JPH0727797B2 - Ceramics heater - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention is applicable to plasma CVD, low pressure CV.
The present invention relates to a ceramics heater suitably used for D, plasma etching, photoetching equipment and the like.

[0002]

2. Description of the Related Art In semiconductor manufacturing equipment requiring a super clean state, a corrosive gas such as chlorine gas or fluorine gas is used as a deposition gas, an etching gas and a cleaning gas. Therefore, if a conventional heater in which the surface of the resistance heating element is coated with a metal such as stainless steel or Inconel is used as a heating device for heating the wafer in contact with these corrosive gases, these gases are used. The exposure to the above-mentioned causes the generation of undesirable particles such as chlorides, oxides and fluorides having a particle size of several μm.

Therefore, as shown in FIG. 1, an infrared lamp 47 is provided outside the container 26 exposed to the deposition gas or the like.
Infrared transmission window 46 is installed on the outer wall of the container, infrared rays are radiated to the heated object 48 made of a material having good corrosion resistance such as graphite, and the wafer placed on the upper surface of the heated object 48 is heated. Type wafer heating device has been developed. However, compared with the direct heating type, this type has a larger heat loss, it takes longer to raise the temperature, and the transmission of infrared rays is gradually hindered due to the deposition of the CVD film on the infrared transmitting window 46, which causes There is a problem that the transparent window 46 absorbs heat to heat the window.

[0004]

The coil embedded in the ceramic substrate is limited to a heat resistant refractory metal from the viewpoint of the thermal expansion coefficient of the ceramic substrate, the thermal expansion coefficient with respect to the sintering temperature, and the melting point. The coefficient of thermal expansion is 2.8 × 10 ^-6 ° C ^{-1 when} Si ₃ N ₄ is used as the ceramic substrate, and the coefficients of thermal expansion of W, Mo and Pt that can be used as coils are respectively.
4.58 × 10 ^-6 ℃ ^-1 , 5.10 × 10 ^-6 ℃ ^-1 and 10.1 × 10 ^-6 ℃ ^-1 , the sintering temperature of Si ₃ N ₄ is 1850 ℃, the melting points of W, Mo and Pt are respectively 3380 ° C, 2610 ° C and 1769 ° C. When manufacturing a ceramic substrate, taking Si ₃ N ₄ as an example, Si ₃ N ₄
Since the coil is embedded in the compact and sintered at 1850 ° C, it is not possible for the coil to melt or deteriorate at the sintering temperature. Also, the thermal expansion of Pt deviates greatly from Si ₃ N ₄ ,
Moreover, the melting point is as low as 1760 ° C., and W, Mo, and W / Mo alloys are preferable. However, when an insulating film other than a metal film is formed by plasma CVD, thermal CVD, bias ECR plasma CVD, or sputtering, O ₂ and N ₂ are used as the atmosphere gas, and
Raise the temperature of the heater to about 1200 ° C. In that case, in the current method for manufacturing a ceramic heater, after hot press sintering, the surface is ground and the electrode terminal surface of tungsten or the like is carved out. Further, W, Mo coils for thermal expansion deviates from the Si ₃ N _4, a gap between the coil and the Si ₃ N ₄ substrate after sintering. Therefore, refractory metals such as W and Mo are oxidized by O _{2 and the} like, and O ₂ diffuses into the electrode rod connection points on the heater surface and in the gap between the coil and the Si ₃ N ₄ substrate to form tungsten oxide and molybdenum oxide. However, the heater deteriorates. Therefore, there is a drawback that it does not function as a heater.

SUMMARY OF THE INVENTION An object of the present invention is to prevent contamination in the apparatus and reduction of thermal efficiency in an apparatus using high temperature and oxidative corrosive gas such as a semiconductor manufacturing apparatus, and moreover, a terminal of a resistance heating element and an electrode member. It is an object of the present invention to provide a ceramics heater having excellent durability and reliability at the joint portion with.

The present invention provides a ceramic base, a resistance heating element embedded in the ceramic base, a terminal provided at an end of the resistance heating element and exposed to the surface of the ceramic base, and the terminal. And a heat-resistant metal plate which is provided on the surface of the ceramic substrate and is joined to the terminals and the ceramic substrate by a braze containing a titanium component, and an electrode member mechanically coupled to the heat-resistant metal plate. Is a ceramics heater. Usually, a heat-resistant metal plate such as Kovar which is not easily oxidized is brazed to the surface of the terminal, a female screw is cut on the surface of the heat-resistant metal plate, and an electrode rod made of stainless steel having a male screw is mechanically fixed.

As the heat-resistant metal plate, Kovar, 43Ni-F
e, Pt, Cu, 26Cr-Fe, Dumet, Al, Ni. The atmospheric operating temperatures of these are 600 ℃, 600 ℃ and 14 ℃, respectively.
They are 00 ℃, 150 ℃, 1000 ℃, 150 ℃, 400 ℃ and 600 ℃. The melting point of the wax containing the titanium component is, for example, 880 when a ceramic heater is applied to semiconductor manufacturing equipment.
It is preferable that the temperature is not lower than ° C. In this respect, titanium-deposited gold solder and titanium-deposited silver solder are preferable. As an attempt to contain such a titanium component, there is Japanese Patent Publication No. 2-23500 filed by the present applicant.

[0008]

In the case of the conventional stainless steel heater, the heating surface of the semiconductor wafer and the terminal of the resistance heating element are largely separated from each other, and the terminal and the external electrode cable are connected outside the container of the semiconductor manufacturing apparatus. On the other hand, in the ceramics heater of the present invention, the periphery of the terminal is exposed to a high temperature and a corrosive atmosphere, but the melting point of the above-mentioned braze containing titanium component is higher than the surface temperature of the heater, and the mechanical bond is corroded. The ceramic heater is stable in a conductive atmosphere and has sufficient bond strength and conductivity even after being exposed to a heat change, so that a ceramic heater having excellent durability and reliability can be obtained. Also,
In general gold solder and silver solder, metal such as Kovar and the terminals W and Mo of the heater show good bonding properties, but there is no bonding force with the silicon nitride serving as the heater substrate. For this reason, not only the bonding strength of the terminals was insufficient, but also a gap through which gas could pass was formed at the interface of the heater substrate, and sufficient atmospheric gas tight resistance could not be obtained. On the other hand, in the ceramic heater of the present invention, when Ti is mixed in the brazing filler metal, Ti diffuses into Si ₃ N ₄ etc., and the bonding of 14.7 kgf / mm ² as described in Japanese Patent Publication No. 2-23500. A strong and strong gas-tight bonding interface can be obtained.

[0009]

EXAMPLES The present invention will now be described in more detail with reference to examples. FIG. 2 is a sectional view showing a state in which the ceramics heater is attached to the thermal CVD apparatus, and FIG. 3 is an enlarged sectional view showing a joint portion between the heat-resistant metal plate 5 and the electrode member 4. In FIG. 2, reference numeral 26 is a container used for CVD for semiconductor manufacturing, 60 is a disk-shaped ceramics heater for heating the wafer, which is attached to the case 6 inside the container, and the size of the wafer heating surface 30 is 4-8. The size of the wafer is set so that it can be installed in inches.

Inside the container 26, thermal CVD is performed from the gas supply hole 19.
Gas is supplied, and the air inside is exhausted from the suction hole 20 by a vacuum pump. Disc-shaped ceramic heater 60
Is a tungsten-based resistance heating element 2 inside a dense, gas-tight disk-shaped ceramic substrate 1 such as silicon nitride.
Is embedded in a spiral shape, and electric power is supplied from the outside through the electrode members 4 at the center and end portions thereof, so that the disk-shaped ceramic heater 60 can be heated to, for example, about 1100 ° C. 16 is a water cooling jacket that covers the upper surface of the case 6
It is a flange with 18, and the O-ring 10 seals between the side wall of the container 26 and the ceiling surface of the container 26. Reference numeral 7 denotes a hollow sheath which is inserted into the inside of the container 26 by penetrating the wall surface of the flange 16 of the container 26, and is joined to the ceramic heater 60. A thermocouple 8 with a stainless sheath is inserted inside the hollow sheath 7. There is an O between the hollow sheath 7 and the flange 16 of the container 26.
A ring is provided to prevent outside air from entering.

The terminal 3 of the resistance heating element 2 is exposed to the rear surface 36 of the heater, and the heat-resistant metal plate 5 is provided between the terminal 3 and the electrode member 4.
Is intervening. The heat-resistant metal plate 5 is separately manufactured in advance and is formed in a washer shape as shown in FIG.
In order to mechanically connect this to the electrode member 4, a thread groove 5a is provided by, for example, thread cutting or the like, and the thread groove 4a of the protruding portion provided on the lower portion of the electrode member 4 is screwed. Heat-resistant metal plate 5,
The titanium substrate is hermetically bonded to the ceramic substrate 1 and the terminal 3 by titanium vapor deposition solder.

The upper surface of the terminal 3 does not necessarily have to be flush with the upper surface of the ceramic substrate 1, and the upper surface is slightly lower than the upper surface of the ceramic substrate as shown in FIG. With this arrangement, the heat-resistant metal plate 5 can be easily aligned, and in combination with the sealing and bonding action of the braze containing the titanium component, the invasion of outside air into the terminal 3 can be prevented more reliably. Further, the heat-resistant metal plate 5 can be provided with deeper holes to firmly fix the electrode member 4.

According to the ceramics heater of this embodiment, it is possible to solve the problems such as the contamination as in the case of the conventional metal heater and the deterioration of the thermal efficiency as in the case of the indirect heating method. The case 6 is made of graphite or the like, and corrosive gas is inevitably mixed into the heater back surface 36 side. Moreover, since the ceramic substrate 1 has a disc shape,
The connecting portion between the terminal 3 of the resistance heating element 2 and the electrode member 4 is repeatedly exposed to heating to high temperature and cooling. However, in this respect, in the present invention, since the heat-resistant metal plate 5 is joined between the terminal 3 and the electrode member 4 by titanium vapor deposition brazing, the heat-resistant metal plate 5 and the ceramic substrate 1 are made of Ti in the titanium vapor deposition brazing. The heat-resistant metal plate 5 and the terminal 3 are firmly bonded by diffusion bonding.
Similarly, since it is firmly joined by diffusion bonding of Ti,
It is possible to improve the hermeticity of the joint portion between the terminal 3 and the electrode member 4 due to corrosive gas or heat, prevent deterioration, and improve the durability and reliability of the heater. The material of the disk-shaped ceramic substrate 1 is silicon nitride, sialon,
Aluminum nitride and the like are preferable, and silicon nitride and sialon are more preferable in terms of thermal shock resistance.

As the resistance heating element 2, it is suitable to use tungsten, molybdenum, platinum or the like which has a high melting point and is excellent in adhesion to silicon nitride or the like. It is preferable that the wafer heating surface 30 is a smooth surface. Especially when the wafer is directly set on the wafer heating surface 30, the flatness should be 500 μm or less to prevent the deposition gas from entering the back surface of the wafer. There is. When manufacturing the disc-shaped ceramic heater, the resistance heating element 2 provided with the terminals 3 in advance is embedded in the ceramic molded body, the ceramic molded body is sintered, and the back side of the disc-shaped ceramic substrate 1 thus obtained is The end face of the terminal 3 is exposed to the back face 36 by grinding, and then the heat resistant metal plate 5 is joined to the back face 36 of the ceramic substrate 1 by titanium vapor deposition wax, and then the heat resistant metal plate 5 and the electrode member 4 are mechanically joined. Let

Referring to FIGS. 3 and 4, the thread cutting method is used.
An example of mechanical coupling is shown. For example, an edge made of tungsten
For example, the child 3 has a diameter of 5 mm and a length of 10 mm, and this terminal 3 is compared.
For example, when connecting to the electrode member 4 made of nickel,
On the Kovar plate 5, cut an M3 x 6 mm female screw 5a, and
On the ten electrode member 4, cut an M3 x 5 mm male screw 4a and
A locking connection was made. Tungsten terminals are extremely hard and brittle
Since it cannot be processed with a normal die, the
Female screw on Kovar plate 5 rather than female screw on terminal
The work was extremely easy. Therefore, conventional
The electrical discharge machining performed on the terminal 3 can be omitted.
It was Those mechanically connected in this way are
The upper surface of the gusten terminal 3 and the lower surface of the tungsten electrode member 4
Is in contact with the
Since the titanium vapor deposition brazing alloy is used for joining,
Good electrical conductivity and hermeticity are achieved. Also, sufficient contact surface
Since the product is obtained, no current concentration occurs at the junction. Well
As another mechanical joining method, the Kovar plate 5 has a diameter of 3 mm ×
Drill a 7 mm hole and make a nickel electrode member 4 with a diameter of 3 mm x 6 mm.
Protrusions are provided, and the press-fit pressure is 1000 kgf / cm with a tightening margin of 20 μm. ²Press fit with
went. Room temperature and 800 ℃ in the range of 0 to 50 μm
A strong bond even after 1000 thermal cycles between
It was a state.

In each of the above examples, the shape of the ceramics heater is preferably a disk shape in order to uniformly heat a circular wafer, but other shapes such as a square disk shape,
It may be hexagonal or the like. The present invention can also be applied to a ceramic heater in a plasma etching apparatus, a photo etching apparatus, or the like.

[0017]

EFFECTS OF THE INVENTION By the titanium diffusion bonding action of the wax containing the titanium component, the heat resistant metal plate and the ceramic substrate and the heat resistant metal plate and the terminal can be firmly and airtightly bonded. Further, it is possible to exert high bonding strength up to the melting point of the brazing filler metal in the high temperature oxidizing corrosive gas.
Therefore, the electrode member and the terminal can be reliably used for a long time in the high temperature oxidative and corrosive gas. The conductive action of the brazing material containing titanium can ensure electrical conduction between the electrode member and the terminal. Therefore, it is not necessary to exactly match the length and the end face of the joint between the two. Drilling of a heat-resistant metal plate is much easier than drilling by electrical discharge machining of terminals.

[Brief description of drawings]

FIG. 1 is a schematic transverse sectional view of a conventional indirect heating type wafer heating apparatus.

FIG. 2 is a schematic cross-sectional view of an unpublished wafer heating device according to Applicants' invention.

FIG. 3 is a schematic horizontal cross-sectional view showing an example of a combined structure of a heat resistant metal plate and an electrode terminal rod.

FIG. 4 is a schematic horizontal cross-sectional view showing another example of a coupling structure of a heat resistant metal plate and an electrode terminal rod.

[Explanation of symbols]

 1 Ceramics substrate 2 Resistance heating element 3 Terminal 4 Electrode member 4a Screw thread of electrode member 4 5 Heat-resistant metal plate 5a Screw groove of heat-resistant metal plate 5b Projection of heat-resistant metal plate 5 Thermocouple 16 Flange 26 For semiconductor manufacturing CVD Container 30 Wafer heating surface 36 Ceramic heater 60 back 60 Ceramic heater

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location // C23C 16/46 H01L 21/205

Claims (1)

[Claims] 1. A ceramic base, a resistance heating element embedded in the ceramic base, a terminal provided at an end of the resistance heating element and exposed to the surface of the ceramic base, the terminal and the terminal. A heat-resistant metal plate provided on the surface of the ceramic substrate and joined to the terminals and the ceramic substrate by a braze containing a titanium component,
A ceramic heater comprising: an electrode member mechanically coupled to the heat-resistant metal plate.