JP5342906B2 - Vapor growth equipment - Google Patents

Description

  The present invention relates to a vapor phase growth apparatus for supplying a vapor phase raw material while heating a substrate to grow a thin film on the substrate, and more particularly to a MOCVD (Metal Organic Chemical Vapor Deposition) apparatus.

Examples of the vapor phase raw material in the MOCVD apparatus include an MO gas that is a raw material gas of a group III element (Ga, Al, In) and an NH ₃ gas that is a raw material gas of a group V element (N).
When growing gallium nitride (GaN) thin films, especially when forming light emitting diodes (LEDs) and laser diodes (LDs), the GaN thin films usually have conductivity by doping impurities such as Si and Mg. It is known that

Impurities are generally classified into n-type impurities and p-type impurities. SiH ₄ (silane) and Si ₂ H ₆ (disilane) are used as n-type impurity materials, and Cp2Mg (p-type impurity materials are used as p-type impurity materials. Cyclopentadienylmagnesium) and DEZn (diethyl zinc) are used. These impurity materials are introduced into the reaction chamber using hydrogen or nitrogen as a carrier gas together with NH ₃ and other MO gases.

  When gas phase raw materials having different decomposition temperatures are introduced into the reaction chamber via the raw material introduction pipe (raw material gas nozzle), if these gas phase raw materials are mixed before being supplied into the reaction chamber, these mixed gases Since they react with each other before being introduced into the reaction chamber, a good thin film cannot be formed.

  Therefore, a plurality of raw material introduction pipes are provided so that gas phase raw materials having different decomposition temperatures are not mixed before being introduced into the reaction chamber, and source gases having different decomposition temperatures are separately introduced into the reaction chamber, and In order to ensure impurity doping, a technique has been developed in which each inlet pipe is provided with a temperature control means such as a heater so that the temperature of the gas phase raw material in each raw material inlet pipe can be controlled separately ( For example, see Patent Document 1).

In a MOCVD apparatus, a source gas or carrier gas introduced into a reaction chamber during film formation is heated indirectly by a substrate and a susceptor heated by a heater, and a thermochemical reaction is promoted to promote a thin film on the substrate. Is formed.
Then, as a means for realizing uniform thin film formation while improving the efficiency of thin film formation, the susceptor on which the substrate is placed is rotated, and a substrate placement member (substrate that places the substrate along with the rotation of the susceptor) A vapor phase growth apparatus having a mechanism for rotating and revolving a substrate during film formation by rotating a tray is known (see, for example, Patent Document 2).

  FIG. 6 is a cross-sectional view of the vapor phase growth apparatus 70 disclosed in Patent Document 2. As shown in FIG. A vapor phase growth apparatus 70 disclosed in Patent Document 1 includes a susceptor 73 made of disc-shaped carbon in a flat cylindrical chamber 72 having a gas introduction pipe 71 disposed at the upper center, and an outer peripheral portion of the susceptor 73. A plurality of substrate holders 74 arranged at equal intervals on the concentric circles, and a partition plate 76 that is disposed above the susceptor 73 and that divides the chamber 72 vertically and forms a reaction chamber 75 on the susceptor 73 side. I have.

  The chamber 72 is divided into a chamber main body 77 having an opening on the side opposite to the susceptor side, and a chamber lid 78 that is airtightly mounted on the upper peripheral wall of the chamber main body 77 via an O-ring. A rotation drive shaft 79 for rotating the susceptor 73 is provided at the center of the bottom of the chamber main body 77. By rotating the susceptor 73 with the rotation drive shaft 79, the substrate holder 74 holding the substrate 80 is moved to the susceptor 73. In addition to revolving with respect to the center of the susceptor 73, a rotation gear mechanism provided on the outer periphery of the susceptor 73 rotates.

A heater 81 for heating the substrate 80 is disposed in a ring shape below the substrate holder 74, and a ring-shaped exhaust passage 82 is provided on the outer peripheral side of the susceptor 73.
The partition plate 76 is divided into a plurality of portions in the circumferential direction and the radial direction, and has a large-diameter ring-shaped outer peripheral side partition plate 76a disposed on the outer peripheral side, and a plurality of portions divided in the circumferential direction on the inner peripheral side thereof. It is formed by a small-diameter ring-shaped inner peripheral side partition plate 76b in which fan-shaped divided bodies are combined. The outer peripheral side partition plate 76 a is fixed at a predetermined position in a state where the outer peripheral edge is placed on the inner periphery of the peripheral wall of the chamber body 77.

  The chamber lid 78 is attached to the lifting / lowering means 86 via a plurality of brackets 86a provided on the outer peripheral portion, and a cylindrical bellows 87 is airtightly attached between the chamber lid 78 and an upper flange 71a provided on the upper portion of the gas introduction pipe 71. In addition, the opening of the chamber body 77 can be opened by operating the elevating means 86 in the upward direction to raise the chamber lid 78 while contracting the bellows 87.

Japanese Unexamined Patent Publication No. 6-069132 JP 2008-262967

A p-type impurity material (hereinafter sometimes referred to as “doping material”) used for doping is an organic metal having a very low vapor pressure, such as Cp2Mg (cyclopentadienylmagnesium) or DEZn (diethylzinc). For this reason, in many cases, the p-type impurity source is housed in a thermostatic chamber and maintained at a temperature higher than room temperature, for example, 35 ° C. to 45 ° C. (depending on film forming conditions).
The p-type impurity raw material supplied from the supply source (constant temperature bath) is supplied to the reaction chamber through the raw material supply pipe. In the case of the vapor phase growth apparatus 70 of Patent Document 2, for example, a gas introduction pipe 71 corresponds to the raw material supply pipe in the vapor phase growth apparatus, and the center of the chamber lid 78 is extended downward from the top. is set up. The gas introduction pipe 71 is heated to about 100 ° C. at the outlet (reaction chamber side) of the gas introduction pipe 71 under the influence of the heater 81 that heats the susceptor 73, but the temperature increases as the distance from the reaction chamber side increases. Is lowered, and is about room temperature to about 40 ° C. at the lowest point.

For this reason, when supplying the p-type impurity source maintained at a temperature higher than normal temperature in the thermostatic chamber to the reaction chamber, the p-type impurity source may condense at the low temperature portion of the gas introduction pipe 71 and adhere to the inner wall of the pipe. .
When the p-type impurity material adheres to the inner wall of the tube, the deposited p-type impurity material may be detached from the tube wall and supplied to the reaction chamber during the growth of a thin film layer that does not require the p-type impurity material ( Memory effect).

Thus, since it is assumed that the temperature difference between the supply source of the p-type impurity source and the source supply pipe (gas introduction pipe 71) causes the memory effect, in order to prevent the memory effect, Heating by winding a heater around the raw material supply pipe is also conceivable.
However, in the apparatus in which the raw material supply pipe (gas introduction pipe) is installed in the chamber along the central axis of the chamber lid, as disclosed in Patent Document 2, a heater cannot be wound. Therefore, at present, no measures are taken.

  The present invention has been made to solve such a problem. In a vapor phase growth apparatus in which a material supply pipe is installed in a chamber, the memory effect of p-type impurities can be suppressed and impurity doping can be reliably performed. An object of the present invention is to obtain a vapor phase growth apparatus that can be used.

(1) A vapor phase growth apparatus according to the present invention includes a chamber main body, a chamber lid provided on the chamber main body for opening and closing the chamber main body, and a substrate installed in the chamber main body on which a thin film is grown. A reaction chamber formed by the opposing surface member and the susceptor, wherein the substrate is heated in a state where the substrate is placed on the susceptor. A vapor phase growth apparatus comprising a plurality of raw material introduction channels for introducing vapor phase raw materials into
A heating medium jacket in which at least one of the plurality of source introduction channels is used as a doping source introduction channel to which a doping source is supplied, and a heating medium is passed adjacent to the channel wall of the doping source introduction channel And a temperature control device for controlling the temperature of the heat medium,
Before Stories heat medium jacket, has a partition wall therein, the heat medium flowed through from one of flow paths partitioned by the partition walls to the other flow path, and wherein the doping material introduced in the heat medium jacket The heat medium is introduced from the channel side adjacent to the channel.

(2) Further, in the above (1), the apparatus has a rotating shaft for rotating the susceptor, and the plurality of raw material introduction flow paths are provided coaxially with the rotating shaft. It is.

(3) Further, in the above-described (2), the plurality of raw material introduction flow paths are provided in triple in the radial direction.

(4) Moreover, in the thing in any one of said (1)-(3), the said temperature control apparatus controls the temperature of a heat medium in the range of 40-80 degreeC, It is characterized by the above-mentioned. .

  In the present invention, a doping medium is provided by providing a heating medium jacket for allowing a heating medium to flow adjacent to the channel wall of the doping material introduction channel and controlling a temperature of the heating medium. Adhesion to the channel wall can be prevented, thereby suppressing the memory effect of the doping raw material and ensuring impurity doping.

1 is a schematic configuration diagram of a vapor phase growth apparatus according to an embodiment of the present invention. It is an enlarged view which expands and shows the part enclosed with the broken line of FIG. It is the schematic which shows an example of the film | membrane structure formed with the vapor phase growth apparatus. It is a SIMS analysis result of a comparative example. It is a SIMS analysis result of an Example. It is sectional drawing of the conventional vapor phase growth apparatus.

FIG. 1 is an explanatory view of a vapor phase growth apparatus according to an embodiment of the present invention, and shows a portion corresponding to a portion A surrounded by a broken line in FIG. 6 showing a conventional example. 2A is an enlarged view of a portion B surrounded by a broken line in FIG. 1, and FIG. 2B is an AA view of FIG. 2A.
A vapor phase growth apparatus according to an embodiment of the present invention will be described below with reference to FIGS.

As shown in FIGS. 1 and 2, the vapor phase growth apparatus 1 according to the present embodiment includes a chamber 7 composed of a chamber body 3 and a chamber lid 5, and a substrate 9 on which the thin film is formed by being installed in the chamber body 3. Is disposed, coaxially with the rotary shaft 15 inside the rotary shaft 15, a counter surface member 13 arranged to face the susceptor 11, a rotary shaft 15 that rotationally drives the susceptor 11, and the rotary shaft 15. And a raw material introduction pipe 17 for introducing a vapor phase raw material.
Hereinafter, the main structure of the vapor phase growth apparatus 1 will be described in detail.

<Chamber>
The chamber 7 has a flat cylindrical shape as a whole, and includes a lower chamber body 3 and a chamber lid 5 that opens and closes the chamber body 3.
A raw material introduction path is installed at the center of the chamber body 3 so that the vapor phase raw material can be supplied to the substrate 9 placed on the susceptor 11. Details of the raw material introduction path will be described later.
The outer peripheral edge portion of the chamber main body 3 is a main body flange 19 which is in contact with the lid flange 21 of the chamber lid 5 so that the chamber 7 can be hermetically closed (see FIG. 1).

A ring-shaped groove 23 serving as a discharge flow path for the supplied source gas is formed at the outer edge of the chamber body 3 and inside the lid flange 21. The upper end portion of the outer wall of the groove portion 23 serves as the support portion 25 of the facing surface member 13.
A susceptor 11 is installed in the chamber body 3 so as to be able to revolve (rotate), and a heater 27 for heating the substrate 9 is installed below the substrate mounting portion 29 in the susceptor 11.
In addition, since there is a part which does not like being influenced by the heating of the heater 27, in the chamber 7, the water cooling jacket is provided in such a part.

  The chamber lid 5 is moved up and down with respect to the chamber body 3 by a lifting mechanism (not shown). A lid flange 21 is formed on the outer peripheral edge of the chamber lid 5, and the lid flange 21 is disposed opposite to the main body flange 19.

<Susceptor>
The susceptor 11 has a disk shape as a whole, and is installed in the chamber 7 so as to be able to revolve as described above. The susceptor 11 is provided with a plurality of substrate placement portions 29 that can rotate, and a substrate 9 on which a thin film is formed is placed on the substrate placement portion 29.
The susceptor 11 is a mechanism that revolves (rotates) as a whole by a drive mechanism (not shown), and the substrate platform 29 rotates in conjunction with this revolution.

<Counterface member>
The opposing surface member 13 has a substantially disk shape as a whole, and a leg portion 31 extending downward is formed at the outer peripheral end portion. The opposing surface member 13 forms a reaction chamber 32 with the susceptor 11 by placing the leg portion 31 on the support portion 25 of the chamber body 3.
The facing surface member 13 includes a substrate facing surface portion 33 disposed to face the substrate 9 placed on the substrate placing portion 29 of the susceptor 11, and a substrate facing surface support portion 35 that supports the peripheral portion of the substrate facing surface portion 33. It is composed of
The peripheral surface portion of the substrate facing surface portion 33 is supported by the substrate facing surface support portion 35 and can be detached from the substrate facing surface support portion 35 by being lifted upward.

<Raw material introduction pipe>
The raw material introduction pipe 17 is formed of a member made of, for example, stainless steel disposed inside the rotation shaft 15 of the susceptor. As shown in FIG. 2, the raw material introduction pipe 17 is formed with three flow paths, a first flow path 37, a second flow path 39, and a third flow path 41, from the center to the radially outer side. ing. A heat medium jacket 43 through which a heat medium flows is provided between the second flow path 39 and the third flow path 41, and a gas phase that flows through the second flow path 39 and the third flow path 41. The temperature of the raw material can be controlled. By causing the p-type impurity material used for doping to flow through the second flow path 39 or the third flow path 41 and controlling the temperature, it is possible to suppress the p-type impurity material from condensing in the material introduction path, and as a result. Memory effect can be prevented.

  The heat medium jacket 43 has a partition wall 45 therein, and the heat medium flows from one flow path partitioned by the partition wall 45 to the other flow path. In the example shown in FIG. 2, as indicated by the arrows in the figure, the heat medium entered from the entrance of the heat medium jacket 43 flows from the bottom to the top in the figure and is folded at the upper end. It flows from the top to the bottom in the outer channel and exits to the outlet. In the middle of the flow path through which the heat medium flows outside the heat medium jacket 43, a temperature adjusting device for adjusting the temperature of the heat medium is provided so that the heat medium temperature can be adjusted in the range of 40 ° C to 80 ° C. It has become. Note that the heat medium temperature can be adjusted to 40 ° C. or higher in order to prevent the p-type impurity material used for doping from condensing in the flow path and adhering to the flow path wall. This is because the temperature is preferably 40 ° C. or higher.

  As the heat medium, for example, water or a solvent can be used, and as the temperature adjusting device, for example, a chiller or the like can be used.

The operation of the vapor phase growth apparatus configured as described above will be described.
When a thin film is grown on the substrate 9 using the vapor phase growth apparatus 1, as shown in FIG. 1, the substrate 9 is placed on the substrate placing portion 29, and the facing surface member 13 is placed facing the susceptor 11. The chamber lid 5 is closed. Then, the susceptor 11 is revolved and the substrate mounting portion 29 is rotated, and the substrate 9 is heated by the heater 27, and in this state, the vapor phase material is caused to flow through the material introduction path.

  The p-type impurity raw material used for doping is passed through the second flow path 39, and the heat medium is flowed from the bottom to the top of the heat medium jacket 43 as indicated by the arrows in FIG. Fold at the upper edge and let it flow from top to bottom. By doing so, the temperature of the p-type impurity material flowing in the second flow path 39 can be controlled to a temperature at which it does not condense. The temperature of the heat medium flowing through the heat medium jacket 43 is adjusted according to the type of doping raw material flowing through the raw material introduction path. As a result, the doping raw material flowing through the second flow path 39 is prevented from condensing in the flow path and adhering to the tube wall, and the memory effect can be suppressed.

In order to confirm the effect of reducing the memory effect by controlling the temperature of the p-type impurity raw material flowing through the raw material introduction path by the heat medium jacket 43, a film forming experiment was conducted using the vapor phase growth apparatus shown in FIGS. went.
FIG. 3 is a schematic view showing an example of a film structure formed by this experiment. On the sapphire substrate, a ud-GaN layer (first layer), an Mg-AlGaN layer (second layer), an Mg-GaN layer ( The third layer) and the ud-GaN layer (fourth layer) are grown.

The vapor phase raw material and the supply flow path that are supplied when each thin film layer is grown are shown below.
(1) ud-GaN layer (first layer)
1st channel: N ₂ + NH ₃ gas mixture orN ₂ + NH ₃ + H ₂ gas mixture 2nd channel ... H ₂ + N ₂ + MO
Third flow path: N ₂ + NH ₃ mixed gas orN ₂ + NH ₃ + H ₂ mixed gas

(2) Mg-AlGaN layer (second layer),
1st channel …… N ₂ + NH ₃ mixed gas orN ₂ + NH ₃ + H ₂ mixed gas 2nd channel …… H ₂ + N ₂ + MO + p-type impurity source 3rd channel …… N ₂ + NH ₃ mixed gas orN ₂ + NH ₃ + H ₂ mixed gas

(3) Mg-GaN layer (third layer)
1st channel …… N ₂ + NH ₃ mixed gas orN ₂ + NH ₃ + H ₂ mixed gas 2nd channel …… H ₂ + N ₂ + MO + p-type impurity source 3rd channel …… N ₂ + NH ₃ mixed gas orN ₂ + NH ₃ + H ₂ mixed gas

(4) ud-GaN layer (fourth layer)
1st channel: N ₂ + NH ₃ gas mixture orN ₂ + NH ₃ + H ₂ gas mixture 2nd channel ... H ₂ + N ₂ + MO
Third flow path: N ₂ + NH ₃ mixed gas orN ₂ + NH ₃ + H ₂ mixed gas

Note that MO is an organic metal source gas such as TMG (trimethylgallium), TMA (trimethylaluminum), or TMI (trimethylindium), and the p-type impurity source gas is Cp2Mg, DEZn, or the like.

In the film structure shown in FIG. 3, for example, Cp2Mg is supplied as a p-type impurity source for the growth of the second Mg-GaN layer and the third Mg-GaN layer. Since the p-type impurity material is not required for the growth of the GaN layer, it is not supplied. For this reason, it is preferable that the p-type impurity material supplied during the growth of the Mg-GaN layer is not mixed as much as possible during the growth of the ud-GaN layer.
Therefore, when the temperature of the heat medium is controlled to about 60 ° C. so that the p-type impurity material does not condense in the material introduction path (Example), and when the temperature control is not performed without passing the heat medium (Comparison) Example 2) was performed. The SIMS analysis results in the two experimental results are shown in FIG. 4 (comparative example) and FIG. 5 (example).
SIMS analysis is an evaluation method capable of measuring the concentration of a trace element in a formed thin film in the thickness (depth) direction of the thin film. ) Is the concentration (atoms / cc), and the horizontal axis is the thickness (measurement position) (μm) of the formed thin film.

In the comparative example shown in FIG. 4, the Mg concentration increases in the ud-GaN layer (fourth layer) grown next to the Mg-GaN layer (fourth layer) even though Cp2Mg is not supplied. ing. This is due to the memory effect of Mg.
On the other hand, in the example shown in FIG. 5, compared with the comparative example, the Mg concentration in the ud-GaN layer (fourth layer) grown after the Mg-GaN layer (third layer) is clearly higher. Reduced. This is nothing but the memory effect can be suppressed.
From the comparative example and the example, it was found that the memory effect can be suppressed by using the jacketed material nozzle.

  In the above-described embodiment, as shown in FIG. 2A, the doping material is caused to flow through the second flow path 39, and the heat medium jacket 43 is interposed between the second flow path 39 and the third flow path 41. Since the heat medium is provided and introduced to the flow path side adjacent to the second flow path 39, the temperature-controlled heat medium flows first to the second flow path 39 side where temperature control is desired. Control becomes possible. In addition, the introduced heat medium exchanges heat with the tube wall of the second flow path 39, the temperature is somewhat lowered, and exits from the flow path on the third flow path 41 side.

  In the above embodiment, the heat medium jacket 43 is provided between the second flow path 39 and the third flow path 41. However, the position where the heat medium jacket 43 is provided is not limited to this, What is necessary is just to provide adjacent to the flow path through which the gaseous-phase raw material which wants to control temperature is supplied. For example, when doping material flows through the 1st flow path 37, the 1st flow path 37 and the 2nd flow path 39 are used. A heat medium jacket 43 may be provided between the two.

  Further, in the above embodiment, as shown in FIG. 2A, the heat medium is introduced into the inner flow path side of the heat medium jacket 43 and is discharged to the outer flow path side. The flow may be such that the medium is introduced to the outer flow path side and discharged to the inner flow path side. In this case, it is suitable for the temperature control of the vapor phase raw material flowing in the third flow path 41.

  The present invention particularly relates to a semiconductor manufacturing apparatus for depositing a compound semiconductor, and more particularly to a vapor phase growth apparatus for introducing an impurity source gas into a reaction chamber of the semiconductor manufacturing apparatus.

DESCRIPTION OF SYMBOLS 1 Vapor growth apparatus 3 Chamber main body 5 Chamber lid 7 Chamber 9 Substrate 11 Susceptor 13 Opposite surface member 15 Engagement holding mechanism 17 Source gas introduction nozzle 19 Main body flange 21 Lid flange 23 Groove 25 Support part 27 Heater 29 Substrate placement Unit 31 Leg 32 Reaction chamber 33 Substrate facing surface 35 Substrate facing surface support 37 First flow path 39 Second flow path 41 Third flow path 43 Heat medium jacket 45 Partition wall

Claims (4)

A chamber main body, a chamber lid provided on the chamber main body for opening and closing the chamber main body, a susceptor on which a substrate on which a thin film is to be grown is placed, and an opposing surface disposed opposite to the susceptor A plurality of raw material introduction channels for introducing a vapor phase raw material into a reaction chamber formed by the opposing surface member and the susceptor by heating the substrate with the substrate placed on the susceptor. A vapor phase growth apparatus comprising:
A heating medium jacket in which at least one of the plurality of source introduction channels is used as a doping source introduction channel to which a doping source is supplied, and a heating medium is passed adjacent to the channel wall of the doping source introduction channel And a temperature control device for controlling the temperature of the heat medium,
Before Stories heat medium jacket, has a partition wall therein, the heat medium flowed through from one of flow paths partitioned by the partition walls to the other flow path, and wherein the doping material introduced in the heat medium jacket A vapor phase growth apparatus characterized in that the heat medium is introduced from a flow path side adjacent to the flow path.   2. The vapor phase growth apparatus according to claim 1, further comprising: a rotating shaft that rotates the susceptor, wherein the plurality of raw material introduction channels are provided coaxially with the rotating shaft.   The vapor deposition apparatus according to claim 1, wherein the plurality of raw material introduction channels are provided in a triple in the radial direction. The said temperature control apparatus controls the temperature of a heat medium in the range of 40-80 degreeC, The vapor phase growth apparatus as described in any one of the Claims 1 thru | or 3 characterized by the above-mentioned.

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