JPH1050811A - Temperature adjustment mechanism for semiconductor substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise and lower a temperature of a semiconductor substrate rapidly and adjust it at a set temperature rapidly by heating and cooling a sucked semiconductor substrate indirectly by a heating mechanism and a cooling mechanism for adjusting a substrate temperature. SOLUTION: A semiconductor substrate is subjected to electrostatic suction and fixed to an electrostatic sucking mechanism. A suction surface of the electrostatic sucking mechanism is heated and cooled. Then, the substrate is heated and cooled by heat conduction from a suction surface or heat conduction to a suction surface and is adjusted at a specified temperature. In the process, heat is conducted rapidly by integrally combining an electrostatic suction mechanism, a heating mechanism and a cooling mechanism. As for arrangement of a heating mechanism and a cooling mechanism, an order of a cooling mechanism - a heating mechanism - an electrostatic sucking mechanism and an order of combination of each mechanism to be combined to an electrostatic sucking mechanism with a cooling mechanism and a heating mechanism provided parallel are essential conditions. As for a heating means of a heating mechanism, either of heating by an electric heater and heating by heating medium circulation can be adopted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature control mechanism for a semiconductor substrate, and more particularly, to a temperature control mechanism capable of rapidly and precisely controlling a semiconductor substrate.

[0002]

2. Description of the Related Art The higher the degree of integration in plasma processing of semiconductors, the finer and more strict accuracy is required.
Plasma processing temperature is a very important factor in achieving ultra-fine and high-precision plasma processing. However, in the current equipment, cooling (in the case of etching processing) is performed to prevent excessive heating of the silicon wafer to be processed. There is no precise temperature control alone. In the film forming process (CVD), only heating (CVD) is performed to heat to a set temperature.
It is a fact that the natural heating during the treatment is left unchecked. The reality is the situation described above, but not because the importance of temperature management is not recognized, but because there is no mechanism that can actually manage the temperature at an economical speed. If the productivity is ignored in the laboratory, precise temperature control is possible, but in the current production line, for example, depending on the material of the thin film to be processed, it can be done quickly without reducing productivity for each film This is because there is no mechanism capable of performing quick control and precise control by changing the temperature to an optimum temperature for the film quality. In order to solve this problem, a mechanism that can quickly adjust the temperature according to the actual processing speed is required. In other words, a mechanism that can quickly and continuously adjust the temperature without reducing the processing speed is required. On the other hand, besides the plasma processing, there are many demands for quickly heating to a set temperature, or for quickly cooling after heating, in order to increase the operation rate of the apparatus. Here, too, there is a need for a mechanism that can quickly and continuously adjust the temperature.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a new temperature control mechanism capable of quickly raising and lowering the temperature of a semiconductor substrate to quickly adjust to a set temperature. Is to be provided.

[0004]

The above-mentioned problem is solved by the following means. That is, 1. A heating mechanism is coupled to a bottom surface of an electrostatic attraction mechanism that electrostatically attracts and fixes a semiconductor substrate, and a cooling mechanism is coupled to a bottom surface of the heating mechanism. A temperature control mechanism for a semiconductor substrate, wherein the temperature of the substrate is controlled by heating and cooling indirectly by a mechanism. 2. A good heat conductor having a built-in heating mechanism and a cooling mechanism is integrally connected to a bottom surface of an electrostatic suction mechanism for electrostatically holding and fixing the semiconductor substrate. A temperature control mechanism for a semiconductor substrate, wherein the substrate temperature is controlled by indirectly heating and cooling by the cooling mechanism.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The temperature control mechanism of the present invention
The semiconductor substrate is electrostatically attracted and fixed to the electrostatic attraction mechanism, and the suction surface of the electrostatic attraction mechanism is heated and cooled, and the substrate is heated by heat transfer from the attraction surface or heat transfer to the attraction surface.
It is characterized by cooling and adjusting to a predetermined temperature. At this time, the electrostatic attraction mechanism, the heating mechanism, and the cooling mechanism are integrally connected to measure quick heat transmission, and the arrangement of the heating mechanism and the cooling mechanism is determined by a cooling mechanism—a heating mechanism—
The essential conditions are the order of the electrostatic attraction mechanism, and the order of the combination of each mechanism to be combined with the electrostatic attraction mechanism in a state where the cooling mechanism and the heating mechanism are arranged in parallel. In the case of the reverse order, that is, in the case of the heating mechanism-cooling mechanism-electrostatic attraction mechanism, a cooling mechanism is inserted between the heating mechanism and the electrostatic attraction mechanism, and a gap portion of the refrigerant circulation path of the cooling mechanism becomes a heat insulating layer, and There is a problem that the rate of temperature rise is slowed down during substrate heating in order to hinder heat transfer from the substrate to the electrostatic attraction mechanism. That is, in the actual processing, the time during which the temperature changes from low temperature to high temperature and high temperature to low temperature is completely a loss time, so that an increase in the loss time causes a decrease in productivity. By reversing the order, the loss time during heating increases, leading to a significant decrease in productivity.

Here, the expression "integral connection" of the electrostatic attraction mechanism, the heating mechanism, and the cooling mechanism means the following. Bonding by metallurgical bonding Bonding by stacking films Dielectric ceramic of electrostatic adsorption mechanism is sprayed, PVD, C
A case in which a film is formed on a base material (base material of the heating mechanism) by a film forming process such as VD or sputtering to be tightly bonded to the base material (base material of the heating mechanism). Bonding by sintering or sintering Metal-metal is in the category of metallurgical joining, but sintering or sintering of combinations of metal-ceramic and ceramic-ceramic that fall outside the category of metallurgical joining.

[Electrostatic chucking mechanism] The electrostatic chucking mechanism of the present invention means a so-called electrostatic chucking mechanism of an electrostatic chuck. The electrostatic attraction mechanism is a general term for a structure mainly composed of a dielectric ceramic and a structure including an electrostatic induction electrode formed on the back surface of the ceramic. In other words, in a monopolar electrostatic chuck, a dielectric ceramic and a structure combining an electrostatic induction electrode formed on the back surface of the ceramic are mainly used. The structure mainly including a structure including an electrostatic induction electrode formed on the back surface of the ceramic and a ceramic insulating plate lining the back surface of the electrode serves as a suction mechanism.

[0008] The dielectric ceramic is a dielectric ceramic sintered body, or a dielectric ceramic film, that is, a dielectric ceramic film formed by thermal spraying, or formed by a thin film treatment such as sputtering or CVD. Alternatively, any one formed by another film forming process can be selected. Here, the dielectric ceramic is not limited to only a ceramic having a particularly high dielectric constant. In view of the phenomenon that even if the thickness of ordinary electric insulating ceramic is reduced, the attraction force increases, the general dielectric ceramic having a low dielectric constant is also included in the category of "dielectric ceramic" in the present invention. From high dielectric constant ceramics such as alumina titanate and barium titanate,
Insulating ceramics such as silicon nitride, aluminum nitride, alumina, sapphire, silicon carbide, formed diamond, and CBN fall into this category.

A heating mechanism (the first invention) and a good heat conductor (the second invention) are connected to the back of the electrostatic attraction mechanism. Then, this metal surface may be used as an electrode. In other words, the heating mechanism and the surface of the good heat conductor coupled to the back of the electrostatic attraction mechanism may be used as electrodes. Conversely, the electrode metal may be used as one side of the heating mechanism, one side of the good heat conductor, or one side of the cooling mechanism. Further, one side of the heating mechanism and one side of the good heat conductor may be made into insulators, and may be used as insulators (in the case of bipolar) on the back of the electrostatic attraction mechanism.

In addition, when the heating mechanism (the first invention) and the good heat conductor (the second invention) are connected to the back surface of the suction mechanism, different kinds of materials are used on the connection surface for the purpose of stress buffering or electrical insulation. In some cases, a layer of material is inserted. The “electrostatic chucking mechanism” of the present invention is a generic term including these layers to be inserted.

[Heating Mechanism] As the heating means, any means of heating by an electric heater or heating by circulation of a heating medium may be adopted. As the heat medium, either a liquid or gas heat medium can be adopted. There are no particular restrictions on the material and structure of the electric heater, and any material or structure can be used, regardless of metal, inorganic, or material, as long as it generates electricity. The formation of the electric heating circuit is formed by using a heater wire, baking or fixing the powder of the electric heating material to the electric heating circuit pattern, forming the film of the electric heating material in the electric heating circuit pattern shape,
Alternatively, a circuit pattern may be formed from an electrothermal metal foil and used by fixing the circuit pattern to a base material, or other commonly used circuit forming means may be appropriately selected depending on the purpose.

The heater wire is used as a bare wire or as required, with the wire surface insulated. In the case of a bare strand, a groove having an electrothermal circuit pattern may be formed in a base made of a good heat conductor, and the strand may be embedded and fixed therein. At this time, the material of the base material may be any as long as at least the surface of the groove is an insulator. The entire substrate may be formed of metal, and only the surface of the groove may be an insulator. If necessary, the wire may be fixed by filling the groove with a refractory. When the surface of the wire is insulated, it may be brazed to a base material of a good heat conductor via an insulating layer. Alternatively, a metal skin may be further fitted on the surface of the insulating layer, and the skin may be brazed to the base material. Further, as a matter of course, similarly to the case of the bare strand, a groove having an electrothermal circuit pattern may be formed in the base material and embedded therein. Alternatively, a structure in which a heater wire whose surface is insulated is cast in metal may be used. In this case, the cast-in metal becomes the base material.

The baking or fixing of the electric heating material is performed by baking or fixing the powder paste of the electric heating material to the insulating substrate having good thermal conductivity.

The film of the electric heating material is formed by forming a high melting point metal, a noble metal, or another electric heating metal on a substrate having good thermal conductivity and insulation by means of thermal spraying, sputtering, CVD, PVD or the like. It is also effective to use a so-called integral sintering type film in which a high melting point metal such as W or Mo is printed on a so-called green ceramic substrate (green sheet) before firing and fired simultaneously with the ceramic. In any case, in this heating mechanism, the electric heating circuit needs to be insulated on the upper and lower surfaces, and in order to rapidly control the temperature, both the heat capacity of the insulator and the heat capacity of the electric heating circuit are infinitely small, that is, Need to be thin. The ceramic heater formed by printing a high melting point metal such as W and Mo on the above ceramic green sheet and integrally sintering it has the advantage of being extremely thin, and is therefore most suitable for the purpose of the present invention.

The base material having good heat conductivity means ceramic or metal having good heat conductivity. Ceramics include aluminum nitride, silicon carbide, and alumina ceramics. Metals include iron, nickel, cobalt, copper, aluminum, silver, molybdenum, tungsten, and alloys and composite materials (metals) of these metals. Metal, metal-ceramic) or other good heat conducting materials. In addition, in the portion of the good heat conductive substrate facing the back surface of the suction mechanism, the back material of the suction mechanism may be used as it is.

[Cooling mechanism] Cooling using a liquid or gaseous refrigerant may be used. In cooling with a refrigerant, a refrigerant circulation path is provided in a base material, and a liquid or gas refrigerant is circulated in the refrigerant circulation path for cooling. For the circulation path, grooves are formed in the base material, or the structure to embed, join, or incorporate the conduit in the base material is formed by casting metal or welding, or the structure to incorporate the conduit is ceramic sintered. It is formed in various ways, such as in a body. The material of the base material forming the circulation path is a metal having good thermal conductivity, ceramic or a composite material of metal ceramic, and the like.
Either may be adopted. In particular, since the coefficient of linear expansion can be freely adjusted by changing the ratio of the metal / ceramic composite material, it is advantageous in reducing the residual stress at the joint.

[Parallel Arrangement of Heating Mechanism and Cooling Mechanism] The heating mechanism and the cooling mechanism may be arranged side by side in addition to the above-described structure in which the heating mechanism and the cooling mechanism are overlapped. That is, a structure in which the electric heating circuit and the circulation path of the refrigerant are arranged side by side may be used.

An embodiment will be described with reference to the drawings. The temperature control mechanism of the present invention can be basically divided into two structures. One is a structure in which a cooling mechanism, a heating mechanism, and an electrostatic attraction mechanism are combined and integrated in this order (FIGS. 1 and 3). The other is a cooling mechanism and a heating mechanism that are arranged side by side and electrostatically attracted. This is a structure (FIGS. 2 and 4) integrated and integrated with the mechanism. These are further classified into two types according to the structure of the electrostatic attraction mechanism. One is a structure in which the dielectric of the electrostatic attraction mechanism is formed of a ceramic sintered body, and the other is a dielectric formed by a film forming method such as thermal spraying, CVD, PVD, sputtering, or other film forming methods. Is the case. 1 to 4 illustrate these situations. The structure shown in FIG. 1 is a structure in which a cooling mechanism, a heating mechanism, and an electrostatic suction mechanism are combined and integrated in this order, in which a dielectric is formed of a ceramic sintered body. FIG. 2 shows a structure in which a cooling mechanism and a heating mechanism are juxtaposed and integrated with an electrostatic attraction mechanism, in which the dielectric is formed of a ceramic sintered body. FIG. 3 shows a structure in which a cooling mechanism, a heating mechanism, and an electrostatic suction mechanism are combined and integrated in this order, and a dielectric is formed by a film forming method. FIG. 4 shows a structure in which a cooling mechanism and a heating mechanism are juxtaposed and integrated with an electrostatic attraction mechanism, in which a dielectric is formed by a film forming method. In FIGS. 1 and 3, the cooling mechanism, the heating mechanism, and the electrostatic attraction mechanism are all integrally connected. In FIG. 2, a cooling mechanism and a heating mechanism are integrally incorporated in a good heat conductor, and are combined and integrated with an electrostatic attraction mechanism. FIG. 4 shows a structure in which a dielectric ceramic film is formed on a structure in which a cooling mechanism and a heating mechanism are integrally built in a good heat conductor.

The following can be mainly used as the electric heating element of the heating mechanism. Heater element wire, powdered or fixed electric heating material powder, coated with electric heating material film, electric heating metal foil, ceramic and sintered integral heater. A typical structure of a heating mechanism using these electric heaters is a structure shown in FIGS. 5 to 8 show examples of a structure using a heater wire. FIG. 5 shows a structure in which a heater wire whose surface is insulated is cast in a cast metal. The surface A is joined to the electrostatic attraction mechanism, and the surface B is joined to the cooling mechanism. FIG. 6 shows a structure in which a heater wire is embedded in a groove formed in the base material B and the base material A is covered. As long as the surfaces of the heater wires are insulated, the materials of the substrates A and B may be metal or ceramic. When the heater wire is bare, at least a portion of the base materials A and B that comes into contact with the heater wire needs to be made of an insulating material. FIG. 7 shows a structure in which a heater wire is sandwiched between base materials A and B and brazed. Substrates A and B
The gap between the heater wires is filled with brazing filler metal. FIG. 8 shows a case where a heater element wire having a surface insulated is buried in a groove formed in the ceramic base material A, and a gap is filled with a brazing material. FIG. 9 shows an electrothermal metal foil sandwiched between ceramic substrates A and B and bonded and fixed with an inorganic adhesive. FIG. 10 shows a structure in which a heater circuit is integrally sintered in ceramic. (A) is a structure in which ceramic and a heater circuit (tungsten-based electric heating circuit) are integrally sintered. The suction mechanism is joined to the surface A, and the cooling mechanism is joined to the surface B.
(B) shows a structure in which the heater circuit and the electrode of the electrostatic chuck are simultaneously sintered together. FIG. 11 shows a structure in which a heater wire and a refrigerant circulation pipe whose surfaces are insulated are cast together with a cast metal. A structure in which a heater wire and a refrigerant circulation line are arranged side by side. FIG. 12 shows a structure in which a heater wire and a refrigerant circulation pipe whose surfaces are insulated are cast together with a cast metal. A structure in which the heater wire (top) and the refrigerant circulation pipeline (bottom) are arranged vertically.

FIGS. 13 and 14 show an example in which the heating mechanism and the cooling mechanism are not provided side by side, but are built in the same base material. FIG. 13 shows that the electric heater is embedded in the groove,
An example in which a refrigerant circulation path is formed at the bottom of a base material. FIG. 14 shows an example in which a heater is cast in a casting metal and a refrigerant circulation path is formed in the bottom of the casting metal.

Next, an embodiment will be described. Example 1 Structure: Structure of FIG. 15 Dielectric adsorption mechanism: Alumina-based dielectric ceramic (φ50) in which bipolar electrodes are integrally sintered inside ceramic
X2t) Heating mechanism: Alumina ceramic heater with a structure in which a tungsten heating circuit is co-fired with ceramic (structure of (a) in Fig. 10) 50 x 2t, output: 200W Cooling mechanism: Uses a nickel cooling box . The refrigerant gas uses Freon gas. Structure of cooling mechanism A 10 mm wide, 0.5 mm thick strip of nickel is spirally wound, sandwiched between two φ50 × 1t nickel discs, and the end face is attached to two nickel discs and a silver braze. did. [Joining of each mechanism] The dielectric adsorption mechanism, heating mechanism and cooling mechanism were brazed with indium. The joining surfaces of the dielectric adsorption mechanism and the heating mechanism were metallized by electroless nickel plating and joined. [Test] Electrostatic adsorption: A voltage of 800 V was applied to the bipolar electrode to adsorb a 2-inch silicon wafer on the surface of the dielectric ceramic. Heating Start heating from room temperature (20 ° C). The heater was energized, and the wafer surface could be heated to 100 ° C. in 40 seconds. After turning off the cooling heater, a refrigerant gas was flown. The wafer surface was cooled to 20 ° C. in 60 seconds. Holding The surface temperature of the silicon wafer could be kept in the range of 100 ° C. ± 1 ° C. by using both the heating of the heater and the cooling of the refrigerant gas. According to the present invention, it was confirmed that the temperature of the silicon wafer can be rapidly raised and lowered and the silicon wafer can be uniformly maintained.

Example 2 Structure of FIG. 16 A spirally wound 500 W electric heater (sheath heater) wire and a spirally wound stainless steel cooling pipe of 8 mm in outer diameter and 7 mm in inner diameter are vertically stacked. Structure cast in molten aluminum. Dielectric ceramic (φ50) is made of aluminum and aluminum on the surface of the heating and cooling mechanism (pedestal).
A titania-based dielectric ceramic powder was formed by spraying 0.3 mm. The electrode is monopolar and also serves as an aluminum pedestal. Cooling mechanism: Uses chlorofluorocarbon as refrigerant. [Test] Electrostatic adsorption: 8 between pedestal and silicon wafer
A 2-inch silicon wafer was adsorbed on the surface of the dielectric ceramic by applying a voltage of 00V. Heating Start from 0 ° C and energize the heater. The wafer surface could reach 50 ° C. in 12 seconds. Holding The surface temperature of the silicon wafer could be maintained in the range of 50 ° C. ± 1 ° C. by using both the heating with the heater and the cooling with the refrigerant gas. After turning off the cooling heater, the wafer surface was cooled to room temperature (20 ° C.) in 30 seconds by flowing a coolant gas. It has been confirmed that the present invention can rapidly raise and lower the temperature of a silicon wafer and maintain the temperature at a uniform temperature.

Example 3 Structure: Structure of FIG. 17 Heating mechanism: Aluminum nitride heater having a structure in which a tungsten-based metal heating circuit is co-fired with ceramic (FIG. 1)
0 (a) structure) φ50 × 2t, 200W Dielectric adsorption mechanism: φ50 × 0.2 for dielectric ceramic
mm aluminum nitride disk, which was brazed (solid) to an aluminum nitride heater. Single pole type with silver soldering surface also serving as electrode. Structure of the cooling mechanism: A tungsten band of 10 mm in width and 0.5 mm in thickness is spirally wound, and two pieces of φ50 ×
A structure in which two tungsten disks and a silver braze are attached to the end face of a 1t tungsten disk. Air cooling [Joining of each mechanism] The aluminum nitride heater and the cooling mechanism were equipped with silver brazing. When brazing, 50% W- between the aluminum nitride heater and the cooling mechanism of tungsten for the purpose of buffering stress
Disk of composite sintered body of 50% aluminum nitride (vol.%) (Φ5
(0 × 1 mm). [Test] Electrostatic adsorption: 7 between electrode and silicon wafer
A 2-inch silicon wafer was adsorbed on the surface of the dielectric ceramic by applying a voltage of 00V. Heating Start heating from room temperature (20 ° C). The heater was energized, and the wafer surface could reach 100 ° C. in 25 seconds and 300 ° C. in 2 minutes. After turning off the cooling heater, air was flown. 2 for wafer surface
Cooled down to 100 ° C in minutes. Holding The surface temperature of the silicon wafer could be maintained in the range of 300 ° C. ± 1 ° C. by using both the heater heating and the air cooling. It has been confirmed that the present invention can rapidly raise and lower the temperature of a silicon wafer and maintain the temperature at a uniform temperature.

[0024]

As described in detail above, the present invention is a mechanism capable of raising and lowering the temperature of a semiconductor substrate surface in an extremely short temperature cycle, and greatly contributes to improvement of plasma processing and film forming processing quality without reducing production efficiency. It is what constitutes.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a temperature control mechanism.

FIG. 2 is an explanatory diagram of a temperature adjusting mechanism.

FIG. 3 is an explanatory diagram of a temperature adjusting mechanism.

FIG. 4 is an explanatory diagram of a temperature adjusting mechanism.

FIG. 5 is an explanatory diagram of a heating mechanism. (Using heater wire)

FIG. 6 is an explanatory view of a heating mechanism. (Using heater wire)

FIG. 7 is an explanatory diagram of a heating mechanism. (Using heater wire)

FIG. 8 is an explanatory view of a heating mechanism. (Using heater wire)

FIG. 9 is an explanatory diagram of a heating mechanism. (Using electric heating metal foil)

FIG. 10 is an explanatory diagram of a heating mechanism. (Simultaneous sintering heater)

FIG. 11 is an explanatory view of a heating mechanism. (Cast heater)

FIG. 12 is an explanatory diagram of a heating mechanism. (Cast heater)

FIG. 13 is an explanatory diagram of a combined structure of a heating and cooling mechanism.

FIG. 14 is an explanatory diagram of a combined structure of a heating and cooling mechanism.

FIG. 15 is an explanatory diagram of the structure of the embodiment.

FIG. 16 is an explanatory diagram of the structure of the embodiment.

FIG. 17 is an explanatory diagram of the structure of the embodiment.

Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication // H01L 21/31 H01L 21/302 B

Claims (2)

[Claims] A heating mechanism is coupled to a bottom surface of an electrostatic attraction mechanism for electrostatically attracting and fixing a semiconductor substrate, and a cooling mechanism is coupled to a bottom surface of the heating mechanism. A temperature control mechanism for a semiconductor substrate, wherein the temperature of the substrate is controlled by heating and cooling indirectly by a heating mechanism and a cooling mechanism. 2. A structure in which a good heat conductor having a built-in heating mechanism and a cooling mechanism is integrally connected to a bottom surface of an electrostatic attraction mechanism for electrostatically attracting and fixing a semiconductor substrate. A semiconductor substrate temperature adjusting mechanism wherein the substrate temperature is adjusted by indirectly heating and cooling the substrate by the heating mechanism and the cooling mechanism.