US20130331005A1

US20130331005A1 - Semiconductor device manufacturing method

Info

Publication number: US20130331005A1
Application number: US13/804,624
Authority: US
Inventors: Akifumi Gawase; Gaku Minamihaba; Hajime EDA; Yukiteru Matsui
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 2012-06-11
Filing date: 2013-03-14
Publication date: 2013-12-12
Also published as: JP2013258213A

Abstract

According to one embodiment, a semiconductor device manufacturing method comprises conditioning a polishing pad by pressing a dresser against a surface of the polishing pad while keeping a surface temperature of the polishing pad at 40° C. or higher, and chemically mechanically polishing a polishing target film formed on a semiconductor substrate by pressing a surface of the polishing target film against the surface of the polishing pad having a negative Rsk value.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2012-132384, filed Jun. 11, 2012, the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a semiconductor device manufacturing method.

BACKGROUND

Semiconductor device manufacturing processes include a process such as shallow trench isolation (STI)-chemical mechanical polishing (CMP) or pre-metal dielectric (PMD)-CMP. In these CMP processes, for example, a silicon oxide film formed on a semiconductor substrate is defined as a polishing target film, and planarized.
To planarize the silicon oxide film in the CMP process, for example, a ceria-based slurry is used. As the properties of the ceria-based slurry, the polishing speed is high, and the planarization performance is high for polishing the silicon oxide film. However, depending on the state of a surface of the polishing pad, many scratches are formed on the surface of the film (for example, silicon oxide film) polished by the CMP process even using the ceria-based slurry. This leads to poor yield and reliability.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view showing a CMP apparatus according to the first embodiment;

FIG. 2 is a plan view showing the CMP apparatus according to the first embodiment;

FIG. 3 is a flowchart showing a semiconductor device manufacturing method according to each embodiment;

FIG. 4 is a view for explaining an Rsk value;

FIG. 5 is a graph showing the relationship between the Rsk value of a polishing pad surface and the number of scratches on the surface of a polishing target film by polishing experiments;

FIG. 6 is a graph showing the relationship between the surface temperature of the polishing pad and the Rsk value of the polishing pad by conditioning experiments;

FIG. 7 is a perspective view showing a CMP apparatus according to the second first embodiment;

FIG. 8 is a perspective view showing a CMP apparatus according to the third embodiment;

FIG. 9 is a plan view showing the CMP apparatus according to the third embodiment;

FIGS. 10, 11, and 12 are sectional views showing a process of conditioning a polishing pad according to the fourth embodiment; and

FIGS. 13 and 14 are sectional views showing steps in the manufacture of an STI in a semiconductor device according to each embodiment.

DETAILED DESCRIPTION

In general, according to one embodiment, a semiconductor device manufacturing method comprises: conditioning a polishing pad by pressing a dresser against a surface of the polishing pad while keeping a surface temperature of the polishing pad at 40° C. or higher; and chemically mechanically polishing a polishing target film formed on a semiconductor substrate by pressing a surface of the polishing target film against the surface of the polishing pad having a negative Rsk value.
The embodiments will now be described with reference to the accompanying drawings. The same reference numerals denote the same parts throughout the drawings. A repetitive description will be made as needed.

First Embodiment

The first embodiment will be described with reference to FIGS. 1 to 6. In the first embodiment, in a CMP method in a semiconductor device manufacturing method, steam is supplied to the surface of a polishing pad 11 to condition the surface of the polishing pad 11 such that it has a negative Rsk value. After that, a polishing target film is polished by pressing (sliding) the polishing pad 11 and the polishing target film against each other. This leads to decrease the number of scratches on the surface of the polishing target film after the CMP process. The first embodiment will be described below in detail.

[CMP Apparatus]

A CMP apparatus according to the first embodiment will be explained below with reference to FIGS. 1 and 2.
FIG. 1 is a perspective view showing the CMP apparatus according to the first embodiment. FIG. 2 is a plan view showing the CMP apparatus according to the first embodiment.
As shown in FIG. 1, the CMP apparatus according to the first embodiment comprises a turntable 10, a polishing pad 11, a top ring 12, a slurry supply nozzle 13, a dresser 15, a polishing pad temperature measurement instrument 16, and steam supply nozzles 17.
The top ring 12 that holds a semiconductor substrate 20 is pressed against the surface of the polishing pad 11 bonded to the surface of the turntable 10. For example, a silicon oxide film that is a polishing target film is formed on the surface of the semiconductor substrate 20. The polishing target film is pressed against the surface of the polishing pad 11 and is polished. The turntable 10 can rotate at 1 to 200 rpm. The top ring 12 can rotate at 1 to 200 rpm. The turntable 10 and the top ring 12 rotate in the same direction, for example, counterclockwise. During polishing of the polishing target film, the turntable 10 and the top ring 12 rotate in a predetermined direction. The polishing load is normally about 50 to 500 hPa.
The slurry supply nozzle 13 is arranged above the polishing pad 11. The slurry supply nozzle 13 can supply a predetermined chemical solution serving as a slurry at a flow rate of 50 to 1,000 cc/min during polishing of the polishing target film. Note that the slurry supply nozzle 13 is provided near the center of the turntable 10. However, the embodiment is not limited to this, and the slurry supply nozzle 13 may appropriately be provided to supply the slurry to the whole surface of the polishing pad 11.
The dresser 15 is pressed against the polishing pad 11, thereby conditioning the surface of the polishing pad 11. The dresser 15 can rotate at 1 to 200 rpm. The dresser 15 rotates, for example, counterclockwise. During conditioning, the turntable 10 and the dresser 15 rotate in a predetermined direction. The dressing load is normally about 50 to 500 hPa. The dresser 15 is, for example, a diamond dresser. However, the embodiment is not limited to this, and a ceramic dresser may be used. As the material of the ceramic dresser, a ceramic such as SiC is used.
The polishing pad temperature measurement instrument 16 that is an infrared radiation thermometer is installed on the column portion (dresser driving shaft) connected to the dresser 15. Details of the polishing pad temperature measurement instrument 16 will be described later.
The steam supply nozzles 17 for ejecting, for example, steam of heated pure water toward the polishing pad 11 are arranged above the polishing pad 11. The steam supply nozzles 17 are arranged above the polishing pad 11 radially about the slurry supply nozzle 13 (the rotating shaft of the turntable 10). For this reason, when the polishing pad 11 rotates, the steam or the like can be ejected to its whole surface. The steam supply nozzles 17 are arranged on the upstream side of the direction of rotation of the turntable 10 relative to the polishing pad temperature measurement instrument 16 (dresser 15). Hence, control of the steam supply nozzles 17 makes it possible to adjust the surface temperature of the polishing pad 11 measured by the polishing pad temperature measurement instrument 16 during conditioning.
A dressing solution supply nozzle (not shown) is also arranged above the polishing pad 11. During conditioning, the dressing solution supply nozzle supplies various kinds of dressing solutions.
Note that the upstream side of the direction of rotation of the turntable 10 relative to the dresser 15 indicates a region within 180° on the upstream side of the direction of rotation of the turntable 10 relative to the dresser 15.
As shown in FIG. 2, the polishing pad temperature measurement instrument 16 is arranged on the upstream side of the direction of rotation of the turntable 10 relative to the dresser 15. Hence, the polishing pad temperature measurement instrument 16 measures the surface temperature (inlet temperature) of the polishing pad 11 on the upstream side of the direction of rotation of the turntable 10 relative to the dresser 15. In addition, the polishing pad temperature measurement instrument 16 is arranged on the downstream side of the direction of rotation of the turntable 10 relative to the steam supply nozzles 17. That is, the polishing pad temperature measurement instrument 16 measures the surface temperature of the polishing pad 11 heated by the steam from the steam supply nozzles 17 before contact with the dresser 15.
The polishing pad temperature measurement instrument 16 measures the surface temperature of the polishing pad 11 on a circular orbit X that passes a center O′ of the dresser 15 and has a predetermined distance about a center O of the turntable 10. This is because the time the dresser 15 and the polishing pad 11 are in contact is long on the circular orbit X, and the maximum temperature can be measured.
Near an end of the dresser 15, the dressing solution hits the dresser 15 and rises. For this reason, when the temperature is measured near the end of the dresser 15, the polishing pad temperature measurement instrument 16 may measure not the surface temperature of the polishing pad 11 but the temperature of the dressing solution erroneously. To measure the surface temperature of the polishing pad 11, the polishing pad temperature measurement instrument 16 preferably measures the temperature at an inlet temperature measurement point A that is located on the circular orbit X and spaced apart from the dressing solution by a distance d1 (for example, 10 mm).

[Manufacturing Method]

A semiconductor device manufacturing method according to the first embodiment will be described below with reference to FIGS. 3 and 4.
FIG. 3 is a flowchart showing a semiconductor device manufacturing method according to each embodiment.
As shown in FIG. 3, first, in step S1, a polishing target film is formed on the semiconductor substrate 20. The polishing target film is, for example, a silicon oxide film when forming an STI structure or a PMD structure. However, the embodiment is not limited to this.
In step S2, the CMP method is performed for the polishing target film. The CMP method according to the first embodiment is performed under the following condition.
First, in step S21, conditioning of the polishing pad 11 is performed. More specifically, the dresser 15 is pressed against the surface of the polishing pad 11. The dresser 15 and the polishing pad 11 are slid (for example, rotated) against each other. The steam supply nozzles 17 supply steam of heated pure water to the surface of the polishing pad 11.
As the polishing pad 11, for example, a pad mainly made of polyurethane and having a Shore D hardness of 50 to 80 and a modulus of elasticity of 200 to 700 MPa is bonded to the turntable 10. The rate of rotation of the turntable 10 is, for example, 10 to 110 rpm. As the dresser 15, for example, a dresser having a diamond roughness of #100 to #200 (available from Asahi Diamond Industrial) is used. For example, the rate of rotation of the dresser 15 is 10 to 110 rpm, and the dressing load is 50 to 300 hPa. The conditioning time is set to, for example, 60 seconds.
At this time, the supply temperature and supply amount of the steam supplied from the steam supply nozzles 17 are controlled such that the surface temperature (the temperature at the inlet temperature measurement point A measured by the polishing pad temperature measurement instrument 16) of the polishing pad 11 becomes 40 to 80° C. This enables to set the Rsk value of the surface of the polishing pad 11 to zero or less (negative).
In step S22, the polishing target film is polished. More specifically, the polishing target film held by the top ring 12 is pressed against the conditioned polishing pad 11, and the polishing target film and the polishing pad 11 are slid against each other. For example, assume that the rate of rotation of the top ring 12 is 120 rpm, and the polishing load is 300 gf/cm². The slurry supply nozzle 13 supplies a slurry at a flow rate of 100 cc/min. The slurry contains, for example, cerium oxide (DLS2 available from Hitachi Chemical) and ammonium polycarboxylate (TK75 available from Kao) polishing grains.
In this way, when the polishing target film is polished by pressing its surface against the surface of the rotating polishing pad 11 having a negative Rsk value, the number of scratches on the surface of the polishing target film after the polishing can be decreased. The basis for this will be described later.
FIG. 4 is a view for explaining the Rsk value.
The Rsk value (roughness curve skewness value) represents the relativity of a probability density distribution relative to the average line of a surface roughness profile.
When the probability density is unevenly distributed on the lower side of the average line of the surface roughness profile, as indicated by (a) in FIG. 4, the Rsk value is positive. At this time, there are many projecting portions and a few flat portions.
On the other hand, when the probability density is unevenly distributed on the upper side of the average line of the surface roughness profile, as indicated by (b) in FIG. 4, the Rsk value is negative. At this time, there are a few projecting portions and many flat portions.
That is, a negative Rsk value means a smoother surface than a positive Rsk value.

[Basis of CMP Condition]

The basis of a CMP condition according to the first embodiment will be described below with reference to FIGS. 5 and 6.
First, polishing experiments were conducted to check the relationship between the Rsk value of the surface of the polishing pad 11 and the number of scratches on the surface of the polishing target film.
FIG. 5 is a graph showing the relationship between the Rsk value of the surface of the polishing pad 11 and the number of scratches on the surface of the polishing target film by the polishing experiments. The Rsk value was calculated from roughness measured by a wide-field laser microscope, for example, an HD100D (available from Lasertec). The number of scratches was counted after light etching of the surface of the polishing target film using diluted hydrofluoric acid after the CMP process. More specifically, after the total number and positions of defectives were measured using KLA2815 (available from KLA Tencor), each defect was evaluated by an SEM, thereby classifying and extracting the types.
As shown in FIG. 5, when the polishing target film is polished by pressing its surface against the surface of the polishing pad 11, a positive correlation (correlation coefficient=0.71) holds between the Rsk value of the surface of the polishing pad 11 at the time of polishing and the number of scratches consequently formed on the surface of the polishing target film. In other words, when the Rsk value of the polishing pad 11 becomes large, the number of scratches on the surface of the polishing target film increases. When the Rsk value becomes small, the number of scratches decreases. In addition, the larger the Rsk value of the surface of the polishing pad 11 becomes on the negative side (the larger the absolute value of the negative value is), the smaller the number of scratches on the surface of the polishing target film is, and the smaller the variation is.
In the above-described way, when the polishing target film is polished by setting the Rsk value of the surface of the polishing pad 11 to a negative value with a large absolute value, the number of scratches on the surface of the polishing target film can be decreased. For this purpose, the Rsk value of the surface of the polishing pad 11 is preferably set to a negative value with a large absolute value by conditioning.
Next, conditioning experiments were conducted to check the relationship between the surface temperature of the polishing pad 11 and the Rsk value of the polishing pad 11. The steam supplied from the steam supply nozzles 17 in the above-described CMP apparatus is controlled, thereby adjusting the surface temperature of the polishing pad 11 measured by the polishing pad temperature measurement instrument 16. The conditioning experiments were conducted under the following condition.
Polishing pad: polyurethane (Shore D hardness=60, modulus of elasticity=400 MPa)
Turntable rate of rotation: 20 rpm
Dresser: diamond roughness=#100 (available from Asahi Diamond Industrial)
Dresser load: 200 hPa
Dresser rate of rotation: 20 rpm
Dressing solution: pure water at 23° C. (room temperature)
Each conditioning experiment was performed for 60 seconds with or without heating by the steam. The conditioning experiments revealed that the surface temperature of the polishing pad 11 measured by the polishing pad temperature measurement instrument 16 was 23° C. (without heating by the steam) or 60° C. (with heating by the steam).
FIG. 6 is a graph showing the relationship between the surface temperature of the polishing pad 11 and the Rsk value of the polishing pad 11 by the conditioning experiments.
As shown in FIG. 6, when the surface of the polishing pad 11 is conditioned by the dresser 15, a negative correlation holds between the surface temperature of the polishing pad 11 at the time of conditioning and the resultant Rsk value of the polishing pad 11. In other words, when the surface temperature of the polishing pad 11 rises, the Rsk value of the polishing pad 11 becomes small. When the surface temperature falls, the Rsk value becomes large. More specifically, when the surface temperatures of the polishing pads 11 are 23 and 60° C., the Rsk values of the polishing pads 11 are 0.32 and −0.32, respectively.
As described above, the Rsk value of the surface of the polishing pad 11 is preferably set to a negative value with a large absolute value by conditioning. When the surface temperature of the polishing pad 11 during conditioning is raised, the Rsk value of the surface of the polishing pad 11 can be set to a negative value with a larger absolute value. Note that as shown in FIG. 6, when the surface temperature of the polishing pad 11 is set to 40° C. or more in conditioning, the Rsk value of the surface of the polishing pad 11 can be negative.
On the other hand, the grinding speed of the polishing pad 11 in conditioning depends on the surface temperature of the polishing pad 11. The higher the surface temperature of the polishing pad 11 is, the lower the grinding speed is the polishing pad, and vice versa. This is presumably because as the surface temperature of the polishing pad 11 rises, the polishing pad 11 softens (the modulus of elasticity becomes less), and grinding becomes difficult. That is, raising the surface temperature of the polishing pad 11 allows its working life to be extended.
When the surface temperature of the polishing pad 11 rises, the material of the polishing pad 11 changes its physical properties and softens. This reduces the wear speed of the dresser 15 pressing against the polishing pad 11. Hence, the working life of the dresser 15 can be extended. For this reason, not only a diamond dresser but also a short-lived dresser such as a non-diamond dresser (for example, a dresser made of a ceramic material) can be used as the dresser 15 for a sufficiently long life.
Note that when the surface temperature of the polishing pad 11 is set to 80° C. or more in conditioning, the physical properties of the material of the polishing pad 11 further change. This is because the material of the polishing pad 11 has a glass transition point of 80° C. or more. The glass transition point indicates a phenomenon that the material changes from a viscous or elastic state to a hard and relatively brittle state in the amorphous domain of a partially crystallized polymer. That is, when the surface temperature of the polishing pad 11 is 80° C. or more, the modulus of elasticity of the material of the polishing pad 11 becomes much less, and the physical properties change greatly in comparison with those of the original material. As a result, the surface of the polishing pad 11 cannot sufficiently be conditioned. For this reason, the surface temperature of the polishing pad 11 is preferably set to 80° C. or less in conditioning.
In the above-described way, when conditioning is performed by keeping the surface temperature of the polishing pad 11 in the range of 40 to 80° C., the Rsk value of the polishing pad 11 can be set to a negative value with a larger absolute value, and the grinding speed of the polishing pad 11 can be reduced.

[Effects]

According to the first embodiment, in the CMP method in the semiconductor device manufacturing method, steam is supplied to the surface of the polishing pad 11, thereby conditioning the surface of the polishing pad 11 at a higher temperature in the range of 40 to 80° C. After that, the polishing target film is polished by pressing its surface against the surface of the conditioned polishing pad 11. This leads to obtain the following effects.
When the surface of the polishing pad 11 is conditioned at a higher temperature, the Rsk value of the surface of the polishing pad 11 can be set to a negative value with a larger absolute value. When the polishing target film is polished by pressing its surface against the surface of the polishing pad 11 having the negative Rsk value, the number of scratches on the surface of the polishing target film after the CMP process can be decreased. This leads to suppress the decrease in the yield and reliability of devices.
In addition, when the surface of the polishing pad 11 is conditioned at a higher temperature, the grinding speed of the polishing pad 11 can be reduced. This leads the working life of the polishing pad 11 to be extended and the cost of the CMP process to be reduced.
When the surface of the polishing pad 11 is conditioned at a higher temperature, the wear speed of the dresser 15 can be reduced. This leads the working life of the dresser 15 to be extended and the cost of the CMP process to be reduced.

Second Embodiment

The second embodiment will be described next with reference to FIGS. 3 and 7. In the first embodiment, the steam supplied from the steam supply nozzles 17 is controlled in conditioning to adjust the surface temperature of the polishing pad 11. In the second embodiment, however, a heater 18 is controlled in conditioning to adjust the surface temperature of a polishing pad 11. The second embodiment will be described below in detail. Note that in the second embodiment, a description of the same points as in the first embodiment will be omitted, and different points will mainly be explained.

[CMP Apparatus]

A CMP apparatus according to the second embodiment will be explained below with reference to FIG. 7.
FIG. 7 is a perspective view showing the CMP apparatus according to the second embodiment.
As shown in FIG. 7, the CMP apparatus according to the second embodiment includes the heater 18 in place of the steam supply nozzles 17, unlike the first embodiment.
During conditioning, the heater 18 comes into contact with the surface of the polishing pad 11. The heater 18 is arranged above the polishing pad 11 radially about a slurry supply nozzle 13 (the rotating shaft of a turntable 10). For this reason, when the polishing pad 11 rotates, its whole surface can be heated. The heater 18 is arranged on the upstream side of the direction of rotation of the turntable 10 relative to a polishing pad temperature measurement instrument 16 (dresser 15). Hence, control of the heater 18 makes it possible to adjust the surface temperature of the polishing pad 11 measured by the polishing pad temperature measurement instrument 16 during conditioning. The heater 18 controls the surface temperature of the polishing pad 11 in the range of 23° C. (room temperature) to 80° C.
The polishing pad temperature measurement instrument 16 is arranged on the upstream side of the direction of rotation of the turntable 10 relative to the dresser 15. Hence, the polishing pad temperature measurement instrument 16 measures the surface temperature (inlet temperature) of the polishing pad 11 on the upstream side of the direction of rotation of the turntable 10 relative to the dresser 15. In addition, the polishing pad temperature measurement instrument 16 is arranged on the downstream side of the direction of rotation of the turntable 10 relative to the heater 18. That is, the polishing pad temperature measurement instrument 16 measures the surface temperature of the polishing pad 11 heated by the heater 18 before contact with the dresser 15.

[Manufacturing Method]

A semiconductor device manufacturing method according to the second embodiment will be described below with reference to FIG. 3.
First, in step S1, a polishing target film is formed on a semiconductor substrate 20.
In step S2, the CMP method is performed for the polishing target film. The CMP method according to the second embodiment is performed under the following condition.
First, in step S21, conditioning of the polishing pad 11 is performed. More specifically, the dresser 15 is pressed against the surface of the polishing pad 11. The dresser 15 and the polishing pad 11 are slid against each other. The heater 18 heats the surface of the polishing pad 11.
At this time, the heater 18 is controlled such that the surface temperature (the temperature at an inlet temperature measurement point A measured by the polishing pad temperature measurement instrument 16) of the polishing pad 11 becomes 40 to 80° C. This enables to make the Rsk value of the polishing pad 11 negative.
In step S22, the polishing target film is polished. More specifically, the polishing target film held by a top ring 12 is pressed against the conditioned polishing pad 11, and the polishing target film and the polishing pad 11 are slid against each other.
In this way, when the polishing target film is polished by pressing its surface against the surface of the rotating polishing pad 11 having a negative Rsk value, the number of scratches on the surface of the polishing target film after the polishing can be decreased.

[Effects]

According to the second embodiment, in the CMP method in the semiconductor device manufacturing method, the heater 18 heats the surface of the polishing pad 11, thereby conditioning the surface of the polishing pad 11 at a higher temperature in the range of 40 to 80° C. After that, the polishing target film is polished by pressing its surface against the surface of the conditioned polishing pad 11. This leads to obtain the same effects as in the first embodiment.

Third Embodiment

The third embodiment will be described next with reference to FIGS. 3, 8, and 9. In the third embodiment, a dresser 15 itself is heated and controlled in conditioning to adjust the surface temperature of a polishing pad 11. The third embodiment will be described below in detail. Note that in the third embodiment, a description of the same points as in the first embodiment will be omitted, and different points will mainly be explained.

[CMP Apparatus]

A CMP apparatus according to the third embodiment will be explained below with reference to FIGS. 8 and 9.
FIG. 8 is a perspective view showing the CMP apparatus according to the third embodiment. FIG. 9 is a plan view showing the CMP apparatus according to the third embodiment.
As shown in FIG. 8, the CMP apparatus according to the third embodiment heats the dresser 15 itself instead of including the steam supply nozzles 17, unlike the first embodiment.
The dresser 15 is pressed against the polishing pad 11, thereby conditioning the surface of the polishing pad 11. At this time, the dresser 15 itself is heated and controlled, thereby adjusting the surface temperature of the polishing pad 11 measured by a polishing pad temperature measurement instrument 16 during conditioning. The dresser 15 controls the surface temperature of the polishing pad 11 in the range of 23 to 80° C.
As shown in FIG. 9, the polishing pad temperature measurement instrument 16 is arranged on the downstream side of the direction of rotation of a turntable 10 relative to the dresser 15. Hence, the polishing pad temperature measurement instrument 16 measures the surface temperature (outlet temperature) of the polishing pad 11 on the downstream side of the direction of rotation of the turntable 10 relative to the dresser 15. That is, the polishing pad temperature measurement instrument 16 measures the surface temperature of the polishing pad 11 heated by the dresser 15.
The polishing pad temperature measurement instrument 16 measures the surface temperature of the polishing pad 11 on a circular orbit X that passes a center O′ of the dresser 15 and has a predetermined distance about a center O of the turntable 10. To measure the surface temperature of not the dressing solution but the polishing pad 11, the polishing pad temperature measurement instrument 16 preferably measures the temperature at an outlet temperature measurement point B that is located on the circular orbit X and spaced apart from the dressing solution by a distance d2 (for example, 10 mm).

[Manufacturing Method]

A semiconductor device manufacturing method according to the third embodiment will be described below with reference to FIG. 3.
First, in step S1, a polishing target film is formed on a semiconductor substrate 20.
In step S2, the CMP method is performed for the polishing target film. The CMP method according to the third embodiment is performed under the following condition.
First, in step S21, conditioning of the polishing pad 11 is performed. More specifically, the dresser 15 is pressed against the surface of the polishing pad 11. The dresser 15 and the polishing pad 11 are slid against each other. The dresser 15 itself is heated to heat the surface of the polishing pad 11.
At this time, the dresser 15 is controlled such that the surface temperature (the temperature at the outlet temperature measurement point B measured by the polishing pad temperature measurement instrument 16) of the polishing pad 11 becomes 40 to 80° C. This enables to make the Rsk value of the polishing pad 11 negative.
In step S22, the polishing target film is polished. More specifically, the polishing target film held by a top ring 12 is pressed against the conditioned polishing pad 11, and the polishing target film and the polishing pad 11 are slid against each other.
In this way, when the polishing target film is polished by pressing its surface against the surface of the rotating polishing pad 11 having a negative Rsk value, the number of scratches on the surface of the polishing target film after the polishing can be decreased.

[Effects]

According to the third embodiment, in the CMP method in the semiconductor device manufacturing method, the dresser 15 heats the surface of the polishing pad 11, thereby conditioning the surface of the polishing pad 11 at a higher temperature in the range of 40 to 80° C. After that, the polishing target film is polished by pressing its surface against the surface of the conditioned polishing pad 11. This leads to obtain the same effects as in the first embodiment.

Fourth Embodiment

The fourth embodiment will be described with reference to FIGS. 3, 10, 11, and 12. In the fourth embodiment, the surface of a polishing pad 11 and the surface of a dresser 15 having an Rsk value of zero or more (positive) press against each other in conditioning. This leads to make the Rsk value of the surface of the polishing pad 11 negative and decrease the number of scratches on the surface of a polishing target film after the CMP process. The fourth embodiment will be described below in detail. Note that in the fourth embodiment, a description of the same points as in the first embodiment will be omitted, and different points will mainly be explained.

[CMP Apparatus]

A CMP apparatus according to the fourth embodiment will be explained below.
In the CMP apparatus according to the fourth embodiment, the surface of the dresser 15 has a positive Rsk value, unlike the first embodiment.
The dresser 15 is pressed against the polishing pad 11, thereby conditioning the surface of the polishing pad 11. At this time, the surface of the dresser 15 has a positive Rsk value. Note that the surface of the dresser 15 preferably has a positive Rsk value with a larger absolute value. The dresser 15 is preferably a metal dresser having a coated surface. However, the embodiment is not limited to this, and a diamond dresser or a ceramic dresser is also usable.
Note that in the CMP apparatus according to the fourth embodiment, the surface temperature of the polishing pad 11 need not be controlled in conditioning. For this reason, the CMP apparatus according to the fourth embodiment may omit the polishing pad temperature measurement instrument 16 and the steam supply nozzles 17 of the CMP apparatus according to the first embodiment.

[Manufacturing Method]

A semiconductor device manufacturing method according to the fourth embodiment will be described below with reference to FIGS. 3, 10, 11, and 12.
FIGS. 10, 11, and 12 are sectional views showing a process of conditioning the polishing pad 11 according to the fourth embodiment.
First, in step S1, a polishing target film is formed on a semiconductor substrate 20.
In step S2, the CMP method is performed for the polishing target film. The CMP method according to the fourth embodiment is performed under the following condition.
First, in step S21, conditioning of the polishing pad 11 is performed.
More specifically, first, as shown in FIG. 10, control is performed such that the surface of the dresser 15 has a positive Rsk value. Next, as shown in FIG. 11, the surface of the polishing pad 11 is pressed against the surface of the dresser 15 having the positive Rsk value. At this time, the dresser 15 and the polishing pad 11 press against each other by such a dresser load that is pressed the convex portions of the surface of the dresser 15 into the surface of the polishing pad 11. The convex portions of the surface of the dresser 15 are thus reflected (transferred) on the surface of the polishing pad 11 so as to form concave portions. That is, the Rsk value of the surface of the polishing pad 11 is negative. At this time, to reflect the surface shape of the dresser 15 better to the surface of the polishing pad 11, the polishing pad 11 and the dresser 15 preferably do not perform relative motion (for example, rotation) in conditioning. Next, as shown in FIG. 12, the dresser 15 is separated from the polishing pad 11. After that, the dresser 15 is moved on the polishing pad 11, and the above-described conditioning operation shown in FIGS. 10, 11, and 12 is repetitively performed.
Note that the polishing pad 11 and the dresser 15 may perform relative motion (for example, rotation) to do conditioning by one-time pressment without moving the dresser 15.
In this way, pressing the surface of the dresser 15 having a positive Rsk value against the surface of the polishing pad 11 makes it possible to make the Rsk value of the surface of the polishing pad 11 negative.
In step S22, the polishing target film is polished. More specifically, the polishing target film held by a top ring 12 is pressed against the conditioned polishing pad 11, and the polishing target film and the polishing pad 11 are slid against each other.
In this way, when the polishing target film is polished by pressing its surface against the surface of the rotating polishing pad 11 having a negative Rsk value, the number of scratches on the surface of the polishing target film after the polishing can be decreased.

[Basis of CMP Condition]

The basis of a CMP condition according to the fourth embodiment will be described below.
Conditioning experiments were conducted to check the relationship between the Rsk value of the dresser 15 and the Rsk value of the polishing pad 11. The conditioning experiments were conducted under the following two conditions (a comparative example and the fourth embodiment):

Comparative Example

Polishing pad: polyurethane (Shore D hardness=60, modulus of elasticity=400 MPa)
Turntable rate of rotation: 20 rpm
Dresser: diamond roughness=#100 (available from Asahi Diamond Industrial)
Dresser load: 200 hPa
Dresser rate of rotation: 20 rpm
Dressing solution: pure water at 23° C. (room temperature)

Fourth Embodiment

Polishing pad: polyurethane (Shore D hardness=60, modulus of elasticity=400 MPa)
Turntable rate of rotation: 0 rpm
Dresser: surface-coated metal dresser, Rsk of surface>0
Dresser load: 200 hPa
Dresser rate of rotation: 0 rpm
Dressing solution: pure water at 23° C. (room temperature)
In the comparative example, the Rsk of the dresser surface was not controlled (the Rsk of the dresser surface is, for example, negative). In the fourth embodiment, the Rsk of the dresser surface was controlled to a positive value. Note that the surface temperature of the polishing pad 11 was 23° C. (room temperature) in the conditioning experiments.
When the surface of the polishing pad 11 is conditioned by the dresser 15, a negative correlation holds between the Rsk value of the surface of the dresser 15 at the time of polishing and the resultant Rsk value of the polishing pad 11. In other words, when the Rsk value of the surface of the dresser 15 becomes large, the Rsk value of the polishing pad 11 becomes small. When the Rsk value of the dresser 15 becomes small, the Rsk value of the polishing pad 11 becomes large. More specifically, when the Rsk values of the surfaces of the dressers 15 are negative (comparative example) and positive (fourth embodiment), the Rsk values of the polishing pads 11 are 0.32 and −0.18, respectively.
As described above, the Rsk value of the surface of the polishing pad 11 is preferably set to a negative value with a larger absolute value by conditioning. When the Rsk value of the surface of the dresser 15 during conditioning is set to a positive value with a larger absolute value, the Rsk value of the surface of the polishing pad 11 can be set to a negative value with a larger absolute value.

[Effects]

According to the fourth embodiment, in the CMP method in the semiconductor device manufacturing method, the Rsk value of the surface of the dresser 15 is controlled, thereby conditioning the surface of the polishing pad 11. After that, the polishing target film is polished by pressing its surface against the surface of the conditioned polishing pad 11. This leads to obtain the following effects.
When the conditioning is performed by setting the Rsk value of the surface of the dresser 15 to a positive value, the Rsk value of the surface of the polishing pad 11 can be set to a negative value. When the polishing target film is polished by pressing its surface against the surface of the polishing pad 11 having the negative Rsk value, the number of scratches on the surface of the polishing target film after the CMP process can be decreased. This leads to suppress the decrease in the yield and reliability of devices.

Application Example

An application example of the semiconductor device manufacturing method according to each embodiment will be described below with reference to FIGS. 13 and 14. A method of manufacturing an STI structure in a semiconductor device will be explained here.
FIGS. 13 and 14 are sectional views showing steps in the manufacture of an STI in a semiconductor device according to each embodiment.
As shown in FIG. 13, a silicon nitride film 21 is formed on a semiconductor substrate 20. After that, an STI pattern 22 is formed in the semiconductor substrate 20 using a silicon oxide film or the like as an etching mask. Note that, for example, a silicon oxide film or the like may be provided between the semiconductor substrate 20 and the silicon nitride film 21.
Next, a silicon oxide film 23 is formed on the entire surface by, for example, high density plasma chemical vapor deposition (CVD). At this time, the silicon oxide film 23 is formed outside the STI pattern 22 as well.
As shown in FIG. 14, the CMP process is performed for the silicon oxide film 23 that is a process target film, and its surface is polished. In the CMP process, the first embodiment is applied. More specifically, the Rsk value of the surface of the polishing pad 11 is conditioned to a negative value. After that, the silicon oxide film 23 is polished by pressing its surface against the surface of the polishing pad 11. The silicon oxide film 23 outside the STI pattern 22 is thus removed, and an STI structure is formed.
However, the embodiment is not limited to this. The CMP process of each embodiment is applicable to a CMP process performs for various kinds of metal materials or insulating materials as a process target film.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.

Claims

What is claimed is:

1. A semiconductor device manufacturing method comprising:

conditioning a polishing pad by pressing a dresser against a surface of the polishing pad while keeping a surface temperature of the polishing pad at 40° C. or higher; and

polishing a polishing target film formed on a semiconductor substrate by pressing a surface of the polishing target film against the surface of the polishing pad having a negative Rsk value.

2. The method of claim 1, wherein when conditioning the polishing pad, the surface temperature of the polishing pad is at 80° C. or lower.

3. The method of claim 1, wherein when conditioning the polishing pad, steam is supplied to the surface of the polishing pad.

4. The method of claim 3, wherein when conditioning the polishing pad, the polishing pad is rotated, and the steam is supplied to the surface of the polishing pad on an upstream side of a direction of rotation relative to the dresser.

5. The method of claim 1, wherein when conditioning the polishing pad, a heater comes into contact with the surface of the polishing pad.

6. The method of claim 5, wherein when conditioning the polishing pad, the polishing pad is rotated, and the heater comes into contact with the surface of the polishing pad on an upstream side of a direction of rotation relative to the dresser.

7. The method of claim 1, wherein when conditioning the polishing pad, the dresser is heated.

8. The method of claim 1, wherein the dresser comprises a non-diamond dresser.

9. The method of claim 1, wherein the polishing pad is made of polyurethane.

10. The method of claim 1, wherein a Shore D hardness of the polishing pad is 50 to 80.

11. The method of claim 1, wherein a modulus of elasticity of the polishing pad is 200 to 700 MPa.

12. A semiconductor device manufacturing method comprising:

conditioning a polishing pad by pressing a dresser having a positive Rsk value against a surface of the polishing pad; and

13. The method of claim 12, wherein the dresser comprises a metal dresser.

14. The method of claim 12, wherein when conditioning the polishing pad, the polishing pad and the dresser are not rotated.

15. The method of claim 12, wherein the polishing pad is made of polyurethane.

16. The method of claim 12, wherein a Shore D hardness of the polishing pad is 50 to 80.

17. The method of claim 12, wherein a modulus of elasticity of the polishing pad is 200 to 700 MPa.