JPH0666270B2 - Method of manufacturing semiconductor device containing phosphorus - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to phosphorus-containing semiconductor devices, particularly III-V semiconductor devices.

Background Art III-V light emitting diodes (LEDs) based on semiconductor materials
Devices such as lasers and lasers are typically fabricated on bulk semiconductor substrates such as bulk indium phosphide substrates. A typical manufacturing process involves epitaxially depositing III-V semiconductor material on a heated substrate via a thermally induced reaction in a gas mixture at the substrate surface. Heretofore, various deposition mixtures have been used. One of the phosphorous-containing mixtures suitable for the deposition of III-V semiconductor materials is a material containing phosphine as the phosphorus source. Thus, for example, when depositing indium phosphide, the initial gas mixture contains phosphine as the phosphorus source and indium chloride as the indium source.

The morphological quality of the deposited layer has an important influence on the device quality. A common defect encountered in growing III-V based semiconductor materials by hydride epitaxy is the formation of hillocks. This mound is a crystallographic defect that causes a portion of the growth material to overlie all other growth materials, at least within an area of 100 μm ^2.
The extension is 0.5 μm. (GH Olsen for hydride epitaxy, an epitaxy method where the source of the Group V element is phosphine and the reactor wall in the reaction zone of the apparatus is heated by an external source such as a furnace.
"GaInAsP Alloy Semiconducer"
tors) TP Pearsall, John Wile
See y & Sons, page 11, 1982. )
The hills substantially degrade or severely limit device characteristics such as current confinement, light output, electrical contact efficiency and reliability. In addition, Koga often makes device fabrication processes that depend on the planar morphology, such as contact mask pattern writing processes, impossible. To reduce morphological defects, such as hills, on slightly deviated substrate surfaces, eg (10
Attempts have been made to grow on a substrate surface that is 1 to 6 degrees offset from a crystallographic plane such as the 0) plane. However, substantial hills are still formed. Moreover, for many device structures that are manufactured depending on the exact crystallographic orientation, even the slight improvement obtained by offsetting is prohibited. For example, in the manufacture of V-groove lasers, the groove formation depends on the in-plane crystallographic orientation of the substrate. If you use a substrate with misaligned orientation
unacceptable etch structure like vetail). Thus, the formation of hills remains a factor in degrading device yield and efficiency.

SUMMARY OF THE INVENTION Collisions in hydride transport of indium phosphide are avoided by ensuring that the phosphine used in the deposition process is essentially completely decomposed before it reaches the deposition substrate. be able to. Decomposition of phosphine can be achieved in various ways. For example, phosphines are heterogeneously decomposed on heated surfaces, such as catalyzed heated surfaces. Using phosphine decomposition, the hydride transport chemistry of III-V semiconductor materials such as III-V ternary and quaternary materials with phosphorus components. It is also advantageous in vapor deposition.

Example Description The method of the present invention for growing III-V semiconductor materials for the manufacture of devices such as LEDs, lasers and photodetectors is based on a hydride deposition gas system. General hydride systems are well known and are described in the references such as Olsen, supra. Basically, Group V materials such as phosphorus and / or arsenic are provided in the form of their corresponding hydrides, namely phosphine and / or arsine. These materials are generally brought into a gas mixture with a carrier gas, for example a reactive carrier such as hydrogen or an inert carrier such as helium. Hydrogen is required, but a carrier gas containing only inert constituents is acceptable in the case of essentially indium-free materials). The Group III material is brought into the reaction mixture by any of a number of conventional methods. For example, hydrogen chloride is diluted in hydrogen and transported over liquid indium. Once formed, the reaction mixture is transported over the deposition substrate. The deposition substrate is maintained at a temperature suitable to induce a reaction of the gas mixture to produce the desired epitaxial layer. For phosphorus-containing binary compounds (eg indium phosphide), ternary compounds and quaternary compounds, temperatures in the range 600 to 750 ° C. are generally suitable. The exact temperature that produces a suitable epitaxial layer for a given stoichiometric deposition material is determined using comparative samples.

The shape of the reactor is not critical. Suitable shapes are described in documents such as Olsen, supra. An example of a convenient shape is shown in FIG. This is a quartz growth vessel 21 having at least one Group III material source 17 and a phosphine source 16.
including. In addition, other group V materials are
It is also possible to introduce from source 18 via, for example, arsine. The deposition gas is exhausted from the reactor by conventional means such as exhaust pipe 20. Other conventional growth means, such as rotation of the substrate, growth at sub-atmospheric pressure, use of a compound barrel apparatus, although not essential, can be used in the technique of the present invention.

As mentioned above, the phosphine is added to the P
It is important that substances such as ₂ , P ₄ and hydrogen moieties, ie, H and H _2, are substantially decomposed (substantial decomposition in the present invention means at least 93 mol% of phosphorus reacting on the deposition substrate). Means that it is in a form other than phosphine).

In general, phosphines only undergo heterogeneous degradation. That is, it requires a surface that causes degradation. The phosphine has a typical reactor temperature of 90% when only the reactor wall is present.
Dependence on the thermal decomposition of the introduced phosphine is insufficient, as it decomposes relatively slowly at temperatures in the range 0 to 900 ° C. Therefore, improvements are needed to enhance degradation. For example (at a given deposition temperature), it is possible to substantially increase the distance traveled, increase the time used for contact with the wall, and thus increase the proportion of introduced phosphine decomposed. is there. Alternatively, a catalyst or a heated high surface area material may be used to enhance the decomposition rate and use a substantially shorter transfer area.

Suitable materials (in Mendeleev's Periodic Table) for Group VI metals, such as tungsten, molybdenum, tantalum, are suitable for inducing phosphine decomposition via catalysts and / or in the presence of large areas or both. Typically,
When the surface undergoing decomposition is heated to a temperature in the range of 400 to 900 ° C., a surface area in the range of 10 to 500 cm ² gives a suitable decomposition for phosphine flow rates in the range of 1 to 10,000 sccm. III-VC when the surface area is less than 5 cm ^2.
Proper decomposition does not occur at the temperatures and flow rates typically used for VDs. Surface areas greater than 500 cm ² are not excluded, but are typically inconvenient for the following reasons. That is,
This is because 1) the reactor has a large volume and 2) it is necessary to use powders which are difficult to disperse in the gas system. Decomposition rate depends on temperature, surface area,
Depends on catalysis and flow rate. The conditions given are generally suitable for producing the desired level of degradation. It is confirmed that, for any particular condition, a decomposition rate sufficient to form a relatively sample-free mound was achieved.

The phosphine does not have to be decomposed in the reaction vessel, but can be introduced into the vessel after decomposing in a region outside the vessel. However, conditions must be maintained so that less volatile decomposition products, such as P _4, do not condense excessively. Overcondensation generally results in a degradation product environment of 400
It can be avoided by keeping the temperature above ℃.

Once the III-V based semiconductor material is deposited, the rest of the device is complete. There is much literature on the completion of various devices. For example, the manufacturing process of V-groove laser is described in "Journal of DP Wilt"
Of Applied Physics "(Journal of App
56, No. 3, 710, 1984. The LED manufacturing process is based on H.Temkin
Kin) et al., "Bell System Technical Journal," Vol. 62, No. 1, page 1, 1983.

The following are examples to illustrate the invention.

Example 1 A substrate of indium phosphide was cut so that the main surface was the (100) plane. These substrates were exposed to bromine dissolved in methanol and chemically polished. After polishing
The substrates were cleaved into 2.0 cm x 3.2 cm (0.8 inch x 1.25 inch) pieces. These pieces were then stored under dry nitrogen until use.

Immediately prior to epitaxy growth, the fragments were sequentially placed in boiling trichloroethane for 3 minutes, boiling acetone for 3 minutes, boiling methanol for 3 minutes, and a 5: 1: 1 mixture of sulfuric acid, hydrogen peroxide and water (room temperature). It was soaked in it for 3 minutes and washed.
Then rinse the substrate with deionized water, then methanol,
Then, it was spin dried with a stream of dry nitrogen. Quartz container 21
Quartz sample holder 19 (first
The substrate was placed on top of the figure). The vessel was evacuated to 1333 Pa (10 Torr) and then filled with hydrogen until about 103,991 Pa (780 Torr). The reactor contained 11.52 grams, a tungsten coil 80 in the form of a loosely wound coil made of tungsten wire 0.45 mm in diameter. By a furnace not shown,
Initially the reactor was maintained at 820 ° C in source region 14 (shown in dotted lines) and 680 ° C in growth region 15. Input tube 1 at this temperature
A continuous hydrogen flow of 500 sccm was maintained by introducing the same hydrogen flow through each of 0, 11, 12 and 13.

The pure hydrogen flow is stopped to start the growth and 16 via tube 22
A 00 sccm backflow of hydrogen was generated and this backflow was mixed with a 50 sccm hydrogen flow containing 5% phosphine using a mass flow controller (indicated by MFC in the figure). After 5 minutes, the sample was moved to a preheating position (not shown) and kept at this position for 10 minutes. Next, a hydrogen flow of 1150 sccm was introduced over the molten indium in boat 17. A 75 sccm gas stream containing 5% phosphine in hydrogen was mixed with a 750 sccm dilute hydrogen stream. This combination was run through tube 10. An 8 sccm hydrogen stream containing 500 ppm hydrogen sulfide was combined in tube 11 with a 1600 sccm hydrogen stream. In addition, 8 sccm containing 1.5% hydrogen chloride
Was introduced into tube 11. These gas streams were allowed to stabilize for about 2 minutes. The sample was then transferred to growth region 15 and the etch removal of about 0.5 μm of indium phosphide was initiated. After 3 minutes, the hydrogen dilution of the gas stream containing 5% phosphine in hydrogen was stopped. A gas stream containing 5% hydrogen chloride in hydrogen was raised to 375 sccm and flowed over liquid indium in boat 17. As a result, n-type indium phosphide growth occurred. After 23 minutes, the hydrogen sulfide component in the hydrogen stream was removed and 1 gram of zinc was inserted at position 25. At this point, the zinc had a temperature of about 375 ° C. Thus p
Type indium phosphide has begun to grow. After 13 minutes, the hydrogen sulfide stream was reintroduced into the hydrogen under the conditions described above, the zinc was returned to its original position and the growth of the n-type indium phosphide layer was continued for 19 minutes. By such a process, the thickness at the bottom
2.0 μm n-type indium phosphide layer, thickness 1 in the middle
μm P-type indium phosphide layer, 1 μm thick on top
A structure having an n-type indium phosphide layer was produced. A V-groove laser was then formed in this structure as described by DP Wilt et al., Supra. The threshold of these lasers is 119mA, the output is 87mA, 10mW / facet
Met.

Example 2 The process of Example 1 was repeated except that the substrate was hand polished before growth. The polishing was performed by placing the substrate on a vacuum chuck and rubbing the surface with a cotton twill cloth moistened with a methanol solution containing 1% by volume of bromine for 10 seconds. The substrate was then rinsed with methanol and spin dried under dry nitrogen. After loading the substrate, the process proceeded as described in Example 1 except the post etch was omitted.
The resulting laser had essentially the same operating characteristics as the laser of Example 1.

Example 3 An indium phosphide substrate whose main surface is the (100) plane is about 0.5
It was first diced into square inch pieces and hand ground as in Example 2. This fragment was then loaded onto the sample holder 26 of the reactor shown in FIG. Approximately 133.3Pa (1 Tor
It was evacuated to r) and filled with hydrogen to about 13.790 Pa (2 psi) above atmospheric pressure. Using a mass flow controller, 700 sccm of hydrogen flow through tube 30, 180 sccm of hydrogen flow through tube 27, 300 sccm of hydrogen flow over catalyst 28, and 275 sccm of phosphine flow over the catalyst. Introduced and another 300 sccm hydrogen stream was flushed through tube 31. The entire area of the furnace (not shown) was maintained at 700 ° C (catalyst 19.
3 grams, 25.4 cm (1 mm) from a 0.25 mm diameter tantalum wire
It was formed by cutting 0 inch). ).

The sample was inserted into growth position 35 for 5 minutes and adjusted to growth temperature. It was confirmed that the phosphine on the catalyst was completely pyrolyzed (93 mol% or more) during this adjustment time.
This confirmation was confirmed by M. Halmann in the "Journal of the Chemical Society" (Journal o
f the Chemical Society) 164, 2853 pages (1963
Year)) UV absorption technique (190 nm).

After 5 minutes of stabilization, 4sc containing 5% by volume of hydrogen chloride
A hydrogen flow of cm was formed around the indium in the boat 32 via the tube 30 and maintained for 5 minutes to etch the sample. After 5 minutes on indium, the growth of indium phosphide was started with a flow of hydrogen containing 5% by volume hydrogen chloride at 160 sccm. This growth process lasted 60 minutes. The resulting indium phosphide layer was observed using a Normarski control optical microscope and no hills were visible.

[Brief description of drawings]

1 and 2 are diagrams illustrating an apparatus suitable for carrying out an embodiment of the present invention. [Explanation of symbols for main parts] Phosphine source …… 16 Catalyst …… 28

Claims (7)

[Claims] 1. A step of exposing a substrate to a vapor containing phosphorus in a hydride epitaxy process, depositing a phosphorus-containing composition on the substrate through an interaction with the vapor, and completing the device. In the method of manufacturing a semiconductor device containing phosphorus, the step of exposing the substrate to a vapor containing phosphorus in the hydride epitaxy step further includes at least 93 mol% of phosphorus that interacts in the substrate.
A method of manufacturing a semiconductor device containing phosphorus, which comprises the step of moving phosphine introduced from a phosphine source through a chamber having a length long enough to satisfy the condition that it is a form other than phosphine. . 2. The method of claim 1, wherein the phosphine is catalytically decomposed before reaching the substrate. 3. The method according to claim 1, wherein the deposit containing the forest comprises a III-V semiconductor material. 4. The method according to claim 3, wherein the phosphine is catalytically decomposed before it reaches the substrate. 5. The method according to claim 4, wherein the catalyst contains a Group VI metal or tantalum, and a method for manufacturing a semiconductor device containing phosphorus. 6. The method of claim 5, wherein the composition comprises one selected from the group consisting of tungsten, molybdenum and tantalum. . 7. The method of claim 1, wherein the device comprises a laser and a method of manufacturing a semiconductor device containing phosphorus.