JPH11277415A - Semiconductor wafer mount-plate and semiconductor wafer polishing method using mount-plate and management device thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor wafer mount-plate and semiconductor wafer polishing method using the mount-plate and management device thereof which eliminate the need for reparing of the mount-plates to efficiently polish the semiconductor wafers by preventing the deformation of the mount-plates due to the changes with age. SOLUTION: Both a front face 11 and a rear face 12 of a mount-plate 1 precisely flattened. The mount-plate 1 is inverted for each batch of polishing. In relation to the mount-plate 1 fro which semiconductor wafers 10 are peeled off and which is cleaned, identification data and the surfaces in use are recognized, and the amount of deformation of the surfaces and the state of the frequencies of application, are sensed. When the deformation is not more than a specified value, the mount-plate is sent again to the process of mounting. When the deformation is more than the specified value, the mount-plate l is replaced with new one.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor wafer affixing plate constituting a semiconductor wafer polishing apparatus, a polishing method capable of stably producing a semiconductor wafer having a high flatness by using the same, and a polishing method. The present invention relates to a device for managing a plate for attaching a semiconductor wafer.

[0002]

2. Description of the Related Art In polishing a semiconductor wafer, it is necessary to attach a semiconductor wafer 10 to an attaching plate 8 as shown in FIG. 10 (a). Surface 81 "). The sticking plate itself is made of ceramics or the like, and has high rigidity and high flatness. However, when the number of times of use in the polishing process increases, FIG.
As shown in (b), the surface 81 is slightly deformed into a concave shape following the shape of the lower platen (not shown) of the polishing apparatus. Even if the attachment plate is deformed on a micron scale, the required flatness of the semiconductor wafer is extremely high, so the deformation of the attachment plate has a fatal effect on the stable production of high flatness wafers. Exert. . Conventionally, in order to recover the flatness of the attaching plate 8, FIG.
As shown in FIGS. 0 (b) and (c), measures have been taken to remove the peripheral portion 83 appropriately and reproduce it on the flat surface 81a.

In addition, as another prior art for polishing and polishing a wafer as flat as possible, for example, as disclosed in Japanese Patent Application Laid-Open No. 64-2857, a predetermined surface is uniformly applied to the surface of an attaching plate. The one that suppresses the deformation of the attaching plate by applying fluid pressure,
As disclosed in Japanese Patent Application Laid-Open No. 4-242929, a dummy wafer is once adhered to an attaching plate and polished to cause a certain deformation on the polishing cloth side, and the attaching plate is further created and polished on the deformed surface. There is also a complicated one in which a desired semiconductor wafer is attached again and polished after the shape is adjusted.

[0004]

However, in the conventional method of appropriately cutting the peripheral portion, it is inevitable that the deformation of the sticking plate is gradually emphasized as the number of times of use is increased, and eventually the limit cannot be corrected. Will reach. Of course, at the same time as the periphery of the attaching plate is
There is also a method of shaving the convex portion 82a of the back surface 82 shown in (c) and reproducing both surfaces with a high degree of flatness, but the time and cost required for the correction are twice as large as those required for the single-sided correction. It is difficult to adopt in terms of productivity and economy. The conventional reproduction frequency is about once or twice a half a year, but if the reproduction is more than four times, in most cases, it is necessary to discard.

[0005] In addition, the above-mentioned prior art in which a fluid pressure is applied requires the introduction of a new device, and the adjustment of the polishing cloth side by a dummy and the creation and polishing of the attaching plate are naturally produced. Sex will fall.

[0006] The present invention has been made in view of such a situation, and the time-dependent deformation of the attaching plate is corrected using the mechanical action in the polishing process of the semiconductor wafer as it is, thereby reducing the number of processes. The present invention provides a technique for eliminating the need for a creative polishing process for regenerating the pasting plate, which had conventionally only been performed independently of the polishing process, and for extending the life of the pasting plate itself.

[0007]

For this reason, in the present invention, both the front and back surfaces of the semiconductor wafer attaching plate constituting the polishing apparatus for semiconductor wafer are flattened with high precision.

When polishing the semiconductor wafer attached to the semiconductor wafer attaching plate, the attaching plate is turned upside down at least for each batch of the polishing process. The semiconductor wafers were alternately stuck and polished.

Further, the parallelism is used as an index for evaluating the flatness of the attaching plate, and a change in the wafer attaching surface of the attaching plate is determined based on the parallelism.

[0010] Further, a measuring instrument for automatically measuring the parallelism and an identifier for distinguishing the front and back surfaces of the semiconductor wafer bonding plate and an identifier for distinguishing each bonding plate between the semiconductor wafer polishing apparatuses are automatically generated. By discriminating, the number of times of use for each batch of the polishing step and the measured value of the parallelism at that time are recorded for each of the front and back surfaces of the individual attaching plates, and based on this, the use of each attaching plate is continued, A management device that automatically determines whether to stop and whether to change the wafer attachment surface is configured.

From this record, it is possible for the operator of the polishing apparatus to determine whether or not the sticking surface should be changed, and it is possible to eliminate the dispersion of the judgment between the operators by following the judgment of the management apparatus. Further, by providing a reversing and transferring mechanism of the attaching plate, the attaching plate can be automatically inverted and transferred to the attaching device according to the judgment result of the management device. This allows
The sticking surface changes automatically.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The accuracy of expressing the flatness of the above-mentioned semiconductor wafer sticking plate (hereinafter referred to as "sticking plate") is as follows.
It is desirable to do the following. When a semiconductor wafer is adhered to an attaching plate having a degree of parallelism higher than that and polished, the flatness of the semiconductor wafer deteriorates and the current high-precision standard cannot be satisfied.

Here, the degree of parallelism is defined in JIS B0620. A parallel plane is defined by a certain virtual plane.
This is the distance between the two planes when the plane is sandwiched between the planes.

Further, when an identifier for identifying the front and back surfaces is provided on the attaching plate, it is easy to grasp the difference in the state of deformation of the front and back surfaces over time.

In polishing the semiconductor wafer, the semiconductor wafer is bonded and polished alternately on both sides of the bonding plate at least for each batch of the polishing process. The force acts to cancel the deformation of the sticking plate. For this reason, no deformation is accumulated, and the change in parallelism is small even when used continuously for a long time. In addition, it is also possible to change the sticking surface every plural batches of the polishing process. Since the change in parallelism in one polishing step is very small, for example,
There is no practical problem with changing every 10 batches. Alternatively, there is a method of repeating an asymmetric cycle such as six times on the front surface and ten times on the back surface, depending on the state of deformation of the attaching plate.

In performing the above method, if an identifier for distinguishing between the front and back surfaces of the attaching plate and an identifier for identifying each attaching plate are provided on each attaching plate, the managing of the attaching plate is ensured. This has the advantage of being easier. In addition, it has an identification mechanism of these identifiers and a measurement mechanism of parallelism, and a measurement mechanism that automatically measures and records the parallelism of each surface of each attachment plate, and an individual attachment plate between polishing devices are distinguished. While recording the parallelism of the front and back surfaces of each of the pasting plates in the order of the number of times of use of the surface, the recorded data is compared with a predetermined value, and a command to change the pasting surface of the pasting plate is output. A management device having a comparison output mechanism can be provided. This makes it possible to easily grasp the accuracy of the pasting surfaces and changes with time for a large number of pasting plates, and to easily determine the change of the pasting surfaces and the continuation of use.

At the production scale, there are a plurality of polishing machines used, and individual sticking plates are used for these individual polishing machines without being specified. Each sticking plate is slightly different in properties and has a peculiar habit unique to the device, so that it does not always deform with the same tendency. For this reason, it is necessary to take detailed measures for each sticking plate. If a management device that integrally manages the change in the parallelism with respect to the number of times of use is prepared for each surface of each attaching plate, the above-described detailed correspondence can be further facilitated.

Hereinafter, the present invention will be described in further detail with reference to examples. Before adding a little explanation to the drawings, FIG. 1 is a side sectional view in which the shape of the attaching plate is emphasized, and FIG. FIG. 3 is a perspective view showing an example of an attaching plate provided with an identifier for distinguishing between the front and back surfaces, FIG. 3 is a flowchart showing an example of a method for polishing a semiconductor wafer according to the present invention, and FIGS. FIG. 6 is a diagram showing a measurement position for measuring the amount of deformation, FIG. 6 is a graph showing the amount of temporal deformation of the attaching plate in Example 2 described later, and FIG. 7 is a temporal deformation of the attaching plate in Example 3 described later. FIG. 8 is a schematic diagram illustrating a configuration of a sticking plate management device of Example 4 described later, and FIG. 9 is a schematic diagram illustrating an internal structure of a sticking plate mounting table.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail with reference to the drawings. Example 1 First, a sticking plate according to the present invention will be described.
10 (a), only the front surface 81 is processed to have a high flatness. However, the pasting plate 1 in the first embodiment shown in FIG. Both are processed to have a high flatness, and the precision is processed to a parallelism of 2.0 μm or less. Incidentally, in the case of the conventional attachment plate, the parallelism of the surface is described in 2.
Although it is 0 μm or less, that of the back surface is usually more than 10 μm.

In the first embodiment, the sticking surface was alternately changed for each batch of the polishing process using the sticking plate. As a result, the deformation is canceled for each batch, the progress of the deformation is much slower than in the past, and the number of batches until the parallelism of the attaching plate exceeds 2.0 μm is 1 in the conventional case.
It was 0 times or more. In the first embodiment, as shown in FIG. 2, identifiers 21 and 22 are provided on both the front and back surfaces of the attaching plate so that the front and back sides can be identified by the sensor and the subsequent recording can be performed. This is because the same flatness finish processing is performed on both the front and back surfaces of the attaching plate, and in the production process, there is a risk that management errors may occur only by storage and recording by the operator, so such an identifier is used. By providing them, the front and back surfaces can be reliably distinguished when the sticking surface is changed for each batch, so that the above-described offset effect can be more favorably exhibited.

Example 2 A polishing step 1 in which “sticking → polishing → peeling” shown in FIG. 3 is used as one cycle using the attaching plate according to the present invention.
Each time the batch is completed, the parallelism of the surface to which the wafer is attached is measured. Then, when this exceeds a predetermined value (± 2 μm in the present embodiment 2), the pasting surface is changed and the polishing step is performed. Thereafter, in the measurement of the parallelism for each batch of the polishing process, it is confirmed that the measured value gradually decreases as the number of used batches increases. If the same sticking surface is used as it is, the measured value starts to increase in the opposite direction beyond zero. When this exceeds 2 μm again, the sticking surface is changed. By doing so, the above-mentioned sticking plate is
It is possible to keep using it forever while correcting the deformation.

In the second embodiment, the parallelism is obtained by the following method. First, as shown in FIG. 5, four intersections A ₁ , D ₁ , A ₂ , D _2, and A ₁ -D _{1 of} two straight lines that pass through the center of the attaching plate 1 and the outer periphery of the attaching plate _1. Divide A, A ₂ -D ₂ into three equal parts 4
Eight points in total of the points B ₁ , C ₁ , B ₂ , and C ₂ are determined as measurement points. Next, as shown in FIG. 4, it is assumed that the pasting plate 1 is placed on a completely flat surface F, and from the reference plane S parallel to the flat surface F to the above-described respective measurement points on the pasting plate 1. Measure the distance. Measurement points A ₁ , B ₁ ,
From C ₁ and D ₁ , measured values a ₁ , b ₁ , c ₁ , and d ₁ are obtained as follows:
From the measurement points A ₂ , B ₂ , C ₂ , D ₂ , the measured value a ₂ ,
b ₂ , c ₂ and d ₂ are obtained. Using these values, the amounts of deformation P ₁ , P ₂ , Q ₁ , and Q ₂ are determined by the following formulas. Among them, P ₁ , P
_You are using ₂ . Incidentally, Q ₁ and Q ₂ will be described later.

[0023]

[Number 1] _{P 1 = {(a 1 +} d 1) - (b 1 + c 1)} ÷ 2

[0024]

P ₂ = {(a ₂ + d ₂ ) − (b ₂ + c ₂ )} 2

[0025]

Equation 3] _{Q 1 = {(a 1 +} b 1) - (c 1 + d 1)} +
{(A ₂ + b ₂ ) − (c ₂ + d ₂ )}

[0026]

Q ₂ = {(a ₁ + b ₁ ) − (a ₂ + b ₂ )} +
{(C ₁ + d ₁ ) − (c ₂ + d ₂ )}

[0027]

P = (P ₁ + P ₂ ) ÷ 2

As can be seen from the above equations, the deformation amounts P ₁ and P ₂ are on the A ₁ -D ₁ line and A ₂ -D ₂ , respectively.
Degree of deformation due to bending or wear on the line
For _1, the average value of the P ₂ P, deformation in the circumferential direction, a variation amount on the assumption that a uniform, which is a value representing the degree of parallelism. In the second embodiment, this value is described as parallelism. Q ₁ and Q ₂ are values representing the magnitude of wear and deformation that are uneven in the circumferential direction. This is due to the non-uniformity of the material of the attaching plate, and the increase in the value cannot be corrected by changing the attaching surface. Further, when the wafer is polished using the sticking plate that causes such uneven deformation, the flatness of the wafer is complicatedly affected. Therefore, when either Q ₁ or Q ₂ exceeds the allowable range, it is desirable to discard even if the P value is within the allowable range.

Example 3 In Example 1, a method was adopted in which the attaching surface of the attaching plate was changed for each batch. In Example 2, the sticking surface was changed when the measured value of the parallelism exceeded a predetermined value. In the third embodiment, the polishing surface is continuously used for each batch of the polishing process while changing the application surface, and the parallelism [P value] exceeds the specified value (1.0 μm) in the + (plus) direction shown in FIG. After that, the inversion was stopped, and it was adhered to only one side so that the parallelism became small (so that the deformation proceeded in the minus direction), and the use was continued. Eventually the specified value on the-(minus) side (-0.2 µm)
When the value exceeded, the change of the sticking surface for each batch was restarted. In this case, by selecting the specified value smaller than the allowable value of the parallelism, the parallelism can be maintained at a value sufficiently smaller than the allowable range forever. In addition, just by inserting the continuous use of only one side only for a short period in this way, it is possible to change the application surface for each batch in most of the use period. For this reason, the rate of change of the parallelism during the use period is small, and the production can be performed in a state where the flatness of the wafer is extremely stable. In the third embodiment, the specified value is
The values were 1.0 μm and −0.2 μm, in order to shorten the period of use by sticking to only one surface, and to reduce the parallelism (P due to the interaction with the polishing device).
Is slightly positive, because the flatness of the semiconductor wafer is better. Although FIG. 7 discloses only the parallelism (P value), Q ₁ and Q ₂ do not actually have much frequency dependency, and
It is within 1.0 μm. However, due to the non-uniformity of the material of the sticking plate, there are a small number of cases in which this is ± 1.0 μm or more. Such a sticking plate is discarded as a defective product for the reason described above.

Embodiment 4 In this embodiment 4, the parallelism of the attaching plate is measured in accordance with the above-described method for manufacturing a semiconductor wafer and connected to a wafer attaching apparatus, and the measured parallelism is set to a specified value. 7 shows a management device for a semiconductor wafer attachment plate that changes the wafer attachment surface of the attachment plate when the value is equal to or greater than a specified value.

As shown in FIG. 8, the management apparatus of the fourth embodiment includes a mounting table 3 on which the bonding plate 1a is mounted between the wafer mounting apparatus 7 and a bonding table mounted on the mounting table 3. An identification unit 52 as an identification mechanism for individually identifying the plate 1a and for distinguishing the front and back surfaces; a measurement unit 5 fixedly arranged above the mounting table 3 and being a measurement mechanism for measuring parallelism; Calculates the parallelism (P value) and the deformation amounts Q ₁ and Q ₂ from the values obtained from the above, compares them with the specified values, makes a determination to change the bonding surface of the wafer, and outputs the result of this determination. A computer (not shown) serving as a comparison output mechanism, and an inverting mechanism 6 that changes the sticking surface by detecting the output instructing the change of the sticking surface and inverting the sticking plate 1a. I have.

The upper surface of the mounting table 3 is used for measuring the amount of displacement.
It is formed on a flat surface as a reference, but when transporting the attaching plate 1a, as shown in FIG.
4 is moved up, and when the attaching plate 1a is arranged at a desired position, it is lowered and mounted on the mounting table 3.

Eight laser-type sensors 51 are fixed to the deformation amount measuring unit 5, and the distance between them is the same as in the second embodiment.
As shown in the figure, the diameter is one third of the diameter of the attaching plate 1a.

The reversing mechanism 6 is provided with a fork rotating table 61. The reversing mechanism 6 receives the attaching plate 1a conveyed from the loading table 3, and moves up and down to rotate, thereby inverting the attaching plate. In the wafer sticking apparatus, the sticking of the wafer is always performed from the upper side of the sticking plate, and thus, the sticking surface is automatically changed by this reversal.

The characteristics of the sticking plate used in the fourth embodiment will now be described. As shown in FIG. 9, the attaching plate 1a of the fourth embodiment is formed such that the diameter of the second surface 12a is larger than the diameter of the first surface 11a, and the side surface of the first surface 11a has a bar code 13a. Is provided. Therefore, the discrimination of the front and back surfaces is performed by the recognition unit 52 recognizing the step 14a due to the difference in diameter, and the discrimination unit 52 recognizes the barcode 13a, respectively.

The reason for providing the step 14a is that, in the case of a sticking plate intended for semi-permanent use, if the front and back surfaces are displayed by means such as a paint or a label, there is a possibility that the plate cannot be identified due to wear or deterioration during use. This is because such a problem can be avoided by using the difference due to the shape. Further, since there is a similar problem with the bar code, it is preferable to adopt a method of embedding and firing black ceramics and the like at the time of preparing the attaching plate.

With such a configuration, a large number of sticking plates in the semiconductor wafer polishing step were individually managed by the method of the third embodiment described above. As a result, while maintaining the parallelism of a large number of sticking plates used on a production scale within the specified value, the service life is more than 10 times longer than before,
You can continue to use. Also, the management for this can be automated by a computer.

[0038]

As described above, the present invention has the following excellent effects. (1) In the polishing process of the semiconductor wafer, the mechanical action during the process is used to correct the deformation of the sticking plate, so that it is necessary to provide a step of independently shaving off a part of the sticking plate as in the related art. As a result, the production efficiency is improved, and the number of service times of the attaching plate is significantly increased. For example, in the past, with a playback frequency of once or twice every six months,
Although the limit of performing the new polishing five to five times has been limited, according to the present invention, ten times or more of the life can be obtained. (2) As a result, the amount of the attaching plate used in the polishing step is significantly reduced. (3) Since the parallelism of the attaching plate is stable, the unevenness of the flatness between each polishing of the semiconductor wafer is reduced. (4) In the simplest embodiment, the present invention can be applied to a conventional device without adding a new device. (5) It is possible to easily further reduce the specified value of the parallelism and further improve the flatness of the semiconductor wafer attached and polished thereon. This is because, even if the specified value is reduced, the frequency of creation polishing is not increased as in the related art, so that the life of the attaching plate is not reduced and the production efficiency is not reduced.

[Brief description of the drawings]

FIG. 1 is a side cross-sectional view that emphasizes the shape of an attaching plate.

FIG. 2 is a perspective view showing an example of an attaching plate provided with an identifier for distinguishing front and back surfaces according to the present invention.

FIG. 3 is a flowchart illustrating an example of a method for polishing a semiconductor wafer according to the present invention.

FIG. 4 shows measurement positions for measuring the amount of deformation of the attaching plate.

FIG. 5 shows measurement positions for measuring the amount of deformation of the attachment plate.

FIG. 6 is a graph showing a temporal deformation amount of an attaching plate in Example 2.

FIG. 7 is a graph showing a temporal deformation amount of an attaching plate in Example 3.

FIG. 8 is a schematic diagram illustrating a configuration of a device for managing a sticking plate according to a fourth embodiment.

FIG. 9 is a schematic diagram showing an internal structure of the attaching plate mounting table.

FIG. 10 is a side cross-sectional view that emphasizes the shape of a conventional attaching plate and the deformation due to a change with time in diameter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 {attachment plate 11} front surface 12 {back surface 1a} attachment plate 11a {first surface 12a {second surface 13a} barcode 14a {step 21} identifier 22} identifier 3 {Mounting table 31} Lifting mechanism 34} Roller 4} Roller conveyor 5} Displacement sensing unit 51} Sensor 52} Identification unit 6} Reversing mechanism 61} Fork turntable 7} {Wafer sticking device 10} Semiconductor wafer

Claims (7)

[Claims] 1. A semiconductor wafer polishing plate for forming a semiconductor wafer polishing apparatus for bonding a semiconductor wafer to be polished to one side thereof, wherein both sides of the semiconductor wafer are highly precisely flattened. Plate for attaching semiconductor wafers. 2. The plate for attaching a semiconductor wafer according to claim 1, wherein the front and back surfaces are flattened with high precision to a parallelism of 2 μm or less. 3. The plate for attaching a semiconductor wafer according to claim 1, wherein an identifier for identifying the front and back surfaces is provided. 4. The semiconductor according to claim 1, wherein an identifier for distinguishing each semiconductor wafer attaching plate between the semiconductor wafer polishing apparatuses is provided. Wafer pasting plate. 5. A method for polishing a semiconductor wafer attached to a semiconductor wafer attaching plate, wherein the semiconductor wafer is attached and polished alternately on both sides of the semiconductor wafer attaching plate at least for each batch of the polishing process. Semiconductor wafer polishing method. 6. When polishing a semiconductor wafer attached to a semiconductor wafer attaching plate, the parallelism of either the front or back of the semiconductor wafer attaching plate is measured for each batch of the polishing process, and the parallelism is used as an index. A method for polishing a semiconductor wafer, comprising determining a surface to which a wafer is to be attached. 7. A discriminating mechanism for distinguishing front and back surfaces of a semiconductor wafer sticking plate, a measuring mechanism for measuring the parallelism of each surface, and a semiconductor wafer sticking plate between semiconductor wafer polishing apparatuses. The parallelism of each of the front and back surfaces is recorded in the order of the number of times of use of the surface, the recorded data is compared with a predetermined value, and a command for changing the attachment surface of the semiconductor wafer attachment plate is output. And a comparison output mechanism.