JP4157541B2 - Sample heating apparatus, processing apparatus, and sample processing method using the same - Google Patents

Description

  The present invention relates to a sample heating apparatus for heating to various processing temperatures while holding a sample of a semiconductor wafer or the like in a film forming apparatus such as plasma CVD, low pressure CVD, photo CVD, sputtering, or an etching apparatus such as plasma etching or photo etching. And a processing apparatus using the same.

  Conventionally, in a semiconductor device manufacturing process, in a film forming apparatus such as plasma CVD, low-pressure CVD, photo-CVD, or sputtering, or in an etching apparatus such as plasma etching or photo-etching, a semiconductor wafer that is a sample (hereinafter referred to as a wafer). A sample heating apparatus is used for heating to various processing temperatures while maintaining the temperature.

For example, as shown in FIG. 7 where a conventional sample heating apparatus is installed in a vacuum processing chamber, a vacuum processing 20 includes a gas supply hole 21 for supplying a process gas and an exhaust hole 22 for evacuating. A sample heating device 31 including a ceramic heater 32 and a ceramic cylindrical support 42 is installed in the vacuum processing chamber 20. This type of ceramic heater 32 is composed of a plate-shaped ceramic body 33 having a disk shape and the upper and lower surfaces of which are smooth and flat. A resistance heating element 34 is embedded in the plate-shaped ceramic body 33, and The main surface is a mounting surface 35 of the wafer W, and the other main surface is joined with a power supply terminal 36 electrically connected to the resistance heating element 34. Further, the other main surface of the plate-shaped ceramic member 33, lead ceramic tubular support 42 so as to surround the upper Symbol feed terminal 36 are integrally joined with a glass bonding, is connected to the feed terminal 36 The wire 37 was taken out of the vacuum processing chamber 20 (see Japanese Patent Laid-Open No. 4-78138).

  In order to perform processing such as film formation and etching on the wafer W by the sample heating device 31, first, the vacuum processing chamber 20 is evacuated and the wafer W is mounted on the mounting surface 35 of the ceramic heater 32. Then, the wafer W is heated to a set temperature of 400 ° C. or more by energizing the power supply terminal 36 to cause the resistance heating element 34 to generate heat, and in this state, a process gas such as a deposition gas or an etching gas from the gas supply hole 21. Is introduced into the vacuum processing chamber 20 to perform various processes on the wafer W.

  However, when the sample heater 31 is repeatedly subjected to a heat cycle in the temperature range from room temperature (25 ° C.) to 400 ° C. or more due to the heat generated by the ceramic heater 32, at the joint between the ceramic heater 32 and the ceramic cylindrical support 42. Since the airtightness is impaired, the degree of vacuum in the vacuum processing chamber 20 is lowered, and as a result, there is a problem that the film forming accuracy and the etching accuracy are adversely affected.

That is, since the sample heating device 31 is large in size and complicated in structure, it is difficult to form and fire the ceramic heater 32 and the ceramic cylindrical support 42 as an integrated body. Although they are integrally joined by joining, there are joint interfaces between the ceramic heater 32 and the joint 40 and between the ceramic cylindrical support 42 and the joint 40, respectively, and the ceramic heater 32 and the ceramic cylinder. Since glass having different heat transfer characteristics intervenes between the support members 42, thermal stress tends to concentrate on these joint interfaces, and as a result, cracks occur in the joint 40 due to repeated thermal stress. I couldn't prevent that.

In the film forming apparatus and the etching apparatus, a highly corrosive halogen-based gas is used as a deposition gas, an etching gas, or a cleaning gas. When exposed to a halogen-based gas, there is a problem in that corrosion wear tends to occur, airtightness is lost in a short period of time, and wear powder generated by the corrosion wear adversely affects processing accuracy on the wafer W.

  In addition, glass bonding can only be used up to a temperature range of about 400 ° C., and cannot cope with the processing in a temperature range of 600 ° C. or higher, which has been required in recent years.

The present invention has been made in view of the above problems, the one main surface of the ceramic plate formed by embedding a resistance heating element and a mounting surface of the sample, the resistance heating element and electrically connected to the other main surface a ceramic heater having a power supply terminal that is, integrally joined to the other main surface of the upper Symbol ceramic heater in an airtight so as to surround the power supply terminal, a ceramic tubular support for installing the ceramic heater in the vacuum processing chamber in the sample heating apparatus comprising a, of the other main surface of the ceramic heater, is characterized in that the engraved circular groove along the inner periphery of the joint between the ceramic tubular support.

As described above, according to the present invention, one main surface of a plate-like ceramic body in which a resistance heating element is embedded is used as a sample mounting surface, and the other main surface is electrically connected to the resistance heating element. a ceramic heater having a power supply terminal that is, integrally joined hermetically by sintering on the other main surface of the upper Symbol ceramic heater so as to surround the power supply terminal, a ceramic tube for installing the ceramic heater in the vacuum processing chamber in the sample heating apparatus comprising a Jo support, among other main surface of the ceramic heater, since it has engraved the annular groove along an inner peripheral edge of the joint between the ceramic tubular support, a ceramic heater The temperature gradient at the joint between the ceramic cylindrical support and the ceramic cylindrical support can be reduced and the thermal stress acting on the joint can be reduced. Kill is possible to maintain. In addition, the ceramic heater, the joint, and the ceramic cylindrical support exposed in the vacuum processing chamber are all made of ceramics that are dense and have excellent heat resistance, corrosion resistance, and plasma resistance, so that they have a long life, such as wafers. The sample is not adversely affected, and the film formation accuracy and etching accuracy are not deteriorated.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is a sectional view showing a state in which the sample heating apparatus of the present invention is attached to a vacuum processing chamber, FIG. 2 is a perspective view showing only the sample heating apparatus, and FIG. 3 is an exploded view of the sample heating apparatus.

  In FIG. 1, reference numeral 20 denotes a vacuum processing chamber having a gas supply hole 21 for supplying a process gas and an exhaust hole 22 for evacuating, in which a ceramic heater 2 and a ceramic cylindrical support are provided. A sample heating apparatus 1 including a body 12 is installed. As shown in FIG. 2, the ceramic heater 2 is composed of a plate-like ceramic body 3 having a disk shape and smooth upper and lower surfaces. The size of the ceramic heater 2 depends on the size of the wafer W, but has an outer diameter of 150 to 350 mm and a thickness of 8 A thing of about ~ 25 mm can be used. In addition, a resistance heating element 4 made of a metal such as tungsten, molybdenum, or platinum is embedded in the plate-like ceramic body 3, and one main surface is used as a mounting surface 5 for the wafer W and the other main surface. Is joined with a power supply terminal 6 electrically connected to the resistance heating element 4. In the present invention, the main surface is the widest surface of the plate-like ceramic body 3, and the other main surface is the surface opposite to one main surface.

  A temperature detecting means 8 such as a thermocouple is built in the center of the plate-shaped ceramic body 3 so as to detect the temperature of the mounting surface 5.

  A cylindrical ceramic support 12 having a cylindrical shape so as to surround the power supply terminal 6 and the lead wire 9 of the temperature detecting means 8 is hermetically bonded to the other main surface of the plate-like ceramic body 3 by sintering. The lead wires 7 and 9 connected to the power supply terminal 6 and the temperature detecting means 8 are taken out of the vacuum processing chamber 20.

  Here, as the plate-like ceramic body 3 and the ceramic cylindrical support body 12 constituting the ceramic heater 2, it is necessary to be formed of a ceramic that is dense and has excellent heat resistance, corrosion resistance, and plasma resistance. As such ceramics, nitride ceramics mainly composed of silicon nitride, sialon, aluminum nitride, and boron nitride can be used. Among these, ceramics mainly composed of aluminum nitride have a high thermal conductivity compared to other ceramics, so that rapid temperature rise is possible, and against highly corrosive halogen-based gases and plasmas. It is preferable because it is excellent.

  In addition, the plate-like ceramic body 3 and the ceramic cylindrical support 12 need to be formed of ceramics of the same kind (same main components are the same) from the viewpoint of joining and integrating by sintering, and preferably ceramics of the same composition It is good to form by. As a result, the difference in thermal expansion between them can be made extremely small, so that the thermal stress generated at the bonding interface can be greatly reduced, and the occurrence of cracks at the bonding portion 10 can be suppressed.

  In the present invention, joining and integrating by sintering means that the joining portion 10 is also made of a ceramic having the same kind or the same composition as the plate-like ceramic body 3 and the ceramic cylindrical support body 12, and the plate-like ceramic body 3 and the joining portion 10. And the joint part 10 and the ceramic cylindrical support body 12 say that all are sintered. As a method of joining and integrating by sintering, a ceramic paste of the same kind or the same composition as the ceramics constituting the plate-like ceramic body 3 and the ceramic cylindrical support 12 is applied to one of the joining surfaces, and the other is joined to the above-mentioned joining Joined by a hot press method of heating and sintering in a pressed state after being brought into contact with the surface, or applying the ceramic paste to one of the joining surfaces and bringing the other into contact with the joining surface Bonding can be performed by an ultrasonic vibration method in which ultrasonic vibration is applied and sintered in a pressed state.

  Thus, if the plate-like ceramic body 3 and the ceramic cylindrical support 12 are joined and integrated by sintering, the joint 10 and the ceramic cylindrical support 12 are provided between the plate-like ceramic body 3 and the joint 10. Therefore, the thermal stress concentrated on the joint 10 can be greatly reduced. In addition, since the joint 10 is excellent in corrosion resistance and plasma resistance, there is little corrosive wear, and since there is little generation of wear powder, the wafer W is not adversely affected.

  Furthermore, in the sample heating apparatus 1 of the present invention, as shown in FIG. 1 and FIG. 3, the other main surface of the ceramic heater 3, along the outer peripheral edge of the joint portion 10 with the ceramic cylindrical support 12. An annular groove 2a having a ring shape similar to the outer shape of the ceramic cylindrical support 12 is formed, and the surface area near the joint 10 is increased to enhance the cooling effect.

  Therefore, even if a heat cycle is repeatedly applied in the temperature range from room temperature to 400 ° C. or more due to the heat generated by the ceramic heater 2, it is possible to relieve the thermal stress concentrated on the joint 10 and prevent the generation of cracks. Airtightness can be maintained even during use.

  That is, even if the ceramic heater 2 and the ceramic cylindrical support body 12 are joined and integrated by sintering, the ceramic heater 2 and the ceramic cylindrical support body 12 and the ceramic heater 2 and the ceramic cylindrical support body 12 are respectively connected. Even when the ceramic heater 1 and the ceramic cylindrical support 12 are formed of the same kind of ceramics to reduce the difference in thermal expansion due to the presence of these joint interfaces, thermal stress is concentrated due to poor heat transfer. However, in the present invention, the heat dissipation of the joint portion 10 is enhanced by providing the annular groove 2a on the outer peripheral edge of the joint portion 10 in the other main surface of the ceramic heater 2 to increase the surface area. Therefore, even if the thermal stress is concentrated on the joint 10, the magnitude of the thermal stress can be reduced and the generation of cracks can be prevented.

  By the way, in order to obtain such an effect, the dimension of the annular groove 2a, in particular, the depth T is important, and if it is less than 1 mm, the effect of relaxing the thermal stress is small because it is too shallow. Therefore, the depth T of the annular groove 2a is preferably at least 1 mm. For example, the plate-like ceramic body 3 and the ceramic cylindrical support 12 are ceramics mainly composed of aluminum nitride having high thermal conductivity. In this case, the effect of relieving the thermal stress most can be obtained by setting the depth T of the annular groove 2a to 4 to 6 mm. However, when the depth T of the annular groove 2a is larger than ½ mm of the thickness of the plate-like ceramic body 3, the strength of the ceramic heater 2 is greatly reduced and it is difficult to make the temperature distribution of the mounting surface 5 uniform. Therefore, the upper limit is preferably set to ½ mm or less of the thickness of the plate-like ceramic body 3.

  The width L of the annular groove 2a is preferably set in the range of 1 to 25 mm. This is because the width L is too narrow below 1 mm, so even if the depth T of the annular groove 2a is 1 mm or more, heat is trapped in the annular groove 2a, and the effect of relieving thermal stress is small. This is because the temperature distribution on the mounting surface 5 may vary.

  Further, the cross-sectional shape of the annular groove 2a is preferably a curved bottom surface as shown in FIG. 1 from the viewpoint of preventing the occurrence of cracks, and the radius of curvature R1 is preferably in the range of 0.5 to 12.5 mm. . As a method of forming such an annular groove 2a, it can be formed by using a processing method such as grinding, shot blasting or ultrasonic processing.

  FIG. 1 shows an example in which the annular groove 2a is provided along the outer peripheral edge of the joint portion 10 with the ceramic cylindrical support 12 in the other main surface of the ceramic heater 2. FIG. As described above, the annular groove 2a may be provided only along the inner peripheral edge of the joint portion 10 with the ceramic cylindrical support body 12. Further, although not shown, the joint portion 10 with the ceramic cylindrical support body 12 is provided. What provided the annular groove 2a along the outer periphery and the inner periphery may be sufficient respectively.

  Thus, if the sample heating apparatus 1 of the present invention is used to perform processing such as film formation and etching on the wafer W, the ceramic heater 2 and the ceramic cylinder can be applied even if repeated thermal cycles are applied in the temperature range from room temperature to 400 ° C. or higher. Since the temperature distribution of the mounting surface 5 can always be kept uniform without impairing the airtightness at the joint 10 with the cylindrical support 12, highly accurate film formation and etching can be performed stably over a long period of time. be able to.

  Next, another embodiment of the present invention will be described.

  FIG. 5 is a cross-sectional view showing another example of the sample heating apparatus 1 of the present invention, in which a frustoconical convex portion 2 b is formed at the center of the other main surface of the plate-like ceramic body 3 constituting the ceramic heater 2. The cylindrical cylindrical support 12 is airtightly joined and integrated with the convex portion 2b by sintering.

  Thus, the same effect as having increased the surface area of the outer periphery of the junction part 10 by forming the convex part 2b in the center part of the other main surface of the plate-like ceramic body 3 is obtained. Since the heat dissipation of the part 10 can be improved, the thermal stress concentrated on the joint part 10 can be relieved and the generation of cracks can be prevented.

  However, in the case of this structure, when the height Q of the convex portion 2b is less than 1 mm, the effect of relaxing the thermal stress is small, and conversely, when the height Q is higher than 10 mm, the thickness of the central portion and the peripheral portion of the plate-like ceramic body 3 are reduced. Therefore, even if the resistance value of the resistance heating element 4 embedded in the plate-like ceramic body 3 is adjusted at the central portion and the peripheral portion, the temperature distribution on the mounting surface 5 is made uniform. Is difficult. Therefore, the height Q of the convex portion 2b is preferably provided in the range of 1 to 10 mm.

  The edge of the other main surface of the plate-shaped ceramic body 3 and the side surface of the convex portion 2b is preferably formed in a smooth curved shape from the viewpoint of preventing the occurrence of cracks, and its radius of curvature R2 is 0.3 mm. The above is preferable.

As described above, FIG. 5 shows an example in which the frustoconical convex portion 2b is formed at the center of the other main surface of the plate-like ceramic body 3. However, as shown in FIG. A ring-shaped convex portion 2b that matches the shape of the joint portion of the ceramic cylindrical support body 12 is formed at the center of the other main surface of the ceramic cylindrical support body 12, and the ceramic cylindrical support body 12 is sintered on the convex portion 2b. Even if the joint is integrated, the airtightness of the joint 10 can be maintained for a long period of time.

  (Embodiment 1) Here, in order to confirm the effect of providing the annular groove 2a along the outer peripheral edge and / or the inner peripheral edge of the joint portion 10 with the ceramic cylindrical support 12, no annular groove 2a is provided. A conventional sample heating device 31 is installed in the vacuum processing chamber 20 and heated until the average temperature of the ceramic heater 32 reaches 800 ° C., and then the temperature of the mounting surface 35 is measured by an infrared radiation thermometer at 10 points. Sample heating with an annular groove 2a provided along the outer peripheral edge of the joint 10 with the ceramic cylindrical support 12 by measuring the distribution and performing simulation analysis using the finite element method based on this temperature distribution The apparatus 1, the sample heating apparatus 1 provided with the annular groove 2a along the inner peripheral edge of the joint 10 with the ceramic cylindrical support 12, and the inner peripheral edge and the outer peripheral edge of the joint 10 with the ceramic cylindrical support 12 Ring groove 2 Are generated at the joints 10 and 40 of the plate-like ceramic bodies 3 and 33 and the ceramic cylindrical supports 12 and 42, respectively, with respect to the sample heating apparatus 1 and the conventional sample heating apparatus 31 without the annular groove 2a. Each thermal stress was analyzed.

  The dimensions of the model are as follows: the plate-like ceramic bodies 3 and 33 have an outer diameter of 300 mm and a thickness of 15 mm, and the ceramic cylindrical supports 12 and 42 have an outer diameter of 50 mm and a wall thickness of 8 mm. The experiments were conducted assuming that the cylindrical supports 12 and 42 are ceramics mainly composed of aluminum nitride having a thermal conductivity of 64 W / mk at 25 ° C. and a thermal conductivity of 32 W / mk at 800 ° C.

  The respective results are as shown in Tables 1 to 3.

  As a result, it can be seen that by providing the annular groove 2a along the inner peripheral edge and / or the outer peripheral edge of the joint portion 10 with the ceramic cylindrical support 12, the thermal stress generated in the joint portion 10 can be greatly relieved. Moreover, it can be seen that the thermal stress tends to decrease as the depth T of the annular groove 2a increases, and that the depth of the annular groove 2a is better.

  Further, it can be seen that the thermal stress can be reduced if the annular groove 2a is provided on the outer peripheral edge rather than the inner peripheral edge of the joint portion 10 with the ceramic cylindrical support body 12.

  Next, in order to confirm the effect when the width L of the annular groove 2a is changed, the depth T of the annular groove 2a is fixed to 4 mm, and the width L of the annular groove 2a is larger than 5 mm as opposed to 2 mm which is smaller than 5 mm. When the thermal stress at 10 mm was analyzed by the finite element method, no change was found in the thermal stress.

From this, it can be seen that the thermal stress acting on the joint 10 is largely caused by the depth T of the annular groove 2a, and the thermal stress can be reduced by providing the annular groove 2a.

  (Example 2) Next, in order to confirm the effect of Example 1, the sample heating apparatus 1 provided with an annular groove 2a having a depth of T1 mm along the outer peripheral edge of the joint 10 with the ceramic cylindrical support 12. And a conventional sample heating device 31 having no annular groove 2a is actually manufactured, and these sample heating devices 1, 31 are installed in the vacuum processing chamber 20, and the ceramic heaters 2, 32 are moved from a normal temperature range (25 ° C.). A heat cycle in which heating and cooling were repeated in a temperature range of 800 ° C. was performed, and an experiment was conducted to confirm the airtightness of the joints 10 and 40 using a He leak detector. The plate-like ceramic bodies 3 and 33 and the ceramic cylindrical supports 12 and 42 constituting the ceramic heaters 2 and 32 both have a thermal conductivity at 25 ° C. of 64 W / mk and a thermal conductivity at 800 ° C. of 32 W. The ceramic heaters 2 and 32 and the ceramic cylindrical supports 12 and 42 having the same dimensions as those of Example 1 were used while being formed of high-purity aluminum nitride ceramics of / mk.

  As a result, in the conventional sample heating apparatus 31 that does not have the annular groove 2a, the joint 40 between the ceramic heater 32 and the ceramic cylindrical support 42 is cracked in about 10 thermal cycles, and the airtightness is lowered. On the other hand, the sample heating apparatus 1 of the present invention provided with the annular groove 2a is sufficiently airtight because no cracks are seen in the joint portion 10 between the ceramic heater 3 and the ceramic cylindrical support 12 even in 600 thermal cycle tests. It was confirmed that it has sex.

It is sectional drawing which shows the state which attached the sample heating apparatus of this invention to the vacuum processing chamber. It is a perspective view which shows only the sample heating apparatus of this invention. It is an exploded view of the sample heating apparatus of this invention. It is sectional drawing which shows the modification of the sample heating apparatus of FIG. It is sectional drawing which shows the other example of the sample heating apparatus of this invention. It is sectional drawing which shows the modification of the sample heating apparatus of FIG. It is sectional drawing which shows the state which attached the conventional sample heating apparatus to the vacuum processing chamber.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,31 ... Sample heating apparatus 2, 32 ... Ceramic heater 2a ... Ring groove 2b ... Convex 3, 33 ... Plate-like ceramic body 4, 34 ... Resistance heating element 5, 35 ... Placement surfaces 6, 36 ... Power supply terminals 7, 9, 37 ... Lead wire 8 ... Temperature detection means 10, 40 ... Junction W ... Wafer

Claims (7)

A ceramic heater having a power supply terminal electrically connected to the resistance heating element on the other main surface side, with one main surface of the plate-shaped ceramic body formed by embedding the resistance heating element as a mounting surface of the sample, in the sample heating apparatus comprising an upper SL is joined to the other main surface of the ceramic heater cylindrical support so as to surround the power supply terminal, of the other main surface of the ceramic heater, the cylindrical support A sample heating apparatus, wherein a groove is formed along the inner peripheral edge of the joint portion. The sample heating apparatus according to claim 1, wherein a bottom surface of the groove is curved. The sample heating apparatus according to claim 1 or 2 , wherein a depth of the groove is 1/2 or less of a thickness of the plate-like ceramic body. The said cylindrical support body consists of ceramics, The sample heating apparatus as described in any one of Claims 1-3 characterized by the above-mentioned. The sample heating apparatus according to any one of claims 1 to 4 , wherein the plate-like ceramic body and the cylindrical support are formed of the same kind of ceramics and bonded and integrated by sintering. . It is a processing apparatus provided with the sample heating apparatus as described in any one of Claims 1-5 , Comprising: At least the said ceramic heater is installed in a processing chamber, and a sample is mounted in one main surface of the said ceramic heater. A processing apparatus characterized in that the sample is subjected to film formation or etching by heating together with the process gas and introducing a process gas into the processing chamber. A step of evacuating a processing chamber in which the sample heating apparatus according to any one of claims 1 to 6 is evacuated, and a sample is mounted on a mounting surface of the sample heating apparatus installed in the processing chamber. A sample processing method comprising: a step, a step of heating a sample heating device to a temperature of 400 ° C. or higher; and a process gas is introduced into the processing chamber to perform film formation or etching on the sample.

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