JPH10128657A - Heating method and device for wafer-polishing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce unevenness of thickness to improve flatness by bringing a hot plate heated substantially uniformly into contact with the back of a wafer polishing plate to substantially uniformly solidifying wax applied to the surface of the wafer-polishing plate. SOLUTION: A heat conductive member 3 is heated by a heating element 2, and the back of a wafer-polishing plate 20 is made closely adhere to the heated heat conductive member 3 to be heated indirectly. Thus, wax applied to the surface of the wafer polishing plate 1 is solidified substantially uniformly. Accordingly, the wafer polishing plate 1 to which wax is applied is heated uniformly so that a raw material wafer can be stuck flat to the wafer polishing plate 1 to reduce unevenness of thickness of the mirror finished surface wafer in the polishing process to heighten flatness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to ceramics,
The present invention relates to a method and an apparatus for heating a plate for polishing a wafer in which a thickness unevenness and a flatness are improved in a polishing process of a wafer such as glass and silicon.

[0002]

2. Description of the Related Art In general, a polishing process (polishing) of a wafer made of ceramics, glass, silicon, or the like is performed as a process of manufacturing a mirror-finished wafer having optical gloss and no processing distortion.

[0003] For example, in the case of a silicon wafer, with the delicate microelectronic device structure,
The surface of the wafer is required to have a flatness of unevenness within several μm. Therefore, the polishing process (polishing) of a silicon wafer is generally performed by a single-side polishing method as shown in FIG. This is because a plurality of wafer polishing plates 2
A number of raw wafers 30 (of course, the number depends on the diameter of the wafer) are stuck with wax 22 or the like to zero, and pressed with appropriate pressure onto a rotary polishing table 24 to which a polishing cloth 26 (artificial leather) is adhered. . An alkaline colloidal silica polishing liquid containing SiO ₂ as a main component is injected into the polishing cloth 26.

Polishing with alkaline colloidal silica is described by a mechanochemical process based on the combined action of mechanical polishing with SiO ₂ abrasive grains and chemical etching with an alkaline solution. Due to this chemical etching action, no processing strain remains on the silicon surface. As a result, a mirror-finished wafer having optical luster and no processing distortion can be manufactured.

As a pre-process for performing such a polishing step (polishing), as shown in FIG. 5B, wax 22 is applied to the surface of the wafer polishing plate 20 by spin coating. Next, the wafer polishing plate 20
Is heated, and the wafer 30 is attached to the softened wax 22 to attach the wafer 30. However, since the wafer polishing plate is often made of ceramic and has a large thickness, it is difficult to heat the plate.

Conventionally, steam (about 100 ° C.) has been brought into direct contact with the back surface of a wafer polishing plate using a steam pot. However, in this method, a part of the steam is cooled before the steam reaches the wafer polishing plate, so that the wafer polishing plate is not uniformly heated,
Temperature unevenness (± 10 ° C.) occurs, and the hardness of the wax at each position applied to the wafer polishing plate becomes uneven, so that the wafer cannot be stuck flat and thickness unevenness occurs. In addition, excess steam goes around the wafer polishing plate surface, and a uniform wax layer is dissolved,
Due to the unevenness of the wax, the wafer cannot be stuck flat, resulting in uneven thickness. If the polishing step (polishing) is performed in this state, the flatness of the mirror-polished wafer is reduced and the thickness is uneven. Further, in the method using the steam pot, since the steam is used, there is a limit in the rate of temperature rise and temperature control.

[0007] Therefore, a method of heating a wafer polishing plate using an IR lamp has been attempted. However, when heated from the front side of the wafer polishing plate, unevenness occurs in the applied wax, and the wafer does not stick flatly.
In the polishing step (polishing), the flatness of the mirror surface wafer is reduced and the thickness is uneven. Further, when heating is performed from the back side of the wafer polishing plate, the heat transfer efficiency is poor, so the output of the IR lamp needs to be increased. for that reason,
This requires a large amount of power supply and cooling of the device, which is not practical.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to improve thickness unevenness and flatness in a polishing process. A method and an apparatus for heating a wafer polishing plate are provided.

[0009]

That is, according to the present invention, there is provided a method for heating a wafer polishing plate, wherein the back surface of the wafer polishing plate having a surface coated with wax is heated substantially uniformly. There is provided a method for heating a wafer polishing plate, wherein the wax applied to the surface of the wafer polishing plate is substantially uniformly solidified by contacting the heating plate.

Further, according to the present invention, there is provided a method for heating a wafer polishing plate, wherein an adsorbing member for adsorbing the wafer polishing plate is disposed between the wafer polishing plate and the heating plate. Provided.

Further, according to the present invention, there is provided a suction member for sucking the wafer polishing plate, and a heating plate capable of detachably contacting the suction member, wherein the heating plate has a heating element therein. And a heating apparatus for the wafer polishing plate, wherein the surface of the heating plate is heated substantially uniformly.

Further, in the present invention, the heating element is preferably an electric heater.

In the present invention, the temperature of the heating plate is preferably 100 to 200 ° C., and the temperature of the wafer polishing plate is preferably 60 to 90 ° C.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a method for heating a wafer polishing plate, in which a substantially uniformly heated heating plate is brought into contact with the back surface of a wafer polishing plate having a surface coated with wax. Thus, the wax applied to the surface of the wafer polishing plate is solidified almost uniformly. Alternatively, an adsorbing member for adsorbing the wafer polishing plate is disposed between the wafer polishing plate and the heating plate.

By uniformly heating the wax-coated wafer polishing plate, the raw material wafer can be stuck flat to the wafer polishing plate, and unevenness in the thickness of the mirror-surface wafer in the polishing process can be reduced. It can contribute to the improvement and the degree of flatness.

Further, when the temperature of the actual wafer polishing plate is raised, the temperature of the heating plate is preferably 100 to 200 ° C. in consideration of the damage of the ceramic due to thermal shock, and the like.
The temperature is more preferably from 130 to 150 ° C. Furthermore,
Since the raw material wafer is stuck flat to the wafer polishing plate using wax, the wafer polishing plate temperature becomes
Preferably it is 60 to 90 ° C. The optimum temperature of the wafer polishing plate is determined by the temperature dependence of the hardness of the wax used.

In the method of heating a wafer polishing plate according to the present invention, it is preferable to use an electric heater as a heating element embedded in the heating plate because the temperature of the heating plate can be easily controlled. Further, it is preferable that the polishing plate is vacuum-adsorbed to the heating plate because the heating plate and the polishing plate can be uniformly contacted and contribute to improvement in heat transfer efficiency. Thereby, the temperature unevenness of the heating plate is ± 2 ° C., and the temperature unevenness of the suction member is also ± 3 to
It can be 4 ° C.

The material of the plate for polishing a wafer of the present invention is not particularly limited, but usually, a ceramic material such as alumina or silicon carbide is used. Further, it is preferable that the flatness on both sides is 1 μm or less in order to obtain a flat wafer.

As the wax for the wafer polishing plate of the present invention, a wax based on pine tar is used. This wax is uniformly coated on the wafer polishing plate by spin coating, and the polishing plate is heated using a heating plate in order to obtain optimal hardness for attaching the wafer.

Hereinafter, the present invention will be described in detail with reference to the drawings. 1A and 1B show an example of a heating device for a wafer polishing plate according to the present invention, wherein FIG. 1A is a schematic front view, and FIG.
It is an AA sectional view of (a). FIG. 2 is a front perspective view showing an example of the arrangement of the heating elements of the heating plate used in the wafer polishing plate heating apparatus of the present invention. FIG.
It is another example of the heating apparatus of the plate for wafer polishing of this invention, (a) is a schematic front view, (b) is AA of (a).
It is sectional drawing. 4A and 4B show an example of an adsorption member used in another example of the wafer polishing plate heating apparatus of the present invention. FIG. 4A is a schematic front view, and FIG. 4B is an AA of FIG.
It is sectional drawing.

As shown in FIGS. 1A and 1B, an example of the wafer polishing plate heating apparatus of the present invention includes a heating plate 1 for uniformly heating a wafer polishing plate 20. I have.

The heating plate 1 is shown in FIGS. 1 (a) and 1 (b).
As shown in FIG. 1, the heating element 2 includes a heat conducting member 3 in which the heating element 2 is embedded, a heat insulating member 4, and a base 10 to which a power terminal 8 of the heating element 2 and a temperature detector 6 are attached. .

The use of an electric heater for the heating element 2 not only significantly reduces the time required for temperature rise than in the conventional method, but is also preferable in terms of maintenance management. Heating element 2
As shown in FIG. 2, three heat generating elements 2
Is preferably embedded in an arc shape. Although the power supply circuit of each heating element 2 may be a single system, in order to obtain a more uniform temperature distribution, the power supply circuit of each heating element 2 is divided into a plurality of systems, and the results are obtained by a plurality of temperature detectors. It is more preferable to control each of them by feedback.

The heat conducting member 3 is preferably made of a material having a high heat conductivity in order to transmit heat uniformly. Such a material is not particularly limited, and examples thereof include aluminum.

The heat insulating member 4 is used to protect the base 10 from heat, and is preferably made of a material having a low thermal conductivity. Such a material is not particularly limited, and examples thereof include rock wool.

The base 10 has a function as a mount for the temperature detector 6 and the power supply terminal 8 of the heating element 2 while holding the heat conducting member 3. The attachment to the heat conducting member 3 is fixed using the heat conducting member holding bolts 12.

As the temperature detector 6, a thermocouple, a resistance temperature detector, or the like is used. The temperature detector 6 is arranged near the center of the heating plate 1 when the power supply circuit of the heating element 2 is a single system, and near the center of each heating element 2 when the power supply circuit of the heating element 2 is plural. It is preferable to measure the temperature in real time. Further, it is preferable to adjust the electric heater to adjust the temperature of the heating plate by feeding back the result to the program temperature controller. The temperature of the wafer polishing plate is measured by an infrared sensor separate from the heating plate. When the temperature is raised to the target temperature, the plate is separated from the heating plate and sent to the next step.

The heating plate 1 used in the present invention is
Rather than directly heating the wafer polishing plate 20 with the heating element 2, indirect heating such that the heat conduction member 3 is first heated by the heating element 2 and the wafer polishing plate 20 is brought into close contact with the heated heat conduction member 3. It is carried out. This is because the heat conductive member 3 can be easily replaced when the adhesion to the polishing plate is deteriorated due to damage or the like.

Another example of the apparatus for heating a wafer polishing plate according to the present invention is as shown in FIGS. 3 (a) and 3 (b).
The heating plate 1 includes a heating plate 1 for uniformly heating the wafer polishing plate 20 and an adsorbing member 15 that is detachably attached to the heating plate 1 and adsorbs and fixes the wafer polishing plate 20. The above-described heating plate 1 can be used alone, but by attaching the suction member 15 of the present invention, the close contact and fixation with the wafer polishing plate 20 can be further ensured. Further, even if the suction member 15 is contaminated or damaged, it can be easily replaced.

As shown in FIG. 4, the suction member 15 is provided with a plurality of independent suction portions 16 on the suction surface of the suction member 15 in order from the center to the peripheral portion of the suction surface. 17 is connected to a vacuum pump. Further, the suction portion 16 has a concentric annular groove which is the center of the suction surface. Thus, after the wafer polishing plate is set at a fixed position, it can be closely attached and fixed by suctioning with a vacuum pump. Further, the outer surface of the suction portion 16 on the suction surface of the suction member 15 is
-It is more preferable to provide an annular sealing member such as a ring. Note that the shape of the suction member 15 is not limited to the above, and is not particularly limited as long as a similar effect can be obtained.

The suction surface of the suction member 15 has a flatness of 10 μm because the wafer polishing plate directly contacts the suction surface.
The following is preferable from the viewpoints of the degree of vacuum and the heat conduction during vacuum suction. Further, it is preferable that the suction member 15 is fixed by the suction member mounting bolt 19 so as not to move.

Further, the material of the adsorbing member 15 is preferably a material having high thermal conductivity and easily transmitting heat uniformly. Such a material is not particularly limited, and examples thereof include aluminum and the like.

[0033]

EXAMPLES The present invention will be described in more detail based on examples, but the present invention is not limited to these examples. The mirror-finished wafer obtained by the wafer polishing plate heating apparatus of the present invention was evaluated by the following method.

(Method of Measuring Dimples) The frequency of occurrence of dimples was evaluated using a magic mirror device.

(Method of Measuring TTV and LTV) Capacitance type flatness measuring device (made by ADE: UltraGage 95)
00).

(Examples 1, 2 and Comparative Example 1: Temperature Distribution Test of Wafer Polishing Plate) The wafer polishing plate heating apparatus of the present invention employs a heating plate (Example 1) and a heating plate. In the case where the suction member was attached (Example 2) and the case where a conventional steam pot was used (Comparative Example 1), a contact-type thermometer was used at four points on the wafer polishing plate and an IR sensor was used at the center. 60 seconds after the start of heating, the temperature was measured. The wafer polishing plate was made of alumina and had a diameter of 400 mm and a thickness of 16 mm.

Table 1 shows the results of the temperature distribution test of the wafer polishing plate obtained as described above.

[0038]

[Table 1]

(Example 2, Comparative Example 2: Evaluation Test of Polished Wafer) In the case where a heating apparatus for a wafer polishing plate of the present invention was used to attach a raw material wafer to a wafer polishing plate (Example 2) In the case where a conventional steam pot was used (Comparative Example 2), a wafer polishing step (polishing) was performed, and an evaluation test was performed on the mirror-finished wafer produced thereby. The polishing process (polishing)
Using a polishing pad (Roba: Suba600)
Mechanochemical polishing with colloidal silica solution
Minutes. In addition, as various conditions, polishing pressure: 350 g
/ Cm ² , polishing temperature: 45 ° C., turntable rotation speed:
This was performed at 110 rpm and a slurry flow rate of 500 cc / min.

Table 2 shows the results of evaluation tests on the polished wafers obtained as described above.

[0041]

[Table 2]

(Discussion 1: Temperature distribution test of wafer polishing plate) From Table 1, in the case of the heating plate of the present invention (Example 1), the temperature difference between the contact surface with the wafer polishing plate is about ± 1 ° C. Can be As a result, the temperature difference at each measurement point of the wafer polishing plate can be kept within 4 ° C., which is a very good state as compared with 10 ° C. in the case of the conventional steam pot (Comparative Example 1). It is possible. In addition, the heating time of the heating plate of the present invention (Example 1) can be greatly reduced as compared with the conventional steam pot (Comparative Example 1), and the control can be easily performed. is there. Further, when an adsorption member is attached to the heating plate of the present invention (Example 2)
Can more effectively heat the wafer polishing plate as compared with the case of the heating plate of the present invention (Example 1).

(Discussion 2: Evaluation Test of Mirror Wafer) Table 2
Thus, the wafer polishing plate heating apparatus (Example 2) of the present invention can significantly improve dimples, which have been a problem of the conventional steam pot (Comparative Example 2), and can make the hardness of wax uniform. . Therefore, as is clear from the values of TTV and LTV, the flatness of the mirror wafer can be significantly improved.

[0044]

As is apparent from the above description, the method and apparatus for heating a wafer polishing plate according to the present invention uniformly heat a wax-coated wafer polishing plate and apply a raw material wafer to the wafer polishing plate. By flatly attaching the wafer, it is possible to contribute to the improvement of the unevenness of the thickness of the mirror surface wafer and the improvement of the flatness in the polishing process.

[Brief description of the drawings]

FIG. 1 is an example of a heating device for a wafer polishing plate according to the present invention, wherein (a) is a schematic front view and (b) is (a).
It is AA sectional drawing of.

FIG. 2 is a front perspective view showing an example of an arrangement of heating elements of a heating plate used in the heating device for a wafer polishing plate of the present invention.

3A and 3B show another example of a heating device for a wafer polishing plate of the present invention, wherein FIG. 3A is a schematic front view, and FIG.
It is an AA sectional view of (a).

FIG. 4 is an example of an adsorbing member used in another example of the wafer polishing plate heating apparatus of the present invention.
FIG. 2B is a schematic front view, and FIG.

FIG. 5 is an example of a general single-side polishing method, in which (a) is a schematic explanatory view and (b) is a schematic perspective view of a wafer polishing plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating plate 2 Heating element 3 Heat conduction member 4 Heat insulation member 6 Temperature detector 8 Power supply terminal 10 Base 12 Heat conduction member mounting bolt 15 Suction member 16 Suction unit 17 Communication member 18 Suction member mounting hole 19 Suction member mounting bolt 20 Wafer polishing Plate 22 Wax 24 Rotary Polishing Table 26 Polishing Cloth 28 Polishing Liquid 30 Raw Material Wafer

Claims (9)

[Claims] 1. A method of heating a wafer polishing plate, comprising: bringing a substantially uniformly heated heating plate into contact with the back surface of the wafer polishing plate having a surface coated with wax to thereby form a wafer polishing plate. A method for heating a plate for polishing a wafer, wherein the wax applied to the surface of the plate is solidified substantially uniformly. 2. The method for heating a wafer polishing plate according to claim 1, wherein an adsorbing member for adsorbing the wafer polishing plate is disposed between the wafer polishing plate and the heating plate. 3. The method for heating a plate for polishing a wafer according to claim 1, wherein a heating element comprising an electric heater is embedded in the heating plate. 4. A heating plate temperature of 100 to 200 ° C.
The method for heating a plate for polishing a wafer according to any one of claims 1 to 3, wherein 5. The wafer polishing plate temperature is from 60 to 9
The method for heating a plate for polishing a wafer according to any one of claims 1 to 4, wherein the temperature is 0 ° C. 6. An adsorbing member for adsorbing a wafer polishing plate, and a heating plate capable of detachably contacting the adsorbing member, wherein the heating plate has a heating element embedded therein for heating. A heating device for a wafer polishing plate, wherein the surface of the plate is heated substantially uniformly. 7. The heating device for a wafer polishing plate according to claim 6, wherein the heating element is an electric heater. 8. The heating plate temperature is 100 to 200 ° C.
The heating device for a wafer polishing plate according to claim 6, wherein: 9. The wafer polishing plate temperature is 60 to 9
The heating apparatus for a wafer polishing plate according to claim 6, wherein the heating temperature is 0 ° C. 10.