JP7349975B2 - CMP polishing equipment - Google Patents

Description

The present invention relates to a CMP polishing apparatus.

Conventional CMP polishing apparatuses are disclosed in Patent Documents 1 and 2. These CMP polishing apparatuses include a carrier, a surface plate, a drive device, a polishing liquid supply device, and a control device.

An object to be polished is fixed to the carrier. The objects to be polished include wafers of Si, SiC, etc., wafers with films on which films such as insulating films, wiring metal films, exposure resists, and protective films are formed. A polishing pad is fixed to the surface plate so as to face the object to be polished. These CMP polishing apparatuses employ polishing pads made of nonwoven fabric, foamed polyurethane, or the like. This polishing pad has a polishing surface that contacts the object to be polished, and concentric or lattice-shaped polishing grooves that are recessed from the polishing surface.

The drive device moves the carrier and the surface plate at a relative speed while applying a load between the object to be polished and the polishing pad. The polishing liquid supply device interposes the polishing liquid between the object to be polished and the polishing pad. In these CMP polishing apparatuses, the polishing liquid contains a chemical such as NaOH and polishing particles such as colloidal silica. The control device controls at least the drive device and the polishing liquid supply device.

Further, these CMP polishing apparatuses attempt to detect the depth of wear on the polishing surface by detecting the thickness of the polishing pad or by having an operator visually observe an indicator included in the polishing pad.

These CMP polishing apparatuses can polish an object to be polished by a CMP (chemical mechanical polishing) method that performs mechanical polishing using abrasive particles and chemical polishing using chemicals at the same time. At this time, a polishing pad having polishing grooves is used to ensure a sufficient amount of polishing particles in the polishing grooves to make the polishing effect of the object to be polished effective. In addition, these CMP polishing apparatuses optimize the next polishing time and predict the life of the polishing pad by detecting the depth of wear on the polishing surface.

Japanese Patent Application Publication No. 2005-347568 Japanese Patent Application Publication No. 2019-145779

However, since the conventional CMP polishing apparatus described above uses a polishing liquid containing abrasive particles when polishing the object to be polished, many abrasive particles are present on the polishing surface and polishing grooves, and the wear of the polishing surface cannot be detected. Insufficient accuracy. In particular, these CMP polishing devices try to detect the depth of wear on the polishing surface based on the thickness of the polishing pad and visual inspection, so the detected value varies due to differences in the thickness of the adhesive layer between the surface plate and the polishing pad and individual differences. Therefore, the detection accuracy is unreliable.

The present invention has been made in view of the above-mentioned conventional situation, and the problem to be solved is to provide a CMP polishing apparatus that can highly accurately detect wear on the polished surface while optimizing the polishing effect of the object to be polished. It is said that

The CMP polishing apparatus of the present invention includes a carrier to which an object to be polished is fixed, a surface plate to which a polishing pad is fixed so as to face the object to be polished, and a load between the object to be polished and the polishing pad. a driving device that moves the carrier and the surface plate at a relative speed while adding a polishing liquid supply device that interposes a polishing liquid between the object to be polished and the polishing pad; A CMP polishing apparatus that polishes the object to be polished by a CMP method, the CMP polishing apparatus comprising:
The polishing pad has a polishing surface in contact with the object to be polished, and a polishing groove recessed from the polishing surface,
Further comprising a wear depth measuring means for non-contactly measuring the wear depth of the polishing surface with reference to the bottom surface of the polishing groove, and a dresser for dressing the polishing surface ,
The polishing pad is made of resin and has a base material in which a plurality of bubbles are formed, and abrasive particles held within the base material or within the bubbles,
The polishing liquid is only liquid,
The control device controls the load, the speed, the polishing time, and the supply of the polishing fluid by transmitting a control signal to the drive device and/or the polishing fluid supply device when the wear depth exceeds a first threshold value. If the wear depth exceeds a second threshold value that is larger than the first threshold value, the polishing of the object to be polished is interrupted and the dresser is operated, and after the dressing is performed, The method is characterized in that polishing of the object to be polished is restarted .

The CMP polishing apparatus of the present invention employs a polishing pad that is made of resin and has a base material in which a plurality of bubbles are formed, and abrasive particles held within the base material or within the bubbles, and the polishing liquid is liquid. Only. Therefore, it is difficult for polishing particles to exist on the polishing surface or in the polishing grooves.

In addition, in this CMP polishing apparatus, since the wear depth measuring means measures the wear depth of the polishing surface using the bottom surface of the polishing groove as a reference, even if the thickness of the adhesive layer between the surface plate and the polishing pad is different, the polishing Surface wear depth can be measured geometrically. At this time, the wear depth of the polished surface is measured without contact, so there is no error caused by the pressing force caused by contact.

Furthermore, since this CMP polishing apparatus employs a polishing pad having polishing grooves, the polishing particles held by the polishing surface facing the polishing grooves effectively polish the object to be polished.

Therefore, in the CMP polishing apparatus of the present invention, it is possible to achieve high accuracy in detecting wear on the polishing surface while making the polishing effect of the object to be polished effective.

The control device transmits a control signal to the drive device and/or the polishing liquid supply device if the wear depth exceeds the first threshold value . Therefore , it is possible to know when to replace the polishing pad according to the depth of wear, and it is also possible to improve the quality of the object to be polished by changing the polishing conditions.

The control device changes at least one of the load, speed, polishing time, and polishing liquid supply amount according to the control signal . Therefore, the quality of the object to be polished can be improved by changing the polishing conditions depending on the depth of wear.

The CMP polishing apparatus further includes a dresser for dressing the polishing surface . Then, if the wear depth exceeds a second threshold value that is greater than the first threshold value, the control device suspends polishing of the object to be polished, operates the dresser, and resumes polishing of the object to be polished after dressing has been performed. Ru. Therefore , the polishing pad can be regenerated depending on the depth of wear.

The wear depth measuring means can measure the wear depth of the polished surface in a non-contact manner using ultrasonic waves or light, but is preferably a dimension measuring device using a laser beam. According to the inventor's confirmation, in this case, the wear depth can be measured accurately within ±0.2 to 0.3 μm. For example, the three-dimensional measuring machine "XM-2000" manufactured by Keyence Corporation, the three-dimensional sensor "Gocator (registered trademark)" manufactured by Lynx Corporation, and the "Laser Scan Micrometer LSM" non-contact, high-precision laser length measurement system manufactured by Mitutoyo Corporation. ” etc. can be adopted.

The CMP polishing apparatus of the present invention can achieve high accuracy in detecting wear on the polishing surface while making effective the polishing effect of the object to be polished.

FIG. 1 is a schematic cross-sectional view showing the main parts of a CMP polishing apparatus according to an embodiment. FIG. 2 is a block diagram of a control device, etc. of the CMP polishing apparatus of the embodiment. FIG. 3 is a schematic enlarged sectional view of a polishing pad in the CMP polishing apparatus of the embodiment. FIG. 4 is a flowchart of a program executed by the control device in the CMP polishing apparatus of the embodiment. FIG. 5 is a flowchart of a program executed by the control device in the CMP polishing apparatus of the embodiment. FIG. 6 is a schematic enlarged cross-sectional view of a polishing pad in a CMP polishing apparatus of a comparative example.

Embodiments embodying the present invention will be described below with reference to the drawings. As shown in FIG. 1, the CMP polishing apparatus of the embodiment includes a plurality of carriers 1, a surface plate 3, a drive device 5, a polishing liquid supply device 7, a dresser 9, a dimension measuring device 11, and As shown in FIG.

Although only a single carrier 1 is shown in FIG. 1, the CMP polishing apparatus has a plurality of carriers 1. Each carrier 1 has a horizontal disk shape. A plurality of recesses 1a are formed in the lower surface of each carrier 1, and a workpiece W to be polished is fixed to each recess 1a. The object to be polished W is a wafer of Si, SiC, etc., or a wafer with a film on which a film such as an insulating film, a wiring metal film, an exposure resist, a protective film, etc. is formed. A carrier rotating shaft 1b is vertically projected from the upper surface of each carrier 1. A surface W1 to be polished of the object W to be polished faces downward.

The surface plate 3 has a horizontal disk shape that encloses all the carriers 1. A surface plate rotating shaft 3a is vertically protruded from the lower surface of the surface plate 3. A disk-shaped polishing pad 15 is fixed to the upper surface of the surface plate 3 with an adhesive so as to face each object W to be polished. As shown in FIG. 3, the polishing pad 15 has a polishing surface 15a that contacts the object W to be polished, and concentric or lattice-shaped polishing grooves 15b recessed downward from the polishing surface 15a. The shape, pitch, width, etc. of the polishing grooves 15b are selected for each user depending on the object W to be polished.

The polishing pad 15 is made of resin and includes a base material 151 in which a plurality of bubbles 151a are formed, and polishing particles 152 held within the base material 151 or within the bubbles 151a.

The base material 151 includes polyether, rigid polyurethane foam, epoxy resin, polyethersulfone (PES) resin, as well as polyvinyl fluoride, vinyl fluoride/hexafluoropropylene copolymer, polyvinylidene fluoride, and vinylidene fluoride/hexafluoride. The material is selected from fluorine-based synthetic resins such as fluoropropylene copolymer, polyethylene resins, polymethyl methacrylate, etc., depending on the object W to be polished, etc., for each user.

The abrasive particles 152 include diamond, CBN (cubic boron nitride), B ₄ C (boron carbide), CeO ₂ , silicon carbide, silica, alumina, zirconia, titania, manganese oxide, barium carbonate, chromium oxide, iron oxide, etc. , and is selected for each user depending on the object W to be polished and the like.

As shown in FIG. 1, the drive device 5 includes a main drive device 5a, a sub drive device 5b, and a pressure device 5c. The main drive device 5a rotates the surface plate rotating shaft 3a around the first axis O1 at a predetermined speed. The sub-drive device 5b rotates each carrier rotating shaft 1b around the second axis O2 at a predetermined speed. The pressure device 5c applies pressure to each carrier rotating shaft 1b and the sub-drive device 5b toward the surface plate 3 with a predetermined load.

The polishing liquid supply device 7 is provided above the surface plate 3. The polishing liquid supply device 7 interposes the polishing liquid 7a between the object W to be polished and the polishing pad 15. The polishing liquid 7a is selected from NaOH aqueous solution, potassium permanganate aqueous solution, amine-based aqueous solution, etc. for each user depending on the object W to be polished. The polishing liquid 7a does not contain polishing particles 152 and is a liquid.

The dresser 9 is provided above the surface plate 3 so as to be movable from near the first axis O1 to the outer periphery of the polishing pad 15. The dresser 9 contacts the polishing surface 15a of the polishing pad 15 and dresses the polishing surface 15a.

The dimension measuring device 11 is provided above the surface plate 3. The dimension measuring device 11 uses a laser beam 11a to non-contactly measure the wear depth of the polished surface 11a with the bottom surface of the polished groove 15b as a reference.

As shown in FIG. 2, the control device 13 is composed of an electronic circuit unit including a microcomputer, a memory, an interface circuit, etc., and includes a dimension measuring device 11, a main drive device 5a, a sub-drive device 5b, a pressure device 5c, and It is connected to the polishing liquid supply device 7. A program for controlling these is stored in the memory of the control device 13.

In this CMP polishing apparatus, when polishing the object W to be polished by the CMP method, the operation is started after the object W to be polished is fixed in the recess 1a of each carrier 1. Thereby, the control device 13 performs the processing shown in the flowcharts shown in FIGS. 4 and 5.

First, as shown in FIG. 4, in step S1, the pressure device 5c applies a load F to pressurize each carrier rotation shaft 1b and the sub-drive device 5b toward the surface plate 3, and the main drive device 5a applies pressure to the surface plate rotation shaft. 3a, a second speed V2 at which the sub-drive device 5b rotates each carrier rotating shaft 1b, a polishing time T, and a supply amount Q of the polishing liquid 7a supplied by the polishing liquid supply device 7. is input.

Therefore, while applying a load F between the object W to be polished and the polishing pad 15, each carrier 1 and the surface plate 3 move at a relative speed for the polishing time T. During this time, the polishing liquid supply device 7 supplies a supply amount Q of the polishing liquid 7a. In this way, polishing is started. At this time, since the polishing pad 15 having the polishing grooves 15b is employed, the polishing particles 152 held by the polishing surface 15a facing the polishing grooves 15b effectively polish the object W to be polished.

Thereafter, in step S2, the dimension measuring device 11 measures the distance L1 to the polishing groove 15b, and in step S3, the dimension measuring device 11 measures the distance L2 to the polishing surface 15a. Then, in step S4, the difference between the distance L1 and the distance L2 is calculated, and this is set as the wear depth Lx of the polished surface 15a. As the polishing continues, the wear depth Lx gradually increases.

In step S5, it is determined whether the wear depth Lx exceeds the first threshold value La even within the polishing time T. In step S5, if the wear depth Lx exceeds the first threshold La, the process proceeds to step S6, and if the wear depth Lx does not exceed the first threshold La, the process returns to step S3.

In step S6, a control signal is transmitted to the main drive device 5a, the sub drive device 5b and/or the pressurizing device 5c, and the load F, the first speed V1, the second speed V2, the polishing time T and the supply amount of the polishing liquid 7a are transmitted. Change at least one of Q. Which of these should be changed is selected by the user depending on the object W to be polished and the like. In this way, in this CMP polishing apparatus, the quality of the object W to be polished can be improved by changing the polishing conditions.

After that, in step S7, it is determined whether the wear depth Lx exceeds the second threshold Lb. In step S7, if the wear depth Lx exceeds the second threshold Lb, the process proceeds to step S8, and if the wear depth Lx does not exceed the second threshold Lb, the process returns to step S7. In this way, the polishing conditions are changed to improve the quality of the polished object W until the wear depth Lx exceeds the first threshold value La and reaches the second threshold value Lb.

In step S8, since the wear depth Lx exceeds the second threshold Lb and the polishing pad 15 should be regenerated, polishing is interrupted. At this time, the second speed V2 is set to 0 and each carrier 1 separates from the polishing pad 15. Then, in the subsequent step S9, the dresser 9 is operated. At this time, the first speed V1 is set at a constant speed, and the dresser 9 moves above the surface plate 3 from near the first axis O1 to the outer peripheral portion of the polishing pad 15. As a result, the polishing surface 15a of the polishing pad 15 is dressed.

After this, as shown in FIG. 5, the process advances to step S10, and polishing is restarted. Then, in step S11, it is determined whether the wear depth Lx exceeds the third threshold Lc. In step S11, if the wear depth Lx exceeds the third threshold Lc, the process proceeds to step S12, and if the wear depth Lx does not exceed the third threshold Lc, the process returns to step S3.

In step S12, it is reported that the wear depth Lx exceeds the third threshold Lc and that the polishing pad 15 is nearing the end of its life. Specifically, an indicator lamp provided in the control device 13 lights up. In this way, in this CMP polishing apparatus, it is possible to know when to replace the polishing pad 15 according to the wear depth Lx.

In the following step S13, it is determined whether the wear depth Lx exceeds the fourth threshold Ld. Step S13 is repeated until the wear depth Lx exceeds the fourth threshold Ld. In step S13, if the wear depth Lx exceeds the fourth threshold Ld, the process proceeds to step S14 and polishing is stopped.

In this way, this CMP polishing apparatus employs a polishing pad 15 that is made of resin and has a base material 151 in which a plurality of bubbles 151a are formed, and abrasive particles 152 held within the base material 151 or within the bubbles 151a. In this case, the polishing liquid 7a is only liquid. Therefore, as shown in FIG. 3, it is difficult for polishing particles 152 to exist on the polishing surface 15a and polishing grooves 15b.

In addition, in this CMP polishing apparatus, since the dimension measuring device 11 measures the wear depth Lx of the polishing surface 15a using the bottom surface of the polishing groove 15b as a reference, even if the thickness of the adhesive layer between the surface plate 3 and the polishing pad 15 is different. However, the wear depth Lx of the polished surface 15a can be measured geometrically. At this time, since the wear depth Lx of the polished surface 15a is measured in a non-contact manner, no error occurs due to the pressing force due to contact.

Therefore, in this CMP polishing apparatus, it is possible to achieve high accuracy in detecting the wear of the polishing surface 15a while making effective the polishing effect of the object W to be polished.

On the other hand, as shown in FIG. 6, in the CMP polishing apparatus, when a polishing pad 16 made of nonwoven fabric or the like that does not hold abrasive particles 152 is used, and a polishing liquid having abrasive particles 152 is used, the polishing Many abrasive particles 152 exist on the surface 15a and the abrasive grooves 15b. Therefore, in this case, even if the dimension measuring device 11 using a laser beam is used, wear on the polished surface 15a can only be detected with low accuracy.

Although the present invention has been described above based on examples, it goes without saying that the present invention is not limited to the above-mentioned examples, and can be applied with appropriate modifications without departing from the spirit thereof.

For example, the CMP polishing apparatus of the present invention includes a carrier that exposes the upper and lower surfaces of the object to be polished, a first surface plate located below the carrier, and a second surface plate located above the carrier, It is also possible to simultaneously polish the upper and lower surfaces of the object to be polished.

Further, the dimension measuring device 11 may be provided above the surface plate 3 so as to be movable from near the first axis O1 to the outer peripheral portion of the polishing pad 15. In this case, since the wear depths of the plurality of polishing surfaces 15a existing from near the first axis O1 to the outer peripheral portion of the polishing pad 15 can be measured without contact, the control device 13 calculates the average value of the wear depths. , the driving device 5 etc. can be controlled by this average value.

The polishing groove 15b that serves as a reference for the polishing depth Lx may only serve as a reference that is not used when polishing the object W to be polished.

The present invention can be used in semiconductor manufacturing equipment.

W...Object to be polished 1...Carrier 15...Polishing pad 3...Surface plate 5...Drive device (5a...Main drive device, 5b...Subdrive device, 5c...Pressure device)
7a... Polishing liquid 7... Polishing liquid supply device 13... Control device 15a... Polishing surface 15b... Polishing groove Lx... Wear depth 11... Wear depth measuring means (dimensional measuring device)
151a... Air bubbles 151... Base material 152... Abrasive particles F... Load V1, V2... Speed (V1... first speed, V2... second speed)
T...Polishing time Q...Supply amount 9...Dresser

Claims (2)

A carrier to which an object to be polished is fixed, a surface plate to which a polishing pad is fixed so as to face the object to be polished, and a load is applied between the object to be polished and the polishing pad, and the carrier is a drive device that moves the surface plate at a relative speed; a polishing liquid supply device that interposes a polishing liquid between the object to be polished and the polishing pad; and at least the drive device and the polishing liquid supply device. In a CMP polishing apparatus for polishing the object to be polished by a CMP method,
The polishing pad has a polishing surface in contact with the object to be polished, and a polishing groove recessed from the polishing surface,
Further comprising a wear depth measuring means for non-contactly measuring the wear depth of the polishing surface with reference to the bottom surface of the polishing groove, and a dresser for dressing the polishing surface ,
The polishing pad is made of resin and has a base material in which a plurality of bubbles are formed, and abrasive particles held within the base material or within the bubbles,
The polishing liquid is only liquid,
The control device controls the load, the speed, the polishing time, and the supply of the polishing fluid by transmitting a control signal to the drive device and/or the polishing fluid supply device when the wear depth exceeds a first threshold value. If the wear depth exceeds a second threshold value that is larger than the first threshold value, the polishing of the object to be polished is interrupted and the dresser is operated, and after the dressing is performed, A CMP polishing apparatus characterized in that the polishing of the object to be polished is restarted . 2. The CMP polishing apparatus according to claim 1 , wherein said wear depth measuring means is a dimension measuring device using a laser beam.

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