JP4843883B2 - Sputtering target - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sputtering target that can be suitably used in the production of a thin film.
[0002]
[Prior art]
A wide variety of thin films are used in devices such as semiconductor elements, recording media, and flat panel displays (FPD) that support the information society and multimedia in recent years. Examples of means for forming a thin film include sputtering, vacuum deposition, and CVD. Among these, the sputtering method is advantageous in forming a uniform film over a large area, and is therefore widely used in the field of FPD.
[0003]
Thin film forming sputtering apparatuses for FPD are roughly classified into two types: a stationary facing type single wafer type apparatus and a substrate passing type in-line apparatus. With the recent increase in size of FPDs, the size of glass substrates used for panel manufacture has increased, and as a result, the targets used for thin film manufacture have also increased in size in accordance with the substrate size. For example, the static counter type sputtering apparatus target reaches 810 mm × 910 mm, and the inline type sputtering apparatus target reaches 300 mm × 980 mm.
[0004]
Materials used as FPD targets are broadly classified into metal materials typified by chromium, aluminum (alloy), molybdenum (molybdenum alloy), and ceramic materials typified by ITO (Indium Tin Oxide). . When a ceramic material is used as the target material, when producing a large target as described above, the production yield decreases due to the deterioration of the moldability of the powder, so a plurality of sintered bodies can be placed on one backing plate. A multi-divided target joined to the substrate is used.
[0005]
Joining of the sintered body, which is the target member, to the backing plate is performed by heating both the sintered body and the backing plate to the melting point of the solder material or higher, and then cooling. During this cooling process, there is a problem that the target warps due to the difference in thermal expansion coefficient between the sintered body and the backing plate, stress is applied to the sintered body, and the sintered body breaks. In addition, after the target is attached to the sputtering apparatus in the film formation process, the sintered body is also cracked by the stress caused by the warp caused by the atmospheric pressure from the back when the target is evacuated and the thermal stress generated during sputtering. The problem that it ends up has arisen. Although the cracked target depends on the degree, it cannot be discharged, or even if it can be discharged, it will lead to abnormal discharge and a large amount of particles, so it can not be used for sputtering, and it is important to solve It was an issue.
[0006]
Japanese Patent Laid-Open No. 2001-26863 discloses that the generation of cracks can be reduced by making the grinding direction of the target surface parallel to the direction of warpage occurring in bonding, and the surface roughness (Ra) of the sintered body is further reduced. It has been reported that the bending strength can be improved. However, when the inventors examined in detail about several types of sintered bodies in which the grinding direction produced in accordance with the method described in the above publication is parallel to the warping direction of the target, even if the sintered bodies have the same degree of Ra, It became clear that there was a difference in bending strength for each sintered body.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to provide a ceramic material sputtering target that can more reliably reduce the ceramic material target manufacturing process (particularly the bonding process) and the cracking of the sintered body that occurs when the target is attached to a film forming apparatus and subjected to sputtering. There is.
[0008]
[Means for Solving the Problems]
The present inventors examined in detail the correlation between the processing method of the ceramic sintered body and the bending strength. As a result, (1) the bending strength of the sintered body is improved by increasing the hardness of the sintered body, (2) the bending strength is improved by reducing the surface roughness during processing, and (3) the same. It was found that the bending strength was different even when the ITO sintered body having a certain hardness was processed to the same surface roughness. And as a result of investigating the different factors of bending strength even when processed to the same degree of surface roughness with respect to the ITO sintered body having the same degree of hardness, from the sputtering surface and the side surface of the sintered body Residual processing flaws in the edge portion parallel to the grinding direction among the configured edge portions have a great influence on the bending strength, and the R surface machining or C surface is applied to the edge portion parallel to the grinding direction. By processing and removing the residual processing flaws, it is possible to prevent stress from concentrating on the processing flaws, so that the bending strength of the sintered body can be stably improved, and the occurrence of cracks in the sintered body can be ensured. The inventors found that it can be suppressed and completed the present invention.
[0009]
That is, the present invention is a sputtering target including a rectangular sintered body in which surface grinding is performed on the sputtering surface in a direction substantially parallel to the major axis, and is composed of the sputtering surface and the side surface of the sintered body. It is a sputtering target chamfered with respect to an edge part parallel to a grinding direction among edge parts.
[0010]
The sintered body of the present invention can be applied to any type of sputtering target such as any size, single wafer type, in-line type, etc., but the larger the target size, the more reliably the cracking of the sintered body can be reduced. The effect of the present invention can be easily obtained. Further, for example, even when only one sintered body is joined on one backing plate as shown in FIG. 1, it is possible to adapt even when a plurality of sintered bodies are joined. When a plurality of sintered bodies are bonded on one backing plate, all of the bonded sintered bodies as shown in FIG. 2 are subjected to surface grinding in a direction parallel to the major axis on the sputtering surface. It is not necessary that the surface be ground in the direction parallel to the long axis on the sputtering surface of at least one sintered body as seen in FIG.
[0011]
Hereinafter, the case where ITO is adopted as the sintered body will be described in detail.
[0012]
First, an ITO molded body is manufactured by adding a binder or the like to a mixed powder of indium oxide powder and tin oxide powder and molding the mixture by a molding method such as a press method or a casting method.
[0013]
As the molding method, either a pressing method or a casting method can be used, but a casting method that easily obtains a dense molded body is preferable. At this time, if the average particle size of the powder used is large, densification of the sintered body may not proceed. Therefore, the average particle size of the powder used is desirably 1.5 μm or less, and more preferably 0.8. 1 to 1.5 μm. Next, consolidation processing such as CIP is performed on the obtained molded body as necessary. Here CIP pressure is sufficient for obtaining a consolidation effect 2 ton / cm ² or more, it is desirable that preferably is 2~3ton / cm ^2.
[0014]
Here, when the first molding is performed by a casting method, a binder removal treatment may be performed for the purpose of removing moisture remaining in the molded body after CIP and organic substances such as a binder.
[0015]
Even when the first molding is performed by the press method, it is desirable to perform the same debinding process when a binder is used during molding.
[0016]
The molded body thus obtained is put into a sintering furnace and sintered. Any method can be used as the sintering method, but in the air, it is desirable to sinter in the air in consideration of the cost of production facilities. The sintering conditions can be selected as appropriate, but in order to obtain a dense sintered body and to suppress evaporation of tin oxide, the sintering temperature is preferably 1450 to 1650 ° C.
[0017]
The atmosphere is a pure oxygen gas atmosphere in the sintering furnace from the time when the temperature rises to 800 ° C. to the end of the holding time at the sintering temperature, and oxygen when oxygen is further introduced. It is preferable that the ratio of the flow rate (L / min) and the charged weight of the compact (kg) (charged weight / oxygen flow rate) is 1.0 or less because the target becomes denser.
[0018]
Also, the sintering time is preferably 5 hours or more, preferably 5 to 30 hours in order to obtain a sufficient hardness increasing effect. By doing so, a dense ITO sintered body can be obtained. The Vickers hardness of the ITO sintered body thus obtained is 700 or more and 800 or less.
[0019]
Next, the obtained ITO sintered body is processed into a predetermined shape to produce individual target members constituting a multi-segment ITO target. The size and shape of each member are not particularly limited.
[0020]
Next, surface grinding is performed to adjust the thickness of each member. At this time, the surface roughness (Ra) of the sputtering surface is preferably adjusted to 0.6 μm or less. The three-point bending strength of the sintered body depends on the surface roughness after grinding. In the case of an ITO sintered body having a Vickers hardness of 700 or more, the surface roughness after processing is 0.6 μm or less, so that the grinding direction It is possible to stably obtain a high value of the three-point bending strength measured by applying a load in parallel with the.
[0021]
After this, with respect to the sintered body ground in the direction parallel to the long axis of the sintered body, the edge portion composed of the sputtering surface and the side surface of the sintered body is parallel to the grinding direction. It is preferable to chamfer the edge portion, and it is better to chamfer R1 or less or C1 or less. By doing so, it is possible to remove the processing scratches remaining at the edge portion, so that it is possible to effectively prevent a decrease in bending strength due to stress concentration on the processing scratches at the edge portion.
[0022]
Furthermore, when chamfering, preferably 0.2 or more and 1.0 or less, more preferably more than 0.2 and 1.0 or less, and when chamfering, preferably 0.2 or more and 1.0 or less. Preferably it exceeds 0.2 and is 1.0 or less. Moreover, you may perform the same chamfering with respect to the edge part orthogonal to a grinding direction among the edge parts comprised from a sputtering surface and a side surface. The grinding in the direction substantially parallel to the long axis of the sintered body in the present invention includes up to ± 10 degrees with respect to the parallel direction. Since the bending strength of the sintered body produced in this way is reliably improved, it is possible to reliably reduce target cracks that occur during bonding and film formation.
[0023]
Next, the obtained sintered body can be easily targeted by placing it at a predetermined position on a backing plate made of oxygen-free copper or the like and bonding it using indium solder or the like.
[0024]
In this specification, the definition and measurement method of Vickers hardness is JIS-R1610-1991, the definition and measurement method of three-point bending strength is JIS-R1601-1991, and the definition and measurement method of surface roughness is JIS. B0601-1994.
[0025]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these.
[0026]
Example 1
90 parts by weight of indium oxide powder having an average particle diameter of 1.3 μm and 10 parts by weight of tin oxide powder having an average particle diameter of 0.7 μm are mixed with a dispersant, a binder and ion-exchanged water in a pot containing a nylon ball containing an iron core for 5 hours. To prepare a slurry. After sufficiently defoaming the obtained slurry, pressure casting using a resin mold was performed to obtain a molded body. This compact was subjected to densification treatment with CIP at a pressure of 3 ton / cm ² . Next, this compact was placed in a pure oxygen atmosphere sintering furnace and sintered under the following conditions.
[0027]
(Sintering conditions)
Firing temperature: 1500 ° C., heating rate: 30 ° C./Hr, sintering time: 15 hours, atmosphere: pure oxygen gas from 800 ° C. during heating to 400 ° C. during cooling (feed weight / oxygen flow rate) The Vickers hardness of the sintered body obtained by introduction at 0.8 was measured to be 720. The obtained sintered body was processed into a bending strength test piece having a width of 4.0 ± 0.1 mm × a thickness of 3.0 ± 0.1 mm × a length of 40 ± 1 mm. Next, the back surface of the test piece was processed using a grinding wheel having a grindstone size of # 400. Next, the surface (test surface) of the test piece is processed using a grinding wheel having a grindstone particle size of 140 to 1500 so that the surface roughness (Ra) is 0.05 to 1.5, and the grinding direction and The parallel edge portion was processed with an R chamfer of 0.3 mm. Using these test pieces, the three-point bending strength was measured. The results are shown in FIG. In FIG. 4, the black circles (●) in the figure indicate the average value of the measurement, and the upper limit value and the lower limit value indicate the maximum value and the minimum value, respectively.
[0028]
From the figure, it is clear that a high value of three-point bending strength is stably obtained by performing an R chamfering process on the edge portion parallel to the grinding direction.
[0029]
Example 2
The three-point bending strength was measured by the same method as in Example 1 except that the edge portion parallel to the grinding direction was processed with a C chamfer of 0.3 mm. The results are shown in FIG. In FIG. 5, the black circles (●) in the figure indicate the average value of the measurement, and the upper limit value and the lower limit value indicate the maximum value and the minimum value, respectively.
[0030]
From the figure, it is apparent that a high value of three-point bending strength is stably obtained by performing C chamfering on the edge portion parallel to the grinding direction.
[0031]
Comparative Example 1
Three-point bending strength was measured by the same method as in Example 1 except that chamfering was not performed. The results are shown in FIG. In FIG. 6, black circles (●) in the figure indicate the average value of measurement, and the upper limit value and lower limit value indicate the maximum value and the minimum value, respectively.
[0032]
When chamfering was not carried out, there was a test piece that would be destroyed with extremely low stress due to the effect of processing scratches at the edge, and a high value could not be obtained stably.
[0033]
Example 3
Ten ITO targets shown in FIG. 3 were produced in the same manner as in Example 1 except for the size of the sintered body. When the obtained 10 targets were placed in a sputtering apparatus and sputtered, it was found that there were no cracks in the sintered body and that the sintered body could be reliably eliminated.
[0034]
Comparative Example 2
Except for the size of the sintered body, ten ITO targets shown in FIG. Of these, cracks occurred in two targets during the cooling process after bonding. Further, when the remaining 8 sheets were placed in a sputtering apparatus and sputtering was performed, cracks occurred in 2 of them.
[0035]
【The invention's effect】
In a sputtering target including a rectangular sintered body whose surface is ground substantially parallel to the major axis on the sputtering surface, the grinding direction of the edge portion composed of the sputtering surface and the side surface of the sintered body Chamfering R1 or less chamfering or C1 or less chamfering on the edge parallel to the surface, cracks in the sintered body that occur when the target manufacturing process or target is attached to a film forming apparatus and subjected to sputtering Can be reduced more reliably.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram when only one sintered body is bonded on one backing plate.
FIG. 2 is a conceptual diagram in the case where a plurality of sintered bodies are bonded onto one backing plate, and all the bonded sintered bodies are subjected to surface grinding on the sputtering surface in a direction parallel to the long axis. It is.
FIG. 3 is a conceptual diagram in the case where a plurality of sintered bodies are joined on one backing plate and surface grinding is performed in a direction parallel to the long axis on the sputtering surface of at least one sintered body. It is.
FIG. 4 is a result of measuring a three-point bending strength using the R-chamfered test piece obtained in Example 1; In FIG. 4, the X axis (horizontal axis) represents the surface roughness Ra (unit: μm), and the Y axis (vertical axis) represents the three-point bending strength (unit: MPa).
FIG. 5 is a result of measuring a three-point bending strength using a C-chamfered test piece obtained in Example 2; In FIG. 5, the X axis (horizontal axis) indicates the surface roughness Ra (unit: μm), and the Y axis (vertical axis) indicates the three-point bending strength (unit: MPa).
6 is a result of measuring a three-point bending strength by using a test piece not chamfered obtained in Comparative Example 1. FIG. In FIG. 6, the X axis (horizontal axis) represents the surface roughness Ra (unit: μm), and the Y axis (vertical axis) represents the three-point bending strength (unit: MPa).
[Explanation of symbols]
1: Sintered body 2: Backing plate 3: Sintered body grinding direction

Claims (6)

In a sputtering target including a rectangular sintered body in which surface grinding is performed on the sputtering surface in a direction substantially parallel to the long axis, grinding is performed on an edge portion composed of the sputtering surface and the side surface of the sintered body. A sputtering target characterized in that it is chamfered with respect to an edge portion parallel to the direction. 2. The sputtering target according to claim 1, wherein a chamfer of R1 or less is applied to an edge portion parallel to the grinding direction among edge portions constituted by the sputtering surface and side surfaces of the sintered body. 2. The sputtering target according to claim 1, wherein a chamfering of C1 or less is applied to an edge portion parallel to the grinding direction among edge portions composed of a sputtering surface and side surfaces of the sintered body. The sputtering target according to claim 1, wherein the surface roughness of the sputtering surface of the sintered body is 0.6 μm or less. The sputtering target according to any one of claims 1 to 4, wherein the sintered body is substantially composed of indium, tin, and oxygen. The sputtering target according to claim 5, wherein the sintered body has a Vickers hardness of 700 to 800.

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