JP6631383B2 - Heater having gas supply piping structure - Google Patents

Description

  The present invention relates to a heater for mounting and heating an object to be heated such as a semiconductor wafer, and more particularly to a wafer heater having a gas supply piping structure for a semiconductor manufacturing apparatus.

  2. Description of the Related Art In a semiconductor manufacturing apparatus that manufactures a semiconductor device such as an LSI, various thin film processes such as a film forming process typified by CVD and sputtering and an etching process are performed on a semiconductor wafer to be processed. These thin-film processes often process semiconductor wafers in a heated state, and a wafer heater, also called a susceptor, in which a semiconductor wafer is placed and heated from the lower surface during the thin-film process in a chamber where the process is performed. Is generally installed.

  The wafer heating heater includes, for example, a wafer mounting table formed of a ceramic disk-shaped member having a flat wafer mounting surface on an upper surface as shown in Patent Document 1, and a cylindrical support for supporting the wafer mounting table from the lower surface side. The semiconductor wafer is heated by a resistance heating element buried inside the wafer mounting table. A high frequency (RF) electrode for generating plasma or an electrostatic chuck (ESC) electrode for electrically attracting and fixing a semiconductor wafer to a wafer mounting surface may be further provided inside the wafer mounting table.

  In the above-described wafer heater, in order to suppress a variation in quality of a semiconductor device as a product, it is required to uniformly heat the semiconductor wafer over the entire surface by increasing the uniformity of the wafer mounting surface. For this reason, the circuit pattern of the resistive heating element embedded in the wafer mounting table is made dense so that temperature unevenness does not occur. Techniques for controlling temperature have been proposed.

JP 2003-17224A

  In the above-described semiconductor manufacturing apparatus, a highly corrosive gas such as a halogen-based gas is used as a reactive gas used for CVD, etching, and the like, so that the terminal portions of the electrodes such as the resistance heating element and the lead wires therefrom are cylindrically supported. The inside of the cylindrical support member is isolated from the corrosive gas atmosphere of the chamber by housing the inside of the member and sealing both ends of the cylindrical support member to the bottom surface of the wafer mounting table and the floor surface of the chamber, respectively. ing.

  However, since the lead wire needs to be connected to a power source or the like outside the chamber through a through hole in the chamber floor, the inside of the cylindrical support member is in an atmospheric pressure atmosphere by the through hole, and therefore, has an oxidizing property. Oxidation of terminals and the like by air is inevitable. For example, when a wafer mounting table is heated to 600 ° C. to perform a CVD process on an object to be processed, a terminal portion attached to a lower surface of the wafer mounting table is exposed to an oxidizing atmosphere at about 600 ° C.

  Therefore, an inert gas such as nitrogen gas is introduced into the inside of the cylindrical support member from the outside of the chamber to make the inside of the cylindrical support member an inert gas atmosphere. However, since the temperature of the inert gas introduced from the outside of the chamber is usually lower than the temperature inside the cylindrical support member, the temperature of the wafer mounting surface is locally lowered by the introduction of the low-temperature inert gas. There was something.

  The present invention has been made in view of such a conventional situation, and the lower surface side of the mounting table without impairing the heat uniformity of the mounting surface of the mounting table for mounting an object to be heated such as a semiconductor wafer. An object of the present invention is to provide a heater capable of preventing oxidation and corrosion of a terminal portion, a lead wire, and the like housed inside a cylindrical support member.

  In order to achieve the above object, a heater according to the present invention includes a mounting table having a mounting surface for an object to be heated on an upper surface, and a tubular support member configured to support the mounting table from below. A flow path for introducing an inert gas into the inside and a flow path for discharging the inside gas are provided inside the cylindrical support portion, and these two flow paths are at least partially , And constitutes a heat exchanger.

  ADVANTAGE OF THE INVENTION According to this invention, oxidation and corrosion of the electrode and the lead wire on the lower surface side of the mounting table can be prevented without impairing the heat uniformity of the mounting surface of the mounting table of the object to be heated.

It is a typical longitudinal section of a semiconductor manufacturing device provided with a heater of one example of the present invention. FIG. 2 is a partial cross-sectional view of a gas supply pipe structure included in the heater of FIG. 1.

  First, embodiments of the present invention will be listed and described. An embodiment of the heater of the present invention is a heater having a mounting table provided with a mounting surface of an object to be heated on an upper surface, and a cylindrical support member for supporting the mounting table from below. A flow path for introducing an inert gas into the inside and a flow path for discharging the inside gas are provided inside the cylindrical support portion, and the two flow paths are at least partially in contact with each other to perform heat exchange. It is characterized by constituting a vessel. This makes it possible to prevent oxidation and corrosion of the terminal portions and the lead wires on the lower surface side of the mounting table without impairing the heat uniformity of the mounting surface of the mounting table for the object to be heated.

  In the above-described embodiment of the heater of the present invention, it is preferable that a portion where the two flow paths at least partially contact each other forms a double piping structure. This makes it possible to easily configure a heat exchanger having a high degree of design freedom.

  In the above-described embodiment of the heater of the present invention, the flow path for introducing the inert gas is an inner flow path of the double pipe structure, and the flow path for discharging the inner gas is formed of the double pipe structure. Preferably it is an outer channel. This makes it possible to reliably supply the inert gas to the terminal portion, the lead wire, and the like on the lower surface side of the mounting table.

  In the above-described embodiment of the heater of the present invention, the flow path for introducing the inert gas is an outer flow path of the double pipe structure, and the flow path for discharging the inner gas is formed of the double pipe structure. It may be an inner channel. This makes it possible to heat the low-temperature inert gas flowing through the outer flow path from both sides by the high-temperature exhaust gas flowing through the inner flow path and the high-temperature atmosphere gas inside the support member.

  In the above-described embodiment of the heater according to the present invention, it is preferable that the respective front end openings of the inner flow path and the outer flow path of the double pipe structure are separated in the flow direction of the inner flow path. Accordingly, it is possible to prevent the inert gas discharged from the opening of the introduction flow path from being discharged from the discharge flow path through a short path without staying inside the support member.

  Next, as a specific example of the heater of the present invention, a heater for a semiconductor wafer and a semiconductor manufacturing apparatus equipped with the heater will be described with reference to FIG. The semiconductor manufacturing apparatus shown in FIG. 1 mainly includes a chamber 1 for performing an etching process, a CVD process, and the like on a semiconductor wafer W, and a wafer heater 2 mounted therein. Comprises a substantially disk-shaped wafer mounting table 21 preferably made of ceramics having a wafer mounting surface 21a on its upper surface, and a substantially cylindrical support member 22 made of preferably ceramics for supporting the wafer mounting table 21 from below. Have. Examples of the ceramic that is a suitable material for the wafer mounting table 21 and the support member 22 include aluminum nitride, silicon nitride, silicon carbide, and aluminum oxide.

  Inside the wafer mounting table 21, a resistance heating element 21b having a predetermined circuit pattern and made of, for example, molybdenum foil or tungsten foil is buried in parallel with the wafer mounting surface 21a, and is connected to both ends thereof. The terminal portion 21 c projects from the lower surface side of the wafer mounting table 21 inside the support member 22. A temperature sensor such as an RF electrode, an ESC electrode, or a thermocouple may be further provided inside the wafer mounting table 21 as necessary. It protrudes from the lower surface or is exposed to the lower surface.

  One end of a lead wire 23 is connected to the terminal portion 21c. The lead wire 23 extends inside the support member 22 to the lower end, and passes through a through hole 1a provided on the bottom surface of the chamber 1. It is drawn out of the chamber 1. Both ends of the support member 22 form outwardly bent flanges, and seal members such as O-rings (not shown) provided on the annular end surfaces thereof and coupling means such as screws and clamps (not shown) penetrating the flanges. And is attached to the bottom surface of the chamber 1 in an airtightly sealed state.

  Inside the support member 22, an introduction flow path 24 for introducing an inert gas as a purge gas from a purge gas supply source (not shown) to the inside of the support member 22, and a discharge flow path 25 for discharging the gas inside the support member 22. Is provided. At least a part of these two flow paths has a double piping structure 26 in which the introduction flow path 24 forms an inner flow path and the discharge flow path 25 forms an outer flow path. The discharge destination of the discharge flow path 25 may be a structure that is opened to the atmosphere outside the chamber 1 as it is, or may be a structure that is opened to the atmosphere outside the chamber 1 via a gas suction means such as a vacuum pump.

  With the above configuration, the function of the heat exchanger can be provided to the double piping structure 26, so that the low-temperature inert gas introduced into the support member 22 flows through the inner flow path while the low-temperature inert gas flows through the inner flow path. It can be heated by hot exhaust gas flowing through the path. As a result, the low-temperature inert gas does not come into contact with the lower surface of the wafer mounting table 21, so that oxidation and corrosion of the terminal portion 21c and the lead wire 23 thereof can be prevented without disturbing the uniformity of the temperature of the wafer mounting surface 21a. it can. Further, since the temperature of the wafer mounting surface 21a can be prevented from being locally lowered, the risk of cracking due to the generation of an excessive cool spot can be reduced.

  Furthermore, the above structure can heat the low-temperature inert gas without consuming external energy or the like, so that the cost can be suppressed, and the structure is extremely simple, so that there is an advantage that the degree of design freedom is high. I have. In addition, since the introduction flow path 24 is an inner flow path, only the inner flow path can be freely extended in the support member 22, so that the terminal section or the lead wire on the lower surface side of the mounting table is surely provided. It becomes possible to supply an inert gas.

  In the heater according to one embodiment of the present invention, the gas flowing inside and outside the double piping structure is reversed, and the introduction flow path 24 is set to the outside flow path, and the discharge flow path 25 is set to the inside flow path. Good. Thereby, the low-temperature inert gas flowing through the outer flow path is heated from both sides by the high-temperature exhaust gas flowing through the inner flow path and the high-temperature atmosphere gas existing inside the support member 22, so that the heating is more effectively performed. It becomes possible to do.

  Further, in the heater according to one specific example of the present invention, the respective front end openings of the inner flow path and the outer flow path of the double pipe structure are separated in the flow direction of the inner flow path as shown in FIG. Is preferred. Thereby, it is possible to prevent the inert gas discharged from the introduction flow path from being immediately discharged from the discharge flow path without substantially staying inside the support member 22. When the opening of the inner flow path is extended to the vicinity of the wafer mounting table 21 and the opening of the outer flow path is separated from the wafer mounting table 21 as shown in FIG. Road 24 is preferred. This is because the inert gas discharged from the introduction flow path 24 can be mixed with the atmospheric gas inside the support member 22 and then brought into contact with the wafer mounting table 21, so that the heat uniformity is further improved.

  The shape of the above-mentioned double piping structure 26 is not limited to a straight pipe shape as shown in FIG. 1, but may be a spiral shape along the inner wall surface of the support member 22 or an axial direction of the support member 22. Various shapes such as a shape that reciprocates a plurality of times can be used. This makes it possible to make the heat transfer area as a heat exchanger a desired size. The size of the double piping structure 26 is not particularly limited as long as heat exchange can be performed under a predetermined inert gas supply amount so as not to disturb the uniformity of the wafer mounting surface 21a. It is preferable to provide a pipe having an inner diameter of about 3.0 to 10.0 mm over a length of about 50 to 100 mm outside the inner pipe having a thickness of about 0.0 to 5.0 mm and a thickness of about 0.5 to 1.0 mm. preferable.

The inert gas is not particularly limited as long as it does not cause a reaction that degrades the constituent materials of the electrodes and the like. Rare gases such as He, Ne, Ar, Kr, Xe, and Rn, and N2 _Two gases or the like can be used. Among these, from the viewpoint of cost N ₂ or Ar is preferred. The inert gas atmosphere inside the support member 22 may be kept in a reduced pressure state, so that heat conduction from the wafer mounting table 21 to the bottom surface of the chamber 1 via the atmosphere inside the support member 22 may be reduced. it can.

  As described above, the heater of the present invention has been described with reference to specific examples. However, the present invention is not limited to the specific examples, and can be implemented in various modes without departing from the gist of the present invention. is there. That is, the technical scope of the present invention covers the claims and equivalents.

  A slurry was prepared by adding 0.5 parts by mass of yttrium oxide as a sintering aid to 99.5 parts by mass of aluminum nitride powder, further adding a binder and an organic solvent, and mixing with a ball mill. The obtained slurry was sprayed by a spray drying method to produce granules, which were press-molded to produce two molded articles having the same shape. These molded bodies were degreased at 700 ° C. in a nitrogen atmosphere, and then sintered at 1850 ° C. in a nitrogen atmosphere to obtain two aluminum nitride sintered bodies. The obtained sintered body was processed into a disk shape having a diameter of 330 mm and a thickness of 8 mm. At this time, the surface roughness was 0.8 μm in Ra, and the flatness was 50 μm.

  Of these two aluminum nitride sintered bodies, a W paste is applied by screen printing to form a resistance heating element on one surface of one of the two sintered bodies so that the line width is all 4 mm. After degreasing at 700 ° C., it was baked at 1830 ° C. in a nitrogen atmosphere. Thus, a resistance heating element having a substantially concentric circuit pattern was formed. Next, an adhesive material containing aluminum nitride as a main component was applied to one surface of the other aluminum nitride sintered body, followed by degreasing. Then, these two aluminum nitride sintered bodies were overlapped and joined so as to cover the resistance heating element. The joint obtained in this way is counterbored on one surface with two holes that reach both ends of the resistance heating element, and W-shaped external terminals are fitted in each hole so as to abut the ends of the resistance heating element. It was inserted.

  One end of an AlN cylindrical support member having an inner diameter of 60 mm, a height of 150 mm, and a thickness of 2 mm, having flanges at both ends, is formed on the surface of the wafer mounting table thus prepared in which the W external terminals are fitted. The parts were hermetically joined. Then, a power supply line was connected to an external terminal protruding from the lower surface of the wafer mounting table inside the support member.

  The wafer mounting table to which one end of the support member was bonded was mounted in a chamber of a CVD apparatus, and the other end of the support member was fixed to the bottom of the chamber in an air-tight manner with an O-ring. Further, as shown in FIG. 1, a double pipe having a structure in which an outer pipe having an inner diameter of 6.0 mm and a thickness of 1.0 mm is provided concentrically on the outer side of an inner pipe having an inner diameter of 3.0 mm and a thickness of 0.5 mm. It was inserted through a through hole at the bottom of the chamber. The outer pipe extends to the center in the axial direction of the support member so that the distal end is opened at that position, and the inner pipe extends to almost the upper end of the support member so that the distal end is in the vicinity of the wafer mounting table. It was made to open. Then, a nitrogen gas supply source is connected so that the inner pipe is used as a purge gas introduction flow path, and an exhaust pump is connected so that the outer pipe is used as a discharge flow path, so that the inside of the support member can be maintained at less than 1 atm. . Thus, a wafer heater according to an example of the present invention was manufactured.

  For comparison, two pipes having substantially the same cross-sectional area and length as the inner flow path as the introduction flow path and the outer flow path as the discharge flow path were not formed in a double pipe structure. A heater according to a comparative example of the present invention was manufactured in the same manner as the heater according to the above embodiment except that the heater was provided inside the support member. Then, for each of the heaters of the example and the comparative example, the wafer mounting table is heated to a predetermined temperature by supplying power to the resistance heating element, and the inside of the support member is purged with nitrogen gas to be mounted. The thermal uniformity of the surface was evaluated.

Specifically, the inside of the chamber was evacuated, and power was supplied to the resistance heating element of the heater to heat the heater to 600 ° C. Then, while evacuating the inside gas of the support member by activating the exhaust pump, nitrogen gas of normal temperature and normal pressure of 100 cm ³ / min was introduced into the introduction flow path. At this time, the temperature distribution on the wafer mounting surface in a steady state before and after the nitrogen gas purge was measured using a 300 mm, 17-point wafer thermometer manufactured by Sensorley. Table 1 shows the temperature difference between the average temperature obtained by arithmetically averaging four points on the circumference of φ100 and the temperature at the center point among the 17 temperatures on the wafer mounting surface obtained by this measurement.

  As can be seen from the above Table 1, the temperature change before and after the nitrogen gas purge was -0.2 ° C in the example, whereas the temperature change before and after the nitrogen gas purge was -9.8 ° C in the comparative example. . Therefore, it was found that better heat uniformity was obtained in the example than in the comparative example even when purging with nitrogen gas. This is because, in the example, the low-temperature inert gas was heat-exchanged with the atmosphere gas in the high-temperature support member and then introduced into the support member, so that the uniformity of the wafer mounting surface was not disturbed. In the comparative example, since the low-temperature inert gas was directly introduced into the supporting member without heat exchange, the wafer mounting table was locally cooled by the inert gas, and in particular, the wafer mounting surface 17 was mounted. It can be considered that the temperature became low locally at the center of the point wafer.

DESCRIPTION OF SYMBOLS 1 Chamber 2 Wafer heater 21 Wafer mounting table 21a Wafer mounting surface 21b Resistance heating element 21c Terminal part 22 Supporting member 23 Lead wire 24 Introducing channel 25 Drain channel 26 Double piping structure W Semiconductor wafer

Claims (4)

A heating heater comprising: a mounting table provided with a mounting surface for an object to be heated on an upper surface; and a cylindrical support member configured to support the mounting table from below. A flow path for introducing a gas into the inside and a flow path for discharging the inside gas are provided, and the two flow paths at least partially contact to constitute a heat exchanger , A heater in which a portion at least partially in contact with a flow path constitutes a double piping structure . The flow path for introducing an inert gas of the double pipe structure is the inner flow path, a flow path for discharging the inner gas is outside flow path of the double pipe structure, according to claim 1 Heater. The flow path for introducing an inert gas of the double pipe structure is the outer flow path, a flow path for discharging the inner gas is inside flow path of the double pipe structure, according to claim 1 Heater. Each of the tip opening of the inner channel and the outer channel of the double pipe structure, are spaced apart in the flow path direction of the inner channel, according to any one of claims 1 to 3 Heater.

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