JPH09111446A - Sputtering apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the forming efficiency of coating of high quality, at the time of sputtering, by directly introducing a process gas into the space within shields including a sputtering region and enabling the exhaust of an out gas to the space outside of the shield.

SOLUTION: This sputtering device 100, is provided with shields 113 to 115 for preventing contamination in a coating forming chamber 104 and partition is executed into space A within the shields housing a wafer 106 and space B outside of the shields, and further a process gas and/or an atmospheric gas are directly introduced into the space A within the shields by gas flow inlets 128a and b. Simultaneously, by ventilation provided in the shield 115, the circulation of the gas between the space A within the shields and the space B outside of the shields is made free, and the gas in the space A within the shields is exhausted to the outside of the system by a cryopump connected with the space B outside of the shields. Thus, sputtering can always be executed under the fresh and sufficient atmospheric gas.

COPYRIGHT: (C)1997,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an apparatus used for film formation by sputtering.

[0002]

2. Description of the Related Art Reactive sputtering, which is one of the methods for obtaining a film of a metal compound, has a characteristic different from CVD which is also frequently used for forming a metal compound film.

For example, when a thin film of a metal compound such as TiN is to be formed, reactive sputtering is often used along with CVD. Reactive sputtering has various advantages such as a wide range of choices of substrates for film formation. The film formation by reactive sputtering is T
It is applied to compounds of metals such as i, Al and W and O, N and C.

In reactive sputtering of compounds of metals such as Ti, Al and W, about 6 × 10 ⁻³ Torr to about 5 × 1 is used.
Film formation is performed at a relatively low pressure in the range of 0 ⁻⁴ Torr.

FIG. 5 is a sectional view of an example of a conventional sputtering apparatus. As shown in FIG. 5, a conventional sputtering apparatus 500 includes a susceptor 508 for holding a wafer 506 inside a cylindrical chamber 504 surrounded by a chamber wall 502, and a sputtering for depositing on the wafer 506. A material target 510. On the back side of the target 510,
A magnet 512 for converging the discharge is arranged. Shield 51 to surround target 510
3 is installed in the chamber to prevent the sputtered particles from scattering and adhering to the chamber wall.

The conventional sputtering apparatus 500 is
It has one or more gas inlets 514 connected to the chamber wall 502. The gas inlet 514 is connected to a gas source, and in reactive sputtering, for example, a mixed gas of a process gas and an atmospheric gas is introduced into the chamber 504 through the gas inlet 514. Shield 51
3 has openings (not shown) in some places, and the atmosphere in the “space B” outside the shield flows into the “space A” inside the shield. That is, the process gas introduced into the space B inside the chamber 504 through the gas inlet 514 reaches the space A.

The substance constituting the target 510 sputtered by the application of electric power reacts with the process gas existing in the space A and is deposited on the wafer 506 as a compound of the target material. An opening (not shown) is also provided below the shield 513 so that the gas in the space A can be stored in the space B.
And then discharged to the outside of the chamber.

[0008]

As described above, in the conventionally used sputtering apparatus, the process gas is supplied to the space (space B) inside the chamber outside the shield for preventing the scattering of sputtered particles. However, it was difficult to supply a sufficient amount of process gas to the space (space A) in which sputtering was performed. Further, outgas containing water and the like volatilized from the surface of the device member is likely to stay in the space where sputtering is performed, which causes contamination in the sputtering region.

Further, since the shield 513 is generally close to the edge portion of the target 510, the magnet 5
Due to the magnetic field of 12, the electrons contained under the target escaped to the shield on the ground side, and the sputter energy was lost. All of these impeded the improvement of the film quality.

The present invention has been made in view of the above problems, and a sputtering apparatus capable of quickly discharging outgas from the sputtering region, efficiently maintaining plasma, and efficiently forming a high quality film. The purpose is to provide.

Another object of the present invention is to provide a sputtering apparatus capable of increasing the efficiency of reactive sputtering and forming a thin film having a uniform film quality.

[0012]

A sputtering apparatus according to the present invention includes a chamber for accommodating a target that is sputtered to release a substance for film formation and a wafer holding unit that holds a wafer to be filmed, and a chamber for the chamber. What is claimed is: 1.A sputtering apparatus comprising: a shield inner space including a target and a wafer; and a shield outer space, wherein the shield has an inlet connected to a gas supply means for supplying a gas. In addition, the gas is directly introduced into the inner space of the shield, the shield has a vent hole, and the gas is circulated between the inner space of the shield and the outer space of the shield, and the chamber is connected to a gas exhaust means for exhausting the gas. The gas in the space outside the shield is discharged to the outside of the chamber.

Another sputtering apparatus of the present invention includes a chamber having airtightness, a side surface accommodated in the chamber, and a sputtering surface which is one bottom surface and is sputtered to release a substance for film formation. A frustum-shaped, frustum-shaped or plate-shaped target, a wafer holding means for holding the film-forming wafer in the chamber facing the sputtering surface of the target, and the target in the chamber in the vicinity of the target. Surrounding the side surface of the target, extending in the direction from the target to the wafer holding means, and further surrounding the wafer holding means and surrounding the wafer holding means, and the inside of the chamber, a shield inner space including the target and the wafer, A shield consisting of one or more members, which is separated from the space outside the shield, and one or more shields, which are provided in the shield, directly guide the gas into the space inside the shield. An inlet for being connected to the inlet,
A gas supply means for supplying gas from the outside of the chamber to the inside of the shield inner space, one or more ventilation holes provided in the shield for allowing gas to flow from the inside of the shield space to the outside space of the shield, and connected to the chamber And a gas discharge means for discharging the gas in the shield outer space to the outside of the chamber.

In these sputtering apparatuses according to the present invention, the gas is directly introduced into the shield inner space surrounded by the shield and containing the target and the wafer, and the atmosphere in the shield inner space is changed to the shield outer space. By allowing easy circulation, the space inside the shield including the region where sputtering is performed is always filled with fresh gas.

Further, the sputtering apparatus of the present invention may be characterized in that the inflow port is formed in a portion where the shield is close to the target and surrounds the side surface of the target.

If the inflow port is formed in the portion surrounding the side surface of the target, the inflow port does not face the sputtering surface of the target, so that the probability of sputtered particles reaching the inflow port is extremely high. It becomes low. Therefore,
The clogging of the inlet due to the deposition of sputtered particles is prevented.

The sputtering apparatus of the present invention further comprises a magnet for forming a magnetic field between the target and the wafer holding means on the side of the target opposite to the wafer holding means side, and the shield is the target. Has a portion that extends in a direction away from the target side surface in a portion that surrounds the target side surface in the vicinity of the target side surface, and extends from the end point of the portion toward the target toward the wafer holding means, and the end portion of the sputtering surface of the target. It may be characterized in that a predetermined space is secured around the.

By securing a space around the edge of the sputtering surface of the target, the movement of electrons in the plasma generated between the target and the wafer holding means is not affected by the shield. Therefore, it is possible to generate and maintain plasma with energy efficiency.

[0019]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
The present invention will be described in detail. In the drawings, common elements are designated by the same reference numerals, and redundant description will be omitted.

FIG. 1 is a sectional view of an example of a sputtering apparatus according to the present invention. The cylindrical sputtering apparatus 100 includes a chamber 104 surrounded by a chamber wall 102.
Is provided. A susceptor 108 for holding the wafer 106 and a target 110 are provided in the chamber 104, and the wafer 106 is arranged to face the target 110 with a certain distance. On the back side of the target 110, the target 110 and the wafer 1
Magnet 112 for converging the discharge between
Is arranged. The bottom surface of the target 110 is disk-shaped. The bottom surface of this target 110 is a sputtering surface that is sputtered to emit particles of target material. The target 110 is installed so that the sputtering surface faces the susceptor 108. Target 11
The particles emitted from the zero sputtering surface are deposited on the surface of the wafer 106 held on the susceptor 108.

The sputtering apparatus 100 shown in FIG.
In the chamber 104 of, a shield for preventing contamination due to scattering of particles of the sputtered target material is
An upper shield 113, a middle shield 114,
The lower shield 115 is composed of three shields. The upper shield 113 is formed so as to be close to and surround the side surface of the target 110 and further extend in the direction from the target 110 toward the susceptor 108. The structure and role of the middle shield 114 will be described later. The lower shield 115 is close to and surrounds the susceptor 108. The upper shield 113, the middle shield 114, and the lower shield 115 are made of SUS.
It is made of 304. However, the material of these shields is S
It may be US306 or titanium. The structure of these shields will be described in detail later.

The inside of the chamber is divided by these shields into two spaces, that is, a space A which is a space inside the shield and a space B which is a space outside the shield. As shown in FIG. 1, in the space A where the wafer 106 and the target 110 are arranged, electric power is applied between the target 110 and the wafer 106, and the target material forming the target 110 is sputtered onto the wafer 106. A thin film is deposited on. The target material is typically W,
Ti, Al alloy, WSi, TiW, MoSi, Si, C
It is a substance such as u. At this time, when reactive sputtering is performed in which a compound of the target material is formed by reacting with the sputtered target material and a thin film of this compound is formed on the wafer 106, the compound is formed by reacting with the target material. Gas is circulated between the target 110 and the wafer 106. For example, when depositing a TiN thin film on the wafer 106, the Ti
Is used to flow N ₂ gas into the space A as a process gas. At this time, an atmosphere gas such as Ar is also circulated together with the process gas N ₂ . When performing normal sputtering that does not involve a chemical reaction, instead of reactive sputtering, only an atmospheric gas such as Ar gas for plasma generation may be passed.

The susceptor 108 is equipped with a heater for heating the wafer 106 to a desired temperature. However, when sputtering is performed in a chamber where the pressure is low, the efficiency of heating by the heater becomes low, so that the heater is heated. A heater gas such as argon is supplied to the susceptor 108 via the gas introduction pipe 146, and the heater gas heated by the heater is circulated as a medium for heating into a slight gap between the wafer 106 and the susceptor 108. . Usually, the heater gas is preferably the same gas as the atmospheric gas for sputtering, but other inert gas may be used.

FIG. 2 is a sectional view near the upper shield 113 of the sputtering apparatus 100 shown in FIG. The structure of the shield will be described below with reference to FIGS. 1 and 2, and the mechanism of gas flow in the sputtering region in the present invention will be clarified. As shown in FIG. 2, the upper shield 113 is fixed to the periphery of the target 110 by screws 120 together with the block 122. Here, the upper shield 113 has a cylindrical shape in which the bottom surface is close to and covers the side surface of the disk-shaped target 110. For convenience of illustration, only two screws 120 for fixing the upper shield 113 are shown in FIG. 1, but the upper shield 113 is fixed to the block 122 at eight points along the circumference.

As shown in FIGS. 1 and 2, a block 123 below the block 122 is provided with a gas introduction section 124 for introducing a process gas and an atmosphere gas. A conduit 126 connected to an external gas source (not shown) that supplies a mixed gas of a process gas and an atmospheric gas is connected to the gas introduction unit 124. Conduit 1
The stop 26 is equipped with a stop valve 130 for adjusting the supply of gas. The conduit 126 is the gas introduction unit 1.
A gas inlet 128a opened inside the block 123 and a gas inlet 128b penetrating the inside of the upper shield 113 (both shown by dotted lines in both FIGS. 1 and 2) are connected via 24. That is, the mixed gas of the process gas and the atmospheric gas passes through the conduit 126 and passes through the gas introducing unit 1.
24, through the gas inlets 128a, 128b,
It is supplied to the space A near the outside of the target 110.
Such gas supply lines extending from the conduit 126-the gas introduction portion 124-the gas inlet 128a-the gas inlet 128b are evenly arranged in 32 sets on the circumference of the cylinder of the chamber 104 at appropriate intervals. . Therefore, the cylindrical upper shield 113 has 32
The gas inlets 128b are regularly arranged, and 32 vents are directed into the space A.

In this way, 32 gas inlets 128b
Since the upper shield 113 is provided with, a sufficient amount of process gas is supplied into the space A. In addition, 32 gas inlets 12 evenly arranged on the circumference
Since the gas is supplied radially inward from the space 8b into the space A, the concentration distribution of the process gas in the space A does not occur.

Further, in the operation under the low pressure condition, it is necessary to quickly exhaust the outgas such as air and water slightly adsorbed on the surface of the member of the apparatus from the space A. For this reason,
The lower shield 115 has a structure having a large number of vent holes (openings) as shown by the dotted line in FIG. For example, like the side surface of the lower shield 115 shown in FIG. 3, a total of eight relatively large openings 134 are formed around the cylindrical lower shield 115, so that the exhaust from the space A to the space B is easy. I have to. In such a case, particles or the like sputtered from the opening 134 (vent) of the lower shield 115 scatters to the outside of the lower shield 115, and for the purpose of preventing this, it is shown in FIGS. 1 and 2. As described above, the middle shield 114 is installed. And middle shield 114 and lower shield 1
The shape and arrangement of the middle shield 114 so that the conductance of the exhaust path constituted by 15 is sufficiently large,
The opening 134 of the lower shield 115 may be adjusted.

As described above, a means for directly supplying gas is provided to the space A in which sputtering is performed, and
By sufficiently increasing the conductance from the space A to the space B for exhaustion, new gas is always present in the space A, and outgas containing water and the like volatilized from the surface of the device member is promptly discharged to the space B. Is discharged to the.

To exhaust gas from the chamber 104, the chamber 104 is provided with a gas outlet 140, as shown in FIG. The gas exhaust port 140 is connected to the space B of the chamber 104. The gas exhaust port 140 is connected to the cryopump 142 to exhaust the gas in the space B to the outside. Therefore, the middle shield 11
4 and the lower shield 115, the outgas exhausted to the space B through the exhaust path configured with an appropriate conductance is supplied to the space B by the cryopump 142.
Be excluded from. In the space B of the chamber 104,
The pressure gauge 144 is connected and the pressure in the space B is monitored. Once the conductance from the space A to the space B is determined, the pressures of the space A and the space B are adjusted by supplying the gas flow rate and the exhaust amount with the stop valve 130 and the cryopump 142.

As described above, since a sufficient amount of gas is always uniformly supplied to the space A and sufficient flowability of the gas from the space A to the space B is secured, the sputtering of the space A is performed. In the area, it is always possible to carry out sputtering in the presence of fresh gas. Therefore, outgas that causes pollution is not retained in the chamber, and
In particular, in reactive sputtering, the process gas concentration in the sputtering region can be kept uniform, so that the film quality is improved, and so on.

The gas inlets for supplying gas to the region (space A) in which sputtering is performed may be arranged differently from the gas inlets 128a and 128b shown in FIG. FIG. 4 is a partial cross-sectional view of a sputtering apparatus 400 with alternative gas inlets 428a and 428b according to the present invention. The sputtering apparatus 1 shown in FIG. 2 in the sputtering apparatus 400 shown in FIG.
The only difference from 00 is the arrangement of the vent holes. As shown in FIG. 4, in the sputtering apparatus 400, the gas inlet 428b that communicates with the gas inlet 428a in the lower block 423 and penetrates the upper shield 413 is a clearance between the side surface of the target 110 and the upper shield 413. Formed towards. In the case of the arrangement of the gas inlet 128b of FIG. 2, there is a problem that sputtered particles from the target 110 adhere to the outlet of the gas inlet 128b. However, as shown in FIG. 4, if the shield 413 has the gas inlet port 428b formed in the portion close to the target 110 and surrounding the side surface of the target 110, the shield 413 is knocked out from the surface of the target 110. Moreover, since the sputtered particles do not reach the outlet of the gas inflow port 428b, problems such as contamination and blockage due to attachment of the sputtered particles are prevented.

Gas inlet 128 as shown in FIG.
a, b and a gas inlet 428a, as shown in FIG.
Which of b is used is determined in consideration of the type of film to be formed, the state of particle generation that causes contamination, and the like.

Further, as shown in FIGS. 1, 2 and 4, the upper shield 113 (or 413) has a shape which extends from the front side of the surface of the target 110 toward the direction away from the target. . This is compared with the prior art. In the shield 513 of the conventional sputtering apparatus 500 shown in FIG.
It extends vertically downward from the vicinity of the periphery of 0, and the area between the target 510 and the shield 513 is narrow. on the other hand,
The upper shield 113 or 413 according to the invention is
Since the target 110 has a portion that is carved near the outer circumference, a wide area is secured near the outer circumference of the target 110 as shown in FIGS. 1, 2, and 4.

As shown in FIG. 2, the device 10 of the present invention.
A magnetic field like a curved line with an arrow 132 is formed by the magnet 112 below the target 110 of 0. During sputtering, the magnetic and electric fields cause the electrons to undergo Lorentz force and bend their trajectories, trapping them in a region below the target. In this region, the collision density with the atmospheric gas such as Ar for ionization becomes high. However, if the shield having the role of the ground is in the immediate vicinity of the periphery of the target, the electrons are likely to escape toward the upper shield 113 and the middle shield 114, and the kinetic energy of the electron is reduced as a whole. However, as represented by the shape of the upper shield 113 in FIGS. 1 and 2, a large space is provided around the edge of the sputtering surface of the target 110 so that the kinetic energy of electrons is not reduced.

By providing a large area near the outer circumference of the shield as described above, it is possible to efficiently use the sputtering energy. Therefore, the discharge pressure can be lowered, and the coverage can be further improved.

As described above, the apparatus of the present invention can be used particularly for reactive sputtering,
A very advantageous effect can be obtained. On the other hand, the apparatus of the present invention is used for PVD such as ordinary sputtering in which only an atmospheric gas such as Ar for plasma is circulated without using a process gas for chemical reaction, and even if it is used for an outgas that causes contamination. It provides significant effects such as effective removal and plasma efficiency and stabilization.

Although the preferred embodiment of the apparatus according to the present invention has been described above, the present embodiment can be variously modified according to the present invention. For example, in FIG. 1, the shield is composed of three upper shields, middle shields, and lower shields, but may be composed of one or two shields. In this case, the shield can have at least one or more gas inlets to directly introduce gas into the shield inner space, and the shield can have at least one or more exhaust openings from the shield inner space. Appropriate conductance should be given to the space outside the shield. Also in this case, it is preferable that the shield has a portion that is separated from the target near the outer periphery of the target, and has a shape that provides a constant space around the end portion of the sputtering surface of the target.

Further, in the above description of the preferred embodiment, the single-wafer type PVD apparatus for processing the wafers one by one has been described. However, a gas having a means for introducing gas is used to shield the gas inside the shield. The configuration of directly introducing the same into the sputtering region of (1) provides the same effect as described above even when used in a batch type PVD apparatus or the like that processes a plurality of wafers.

[0039]

As described above in detail, in the sputtering apparatus of the present invention, the shield provided with the means for introducing gas is used to directly introduce the gas into the space inside the shield including the sputtering region, and to shield the shield. The atmosphere inside can be easily distributed to the space outside the shield. Therefore, the space inside the shield is always filled with fresh gas and outgas is prevented from staying.

Further, in the present invention, the shield has a shape extending in the direction away from the side surface of the target, and a predetermined space is secured around the end of the sputtering surface of the target. Therefore, loss of electron kinetic energy is prevented, and plasma is efficiently generated and maintained.

Therefore, a sputtering apparatus capable of efficiently forming a high quality film is provided.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a sputtering apparatus according to the present invention.

FIG. 2 is a cross-sectional view around the upper shield of the sputtering apparatus shown in FIG. 1, showing a gas inlet arrangement.

FIG. 3 is a side view of the lower shield showing the placement of the vents.

FIG. 4 is a cross-sectional view around the upper shield, which is different from that of FIG. 2, and shows another gas inlet arrangement.

FIG. 5 is a cross-sectional view of a conventional sputtering device.

[Explanation of symbols]

100, 400 ... Sputtering apparatus, 102 ... Chamber wall, 104 ... Chamber, 106 ... Wafer, 108 ... Susceptor, 110 ... Target, 112 ... Magnet, 1
13, 413 ... Upper shield, 114 ... Middle shield, 115 ... Lower shield, 120 ... Screw, 12
2, 123, 422, 423 ... Block, 124, 42
4 ... Gas introduction part, 126 ... Conduit, 128a, b, 428
a, b ... Gas inlet, 130 ... Stop valve, 132
... arrow, 134 ... vent, 140 ... gas exhaust, 142
... cryopump, 144 ... pressure gauge, 146 ... heater gas introduction pipe.

Claims (4)

[Claims] 1. A chamber for accommodating a target which is sputtered to release a substance for film formation and a wafer holding means for holding a wafer to be filmed, and the inside of the chamber including the target and the wafer. A shield inner space and a shield defining a shield outer space, wherein the shield has an inflow port connected to a gas supply means for supplying a gas, and the shield inner space Gas is directly introduced into the shield, the shield has a vent hole, the gas is circulated between the shield inner space and the shield outer space, the chamber is connected to a gas exhaust means for exhausting the gas, A sputtering apparatus, which discharges the gas in the space outside the shield to the outside of the chamber. 2. A cone shape having an airtight chamber, a side surface, a side surface, and a sputtering surface which is one bottom surface and is sputtered to release a substance for film formation. A trapezoidal or plate-shaped target, a wafer holding means for holding the film-forming wafer in the chamber facing the sputtering surface of the target, and in the chamber, the target in proximity to the target. Surrounding the side surface, extending in the direction from the target to the wafer holding means, and further surrounding and proximate to the wafer holding means, the interior of the chamber containing the target and the wafer. A shield consisting of one or more members, which is divided into a shield inner space and a shield outer space; and one or more shields provided on the shield. A gas inlet for directly introducing gas into the inner space of the chamber, gas supply means connected to the inlet for supplying gas into the inner space of the shield from outside the chamber, and one or more for the shield A vent is provided which allows gas to flow from the inside space of the shield to the outside space of the shield, and a gas discharge means which is connected to the chamber and discharges the gas inside the outside space of the shield to the outside of the chamber. A sputtering apparatus characterized by the above. 3. The sputtering apparatus according to claim 2, wherein the inflow port is formed in a portion where the shield is close to the target and surrounds a side surface of the target. 4. A magnet for forming a magnetic field between the target and the wafer holding means is further provided on a side of the target opposite to the wafer holding means side, and the shield is provided on the target. In a portion that closely surrounds the target side surface, there is a portion that extends in a direction away from the target side surface, and further extend from the end point of the portion in the direction from the target toward the wafer holding means, The sputtering apparatus according to claim 2 or 3, wherein a predetermined space is secured around the edge of the sputtering surface.