JP2009224472A - Etching device for semiconductor wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an etching device for semiconductor wafers, which has good efficiency of etching and is free from the risk of breakage of a semiconductor wafer in a surface direction. <P>SOLUTION: The semiconductor wafers 1 and 1 are disposed having non-etching surfaces 1b face to face, and have their peripheral edges held in a liquid-tight state by a holding device 10. Respective O-rings 11a, 12a, and 13a are brought into tight contact with one another by a vacuum pump 20. Consequently, when both the semiconductor wafers 1 are dipped in an etchant, the etchant does not come into contact with the non-etching surfaces 1b. The holding device 10 holds the peripheral edges of both the semiconductor wafers 1, so no stress operates in the surface direction of the semiconductor wafers 1, which are therefore not damaged. Further, a plurality of holding devices 10 each holding a pair of semiconductor wafers 1 are dipped in the etchant to etch many semiconductor wafers 1 simultaneously. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a semiconductor wafer etching apparatus.

  Conventionally, two types of methods have been proposed for simultaneously etching a plurality of semiconductor wafers. One is a technique in which each semiconductor wafer is immersed in an etching solution after wax is applied to the non-etched surface of each semiconductor wafer. The other is a method in which a non-etched surface of each semiconductor wafer is protected and a device that sucks the non-etched surface in a vacuum is used, and the entire device is immersed in an etching solution.

Japanese Patent No. 2857958 (paragraphs 18 to 20, FIGS. 6 and 7).

However, the former method described above has a problem that etching efficiency is poor because it is necessary to apply wax to the non-etched surface of all semiconductor wafers. In the latter method, since the non-etched surface of the semiconductor wafer is sucked in vacuum, the semiconductor wafer may be damaged in the surface direction. In particular, in the case of a semiconductor wafer in which a semiconductor device having a sensing part having a membrane structure such as a pressure sensor is formed on an etching surface, the thin sensing part is easily damaged. Moreover, since it is necessary to mount an apparatus for each semiconductor wafer, there is a problem that the cost required for etching increases.
That is, the conventional one has the main problems that the etching efficiency is low and the semiconductor wafer may be damaged.

  Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is to realize a semiconductor wafer etching apparatus that has good etching efficiency and that does not cause the semiconductor wafer to be damaged in the surface direction. And

  In order to achieve the above object, according to the first aspect of the present invention, in the first aspect of the invention, the peripheral edges of the pair of semiconductor wafers (1, 1) whose non-etched surfaces (1b) face each other are held in a liquid-tight state. The apparatus (10) is provided, and the technical means that the one set of semiconductor wafers held by the holding device is configured to be immersed in the etching solution (4) is used.

  According to a second aspect of the present invention, in the semiconductor wafer etching apparatus according to the first aspect, the semiconductor wafer (1) is immersed in the etching solution (4) to thereby form a sensing part (1d) having a membrane structure. Is used to form the etching surface (1a).

  According to a third aspect of the present invention, in the semiconductor wafer etching apparatus according to the first or second aspect, the holding device (10) includes a holding member (11, 12, 13) that holds the peripheral edge, A technical means is provided that includes a vacuum device (20, 21) for evacuating a boundary between the holding member and the peripheral edge.

  According to a fourth aspect of the present invention, in the semiconductor wafer etching apparatus according to any one of the first to third aspects, a space (2) is formed between the non-etched surfaces (1b). The technical means that a pressure control device (30) for controlling the pressure in the space is provided is used.

  According to a fifth aspect of the present invention, in the semiconductor wafer etching apparatus according to the fourth aspect, the pressure control device (30) fills the space (2) with a gas and controls the pressure of the gas. The technical means of controlling the pressure in the space is used.

  According to a sixth aspect of the present invention, in the semiconductor wafer etching apparatus according to the fourth aspect, the pressure control device (30) fills the space (2) with a liquid and controls the pressure of the liquid. The technical means of controlling the pressure in the space is used.

  According to a seventh aspect of the present invention, in the semiconductor wafer etching apparatus according to any one of the fourth to sixth aspects, the pressure control device (30) is a pressure detection device that detects the pressure in the space. (40) is used, and technical means for stopping the etching when the pressure detected by the pressure detection device reaches a predetermined value is used.

  According to an eighth aspect of the present invention, in the semiconductor wafer etching apparatus according to any one of the first to seventh aspects, the one set of semiconductor wafers (1, 1) held by the holding device (10). A plurality of sets of 1) are arranged, and an etching trough (50) for immersing each set of semiconductor wafers in the etchant (4) is provided, and technical means of stirring the etchant in the etching trough is used.

  In addition, the code | symbol in each said parenthesis shows the correspondence with the specific example in embodiment of invention mentioned later.

(Effect of the invention according to claim 1)
Since the peripheral edges of a set of semiconductor wafers whose non-etching surfaces face each other are held in a liquid-tight state by a holding device, the etching solution is not etched when the set of semiconductor wafers is immersed in an etching solution. There is no risk of touching.
Therefore, a set of semiconductor wafers can be etched at the same time without performing wax treatment on the non-etched surface of each semiconductor wafer, so that the etching efficiency can be improved.
In addition, since the holding device holds the peripheral edge of the pair of semiconductor wafers, no stress acts in the surface direction of the semiconductor wafer, so that there is no possibility that the semiconductor wafer is damaged in the surface direction.

  In particular, as described in claim 2, when the semiconductor wafer is immersed in an etching solution to form a sensing portion of the membrane structure on the etching surface, pressure is applied in the surface direction of the semiconductor wafer. However, according to the first aspect of the present invention, since the holding device holds the periphery of the semiconductor wafer, there is no possibility that the sensing unit is damaged.

(Effect of the invention according to claim 3)
Since the boundary between the holding member and the peripheral edge is evacuated by the vacuum device, the boundary portion can be maintained in a good liquid-tight state.

(Effect of the invention according to claim 4)
Since the pressure in the space formed between the non-etched surfaces can be controlled, the semiconductor wafer can be prevented from being damaged by the pressure of the etchant applied in the direction of the etched surface.

For example, as described in claim 5, the semiconductor wafer can be prevented from being damaged by filling the space with a gas and controlling the pressure of the gas.
According to a sixth aspect of the present invention, the semiconductor wafer can be prevented from being damaged by filling the space with a liquid and controlling the pressure of the liquid.

(Effect of the invention according to claim 7)
Conventionally, the relationship between the elapsed time from the start of etching and the progress of etching is obtained, and the etching is stopped when the target time is reached from the start of etching.
However, in the conventional method, the degree of progress of etching has varied due to unevenness in the concentration of the etching solution or an error in the thickness of the semiconductor wafer.

In the present invention, as the etching of the etching surface proceeds, the semiconductor wafer is displaced (deformed) in the surface direction, so that the pressure in the space also changes.
Therefore, the relationship between the progress of etching and the pressure in the space is obtained in advance. This relationship does not change due to unevenness in the concentration of the etching solution or an error in the thickness of the semiconductor wafer.
If a pressure detection device for detecting the pressure in the space is provided, and etching is stopped when the pressure detected by the pressure detection device reaches a predetermined value, the etching accuracy can be improved.

(Effect of the invention according to claim 8)
Since a plurality of sets of semiconductor wafers can be etched simultaneously, the etching efficiency can be further increased. In addition, since the etching solution is agitated, there is no unevenness in the concentration of the etching solution, so that the etching accuracy can be improved.
As a method of stirring the etching solution, a method of providing a fan or the like for stirring the etching solution in the etching bowl may be used, or a method of moving each set of semiconductor wafers themselves in the etching solution.

<First Embodiment>
A first embodiment according to the present invention will be described with reference to the drawings. In the following embodiments, a semiconductor wafer etching apparatus (hereinafter abbreviated as an etching apparatus) for manufacturing a pressure sensor will be described as an example.
FIG. 1 is a longitudinal sectional view of a holding device provided in the etching apparatus according to this embodiment. 2 is an external view of the holding device shown in FIG. 1, (a) is a side view of the holding device shown in FIG. 1 as viewed from arrow A, and (b) is the holding device shown in (a) from arrow B. FIG. FIG. 3 is an enlarged view of a main part of the holding device shown in FIG. 6 (a) to 6 (c) and FIGS. 7 (a) and 7 (b) are explanatory views showing an etching solution stirring method.

[Main configuration]
The etching apparatus according to this embodiment includes a holding device 10 that holds a set of semiconductor wafers 1, a vacuum pump 20 that maintains a liquid-tight state between the holding device 10 and each semiconductor wafer 1, and the vacuum pump 20. And a tube 21 for connecting the holding device 10 and the vacuum pump 20 to each other.

  Each semiconductor wafer 1 is formed in a disc shape. Each semiconductor wafer 1 is disposed with the non-etched surfaces 1b facing each other. A space 2 is formed between the non-etched surfaces 1b of each semiconductor wafer 1. Each semiconductor wafer 1 is used to manufacture a plurality of pressure sensors. By etching the etching surface 1a with an etching solution, a plurality of cavities 1c are formed, and a sensing portion (a portion that reacts to pressure) having a membrane structure. A plurality of 1d are formed.

  A holding device 10 is mounted on the periphery of each semiconductor wafer 1. The holding device 10 includes a holding member 11 attached to the periphery of one semiconductor wafer 1, a holding member 12 attached to the periphery of the other semiconductor wafer 1, and a connection member 13 that connects the holding members 11, 12. With. As shown in FIG. 2, the holding members 11 and 12 and the connection member 13 are each formed in a ring shape in plan view corresponding to the peripheral shape of the semiconductor wafer 1.

  Of the holding members 11 and 12, O-rings 11 a and 12 a are respectively attached to the peripheral edges in contact with the peripheral edge of the semiconductor wafer 1. In addition, an O-ring 13 a is attached to the periphery of the connecting member 13 that is in contact with the holding members 11 and 12. Each O-ring is made of a highly liquid-tight material (for example, rubber).

As shown in FIG. 3, gaps 11b and 12b are formed at the boundaries between the O-rings 11a and 12a and the corresponding peripheral edges of the semiconductor wafer 1, respectively. A communication passage 13b that communicates with the gaps 11b and 12b is formed inside the O-ring 13a.
One end of the tube 21 is inserted from the peripheral surface of the connecting member 13 into the O-ring 13a, and the one end communicates with the communication path 13b. In FIG. 3, the gaps 11b and 12b and the communication path 13b are drawn wider than they actually are for the sake of clarity.

  The control device 22 connected to the vacuum pump 20 controls the operation of the vacuum pump 20 and maintains the liquid-tight state between the holding device 10 and each semiconductor wafer 1. The etching apparatus includes a plurality of holding devices 10, and a set of semiconductor wafers 1 is held in each holding device 10 (FIGS. 6 and 7). In addition, each holding device 10 holding the semiconductor wafer 1 is accommodated in an etching trough 50, and an apparatus for taking out each holding device 10 from the etching solution 4 after the etching is provided.

[Etching process]
In FIG. 1, it is assumed that the side indicated by the arrow A is the lower side when setting the semiconductor wafer. First, one semiconductor wafer 1 is placed on the holding member 11 placed on the setting surface. At this time, one of the semiconductor wafers 1 is placed so that the etching surface 1a faces downward and the non-etching surface 1b faces upward. Next, the connection member 13 is placed on the holding member 11.

  Next, the other semiconductor wafer 1 is placed on the connection member 13. At this time, the other semiconductor wafer 1 is placed so that the non-etched surface 1b faces downward and the etched surface 1a faces upward. That is, the two semiconductor wafers 1 are placed so that the non-etched surfaces 1b face each other. Next, the holding member 12 is placed on the semiconductor wafer 1.

Next, the vacuum pump 20 is operated by the control device 22 so that each semiconductor wafer 1 is brought into close contact with the O-rings 11a and 12a, and the O-rings 11a and 12a are brought into close contact with the O-ring 13a. Thereby, each semiconductor wafer 1 and the holding device 10 are maintained in a liquid-tight state. With respect to the other holding devices 10, one set of semiconductor wafers 1 is held for each holding device 10 by the same procedure.
The holding device 10 is arranged radially as shown in FIG. 6 according to the stirring method, or arranged so that the semiconductor wafers face each other as shown in FIG.

Next, each holding device 10 in a state of holding a pair of semiconductor wafers 1 is accommodated in the etching trough 50, immersed in the etching solution 4, and the etching solution 4 is stirred.
The stirring of the etching solution 4 uses a technique in which the stirring member 51 is arranged at the center of the space surrounded by the holding devices 10 arranged radially as shown in FIG. 6A and the stirring member 51 is rotated. You can also. Further, as shown in FIG. 6B, a method may be used in which the holding devices 10 are arranged radially inside the etching rod 50 and the etching rod 60 is rotated. Moreover, as shown in FIG.6 (c), the method of rotating each holding | maintenance apparatus 10 itself arrange | positioned radially may be sufficient.

Furthermore, as shown in FIG. 7A, the holding devices 10 are arranged inside the etching trough 50 so that the semiconductor wafers face each other, and a stirring member (for example, a fan) provided inside the etching trough 50 A method of rotating 52 may be used. Further, as shown in FIG. 7B, each holding device 10 is arranged inside the etching trough 50 so that the semiconductor wafers face each other, and each holding device 10 itself is moved (for example, linear reciprocating motion). It is also possible to use this method.
Then, each holding device 10 is taken out from the etching solution 4 when the target etching time has elapsed.

[Effect of the first embodiment]
(1) Since the peripheral edge of a set of semiconductor wafers 1 where the non-etching surfaces 1b face each other is held in a liquid-tight state by the holding device 10, the set of semiconductor wafers 1 is immersed in the etching solution 4. Furthermore, there is no possibility that the etching solution 4 contacts the non-etched surface 1b.
Therefore, since many semiconductor wafers 1 can be etched simultaneously without performing wax treatment on the non-etched surface 1b of each semiconductor wafer 1, the etching efficiency can be improved.
In addition, since the holding device 10 holds the peripheral edges of the pair of semiconductor wafers 1 and 1, no stress acts in the surface direction of the semiconductor wafer 1, so there is no possibility that the semiconductor wafer 1 is damaged in the surface direction.

(2) In particular, since the semiconductor wafer 1 for manufacturing the pressure sensor forms the sensing part 1b having a membrane structure by etching, the strength in the surface direction of the sensing part 1b is weak. Since it holds, there is no possibility that the sensing part 1b will be damaged.

Second Embodiment
Next, a second embodiment of the present invention will be described with reference to the drawings. The etching apparatus according to this embodiment is characterized in that distortion of the semiconductor wafer 1 accompanying the progress of etching can be prevented. FIG. 4 is a longitudinal sectional view of a holding device provided in the etching apparatus according to this embodiment. Note that the description of the same configuration as the etching apparatus of the first embodiment is omitted.

  One end of the tube 31 is inserted from the peripheral surface of the connection member 13 through the O-ring 13 a into the space 2, and the other end of the tube 31 is connected to the pressure control device 30. Further, tubes 21 and 21 connected to the vacuum pump 20 are inserted into the O-ring 13a. The space 2 is filled with a gas such as air, and the pressure of the gas is controlled by the pressure control device 30.

As the etching of each semiconductor wafer 1 proceeds, the film thickness of the sensing portion 1d of the membrane structure gradually decreases, so that each sensing portion 1d of each semiconductor wafer 1 is distorted (swells) in the direction of the space 2 due to the pressure of the etching solution.
Therefore, the pressure is applied to the space 2 by the pressure control device 30 before the etching is started, and even if the thickness of the sensing unit 1d is reduced as the etching progresses, the sensing unit 1d is not in the space 2. Do not distort in the direction. As for the magnitude of the pressure applied to the space 2, a pressure at which the sensing unit 1d is not distorted by the pressure of the etching solution 4 is obtained in advance by experiments or simulations.
Thereby, the sensing part 1d can be prevented from being damaged by the pressure of the etching solution 4.

<Third Embodiment>
Next, a third embodiment of the invention will be described with reference to the drawings. The etching apparatus according to this embodiment is characterized in that the accuracy of etching can be improved. FIG. 5 is an explanatory diagram of a pressure sensor mounted on a semiconductor wafer.

  The etching apparatus according to this embodiment does not include the pressure control apparatus 30 of the second embodiment, and the tube 31 is not inserted through the connection member 13. The space 2 is sealed and maintained at a constant pressure. As shown in FIG. 5, a pressure sensor 40 is provided on the non-etched surface 1 d of the semiconductor wafer 1.

  The pressure sensor 40 detects the pressure in the space 2. The wiring connected to the pressure sensor 40 is electrically connected to an external etching control device (not shown) through the connection member 13. The etching control device performs control for taking out each holding device 10 from the etching solution 4 in accordance with the pressure detected by the pressure sensor 40.

  Further, the relationship between the film thickness of the sensing unit 1d and the pressure in the space 2 is obtained in advance by experiments, and the relationship is binarized and stored in a table format in a storage device in the etching control device. .

  Then, as the etching progresses, the thickness of each sensing unit 1d decreases, and when each sensing unit 1d expands toward the space 2, the pressure in the space 2 increases, and the pressure value is detected by the pressure sensor 40. Is done. When the film thickness of each sensing unit 1d reaches the target value and the pressure in the space 2 reaches a predetermined value, the etching control device takes out each holding device 10 from the etching solution 4 and stops etching.

As described above, according to the etching apparatus of the third embodiment, the etching can be stopped according to the pressure of the space 2 that changes in accordance with the film thickness of the sensing unit 1d, instead of being controlled by the etching time. .
Therefore, the etching accuracy can be improved because the etching solution is not affected by unevenness in the concentration of the etching solution or an error in the thickness of the semiconductor wafer.
The pressure sensor 40 may be attached to the O-ring 13a, for example, as long as the pressure in the space 2 can be accurately detected.

<Other embodiments>
(1) In each of the above-described embodiments, the configuration in which the space 2 is formed between the non-etched surfaces 1b of the semiconductor wafer 1 has been described. However, the configuration in which the non-etched surfaces 1b are in contact with each other is also held by the holding device 10. Is possible.

(2) A configuration in which a support member having a shape corresponding to the semiconductor wafer 1 is interposed between the non-etching surfaces 1b and the non-etching surfaces 1b of the respective semiconductor wafers 1 are in contact with both surfaces of the support member is also possible. In addition, when there is a problem that the support member and the semiconductor wafer are in close contact with each other and it is difficult to separate the semiconductor wafer from the support member, the problem can be solved by using a support member having unevenness on both sides (for example, polished glass). .

(3) A fixing member (not shown) may be mounted on the peripheral surfaces of the holding members 11 and 12 and the connecting member 13 so as to fix them in close contact with each other to ensure liquid tightness between the members. . According to this configuration, since the vacuum pump 20 and the tube 21 are not necessary, the manufacturing cost of the etching apparatus can be reduced.

(4) In the second embodiment, the space 2 can be filled with a liquid such as water instead of the gas.

(5) In 2nd Embodiment, the pressure sensor 40 used in 3rd Embodiment is provided in the predetermined location of the space 2, and a pressure control apparatus is used so that the pressure value of the space 2 detected by the pressure sensor may become constant. 30 can also be controlled. According to this configuration, since the pressure in the space 2 can be controlled so as not to change as the film thickness of each sensing unit 1d becomes thinner, it is possible to reliably prevent distortion of each sensing unit 1d as etching progresses. can do.

FIG. 3 is a longitudinal sectional view of a holding device provided in the etching apparatus according to the first embodiment. 2 is an external view of the holding device shown in FIG. 1, (a) is a side view of the holding device shown in FIG. 1 as viewed from an arrow A, and (b) is a plan view of the holding device shown in FIG. It is. It is a principal part enlarged view of the holding | maintenance apparatus shown in FIG. It is a longitudinal cross-sectional view of the holding | maintenance apparatus with which the etching apparatus which concerns on 2nd Embodiment was equipped. It is explanatory drawing of the pressure sensor with which the semiconductor wafer was mounted | worn. FIGS. 6A to 6C are explanatory views showing a stirring method for the etching solution. FIGS. 7A and 7B are explanatory views showing a method for stirring the etching solution.

Explanation of symbols

1..Semiconductor wafer, 1a..etched surface, 1b..non-etched surface,
1c..Cavity part, 1d..Sensing part, 2..Space, 4 .... Etching solution,
10 .. Holding device, 11, 12, 13 .. Holding member,
20. ・ Vacuum pump (vacuum device), 30 ・ ・ Pressure control device,
40 ·· Pressure sensor (pressure detector), 50 · · Etching soot,
51, 52 .. Stirring member.

Claims (8)

A holding device that holds the periphery of a set of semiconductor wafers whose non-etched surfaces face each other in a liquid-tight state;
An etching apparatus for a semiconductor wafer, characterized in that the set of semiconductor wafers held by the holding apparatus can be immersed in an etching solution.   The semiconductor wafer etching apparatus according to claim 1, wherein the semiconductor wafer forms a sensing portion having a membrane structure on an etching surface by being immersed in the etching solution. The holding device is
A holding member for holding the peripheral edge;
The semiconductor wafer etching apparatus according to claim 1, further comprising: a vacuum apparatus that evacuates a boundary between the holding member and the peripheral edge.   4. The semiconductor wafer according to claim 1, wherein a space is formed between the non-etched surfaces, and a pressure control device that controls a pressure in the space is provided. 5. Etching equipment. The pressure control device includes:
5. The semiconductor wafer etching apparatus according to claim 4, wherein the space is filled with a gas and the pressure of the space is controlled by controlling the pressure of the gas. The pressure control device includes:
5. The semiconductor wafer etching apparatus according to claim 4, wherein the space is filled with a liquid and the pressure of the space is controlled by controlling the pressure of the liquid. The pressure control device includes:
The pressure detection device for detecting the pressure in the space is provided, and etching is stopped when the pressure detected by the pressure detection device reaches a predetermined value. The semiconductor wafer etching apparatus according to claim 1.   A plurality of sets of the one set of semiconductor wafers held by the holding device are arranged, an etching trough for immersing each set of semiconductor wafers in an etching solution is provided, and the etching solution in the etching trough is stirred. An apparatus for etching a semiconductor wafer according to any one of claims 1 to 7.

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