KR101355902B1 - Sputtering target for solar cell - Google Patents

Abstract

The present invention provides a target material and a backing plate obtained by performing a process of applying a physical stress to an indium ingot and making the thickness of the ingot less than or equal to 70% of the original thickness. It is formed by bonding with a bonding material made of gallium alloy, It is a sputtering target for solar cells characterized by the above-mentioned.
The sputtering target for solar cells of this invention has a high sputter rate of the sputter | spatter initial stage, and the time-dependent fall of a sputter rate is small, and can form a more homogeneous indium film. That is, it can be expected to form a homogeneous film with a high rate up to the life end.

Description

Sputtering target for solar cell {SPUTTERING TARGET FOR SOLAR CELL}

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a sputtering target for solar cells, and more particularly, to a sputtering target for solar cells that has a constant sputter rate to the end of life and enables uniform film formation.

The indium thin film used as a light absorption layer of a thin film solar cell is generally formed by sputtering the indium sputtering target (henceforth an indium target). Indium is a soft material, and since the melting point is a low melting point metal at 156.4 ° C., the indium target is often produced by casting and rolling.

Patent Document 1 discloses a method for producing a target in which a thin film such as indium is formed on a backing plate, and then a molten metal such as indium is introduced on the thin film to form the backing plate and the target material integrally. Is disclosed. This method is a method called direct casting with respect to the indirect casting method of bonding the target material to the backing plate after the target material is produced by casting or the like, and the target material and the backing plate can be joined without gaps. Therefore, thermal irregularity does not occur at the time of sputtering, and it is said that a uniform film | membrane is formed.

Patent Literature 2 divides an indium raw material into a mold in multiple times, removes the indium oxide from the surface of the molten metal produced each time, and then obtains the surface by grinding the ingot obtained by cooling. A method for producing an indium target for a battery is disclosed. This manufacturing method is also the method using the direct casting method, and since the target obtained by this method has little amount of indium oxide in a molten metal, it is reported that the fall of the light transmittance of a light absorption layer is prevented.

However, the conventional indium target manufactured by these manufacturing methods did not have high sputter rate sufficiently, and efficient film-forming was difficult. In a sputtering target, it is preferable that initial stage sputter rate is high and it is high sputter rate to a life end. Moreover, when sputtering is performed with the conventional indium target, there existed a problem that the homogeneity of the film | membrane obtained will fall especially especially when the sputter advances to some extent.

Japanese Patent Application Laid-Open No. 63-44820 Japanese Patent Application Laid-Open No. 2010-24474

SUMMARY OF THE INVENTION The present invention has been made under the above circumstances, and an object of the present invention is to provide a sputtering target for a solar cell which has a high sputter rate at the initial stage of sputtering and a small decrease in the sputter rate over time, and can form a more homogeneous film. It is done.

The present invention which achieves the above object is a target material, a backing plate, made of a processed material obtained by performing a process of applying a physical stress to an indium ingot and making the thickness of the ingot less than or equal to 70% of the original thickness; And a bonding material made of indium-tin or indium-gallium alloy which bonds the target material and the backing plate to the sputtering target for solar cells.

In the sputtering target for solar cells of this invention, it is preferable that the said target material is a target material manufactured from the processing material obtained by performing the process which adds a physical stress to the ingot made from indium, and makes the thickness of the said ingot 50% or less of the original thickness. .

In the solar cell sputtering target of this invention, it is preferable that melting | fusing point of the said indium-tin and indium- gallium alloy is 140 degrees C or less.

In the solar cell sputtering target of this invention, it is preferable that the said indium tin and an indium gallium alloy have melting | fusing point of 130 degrees C or less.

In the solar cell sputtering target of this invention, it is preferable that the process which adds the said physical stress is rolling.

In the solar cell sputtering target of this invention, it is preferable that the process which adds the said physical stress is forging.

In the sputtering target for solar cells of this invention, the two points which interpose the grain boundary of the indium crystal grain set to 100 micrometer pitch in the deepest part of the erosion formed when the use ratio is 10% or more are used. It is preferable that the average of the difference of the said depth between the two points at the time of measuring the depth of the erosion in a measurement location is 100 micrometers or less.

In the solar cell sputtering target of the present invention, the erosion at two measurement points sandwiching the grain boundaries of the grains of indium set at a pitch of 100 µm at the deepest portion of the erosion formed when the use ratio is 10% or more. It is preferable that the average of the difference of the said depths between the two points at the time of measuring the depth of is 60 micrometers or less.

The sputtering target for solar cells of this invention has a high sputter rate of the sputter | spatter initial stage, and the time-dependent fall of a sputter rate is small, and can form a more homogeneous indium film. That is, it can be expected to form a high-rate and homogeneous film up to the life end.

1 shows an example of a top view of a target material when the use ratio is 10% or more.
2 is a micrograph of the surface of an indium film obtained when sputtering using the indium target of Example 3. FIG.
3 is a micrograph of the surface of the indium film obtained when sputtering using the indium target of Example 6. FIG.
4 is a micrograph of the surface of an indium film obtained when sputtering using the indium target of Comparative Example 1. FIG.

The sputtering target for solar cells of this invention is a target material manufactured from the processing material obtained by performing a process which adds a physical stress to an indium ingot, and makes the thickness of the said ingot 70% or less of the original thickness, a backing plate, and the said target material And a bonding material made of indium tin or an indium gallium alloy for bonding the backing plate to the backing plate.

The target material in the solar cell sputtering target of this invention is a target material manufactured from the processing material obtained by performing the process which adds a physical stress to an indium ingot, and makes the thickness of this ingot 70% or less of original thickness.

When the target material is manufactured from the ingot without applying physical stress to the ingot, a high sputter rate cannot be obtained. On the other hand, when a physical stress is applied to the ingot to form a workpiece and a target material is manufactured from the workpiece, a high sputter rate can be obtained. Although this reason is not clear, the following reasons can be considered, for example.

In the indium made of indium, an oxide layer is formed on the surface of the crystal grains which form the ingot, and it is thought that an impurity is unevenly distributed. When this ingot is used as it is for a target material, these ubiquitous impurities, etc. are caused, and the contact resistance of the crystal grains of indium which comprises a target material becomes large. As a result, at the time of output constant, the voltage rise and the current value at the time of sputtering generate | occur | produce, and sputter rate is considered to become small. In addition, such localized impurities are considered to be a cause of an arc and a current loss.

On the other hand, when processing which applies a physical stress to the ingot made from indium, it is thought that the oxide layer and the impurity which were unevenly localized on the crystal grain surface of the ingot are parted or dispersed. As a result, the contact resistance of the crystal grains of indium which comprises a target material becomes small, the voltage drop at the time of sputter | spatter and the increase of an electric current value are acquired, and it is thought that a sputter rate becomes large. In addition, generation of an arc or a current loss can be suppressed by the division or dispersion of such impurities and the like.

The processing for applying physical stress is not particularly limited as long as it is a plastic working that deforms the material by applying a large force to the material, and examples thereof include rolling, forging, extrusion molding, and pressing. Among these, rolling and forging are preferable in the point that a processing operation is easy, the point which can divide or disperse an oxide layer and an impurity reliably.

There is no restriction | limiting in particular as long as the said method of rolling meets the said conditions, It does not interfere in the same way as the rolling method currently performed with respect to the ingot made from indium etc. conventionally. There is no restriction | limiting in particular as long as the said forging method satisfies the said conditions, and it does not interfere in the same way as the forging method currently performed with respect to the ingot made from indium etc. conventionally. When the process to which a physical stress is applied is rolling, the rolling board etc. which were obtained by rolling become the said process material. When the processing to which physical stress is applied is forging, the forging plate obtained by forging becomes the said processing material.

The degree of processing to which the physical stress is applied is such that the thickness of the ingot is 70% or less of the original thickness, preferably 60% or less, more preferably 50% or less, further preferably It is about 40% or less. When the thickness of the ingot is set to 70% or less of the original thickness by the process of applying physical stress, the oxide layer or the impurities can be sufficiently divided or dispersed, thereby ensuring a uniform sputter rate and forming a homogeneous film. When the thickness of the ingot is set to 70% or less of the original thickness, for example, when the thickness of the ingot to be provided for the processing to which the physical stress is applied is 15 mm, the thickness of the ingot after processing is set to 10.5 mm or less.

The manufacturing method of the indium ingot does not interfere with the casting method conventionally performed. For example, indium materials, such as an ingot form, a ball form, or a granule, are heated and melt | dissolved at 170-200 degreeC, the obtained molten metal flows in a metal mold | die, it can be cooled, and an ingot can be obtained.

99.99% or more is preferable and, as for the purity of an indium material, 99.995% or more is more preferable. When the purity of the indium material is 99.99% or more, dispersion of impurities tends to be sufficient by subjecting the ingot to the above-described physical stress. In addition, the effect of impurities on solar cell efficiency is small.

There is no restriction | limiting in particular in the shape and size of an ingot, It is suitably determined according to the shape and size of the target material made into the objective. For example, the shape of the ingot is plate-like or cylindrical, and its thickness is usually 3 to 40 mm.

There is no restriction | limiting in particular in the method of manufacturing a target material from the processing material obtained by performing the process which adds a physical stress to an ingot, A cutting process, grinding | polishing, etc. can be carried out suitably, unless the effect of this invention is impaired. You may use a processed material as a target material as it is, without adding a process to the said processed material.

The bonding material in the sputtering target for solar cells of this invention is made of indium tin alloy or indium gallium alloy. By using a bonding material made of an indium-tin alloy or an indium-gallium alloy, it is possible to maintain a high sputter rate obtained by the above-mentioned physical stressing process for a long time after the start of sputtering.

Since these bonding materials are lower in melting point than indium which is a material of the target material, they can be melted and bonded at a temperature lower than the melting point of indium at the time of bonding. By bonding at a temperature lower than the melting point of indium which is a material of the target material, it is possible to prevent the oxide layer or impurity that is divided or dispersed from re-aggregating by the above-mentioned physical stressing process. For this reason, if the bonding material made from indium tin alloy or indium gallium alloy is used, it is thought that the high sputter rate obtained by the process which adds the said physical stress can be maintained.

On the other hand, when melting | fusing point of a bonding material is equal to melting | fusing point of indium, it is necessary to melt | dissolve and bond at the temperature equal to or more than melting | fusing point of indium at the time of bonding. When bonding is carried out at a temperature equal to or higher than the melting point of indium which is a material of the target material, some crystal grains of the target material grow or melt at the time of bonding. Then, the oxide layer or the impurity which was divided or dispersed by the process which applies the said physical stress aggregates again and is unevenly distributed. As a result, it becomes difficult to maintain a high sputter rate for a long time after the start of sputtering.

It is preferable that melting | fusing point of the said indium-tin and indium-gallium alloy is 140 degrees C or less, More preferably, it is 130 degrees C or less, More preferably, it is 125 degrees C or less. If the melting point of the indium-tin and the indium-gallium alloy is 140 ° C. or lower, it is sufficiently lower than the melting point of indium (156.4 ° C.), so that bonding at a temperature lower than the melting point of indium is easy, and is segmented by the processing applying the physical stress. Alternatively, reaggregation of the dispersed oxide layer or impurities can be reliably prevented.

The lower limit of the melting point of the indium tin and the indium gallium alloy is not particularly limited, but considering the handling and sputtering conditions, the melting point is preferably 65 ° C or higher.

As the relationship between the composition and the melting point in the indium-tin alloy, for example, when the melting point is 140 ° C. or lower, the indium content ratio is about 44 to 83 mass%, and when the melting point is 130 ° C. or less, the indium content ratio is 47 to 73 mass% It is enough.

As the relationship between the composition and the melting point in the indium-gallium alloy, for example, when the melting point is 140 ° C. or less, the indium content ratio is about 97 mass% or less, and when the melting point is 130 ° C. or less, the indium content ratio is about 95 mass% or less. When melting | fusing point is 65 degreeC or more, the indium content rate is about 60 mass% or more.

The amount of the bonding material used for joining the target material and the backing plate is not particularly limited as long as sufficient bonding of the target material and the backing plate is possible, and can be appropriately determined according to the size of the target material and the backing plate, the material of the backing plate, and the like.

The backing plate in the sputtering target for solar cells of this invention does not have a restriction | limiting in particular as long as it can join the said target material with the said bonding material, and has a backing plate predetermined | prescribed function, For example, a backing plate made of copper etc. Can be used.

The sputtering target for solar cells of this invention can be manufactured by joining the said target material and a backing plate by a well-known method with the said bonding material. For example, the target material and the backing plate are heated and dissolved at a temperature lower than the melting point of indium, for example, 120 to 150 ° C, at a temperature at which the bonding material dissolves, and the bonding material dissolved on the bonding surface of the backing plate is applied. After bonding each bonding surface together and crimping | bonding them together, it cools. Or a bonding agent is apply | coated to each bonding surface of a target material and a backing plate, each bonding surface is bonded together, and the temperature which is lower than melting | fusing point of an indium at the temperature which a bonding material melt | dissolves a sputtering target and a backing plate, for example It cools after heating to 120-150 degreeC.

Alternatively, the target material is heated to a temperature slightly lower than the melting point of indium, for example, 120 to 150 ° C, and the backing plate is heated to a temperature higher than the melting point of indium, for example, 170 to 200 ° C. The bonding material melt | dissolved on the bonding surface of a backing plate is apply | coated, the bonding surface of a target material and a backing plate is bonded together, and after crimping | bonding both, it cools.

Moreover, after sputtering target for solar cells of this invention joins the precursor of a target material and a backing plate with the said bonding material, you may manufacture it with the precursor as a target material by processing into the precursor part. The precursor of the target material is a material obtained by performing processing such as cutting, polishing, or the like on the processed material obtained by applying a physical stress to the ingot, or the processed material.

On the other hand, the sputtering target for solar cells of this invention is the sputtering target manufactured by the indirect casting method.

The sputtering target for solar cells of this invention can be sputtered on the conditions similar to the conventional indium target.

In the solar cell sputtering target of the present invention, the erosion at two measurement points sandwiching the grain boundaries of the grains of indium set at a pitch of 100 µm at the deepest portion of the erosion formed when the use ratio is 10% or more. It is preferable that the average (henceforth an average step | step) of the difference of the depth of is 100 micrometers or less, It is more preferable that it is 60 micrometers or less, It is more preferable that it is 50 micrometers or less. This case will be described below.

The use ratio is the ratio with respect to the mass of the target material before sputtering of the mass (the difference of the mass of the target material before sputtering and the mass of the target material after sputtering) reduced by the sputter | spatter.

In FIG. 1, an example of the top view of the target material when a use ratio is 10% or more is shown. In the disk-shaped target material 1 of diameter 4 inches, the erosion 2 which is a part dug by sputter | spatter is formed in the sputter | spatter part of the surface 4 in ring shape. The erosion 2 is deeply formed toward the center of the region placed between the outer and inner lines of the ring. The deepest part 5 is formed in circular shape in the substantially center part of the said area | region of the ring.

The deepest part is a part including the deepest part formed in the erosion part, for example, a part having a depth of 90 to 100% with respect to the maximum depth of the erosion part. The depth of erosion is the length of a direction perpendicular to the surface 4 from the surface 4 of the target material 1 to the erosion part surface.

The surface of the erosion part including the deepest part was observed with an electron microscope, and at the deepest part, for example, three or more measurement sites 3 were set at substantially equal intervals as shown in FIG. In the site | part 3, three or more line segments of length 10mm are assumed. On each line segment, two measurement points which interpose the grain boundaries of the crystal grains of indium are set with a pitch of 100 micrometers. The depth of the erosion is measured at each measuring point, and for each line segment, the difference in the depth of the erosion (grain boundary) between two measuring points on the line segment is obtained. The average of the grain boundary difference of all the line segments is computed, and the average is made into an average step | step.

The depth of the erosion can be obtained by, for example, a surface roughness measuring device. The specific measuring method is explained in full detail in the following Examples.

From the relationship with the size of the crystal grains constituting the target material, if two measurement points are placed between the grain boundaries of the indium crystal grains at a pitch of 100 μm, the measurement points of the two points are separated from each other. It is set one by one on the grains of indium. The depth of the erosion increases as the sputter rate increases. Therefore, the difference of the depth of erosion in the measurement point of two points of each said set means the difference of the sputter rate in two mutually adjacent indium crystal grains.

That is, the larger the average step means that the sputter rate of one grain is different from the sputter rate of the other grain in mutually adjacent grains, and that the smaller the average step is smaller in the grains adjacent to each other. This means that the sputter rate of the grains and the sputter rate of the other grains do not differ significantly.

If the average step is 100 µm or less, the sputter rate does not differ greatly between the adjacent grains, and thus, a uniform sputter rate can be obtained over the entire sputter portion of the target material. As a result, a homogeneous film is formed by the sputter. Can be formed. On the other hand, when the said average step | step is larger than 100 micrometers, since sputter rate differs greatly between mutually adjacent crystal grains, a uniform sputter rate cannot be obtained over the whole sputter | spatter part of a target material, As a result, a homogeneous film | membrane by sputter | spatter can be obtained. It becomes difficult to form.

In the solar cell sputtering target of the present invention, an oxide layer or impurities localized on the surface of crystal grains forming the ingot are divided or dispersed by performing a process of applying a physical stress to an indium made of indium. Since it is further bonded by the bonding material or the like, the divided or dispersed state is maintained. For this reason, a sputter rate does not differ significantly between adjoining crystal grains, and the said average step | step is easy to become 100 micrometers or less. As a result, when the sputtering target for solar cells of this invention is used, a homogeneous film | membrane can be formed by sputtering.

On the other hand, in the case where the processing of applying physical stress to the indium ingot is not performed, or even if the processing is not carried out by bonding material made of indium-tin alloy or the like, the oxide layer or impurities are formed on the surface of the crystal grain. This is not divided or dispersed, and is in a state of being distributed unevenly. For this reason, the sputter rate differs greatly between adjacent crystal grains, and the said average step | step is hard to become 100 micrometers or less. As a result, when the conventional sputtering target for solar cells is used, it is difficult to form a homogeneous film | membrane by sputtering.

The average step is likely to appear at the stage and site where the sputter has advanced. For example, when the use ratio is 10% or more, it is also prominent at the deepest part of the erosion.

[Example]

The measuring method used by the Example and the comparative example is described.

(Bulk resistance, current and voltage)

The bulk resistance was measured by placing the probe on the target material surface of the indium target in AUTO RANGE mode using Mitsubishi Chemical's Lorester HP MCP-T410 (series 4 probe probe TYPE ESP). The voltage and current values were read from the power meter of the sputtering device during the sputtering.

(usage proportion)

Sputtering was performed using the produced indium target, and the mass of the indium target after sputtering was measured. The mass of the indium target before sputter | spatter implementation was made into M <_1> , the mass of the target material before sputter | spatter implementation as M <_2> and the mass of the target material before sputtering was made into M <_3> , and the use ratio was calculated | required by the following formula. In the following formula, (M ₁ -M ₂ ) means the mass of the target material reduced by the sputter.

(Sputter rate)

Sputtering was performed on condition of the following using the produced indium target.

Device Name: High-rate Sputter Device (Shinkugi Kaigokyo EX-3013M)

Reach vacuum level 3.0 × 10 ^{-4 to} 8.3 × 10 ^-5 Pa

O2 flow rate 0sccm

Ar flow rate 49sccm

Sputter Pressure 6.5 × 10 ^-1 Pa

Output 154W

Substrate temperature room temperature

Use glass 40mm in width, 40mm in width, 0.8mm in thickness, Corning # 1737

The thickness and use ratio of the film | membrane formed by sputtering every fixed time were measured. Sputter time on the horizontal axis and film thickness were taken on the vertical axis, and the curve was created. The slope of the tangential line of the curve at the start of sputtering was taken as the initial rate. The sputter rate was calculated | required from the inclination of the tangential of the curve in the time when the use ratio became 15%, and the numerical value was made into the rate at 15% or more of the use ratio.

When the initial rate was R ₀ and the use rate was 15% or more, the rate was R ₁₅ , and the sputter rate drop rate was obtained by the following equation.

(Average step)

Using the indium target which performed the sputter | spatter shown by the said measuring method of the said sputter rate, at three innermost parts of the ring-shaped erosion formed at 10% or more of usage ratio, it set the three measurement site | parts at substantially equal intervals, and measures each Three line segments having a length of 10 mm were assumed at the site, and two measurement points were set on the respective line segments at a pitch of 100 µm. The depth of the erosion at each measuring point, ie, the length in the direction perpendicular to the surface from the surface of the target material to each measurement point was measured under the following conditions. The difference (grain difference) of the depth of erosion at two measuring points on the said line segment for every said 9 line segments was calculated | required, and their average was made into the average level | step difference. The deepest part of the erosion was a portion having a depth of 90 to 100% with respect to the maximum depth of the erosion.

Equipment Name: Surface Roughness Measurement System (Nihonshinkugijutsu Co., Ltd., DEKTAK 6M)

Scan length 100㎛

Scan type Standard Scan

Stylus type Radius 12.5㎛

Stylus force 15mg

Meas Range 2620KÅ

(Surface roughness Ra of the film)

The surface roughness Ra (micrometer) of the indium film obtained by performing the sputtering shown by the said sputter rate measurement method at the film thickness of 5000 kPa was measured on condition of the following using the COLOR3D Laser Scanning Microscope VK-8710 made from KEYENCE.

[Measuring conditions]

Filter: 1% light

Z measuring pitch: 0.01㎛

Measurement Mode: Surface Geometry

Measuring Area: Face

Measurement quality: high precision

Example 1

In (purity 99.99% or more) was melt | dissolved at 180 degreeC, the obtained molten metal was inject | poured into the metal mold | die, and 100 mm of length, 100 mm of width, and 15 mm of thickness ingot were cast. About the obtained ingot, it rolled on the conditions of 1 mm / pass of rolling amount at normal temperature using the rolling mill made from Nippon Cross-Atsuen, and obtained the rolled plate of thickness 9mm. The obtained rolled sheet was cut out to disk shape of diameter 102mm, and both surfaces were cut using each 1 mm price, and it was set as the smooth surface. This rolled disk (target material) and a disk-shaped backing plate made of oxygen-free copper having a diameter of 110 mm were heated so as to be 130 ° C on a hot plate with their respective bonding surfaces facing up. The alloy (melting point 125 degreeC) consisting of 50 mass% of In (purity 99.99% or more) and 50 mass% of Sn (purity 99.99% or more) is used as a bonding material, and 130 degreeC molten metal of this alloy is used as the bonding surface of the said backing plate. The thin film was attached using a ultrasonic soldering iron. The said rolled disk which was heated on this was mounted, it cooled, putting the weight on the rolled disk, so that it might not move, and bonding was performed. Subsequently, an indium target was produced by processing the rolled disc part to a size of 101 mm in diameter and 6 mm in thickness on a shelf. Various evaluation was performed about this indium target by the said measuring method. The results are shown in Table 1.

In Example 1, sputter | spatter was performed on the said indium target on the said conditions, and when the use ratio is 16%, the rate and average step | step at 15% or more of use ratio were calculated | required. Also in the following Examples and Comparative Examples, when the use ratio shown in Table 1 or Table 2 was 15% or more, the rate and average step were determined.

[Example 2]

An alloy (melting point 115 ° C.) composed of 90% by mass of In (purity of 99.99% or more) and 10% by mass of Ga (purity of 99.99% or more) as a bonding material having a heating temperature of 120 ° C. and a bonding material. It used and carried out like Example 1 except having set the molten metal temperature of this alloy to 120 degreeC, and produced the indium target. Various evaluation was performed about this indium target by the said measuring method. The results are shown in Table 1.

[Example 3]

The indium target was produced like Example 1 except having set the thickness of the flat ingot to 18 mm. Various evaluation was performed about this indium target by the said measuring method. The results are shown in Table 1.

In addition, when the said sputter rate measurement was performed using this indium target, the surface of the indium film obtained by the sputter | spatter when the film thickness is 5000 kPa was observed using COLOR3D Laser Scanning Microscope VK-8710 made from KEYENCE. The obtained image is shown in FIG.

Example 4

The thickness of the flat ingot of 18 mm, the heating temperature of the rolled disc and the backing plate of 120 ° C, and the bonding material include 90 mass% of In (purity of 99.99% or more) and Ga (purity of 99.99% or more). An indium target was produced in the same manner as in Example 1 except that an alloy composed of 10% by mass (melting point 115 ° C) was used and the molten metal temperature of this alloy was 120 ° C. Various evaluation was performed about this indium target by the said measuring method. The results are shown in Table 1.

[Example 5]

The thickness of the flat ingot of 18 mm, the heating temperature of the rolled disc and the backing plate of 100 ° C, and the bonding material include 80 mass% of In (purity of 99.99% or more) and Ga (purity of 99.99% or more). An indium target was produced in the same manner as in Example 1, except that an alloy made of 20% by mass (melting point 90 ° C) was used and the molten metal temperature of this alloy was 100 ° C. Various evaluation was performed about this indium target by the said measuring method. The results are shown in Table 1.

[Example 6]

An indium target was produced in the same manner as in Example 1 except that the thickness of the flat ingot was 22.5 mm. Various evaluation was performed about this indium target by the said measuring method. The results are shown in Table 1.

Moreover, when the said sputter rate measurement was performed using this indium target, the surface when the film thickness is 5000 kPa of the indium film obtained by this sputter | spatter was observed on the conditions similar to Example 3. The obtained image is shown in FIG.

[Example 7]

Except having made the thickness of the flat ingot into 18 mm, and instead of rolling this ingot, forging the whole ingot by using a hammer by hand forging and making the thickness of the ingot 9 mm. It carried out like 1 and produced the indium target. Various evaluation was performed about this indium target by the said measuring method. The results are shown in Table 1.

Comparative Example 1

A stainless steel cylindrical mold having an inner diameter of 102 mm was mounted on a disk-shaped oxygen-free copper backing plate having a diameter of 110 mm, and its center line was fitted in accordance with the center line of the backing plate, and the clamp was fixed so that the mold did not move. This was heated to a temperature of 180 ° C. (above the melting point of In) on a hot plate. On (back purity 99.99%) was poured into this backing plate so that the thickness after melt | dissolution may be set to 7 mm, and after melt | dissolving, the oxide of a surface was removed and it cooled, In solidified In. This solidified body was processed into the disk shape of diameter 101mm and thickness 6mm using the shelf, and the indium target was produced. Various evaluation was performed about this indium target by the said measuring method. The results are shown in Table 2.

Moreover, when the said sputter rate measurement was performed using this indium target, the surface when the film thickness is 5000 kPa of the indium film obtained by this sputter | spatter was observed on the conditions similar to Example 3. The obtained image is shown in FIG.

[Comparative Example 2]

The thickness of the flat ingot was 9 mm, and the ingot was cut into a disk shape having a diameter of 102 mm without rolling on the ingot, and both sides were cut using each 1 mm price to obtain a smooth surface. Except having performed similarly to Example 1, the indium target was produced. Various evaluation was performed about this indium target by the said measuring method. The results are shown in Table 2.

[Comparative Example 3]

The indium target was produced like Example 1 except having set the thickness of the flat ingot to 11 mm. Various evaluation was performed about this indium target by the said measuring method. The results are shown in Table 2.

[Comparative Example 4]

In (purity 99.99% or more) was melt | dissolved at 180 degreeC, the obtained molten metal was inject | poured into the metal mold | die, and 100 mm of length, 100 mm of width, and 15 mm of thickness ingot were cast. About the obtained ingot, it rolled on the conditions of 1 mm / pass of reduction amount at normal temperature using the rolling mill made from Nippon Cross-Atsuen, and made the thickness of the ingot 9 mm. The obtained rolled sheet was cut out to disk shape of diameter 102mm, and both surfaces were cut using each 1 mm price, and it was set as the smooth surface. This rolled disk and the disk-shaped oxygen-free copper backing plate of diameter 110mm were mounted on the hotplate with each bonding surface facing up, and it heated so that a rolling disk might be 140 degreeC and a backing plate might be 180 degreeC. An In (purity of 99.99% or more) metal (melting point 156.4 ° C.) was used as a bonding material, and a 180 ° C. molten metal of this In metal was attached to the bonding surface of the backing plate while being thinly stretched using a gote. The said rolled disk which was heated on this was mounted, it cooled, putting the weight on the rolled disk, so that it might not move, and bonding was performed. Subsequently, an indium target was produced by processing the rolled disc part to a size of 101 mm in diameter and 6 mm in thickness on a lathe. Various evaluation was performed about this indium target by the said measuring method. The results are shown in Table 2.

[Comparative Example 5]

Except having made the thickness of the flat ingot into 18 mm, it carried out similarly to the comparative example 4, and produced the indium target. Various evaluation was performed about this indium target by the said measuring method. The results are shown in Table 2.

[Comparative Example 6]

Except having made the thickness of the ingot into 10.5 mm, it carried out like Example 7 and produced the indium target. Various evaluation was performed about this indium target by the said measuring method. The results are shown in Table 1.

[Table 1]

[Table 2]

From the comparison of Examples 1, 3 and 6 in Table 1 and Comparative Examples 2 and 3 in Table 2, the initial rate of the sputtering target obtained by rolling the ingot thickness to 70% or less of the original thickness is obtained. It turns out that the surface roughness of the In film obtained by sputtering this sputtering target becomes small. It can be seen from the comparison between Figs. 2 and 3 and Fig. 4 that the In film obtained by sputtering the sputtering target obtained by rolling the thickness of the ingot to 70% or less of the original thickness has a small surface roughness. In addition, it is understood from the comparison between Example 7 and Comparative Example 6 in Table 1 that the same effects as in the case of rolling can be obtained by forging the thickness of the ingot to be 70% or less of the original thickness.

Further, from the comparison between Example 2 and Comparative Example 4 and the comparison between Examples 3 to 5 and Comparative Example 5, even though the thickness of the ingot was rolled to 70% or less of the original thickness, a sputtering target having a high initial rate was obtained. When the target material and the backing plate are bonded together using bonding materials other than the indium-tin and indium-gallium alloy bonding materials, it is understood that the sputter rate greatly decreases as the sputter proceeds. On the other hand, when the thickness of the ingot is rolled to 70% or less of the original thickness, and the target material and the backing plate are bonded using a bonding material made of indium tin or indium gallium alloy, the initial rate is high. Even if sputtering advances, it turns out that the fall of a sputter rate is smaller.

1: target material
2: erosion
3: measuring area
4: surface
5: deepest

Claims (8)

A target material, a backing plate, and a backing plate made of a processed material obtained by subjecting the ingot having an indium content of 99.99% by mass or more to physical stress and making the thickness of the ingot less than 60% of the original thickness; A sputtering target for solar cells, comprising a bonding material made of indium-tin or indium-gallium alloy having a melting point of 140 ° C. or less to bond the target material and the backing plate. The method of claim 1,
The said target material is a target material manufactured from the processing material obtained by performing a process which adds physical stress to the ingot whose indium content is 99.99 mass% or more, and makes the thickness of the said ingot 50% or less of original thickness, The sputtering target for solar cells characterized by the above-mentioned. 3. The method according to claim 1 or 2,
The indium-tin and indium-gallium alloys have a melting point of 130 ° C. or lower, wherein the sputtering target for solar cells is used. 3. The method according to claim 1 or 2,
The sputtering target for solar cells, wherein the processing to which the physical stress is applied is rolling. 3. The method according to claim 1 or 2,
The sputtering target for solar cells, wherein the processing to which the physical stress is applied is forged. 3. The method according to claim 1 or 2,
3 parts spaced evenly at the deepest part of the erosion formed when the ratio of the mass of the target material before sputtering and the mass of the target material after sputtering to the mass of the target material before sputtering is 10% or more. After setting a measurement site | part, assuming three line segments of length 10mm in each measurement site | part, and setting two measurement points which interpose the grain boundary of the indium crystal grain at 100 micrometer pitch on each line segment, the said A sputtering target for solar cells, wherein the average of the difference in depth of erosion measured at two measuring points on the line segment every nine line segments is 100 µm or less. 3. The method according to claim 1 or 2,
3 parts spaced evenly at the deepest part of the erosion formed when the ratio of the mass of the target material before sputtering and the mass of the target material after sputtering to the mass of the target material before sputtering is 10% or more. After setting up the measurement site, assuming three line segments of 10 mm in length at each measurement site, and setting two measurement points at which the grain boundaries of indium grains are interposed between the line segments at 100 μm pitch, each of the nine line segments The average of the difference of the depth of the erosion measured by the two measuring points on the line segment is 60 micrometers or less, The sputtering target for solar cells characterized by the above-mentioned. delete

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