JP2003167324A - Metal silicide sputtering target and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal silicide sputtering target which ensures optical and chemical properties effective in film deposition for a phase shifting mask and can suppress the generation of particles and to provide a method for manufacturing the target. <P>SOLUTION: The metal silicide sputtering target is characterized in that it has 3-25 at.% metal (M) content and the texture in the target comprises two phases of MSi<SB>2</SB>and free Si. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an LSI, a VLSI.
The present invention relates to a metal silicide sputtering target for forming a thin film used as a material for a phase shift mask used in a semiconductor device such as the above and a manufacturing method thereof.

[0002]

2. Description of the Related Art The demand for miniaturization of lithography in semiconductor manufacturing is accelerating year by year. The demand for mask materials requires resolution and dimensional controllability, and improvements have been tried by introducing new materials. Among them, a halftone type phase shift mask is used as one of the photomasks for transferring a fine pattern. The mask pattern formed on the transparent substrate is composed of a light transmissive part that transmits light of intensity that substantially contributes to exposure and a light semi-transmissive part that transmits light of intensity that does not substantially contribute to exposure. It The light transmitted through the light semi-transmissive part is controlled so that the phase is inverted, and the light transmitted through the light transmissive part is erased from each other at the boundary part between them, thereby improving the contrast at the boundary part. is there. The structure of the phase shift mask is simplified because the light semi-transmissive portion has both the light shielding and phase shifting performances.

It is known that an oxide of metal silicide is effective as a material used for this phase shift mask. This metal silicide oxide film is obtained by reactive sputtering of a metal silicide target containing a large excess of Si in an oxygen atmosphere. This feature is that a single layer film has both light transmittance and phase shift properties at the same time. It is possible to optimize and it is possible to form a very thin film due to the film having a high refractive index, and therefore the step of the mask pattern can be made small. Will also be advantageous.

[0004] In film formation, a metal silicide target with a large excess of Si is carried out by oxygen reactive sputtering, but there is a drawback in that the number of particles is very large in this oxygen reactive sputtering. The requirement for preventing the generation of particles in the mask is comparable to or higher than that of semiconductor devices, and is extremely strict. Therefore, from the viewpoint of reducing particles as in the case of the semiconductor device, it is essential that the target has a high density and a low gas component content such as oxygen or carbon. In the case of DC sputtering, there is a problem that abnormal discharge frequently occurs, so that it is necessary to pay attention to the content and density of oxygen and the like.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a metal silicide sputtering target capable of obtaining effective optical / chemical characteristics during film formation of a phase shift mask and suppressing generation of particles to an extremely low level. It is to establish a manufacturing method.

[0006]

SUMMARY OF THE INVENTION From the above, the present invention relates to 1. 1. A metal silicide sputtering target having a metal (M) content of 3 to 25 at% and a texture in the target consisting of two phases, MSi ₂ and free Si. Metal (M) is Mo, W, Ta, Ti, V, Ni, Cr, Co, Zr, H
2. The metal silicide sputtering target according to 1 above, which is one or more kinds of metal elements selected from f. The metal (M) is Mo, The metal silicide sputtering target according to the above 1, wherein the metal (M) is Mo. 4. 4. The metal silicide sputtering target according to each of the above 1 to 3, wherein the oxygen content is 1000 ppm or less. 6. The metal silicide sputtering target according to each of the above 1 to 3, wherein the oxygen content is 500 ppm or less. 6. The metal silicide sputtering target according to each of the above 1 to 3, wherein the oxygen content is 300 ppm or less. 7. The metal silicide sputtering target according to each of 1 to 6 above, wherein the carbon content is 100 ppm or less. 7. The metal silicide sputtering target according to each of 1 to 6 above, wherein the carbon content is 50 ppm or less. 10. The metal silicide sputtering target according to each of 1 to 6 above, wherein the carbon content is 20 ppm or less. 11. The metal silicide sputtering target according to each of 1 to 9 above, which has a relative density of 98% or more. 11. The metal silicide sputtering target according to each of the above 1 to 9, wherein the relative density is 99% or more. 13. The metal silicide sputtering target 13 according to each of 1 to 11 above, which has a structure in which the MoSi ₂ particle diameter is 20 μm or less and the number of MoSi ₂ particles per 0.01 mm ² is 20 or more. ． After mixing metal powder or metal hydride powder and Si powder, and heating and synthesizing this to obtain metal silicide powder,
The metal silicide powder is mechanically finely pulverized, and then the finely pulverized metal silicide powder and fine Si powder are uniformly mixed so as to have a predetermined molar ratio, and the metal silicide powder is fired using a vacuum heating furnace. 1 to 12 characterized by tying
13. Method for manufacturing metal silicide sputtering target described in 14 above. After mixing metal powder or metal hydride powder and Si powder, and heating and synthesizing this to obtain metal silicide powder,
A vacuum heating furnace using a metal lining and a metal heater by mechanically finely pulverizing the metal silicide powder and then uniformly mixing the fine powder metal silicide powder and the fine Si powder in a predetermined molar ratio. A method for producing a metal silicide sputtering target according to each of 1 to 12 above, characterized in that the metal silicide powder fired by using is sintered.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION A typical silicide target for LSI has a molar ratio of about 2.0 to 3.0, but a large Si excess metal silicide target for a phase shift mask has a molar ratio of 3.0 to 32.3 (Msi _{32 to} Msi ₃ ). The target is manufactured by the powder metallurgy method, but its structure must be fine and uniformly dispersed in order to reduce particles. If the metal content is less than 3 at%, it becomes brittle like a poly-Si target, so that the sputtering power is not applied so much and particles increase due to generation of microcracks. 25at metal content
If it exceeds%, effective optical properties such as refractive index cannot be obtained. Therefore, the metal content needs to be in the range of 3 to 25 at%.

In the conventional Si large excess metal silicide target, metal powder and Si are mixed and sintered to produce a sputtering target. In such a target manufacturing method, a silicidation reaction occurs between the metal powder and the Si powder during sintering, and heat generation causes coarsening of the structure near the metal powder due to melting of the silicide and Si. And
Such a coarse structure causes a large step due to a difference in sputtering rate during sputtering, which causes generation of particles. Therefore, the silicidation reaction must be performed before sintering.

Therefore, fine metal powder or fine metal hydride powder and fine Si powder were used to heat-synthesize metal silicide at a temperature at which crystal structure coarsening did not occur, and this metal silicide powder was finely pulverized. The fine Si powder is uniformly mixed into the product to a predetermined molar ratio, that is, a molar ratio of 2.
A metal silicide synthetic powder near 0 was prepared in advance, and a powder obtained by finely pulverizing this synthetic powder and Si powder were mixed and sintered to obtain a sputtering target having a uniform fine structure. However, in such a process, oxygen is adsorbed on the surface in the pulverization process and the mixing process after the synthesis, and a large amount of oxygen is inevitably picked up. The adsorption of oxygen increases in proportion to the surface area of the finely pulverized powder, and the oxygen content taken into the target reaches about 1000 to 2000 ppm. When sputtering is performed using a target having a high oxygen content as described above, there is a problem that abnormal discharge due to the oxide in the target occurs on the target surface and particles increase.

As a solution to the above, graphite
Use a heating furnace that uses a metal lining and a heater
Sinter (heat treatment) the silicide-Si mixed powder under vacuum
It was found that the oxygen content can be reduced by
It was In particular, the material of the lining of the vacuum heating furnace and the heater
Other than graphite, preferably like molybdenum
Preventing carbon (C) contamination from the furnace body by using metal
Not only to reduce the carbon content to 20ppm or less
I found that I can do it. This deoxygenation reaction is
O₂React with each other and gasify as SiO,
The decarbonization reaction converts the existing C into CO or CO₂In the form of
This is due to the fact that it can be reduced by converting the
As described above, by the process of the present invention, the relative density is 98% or more.
Has a relative density of 99% or more.₂Particle size is 20μm or less
Bottom, 0.01mm²MoSi per hit₂Tissue with 20 or more particles
A metal silicide sputtering target with
Be done. MoSi ₂Particle size is over 20μm and 0.01mm²
MoSi per hit₂If the number of particles is less than 20, coarse MoSi₂grain
The grain boundary step between the silicon and the Si phase becomes large, and re-deposition occurs at the step.
It is preferable because it causes the film to adhere and increase the number of particles.
Not MoSi₂Particle size 20μm or less, 0.01mm²Per hit
MoSi₂It is desirable that the number of particles be 20 or more. The present invention
Targets such as are effective during phase shift mask deposition
Excellent optical and chemical properties and particle generation
Excellent effect that can keep the amount of raw material extremely low
Have.

[0011]

EXAMPLES Next, examples and comparative examples will be described.
In addition, this embodiment is for showing an example of the invention,
The invention is not limited to these examples. That is, it includes other aspects and modifications included in the technical idea of the present invention.

(Examples 1-1 to 1-18) High-purity metal powder M (in this case, M is Mo, W, Ta, Cr, Zr, H, respectively)
f) and high-purity Si powder were mixed in a ball mill and heated in a vacuum to obtain an alloy mass of MSix (x = 2.50). This lump of silicide is pulverized with a jet mill to obtain a silicide powder (MoSi, WSi, Ta) having a maximum particle size of 20 μm.
Si, CrSi, ZrSi, HfSi) was obtained. These silicide powders are jet milled to a maximum particle size of 20
Si powder made to be μm, M: 3at%, 15at%, 25at
%, That is, Si / M is 32.33,
5.67 and 3.00 were mixed, and the mixed powder was vacuum heat-treated for 4 hours in a metal-lined vacuum sintering furnace at 1350 ° C. and a vacuum degree of 1 × 10 ⁻⁴ torr, and the obtained silicide mass was ball-milled. Was pulverized to obtain a silicide powder. Using this silicide powder, a sintered body was prepared by a hot pressing method, a target of φ300 mm × 6.35 mmt was prepared by machining, and sputtering was performed to measure particles on a wafer (6 inch type). The results are shown in Table 1. Table 1 also shows oxygen (O) analysis values, carbon (C) analysis values, denseness, maximum particle size of silicide, average number of particles, and heat treatment furnace lining heater material. The average number of particles in Table 1 indicates the number of particles of metal silicide per 0.01 mm ² . The same applies hereinafter.

(Examples 2-1 to 2-9) High-purity metal powder M (in this case, M is Mo, W, and Ta, respectively) and high-purity S
The i powder was mixed in a ball mill and heated in a vacuum to obtain an alloy mass of MSix (x = 2.50). This lump of silicide was pulverized by a jet mill to obtain a silicide powder having a maximum particle size of 20 μm. Si powder with a maximum particle size of 20 μm was pulverized to this silicide powder by M: 3 at%, 1
5 at% and 25 at%, that is, Si / M was mixed at 32.33, 5.67, and 3.00, respectively, and the mixed powder was heated to 1350 ° using a graphite-lined vacuum sintering furnace.
C, vacuum heat treatment is performed at a vacuum degree of 1 × 10 ⁻⁴ torr for ⁴ hours, and the obtained silicide mass is crushed by a ball mill to obtain a silicide (Mo
Si, WSi, TaSi) powder was obtained. Using this silicide powder, a sintered body was prepared by hot pressing, and a target of φ300 mm × 6.35 mmt was prepared by machining,
Sputtering was performed to measure particles on the wafer (6 inch type). The results are also shown in Table 1.
Table 1 also shows oxygen (O) analysis values, carbon (C) analysis values, denseness, maximum particle size of silicide, average number of particles, and heat treatment furnace lining heater material.

(Comparative Examples 1-1 to 1-7) High-purity metal powder M (in this case, M is Mo, W, Ta) and high-purity S
i powder with a ball mill, M: 3.00at%, 15.00at%, 2
5.00at% (however, for W and Ta, M: 3.00at
%, 25.00 at%), that is, Si / M is 32.33, 5.67, 3.00 (however, for W and Ta, 32.33, 3.00), and the mixed powder is vacuum lined with metal. 1350 ° C, 1 × 10 ^-4 torr using sintering furnace
Vacuum synthesizing for 4hr at the degree of vacuum, and crushing the obtained silicide mass with a ball mill to obtain silicide (MoSi, WSi, T
aSi) powder was obtained. Using this silicide powder, a sintered body was prepared by hot pressing and was machined to a diameter of 30 mm.
A target of 0 mm × 6.35 mmt was prepared and sputtered to measure particles on a wafer (6 inch type). The results are shown in Table 1. Table 1 also shows oxygen (O) analysis values, carbon (C) analysis values, denseness, maximum particle size of silicide, average number of particles, and heat treatment furnace lining heater material.

(Comparative Examples 2-1 to 2-7) A mixed powder made of the same materials as in Comparative Examples 1-1 to 1-7 was used at 1350 ° C. and 1 × 10 6 using a graphite-lined vacuum sintering furnace. Vacuum synthesis was performed at a vacuum degree of ^-4 torr for ⁴ hours, and the obtained silicide mass was crushed by a ball mill to obtain a silicide (MoSi, WSi, TaSi) powder. Similar to Comparative Examples 1-1 to 1-7, using these silicide powders, a sintered body was prepared by a hot pressing method, a target of φ300 mm × 6.35 mmt was prepared by machining, and sputtering was performed on the wafer (6 Inch type) particles were measured. The results are shown in Table 1. Similarly, in Table 1, oxygen (O) analysis value, carbon (C) analysis value, element,
The maximum particle size of silicide, the average number of particles, and the heater material lined in the heat treatment furnace are also shown.

[0016]

[Table 1]

As shown in Table 1 above, Examples 1-1 to 1-18
As for the material, Mo was used as the heater material for the heat treatment furnace, but the oxygen content was as small as 270 to 520 ppm and the carbon content was also small (20 ppm or less). The maximum particle size is 20μ
The number of particles was m or less and the number of particles was 30 or less. In Examples 2-1 to 2-9, carbon was used as the heater lining heater material. Oxygen 450-60
The amount of carbon is a little high, and the amount of carbon is also 50 to 100 ppm. The maximum particle size was 20 μm or less, and the number of particles was 18 to 35, which were slightly larger than those of Examples 1-1 to 1-18, but all showed good results. In contrast to these Examples, Comparative Examples 1-1 to 1-7 use a metal lining as a heat treatment furnace lining heater material and have a relatively large amount of oxygen of 350 to 510 ppm, but a small amount of carbon (20 ppm or less). . However, the maximum particle size was as large as 31 to 53 μm, and the number of particles was 58 to 130, which was larger than those in the examples, and all showed bad results. In Comparative Examples 2-1 to 2-7, carbon lining was used as the heater material for the heat treatment furnace and oxygen 3
20 to 650 ppm and the amount of carbon is 120 to 280
Remarkably increased to ppm. The maximum particle size is 24-50.
The number of particles was 82 μm to 230 μm, which was very large, and was much larger than those of the examples.
Regarding the above, as metals (M), especially Mo, W, T
a, Cr, Zr, Hf are shown, but Ti, which is not listed here,
Similar results were obtained for V, Ni and Co.

[0018]

INDUSTRIAL APPLICABILITY The present invention can provide a metal silicide sputtering target capable of obtaining effective optical / chemical characteristics during film formation of a phase shift mask and suppressing generation of particles to an extremely low level, and a method of manufacturing the same. It has an excellent effect that it can be done.

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Claims (14)

[Claims] 1. A metal silicide sputtering target having a metal (M) content of 3 to 25 at%, and the structure of the target is composed of two phases, MSi ₂ and free Si. 2. The metal (M) is Mo, W, Ta, Ti, V, Ni, Cr,
The metal silicide sputtering target according to claim 1, which is one or more kinds of metal elements selected from Co, Zr, and Hf. 3. The metal silicide sputtering target according to claim 1, wherein the metal (M) is Mo. 4. The metal silicide sputtering target according to each of claims 1 to 3, wherein the oxygen content is 1000 ppm or less. 5. The metal silicide sputtering target according to claim 1, wherein the oxygen content is 500 ppm or less. 6. The metal silicide sputtering target according to claim 1, wherein the oxygen content is 300 ppm or less. 7. The metal silicide sputtering target according to each of claims 1 to 6, wherein the carbon content is 100 ppm or less. 8. The metal silicide sputtering target according to each of claims 1 to 6, wherein the carbon content is 50 ppm or less. 9. The metal silicide sputtering target according to each of claims 1 to 6, wherein the carbon content is 20 ppm or less. 10. The metal silicide sputtering target according to claim 1, wherein the relative density is 98% or more. 11. The metal silicide sputtering target according to claim 1, wherein the relative density is 99% or more. 12. The MoSi ₂ particle size is 20 μm or less, 0.0
The metal silicide sputtering target according to each of claims 1 to 11, which has a structure in which the number of MoSi ₂ particles per 1 mm ² is 20 or more. 13. Metal powder or metal hydride powder and Si
After mixing the powders, and heating and synthesizing the powders to form a metal silicide powder, the metal silicide powder is mechanically pulverized,
Next, the finely pulverized metal silicide powder and the fine Si powder are uniformly mixed so as to have a predetermined molar ratio, and the metal silicide powder fired using a vacuum heating furnace is sintered. 2. A method of manufacturing a metal silicide sputtering target according to each of 1. 14. Metal powder or metal hydride powder and Si
After mixing the powders, and heating and synthesizing the powders to form a metal silicide powder, the metal silicide powder is mechanically pulverized,
Next, this fine powder metal silicide powder and fine Si powder are uniformly mixed so as to have a predetermined molar ratio, and the metal silicide powder fired using a vacuum heating furnace using a metal lining and a metal heater is sintered. It is characterized by the above-mentioned.
2. The method for producing a metal silicide sputtering target according to each of 2.