Patent Publication Number: US-2018045697-A1

Title: Thermal desorption system and method of analyzing a substrate using the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     Korean Patent Application No. 10-2016-0101659, filed on Aug. 10, 2016, in the Korean Intellectual Property Office, and entitled: “Thermal Desorption System and Method of Analyzing A Substrate Using the Same,” is incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Field 
     Embodiments relate to a thermal desorption system and a method of analyzing a substrate using the same. 
     2. Description of the Related Art 
     During semiconductor manufacturing processes, a reaction gas may be adsorbed on a surface of a layer formed on a wafer, thereby causing a failure. A thermal desorption system may desorb the material adsorbed on the wafer surface and analyze the desorbed material. 
     SUMMARY 
     Embodiments are directed to a thermal desorption system and a method of analyzing a substrate using the same. 
     The embodiments may be realized by providing a thermal desorption system including a chamber including a space in which a substrate is heated; a flow compartment within the chamber, the flow compartment providing a separate gas flow space within the chamber; a substrate support that supports the substrate within the flow compartment; a heater that heats the substrate within the flow compartment; and a gas pipe that introduces a carrier gas into the flow compartment and discharges the carrier gas from the flow compartment. 
     The embodiments may be realized by providing a thermal desorption system including a chamber including a lower chamber and an upper chamber, the lower chamber and the upper chamber being engaged with each other to provide a first space; a flow compartment within the chamber to provide a separate second space within the first space; a substrate support that supports the substrate within the flow compartment; a heater that heats the substrate within the flow compartment; and a gas pipe that introduces and discharges a carrier gas into and from the flow compartment. 
     The embodiments may be realized by providing a thermal desorption system including a flow compartment; a substrate support in the flow compartment, a substrate being supportable on the substrate support; a heater in the flow compartment, the substrate being heatable by the heater such that a material is desorbable from a surface of the substrate; a gas pipe in fluid communication with the flow compartment, a carrier gas being introducible into the flow compartment and dischargeable from the flow compartment through the gas pipe; and an analyzer that analyzes gas discharged through the gas pipe for the presence of a material desorbed from a surface of the substrate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features will be apparent to those of skill in the art by describing in detail exemplary embodiments with reference to the attached drawings in which: 
         FIG. 1  illustrates a schematic view of a thermal desorption system in accordance with example embodiments. 
         FIG. 2  illustrates a plan view of a lower chamber of the thermal desorption system in  FIG. 1 . 
         FIG. 3  illustrates a perspective view of the lower chamber in  FIG. 2 . 
         FIG. 4  illustrates a schematic view of an analyzer of the thermal desorption system in  FIG. 1 . 
         FIG. 5  illustrates a flow compartment of the thermal desorption system in  FIG. 1 . 
         FIG. 6  illustrates a cross-sectional view of a portion of the flow compartment in accordance with other example embodiments. 
         FIG. 7  illustrates a plan view of a thermal desorption system in accordance with example embodiments. 
         FIGS. 8 to 10  illustrate views of stages in a method of analyzing a substrate in accordance with example embodiments. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a schematic view of a thermal desorption system in accordance with example embodiments.  FIG. 2  illustrates a plan view of a lower chamber of the thermal desorption system in  FIG. 1 .  FIG. 3  illustrates a perspective view of the lower chamber in  FIG. 2 .  FIG. 4  illustrates a view of an analyzer of the thermal desorption system in  FIG. 1 .  FIG. 5  illustrates a flow compartment of the thermal desorption system in  FIG. 1 .  FIG. 6  illustrates a cross-sectional view of a portion of the flow compartment in accordance with other example embodiments. 
     Referring to  FIGS. 1 to 6 , a thermal desorption system  100  may include a chamber having a lower chamber  110  and an upper chamber  120  clamped together to form a first space S 1  where a substrate, e.g., a wafer W, may be heated, a flow compartment  200  within the chamber to provide a second space S 2  within the first space S 1  and separate from the first space S 1 , a substrate support  130  within the flow compartment  200  to support the substrate, a heater to heat the substrate within the flow compartment  200 , and a gas pipe to introduce and discharge a carrier gas into and from the flow compartment  200 . 
     In an implementation, the thermal desorption system  100  may be a gas analyzer that heats the substrate (e.g., the wafer W) to desorb (e.g., remove) an adsorbed material from a surface of the substrate and analyze the desorbed material. For example, the thermal desorption system  100  may thermally desorb a material on a surface of the wafer W or in a layer on the wafer W (which may be formed on the wafer W by a semiconductor process such as a thin layer deposition process, an etch process, or the like), and may perform quantitative and qualitative analysis in real time. 
     As illustrated in  FIG. 1 , the lower chamber  110  may include a bottom wall  112  and a first sidewall  114  defining a first inner space. In an implementation, when viewed in a plan view, the first sidewall  114  may have a cylindrical shape. In an implementation, the first sidewall  114  may have a polygonal shape. The upper chamber  120  may include a top wall  122  and a second sidewall  124  defining a second inner space. In an implementation, when viewed in the plan view, the second sidewall  124  may have a cylindrical shape corresponding to the first sidewall  114 . In an implementation, the second sidewall  124  may have a polygonal shape. A plating layer may be formed on surfaces of the lower chamber  110  and the upper chamber  120 . For example, the chamber may include a metal such as aluminum (Al), and the plating layer may include a metal such as gold (Au). 
     The first sidewall  114  may have an upper edge  116 , and the second sidewall  124  may have a lower edge corresponding to the upper edge  116 . The lower chamber  110  and the upper chamber  120  may be engaged with each other to form the airtight, e.g., isolated, space S 1  therebetween. A sealing member, e.g., an O-ring  118 , may be provided in or on at least one of engagement surfaces of the upper edge  116  and the lower edge. 
     The lower chamber  110  and the upper chamber  120  may be movable relative to each other. For example, the upper chamber  120  may be supported and may be movable along a vertical rail extending in a vertical direction by a linear motor. The upper chamber  120  may move upwardly by the linear motor to open the chamber and may move downwardly to engage with the lower chamber  110  to close the chamber. In an implementation, the upper chamber  120  may move to open or close the chamber through a connection linkage connected to the lower chamber  110 . 
     The heater  130  may be on or in the bottom wall  112  of the lower chamber  110 . For example, the heater  130  may include a heating plate on the bottom wall of the lower chamber  110 . In an implementation, the heater  130  may include a heater coil, a heater lamp, etc. 
     The heater  130  may be under the substrate to heat the substrate. For example, the heater  130  may heat the substrate to a temperature of, e.g., about 600° C. to about 900° C. 
     In an implementation, the thermal desorption system  100  may further include a coolant circulator to circulate a coolant through a coolant line  142 ,  146 . The coolant circulator may include, e.g., a first coolant supplier  140  and/or a second coolant supplier  144 . The first coolant supplier  140  may circulate a coolant through the first coolant line  142  in the upper chamber  120  to cool the upper chamber  120 . The second coolant supplier  144  may circulate a coolant through the second coolant line  146  in the lower chamber  110  to cool the lower chamber  110 . 
     The coolant circulator may help maintain the chamber below a room or ambient temperature (e.g., about 30° C.), and may help prevent the O-ring  118  from melting at a high temperature. 
     In an implementation, the flow compartment  200  may be disposed within the chamber to provide the second space S 2  as a separate gas flow space within the chamber space. For example, the flow compartment  200  may be within the lower chamber  110 . The flow compartment  200  may be on the heater  130  on the bottom wall of the lower chamber  110 . The flow compartment  200  may be spaced apart from an inner upper surface  128  of the chamber by a predetermined distance L. 
     For example, the flow compartment  200  may include a lower wall  202  on the bottom wall of the lower chamber  110 , a plurality of sidewalls  204  extending in a vertical direction on the lower wall  202 , and an upper wall  206  on the sidewalls  204 . In an implementation, the flow compartment  200  may have, e.g., a polygonal shape such as rectangle, when viewed in a plan view. In an implementation, the flow compartment  200  may have, e.g., a cylindrical shape. The upper wall  206  may be movable to selectively cover the sidewalls  204  such that the upper wall  206  selectively opens and closes the flow compartment  200 . Accordingly, when the upper wall  206  opens the flow compartment  200 , the wafer W may be loaded into the flow compartment  200  and then, the flow compartment  200  may be closed and a thermal desorption process may be performed within the flow compartment  200 . 
     The upper wall  206  of the flow compartment  200  may be spaced from the upper surface  128  of the chamber by a first distance, and the sidewall  204  of the flow compartment  200  may be spaced from an inner surface of the first sidewall  114  of the lower chamber  110  by a second distance. The first distance may be greater than the second distance. In an implementation, the sidewall  204  of the flow compartment  200  may contact the inner surface of the first sidewall  114  of the lower chamber  110 . 
     The flow compartment  200  may include a nonmetallic inorganic material. Examples of the nonmetallic inorganic material may include ceramic, quartz, or the like. In an implementation, the flow compartment  200  may include a material having a high thermal conductivity. 
     The second space S 2  of the flow compartment  200  may be separate or isolated from the first space S 1  of the chamber. In an implementation, a flow of a gas in the second space S 2  may be blocked from entering or otherwise interacting with the first space S 1 . In an implementation, through-holes (for allowing a gas flow) may be formed in a lower portion of the sidewall  204  of the flow compartment  200  to communicate or open the second space S 2  with the first space S 1 , so that the chamber and the flow compartment may have a same pressure. 
     The substrate support may include a plurality of support pins  300  supporting the substrate. The support pins  300  may extend upwardly from the lower wall  202  of the flow compartment  200  to contact and support the wafer W. Accordingly, the wafer W may be supported within the flow compartment  200  by the substrate support, and the heater may heat the wafer W to a desired temperature. 
     The gas pipe may include a plurality of carrier gas pipes for introducing and draining a carrier gas into and from the flow compartment  200 . For example, the gas pipe may include a carrier gas inlet pipe  152  and a carrier gas outlet pipe  154  in, e.g., both, sidewalls  204  of the flow compartment  200  opposite to each other. For example, the carrier gas inlet pipe  152  may be arranged opposite to the carrier gas outlet pipe  154  in the flow compartment  200 . 
     In an implementation, the thermal desorption system  100  may further include a gas supplier  150  to supply the carrier gas (e.g., nitrogen (N 2 ) gas) of or at a high temperature through the carrier gas inlet pipe  152 . In an implementation, the thermal desorption system  100  may further include an analyzer  160  to detect a gas discharged through the carrier gas outlet pipe  162  to analyze a material absorbed on the surface of the substrate. For example, the analyzer  160  may analyze the discharged gas to determine the presence of material that had been absorbed on the surface of the substrate (and now removed by the carrier gas). 
     The gas supplier  150  may be connected to the carrier gas inlet pipe  152  through a first valve  153 . The gas supplier  150  may supply the carrier gas into the flow compartment  200  within the chamber through the carrier gas inlet pipe  152 . In an implementation, a mass flow controller (MFC) may be installed in the carrier gas inlet pipe  152  to control a flow of the carrier gas. In an implementation, the gas supplier  150  may supply the carrier gas into the first space S 1  of the chamber and the second space S 2  of the flow compartment  200  through an extra carrier gas inlet pipe. 
     The flow compartment  200  may provide the second space S 2  as the separate gas flow space within the chamber space S 1 . The carrier gas introduced into the flow compartment  200  through the carrier gas inlet pipe  152  may flow through the space S 2  over the substrate within the flow compartment  200 , and then, may be discharged with a material thermally desorbed from the surface of the substrate into the analyzer  160  through the carrier gas outlet pipe  162 . 
     The analyzer  160  may include at least one of a first analyzer  161 A for performing quantitative analysis and a second analyzer  161 B for performing qualitative analysis. As illustrated in  FIG. 4 , the analyzer  160  may include both the first analyzer  161 A and the second analyzer  161 B. The carrier gas outlet pipe  162  may be connected to a first outlet line  164  and a second outlet line  166  through a first control valve  163 . The first analyzer  161 A may be connected to the first outlet line  164 , and the second analyzer  161 B may be connected to the second outlet line  166 . A second control valve  165  may be installed in the first outlet line  164 , and a third control valve  167  may be installed in the second outlet line  166 . A flow of the gas into the first and second analyzers  161 A and  161 B may be controlled by the first to third control valves  163 ,  165 , and  167 . 
     The first analyzer  161 A may be an analyzer using, e.g., atmospheric pressure ionization (API) mass spectrometry, integrated cavity output spectroscopy (ICOS, for example, OA-ICOS), etc. The second analyzer  161 B may be, e.g., a residual gas analyzer (RGA). 
     In an implementation, the thermal desorption system  100  may further include an exhaust to reduce a pressure of the chamber. The exhaust may include, e.g., an exhaust line  172  and a vacuum pump  170  connected to the exhaust line  172 . The exhaust line  172  may be connected to the carrier gas inlet pipe  152  through first valve  153 . The vacuum pump  170  may selectively create a vacuum within the first space S 1  of the chamber and the second space S 2  within the flow compartment  200  through the exhaust line  172  and the carrier gas inlet pipe  152 . 
     In an implementation, the vacuum pump  170  may selectively create a vacuum within the first space S 1  of the chamber and the second space S 2  within the flow compartment  200  through an extra exhaust line. 
     The exhaust may include an electromagnetic valve installed in the exhaust line  172 . A controller may open and close the electromagnetic valve, and operate the vacuum pump. Accordingly, the exhaust may discharge the gas within the chamber and the flow compartment  200  to the outside. 
     The thermal desorption system  100  may further include a temperature sensor to detect a temperature of the substrate or the chamber. For example, the temperature sensor may include a thermocouple  400  positioned within the flow compartment  200  to detect a temperature of the substrate. The thermocouple  400  may extend upwardly from the lower wall  202  of the flow compartment  200  to detect a temperature of the substrate. In an implementation, the temperature sensor may further include a second thermocouple positioned in the chamber and configured to a temperature of the chamber. For example, the second thermocouple may protrude from the upper surface  128  of the upper chamber  120  to detect a temperature of the upper chamber  120 . 
     As illustrated in  FIG. 5 , the flow compartment  200  may be disposed on the bottom wall of the lower chamber  110 . The upper wall  206  of the flow compartment  200  (e.g., a plane of a top surface of the upper wall  206 ) may be positioned to be lower than the upper edge  116  of the lower chamber  110  (e.g., a plane of the upper edge  116 ). An upper surface of the upper edge  116  of the lower chamber  110  may be positioned to be higher than an upper surface of the upper wall  206  of the flow compartment  200  by a predetermined height H. 
     As illustrated in  FIG. 6 , in an implementation, the upper wall  206  of the flow compartment  200  may be positioned to be higher than the upper edge  116  of the lower chamber  110 . An upper surface of the upper wall  206  of the flow compartment  200  may be positioned to be higher than an upper surface of the upper edge  116  by a predetermined height. The upper surface of the upper wall  206  of the flow compartment  200  may be spaced apart from the upper surface  128  of the upper chamber  120  by a predetermined distance L. 
     As mentioned above, the thermal desorption system  100  may include the flow compartment  200  in the chamber to provide a separate gas flow space within the chamber, the heater to heat the wafer W loaded into the flow compartment  200  to desorb a material (e.g., a reaction by-product) on or from the surface of the wafer W, and the gas pipe to introduce the carrier gas into the flow compartment  200  and discharge the carrier gas with the desorbed material from the flow compartment  200 . In an implementation, the thermal desorption system  100  may further include an analyzer  170  to analyze the discharged material in real time. In an implementation, the thermal desorption system  100  may perform the thermal desorption process and then may exhaust the gas (or air) within the chamber and the flow compartment  200  to clean the flow compartment  200 . 
     The flow compartment  200  may provide a minimum gas flow space which is separate from the upper space of the chamber. A flow of the desorbed material within the flow compartment may be blocked to the upper space of the chamber, and the desorbed material may be discharged directly through the carrier gas outlet pipe  162  of the gas pipe and then may be analyzed in real time. Accordingly, the desorbed material may be prevented from being condensed due to a temperature difference between the wafer W and the upper space of the chamber, and a time for the adsorbed material to transfer from the wafer W to the analyzer  170  may be reduced to thereby improve efficiency of analysis. 
     In an implementation, the carrier gas may be introduced to the chamber, atmospheric pressure analysis may be performed, and the total amount of the material desorbed from the wafer W may be used to perform quantitative analysis in real time. Further, the thermal desorption system  100  may perform quantitative analysis and qualitative analysis optionally or at the same time. 
       FIG. 7  illustrates a plan view of a thermal desorption system in accordance with example embodiments. The thermal desorption system may be substantially the same as or similar to the thermal desorption system as described with reference to  FIG. 1 , except for a gas pipe. Thus, same reference numerals will be used to refer to the same or like elements and any further repetitive explanation concerning the above elements may be omitted. 
     Referring to  FIG. 7 , a gas pipe of a thermal desorption system  101  may include a first carrier gas inlet pipe  152  to introduce a carrier gas into a second space S 2  of a flow compartment  200  and a second carrier gas inlet pipe  154  to introduce a carrier gas into a first space S 1  of a chamber. 
     A gas supplier  150  may supply the carrier gas into the flow compartment  200  through the first carrier gas inlet pipe  152 . A first valve  153  may be installed in the first carrier gas inlet pipe  152  and a second valve  155  may be installed in the second carrier gas inlet pipe  154 . 
     A vacuum pump  170  may exhaust an air within the flow compartment  200  through a first exhaust line  172  and the first carrier gas inlet pipe  152 . Additionally, the vacuum pump  170  may exhaust an air within the chamber through the first exhaust line  172  and a second exhaust line  174 . 
     In an implementation, the second space S 2  of the flow compartment  200  may be sealed from the first space S 1  of the chamber. Pressures in the first space S 1  of the chamber and the second space S 2  of the flow compartment  200  may be controlled independently to each other. 
     In an implementation, the second space S 2  of the flow compartment  200  may be in communication with the first space S 1  of the chamber. In this case, the gas supplier  150  may supply the carrier gas to the flow compartment  200  and the chamber respectively, and may exhaust the air within the flow compartment  200  and the chamber respectively. 
     Hereinafter, a method of analyzing a contamination material on a substrate using the thermal desorption system in  FIG. 1  will be explained in detail. 
       FIGS. 8 to 10  illustrate views of stages in a method of analyzing a substrate in accordance with example embodiments. 
     Referring to  FIG. 8 , first, a semiconductor process (e.g., a thin layer deposition process, an etch process, or the like) may be performed on a wafer W, and then, the wafer W may be loaded into a chamber of a thermal desorption system in order to analyze a contamination material on the wafer W. 
     An upper chamber  120  may move upwardly to open the chamber, and then, a flow compartment  200  within the chamber may be opened and the wafer W may be transferred onto supporting pins  300  of a substrate support within the flow compartment  200 . Thus, the wafer W may be supported on a heater  130  by the substrate support. 
     After the wafer W is placed on the supporting pins  300 , an upper wall  206  may be disposed on sidewalls  204  of the flow compartment  200 , to form a space as a minimum gas flow path surrounding the wafer W within the chamber. 
     Referring to  FIG. 9 , the upper chamber  120  may move downwardly to engage with a lower chamber  110 , a thermal desorption process may be performed by the heater that heats the wafer W to a desired temperature, and a carrier gas may be introduced into the flow compartment  200  and then may be exhausted from the flow compartment  200  to be analyzed in real time. 
     For example, first, the carrier gas may be supplied to the chamber to maintain the chamber under an atmospheric pressure. A gas supplier  150  may supply the carrier gas into the flow compartment  200  through a carrier gas inlet pipe  152 . The carrier gas may include a nitrogen (N 2 ) gas. Accordingly, the chamber may be maintained under an atmospheric pressure. Before supplying the carrier gas into the chamber, a gas within the chamber may be exhausted to form a vacuum within the chamber. 
     Then, the wafer W may be heated to desorb (e.g., remove) a material from the wafer W. The heater  130  may heat the wafer W to a temperature of, e.g., about 600° C. to about 900° C. In an implementation, a coolant circulator may circulate a coolant through coolant lines  142  and  146  in the chamber to maintain the chamber under room or ambient temperature (e.g., under about 30° C.). In an implementation, the wafer W may be heated to about 900° C., and a temperature of an upper space of the chamber may be heated to about 200° C. For example, a relatively great temperature difference between the wafer W and the upper space of the chamber may be generated. 
     When the wafer W is heated, a carrier gas may be introduced into the flow compartment  200  and may be exhausted with a gas including the material desorbed from the wafer W from the flow compartment  200 . 
     The gas supplier  150  may supply the carrier gas into the flow compartment  200  through the carrier gas inlet pipe  152 . The carrier gas may include a nitrogen (N 2 ) gas of high temperature. The carrier gas may flow through the gas flow space within the flow compartment  200  and then may be exhausted with the gas including the material thermally desorbed from the wafer W from the flow compartment  200  through a carrier gas outlet pipe  162 . Accordingly, the desorbed gas may not move upward to the upper space of the chamber having a relatively low temperature, but rather may be exhausted through the carrier gas outlet pipe  162  to an analyzer  160 . 
     The discharged gas may be analyzed in real time. The analyzer  160  may analyze the discharged gas through the carrier gas outlet pipe  162 . For example, the analyzer  160  may include at least one of a first analyzer  161 A performing quantitative analysis and a second analyzer  161 B performing qualitative analysis. Accordingly, the total amount of the material desorbed from the wafer W may be used to perform quantitative analysis in real time. Additionally, quantitative analysis and qualitative analysis may be performed optionally or at the same time. 
     Referring to  FIG. 10 , after the wafer is unloaded, a gas within the chamber and the flow compartment  200  may be exhausted. 
     In an implementation, after analysis of the wafer W, the wafer W may be unloaded and then, a cleaning process of the chamber may be performed. 
     The heater  130  may heat the flow compartment  200  and the chamber to a desired temperature to desorb a material adsorbed within the flow compartment  200  and the chamber, and a vacuum pump  170  may exhaust the gas within the flow compartment  200  an the chamber through the first carrier gas inlet pipe  152 . Thus, a remaining material within the flow compartment  200  may be removed completely, thereby improving efficiency of following or subsequent analyses. 
     The above thermal desorption system and the substrate analyzing method may be used to manufacture a semiconductor device such as a logic device or a memory device. For example, the semiconductor device may include logic devices such as central processing units (CPUs), main processing units (MPUs), application processors (APs), etc., volatile memory devices such as DRAM devices, SRAM devices, etc., or non-volatile memory devices such as flash memory devices, PRAM devices, MRAM devices, RRAM devices, etc. 
     By way of summation and review, a vacuum-based analysis method may be adapted in a thermal desorption system, it may be impossible to perform quantitative analysis, and it may be difficult to analyze a total amount of desorbed gas. Further, the desorbed gas may be adsorbed again or condensed within a chamber, and it may be difficult to precisely analyze the material adsorbed on the wafer. 
     The embodiments may provide a thermal desorption system for analyzing a material adsorbed on a wafer surface. 
     The flow compartment may provide a minimum gas flow space which is separate from an upper space of the chamber. The desorbed material may be discharged directly through a carrier gas outlet pipe connected to the flow compartment and then may be analyzed in real time. Accordingly, the desorbed material may be prevented from being condensed due to a temperature difference between the substrate and the upper space of the chamber, and a time for the adsorbed material to transfer from the substrate to the analyzer may be reduced to thereby improve efficiency of analysis. 
     Additionally, the total amount of the material desorbed from the substrate may be used to perform quantitative analysis in real time. Further, quantitative analysis and qualitative analysis may be performed optionally or at the same time. 
     The embodiments may provide a thermal desorption system capable of improving efficiency of analysis. 
     Example embodiments have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. In some instances, as would be apparent to one of ordinary skill in the art as of the filing of the present application, features, characteristics, and/or elements described in connection with a particular embodiment may be used singly or in combination with features, characteristics, and/or elements described in connection with other embodiments unless otherwise specifically indicated. Accordingly, it will be understood by those of skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.