JPH0360014A - Conductive base substance for picturing device - Google Patents

Abstract

PURPOSE:To suppress the effect of thermal expansion due to ambient temperature, to retard deformation of a base body, and to lower specific gravity by decreasing Fe content within a sintered body below a specific level, and specifying the flantness of the surface of the sintered body. CONSTITUTION:The mixed powder, being made up such that the powder of aluminum compounds is 0.1-10wt.%, the powder of the compounds of group II a elements and group III a elements is 0.1-10wt.%, the conductivity giving agent is 0.5-10wt.%, and the remainder is alpha type SiC, is molded so that the Fe content within this mixed powder is 300ppm or less, or it is molded after being deironed so that the Fe content is 300ppm or less, and then it is baked in nonoxidizing atmosphere. And the flatness of the surface of the sintered base body is set to 5mum.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a material for a drawing device for creating fine circuits on a mask/reticle substrate using an electron beam or the like, such as a mask that holds a mask/reticle substrate. The present invention relates to a non-magnetic and conductive substrate such as a holder and an X-Y table for moving the holder in the vertical and horizontal directions.

[Conventional technology]

FIG. 1 is a schematic explanatory diagram of a conventional drawing apparatus, in which a mask/reticle substrate 3 is elastically held on a mask holder 2 fixed on an X-Y table 1. While moving the X-Y table 1 in the X or Y direction, a circuit is formed on the mask/reticle substrate 3 by an electron beam emitted from an electron beam emitting device 4 above. .

The materials of the X-Y table 1, mask holder 2, etc. are required to be non-magnetic because if they are magnetic, they will have a negative effect on the straightness of the electron beam and will significantly reduce the writing accuracy. On the other hand, in order to release static electricity generated on the mask reticle substrate due to electron beam writing, it is required that the mask reticle has conductivity with a volume resistivity of 10'Ω·cn+ order or less. Conventionally, metals such as beryllium copper (BeCu) and phosphate steel have been used as base materials satisfying such characteristics.

[Problem to be solved by the invention]

However, such metals have a coefficient of thermal expansion of 12xl
It is large, more than O-'/"c, and when forming a circuit, the circuit projection position is likely to shift due to the ambient temperature, and there is a limit to the formation of fine circuits. Also, the Young's modulus is 2xlO&kg/cm
Since the specific gravity is as low as 8 or more, the rigidity is low and the base body is easily deformed.Furthermore, since the specific gravity is as high as 8 or more, there is a problem that it is not possible to reduce the weight so that, for example, the X-Y stage can operate easily.

Further, with the recent trend toward higher circuit densities, there has been an extremely strict requirement that the width of the circuit pattern on the mask be 0.5 μm or less, and this is difficult to achieve with the base material.

Therefore, in order to solve the above problem, the inventor of the present application attempted to use conductive ceramics as a base material that satisfies the above characteristics. Some conductive ceramics such as Si, N4, and SiC have a thermal expansion coefficient of 6xlO'/'C or less, a Young's modulus of 3xlO'kg/cm' or more, and a specific gravity of 4.0 or less, which solves the above problems. This is because there are some properties that allow it.

However, raw material powder for such ceramics usually inevitably contains magnetic metals such as Fe, and if the content of this magnetic metal is high, the magnetic flux density in the sintered body cannot be sufficiently reduced. When used as a conductive substrate material for a writing device, it has a negative effect on the straightness of the electron beam. In addition, the flatness of the surface of the ceramic sintered body is usually 10IJl11
Due to the above roughness, when forming a circuit by holding the mask, the error in the projection position on the mask exceeds 0.5 μm, and there is a limit to the formation of a circuit with a fine width.

[Purpose of the invention]

In the present invention, the conductive base is less affected by thermal expansion due to ambient temperature, hardly deforms the base, and has a low specific gravity, and has conductivity with a volume resistivity of 10' Ω·cra order or less. , and the magnetic flux density is 0.05 mG
An object of the present invention is to provide a conductive substrate for a drawing device in which the flatness of the surface of the sintered body is 5 μm or less.

[Means to solve the problem]

Therefore, the inventor of the present application set the composition ratio of the conductive ceramic within a certain range, and reduced the content of Fe, which is a magnetic metal, in this sintered body to a predetermined amount or less, and reduced the magnetic flux density to 0.0.
The above-mentioned problems could be solved by making the flatness of the surface of this sintered body 5 μm or less while making it sufficiently small to 5 mG or less.

According to the present invention, the aluminum compound is 0.1 to 10% by weight, one or more compounds of Ua group elements and IIIa group elements are 0.1 to 10% by weight, and the conductivity imparting agent is 0.5 to 10% by weight. %, the balance is conductive Si consisting of silicon carbide (SiC)
A C-based sintered body, characterized in that the content of Fe among 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 or less. A conductive substrate for a drawing device is provided.

If the aluminum compound content is less than 0.1% by weight, sintering will not proceed and a dense sintered body will not be obtained, and if it exceeds 10 weight itx, densification will be difficult and the Young's modulus will decrease. Preferably it is 1.0 to 3.0% by weight.

If the amount of the compound of the Ua group element and the group (II) a group element is less than 0.1% by weight, sintering will not proceed, and if it exceeds 10 times Nz, the Young's modulus will decrease. Preferably, it is 0.1 to 1.0 weight2.

If the conductivity imparting agent is less than 0.5 weight tz, the conductivity necessary for a conductive substrate for a drawing device will not be imparted, and if it exceeds 1 x 1 x, it will be difficult to densify and the Young's modulus will decrease. Preferably it is 3.0 to 6.0% by weight.

When SiC is less than 90 Nz, sinterability is poor and Young's modulus is reduced.

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

If the flatness of the surface of the sintered body is 5 μm or more, when holding the mask to form a circuit, the error in the projection position on the mask becomes large, and there is a limit to the formation of fine circuits. Preferably it is 2 μm or less, more preferably 1 μm or less.

As the conductivity imparting agent, in addition to Ti, one or more of IVa group elements, Va group elements, and VIa group elements, or their carbides, nitrides, and carbonitrides can be selected.

In addition to the compounds of the Ua group elements and IIIa group elements, B, B4. C, C, etc. can also be used.

The volume resistivity is 103Ω as a conductive substrate for a drawing device.
- It is necessary to be on the order of cm or less.

Preferably it is 5×10”Ω·cm or less, more preferably 1 to 3×10”Ω·cm.

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

The coefficient of thermal expansion is preferably 5xlO-h/'c or less as a conductive substrate for a drawing device.

Young's modulus is 3xlO6k as a conductive substrate for drawing equipment.
g/c- or more, preferably 4xlO6 kg/cm'' or more.

When compared with the value of Young's modulus, the specific gravity is desired to be 4.0 or less as a conductive substrate for a drawing device.

In manufacturing the conductive silicon carbide sintered body of the present invention, a silicon carbide powder bundle, an aluminum compound powder, a compound powder of an Na group element and an A group element, and a conductivity imparting agent are mixed in the above composition range. The prepared mixed powder is
A raw material powder having an e content of 300 ppm or less is selected, or the mixed powder is subjected to iron removal treatment so that the e content is 300 ppm or less, and then molded and fired in a non-oxidizing atmosphere. The atmosphere is controlled by Arz He, Co gas, etc., and at this time, the atmosphere is kept in equilibrium with carbon heated to 1800°C or higher, and the oxygen concentration is adjusted to 10-"a.
Make it below tm. That is, when the oxygen concentration is 10-"atI
If it exceeds ll, the conductivity will be insufficient and the resistance will be 103Ω・cm.
The following body specific resistance cannot be obtained.

Further, the firing temperature is desirably set at 1800 to 2100°C.

Furthermore, the silicon carbide powder bundle used may be either α-type or β-type, with α-type being preferred from the economic point of view. As for the firing method, except for setting the atmosphere to the above conditions,
Any known method may be used, such as a non-pressure firing method, a hot press method, a gas pressure firing method, or a hot isostatic pressing method.

Further, according to the present invention, one or more of the aluminum compound and the compound of the Ua group element and the IIIa group element is 0.1 to 15% by weight2. 15-60% by weight of conductivity imparting agent
, conductive Si3 with the remainder made of silicon nitride (SLN4)
A drawing characterized in that the N4-based sintered body has an Fe content of 300 ppm or less among the inevitable impurities contained in the sintered body, and the flatness of the base surface is 5 μm or less. A conductive substrate for a device is provided.

If the total amount of the aluminum compound, the IIa group element, and the I[la group element compound is less than 0.1 weight 2 or more than 15 weight 2, sufficient sintering will not occur and the Young's modulus will decrease.

Preferably, it is 1 to 10 weight2.

When the conductivity imparting agent is less than 15 weight X, the volume resistivity is 1
If the weight exceeds 60 Ω, the amount of silicon nitride decreases, resulting in insufficient sintering and a decrease in Young's modulus. Preferably it is 18 to 55% by weight1, more preferably 20 to 30% by weight2.

40 layers of Si3N4! If it is less than χ, sinterability will be poor and Young's modulus will decrease.

If the content of Fe in the sintered body exceeds 300 ppm, the hourly density exceeds Q,05 raG, and the sintered body cannot be used as a conductive substrate for a drawing device. Preferably 250 ppm or less,
More preferably it is 150 ppm or less.

If the flatness of the substrate surface is 5 μm or more, when a circuit is formed by holding a mask, the projection position error on the mask becomes large, and there is a limit to the formation of fine circuits. Preferably it is 2 μm or less, more preferably 1 μm or less.

As the conductivity imparting agent, in addition to Ti, one or more of IVa group elements, Va group elements, and VIa group elements alone or compounds thereof such as carbides, nitrides, carbonitrides, etc. can be selected. .

The volume resistivity is 103Ω as a conductive substrate for a drawing device.
- It is necessary to be on the order of cm or less.

Preferably it is 5 xlO"Ω·cm or less, more preferably 1 to 3 xlO"Ω·cm.

The magnetic flux density is 0.05 mG as a conductive substrate for drawing equipment.
It is preferably 0.02 mGG or less, more preferably 0.01 mGG or less.

The thermal expansion coefficient is 5xLO- as a conductive substrate for a drawing device.
'/''CC is below.

The Young's modulus is 2.8xlo as a conductive substrate for a drawing device.
'kg/c- or more, preferably 3. Oxlo6kg/c
- That's all.

When compared with the value of Young's modulus, the specific gravity is desired to be 3.3 or less as a conductive substrate for a drawing device.

In producing the conductive silicon nitride sintered body of the present invention, a mixture of silicon nitride powder, aluminum compound powder, Ua group element, IIIa group element compound powder, and conductivity imparting agent prepared within the above composition range is used. For the powder, select a raw powder whose mixed powder has a Pe content of 300 ppm or less, or select a raw material powder whose mixed powder has a Fe content of 300 ppm or less.
After de-iron treatment is performed so that the particle size is less than m, it is molded and fired in a non-oxidizing atmosphere. As for the atmosphere, Ars He...
Controlled by Co gas or the like.

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

In addition, as the firing method, other than setting the atmosphere to the above conditions, known methods are possible, such as non-pressure firing method, hot press method, gas pressure firing method, hot isostatic pressing method, etc. It may be any of the following.

[Example 1] A mixture of α-type SiC with a specific surface area of 15 n+”/g, powder of an aluminum compound, powder of a compound of a Ua group element and an I1la group element, and a conductivity imparting agent in the proportions shown in Table 1. powder, the Fe content of this mixed powder is 300 ppm
The following materials were molded into bottom shapes, or after being deironated to 300 pp- or less, and fired at 1800 to 2100 DEG C. in a non-oxidizing atmosphere after the bottom molding.

The following measurements were performed regarding the characteristics of the obtained sintered body.

To measure the content of magnetic metal in a sintered body, mix sodium carbonate and boric acid with each sample, melt it in a platinum crucible, dissolve it in hydrochloric acid and pure water, and then remove the magnetic metal in this solution by ICP.
It was quantified by measurement using an emission spectrometer.

The magnetic flux density was measured using an analog magnetic field measuring device.

However, although the measurement performance is 0.1 mG (milliGauss) or more, measurements were made with a magnification of 0.1 mG or less and a scale.

Measurement of volume resistivity was performed with a diameter of 10 mm and a thickness of 5III.
After baking the paste on both sides of the disk No. 11, measurements were taken using a digital multimeter at room temperature.

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

The thermal expansion coefficient was measured using a TMA thermal dilatometer, the Young's modulus was measured using an ultrasonic velocity measuring method, and the specific gravity was measured using an Archimedes method.

These results are shown in Table 1.

[Margin below]

As understood from Table 1, the argonium compound is 0
．． Sample No. 1.6.7.12.15.21 in which one or more of the group IIIa element and the compound of the group IIIa element was outside the range of 1 to 10% by weight and 0.1 to 10% by weight was not densified. is sufficient, and the Young's modulus is reduced.

In addition, sample No. in which the conductivity imparting agent is less than 0.5% by weight
, 22 has a high volume resistivity of 2.7xlO'Ω'mm, which is not suitable for the purpose of the present invention, and sample N exceeding 10% by weight.
In No. 0129, densification was not promoted and the Young's modulus was decreased.

Furthermore, sample No. 30, in which the Fe content in the SiC sintered body exceeds 300 ppm, has a high magnetic flux density of 0.08 IIG and is not suitable for the purpose of the present invention.

In contrast, samples Nos. 12 to 5, which are within the scope of the present invention.
8-11.13.14.16-20.23-28 and 3
Regarding Nos. 1 to 36, the characteristics necessary for the conductive substrate for the drawing device of the present invention are as follows: magnetic flux density is 0.05 mGC or less, thermal expansion coefficient is 5xlO-'/''C or less, and Young's modulus is 3xlO6kg/c- or more. , volume resistivity is 103Ω'
It can be seen that it satisfies the cm order or less.

Next, using the same material as sample No. 9 shown in Table 1,
A conductive substrate for a drawing device, which is a mask holder shown in FIG. 1, was prepared. The second surface of this mask holder that needs to be used
Polish it to the flatness shown in the table, install it in the actual lithography equipment, hold the mask, and beam the electron beam for 40m.
The projection position error when moving at a speed of m/s was observed using an optical microscope, and the value of this error was evaluated and shown in Table 2.

Table 2 As can be seen from Table 2, sample No. 37 with a flatness of 10 μm has a large projection position error of 0.6 μm, and the required circuit pattern spacing (0°5 μl 11
) and cannot be used.

In contrast, sample No. 3839 with a flatness of 5 μm or less
．． No. 40 had a diameter of 0.3 μm or less, and it was found that there was no problem.

[Example 2] Si, N, with a specific surface area of 6 m"7 g, powder of an aluminum compound, powder of a compound of a group IIa element, a compound of a group IIa element, and a conductivity imparting agent were prepared in the proportions shown in Table 3. The mixed powder obtained in the above step 5 is molded into a powder having a Fe content of 300 ppm or less, or the F in these mixed powders is
After iron removal treatment, molding was carried out in a non-oxidizing atmosphere at 1800 °C.
Calcined at ~2000°C.

The following characteristic measurements were performed on the obtained sintered body.

The content of magnetic metal in the sintered body is determined by mixing a sample with sodium carbonate and boric acid, melting it in a platinum crucible, dissolving it in hydrochloric acid and pure water, and then calculating the Fe content, which is a magnetic metal, in this solution. was measured and quantified using an ICP emission spectrometer.

The magnetic flux density was measured using an analog magnetic field measuring device.

However, the measurement performance was over 0.1 mG, but at 0.1 m
Measurements below G were enlarged and marked with a scale. The volume resistivity was measured using a digital multimeter at room temperature after baking silver paste on both sides of a disk with a diameter of 10 m5+ and a thickness of 5 mm.

The flatness of the surface of the substrate was determined by scanning a plurality of straight lines on the surface of the substrate to be used using a contact type surface roughness meter, and then determining the average surface roughness Ra.

The thermal expansion coefficient was measured using a TMA thermal dilatometer, the Young's modulus was measured using an ultrasonic velocity measuring method, and the specific gravity was measured using an Archimedes method.

These results are shown in Table 3.

[Margin below]

As understood from Table 3, aluminum compounds, U
Sample No. 1 in which the total amount of one or more compounds of group a elements and group IIIa elements is outside the range of 0.1 to 15 times Iχ
and No. 11 were insufficiently sintered, and the above measurements could not be performed. In addition, samples No. 12, 13, 14, 20, 21 and 22 in which the conductivity imparting agent was outside the range of 15 to 60 weight 2 had a volume resistivity of 10'Ω・cm or more or were not sintered properly. Otherwise, it was found that the Young's modulus decreased and it could not be used. Furthermore, sample No. 28, in which the content of Fe among the inevitable impurities contained in the sintered body is 300 ppm or more, has a magnetic flux density of 0.09 IIIG.
It can be seen that this is so high that it cannot be used as a conductive substrate for a drawing device.

In contrast, samples No. 2 to 10.15 within the scope of the present invention
〜19. Regarding 23 to 27 and 29 to 36, the characteristics necessary for the conductive substrate for the gate drawing device of the present invention, that is, the magnetic flux density is 0.05 mG or less, and the thermal expansion coefficient is 6.0xlO
-'/℃ or less, Young's modulus is 2.8xlO' kg/c-
From the above, it can be seen that the volume resistivity satisfies the order of 10'J, Ω·am or less.

Next, using the same material as Sample No. 8 shown in Table 3, the surface of the mask holder shown in Fig. 1 was polished to the flatness shown in Table 4, and incorporated into the actual lithography equipment. , hold the mask and apply the electron beam to 4On+m/
The projection position error when moving at a speed of s was measured, and the error values are shown in Table 4.

Table 4 As can be understood from Table 4, sample No. 37 with a flatness of 10 μm had a large projection position error of 0.7 μm, and was not used because the required circuit pattern spacing (exceeding 0.5 μm) On the other hand, it can be seen that the flatness of sample No. 38, 39, 40 whose flatness is 5 μm or less is 0.3 μm or less and there is no problem.

〔Effect of the invention〕

As mentioned above, in the present invention, SiC or Si3N
The composition of step 4 is set within a predetermined range, and the Fe content of the magnetic metal, which is an inevitable impurity in the sintered body, is set to 300 ppm or less.
By setting the volume resistivity to 103Ω・cm or less and the flatness of this sintered body to 5 μm or less, the effect of thermal expansion due to ambient temperature is small, the base body is hard to deform, and the drawing device has a small specific gravity. It is possible to provide an excellent conductive substrate for use in drawing devices, which has a magnetic density of 0.05 m Gauss or less and a projection position error of 0.5 μm or less.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of a drawing apparatus in which the material of the present invention is used. l... X-Y table 2... Mask holder 3... Mask/reticle board 4... Electron beam emitting device

Claims (2)

[Claims] (1) Aluminum compound is 0.1 to 10% by weight, IIa
One or more compounds of group elements and group IIIa elements are 0.1 to 1
A conductive SiC sintered body consisting of 0% by weight, 0.5 to 10% by weight of a conductivity-imparting agent, and the balance being silicon carbide (SiC), and of the inevitable impurities contained in this sintered body. F
A conductive substrate for a drawing device, characterized in that the content of e is 300 ppm or less, and the flatness of the surface of the sintered body is 5 μm or less. (2) The total amount of one or more compounds of aluminum element, group IIa element, and group IIIa element is 0.1 to 15% by weight, the conductivity imparting agent is 15 to 60% by weight, and the balance is silicon nitride. Conductive Si_3N_4 consisting of (Si_3N_4)
A drawing characterized in that the sintered body is a quality sintered body, the content of Fe among 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 or less. Conductive substrate for devices.