Patent Grant
7288020
1. Field of the Invention
The present invention relates to a blast processing method, and more specifically, to a blast processing method for removing a deposit adhered onto a component part of a semiconductor manufacturing apparatus.
2. Description of the Related Art
In usual, in manufacture of a semiconductor device, various films such as a silicon oxide film are formed on a wafer by using a semiconductor manufacturing apparatus.
In a step of generating the films, a deposition is sometimes adhered onto a heater, an electrostatic chuck, or a susceptor, which constructs the semiconductor manufacturing apparatus. When the deposition is adhered onto the heater or the susceptor, uniform heating performance for the wafer is decreased, and reproducibility of device characteristics or the like is reduced. Moreover, when the deposition is adhered onto the electrostatic chuck, sufficient electrostatic suction force is not generated, and surface roughness thereof or the like is changed to change a degree of contact of the electrostatic chuck with the wafer and a way of heat transfer therefrom to the wafer. Thus, the uniform heating performance for the wafer at a time of plasma heat input is decreased, and the reproducibility of the device characteristics or the like is reduced.
Therefore, process of periodically removing the deposit adhered onto such a component part of the semiconductor manufacturing apparatus has been heretofore performed (for example, refer to Japanese Patent Laid-Open Publication Nos. 2002-28599 and 2005-193308).
However, though a deposit removal method described in a related art of Japanese Patent Laid-Open Publication No. 2002-28599 is a method of blowing blasting beads to such a processing object, there has been an apprehension that the blasting beads may remain on the processing object, resulting in being a particulate contamination source.
Moreover, a deposit removal method disclosed in Japanese Patent Laid-Open Publication No. 2005-193308 is a method of blowing a blasting material to the processing object. However, since a pressure and the like at a time of blowing the blasting material are not regulated, there has been an apprehension that such a problem may occur that a surface of the processing object is damaged when the pressure is too large.
It is an object of the present invention to provide a blast processing method capable of certainly removing the deposit without damaging the surface of the processing object.
In order to achieve the above-described object, the present invention is a blast processing method for blowing a blasting material onto a surface of a processing object formed of aluminum nitride and removing a deposit adhered onto the surface, characterized in that abrasive grains made of silicon carbide or aluminum oxide and having a grain size of #400 to #800 are used as the blasting material, and a blast pressure as a pressure when the blasting material collides with the surface of the processing object is set at 40 to 150 gf/cm2.
In accordance with the blast processing method according to the present invention, only the deposit adhered onto the surface can be removed without damaging the surface of the processing object. Moreover, even after the blast processing, the blasting material hardly remains on the surface.
A description will be made below of an embodiment of the present invention.
[Processing Object]
In this embodiment, for a processing object, a member made of aluminum nitride (AlN) is used. For example, as the processing object, a component part of a semiconductor manufacturing apparatus, such as a ceramic heater, an electrostatic chuck, and a susceptor, can be employed.
[Blasting Material]
As the blasting material, abrasive grains are used, which are made of silicon carbide (SiC) or aluminum oxide (Al2O3), and have a grain size of #400 to #800. When the grain size is less than #400, there is a problem that fine irregularities are formed on the surface 3a of the plate member 3, resulting in a decrease of uniform heating performance of the processing object. Meanwhile, when the grain size is larger than #800, there is a problem that it takes very long to perform the processing since it becomes difficult to sufficiently remove the deposit on the plate member 3.
[Blast Processing Apparatus]
As shown in
As shown in
The blowing means 11 is configured to run in the x-direction, the y-direction and up and down. These mounting stage 9 and blowing means 11 are configured to run individually.
An insertion hole 13 is drilled in a center portion of the mounting stage 9, and a shaft member 5 of the ceramic heater 1 is inserted into the insertion hole 13. Moreover, the lower surface of the plate member 3 is made to abut on an upper surface of the mounting stage 9, and the ceramic heater 1 is thus mounted on the mounting stage 9.
Moreover, as shown in
Specifically, as shown in
Hence, as shown in
[Blast Processing Condition]
In this embodiment, a blast pressure as a pressure when the blasting material 19 collides with the surface 3a of the plate member 3 (processing object) is set at 40 to 150 gf/cm2. The blast pressure is a pressure which the plate member 3 receives from the blasting member 3 by the fact that the blasting material 19 and gas are blown to the surface 3a of the plate member 3.
When the blast pressure is less than 40 gf/cm2, the problem is present that it takes very long to perform the processing since it becomes difficult to sufficiently remove the deposit on the plate member 3. Meanwhile, when the blast pressure exceeds 150 gf/cm2, there is an apprehension that the surface 3a of the plate member 3 may be damaged. When the surface 3a is damaged, the fine irregularities are formed on the surface 3a, and the uniform heating performance is thus decreased, and accordingly, this is not preferable.
Note that, more preferably, the blast pressure is 60 to 100 gf/cm2.
Moreover, it is preferable that a moving speed of the nozzle portions 17 be 5 to 15 cm/min, and it is preferable that a distance from the tip ends of the nozzle portions 17 to the surface 3a of the processing object be 6 to 12 cm.
[Blowing Amount of Blasting Material]
On the surface 3a of the plate member 3 of the ceramic heater 1 as the processing object, it is preferable to set a blowing amount of the blasting material 19 per unit area at 1.4 to 4.3 g/cm2.
When the blowing amount is less than 1.4 g/cm2, it takes very long to perform the processing since it becomes difficult to sufficiently remove the deposit on the plate member 3. Meanwhile, when the blowing amount is larger than 4.3 g/cm2, the fine irregularities are formed on the surface 3a of the plate member 3, resulting in the decrease of the uniform heating performance.
Note that, more preferably, the blowing amount is 1.7 to 2.8 g/cm2.
Subsequently, a description will be briefly made below of a calculation method for calculating the blowing amount of the blasting material 19 by using
A blowing amount per square millimeter on the surface 3a of the plate member 3 is represented as Q [g/mm2]. A total time of blowing the blasting material 19 is represented as T [sec]. A blowing amount of blowing the blasting material 19 for one second per square millimeter on the surface 3a of the plate member 3 is represented as q [g/sec·mm2. The moving speed of the nozzle portions 17 is represented as V [mm/sec]. A length of one pass of each of the nozzle portions 17 is defined as 200 [mm]. A moving time of each nozzle portion 17 per pass is represented as t [sec]. An amount of the blasting material 19 supplied to the nozzle portions 17 for one second is represented as G [g/sec].
First, the blowing amount Q per square millimeter on the surface 3a of the plate member 3 is obtained by the following calculating expression:
Q=T×q (Expression 1)
Here, T just needs to be obtained by multiplying the moving time per pass by the number of passes. When one pass is ended, each nozzle portion 17 laterally shifts by a predetermined distance (for example, 5 mm) to transfer to the next pass. Accordingly, a sum of the number of passes for processing the plate member 3 is obtained as:
200 [mm]/5 [mm]=40 [times]
Hence, the following calculating expression is established:
T=(200/V)×(200/5)=8000/V (Expression 2)
Moreover, the blowing amount q of blowing the blasting material 19 for one second per square millimeter on the surface 3a of the plate member 3 is obtained by the following calculating expression.
q=G/(200×200)=G/40000 (Expression 3)
When Expression 2 and Expression 3 are substituted into Expression 1 described above, the following calculating expression is established:
Q=T×q=(8000/V)×(G/40000)=G/5V [g/mm2] (Expression 4)
[Blast Processing Method]
A description will be made of a procedure of implementing the blast processing for the ceramic heater 1 as the processing object.
First, as shown in
Subsequently, as shown in
Then, such a horizontal movement is stopped at an endpoint of the movement, and in this state, the mounting stage 9 is shifted in the X-direction by the predetermined distance (for example, 5 mm). Thereafter, the blowing means 11 is horizontally moved in a direction (in the Y-direction) reverse to the previous moving direction. By repeating such operations, the blast processing by a predetermined number of passes (for example, 40 passes) is performed.
After the blast processing is ended, the surface 3a of the plate member 3 is ultrasonically washed with pure water and isopropyl alcohol (IPA), followed by drying.
A description will be made below of functions and effects, which are brought by the embodiment of the present invention.
In accordance with the blast processing method according to this embodiment, as the blasting material, the abrasive grains are used, which are made of silicon carbide or aluminum oxide, and have a grain size of #400 to #800. Moreover, the blast pressure as the pressure when the blasting material collides with the surface 3a of the plate member 3 of the ceramic heater 1 as the processing object is set at 40 to 150 gf/cm2. Accordingly, the surface 3a is not damaged even after the blast processing, and therefore, the uniform heating performance of the used ceramic heater 1 returns to an initial state thereof where the ceramic heater 1 is unused. Hence, the ceramic heater 1 can be suitably reused. Note that the blast processing method according to this embodiment can also be applied to the susceptor and the electrostatic chuck, which are the processing objects, as well as the ceramic heater 1.
When, as the processing object, the electrostatic chuck is subjected to the processing, suction force thereof and a degree of contact thereof with a wafer when the electrostatic chuck sucks the wafer are restored to a state where the electrostatic chuck is unused. In such a way, a temperature distribution of the electrostatic chuck becomes normal, and uniform heating performance thereof becomes equivalent to that in an initial state.
A description will be made below of the present invention through examples more specifically.
First, as the processing object, the ceramic heater 1 made of aluminum nitride, of which size is Ø300 mm, was prepared. By using the ceramic heater 1, 10,000 wafers were processed by CVD processing. As a result, the uniform heating performance for the wafers at a heating temperature of 500° C. was decreased by 5° C. as compared with that in an initial state. Here, the uniform heating performance for the wafers refers to a difference between the highest temperature and the lowest temperature on each wafer. It is conceived that the decrease of the uniform heating performance occurred since the deposition was adhered onto the ceramic heater 1.
The blast processing according to the present invention was implemented for the ceramic heater 1 that had processed 10,000 wafers.
First, as shown in
Then, the blasting material 19 was jetted from the nozzle portions 17 while horizontally moving the blowing means 11 in the Y-direction. Here, the nozzle portions 17 were arranged so as to be spaced by 100 mm from one another in the X-direction and the Y-direction. Then, as shown in
Subsequently, the blowing means 11 was held at the terminal end, and the mounting stage 9 was moved in a sliding manner in the X-direction by 5 mm. Thereafter, the blowing means 11 was turned back in the (−Y)-direction, and was moved horizontally. Such operations were repeated. Then, as shown in
Note that a setting was made so that each blowing amount per unit area on the surface 3a of the plate member 3 could be uniform with those of the others. Moreover, a supply amount per unit time of the blasting material 19 supplied to one nozzle portion 17 was set at 2.67 μg/sec].
Processing conditions in the above-described blast processing are shown in Table 1 to be shown below.
Moreover, the ceramic heaters 1 subjected to the blast processing under the conditions shown in Table 1 were disposed in the atmosphere, and the wafers with the size of Ø300 mm were mounted on the surfaces 3a of the plate members 3. Then, the heaters were heated up to 500° C., and uniform heating performances (differences between the maximum values and minimum values of the temperatures of the wafers) were measured by a TC wafer that has multiple thermocouples on the wafer.
As shown in Table 1, the ceramic heaters 1 subjected to the blast processing under the conditions of the present invention examples were better in uniform heating performance than those in the cases of the comparative examples. Then, the uniform heating performances of the ceramic heaters 1 became substantially equivalent to those in an unused initial state, and it became possible to sufficiently reuse the ceramic heaters 1.
Subsequently, used electrostatic chucks with a size of Ø300 mm were used as the processing objects, and the blast processing was implemented for the electrostatic chucks under conditions shown in Table 2 to be shown below.
While heating the electrostatic chucks subjected to the blast processing under the conditions in Table 2 by means of a lamp of 1500 W in vacuum, suction forces of the electrostatic chucks were measured by using a wafer backside gas pressure measuring method. These suction forces were compared with those of unused electrostatic chucks, and reductions from the suction forces of the unused electrostatic chucks were measured. As a result, according to the present invention examples, the suction forces became equivalent to those of the unused electrostatic chucks, and the uniform heating performances for the wafers also became equivalent to those of the unused electrostatic chucks.
Subsequently, used susceptors with a size of Ø200 mm were used as the processing objects, and the blast processing was implemented for the susceptors under conditions shown in Table 3 to be shown below.
Adhesive tapes were put onto and peeled from the surfaces 3a of the susceptors subjected to the blast processing under the conditions in Table 3, and were observed by means of SEM/EDS. As a result, when the blast processing was performed under the conditions of the present invention examples, the blasting materials 19 or the deposits were not detected. Meanwhile, in the cases of the comparative examples, Al, F, Si, and C, which are components of the deposits, were detected. It is assumed that Al was from aluminum nitride as a component of the electrostatic chucks, that F was generated from gas for use in the CVD processing, and that Si and C are components of the blasting material 19.
Subsequently, used electrostatic chucks with a size of Ø200 mm were used as the processing objects, and the blast processing was implemented for the electrostatic chucks under conditions shown in Table 4 to be shown below.
Si wafers were sucked onto the electrostatic chucks subjected to the blast processing under the conditions shown in Table 4, and particle amounts on back surfaces of the Si wafers were measured by means of a particle counter.
When the blast processing was implemented under the conditions of the present invention examples in Table 4, the particle amounts were small.
Meanwhile, when the blast processing was implemented under the conditions shown in the comparative examples, the particle amounts were increased as compared with those in the present invention examples. This is assumed to be caused by the following phenomenon. Specifically, in addition to the particles of the blasting material 19 remaining on the surfaces of the electrostatic chucks, the aluminum nitride itself was formed into particles owing to grain separation and the like as a result of damage to the surfaces of the electrostatic chucks, or the back surfaces of the wafers were damaged to some extent since the surface roughness of the electrostatic chuck became too large.
Moreover, the suction forces of the electrostatic chucks were not generated sufficiently in a part of the comparative examples, and there, it became difficult to suck the wafers. Accordingly, it was impossible to measure the particle amounts.
This application is based upon and claims the benefit of priority from prior U.S. Provisional Application No. 60/778,749, filed on Mar. 3, 2006; the entire contents of which are incorporated herein by reference.
| Number | Name | Date | Kind |
|---|---|---|---|
| 20020168867 | Haerle et al. | Nov 2002 | A1 |
| 20030162483 | Saka et al. | Aug 2003 | A1 |
| Number | Date | Country |
|---|---|---|
| 2002-028599 | Jan 2002 | JP |
| 2005-193308 | Jul 2005 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 60778749 | Mar 2006 | US |
