JP7746199B2 - Sample holder - Google Patents

Description

This disclosure relates to sample holders such as wafer heating devices.

For example, the configuration described in Patent Document 1 is known as a sample holder. The sample holder described in Patent Document 1 comprises an electrostatic chuck portion with an electrode inside, a temperature control base portion with a through-hole, an insulator located within the through-hole, and a power supply terminal located within the insulator that supplies electricity to the electrode; the temperature control base portion, the insulator, and the electrostatic chuck portion are bonded together with an adhesive layer.

Patent Publication No. 2016-171185

When the insulating portion of the electrostatic chuck portion of a sample holder experiences dielectric breakdown, the current from the power supply terminal flows through the insulating portion to the metal member, reducing the clamping force of the electrode. Dielectric breakdown occurs when the voltage applied to the insulating portion exceeds a certain limit, i.e., when it exceeds the dielectric breakdown voltage. This dielectric breakdown voltage varies depending on the length of the current path, assuming the same electric field strength. Current tends to travel along the shortest path through areas with the lowest resistance, so it travels along the interface between the electrostatic chuck portion and the adhesive layer. Therefore, when the current path is short, the dielectric breakdown voltage is lower than when the current path is long, making dielectric breakdown more likely to occur.

Since modern sample holders need to have excellent adhesive strength over long periods of time, they are required to have low dielectric breakdown and excellent durability.

The sample holder of the present disclosure comprises a ceramic substrate, an electrode, a cylindrical body, a first adhesive layer, a power supply terminal, a metal member, and a second adhesive layer. The ceramic substrate has a first surface and a second surface opposite the first surface, and the second surface has a recess. The electrode is located inside the ceramic substrate. The cylindrical body has a third surface opposite the second surface. The first adhesive layer is located in contact with at least the second and third surfaces. The power supply terminal is located inside the cylindrical body and connected to the electrode. The metal member has a fourth surface opposite the second surface and is located surrounding the outer peripheral surface of the cylindrical body. The second adhesive layer is located in contact with the outer peripheral surface, the second surface, and the fourth surface. The recess is located so that at least a portion of it overlaps the third surface when viewed from above toward the first surface, and the first adhesive layer is located in the recess.

The sample holder of one embodiment of the present disclosure has excellent durability.

FIG. 2 is a cross-sectional view showing an example of a sample holder. FIG. 2 is a plan perspective view of the sample holder shown in FIG. 1 . FIG. 10 is a plan perspective view showing another example of the sample holder. FIG. 10 is a plan perspective view showing another example of the sample holder. FIG. 10 is a cross-sectional view showing another example of the sample holder. FIG. 10 is a cross-sectional view showing another example of the sample holder. FIG. 10 is a cross-sectional view showing another example of the sample holder. FIG. 8 is a plan perspective view of the sample holder shown in FIG. 7. FIG. 10 is a cross-sectional view showing another example of the sample holder. FIG. 10 is a cross-sectional view showing another example of the sample holder. FIG. 10 is an enlarged cross-sectional view showing another example of the sample holder.

The sample holder 100 will now be described in detail.

Figure 1 is a cross-sectional view showing an example of a sample holder 100. As shown in Figure 1, the sample holder 100 includes a ceramic substrate 1, an electrode 2, a cylindrical body 3, a first adhesive layer 4, a power supply terminal 5, a metal member 6, and a second adhesive layer 7.

The ceramic substrate 1 is a component in the sample holder 100 that holds a sample. The ceramic substrate 1 has a first surface 11 and a second surface 12 located opposite the first surface 11. In FIG. 1, the first surface 11 is the sample holding surface. The ceramic substrate 1 is, for example, disk-shaped. Examples of materials for the ceramic substrate 1 include aluminum oxide and aluminum nitride. When the ceramic substrate 1 is disk-shaped, its dimensions are, for example, a thickness of 1 to 10 mm and a diameter of 200 to 350 mm.

The electrode 2 is a member for adsorbing the sample in the sample holder 100. As shown in FIG. 1, the electrode 2 is located inside the ceramic substrate 1. The electrode 2 may be made of a metal material such as platinum or tungsten.

The cylindrical body 3 is a component that prevents the power supply terminal 5 from becoming electrically connected to other components. The cylindrical body 3 has a third surface 31 that faces the second surface 12 of the ceramic substrate 1. The cylindrical body 3 extends in a direction away from the second surface 12 of the ceramic substrate 1.

The cylindrical body 3 may be made of an insulating material such as ceramic or polyimide. The dimensions of the cylindrical body 3 are, for example, an outer diameter of 2 to 30 mm, an inner diameter of 0.5 to 10 mm, and a length of 20 to 60 mm.

The first adhesive layer 4 bonds the ceramic substrate 1 and the cylindrical body 3 together. The first adhesive layer 4 is located in contact with both the second surface 12 of the ceramic substrate 1 and the third surface 31 of the cylindrical body 3. As long as the first adhesive layer 4 is located in contact with both the second surface 12 of the ceramic substrate 1 and the third surface 31 of the cylindrical body 3, it may extend beyond the cylindrical body 3 when viewed from above. The material of the first adhesive layer 4 is, for example, silicone resin or epoxy resin. The thickness of the first adhesive layer 4 at the portion where the ceramic substrate 1 and the cylindrical body 3 face each other is, for example, 0.1 to 5 mm.

The power supply terminal 5 is a member for passing electricity to the electrode 2. The power supply terminal 5 is located inside the cylindrical body 3 and connected to the electrode 2. The power supply terminal 5 is connected to an external power source and supplies electricity to the electrode 2. As shown in Figure 1, the power supply terminal 5 may also have a flange-like shape, with the portion that connects to the electrode 2 being wider than the rest of the terminal. This strengthens the fixation to the ceramic substrate 1 and makes it less likely to peel off. When the power supply terminal 5 is a cylindrical member, its outer diameter is 0.5 to 10 mm and its length is 20 to 70 mm.

The metal member 6 is a member for cooling the ceramic substrate 1. As shown in FIG. 1 , the metal member 6 is positioned to surround the outer peripheral surface 32 of the cylindrical body 3. The metal member 6 has a fourth surface 61 facing the second surface 12.

The metal member 6 may be made of a metal material such as aluminum or titanium. The metal member 6 may be, for example, disk-shaped, with a diameter of 200 to 400 mm and a thickness of 20 to 60 mm.

The second adhesive layer 7 bonds the ceramic substrate 1 and the metal member 6 together. The second adhesive layer 7 is positioned in contact with the outer peripheral surface 32 of the cylindrical body 3, the second surface 12 of the ceramic substrate 1, and the fourth surface 61 of the metal member 6. The material of the second adhesive layer 7 is an insulator such as silicone resin or fluororubber.

When the first adhesive layer 4 is located along the space between the second surface 12 of the ceramic substrate 1 and the third surface 31 of the cylindrical body 3, the distance of the current path is the length in the left-right direction of the third surface 31 in the cross-sectional view shown in Figure 1.

In this embodiment, as shown in FIG. 1, the second surface 12 of the ceramic substrate 1 has a recess 121. As shown in FIGS. 2 and 3, in a planar perspective view looking toward the first surface 11 of the ceramic substrate 1, the recess 121 is located so that at least a portion of it overlaps the third surface 31. Here, "planar perspective view looking toward the first surface 11 of the ceramic substrate 1" refers to a planar perspective view of the sample holder 100 viewed from above (from above in FIG. 1). As shown in FIGS. 2 and 3, the shape of the recess 121 may be circular or arc-shaped in planar perspective. As shown in FIG. 1, the first adhesive layer 4 is located in the recess 121. Furthermore, since the first adhesive layer 4 is located above the cylindrical body 3 and has the same outer diameter, the cylindrical body 3 and the third surface 31 are located at the position of the first adhesive layer 4 in the planar perspective views of FIGS. 2 and 3. This also applies to the planar perspective views described below. Note that FIG. 1 is a cross-sectional view taken along line A-A' in FIG. 2.

As shown in Figure 1, the first adhesive layer 4 is located within the recess 121. This allows the distance of the current path to be longer by the length of the first adhesive layer 4 located within the recess 121, compared to when the first adhesive layer 4 in contact with the second surface 12 of the ceramic substrate 1 is flat in side view. This makes the ceramic substrate 1 less susceptible to dielectric breakdown, resulting in excellent durability. Furthermore, there is little risk of the adhesive force of the electrode 2 decreasing.

Also, as shown in FIG. 4, the recess 121 may have an annular recess 121 that overlaps the third surface 31 in a planar perspective. As a result, even if current flows radially from the power supply terminal 5, the annular shape of the recess 121 makes the ceramic substrate 1 less susceptible to dielectric breakdown, resulting in excellent durability. Furthermore, there is little risk of a decrease in the adhesive force of the electrode 2. Furthermore, by bonding the ceramic substrate 1 and the cylindrical body 3 via the first adhesive layer 4 that fills the annular recess 121, stress associated with displacement of the ceramic substrate 1, the first adhesive layer 4, and the second adhesive layer 7 that occurs due to repeated thermal expansion and contraction caused by heating and cooling cycles can be alleviated. When the first adhesive layer 4 located in the recess 121 is annular in a planar perspective, for example, the outer diameter is 2 to 30 mm and the inner diameter is 0.5 to 10 mm.

As shown in FIG. 5 , the annular recess 121 may overlap the outer peripheral surface 32 of the cylindrical body 3 in a planar perspective view. "Overlapping the outer peripheral surface 32" here means that at least a portion of the annular recess 121 is located on the outer peripheral surface 32 of the cylindrical body 3. As shown in FIG. 5 , the contact area between the ceramic substrate 1, the first adhesive layer 4, and the second adhesive layer 7 involves contact between multiple different materials. This makes it easy for gaps to form due to repeated thermal expansion and contraction caused by heating and cooling cycles. Therefore, there is a risk that current applied to the power supply terminal 5 may be transmitted to the metal member 6 along the second surface 12 of the ceramic substrate 1 through the gap. The presence of the annular recess 121 here increases the length of the current path, making dielectric breakdown less likely to occur. Even if dielectric breakdown does occur, the increased distance from the power supply terminal 5 to the metal member 6 makes it more difficult for current to be transmitted from the power supply terminal 5 to the metal member 6. As a result, the sample holder 100 of the present disclosure has high durability.

Furthermore, as shown in FIG. 6 , the annular recess 121 may overlap annularly with the inner circumferential surface of the cylindrical body 3 in a planar perspective. "Overlapping annularly with the inner circumferential surface" here means that at least a portion of the annular recess 121 is located on the outer circumferential surface 32 of the cylindrical body 3. When the annular recess 121 overlaps annularly with the inner circumferential surface of the cylindrical body 3 in a planar perspective, less air gets between the ceramic substrate 1 and the cylindrical body 3, and the sample holder 100 of the present disclosure has high thermal uniformity.

Also, as shown in Figures 7 and 8, multiple annular recesses 121 may be provided. This increases the distance from the power supply terminal 5 to the metal member 6, reducing the risk of dielectric breakdown. Figures 7 and 8 show a case where there are two annular recesses 121. Furthermore, by providing multiple annular recesses 121, stresses associated with displacement of the ceramic substrate 1, the first adhesive layer 4, and the second adhesive layer 7 caused by repeated thermal expansion and contraction due to heating and cooling cycles can be more effectively alleviated compared to a case where there is only one annular recess 121. Furthermore, when there are multiple annular recesses 121, the widths of the respective annular recesses 121 and the spacing between the annular recesses 121 may be different.

Also, as shown in FIG. 9 , at least a portion of the cylindrical body 3 may be located within the recess 121, and the portion located within the recess 121 may be covered by the first adhesive layer 4. In this way, the recess 121 covers up to a portion of the outer circumferential surface 32 of the cylindrical body 3, thereby increasing the distance of the current path. This makes the ceramic substrate 1 less susceptible to dielectric breakdown and therefore more durable. Furthermore, there is less risk of a decrease in the adhesive force of the electrode 2. Furthermore, the coverage by the first adhesive layer 4 further improves the bonding strength between the ceramic substrate 1 and the cylindrical body 3, reducing the risk of peeling. As a result, the sample holder 100 of the present disclosure has high durability.

Also, as shown in FIG. 10 , the cylindrical body 3 may have a protrusion 33 on the third surface 31, the protrusion 33 being located within the recess 121, and the portion located within the recess 121 may be covered by the first adhesive layer 4. The shape of the protrusion 33 may be, for example, a cylinder or a prism. The presence of the protrusion 33 in the sample holder 100 can alleviate stress associated with displacement of the ceramic substrate 1, the first adhesive layer 4, and the second adhesive layer 7 caused by repeated thermal expansion and contraction due to heating and cooling cycles. As a result, the durability of the sample holder 100 can be maintained. Furthermore, the presence of the protrusion 33 allows for easy positioning when fixing the ceramic substrate 1 and the cylindrical body 3, allowing for efficient manufacturing.

Furthermore, the protrusion 33 only needs to be closer to the first surface 11 than to the second surface 12 of the ceramic substrate 1, but the longer the protrusion 33, the easier it will be to position it.

As shown in FIG. 11 , the recess 121 may have a large inner diameter on the second surface 12. A large inner diameter on the second surface 12 here means that the length of the bottom of the recess 121 in FIG. 10 is longer than the length of the opening of the recess 121 in FIG. 10 . This allows for a larger volume of the first adhesive layer 4 to be added compared to when the lengths of the bottom and opening of the recess 121 in FIG. 11 are the same. This further improves the bonding strength between the ceramic substrate 1 and the cylindrical body 3. Furthermore, a large inner diameter on the second surface 12 allows for a longer current path. This reduces the likelihood of dielectric breakdown in the ceramic substrate 1, resulting in excellent durability. Furthermore, there is little risk of a decrease in the adhesive force of the electrode 2.

Furthermore, when the inner diameter of the recess 121 expands, it may be rounded. This reduces the amount of stress generated at the corner between the first adhesive layer 4 located along the third surface 31 of the cylindrical body 3 and the first adhesive layer 4 located in the recess 121, compared to when the corner is not rounded, making it less likely that the ceramic substrate 1 and the first adhesive layer 4 will peel off. As a result, the sample holder 100 of the present disclosure has high durability.

The surface roughness of the recess 121 may also be greater than the surface roughness of the second surface 12. The greater the surface roughness, the more likely it is that the progress of current will be hindered. This reduces the risk of dielectric breakdown.

The recess 121 can be formed, for example, by the following method. The recess 121 can be formed by grinding the ceramic substrate 1 using a machining center. If the recess is shallow, it can be formed by sandblasting after masking the area other than where the recess 121 will be formed.

The first adhesive layer 4 and the second adhesive layer 7 can be formed by the following methods. The first adhesive layer 4 is formed by using a dispenser to dispense raw material at a predetermined position on the second surface 12 of the ceramic substrate 1, adhering the cylindrical body, and then hardening it by heat treatment. The second adhesive layer 7 is formed by applying raw material to a predetermined position on the second surface 12 of the ceramic substrate 1 using a screen or metal mask, adhering the metal member 6, and then hardening it by heat treatment.

In addition, the specific details of the configuration, structure, positional relationships, and shape shown in the above embodiments may be modified as appropriate without departing from the spirit of this disclosure. Furthermore, the configurations, structures, positional relationships, and shapes shown in the above embodiments may be combined as appropriate without departing from the spirit of this disclosure.

1: Ceramic substrate 11: First surface 12: Second surface 121: Recess 2: Electrode 3: Cylindrical body 31: Third surface 32: Outer circumferential surface 33: Protrusion 4: First adhesive layer 5: Power supply terminal 6: Metal member 61: Fourth surface 7: Second adhesive layer 100: Sample holder

Claims (9)

A ceramic substrate;
An electrode;
A cylindrical body;
a first adhesive layer;
A power supply terminal;
A metal member;
a second adhesive layer;
the ceramic substrate has a first surface and a second surface opposite the first surface;
the second surface has a recess;
the electrodes are located inside the ceramic substrate;
the cylindrical body has a third surface facing the second surface,
the first adhesive layer is located in contact with at least each of the second surface and the third surface;
the power supply terminal is located inside the cylindrical body and connected to the electrode;
the metal member has a fourth surface facing the second surface and is positioned to surround the outer circumferential surface of the cylindrical body,
the second adhesive layer is positioned in contact with each of the outer peripheral surface, the second surface, and the fourth surface;
the recess is positioned so that at least a portion of the recess overlaps with the third surface in a planar perspective view toward the first surface,
The first adhesive layer is located in the recess. The sample holder according to claim 1, wherein the recess has an annular recess that annularly overlaps the third surface in the plan view. The sample holder according to claim 2 , wherein the annular recess overlaps the outer peripheral surface of the cylindrical body in an annular shape in the planar perspective view. The sample holder according to claim 2 or 3, wherein the annular recess overlaps an inner peripheral surface of the cylindrical body in an annular shape in the planar perspective view. A sample holder according to any one of claims 2 to 4, wherein there are multiple annular recesses. A sample holder according to claim 1 or claim 2, wherein at least a portion of the cylindrical body is located within the recess, and the portion located within the recess is covered with the first adhesive layer. A sample holder according to any one of claims 1 to 6, wherein the cylindrical body has a protrusion on the third surface, the protrusion is located within the recess, and the portion located within the recess is covered with the first adhesive layer. A sample holder according to any one of claims 1 to 7, wherein the recess has a larger inner diameter on the second surface. A sample holder according to any one of claims 1 to 8, wherein the recess has a surface roughness greater than the surface roughness of the second surface.