Ceramic resistor

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Industrial application field]

The present invention relates to a ceramic resistor mainly made of aluminum nitride, which is suitable for a heater material, a vacuum tube outer tube, a charge removing material in a semiconductor manufacturing apparatus, a wafer transfer arm, a wafer handling jig, and the like.

【0002】

[Previous technology]

Conventionally, as a method for adjusting the electric resistance of insulating ceramics, it is 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 electrical resistance.

【0003】

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. Recently, it has been reported that it has excellent durability against plasma. 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, it is 10¹⁶At present, it has not been put into practical use because it has a resistance value of Ω-cm or more.

【0004】

Attempts have been made to reduce the electrical resistance of such aluminum nitride. For example, it is proposed in Japanese Patent Application Laid-Open No. 56-4509 to adjust the specific resistance by adding a conductive material such as Al to the insulating ceramics of aluminum nitride or boron nitride. Further, in thin film ceramics, for example, it is proposed in Tokusho 55-50364 to obtain a thin film resistor having a small temperature coefficient of resistance by dispersing metallic aluminum in aluminum nitride.

【0005】

[Problems to be Solved by the Invention]

In general, the volume specific resistance value of an insulator tends to decrease with temperature, but in the case of aluminum nitride, for example, it is 10 at room temperature.¹⁶10 from Ω-cm at 300 ° C¹¹It tends to decrease to Ω-cm or less. Therefore, when it is used from room temperature to a high temperature of 300 ° C, there is a problem that the operating temperature condition is limited because the resistance value changes and stable operation cannot be obtained.

【0006】

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

【0007】

[Means to solve problems]

The present inventors have a particular electrical resistance of 10 for the above problems.¹³As a result of repeated studies from the viewpoint of its composition and structure as a ceramic resistor of Ω-cm or less, for example, an element of Group 4b of the Periodic Table in an insulator containing aluminum nitride as a main component formed by a chemical vapor phase synthesis method. By containing 0.005 to 30 atomic% of group elements and dissolving the element in the aluminum nitride crystal to control the lattice constant of aluminum nitride within a specific range, the volume specific resistance of the insulating layer is 10¹³We have found that the material properties can be adjusted in the range of Ω-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 made.

【0008】

That is, the ceramic resistor of the present invention is a ceramic resistor mainly composed of an aluminum nitride crystal phase, and 0.005 to 30 atomic% of Group 4b elements of the Periodic Table are present in the ceramic resistor in the crystal phase. The lattice constant is a value shifted by 0.003 to 0.030 angstroms on the a-axis and 0.004 to 0.080 angstroms on the c-axis, and the volume specific resistance at 25 ° C is 10.¹³It is characterized by being Ω-cm or less.

【0009】

Hereinafter, the present invention will be described in detail. The ceramic resistor in the present invention is mainly composed of aluminum nitride, but contains 0.005 to 30 atomic% of Group 4b elements of the Periodic Table in terms of composition. The amount of elements in Group 4b of the Periodic Table is an important element for imparting conductivity to aluminum nitride. If the amount of this element is less than 0.005 atomic%, the desired resistance cannot be obtained, and 30 atomic%. If it exceeds, other crystal phases are likely to be formed, resistance control becomes difficult, and peeling and cracks are likely to occur in the thin film. The elements of Group 4b of the periodic table are specifically C, Si, Ge, Sn, and Pb, and C and Si are particularly desirable in terms of film forming property.

【0010】

In addition, this ceramic resistor is mainly composed of aluminum nitride crystals in terms of structure, and some of the elements of Group 4b of the Periodic Table of the Periodic Table in this resistor are dissolved in the aluminum nitride crystals. Due to the Group 4b elements of the Periodic Table that cannot be completely dissolved in the crystal, the crystal phase of the nitrides of the Group 4b Group of the Periodic Table may be present at a ratio of 20% by weight or less. In addition, the lattice constant of aluminum nitride crystals is in the range of values in which the lattice constant is shifted from the lattice constant of aluminum nitride by 0.003 to 0.030 angstroms on the a-axis and 0.004 to 0.080 angstroms on the c-axis due to the solid dissolution of Group 4b elements in the periodic table. It has a lattice constant that is clearly different from the lattice constants (a-axis 3.120 angstroms, c-axis 4.994 angstroms) of crystals made of aluminum nitride alone.

【0011】

The ceramic resistor of the present invention has 10 at 25 ° C due to the above configuration.¹³It has a volume specific resistance of Ω-cm or less, and its lower limit is about 320 Ω-cm. Moreover, as is clear from the examples described later, this resistor also has excellent resistance stability in which the change with respect to the resistance value of 25 ° C is 3 orders of magnitude or less in the temperature range from room temperature to 300 ° C. It is a feature. Moreover, it has the same resistance value as room temperature even at -100 ° C.

【0012】

The method for producing the ceramic resistor of the present invention does not particularly limit the production method as long as the above configuration is satisfied, but the vapor phase growth method is particularly preferable in terms of ease of production. Specifically, it is formed by a physical vapor deposition method (PVD method) such as sputtering and ion plating, and a chemical vapor deposition method (CVD method) such as plasma CVD, optical CVD, and MO (Metal-organic) CVD. However, among these, the CVD method is preferable. According to these film forming methods, aluminum nitride in which the elements of Group 4b of the Periodic Table are excessively dissolved can be synthesized, and the elements of Group 4b of the Periodic Table adopted in the present invention are contained in an amount of 0.01 to 30 atomic%. It is possible to obtain a ceramic resistor having a changed lattice constant of the aluminum nitride crystal.

【0013】

Si was selected as the Group 4b element of the Periodic Table, and as a specific manufacturing method using the CVD method, N was used as the raw material gas.₂Gas, NH₃Gas, SiCl₄And AlCl₃Using gas, set the flow rate ratio of these gases to N₂/ AlCl₃= 5 ~ 70, SiCl₄/ NH₃= 0.001 ~ 3, NH₃/ AlCl₃It can be produced by setting = 0.1 to 10 and setting the film formation temperature to a relatively high temperature of 850 ° C or higher. SiCl₄SiHCl instead of₃, SiH₂Cl₂, SiH₄, Si₂H₆Etc. may be used, and AlCl₃Instead of, a halide such as AlBr or an organic aluminum such as trimethylaluminum may be used.

【0014】

On the other hand, any substrate that forms a film can be used, but specifically, Al.₂O₃, AlON, Si₃N₄, Diamond, mullite, ZrO₂, W, Mo, Mo-Mn, TiN, SiC, WC, carbon and Si semiconductor materials (n-type or p-type) can also be mentioned, but among these, the sintered body mainly composed of aluminum nitride is considered for adhesion. Most desirable.

【0015】

[Action]

Normally, aluminum nitride has a volume specific resistance of 10.¹⁴It is a high insulator exceeding Ω-cm, but when the element of Group 4b of the Periodic Table is dissolved in the aluminum nitride crystal and aluminum or nitrogen is replaced with the element of Group 4b of the Periodic Table, it becomes a donor or acceptor. It is considered to contribute to the conductivity and increase the conductivity of the crystal. Further, the solid solution of the Group 4b element of the Periodic Table of the Periodic Table to the aluminum nitride crystal can be determined by the change of the lattice constant. For example, the lattice constant of aluminum nitride containing no Group 4b elements of the Periodic Table was 3.120 angstroms on the a-axis and 4.994 angstroms on the c-axis. It also changes with the c-axis. Then, if the lattice constant is shifted from these values to 0.003 to 0.030 angstroms on the a-axis and 0.004 to 0.080 angstroms on the c-axis to a larger or smaller value, the volume eigenresistance is set to 10.¹³It can be controlled to Ω-cm or less.

【0016】

Moreover, the ceramic resistor of the present invention has a small change in resistance with respect to temperature. For example, in the case of general aluminum nitride, it is 10 in the temperature range from room temperature (25 ° C) to 300 ° C.¹⁶Ω-cm to 10¹¹In contrast to Ω-cm, the ceramic resistor of the present invention has, for example, 10¹³Ω-cm to 10¹¹It has the characteristic that it changes only up to Ω-cm by 3 orders of magnitude or less, and maintains the volume specific resistance value with a small rate of change even at a low temperature of -100 ° C.

【0017】

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

【0018】

[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. To form the AlN film, the substrate was placed in a furnace heated to 900 ° C by an external heating method, and a SiCl4 gas of 8 SLM for nitrogen, 1 SLM for ammonia, and 0 to 0.5 SLM was flowed to set the pressure to 50 torr. In addition, aluminum chloride (AlCl₃) Was introduced at a flow rate of 0.3 SLM to initiate the reaction, and a film having a film thickness of 400 μm was formed (Sample Nos. 1 to 9).

【0019】

The obtained film was angle-corrected by the X-ray diffraction method using Si (SRM640b) as a standard sample, and calculated by the peak top method. The measurement surface indices were (100), (002), (101), (102), (110), (103), (112), and (004). In addition, volume intrinsic resistance at -100 ° C, room temperature and 300 ° C was measured and shown in Table 1. In addition, Fig. 1 shows the volume specific resistance of No. 5 at -100 to 600 ° C.

【0020】

Example 2 An AlN film was formed on the surface of a substrate made of an aluminum nitride sintered body by a chemical vapor deposition method. To form the AlN film, the substrate is placed in a furnace heated to 900 ° C by an external heating method, nitrogen is 8 SLM, ammonia is 1 SLM, and CH is 0 to 0.5 SLM.₄, GeH₄, SnCl₄, Pb (CH)₃)₄The pressure was set to 50 torr by flowing gas. In addition, aluminum chloride (AlCl₃) Was introduced at a flow rate of 0.3 SLM to initiate the reaction, and a film having a film thickness of about 400 μm was formed (Sample Nos. 10 to 13). For the obtained film, the lattice constant was calculated from the X-ray diffraction method in the same manner as in Example 1, and the volume specific resistance at -100 ° C, room temperature and 300 ° C was measured, and the results are shown in Table 1.

【0021】

[table 1]

【0022】

As is clear from the results of Samples Nos. 1 to 9 in Table 1, the Si atomic weight and lattice constant in aluminum nitride are SiCl.₄It changes with the flow rate and is SiC₄If the Si atomic weight is 0.0001 atomic% of the impurity level, the volume specific resistance is also 9 × 10.¹⁵It had high insulation of Ω-cm, but SiCl₄As the flow rate of the sample gradually increased, the Si atomic weight in the film increased and the lattice constant gradually decreased, but the film of Sample No. 9 had a silicon nitride phase as the main phase. The obtained aluminum nitride film was an AlN film oriented in (002) from the X-ray diffraction measurement. However, a transmission electron microscope observation shows that a silicon nitride crystal phase is present, and the amount thereof is SiCl.₄There was a correlation with the flow rate.

【0023】

Regarding the elements of Group 4b of the Periodic Table other than Si, the atomic weights and lattice constants of the elements of Group 4b of the Periodic Table in aluminum nitride change depending on the flow rate of the added gas containing the elements of Group 4b of the Periodic Table. As the flow rate of the added gas containing the Group 4b element was gradually increased, the amount of the Group 4b element in the periodic table in the film increased, the lattice constant gradually changed, and the volume specific resistance decreased. The obtained aluminum nitride film was an AlN film oriented in (002) from the X-ray diffraction measurement, and some of them had a nitride crystal phase.

【0024】

[Effect of the invention]

As described in detail above, according to the present invention, by controlling the amount of elements in Group 4b of the periodic table and the lattice constant in aluminum nitride, the volume specific resistance at room temperature is 10.¹³It is possible to obtain a resistor with a temperature change of Ω-cm or less and a small temperature change. Therefore, the resistance value can be changed without losing the characteristics of aluminum nitride, for example, corrosion resistance.

[Simple explanation of drawings]

[Figure 1]

It is a figure which shows the change of the volume specific resistance of sample No. 5 from -100 ° C to 600 ° C.