CN115966501A - Electrostatic chuck - Google Patents

Abstract

The application discloses electrostatic chuck, including sucking disc main part, heat dissipation base and set up in heat conduction cavity between sucking disc main part and the heat dissipation base, be provided with electrostatic electrode and heating electrode in the sucking disc main part, electrostatic electrode is used for producing electrostatic attraction, heating electrode is used for producing the heat, form in the heat conduction cavity can with external connection's passageway, the heat conduction cavity has first user state and the second user state of high heat conductivity of low heat conductivity relatively, under first user state do not fill heat-conducting medium in the passageway, under the second user state fill heat-conducting medium in the passageway, the heat conduction cavity of this application electrostatic chuck can select to fill or not fill heat-conducting medium as required to have different heat conductivities, the user demand of adaptation intensification and cooling.

Description

Electrostatic chuck

Technical Field

The application relates to the technical field of semiconductor manufacturing, in particular to an electrostatic chuck.

Background

Electrostatic chucks are widely used in Integrated Circuit (IC) manufacturing, such as plasma ETCH (ETCH), physical Vapor Deposition (PVD), chemical Vapor Deposition (CVD), etc., to support a wafer to prevent the wafer from moving or dislocating during the process, to provide rf bias to the wafer, and to control the temperature of the wafer surface.

With the rapid development of the third generation wide bandgap semiconductor, the demand for high temperature electrostatic chucks for semiconductor device, especially for SiC device fabrication, has risen dramatically. The technical requirement of the high-temperature electrostatic chuck is extremely high, the temperature control precision needs to reach +/-2 ℃, the time of heating from room temperature to 500 ℃ is not more than 20 minutes, and the temperature range needs to reach 100-700 ℃, so that the wafer kept on the high-temperature electrostatic chuck reaches the expected temperature (such as above 500 ℃), and the process precision of film forming or etching of the wafer and the like is guaranteed.

Most of the existing high-temperature electrostatic chucks utilize a refrigerating unit to cool the electrostatic chuck by cooling a cooling liquid flowing through the electrostatic chuck, and the cooling liquid is matched with a heating electrode arranged on the electrostatic chuck to realize real-time temperature control of the electrostatic chuck. However, the cooling of the electrostatic chuck requires that heat conduction between the materials of the layers can be performed rapidly, i.e. the materials of the layers have high thermal conductivity; the heating of the electrostatic chuck requires that each layer of material has a low thermal conductivity to prevent the heat generated by the heating electrode from quickly losing through each layer of material, and both the materials are difficult to be considered simultaneously.

Disclosure of Invention

In view of this, this application provides an electrostatic chuck, can effectively reduce thermal loss when the intensification, can give off with higher speed the thermal when the cooling again, compromise the user demand of intensification and cooling.

The utility model provides an electrostatic chuck, includes sucking disc main part, heat dissipation base and set up in heat conduction cavity between sucking disc main part and the heat dissipation base, be provided with electrostatic electrode and heating electrode in the sucking disc main part, electrostatic electrode is used for producing electrostatic attraction, heating electrode is used for the production of heat, form in the heat conduction cavity can with external connection's passageway, the heat conduction cavity has the first user state of relatively low heat conductivity and the second user state of relatively high heat conductivity, under first user state do not fill heat-conducting medium in the passageway, under the second user state pack heat-conducting medium in the passageway.

Compared with the prior art, the electrostatic chuck is provided with the heat conduction cavity between the chuck main body and the heat dissipation base, the channel is formed in the heat conduction cavity, the channel can be selectively filled or not filled with heat conduction media as required, the heat conduction performance of the heat conduction cavity is poor when the heat conduction media are not filled, and the heat transfer to the heat dissipation base is slowed down; the heat conduction cavity has good heat conduction performance when filled with heat conduction media, and accelerates the transfer of heat to the heat dissipation base, thereby meeting the use requirements of temperature rise and temperature reduction.

Drawings

Fig. 1 is a schematic view of a first embodiment of an electrostatic chuck of the present application.

Fig. 2 is a schematic view of another usage state of the electrostatic chuck shown in fig. 1.

Fig. 3 is a schematic view of a second embodiment of an electrostatic chuck of the present application.

Fig. 4 is a schematic view of a third embodiment of an electrostatic chuck of the present application.

Detailed Description

To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings. One or more embodiments of the present disclosure are illustrated in the drawings to provide a more accurate and thorough understanding of the subject disclosure. It should be understood, however, that the present application may be embodied in many different forms and is not limited to the embodiments described below.

The same or similar reference numbers in the drawings of this application correspond to the same or similar components; in the description of the present application, it is to be understood that if there is an orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", etc. based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not intended to indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and are not to be construed as limitations of the present patent, and specific meanings of the above terms may be understood by those skilled in the art according to specific situations.

The present application provides an electrostatic chuck 100, which is mainly used for bearing a wafer, especially a SiC wafer, in a semiconductor device manufacturing process. Fig. 1 illustrates an embodiment of an electrostatic chuck 100 according to the present invention, wherein the electrostatic chuck 100 is a thin disk-shaped structure, and comprises a chuck body 20, a heat conducting cavity 30 and a heat dissipating base 40 sequentially arranged from top to bottom.

The chuck body 20 serves as a main structure of the electrostatic chuck 100, and is used for carrying and fixing a wafer to be processed. In the embodiment shown in FIG. 1, the chuck body 20 includes a dielectric layer 22 and an electrostatic electrode 24 and a heater electrode 26 embedded in the dielectric layer 22. Dielectric layer 22 is an insulating material such as alumina ceramic. The electrostatic electrode 24 and the heating electrode 26 are both thin-film metal conductors and are arranged in the dielectric layer 22 at intervals from top to bottom, wherein the electrostatic electrode 24 is disposed near the upper surface of the dielectric layer 22, and the heating electrode 26 is disposed near the lower surface of the dielectric layer 22. The upper surface of dielectric layer 22 serves as the bearing surface for the entire electrostatic chuck 100 for the placement of a wafer to be processed; the electrostatic electrode 24 generates electrostatic attraction to attract the wafer on the carrying surface when the power is on, and the heating electrode 26 generates a large amount of heat when the power is on, so as to rapidly heat the carried wafer to a predetermined temperature.

Dielectric layer 22 is preferably a multi-layer structure comprising a first dielectric layer 22a, a second dielectric layer 22b, and a third dielectric layer 22c disposed in this order from top to bottom, wherein an electrostatic electrode 24 is disposed between first dielectric layer 22a and second dielectric layer 22b, and a heater electrode 26 is disposed between second dielectric layer 22b and third dielectric layer 22 c. The dielectric layers 22a, 22b, and 22c may be formed by sintering or the like, and the electrode layers (i.e., the electrostatic electrode 24 and the heating electrode 26) may be formed on the dielectric layers by screen printing or the like. In this embodiment, the third dielectric layer 22c is first formed, the heater electrode 26 is then formed on the third dielectric layer 22c, the second dielectric layer 22b is then formed on the third dielectric layer 22c and covers the heater electrode 26, the electrostatic electrode 24 is then formed on the second dielectric layer 22b, and the first dielectric layer 22a is finally formed on the second dielectric layer 22b and covers the electrostatic electrode 24. The dielectric layers 22a, 22b, and 22c may be made of the same or different materials and are integrally connected after molding.

The heat dissipation base 40 is mainly used for cooling the main body 20 of the suction cup, and is made of a metal material with a high thermal conductivity coefficient, such as copper, aluminum, copper-aluminum alloy, and the like. Preferably, a flow passage is formed in the heat dissipation base 40, and the flow passage is connected in series with the external refrigeration unit through a pipeline or the like. When the main body 20 needs to be cooled, the refrigerator set is started, and a cooling liquid, such as water, fluoride (such as Freon) and the like, preferably circulates in the pipeline. The heat dissipation base 40 is used as a heat absorption device of the refrigerating unit and exchanges heat with the cooling liquid when the cooling liquid flows through the flow passage; the heat absorbed coolant releases heat to the external environment when flowing to a heat dissipation device, such as a condenser, of the refrigeration unit, and the heat dissipation and cooling of the heat dissipation base 40 are realized by continuous circulation. For simplicity of illustration, the specific structure of the refrigeration unit and the flow passages are not shown in the drawings, and may be arranged as desired.

The heat conductive cavity 30 is disposed between the heat sink base 40 and the chuck body 20 to conduct heat from the chuck body 20 to the heat sink base 40. In the embodiment shown in fig. 1, the heat conducting cavity 30 is formed with a channel 32 on a side thereof adjacent to the chuck body 20, and the channel 32 is connected to an external device, such as a syringe pump, for injecting the heat conducting medium 34 into the channel 32 or pumping the heat conducting medium away from the channel 32. In the illustrated embodiment, the channel 32 extends transversely through the thermally conductive cavity 30 and defines an inlet 36 and an outlet 38 on opposite sides (i.e., left and right sides as shown) of the thermally conductive cavity 30, wherein the inlet 36 is configured to inject the thermally conductive medium 34 into the channel 32 and the outlet 38 is configured to withdraw the thermally conductive medium 34 from the channel 32. In some embodiments, the side of the heat conducting cavity 30 may be provided with only a single opening, both as an inlet for the heat conducting medium 34 to be injected and as an outlet for the heat conducting medium 34 to be extracted. In the illustrated embodiment, the channel 32 of the heat conducting cavity 30 is a semi-closed structure facing the opening of the chuck body 20, and the lower surface of the chuck body 20 (i.e., the bottom surface of the third dielectric layer 22 c) overlaps the top surface of the heat conducting cavity 30 during assembly, and is connected to the heat conducting cavity by welding (e.g., pressure diffusion welding) to form a whole and close the channel 32.

Preferably, the thermal conductive cavity 30 and the third dielectric layer 22c of the chuck body 20 connected thereto are made of the same material, such as alumina ceramic. Thus, the heat conducting cavity 30 has better heat conducting capacity, and the heat conducting coefficient is not lower than 10W/(m.K) within the temperature range of 30-800 ℃; moreover, the thermal conductive cavity 30 and the third dielectric layer 22c have substantially the same thermal expansion coefficient, so that the thermal conductive cavity 30 and the third dielectric layer 22c can be expanded or contracted synchronously during the temperature rise or decrease of the chuck body 20, and the two can be always kept in tight connection.

When the electrostatic chuck 100 of the present embodiment is used, the electrostatic electrode 24 is connected to an external power source through a wire or the like, so as to generate an electrostatic attraction force to fix the wafer onto the first dielectric layer 22a of the chuck body 20, which not only can prevent the wafer from moving or dislocating during the subsequent process, but also can make the wafer completely contact with the first dielectric layer 22a, thereby facilitating the heat conduction therebetween; the heating electrode 26 is also connected to an external power source through a wire or the like, and generates a large amount of heat in the chuck body 20, and the generated heat is conducted upward through the first dielectric layer 22a, thereby heating the wafer to a desired temperature (e.g., 500 ℃) and ensuring the accuracy of the film forming or etching process of the wafer. For simplicity of illustration, an external power source and electrical connections of the electrostatic electrodes 24 and the heater electrodes 26 to the external power source are not shown in the drawings.

During the process of turning on the heating electrode 26, heating the chuck body 20 and heating the wafer, the heat conducting chamber 30 is in a first use state (as shown in fig. 1): the heat transfer medium 34 is absent from the channels 32. At this moment, the channel 32 is equivalent to an air thermal isolation layer, so that the sucker main body 20 and the heat conduction cavity 30 cannot form effective heat conduction, the overall heat conduction performance of the heat conduction cavity 30 is poor, the heat of the sucker main body 20 is difficult to be transferred to the heat dissipation base 40 through the heat conduction cavity 30, the heat loss in the temperature rising process of the sucker main body 20 can be effectively reduced, and the temperature rising rate is improved. Since the heat loss is reduced, more heat can be transferred upward to the wafer, so that the heating power of the heating electrode 26 can be properly reduced, and the overall use cost can be effectively reduced. In some embodiments, when the heat conducting cavity 30 is in the first usage state, a vacuum may be drawn on the channel 32, further enhancing the thermal isolation effect of the channel 32.

When the chuck body 20 needs to be cooled, the heat conducting cavity 30 is in a second use state (as shown in fig. 2): a heat transfer medium 34 is injected into the channel 32. The heat transfer medium 34 is preferably a thermal oil having excellent thermal stability and excellent heat transfer properties, such as an alkylbenzene type (benzenoid type) thermal oil, an alkylnaphthalene type thermal oil, or the like. The sucking disc main part 20 and the heat conduction cavity 30 carry out heat-conduction fast through heat-conducting medium 34 for heat conduction performance on the whole of heat conduction cavity 30 is good, and the heat of sucking disc main part 20 can be through heat conduction cavity 30 to heat dissipation base 40 fast transfer and give off, effectively promotes the cooling rate of sucking disc main part 20. In this embodiment, the bottom surface of the heat conducting cavity 30 is integrally connected to the heat dissipating base 40 by welding (e.g., high temperature brazing), so as to ensure the connection tightness and heat conduction performance between the two.

In the electrostatic chuck 100 of this embodiment, the heat conducting cavity 30 is disposed between the chuck main body 20 and the heat dissipating base 40, the heat conducting cavity 30 forms the channel 32, the channel 32 may be selectively filled or not filled with the heat conducting medium 34 as required, and when the heat conducting medium 34 is not filled, the heat conducting cavity 30 has poor heat conducting performance, so as to slow down the transfer of heat to the heat dissipating base 40, thereby effectively reducing heat loss and enabling the chuck main body 20 to be rapidly heated; when the heat-conducting medium 34 is filled, the heat-conducting cavity 30 has good heat-conducting property, so that the heat is transferred to the heat-radiating base 40 at an accelerated speed, and further the heat-radiating efficiency is effectively improved, and the sucker main body 20 is rapidly cooled. The heat conduction cavity 30 of the electrostatic chuck 100 of the present application can be selectively filled or unfilled with the heat conducting medium 34 as required, and then in different use states and have different heat conduction performances, and the use requirements of temperature rise and temperature reduction are taken into account simultaneously, so that the electrostatic chuck has excellent use effect and wide application prospect.

Fig. 3 shows a second embodiment of the electrostatic chuck 100 of the present application, which is different from the first embodiment mainly in that the heat conducting medium 34 is filled in the channel 32 of the heat conducting cavity 30. In this embodiment, heat-conducting medium 34 is the helium, and the helium is a noble gas, and colorless, tasteless, incombustible and heat conductivity are very strong, can form good heat-conduction between sucking disc main part 20 and heat conduction cavity 30, and the transmission of heat to heat dissipation base 40 is accelerated, and then effectively promotes the radiating efficiency, makes sucking disc main part 20 can rapid cooling. In some embodiments, the heat transfer medium 34 filled in the channel 32 of the heat transfer chamber 30 may be other gases, such as argon, etc., as long as the heat transfer between the chuck body 20 and the heat transfer chamber 30 is improved after filling.

In this embodiment, the heat conducting cavity 30 and the dielectric layer 22 of the chuck body 20 are also made of alumina ceramic material, and they are integrally connected by high temperature sintering and other processes after being stacked. Unlike the previous embodiment, the chuck body 20 is larger than the thermally conductive chamber 30, and can hold larger wafers. The heat conducting cavity 30 and the heat dissipating base 40 may be connected by welding, bonding, or the like. When the heat conducting cavity 30 and the heat radiating base 40 are bonded together, the bonding material used is preferably an elastic silicone heat conducting adhesive, which can provide effective heat conduction between the heat conducting cavity 30 and the heat radiating base 40, and can elastically deform along with expansion and contraction of the heat conducting cavity 30, so as to maintain tight connection between the two.

Fig. 4 shows a third embodiment of the electrostatic chuck 100 of the present application, which is different from the first embodiment mainly in the heat conducting cavity 30.

In this embodiment, the dielectric layer 22 of the chuck body 20 and the thermal conductive cavity 30 are made of aluminum nitride ceramic. The size of the heat conducting cavity 30 is slightly larger than that of the chuck main body 20, and the outer edge of the heat conducting cavity 30 protrudes outwards relative to the chuck main body 20. The center of the heat conducting cavity 30 is concave to form a channel 32, and the size of the channel 32 is smaller than that of the sucker main body 20; the heat conducting cavity 30 is recessed in the chuck body 20 to form a mounting cavity 39, and the mounting cavity 39 is disposed around the channel 32. During assembly, the bottom of the chuck body 20, namely the third dielectric layer 22c is embedded into the assembly cavity 39 of the heat conducting cavity 30, the heat conducting cavity 30 wraps the bottom surface and the outer peripheral surface of the third dielectric layer 22c, a larger contact area is formed between the bottom surface and the outer peripheral surface, and a better sealing effect and a better heat conduction effect are achieved after welding.

In some embodiments, the thermal conductive chamber 30 may be made of other materials, such as metal, polymer, etc., as long as the thermal conductivity is not lower than 10.0W/(m · K) and does not react with the third dielectric layer 22c of the chuck body 20 connected thereto within the operating temperature range of the electrostatic chuck 100. When different materials are used for the thermal conductive cavity 30 and the third dielectric layer 22c, the difference between the thermal expansion coefficients of the two materials is preferably not more than ± 10% in order to avoid problems during temperature rising or temperature lowering.

It should be noted that the present application is not limited to the above embodiments, and other changes and modifications can be made by those skilled in the art according to the spirit of the present application, and all changes and modifications made according to the spirit of the present application are intended to be included within the scope of the present application.

Claims (10)

1. The electrostatic chuck (100) is characterized by comprising a chuck main body (20), a heat dissipation base (40) and a heat conduction cavity (30) arranged between the chuck main body (20) and the heat dissipation base (40), wherein an electrostatic electrode (24) and a heating electrode (26) are arranged in the chuck main body (20), the electrostatic electrode (24) is used for generating electrostatic attraction, the heating electrode (26) is used for generating heat, a channel (32) capable of being connected with the outside is formed in the heat conduction cavity (30), the heat conduction cavity (30) has a first use state with relatively low heat conduction performance and a second use state with relatively high heat conduction performance, a heat conduction medium (34) is not filled in the channel (32) in the first use state, and the heat conduction medium (34) is filled in the channel (32) in the second use state.

2. The electrostatic clamp (100) of claim 1, wherein in the second use state, the heat conducting medium (34) filled in the channel (32) is a heat conducting oil.

3. The electrostatic clamp (100) according to claim 2, wherein in the second use state the heat conducting medium (34) filled in the channel (32) is an alkylbenzene type heat conducting oil or an alkylnaphthalene type heat conducting oil.

4. The electrostatic clamp (100) of claim 1, wherein in the second use state, the heat transfer medium (34) filled in the channel (32) is helium or argon.

5. The electrostatic clamp (100) of claim 1, wherein said channel (32) is evacuated in a first condition of use.

6. The electrostatic clamp (100) of claim 1, wherein said channel (32) extends transversely through said thermally conductive chamber (30) and defines an inlet (36) and an outlet (38) on opposite sides of said thermally conductive chamber (30) in the transverse direction.

7. The electrostatic chuck (100) of any of claims 1 to 6, wherein the chuck body (20) further comprises a first dielectric layer (22 a), a second dielectric layer (22 b), and a third dielectric layer (22 c) disposed in sequence, the electrostatic electrode (24) is disposed between the first dielectric layer (22 a) and the second dielectric layer (22 b), the heater electrode (26) is disposed between the second dielectric layer (22 b) and the third dielectric layer (22 c), and the third dielectric layer (22 c) is connected to the thermally conductive cavity (30) and has a coefficient of thermal expansion that does not deviate by more than ± 10%.

8. The electrostatic chuck (100) of claim 7, wherein said thermally conductive cavity (30) is aluminum nitride, aluminum oxide, metal or a polymer material having a thermal conductivity of not less than 10W/(m-K).

9. The electrostatic clamp (100) of claim 7, wherein said thermally conductive cavity (30) is welded to said third dielectric layer (22 c) or is sintered; the heat conduction cavity (30) is connected with the heat dissipation base (40) in a welding mode or is bonded through heat conduction glue.

10. The electrostatic chuck (100) of claim 7, wherein said thermally conductive cavity (30) is larger in size than said chuck body (20), said third dielectric layer (22 c) being at least partially embedded in said thermally conductive cavity (30).

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