Member for semiconductor manufacturing device

Abstract

A member for a semiconductor manufacturing device 10 comprises: a ceramic plate 20 having a circular wafer mounting surface 22a and an annular FR mounting surface 24a provided at a position lower by one step than the wafer mounting surface 22a on an outer periphery of the wafer mounting surface 22a; and a cooling plate 30 provided on the lower surface of the ceramic plate 20. A coupling part (truncated cone part 22) connecting the wafer mounting surface 22a and the FR mounting surface 24a has a truncated cone side surface (tapered surface 23a) whose diameter increases from the wafer mounting surface 22a toward the FR mounting surface 24a.

Description

Semiconductor manufacturing equipment components

[0001] The present invention relates to a member for a semiconductor manufacturing device.

[0002] Semiconductor manufacturing equipment components are used to perform plasma-assisted CVD, etching, and other processes on wafers. For example, a semiconductor manufacturing equipment component disclosed in Patent Document 1 includes a ceramic plate and a cooling plate attached to the underside of the ceramic plate. The ceramic plate has a circular wafer mounting surface attached to its upper surface and an annular focus ring mounting surface attached to the outer periphery of the wafer mounting surface, positioned one step lower than the wafer mounting surface. A connecting portion connecting the wafer mounting surface and the focus ring mounting surface has a side surface perpendicular to the wafer mounting surface. A focus ring mounted on the focus ring mounting surface has a step along the inner periphery of its upper end to prevent interference with the wafer. The wafer mounted on the wafer mounting surface is placed in a state where it overhangs the wafer mounting surface.

[0003] Japanese Patent Application Laid-Open No. 2023-27641

[0004] When processing wafers using such semiconductor manufacturing equipment components, the wafer is subjected to heat input from the plasma, but the wafer is cooled by a cooling plate. However, when the outer periphery of the wafer overhangs the wafer mounting surface, it is not sufficiently cooled and can become locally hot.

[0005] The present invention has been made to solve the above-mentioned problems, and a main object of the present invention is to improve the ability to cool the outer periphery of the wafer.

[0006] [1] A semiconductor manufacturing equipment member of the present invention comprises: a ceramic plate having a circular wafer mounting surface and an annular focus ring mounting surface located around the outer periphery of the wafer mounting surface at a position one step lower than the wafer mounting surface; and a cooling plate provided on the underside of the ceramic plate, wherein a connecting portion connecting the wafer mounting surface and the focus ring mounting surface has a side surface of a truncated cone whose diameter increases from the wafer mounting surface toward the focus ring mounting surface.

[0007] In this semiconductor manufacturing equipment component, the connecting portion connecting the wafer mounting surface and the focus ring mounting surface has a truncated cone-shaped side surface whose diameter increases from the wafer mounting surface toward the focus ring mounting surface (i.e., from top to bottom). This increases the thermal path from the outer periphery of the wafer mounting surface toward the cooling plate compared to when the side surface of the connecting portion is perpendicular to the wafer mounting surface. This improves the ability to cool the outer periphery of the wafer.

[0008] Here, the "side surface of a truncated cone" includes not only the side surface of a truncated cone in the strict sense, but also the case where the side surface of the truncated cone is convex or concave (the same applies below).

[0009] [2] In the semiconductor manufacturing equipment member of the present invention (the semiconductor manufacturing equipment member described in [1] above), the diameter of the wafer mounting surface may be smaller than the diameter of the wafer to be mounted. In this case, the peripheral portion of the wafer is particularly likely to become hot, so applying the present invention is highly significant.

[0010] [3] In the semiconductor manufacturing equipment member of the present invention (the semiconductor manufacturing equipment member according to [1] or [2] above), the angle of the side surface of the connecting portion with respect to the focus ring mounting surface may be 70° or less. This can sufficiently increase the thermal path from the outer periphery of the wafer mounting surface to the cooling plate.

[0011] [4] The semiconductor manufacturing equipment component of the present invention (the semiconductor manufacturing equipment component described in any one of [1] to [3] above) may include a focus ring mounted on the focus ring mounting surface, and the portion of the inner peripheral surface of the focus ring facing the side surface of the connecting portion may be a frustum-shaped side surface whose diameter increases from top to bottom. For example, when a wafer mounted on the wafer mounting surface is positioned so as to cover the inner peripheral portion of the focus ring from above, the inner peripheral portion of the focus ring is more likely to cool than other portions because there is no heat input from plasma. However, since the portion of the inner peripheral surface of the focus ring facing the side surface of the connecting portion is a frustum-shaped side surface whose diameter increases from top to bottom, heat dissipation by the cooling plate is small. As a result, excessive cooling of the inner peripheral portion of the focus ring, which is generally more likely to cool, can be prevented.

[0012] [5] In the semiconductor manufacturing equipment member of the present invention (the semiconductor manufacturing equipment member described in [4] above), the angle of the portion with respect to the focus ring mounting surface may be larger than the angle of the side surface of the connecting portion with respect to the focus ring mounting surface. In this case, the gap between the side surface of the connecting portion of the ceramic plate and the portion of the inner circumferential surface of the focus ring facing the side surface of the connecting portion becomes wider as it goes upward, making it easier to prevent the focus ring from coming into contact with the ceramic plate.

[0013] [6] In the semiconductor manufacturing equipment member of the present invention (the semiconductor manufacturing equipment member described in [4] above), the angle of the portion with respect to the focus ring mounting surface may be smaller than the angle of the side surface of the connecting portion with respect to the focus ring mounting surface. This sufficiently reduces the contact area between the underside of the inner peripheral portion of the focus ring and the focus ring mounting surface, thereby more effectively preventing the inner peripheral portion of the focus ring, which generally cools easily, from becoming excessively cooled.

[0014] 1 is a longitudinal sectional view of a semiconductor manufacturing equipment member 10. FIG. 2 is a plan view of a semiconductor manufacturing equipment member 10. FIG. 3 is a partial enlarged view of FIG. 1. FIG. 4 is a partial enlarged view of a comparative embodiment. FIG. 5 is a partial enlarged view of another embodiment.

[0015] A preferred embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is a longitudinal cross-sectional view of a semiconductor manufacturing equipment component 10 (a cross-sectional view when cut along a plane including the central axis of the semiconductor manufacturing equipment component 10), Fig. 2 is a plan view of the semiconductor manufacturing equipment component 10, and Fig. 3 is an enlarged view of a portion of Fig. 1 (an enlarged view of a portion surrounded by a circle in Fig. 1). In the following description, terms such as up / down, left / right, front / rear, etc. may be used, but these terms merely refer to relative positional relationships.

[0016] Semiconductor manufacturing equipment component 10 is used to perform CVD, etching, or the like on wafers W using plasma, and is fixed to a mounting plate 84 provided inside a semiconductor process chamber 80. Semiconductor manufacturing equipment component 10 includes a ceramic plate 20, a cooling plate 30, a bonding layer 40, and a focus ring 60. Hereinafter, "focus ring" will be abbreviated as "FR."

[0017] The ceramic plate 20 has a circular wafer mounting surface 22a and an annular FR mounting surface 24a located on the outer periphery of the wafer mounting surface 22a and one step lower than the wafer mounting surface 22a. A wafer W is mounted on the wafer mounting surface 22a, and an FR 60 is mounted on the FR mounting surface 24a. The ceramic plate 20 is made of a ceramic material such as alumina or aluminum nitride. The ceramic plate 20 has a shape in which a truncated cone portion 22 is stacked on the upper surface of a flat cylindrical portion 24. The upper surface of the truncated cone portion 22 of the ceramic plate 20 is the wafer mounting surface 22a, and the annular surface of the upper surface of the cylindrical portion 24 excluding the truncated cone portion 22 is the FR mounting surface 24a. The truncated cone portion 22 also serves as a connecting portion connecting the wafer mounting surface 22a and the FR mounting surface 24a. Therefore, the connecting portion has a truncated cone side (tapered surface 23a) whose diameter increases from the wafer mounting surface 22a toward the FR mounting surface 24a. The angle α (see FIG. 3) of the tapered surface 23a with respect to the FR mounting surface 24a may be less than 90°, preferably 80° or less, and more preferably 70° or less. There is no particular lower limit to the angle α, but the angle α is preferably 20° or more. An angle α of 20° or more is preferable because it prevents the tip of the FR 60 from becoming too acute and reduces the risk of cracking the FR 60. The diameter of the wafer mounting surface 22a is smaller than the diameter of the wafer W (e.g., 300 mm).

[0018] The truncated cone portion 22 of the ceramic plate 20 incorporates a wafer attracting electrode 25. The wafer attracting electrode 25 is formed of a material containing, for example, W, Mo, WC, or MoC. The wafer attracting electrode 25 is a disk-shaped or mesh-shaped unipolar electrostatic electrode. The layer of the ceramic plate 20 above the wafer attracting electrode 25 functions as a dielectric layer. A DC wafer attracting power supply (not shown) is connected to the wafer attracting electrode 25.

[0019] The cylindrical portion 24 of the ceramic plate 20 incorporates an FR adsorption electrode 26. The FR adsorption electrode 26 is embedded in the cylindrical portion 24 at a position facing the FR mounting surface 24a. The FR adsorption electrode 26 is formed of a material containing, for example, W, Mo, WC, or MoC. The FR adsorption electrode 26 is a ring-shaped or mesh-shaped unipolar electrostatic electrode. The layer of the ceramic plate 20 above the FR adsorption electrode 26 functions as a dielectric layer. A DC FR adsorption power supply (not shown) is connected to the FR adsorption electrode 26.

[0020] The cooling plate 30 is a circular plate member having a refrigerant flow path 32 therein through which a refrigerant can circulate. The refrigerant flow path 32 is formed in a single stroke from one end to the other so as to cover the entire surface of the ceramic plate 20 in a plan view. In this embodiment, the diameter of the cooling plate 30 is the same as the diameter of the underside of the ceramic plate 20. The refrigerant flowing through the refrigerant flow path 32 is preferably a liquid, and is preferably electrically insulating. Examples of electrically insulating liquids include fluorine-based inert liquids. The cooling plate 30 is made of a conductive material containing, for example, a metal. Examples of conductive materials include metals and composite materials. Examples of metals include Al, Ti, Mo, and alloys thereof. Examples of composite materials include metal matrix composites (MMCs) and ceramic matrix composites (CMCs). Specific examples of such composite materials include materials containing Si, SiC, and Ti, and materials in which porous SiC is impregnated with Al and / or Si. A material containing Si, SiC, and Ti is called SiSiCTi, a material in which a porous SiC body is impregnated with Al is called AlSiC, and a material in which a porous SiC body is impregnated with Si is called SiSiC. It is preferable to select a material for the cooling plate 30 that has a thermal expansion coefficient close to that of the material for the ceramic plate 20. The cooling plate 30 is also used as an RF electrode. A protective film made of an insulating material (e.g., alumina or yttria) may be formed on the outer periphery of the cooling plate 30.

[0021] The bonding layer 40 bonds the lower surface of the ceramic plate 20 to the upper surface of the cooling plate 30. In this embodiment, the bonding layer 40 is an organic adhesive layer. The organic adhesive layer may be made of a resin such as an acrylic resin, a silicone resin, or an epoxy resin. In addition to the resin, a filler may be contained.

[0022] The FR 60 is an annular member placed on the FR mounting surface 24a and is made of, for example, silicon. A step 62 is provided along the circumferential direction at the upper portion of the inner circumferential surface of the FR 60. The step 62 is provided to prevent interference between the wafer W and the FR 60. A portion 63 of the inner circumferential surface of the FR 60 facing the tapered surface 23a is a side surface of a truncated cone (tapered surface) whose diameter increases from top to bottom. This portion 63 does not contact the tapered surface 23a. In other words, a gap is formed between this portion 63 and the tapered surface 23a. Therefore, the FR 60 is less susceptible to the thermal influence of the truncated cone portion 22 of the ceramic plate 20. In this embodiment, the angle β (see FIG. 3 ) of the portion 63 relative to the FR mounting surface 24a is the same as the angle α of the tapered surface 23a relative to the FR mounting surface 24a.

[0023] Next, an example of how the semiconductor manufacturing equipment component 10 is used will be described with reference to FIG. 1 . The chamber 80 has a shower head 82 on its ceiling. The semiconductor manufacturing equipment component 10 is fixed to a mounting plate 84 disposed inside the chamber 80. Specifically, the semiconductor manufacturing equipment component 10 is fixed to the mounting plate 84 by placing an O-ring 88 having a diameter substantially equal to that of the cooling plate 30 between the lower surface of the cooling plate 30 and the upper surface of the mounting plate 84, and then fastening the mounting plate 84 and the cooling plate 30 with a plurality of bolts 90. The bolts 90 have a head and a foot. The bolts 90 are inserted from below into stepped bolt insertion holes 86 that vertically penetrate the mounting plate 84, and the foot portions are threaded into the screw holes 34 provided on the lower surface of the cooling plate 30. At this time, the heads of the bolts 90 engage with the stepped portions of the bolt insertion holes 86. The O-rings 88 are compressed vertically to provide a seal. If there are other locations that require sealing, separate O-rings are also provided at those locations.

[0024] An FR 60 is placed on the FR mounting surface 24a of the semiconductor manufacturing equipment member 10, and a disk-shaped wafer W is placed on the wafer mounting surface 22a. In this state, a DC voltage is applied to the wafer suction electrode 25 to attract the wafer W to the wafer mounting surface 22a, and a DC voltage is applied to the FR suction electrode 26 to attract the FR 60 to the FR mounting surface 24a. The interior of the chamber 80 is then set to a predetermined vacuum atmosphere (or reduced-pressure atmosphere), and a process gas is supplied from the shower head 82 while a high-frequency voltage is applied between the shower head 82 and the cooling plate 30. This generates plasma between the cooling plate 30 and the shower head 82. The plasma is then used to process the wafer W.

[0025] The FR 60 is also consumed as the wafers W are plasma processed. However, since the FR 60 is thicker than the wafers W, the FR 60 is replaced after a plurality of wafers W have been processed.

[0026] When a wafer W is processed using the semiconductor manufacturing equipment member 10, heat is input to the wafer W due to plasma, but the wafer W is cooled by the cooling plate 30. The outer periphery of the wafer W overhangs the wafer mounting surface 22a because the diameter of the wafer W is larger than the diameter of the wafer mounting surface 22a. Therefore, the outer periphery of the wafer W is less likely to be heat-removed by the cooling plate 30 and is prone to becoming hot. However, in this embodiment, the connecting portion (frustum portion 22) connecting the wafer mounting surface 22a and the FR mounting surface 24a has a side surface (tapered surface 23a) of the truncated cone whose diameter increases from the wafer mounting surface 22a toward the FR mounting surface 24a. Therefore, compared to when the side surface of the connecting portion is perpendicular to the wafer mounting surface 22a, the thermal path from the outer periphery of the wafer mounting surface 22a toward the cooling plate 30 is increased.

[0027] This point will be explained in detail below. FIG. 4 is a partially enlarged view of a comparative embodiment (the embodiment of the prior art disclosed in Patent Document 1). In FIG. 4, the ceramic plate 20 is formed by stacking a flat, small-diameter cylindrical portion 122 on the upper surface of a flat cylindrical portion 24. The upper surface of the cylindrical portion 122 of the ceramic plate 20 is the wafer mounting surface 22a. The cylindrical portion 122 also serves as a connecting portion connecting the wafer mounting surface 22a and the FR mounting surface 24a. The connecting portion has a side surface (vertical surface 123a) of the cylindrical portion 122. Furthermore, a portion 163 of the inner peripheral surface of the FR 60 facing the vertical surface 123a is also a vertical surface. Note that in FIG. 4, the same components as those of this embodiment are denoted by the same reference numerals. In FIG. 4, the tapered surface 23a and portion 63 of this embodiment are indicated by dotted lines. In this embodiment, the connecting portion (frustum portion 22) has a side surface (tapered surface 23a) of the truncated cone whose diameter increases from the wafer mounting surface 22a to the FR mounting surface 24a. This increases the number of thermal paths from the outer periphery of the wafer mounting surface 22a to the cooling plate 30 compared to the comparative embodiment, in which the connecting portion (cylindrical portion 122) has a vertical side surface (vertical surface 123a). Specifically, the area of ​​the right-angled triangular cross section indicated by dotted hatching in FIG. 4 is an increased number of paths. As a result, in this embodiment, heat is more easily removed from the overhanging outer periphery of the wafer W compared to the comparative embodiment.

[0028] Furthermore, the wafer W placed on the wafer placement surface 22a is disposed so as to cover the inner periphery of the FR 60 from above. In this case, in the comparative example of FIG. 4 , the inner periphery of the FR 60 covered by the wafer W is more likely to cool than other portions because the plasma heat input is blocked by the wafer W. However, in this embodiment, the inner periphery of the FR 60 covered by the wafer W has a shape in which a portion of the inner periphery of the FR 60 in the comparative example is obliquely cut off, and therefore heat dissipation by the cooling plate 30 is small. As a result, it is possible to prevent the inner periphery of the FR 60, which generally cools easily, from being excessively cooled.

[0029] According to the semiconductor manufacturing equipment member 10 described above, the connecting portion (frustum portion 22) has a side surface of a truncated cone whose diameter increases from the wafer mounting surface 22a toward the FR mounting surface 24a, and therefore, compared to the comparative embodiment shown in FIG. 4 in which the connecting portion has a vertical side surface (vertical surface 123a), the number of thermal paths from the outer periphery of the wafer mounting surface 22a toward the cooling plate 30 increases. Therefore, the ability to cool the outer periphery of the wafer W is improved.

[0030] Furthermore, the diameter of the wafer mounting surface 22a is smaller than the diameter of the mounted wafer W. In this case, the peripheral portion of the wafer W is particularly likely to become hot, and therefore, it is highly significant to apply the present invention.

[0031] Furthermore, the angle α of the tapered surface 23a with respect to the FR mounting surface 24a is preferably 70° or less, which can sufficiently increase the thermal path from the outer periphery of the wafer mounting surface 22a to the cooling plate 30.

[0032] Furthermore, the portion 63 of the inner peripheral surface of the FR 60 facing the tapered surface 23a is the side surface of a truncated cone whose diameter increases from top to bottom, which prevents the inner peripheral portion of the FR 60, which is generally prone to cooling, from being cooled excessively.

[0033] Furthermore, since both the side of the connecting portion (frustum portion 22) of the ceramic plate 20 and the portion 63 of the inner surface of the FR 60 are tapered surfaces, when the FR 60 is placed on the FR placement surface 24a, the self-alignment effect improves the installation position accuracy of the FR 60.

[0034] It goes without saying that the present invention is not limited to the above-described embodiment, and can be embodied in various forms as long as they fall within the technical scope of the present invention.

[0035] In the above-described embodiment, the angle α of the tapered surface 23a relative to the FR mounting surface 24a and the angle β of the portion 63 (tapered surface) relative to the FR mounting surface 24a are the same, but this is not particularly limited to this, and the configurations shown in Figures 5 and 6 may be adopted, for example. In Figures 5 and 6, the same components as those in the above-described embodiment are denoted by the same reference numerals.

[0036] 5, the angle β of the portion 63 (tapered surface) relative to the FR mounting surface 24a is larger than the angle α of the tapered surface 23a relative to the FR mounting surface 24a (i.e., β>α). In this way, the gap between the portion 63 (tapered surface) of the FR 60 and the tapered surface 23a of the ceramic plate 20 becomes wider as it goes upward, making it easier to prevent the portion 63 (tapered surface) of the FR 60 from contacting the ceramic plate 20.

[0037] 6, the angle β of the portion 63 (tapered surface) relative to the FR mounting surface 24a is smaller than the angle α of the tapered surface 23a relative to the FR mounting surface 24a (i.e., β<α). This sufficiently reduces the contact area between the lower surface of the inner periphery of the FR 60 and the FR mounting surface 24a, thereby more effectively preventing the inner periphery of the FR 60, which generally tends to cool easily, from becoming excessively cold.

[0038] 5 and 6, the difference between the angles α and β is preferably 30° or less, and more preferably 15° or less, which reduces the risk of the space between the portion 63 of the FR 60 and the tapered surface 23a of the ceramic plate 20 becoming too large, causing other problems such as discharge.

[0039] In the above-described embodiment, the tapered surface 23a of the ceramic plate 20 and the portion 63 of the inner peripheral surface of the FR 60 facing the tapered surface 23a are strictly defined as the side surface of a truncated cone, but this is not particularly limited. For example, instead of the side surface of a truncated cone, the side surface of the truncated cone may have a convex or concave shape. The same applies to the portion 63.

[0040] In the above-described embodiment, a heater electrode for heating a wafer may be embedded in the truncated cone portion 22 of the ceramic plate 20. In this case, when it is necessary to heat the wafer W placed on the wafer mounting surface 22a, the heater electrode for heating the wafer can be energized to heat the wafer W to the desired high temperature. Also, a heater electrode for heating the FR may be embedded in the cylindrical portion 24 of the ceramic plate 20 at a position facing the FR mounting surface 24a. In this case, when it is necessary to heat the FR 60 placed on the FR mounting surface 24a, the heater electrode for heating the FR can be energized to heat the FR 60 to the desired high temperature. When both a heater electrode for heating a wafer and a heater electrode for heating the FR are embedded in the ceramic plate 20, it is preferable that the temperatures of the respective heater electrodes be individually adjustable.

[0041] In the above-described embodiment, an organic adhesive layer is used as the bonding layer 40, but the present invention is not limited to this. For example, the bonding layer 40 may be an inorganic bonding layer such as a metal. The inorganic bonding layer may be a metallic bonding layer formed of solder or a metal brazing material (e.g., a brazing material such as aluminum or titanium). The metallic bonding layer may be formed by, for example, thermal compression bonding (TCB). TCB refers to a known method in which a metallic bonding material is sandwiched between two members to be joined and the two members are pressure-bonded while heated to a temperature below the solidus temperature of the metallic bonding material.

[0042] The present invention can be used for components used in semiconductor manufacturing equipment, such as electrostatic chuck heaters, electrostatic chucks, and ceramic heaters.

[0043] 10 semiconductor manufacturing equipment member, 20 ceramic plate, 22 truncated cone portion, 22a wafer mounting surface, 23a tapered surface, 24 cylindrical portion, 24a FR mounting surface, 25 wafer suction electrode, 26 FR suction electrode, 30 cooling plate, 32 refrigerant flow path, 34 screw hole, 40 bonding layer, 60 focus ring (FR), 62 step, 63 portion, 80 chamber, 82 shower head, 84 installation plate, 86 bolt insertion hole, 88 O-ring, 90 bolt, 122 cylindrical portion, 123a vertical surface, 163 portion.

Claims

1. A component for semiconductor manufacturing equipment comprising: a ceramic plate having a circular wafer mounting surface and an annular focus ring mounting surface located around the outer periphery of the wafer mounting surface at a position one step lower than the wafer mounting surface; and a cooling plate provided on the underside of the ceramic plate, wherein a connecting portion connecting the wafer mounting surface and the focus ring mounting surface has a side surface of a truncated cone whose diameter increases from the wafer mounting surface toward the focus ring mounting surface.

2. The semiconductor manufacturing equipment member according to claim 1, wherein the diameter of the wafer mounting surface is smaller than the diameter of the wafer to be mounted.

3. The semiconductor manufacturing equipment member according to claim 1, wherein an angle of a side surface of the connecting portion with respect to the focus ring mounting surface is 70° or less.

4. A component for semiconductor manufacturing equipment as claimed in claim 1 or 2, comprising a focus ring placed on the focus ring mounting surface, and a portion of the inner peripheral surface of the focus ring that faces the side surface of the connecting portion is the side surface of a truncated cone whose diameter increases from top to bottom.

5. The member for semiconductor manufacturing equipment according to claim 4, wherein an angle of said portion with respect to said focus ring mounting surface is larger than an angle of a side surface of said connecting portion with respect to said focus ring mounting surface.

6. The semiconductor manufacturing equipment member according to claim 4, wherein an angle of said portion with respect to said focus ring mounting surface is smaller than an angle of a side surface of said connecting portion with respect to said focus ring mounting surface.

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