CMP composite groove polishing pad

Description

CROSS REFERENCE OF RELATED APPLICATION

The present invention claims priority under 35 U.S.C. 119(a-d) to CN 201810875035.8, filed Aug. 3, 2018.

BACKGROUND OF THE PRESENT INVENTION

Field of Invention

The present invention relates to the field of chemical mechanical polishing (CMP), and more particularly to a CMP composite groove polishing pad.

Description of Related Arts

Chemical mechanical polishing (CMP) is a micro-nano processing technology that combines mechanical grinding with chemical oxidation to remove the surface material of machined workpieces. The surface of the machined workpieces is ultra-flat and ultra-smooth through the CMP process, so that the CMP process is mainly used in the field of IC and MEMS manufacturing. During the CMP process, a rotating wafer is pressed onto a rotating polishing pad, and a polishing liquid containing abrasive particles and chemicals flows between the wafer and the polishing pad, so that the surface material of the wafer is continuously removed under the chemical action of the chemicals in the polishing liquid, and the mechanical action of the abrasive particles and the polishing pad. The polishing pad plays a very important role in the CMP process. A complete polishing pad from top to bottom comprises a substrate, a back-adhesive layer and a supporting base in sequence, wherein the substrate is in contact with the wafer and mainly for grinding and polishing, the back-adhesive layer bonds the substrate and the supporting base together, and the supporting base mainly serves as a support. In order to ensure that the polishing liquid has a sufficient action time on the substrate, a groove is usually engraved on the substrate to store the polishing liquid, and the shape and size of the groove on the substrate of the polishing pad directly affect the transportation of the polishing liquid in the polishing area, the uniform distribution, the residence time, and the mixing efficiency of new and old polishing liquids. In addition, the polishing effect is affected by factors such as relative speed, the surface contact pressure, and the surface friction between the wafer and the polishing pad, all of which are related to the shape of the groove on the substrate of the polishing pad.

At present, the groove on the substrate of the existing polishing pad has mainly a single annular shape, the polishing removal rate of the wafer is low, and the transportation and uniform distribution ability of the polishing liquid is low.

SUMMARY OF THE PRESENT INVENTION

An object of the present invention is to provide a CMP composite groove polishing pad, which solves problems that the groove on the substrate of the polishing pad is mainly annular in shape, the removal rate of the wafer is low and the transportation and uniform distribution ability of the polishing liquid is low.

The present invention provides a technical solution as follows.

A CMP (chemical mechanical polishing) composite groove polishing pad comprises a polishing pad substrate and has a rotation center located in a middle of the polishing pad substrate, a first groove, a second groove and a third groove, wherein all of the first groove, the second groove and the third groove are provided on the polishing pad substrate; the first groove and the second groove are communicated with each other end to end to form a petal-shaped composite groove.

Preferably, the first groove comprises at least two positive spiral logarithmic sub grooves each of which is a forward semicircular curve radially distributed along the polishing pad substrate, starts from the rotation center and ends with an edge of the polishing pad substrate.

Preferably, the first groove comprises two to eight positive spiral logarithmic sub grooves.

Preferably, the second groove comprises at least two negative spiral logarithmic sub grooves each of which is a reverse semicircular curve radially distributed along the polishing pad substrate, starts from the rotation center and ends with the edge of the polishing pad substrate.

Preferably, the second groove comprises two to eight negative spiral logarithmic sub grooves.

Preferably, an angle in a range of 0-150 degrees is formed at a junction of the third groove and each of the positive spiral logarithmic sub grooves of the first groove, and an angle in a range of 0-150 degrees is also formed at a junction of the third groove and each of the negative spiral logarithmic sub grooves of the second groove.

Preferably, each of the positive spiral logarithmic sub grooves of the first groove, each of the negative spiral logarithmic sub grooves of the second groove, and the third groove has a width in a range of 0.2 to 2.0 mm.

Preferably, each of the first groove, the second groove and the third groove has a depth in a range of 0.5 to 2.5 mm.

Preferably, there are at least two third grooves which are at least two concentric annular grooves centered on the rotation center, respectively.

Compared with the prior art, the present invention has some beneficially effects as follows.

(1) The present invention has a petal-shaped composite groove formed by communicating a first groove with a second groove end to end on a polishing pad, so as to evenly distribute and transport a polishing liquid and obtain a high removal rate of a wafer.

(2) The present invention has a petal-shaped composite groove formed by communicating the first groove with the second groove end to end on the polishing pad, so as to prolong the residence time and facilitate the discharge of the waste polishing liquid, so that the petal-shaped composite groove is not clogged during operation.

(3) All of the first groove, the second groove and the third groove on the polishing pad substrate provided by the present invention have a certain range of angle, width and depth, so that the transportation and distribution of the polishing liquid, the residence time, and the discharge of the waste polishing liquid reach the optimal state.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a structurally schematic view of a CMP composite groove polishing pad provided by the present invention.

FIG. 2 is a polishing rate data map of a single annular groove polishing pad and a composite groove polishing pad provided by the present invention.

In the drawings, 1: polishing pad substrate; 101: rotation center; 2: first groove; 201: positive spiral logarithmic sub groove; 3: second groove; 202: negative spiral logarithmic sub groove; 4: third groove.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

All of the features disclosed in this specification, in addition to mutually exclusive features and/or steps, may be combined in any form.

The present invention is described in detail with accompanying drawings as follows.

First Embodiment

A CMP (chemical mechanical polishing) composite groove polishing pad according to a first embodiment of the present invention comprises a polishing pad substrate 1 and has a rotation center 101 located in a middle of the polishing pad substrate 1, a first groove 2, a second groove 3 and a third groove 4, wherein all of the first groove 2, the second groove 3 and the third groove 4 are provided on the polishing pad substrate 1; the first groove 2 and the second groove 3 are connected with each other end to end to form a petal-shaped composite groove.

The petal-shaped composite groove formed by the first groove 2 and the second groove 3 is able to evenly distribute and transport the polishing liquid, prolong the residence time and facilitate the discharge of the waste polishing liquid, and the petal-shaped composite groove is not clogged during operation.

Second Embodiment

Based on the first embodiment, the CMP composite groove polishing pad is further described according to a second embodiment of the present invention, wherein the first groove 2 comprises at least two positive spiral logarithmic sub grooves 201 each of which is a forward semicircular curve radially distributed along the polishing pad substrate 1, starts from the rotation center 101 and ends with an edge of the polishing pad substrate 1, so that the petal-shaped composite groove is able to be formed.

Third Embodiment

Based on the second embodiment, the CMP composite groove polishing pad is further described according to a third embodiment of the present invention, wherein the first groove 2 comprises two to eight positive spiral logarithmic sub grooves 201 so as to form the petal-shaped composite groove.

Fourth Embodiment

Based on the first embodiment, the CMP composite groove polishing pad is further described according to a fourth embodiment of the present invention, wherein the second groove 3 comprises at least two negative spiral logarithmic sub grooves 202 each of which is a reverse semicircular curve radially distributed along the polishing pad substrate 1, starts from the rotation center 101 and ends with the edge of the polishing pad substrate 1, so that the petal-shaped composite groove is able to be formed.

Fifth Embodiment

Based on the fourth embodiment, the CMP composite groove polishing pad is further described according to a fifth embodiment of the present invention, wherein the second groove 3 comprises two to eight negative spiral logarithmic sub grooves 202 so as to form the petal-shaped composite groove.

Sixth Embodiment

Based on any one the first embodiment, the second embodiment and the fourth embodiment, the CMP composite groove polishing pad is further described according to a sixth embodiment of the present invention, wherein an angle in a range of 0-150 degrees is formed at a junction of the third groove 4 and each of the positive spiral logarithmic sub grooves 201 of the first groove 2, and an angle in a range of 0-150 degrees is also formed at a junction of the third groove 4 and each of the negative spiral logarithmic sub grooves 202 of the second groove 3, so as to facilitate the discharge of the waste polishing liquid.

Seven Embodiment

Based on any one of the first embodiment, the second embodiment and the fourth embodiment, the CMP composite groove polishing pad is further described according to a seventh embodiment of the present invention, wherein each of the positive spiral logarithmic sub grooves 201 of the first groove 2, each of the negative spiral logarithmic sub grooves 202 of the second groove 3, and the third groove 4 have a width in a range of 0.2 to 2.0 mm, so as to evenly distribute and transport the polishing liquid.

Eighth Embodiment

Based on any one of the first embodiment, the second embodiment and the fourth embodiment, the CMP composite groove polishing pad is further described according to an eighth embodiment of the present invention, wherein each of the first groove 2, the second groove 3 and the third groove 4 has a depth in a range of 0.5 to 2.5 mm, so as to prolong the residence time of the polishing liquid.

Ninth Embodiment

Based on any one of the first embodiment, the second embodiment, the third embodiment, the fourth embodiment and the fifth embodiment, the CMP composite groove polishing pad is further described according to a ninth embodiment of the present invention, wherein there are at least two third grooves 4 which are respectively at least two concentric annular grooves centered on the rotation center 101 for communicating with the petal-shaped composite groove, so as to better transport and distribute the polishing liquid.

Experimental Part

The wafer was subjected to a comparative experiment using a single annular groove polishing pad and the composite groove polishing pad provided by the present invention. Four time points were selected during the experiment, which were 0.5 h, 2 h, 5 h, 8 h, respectively. Select 21 test points along the diameter direction on three wafers to test the removal rate (RR) of the wafers, and finally calculate the average value of the removal rates of the three wafers to obtain the data map. As shown in FIG. 2, the abscissa axis is the 21 test points selected along the diameter direction on the wafer; the ordinate axis is the removal rate, and a unit of the removal rate is A/min; BL is the removal rate of the wafer when using a single annular groove polishing pad; S is the removal rate of the wafer when using the composite groove polishing pad provided by the present invention.

It can be seen from FIG. 2 that the RRs of the wafer by the single annular groove polishing pad at 0.5 h, 2 h, 5 h and 8 h are lower than those of the wafer by the composite groove polishing pad provided by the present invention. Also, it can be seen that the RRs of the 21 test points on the wafer by the single annular groove polishing pad are uneven, unstable and undulating; and the RRs of the 21 test points on the wafer by the composite groove polishing pad provided by the present invention are stable and average.