JPH11147787A - Epitaxial growth furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epitaxial growth furnace capable of remarkably reducing the temperature difference caused between the right and the back sides of a wafer in spite of a simple constitution as compared with that of a conventional furnace when heating the wafer at the time of epitaxial growth. SOLUTION: A pair of semiconductor wafers 10a and 10b are arranged in the interior of a reactional chamber 1 by holding mechanisms so as to oppose the surfaces thereof with an interval kept therebetween and further expose the back surface of each semiconductor wafer and oppose to the inner walls 2a and 2b of the reactional chamber 1 and a pair of heaters 11a and 11b for irradiating each back surface of both the semiconductor wafers with radiant heat are arranged in an epitaxial growth furnace for depositing and growing an Si epitaxial layer on the right side of the semiconductor wafers at a high temperature in the reactional chamber 1 by reduction or thermal decomposition of a reactional gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epitaxial growth furnace for epitaxially growing a surface of a semiconductor wafer substrate.

[0002]

2. Description of the Related Art At present, the most widely studied and applied silicon epitaxial growth method is H-Si-
This is a Cl-based CVD (Chemical vapor deposition) method.
In this method, a silicon source gas is supplied by a hydrogen carrier onto a silicon substrate heated to a high temperature, and an H-S
A silicon single crystal is deposited and grown through an i-Cl-based reaction. As a silicon source gas, SiCl
₄ , SiHCl ₃ , SiH ₂ Cl ₂ , and SiH ₄ are common.

[0003] As a growth furnace apparatus for performing such epitaxial growth, various types have conventionally been used. For example, there is a single-wafer device as an advantage in increasing the diameter. The substrate is placed on a susceptor in a chamber heated by a radiant heating method using a halogen lamp, and a reaction gas is sent into the chamber. Since this is a single-wafer treatment, the reaction chamber itself can be made compact, and the heating conditions, gas flow distribution, etc. can be easily designed and the uniformity of the epitaxial film characteristics can be increased.

In the conventional epitaxial growth method and apparatus described above, the wafer substrate is heated in a reference gas atmosphere such as hydrogen while being placed on a susceptor in the chamber, and then a new material is added to the reference gas. By releasing the gas and supplying it on the wafer surface, a reaction gas in which the material gas is mixed with the reference gas is generated, and the growth is started.

[0005]

However, in the heating method from one side, such as heating from the back side by heat conduction from the susceptor, a temperature difference occurs between the front side and the back side of the semiconductor wafer. . If a temperature difference occurs between the front and back of the wafer, one side thermally expands more than the other, causing warpage, and a temperature difference also occurs in the radial direction of the wafer. Such thermal stress may cause a so-called slip defect as a result of the slip deformation of the crystal and a step on the wafer surface.

Therefore, in order to avoid a temperature difference between the front and back surfaces of the wafer, which causes a warp or a slip defect of the wafer, there is a method of performing radiant heating from both sides of the wafer by using a lamp. And is not practical.

SUMMARY OF THE INVENTION In view of the above problems, it is a main object of the present invention to provide an excellent epitaxial growth furnace capable of satisfactorily performing epitaxial growth on the surface of a semiconductor wafer without causing defects. Another object of the present invention is to provide an epitaxial growth furnace capable of greatly reducing a temperature difference generated between the front and back of a wafer as compared with the conventional one while having a simple configuration in heating a wafer during epitaxial growth.

[0008]

In order to achieve the above object, in the epitaxial growth furnace according to the first aspect of the present invention, the surface of a semiconductor wafer at a high temperature is reduced or thermally decomposed on a surface of a semiconductor wafer in a reaction chamber. In an epitaxial growth furnace for depositing and growing an epitaxial layer,
A holding mechanism for arranging a pair of semiconductor wafers inside the reaction chamber such that the front surfaces thereof face each other at an interval, and the back surfaces of the respective semiconductor wafers are exposed and face the inner wall of the reaction chamber; And a pair of heaters for irradiating radiant heat to the respective back surfaces of the two semiconductor wafers.

According to a second aspect of the present invention, in the epitaxial growth furnace according to the first aspect, the holding mechanism vertically holds the pair of semiconductor wafers.

Further, in the epitaxial growth furnace according to the third aspect of the present invention, in the epitaxial growth furnace according to the second aspect, the holding mechanism holds the pair of semiconductor wafers in parallel with each other.

Further, in the epitaxial growth furnace according to the invention described in claim 4, in the epitaxial growth furnace described in claim 2, the holding mechanism holds the pair of semiconductor wafers at an inclined angle symmetric with respect to a vertical direction. It is to be kept in an inclined state.

In the present invention, a pair of heaters irradiates radiant heat to the back surface of each of a pair of semiconductor wafers arranged in a reaction chamber so as to face each other at an interval so that the surfaces face each other. Therefore, one semiconductor wafer has its back surface heated by radiant heat from one heater and its front surface heated by radiant heat from the other heater via the other semiconductor wafer.

As described above, the pair of semiconductor wafers are heated by the respective heaters on the back surfaces, and simultaneously, the respective front surfaces are heated by the other heater via the other semiconductor wafer. There is no large temperature difference between the front side and the back side as in the case of heating only from the side. Therefore, according to the epitaxial growth furnace of the present invention, the induction of warpage and slip defects of the semiconductor wafer is prevented, and favorable epitaxial growth can be performed.

Since the epitaxial growth is performed on both the pair of semiconductor wafers at the same time, the reaction gas is supplied evenly to both surfaces. Therefore, if a pair of semiconductor wafers are vertically held by the holding mechanism as described in claim 2, the reaction gas is supplied as a laminar flow from above to below (longitudinal direction) between the opposed wafers. Thereby, the gas supply to both semiconductor wafer surfaces can be made uniform. Further, such a configuration of vertical placement and laminar flow in the vertical direction can save space in a large-diameter semiconductor wafer.

In particular, when the pair of semiconductor wafers are held parallel to each other by the holding mechanism as described in claim 3, the pair of semiconductor wafers can be arranged at the shortest distance, and the wall of the reaction chamber and Since the respective heaters can be arranged in parallel with each other, it is easy to design the apparatus and easily obtain a uniform heating state.

The holding mechanism may be provided with a means for arranging a pair of semiconductor wafers in parallel in the vertical direction. For example, a configuration is provided in which a susceptor holding a wafer in a reaction chamber is provided with a mounting wall to which the susceptor is vertically removably mounted. At this time, holding means for preventing the semiconductor wafer from falling off the susceptor is provided.

According to a fourth aspect of the present invention, in the vertical arrangement of the pair of semiconductor wafers, the pair of semiconductor wafers are held by the holding mechanism at an angle symmetrical with respect to the vertical direction. Then, the larger the inclination angle, the higher the contact ratio of the wafer surface to the flow of the reaction gas supplied from above, so that the efficiency of epitaxial growth is improved and stable growth is obtained. This inclined state is a state in which the distance between the upper ends of both wafers is wider than the distance between the lower ends.

When the susceptor is to be inclined, means for attaching the susceptor to the reaction chamber so as to be able to incline may be provided. If the susceptor is in an inclined state, the susceptor can be simply placed on the susceptor. No special means for preventing falling off is necessary since it is difficult to fall off.

However, if the inclination angle is too large, it becomes difficult for the radiant heat from the heater to be uniformly radiated to the entire back surface. Therefore, it is desirable that the inclination angle be within an appropriate range. For example, when the radiant heat radiation surface of the heater is along the vertical direction, the inclination angle of each semiconductor wafer surface with respect to the vertical direction is set to about 20 degrees or less.

Note that the pair of semiconductor wafers in the present invention is not limited to one set, but may be any number as long as the size of the reaction chamber, the design of the uniform laminar flow of the reaction gas, and the arrangement of the corresponding heaters are possible. Any number of pairs may be used. For example, in a case where two sets of four sheets (two pairs) are arranged in a plurality of pairs, a configuration such as four sheets on the same circumference or one pair in the vertical direction can be considered. Also, the present invention is not limited to an even number of one-to-two sheets,
For example, a configuration is also conceivable in which three semiconductor wafers are arranged on the same circumference at equal angular intervals. In this case, the heaters may be arranged at equal angular intervals on the back side of each wafer on the same circumference outside the reaction chamber.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION As one embodiment of the present invention, a pair (two pairs) of semiconductor wafers of the same size are vertically arranged in parallel in a reaction chamber with their surfaces facing each other. A growth furnace for performing epitaxial growth by
This is shown in the schematic diagram of FIG. (A) is YY partial side sectional drawing, (b) is XX partial cross sectional view.

In the epitaxial growth furnace according to the present embodiment, a first side wall and a second side wall which face each other vertically and parallel to each other as long sides are provided as holding mechanisms in a vertical reaction chamber having an elliptical cross section and an inverted bell shape. It is a vertical type provided with a cylindrical middle chamber having a substantially rectangular section. FIG. 2 is a cross-sectional view of FIG.
FIG. 3 is a vertical sectional view of a ZZ part orthogonal to the Y section, and is a front view as viewed from the middle chamber.

That is, the present epitaxial growth furnace has a double structure of the reaction chamber 1 and the middle chamber 2, and the room A in the middle chamber 2 constitutes a second independent space isolated from the inner wall surface of the reaction chamber 1. Then, the room B formed by the inner wall surface of the reaction chamber 1 and the outer wall surface of the middle chamber 2 constitutes a first independent space.

The first side wall 2a and the second side wall 2b of the middle chamber 2, which is a semiconductor wafer holding mechanism, are respectively provided on the first side wall 2a and the second side wall 2b as shown in a plan view (FIG. An opening (3a, 3b) for attaching the semiconductor wafer 10a and the second semiconductor wafer 10b through the first and second susceptors (6a, 6b) is formed.

The first and second openings are formed in the openings (3a, 3b).
The first and second susceptors (6a, 6b) respectively holding the semiconductor wafers (10a, 10b) are locked, so that the first and second semiconductor wafers (10a, 1b) are locked.
0b) face each other vertically and parallel to each other, and are exposed and held in the room A, which is an independent space. At this time, the back surfaces of the two semiconductor wafers are exposed to the chamber B and face the inner wall surface of the reaction chamber 1.

In this embodiment, both susceptors (6a, 6
A so-called bayonet method was used as means for locking b) to each of the openings (3a, 3b). That is, as shown in the plan view of FIG. 4, on the susceptor (6a, 6b) side, a plurality of claw portions (7a, 7b) are formed at equal angular intervals on the outer periphery of the wafer holding region. Department (3
On the a, 3b) side, the same number of strip portions (4a, 4b) as the claw portions project at equal angular intervals corresponding to the arrangement of the claw portions (7a, 7b) on the susceptor side along the inner circumference. Have been.
The claw portions (7a, 7b) and the strip portions (4a, 4b) are shown in FIG.
As shown in FIG. 5, when the susceptor is locked, the susceptors have a cross-sectional shape that can fit and slide with each other.

When the susceptor is locked, the claw portion (7
a, 7b) and the strips (4a, 4b) are located at alternate positions, and the first and second susceptors (6a, 6b) are opened from the chamber B side toward the chamber A side (3a). , 3
b) Fit and rotate in a predetermined direction. With this rotation, each claw (7a, 7b) is turned into a corresponding strip (4a, 4).
Slide along b).

The surface (A) of each strip (4a, 4b)
One end of the chamber side has a spring-type lock pin (5
a, 5b) and each claw portion (7a, 7a).
Lock pins (5a, 5a,
5b) are formed with recesses (9a, 9b) that can be fitted, and when the sliding along the strips (4a, 4b) of the claws (7a, 7b) proceeds, each recess (9a, 9b) of the claws is advanced. 8a, 8b) are engaged with each other when they are located on the corresponding lock pins (5a, 5b), and thereby, into the respective openings (3a, 3b) of the first and second susceptors (6a, 6b). Is obtained.

The first susceptor 6a and the second susceptor 6b have several suction ports (9a, 9b) on the bottom surface on which the first and second semiconductor wafers (10a, 10b) are mounted, respectively. Are formed, and the susceptors (6a, 6a)
In the operation of locking the openings b) to the openings (3a, 3b),
Each of the wafers is handled by a robot arm (not shown) that sucks the susceptor together with the wafer from the back side of the susceptor (6a, 6b).

As described above, the first and second susceptors (6a, 6b) are moved by the robot arm along with the first and second semiconductor wafers (10a, 10b) through the door (not shown) of the reaction chamber. Each opening (3a, 3b) is locked, that is, the first and second wafer mounting walls (2a, 2b).
When both openings (3a, 3b) of b) are closed, the chamber 1 is completely separated into the chamber A and the chamber B so that they can be individually sealed, and the atmosphere in each chamber is different. Can be controlled.

Therefore, if both chambers B are set to a negative pressure with respect to chamber A, even after the robot arm is released from suction, the first arm is sucked through the suction port (9a, 9b) on the bottom surface of the susceptor (6a, 6b). The second semiconductor wafer (10a, 10b) is attracted to the chamber B side, and is fixed and held by each susceptor.

While the negative pressure state of the chamber B is maintained, the first and second semiconductor wafers (10a, 10b) are vertically aligned in parallel with the susceptors (6a, 10a) facing each other.
It is held in the chamber 1 via 6b).

On the other hand, outside the chamber 1, a pair of a first heater 11a and a second heater 11b for irradiating the semiconductor wafers (10a, 10b) with radiant heat from the back side is disposed. These heaters (11a, 11b) are arranged so as to face the back surface of one semiconductor wafer and to face the surface of the other semiconductor wafer, respectively.

Accordingly, the first heater 11a heats the first semiconductor wafer 10a from the back side and heats the second semiconductor wafer 10b from the front side.
Is for heating the second semiconductor wafer 10b from the back side and heating the first semiconductor wafer 10a from the front side. That is, since the two semiconductor wafers (10a, 10b) are heated from both the front and back surfaces, there is no large front-to-back temperature difference that occurs when heating is performed only from one side as in the related art. Further, the radiant heat irradiation surface of each heater is parallel to the corresponding susceptor and the back surface of the semiconductor wafer, and uniform heating is performed over the entire surface of the semiconductor wafer.

In the upper part of the reaction chamber 1, there is provided a second gas flow means (not shown) for supplying a laminar flow reaction gas containing a material gas only from the upper part of the chamber A downward.
A lower part of the reaction chamber 1 is provided with a first gas flow means (not shown) for supplying only hydrogen gas from below to the upper part of the chamber B from below. In the present embodiment, as shown in FIG. 2, the middle chamber 2 is used to send the reaction gas supplied from above the chamber A upward along the side wall from the bottom and discharge the reaction gas outside the reaction chamber 1. A channel 12 was provided. The supply of the hydrogen gas may be in any direction from below to above and from above to below, and is appropriately selected according to the device design.

In the epitaxial growth furnace having the above configuration, first, the first and second semiconductor wafers (10a, 10b) are respectively moved by the above-mentioned robot arm.
The first and second susceptors (6a, 6a)
b), the first opening 3a and the second opening 3
After the suction of each of the robot arms is released by setting both the B chamber pressure to the A chamber to be a negative pressure, the semiconductor wafers (10a, 10a,
10b) is adsorbed to each susceptor and brought into a fixed holding state.

The first and second semiconductor wafers (10a, 1
While maintaining the fixed holding state of 0b), heating by the first and second heaters (11a, 11b) is performed to heat both wafers to a temperature required for epitaxial growth conditions. When the temperature reaches a predetermined temperature, the first gas circulation means and the second gas circulation means are driven to supply hydrogen gas from below to the chamber B upward, and the laminar reaction gas is supplied to the chamber A upward. From below to start epitaxial growth.

During the epitaxial growth step, the first
And the second semiconductor wafers (10a, 10b) are first and second heaters (11a, 11b) from both sides.
The wafer is heated by b), the temperature difference between the front and back surfaces of each wafer is extremely small, the wafer does not warp, the occurrence of slip is avoided, and good epitaxial growth is promoted. Furthermore, according to the epitaxial growth furnace according to the present embodiment, as the epitaxial growth proceeds, only the hydrogen gas by the first gas flow means comes into contact with the inner wall surface of the reaction chamber 1, and the reaction gas containing the material gas does not flow. In addition, no silicon product is deposited on the inner wall surface of the chamber 1.

The configuration of the epitaxial growth furnace according to the present embodiment can be used even if it is a horizontal type. In other words, when a pair of semiconductor wafers are arranged vertically in parallel along the horizontal direction, the semiconductor wafer disposed above is susceptor (locked to the opening by the bayonet method) due to the negative pressure of chamber B against chamber A. Is fixed), so there is no problem.

In the above-described embodiment, each of the semiconductor wafers (10a, 10b) is
susceptors (6a, 6b)
A plurality of suction ports (9a, 9b) are formed in the bottom surface of the semiconductor wafer, and the semiconductor wafers (10a, 10b) are sucked through the suction ports. However, the present invention is not limited to this configuration. Any configuration can be used as long as it can be held. For example, the susceptor (6a, 6b) itself may be provided with a holding means such as a spring type press for holding each semiconductor wafer (10a, 10b).

In the above embodiment, a pair of wafers whose surfaces are opposed to each other are arranged in parallel along the vertical direction. However, another embodiment of the present invention will be described below. FIG. 5 shows a growth furnace configured to epitaxially grow a wafer in an inclined state having a symmetrical inclination angle with respect to a vertical direction.

As shown in the cross-sectional view of FIG. 5, the epitaxial growth furnace according to the present embodiment has a cylindrical middle chamber 22 in a vertical reaction chamber 21 having an elliptical cross section and an inverted bell shape, as in the first embodiment. When the side wall is used as a semiconductor wafer holding mechanism, at least a region including the susceptor installation portions (23a, 23b) of the middle chamber 22 is formed to have a reduced diameter, and the first side wall 22a and the second side wall 22b are positioned upward. It is configured to be inclined so that the interval is wider than below. In the present embodiment, the C room in the middle chamber 22 constitutes a second independent space, and the D room formed by the inner wall surface of the cylindrical chamber 21 and the outer wall surface of the middle chamber 22 is the first independent space.
Constitutes an independent space.

The first and second side walls (22a, 22b) have a first susceptor mounting portion 23a and a second susceptor mounting portion 23b, each having a shape substantially matching the susceptor bottom portion. A concave portion for receiving the second susceptor 26b) from the back side is formed. On the other hand, the first and second susceptors (26a, 26b) are respectively hooked on the outer peripheral edge of the concave portion of the susceptor mounting portions (23a, 23b). Protrusions (27a, 27b) are formed, fit into the susceptor mounting portions (23a, 23b) of the inclined first and second side walls (22a, 22b), and are stable without special locking means. It is configured to be mounted.

As described above, the susceptor mounting portions (2
3a, 23b) and the semiconductor wafer (30) mounted on the inclined susceptor (26a, 26b).
a, 30b) exposes its surface in the C room in the middle chamber 22 without falling down due to this inclination,
In addition, it is kept separated from the inner wall surface of the reaction chamber 21. Therefore, unlike the first embodiment, it is not necessary to specially provide a pressing portion, a suction unit, and the like for holding the semiconductor wafer. In particular, to suck semiconductor wafers,
It is not necessary to separate the insides of the reaction chambers so that they can be hermetically sealed and adjust the pressure under reduced pressure.

Outside the chamber 21, as in the first embodiment, a first heater 31a for heating the first semiconductor wafer 30a from the back side and heating the second semiconductor wafer 30b from the front side is provided. , The second semiconductor wafer 30b
Is heated from the back side and the first semiconductor wafer 30a
And a second heater 31b for heating the surface from the front side.

Here, the inclination angle is set to 20 degrees or less with respect to the vertical direction. If you take a large angle of inclination beyond this, the occupied space will spread in the horizontal direction,
This is because the chamber 21 becomes larger in the width direction, and at the same time, the distance from the heater differs in the vertical direction due to the inclination of the wafer, making uniform heating difficult, and a temperature difference may occur in the same wafer. In particular, 300mm and 400mm
In the case of so-called large-diameter wafers such as mm, the interval between both upper wafers is greatly increased with an increase in the inclination angle, and it is not easy to configure an apparatus for supplying a uniform reaction gas as a laminar flow.

The reaction chamber 21 is provided with a second gas flow means (not shown) for supplying a laminar flow reaction gas only from the upper part to the lower part into the C chamber at the upper part, and a hydrogen gas from the bottom part to the D part chamber at the lower part. The first to supply only gas upward from below
The middle chamber 22 has a flow path 32 through which the reaction gas supplied from above the C chamber is sent upward from the bottom along the side wall and discharged out of the reaction chamber 21. Was provided.

In the epitaxial growth furnace configured as described above, for example, the first and second susceptors (26a, 2a) on which the semiconductor wafers (30a, 30b) are mounted, respectively.
6b) is placed in an inclined state on each of the susceptor installation sections (23a, 23b) in the middle chamber 22 by a robot arm or the like, and the reaction chamber 21 is raised relative to the middle chamber 22 which is fixedly installed. After inserting the middle chamber 22 into the reaction chamber 21, the first and second heaters (31a, 31b) heat the semiconductor wafer to a temperature required for epitaxial growth conditions,
When the supply of the reaction gas is started, the epitaxial growth on the wafer surface can be started.

In the present embodiment, the two semiconductor wafers (30a, 30b) are inclined with respect to the vertical direction, but are not so large as to cause a large vertical difference in heating from the heater. Since the two heaters are uniformly heated from both sides to face each other, the temperature difference between the front and back surfaces is small, and good epitaxial growth is promoted without the possibility of warpage or slip of the wafer.

[0050]

As described above, according to the present invention, since the temperature difference between the front and back surfaces of the semiconductor wafer is small and the semiconductor wafer can be heated almost uniformly, it is possible to avoid the occurrence of the warpage or slip of the wafer due to the large temperature difference. There is an effect that good epitaxial growth can always be performed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an epitaxial growth furnace according to an embodiment of the present invention, in which (a) is a side sectional view of a YY part and (b) is a cross sectional view of a XX part.

FIG. 2 is a vertical sectional view of a ZZ portion (perpendicular to the YY cross section) of FIG. 1;

FIG. 3 is a plan view of first and second side walls (2a, 2b) of FIG. 1;

FIG. 4 is a plan view of the susceptor (6a, 6b) of FIG.

FIG. 5 is a schematic configuration diagram of an epitaxial growth furnace according to another embodiment of the present invention.

[Explanation of symbols]

 1, 21: chamber 2a, 22a: first side wall 2b, 22b: second side wall 3a, 3b: opening 4a, 4b: strip 5a, 5b: lock pin 6a, 6b: susceptor 7a, 7b: claw Parts 8a, 8b: recessed parts 9a, 9b: suction ports 10a, 10b, 30a, 30b: semiconductor wafers 11a, 11b, 31a, 31b: heaters 23a, 23b: susceptor installation parts 26a, 26b: susceptors 27a, 27b: protrusions

Continuing from the front page (72) Inventor Kazutoshi Inoue 555 Nakanoya, Annaka-shi, Gunma 1 Inside Super Silicon Laboratories, Inc.

Claims (4)

[Claims] 1. An epitaxial growth furnace for depositing and growing a Si epitaxial layer on a surface of a semiconductor wafer at a high temperature in a reaction chamber by reduction or thermal decomposition of a reaction gas, wherein a pair of semiconductor wafers are placed inside the reaction chamber. A holding mechanism arranged so as to face each other at an interval, and to expose the back surface of each semiconductor wafer to the inner wall of the reaction chamber, and a pair for irradiating radiant heat to each back surface of both semiconductor wafers arranged facing each other; An epitaxial growth furnace, comprising: 2. The semiconductor device according to claim 1, wherein the holding mechanism holds the pair of semiconductor wafers in a vertical direction.
3. The epitaxial growth furnace according to 1. 3. The epitaxial growth furnace according to claim 2, wherein said holding mechanism holds a pair of semiconductor wafers in parallel with each other. 4. The epitaxial growth furnace according to claim 2, wherein the holding mechanism holds the pair of semiconductor wafers at an inclined angle symmetric with respect to a vertical direction.