JPH08153603A - Ceramic resistor - Google Patents

Abstract

PURPOSE: To adjust the volumetric specific resistance in the specific range and to stabilize in a wide temperature range by a method wherein the element of twenty-first group in a periodic table is contained in specific atomic %, in an insulator mainly containing aluminum nitride and its lattice constant is controlled in a specific range by solidifying the element in aluminum nitride crystal. CONSTITUTION: Conductivity is given to a ceramic resistor, which is mainly composed of aluminum nitride, by adding to it the second b-group element (0.005 to 25 atomic %). By the solidification of the second b-group element, its lattice constant is in the range of 0.003 to 0.025Å on a-axis and 0.005 to 0.050Å on c-axis, and they are different from the lattice constant of aluminum single unit. The ceramic resistor of the above-mentioned constitution has the volumetric specific resistance of 10<13> Ω-cm or smaller at 25 deg.C, and it is confirmed that its lower limit value is 10<6> Ω-cm. Also, this resistor has excellent resistance stability that the change against the resistance value at 25 deg.C in the range from room temperature to 300 deg.C is in three digits or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mainly composed of aluminum nitride suitable for heater materials, vacuum tube envelopes and antistatic materials for semiconductor manufacturing equipment, wafer transfer arms, wafer handling jigs and electrostatic chucks. To a ceramic resistor.

[0002]

2. Description of the Related Art Conventionally, as a method for adjusting the electric resistance of insulating ceramics, it has been generally practiced to add a conductive material to the insulating ceramics to control the resistance value. For example, titanium nitride is added to alumina to reduce the electric resistance.

On the other hand, aluminum nitride is a kind of non-oxidizing ceramics and is expected to be applied as a structural material or a high temperature material, and it has recently been reported that it has excellent durability against plasma resistance. There is. Therefore, application of this aluminum nitride as a component in a semiconductor manufacturing apparatus such as an electrostatic chuck is considered. However, this aluminum nitride itself is a highly insulating material, and even at room temperature, 1
At present, it has not been put into practical use because it has a resistance value of 0 ¹⁶ Ω-cm or more.

Even with respect to such aluminum nitride,
Attempts have been made to reduce the electrical resistance. For example, JP-A-56-4509 proposes that a conductive material such as Al is added to an insulating ceramic such as aluminum nitride or boron nitride to adjust the specific resistance. In the case of thin film ceramics, it is also possible to obtain a thin film resistor having a small temperature coefficient of resistance by dispersing metallic aluminum in aluminum nitride, for example.
Has been proposed in the issue.

[0005]

Generally, the volume resistivity of an insulator tends to decrease with temperature. For example, aluminum nitride has a resistivity of 10 ¹⁶ Ω-cm at room temperature.
To 300 ° C. to 10 ¹¹ Ω-cm or less. Therefore, when used from room temperature to a high temperature of 300 ° C., stable operation cannot be obtained, and there is a problem that the operating temperature condition is limited. Further, at room temperature or lower, there is a drawback that AlN alone cannot be used as a resistor having an appropriate resistance because it has a high resistance.

Further, in the method of controlling the electric resistance by adding the conductive material, there is a problem that the characteristics originally possessed by the insulating ceramics are impaired due to the characteristics of the conductive material itself. For example, the corrosion resistance and durability were poor, and the properties of aluminum nitride were deteriorated.

[0007]

The inventors of the present invention have made repeated studies on the above problems from the viewpoints of composition and structure as a ceramic resistor having an electric resistance of 10 ¹³ Ω-cm or less. For example, an insulator mainly composed of aluminum nitride formed by a chemical vapor deposition method contains 0.005 to 25 atomic% of an element of the group 2b element group of the periodic table, and the element is an aluminum nitride crystal. The volume resistivity of the insulating layer is 10 ¹³ Ω− by controlling the lattice constant of aluminum nitride to be in a specific range by making a solid solution therein.
It has been found that the material properties can be adjusted to a range of cm or less, the temperature change is small, and stable material properties can be obtained in a wide temperature range, and the present invention has been accomplished.

That is, the ceramic resistor of the present invention is a ceramic resistor mainly composed of an aluminum nitride crystal phase, and the element of Group 2b of the periodic table is 0.005 in the resistor.
.About.25 atomic%, and the lattice constant in the crystal phase is a
It is a value shifted by 0.003 to 0.025 angstrom on the axis and 0.005 to 0.050 angstrom on the c-axis, and the volume resistivity at 25 ° C. is 10 ¹³ Ω-cm or less. To do.

The present invention will be described in detail below. The ceramic resistor in the present invention is mainly composed of aluminum nitride, but has a composition of 0.002 elements of Group 2b of the periodic table.
The content is 5 to 25 atom%. This Periodic Table No. 2
The b-group element amount is an important element for imparting conductivity to aluminum nitride, and the element amount is 0.005
If it is less than atomic%, the desired resistance cannot be obtained, and it is 25 atomic%.
If it exceeds the range, another crystal phase is likely to be generated, resistance control becomes difficult, and peeling and cracks are likely to occur in the thin film. The elements of Group 2b of the Periodic Table are Zn, Cd, and Hg, and Zn and Cd are particularly preferable in terms of film forming property.

This ceramic resistor is structurally
Although mainly composed of aluminum nitride crystal, a part of the Group 2b element of the periodic table in this resistor is solid-solved in the aluminum nitride crystal, but cannot be completely dissolved in this crystal. There may be a case where a crystal phase such as a nitride of Group 2b of the periodic table is present in a proportion of 20% by weight or less due to the Group 2b element. In addition, the aluminum nitride crystal has a lattice constant of 0.003 to 0.025 angstrom from the lattice constant of aluminum nitride due to the solid solution of the Group 2b element of the periodic table,
It is in the range of values shifted by 0.005 to 0.050 angstroms on the c-axis, and it is clear that the lattice constant of crystals made of aluminum nitride alone (a-axis 3.120 angstroms, c-axis 4.994 angstroms) They have different lattice constants.

The ceramic resistor of the present invention has a volume resistivity of 10 ¹³ Ω-cm or less at 25 ° C. with the above-mentioned structure, and its lower limit value is 10 when confirmed by experiments.
It was ⁶ Ω-cm. Moreover, as is apparent from the examples described later, this resistor has a great feature that it has an excellent resistance stability in which the change with respect to the resistance value at 25 ° C. is 3 digits or less in the temperature range from room temperature to 300 ° C. is there.
Further, it has a resistance value which is not different from room temperature even at -100 ° C.

As a method for manufacturing the ceramic resistor of the present invention, the manufacturing method is not particularly limited as long as the above-mentioned constitution is satisfied, but the vapor phase growth method is particularly preferable in view of the ease of manufacturing. Preferably, specifically, a physical vapor phase synthesis method (PVD method) such as sputtering or ion plating, plasma CVD, photo CVD, MO (M
It is formed by a chemical vapor deposition method (CVD method) such as metal-organic CVD.
The VD method is good. According to these film forming methods,
A ceramic which can synthesize aluminum nitride in which b group element is excessively solid-solved and which contains 0.01 to 25 atom% of Group 2b element of the periodic table adopted by the present invention and whose lattice constant of aluminum nitride crystal is changed. A resistor can be obtained.

Zn is selected as a Group 2b element of the periodic table, and a specific manufacturing method using the CVD method is as follows: N ₂ gas, NH ₃ gas, Zn (CH ₃ ) ₂ and AlCl ₃ gas are used as raw material gases. And the flow rate ratio of these gases is N ₂ /
_{AlCl 3 = 5~70, Zn (CH} 3) 2 / NH 3 =
It can be produced by setting 0.001 to 5 and NH ₃ / AlCl ₃ = 0.1 to 10 and setting the film forming temperature to a relatively high temperature of 850 ° C. or higher. Instead of AlCl ₃ , a halide such as AlBr ₃ or an organic metal such as trimethylaluminum can be used.

In addition, as a gas containing a Group 2b element of the periodic table, Zn (CH ₃ ) ₂ , Zn (C ₂ H ₅ ) ₂ and Cd are used.
(CH ₃ ) ₂ , Cd (C ₂ H ₅ ) ₂ , Hg (CH ₃ ) ₂
And the like.

On the other hand, as the substrate for forming the film, any substrate can be used, but specifically, Al ₂ O ₃ and AlO are used.
N, Si ₃ N ₄ , diamond, mullite, ZrO ₂ ,
W, Mo, Mo-Mn, TiN, SiC, WC, carbon, and Si semiconductor materials (n-type or p-type) are also included, and among these, the coefficient of thermal expansion from room temperature to 800 ° C is 4.0 to 8. 0 × 10 ⁻⁶ / ° C., especially 5.0 to 7.4 ×
The one having a temperature of 10 ⁻⁶ / ° C. is most desirable in consideration of the adhesiveness.

[0016]

[Function] Normally, aluminum nitride has a volume resistivity of 10 ¹⁴
Although it is a high insulator exceeding Ω-cm, when an element of Group 2b of the periodic table is dissolved in the aluminum nitride crystal to replace aluminum or nitrogen with an element of the Group 2b of the periodic table, conductivity is obtained as an acceptor. Is considered to contribute to the increase of the conductivity of the crystal. The solid solution of the Group 2b element of the periodic table in the aluminum nitride crystal can be determined by the change in the lattice constant. For example, the lattice constant of aluminum nitride containing no Group 2b element of the periodic table is 3.
It is 120 angstroms and 4.994 angstroms on the c-axis, but as the Group 2b element of the periodic table becomes a solid solution, both the a-axis and the c-axis change. Then, when the lattice constant is shifted from these values by 0.003 to 0.025 angstrom on the a-axis and 0.005 to 0.050 angstrom on the c-axis, the volume resistivity is 10 ¹³ Ω-cm.
The following can be controlled.

Further, the ceramic resistor of the present invention has a small resistance change with temperature. For example, in the case of general aluminum nitride, in the temperature range from room temperature (25 ° C.) to 300 ° C., 10 ¹⁶ Ω-cm to 10 ¹² Ω- While it varies up to cm, in the ceramic resistor of the present invention, for example, 1
It has a feature that it changes from 0 ¹² Ω-cm to 10 ¹⁰ Ω-cm by 3 digits or less.

Therefore, it is particularly useful for applications such as electrostatic chucks in semiconductor manufacturing equipment which require stable resistance over a wide temperature range.

[0019]

【Example】

Example 1 An AlN film was formed on the surface of a substrate made of an aluminum nitride sintered body by a chemical vapor deposition method. The AlN film is formed by placing the substrate in a furnace heated to 900 ° C. by an external heating method, nitrogen 8 SLM, ammonia 1 SLM, 0 to 0.
A gas containing an element of Group 2b of the periodic table of 5 SLM was caused to flow to a pressure of 50 torr. Furthermore, aluminum chloride (A
lCl ₃ ) was introduced at a flow rate of 0.3 SLM to start the reaction to form a film having a thickness of 400 μm.

The obtained film was analyzed by X-ray diffraction to obtain Si (S
The angle was corrected using RM640b) as a standard sample, and the peak top method was used for calculation. The measurement plane index is (100),
(002), (101), (102), (110),
The values were (103), (112), and (004).

[0021]

[Table 1]

As is clear from the results shown in Table 1, the amount of the Group 2b element in the periodic table and the lattice constant in aluminum nitride vary depending on the flow rate of the gas containing the Group 2b element in the periodic table,
When the group 2b element-containing gas of the periodic table was not introduced at all and the group 2b element of the periodic table was also 0.0001 atom% of the impurity level, the volume resistivity was 9 × 10 ¹⁵ Ω-cm and high insulation was achieved. However, as the flow rate of the group 2b element-containing gas of the periodic table gradually increases, the amount of the group 2b element in the film increases, the lattice constant also gradually decreases, and the volume resistivity becomes 1 It decreased to 0.2 × 10 ⁶ Ω-cm. Note that the obtained aluminum nitride film was (00
It was an AlN film oriented in 2).

[0023]

As described above in detail, according to the present invention, the volume resistivity at room temperature is 10 ¹³ Ω-cm or less by controlling the amount of the Group 2b element of the periodic table and the lattice constant in aluminum nitride. Thus, it is possible to obtain a resistor whose resistance change is small at temperatures from −100 ° C. to 300 ° C.

Claims (2)

[Claims] 1. A ceramic resistor having an aluminum nitride crystal phase as a main component, wherein 0.005 to 25 atom% of a Group 2b element of the periodic table is present in the resistor, and the lattice constant in the crystal phase is From the lattice constant of aluminum nitride single phase a
The value is shifted by 0.003 to 0.025 angstrom on the axis and 0.005 to 0.050 angstrom on the c axis, and the volume resistivity at 25 ° C. is 1
A ceramic resistor having a resistance of 0 ¹³ Ω-cm or less. 2. The ceramic resistor according to claim 1, wherein the resistor is formed by a chemical vapor deposition method.