JP2001102336A - Table for wafer-polishing device, and ceramic structure body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a table for a wafer-polishing device that has the superior strength of a bonding interface, incapable of being broken easily, and at the same time has a superior soaking property. SOLUTION: A table 2 is composed of one part of a wafer-polishing device 1. A semiconductor wafer 5, retained onto a retention surface 6a of a wafer retention plate 6, is slid on a polishing surface 2a of the table 2. In the table 2, bases 11A and 11B made of ceramics are laminated, and at the same time, are bonded via an organic-system bonding layer 14 each other. The thickness of a machining deterioration layer L1 in the surface layer of a surface to be bonded is set to 30 μm or less. On a bonding interface, a fluid channel 12 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a table for a wafer polishing apparatus and a ceramic structure.

[0002]

2. Description of the Related Art Generally, a mirror wafer having a mirror surface can be obtained by slicing a single crystal silicon ingot thinly and polishing it through a lapping step and a polishing step. In particular, when the epitaxial growth layer forming step is performed after the lapping step and before the polishing step, an epitaxial wafer can be obtained. Then, these bare wafers are oxidized,
Various processes such as etching and impurity diffusion are repeatedly performed, and finally a semiconductor device is manufactured.

In the above series of steps, it is necessary to polish the device formation surface of a semiconductor wafer by using some means. Therefore, various types of wafer polishing apparatuses (lapping machines, polishing machines, and the like) have been conventionally proposed.

A typical wafer polishing apparatus includes a table, a pusher plate, a cooling jacket, and the like. A table made of metal such as stainless steel is fixed on the upper part of the cooling jacket. Cooling water is circulated through a flow path provided in the cooling jacket. A semiconductor wafer is attached to the holding surface of the pusher plate using a thermoplastic wax. The semiconductor wafer held by the rotating pusher plate is pressed from above onto the polished surface of the table. As a result, the semiconductor wafer comes into sliding contact with the polishing surface, and one side surface of the wafer is uniformly polished. Then, the heat generated in the wafer at this time is conducted to the cooling jacket via the table, and is taken out of the apparatus by the cooling water circulating in the flow path.

By the way, in order to realize a large-diameter and high-quality wafer, it is necessary to minimize the temperature variation in the table and to improve the heat uniformity of the table.
For this reason, the present inventors have conceived of using ceramics as a material for forming the table, and further providing a flow path in the table itself instead of the cooling jacket. In view of this, a structure has already been proposed in which a plurality of ceramic substrates are laminated and the respective substrates are bonded to each other via an organic adhesive layer, and a flow path is provided at the bonding interface of the substrates.

[0006]

However, when the above-described structure is employed, a general organic adhesive cannot provide sufficient adhesive strength, and cracks and peeling occur at the adhesive interface, thereby causing a problem in the table. However, there was a problem that it was easily broken. Further, in this case, the sealing property at the bonding interface is deteriorated, and water flowing through the flow path may leak out of the table.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a table for a wafer polishing apparatus which is excellent in adhesive interface strength, is not easily broken, and has excellent heat uniformity. is there.

[0008]

According to the first aspect of the present invention, a semiconductor wafer held on a holding surface of a wafer holding plate constituting a wafer polishing apparatus is slid. In a table having a polished surface to be contacted, the thickness of the affected layer on the surface of the surface to be bonded is 30
In a state where a plurality of ceramic substrates set to μm or less are laminated, each substrate is adhered to each other via an organic adhesive layer, and a fluid flow path is provided at an adhesion interface of the substrate. The gist is a table for a wafer polishing apparatus.

According to a second aspect of the present invention, in the first aspect, the thickness of the organic adhesive layer is 10 μm to 50 μm. According to a third aspect of the present invention, in the first or second aspect, each of the ceramic bases is a base made of a silicon carbide sintered body.

[0010] In the invention according to claim 4, the ceramic base material is bonded to each other via an organic adhesive layer, and the thickness of the damaged layer on the surface to be bonded of the base material is 3 mm.
The gist is a ceramic structure characterized by being set to 0 μm or less.

According to a fifth aspect of the present invention, in the fourth aspect, the thickness of the organic adhesive layer is 10 μm to 50 μm. According to a sixth aspect of the present invention, in each of the fifth and sixth aspects, each of the ceramic bases is a base made of a silicon carbide sintered body.

The "action" of the present invention will be described below. According to the invention as set forth in claims 1 to 3, as a result, the thickness of the fragile and easily deformed work-affected layer is reduced, so that sufficient adhesive strength can be obtained even when an organic adhesive is used, and the bonding interface Cracks and peeling are less likely to occur. Further, according to the present invention, since the sealing property at the bonding interface is maintained, leakage of the fluid flowing through the fluid flow path from the bonding interface is avoided. Furthermore, since the temperature can be finely controlled by flowing the fluid through the fluid flow path, the temperature variation in the table is reduced.

According to the second aspect of the present invention, since the thickness of the organic adhesive layer is set within the above-mentioned preferred range, sufficient strength can be provided at the bonding interface while improving the temperature uniformity of the table. Obtainable. That is, if the layer is too thin,
Sufficient adhesive strength cannot be obtained, and the ceramic substrates are easily separated from each other. Conversely, since the organic adhesive has a lower elastic modulus than ceramics, if the layer is too thick, cracks tend to occur in the adhesive layer when stress is applied. In addition, since the organic adhesive has a lower thermal conductivity than ceramics, if the layer is too thick, the thermal resistance of the adhesive layer becomes large, which may hinder the improvement of the table uniformity.

According to the third aspect of the present invention, the table is formed by bonding ceramic substrates of the same type, that is, ceramic substrates having the same coefficient of thermal expansion. For this reason, thermal stress is hardly generated near the bonding interface, and extremely high bonding strength can be obtained. Further, the silicon carbide sintered body is superior to other ceramic sintered bodies, especially in thermal conductivity, heat resistance, thermal shock resistance, wear resistance, and the like. Therefore, if polishing is performed using a table made of such a base material, it is possible to reliably cope with an increase in diameter and quality of a semiconductor wafer.

According to the invention as set forth in claims 4 to 6, the thickness of the work-affected layer which is fragile and easily falls off is reduced, so that sufficient adhesive strength can be obtained even when an organic adhesive is used. Thus, cracks and peeling are less likely to occur at the bonding interface. The reason is that, in the ceramic base material, a suitable anchor effect can be obtained by reducing the thickness of the work-affected layer that is fragile and easy to fall off.

According to the fifth aspect of the present invention, since the thickness of the organic adhesive layer is set within the above-mentioned preferred range, the thickness of the organic adhesive layer is sufficient for the adhesive interface while avoiding an increase in the thermal resistance of the adhesive layer. High strength can be obtained. That is, if the layer is too thin, sufficient adhesive strength cannot be obtained, and the ceramic substrates are easily separated from each other. Conversely, since the organic adhesive has a lower elastic modulus than ceramics, if the layer is too thick, cracks tend to occur in the adhesive layer when stress is applied. Further, since the organic adhesive has a lower thermal conductivity than ceramics, if the layer is too thick, the thermal resistance in the adhesive layer will increase.

According to the sixth aspect of the present invention, thermal stress is hardly generated at the bonding interface, and extremely high bonding strength can be obtained. In particular, thermal conductivity, heat resistance, thermal shock resistance, abrasion resistance and the like can be obtained. It is possible to obtain a structure excellent in quality

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A wafer polishing apparatus 1 according to one embodiment of the present invention will be described below in detail with reference to FIGS.

FIG. 1 shows a wafer polishing apparatus 1 according to this embodiment.
Is schematically shown. The table 2 constituting the wafer polishing apparatus 1 has a disk shape. The upper surface of the table 2 is a polishing surface 2a for polishing the semiconductor wafer 5. A polishing cloth (not shown) is attached to the polishing surface 2a. The table 2 according to the present embodiment is directly and horizontally fixed to the upper end surface of the cylindrical rotating shaft 4 without using a cooling jacket. Therefore, when the rotation shaft 4 is driven to rotate, the table 2 rotates integrally with the rotation shaft 4.

As shown in FIG. 1, the wafer polishing apparatus 1 includes a plurality (two in FIG. 1 for convenience of illustration) of wafer holding plates 6. As a material for forming the plate 6, for example, a glass, a ceramic material such as alumina, a metal material such as stainless steel, or the like is employed. A pusher bar 7 is fixed to the center of one side surface (non-holding surface 6b) of each wafer holding plate 6. Each pusher bar 7 is located above the table 2 and is connected to driving means (not shown). Each pusher bar 7 horizontally supports each wafer holding plate 6. At this time, the holding surface 6
a is in a state facing the polishing surface 2a of the table 2. Further, each pusher bar 7 can not only rotate with the wafer holding plate 6 but also move up and down within a predetermined range. Instead of the method of moving the plate 6 up and down, a structure of moving the table 2 up and down may be adopted. The semiconductor wafer 5 is adhered to the holding surface 6a of the wafer holding plate 6 using, for example, thermoplastic wax. The semiconductor wafer 5 may be attracted to the holding surface 6a by evacuation or electrostatically. At this time, the polished surface 5a of the semiconductor wafer 5 needs to face the polished surface 2a of the table 2.

When the apparatus 1 is a lapping machine, that is, an apparatus for polishing a wafer that has undergone a slicing step in a bare wafer process, the wafer holding plate 6 is preferably as follows. That is, it is preferable that the plate 6 slides the semiconductor wafer 5 in a state where a predetermined pressing force is applied to the polishing surface 2a. This is because, even if a pressing force is applied by such a wafer holding plate 6 (that is, a pusher plate), there is no need to worry about peeling of the epitaxial growth layer since the epitaxial growth layer is not formed. The same applies to a case where the apparatus 1 is a polishing machine for manufacturing a mirror wafer, that is, an apparatus that performs polishing without performing an epitaxial growth step on a wafer that has undergone the lapping step.

On the other hand, if the apparatus 1 is a polishing machine for manufacturing an epitaxial wafer, that is, an apparatus that performs an epitaxial growth step on a wafer that has undergone the lapping step and then performs polishing, the plate 6 is formed as follows. It is good to be something. That is, plate 6
It is preferable that the semiconductor wafer 5 is slid in contact with the polishing surface 2a with almost no pressing force applied. This is because the silicon epitaxial growth layer is easier to peel than single crystal silicon. This is basically the same when the apparatus 1 is a machine for performing chemical mechanical polishing (CMP) after various film forming steps.

Next, the configuration of the table 2 will be described in detail. As shown in FIGS. 1 and 2, the table 2 of the present embodiment has a plurality of (here, two) base materials 11A, 1A.
This is a ceramic structure obtained by laminating 1B. On the back surface of the upper base material 11A, grooves 13 forming a part of a cooling water channel 12, which is a fluid flow channel, are formed in a predetermined pattern. The two substrates 11A and 11B are connected to each other by the organic adhesive layer 1.
4 are integrated with each other by being joined to each other. As a result, the water channel 12 is formed at the bonding interface between the substrates 11A and 11B. A through hole 15 is formed substantially at the center of the lower substrate 11B. These through holes 15
Is provided with a flow path 4 a provided in the rotating shaft 4 and the water passage 12.
And the communication.

The groove 13 constituting a part of the water channel 12 is a grinding groove formed by grinding the back surface (that is, the surface to be bonded) of the upper base material 11A after the raw processing and before firing.
The depth of the groove 13 is about 3 mm to 10 mm, and the width is 5 mm to 20 mm
It may be set to each degree.

The through hole 1 is provided substantially at the center of the lower substrate 11B.
5 are formed. These through holes 15 are
The flow path 4a provided therein and the water channel 12 are communicated.

The ceramic material constituting each of the bases 11A and 11B is preferably a silicide ceramic or a carbide ceramic, and in particular, a silicon carbide sintered body (SiC sintered body) using silicon carbide powder as a starting material. Body). This is because a silicon carbide sintered body using silicon carbide powder as a starting material is superior to other ceramic sintered bodies, particularly in thermal conductivity, heat resistance, thermal shock resistance, wear resistance, and the like. In this embodiment, the two substrates 11
The same material is used for both A and 11B.

As the silicon carbide powder, α-type silicon carbide powder, β-type silicon carbide powder, amorphous silicon carbide powder and the like are used. In this case, only one kind of powder may be used alone, or two or more kinds of powder may be combined (α type + β type,
α-type + amorphous, β-type + amorphous, or α-type + β-type + amorphous). Note that a sintered body manufactured using β-type silicon carbide powder contains more large plate-like crystals than a sintered body manufactured using other types of silicon carbide powder. Therefore, the grain boundaries of the crystal grains in the sintered body are small, and the sintered body is particularly excellent in thermal conductivity.

The density of the substrates 11A and 11B is 2.7 g / c
It is preferably at least m ^3, more preferably at least 3.0 g / cm ³ , particularly preferably at least 3.1 g / cm ³ . If the density is low, the bonding between crystal grains in the sintered body becomes weak or the number of pores increases, so that sufficient corrosion resistance and wear resistance cannot be ensured.

The thermal conductivity of the substrates 11A and 11B is 30 W /
mK or more, and more preferably 80 W / mK to 2
Desirably, it is 00 W / mK. If the thermal conductivity is too small, temperature variations are likely to occur in the sintered body, which may prevent the semiconductor wafer 5 from having a large diameter and high quality. Conversely, the higher the thermal conductivity is, the more preferable it is. On the other hand, if the thermal conductivity exceeds 200 W / mK, it is difficult to supply a low-cost and stable material.

The organic adhesive layer 14 for joining the substrates 11A and 11B to each other is preferably formed using an epoxy resin adhesive. The reason is that the adhesive has excellent adhesive strength in addition to heat resistance. Specifically, in this embodiment, a mixture of a modified polyamine and silicon oxide (SiO ₂ ) at a predetermined ratio is used in an epoxy resin. This adhesive has a preferable property that it does not easily swell even when exposed to water. It is preferable that the adhesive has thermosetting properties.

The thickness of the organic adhesive layer 14 is 10 μm to 5 μm.
It is often set to about 0 μm, especially 20 μm to 4 μm.
It may be set to about 0 μm. If the adhesive layer 14 is too thin, sufficient adhesive strength cannot be obtained, and the base material 11
A and 11B are easily separated from each other. Conversely, since the organic adhesive has a lower elastic modulus than ceramics, if the adhesive layer 14 is too thick, cracks tend to occur in the adhesive layer 14 when stress is applied. In addition, since organic adhesives have lower thermal conductivity than ceramics,
If the thickness of the adhesive layer 14 is too large, the thermal resistance of the adhesive layer 14 increases, which may hinder the improvement in the uniformity of the table 2.

The thickness t1 of the work-affected layer L1 on the back surface of the upper substrate 11A, which is the surface to be adhered, and the surface layer of the lower substrate 11B must be set to 30 μm or less, and more preferably 10 μm or less. In particular, the thickness is preferably set to 1 μm or less (see FIG. 2B). Incidentally, the work-affected layer L1 as described above is generated on the surface layers of the base materials 11A and 11B by about several tens of μm by performing the surface finishing after the firing step.

If the thickness t1 of L1 exceeds 30 μm in the case of using an organic adhesive, the probability that the deteriorated layer L1 will fall off will increase, and it will be impossible to obtain sufficient adhesive strength. . Of course, if possible, it is preferable that the affected layer L1 is completely removed as shown in FIG. In this case, it is presumed that the grain boundaries of the crystal grains are exposed on the surface of the base material and the organic adhesive layer 14 is buried therein, so that an extremely high anchor effect can be obtained.

Here, the procedure for manufacturing the table 2 will be briefly described. First, a mixture obtained by adding a small amount of a sintering aid to silicon carbide powder is uniformly mixed. As the sintering aid, boron and its compound, aluminum and its compound, carbon and the like are selected. This is because if a small amount of this kind of sintering aid is added, the crystal growth rate of silicon carbide increases, leading to densification and high thermal conductivity of the sintered body.

Next, a mold is formed using the above mixture as a material to produce a disk-shaped molded body.
Subsequently, a groove 13 having a predetermined width and a predetermined depth is formed on almost the entire surface of the formed body by grinding the bottom surface of the formed body that is to be the upper base material 11A later. Furthermore, this molded body is
By firing in the temperature range of 00 ° C to 2400 ° C, two substrates 11A and 11B made of a silicon carbide sintered body are produced. In this case, if the firing temperature is too low, not only is it difficult to increase the crystal grain size, but also many pores remain in the sintered body. Conversely, if the firing temperature is too high, the decomposition of silicon carbide starts, resulting in a reduction in the strength of the sintered body.

After the firing step, a surface finishing process is performed, and further, the work-affected layer L1 on the back surface of the upper substrate 11A and the upper surface of the lower substrate 11B is thinned (or completely removed).
Perform processing. Examples of such a thinning process and a removing process include a mechanical process such as a surface grinding process using a grinding machine. Note that, instead of performing such a mechanical treatment, a chemical treatment may be performed. In the present embodiment, etching using an acidic etchant capable of dissolving silicon carbide corresponds to the chemical treatment. More specifically, it refers to etching using an etchant in which a predetermined amount of a weak acid is mixed with hydrofluoric acid. Examples of the weak acid include an organic acid such as acetic acid. The weight ratio of each component in hydrofluoric acetic acid is preferably hydrofluoric acid: nitric acid: acetic acid = 1: 2: 1.

Subsequently, an organic adhesive is previously applied to the upper surface of the lower substrate 11B, and then the two substrates 11A,
11B are laminated. In this state, two substrates 11A,
11B is heated to the curing temperature of the resin, and both 11A, 11B
Glue. Finally, the surface of the upper substrate 11A is polished to form a polished surface 2a having a surface roughness suitable for polishing the semiconductor wafer 5. Such a surface polishing step may be performed before the bonding step or the groove processing step. The table 2 of the present embodiment is completed through the above procedure.

In the following, some examples that embody the present embodiment are introduced. [Example 1] In the production of Example 1, "Beta Random (trade name)" manufactured by IBIDEN Co., Ltd. was used as a silicon carbide powder containing 94.6% by weight of β-type crystal. The silicon carbide powder had an average crystal grain size of 1.3 μm and contained 1.5% by weight of boron and 3.6% by weight of free carbon.

First, 5 parts by weight of polyvinyl alcohol and 300 parts by weight of water were mixed with 100 parts by weight of the silicon carbide powder, and then mixed in a ball mill for 5 hours to obtain a uniform mixture. After drying the mixture for a predetermined time to remove a certain amount of water, an appropriate amount of the dried mixture was collected and granulated. Next, the granules of the mixture were molded using a metal mold under a pressing pressure of 50 kg / cm ² . The density of the obtained green body was 1.2 g / cm ³ .

Subsequently, by grinding the bottom surface of the molded body to become the upper base material 11A later, a groove 13 having a depth of 5 mm and a width of 10 mm was formed on almost the entire bottom surface. Next, the green compact was charged into a graphite crucible capable of shutting off outside air, and was fired using a Tamman-type firing furnace. The firing was performed in an argon gas atmosphere at 1 atm. Further, at the time of baking, heating was performed at a heating rate of 10 ° C./min to a maximum temperature of 2300 ° C., and thereafter, the temperature was maintained for 2 hours. Observation of the obtained base materials 11A and 11B revealed an extremely dense three-dimensional network structure in which plate-like crystals were entangled in multiple directions. The density of the substrates 11A and 11B is 3.1 g / cm.
³ , and the thermal conductivity was 150 W / mK. Substrate 1
Boron contained in 1A and 11B was 0.4% by weight, and free carbon was 1.8% by weight.

Subsequently, after performing the surface finishing by a conventionally known method, the surface of the upper substrate 11A and the lower substrate 1A are further subjected to surface grinding as a thinning treatment.
The thickness t1 of the work-affected layer L1 in the surface layer of 1B was adjusted to be about 1 μm. Then, an epoxy resin adhesive (trade name "EP-160", manufactured by Cemedine Co., Ltd.)
The two substrates 11A and 11B were bonded and integrated by using the above. The thickness of the organic adhesive layer 14 was set to about 20 μm. The curing temperature was set at 160 ° C., the curing time was set at 90 minutes, and the load during bonding was set at 10 g / cm ² .

Further, by polishing the surface of the upper substrate 11A, a table 2 having a polished surface 2a having a surface roughness suitable for polishing the semiconductor wafer 5 was finally completed. The table 2 of Example 1 obtained in this manner was set in the above-mentioned various polishing apparatuses 1, and the cooling water W
Of the semiconductor wafers 5 of various sizes was polished while constantly circulating. As a result, for both types,
No thermal deformation was observed on the table 2 itself. Also, no cracks occurred in the organic adhesive layer 14, and a high strength was secured at the bonding interface between the substrates 11A and 11B. The bending strength at the interface was measured by a method according to JIS R1624 by performing a destructive test on Table 2 by a conventionally known method, and the average value was about 10 (?) Kgf /
It was mm ^2. Of course, no leakage of the cooling water W from the bonding interface was observed at all.

Then, when the semiconductor wafer 5 obtained through polishing by the various polishing apparatuses 1 was observed, no damage was found on the wafer 5 regardless of the wafer size. Also, there was no occurrence of a large warp in the wafer 5. That is, it was found that when the table 2 of the present embodiment was used, an extremely accurate and high quality semiconductor wafer 5 could be obtained. [Example 2] In the production of Example 2, α-type silicon carbide powder (specifically, “OY15 (trade name)” manufactured by Yakushima Electric Works Co., Ltd.) was used instead of β-type silicon carbide powder. . As a result, the density of the obtained base materials 11A and 11B was 3.1 g / cm ³ , and the thermal conductivity was 125 W / mK. The boron contained in the base materials 11A and 11B is 0.4
% Of free carbon was 1.8% by weight. even here,
By performing the above surface finishing and surface grinding,
The thickness t1 of the work-affected layer L1 in the surface layer of the surface to be bonded was adjusted to be about 5 μm.

After completing the table 2 in the same procedure as in the first embodiment, the table 2 was set in the above-mentioned various polishing apparatuses 1, and the semiconductor wafers 5 of various sizes were polished. Excellent results were obtained. Also, no cracks occurred in the organic adhesive layer 14, and high strength was secured at the bonding interface between the substrates 11A and 11B. When the flexural strength was measured in accordance with JIS R 1624 in the same manner as in Example 1, the average value was about 8 kgf / mm ² . That is, the present example using α-type silicon carbide powder as a starting material tended to have better adhesive strength than Example 1 using α-type silicon carbide powder as a starting material. [Embodiments 3 to 5] Also in Embodiments 3, 4, and 5, the table 2 was completed through basically the same procedure as in Embodiment 1. However, in Example 3, the thickness t1 of the affected layer L1 after the surface grinding was adjusted to be about 10 μm. In Example 4, the thickness t1 of the affected layer L1 after the surface grinding was adjusted to be about 20 μm. In Example 5, the thickness t1 of the affected layer L1 after the surface grinding was adjusted to be about 0 μm (that is, the affected layer L1 was completely removed).

The obtained table 2 was set in the above-mentioned various polishing apparatuses 1, and the semiconductor wafers 5 of various sizes were polished. As a result, almost the same excellent results as in the first embodiment could be obtained. Also, no cracks occurred in the organic adhesive layer 14, and high strength was secured at the bonding interface between the substrates 11A and 11B. J as in Example 1
When the flexural strength according to IS R 1624 was measured,
The average value was about 7 kgf / mm ² in Example 3, and Example 4
About 6 kgf / mm ² in Example 5, and about 12 kgf / m ² in Example 5.
It was m ^2. [Comparative Examples 1 and 2] In Comparative Example 1, while only surface finishing is performed after the firing step, the subsequent surface grinding is omitted, and the base materials 11A and 11A are formed using the epoxy resin adhesive “EP-160”. 11B were bonded together.

In Comparative Example 2, while only surface finishing was performed after the firing step, subsequent surface grinding was omitted, and
The base materials 11A and 11A were formed using an epoxy resin-based adhesive (trade name “Cemedine 110”) of a type different from that of each embodiment.
B were bonded together. The thickness of the work-affected layer L1 on the surface of the surface to be bonded was about 35 μm, which was considerably larger than those of the above examples.

The obtained also for the table 2 in Example 1 was measured bending strength by JIS R 1624, the average value is met about 1 kgf / mm ² at about 4 kgf / mm ^2, Comparative Example 2 In Comparative Example 1 Was. That is, high adhesive strength as in Examples 1 to 5 could not be obtained. Therefore, the table 2 of Comparative Examples 1 and 2 was
It was suggested that when the semiconductor wafer 5 was polished while being set to, the adhesive interface would likely be broken by the application of heat or stress.

Therefore, according to the embodiment of the present embodiment, the following effects can be obtained. (1) The table 2 of the wafer polishing apparatus 1 uses the base materials 11A and 11B in which the thickness t1 of the work-affected layer L1 on the surface of the surface to be bonded is set to 30 μm or less, and uses an organic adhesive. It is configured by using and bonding.
For this reason, sufficient strength can be given to the organic adhesive layer 14, and cracks and peeling are less likely to occur at the bonding interface. Therefore, it is possible to provide the wafer polishing apparatus table 2 which is hard to break and can withstand practical use.

Further, since the sealing property at the bonding interface is maintained, it is possible to prevent the cooling water W flowing through the water channel 12 from leaking from the bonding interface. (2) In the case of the table 2, the cooling water W can flow through the water channel 12 existing at the bonding interface between the substrates 11A and 11B. Therefore, the heat generated during polishing of the semiconductor wafer 5 can be directly and efficiently released from the table 2 and the temperature can be finely controlled. Therefore, compared with the conventional apparatus in which the table 2 is placed on the cooling jacket to perform indirect cooling, the temperature variation in the table 2 is reduced, and the heat uniformity is reliably improved. Therefore, according to this apparatus 1, the wafer 5 is less likely to be adversely affected by heat, and it is possible to cope with an increase in the diameter of the wafer 5.
In addition, since the wafer 5 can be polished with high accuracy, it is possible to cope with high quality.

(3) The table 2 has two substrates 1
A laminated structure composed of 1A and 11B is employed. Therefore, after the structure (that is, the groove 13) that becomes the water channel 12 is formed in advance on the back surface of the upper base material 11A, the base materials 11A, 11
B can be bonded together. Therefore, the water channel 12 can be formed relatively easily at the bonding interface. Therefore,
There is an advantage that there is no particular difficulty in manufacturing the table 2. Further, with this structure, it is not necessary to add a piping structure to the joint interface, so that the structure is not complicated and the cost is not increased.

(4) In the table 2 of the present embodiment, the thickness of the organic adhesive layer 14 is set within the above preferred range. For this reason, it is possible to obtain sufficient strength at the bonding interface while improving the table soaking property.

(5) The table 2 is composed of two substrates 11A and 11B made of the same type of ceramic sintered body, in other words, two substrates 11A and 11B having the same thermal expansion coefficient. . Therefore, thermal stress is hardly generated near the bonding interface, and extremely high bonding strength can be obtained. Therefore, it is possible to make the table 2 extremely hard to break.

The two substrates 1 constituting the table 2
Each of 1A and 11B is a dense body made of a silicon carbide sintered body starting from silicon carbide powder. Such a dense body is preferable because the bonding between crystal grains is strong and the number of pores is extremely small. In addition, a silicon carbide sintered body using a silicon carbide powder as a starting material is particularly superior in thermal conductivity, heat resistance, thermal shock resistance, wear resistance, and the like, as compared with other ceramic sintered bodies. Therefore, such a base material 11A,
If the polishing is performed using the table 2 made of 11B, it is possible to surely cope with an increase in diameter and quality of the semiconductor wafer 5.

(6) In the case of the wafer polishing apparatus 1 using the table 2, the cooling jacket itself is not required, so that the structure of the entire apparatus is simplified. The embodiment of the present invention may be modified as follows.

As shown in another example of the table 21 shown in FIGS. 3 and 4, the copper tube 1 is inserted into the groove 13 formed at the bonding interface.
6 may be provided to circulate the cooling water W inside the copper tube 16. Copper was selected as the tube forming material because copper has a high thermal conductivity, is inexpensive, and has excellent workability. Both ends of the spirally bent copper tube 16 are bent downward at a right angle, and are inserted into the through holes 15 respectively. Copper tube 1
6 are provided with a pair of flow paths 4 provided in the rotating shaft 4.
a.

As shown in a table 31 of another example shown in FIG. 5, at least the copper tube 1 is formed in the organic adhesive layer 14.
It is preferable that a powder (for example, copper powder) 17 made of a high thermal conductive material is mixed as a filler around 6.
With such a configuration, the thermal resistance at the bonding interface becomes smaller, so that the temperature uniformity of the table 2 can be further improved.

Table 2 of the embodiment having a two-layer structure
Alternatively, a table having a three-layer structure or a table having a multilayer structure of four or more layers may be used. The groove 13 may be formed not only on the back surface of the upper substrate 11A, but also on the upper surface of the lower substrate 11B, or may be formed on both the substrates 11A and 11B.

As a silicide ceramic other than silicon carbide, for example, silicon nitride (Si ₃ N ₄ ), sialon, or the like may be selected. Further, as a carbide ceramic other than silicon carbide, for example, boron carbide (B ₄ C) or the like may be selected. Furthermore, it is also possible to select materials other than silicide ceramics and carbide ceramics, for example, oxide ceramics represented by alumina and the like. Further, the upper base material 11A and the lower base material 11B are not necessarily made of ceramics of the same kind, and may be made of ceramics of different kinds.

In using the table 2 of the present embodiment, a liquid other than water may be circulated in the water channel 12.
Further, a gas may be circulated. The ceramic structure of the present invention is not only embodied as the table 2 of the wafer polishing apparatus 1 but may be applied to other uses (for example, a heater or the like).
In this case, the shape of the ceramic substrates bonded to each other is not limited to a plate shape, and may be, for example, a lump or a rod. Further, unless particularly necessary, the flow channel structure at the bonding interface may be omitted.

Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the above-described embodiment will be enumerated below. (1) In Claims 3 and 6, the organic adhesive layer comprises an epoxy resin and a modified polyamine and silicon oxide (S).
iO ₂ ) is mixed at a predetermined ratio.

(2) In any one of the third and sixth aspects and the technical idea 1, the ceramic substrate is a sintered body obtained by using α-type silicon carbide powder as a starting material.
Therefore, according to the invention described in the technical idea 2, higher strength can be obtained at the bonding interface.

[0062]

As described in detail above, according to the first to third aspects of the present invention, there is provided a table for a wafer polishing apparatus which is excellent in the strength of an adhesive interface, is not easily broken, and has excellent heat uniformity. be able to. In particular, according to the third aspect of the present invention, it is possible to provide a table that is extremely hard to break.

According to the invention set forth in claims 4 to 6, it is possible to provide a ceramic structure which is excellent in the strength of the bonding interface and is not easily broken. In particular, according to the invention described in claim 6, it is possible to provide a ceramic structure that is extremely hard to be broken.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a wafer polishing apparatus according to an embodiment of the invention.

FIG. 2A is an enlarged cross-sectional view of a main part of a table used in the wafer polishing apparatus according to the embodiment, and FIGS. 2B and 2C are cross-sectional views conceptually showing a further enlarged view of the bonding interface. .

FIG. 3 is a schematic view showing another example of a wafer polishing apparatus.

FIG. 4 is an enlarged sectional view of a main part of a table used in the apparatus shown in FIG. 3;

FIG. 5 is an enlarged sectional view of a main part of a table of another example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Wafer polisher, 2,21,31 ... Table for wafer polisher which is a kind of ceramic structure, 2a ... Polishing surface, 5 ... Semiconductor wafer, 6 ... Wafer holding plate, 6
a ... holding surface, 11A, 11B ... base material, 12 ... cooling water channel as fluid flow path, 13 ... groove, 14 ... organic adhesive layer,
L1: Work-affected layer, t1: Thickness of the work-affected layer.

Claims (6)

[Claims] 1. A table having a polished surface to which a semiconductor wafer held on a holding surface of a wafer holding plate constituting a wafer polishing apparatus is slidably contacted, wherein a thickness of a work-affected layer on a surface layer of a surface to be bonded is provided. In a state in which a plurality of ceramic base materials each having a thickness of 30 μm or less are laminated, the base materials are bonded to each other via an organic adhesive layer, and a fluid flow path is provided at the bonding interface of the base materials. Table for wafer polishing equipment. 2. The organic adhesive layer has a thickness of 10 μm to 5 μm.
2. The table for a wafer polishing apparatus according to claim 1, wherein the thickness is 0 μm. 3. The table for a wafer polishing apparatus according to claim 1, wherein each of the ceramic bases is a base made of a silicon carbide sintered body. 4. A structure in which ceramic base materials are bonded to each other via an organic adhesive layer, and the thickness of the work-affected layer on the surface to be bonded of the base material is set to 30 μm or less. A ceramic structure characterized by the following. 5. The organic adhesive layer has a thickness of 10 μm to 5 μm.
The ceramic structure according to claim 4, wherein the thickness is 0 μm. 6. The ceramic structure according to claim 4, wherein each of said ceramic bases is a base made of a silicon carbide sintered body.