JP6133813B2 - Adhesive for wafer heating apparatus and wafer heating apparatus using the same - Google Patents

Description

The present invention is, for example, relates to a wafer heating equipment using adhesive and this for wafer heating apparatus for heating and fixing a semiconductor wafer.

  Conventionally, in a semiconductor manufacturing apparatus, a process such as dry etching (for example, plasma etching) is performed on a semiconductor wafer (for example, a silicon wafer). In order to improve processing accuracy such as dry etching, it is necessary to securely fix the semiconductor wafer. Therefore, as a wafer heating apparatus for fixing and heating a semiconductor wafer, an electrostatic chuck for fixing the semiconductor wafer by electrostatic attraction and a vacuum chuck for fixing the semiconductor wafer by vacuum suction are known.

  An electrostatic chuck includes, for example, a base member and a suction support member provided with a suction electrode and a heater. The base member and the adsorption support member are joined using an adhesive. The electrostatic chuck is configured so that the semiconductor wafer can be sucked and supported on the suction surface of the suction support member by electrostatic attraction generated when a voltage is applied to the suction electrode.

  By the way, when processing such as etching is performed on the semiconductor wafer, the semiconductor wafer is heated by a heater provided on the suction support member. The electrostatic chuck is required to have a small temperature variation (thermal uniformity) on the suction surface of the suction support member in order to improve processing accuracy such as etching. For example, in Patent Document 1, two adhesive layers are provided between a base member and an adsorption support member for the purpose of improving the heat uniformity of the adsorption support member, and one of them is a flat filler (filling). A method of containing a material) is disclosed.

International Publication No. 2010/061740

  However, in Patent Document 1, since the adhesive layer contains a flat filler, the thermal conductivity of the adhesive layer increases, the heat of the heater diffuses, and the heat equalization of the adsorption support member (particularly the adsorption surface). Will fall. Moreover, since the particle size of a filler is large, a filler tends to settle in the adhesive before hardening, and the bias of a filler arises within an adhesive agent (for example, up and down). Therefore, the characteristics of the adhesive change depending on the location, and the reliability of the adhesive is lowered.

The present invention has been made in view of such a background, and can improve the heat uniformity and flatness of the adsorption support member, and has an excellent reliability for a wafer heating apparatus and a wafer heating apparatus using the same. Is intended to provide a place.

  A first aspect of the present invention is an adhesive used for a wafer heating apparatus including a base member and an adsorption support member provided with a heater, for bonding the base member and the adsorption support member. Wafer heating, comprising at least a matrix resin and an inorganic filler dispersed in the matrix resin, wherein at least a part of the inorganic filler is hollow particles having a hollow interior In the adhesive for the device.

  The adhesive for the wafer heating device contains an inorganic filler dispersed in a matrix resin. And the inorganic filler contains the hollow particle whose inside is hollow at least in part. Therefore, it is possible to reduce the thermal conductivity of the inorganic filler, and further to reduce the thermal conductivity of the entire adhesive including the inorganic filler. Thereby, it can suppress that the heat | fever of the heater provided in the adsorption | suction support member diffuses through an adhesive agent, and can improve the thermal uniformity of an adsorption | suction support member (adsorption surface which adsorb | sucks a to-be-adsorbed object).

  In addition, since the inorganic filler contains hollow particles, the elastic modulus of the inorganic filler can be reduced, and further, the elastic modulus of the entire adhesive including the inorganic filler can be reduced. Thereby, the stress resulting from the difference in thermal expansion coefficient between the base member and the adsorption support member can be relaxed by the adhesive. And deformation | transformation, such as a curvature of an adsorption | suction support member, can be suppressed and the flatness of an adsorption | suction support member (adsorption surface which adsorb | sucks a to-be-adsorbed object) can be improved.

  Further, the hollow particles have a lower density than the solid particles, and the sedimentation rate in the adhesive is slow. Therefore, it is possible to suppress the unevenness of the inorganic filler in the adhesive and to prevent the characteristics from changing in the adhesive (for example, up and down). Thereby, the reliability of an adhesive agent can be improved and the above-mentioned effect of improving the thermal uniformity and flatness of the adsorption support member can be sufficiently obtained.

  A second aspect of the present invention includes a base member and an adsorption support member provided with a heater, and the base member and the adsorption support member are bonded using an adhesive for the wafer heating device. In the wafer heating apparatus,

  The wafer heating apparatus includes a base member and a suction support member. Both are joined using the adhesive for a wafer heating apparatus described above. That is, it is joined using an adhesive having excellent reliability that can improve the heat uniformity and flatness of the adsorption support member. Therefore, it is possible to improve the heat uniformity and flatness of the adsorption support member (the adsorption surface that adsorbs the object to be adsorbed). In addition, the reliability of the adhesive can be increased.

Thus, according to the present invention, to provide a uniform can increase the heat-flatness, the adhesive and the wafer heating equipment using the same for wafer heating apparatus having excellent reliability of the suction support member Can do.

  Further, the adhesive for the wafer heating device includes, for example, all of the state before curing the matrix resin, the state of semi-curing, the state after curing, and the like. In addition, as described above, at least a part of the inorganic filler is hollow particles having a hollow inside. The particles other than the hollow particles are, for example, solid particles having a solid inside. The hollow particles can be produced using various conventionally known methods.

  Moreover, it is preferable that the shape of the said hollow particle is spherical. In this case, there is less risk of damaging the base member and the adsorption support member than when the hollow particles are, for example, plate-like or fiber-like. Moreover, if it is the same content, since the heat conductivity of an adhesive agent will become low compared with the case of plate shape or a fiber form, the thermal uniformity of an adsorption | suction support member can further be improved. In addition, if the content is the same, the elastic modulus of the adhesive is lower than when it is in the form of a plate or fiber, so the stress caused by the difference in thermal expansion coefficient between the base member and the adsorption support member is further relaxed. And the flatness of the suction support member can be further increased.

  Note that the shape of the hollow particles being “spherical” includes not only a true spherical shape but also a shape approximating a true spherical shape. That is, it means that 90% or more of the entire hollow particles are in the range of form factors 1 to 1.4. Here, the shape factor is calculated from the average value of the ratio of the major axis and the minor axis orthogonal to the major axis of an arbitrary number (for example, several hundreds) of particles magnified and observed with a scanning electron microscope (SEM) or the like. Can do. Therefore, if only perfect spherical particles are used, the shape factor is 1, and the more the shape factor deviates from 1, the more non-spherical.

  Moreover, it is preferable that the shape of the hollow part in the said hollow particle is an indefinite shape. In this case, due to uneven density inside the hollow particles, the hollow particles easily rotate when the hollow particles settle in the adhesive. For this reason, the hollow particles easily interfere with surrounding resin (matrix resin) and particles (particles constituting the inorganic filler), and the sedimentation rate of the hollow particles becomes slow. Thereby, the bias | inclination of the inorganic filler in an adhesive agent and the change of the characteristic accompanying it can be prevented further, and the reliability of an adhesive agent can further be improved. The “indefinite shape” means that the above-mentioned shape factor exceeds 1.4.

  Further, in the hollow particles, it is preferable that the hollow portion is in a central portion of the hollow particles. Furthermore, it is preferable that parts other than the hollow part are dense. In this case, the matrix resin is prevented from entering the hollow portion, and the effect of the hollow particles having the hollow portion can be sufficiently obtained.

  Moreover, it is preferable that at least a part of the hollow particles have a particle size of 5 μm or more. That is, hollow particles having a large particle size have a greater contribution to lowering the thermal conductivity and lowering the elastic modulus, and the settling rate in the adhesive is also slower. Therefore, by including hollow particles having a particle size of 5 μm or more, it is possible to reduce the thermal conductivity and the low elastic modulus of the inorganic filler (adhesive), and to increase the thermal uniformity and flatness of the adsorption support member. . In addition, it is possible to prevent the bias of the inorganic filler in the adhesive and the change in the characteristics associated therewith, and to improve the reliability of the adhesive.

  The particle size of the hollow particles is usually 50 μm or less, preferably 100 μm or less at the maximum. When the particle diameter of the hollow particles is increased with respect to the thickness of the adhesive (for example, the coating thickness), the amount of the matrix resin is reduced by that amount, and the strength of the adhesive may be reduced.

  In the inorganic filler, the proportion of the hollow particles is preferably 5% or less when the particle size is less than 5 μm, and 10% or more when the particle size is 5 μm or more. That is, particles having a particle size of less than 5 μm have a small effect on the unevenness of the inorganic filler in the adhesive because the sedimentation rate in the adhesive is slow even if the inside is not hollow. On the other hand, if it is hollow, the shape of the entire particle is not spherical, and the filling property may be lowered, or the viscosity of the adhesive may be increased. Therefore, it is preferable that the ratio of the hollow particles is not more than the specific ratio.

  On the other hand, particles having a particle size of 5 μm or more have a large contribution to lower thermal conductivity and lower elastic modulus if the inside is hollow. Therefore, it is preferable that the ratio of the hollow particles is not less than the specific ratio. The ratio of the hollow particles can be determined by, for example, observing the cured adhesive with a scanning electron microscope (SEM).

  In the inorganic filler, the proportion of particles having a particle size of 5 μm or more is preferably 30% or more and 80% or less when integrated by volume or mass. In this case, the above-described effect due to the inclusion of hollow particles having a large particle size (for example, a particle size of 5 μm or more) can be sufficiently obtained. That is, the thermal conductivity and the low elastic modulus of the inorganic filler (adhesive) can be reduced, and the heat uniformity and flatness of the adsorption support member can be increased. In addition, it is possible to prevent the bias of the inorganic filler in the adhesive and the change in the characteristics associated therewith, and to improve the reliability of the adhesive.

  In the inorganic filler, when the ratio of particles having a particle size of 5 μm or more is integrated by volume or mass and is less than 30%, the strength of the adhesive may not be sufficiently ensured by the inorganic filler. . Furthermore, since the surface area of the inorganic filler is increased, moisture in the air is likely to be adsorbed, and it is easily affected by the production and storage environment of the inorganic filler, which may make it difficult to stably produce the adhesive. On the other hand, when the ratio of particles having a particle diameter of 5 μm or more is integrated by volume or mass and exceeds 80%, mixing of the matrix resin and the inorganic filler may be difficult.

  In the inorganic filler, the proportion of particles having a particle size of 1 μm or less is preferably 10% or more and 40% or less when integrated by volume or mass. In this case, by containing a certain amount of particles having a small particle size, the fluidity of the adhesive can be reduced, and sedimentation of particles having a large particle size can be suppressed. Thereby, the bias | inclination of the inorganic filler in an adhesive agent and the change of the characteristic accompanying it can be prevented, and the reliability of an adhesive agent can be improved.

  In the inorganic filler, when the ratio of particles having a particle size of 1 μm or less is integrated by volume or mass and is less than 10%, the fluidity of the adhesive is lowered and sedimentation of particles having a large particle size is suppressed. The effect may not be obtained sufficiently. On the other hand, when the proportion of particles having a particle size of 1 μm or less exceeds 40% by volume or mass, the fluidity of the adhesive is too low, and the kneading or adhesive of the matrix resin and the inorganic filler It may be difficult to apply the coating.

  The inorganic filler preferably has at least two peaks in the particle size distribution. In this case, for example, it is possible to achieve both the effect of including particles (hollow particles) having a large particle size and the effect of including particles having a small particle size. Further, for example, by mixing inorganic fillers having different particle size distributions so as to have two peaks, it becomes easy to control the particle size distribution of the inorganic fillers and to adjust the viscosity of the adhesive.

  The adhesive may be formed in a sheet shape having a predetermined thickness. In this case, handling of the adhesive becomes easy, and workability at the time of joining the base member and the suction support member can be improved. The sheet-like adhesive here includes, for example, all the states before the matrix resin curing, the semi-cured state, the cured state, and the like.

  The thermal conductivity of the adhesive is preferably 0.2 to 1.2 W / (m · K). In this case, low thermal conductivity of the adhesive can be realized, the heat of the heater provided on the adsorption support member can be prevented from diffusing through the adhesive, and the heat uniformity of the adsorption support member can be improved. The thermal conductivity of the adhesive can be set in consideration of, for example, the temperature distribution of the adsorption support member (adsorption surface that adsorbs the object to be adsorbed), the temperature increase rate, the temperature decrease rate, the thickness of the adhesive, and the like. .

  Moreover, content of the said inorganic filler in the said adhesive agent can be 3-50 volume%, for example. What is necessary is just to set content of an inorganic filler so that an adhesive agent may become desired heat conductivity, for example.

  In the adhesive, for example, an epoxy resin, a silicone resin, an acrylic resin, an epoxy acrylate resin, a urethane acrylate resin, or the like can be used as the matrix resin.

  Examples of the inorganic filler include alumina, silica, aluminum nitride, silicon nitride, aluminosilicate, zirconia, titania, barium sulfate, calcium carbonate, mica, and carbon black. Of these, particularly inexpensive and durable alumina and silica are preferable. Moreover, these may be used independently and may mix and use 2 or more types.

  Moreover, the said wafer heating apparatus WHEREIN: The said adsorption | suction support member can have a ceramic insulator, and can be set as the structure which provided the heater in the ceramic insulator. Examples of the material constituting the ceramic insulator include alumina, aluminum nitride, and yttria. Of these, alumina is excellent in terms of strength and wear resistance. Aluminum nitride is excellent in terms of thermal conductivity. Yttria has excellent plasma resistance.

  Moreover, as a material which comprises a base member, metal materials, such as aluminum, titanium, and these alloys, are mentioned, for example. Among these, aluminum and its alloys are excellent in workability and cost. Titanium and its alloys have a small coefficient of thermal expansion, and can suppress stress caused by a difference in coefficient of thermal expansion with the ceramic constituting the adsorption support member.

In addition, about the sedimentation rate of the inorganic filler (hollow particle) in an adhesive agent, it can be considered using the Stokes formula showing the sedimentation rate at the time of particle | grains sedimenting in the fluid. The Stokes equation is expressed by v = ((ρ _s −ρ _w ) · g / 18η) · d ² . However, in the formula, v: particle sedimentation velocity (m / s), ρ _s : particle density (kg / m ³ ), d: particle diameter (m), ρ _w : fluid (matrix resin) density ( kg / m ³ ), η: viscosity (Pa · s) of fluid (matrix resin), and g: acceleration of gravity (m / s ² ).

From the Stokes' formula, hollow particles have a lower particle density ρ _s than solid particles, and therefore the sedimentation velocity v of the particles is slow. In addition, since the sedimentation speed v of particles increases as the particle diameter d increases, the effect of slowing the sedimentation speed v of particles (suppressing sedimentation) increases when the particles having a large particle diameter d are hollow.

It is a perspective view which shows the structure of a wafer heating apparatus (electrostatic chuck). It is sectional drawing which shows the structure of a wafer heating apparatus (electrostatic chuck). It is the photograph which observed the cross section of the adhesive agent by SEM. It is a graph which shows the particle size distribution of an inorganic filler. It is a graph which shows the relationship between an alumina addition amount and thermal conductivity.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
First, the wafer heating apparatus of this embodiment will be described.

  As shown in FIGS. 1 and 2, the wafer heating device (electrostatic chuck) 1 includes a base member 3 and an adsorption support member 2 provided with a heater 22. The base member 3 and the adsorption support member 2 are joined using an adhesive (adhesive layer 4). This will be described in detail below.

  As shown in the figure, the electrostatic chuck 1 is for adsorbing and supporting a semiconductor wafer as an object to be adsorbed 8, and is made of a metal base member 3 and an adsorbing support member disposed on the base member 3. 2 are provided. The base member 3 and the suction support member 2 are joined together by an adhesive layer 4 disposed between them. The adhesive layer 4 is composed of an adhesive described later. Hereinafter, in the present embodiment, the suction support member 2 side is described as the upper side, and the base member 3 side is described as the lower side.

  Inside the electrostatic chuck 1, there is provided a cooling gas supply path 51 serving as a supply path for a cooling gas such as helium for cooling the object (semiconductor wafer) 8. The adsorption surface 201 described later of the adsorption support member 2 is provided with a plurality of cooling openings 52 formed by opening the cooling gas supply passage 51, and the cooling gas supplied from the cooling openings 52 is adsorbed on the adsorption surface 201. An annular cooling groove 53 formed so as to spread over the whole is provided.

  As shown in the figure, the suction support member 2 has a circular plate shape. The upper surface of the adsorption support member 2 is an adsorption surface 201 that adsorbs an object to be adsorbed (semiconductor wafer) 8. Further, the adsorption support member 2 has an electrically insulating ceramic insulator 20. The ceramic insulator 20 is configured by laminating a plurality of ceramic layers (not shown). Each ceramic layer is made of an alumina sintered body containing alumina as a main component.

  Inside the ceramic insulator 20, an adsorption electrode 21 is disposed. The adsorption electrode 21 is connected to an electrode power source (not shown) via an electrode connection terminal (not shown). The attracting electrode 21 generates an electrostatic attractive force when a DC high voltage is applied, and the electrostatic attracting force attracts the object to be attracted (semiconductor wafer) 8 to the attracting surface 201 of the attracting support member 2 to support / Fix it. The adsorption electrode 21 is made of tungsten or molybdenum.

  A heater (heating element) 22 is disposed inside the ceramic insulator 20. The heater 22 is arranged in a spiral on substantially the same plane on the base member 3 side with respect to the adsorption electrode 21. The heater 22 is connected to a heater power supply (not shown) via a heater connection terminal (not shown).

  As shown in the figure, the base member 3 is made of aluminum or an aluminum alloy. Inside the base member 3, for example, a refrigerant flow path 31 serving as a space for circulating a refrigerant such as a fluorinated liquid or pure water is provided. The refrigerant flow path 31 is configured so that refrigerant can be introduced and discharged. The suction support member 2 is disposed on the upper surface 301 of the base member 3 with the adhesive layer 4 interposed therebetween.

Next, the adhesive of this embodiment will be described.
As shown in FIGS. 3A and 3B, the adhesive 40 contains at least a matrix resin 41 and an inorganic filler 42 dispersed in the matrix resin 41. At least a part of the inorganic filler 42 is hollow particles 421 whose inside is hollow. 3A and 3B are SEM photographs of the cross section of the adhesive 40 after curing, and are photographs of different parts of the same sample. This will be described in detail below.

  As shown in the figure, the adhesive 40 is formed by dispersing an inorganic filler 42 in a matrix resin 41. An epoxy resin is used as the matrix resin 41. In this embodiment, a thermosetting epoxy resin containing a thermosetting curing agent is used. As the inorganic filler 42, alumina particles are used.

  The content of the inorganic filler 42 in the adhesive 40 is 3 to 50% by volume. The thermal conductivity of the adhesive 40 is 0.2 to 1.2 W / (m · K). Note that the content of the inorganic filler 42 in the adhesive 40 can be set so that the adhesive 40 has a desired thermal conductivity.

  The inorganic filler 42 includes hollow particles 421 in a part thereof. The hollow particle 421 is a particle having a hollow inside and has a hollow portion 422. In the inorganic filler 42, the particles other than the hollow particles 421 are solid particles having a solid inside. In the inorganic filler 42, the ratio of the hollow particles 421 is 5% or less when the particle size is less than 5 μm, and 10% or more when the particle size is 5 μm or more.

  The hollow particle 421 has a spherical shape. On the other hand, the shape of the hollow part 422 in the hollow particle 421 is not spherical but an indefinite shape. Some hollow particles 421 have one hollow portion 422, while others have a plurality of hollow portions 422. In addition, the hollow portion 422 may be in the central portion of the hollow particle 421, and some may not. Further, in the hollow particle 421, the portion other than the hollow portion 422 is dense.

  In the inorganic filler 42, the proportion of particles having a particle size (particle size) of 5 μm or more is 30 to 80% when integrated by volume (or mass). A part of the hollow particles 421 has a particle size of 5 μm or more. Further, the proportion of particles having a particle size of 1 μm or less is 10 to 40% when integrated by volume (or mass).

  Here, the particle size distribution of the inorganic filler 42 is shown in FIG. The particle size distribution was measured by a scattering type particle size distribution measuring method by laser diffraction. In the figure, the horizontal axis represents the particle diameter, and the vertical axis represents the ratio (volume%). As shown in the figure, the inorganic filler 42 has two peaks in the particle size distribution: a peak in the vicinity of a particle diameter of 1 μm and a peak slightly beyond the particle diameter of 10 μm. That is, particles having a small particle size and particles having a large particle size are mixed.

  The hollow particles 421 can be produced as follows. In other words, aluminum fine powder is dispersed in an oxygen stream and oxidized by ignition. At this time, since the metal and oxide become liquid by reaction heat, they become spherical by surface tension. By cooling this, fine spherical particles can be obtained. From aluminum, true spherical particles of alumina are obtained. Since some of the particles (particularly large particles having a particle diameter of 5 μm or more) take in outside air when they become spherical, voids are formed inside. By variously controlling the pressure, temperature, amount of powder, and the like, the particle diameter and the shape of the holes can be changed, and hollow particles 421 having non-spherical holes (hollow part 422) can be obtained.

Next, a method for joining the adsorption support member 2 and the base member 3 will be described.
First, a predetermined amount of alumina particles as the inorganic filler 42 is added to the thermosetting epoxy resin as the matrix resin 41 to produce a paste-like adhesive 40. Then, the adhesive 40 is applied to the upper surface 301 of the base member 3 (the bonding surface with the suction support member 2).

  Next, the suction support member 2 is placed on the adhesive 40 applied to the upper surface 301 of the base member 3. Then, a weight is placed on the suction support member 2 and pressed from above. Then, it heats at predetermined | prescribed temperature in air | atmosphere, the adhesive agent 40 is hardened, and the contact bonding layer 4 which consists of the adhesive agent 40 after hardening is formed. Thereby, the adsorption support member 2 and the base member 3 are joined.

Next, the effect of this embodiment is demonstrated.
The adhesive 40 of this embodiment contains an inorganic filler 42 dispersed in a matrix resin 41. And the inorganic filler 42 contains the hollow particle 421 whose inside is hollow at least in part. Therefore, it is possible to reduce the thermal conductivity of the inorganic filler 42 and further reduce the thermal conductivity of the entire adhesive 40 including the inorganic filler. Accordingly, the heat of the heater 22 provided on the adsorption support member 2 is prevented from diffusing through the adhesive 40 (adhesive layer 4), and the adsorption support member 2 (the adsorption surface 201 that adsorbs the object to be adsorbed 8) is suppressed. Soaking can be improved.

  In addition, since the inorganic filler 42 includes the hollow particles 421, the elastic modulus of the inorganic filler 42 can be reduced, and further, the elastic modulus of the entire adhesive 40 including the inorganic filler 42 can be reduced. Thereby, the stress resulting from the difference in coefficient of thermal expansion between the base member 3 and the adsorption support member 2 can be relaxed by the adhesive 40 (adhesive layer 4). And deformation | transformation, such as curvature of the adsorption | suction support member 2, can be suppressed and the flatness of the adsorption | suction support member 2 (adsorption surface 201 which adsorb | sucks the to-be-adsorbed object 8) can be raised.

  In addition, the hollow particles 421 have a lower density than the solid particles, and the sedimentation rate in the adhesive 40 is slow. Therefore, it is possible to suppress the unevenness of the inorganic filler 42 in the adhesive 40 and to prevent the characteristics from changing in the adhesive 40 (for example, up and down). Thereby, the reliability of the adhesive 40 can be improved, and the above-described effect of improving the heat uniformity and flatness of the adsorption support member 2 can be sufficiently obtained.

  Moreover, in the adhesive 40 of this embodiment, the shape of the hollow particle 421 is spherical. Therefore, there is less risk of damaging the base member 3 and the adsorption support member 2 than when the hollow particles 421 are plate-like or fiber-like, for example. Moreover, if it is the same content, since the heat conductivity of the adhesive agent 40 will become low compared with the case where it is plate shape or fiber shape, the thermal uniformity of the adsorption | suction support member 2 can further be improved. In addition, if the content is the same, the elastic modulus of the adhesive 40 is lower than when it is in the form of a plate or fiber, and therefore stress caused by the difference in thermal expansion coefficient between the base member 3 and the adsorption support member 2 is reduced. The degree of flatness of the suction support member 2 can be further increased.

  Moreover, the shape of the hollow part 422 in the hollow particle 421 is an indefinite shape. Due to the density unevenness inside the hollow particles 421, the hollow particles 421 easily rotate when the hollow particles 421 settle in the adhesive 40. For this reason, the hollow particles 421 easily interfere with surrounding resin (matrix resin 41) and particles (particles constituting the inorganic filler 42), and the sedimentation speed of the hollow particles 421 becomes slow. Thereby, the bias | inclination of the inorganic filler 42 in the adhesive agent 40 and the change of the characteristic accompanying it can be prevented further, and the reliability of the adhesive agent 40 can further be improved.

  The hollow particles 421 include those in which the hollow portion 422 is at the center of the hollow particle 421. Further, in the hollow particle 421, the portion other than the hollow portion 422 is dense. Therefore, the matrix resin 41 is prevented from entering the hollow portion 422, and the effect of the hollow particles 421 having the hollow portion 422 can be sufficiently obtained.

  A part of the hollow particles 421 has a particle size of 5 μm or more. That is, the hollow particle 421 having a larger particle size has a greater contribution to lowering the thermal conductivity and lowering the elastic modulus, and the settling rate in the adhesive 40 is also slower. Therefore, by including the hollow particles 421 having a particle size of 5 μm or more, the inorganic filler 42 (adhesive 40) can have a low thermal conductivity and a low elastic modulus, and the adsorption support member 2 can have a uniform thermal uniformity and flatness. Can be increased. In addition, it is possible to prevent the bias of the inorganic filler 42 in the adhesive 40 and the change in the characteristics associated therewith, and improve the reliability of the adhesive 40.

  In the inorganic filler 42, the ratio of the hollow particles 421 is 5% or less when the particle size is less than 5 μm, and 10% or more when the particle size is 5 μm or more. Therefore, the above-described effects due to the inclusion of the hollow particles 421 can be sufficiently obtained.

  In the inorganic filler 42, the proportion of particles having a particle size of 5 μm or more is 30% or more and 80% or less when integrated by volume (or mass). Therefore, the above-mentioned effect due to the inclusion of the hollow particles 421 having a large particle size (for example, a particle size of 5 μm or more) can be sufficiently obtained.

  In the inorganic filler 42, the proportion of particles having a particle size of 1 μm or less is 10% or more and 40% or less when integrated by volume (or mass). By containing a certain amount of particles having a small particle size, the fluidity of the adhesive 40 can be reduced, and sedimentation of particles having a large particle size can be suppressed. Thereby, the bias | inclination of the inorganic filler 42 in the adhesive agent 40 and the change of the characteristic accompanying it can be prevented, and the reliability of the adhesive agent 40 can be improved.

  The inorganic filler 42 has two peaks in the particle size distribution. Therefore, it is possible to achieve both the effect of including particles having a large particle size (hollow particle 421) and the effect of including particles having a small particle size. Further, by mixing the inorganic fillers 42 having different particle size distributions, the control of the particle size distribution of the inorganic fillers 42 and the adjustment of the viscosity of the adhesive 40 are facilitated.

  The thermal conductivity of the adhesive 40 is 0.2 to 1.2 W / (m · K). Therefore, a low thermal conductivity of the adhesive 40 can be realized, the heat of the heater 22 provided on the adsorption support member 2 can be prevented from diffusing through the adhesive 40 (adhesive layer 4), and the level of the adsorption support member 2 can be reduced. Thermal property can be increased.

  Further, the wafer heating apparatus (electrostatic chuck) 1 of this embodiment includes a base member 3 and an adsorption support member 2. Both are joined using the adhesive 40 described above. That is, the adhesive support member 2 is joined using the highly reliable adhesive 40 that can improve the heat uniformity and flatness. Therefore, it is possible to improve the heat uniformity and flatness of the adsorption support member 2 (the adsorption surface 201 that adsorbs the object 8 to be adsorbed). Further, the reliability of the adhesive 40 can be increased.

  As described above, according to the present embodiment, the adhesive 40 excellent in reliability that can improve the heat uniformity and flatness of the suction support member 2 (suction surface 201), and the wafer heating device (static An electric chuck) 1 can be provided.

(Experimental example)
In this experimental example, the thermal conductivity of the adhesive was measured when alumina particles (inorganic filler) having the particle size distribution shown in FIG. 4 were added to the epoxy resin (matrix resin). The thermal conductivity was measured by a hot wire method. The result is shown in FIG. As can be seen from the figure, a thermal conductivity of 1.2 W / (m · K) is realized when the amount of alumina added is 50 vol% or less.

(Other embodiments)
The present invention is not limited to the above-described embodiments and experimental examples, and it goes without saying that the present invention can be implemented in various modes without departing from the present invention.

  (1) In the said embodiment, although the paste-form adhesive agent was used, the adhesive agent may be formed in the sheet form which has predetermined | prescribed thickness, for example. In this case, handling of the adhesive becomes easy, and workability at the time of joining the base member and the suction support member can be improved. Here, the sheet-like adhesive includes all of a state before curing, a state of semi-curing, a state after curing, and the like.

  (2) In the above-described embodiment, the adhesive (adhesive layer) is disposed between the suction support member and the base member so as to be in direct contact with the suction support member and the base member. Between the adhesive layer) and the adsorption support member, between the adhesive (adhesive layer) and the base member, from a metal plate such as an aluminum plate or a stainless steel plate, a glass plate such as a carbon fiber substrate, a graphite substrate, or a quartz substrate. Other layers such as a thermal diffusion layer may be disposed. And you may arrange | position an adhesive agent (adhesion layer) between other layers, such as an adsorption | suction support member and a thermal diffusion layer, and other layers, such as a base member and a thermal diffusion layer.

  (3) In the above embodiment, the adhesive (adhesive layer) is disposed so as to be in direct contact with the ceramic insulator of the adsorption support member. For example, the surface of the ceramic insulator (surface on the base member side) ), A heater may be provided, and the adhesive (adhesive layer) may be disposed in direct contact with the heater.

  (4) In the above embodiment, the adhesive is used for the electrostatic chuck. Specifically, although it was used for joining the base member of the electrostatic chuck and the suction support member, for example, an adhesive may be used for other wafer heating devices such as a vacuum chuck. Similar to the electrostatic chuck, the vacuum chuck includes a base member and a suction support member, and has a suction hole that allows the suction support member to be evacuated.

  (5) In the above-described embodiment, in the adsorption support member, the adsorption electrode and the heater are provided inside the ceramic insulator. However, the adsorption electrode and the heater may be provided on the surface of the ceramic insulator. In this case, for example, a film heater in which a heater is provided on an insulating film made of polyimide or the like can be used as the heater.

  (6) Although alumina particles are used as the inorganic filler in the embodiment, for example, silica particles or the like may be used. Further, silica particles can be obtained from silicon by the same method as the above-described method for producing alumina particles.

1 ... Wafer heating device (electrostatic chuck)
DESCRIPTION OF SYMBOLS 2 ... Adsorption support member 21 ... Electrode for adsorption 22 ... Heater 3 ... Base member 40 ... Adhesive 41 ... Matrix resin 42 ... Inorganic filler 421 ... Hollow particle

Claims (15)

An adhesive for joining the base member and the suction support member, used in a wafer heating apparatus including a base member and a suction support member provided with a heater,
Containing at least a matrix resin and an inorganic filler dispersed in the matrix resin;
An adhesive for a wafer heating apparatus, wherein at least a part of the inorganic filler is hollow particles having a hollow interior.   The adhesive for a wafer heating apparatus according to claim 1, wherein the hollow particles have a spherical shape.   The adhesive for a wafer heating apparatus according to claim 1 or 2, wherein a shape of a hollow portion in the hollow particle is an indefinite shape.   The adhesive for a wafer heating apparatus according to any one of claims 1 to 3, wherein a particle diameter of at least a part of the hollow particles is 5 µm or more.   The said inorganic filler WHEREIN: The ratio of the particle | grains with a particle size of 5 micrometers or more is 30% or more and 80% or less when integrated | accumulated by a volume or mass, The any one of Claims 1-4 characterized by the above-mentioned. Adhesive for wafer heating equipment.   The ratio of particles having a particle size of 1 μm or less in the inorganic filler is 10% or more and 40% or less when integrated by volume or mass. Adhesive for wafer heating equipment.   It is formed in the sheet form which has predetermined | prescribed thickness, The adhesive agent for wafer heating apparatuses of any one of Claims 1-6 characterized by the above-mentioned. The adhesive for a wafer heating apparatus according to any one of claims 1 to 7, further comprising a hollow portion at a central portion in the hollow particles. The adhesive for a wafer heating apparatus according to any one of claims 1 to 8, wherein a particle diameter of the hollow particles is at most 100 µm or less. The adhesive for a wafer heating apparatus according to any one of claims 1 to 9, wherein the thermal conductivity is 0.2 to 1.2 W / (m · K). 11. The wafer heating according to claim 1, wherein the inorganic filler has two peaks in a particle size distribution measured by a scattering particle size distribution measuring method by laser diffraction. Adhesive for equipment. Content of the said inorganic filler in the said adhesive agent is 3-50 volume%, The adhesive agent for wafer heating apparatuses of any one of Claims 1-11 characterized by the above-mentioned. A base member;
An adsorption support member provided with a heater,
Wherein the base member and the suction support member, the wafer heating apparatus characterized by being joined with an adhesive for wafer heating apparatus according to any one of claims 1 to 12. The wafer heating apparatus according to claim 13, wherein the adsorption support member includes a ceramic insulator, and an adsorption electrode is disposed inside the ceramic insulator. The adsorption support member has a ceramic insulator, and a heater is provided on the surface of the ceramic insulator on the base member side,
  The wafer heating apparatus according to claim 13, wherein the adhesive is disposed so as to be in direct contact with the heater.