JP2753865B2 - Conductive substrate for drawing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a drawing apparatus material for forming a fine circuit on a mask / reticle substrate by an electron beam or the like, for example, a mask for holding a mask / retics substrate The present invention relates to a non-magnetic and conductive substrate such as an XY table for moving the holder in the vertical and horizontal directions.

[Conventional technology]

FIG. 1 is a schematic explanatory view of a drawing apparatus conventionally used, in which a mask / retics substrate 3 is elastically held by a mask holder 2 fixed on an XY table 1.
Then, while moving the XY table 1 in the X or Y direction, a circuit is formed on the mask / retics substrate 3 by the electron beam emitted from the upper electron beam emitting device 4. .

Such an XY table 1 and a mask holder 2
If the material is magnetic, it will adversely affect the straightness of the electron beam and significantly degrade the drawing accuracy. In order to release the generated static electricity, it is required that the volume resistivity be less than 10 ³ Ω · cm. Conventionally, metals such as beryllium copper (BeCu) and copper phosphate have been used as base materials satisfying such characteristics.

[Problems to be solved by the invention]

However, such metals have a coefficient of thermal expansion of 12x10
⁻⁶ / ° C. or more, the circuit projection position tends to shift depending on the ambient temperature when forming a circuit, and there is a limit in forming a fine circuit. Further, since the Young's modulus is as low as ² × 10 ⁶ kg / cm ² or less, the rigidity is small and the base is easily deformed. Further, since the specific gravity is as large as 8 or more, there is a problem that, for example, the XY stage cannot be reduced in weight to achieve a light operation.

In addition, the width of the circuit pattern on the mask has been extremely strictly required to be 0.5 μm or less with the recent increase in circuit density, and it is difficult to achieve the above with the base material.

Then, in order to solve the above-mentioned problem, the inventor of the present application tried to use a conductive ceramic as a base material satisfying the above characteristics. Among conductive ceramics such as Si ₃ N ₄ and SiC, the thermal expansion coefficient is ⁶ × 10 ⁻⁶ / ° C. or less, and the Young's modulus is 3
This is because some have characteristics that can solve the above-mentioned problems, such as x10 ⁶ kg / cm ² or more and specific gravity of 4.0 or less.

However, such ceramic powders usually contain magnetic metals such as Fe inevitably.If the content of the magnetic metals is large, the magnetic flux density in the sintered body cannot be sufficiently reduced. When used as a conductive substrate material for a drawing apparatus, it adversely affects the straightness of an electron beam. In addition, since the flatness of the surface of the ceramic sintered body is usually as rough as 10 μm or more, when forming a circuit while holding the mask, the error of the projection position on the mask exceeds 0.5 μm, and it is necessary to form a circuit with a fine width. There is a limit.

[Object of the invention]

In the present invention, the effect of thermal expansion due to the ambient temperature is small, the substrate is unlikely to be deformed, and the conductive substrate has a small specific gravity, and has a volume specific resistance of 10 ³ Ωcm or less. And the magnetic flux density is 0.05mG (milligauss)
An object of the present invention is to provide a conductive substrate for a drawing apparatus in which the flatness of the surface of the sintered body is 5 μm or less.

[Means for solving the problem]

Therefore, the present inventor has set the composition ratio of the conductive ceramic within a certain range, reduced the Fe content of the magnetic metal in this sintered body to a predetermined amount or less, and reduced the magnetic flux density to 0.05 mG.
On the other hand, the above problem was solved by setting the flatness of the surface of the sintered body to 5 μm or less while making it sufficiently small as follows.

According to the present invention, the aluminum compound is 0.1 to 10% by weight, and at least one compound of the group IIa element and the group IIIa element is 0.1% by weight.
~ 10% by weight, 0.5 to 10% by weight of the conductivity-imparting agent, the remainder is a conductive SiC sintered body consisting of silicon carbide (SiC),
Fe content of the inevitable impurities contained in the sintered body is
300 ppm or less, and the flatness of the surface of the sintered body is 5 μm
A conductive substrate for a drawing apparatus characterized by the following is provided.

If the aluminum compound is less than 0.1% by weight, sintering does not proceed, and a dense sintered body cannot be obtained. If the aluminum compound exceeds 10% by weight, it is difficult to densify, and the Young's modulus decreases. Preferably, 1.
0 to 3.0% by weight.

If the compound of the group IIa element and the group IIIa element is 0.1% by weight or less, sintering does not proceed, and if it exceeds 10% by weight, the Young's modulus decreases. Preferably, it is 0.1 to 1.0% by weight.

If the amount of the conductivity-imparting agent is less than 0.5% by weight, the conductivity required as a conductive substrate for a drawing apparatus is not provided. If the amount exceeds 10% by weight, densification becomes difficult and the Young's modulus decreases. Preferably, it is 3.0 to 6.0% by weight.

If the content of SiC is less than 90% by weight, the sinterability is poor and the Young's modulus is reduced.

If the content of Fe in the sintered body exceeds 300 ppm, the magnetic flux density exceeds 0.05 mG and cannot be used as a conductive substrate for a drawing apparatus. Preferably it is 250 ppm or less, more preferably 150 ppm or less.

If the surface degree of the sintered body surface is 5 μm or more, when forming a circuit while holding the mask, the projection position error on the mask becomes large, and the formation of a fine circuit is limited. Preferably it is 2 μm or less, more preferably 1 μm or less.

Examples of the conductivity-imparting agent include Ti, a group IVa element, a group Va element, a group VIa element or a carbide or nitride thereof, in addition to Ti.
One or more carbonitrides can be selected.

In addition to the compounds of the IIa group element and the IIIa group element, B, B ₄ C, C and the like can be used as a sintering aid.

Volume resistivity is 10 ³ Ω as a conductive substrate for drawing equipment.
・ It must be less than cm order. Preferably 5x
10 ² Ω · cm or less, more preferably 1~3x10 ^{2 Ω} · cm.

When used as a conductive substrate for a drawing apparatus, the magnetic flux density is 0.05 mG or less, preferably 0.02 mG or less, more preferably 0.01 mG or less.

The coefficient of thermal expansion is preferably 5 × 10 ⁻⁶ / ° C. or less as a conductive substrate for a drawing apparatus.

Young's modulus is 3x10 ⁶ kg / cm as a conductive substrate for drawing equipment.
² or more, preferably 4x10 ⁶ kg / cm ² or more.

The specific gravity is desired to be 4.0 or less as a conductive substrate for a drawing apparatus in comparison with the value of Young's modulus.

In the production of the conductive silicon carbide sintered body of the present invention, silicon carbide powder, aluminum compound powder, IIa
A powder of a compound of a Group III element and a Group IIIa element, and a mixed powder prepared with the above-described composition range of a conductivity-imparting agent, or a raw material powder in which the Fe content of the mixed powder is 300 ppm or less,
Alternatively, the mixed powder is subjected to a deironing treatment so as to have a concentration of 300 ppm or less, and then molded and fired in a non-oxidizing atmosphere. The atmosphere is controlled by Ar, He, Co gas or the like. At that time, the atmosphere is kept in equilibrium with carbon heated to 1800 ° C. or more, and the oxygen concentration is set to 10 ⁻¹³ atm or less. That is, the oxygen concentration
If it exceeds 10 ^-13 atm, conductivity becomes insufficient and 10 ³ Ωcm
The following body specific resistance cannot be obtained.

The firing temperature is desirably set to 1800 to 2100 ° C.

Further, the silicon carbide powder used may be either α-type or β-type, and α-type is preferred from the viewpoint of economy.
As the firing method, a known method can be used, except that the atmosphere is set to the above conditions. For example, any of a non-pressure firing method, a hot press method, a gas pressure firing method, and a hot isostatic press method can be used. It may be.

Further, according to the present invention, one or more of the aluminum compound, the compound of the group IIa element and the compound of the group IIIa element is used.
A conductive Si ₃ N ₄ sintered body comprising 0.1 to 15% by weight, a conductivity imparting agent of 15 to 60% by weight, and a balance of silicon nitride (Si ₃ N ₄ ). Of the inevitable impurities contained in Fe
Is provided, and the flatness of the substrate surface is 5 μm or less.

If the total amount of the aluminum compound, the compound of the group IIa element and the compound of the group IIIa element is less than 0.1% by weight or more than 15% by weight, sintering is not sufficiently performed, and the Young's modulus decreases. Preferably, 1
~ 10% by weight.

If the conductivity-imparting agent is less than 15% by weight, the volume resistivity 10
^If it is too high, on the order of ⁴ Ω · cm or more, it cannot be used as a conductive substrate for a drawing apparatus. If it exceeds 60% by weight, the amount of silicon nitride decreases, so that sintering becomes insufficient and the Young's modulus decreases. Preferably 18-55% by weight, more preferably 20-
30% by weight.

If the content of Si ₃ N ₄ is less than 40% by weight, the sinterability is poor and the Young's modulus is reduced.

If the content of Fe in the sintered body exceeds 300 ppm, the density per hour exceeds 0.05 mG, and it cannot be used as a conductive substrate for a drawing apparatus. Preferably it is 250 ppm or less, more preferably 150 ppm or less.

If the flatness of the substrate surface is 5 μm or more, when forming a circuit while holding the mask, the projection position error on the mask becomes large, and the formation of a fine circuit is limited. Preferably it is 2 μm or less, more preferably 1 μm or less.

Examples of the conductivity-imparting agent include Ti, a group IVa element, a group Va element, a group VIa element or a carbide or nitride thereof, in addition to Ti.
One or more compounds such as carbonitrides can be selected.

Volume resistivity is 10 ³ Ω as a conductive substrate for drawing equipment.
・ It must be less than cm order. Preferably 5x
10 ² Ω · cm or less, more preferably 1~3x10 ^{2 Ω} · cm.

The magnetic flux density is 0.05 mG or less, preferably 0.02 mG or less, more preferably 0.01 mG, as a conductive substrate for a writing apparatus.

The coefficient of thermal expansion is 5x10 ^-6 /
° C.

Young's modulus is 2.8 × 10 ⁶ kg /
cm ² or more, preferably 3.0 × 10 ⁶ kg / cm ² or more.

The specific gravity is desired to be 3.3 or less as a conductive substrate for a drawing apparatus in comparison with the value of Young's modulus.

In producing the conductive silicon nitride sintered body of the present invention, a silicon nitride powder, an aluminum compound powder, a IIa element, a IIIa element compound powder, and a conductivity-imparting agent are prepared in the above composition range. Of the mixed powder
A raw material powder having an Fe content of 300 ppm or less is selected, or the mixed powder is subjected to a deironing treatment so as to have an Fe content of 300 ppm or less, molded and fired in a non-oxidizing atmosphere.
The atmosphere is controlled by Ar, He, Co gas or the like.

Note that the firing temperature is desirably set to 1800 to 2000 ° C.

In addition, as the firing method, a known method can be used, except that the atmosphere is set to the above conditions, and examples thereof include a non-pressure firing method, a hot press method, a gas pressure firing method, and a hot isostatic pressing method. Any of these may be used.

Example 1 Powder of an aluminum compound, powder of a compound of a group IIa element and a compound of a group IIIa element, and a conductivity-imparting agent were prepared in α-type SiC having a specific surface area of 15 m ² / g in proportions shown in Table 1. The mixed powder obtained is molded into a powder having a Fe content of 300 ppm or less in the mixed powder, or molded after de-ironing so as to be 300 ppm or less at 1800 to 2100 ° C. in a non-oxidizing atmosphere after molding. Fired.

The characteristics of the obtained sintered body were measured as follows.

To measure the content of magnetic metal in the sintered body, each sample was mixed with sodium carbonate and boric acid, melted in a platinum crucible, dissolved in hydrochloric acid and pure water, and the magnetic metal in this solution was subjected to ICP.
It was quantified by measuring with an emission spectrometer.

The magnetic flux density was measured by an analog magnetic field measuring device. However, the measurement performance is 0.1mG (milligauss) or more,
The measurement was performed with a scale of less than mG.

The volume resistivity was measured using a digital multimeter at room temperature after baking silver paste on both sides of a disk having a diameter of 10 mm and a thickness of 5 mm.

The flatness of the substrate surface is determined by the average surface roughness Ra after scanning multiple straight lines on the entire surface required for using the substrate using a contact surface roughness meter.
I asked.

The coefficient of thermal expansion was measured by a TMA thermal expansion meter, the Young's modulus was measured by an ultrasonic velocity measurement method, and the specific gravity was measured by an Archimedes method.

 The results are shown in Table 1.

As can be seen from Table 1, the aluminum compound
0.1 to 10% by weight of a compound of a group IIa element and a group IIIa element
Samples No. 1, 6, 7, 1 in which the number of seeds is out of the range of 0.1 to 10% by weight
All of 2, 15, and 21 are insufficiently densified, and have a low Young's modulus.

Sample No. 22 in which the conductivity-imparting agent was less than 0.5% by weight was used.
Has a high volume resistivity of 2.7 × 10 ⁷ Ω · mm, which does not meet the purpose of the present invention. In Sample No. 29 exceeding 10% by weight, densification is not promoted and Young's modulus is lowered.

Further, Sample No. 30 in which the Fe content in the SiC crystal exceeds 300 ppm has a high magnetic flux density of 0.08 mG, which is not suitable for the purpose of the present invention.

On the other hand, Sample Nos. 2 to 5 and 8 within the scope of the present invention
For ~ 11, 13, 14, 16-20, 23-28 and 31-36,
Characteristics required as a conductive substrate for a drawing apparatus of the present invention, that is, the magnetic flux density is 0.05 mG or less, the coefficient of thermal expansion is 5 × 10 ^-6 / ° C. or less, the Young's modulus is 3 × 10 ⁶ kg / cm ² or more, the volume resistivity is 10 ³ Ω
-It turns out that the order of cm or less is satisfied.

Next, using the same sample as the sample No. 9 shown in Table 1,
A conductive substrate for a drawing apparatus as a mask holder shown in FIG. 1 was prepared. The required surface of this mask holder is
Polished to achieve the flatness shown in the table, built into the actual drawing device, held the mask by this, electron beam 40 mm / s
The projection position error at the time of moving at the speed of was observed with an optical microscope, and the value of this error was evaluated.

As understood from Table 2, the sample No. 37 having a surface roughness of 10 μm cannot be used because the projection position error is as large as 0.6 μm and exceeds the required circuit pattern interval (0.5 μm).

On the other hand, sample No. 38 39, 40 with flatness of 5 μm or less
Was 0.3 μm or less, indicating no problem.

Example 2 A powder of an aluminum compound, a powder of a compound of a Group IIa element, a powder of a compound of a Group IIIa element, and a conductivity-imparting agent were added to Si ₃ N ₄ having a specific surface area of 6 m ² / g in proportions shown in Table 3. The prepared mixed powder is
The mixed powder having a Fe content of 300 ppm or less was molded, or the Fe in the mixed powder was subjected to a deironing treatment, molded, and fired at 1800 to 2000 ° C. in a non-oxidizing atmosphere.

 The following properties were measured for the obtained fired body.

The content of the magnetic metal in the sintered body was determined by mixing sodium carbonate and boric acid in the sample, melting the mixture in a platinum crucible, dissolving it in hydrochloric acid and pure, and then measuring the Fe content of the magnetic metal in this solution. It was quantified by measurement with an ICP emission spectrometer.

The magnetic flux density was measured by an analog magnetic field measuring device. However, the measurement performance was 0.1 mG or more, but 0.1 mG or less was measured with an enlarged scale. Volume resistivity is 10mm in diameter,
After baking silver paste on both sides of a 5 mm thick disk, measurement was performed at room temperature with a digital multimeter.

For the flatness of the substrate surface, the average surface roughness Ra after scanning a plurality of straight lines on the surface required for use of the substrate by a contact surface roughness meter was obtained.

The coefficient of thermal expansion was measured by a TMA thermal expansion meter, the Young's modulus was measured by an ultrasonic velocity measurement method, and the specific gravity was measured by an Archimedes method.

 The results are shown in Table 3.

As can be seen from Table 3, aluminum compounds,
Samples Nos. 1 and 11 in which the total amount of one or more of the compounds of Group IIa elements and Group IIIa elements is out of the range of 0.1 to 15% by weight are insufficiently sintered, and the above measurement cannot be performed. Was. Sample No. 1 in which the conductivity-imparting agent was out of the range of 15 to 60% by weight.
It was found that 2, 13, 14, 20, 21 and 22 had a volume resistivity of 10 ⁴ Ω · cm or more or could not be used due to insufficient sintering or a low Young's modulus. Furthermore, among the unavoidable impurities contained in the sintered body, the content of Fe is 300 ppm.
Sample No. 28 described above has a high magnetic flux density of 0.09 mG and cannot be used as a conductive substrate for a writing apparatus.

On the other hand, Sample Nos. 2 to 10, 15 to 1 within the scope of the present invention
9, 23 to 27 and 29 to 36, properties required as a conductive substrate for a drawing apparatus of the present invention, that is, the magnetic flux density is 0.05 mG
Below, thermal expansion coefficient 6.0x10 ^-6 / ℃ or less, Young's modulus 2.8x1
0 ⁶ kg / cm ² or more, a volume resistivity of it can be seen that satisfies the following 10 ³ Ω · cm order.

Next, using the same material as the sample No. 8 shown in FIG.
The surface of the mask holder shown in FIG. 1 was polished so as to have the flatness shown in Table 4, incorporated into an actual drawing apparatus, and the electron beam was moved at a speed of 40 mm / s while holding the mask. The projection position error at the time is measured, and this error value is
It is shown in the table.

As understood from Table 4, the sample No. 36 having a flatness of 10 μm has a large projection position error of 0.7 μm and cannot be used because the required circuit pattern interval exceeds 0.5 μm. Sample No. 3 with flatness of 5 μm or less
Samples of 8, 39 and 40 have a size of 0.3 μm or less, indicating that there is no problem.

〔The invention's effect〕

As described above, in the present invention, the composition of SiC or Si ₃ N ₄ is set in a predetermined range, the Fe content of the magnetic metal that is an unavoidable impurity in the sintered body is 300 ppm or less, and the volume resistivity is
10 ³ Ω · cm or less and the flatness of this sintered body is 5μ
m or less, the thermal expansion due to the ambient temperature is less affected, the deformation of the substrate is less likely to occur, and the conductive substrate for a drawing apparatus having a smaller specific gravity, the magnetic density is 0.05 m
It is possible to provide an excellent conductive substrate for a drawing apparatus having a projection position error of 0.5 μm or less and a projection error of 0.5 μm or less.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a drawing apparatus using the material of the present invention. 1. XY table 2. Mask holder 3. Mask / reticle substrate 4. Electron beam emitting device

Claims (2)

(57) [Claims] (1) An aluminum compound containing 0.1 to 10% by weight of II
A conductive SiC sintered body comprising 0.1 to 10% by weight of at least one compound of a group a element and III group a element, 0.5 to 10% by weight of a conductivity-imparting agent, and silicon carbide (SiC) as a balance. Therefore, the content of Fe among the inevitable impurities contained in this sintered body is 300p
pm or less, and the flatness of the surface of the sintered body is 5 μm or less. 2. A compound of one or more of compounds of aluminum element, group IIa element and group IIIa element having a total amount of 0.1 to 15%.
Wt.%, The conductivity-imparting agent is 15-60 wt.%, And the balance is silicon nitride (Si ₃ N ₄ ), which is a conductive Si ₃ N ₄ sintered body which is inevitably contained in the sintered body. Fe content of impurities
300 ppm or less, and the flatness of the surface of the sintered body is 5 μm
A conductive substrate for a drawing apparatus, characterized in that: