JPH0787180B2 - Vapor growth method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] The present invention is a method generally called organometallic pyrolysis vapor phase epitaxy and suitable for vapor phase growth of a compound semiconductor film. In a susceptor having a revolving rotary table and a revolving rotary table for revolving the revolving rotary table on the same plane, a wafer is placed on each of the revolving rotary tables, and the susceptor is high-frequency heated and bypassed with a source gas. H ₂ as a carrier gas is caused to flow in a direction parallel to the rotation and revolution planes of the susceptor, and the respective semiconductor wafers are rotated and revolved so that the position of each wafer that is rotated is switched between upstream and downstream of the gas flow. The film is made to undergo metalorganic pyrolysis vapor phase growth so that not only compound semiconductor integrated circuit devices, but also HEMTs and heterojunction high-speed semiconductor devices can be mass-produced. That.

[Industrial application field]

The present invention relates to a metal organic thermal decomposition vapor phase growth method capable of growing a compound semiconductor film having a uniform film thickness.

[Conventional technology]

Metalorganics chemical vap
Our deposition: MOCVD method is superior in the uniformity of the grown film thickness compared to liquid phase epitaxial growth (1iquid phase epitaxy: LPE) method, and it is a semiconductor wafer compared to molecular beam epitaxy (MBE) method. It is said to be excellent in mass productivity such as batch processing.

When growing a compound semiconductor film by this MOCVD method,
The semiconductor wafer may be held stationary, or may be rotated or revolved.

(Problems to be Solved by the Invention) By the way, although the film thickness of the compound semiconductor film grown by the MOCVD method is excellent in terms of uniformity, it is not possible to manufacture an integrated circuit device using it. Has not reached

It is generally known that when a semiconductor film is grown, the film thickness becomes more uniform when the semiconductor wafer is rotated or revolved than when the semiconductor wafer is kept stationary.

From this, it is easily conjectured that if the semiconductor film is grown while rotating and revolving the semiconductor wafer, the uniformity of the film thickness will be improved. It has not been.

The biggest reason is that the mechanism for rotating and revolving becomes complicated, and the frictional part increases due to the complexity of the mechanism. There is a possibility that it may be taken in as a pollutant substance into the growing semiconductor film.

As described above, the risk of contaminants being taken into the growing semiconductor film is particularly remarkable when the MOCVD method is performed.

That is, when the MOCVD method is applied to grow a GaAs film, for example, the temperature of the semiconductor wafer is set to about 600 to 700.
It is necessary to set the temperature to about [° C.], and to grow the AlGaAs film, it is necessary to set the temperature to about 700 to 800 [° C.]. Therefore, the susceptor that holds the semiconductor wafer in the MOCVD apparatus must be made of a material that can withstand the same temperature, and this susceptor is a dielectric material because it is heated at high frequency. It is necessary. As a material satisfying such a condition, there has been conventionally used carbon which is often used as a susceptor and which is conventionally heated. However, it is difficult to imagine that when the mechanism that allows the semiconductor wafer to rotate and revolve as described above is formed from carbon as a material, the generated carbon fine powder will be taken into the semiconductor film as a contaminant. Absent. In the case of realizing either one of rotation and revolution of a semiconductor wafer, as in the apparatus for performing the MOCVD method according to the conventional technique, simply use one rotary shaft on the rotary table on which the semiconductor wafer is mounted. Since it can be installed, its structure is completely incomparable to the one in which the rotation and the revolution are simultaneously performed, and therefore, the generation of pollutants need not be considered.

The present invention is a method for producing a MO wafer while rotating and revolving a semiconductor wafer.
By applying a CVD method to grow a semiconductor film, it is possible to obtain a film thickness uniformity that has never been possible in the past.

[Means for solving problems]

In the vapor phase epitaxy method according to the present invention, each rotation for rotation in a susceptor having a plurality of rotation rotary tables made of carbon and a rotation rotary table for revolving the rotation rotary tables on the same plane. Place the wafer on the table and heat the susceptor at high frequency while bypassing the carrier gas with the source gas.
H ₂ as a gas is caused to flow in a direction parallel to the rotation and revolution planes of the susceptor, the wafer is rotated and revolved, and the position of each wafer that rotates is exchanged between the upstream and downstream of the gas flow while the organic compound semiconductor film is formed. Metal pyrolysis vapor growth is attempted.

[Action]

According to the above means, the uniformity of the film thickness in the grown compound semiconductor film is extremely high, for example ± 1.
It was possible to suppress it within 5 [%], and there was no contamination due to the feared susceptor material.

〔Example〕

FIG. 1 is an explanatory view of the essential parts of a MOCVD apparatus for carrying out the vapor phase growth method of the present invention, and FIG. 2 is a cross-sectional explanatory view of the essential parts thereof.

In each figure, 1 is a reaction tube made of, for example, quartz, 1A is a reaction gas supply tube, 1B is an exhaust tube, 2 is a high frequency heating coil, 3 is a semiconductor wafer susceptor, 4 is an orbiting table for revolution,
Reference numeral 5 is a rotation rotary table, 6 is a rotation / revolution driving rod having gear teeth cut at the tip thereof, 7 is an electric motor, and 8 is a semiconductor wafer mounted on the rotation rotary table.

A case of growing a GaAs crystal film or an AlGaAs crystal film using this MOCVD apparatus will be described.

Three GaAs wafers each having a diameter of about 5 cm (2 [inch]) are placed on the three rotation rotary tables 5 shown in FIG.

Epitaxial growth is performed while rotating the orbiting rotary table 4 at a rate of about 20 [times] per 1 minute, and rotating the rotary table 5 at a rate of several tens of times per 1 minute.

Other conditions for performing this epitaxial growth are as follows.

(1) H ₂ as bypass carrier gas 20 [l / min]
Flow at a rate of.

(2) Trimethylgallium (TMG: (CH ₃ ) ₃ Ga) whose temperature is maintained at 0 [° C] is flowed at a rate of 25 [cc / min].

(3) 25% 6 [%] arsine (AsH ₃ ) based on H ₂
Flow at a rate of 0 [cc / min].

(4) The growth temperature was 650 ° C.

The V / III ratio in the GaAs crystal film epitaxially grown in this way was 6.6, and the variation in film thickness within the entire surface of the wafer was within ± 1.5%.

In addition, in order to grow an AlGaAs crystal film, in addition to the above-mentioned conditions, trimethylaluminum (TMA: (CH ₃ ) ₃ Al) maintained at a temperature of 16 ° C was used at 16 [cc / min]. It is good to flow at the ratio of.

In addition, the conventional MOCVD method is applied to grow the AlGaAs crystal film,
In some cases, it was reported that the data obtained was about ± 1.5% of the film thickness variation within the wafer surface.
This is measured in the gas flow direction and does not relate to the entire surface of the wafer as in the present invention. By the way,
When the conventional MOCVD method is applied, the uniformity of the film thickness on the entire surface of the wafer is ± several [%] in the best condition, and usually only ± 10 [%].

Here, the mechanism for rotating and revolving the semiconductor wafer will be described in detail.

FIG. 3 is a plan view of a main part of the susceptor 3 shown in FIGS. 1 and 2, and the same parts as those described with reference to FIGS. 1 and 2 are designated by the same symbols.

In the figure, 11 is a gear portion formed in a belt shape along the circumference of the back surface of the revolution rotary table 4, 12 is a gear portion integrally formed with the susceptor 3, and 13 is a rotary rotary table 5. Each of the rotating shafts is integrally formed and has teeth around which gear teeth are cut.

FIG. 4 shows a cutaway side view of an essential part of the revolution rotary table 4,
The same parts as those described with reference to FIGS. 3 to 3 are designated by the same symbols.

In the figure, 14 is the rotary shaft of the revolution rotary table 4, 15 is a recess into which the gear part 12 formed integrally with the susceptor 3 is fitted, and 16 is a recess into which the rotary table 5 is fitted. Reference numerals 17 and 17 respectively denote holes into which the rotary shaft 13 of the rotary turntable 5 is fitted.

FIG. 5 shows a cutaway side view of a main part of the rotation table 5 for rotation,
The same parts as those described with reference to FIGS. 4 to 4 are designated by the same symbols.

FIG. 6 shows a cutaway side view of a main part of the susceptor 3, and the same parts as those described with reference to FIGS. 1 to 5 are designated by the same symbols.

In the figure, 18 is a recess into which the revolving rotary table 4 is fitted, 19
Is a hole into which the rotary shaft 13 of the revolution rotary base 4 is fitted, and 21 is a hole into which the auto-revolution driving rod 6 is fitted.

As is clear from FIG. 3 to FIG. 6, the revolving rotary table 4
When the rotation table 5 for rotation is mounted on, the rotation shaft 13 of the rotation table 5 for rotation is partially exposed to face the recess 15. In this state, when the revolution rotary table 4 is mounted on the susceptor 3, the gear formed around the rotary shaft 13 in the rotation rotary table 5 engages with the gear portion 12 formed integrally with the susceptor 3. To do. Then, when the toothed end of the gear of the revolving drive rod 6 is fitted into the hole 21 of the susceptor 3, the gear formed in a belt shape along the tooth and the back surface circumference of the revolving rotary table 4. The part 11 engages.

When the auto-revolution driving rod 6 is rotated in the state of being set in this way, the revolving rotary table 4 is driven, and the revolving rotary table 4 is rotated.
When is rotated, the rotating shaft 13 engaged with the fixed gear portion 12 is driven to rotate the rotation table 5 for rotation.

It goes without saying that all the members related to the susceptor 3 described above are made of carbon.

By the way, in the present invention, even if the semiconductor wafer 8 is revolved around the axis, contaminants such as carbon fine powder are not generated from the susceptor 3 and the like. It is believed that the reason is that a large amount of bypass carrier gas composed of, for example, H ₂ is allowed to flow during growth.

That is, normally, this kind of gas is flowed so as to be about several (l / min), but in the present invention, as is also seen in the above-mentioned examples, 20 (l / min) is also allowed to flow. There is. In this way, the gas acts as a kind of lubricant, and the friction of the mechanism is reduced, so it seems that fine carbon powder is not generated. This is also estimated from the fact that the use of H ₂ having a viscosity higher than that of N ₂ as the bypass carrier gas gives better results. It has been confirmed that reducing the flow rate of the bypass carrier gas or using N ₂ hinders the smooth movement of the mechanism. Although a standardized value has not yet been obtained for the flow rate of the gas, it is easy to experimentally confirm whether or not there is an influence on the smooth operation of the mechanism.

Now, it will be explained that the semiconductor film obtained by carrying out the present invention is excellent in uniformity in film thickness.

FIGS. 7 and 8 show the GaAs on the GaAs substrate according to the present invention.
The measurement results of the same sample on which the film is formed are shown as a diagram, and the vertical axis represents the normalized film thickness and the horizontal axis represents the distance from the wafer center.

FIG. 7 shows the result of measurement in the B-D direction seen on the annexed wafer, and FIG. 8 shows the result of measurement in the A-C direction of the similarly attached wafer. In both cases, it is clear that the distribution of the film thickness is extremely small.

FIGS. 9 and 10 show the same measurement results for samples other than the samples described with reference to FIGS. 7 and 8 as a diagram.

Even in the case of this sample, it is clear that the distribution of the film thickness is extremely small.

FIG. 11 is a diagram in which the results obtained by measuring the film thickness distribution in the circumferential direction of a certain sample are compiled, and the growth rate is plotted on the vertical axis and the wafer center is plotted on the horizontal axis. Each angle is taken.

It can be seen that the distribution of the film thickness is extremely small in this direction as well.

FIG. 12 is a diagram relating to the film thickness distribution showing a comparison between the case of revolving and orbiting according to the present invention and the case of standing still. The normalized film thickness is plotted on the vertical axis and the wafer center is plotted on the horizontal axis. The distance from each is taken.

As is clear from the figure, there is almost no film thickness distribution when it is revolved, but when it is stationary, the effect of the gas flow is significant.

The samples for which the above measurement data were obtained were all obtained by growing a GaAs film on a GaAs substrate, but not limited to such a GaAs system, an InP system, a ternary system, or a quaternary system semiconductor film was grown. In the case of the above, high film thickness uniformity is obtained.

〔The invention's effect〕

In the vapor phase growth method according to the present invention, each rotation for rotation in a susceptor having a plurality of rotation rotary tables made of carbon and a rotation rotary table for revolving the rotation rotary tables on the same plane. Place the wafer on the table and heat the susceptor at high frequency while bypassing the carrier gas with the source gas.
H ₂ as a gas is caused to flow in a direction parallel to the rotation and revolution planes of the susceptor, the wafer is rotated and revolved, and the position of each wafer that rotates is exchanged between the upstream and downstream of the gas flow while the organic compound semiconductor film is formed. Metal pyrolysis vapor growth is attempted.

By doing so, it is possible to grow a compound semiconductor film having a uniform film thickness, and it is possible to inexpensively manufacture an integrated circuit device, a HEMT, a heterojunction high-speed semiconductor device and the like using a compound semiconductor.

[Brief description of drawings]

FIG. 1 is an explanatory view of the essential parts of a MOCVD apparatus for carrying out the vapor phase growth method of the present invention, FIG. 2 is an explanatory cross-sectional view of the essential parts of the MOCVD apparatus shown in FIG. 1, and FIG. 2 is an explanatory plan view of the main part of the susceptor 3 shown in FIG. 2, FIG. 4 is a side view of a main part of the revolution rotary table 4, and FIG. 5 is a side view of the main part of the rotation table 5 for rotation. FIG. 7 to FIG. 10 are diagrams showing a film thickness distribution in a predetermined direction, FIG. 11 is a diagram showing a film thickness distribution in a circumferential direction, and FIG. 12 is according to the present invention. FIG. 3 is a diagram showing a film thickness distribution comparing the case and the case using the conventional technique. In the figure, 1 is a reaction tube, 1A is a reaction gas supply tube, 1B is an exhaust tube, 2 is a high-frequency heating coil, 3 is a semiconductor wafer susceptor, 4 is a rotation table for revolution, 5 is a rotation table for rotation, Reference numeral 6 is a rotation / revolution driving rod, 7 is an electric motor, and 8 is a semiconductor wafer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hitoshi Tanaka, 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor Kazumi Kasai, 1015, Kamikodanaka, Nakahara-ku, Kawasaki, Kanagawa Prefecture, Fujitsu Limited ( 72) Inventor Tatsuya Ohori, 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa, Fujitsu Limited (56) References JP 57-111298 (JP, A) S.K.

Claims (1)

[Claims] 1. A wafer is placed on each rotation rotary table in a susceptor having a plurality of rotation rotary tables made of carbon as a material and a rotation rotary table for revolving the rotation rotary tables on the same plane. , the susceptor and of H ₂ flowing in rotation and revolution plane parallel direction of the susceptor as a bypass carrier gas with the raw material gas with high-frequency heating, the position of each wafer to said rotation is rotation and revolution of each wafer the A vapor phase growth method characterized in that a compound semiconductor film is subjected to metalorganic pyrolysis vapor phase growth while switching upstream and downstream of a gas flow.