JPH07201743A - Device for vapor deposition - Google Patents

Abstract

PURPOSE:To inverse a susceptor in the cleaning and heat treating step of substrate for avoiding the pollution in a deposition chamber in relation to the susceptor holding the substrate. CONSTITUTION:A susceptor 1 includes a U-shaped driver 4 fixed to the upper end of a vertical shaft 6, cylindrical cams 1c, 1d that move up and down in response to the rotation of the shaft 6. The substrate holding surface 1a is formed on one end of the susceptor 1. The cylindrical cams 1c, 1d double symmetrically provided are free rotatably held by a holding part 4 around a swivelling axle to be vertically hung. In such a constitution, the susceptor 1 is lifted by the acceleration of the shaft 6 to be inversed when the center of gravity gets higher than the swivelling axle thereby reversing the substrate holding surface 1a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vapor phase deposition apparatus which causes less pollution due to evaporation from a substrate, and more particularly to a susceptor which can orient a substrate holding surface in a direction opposite to that during deposition.

A vapor deposition apparatus for depositing a semiconductor thin film on a semiconductor substrate, for example, a CVD (chemical vapor deposition) apparatus, MBE
In a (molecular beam epitaxy) device, the substrate is heated to clean the substrate surface before deposition.

However, the constituent elements of the substrate evaporated from the surface of the substrate due to this heating adhere to the inner wall of the apparatus, and are then mixed into the raw material gas during the deposition of the semiconductor thin film to contaminate the thin film and deteriorate the quality of the thin film. .

Therefore, there is a demand for a vapor deposition apparatus capable of preventing such contamination from the substrate.

[0005]

2. Description of the Related Art HgCd is a conventional vapor deposition apparatus.
A description will be given with reference to an example of depositing a Te thin film by the CVD method.

The HgCdTe thin film used in the infrared device can be deposited by epitaxial growth on CdTe or CdZnTe having a small lattice mismatch as a substrate. However, CdTe and CdZnTe are expensive and cannot manufacture a large-area substrate. Therefore, it is possible to easily obtain a large-sized substrate at a low cost.
Single crystal is used as the substrate.

When GaAs is used as the substrate for the HgCdTe thin film, the Ga element in the substrate diffuses into the HgCdTe deposited layer and acts as an n-type impurity, and the lattice constant between the substrate and the deposited layer is large, so that the deposited layer is large. The problem is that the crystal defect density is high. In order to solve this problem, a buffer layer made of CdTe is usually used for the substrate and HgC.
It is provided between the dTe thin film.

By the way, in order to deposit the CdTe buffer layer on the GaAs substrate surface, it is necessary to heat the GaAs substrate to a temperature of about 600 ° C. to clean the substrate surface before the deposition. However, the heating of the substrate for cleaning cleans the inner wall of the deposition chamber. That is, first GaAs
As having a high dissociation pressure evaporates from the surface of the substrate, then Ga that has lost its bond with As scatters, and these As and Ga adhere to the inner wall surface of the deposition chamber. These impurity elements adhering to the inner wall of the deposition chamber are mixed with the raw material gas at the time of deposition, or fly directly and are taken into the deposited thin film as impurities.

For example, HgCdTe is formed on a GaAs substrate by a CVD method containing organic Cd (eg DMCd) as a source gas.
When depositing a thin film, DMCd + Hg → DMHg ↑ + Cd ↓, 3DMHg +
By the chemical reaction of 2Ga (GaAs) → 2TMGa ↑ + Hg, Ga adhering to the inner wall surface of the deposition chamber reacts with organic mercury (eg DMHg) which is a reaction product of organic Cd and mercury.
yields a (eg TMGa). As a result, organic Ga is mixed in the raw material gas and a large amount of Ga impurities are taken into the HgCdTe thin film by R. Korenstein et al.
Vac.Sci.Technol., A8, p1039 (1990).

Therefore, a method for protecting the inner wall of the deposition chamber, which is exposed to the source gas in the vapor deposition apparatus, from the contamination by the constituent elements of the substrate caused by the heating before the deposition is required to form the high-purity deposition layer. Becomes

[0011]

As described above, in the conventional vapor deposition apparatus, the constituent elements of the substrate adhere to the inner wall surface of the deposition chamber during the heat treatment of the substrate. There was a problem that they were taken in as impurities.

According to the present invention, by reversing the upper and lower surfaces of the susceptor, the substrate holding surface of the susceptor is turned upside down when the substrate is heated, which may contaminate the deposition chamber, thereby reducing contamination in the deposition chamber. , An object is to provide a vapor phase deposition apparatus for depositing a high-purity thin film.

[0013]

FIG. 1 is a perspective view of a susceptor according to an embodiment of the present invention, showing the structure of a susceptor of a vapor deposition apparatus and its supporting structure. FIG. 2 is a cross-sectional view of the vapor phase deposition apparatus according to the embodiment of the present invention, showing an outline of the main part of the vapor phase deposition apparatus.

The first constitution of the present invention for solving the above-mentioned problems is to refer to FIG. 1 and FIG. 2 and to show a shaft 6 vertically and rotatably provided in a deposition chamber and an upper end of the shaft 6. A susceptor 1 that is held and has a substrate holding surface 1a formed
In a vapor deposition apparatus having: a cylindrical portion 1e formed on the susceptor 1; and a two-fold rotationally symmetric two-piece formed on the side surface of the cylindrical portion 1e and having a central axis of the cylindrical portion 1e as a symmetry axis Cylindrical cams 1c and 1d and two cylindrical cams 1c and 1d
To each of the two ends of the diameter of the cylindrical portion 1e, sandwiching the cylindrical portion 1e, and two contactors 3c and 3d sandwiching the cylindrical portion 1e, and one contactor to each bifurcated branch formed at the upper end of the shaft 6. Three
c, 3d) are held on a horizontal straight line, and the contacts 3c, 3d
A holding portion 4 for rotatably supporting the cylindrical portion 1e held between the two forks around the horizontal straight line, and a rotary drive device 7 for applying a rotational acceleration to the shaft 6, The center of gravity of the susceptor 1 is provided at a position where the center line of the cylindrical portion 1e vertically hangs when the shaft 6 stops or rotates at a constant speed, and the cylindrical cams 1c and 1d and the sandwiching portion 4 have the cylindrical cam 1c. , 1d as subordinate nodes and the contactors 3c, 3d as driving nodes, a cylindrical cam device for linearly moving the susceptor 1 up and down according to the rotational acceleration of the shaft 6 is configured, and In the second configuration, in the vapor phase deposition apparatus of the first configuration, the temperature radiating for introducing the heat radiation light from the susceptor 1 into the shaft 6 at the bottom side 4a of the U-shaped portion 4 and deriving it from the lower end. It is characterized by the provision of a window 5 for The third configuration is characterized in that, in the vapor phase deposition apparatus of the first configuration, a nozzle 8 for supplying a volatile component gas is provided in the vicinity of the substrate holding surface (1a) when heating and cleaning the substrate 2. To do.

[0015]

In the structure of the present invention, the susceptor has a cylindrical portion in a part thereof, and has a substrate holding surface orthogonal to or oblique to the cylindrical portion. One of such shapes is a cylindrical susceptor. In this case, the entire susceptor constitutes a cylindrical portion, and one end surface of the cylinder can be used as the substrate holding surface. Hereinafter, for convenience of description, an example in which the susceptor 1 has a cylindrical shape will be described.

First, in the configuration of the present invention, referring to FIG.
The cylindrical portion 1e of the susceptor 1 is provided with two cylindrical cams 1c and 1d, for example, cylindrical cam grooves, which are in a two-fold rotational symmetrical relationship. One of the contacts 3c, 3d contacts the cylindrical cams 1c, 1d, respectively, and the two contacts 3c, 3d are arranged so as to face both ends of the diameter of the cylindrical portion 1e.

These two contactors 3c and 3d are normally located near the tips of the vertical branches 4c and 4d of the bifurcated holding part 4, the contactor 3c of the cylindrical cam 1c on the branch 4c, and the branch 4d on the branch 4d. The contactor 3d of the cam 1d is held, and the contactors 3c and 3d are mounted so as to be on a horizontal straight line.

Further, the cylindrical cams 1c and 1d have a two-fold rotational symmetry relationship with each other. Therefore, the cylindrical portion 1e is clamped by the two contacts 3c and 3d whose diameters are arranged on a horizontal straight line. As a result, since the diameter of the cylindrical portion 1e is always held horizontally, the central axis of the cylindrical susceptor 1 is always orthogonal to the horizontal straight line connecting the contacts 3c and 3d (hereinafter referred to as "horizontal rotation axis"). In other words, in other words, it is held so as to be in the vertical plane orthogonal to the holding direction (which means the horizontal rotation axis direction).

Next, in the configuration of the present invention, the susceptor 1 is disposed between the branches 4c and 4d of the holding portion 4 and is rotatably held in the forward and reverse directions about the horizontal rotation axis. Such a mechanism can be realized, for example, by making the contacts 3c, 3d cylindrical or spherical, or by rotatably supporting the contacts 3c, 3d on the branches 4c, 4d of the holding portion 4.

In this structure, when the shaft 6, that is, the sandwiching portion 4 is stopped or is rotating at a constant speed, the susceptor 1 hangs with its center of gravity at the lowest point. Therefore, when the center of gravity is above the sandwiching position (the position of the horizontal rotation axis), the susceptor 1 rapidly rotates around the horizontal rotation axis so that the center of gravity becomes the lowest point. In this configuration, when the susceptor 1 hangs down, the susceptor 1 is arranged so that the cylindrical portion 4 is vertically positioned and hangs down.
The center of gravity position of is determined. Therefore, by this rotation, the susceptor 1 is turned upside down 180 °. That is, the susceptor 1
The substrate holding surface 1a formed at one end of the substrate also moves to the opposite side of the susceptor 1 as the susceptor is inverted.

Further, in the configuration of the present invention, the cylindrical portion 1e and the sandwiching portion 4 constitute a cylindrical cam mechanism in which the cylindrical cams 1c and 1d serve as subordinate nodes and the contacts 3c and 3d serve as driving nodes. This cylindrical cam mechanism will be described with reference to FIGS. 1 (a) shows an initial state in which the shaft 6 is stationary, FIG. 2 (b) shows a state immediately after rotational acceleration is applied to the shaft, and FIG. 3 (c) shows a still state thereafter. Is represented.

As described above, in the stationary state, as shown in FIG.
Referring to (a), the cylindrical portion 1e is vertically sandwiched by the contacts 3c and 3d. When rotation is applied to the shaft 6 in this state, the rotation of the holding portion 4 at the upper end of the shaft 6 is accelerated, while the cylindrical portion 1e remains stationary due to inertial force. For this reason, the contacts 3c and 3d are
Rotating along the cam curves of c and 1d, the cylindrical portion 1e is vertically moved upward with reference to FIG. Such a mechanism can be realized by using a cylindrical cam having a cam curve as a spiral or an ordinary cylindrical cam that converts such rotation into a straight line.
If the shaft 6 is rotating at a constant speed initially,
Except that the rotation speed is accelerated, the same actions and effects as in the above example are produced.

Next, the rotational acceleration of the shaft 6 is reduced to zero or to such an extent that the cam does not move. The contactor 3c,
The rotation of the cylindrical portion 1e may be accelerated by the rotation of 3d, but it is also possible to reduce the rotation by setting the increased rotational speed to a small value which is the inverse of the acceleration.

The cylindrical portion 1e which has moved upward after the decrease in the rotational acceleration of the shaft 6 or before the decrease is shown in FIG. 1 (c).
With reference to, the center of gravity is moving upward beyond the horizontal rotation axis, and therefore, it is inverted around the horizontal rotation axis as described above. As a result, the substrate holding surface 1a, which is initially on the upper end surface of the susceptor 1 and faces upward, becomes the lower surface of the susceptor 1 after turning and faces downward.

The inverted susceptor 1 can be inverted again to restore the initial state by applying the same acceleration to the shaft 6. Therefore, the deposition chamber is provided above or below the vapor phase growth apparatus, the surface of the substrate 2 held by the substrate holding surface 1a is exposed to the deposition chamber during deposition, and the susceptor 1 is inverted during heating and cleaning of the substrate 2. 2 can be isolated from the deposition chamber. Therefore, with this configuration, it is possible to prevent the deposition chamber wall surface and the deposition chamber from being contaminated by the elements scattered from the substrate 2. Therefore, a thin film containing few impurities is deposited.

Even if the deposition chamber is provided on either side of the vapor phase growth apparatus and the substrate holding surface is formed on the side surface of the susceptor 1, the same action and effect are produced. In the second configuration, referring to FIG. 1, a window 5 is provided on the bottom side 4a of the holding section 4. This window 5 is a temperature observation window 5 for introducing the heat radiation light from the susceptor 1 to the shaft 6 and guiding it from the lower end of the shaft 6 with reference to FIG.
For example, the temperature of the susceptor 6 can be observed with a radiation thermometer. Therefore, the substrate temperature can be controlled easily and precisely.

In the third configuration, in the vicinity of the substrate holding surface 1a when the substrate 2 is heated and cleaned, for example, in the vicinity of the substrate holding surface 1a facing downward when the deposition chamber is provided in the upper part of the apparatus, A nozzle 8 is provided to supply a volatile component element that constitutes the substrate when the substrate is heated and washed. As a result, the partial pressure of the volatile element in the atmosphere near the surface of the substrate can be increased and the evaporation of the element from the substrate can be prevented. Therefore, it is possible to reduce the contamination caused by the decomposition of the substrate and to deposit a thin film having good crystallinity.

Needless to say, in the present invention, the spiral cylinder cam curve is wound in the reverse direction so that the direction of rotation of the pinching portion, which is the driving node, can be reversed.

[0029]

The present invention will be described in detail with reference to an embodiment of a CVD apparatus for depositing a HgCdTe thin film on a GaAs substrate.

Referring to FIG. 1, the susceptor 1 has a diameter of 10.
It is composed of a carbon cylinder having a height of 5 cm and a height of 10 cm, a substrate holding surface 1a perpendicular to the cylinder axis is formed at one end, and two cylindrical cams 1c, 1d are formed on the side surfaces.

The substrate holding surface 1a is a plane perpendicular to the cylinder axis on which the substrate 2 is placed, and has a ring-shaped substrate holder 1b which is screwed onto the susceptor 1 and presses the periphery of the substrate 2 on the plane. .

The cylindrical cams 1c and 1d are formed as spiral cam grooves. As described above, other cam curves can be used. Each of the contacts 3c, 3d is formed by forming a contact end made of quartz glass in the shape of a circle, a sphere or a boat at the tip of the quartz glass shaft, and the quartz glass shaft holds the nipping portion 4
The contact end is inserted into the cam groove and held.

The holding portion 4 is formed on the upper end of the quartz shaft 6, and is made of a quartz member mounted on the upper end of the shaft 6 at the center of the U-shaped bottom side 4a. The two contacts 3c, 3d are attached by inserting the glass shafts of the contacts 3c, 3d into holes provided at the horizontal positions of the tips of the two branches 4c, 4d of the holding part 4. This attachment is pivotally supported when the contact ends of the contacts 3c and 3d are boat-shaped. With a circular or spherical contact end, the contact end holds the susceptor rotatably, so that the glass shaft can also be fixed.

The nipping portion 4 has a window 5 formed of an optically flat surface in the center of the upper surface of the bottom side 4a, that is, immediately above the upper end surface of the shaft 6.
Is provided. On the other hand, a similar window is also provided at the lower end of the shaft 6, and the temperature of the susceptor 1 located immediately above the lower end of the shaft 6 can be observed by the radiation thermometer 13 (see FIG. 2).

In the vapor phase growth apparatus of this embodiment, referring to FIG. 2, the source gas inlet 10 is provided at the upper end and the exhaust port 1 is provided at the lower portion of the side wall.
1 and a susceptor 1 supported by the tip of the shaft 6 that penetrates the quartz chamber 12 having the No. 1 and the rotary drive device 7 provided at the center of the bottom surface of the chamber 12 and has the tip inserted into the chamber 12. Have and.

The gas inlets 10 are, for example, eight gas inlets provided in a line on the upper surface of the chamber. First, the state at the time of deposition will be described.

The susceptor 1 has a holding portion 4 at the tip of the shaft 6.
The substrate holding surface 1a is held horizontally and upward during the deposition. At this time, the substrate 2 and the champer 1
By making the distance between the two upper surfaces close to each other by, for example, 2 cm, a uniform flow is formed on the substrate together with the gas introduction ports 10 arranged in a row. In the apparatus of this embodiment, the upper part of this chamber 12 becomes the deposition chamber 9. The susceptor 1 being deposited is rotated by the drive rotation device 7 at a constant speed, for example, 20 rpm.

As the substrate 2, a GaAs crystal wafer having a diameter of 75 cm was used, and a CdTe buffer layer was first deposited, and then a HgCdTe thin film was deposited. The source gas used was hydrogen gas at 1 atm as a carrier gas, and DMCd (dimethyl cadmium) was added at 10 ^-5 atm and D for deposition of the CdTe buffer layer.
IPTe (diisopropyl tellurium) was mixed at a partial pressure of 10 ⁻³ atm and used. For the subsequent deposition of the HgCdTe thin film, in addition to the source gas for the deposition of the CdTe buffer layer, metallic mercury is heated to 300 ° C. to supply mercury vapor,
An Hg partial pressure of 10 ^-2 atm was applied in the chamber. Board 2
Is heated by inductively heating the susceptor 1 with a high-frequency coil provided outside the chamber 12, and is maintained at, for example, 360 ° C. during deposition.

Under such conditions, both the CdTe buffer layer and the HgCdTe thin film were deposited at a growth rate of approximately 2.5 μm / hour. Next, the pretreatment before the deposition and the treatment after the deposition will be described.

The GaAs substrate 2 is fixed on the substrate holding surface 1a of the susceptor 1 by the substrate holder 1b. Then,
In the chamber 12, the susceptor 1 is turned over so that the substrate holding surface 1a faces downward. In such an operation, the substrate 2 is attached on the upper surface of the susceptor 1, and then the susceptor is inverted, which facilitates the operation of the substrate and reduces the adhesion of dust. The susceptor 1 can be inverted by rotating the shaft 6 by the rotation driving device 7 as described above. A nozzle 8 is provided near the substrate holding surface facing downward.

Next, the susceptor 1 is rotated by the rotation driving device 7 at, for example, 20 rpm, and hydrogen gas of 1 atm is supplied from the gas introduction port. Next, the susceptor 1 is heated by high frequency induction heating, and the substrate 2 is subjected to heat treatment for cleaning at 600 ° C. for 30 minutes. At this time, since the surface of the substrate 2 faces downward, elements evaporated from the surface do not reach the upper part of the chamber 12, which is the deposition chamber 9. Therefore, the inner wall surface of the deposition chamber 9 and the members exposed in the deposition chamber are not contaminated.

In this heat treatment, the temperature of the substrate 2 is 600
After the temperature is raised to 0 ° C., the surface of the substrate 2 is continuously irradiated with TBAs (tertiary butyl arsine) having a partial pressure of 10 ⁻³ atm from a nozzle 8 provided near the substrate holding surface.

Next, the substrate temperature is set to the deposition temperature, for example, 36
Cool down to 0 ° C and maintain. These temperature adjustments are performed by observing the heat radiation from the substrate surface by a radiation temperature type 13 provided at the lower end of the shaft 6 through the window 6 and returning the result to the high frequency output.

Next, the irradiation of TBAs is stopped, the rotation of the shaft 6 is accelerated to about 100 rpm, the susceptor 1 is inverted, and the substrate holding surface 1a is directed upward. The inversion operation is the same as described above. After that, the speed gradually slows down to 20
rpm.

After the temperature is stabilized after the inversion, the above-mentioned Cd
The Te buffer layer and the HgCdTe thin film are deposited. Then, the rotation of the shaft 6 is accelerated again, the susceptor 1 is inverted, and the substrate holding surface 1a is directed downward. As a result, it is possible to prevent dust from accumulating on the surface of the substrate 2 after the accumulation.

FIG. 3 is a sectional view of a vapor phase deposition apparatus according to another embodiment of the present invention, showing a horizontal vapor deposition apparatus. Referring to FIG. 3, the chamber of the apparatus of the present embodiment is a chamber body 1 composed of a quartz glass cylindrical tube having a left end closed tube and a right end open tube.
2A and a quartz cap 12B that fits into the open tube portion. A gas inlet 10A for introducing the raw material gas is opened at the center of the left sealed tube portion of the chamber body 12A. An exhaust port 11A is opened at the lower end of the cap 12B.

Susceptor 1 for holding substrate 2 and shaft 6
Clamping part 4, which supports susceptor 1 at the upper end, and shaft 6
The rotary drive unit 7 is arranged in the same manner as in the above-described first embodiment. The rotation driving unit 7 is provided in a region where a part of the bottom surface of the chamber body 12A is processed flat. Also, the temperature of the susceptor 1 can be measured from the lower end of the shaft 6 with the radiation temperature type 13, as in the first embodiment.

The substrate 2 being deposited is held on the upper end surface of the susceptor 1 and placed above the chamber body. During the heat treatment for cleaning the substrate 2, the susceptor 1 is turned over and the substrate 2 is held downward on the lower surface of the susceptor 1. A gas introduction pipe having a nozzle 8A that opens near the surface of the substrate 2 in this state and discharges TBAs is inserted from the lower left end of the chamber body 12A.

The operation of this embodiment is the same as that of the first embodiment. The deposition conditions are the same as in the first embodiment.

[0050]

According to the vapor deposition apparatus of the present invention, the substrate holding surface of the susceptor can be inverted during the deposition and at other times, so that the contamination of the deposition chamber by the impurity element evaporated from the substrate surface. Can be avoided, and a thin film having a high purity can be deposited.

Therefore, it greatly contributes to the performance improvement of the electronic device including the semiconductor circuit.

[Brief description of drawings]

FIG. 1 is a perspective view of a susceptor according to an embodiment of the present invention.

FIG. 2 is a sectional view of a vapor deposition apparatus according to an embodiment of the present invention.

FIG. 3 is a sectional view of a vapor deposition apparatus according to another embodiment of the present invention.

[Explanation of symbols]

 1 Susceptor 1a Substrate holding surface 1b Substrate holder 1c, 1d Cylindrical cam 1e Cylindrical part 2 Substrates 3c, 3d Contactor 4 U-shaped part 4a Bottom side 4c, 4d Branch 5 Window 6 Shaft 7 Rotation drive device 8, 8A Nozzle 9 Deposition chamber 10, 10A gas inlet 11, 11A exhaust port 12 chamber 12A chamber body 12B cap 13 radiation thermometer 14, 14A high frequency coil

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H01L 27/12 G 31/0264

Claims (3)

[Claims] 1. A deposition chamber includes a shaft (6) vertically and rotatably provided, and a susceptor (1) held by an upper end of the shaft (6) and having a substrate holding surface (1a) formed therein. In a vapor deposition apparatus, a cylinder part (1e) formed on the susceptor (1) and two rotations formed on a side surface of the cylinder part (1e) and having a central axis of the cylinder part (1e) as an axis of symmetry. The two cylindrical cams (1c, 1d) symmetrical to each other and the two cylindrical cams (1c, 1d) contact each other at both ends of the diameter of the cylindrical part (1e) to sandwich the cylindrical part (1e). Two contactors (3c, 3d) and one contactor (3c, 3d) for each branch of the fork formed at the upper end of the shaft (6)
And a holding portion (4) for holding the cylindrical portion (1e) held between the forks by the contacts (3c, 3d) so as to be rotatable around the horizontal straight line. , A rotation drive device (7) for applying a rotational acceleration to the shaft (6), and the center of gravity of the susceptor (1) is the shaft (6).
Is provided at a position where the center line of the cylindrical portion (1e) vertically hangs when the cylinder cam (1c, 1c, 1c) is stopped.
The cylindrical cam (1c, 1d) serves as a subordinate node and the contactors (3c, 3d) serve as a driving node for the susceptor (d) and the holding portion (4) according to the rotational acceleration of the shaft (6). 1)
A vapor phase deposition apparatus comprising a cylindrical cam device for vertically moving the cylinder. 2. The vapor deposition apparatus according to claim 1,
At the bottom side (4a) of the U-shaped portion (4), a temperature observation window (5) for introducing the heat radiation light from the susceptor (1) into the shaft (6) and leading it out from the lower end is provided. A vapor deposition apparatus characterized by the above. 3. The vapor deposition apparatus according to claim 1,
A vapor deposition apparatus, characterized in that a nozzle (8) for supplying a volatile component gas is provided in the vicinity of the substrate holding surface (1a) when the substrate (2) is heated and washed.