JP4833088B2 - High temperature reflow sputtering equipment - Google Patents

Description

  The present invention relates to a technique of high-temperature reflow sputtering in which a metal material is embedded in a hole formed on the surface of a substrate.

  Sputtering technology for creating a predetermined thin film on the surface of a substrate by sputtering a target is actively used in the production of semiconductor integrated circuits. In many cases, a substrate such as a semiconductor wafer on which a thin film is formed by sputtering has fine holes, and it is necessary to form a thin film in the fine holes. For example, in a 256 megabit to 1 gigabit DRAM (Dynamic Random Access Memory), a film is formed in a groove or hole (generally referred to as a hole in this specification) having a width or diameter of about 0.25 μm to 0.18 μm according to a design rule. It is becoming necessary to do.

As a technique using sputtering for film formation in such a hole, a technique of high-temperature reflow sputtering in which a metal material is embedded in the hole is conventionally known. FIG. 6 is a front view showing a schematic configuration of a conventional high-temperature reflow sputtering apparatus that performs such high-temperature reflow sputtering.
The high-temperature reflow sputtering apparatus shown in FIG. 6 includes a sputtering chamber 4 provided with an exhaust system 41, a target 42 provided so as to expose a surface to be sputtered in the sputtering chamber 4, and sputtering for sputtering the target 42. A power source 43, a substrate holder 44 for placing the substrate 9 at a predetermined position in the sputtering chamber 4 where the material of the target 42 released by sputtering reaches, and a predetermined sputtering discharge gas are introduced into the sputtering chamber 4. A discharge gas introduction system 45 and a heater 441 provided in the substrate holder 44 are provided so as to heat the substrate 9 to a predetermined temperature.

The target 42 is made of metal such as aluminum and is attached to the sputter chamber 4 via an insulating material 421. The sputter power supply 43 is configured to apply a negative high voltage to the target 42. When a sputter discharge gas such as argon is introduced into the sputter chamber 4 by the discharge gas introduction system 45 and a negative high voltage is applied to the target 42, the substrate holder 44 and the walls of the sputter chamber 4 that are at ground potential A direct current electric field is set between the two and a sputter discharge is generated by the direct current electric field. The metal material particles (usually in an atomic state, hereinafter referred to as sputtered particles) released from the target 42 by the sputtering discharge reach the substrate 9 and deposit a thin film of a predetermined metal material. Note that the distance between the target 42 and the substrate 9 in this apparatus is 60 mm.
On the other hand, heat from the heater 441 is applied to the substrate 9 via the substrate holder 44, and the substrate 9 is heated to a predetermined temperature. The thin film deposited on the surface of the substrate 9 is reflowed (fluidized) by the heat of the substrate 9 and flows into fine holes. As a result, the metal material is buried in the holes, and the surface of the substrate 9 is flattened.
Japanese Patent Application Laid-Open No. 08-107069 JP 09-228040 A

In the conventional high-temperature reflow sputtering described above, the substrate is heated from about 400 ° C. to about 500 ° C. The higher the temperature of the substrate during film formation (hereinafter referred to as film formation temperature), the higher the fluidity of the metal material, and the metal material can be easily embedded in the holes.
However, by performing the treatment at such a high temperature, the crystal growth of the metal material is accelerated and the grain size is increased. When the grain size is increased, there is a problem that irregularities are formed on the surface of the substrate, which makes it difficult to perform alignment in the subsequent photolithography. In addition, as the grain size increases, the problem of electromigration becomes obvious.

  Further, in the manufacture of a device having a multilayer wiring structure, an aluminum film may already be formed as a first layer wiring on a silicon substrate. In this case, when high-temperature reflow sputtering of aluminum is performed for the second layer wiring, these melt at a temperature of about 400 ° C. to 500 ° C. at the interface between the already formed first layer aluminum film and silicon. Then, by cooling, aluminum and silicon are eutectic, resulting in “disappearance of aluminum” which becomes an aluminum-silicon alloy. Such disappearance of aluminum causes defects and defects such as circuit disconnection and increased wiring resistance.

  In order to prevent such a problem from occurring, it is conceivable to perform high-temperature reflow sputtering at 400 ° C. or lower. However, when high-temperature reflow sputtering is performed at such a low temperature of 400 ° C. or lower, for example, about 200 ° C., the metal material cannot be sufficiently reflowed, and voids called voids are generated in the holes. If a void is generated in the hole, the circuit is disconnected or a defect such as an increase in wiring resistance is caused.

  The invention of the present application has been made to solve the above-described problems, and an object of the present invention is to provide a high-temperature reflow sputtering technique that can sufficiently fill a metal material in a hole even when the substrate is heated at a lower temperature. It is said.

In order to solve the above-mentioned problems, the present invention is a chamber that is airtightly connected around the separation chamber and the separation chamber, and in which the substrate is temporarily retained when the substrate is taken in and out of the atmosphere side. A high-temperature reflow sputtering apparatus that includes a load lock chamber and a plurality of processing chambers hermetically connected around the separation chamber and embeds a metal material in fine holes formed on the surface of the substrate, One of the plurality of processing chambers is a sputtering chamber, and the sputtering chamber exhausts the inside of the sputtering chamber, a substrate holder for holding the substrate, and electrostatically attracts the substrate to the substrate holder. Electrostatic adsorption mechanism and the electrostatic adsorption An electrostatic adsorption mechanism control unit that controls the structure, a heater provided in the substrate holder, a distance change mechanism that changes the distance between the substrate and the target, and a distance change mechanism control unit that controls the distance change mechanism And a target holder for holding the target, wherein the electrostatic adsorption mechanism control unit creates a thin film of a metal material on the side surface and bottom surface of the hole of the substrate during the operation of the heater. In the method, the electrostatic adsorption mechanism is not operated, the heat transfer efficiency between the substrate and the substrate holder is made poor, and a thin film of metal material is further deposited and reflowed after the first step. In the second step of embedding the metal material in the hole on the substrate, control is performed to improve the heat transfer efficiency between the substrate and the substrate holder by operating the electrostatic adsorption mechanism. The distance changing mechanism control unit controls the separation chamber so that the distance between the target and the substrate is longer than the distance between the target and the substrate in the second step in the first step. Includes a cooling panel provided so that the surface is exposed to the internal space of the separation chamber, and a refrigerator that cools the cooling panel to 130K to 50K.
The invention of the present application is a separation chamber and a load lock chamber that is airtightly connected to the periphery of the separation chamber and is a chamber in which the substrate is temporarily retained when the substrate is taken in and out of the atmosphere side, A high-temperature reflow sputtering apparatus that embeds a metal material in a fine hole formed on a surface of a substrate, the plurality of processing chambers being hermetically connected around the separation chamber. Two are a first sputtering chamber and a second sputtering chamber. The first sputtering chamber includes an exhaust system for exhausting the inside of the first sputtering chamber, a first substrate holder for holding a substrate, and a first substrate holder. A first target holder for holding one target, The second sputtering chamber has an exhaust system for exhausting the inside of the second sputtering chamber, a second substrate holder for holding the substrate, and electrostatically adsorbs the substrate to the second substrate holder. An electrostatic adsorption mechanism for controlling the electrostatic adsorption mechanism, an electrostatic adsorption mechanism control unit for controlling the electrostatic adsorption mechanism, a heater provided in the second substrate holder, and a second for holding the second target A distance between the substrate and the first target is longer than a distance between the substrate and the second target in the second sputtering chamber. A first step of forming a thin film of a metal material on the side and bottom surfaces of the hole of the substrate is performed, and the electrostatic adsorption mechanism control unit is reflowed. In the second step of embedding a metal material in the hole on the substrate, the separation is performed by controlling the electrostatic transfer mechanism to improve the heat transfer efficiency between the substrate and the substrate holder during the operation of the heater. The chamber includes a cooling panel provided such that the surface is exposed to the internal space of the separation chamber, and a refrigerator that cools the cooling panel to 130K to 50K.

As described below, according to the invention of claim 1 or 6 of the present application, even when the substrate is heated at a lower temperature, the metal material can be sufficiently embedded in the hole. For this reason, it is possible to effectively embed the metal material in the hole while avoiding problems such as an increase in grain size that occurs when performing high-temperature processing. Furthermore, since the residual impurity gas in the separation chamber is effectively removed, the quality of high-temperature reflow sputtering in the sputtering chamber can be further improved.
According to the first aspect of the invention, since the first step and the second step can be performed in one sputter chamber, only one sputter chamber is required, and the cost of the apparatus is reduced.
According to the invention of claim 6, since the first step and the second step can be performed simultaneously in different sputtering chambers, the tact time can be shortened and the productivity can be improved.
According to the invention of claim 2 , 4 , 6, or 8, since the cooling panel is processed to prevent corrosion, corrosion does not occur even if moisture in the separation chamber is continuously removed.

Hereinafter, the best mode for carrying out the present invention will be described.
FIG. 1 is a schematic plan view of a high-temperature reflow sputtering apparatus according to an embodiment of the present invention.
The high-temperature reflow sputtering apparatus shown in FIG. 1 is a multi-chamber type apparatus, and includes a separation chamber 1 disposed in the center and a plurality of processing chambers 2, 3, 4, 8, which are hermetically connected around the separation chamber 1. The chamber arrangement is composed of 81 and two load lock chambers 5. Each chamber 1, 2, 3, 4, 5, 8, 81 is provided with a dedicated or dual-purpose exhaust system (not shown), and is exhausted to a predetermined pressure. A gate valve 6 is provided at a connection location between the chambers.

In the separation chamber 1, a transport robot 11 is provided as a transport mechanism for transporting the substrate 9 between the chambers. As the transfer robot 11, an articulated robot is used. The transfer robot 11 takes out the substrates 9 one by one from any one of the load lock chambers 5 and sends them to the respective processing chambers 2, 3, 4, 8, 81 for sequential processing. It returns to one of the load lock chambers 5.
An autoloader 7 is provided outside the load lock chamber 5. The autoloader 7 takes out the substrates 9 one by one from the external cassette 62 on the atmosphere side, and stores them in the in-lock cassette 51 in the load lock chamber 5.

  One of the plurality of processing chambers 2, 3, 4, 8, 81 is a sputtering chamber 4 in which holes on the surface of the substrate 9 are embedded by high-temperature reflow sputtering. Other than this, a preheating chamber 2 for preheating the substrate 9 before sputtering, a pretreatment etching chamber 3 for performing pretreatment etching for removing a natural oxide film or a protective film on the surface of the substrate 9 before sputtering, a high temperature This is a base film creation chamber 8 for creating a base film before film formation by reflow sputtering.

FIG. 2 is a schematic front sectional view of the sputtering chamber 4 in the high-temperature reflow sputtering apparatus shown in FIG. The sputter chamber 4 that forms the main part of the sputtering apparatus will be described with reference to FIG.
The sputter chamber 4 is an airtight container having a gate valve 6 and is electrically grounded. The inside of the sputter chamber 4 is evacuated to about 10 ⁻⁸ to 10 ⁻⁹ Torr by an exhaust system 41. The exhaust system 41 includes a plurality of stages of vacuum pumps such as a turbo molecular pump and a cryopump, and is provided with an unillustrated exhaust speed regulator such as a variable orifice.
The sputter chamber 4 is provided with a discharge gas introduction system 45 for introducing a predetermined sputter discharge gas so that a gas having a high sputtering rate such as argon can be introduced into the chamber at a predetermined flow rate. . Specifically, the discharge gas introduction system 45 includes a gas cylinder 451 storing a sputtering discharge gas such as argon, a pipe 452 connecting the sputter chamber 4 and the gas cylinder 451, a valve 453 provided in the pipe 452, and a flow rate adjustment. Mainly composed of a container 454.

A target 42 is provided in the sputtering chamber 4 so as to expose the surface to be sputtered. The target 42 is formed of a metal material, for example, aluminum, embedded in the hole on the surface of the substrate 9. The target 42 is attached to the sputter chamber 4 through a target holder 421 and an insulator 422 so as to hermetically close the upper opening of the sputter chamber 4.
A sputtering power source 43 for sputtering the target 42 is connected to the target 42. The sputtering power source 43 is configured to apply a negative DC voltage of about 400 to 600 V to the target 42. When the sputtering power supply 43 is operated in a state where the gas is introduced by the discharge gas introduction system 45, the gas is discharged and the target 42 is sputtered. In addition, when sputter discharge is maintained only by ionization of sputtered particles emitted from the target 42, gas may not be introduced.

A magnet mechanism 48 is provided behind the target 42. The magnet mechanism 48 achieves magnetron discharge. Specifically, the magnet mechanism 48 includes a central magnet 481, a peripheral peripheral magnet 482 surrounding the central magnet 481, and a plate-like yoke 483 to which the central magnet 481 and the peripheral magnet 482 are fixed. Between the center magnet 481 and the peripheral magnet 482, an arch-shaped magnetic field line 484 that penetrates the target 42 is set. Electrons are confined in a region surrounded by the magnetic force lines 484 and the surface to be sputtered of the target 42, and neutral gas molecules are ionized with high efficiency. For this reason, sputter discharge is maintained efficiently, and many sputtered particles are released, so that a high deposition rate can be obtained.
Further, the direction of the DC electric field set by the sputtering power source 43 is perpendicular to the surface to be sputtered of the target 42. Accordingly, the magnetic field and the electric field are orthogonal to each other in the vicinity of the top of the arched magnetic field line 484, and a magnetron discharge is achieved. That is, electrons move in a magnetron motion and circulate around the center axis of the target 42 to further improve the efficiency of sputtering discharge.

Further, a substrate holder 44 for placing the substrate 9 is provided in the sputter chamber 4 at a position where the material of the target 42 released by sputtering reaches. A heater 441 such as a resistance heating method is embedded in the substrate holder 44. As the heater 441, a radiation heating type heater may be provided in the substrate holder 44.
The substrate holder 44 is provided with an electrostatic adsorption mechanism 49 for bringing the substrate 9 into contact with good thermal contact. The electrostatic adsorption mechanism 49 mainly includes an adsorption electrode 492 embedded in a dielectric block 491 provided as a part of the substrate holder 44, and an adsorption power source 493 that applies a DC voltage between the adsorption electrodes 492. It is configured.

The dielectric block 491 is bonded to the substrate holder 44 with good adhesion. The surface of the dielectric block 491 is a mounting surface on which the substrate 9 is mounted, and a plurality of recesses 494 are formed on this surface. A pressurization gas introduction system 495 that introduces a pressurization gas is connected to the recess 494.
The suction power supply 493 is configured to apply a voltage of, for example, about 200 to 800 V between the pair of suction electrodes 492. This voltage causes dielectric polarization in the dielectric block 491 and induces static electricity on the surface. The static electricity causes the substrate 9 to be electrostatically attracted to the dielectric block 491. As a result, the adhesion of the substrate 9 to the substrate holder 44 is improved, and heat from the heater 441 is efficiently transmitted to the substrate 9.
Further, as a result of the gas being introduced into the recess 494 by the pressurization gas introduction system 495, the pressure in the recess 494 increases. For this reason, the heat transfer efficiency between the substrate holder 44 and the substrate 9 is improved, and the heating efficiency of the substrate 9 is increased. The pressurization gas introduction system 495 introduces a gas such as helium having good heat transfer efficiency.
A major feature of the apparatus of this embodiment is that the substrate holder 44 is provided with a distance changing mechanism 46 for changing the distance between the target 42 and the substrate 9. More specifically, the substrate holder 44 is supported by the support column 442. The distance changing mechanism 46 includes a holding plate 463 that holds the lower end of the column 442, a driven body 464 that fixes the holding plate 463, a ball screw 461 that drives the driven body 464, and a motor 462 that rotates the ball screw 461. And is composed mainly of.

The driven body 464 is a cylindrical member having an inner diameter that matches the outer diameter of the ball screw 461. The inner surface of the driven body 464 is threaded with high accuracy and meshes with the ball screw 461. Further, the driven body 464 is prevented from rotating by a rotation stopper (not shown).
When the ball screw 461 is rotated by the motor 462, the rotational force is transmitted to the driven body 464. Since the driven body 464 is prevented from rotating by a rotation stopper (not shown), it only moves up and down. As a result, the support column 442 moves up and down via the holding plate 463 fixed to the driven body 464, and the substrate holder 44 also moves up and down accordingly. Further, since the target 42 is fixed in the sputtering chamber 4, the distance between the substrate 9 placed on the substrate holder 44 and the target 42 can be changed by the operation of the distance changing mechanism 46 as described above. It has become.

In the apparatus of this embodiment, a control unit (not shown) that controls the entire apparatus is provided. The control unit is configured to control each component such as the distance changing mechanism 46 and the sputtering power source 43.
The distance changing mechanism 46 and a control unit (not shown) for controlling the distance changing mechanism 46 according to the present embodiment are provided in association with the apparatus of the present embodiment performing two-stage film formation. The two-stage film formation is a technique found by the inventors of the present application in an attempt to lower the temperature of the substrate (hereinafter referred to as film formation temperature) when performing high-temperature reflow sputtering. This point will be described with reference to FIGS. FIG. 3 is a diagram showing a problem when the film formation temperature is lowered without performing the two-stage film formation, and FIG. 4 is a diagram showing a film formation state when the two-stage film formation is performed.

First, the case where the two-stage film formation is not performed will be described with reference to FIG. As described above, the high-temperature reflow sputtering is a technique in which a thin film is deposited on the surface of the substrate 9 on which the holes 90 are formed by sputtering, and the substrate 9 is heated to reflow the thin film and embedded in the holes. At this time, the reflowed thin film (hereinafter referred to as reflow thin film) 91 tends to remain at the edge of the opening of the hole 90 due to the influence of the interfacial tension or the like. In this case, as shown in FIG. 3A, the reflow thin film 91 stays on the edge of the opening so that the reflow thin film 91 rises as shown in FIG. 3A. In addition, a thin film is initially deposited on the inner surface of the hole 90, but as a result of the substrate 9 being exposed to a high temperature, the thin film is interrupted at the side of the hole 90.
Even if the deposition amount of the thin film is increased by continuing the sputtering, only the reflow thin film 91 that rises and stays at the edge of the opening increases and does not flow into the hole 90. As a result, the opening is blocked by the reflow thin film 91, and even if it seems that the filling of the metal material into the hole 90 is completed, the void is formed in the hole 90 as shown in FIG. A cavity 92 called "is generated. When the void 92 is formed, when a metal material is embedded as a wiring, the wiring is disconnected and a fatal element defect is caused.

When the film forming temperature is raised to a certain degree, the fluidity of the reflow thin film 91 is improved, so that the reflow thin film 91 staying at the edge of the opening of the hole 90 can be poured into the hole 90, thereby forming the voids. It can be suppressed to some extent. However, increasing the film formation temperature causes the above-described problems such as an increase in grain size.
In order to prevent the generation of the void 92, it is only necessary to prevent the reflow thin film 91 from staying at the edge of the opening of the hole 90. The retention of the reflow thin film 91 is caused by the interfacial tension of the reflow thin film 91 itself, but it is considered that the influence of the affinity (wetting property) with the base surface is also great. That is, the reflow thin film 91 is made of a metal such as aluminum, and the surface of the hole 90 is made of a different material such as silicon or silicon oxide. Generally, the affinity for the surface of different materials is low, and it is difficult to flow along the surface. If the reflow thin film 91 flows on the surface of the same material, the affinity is high, so that the residence at the edge of the opening of the hole 90 should be reduced.

In order for the reflow thin film 91 to flow on the surface of the same material, a thin film of the same material may be formed in advance on the surface in the hole 90. From such a view, the inventor of the present application is divided into two steps of high-temperature reflow sputtering, and as shown in FIG. 4 (A), first, a thin film 93 of a metal material is first formed thinly on the inner surface of the hole 90. (Hereinafter, the film created in this step is referred to as “base thin film”), and after the first step, as shown in FIGS. 4B and 4C, a metal material thin film is further deposited. Then, the temperature of the substrate 9 is raised and reflowed to complete a two-stage film forming method for performing the second step of embedding a metal material in the hole 90.
In the first step, it is important to lower the film formation temperature so that the deposited base thin film 93 does not reflow. If the film forming temperature is increased to such an extent that the base thin film 93 is reflowed, the base thin film 93 is interrupted on the side surface of the hole 90 as shown in FIG. When the break occurs, the reflow thin film 91 must flow over the underlying surface of the hole 90, so that the fluidity is lowered and voids are likely to be generated.

  The major feature of the apparatus of this embodiment is that the distance between the target 42 and the substrate 9 (hereinafter referred to as the TS distance) is longer than the conventional distance in the first step of the two-stage film formation. . Specifically, the control unit operates the motor 462 of the distance changing mechanism 46 to perform control so that the distance between the substrate holder 44 and the target 42 is a long first distance in the first step, and the second step. In the process, the distance between the substrate holder 44 and the target 42 is controlled to be a second distance shorter than the first distance.

The situation when the TS distance is changed will be described with reference to FIG. FIG. 5 is a schematic diagram when the TS distance is changed.
When the distance between the target 42 and the substrate 9 is increased from L1 to L2, the area of the sputtering surface of the target 42 that can be seen from one point P in the hole 90 is larger in the case of L2 than in L1. (S1 <S2). Since the area (S1, S2) of the surface to be sputtered of the target 42 is the area of the sputtered particle emission portion that can reach one point P in the hole, the point P is more in the case of L2 than L1. As a result, the amount of sputtered particles reaching the surface increases and the film formation rate increases. The same applies to other points in the hole 90. When the TS distance is increased, the amount of sputtered particles reaching the point increases, and the deposition rate at that point increases. That is, by increasing the TS distance, the film formation rate on the inner surface of the hole 90 can be increased.

  In the present embodiment, from the above viewpoint, the TS distance is increased in the first step to increase the deposition rate on the inner surface of the hole 90. When the deposition rate is increased, the base thin film 93 can be formed thick in the first step. According to the inventor's research, it was found that when the thickness of the base thin film 93 is increased, embedding without generating voids is possible even if the base thin film 93 is processed at a lower temperature in the second step. For example, when aluminum is embedded in a hole with an aspect ratio of 3, in the first step, the base thin film 93 is formed on the inner surface (side surface and bottom surface) of the hole 90 with a thickness of about 300 angstroms. Even when the substrate 9 was reflowed while being heated at a relatively low temperature of 380 ° C. while depositing a thin film in the process, generation of voids was not observed.

  The reason why the film forming temperature can be lowered as described above cannot be generally stated, but it is presumed that the fluidity of the reflow thin film 91 in the second step depends on the film thickness of the base thin film 93. That is, it is presumed that the reflow thin film 91 flows more easily when the base thin film 93 as the base is thicker. Further, when the base thin film 93 is thin, when the substrate 9 is heated in the second step, the base thin film 93 flows before the reflow thin film 91 flows, as shown in FIG. It is assumed that there may be interruptions.

  In any case, in the apparatus of this embodiment, the TS distance is increased in the first step to form the thick base thin film 93 on the inner surface of the hole 90, so that the high temperature reflow sputtering is performed at a relatively low temperature in the second step. It can be performed. Note that it is not preferable to increase the TS distance in the second step. This is because if the TS distance is increased, the amount of sputtered particles that reach the substrate 9 out of the sputtered particles emitted from the target 42 decreases, so that there is a problem that the efficiency of the entire film formation is lowered. In the second process, since the thin film is reflowed and embedded in the hole 90, it is not necessary to increase the film formation rate in the hole 90 as in the first process. It is not preferable to unnecessarily increase the TS distance to reduce the film formation efficiency.

  In the first step, the pressure in the sputtering chamber 4 during film formation (hereinafter referred to as film formation pressure) is preferably set lower than that of normal sputtering. When the pressure is high, the number of gas molecules existing in the sputtered particle flight space from the target 42 to the substrate 9 is large, so that most of the sputtered particles emitted from the target 42 are scattered by the gas molecules. Although many sputtered particles can reach the surface of the substrate 9 other than the hole 90 even when scattered, the amount of sputtered particles that can reach the hole 90 is reduced when the scattered spattered particles are large. As a result, the film formation rate on the inner surface of the hole 90 is relatively lowered. Therefore, in the first step, the deposition pressure is set lower than usual so that the sputtered particles flying toward the hole 90 are not scattered. Thereby, the film forming rate on the inner surface of the hole 90 is relatively increased, and a thick base thin film 93 can be formed on the inner surface of the hole 90. Specifically, in the first step, it is preferable that the film forming pressure is 1 mTorr or less.

The operation in the sputter chamber 4 including the above-described two-stage film formation will be described. The substrate 9 is carried into the sputtering chamber 4 and placed on the substrate holder 44. The sputter chamber 4 is evacuated to about 10 ⁻⁸ to 10 ⁻⁹ Torr in advance, and in this state, a sputter discharge gas is introduced into the sputter chamber 4 by the discharge gas introduction system 45. By controlling an exhaust speed regulator (not shown) of the exhaust system 41 and a flow rate regulator 454 of the discharge gas introduction system 45, the inside of the sputtering chamber 4 is 0.8 to 1.5 mTorr which is the film forming pressure in the first step. Keep at a moderate pressure.

  Then, the sputtering power source 43 operates to perform the sputtering in the first step. At this time, as described above, the control unit (not shown) operates the distance changing mechanism 46 to place the substrate holder 44 in a predetermined lowered position in advance, thereby increasing the TS distance. Further, although the heater 441 in the substrate holder 44 is always operating, the electrostatic adsorption mechanism 49 and the boosting gas introduction system 495 are not operated. Therefore, the heat transfer efficiency from the heater 441 to the substrate 9 is poor, and the temperature of the substrate 9 is maintained at a low temperature of about 100 to 150 ° C. As described above, the base thin film 93 is formed by sputtering in the first step. The thickness of the base thin film 93 is about 200 to 400 angstroms. In the first step, the input power to the target 42 by the sputtering power source 43 is about 18 to 20 kW, which is higher than usual. This is to compensate for a decrease in the overall film formation efficiency due to an increase in the TS distance and to complete the film formation in a short time before the substrate 9 is heated by the heater 441 so much.

Next, the second step is performed. That is, a control unit (not shown) operates the distance changing mechanism 46 to position the substrate holder 44 at a predetermined raised position and shorten the TS distance. At substantially the same time, the electrostatic adsorption mechanism 49 and the pressure-increasing gas introduction system 495 are operated to improve the heat transfer efficiency from the substrate holder 44 to the substrate 9 and raise the temperature of the substrate 9. Then, the sputtering power source 43 is operated to continue the sputtering, and a thin film is further deposited on the base thin film 93. The deposited or depositing thin film is reflowed by the heat of the substrate 9 to become a reflow thin film 91 and flows into the inner surface of the hole 90. As a result, a metal material is embedded in the hole 90.
In the second step, the power input to the target 42 by the sputtering power source 43 is lower than that in the first step and is about 2 to 4 kW. This is based on the fact that the embedding property in the hole 90 is better when the thin film is gradually deposited and reflowed without increasing the film forming speed. Moreover, when moving from the first step to the second step, the power may be reduced after the operation of the sputtering power supply 43 is stopped once, but the power may be reduced without stopping the operation.

Next, returning to FIG. 1, another configuration of the high-temperature reflow sputtering apparatus of the present embodiment will be described.
The pretreatment etching chamber 3 shown in FIG. 1 is configured to remove the natural oxide film and the protective film on the surface of the substrate 9 by etching the substrate 9 prior to film formation. The pretreatment etching chamber 3 forms plasma therein, and ions in the plasma collide with the surface of the substrate 9 to remove the natural oxide film and the protective film by etching.
Further, the preheat chamber 2 is configured to heat the substrate 9 prior to film formation and release the occluded gas of the substrate 9. When the occlusion gas is not released, the occlusion gas is abruptly released due to heat during film formation, and the film surface becomes rough due to foaming. A heat stage (not shown) that is heated and maintained at a predetermined temperature is provided in the preheat chamber 2. The substrate 9 is placed on the heat stage and preheated by being heated to a predetermined temperature.
The under film forming chamber 8 forms a titanium thin film as an under film before the high temperature reflow sputtering. The undercoat film creation chamber 8 is designed to create this undercoat film by sputtering, and has substantially the same configuration as the sputter chamber 4 shown in FIG. 2 except that it includes a titanium target. In some cases, an antireflection film is formed on the high-temperature reflow sputtering film formed in the sputtering chamber 4. In this case, one of the other processing chambers 81 is an antireflection film forming chamber. . The antireflection film forming chamber is configured to be formed by sputtering using a titanium nitride thin film as an antireflection film.

The separation chamber 1 is provided with an exhaust system (not shown) as described above. This exhaust system is an exhaust system provided with a cryopump or the like, and the separation chamber 1 is configured to be exhausted to about 10 ⁻⁸ to 10 ⁻⁹ Torr by this exhaust system. By such exhaust, the atmosphere in the separation chamber 1 is kept clean. However, in order to maintain the quality of the high-temperature reflow sputtering sufficiently high, the apparatus of this embodiment is provided with another exhaust system in the separation chamber 1.

In the apparatus of the present embodiment described above, the substrate 9 is transferred to the processing chambers 2, 3, 4, 8, 81 via the separation chamber 1. At this time, if there is an impure gas in the separation chamber 1, the impurities adhere to the surface of the substrate 9. And the problem which becomes unable to fully perform high temperature reflow sputtering in the sputter | spatter chamber 4 arises with the adhering impurity.
More specifically, when water molecules adhere to the surface of the substrate 9, there is a problem that, during film formation in the sputtering chamber 4, the adhesion of the thin film is hindered or the thin film is denatured such as being oxidized. is there. Furthermore, water molecules are rapidly evaporated by the heat applied to the substrate 9 during film formation in the sputter chamber 4, and irregularities are formed on the surface of the base thin film 93 by foaming or the like, or holes are formed in the base thin film 93. Sometimes. If such irregularities and holes are formed, the reflow thin film 91 may not flow well, which may cause voids.

  In order to prevent the above problem, the apparatus according to this embodiment includes a panel 12 provided so as to be exposed to the internal space of the separation chamber 1, and the panel 12 is cooled to remove impure gas in the separation chamber 1. And a refrigerator 13 for condensing on the surface of 12.

  The panel 12 is a member made of a material having high thermal conductivity such as copper, and has a shape obtained by bending a belt-like member into an arc shape as shown in FIG. As can be seen from FIG. 2, the panel 12 is in a horizontal posture, and its surface is exposed in the separation chamber 1. Further, when the panel is made of copper, the one that has been plated with Ni or the like to prevent corrosion of the surface is used. Further, as can be seen from FIG. 1, the panel 12 is located in the vicinity of the boundary portion between the two load lock chambers 5 and the preheat chamber 2.

  The refrigerator 13 is provided outside the separation chamber 1. For the refrigerator 13, for example, CRC420 manufactured by Anerva Co., Ltd. can be used. The refrigerator 13 and the panel 12 are connected by a heat conduction block 14 provided through the wall of the separation chamber 1. The heat conducting block 14 is formed of a material having high thermal conductivity such as copper, and the cold produced by the refrigerator 13 is efficiently transmitted to the panel 12. Further, a heat insulating material (not shown) is provided between the heat conducting block 14 and the wall of the separation chamber 1 so that the cold produced by the refrigerator 13 is not transmitted to the wall of the separation chamber 1.

Although the separation chamber 1 is exhausted by the exhaust system (not shown) described above, it is inevitable that a certain amount of impure gas remains. When the panel 12 is cooled to a predetermined temperature by the cold produced by the refrigerator 13, the residual impurity gas in the separation chamber 1 is condensed on the panel 12. For this reason, adhesion of impure gas to the surface of the substrate 9 is suppressed.
If the amount of impure gas condensing on the panel 12 increases, the temperature drop on the surface of the panel 12 becomes insufficient and the impure gas condensing efficiency is lowered. Do. The regenerating operation is performed while the operation of the apparatus is stopped. Specifically, the panel 12 is heated while exhausting the separation chamber 1 at high speed by an exhaust system (not shown). When the temperature of the panel 12 rises to a certain degree, the condensed impure gas is discharged into the separation chamber 1 and is discharged from the separation chamber 1 by an exhaust system (not shown). And the surface of the panel 12 becomes an original clean surface without impure gas. Then, after the inside of the separation chamber 1 is evacuated again to a high vacuum, the operation of the apparatus is resumed.

  The degree to which the panel 12 is cooled is important because it directly relates to which residual gas is condensed. In the present embodiment, the refrigerator 13 cools the panel 12 to about 130K to 50K. This cooling temperature is set to condense mainly water molecules in the separation chamber 1 as an impure gas. This is because the presence of water molecules is particularly problematic in high-temperature reflow sputtering as described above. In order to adsorb this water molecule, it is desirable to set it to 130K or less.

  Further, the cooling temperature of the panel 12 should be set so as not to condense even the processing gas (process gas) introduced into each of the processing chambers 2, 3, 4, 8, 81. Since the pressure in each processing chamber 2, 3, 4, 8, 81 is determined by the flow rate of the process gas and the effective exhaust speed by the exhaust system, when the panel 12 is condensed to the process gas, each of these processes is performed. This is because the pressure in the chamber becomes unstable. In addition, if the panel 12 adsorbs not only moisture but also process gas, the amount of gas condensing on the panel 12 increases in a short time. Therefore, the regeneration operation of the panel 12 must be frequently performed, and productivity is increased. Causes a drop. Nitrogen or argon is often used as the process gas, and in order not to condense it, it is preferable to set the cooling temperature of the panel 12 to 50K or higher. Therefore, it is important to control the temperature of the panel 12 in the range of 130K to 50K.

  In addition, it is significant from the viewpoint of the removal of the water molecules that the surface (condensation surface) of the panel 12 is located in the vicinity of the load lock chamber 5 and the preheat chamber 2. That is, water molecules remaining in the separation chamber 1 enter from the atmosphere side via the load lock chamber 5 or are released from the substrate 9 during preheating in the preheating chamber 2 and are separated from the preheating chamber 2. It is often the one that entered 1. Water molecules are unlikely to enter from other chambers. Therefore, the configuration in which the surface of the panel 12 is located in the vicinity of the load lock chamber 5 and the preheat chamber 2 is significant as the impurity gas is condensed only in a necessary place without increasing the surface of the panel 12 and deteriorating thermal efficiency. There is.

Next, the overall movement of the high temperature reflow sputtering apparatus of this embodiment will be described.
The substrate 9 accommodated in the external cassette 62 is carried into the in-lock cassette 51 in the load lock chamber 5 by the autoloader 7. The substrate 9 loaded into the in-lock cassette 51 is first loaded into the preheat chamber 2 by the transfer robot 11 provided in the separation chamber 1. The substrate 9 carried into the preheat chamber 2 is placed on a heat stage (not shown) and heated to a predetermined temperature. As a result, the substrate 9 is preheated, and the occluded gas in the substrate 9 is released. Next, the substrate 9 is transferred to the pretreatment etching chamber 3, and the natural oxide film or protective film on the surface of the substrate 9 is etched. Thereafter, the substrate 9 is carried into the base film forming chamber 8, and a thin titanium film is formed as a base film.
Then, the substrate 9 is carried into the sputtering chamber 4. Then, high-temperature reflow sputtering is performed by the above-described two-stage film formation in the sputtering chamber 4, and the film formation is completed in a state in which the hole on the surface of the substrate 9 is sufficiently filled with the metal material, and the hole is flattened. The
Thereafter, the substrate 9 is unloaded from the sputter chamber 4, and after processing such as formation of an antireflection film and cooling is performed as necessary, the substrate 9 is accommodated in the in-lock cassette 51 in the load lock chamber 5. Thereafter, when a predetermined number of processed substrates 9 are accommodated in the in-lock cassette 51, the autoloader 7 operates to carry out the processed substrates 9 to the external cassette 62.

Next, embodiments corresponding to the second and eighth aspects of the invention will be described.
In the apparatus of the above-described embodiment, the number of the sputter chamber 4 is one, and the first step and the second step are continuously performed in the sputter chamber 4. However, two sputter chambers can be provided so that the first step is performed in one sputter chamber and the second step is performed in the other sputter chamber. The invention of claim 6 has this configuration.
Specifically, in addition to the sputtering chamber (hereinafter referred to as a first sputtering chamber) 4 shown in FIG. 1, one of the processing chambers is set as another sputtering chamber (hereinafter referred to as a second sputtering chamber). In the first sputtering chamber, the distance changing mechanism 46 as described above is unnecessary, and the substrate holder is configured so that the TS distance is the long distance described above. In the second sputtering chamber, the substrate holder is configured such that the TS distance is the short distance described above.

Further, in the first sputtering chamber, a heater for heating the substrate 9 is not particularly required. However, in the second sputtering chamber, a heater similar to that in the above-described embodiment is provided, and the electrostatic adsorption mechanism 49 and the boosting gas are provided. An introduction system 495 is similarly provided.
In this embodiment, after pre-processing etching and preheating are similarly performed, the substrate 9 is carried into the first sputter chamber. Then, after forming the base thin film in the first step in the first sputtering chamber, the substrate 9 is carried into the second sputtering chamber and the second step is performed. That is, a thin film of a metal material is further deposited and reflowed to fill the hole with the metal material. At this time, after the first step, the second step is continuously performed without the substrate 9 being taken out to the atmosphere. Therefore, there is no problem that the surface of the base thin film is oxidized or foreign matter adheres to the surface and the fluidity of the reflow thin film decreases in the second step, which is preferable in this respect.
The merit of this embodiment is that the tact time can be shortened because the first step and the second step are performed in different sputtering chambers. Therefore, in the above-described embodiment, when the processing in the sputter chamber among the processing chambers takes the longest time, the productivity can be improved by this embodiment. However, since there are two sputter chambers, the cost of the apparatus increases. Conversely, the above-described embodiment is advantageous in terms of the cost of the apparatus.

Next, examples in the above embodiment will be described focusing on two-stage film formation.
First, conditions common to the first and second steps are as follows.
・ Substrate: 200 mm diameter silicon wafer ・ Hole: Opening diameter 0.3 μm, depth 1 μm, aspect ratio 3
・ Target: 300mm diameter aluminum

Moreover, the following conditions are mentioned as a 1st process.
・ Film pressure: 1 mTorr
・ Discharge gas; Argon ・ Gas flow rate: 20 cc / min ・ Applied voltage to the target: −500 V
・ Power input to the target: 18 kW
・ TS distance: 90mm
-Film formation temperature: 100-150 ° C
Under the above conditions, the base thin film can be formed at a deposition rate of about 10,000 angstroms per minute, and sputtering is continued for about 18 seconds to form the base thin film with a thickness of about 3000 angstroms.

Moreover, the following conditions are mentioned as a 2nd process.
・ Film pressure: 1 mTorr
・ Discharge gas; Argon ・ Gas flow rate: 20 cc / min ・ Applied voltage to the target: −300 V
・ Power input to the target: 3kW
・ TS distance: 60mm
・ Film formation temperature: 400 ℃
When the second step is performed under the above conditions, aluminum can be embedded in the holes in a processing time of about 120 seconds, and no voids are observed.

In the embodiments and examples related to the configuration and operation described above, the distance changing mechanism 46 moves the substrate holder 44 to change the TS distance. However, the distance changing mechanism 46 may be configured to move the target 42. Also, the direction of movement is not limited to the vertical direction. When the substrate 9 and the target 42 face each other in a vertical posture, the moving direction is a horizontal direction.
In high-temperature reflow sputtering, the substrate 9 may be heated after the sputtering is finished to reflow the thin film. Also in the above-described embodiments and examples, the metal material may be embedded in the holes by performing only the heating process of the substrate 9 after the completion of the second process. In the above embodiment, the target 42 is made of aluminum. However, the present invention can be similarly applied when a copper thin film is formed using the copper target 42. Moreover, even when using a target made of an alloy of aluminum or copper or a target made of another metal material, the same can be applied.

1 is a schematic plan view of a high-temperature reflow sputtering apparatus according to an embodiment of the present invention. FIG. 2 is a schematic front sectional view of a sputtering chamber in the high temperature reflow sputtering apparatus shown in FIG. 1. It is the figure which showed the problem when the film-forming temperature was lowered | hung without performing two-stage film-forming. It is a figure which shows the film-forming condition at the time of performing two-stage film-forming. It is the schematic when changing TS distance. It is a front view which shows schematic structure of the conventional high temperature reflow sputtering apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Separation chamber 11 Transfer robot 2 as a transfer mechanism Preheat chamber 3 Pretreatment etching chamber 4 Sputter chamber 41 Exhaust system 42 Target 43 Sputter power supply 44 Substrate holder 441 Heater 45 Discharge gas introduction system 46 Distance changing mechanism 48 Magnet mechanism 49 Electrostatic Adsorption mechanism 495 Gas introduction system for pressurization 5 Load lock chamber 6 Gate valve 7 Autoloader 9 Substrate 90 Hole 91 Reflow thin film 92 Void 93 Base thin film

Claims (10)

A separation chamber;
A load lock chamber that is airtightly connected around the separation chamber and in which the substrate temporarily stays when the substrate is taken in and out of the atmosphere side;
A high-temperature reflow sputtering apparatus that embeds a metal material in a fine hole formed on a surface of a substrate, and includes a plurality of processing chambers hermetically connected around the separation chamber,
One of the plurality of processing chambers is a sputtering chamber;
The sputtering chamber comprises:
An exhaust system for exhausting the inside of the sputtering chamber;
A substrate holder for holding the substrate;
An electrostatic adsorption mechanism for electrostatically adsorbing the substrate to the substrate holder;
An electrostatic adsorption mechanism control unit for controlling the electrostatic adsorption mechanism;
A heater provided in the substrate holder;
A distance changing mechanism for changing the distance between the substrate and the target;
A distance change mechanism control unit for controlling the distance change mechanism; and a target holder for holding the target;
In the first step of creating a thin film of a metal material on the side and bottom surfaces of the holes of the substrate during the operation of the heater, the electrostatic adsorption mechanism control unit operates the substrate without operating the electrostatic adsorption mechanism. The heat transfer efficiency between the substrate holder and the substrate holder is poor, and after the first step, a thin film of metal material is further deposited and reflowed to embed the metal material in the hole on the substrate. In the process, the electrostatic adsorption mechanism is operated to improve the heat transfer efficiency between the substrate and the substrate holder ,
The distance change mechanism control unit performs control so that the distance between the target and the substrate in the first step is longer than the distance between the target and the substrate in a second step,
The separation chamber includes a cooling panel provided such that the surface is exposed to the internal space of the separation chamber;
A refrigerator that cools the cooling panel to 130K to 50K.
A high-temperature reflow sputtering apparatus characterized by that.   The high-temperature reflow sputtering apparatus according to claim 1, wherein a surface of the cooling panel is subjected to corrosion prevention processing.   The high-temperature reflow sputtering apparatus according to claim 1, wherein the cooling panel is made of copper. The high-temperature reflow sputtering apparatus according to claim 2 , wherein the corrosion prevention processing is nickel plating. The distance between the target and the substrate in the first step is 90 mm, and the distance between the target and the substrate in the second step is 60 mm . A high-temperature reflow sputtering apparatus described in 1. A separation chamber;
A load lock chamber that is hermetically connected around the separation chamber and is a chamber in which the substrate temporarily stays when the substrate is taken in and out of the atmosphere side;
A high-temperature reflow sputtering apparatus that embeds a metal material in a fine hole formed on a surface of a substrate, and includes a plurality of processing chambers hermetically connected around the separation chamber,
Two of the plurality of processing chambers are first and second sputtering chambers;
The first sputtering chamber comprises:
An exhaust system for exhausting the interior of the first sputtering chamber;
A first substrate holder for holding the substrate;
A first target holder for holding the first target;
The second sputtering chamber comprises:
An exhaust system for exhausting the inside of the second sputtering chamber;
A second substrate holder for holding the substrate;
An electrostatic adsorption mechanism for electrostatically adsorbing the substrate to the second substrate holder;
An electrostatic adsorption mechanism control unit for controlling the electrostatic adsorption mechanism;
A heater provided in the second substrate holder;
A second target holder for holding a second target;
The distance between the substrate and the first target is longer than the distance between said substrate in said second sputtering chamber the second target,
In the first sputtering chamber, a first step of forming a thin film of a metal material on the side surface and the bottom surface of the hole of the substrate is performed.
In the second step of embedding a metal material in the hole on the substrate by reflowing the electrostatic adsorption mechanism control unit, the electrostatic adsorption mechanism is operated during the operation of the heater so that the gap between the substrate and the substrate holder is Control to improve heat transfer efficiency ,
The separation chamber includes a cooling panel provided such that the surface is exposed to the internal space of the separation chamber;
A refrigerator that cools the cooling panel to 130K to 50K.
A high-temperature reflow sputtering apparatus characterized by that.   The high-temperature reflow sputtering apparatus according to claim 6, wherein the cooling panel has a surface subjected to corrosion prevention processing.   The high-temperature reflow sputtering apparatus according to claim 6 or 7, wherein the cooling panel is made of copper. The high-temperature reflow sputtering apparatus according to claim 7 , wherein the corrosion prevention processing is nickel plating. The distance between the first target and the substrate in the first sputtering chamber is 90 mm, and the distance between the second target and the substrate in the second sputtering chamber is 60 mm. The high-temperature reflow sputtering apparatus according to any one of claims 6 to 9.

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