JPH0323633B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the production of Group-3 alloys or compounds (hereinafter referred to as compounds). In particular, the present invention relates to the deposition of said substance of the compound to be prepared onto a heated substrate in an otherwise cold environment.

Metal-organic chemical vapor deposition method (hereinafter referred to as MOCVD method)
has been proposed. The process consists of impinging a stream of cold gaseous reactants, usually mixed with a carrier gas, against a hot substrate, such as the reaction of trimethylgallium with hydrogen arsenide using hydrogen as the carrier gas. This reaction can be expressed by the following equation.

(i) Ca (CH ₃ ) ₃ (air) + AsH ₃ (air) H ₂ / High temperature---→ Substrate CaAs (solid) + 3CH ₄ (air) For example, when the group element is indium, such as indium phosphide. Attempts to apply similar reactions to the production of certain Group Group compounds have been made by reacting trialkylindium and Group element hydrides, such as hydrogen phosphide and hydrogen arsenide, together at low temperatures and applying them to a hot substrate. This has not been met with sufficient success because non-volatile polymeric substances are formed before reaching the target. The formation of the polymer can be summarized by the following equation.

(ii) (wherein R=alkyl, X is a group element) This type of reaction is described by R. Didchenko et al. in J. In. Org. Nuc. Chem. 14 , 35 (1960). The formation of this polymeric material depletes the gas phase reactants, resulting in reduced product growth rates and poor morphology. Moreover, precise control of the amount of indium present in the product is not possible since the gas phase concentration of the indium compound is changed by reaction (ii) as indicated above. Trimethyl gallium and hydrogen arsenide do not significantly form the corresponding polymeric substances.

According to the present invention, instead of causing the group 5 element hydride and the group element alkyl derivative to react by colliding with a hot substrate, electron density is imparted to the group group element alkyl derivative, thereby making the derivative of,
It is a weak Lewis acid that does not undergo reaction with group hydrides to form non-volatile polymers. This modified derivative is then mixed with the required Group element hydride and conveyed to the substrate on a heated susceptor plate where the required Group-Group compound is deposited. . A Lewis acid is defined herein as an element or compound that is electron deficient and is an electron acceptor, and a Lewis base is defined as an element or compound that has an excess of electrons and is an electron donor.

A first method according to the invention involves reacting (i) the desired alkyl derivative of the group element with (ii) the alkyl derivative of the group element to form a volatile intermediate, which is then evaporated. The intermediate and (iii) the desired Group element hydride are carried as a gas in a hydrogen gas stream and impinged on the hot substrate. In this way, the alkyl derivative of the group element is endowed with electron density by reaction with the alkyl derivative of the group element, forming a volatile intermediate. This volatile intermediate reacts with the Group element hydride on the hot substrate. The reaction can be represented by the following equation.

MR ₃ (Ki) + XR′ ₃ (Ki) H ₂ --→ Low temperature R ₃ M・XR′ ₃ (Ki) R ₃ M・XR′ ₃ (Ki) + X′H ₃ (Ki)
H ₂ ---→ High temperature plate MX'+XR' ₃ +3RH In the formula, M is a group element, X and X' are group elements,
R and R' are alkyl groups. X may be, but need not be, the same as X', and R may be, but need not be, the same as R'. Preferably R and R' are methyl or ethyl groups.

In the above formula, MR ₃ reacts with XR′ ₃ when cold, and the compound R ₃ M·XR′ ₃ formed _is
Since it is a stronger Lewis base than X'H ₃ , it is stable in the presence of X'H ₃ and thus the formation of undesirable polymers is stopped.

A second process according to the invention involves substituting the alkyl group of the desired alkyl derivative of the group element with an electron donating group, and then displacing the obtained substituted alkyl derivative of the group element in a stream of hydrogen gas as required. consisting of mixing with a group element hydride and transporting it to a hot substrate.

In this way substituted alkyl derivatives of group elements are prepared which are weaker isic acids than unsubstituted alkyl derivatives of group elements. This substituted alkyl derivative of the Group element does not react with the Group element hydride when used in the MOCVD process until it reaches the hot substrate.

The invention will now be described with reference to the following examples and the accompanying drawings, which are schematic illustrations of apparatus for carrying out the method of the invention.

The illustrated device includes inlet and outlet pipes 2 and 3 for communicating cooling water to an external cooling jacket 9.
It has a water-cooled container 1 with a . Inside the container 1 is a graphite table 4, on which a substrate 5 for vapor deposition is placed. A thermocouple 6 extending from the outside of the container 1 enters the inside of the stand 4, and the outside of the container is surrounded by an induction heating coil 7. The interior of the container has an exhaust pipe 8. In these respects, the present invention
A standard reaction vessel for MOCVD, except that the water cooling jacket 9 is shortened and the steam inlet end of the vessel 1 is not covered. The reason should be obvious.

At the inlet end of the vessel 1 there is an inlet passage 10 for the flow of vapor for reaction to adducts or compounds according to the invention. The passageway 10 has an axial inlet 11 for group alkyl derivative vapor and a radial inlet 12 adjacent to the inlet 11 for admitting electron donating vapor. The baffle plate 13 is such that it limits the passage in front of the radial inlet 12 and defines a partially closed reaction chamber. Immediately in front of the adjustment plate 13 are H ₂ S and
Radial inlet 1 for dopant such as ZnMe ₂
There are 4. The passage extends into the container 1 and has a side hole 15 for communicating the interior of the container with the passage 10. A radial inlet 16 is attached to the outer side of the water cooling jacket 9 of the vessel for the group hydride vapor.

Means such as a heater tape is provided to increase the temperature of the inlet passageway 10, typically to 20° above ambient, to prevent agglomeration of adducts or compounds formed in the passageway 10. . Premature agglomeration is also prevented by shortening the water cooling jacket mentioned earlier.

Reference will now be made to specific examples.

Example 1 A first cryogenic vapor stream consisting of 10 ^-4 moles of trimethylindium in hydrogen was passed from inlet 11 to passage 10, and a second stream consisting of the same concentration of triethylphosphine in hydrogen. A stream of cold steam flows from inlet 12 into passageway 10. Those streams react in the reaction chamber to give a volatile adduct, which enters vessel 1 through inlet 15 and a third substance containing about 15 times the amount of phosphine, also mixed with hydrogen, which enters the vessel through inlet 16. Contact with cold vapor stream. The mixed vapor stream is directed over a heated substrate 5 (typically 650°
±50℃) to deposit indium phosphorus. The reaction can be expressed by the following equation.

InMe ₃ +PEt ₃ H ₂ (air) ――――→ Low temperature Me ₃ In・PEt ₃ Me ₃ In・PEt ₃ +PH ₃ H ₂ (air) ――――→ High temperature substrate InP + PEt ₃ +3MeH Deposition speed is determined by introduction of vapor flow The amount was adjusted to approximately 5-6 microns/hour per unit area by adjusting the amount using a flow regulator.

Additionally, in the following examples, the reactor and conditions were similar to those described above.

Example 2 Indium arsenide was produced on a high temperature substrate by the MOCVD method. In this case, trimethylindium and triethylarsine, followed by excess arsine, were bombarded together in a stream of cold hydrogen gas onto the substrate. The reaction can be expressed by the following equation.

InMe ₃ +AsEt ₃ 〓〓 Me ₃ In・AsEt ₃ +AsH ₃ H ₂ ---→ Low temperature InAs + AsEt ₃ +3MeH Example 3 Indium phosphide was produced on a hot substrate by the MOCVD method. In this case, triethylindium and triethylamine, followed by an excess of phosphine, were combined in a stream of cold hydrogen gas and impinged on the substrate. The reaction can be represented by the following equation.

InEt ₃ +NEt ₃ H ₂ ---→ Low temperature Et ₃ In・NEt ₃ Et ₃ In・NEt ₃ +PH ₃ H ₂ ---→ High temperature substrate InP + NEt ₃ +3EtH Example 4 Three components of gallium indium arsenide on a hot substrate by MOCVD method I made an alloy. In this case trimethylgallium, trimethylindium and triethylphosphine, followed by excess arsine, were combined in a stream of cold hydrogen gas and impinged on the substrate. The reaction can be expressed by the following equation.

xGaMe ₃ + (1-X) InMe ₃ + PEt ₃ H ₂ ---→ Low temperature (1-X) InMe ₃・PEt ₃ +xMe ₃ Ga・PEt ₃ xMe ₃ Ga・PEt ₃ + (1-X) Me ₃ In・PEt ₃ +AsH ₃ H ₂ ---→ High temperature substrate Ga _X In _(1-X) As+PEt ₃ +3MeH A second method according to the invention is illustrated in the following example.

Example 5 Indium phosphide was produced on a hot substrate by MOCVD. In this case phosphine and dimethyl
Diethylamino indium (Me ₂ InNEt ₂ ) was combined in a stream of cold hydrogen gas and bombarded with a hot substrate. Dimethyl diethylamino indium was prepared by conventional chemical means. It will be seen that diethyl diethylamino indium is trimethyl indium with one of the alkyl groups replaced by a whole paper endowed amine group. Therefore, dimethyldiethylamino indium is trimethyl
It is a weaker Lewis acid than indium. The MCCVD reaction can be expressed by the following equation.

Me ₂ InNEt ₂ + PH ₃ H ₂ ---→ Hot plate InP + by-products Dimethyl diethylamino Indium does not react with PH ₃ to produce non-volatile products at low temperatures. Dimethyl dimethylamino indium may also be used and is preferred because of its high volatility.

Example 6 A gallium indium phosphorus arsenide quaternary alloy was prepared on a hot substrate by MOCVD. In this case trimethyl gallium, trimethyl indium,
Triethyl phosphine and excess amounts of arsine and phosphine were used as cold gases to collide with the substrate.
The reaction can be expressed by the following equation.

GaMe ₃ +InMe ₃ +PEt _3Low temperature――→ GaMe ₃・PEt ₃ +InMe ₃・PEt ₃ GaMe ₃・PEt ₃ +InMe ₃・PEt ₃ +AsH ₃ +PH _3High temperature――→ Substrate Ga _X In _1-X AsyP _ly +PEt ₃ +MeH In this reaction, these equations are not balanced, but to be exact, they include the x and y terms of the alloy.

The invention can in principle be applied to any system containing alkyl derivatives that are strong enough Lewis acids to be difficult to transport to the desired reaction site.

[Brief explanation of the drawing]

The drawing is a schematic illustration of an apparatus for carrying out the method of the invention. DESCRIPTION OF SYMBOLS 1... Container, 5... Substrate, 9... Water cooling jacket, 11, 12, 16... Reaction steam inlet, 14...
...Dope inlet, 8...Exhaust pipe.

Claims (1)

[Scope of Claims] 1. A method for depositing a group-group compound on a heated substrate, comprising: mixing an alkyl derivative of a group element and a hydride of a group element, each in a vapor stream; A method characterized in that the alkyl derivatives of group elements in the vapor stream are modified into weak Lewis acids by imparting electron density. 2. Combining the alkyl derivative of the desired group element with an alkyl derivative of the group element, i.e., a Lewis base, thereby forming a volatile adduct, and then combining the volatile adduct with the desired group element. 2. A method as claimed in claim 1, in which the hydride is carried as a vapor and impinged onto a hot substrate. 3. The method according to claim 1, wherein the modified derivative is produced by substituting an alkyl group of a group element alkyl derivative with an electron donating group. 4. A method according to any of claims 1 to 3, wherein the modified derivative is prepared immediately before transferring it onto the substrate. 5. The method according to any one of claims 1 to 4, wherein the group element is gainium. 6 A vapor stream containing an alkyl derivative of a group element is mixed with a vapor stream of a compound that donates electrons, thereby forming a modified derivative, and a vapor stream containing this derivative is mixed with a vapor stream containing a hydride of a group element. 6. A method according to any one of claims 1 to 5, further comprising mixing a vapor stream with a vapor stream and then contacting the mixed stream with a substrate. 7. The method of claim 5, wherein the first mixed vapor stream is maintained at approximately ambient temperature to avoid agglomeration of the modified derivative. 8. A method according to claim 1 or claim 7, wherein all gas streams contain excess hydrogen. 9 Claim 1-- The mixture of alkyl derivatives of group elements is modified before being delivered to the substrate.
The method described in any of Item 8. 10. The method according to any one of claims 1 to 9, for transporting a hydride of a group element to a substrate.