CN104018128A - Nickel-platinum alloy sputtering target material and preparation method thereof - Google Patents

Abstract

The invention provides a nickel-platinum alloy sputtering target material and a preparation method thereof. In the nickel-platinum alloy sputtering target material, the platinum content is 0-5 atom%, the average crystal grain size of the target material is less than 80 mu m and the dimension of each crystal grain is not more than 150 mu m, the target material has uniformly-distributed diffraction-peak intensity combination, and the diffraction peak intensity at a single direction is not more than 50%, and the pass through flux (PTF) of the target material is larger than 40% and the measured value difference at different directions is within 5%. The nickel-platinum alloy sputtering target material is capable of reducing sputtering phenomena, and has relatively long service life. A film prepared from the target material has relatively good uniformity. The invention also aims at providing the preparation method of the above nickel-platinum alloy sputtering target material which has high pass through flux (PTF) and low platinum content.

Description

A kind of nickel platinum alloy sputtering target material and preparation method thereof

Technical field

The present invention relates to alloy casting and manufacture field, be specifically related to a kind of nickel platinum alloy sputtering target material and preparation method thereof.

Background technology

The magnetic susceptibility (PTF, Pass Through Flux) of sputtering target material refers to the magnetic field and the ratio that applies magnetic field through target.The PTF of non magnetic target is 100%, means that not applying magnetic field is shunted by target.The PTF value of magnetic target is generally between 0 to 100%, and most its PTF of industrial material is between 10% to 95% conventionally.The measuring method of PTF has a variety of, and wherein that representative is standard A STMF-1761-00 and the F-2086-01 of U.S. material and test association defined.

Magnetron sputtering is method conventional in film preparation, in this method, target is as negative electrode, it is equipped with permanent magnet or electro-magnet behind, and the magnetic field that magnet applies is through target, with sputter gas (Ar) collision in sputter cavity, surface at target forms plasmasphere, these ionizable ions constantly clash into the surface of target under the effect in magnetic field, target atom is hit to target material surface and be deposited on the matrix being positioned over before target, form film simultaneously on matrix.

But a shortcoming of magnetron sputtering is and is not suitable for ferromagnetic substance, ferromagnetic substance is owing to having stronger magnetic, and the magnetic field that magnetron sputtering equipment applies is easy to be shunted by target, is crossing to surperficial magnetic line of force thereby reduce.Therefore, materials such as Fe, Co, Ni, and be not suitable for magnetron sputtering, because can make build-up of luminance or sustain discharge difficulty relatively, also can cause such as problems such as deposition membrane thickness unevenness simultaneously.This restriction can be used target (approximately 1.5～3mm) as thin as a wafer to solve, and this thickness is also not enough to most of magnetic line of force to shunt conventionally, but so thin target cost is high and work-ing life is short.Therefore,, if will make Ferromagnetic target magnetron sputtering, the thickness of target becomes an obstacle.

Conventionally, the PTF of target reaches more than 30% just can build-up of luminance, and higher PTF allows the sputtering target material that use is thicker, can improve sputtering yield and the utilization ratio of target simultaneously.Meanwhile, increase PTF and can make aura more stable, therefore the film of deposition also has better uniformity of film.Another problem existing in using low PTF target is to accelerate sputter phenomenon.Along with the minimizing (forming sputter ditch) of target local section, magnetic line of force is increased in sputter ditch position, cause the part of PTF to increase, this can change the behavior of aura, cause that sputter gas strengthens at this region ionization probability, namely there is higher sputter rate to betide this region, finally, this sputter ditch becomes very narrow, cause target utilization to decline, this phenomenon is more obvious in the time using thinner target, and the generation of simultaneously accelerating sputter also can cause the rising of film deposition rate at regional area, thereby affects the homogeneity of film integral.In addition, the homogeneity of overall target PTF also has larger impact to the homogeneity of film.

Magnetron sputtering is widely used in electronic industry, particularly in magnetic recording and semicon industry.Nickel and nickelalloy target are the modal targets of semicon industry, such as, become the silicide of main flow with the silicide that the NiSi film of nickel or nickel platinum alloy preparation of target materials has replaced Co, the interconnection that is widely used in microelectronics industry with the field such as contact.But at nickel or nickel platinum alloy sputtering target material, in the use procedure of the nickel platinum target of especially low platinum content, also there are some problems.First, due to the ferromegnetism of nickel and nickel platinum alloy, the thickness of target is restricted conventionally, and the thickness of nickel target is less than 5mm conventionally, in a lot of situations, is less than 3mm, and the problem that this thickness brings is that the work-ing life of target is lower and cost is higher.Secondly, the PTF of nickel and nickel platinum alloy target is conventionally lower, and taking pure nickel as example, its PTF is between 5% to 20% conventionally, and so low PTF value at all cannot build-up of luminance.Low PTF is to nickel platinum alloy, especially the nickelalloy of platinum content lower (atomic percent is less than 5%) exists too, even make the PTF of target be greater than 30% by working method, and can normal build-up of luminance when sputter, its utilization ratio is conventionally all below 20%.Simultaneously, the sputter ditch phenomenon that low PTF causes is particularly evident in nickel and low platinum content nickel platinum alloy, the existence of sputter ditch causes the abnormal of nickel and the local sputter rate of nickel nickel platinum alloy target, causes prepared film equality variation, has greatly affected the good article rate of prepared product.

The method that improves the PTF of target has a variety of.Such as, the U.S. patent of invention US4299678 provide a kind of method, makes the Curie temperature of service temperature higher than target in the time of sputter.It is more difficult that but this method operates.For another example, add alloying element and improve the PTF of target, but for specific alloy target material, add merely alloying element in order to improve PTF, not only can change the composition of target, also can change the performance of target.In addition, improve PTF by the change of target configuration design or the target head to magnetron sputtering in addition, such as, Chinese invention patent 200810010809.7 has been announced a kind of method that improves target utilization by the sputter face at planar target or backside surface processing sputtering ring, but this method cost costliness, there is no actual benefit.

Chinese invention patent 20058006513.2 discloses the preparation method of a kind of Pt content in the Ni-Pt of 0.1～20 % by weight alloy and Ni-Pt alloys target.But this patent of invention only discloses the method that the hardness of Ni-Pt alloy pig is declined and can efficient stable rolling, does not have the content that relates to any PTF about NiPt target and concrete rolling technology.Chinese invention patent 200710168027.1 discloses a kind of ultra-high purity NiPt alloy and has comprised the sputtering target of this alloy, can prepare 4N5NiPt sputtering target by the processing of melting heated mechanical, but the particle size of the NiPt target of preparing by this kind of method is between 200～300 microns, so thick grain-size is unfavorable for that preparation has the film of even structure, and sputter rate is lower.Chinese invention patent 201180014500.50 has been announced a kind of nickel alloy sputtering target, in this invention by containing in the NiPt alloy of Pt5～30 atom %, the alloying element that adds at least 1～5 atom % improves the PTF of target, simultaneously because the content of Pt is wherein 5～30%, the existence of non magnetic Pt element itself can improve the PTF of Ni, but for the content of Pt the NiPt target below 5 atom % and how to improve its PTF and do not relate to.Therefore, how to prepare the nickel and the low platinum content nickel platinum alloy target that there is larger thickness and there is higher PTF value, reduce the generation of sputter phenomenon, improve the work-ing life of target, improve the homogeneity that adopts the prepared film of target, the good article rate that improves prepared product is urgent problem in nickel and the application of low platinum content nickel platinum alloy target simultaneously.

Summary of the invention

The object of the present invention is to provide a kind of nickel platinum alloy sputtering target material and manufacture method thereof, described nickel platinum alloy sputtering target, can reduce sputter phenomenon and occur, and has longer work-ing life, uses the prepared film of this target to have good homogeneity; Another object of the present invention is to provide a kind of preparation method who obtains above-mentioned nickel platinum alloy sputtering target material.

First object of the present invention is achieved in that in described nickel platinum alloy sputtering target material, the content of platinum is 0～5 atom %, and the average grain size of target is less than 80 microns and single grain-size and is not more than 150 microns.

Preferably, the average grain size of described nickel platinum alloy sputtering target material is less than 50 microns, and single grain-size is not more than 100 microns.

In X-ray diffraction analysis, the X-ray diffraction peak intensity ratio of (111) crystal face representing with formula I

$R\left(111\right)\%=100\×\frac{\frac{I\left(111\right)}{\mathrm{Ip}\left(111\right)}}{\mathrm{\Σ}\frac{I\left(\mathrm{hk}1\right)}{\mathrm{Ip}\left(\mathrm{hk}1\right)}}\%$ ... ... ... ... ... formula I

For being less than 50%.

Preferably, in X-ray diffraction analysis, the X-ray diffraction peak intensity ratio of (200) crystal face representing with formula II

$R\left(200\right)\%=100\×\frac{\frac{I\left(200\right)}{\mathrm{Ip}\left(200\right)}}{\mathrm{\Σ}\frac{I\left(\mathrm{hk}1\right)}{\mathrm{Ip}\left(\mathrm{hk}1\right)}}\%$ ... ... ... ... ... formula II

For being greater than 20%.

The magnetic susceptibility (PTF) of described target be greater than 40% and the numerical value difference measured on each different directions in 5%.

Preferably, the PTF of described nickel platinum alloy sputtering target material be greater than 50% and the numerical value difference measured on each different directions in 5%.

Preferably, the PTF of described nickel platinum alloy sputtering target material be greater than 60% and the numerical value difference measured on each different directions in 5%.

Another object of the present invention is achieved in that described nickel platinum alloy sputtering target material adopts the method for thermomechanical processing to make, and concrete preparation method comprises the following steps:

(a) ingot casting preparation: nickel or nickelalloy raw material are smelted into ingot casting.

(b) hot rolling: hot rolling nickel or Ni alloy ingot become material base, wherein need carry out the alternately rolling of transverse and longitudinal when hot rolling, and hot-rolled temperature is 950 DEG C～1250 DEG C, and hot rolling deformation amount is more than 30%.

(c) cold rolling heat treated: the material base after hot rolling is carried out to cold rolling and alternately processing of thermal treatment, and cold rolling total deflection is in 30%.

Described cold rolling be transverse rolling and axial rolling by an angle of 90 degrees alternately rolling clockwise, cold rolling number of times is twice, carries out a thermal treatment between cold rolling.

Described thermal treatment temp is 600 DEG C～800 DEG C, and the time is 1～4 hour.

Adopt thermomechanical provided by the present invention to process preparation technology, prepare Pt content at 0～5 atom %, grain fineness number is in 100 microns and be evenly distributed, and PTF is more than 40% and be evenly distributed, and has the nickel platinum alloy target of equally distributed diffraction peak intensity combination.Use described nickel platinum alloy target to carry out magnetron sputtering, can greatly improve the generation of sputter phenomenon in nickel platinum alloy sputter procedure, can prepare the target of larger thickness, the work-ing life of target and efficiency are improved greatly, and use the nickel platinum alloy film of this kind of preparation of target materials to have good homogeneity.Meanwhile, the preparation method that the present invention improves has simple to operate, the feature that working (machining) efficiency is high.

Brief description of the drawings

Fig. 1 and the metallograph that is the NiPt target that in employing the present invention prepared by embodiment 4.

Fig. 2 is the metallograph that adopts the NiPt target that in the present invention prepared by comparative example 1.

Embodiment

Below in conjunction with accompanying drawing, the present invention is further illustrated, but never in any form the present invention is limited, and any change or the improvement done based on training centre of the present invention, all belong to protection scope of the present invention.

First nickel and platinum raw material are provided, and the material purity of nickel and platinum, more than 4N, is prepared into nickel platinum alloy ingot casting by the method such as vacuum induction melting or electron beam melting.

Secondly, nickel platinum alloy ingot casting is carried out to hot rolling, the temperature of hot rolling must be controlled between 950 DEG C～1250 DEG C, temperature can ftracture lower than 950 DEG C of pine-tree structure and ingot castings that can not effectively destroy ingot casting, serious higher than 1250 DEG C of oxidations, and target base abnormal grain growth, is unfavorable for the follow-up control to tissue.The deflection of hot rolling must be greater than 30%, and the rolling direction of hot rolling must transverse rolling and axial rolling alternately rolling back and forth, and the object of doing is like this pine-tree structure that guarantees to eliminate completely ingot casting, promotes the even structure of target base after hot rolling simultaneously.

Hot rolling needs target base to carry out the treatment process of cold rolling heat treated later.Be proved to be and can have improved PTF although cold rolling, but cold rolling deflection is after 5% conventionally, PTF just starts to be tending towards saturated, deflection is substantially saturated after 10%, thereafter cold rolling can cause that target base internal stress produces too much gathering, easily produce deformation texture, affect target internal structure and affect following process.And thermal treatment is for eliminating the inner too much internal stress of target base, eliminate texture, promote recrystallize, preparation has evenly tiny grain fineness number and has larger help.The technique that therefore, must adopt cold rolling heat treated to combine.But in order to obtain having the sputtering target material of high magnetic spectroscopy susceptibility, simple cold rolling heating treatment process is not all right, must carry out strict control to this technological process.

First, heat treated temperature is had to requirement.Common heat treated temperature need be controlled near the recrystallization temperature of target, and for nickel and nickelalloy, recrystallization temperature is 600 DEG C of left and right, is all acceptable in theory in the wide temperature range between 500 DEG C～900 DEG C.But the stress of cold rolling generation is too much eliminated in the too high meeting of thermal treatment temp, thereby reduce the PTF of target.The too low annealing time that can extend of thermal treatment temp, affects efficiency.Therefore, preferred heat treated temperature is between 600 DEG C～800 DEG C.

Secondly, cold rolling total deformation and cold rolling direction are also had to requirement.Although as previously mentioned, with regard to nickel, cold rolling reduction is after 5%, PTF has started to be tending towards saturated, but contriver finds, by improving cold rolling and technique heat treatment process, in the time that cold rolling total deflection reaches 20%～30%, PTF just starts saturatedly, and PTF has a significant raising in this process.In the time that cold rolling reduction exceedes 30%, PTF is saturated, and extra cold rolling can increasing is out of shape internal stress.Therefore, cold rolling deflection is 20%～30%, suitable.Secondly, cold rolling direction is also very large on the PTF impact of material, with respect to along a direction rolling, replace the cold rolling raising effect to PTF more obvious, after cold rolling, carry out a thermal treatment, can promote the recrystallize of target, and can eliminate the part stress producing in cold-rolled process, thereby further improve the homogeneity of target crystalline grains distribution of sizes and PTF.In addition, alternately the formation of deformation texture in cold-rolled process has been avoided in rolling.Conventionally, because low platinum-nickel alloy is mainly taking face-centred cubic structure as main, if in cold roller and deformed process along a direction rolling, easily produce deformation texture.The distortion preferred orientation of common low platinum Ni alloy is taking <111> direction as main, when along a direction rolling, in X-ray diffraction, the intensity of <111> direction can account for the more than 50% of total intensity.The existence of deformation texture not only can aggravate the generation of nickel and nickelalloy sputter phenomenon in sputter procedure, and meanwhile, while using this target to prepare film especially to use circular substrate, thickness and the homogeneity of substrate center and marginal position film become very poor.And contriver finds in cold-rolled process that alternately rolling can not only greatly improve the PTF value of target, also can avoid the generation of <111> preferred orientation, thereby can greatly improve the homogeneity of the film of this preparation of target materials of use.

In the present invention, by the technique of hot rolling, cold rolling heat treated, prepare the nickel platinum alloy target with low platinum content with high magnetic susceptibility (PTF), target thickness is more than 3mm, PTF is more than 40% and be evenly distributed, grain-size is below 100 microns and be evenly distributed, and the combination of the diffraction peak intensity of target evenly, the preferred orientation that does not exist the diffracted intensity in single direction to be greater than 50%.

Below in conjunction with specific embodiment, the preparation method of nickel platinum alloy target in the present invention is specifically described.

Embodiment 1～6

Electrolytic nickel taking purity as 4N and Pt sheet are raw material, prepare NiPt alloy cast ingot by vacuum induction melting.Ingot casting is carried out to hot rolling, and hot-rolled temperature is 950 DEG C～1250 DEG C, and hot rolling deformation amount is more than 30%.After hot rolling is complete and cooling, carry out cold rolling and thermal treatment Alternating System, cold rolling total deformation is 20%～30%, rolling direction is alternately rolling, thermal treatment temp is 600 DEG C～800 DEG C, heat treatment time is 1～4 hour, carries out a thermal treatment between cold rolling twice, after completing, it is 3～5mm that target is worked into thickness, and diameter is 450mm.

Adopt ASTMF-2086-01 method to measure PTF, the PTF numerical value number of measuring is 10, with every 300 clockwise direction image data, calculate the variation range of PTF simultaneously, the calculation formula of PTF variation range is: the difference of maximum value and minimum value is multiplied by 100% divided by mean value; Target after processing is done to metallurgical analysis, and adopt ASTME112-96 to measure average grain size; Target sampling is done to X-ray diffraction (XRD) material phase analysis, calculate single diffraction direction and account for the per-cent of all diffraction peak intensities according to diffraction result; Use this target to carry out thin film sputtering, and measure the sheet resistance of film, the sheet resistance of film adopts four-electrode method to measure, and measures the numerical value of 121 points on a silicon chip and adds up the distribution range of sheet resistance, assesses the homogeneity of film with the distribution (%1s) of sheet resistance data; Complete the life-span of assessing target after thin film sputtering according to the real time of sputter (KWH).Detailed numerical value as shown in Table 1 and Table 2.

As can be seen from Table 1 and Table 2, by method of the present invention, the PTF of gained target is more than 40%, and the highest has reached 60%, and PTF% is distributed in 5%, has good uniformity coefficient.The average grain size of target is below 100 microns, and the average grain size of some target has reached below 50 microns, and crystal grain largest grain size is no more than 3 times of average grain size, has more uniform grain-size.The higher PTF that has that uses the method for inventive example raising to prepare carries out sputter with the nickel platinum target that better prepared by grain-size, target generally has higher work-ing life (more than 120KWH), use the film of preparation of target materials in the embodiment of the present invention to have good homogeneity, in silicon chip, Rs is distributed in 3%.

Comparative example 1～6

Electrolytic nickel taking purity as 4N and Pt sheet are raw material, prepare NiPt alloy cast ingot by vacuum induction melting.Ingot casting is carried out to hot rolling, and hot-rolled temperature is 900 DEG C～1350 DEG C, and hot rolling deformation amount is more than 30%.After hot rolling is complete and cooling, carry out cold rolling and thermal treatment, cold rolling total deformation is 5%～40%, rolling direction is longitudinal or alternately rolling, and thermal treatment temp is 550 DEG C～950 DEG C, 1～4 hour time, comparative example 1～3 is cold rolling respectively carries out once with thermal treatment, comparative example 4～6 is cold rolling carries out more than three times with thermal treatment, but rolling direction is longitudinal rolling, after completing, it is 3mm～5mm that target is worked into thickness, and diameter is 450mm.

Adopt ASTMF-2086-01 method to measure PTF, the PTF numerical value number of measuring is 10, with every 300 clockwise direction image data, calculate the variation range of PTF simultaneously, the calculation formula of PTF variation range is: the difference of maximum value and minimum value is multiplied by 100% divided by mean value; Target after processing is done to metallurgical analysis, and adopt ASTME112-96 to measure average grain size; Target sampling is done to X-ray diffraction (XRD) material phase analysis, calculate single diffraction direction and account for the per-cent of all diffraction peak intensities according to diffraction result; Use this target to carry out thin film sputtering, and measure the sheet resistance of film, the sheet resistance of film adopts four-electrode method to measure, and measures the numerical value of 121 points on a silicon chip and adds up the distribution range of sheet resistance, assesses the homogeneity of film with the distribution (%1s) of sheet resistance data; Complete the life-span of assessing target after thin film sputtering according to the real time of sputter (KWH).Detailed numerical value as shown in Table 1 and Table 2.

The preparation of target materials technique of the different embodiment of table 1 and comparative example

As can be seen from the table, if in cold-rolled process to carrying out once cold rolling and thermal treatment, the PTF of target is generally lower, below 30%, causing cannot build-up of luminance in the time of sputter.Too high or the too low meeting of annealing temperature of little hot-rolled temperature causes the abnormal growth of crystal grain, and mean grain size enlarges markedly, and has occurred that the crystal grain of thousands of microns, largest grain size have exceeded the more than 4 times of average grain size.Fig. 1 and Fig. 2 are respectively the metallographs that adopts the present embodiment and the NiPt target that adopts comparative example to prepare.The nickel platinum target prepared by lower PTF and poor grain-size that has that uses in comparative example of the present invention prepared by method carries out sputter, part PTF% is lower than 30% normally build-up of luminance of target, substantially below 100kWH, and have poor uniformity of film the work-ing life of target.

The target performance evaluation of the different embodiment of table 2 and comparative example

Claims (8)

1. a nickel platinum alloy sputtering target, is characterized in that: in described nickel platinum sputtering target, the content of platinum is 0～5 atomic percent, and the average grain size of target is less than 80 microns, and single grain-size is not more than 150 microns.

2. nickel platinum alloy sputtering target according to claim 1, is characterized in that: in described nickel platinum sputtering target, average grain size is less than 50 microns, and single grain-size is not more than 100 microns.

3. nickel platinum alloy sputtering target according to claim 1, is characterized in that: in X-ray diffraction analysis, the X-ray diffraction peak intensity of (111) crystal face representing with formula I compares for being less than 50%,

... ... ... ... ... formula I.

4. nickel platinum alloy sputtering target according to claim 1, is characterized in that: in X-ray diffraction analysis, the X-ray diffraction peak intensity ratio of (200) crystal face representing with formula II is greater than 20%,

... ... ... ... ... formula II.

5. nickel platinum alloy sputtering target according to claim 1, is characterized in that: the magnetic susceptibility (PTF) of described target be greater than 40% and the numerical value difference measured on each different directions in 5%.

6. nickel platinum alloy sputtering target according to claim 1, is characterized in that: the magnetic susceptibility (PTF) of described target be greater than 50% and the numerical value difference measured on each different directions in 5%.

7. nickel platinum alloy sputtering target according to claim 1, is characterized in that: the magnetic susceptibility (PTF) of described target be greater than 60% and the numerical value difference measured on each different directions in 5%.

8. a preparation method for nickel platinum alloy sputtering target as claimed in claim 1, comprises the following steps:

(a) melting: nickel or nickelalloy raw material are smelted into ingot casting;

(b) hot rolling: hot rolling nickel or Ni alloy ingot become material base;

(c) cold rolling and thermal treatment: the material base after hot rolling is carried out to cold rolling and alternately processing of thermal treatment;

It is characterized in that: wherein need carry out the alternately rolling of transverse and longitudinal when hot rolling, hot-rolled temperature is 950 DEG C～1250 DEG C, and hot rolling deformation amount is more than 30%; Described cold rolling be transverse rolling and axial rolling by an angle of 90 degrees alternately rolling clockwise, cold rolling number of times is twice, carries out a thermal treatment between cold rolling, cold rolling total deflection is in 20%～30%; Described thermal treatment temp is 600 DEG C～800 DEG C, and the time is 1～4 hour.