CN115007864A - Pure tungsten plate for ion implantation and preparation method and application thereof - Google Patents

Abstract

The invention relates to the technical field of tungsten plate production, in particular to a pure tungsten plate for ion implantation and a preparation method and application thereof. The pure tungsten plate for ion implantation is prepared by pressing, sintering, recrystallization rolling and stress relief annealing pure tungsten powder, and the metallographic structure of the pure tungsten plate for ion implantation is in a strip fiber state. The pure tungsten plate for ion implantation provided by the invention is prepared from pure tungsten powder through pressing, sintering, rolling and stress relief annealing, and the pure tungsten plate for ion implantation with a metallographic structure in a strip fiber state is prepared. Moderate hardness and uniform microstructure. Under the same cutting process, the tool loss is only 25 percent of that of a fine-grained pure tungsten plate and 40 percent of that of a coarse-grained pure tungsten plate, and the milling performance of the milling machine with excellent machining performance is excellent. Meanwhile, the pure tungsten plate for ion implantation provided by the invention is manufactured into a part, and the milled edge has no crack, burr and unfilled corner; the surface is smooth, and no obvious messy tool marks exist; the inner wall of the countersunk hole is smooth, and the bottom has no turned edge and has excellent use performance.

Description

Pure tungsten plate for ion implantation and preparation method and application thereof

Technical Field

The invention relates to the technical field of tungsten plate production, in particular to a pure tungsten plate for ion implantation and a preparation method and application thereof.

Background

The pure tungsten plate is an important component of an ion implanter in the semiconductor field, and the semiconductor ion implantation technology is a high and new technology for material surface modification, which is an essential technology in the modern manufacture of large-scale integrated circuits. The tungsten device manufactured by precisely machining a tungsten plate with the thickness of 2-10 mm is mainly used for an ion source system of a semiconductor ion implanter, plays a role in restraining and shielding ionizing rays, and is a key part for manufacturing the ion source system.

The Chinese semiconductor material market has a high-speed growth trend in recent years, and international well-known companies have also increased the procurement plans in China. The development space of tungsten devices for semiconductor devices is quite wide. In addition, the localization of ion implantation equipment is a great trend, and the current tungsten plate for ion implantation has the main difficulties of large milling loss and high cost. The main production process is that tungsten powder is used as raw material, and the tungsten powder is made into blank by powder metallurgy method, then is rolled and deformed, and finally is processed into tungsten parts with corresponding shape and size requirements by precision machining technology, and the processed shape is complex, so that the method not only has rigorous requirements on precision, but also has strict requirements on appearance quality and use effect. Therefore, a pure tungsten plate with excellent milling performance, low processing cost and stable performance is needed to solve the problems of high loss of the existing pure tungsten plate milling cutter, poor use performance of the pure tungsten plate and the like, so as to promote the localization process of the ion implantation equipment.

Disclosure of Invention

In order to solve the problems of insufficient milling performance, high cutter loss, poor use performance and the like of the pure tungsten plate in the prior art, the invention provides the pure tungsten plate for ion implantation, which is prepared by pressing, sintering, recrystallization rolling and stress relief annealing of pure tungsten powder, wherein the metallographic structure of the pure tungsten plate for ion implantation is in a long-strip fibrous state.

In one embodiment, the aspect ratio of the long strip fibrous metallographic structure is greater than 10:1, and the length of the long strip fibrous metallographic structure is greater than 200 um.

In one embodiment, the pressing process adopts cold isostatic pressing, the maximum pressing pressure is 220-230 MPa, and the pressure maintaining time is 50-70 s.

In one embodiment, the sintering process adopts medium-frequency sintering, the maximum sintering temperature is 2200 ℃, and the temperature is kept at the maximum temperature for 15-20 hours. Preferably, the sintered density is more than or equal to 18.8g/cm ³ 。

In one embodiment, the recrystallization rolling is performed with recrystallization annealing in the rolling process, the annealing temperature is 1600 +/-100 ℃, and the holding time is 1-2 hours.

In one embodiment, a 650-mill is adopted in the rolling process to perform cross rolling on the sintered blank, the heating temperature is 1500 +/-50 ℃ in the cogging stage, the heat is preserved for 1-2 hours, and the deformation of the first pass is 30%; the subsequent passes are insulated for 10 minutes according to the temperature of 1400 +/-50 ℃, and the deformation amount of each time is 10 percent; and (3) when the deformation reaches 50%, carrying out primary recrystallization annealing at the annealing temperature of 1600 +/-100 ℃ for 1-2 hours, and rolling the target specification according to the 10% deformation after recrystallization annealing until the rolling is finished.

In one embodiment, the purity of the pure tungsten powder is more than or equal to 99.98%, and the average particle size is 3-4 um. Preferably, the pure tungsten powder is produced by adopting Xiamen aigrette tungsten industry.

In one embodiment, the temperature of the stress relief annealing is 1300 ℃ +/-100 ℃ and the holding time is 2-3 hours.

The invention also provides a preparation method of the pure tungsten plate for ion implantation, which comprises the following steps:

s1, selecting pure tungsten powder with the purity of more than or equal to 99.98% and the average particle size of 3-4 um;

s2, putting pure tungsten powder into a mold, pressing a green body by adopting isostatic cool pressing, wherein the highest pressure of the green body is 220-230 MPa, and the pressure maintaining time is 50-70S;

s3, performing intermediate frequency sintering on the pressed green body, wherein the sintering temperature is 2200 ℃ at the highest temperature, and keeping the temperature at the highest temperature for 15-20 h in a hydrogen atmosphere environment to obtain a sintered green body; preferably, the sintered density is more than or equal to 18.8g/cm ³ ；

S4, a 650-pass rolling mill is adopted in the rolling process to perform cross rolling on the sintered blank, the heating temperature is 1500 +/-50 ℃ in the cogging stage, the heat is preserved for 1-2 hours, and the primary deformation is 30%; the subsequent passes are insulated for 10 minutes according to the temperature of 1400 +/-50 ℃, and the deformation amount of each time is 10 percent; when the deformation reaches 50%, carrying out primary recrystallization annealing at the annealing temperature of 1600 +/-100 ℃ for 1-2 hours, and rolling the target specification according to the 10% deformation after recrystallization annealing until the rolling is finished;

and S5, after the rolling is finished, performing stress relief annealing by using a muffle furnace, and preserving the heat at 1300 ℃ for 2 hours to obtain the pure tungsten plate for ion implantation.

The invention also provides an application of the pure tungsten plate for ion implantation or the pure tungsten plate for ion implantation prepared by the preparation method in the field of ion implantation.

Based on the above, compared with the prior art, the pure tungsten plate for ion implantation provided by the invention is prepared by pressing, sintering, rolling and stress relief annealing pure tungsten powder to obtain the pure tungsten plate for ion implantation with a strip-shaped fibrous metallographic structure. Moderate hardness and uniform microstructure. Under the same cutting process, the tool loss is only 25 percent of that of a fine-grained pure tungsten plate and 40 percent of that of a coarse-grained pure tungsten plate, and the milling performance of the milling machine with excellent machining performance is excellent. Meanwhile, the pure tungsten plate for ion implantation provided by the invention is manufactured into a part, and the milled edge has no crack, burr and unfilled corner; the surface is smooth, and no obvious messy tool marks exist; the inner wall of the countersunk hole is smooth, and the bottom has no turned edge and has excellent use performance.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts; in the following description, the drawings are illustrated in a schematic view, and the drawings are not intended to limit the present invention.

FIG. 1 is a metallographic structure diagram of example 1;

FIG. 2 is a metallographic structure diagram of comparative example 1;

FIG. 3 is a metallographic structure diagram of comparative example 2;

FIG. 4 is a hardness comparison graph;

FIG. 5 is a graph of insert wear after the milling test of example 1;

FIG. 6 is a graph of insert wear after milling test of comparative example 1;

FIG. 7 is a graph of insert wear after milling test of comparative example 2;

FIG. 8 is a view of the surface condition after the milling test of example 1;

FIG. 9 is a graph of the surface condition after milling test of comparative example 1;

FIG. 10 is a graph of the surface condition after the milling test of comparative example 2;

FIG. 11 is a roughness comparison graph after milling test;

FIG. 12 is a front view of the embodiment 1 after processing into parts;

fig. 13 is a rear view of fig. 12.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments; the technical features designed in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other; all other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it is to be noted that all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs, and are not to be construed as limiting the present invention; it will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Example 1

Raw materials: the method selects mansion rainbow molybdenum tungsten industrial pure tungsten powder, the purity of the powder is more than or equal to 99.98 percent, the average particle size of the powder is 3-4 um, and the chemical components are shown in table 1.

Pressing: and pressing the green blank by adopting cold isostatic pressing, wherein the specification of a pressing die is 300 × 250 × 45, the maximum pressure of the green blank is 225MPa, and the pressure maintaining time is 60 s.

And (3) sintering: sintering by adopting a medium-frequency sintering mode, placing at 250 width sides, performing heat preservation for 20 hours at the highest temperature in a hydrogen atmosphere environment at the highest temperature of 2200 ℃, wherein the sintering density is more than or equal to 18.8g/cm ³ 。

Rolling: and (3) performing cross rolling on the sintered blank by using a 650-type rolling mill, preserving the heat of 1500 ℃ for 1 hour in the cogging stage, preserving the heat of 30% in the first pass, preserving the heat of 1400 ℃ for 10 minutes in the subsequent passes, and preserving the heat of 10% in each pass. Carrying out primary recrystallization annealing when the deformation reaches 50%, keeping the annealing temperature at 1600 ℃ for 1 hour, and rolling the target specification according to the deformation of 10% after recrystallization annealing until the rolling is finished;

stress relief: and (3) preserving the temperature of the rolled product at 1300 ℃ for 2 hours by adopting a muffle furnace.

TABLE 1 chemical composition Table

Chemical elements

W

O

Mo

Fe/C

K/Cr/Na/Ni

Ca/Mn

S

Co/Cd/Cu

Content%

≥99.98

＜0.0050

＜0.0020

＜0.0015

＜0.0010

＜0.0005

＜0.0002

＜0.0001

Comparative example 1

Commercially available fine grain type pure tungsten plate (no recrystallization annealing in the production process)

Comparative example 2

Commercial coarse crystal pure tungsten plate (the metallographic structure is changed by temperature control in the production process, the mark is W1)

The tests of example 1 and comparative examples 1-2 were carried out according to the following test items and methods:

metallographic phase: calibrating the rolling direction of the tungsten plate, preparing a sample through a metallographic sampling machine, analyzing the sample by using a Lycra metallographic microscope after the sample preparation is finished, and obtaining a detection result shown in the figure 1-3.

Hardness: samples of example 1 and comparative examples 1-2 were taken, and multi-point sampling was performed at the same point of different samples, and Vickers hardness HV30 was used to characterize hardness and volatility, and the test results are shown in Table 2 and FIG. 4.

Milling performance: the samples of the embodiment 1 and the comparative examples 1-2 are firstly blanked by linear cutting to prepare square plate samples of 100 multiplied by 50mm, and then a plane grinder is used for six-side polishing to ensure that the milling test sample flatness and verticality of different microstructures of the three square plate samples are in a consistent state. And then, carrying out milling test by adopting a Beijing finishing impression machine, wherein the cutter adopts a Jinlu hard alloy cutter with the specification of a D6 flat-bottom milling cutter. The milling performance of the same cutter and different milling materials is characterized by comparing the cutter abrasion difference, and the cutter abrasion test result is shown in figures 5-7.

Surface roughness: the surface roughness after milling is tested by adopting a Sanfeng roughness measuring instrument, and the test results are shown in the figures 8-11 and table 3.

TABLE 2 hardness comparison

Location point	1	2	3	4	5	6	7	8	9	10
											Example 1	410	415	408	413	411	413	416	405	406	409
Comparative example 1	440	439	441	435	430	421	442	439	438	440
											Comparative example 2	356	370	343	350	362	340	375	370	372	344

TABLE 3 roughness comparison

Location point	1	2	3	4	5	6	7	8	9	10
											Example 1	0.65	0.68	0.71	0.66	0.7	0.69	0.68	0.66	0.67	0.69
Comparative example 1	0.98	1.00	0.94	0.99	0.94	0.88	1.05	0.97	0.92	0.86
											Comparative example 2	1.84	1.77	1.86	1.85	1.86	1.77	1.66	1.65	1.88	1.73

As can be seen from FIGS. 1 to 3, the microstructure in the rolling direction of example 1 is a coarse long fiber structure, the microstructure in the rolling direction of comparative example 1 is a fine short fiber structure, and the microstructure in the rolling direction of comparative example 2 is coarse large crystals.

As can be seen from fig. 4, comparative example 2 < example 1 < comparative example 1 in the hardness value. At this time, the hardness of the steel is only slightly reduced in example 1 compared with that of comparative example 2, and is above 400HV 30; from the hardness distribution of the three components, the fluctuation is shown in that example 1 is smaller than comparative example 2. The main reason for this is that comparative example 2 is in a state close to partial recrystallization, the distribution of the crystal grain size is not uniform, the hardness is small when the hardness is hit at coarse crystal grains, and the hardness is large when the hardness is hit at small crystal grains. The comparative example 1 exhibited coarse grains in part on the microstructure, resulting in fluctuation in hardness distribution. In contrast to the first two, the microstructure of example 1 is relatively uniform and the hardness distribution is relatively stable.

The surface quality is different after the milling test, the surface state is shown in figures 8-11, and the tungsten plate surface pits in the comparative example 2 are obvious. The tungsten plate of comparative example 1 has no obvious grain and pit on the surface, but has obvious knife mark on the surface. The tungsten plate of the embodiment 1 has smooth surface after milling, no particle falling and pit points and relatively few milling traces. The roughness values are shown in FIG. 5, and from the roughness average values, example 1 < comparative example 2. The reason is that the grain boundaries of the crystal grains of comparative example 2 move, the crystal grains coarsen, and reach relatively stable shapes and sizes, in this state, the hardness decreases, the bonding force between the crystal grains is weak, and larger crystal grains fall off under the milling force to form a pit, and the roughness value is larger. The microstructure of the comparative example 1 is fine and short fibrous, the number of grain boundaries is large, the bonding force between the grain boundaries and the grain boundaries is strong, and the hardness is also large, so that the tool nose of the milling tool is easy to break during milling, and the surface tool mark is serious, and the conclusion is continued to be demonstrated in the influence of the microstructure on the tool damage. The microstructure of example 1 is a thick and long fibrous shape, the number of grain boundaries is larger in example 1 compared with that of comparative example 2, and the lapping shape is formed between the crystal grains, so that the strength between the crystal grains is increased, and the situation that the crystal grains are peeled off in the milling process is not easy to occur. Compared with comparative example 1, the surface state of example 1 is obviously better than that of comparative example 1 and comparative example 2, and the excellent milling performance of example 1 is reflected.

Meanwhile, due to the characteristics of high hardness and high brittleness, the pure tungsten plate cannot be machined by a side edge cutting mode, and only can be milled by a bottom edge for a flat-bottom milling cutter, so that the influence of the microstructure on the cutter damage can be accurately evaluated by comparing the abrasion degrees of the bottom edges of different microstructures under the same cutting process.

As can be seen from FIGS. 5 to 7, the wear of the end edge of the milling cutter in example 1 < comparative example 2 < comparative example 1, the wear area of the end edge of example 1 was 0.154mm as evaluated from the flat bottom wear area ² Comparative example 2 bottom edge wear area 0.379mm ² Comparative example 1 having a bottom edge wear area of 0.612mm ² The wear of the cutter of example 1 was only 25% of that of comparative example 1 and 40% of that of comparative example 2. During milling, the surface quality is guaranteed to be bright without pits, falling grains and pits, the comparative example 2 is in a partially recrystallized state, the grain boundary bonding force is weak, the uniformity of grains is poor, and in the milling process, the milling cutter can generate small and large impact on the cutting edge of the milling cutter, so that the cutter is abraded. Secondly, the hardness is the main reason for generating the cutter loss, the comparative example 1 is a fine grain structure, and the grain boundary number multi-binding force is strong, so that the hardness is high, and the cutter loss is large in the milling process. Therefore, the pure tungsten plate of the milling example 1 has lower tool loss than the pure tungsten plate of the comparative example 1 and the pure tungsten plate of the comparative example 2, and shows the excellent machining performance of the pure tungsten plate for ion implantation provided by the invention.

The test processing is carried out on the ion implantation part obtained in the embodiment 1, and the results are shown in fig. 12-13, so that the milled edge of the obtained ion implantation part has no notches, burrs or unfilled corners; the surface is smooth, and no obvious messy tool marks exist; the inner wall of the countersunk hole is smooth, and the bottom of the countersunk hole is not provided with a turned edge and a broken opening.

In summary, the pure tungsten plate for ion implantation provided by the invention is prepared from pure tungsten powder through pressing, sintering, rolling and stress relief annealing, and the pure tungsten plate for ion implantation with a metallographic structure in a strip fiber state is prepared. Moderate hardness and uniform microstructure. Under the same cutting process, the tool loss is only 25 percent of that of a fine-grained pure tungsten plate and 40 percent of that of a coarse-grained pure tungsten plate, and the milling performance of the milling machine with excellent machining performance is excellent. Meanwhile, the pure tungsten plate for ion implantation provided by the invention is manufactured into a part, and the milled edge has no crack, burr and unfilled corner; the surface is smooth, and no obvious messy tool marks exist; the inner wall of the countersunk hole is smooth, and the bottom has no turned edge and has excellent use performance.

In addition, it will be appreciated by those skilled in the art that, although there may be many problems with the prior art, each embodiment or aspect of the present invention may be improved only in one or several respects, without necessarily simultaneously solving all the technical problems listed in the prior art or in the background. It will be understood by those skilled in the art that nothing in a claim should be taken as a limitation on that claim.

Although terms such as pressing, sintering, rolling, stress relief annealing, recrystallization annealing, etc. are used more often herein, the possibility of using other terms is not excluded. These terms are used merely to more conveniently describe and explain the nature of the present invention; they are to be construed as being without limitation to any additional limitations that may be imposed by the spirit of the present invention; the terms "first," "second," and the like in the description and in the claims, and in the drawings, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1. A pure tungsten plate for ion implantation is characterized in that: the ion implantation pure tungsten plate is prepared by pure tungsten powder through pressing, sintering, recrystallization rolling and stress relief annealing, and the metallographic structure of the pure tungsten plate for ion implantation is in a long-strip fibrous state.

2. The pure tungsten plate for ion implantation according to claim 1, wherein: the length-width ratio of the long fibrous metallographic structure is greater than 10:1, and the length of the long fibrous metallographic structure is greater than 200 um.

3. The pure tungsten plate for ion implantation according to claim 1, wherein: and the pressing process adopts cold isostatic pressing, the highest pressing pressure is 220-230 MPa, and the pressure maintaining time is 50-70 s.

4. The pure tungsten plate for ion implantation according to claim 1, wherein: the sintering process adopts medium-frequency sintering, the maximum sintering temperature is 2200 ℃, and the temperature is kept at the maximum temperature for 15-20 h.

5. The pure tungsten plate for ion implantation according to claim 1, wherein: and the recrystallization rolling is to perform recrystallization annealing in the rolling process, wherein the annealing temperature is 1600 +/-100 ℃, and the heat preservation time is 1-2 hours.

6. The pure tungsten plate for ion implantation according to claim 5, wherein: the rolling process adopts a 650 rolling mill to perform cross rolling on the sintered blank, the heating temperature is 1500 +/-50 ℃ in the cogging stage, the heat is preserved for 1-2 hours, and the first deformation is 30%; the subsequent passes are insulated for 10 minutes according to the temperature of 1400 +/-50 ℃, and the deformation amount of each time is 10 percent; and (3) when the deformation reaches 50%, carrying out primary recrystallization annealing at the annealing temperature of 1600 +/-100 ℃ for 1-2 hours, and rolling the target specification according to the 10% deformation after recrystallization annealing until the rolling is finished.

7. The pure tungsten plate for ion implantation according to claim 1, wherein: the purity of the pure tungsten powder is more than or equal to 99.98%, and the average particle size is 3-4 um.

8. The pure tungsten plate for ion implantation according to claim 1, wherein: and the stress relief annealing temperature is 1300 +/-100 ℃, and the heat preservation time is 2-3 hours.

9. A method for producing the pure tungsten plate for ion implantation according to any one of claims 1 to 8, comprising the steps of:

s1, selecting pure tungsten powder with the purity of more than or equal to 99.98% and the average particle size of 3-4 um;

s2, putting pure tungsten powder into a mold, pressing a green body by adopting isostatic cool pressing, wherein the highest pressure of the green body is 220-230 MPa, and the pressure maintaining time is 50-70S;

s3, performing intermediate frequency sintering on the pressed green body, wherein the sintering temperature is 2200 ℃ at the highest temperature, and keeping the temperature at the highest temperature for 15-20 h in a hydrogen atmosphere environment to obtain a sintered green body;

s4, performing cross rolling on the sintered blank by using a 650-type rolling mill in the rolling process, wherein the sintered blank is subjected to cross rolling by using the 650-type rolling mill, the heating temperature is 1500 +/-50 ℃ in the cogging stage, the heat is preserved for 1-2 hours, and the first deformation is 30%; the subsequent passes are insulated for 10 minutes according to the temperature of 1400 +/-50 ℃, and the deformation amount of each time is 10 percent; when the deformation reaches 50%, carrying out primary recrystallization annealing at the annealing temperature of 1600 +/-100 ℃ for 1-2 hours, and rolling the target specification according to the 10% deformation after recrystallization annealing until the rolling is finished;

and S5, after the rolling is finished, performing stress relief annealing by using a muffle furnace, and preserving the heat at 1300 ℃ for 2 hours to obtain the pure tungsten plate for ion implantation.

10. An application in the field of ion implantation, which is characterized in that the pure tungsten plate for ion implantation according to any one of claims 1 to 8 or the pure tungsten plate for ion implantation prepared by the preparation method according to claim 9 is adopted.

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