JP2848416B2 - Vapor phase growth equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for producing a CVD (vapor phase) film.

As VLSIs become more highly integrated, the demand for ultra-fine processing is becoming more and more severe.

For example, when a CVD film is used as a membrane for an X-ray exposure mask, the distortion of the mask pattern must be suppressed to at least 0.05 μm or less in order to form a pattern having a line width of 0.5 μm.

[Conventional technology]

In a conventional induction heating type CVD film manufacturing system, Si
When a disk-shaped susceptor is used as a susceptor as a dielectric heating body for holding a wafer, it depends on the flow rate and direction of the reaction gas or the size of the susceptor. The peripheral portion has a unique property that the temperature is higher, and as a result, the CVD deposition rate in the peripheral portion is higher than that in the central portion, so that a film thickness distribution occurs in the wafer. For example, S prepared by this method as a CVD film
When iC is used as a membrane for an X-ray exposure mask,
If the SiC film has an in-plane distribution, stress distortion occurs in the absorber during bag etching or etching of the absorber. Therefore, the distortion of the target mask itself is set to 0.
It is impossible to keep the thickness below 05 μm.

[Problems to be solved by the invention]

In order to reduce this distortion (temperature gradient), a necessary condition is that the in-plane distribution (uneven thickness) of the film is ± 3% or less.

The reason why such a film thickness distribution occurs is that a temperature distribution is generated between the central portion and the peripheral portion of the susceptor as described above. Therefore, by improving this temperature distribution, the in-plane distribution of the film thickness can be improved.

SUMMARY OF THE INVENTION An object of the present invention is to provide a temperature distribution of a susceptor with a gradient in a direction to offset the film thickness distribution, so that the film thickness becomes uniform.

[Means for solving the problem]

To achieve the above object, according to the present invention, in an apparatus for growing a CVD film by induction heating on a wafer supported by a susceptor, the contact heat transfer area between the susceptor and the wafer is large at the center of the susceptor. , And a susceptor that becomes smaller toward the periphery.

Since the wafer is generally in a disk shape, in this case, the susceptor is also formed in a disk shape. A plurality of concentric grooves are formed on a susceptor (disk) as a means for imparting the above-described predetermined characteristics to the contact heat transfer area. The width of these grooves increases from the center to the periphery (claim 2).

Also, separately from this, a spiral groove is formed on the disk,
The pitch of the grooves may be increased from the center to the periphery (claim 3).

Further, it is also possible to form porosity on the disk and to increase the arrangement density of the porosity from the center to the periphery of the disk (claim 4).

(Operation)

As described above, the temperature of the susceptor is higher in the peripheral part than in the central part. Since the thermal efficiency is reduced, the temperature distribution of the susceptor can be made substantially uniform.

A plurality of concentric grooves formed on the disk of the susceptor have a groove width increasing from the center to the periphery, so that the peripheral area has a smaller contact area with the wafer, and therefore, the heat transfer efficiency is smaller. .

The same is true for spiral grooves as long as the groove pitch increases from the center to the periphery.

When a hole is formed on a disk, the contact density decreases as the arrangement density (number) of the holes increases from the center to the periphery of the disk.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 5 shows the basic structure of a vapor phase growth (epitaxial) apparatus. A wafer (Si wafer) 11 on which a CVD film is to be manufactured is held on a susceptor 13. The illustrated embodiment shows a case of a reactor in which a large number of susceptors 13 are arranged in a furnace core tube 10 and a large number of susceptors 13 are simultaneously processed. What is necessary is just to attach a single wafer 11.

The susceptor 13 supporting the wafer 11 on both sides is fixed and held on a common susceptor support 17. Reference numerals 15 and 19 denote a heater and an exhaust port, respectively, disposed around the furnace core tube 10.
Heat from the heater 15 is transmitted to the wafer 11 via a susceptor 13 as an induction heat transfer means.

Wafer 11 is generally substantially circular, and thus susceptor 13
Also generally shows a circular shape (disk), but the shape is not particularly limited in the present invention.

Now, in such a vapor phase growth apparatus, as described above,
The susceptor 13 has a unique characteristic that the temperature gradient is not uniform and the temperature of the peripheral portion becomes higher than that of the central portion. As a result, there is a problem that the thickness of the CVD film grown on the wafer in a vapor phase becomes uneven.

Therefore, according to the present invention, the contact heat transfer area between the susceptor 13 and the wafer 11 is large at the center and becomes small toward the periphery. That is, the susceptor 13 and the wafer
This is based on the idea of intentionally providing a reverse heat gradient in a direction that offsets the temperature gradient inherent in the susceptor 13 to the heat transfer area in contact with the susceptor 13.

To that end, according to the embodiment shown in FIGS.
A plurality of concentric grooves (non-contact portions) 31 are formed in the susceptor 13, and the width of the grooves is smaller in the center groove and larger in the peripheral groove. That is, the contact area between the susceptor 13 and the wafer 11 is smaller toward the periphery. Although only three grooves are shown in FIGS. 1 and 2 for simplicity of illustration, in practice, control accuracy can be increased by arranging a large number of grooves with slightly different groove widths.

In the embodiment shown in FIGS. 1 and 2, it can be recognized that a plurality of the same annular projections are arranged on the susceptor so that the pitch is gradually increased. Alternatively, the arrangement pitch may be the same, and the width of the protrusion may be reduced toward the periphery.

The wafer 11 is generally simply held by claws 21 provided on the susceptor 13 as shown in FIG.
There is no need for a means to adhere to 13.

FIG. 3 shows a modified embodiment of FIG. 2. In FIG. 3, a spiral groove (or spiral projection) 33 is formed in the susceptor 13 instead of the annular groove (or annular projection). The pitch of the spiral groove 33 becomes denser toward the periphery. Alternatively, the same object can be achieved even if the groove width of the spiral groove 33 is increased toward the periphery.

FIG. 4 shows still another embodiment, in which a large number of openings 35 are formed in the susceptor 13, and the arrangement pitch is sparse at the center and closer to the circumference. By doing so, the contact heating area at the center becomes relatively large, and the same object can be achieved.

6 to 8 show a reference example, in which FIG.
The susceptor 14 is formed of a material having a dielectric constant as shown in FIG. That is, the dielectric constant (insulating property) of the susceptor 14 has the smallest characteristic curve at the central portion and a larger characteristic curve at the peripheral portion.

By doing so, the electric heating efficiency of the susceptor becomes smaller toward the periphery, so that the object can be similarly achieved.

FIG. 8 shows a specific method for realizing the dielectric constant as shown in FIG. Generally, a susceptor as a dielectric heating body is formed of carbon. In FIG. 8, both sides of carbon 41 are covered with a refractory insulating material 43 such as quartz or ceramic. The carbon located inside has a shape like a convex lens whose center is thick and whose thickness is reduced toward the periphery. In other words, the insulating material 43 such as quartz located on both sides of the carbon is thin at the center and increases in thickness toward the periphery. As a result, a dielectric constant characteristic as shown in FIG. 7 is obtained.

〔The invention's effect〕

As described above, since the temperature of the susceptor is higher in the peripheral part than in the central part, the contact heat transfer area between the susceptor and the wafer is made larger at the center of the susceptor and becomes smaller toward the periphery according to the present invention. By doing so, the heat transfer efficiency decreases in the peripheral portion, and the temperature distribution of the susceptor can be made substantially uniform.

[Brief description of the drawings]

1 is a cross-sectional side view of a susceptor to which a wafer is mounted according to an embodiment of the present invention, FIG. 2 is a front view of the susceptor shown in FIG. 1, and FIGS. 3 and 4 show two modified embodiments of the susceptor. FIG. 5 is a diagram showing a basic structure of a vapor phase growth apparatus, FIG. 6 is a diagram showing a reference example, FIG. 7 is a diagram showing a dielectric constant characteristic of the susceptor shown in FIG. FIG. 8 is a diagram showing the internal structure of the susceptor shown in FIG. 11 ... wafer, 13,14 ... susceptor, 31,33 ... groove.

Claims (4)

(57) [Claims] A wafer (1) supported on a susceptor (13, 14).
1) An apparatus for growing a CVD film by induction heating, comprising a susceptor in which the heat transfer area of contact between the susceptor and the wafer is large at the center of the susceptor and decreases toward the periphery. apparatus. 2. The susceptor (13) has a disk shape, and a plurality of concentric grooves (31) are formed on the disk, and the width of these grooves is from the center to the periphery. The vapor phase growth apparatus according to claim 1, wherein the apparatus is larger. 3. The susceptor has the shape of a disk, and spiral grooves (33) are formed on the disk, and the pitch of the grooves increases from the center toward the periphery. The vapor phase growth apparatus according to claim 1, wherein: 4. The susceptor has the shape of a disk, and a plurality of holes (35) are formed on the disk, and the arrangement density of the holes increases from the center to the periphery of the disk. The vapor phase growth apparatus according to claim 1, wherein: