KR100436825B1 - Polishing apparatus and method for producing semiconductors using the apparatus - Google Patents

Abstract

The present invention relates to a polishing apparatus and a semiconductor manufacturing method using the same. By grinding the dressing of the grindstone surface by dimensional machining, the dressing tool surface can be sharpened while preventing the cracking of the grindstone surface that causes scratches. In addition, because of the fixed number cutting, the flatness of the surface of the dressing tool can be assured, and even if several centimeters of thickness and a thick grindstone are used, the flatness can be maintained until the end, and processing with less in-plane unevenness can always be performed. As a result, the life of the dressing tool can be dramatically increased.

In addition, by performing the stationary water dress in parallel with the processing of the wafer, the throughput of the device can be improved while maintaining the processing rate.

The apparatus and method are effective for flattening various substrate surfaces having irregularities.

Description

Polishing device and semiconductor manufacturing method using the device {POLISHING APPARATUS AND METHOD FOR PRODUCING SEMICONDUCTORS USING THE APPARATUS}

Background Art In recent years, as the processing time of semiconductor devices is increased and miniaturized, multilayer wiring technology for stacking circuit elements of semiconductor devices has become important. With the advance of this multilayer wiring technology, the problem of the unevenness | corrugation formed in the sample surface has come to the present. For example, when a circuit pattern is formed on a sample surface by an optical exposure apparatus (hereinafter referred to as a stepper), the focus of the stepper needs to be precisely aligned on the sample surface. Difficulties in adjusting the focus cause a serious problem of resolution.

In order to alleviate such disadvantages, a technology for planarizing the surface of the semiconductor device is required.

Japanese Patent Laid-Open No. 10-146750 discloses a technique for planarizing fine concavo-convex formation on the surface of a semiconductor device. According to the technique disclosed in the above publication, the wafer to be processed held on the rotating holder is pressed onto the surface of the polishing pad held on the rotating table, and the polishing liquid containing glass abrasive particles is subjected to polishing pad and blood. By supplying between the processing wafers, the surface of the semiconductor wafer substrate can be polished to flatten fine irregularities.

The polishing pad used for such polishing is bladed (dressed) at an appropriate frequency due to the glazing of the surface during use. Sharpening is performed by cutting a polishing pad with a dressing diamond grindstone or the like (hereinafter referred to as a dressing tool) as described in Japanese Patent Application Laid-open No. Hei 10-180618 to roughen the surface appropriately.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planarization technology of a wafer surface pattern by polishing, which is used in the fabrication of semiconductor integrated circuits. The present invention relates to a process for flattening high precision, high efficiency, and low cost without causing damage. It relates to a processing device.

1 is an explanatory diagram of a planarization process of a wafer surface;

2 illustrates a chemical mechanical polishing method;

3 is a view showing a plane and a cross section of a semiconductor memory device;

4 is a view for explaining a problem when processing using a soft polishing pad;

5 is a view for explaining the configuration of the grindstone used in the fixed abrasive grain processing method;

Fig. 6 is a view for explaining a conventional dressing method in the fixed abrasive grain processing method;

7 illustrates a dressing method of the present invention;

8 is a view showing the structure of a processing apparatus suitable for the practice of the present invention.

Such sharpening of the polishing tool is performed by applying a constant load to the dressing tool and pressing the rotating polishing tool. However, the sharpening performed by such a conventional technique has only been to roughen the surface of the polishing tool.

On the other hand, in order to increase the service life of the abrasive tool, it is necessary to thicken or harden the abrasive tool, but as the hardness of the abrasive tool is increased, there is a problem that cannot be considered in the prior art.

The present invention is to solve such a problem, and has the following constitution.

The present invention provides a polishing apparatus for applying a relative movement between a workpiece and an abrasive tool to polish the surface of the workpiece on the abrasive surface of the abrasive tool, the dressing tool for forming a rough surface on the abrasive surface of the abrasive tool; First moving means for giving a relative movement between the dressing tool and the polishing tool, and a second movement for moving the dressing tool in a direction perpendicular to the polishing surface of the polishing tool to determine a position at a desired position. Means and a control means for performing the movement by the first moving means while controlling the position of the second moving means to provide a polishing apparatus.

In addition, the subject, effect | action, and effect of this invention are explained in full detail in the column of the form for implementing an later invention.

Embodiments of the present invention will be described below with reference to the drawings.

Although the semiconductor manufacturing process consists of many process processing steps, first, the wiring process which is an example of the process to which this invention is applied is demonstrated using FIG.

1A shows a cross-sectional view of the wafer on which the wirings of the first layer are formed. An insulating film 2 is formed on the surface of the wafer substrate 1 on which the transistor portion is formed, and a wiring layer 3 such as aluminum is provided thereon. Since holes are formed in the insulating film 2 for the purpose of bonding the transistors, the portion 3 'of the wiring layer is somewhat concave.

In the wiring process of the second layer shown in FIG. 1 (b), the insulating photoresist 4 and the metal aluminum layer 5 are formed on the first layer, and the exposure photoresist layer 6 is formed again in order to wire pattern the aluminum layer. Attach.

Next, as illustrated in FIG. 1C, the circuit pattern is exposed and transferred onto the photoresist 6 using the stepper 7. In this case, if the surface of the photoresist layer 6 is uneven, as shown in the drawing, the concave portion and the convex portion 8 on the surface of the photoresist become out of focus at the same time, which is a serious obstacle of poor resolution.

In order to solve such a disadvantage, the planarization treatment of the substrate surface as described below is performed. After forming the insulating layer 4 after the processing process of FIG. 1 (a), as shown in FIG. 1 (d), FIG. Obtain the state of (e). Thereafter, the metal aluminum layer 5 and the photoresist layer 6 are formed and exposed with a stepper as shown in Fig. 1 (f). In this state, since the resist surface is flat, the problem of resolution defects does not occur.

An outline of a fixed abrasive grain polishing apparatus suitable for the employment of the abrasive machining of the present invention will be described below in comparison with a chemical mechanical polishing apparatus generally used in the related art.

(1) Outline of chemical mechanical polishing device

The surface leveling device of the surface of a semiconductor device as disclosed in Japanese Patent Laid-Open No. 10-180618 is called a chemical mechanical polishing (CMP) device. As described above, the apparatus presses a polishing pad held on a rotating member to a semiconductor device held on a rotating sample object and simultaneously distributes a liquid containing polishing slurry between the polishing pad and the sample, thereby polishing the surface of the semiconductor device. To flatten the surface of a semiconductor device.

2 is a diagram showing the principle of polishing a semiconductor device of a CMP apparatus. First, the polishing pad 11 is attached to the surface plate 12 and rotated. The polishing pad is formed by slicing a foamed urethane resin or the like into a thin sheet shape. The polishing pad is divided into various materials and fine surface structures depending on the type of workpiece and the degree of surface roughness to be finished.

The wafer (semiconductor device) 1 to be processed is fixed to the wafer holder 14 via an elastic pressing pad 13. The wafer holder 14 is rotated and loaded onto the surface of the polishing pad 11, and the polishing slurry 15 is again supplied on the polishing pad 11, thereby polishing and removing the convex portions of the insulating film 4 on the wafer surface. .

As described above, CMP is widely known as a glass polishing particle polishing technique by processing while supplying polishing slurry between the polishing pad and the workpiece, but has three major problems.

The first problem is a pattern dimension dependency problem in that it cannot be sufficiently flattened depending on the type of the pattern and the state of the step. In general, a pattern on a semiconductor wafer is formed from a pattern having various dimensions and steps.

For example, in the case of using a semiconductor memory device as an example, as shown in Fig. 3A, one chip is divided into four blocks. Among the four blocks, minute memory cells ll are formed in a precise and precise manner, and are referred to as memory mat portions 16.

Peripheral circuits 17 for accessing the memory cells ll are formed at the boundary of the four memory mat portions. In a typical dynamic memory, one chip dimension is about 7 mm x 20 mm, and the width of the peripheral circuit portion is about 1 mm. When the cross section A-A 'of the chip is taken, as shown in Fig. 3B, the average height of the memory mat portion 16 is about 0.5 to 1 mu m higher than the average height of the peripheral circuit portion 17. Figs. When the insulating film 4 having a thickness of about 1 to 2 mu m is formed on such a step pattern, the cross-sectional shape 31 of the surface portion also reflects the step shape of the underlying pattern.

In the semiconductor wafer planarization step, the insulating film 4 on the wafer surface is planarized like a dashed line 32, but a soft polishing pad 1LL made of expanded polyurethane resin, which is generally used for this purpose, is used. In the case of use, since pattern dependency exists in polishing rate, it is not flattened like this. That is, as shown in Fig. 4, when a soft polishing pad 1LL is used, the polishing pad surface shape deforms like the solid line 30 in the drawing due to the polishing load. Since the load is concentrated in the micropattern having a dimension of µm, the flattening is performed in a short time because the load is concentrated, but the polishing speed is slowed because a pattern is applied as a distributed load to a pattern having a large dimension of several mm. As a result, the cross-sectional shape after polishing becomes like the broken line 34 in Fig. 4, and the height difference d still remains.

The use of semiconductor wiring process requires unevenness of ± 5% or less, and the limit of the hardness of the present condition and the polishing pad has a Young's modulus of about 10 kg / mm ² as the upper limit.

For this reason, in semiconductor devices in which various patterns of small and large orders ranging from several mm orders to micrometer orders, such as memory devices, are not expected to have sufficient planarization effects, a semiconductor product which does not include a pattern having too large dimensions as an applicable object, for example, For example, it is limited to logical LSI.

The second problem in the glass polishing particle type planarization technology is high running cost. This is due to the low utilization efficiency of the polishing slurry in the glass polishing particle polishing method. In other words, in order to perform ultra smooth polishing without abrasion damage (scratch), it is necessary to supply abrasive slurries such as colloidal silica at a rate of several hundred cc / min or more, but most of them are excluded without contributing to actual processing.

The price of high-purity slurry for semiconductors is very expensive, and the improvement of the polishing slurry is strongly required because the use amount of the polishing slurry determines most of the cost of the planar polishing process.

The short life of the polishing pad, which is the third subject, is also caused by the dressing operation on the surface of the polishing pad. In the present state, it is necessary to replace the polishing pad every 500 wafers.

(2) Outline of Fixed Grinding Particle Polishing Machine

As a solution to the above problems of glass abrasive grain polishing, there is a polishing method by fixed abrasive grain polishing employed in the apparatus of the present invention.

In the polishing apparatus shown in Fig. 2, in the polishing apparatus shown in Fig. 2, instead of the conventional polishing pad, a special grinding wheel 20 whose hardness is most appropriately controlled is used.

Specifically, the elastic modulus of the grindstone 20 is 5 to 500 kg / mm ^{2, which} is 1/10 to 1/100 of the hardness of the conventional grindstone used in other fields. Compared with the hardness of hard polishing pads such as hard foamed polyurethane, there is a hardness of 5 to 50 times.

The structure of the grindstone used by the said technique in FIG. 5 is shown. As the kind of the abrasive grains 21, silicon dioxide, cerium oxide, aluminum oxide and the like are preferable, and particles having a particle diameter of about 0.1 to 1 탆 can obtain good processing efficiency without causing scratches.

As the resin 22 for bonding these abrasive particles, a high purity organic resin such as phenol or polyester is preferred. The abrasive grains are kneaded to the bonding resin, and then solidified by applying an appropriate pressure, followed by treatment such as heat curing if necessary. And can control the hardness of the grinding wheel to be completed by the type and size of the biasing force of the binder resin in the above manufacturing method, and in the present technique so that it 5~5OOkg / mm ^2.

Pure water is supplied as a polishing liquid to a grindstone prepared by bonding cerium oxide abrasive particles having a particle diameter of 1 μm to a modulus of elasticity of 100 kg / mm ² using pure water as a polishing liquid, and a silicon dioxide film having a thickness of 1 μm is used. In the case of processing, no scratches are generated, and very good flattening performance is obtained at a processing speed of 0.3 ± 0.1 탆 / min or less for all kinds of patterns having a pattern width of 10 mm to 0.5 탆.

The combination of the scratch-free processing and the good flattening performance is an effect that can be achieved only by the fixed abrasive grain processing using the grinding wheel with optimized elastic modulus.

In the case of glass abrasive grain processing, about 500 wafers were used for the life of the polishing pad. In the above technique, the grindstone thickness can be several cm, so that the grindstone life can be extended to about 15,000 wafer processing.

This means that the replacement frequency of the polishing pad can be reduced to 1/30 "every day to every month", which is a great advantage in mass production sites.

The flattening method using the grinding wheel as an abrasive tool has a number of advantages, but it can be seen that a new problem occurs due to the fixed abrasive grain processing.

The 1st problem is the problem of maintaining the processing efficiency of a grindstone surface. In the planarization technique using the above-mentioned grindstone, similarly to the planarization polishing by glass abrasive grains, dressing (sharpening) of the grindstone surface is sometimes necessary because the grindstone surface is glazed by polishing of the wafer. In this dressing method, scraping by static pressure load is conventionally used.

Specifically, as shown in FIG. 6, the conditioning ring 42 in which the diamond particles 41 of # 80 to # 400 are embedded is placed on the surface of the grindstone 20 at an average surface pressure of about 100 to 300 g / cm ² . It slides at a relative speed of about 5 to 30 cm / s while being loaded. As a result, the blade tip of the diamond particles 41 can be scraped without leaving the whetstone surface, so that the whetstone surface can be sharpened.

However, when the surface of the grindstone is dressed like a CMP polishing pad, sharp cracks 43 reaching a depth of several tens of micrometers are generated on the surface of the grindstone, and this cracked end becomes a trigger (pulling), and the grindstone end during the polishing process. It can be seen that this leads to the destruction of and finally leads to the large scratch generation of the order of µm. It is assumed that the above-described cracking is caused by the size of the diamond grains 41 being large from # 80 to # 400, that is, the particle diameter: 300 µm to 60 µm. This problem is also a problem due to the high hardness of the grinding wheel 20 for wafer polishing.

Therefore, this problem can be solved by reducing the diameter of the diamond particles, but in this case, the diamond particles 41 are difficult to stick to the base ring 42, and the diamond particles are detached during the dressing operation and embedded in the whetstone surface. It causes more serious problems that cause scratches.

The phenomenon of cracking on the surface of the polishing tool is a peculiar phenomenon that occurs only when dressing the grindstone whose mechanical properties are adjusted for semiconductor leveling purposes, and does not occur when dressing the polishing pad composed of a soft polyurethane material. .

The second problem is the problem of flatness deterioration of the grindstone surface. Conventional dressing method is based on the processing principle of scratching the diamond particles while pushing them to the surface of the grindstone with a constant load. It is aimed.

Therefore, as shown in FIG. 6, the static pressure load by an air cylinder etc. is generally applied to the conditioning ring 42 via the gimbal point 44. As shown in FIG. Therefore, if the hardness distribution of the grindstone is uneven or the rotation of the conditioning ring is out of the set value, the dressing quantity distribution in the grindstone radial direction becomes uneven, so that the grindstone of the initial thickness of 20 mm may be dressed to a thickness of about 10 mm. By that time, the shape of the grindstone surface becomes a shallow bowl shape in the order of several tens of micrometers, or the reverse Mt. As such, when the flatness of the whetstone surface becomes poor, processing irregularities occur on the wafer surface to be processed, which is a serious defect.

In order to obtain 5% processing uniformity by planarization by fixed abrasive grain processing, it is necessary to have a level of several micrometers as the flatness of the grindstone.

The problem of the flatness of the grindstone arises even when the new grindstone is used. In other words, in the case of large grindstones with a diameter of 70 cm or more and a thickness of several cm, it is very difficult to produce the flatness of the polished surface at the level of several micrometers and to mount it on the polishing apparatus. It was impossible to correct by the static dressing method. In addition, due to the convenience of manufacturing and mounting large grindstones, when the grindstone is divided into a plurality of segments and mounted, a step between segments of several tens of micrometers is unavoidable, which is also a big problem.

The problem of the flatness of the surface of the polishing tool as described above is a unique problem when using a grindstone of several centimeters in thickness, and the general polishing of the pad material has a modulus of elasticity of less than 10 kg / mm ² and a thickness of about 1 mm. It was almost negligible in the particle co-polishing pad.

In addition, even when flatness is a problem, for example, it was possible to sufficiently cope with simple correction control such as increasing the time for dressing the convex portion of the polishing pad surface or increasing the load.

As described so far, in the wafer planarization process by fixed abrasive grain processing, the constant pressure dressing method used in the conventional planarization process by glass abrasive grain processing generates many problems, and the problem solving is strongly required.

(3) Outline of Example Device of the Present Invention

An embodiment device of the present invention is to solve the problems specific to the device for polishing the surface of a semiconductor device by a hard polishing tool as used in the above fixed abrasive grain processing. It demonstrates using drawing below.

The specific example for implementing this invention in FIG. 7 is shown. In the figure, the wafer holder for the wafer (workpiece) to be polished is omitted.

50mm diameter cup-shaped dressing tool 101 with diamond particle 4l of # l00 fixed to blade tip is driven by spindle motor 102 and rotates at high speed of about 10000rpm and rotates at speed of about 10rpm The polishing surface of the grindstone 20 (polishing tool) is dressed. By the high-speed rotation, the circumferential speed of the dressing tool 10l reaches about 20 m / s, thereby dressing the whetstone surface with a sufficiently small roughness.

The cutting amount of the dressing tool 101 in this case is a micrometer order, and is typically 1 micrometer. The spindle motor 102 is provided on the Z moving table 103, is driven by the Z drive system 104 (second moving means), moves in the Z axis direction in the drawing, and can be positioned at any position. In addition, since the Z moving table 103 restricts the movement in the X axis direction on the X moving table 105 which is moved in the X axis direction by the X drive system 106, the dressing tool 101 is moved by the movement of the X moving table. The linear movement is performed in the grindstone radius direction while maintaining the cutting amount (the position in the Z-axis direction of the dressing tool).

In addition, the rotating means for rotating the spindle motor 102, the X moving table 105, or the grinding wheel for grinding the wafer applies a relative motion between the dressing tool 101 and the grinding wheel 20, to the first moving means of the present invention. It is equivalent. The motion error of the axis orthogonal to the moving axis of these moving means needs to be small enough compared with the cutting amount.

In this way, the upper surface of the grindstone 20 is ground in an accurate plane by grinding the sample surface while maintaining the position in the Z-axis direction of the dressing tool 101 (hereinafter referred to as constant dimension dressing). In this case, the cutting amount of the dressing tool 101 is determined by the positioning coordinates of the Z moving table 103 and is given by the instruction of the control system 107.

In addition, although the embodiment of the present invention employs a moving system for moving the dressing tool 101 in the Z direction, the grinding wheel 20 for wafer polishing may be moved in the Z direction, so that a constant cutting amount is maintained. Do it. Also, the grinding wheel 20 for wafer polishing may be moved with respect to the movement in the X direction.

The diamond particles 41 placed and fixed on the machining surface of the dressing tool 101 are stuck to the wafer grinding wheel 20 when the cutting amount is set by the Z drive system 104. When the dressing tool 101 rotates in this state, the diamond particles 41 grind the surface of the grinding wheel 20 for wafer polishing while maintaining the position in the Z direction.

Surface processing of the grinding wheel for wafer polishing which consists of the said structure is performed as follows. First, if the start instruction of the dressing operation is given prior to wafer polishing, the grinding wheel 20 starts to rotate, and at the same time, the control device 107 cuts in the Z drive system until the dressing tool 101 contacts the surface of the grindstone. Give directions to move to. In addition, any element (not shown) which detects this contact state may be anything, such as a contact sensor or a non-contact sensor, such as an optical type, and it is preferable that the spindle motor 102 rotates.

When the contact of both is confirmed, the control device 107 gives a cutting instruction of 1 占 퐉 and instructs the X-axis drive system 106 to continuously move at a speed of about 10 mm / s. The X moving table 105 reciprocates the distance of the radius of the grindstone 20 so that the dressing tool 101 softly removes the entire surface of the grindstone by 1 μm. As a result, the surface of the grindstone is dressing, but the reciprocating frequency, the moving speed, the cutting amount, and the rotational speed of the grindstone 20 of the X moving table are set to optimum conditions according to the type of the grindstone. It is preferable to supply pure water as the processing liquid for grinding during this dressing operation, and to remove the waste liquid and the cutting powder remaining on the grindstone surface by vacuum suction.

Setting of the reciprocating frequency is such that the cutting allowable depth (even the tip of the diamond grains 4l) can be pierced on the surface of the grinding wheel 20 for wafer grinding, which can pierce the diamond grain 41 on the grinding wheel 20 for wafer polishing. It is desirable to make a decision based on the limit depth, which is not available. For example, when the allowable depth of cutting is 0.5 mu m, when the grinding wheel surface is to be deleted by 1 mu m, the order requires movement by the X moving table 105 at least twice (one round trip).

In order to obtain such a large cutting amount, the position control by the Z drive system 104 may be performed step by step. For example, when cutting 2 micrometers, cutting 0.5 micrometer may be repeated 4 times. These dressing operations may be performed before processing of the workpiece, or may be performed during processing in parallel with the processing. In particular, when dressing in stages as described above, the processing of the device is not impaired when performed in parallel with processing.

In addition, the case where the surface of the grinding wheel 20 is planarly processed by performing X movement to the dressing tool while the positioning coordinates of the Z moving table 103 are fixed is described, but the X coordinate of the X movement has been described. Correspondingly, by numerically controlling the positioning coordinates of the Z moving table 103, the surface of the grinding wheel 20 can be formed into a curved surface other than a plane.

In the practice of the present invention, the selection of the diamond particles 41 of the dressing tool is very important, and it is not desirable to be too small or too large. In other words, the dressing tool including a large number of diamond particles having a small particle diameter has good efficiency because of the large number of cutting edges, but the diamond particles are easily released due to the grinding force and are likely to cause fatal scratches. On the contrary, the dressing tool containing a small number of diamond particles having a large particle diameter does not have to worry about detachment of the diamond particles. However, since the number of cutting edges is small, the efficiency decreases unless the rotation speed of the tool is increased.

In the case where the tip of the diamond particles is pointed in a point shape, or when the tip is in the shape of a flat blade, high efficiency can be obtained even if the number of diamond particles is small. Such a tool blade having a flat blade tip has a diamond bite or a superhard bite used for mirror turning, and a dressing tool of such a type that rotates a removable small bite of this type at high speed. Embodiments of the present invention yield good results.

According to the constant value dressing of the device of the embodiment of the present invention, the sharpening of the grinding wheel surface and the flattening of the grinding wheel surface can be realized simultaneously, and the hardness is high without causing cracks in the wafer grinding wheel by setting the appropriate cutting amount. Sharpening and flattening of the whetstone can be realized.

In addition, the reason why it is possible to suppress the occurrence of cracks in the grinding wheel 20 for wafer polishing in the embodiment device of the present invention is that the dressing tool 101 in which the diamond particles 41 are formed on the machined surface of the embodiment device of the present invention has a cutting amount ( It is because grinding | polishing is performed so that the circumference | surface (surface of the wafer grinding wheel 20 for grinding) may be scraped off with the depth deeply maintained. That is, by setting the appropriate cutting amount, the scrape breaking force with respect to the wafer grinding wheel 20 can be suppressed to a certain value even for microstructural changes in the grindstone resulting from the presence of pores and the like.

On the other hand, in the case of applying the conventional static pressure polishing method, the dressing tool is pressed on a wafer grinding wheel at a certain pressure on the average.However, in the case of microscopic view, the cutting depth is discontinuous due to the presence of pores. In some cases, cracks could be generated immediately beyond the allowable cutting depth.

As described in detail above, in the embodiment apparatus of the present invention, the above-mentioned problem is solved by fixing the relative positions of the grinding wheel and the grinding tool in the Z-direction even when a grinding wheel having a high hardness is used. It becomes possible to solve.

In addition, according to the constant-size dressing of the present invention, the surface of the grinding wheel for grinding the wafer can be flattened with higher accuracy compared with the conventional polishing by the static pressure load.

In the polishing by the static load, there is a problem that the smooth wrinkles on the surface of the grinding wheel can not be removed even if the fine wrinkles on the surface of the grinding wheel are removed. This is because the dressing tool moves as described above only the gentle wrinkles of the grinding wheel for grinding the wafer. In particular, in an apparatus in which the size of the wafer grinding wheel 20 as shown in FIG. 7 is much larger than that of the dressing tool 101, for example, a convex portion having a wide feather from the end to the end of the grinding wheel 20 for wafer grinding (or The occurrence of concave portions may also be considered, and the damage may become more remarkable.

On the other hand, in the case of the constant-size dressing of the present invention, the wafer polishing grindstone surface can be ground without being influenced by the irregularities of the wafer polishing grindstone surface, so that it is possible to flatten the wafer polishing grindstone with precision.

In addition, dimensional dressings should be used to ensure that excessive pressure is not applied to the grinding wheel for grinding the wafer. In other words, care should be taken not to press the dressing tool with excessive pressure due to excessive depth setting.

The control of the Z drive system by the element for detecting the contact state between the dressing tool and the wafer grinding wheel as described above is to prevent excessive pressure from being applied to the wafer grinding wheel. In addition, a means for detecting the pressing force of the dressing tool (not shown) is provided, and when a certain pressing pressure is detected, the dressing tool is once removed from the wafer grinding wheel to generate an error or to reset the appropriate cutting amount and polish again. Means for doing this may be provided.

Another operation is a method of dressing simultaneously with the polishing of the wafer. In this operation method, there is a mode in which the above operation is performed only once in one wafer processing, and the dressing is performed continuously while the cutting amount is continuously increased during processing. The latter mode is preferable for the low speed dress depending on the type of grindstone. Do.

In the above embodiment, the condition where the dress the grinding wheel to the cerium oxide as abrasive grains, the conventional method to be nil, and that generates a three-level of cracks per lOcm ² scratching was not.

In addition, the flatness of the grindstone was maintained at a flatness of 5 µm over the grindstone surface, and this value did not deteriorate even after dressing about 5000 dressings, i.e., until the grindstone thickness decreased by 10 mm.

It is also conceivable to use a combination of polishing by a constant pressure load, which has been conventionally used, and a constant dressing in one apparatus. In this case, the polishing by the static pressure load or the polishing by the dimensional dressing may be selected depending on whether the grinding wheel for polishing the wafer or the polishing pad used in the conventional CMP apparatus is used.

For example, in the apparatus of FIG. 7, the operator at the time of replacing the grinding wheel (or polishing pad) for wafer polishing, inputs whether to use the grinding wheel or polishing pad by an input device not shown in FIG. The device may be set to automatically select either polishing by static pressure load or dimensional dressing.

In addition, even with a polishing pad used in the conventional CMP, a certain size dressing may be appropriate depending on the hardness thereof. Therefore, either the polishing by the static pressure load or the constant size dressing is automatically applied depending on the type of the polishing tool. It is also conceivable to set the device to be selected.

This arrangement makes it possible for the operator to easily set the appropriate polishing conditions without knowing the principle of polishing by the static pressure load or the constant size dressing.

Next, the specific structural example of the processing apparatus suitable for implementing this invention is demonstrated using FIG. Basically, it is a two-platen, two-head polishing apparatus, and is characterized by using a grindstone as an abrasive tool and applying the present invention for optimally dressing the grindstone.

The first grinding wheel 51 is bonded to the upper surface of the grinding wheel optimized for high elastic modulus, and the second grinding wheel 52 is bonded to the upper surface of the grinding wheel having a small elastic modulus for finishing. These grinding wheels polish wafers while rotating at a constant speed of about 20 rpm, respectively.

Dressing of the first grinding wheel 51 is performed before processing. The spindle motor 102 provided at the tip of the rotary swing arm 108 rotates the small diameter dressing tool 101 at a high speed of 10000 rpm to dress the surface of the grinding wheel 51 rotating at 20 rpm. The setting of the cutting amount is made by the Z moving device 103 of the rotary rocking arm base, and is typically cut by 1 mu m. The rocking cycle of the arm is approximately 30 seconds, and when it is finished, it is ready for wafer polishing.

In the above embodiment, the arm rotation oscillation type is used. However, this may be a linear movement type as shown in FIG. The above embodiment is an example of dressing before flattening and polishing, but it may be performed in parallel during the processing as described above.

After the dressing is finished, the wafer is finally polished. The wafer to be processed 55 is withdrawn from the loader cassette 53 by the handling robot 54 and placed on the load ring 57 of the linear carrier 56. Next, when the linear carrier 56 is moved to the left in the drawing and positioned at the load / unload position, the polishing arm A58 is rotated to move and the lower surface of the wafer polishing holder 59 provided at its tip. The wafer to be processed 55 is vacuum-adsorbed. Then, the polishing arm A58 is rotated such that the wafer polishing holder 59 is positioned on the first grinding wheel 51. The wafer polishing holder 59 is pressed while being rotated by pressing the processing wafer 55 adsorbed on the lower surface on a grindstone. After the first machining step is finished, the polishing arm A58 is rotated so that the wafer polishing holder 59 is positioned on the second grinding wheel 52. Thereafter, the wafer polishing holder 59 is rotated while pressing the work wafer 55 adsorbed on the lower surface on the second grindstone plate 52 to finish the work.

Then, when the said two steps process is complete | finished, it enters a washing | cleaning process next. The polishing arm A58 rotates, and this time, the wafer polishing holder 59 is positioned on the cleaning position in which the rotating brush 60 is provided.

The rotary brush 60 rotates and washes the processed surface of the to-be-processed wafer 55 adsorbed to the lower surface of the wafer polishing holder 59 with a hand brush. When the cleaning is finished, the linear carrier 56 moves again to the cleaning position, and receives the processed wafer opened from vacuum suction of the wafer polishing holder 59. In addition, although a rotating brush is used here, the washing | cleaning method by the jet stream which provided the ultrasonic wave can also be used instead. After that, when the linear carrier 56 returns to the load / unload position, the wafer handling robot 54 grasps the processed wafer and stores it in the unload cassette 6l.

The above is the operation for one cycle of the polishing arm A58. Similarly, the grinding arm B62 operates in parallel with this. Naturally, this is for time-sharing the two polishing plates efficiently. The operation sequence of the polishing arm B62 is exactly the same as that of the polishing arm A58, but the phase is delayed by a half cycle. In other words, the polishing arm B62 starts operation in accordance with the start of the second polishing step.

The above embodiment is a configuration example in which the number of polishing arms is two, and the dressing device has only one system. A set of cleaning brush or rod / By providing the stop position of the linear carrier for unloading, the two grinding arms can be used to combine these functions.

In the above embodiment, only the first polishing table is to be dressed, but if necessary, the second polishing table may be dressed by changing the rotational center position of the dressing device, or a second dressing device may be provided separately.

The embodiment in which two abrasive arms are provided so far has been described. However, in order to simplify the configuration, it is natural or one may be used. On the contrary, in order to improve the throughput of the apparatus, the number of polishing arms may be three or more, or a plurality of wafer polishing holders may be provided in one polishing arm.

Further, in the above embodiment, two rotary tables are provided respectively for the polishing pad and the grindstone, but it is also possible to use this as one rotary table. In other words, a ring-shaped grindstone is installed at the periphery of the rotating table and a finishing grindstone is installed at the center of the rotary table.

The abrasive grindstone or polishing pad mounted on these polishing plates is not necessarily limited to an integral disk shape but may be a combination of a plurality of segment shapes. In addition, in order to reduce the footprint (projection area for installation) of the apparatus, it is also possible to have a design in which the rotating table is inclined.

In addition, the embodiment device of the present invention can be applied to the manufacture of optical devices having fine surface structures such as liquid crystal display devices, micromachines, magnetic disk substrates, optical disk substrates, and Fresnel lenses, as well as semiconductor devices.

When the semiconductor wafer is flattened by a fixed abrasive grain processing method using a grindstone as a grinding tool, the grinding of the grindstone surface is prevented from happening because the dressing of the grindstone is done by a constant size dressing method that cuts the micrometer order. Can be.

In this case, since constant dimension cutting is performed, the flatness of the grindstone surface is always guaranteed, and polishing can be performed without occurrence of nonuniformity at all times. As a result, the thickness of the grindstone can be several cm or more, and the grindstone life can be profoundly extended.

In addition, by continuously applying the dress to the whetstone of the present invention during wafer processing, loading during processing can be prevented and the overhead time required for dressing can be eliminated. Can improve.

In addition, the description of the embodiment of the present invention mainly described an example of using a grindstone by a fixed abrasive grain polishing method, even if it is applied to a polishing pad used in the conventional CMP apparatus, it is easy to obtain almost the same effect easily I can imagine it. In this case, the effect of the present invention can be maximally enjoyed by using a polishing pad having a large elastic modulus (hard) more than conventionally.

In addition, in the embodiment apparatus of the present invention, since the polishing tool can be planarized and the blade can be raised simultaneously, the throughput of the apparatus can be improved.

In addition, although the embodiments of the present invention have been described so far, the present invention can be applied to planarization of substrates such as thin film devices, glass, ceramics, and the like.

In addition, in the present invention, by carrying out the constant size dress in parallel with the processing of the wafer, the throughput of the device can be improved while maintaining the processing rate.

According to the present invention, even in a fixed abrasive grain processing method using whetstone, cracking can be prevented and the surface of the whetstone can be sharpened, so that flattening processing without scratching can be performed. In addition, in the present invention, since a fixed dimension is cut, the flatness of the grindstone surface can be assured, and the machining with little in-plane unevenness can always be performed. As a result, it is possible to use a thickness of several centimeters and a thick grindstone, which can significantly lengthen the life of the grindstone.

In addition, in the present invention, the constant size dress is performed in parallel with the processing of the wafer, and the throughput of the device can be improved while maintaining the processing rate.

Claims (11)

A polishing apparatus for polishing a surface of a layer on a polishing surface of the polishing tool by giving a relative movement between a layer having irregularities formed on a semiconductor wafer and the polishing tool, A dressing tool for dressing by forming a surface roughness on the polishing surface of the polishing tool; First moving means for providing a relative movement in a horizontal direction with respect to the polishing surface of the polishing tool between the dressing tool and the polishing tool; Second moving means for moving the dressing tool in a direction perpendicular to the polishing surface of the polishing tool; And control means for executing the movement by the first moving means while maintaining the position of the second moving means, A polishing apparatus, characterized in that the elastic modulus of the polishing tool is 5 to 500 kg / mm 2. The method of claim 1, And the abrasive tool is composed of abrasive particles and a material for bonding and retaining the abrasive particles. The method of claim 1, And the dressing tool comprises a plurality of hard particles. The method of claim 3, The hard particle body is a polishing apparatus, characterized in that the diamond. The method of claim 1, The control means includes detection means for detecting a contact between the polishing tool and the dressing tool, and controls to stop the second moving means based on the detection of contact between the polishing tool and the dressing tool by the detection means. Polishing apparatus, characterized in that. The method of claim 1, And the first moving means moves the dressing tool, the polishing tool, or both so that the dressing tool moves on the polishing tool. The method of claim 1, And said control means comprises setting means for setting a cutting amount of said dressing tool for said polishing tool, and said second moving means moves in accordance with a setting value of said setting means. The method of claim 7, wherein And said control means realizes the cutting amount set by said setting means by moving said second moving means a plurality of times. The method of claim 8, And the setting amount of the cutting amount by the setting means is set smaller than the depth at which the hard particles included in the dressing tool can be pierced by the polishing tool. A polishing apparatus for polishing a surface of a layer on a polishing surface of the polishing tool by giving a relative movement between a layer having irregularities formed on a semiconductor wafer and the polishing tool, A dressing tool for dressing by forming a surface roughness on the polishing surface of the polishing tool; Means for performing the positional control of the dressing tool in a direction perpendicular to the polishing surface of the polishing tool so as to form a surface roughness on the polishing surface, A polishing apparatus, characterized in that the elastic modulus of the polishing tool is 5 to 500 kg / mm 2. In the method of manufacturing a semiconductor in which the thin film surface adhered on the surface of the semiconductor substrate on which the uneven pattern is formed is pressed while being subjected to relative movement by pressing the polishing surface of the polishing tool. The surface roughness is formed by a dressing tool for forming a surface roughness on the polishing surface of the polishing tool having an elastic modulus of 5 to 500 kg / mm 2 during or during the polishing process. A method of manufacturing a semiconductor, characterized by performing a relative movement in a horizontal direction with respect to the polishing surface while maintaining the position of the movement of the dressing tool in the vertical direction.