacuated by the vacuum pump  123  via the diffuser  190   a  connected to vacuum line  121 . The diffuser  190   a  is located at the bottom of the transfer chamber  120  between a load lock chamber  130  and the aligning chamber  140 . Agate valve  126  is disposed in the vacuum line  121  for regulating the amount of gas or air exhausted from the transfer chamber  120  according to a control signal output from the controller. However, once the degree of vacuum in the transfer chamber  120  becomes higher than that in a process chamber  110  into which a wafer is to be transferred (or from which the wafer is to be transferred), the transfer chamber  120  is supplied with a vent gas via the diffuser  190   b.  The diffuser  190   b  is located at the bottom of the transfer chamber  120  between a load lock chamber  130  and the cooling chamber  150 .  
         [0037]     The venting system can supply a constant amount of gas into the transfer chamber  120  to increase the pressure in the transfer chamber from a low vacuum pressure to atmospheric pressure. Also, the vent line  122  has a slow venting section  125  configured as a bypass in the vent line  122 . A minute amount of vent gas is allowed into the transfer chamber  120  through the slow venting (bypass) section  125  of the vent line  122  while the transfer chamber  120  is in a low vacuum pressure state (for example, about 1.0 E −2  Torr). To this end, a plurality of valves  127  controlled by the controller are disposed in the main section and the slow venting (bypass) section  125  of the vent line  122  so as to selectively supply the vent gas to the transfer chamber  120  through the main section and slow venting (bypass) section. Also, a pressure reducing device  128  such as a throttle valve or automatic pressure regulating valve is disposed in the slow venting (bypass) section  125 .  
         [0038]     The diffusers  190   a ,  190   b  according to the present invention each include a filter  193  capable of reducing the pressure of the gas flowing through the diffuser. Accordingly, when a wafer is positioned above the diffuser  190   b  in the transfer chamber  120  by the robotic arm  180 , the vent gas issuing from the diffuser  190   b  will not cause the wafer to be released from the wafer support  182  or to become misaligned on the wafer support  182 .  
         [0039]     As shown in  FIG. 5 , the diffusers  190   a  and  190   b  each include a tube  191  connected to the respective vacuum/vent line  121  and  122  with a pipe fitting, a case  192  in which the tube  191  is enclosed as spaced therefrom, and a filter  193  interposed between the case  192  and the tube  191 . The tube  191  has a plurality of holes through which gas can flow. The case  192  has a plurality of pores smaller than the holes in the tube  191  in terms of their cross-sectional areas. The filter  193 , on the other hand, has a plurality of micro pores smaller than the pores in the case  192 .  
         [0040]     The case  192  includes a cylindrical support  194  that supports the filter  193  and encloses the tube  191 , a spacer  196  closing both ends of the support  194 , and a respective Teflon® (tetrafluoroethylene) gasket  195  interposed between the spacer  196  and each end of the support  114 . The support  194  is made of ceramics, and the spacer  196  is made of metal. The filter is made of ceramics and preferably, of a film of aluminum oxide (Al 2 O 3 ).  
         [0041]     Also, the filter  193  has micro pores whose diameter (average diameter on the order over microns) is smaller than the (average) diameter of fine particles that can be present in the transfer chamber  120 . For example, the filter  193  may have two layers consisting of a first filter layer  197  having fine pores that are 0.2 μm, 0.5 μm, or 0.8 μm in diameter, and a second filter layer  198  having fine pores of 1 μm in diameter. In this case, the first filter layer  197  has a thickness of about 20 μm, and the second filter layer  198  has a thickness of about 30 μm. The support  194  has a thickness of about 100 μm and pores that are about 15 μm in diameter. Also, the filter  193  may be supported as radially spaced from the tube  191  by a certain interval.  
         [0042]     Thus, the filters  193  prevent pollutants from entering or exiting the vacuum/vent lines  121  and  122  connected to the transfer chamber  120 . Hence, the diffusers  190   a ,  190   b  of the present invention prevent the wafers from being contaminated and thus contribute to maximizing the production yield.  
         [0043]     Finally, the surface of the filter  193  can be been checked after the transfer chamber  120  has been supplied with the vent gas for a predetermined period of time. Specifically, an electron probe micro analyzer can be used to identify the pollutants on the filter  193 . Therefore, the potential source of contamination of the wafers can be determined. For instance, if the pollutants on the surface of the filter  193  of diffuser  190   b  contain Fe or Al, then the various valves in the purge line  122  can be identified as the source of contamination because the valves are typically of materials comprising Fe or Al.  
         [0044]     According to the present invention as described above, the diffuser includes a filter capable of reducing the pressure of the gas passing therethrough. Accordingly, when a wafer being transferred by the robotic arm in the transfer chamber is located above the diffuser connected to the vent line, the wafer will not become misaligned on or released from the wafer support by the venting gas. Also, the filter(s) prevent pollutants from entering or exiting the vacuum/vent lines connected to the transfer chamber. Thus, the diffusers prevent the wafers from being contaminated. Thus, the diffusers of the present invention contribute to maximizing the production yield of the semiconductor devices.  
         [0045]     Finally, although the present invention has been described above with respect to the preferred embodiments thereof, it will be understood that the scope of the invention is not so limited. Rather, the invention includes various modifications and alternative arrangements of the preferred embodiments as will be apparent to persons skilled in the art. Accordingly, the true spirit and scope of the invention is not limited to the preferred embodiments but by the scope of the appended claims.