JP2915750B2 - Ceramic heater with electrostatic chuck - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic heater with an electrostatic chuck, and more particularly to a ceramic heater with an electrostatic chuck used in a temperature raising / lowering step in a semiconductor process.

[0002]

2. Description of the Related Art Conventionally, a heater wound with a metal wire has been used for heating a semiconductor wafer in a semiconductor device manufacturing process. However, a ceramic integrated heater using a ceramic thin film as a heating element has also been used. It has been proposed (see Japanese Patent Application Laid-Open No. 4-124076). In addition, when heating the semiconductor wafer, an electrostatic chuck is used in a reduced pressure atmosphere to fix the semiconductor wafer on the heater, but the material changes from resin to ceramic as the temperature of the process increases. (See JP-A-52-67353 and JP-A-59-124140). Recently, a ceramic heater with an electrostatic chuck in which these ceramic heaters and a ceramic electrostatic chuck are combined has been proposed. (See Japanese Patent Application Laid-Open No. 4-358074).

[0003]

However, this ceramic heater with an electrostatic chuck uses a sintered body of boron nitride as a base material, which is composed of an electrode for the electrostatic chuck and pyrolytic graphite as a heat generating layer. Since the expansion rates are different, there is a problem that the layer is separated or cracks are generated by thermal stress while the temperature is repeatedly raised and lowered.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a ceramic heater with an electrostatic chuck which solves such disadvantages and problems, and comprises a substrate made of graphite and a substrate made of pyrolytic boron nitride. A buffer layer is provided, an electrode for electrostatic chuck made of pyrolytic graphite and a heating layer made of pyrolytic graphite are provided thereon, and an insulating layer made of pyrolytic boron nitride is further provided thereon ,
The coefficient of linear expansion of the buffer layer depends on the substrate, the electrode, and the heating layer.
Between the linear expansion coefficient of
The coefficient of linear expansion approximates the coefficient of
And the surface in contact with the heating layer
It is characterized in that those allowed.

That is, the inventors of the present invention have conducted various studies on a method of solving the problems of the conventionally known ceramic heater with an electrostatic chuck. As a result, the base material was made of graphite and the pyrolytic boron nitride was formed thereon. When the buffer made of pyrolytic boron nitride is used, the coefficient of linear expansion α ₃ of the buffer made of pyrolytic boron nitride is equal to the coefficient of linear expansion α ₁ of graphite as a base material (4.0 × 10 ⁻⁶ / ° C.) Intermediate value (α ₁ ) of linear expansion coefficient α ₂ (1.2 × 10 ^-6 / ° C) of pyrolytic graphite as electrode for electrostatic chuck and heat generating layer
α ₃ > α ₂ ), and this buffer relaxes the thermal stress between the base material, the electrode for the electrostatic chuck, and the heat generating layer. It has been found that problems such as occurrence will not occur, and this will reduce the cost of maintaining semiconductor manufacturing equipment,
The present invention has been completed by confirming that the maintenance time can be reduced and the semiconductor manufacturing cost can be reduced. This is described in more detail below.

[0006]

The present invention relates to a ceramic heater with an electrostatic chuck, as described above, in which a buffer made of pyrolytic boron nitride is provided on a base material made of graphite, and a buffer made of pyrolytic graphite is formed thereon. It is characterized by providing an electrostatic chuck electrode and a heat generating layer, and further providing an insulating layer made of pyrolytic boron nitride thereon. Even if the process is repeated, there is no problem such as peeling or cracking, so that it has an advantage that it is useful for a semiconductor process or the like.

The ceramic heater with an electrostatic chuck according to the present invention uses a pyrolytic graphite thin film as a heating element. In this method, pyrolytic boron nitride is provided as a buffer on a graphite base material. Furthermore, an electrostatic chuck electrode made of pyrolytic graphite, a heat generating layer, and an insulating layer made of pyrolytic boron nitride are provided thereon by a known method.

However, in the conventionally known ceramic heater with an electrostatic chuck, the linear expansion coefficient α ₁ of the boron nitride sintered body as the base material is −0.6 × 10 ⁻⁶ / ° C. Since the thermal expansion coefficient α ₂ of the pyrolytic graphite as the heat generating layer is 1.2 × 10 ⁻⁶ / ° C., it can be used for heat treatment in a semiconductor process, for example, at 10 ⁻⁵ Torr.
When the temperature was repeatedly raised and lowered between 100 and 1,000 ° C under the pressure of, the layer was peeled off or cracked due to thermal stress after about 30 repetitions.

However, when the buffer made of pyrolytic boron nitride is provided on the graphite base material according to the present invention as described above, the linear expansion coefficient α of the buffer made of pyrolytic boron nitride can be improved. ₃ is 2.6 × 10 ⁻⁶ / ° C., which is the linear expansion coefficient α ₁ (4.0 × 10 ⁻⁶ / ° C.) of the graphite as the base material and the pyrolytic graphite as the electrode for the electrostatic chuck and the heat generating layer Coefficient of linear expansion α
₂ (1.2 × 10 ^-6 / ° C), which reduces the occurrence of layer peeling and cracking due to thermal stress generated when this is repeatedly used for temperature rise and fall in the heat treatment step of a semiconductor process. Advantageously, such disadvantages are avoided. More preferably, the linear expansion coefficient α ₃ of the pyrolytic boron nitride is gradually changed from α ₁ to α ₂ from the inside to the outside by manipulating the reaction conditions.

In this case, the material forming the buffer layer has a coefficient of linear expansion that is an intermediate value between the coefficient of linear expansion of the substrate and the coefficient of linear expansion of the material forming the electrode for the electrostatic chuck and the heat generating layer. However, from the viewpoint of purity, insulating properties and affinity with graphite as a base material, pyrolytic graphite as an electrode for an electrostatic chuck and a heat generating layer, the above pyrolytic boron nitride should be used. Is the most desirable.

[0011]

Next, examples of the present invention and comparative examples will be described. EXAMPLE A base material (linear expansion coefficient: 4.0 × 10 ⁻⁶ / ° C.) on a disk made of graphite having a diameter of 200 mmφ and a thickness of 5 mm was placed in a thermal CVD reactor, and ammonia and boron trichloride were used as raw materials. Thermal decomposition was performed at a reaction temperature of 1,830 ° C. and a pressure of 10 Torr to form a buffer layer made of pyrolytic boron nitride having a thickness of 1 mm on the substrate. The coefficient of linear expansion of this buffer layer was 2.5 × 10 ⁻⁶ / ° C.

Next, these substrates were placed in a thermal CVD reactor, and propane gas was pyrolyzed at a reaction temperature of 1,900 ° C. and a pressure of 5 Torr, and the generated pyrolytic graphite was deposited on the substrate to a thickness of 50 μm. After that, this was formed into an electrode for electrostatic chuck and a heating element for heater by machining, and this was installed again in the thermal CVD reactor, and the reaction temperature was 1,750.
Ammonia and boron trichloride were thermally decomposed at 10 ° C. and a pressure of 10 Torr, and pyrolytic boron nitride was coated thereon to a thickness of 100 μm to form an insulating layer, thereby producing a ceramic heater with an electrostatic chuck.

Next, the ceramic heater with the electrostatic chuck produced in this manner is mounted on the apparatus, and the apparatus is operated at 10 ^-5 Torr.
The temperature was repeatedly raised and lowered between 100 ° C. and 1,000 ° C., and none of them showed any abnormality such as peeling or cracking even when the temperature was repeated 100 times.

A disk-shaped substrate (linear expansion coefficient: 4.0 × 10 ⁻⁶ / ° C.) made of graphite having a diameter of 200 mmφ and a thickness of 5 mm was placed in a thermal CVD reactor, and ammonia and boron trichloride were used as raw materials. At a reaction temperature of 1,850 ° C with a gradient of 10 ° C / hr for 5 hours.
By pyrolysis with orr, a buffer layer made of pyrolytic boron nitride having a thickness of 1 mm was formed on the substrate. The coefficient of linear expansion of this buffer layer is 3.9 × 10 ⁻⁶ / ° C. on the surface in contact with graphite, and decreases continuously toward the outside.
⁻⁶ / ° C. Subsequently, 10 ⁻⁵ To
The temperature was repeatedly increased and decreased between 100 ° C. and 1,000 ° C. under rr, and no abnormalities such as peeling and cracks were observed even after repeating the cycle 100 times.

Comparative Example For comparison, a ceramic heater with an electrostatic chuck was prepared in the same manner as in the example except that a substrate made of a boron nitride sintered body was used. As a result, cracks occurred in the insulating film when the temperature was repeatedly increased and decreased 30 times.

[0016]

The present invention relates to a ceramic heater with an electrostatic chuck, as described above, in which a buffer layer made of pyrolytic boron nitride is provided on a graphite base material, and a pyrolytic boron nitride is formed thereon. An electrode for graphite chuck made of graphite and a heating layer made of pyrolytic graphite are provided, and an insulating layer made of pyrolytic boron nitride is further provided on the heating layer. A buffer layer made of pyrolytic boron nitride is provided on a base material made of pyrolytic boron nitride. The linear expansion coefficient of the buffer layer made of pyrolytic boron nitride is Electrode for electrode for electrostatic chuck made of decomposed graphite and the coefficient of linear expansion of the heating layer are in the middle, so when this is used for heat treatment in semiconductor process, repeated temperature rise and fall Is thermal stress relieving to be more generated, this compound peeled off a number of repeated but the layer of heating and cooling, the one with the advantage that defect is resolved that cracks are generated.

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI H01L 21/324 H01L 21/324 Q H02N 13/00 H02N 13/00 D (56) References JP-A-5-129210 (JP, A) JP-A-4-34953 (JP, A) JP-A-59-124140 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 21/68

Claims (1)

(57) [Claims] A buffer layer made of pyrolytic boron nitride is provided on a graphite base material, and an electrostatic chuck electrode made of pyrolytic graphite and a heating layer made of pyrolytic graphite are provided thereon. An insulating layer made of pyrolytic boron nitride is provided thereon , and the buffer layer has a linear expansion.
The coefficient is the coefficient of linear expansion between the substrate, the electrode and the heat generating layer.
The surface that is gradually changed between and is in contact with the substrate
In this example, the coefficient of linear expansion is approximated,
A ceramic heater with an electrostatic chuck, characterized in that the coefficient of thermal expansion approximates these linear expansion coefficients .