KR100470137B1 - Polishing apparatus comprising frozen pad and method for polishing using the same - Google Patents

Abstract

Disclosed are a chemical polishing apparatus in which polishing chemicals required for polishing are supplied from a polishing pad and a polishing method using the same. The present invention relates to a chemical polishing apparatus used for polishing a material film formed on a wafer in a manufacturing process of a semiconductor device, wherein the chemical polishing apparatus is adsorbed on a bottom surface and applied to a wafer temperature and a wafer back side during the polishing process. A wafer head capable of maintaining a uniform pressure, a cooling pad provided at a position facing the wafer head and supplied with chemicals required for polishing in a polishing process, a cooling vessel surrounding the bottom and side surfaces of the cooling pad, and And a cooling means attached to a bottom surface of a cooling vessel and used for forming and maintaining the cooling pad, and a chamber including each of the above elements and maintained in an anhydrous state. do.

Description

Polishing apparatus comprising frozen pad and method for polishing using the same

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing apparatus used in a manufacturing process of a semiconductor device and a polishing method using the same. Specifically, a chemical mechanical polishing comprising a cooling polishing pad having a mechanism in which polishing chemicals are supplied by itself and an associated wafer head is provided. ) And a polishing method using the same.

As the wafer size becomes large in the semiconductor process, a polishing method using chemical mechanical polishing is widely used.

Referring to FIG. 1, the conventional chemical mechanical polishing apparatus adsorbs the back structure of the wafer 18 during the polishing process and the lower structure including the polishing table 10 and the polishing pad 12 provided thereon. And a slurry supply means 20 for supplying a slurry 22 between the wafer 18 and the polishing pad 12 during the polishing process. In the polishing process, the wafer 18 is prevented from being separated by the guide ring 16 attached to the bottom surface of the wafer head 14 opposite the polishing pad 12.

Polishing begins by feeding slurry 22 between wafer 18 and polishing pad 12 after wafer 18 is adsorbed onto wafer head 14. The slurry 22 includes a polishing agent, which is a mechanical polishing component composed of fine ceramic particles, and various chemical solutions depending on the material to be polished, so that the surface of the wafer is polished by a combination of the mechanical and chemical elements.

In the case of polishing using a chemical polishing apparatus according to the prior art, polishing by mechanical elements becomes a major factor, which not only causes defects affecting subsequent processes such as scratches, but also erosion appears and slurry by mechanical friction. The rise in temperature leads to greater chemical reactions resulting in dishing.

For example, FIG. 2 illustrates a process of forming the polysilicon contact plug 28 in the cell region C and the peripheral circuit region P using the conventional CMP after the gate line 26 or the bit line is formed. , The characteristics of the peripheral circuit region P having a relatively larger spacing between the patterns than the dishing 30 in the cell region C, the corrosion 32, the rounding 34 appearing at the boundary of the region, and the cell region C Excessive oxide loss (36) and resulting damage (38) of the gate lines appear, leaving the residue (40) of polysilicon on the interlayer insulating film (39). In FIG. 2, reference numeral 24 denotes a substrate.

FIG. 3 shows a case where a conventional CMP is used for the planarization process of the interlayer insulating film 41, and similarly, the rounding 42, the excessive etching portion 44, and the damage 46 of the metal wiring 45 formed at the edge of the region. Appears. Reference numeral 48 is a barrier layer.

4 shows a case in which a conventional CMP is used to form the metal plug 50. The corrosion 52 and the dishing 54 appear on the metal plug 50 and the metal residue 58 on the interlayer insulating film 56. It can be seen that this is formed.

5 shows a case in which a conventional CMP is used in a dual damascene process, a dishing 62 appears in a conductive plug 60 filled in contact holes formed of primary and secondary damascene, and corrosion of the interlayer insulating layer 64 66), it can be seen that a metal residue 68 is formed.

In addition to the above problems, as a result of slurry storage and transportation, the abrasive in the slurry is prevented from sedimentation and agglomeration due to the difference in specific gravity, and the slurry is continuously circulated and nitrogen is used for effective slurry dispersion. As it maintains and manages, there are problems in process and equipment management, and the agglomeration of abrasive due to the change of slurry aging may cause scratches in the polishing process. To remove it. Accordingly, the conventional CMP process has a problem in that the cost of the overall process is increased, such as the overall amount of slurry is reduced and the associated cost is increased.

Therefore, the technical problem to be achieved by the present invention is to solve the problems of the prior art described above, by eliminating the use of the slurry by eliminating the problems associated with the use of the slurry, ensuring wafer yield with low cost, high efficiency and high productivity It is possible to provide a chemical mechanical polishing apparatus.

Another object of the present invention is to provide a polishing method using the chemical mechanical polishing apparatus.

1 is a schematic cross-sectional view of a chemical polishing apparatus according to the prior art.

2 to 5 are cross-sectional views illustrating problems caused in the polishing process using the conventional chemical polishing apparatus of FIG. 1.

6 is a sectional view of a polishing apparatus having a cooling pad according to a first embodiment of the present invention.

FIG. 7 is a detailed cross-sectional view of the cooling means provided in the polishing apparatus shown in FIG. 6.

FIG. 8 is a detailed cross-sectional view of the wafer head provided in the polishing apparatus shown in FIG. 6.

9 and 10 are enlarged cross-sectional views of the wafer guide ring in the wafer head shown in FIG. 8, respectively, illustrating different embodiments of the guide ring.

FIG. 11 is a cross-sectional view of a wafer head having a vibrator that may be included in the polishing apparatus shown in FIG. 6.

12 is a cross-sectional view illustrating rotation inducing means of a wafer head provided in the polishing apparatus shown in FIG. 6.

Fig. 13 is a sectional view of the polishing apparatus according to the second embodiment of the present invention, showing only the polishing pad portion.

14 is a plan view of FIG. 13.

FIG. 15 is a cross-sectional view of the polishing apparatus according to the third embodiment of the present invention, showing briefly only portions different from the second embodiment.

Fig. 16 is a sectional view of the polishing apparatus according to the fourth embodiment of the present invention, showing only portions of the polishing pad different from the first embodiment.

Fig. 17 is a sectional view of the polishing apparatus according to the fifth embodiment of the present invention, showing the case where the second and fourth embodiments are combined.

18 and 19 are cross-sectional views showing step by step the polishing method using a polishing apparatus according to a first embodiment of the present invention.

20 to 22 are cross-sectional views showing a polishing method according to the second to fourth embodiments of the present invention.

FIG. 23 is a view illustrating a configuration of cooling pads required for sequentially polishing different material films.

24 is a block diagram showing step by step a polishing method according to a fifth embodiment of the present invention.

25 is a cross-sectional view of a bare wafer whose surface is polished by the polishing method according to the fifth embodiment of the present invention.

* Description of Signs of Major Parts of Drawings *

100: cooling pad 102: cooling pad container

104: cooling means 104a, 104c: first and second thermoelectric elements

104b, 160: Cooling part 110: Wafer head

112: head body 114: head cooling means

116: wafer backing plate

118: Wafer guide ring 120: Wafer

122: head thermoelectric element 124: vacuum line

128: motor 130: timing belt

150: pin 152: vibrator

160a, 160b: cooling gas inlet and exhaust

162: cooling plate 162a: fin

In order to achieve the above technical problem, the present invention provides a chemical mechanical polishing (CMP) apparatus for use in polishing a material film formed on a wafer using a low temperature chemical polishing process, wherein the chemical mechanical polishing apparatus has a polishing wafer on its bottom surface. A wafer head which is adsorbed and capable of maintaining a uniform temperature of the wafer and a pressure applied to the back surface of the wafer during the polishing process; A cooling pad provided at a position opposite to the wafer head, the surface being flattened to be suitable for polishing the wafer, and having a chemical required for the polishing supplied by itself during the polishing process; A cooling vessel surrounding the bottom and side surfaces of the cooling pad; Cooling means attached to a bottom surface of the cooling container and used to form and maintain the cooling pad; And a chamber including each of the above elements and maintained in anhydrous state.

The wafer head may include a main body into which pressurized gas flows upward; A head cooling unit used to cool the wafer; A wafer suction plate attached to a bottom surface of the head cooling unit and generating a temperature difference between a surface facing the cooling pad and a surface attached to the head cooling unit; A wafer guide ring disposed around the wafer suction plate to surround the wafer; And a vacuum line used for adsorption of the wafer formed through the head cooling unit and the wafer adsorption plate.

The cooling pad is a circular series or a square series.

A platter is further provided in the chamber for planarizing the surface of the cooling pad.

The material of the cooling vessel is an aluminum-based alloy, a copper-based alloy, a titanium-based alloy, or a stainless steel-based alloy.

The portion of the cooling vessel that is in direct contact with the cooling pad is plated with a metal material such as Group 8 on the periodic table and gold (Au).

The cooling means is a cooling unit for removing heat generated from the first and second thermoelectric elements in contact with the first and second thermoelectric elements and the entire bottom of the first and second thermoelectric elements in contact with the bottom surface of the cooling vessel. The first and second thermoelectric elements are configured to generate a low temperature on the cooling container side and a high temperature on the cooling unit side.

The main materials of the first and second thermoelectric elements are formed by mixing Group 6A and Group 5B on the periodic table at a constant molar ratio.

A thermoelectric element for generating the temperature difference is also provided in the wafer suction plate.

The other part of the wafer suction plate except for the part directly contacting the wafer is made of aluminum, copper, titanium, titanium alloy or stainless steel.

A plurality of cooling fins are formed at the bottom of the cooling vessel.

A vibrator using a vibration frequency of 10 to 100 MHz is attached to a side surface of the cooling vessel in which a plurality of cooling fins are formed at the bottom.

The heating plate is provided with a plurality of fins formed on the ceiling of the cooling unit.

In order to achieve the above another technical problem, the present invention comprises the steps of forming a material layer on the substrate; And polishing the material layer, wherein the polishing is performed using the polishing apparatus of claim 1.

The material layer is formed to be in direct contact with the substrate or indirectly through the lower material film.

The material layer is formed of at least one selected from a conductive layer, an insulating layer, and a mixed layer composed of the conductive layer and the insulating layer.

In this process, the insulating layer is a metal interlayer insulating film, when the material film formed in a high-density plasma method or a BPSG (Boro-Phospo Silicate Glass) film, the cooling pad is mixed with hydrofluoric acid, NH4F, CH3COOH, each chemical Mixing at a ratio of ˜1,000: 1 to 10: 1 to 20; Filling the cooling vessel with the mixed chemical solution; And it is formed through the step of uniformly cooling the mixed chemical solution below the freezing point using a thermoelectric element.

In addition, when the conductive layer is the polysilicon layer, the cooling pad for polishing the conductive layer is mixed with hydrofluoric acid, nitric acid, hydrogen peroxide and TMAH or NH4OH, but the mixing ratio of hydrofluoric acid to nitric acid is 1 to 10:50 to 1,000. Mixing with hydrogen peroxide and TMAH (or NH 4 OH) with water at a mixing ratio of 100-300: 100-500; The mixed chemical solution is formed through a step of uniformly cooling below freezing point without phase separation and concentration change using a thermoelectric element.

When the conductive layer is the tungsten layer, the cooling pad for polishing the conductive layer is

Mixing KH 2 PO 4, KOH (or NH 4 OH), and K 3 [Fe (CN) 6] in a mixing ratio of 1 to 100: 1 to 10: 1 to 100; Filling the cooling vessel with the mixed chemical solution; And it is formed through the step of uniformly cooling the mixed chemical solution below the freezing point using a thermoelectric element.

When the conductive layer is a tungsten layer, the cooling pad for polishing the conductive layer may include mixing HNO 3: HF at a ratio of 1 to 100: 1 to 20, respectively; Filling the cooling vessel with the mixed chemical solution; And it is formed through the step of uniformly cooling the mixed chemical solution below the freezing point using a thermoelectric element.

When the conductive layer is a tungsten layer, the cooling pad for polishing the conductive layer is filled with H 2 O 2 in the cooling vessel; And uniformly cooling the H202 below the freezing point using a thermoelectric element.

When the conductive layer is an aluminum layer, the cooling pad for polishing the conductive layer may include mixing HNO 3, CH 3 COOH, and H 3 PO 4 in a mixing ratio of 1 to 20: 1 to 100: 1 to 100; Filling the cooling vessel with the mixed chemical solution; And cooling the mixed chemical solution uniformly below freezing point without phase separation and concentration change using a thermoelectric element.

When the conductive layer is a copper layer, the cooling pad comprises mixing CuCl 2, H202, or FeCl 2 with pure water at a mixing ratio of 1 to 100: 1 to 500; Filling the cooling vessel with the mixed chemical solution; And cooling the mixed chemical solution uniformly below freezing point without phase separation and concentration change using a thermoelectric element.

By using the present invention, since the conventional slurry is not used in various polishing processes performed in the manufacturing process of the semiconductor device, all the problems caused by the use of the slurry, such as dishing, corrosion, excessive etching, rounding or scratching, etc. can be solved. In addition, since the slurry management and maintenance are unnecessary and the associated costs incurred in the process can be reduced, the overall process cost can be greatly reduced as compared to the conventional CMP process.

Hereinafter, a chemical mechanical polishing apparatus and a polishing method using the same according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In this process, the thicknesses of layers or regions illustrated in the drawings are exaggerated for clarity.

First, a chemical mechanical polishing apparatus according to an embodiment of the present invention will be described.

<First Embodiment>

Referring to FIG. 6, reference numeral 98 denotes an anhydrous chamber from which water is removed. For this purpose, an inlet 99a through which drying nitrogen gas N2 is introduced is provided at an upper portion thereof, and an outlet 99b is provided at a lower portion thereof. It is. The location of the inlet 99a and the outlet 99b is optional. Reference numeral 100 denotes a cooling polishing pad (hereinafter referred to as a 'cooling pad') that is cooled by freezing the chemical solution used for polishing below the freezing point. The cooling pad 100 may be made of various chemicals depending on the material to be polished. For example, the cooling pad 100 may include nitric acid (HNO 3), hydrofluoric acid (HF), hydrochloric acid (HCl), sulfuric acid (H 2 SO 4), phosphoric acid (H 3 PO 4), ammonia (NH 4 OH), NH 4 F, fruit tree (H 202), TMAH, KH 2 P04, KOH , K3 [Fe (CN) 6], pure water, CH3COOH, CuCl2, FeCl2, etc. At least a predetermined chemical substance composed of at least a predetermined mixing ratio according to the polishing target material.

For example, the cooling pad 100 is for use in a process of planarizing the metal interlayer insulating film, and when the metal interlayer insulating film is a material film formed by a high density plasma method or a BPSG (Boro-Phospo Silicate Glass) film, the cooling pad 100 is used. ) Is composed of hydrofluoric acid, NH4F, CH3COOH, each of the chemicals are mixed in a ratio of 10 to 1,000: 1 to 10: 1 to 20. In addition, if the metal pad 100 is to be used in the process of forming a metal plug, in particular tungsten (W) plug, it is composed of KH 2 PO 4, KOH (or NH 4 OH), K 3 [Fe (CN) 6], Chemical substances are mixed in the ratio of 1-100: 1-10: 1-100.

As such, the cooling pad 100 may be configured by mixing various chemical substances in a predetermined ratio according to the material to be polished.

The cooling pad 100 is filled in the cooling container 102, and its surface has a flatness suitable for wafer polishing. The chamber 98 has a cooling pad platter, such as a flat ruler or a flat panel, as a means for smoothing the surface of the cooling pad 100 for wafer polishing prior to the polishing process. 'Platter'). The platter material is a titanium alloy, platinum (Pt), tungsten (W), iron (Fe) -based alloys. When the chemical solution filled in the cooling vessel 102 is cooled to form the cooling pad 100, the surface thereof becomes flat to some extent, but not flat enough to be suitable for wafer polishing. Therefore, immediately after the cooling pad 100 is formed, the surface of the cooling pad 100 needs to be flat enough to be suitable for wafer polishing, and the platter is used for this purpose. The platter is also used to polish the surface of one wafer and then to re-cool the cooling pad 100 for the next polishing.

The cooling vessel 102 preferably has a circular shape in a planar shape, but may be a rectangular type. In addition, the material of the cooling container 102 is excellent in thermal conductivity, and is an aluminum alloy, a copper alloy, a titanium alloy, or a stainless steel alloy. In addition, the portion in direct contact with the cooling pad 100 is a Group 8 material on the periodic table, such as iron (Fe), cobalt (Co), nickel (Ni), ruthenium (Ru), palladium (Pd), osmium (0s), It is plated with iridium (Ir) or platinum (Pt) and gold (Au).

Cooling means 104 is attached to the bottom surface of the cooling vessel 102. The cooling means 104 is for freezing and maintaining the frozen state of the chemicals constituting the cooling pad 100.

Referring to FIG. 7, the cooling means 104 includes an entire bottom surface of the first and second thermoelectric elements 104a and 104c and the first and second thermoelectric elements 104a and 104c in contact with the bottom surface of the cooling vessel 102. It consists of the cooling part 104b which contact | connects. The first and second thermoelectric elements 104a and 104b generate a temperature difference between the cooling vessel 102 side and the cooling unit 104b side as power is applied, thereby generating a low temperature on the cooling vessel 102 side. The high temperature is generated on the cooling unit 104b side. By using the first and second thermoelectric elements 104a and 104c, the temperature of the cooling vessel 102 can be lowered to -250 ° C to 100 ° C. The main material of the first and second thermoelectric elements 104a and 104c is a mixture of Group 6A (eg, Se, Po, Te) and Group 5A (eg, P, As, Sb, Bi) on the periodic table at a constant molar ratio. It is. The first and second thermoelectric elements 104a and 104c preferably have a circular series corresponding to the cooling vessel 102, but may be rectangular, triangular, or donut-based.

The cooling part 104b is in contact with the high temperature side of the 1st and 2nd thermoelectric elements 104a and 104c. Therefore, it is necessary to quickly remove heat generated in the first and second thermoelectric elements 104a and 104b, and accordingly, the cooling container 102 side can be maintained at a desired temperature. To this end, a cooling gas is introduced into the cooling unit 104b. The cooling gas is dry ice (LCO2), liquid nitrogen (LN2), liquid hydrogen (LH2), liquid oxygen (LO2), liquid helium (LHe), liquid neon (LNe), liquid argon (LAr), liquid xenon (LXe) ) Or liquid krypton (LKr).

Referring back to FIG. 6, the wafer head 110 is provided on the cooling pad 100. The wafer head 110 includes a main body 112 and a head cooling unit 114 attached to the bottom of the main body 112, a wafer suction plate 116 attached to the lower surface of the head cooling unit 114, and a wafer guide ring provided around the wafer head 110. It consists of 118. Reference numeral 120 denotes a wafer vacuum-adsorbed to the wafer suction plate 116. Pressurized gas flows into the upper part of the main body 112, and an even pressure is applied to the entire surface of the wafer. For example, the pressurized gas may be used to generate a pressure of about 0.01 psi to about 100 psi when the wafer 120 contacts the cooling pad 100.

Although not shown in the drawings, a carrier film may be provided between the wafer adsorption plate 116 and the wafer 120 as one of means used to evenly transfer the pressure by the pressurized gas to the entire surface of the wafer.

In addition, in order to maintain the horizontal and spacing of the wafer 120 and the cooling pad 110 during polishing, a sensing means capable of detecting the horizontal and spacing change of any one of the wafer header 120 and the cooling pad 100 may be a wafer. At least the wafer head 110 is provided during the driving of the head 110 and the cooling container 102. It is preferably provided around the wafer head 110, in particular around the head body 112. By simply providing the sensing means in the wafer head 110, it is possible to sufficiently detect the horizontal and the interval change between the wafer 120 and the cooling pad 100, but the second sensing means is provided in the cooling container 102. In addition, the detection rate and precision may be increased.

Since it is difficult to directly control the movement of the wafer head 110 and the cooling vessel 102 with the sensing means, the sensing means transmits power to the wafer head 110 and the cooling vessel 102 so that both movements can be controlled. It is preferable to connect the causing dynamometer, for example, the rotational and vertical movement of the wafer head 110 to the rotating dynamometer and aligner responsible for the movement.

The sensing means may be any one capable of detecting relative horizontal and spacing changes of two objects, but may be an interferometer, gyroscope, reflectometry, acoustic vibration, or infrared sensor. (RI sensor) and torque motor current (preferably any one).

Referring to FIG. 8, a head thermoelectric element 122 is provided in the wafer suction plate 116. The head thermoelectric element 122 may have the same material and configuration as the first and second thermoelectric elements 104a and 104c of the cooling unit 104. The surface facing the wafer 120 of the head thermoelectric element 122 is a low temperature region, and the surface facing the head cooling unit 114 is a high temperature region. The front surface of the wafer 120 is maintained at a uniform temperature due to the head thermoelectric element 122. A vacuum line 124 connected to the wafer 120 is provided between the head thermoelectric elements 122. The head cooling unit 114 functions the same as the cooling unit 104. In other words, it serves to lower the temperature of the wafer 120 and maintain it at a constant temperature. At this time, the low temperature surface of the wafer 120 can be maintained at about -10 ° C to about 200 ° C. The portion of the wafer adsorption plate 116 that is in direct contact with the wafer 120 is composed of a metal having high heat transfer rate, such as aluminum, platinum, gold, copper, nickel, and the like, and the front of the group 8A (Fe, Co) on the periodic table , Mo, Pt, Ru, Ir) material is plated. The other part of the wafer suction plate 116 is made of aluminum, copper, titanium, titanium alloy or stainless steel.

Referring to FIG. 9, the wafer guide ring 118 includes a guider 118b in contact with the cylinder 118a and the wafer 120, and a spring 118c for applying an elastic force to the backside of the guider 118b in the cylinder 118a. It consists of. In addition, the material of the wafer guide ring 118 is a Teflon-based polymer resin having chemical resistance.

Meanwhile, as shown in FIG. 10, the liquid 118d may be used instead of the spring 118c of FIG. 9 as a means for applying an elastic force to the back of the guider.

FIG. 11 illustrates a modified wafer head, and a vibrator 126 is provided around the main body of the wafer head 110 shown in FIG. 6. The vibrator 126 is for allowing the liquefied solution of the cooling pad 100 to easily flow in and out between the patterns of the wafer polishing surface during the polishing process. The vibrator 126 uses a vibration frequency of 10 MHz to 100 MHz.

Referring to FIG. 12, the rotation shaft 110a of the wafer head 110 is connected to the rotation shaft 128a of the motor 128 and the timing belt 130, which may maintain a constant rotation rate even at a high speed and a low speed. The wafer head 110 may be rotated at 0.01 rpm to 500 rpm using the motor 128.

Second Embodiment

Only parts different from the first embodiment will be described.

Referring to FIG. 13, a plurality of cooling fins 150 are provided at the bottom of the cooling vessel 102. Cooling fin 150 is formed evenly on the bottom of the cooling vessel 102, as shown in FIG. Cooling fin 150 is the result of the expansion of the contact area between the chemical solution and the cooling container 102 to be used as the cooling pad 100 is filled in the cooling container 102 uniformly below the freezing point in a shorter time Can be frozen. As such, since the chemical solution filled in the cooling container 102 can be instantly and rapidly frozen in a uniform manner, the chemical solution composed of various components can be separated from each component during the freezing process to prevent the composition of the solution from changing.

Referring to FIG. 14, it can be seen that a donut-type first thermoelectric element 104c is provided around the circular second thermoelectric element 104c. In addition, it can be seen that the diameter of the first thermoelectric element 104c is larger than the diameter of the cooling pad 100.

Third Embodiment

Only parts different from the first and second embodiments will be described.

Referring to FIG. 15, the other parts are the same as in the second embodiment, but the vibrator 152 is further provided on the side surface of the cooling container 102. As described above for the vibrator 152 is as described above.

Fourth Example

Only parts different from the first to third embodiments will be described.

Referring to FIG. 16, reference numeral 160 denotes a cooling unit. Cooling gas that flows heat generated from the first and second thermoelectric elements 104a and 104c into the cooling unit 160 to the ceiling of the cooling unit 160 in contact with the first and second thermoelectric elements 104a and 104c. Is provided with a heating plate 162 to transmit to. A plurality of fins 162a are provided on the heat generating plate 162 as a means for widening the heat generating surface area. Therefore, the heat generating area that is contacted until the cooling gas introduced into the cooling unit 160 through the cooling gas inlet 160a leaves the cooling unit 160 through the outlet 160b is much higher than when there is no heating plate 162. As a result, it is possible to quickly remove heat generated from the first and second thermoelectric elements 104a and 104c, thereby freezing the polishing chemicals filled in the cooling vessel 102 below the freezing point in a short time. .

Fifth Embodiment

In the case of combining the second and fourth embodiments.

That is, referring to FIG. 17, a cooling vessel 102 having a plurality of cooling fins 150 at the bottom, as shown in the second embodiment, having the first and second thermoelectric elements 104a and 104c therebetween. The cooling unit 160 is provided with a heating plate 162 on the ceiling, as shown in the fourth embodiment below.

Next, a polishing method using the above-described chemical polishing apparatus according to an embodiment of the present invention will be described.

<First Embodiment>

Referring to FIG. 18, the substrate 200 is divided into a cell region C and a peripheral circuit region P, and then a gate stack 210 is formed on each region of the substrate 200. The gate stack 210 is formed by sequentially forming a gate oxide film, a gate conductive layer, and a gate insulating film. After forming the spacer 212 on the side of the gate stack 210, an interlayer insulating layer 213 is formed on the substrate 200 to cover the gate stack 210 and the spacer 212. By patterning the interlayer insulating film 213 using self-aligned, the contact hole 214 and the peripheral circuit in which the substrate between the gate stack 212 of the cell region C is exposed to the interlayer insulating film 213. A via hole 216 is formed through which the gate conductive layer (not shown) of the gate stack 210 formed in the region P is exposed. A polysilicon layer 218 is formed on the interlayer insulating layer 213 to fill the contact hole 214 and the via hole 216. At this time, the polysilicon layer 218 is formed to a thickness of about 1,000 kPa to 10,000 kPa.

Thereafter, the entire surface of the polysilicon layer 218 is polished using any one of the above-described chemical polishing apparatuses according to the first to fifth embodiments, for example, the polishing apparatus according to the first embodiment. In this case, the polishing is performed until the interlayer insulating film 213 is exposed.

Prior to the polishing, the substrate 200 on which the polysilicon layer 218 is formed is loaded into the chamber 98 shown in FIG. 6 and vacuum-adsorbed to the wafer head 110, and the dry nitrogen gas is dried in the chamber 98. N2) is flowed to keep the inside of the chamber 98 dry. Subsequently, in order to form the cooling pad 100, a chemical etchant suitable for polishing the polysilicon layer 218 is prepared and filled in the cooling vessel 102. The chemical agent is prepared using hydrofluoric acid, nitric acid, hydrogen peroxide and TMAH or NH 4 OH. At this time, hydrofluoric acid to nitric acid is mixed at a mixing ratio of 1 to 10:50 to 1,000, and hydrogen peroxide to TMAH (or NH4OH) is mixed at a mixing ratio of 100 to 300: 100 to 500. Thereafter, power is applied to the first and second thermoelectric elements 104a and 104c to uniformly freeze the chemical etchant below the freezing point. Preferably, the chemical agent is cooled to 10 ° C to -150 ° C. The surface of the cooling pad 100 thus cooled is flattened to be suitable for wafer polishing by using a platter provided in the chamber 98. Specifically, the platter is brought into contact with the surface of the cooling pad 100 and then cooled through the platter. While applying a predetermined pressure (0.1 psi to 30 psi) to the pad 100, the surface of the cooling pad 100 is planarized while moving at a moving speed of about 0.01 m / min to 10 m / min. The platter is formed using a titanium alloy or platinum (Pt), tungsten (W), iron (Fe) -based alloys.

Meanwhile, the substrate 200 vacuum-adsorbed to the wafer head 110 during the polishing process is maintained at about -50 ° C to 200 ° C according to a desired polishing rate using the head thermoelectric element 122. In addition, the rotational speed, pressure, and vibration frequency of the substrate 200 are preferably maintained at appropriate values within the ranges of 1 rpm to 300 rpm, 0 psi to 100 psi, and 10 MHz to 300 MHz, respectively. At this time, the wafer head 110 and the substrate 200 and the cooling pad 100 are to be kept exactly horizontal.

In the polishing, the mechanical element using the conventional abrasive is excluded, and by using the thermoelectric element, the temperature of the substrate 200 and the cooling pad 100 can be maintained uniformly over the entire region throughout the polishing process, thus the substrate 200 The entire surface of the polysilicon layer 218 is uniformly polished over the entire region. As a result, as shown in FIG. 19, the damage of the gate stack 210 formed in the peripheral circuit region or the interlayer insulating film without the dishing, the rounding that occurs at the region boundary, the corrosion of the pattern, the scratches, and the like, as shown in FIG. Complete polysilicon plugs 218a and 218b are formed to fill contact holes 214 and via holes 216, such as no polysilicon debris is formed on 218.

Second Embodiment

In the second embodiment, as shown in FIG. 20, after the metal wires 230 and 232 are formed in the cells and peripheral circuit regions C and P on the substrate 200, the metal interlayer insulating film 234 covering the entire surface thereof is formed. ), Forming an insulating film 233 for improving the gap fill on the entire surface of the metal wirings 230 and 232, forming a thickness of the metal interlayer insulating film 234 (100 kPa to 20,000 kPa), and a cooling pad for polishing the same. Only the chemical agent used for forming is different, and the remaining conditions are the same as in the first embodiment.

The metal interlayer insulating film 234 is formed of a material film formed by a high density plasma method or a BPSG film. In this case, as the chemical etchant for forming the cooling pad 100, hydrofluoric acid, NH 4 F, and CH 3 COOH are used, but each is mixed and used in a mixing ratio of 10 to 1,000: 1 to 10: 1 to 20.

Third Embodiment

The method relates to a method of forming a conductive plug for connecting a metal layer or a conductive layer formed on upper and lower portions thereof. As illustrated in FIG. 21, a via hole 254 is formed in the interlayer insulating layer 250 to expose the conductive layer 252. Then, the barrier layer 256 is formed on the entire via hole 254, and is formed of a material film composed of a tantalum nitride film, a titanium film, and a titanium nitride film, each of 0 to 1,000 mV: 50 to 1,000 mV: It is formed to a thickness of 50 ~ 1,000Å. A conductive layer (not shown) filling the via hole 254 is formed on the barrier layer 256. The conductive layer is formed to a thickness of 100 kPa to 50,000 kPa. Subsequently, the entire surface of the conductive layer is polished using the chemical polishing apparatus of the present invention until the interlayer insulating film 250 is exposed. In this way, the conductive plug 258 filling the via hole 254 is formed. The conductive layer is formed of a tungsten layer, an aluminum layer or a copper layer. Thus, the conductive plug 258 is a tungsten plug, an aluminum plug or a copper plug.

In the polishing process, when the conductive layer is a tungsten layer, in order to form a cooling pad for polishing the conductive layer, KH 2 PO 4, KOH (or NH 4 OH), and K 3 [Fe (CN) 6] are used as chemical etchant, respectively. Is used in a mixing ratio of 1 to 100: 1 to 10: 1 to 100.

When the conductive layer is tungsten, in addition to the chemical agent, HNO 3: HF may be mixed and used in a ratio of 1 to 100: 1 to 20, respectively, or only H202 may be used.

When the aluminum layer is used as the conductive layer, HNO 3, CH 3 COOH, H 3 PO 4 are mixed and used in a mixing ratio of 1 to 20: 1 to 100: 1 to 100 as the chemical etchant used to form the cooling pad. .

When the copper layer is used as the conductive layer, CuCl 2, H202, or FeCl 2 may be mixed with pure water as the chemical agent, but may be mixed with a mixing ratio of 1 to 100: 1 to 500.

The temperature directly applied to the substrate 200 during the polishing of each conductive layer is preferably maintained at -30 ° C to 300 ° C depending on the desired polishing rate.

Other polishing conditions other than that are maintained in the same manner as in the first embodiment.

Fourth Example

In the case of using the chemical polishing apparatus of the present invention in a dual damascene manufacturing process, as shown in FIG. 22, the lower layer 270 is deposited on the substrate 200 in the first and second damascene processes. The interlayer insulating layer 278 and the stopper layer 280 having the contact holes 272, 274, and 276 exposed are sequentially formed. The interlayer insulating film 278 is formed to a thickness of 5,000 to 30,000 kPa. The stopper layer 280 is formed of a nitride film. Next, a conductive layer (not shown) filling the contact holes 272, 274, and 276 is formed on the stopper layer 280. The entire surface of the conductive layer is polished using the chemical polishing apparatus of the present invention, for example, the polishing apparatus according to the first embodiment, but polished until the stopper layer 280 is exposed.

In the polishing process, the conductive layer is formed of a tungsten layer, an aluminum layer, or a copper layer. At this time, the chemical agent and other conditions used to form the cooling pad 100 for polishing each conductive layer are the same as in the third embodiment.

In the chemical polishing method according to the first to fourth embodiments, when material films having different properties are sequentially formed on a substrate, for example, a polysilicon layer, a BPSG film, and a tungsten layer are sequentially formed on the substrate. In the case where the material layer is polished in reverse order, it is difficult to carry out with one cooling pad. Thus, as shown in FIG. 23, the first to the first to uniformly cool the chemical solution suitable for polishing each of the material layers. 3, preparing the cooling pads 300, 310, and 320 and polishing the tungsten layer using the first cooling pad 300, and the BPSG film using the second cooling pad 310, and the polysilicon layer being made of 3 Polish using the cooling pad 320. The first to third cooling pads 300, 310, and 320 are rotated at positions fixed to the rotation shaft 330. Therefore, when the tungsten layer is polished, the first cooling pad 300 is rotated and positioned under the substrate 340, and then the substrate 340 is contacted with the first cooling pad 300 to be polished. The same process is performed when the second and third cooling pads 310 and 320 are used.

Fifth Embodiment

Wafers used in the manufacture of semiconductor devices are formed by slicing ingots of semiconductor material to a thin thickness and polishing the surface. The surface of the initial bare wafer separated from the ingot is not only flat, but there are also many kinds of contaminants.

A fifth embodiment relates to the polishing of an initial bare wafer surface separated from an ingot.

Referring to FIG. 24, the first step 400 is to cut an ingot into a thin thickness to form an initial bare wafer for use in manufacturing a semiconductor device.

The second step 402 is to grind the surface of the initial bare wafer in a chemical polishing apparatus in which chemicals required for polishing are self-supplied in the polishing process.

Specifically, any one selected from the chemical polishing apparatuses according to the first to fifth embodiments of the present invention is selected, and the initial bare wafer is loaded on the selected chemical polishing apparatus and attached to the bottom surface of the wafer head, and the wafer head is attached. The lower surface of the initial bare wafer is polished by compressing the cooling pad and the initial bare wafer while rotating. In this way, as shown in FIG. 25, the bare wafer 410 suitable for the manufacturing process of the semiconductor device whose surface was smoothly planarized is formed.

Meanwhile, the chemical polishing apparatus according to the embodiment of the present invention can also be used to polish the back side of the wafer on which the semiconductor devices such as transistors and capacitors and wirings for connecting the semiconductor devices are prepared according to the recipe on the smooth surface of the wafer. have.

While many details are set forth in the foregoing description, they should be construed as illustrative of preferred embodiments, rather than to limit the scope of the invention. For example, one of ordinary skill in the art to which the present invention pertains may modify the structure of the cooling vessel, and in particular, the shape of the cooling fin 150 may be modified in various forms. In addition, a desired purpose may be achieved by using a compressor or the like in addition to a thermoelectric element to form a cooling pad, and the technical spirit of the present invention may be applied to a multi-chamber. Further, there may be a polishing apparatus in which a conventional wafer head excluding the slurry supply device and the cooling pad of the present invention are combined. Therefore, the scope of the present invention should not be defined by the described embodiments, but should be determined by the technical spirit described in the claims.

As described above, the present invention provides a chemical polishing apparatus having a cooling pad capable of supplying a chemical for polishing itself and a wafer head corresponding thereto, which does not require a slurry and eliminates a strong mechanical property. As described above, when the polishing apparatus of the present invention is used, all problems caused by the use of the slurry, that is, dishing, corrosion, excessive etching, rounding or scratching, etc. can be eliminated because the conventional slurry is not used. Since it is unnecessary and can reduce the associated costs incurred in the process, the overall process cost can be significantly reduced compared to the conventional CMP process.

Claims (30)

In a chemical mechanical polishing (CMP) apparatus used for polishing a material film formed on a wafer using a low temperature chemical polishing process, The chemical mechanical polishing apparatus includes: a wafer head adsorbed on a bottom surface of the chemical mechanical polishing apparatus and capable of uniformly maintaining a temperature of the wafer and a pressure applied to the back surface of the wafer during the polishing process; A cooling pad provided at a position opposite to the wafer head, the surface being flattened to be suitable for polishing the wafer, and having a chemical required for the polishing supplied by itself during the polishing process; A cooling vessel surrounding the bottom and side surfaces of the cooling pad; Cooling means attached to a bottom surface of the cooling container and used to form and maintain the cooling pad; And Polishing apparatus, characterized in that provided with a chamber containing each of the elements and maintained in anhydrous state. The method of claim 1, wherein the wafer head A main body into which the pressurized gas is introduced; A head cooling unit used to cool the wafer; A wafer suction plate attached to a bottom surface of the head cooling unit and generating a temperature difference between a surface facing the cooling pad and a surface attached to the head cooling unit; A wafer guide ring disposed around the wafer suction plate to surround the wafer; And And a vacuum line used for adsorption of the wafer formed through the head cooling unit and the wafer adsorption plate. The chemical polishing apparatus according to claim 1, wherein the chamber is further provided with a flatter for flattening the surface of the cooling pad. According to claim 1, wherein the chemicals constituting the cooling pad is nitric acid (HNO3), hydrofluoric acid (HF), hydrochloric acid (HCl), sulfuric acid (H2SO4), phosphoric acid (H3PO4), ammonia (NH4OH), NH4F, hydrogen peroxide ( H202), TMAH, KH2P04, KOH, K3 [Fe (CN) 6], pure water, CH3COOH, CuCl2, FeCl2 and the like, at least one selected from the group consisting of a chemical polishing apparatus. 2. The chemical polishing apparatus according to claim 1, wherein sensing means for detecting horizontal and interval change of the wafer and the cooling pad is provided in at least one selected from the wafer head and the cooling vessel. The chemical polishing apparatus of claim 1, wherein the cooling container is made of an aluminum alloy, a copper alloy, a titanium alloy, or a stainless steel alloy. The chemical polishing apparatus according to claim 1, wherein the portion of the cooling vessel that is in direct contact with the cooling pad is plated with a Group VIII material on the periodic table and gold (Au). The method of claim 1, wherein the cooling means, First and second thermoelectric elements in contact with a bottom surface of the cooling vessel; And And a cooling unit for removing heat generated from the first and second thermoelectric elements in contact with the entire bottom surface of the first and second thermoelectric elements, wherein the first and second thermoelectric elements have a low temperature on the cooling container side. The chemical polishing apparatus characterized by generating a high temperature on the cooling unit side. The method of claim 8, wherein the main material of the first and second thermoelectric element is mixed with any one of Group 6A Se, Po and Te on the periodic table and any one of Group 5A P, As, Sb and Bi in a constant molar ratio Chemical polishing apparatus, characterized in that formed. The chemical polishing apparatus according to claim 2, wherein a thermoelectric element for generating the temperature difference is provided in the wafer adsorption plate. 3. The portion of the wafer adsorption plate in direct contact with the wafer is made of aluminium, platinum, gold, copper or nickel, and the Group 8 material on the periodic table is plated on the entire surface. Chemical polishing device. 12. The chemical polishing apparatus according to claim 11, wherein other portions of the wafer adsorption plate except for the portion in direct contact with the wafer are made of aluminum, copper, titanium, titanium alloy or stainless steel. 3. The chemical polishing apparatus according to claim 2, wherein the wafer head is connected to a motor which maintains a constant rotation rate at high speed and low speed through a timing belt. The chemical polishing apparatus according to claim 1, wherein a plurality of cooling fins are formed at the bottom of the cooling vessel. 15. The chemical polishing apparatus according to claim 14, wherein a vibrator using a vibration frequency of 10 to 100 MHz is attached to a side surface of the cooling vessel in which a plurality of cooling fins are formed at the bottom. The chemical polishing apparatus according to claim 2, wherein a vibrator is provided on the side of the wafer head. The chemical polishing apparatus according to claim 8, wherein a heating plate having a plurality of fins is provided on the ceiling of the cooling unit. Forming a material layer on the substrate; Moving the substrate on which the material layer is formed to the polishing apparatus of claim 1 and mounting the material layer on a wafer head of the polishing apparatus to face the cooling pad of the polishing apparatus; And Operating the polishing apparatus to polish the surface of the material layer by rotating contacting the entire surface of the material layer to the cooling pad. 19. The method of claim 18, wherein the material layer is formed in direct contact with the substrate or indirectly through the underlying material film. The polishing method according to claim 18, wherein the material layer is formed of at least one selected from a conductive layer, an insulating layer, and a mixed layer composed of the conductive layer and the insulating layer. The polishing method according to claim 20, wherein the conductive layer is formed of a polysilicon layer, a tungsten layer, an aluminum layer, or a copper layer. The method of claim 21, wherein when the conductive layer is the polysilicon layer, the cooling pad for polishing the conductive layer is mixed with hydrofluoric acid, nitric acid, hydrogen peroxide and TMAH or NH4OH, wherein the hydrofluoric acid to nitric acid is 1 to 10:50 Mixing at a mixing ratio of ˜1,000 and mixing the hydrogen peroxide solution with TMAH (or NH 4 OH) at a mixing ratio of 100 to 300: 100 to 500; Polishing the mixed chemical solution is formed through the step of uniformly cooling below the freezing point using a thermoelectric element. 22. The method of claim 21, wherein when the conductive layer is the tungsten layer, the cooling pad for polishing the conductive layer includes KH 2 PO 4, KOH (or NH 4 OH), and K 3 [Fe (CN) 6] 1 to 100: 1 to 10: 1. Mixing at a mixing ratio of ˜100; Filling the cooling vessel with the mixed chemical solution; And Polishing the mixed chemical solution is formed through the step of uniformly cooling below the freezing point using a thermoelectric element. The method of claim 21, wherein when the conductive layer is a tungsten layer, the cooling pad for polishing the conductive layer is Mixing HNO 3: HF in a ratio of 1 to 100: 1 to 20, respectively; Filling the cooling vessel with the mixed chemical solution; And Polishing the mixed chemical solution is formed through the step of uniformly cooling below the freezing point using a thermoelectric element. 22. The method of claim 21, wherein when the conductive layer is a tungsten layer, the cooling pad for polishing the conductive layer comprises: filling H2O2 with the cooling vessel; And Polishing method for forming the H202 through the step of uniformly cooling below the freezing point using a thermoelectric element. The method of claim 21, wherein when the conductive layer is an aluminum layer, the cooling pad for polishing the conductive layer is Mixing HNO 3, CH 3 COOH, and H 3 PO 4 in a mixing ratio of 1 to 20: 1 to 100: 1 to 100; Filling the cooling vessel with the mixed chemical solution; And Polishing the mixed chemical solution is formed through the step of uniformly cooling below the freezing point using a thermoelectric element. The cooling pad of claim 21, wherein the cooling pad is in the case where the conductive layer is a copper layer. Mixing CuCl 2, H202, or FeCl 2 with pure water at a mixing ratio of 1 to 100: 1 to 500; Filling the cooling vessel with the mixed chemical solution; And Polishing the mixed chemical solution is formed through the step of uniformly cooling below the freezing point using a thermoelectric element. Cutting the ingot to form an initial bare wafer; Loading the initial bare wafer onto a cooling pad of the polishing apparatus of claim 1; And Operating the polishing apparatus to polish the initial bare wafer loaded on the cooling pad. 29. The method of claim 28, wherein the initial bare wafer is a silicon (Si) wafer or a arsenic gallium (GaAs) wafer. The polishing method according to any one of claims 23 to 25, wherein after the cooling pad is formed, its surface is planarized to be suitable for wafer polishing.