JP2002170809A - Device and method of clamping semiconductor wafer for etching apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and high-precisely position a semiconductor wafer for an etching pot or a thickness sensor. SOLUTION: An etching apparatus comprises: an etching pot 22, which comprises a wafer base 26, a wafer ring 28, and a cylinder 29, where a semiconductor wafer 1 is sandwiched by the wafer base 26 and the wafer ring 28 which are connected to the etching pot 22 by the cylinder 29; and an etching base having a thickness sensor, where the etching pot 22 is placed on the etching base. A clamp device 25 comprises: a support ring 80, which supports the etching pot 22 to turn upside down in a horizontal position; a wafer receiver 81, which supports the semiconductor wafer 1 between the wafer ring 28 and the wafer base 26 in a horizontal position; a position adjustment mechanism 82, which performs position adjustment of the wafer receiver 81 namely the semiconductor wafer 1 in the directions of X, Y, and θ; an expanding camera 89, which is set in a positioning state on the wafer base 26; and a monitor 90. The semiconductor wafer 1 is positioned so that a thickness measuring point K in the semiconductor wafer matches with a detecting point (mark M) of the thickness sensor by using an image taken by the expanding camera 89.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching apparatus which uses an etching pot and performs etching while detecting the thickness of a semiconductor wafer with a non-contact type thickness sensor.
The present invention relates to a semiconductor wafer clamping device and a clamping method for clamping between two clamp members.

[0002]

When manufacturing a sensor chip such as a semiconductor pressure sensor or a semiconductor acceleration sensor, for example, as shown schematically in FIG. Thousands of sensor chips 2 are formed, and then each chip 2 is cut off. In this case, as shown in FIG. 7B, an epitaxial layer is formed on one side of the semiconductor wafer 1, and a circuit element, a power supply electrode, and the like constituting a signal processing circuit corresponding to each sensor chip 2 are provided. This surface is referred to as a circuit surface 1a.

In the case of a pressure sensor, the sensor chip 2 has a shape as shown in FIG. 8, and a concave portion 2a is formed on the surface opposite to the circuit surface 1a except for the peripheral portion. A diaphragm is formed. Also, in the case of an acceleration sensor, as shown in FIG.
A concave portion 2a is formed on a surface opposite to the circuit surface 1a in a state where an island-shaped bulge is left in the center.
Generally, in order to form the concave portion 2a, an etching surface 1b of the semiconductor wafer 1 opposite to the circuit surface 1a is covered with a mask 3 except for a portion where the concave portion 2a is formed, and then the etching surface 1b is made of, for example, water. An immersion type etching method (for example, anisotropic etching) of immersion in a strong alkaline liquid such as potassium oxide is used.

FIG. 10 shows a conventional etching apparatus. Here, the semiconductor wafer 1 has its circuit surface 1a
The outer peripheral edge of the etched surface 1b (the area where the sensor chip 2 is not formed) is covered with the masking material 4 and held by an etching jig 5 made of, for example, a ceramic plate. Then, in this state, the etching surface 1b is immersed in the processing tank 7 containing the etching solution 6.
Is etched. Further, when the etching of a predetermined thickness is performed, the semiconductor wafer 1 held by the etching jig 5 is taken out of the processing tank 7 and
By performing the water cleaning, the etching is stopped.

In this case, in order to maintain the etching solution 6 at a temperature (for example, 110 ° C.) suitable for processing, the processing tank 7 is provided with a heater 8.
Are controlled by a heater control circuit 10 based on the detection of a temperature sensor 9 for detecting the temperature of the etching solution 6. A stirrer 11 for stirring the etching solution 6 is also provided in the processing tank 7. When the electrochemical stop etching is performed, the electrode 12 immersed in the etching solution 6 and the electrode 12 and the semiconductor wafer 1 are further immersed.
(Circuit surface 1a) and a power supply 1 for flowing a direct current
3. A current detector 14 for detecting the value of the flowing current is provided.

When the sensor chip 2 is formed, the thickness T of a thin portion (diaphragm in the case of a pressure sensor) formed by etching on the semiconductor wafer 1 (sensor chip 2) shown in FIGS. It is important to perform processing with high accuracy to obtain a thickness in terms of sensor performance. Therefore, in performing the above-mentioned etching process, it is necessary to manage the etching to be stopped when a predetermined etching depth of the concave portion 2a is obtained. Conventionally, a time management method has generally been adopted as a method of controlling the thickness.

This time management system utilizes the fact that the etching time and the etching depth are substantially proportional to each other. As shown in FIG. 11, the amount of etching per unit time (referred to as etching rate) is previously determined on a test basis. Then, a graph showing the relationship between time and etching depth is created. Then, from the original thickness T0 of the semiconductor wafer 1 and the target thickness T, a time t1 at which an etching depth of (T0-T) is obtained is obtained from a graph, and the actual etching time (immersion time) is managed. Was something.

However, in this method, since accurate reproducibility of the etching rate is required, it is necessary to strictly control the concentration and the temperature of the etching solution 6. Average thickness variation ±
0.5 μm) by a single etching process. Therefore, in practice, the etching process and the thickness measurement are divided into a plurality of times and the processes are repeated.

In the case of electrochemical stop etching, as shown in FIG. 12, the current value detected by the current detector 14 fluctuates with the lapse of time, and the current value changes near the target thickness T. Using the appearance of the peak value P,
The etching is stopped after a lapse of a predetermined time t2 from the appearance of the peak value P. According to this, since the influence of the etching rate is small, the accuracy of the thickness management is higher than that of the above-described time management method.

However, in the electrochemical stop etching, a diaphragm having a thickness of 20 μm or more cannot be etched, and a thickness smaller than the epi layer cannot be obtained in principle. Since the thickness of the epi layer varies between semiconductor wafers 1 by about ± 10%, an average thickness variation between wafers of about ± 1 μm occurs, and sufficient accuracy of the thickness cannot be obtained by one process. Had become something. Thus, in the conventional method,
There is a fundamental problem that it is not possible to accurately and directly grasp the thickness of the semiconductor wafer 1 during the etching to control the etching stop timing.

Therefore, the present applicant has developed a thickness sensor 51 (see FIGS. 8 and 9) capable of directly detecting the thickness of the semiconductor wafer 1 in a non-contact manner, and has filed an application first ( See JP-A-7-306018). If the etching process can be controlled by the thickness sensor 51 while monitoring the thickness of the etched portion of the semiconductor wafer 1, the thickness control can be performed with high accuracy.
However, in the above-mentioned conventional immersion type etching processing method, the arrangement itself of the thickness sensor 51 is difficult,
Even if it can be arranged, it is difficult to put it to practical use, for example, a complicated structure is required to protect the sensor from the etching solution 6.

On the other hand, although not shown, the present inventors replace the conventional immersion method with the semiconductor wafer 1 at its end (outer peripheral edge) by using two ring-shaped clamp members (wafers). A so-called pot construction method has been developed in which an etching processing chamber (etching pot) having an etching surface 1b of the upper surface of the semiconductor wafer 1 as an inner bottom surface by holding the semiconductor wafer 1 in a clamped state from above and below by a base and a wafer ring. I have. According to this pot method, the circuit surface 1a side of the semiconductor wafer 1 can be opened, and the mounting of the thickness sensor 51 described above can be realized.

However, with the miniaturization and high precision of the sensor chip 2, a minute concave portion 2a having a side of, for example, 1 mm or less is provided.
In the case where is formed, how to precisely align the measurement point k of the semiconductor wafer 1 with the detection position of the thickness sensor 51 in the horizontal direction becomes a new technical problem. In this case, a plurality of types of semiconductor wafers 1 are etched by one etching apparatus (pot). However, a position adjustment mechanism for adjusting the position between the etching pot and the thickness sensor 51 is provided, and the semiconductor wafer 1 is etched. If the relative position of the thickness sensor 51 is finely adjusted each time the sensor is replaced, the configuration becomes large and complicated, and the operation is considerably difficult, and the productivity is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an etching apparatus using an etching pot for sandwiching a semiconductor wafer between two clamp members. It is an object of the present invention to provide a semiconductor wafer clamping apparatus and a clamping method in an etching apparatus capable of easily and highly accurately aligning semiconductor wafers.

[0015]

In order to achieve the above object, a semiconductor wafer clamping device in an etching apparatus according to claim 1 of the present invention is provided by means of a temporary holding means. The semiconductor wafer is held between the clamp members so that the position of the semiconductor wafer can be adjusted in the horizontal direction, the position of the semiconductor wafer with respect to the clamp member is measured by the measuring means, and the thickness in the semiconductor wafer is measured by the position adjusting means based on the measurement. The semiconductor wafer is positioned with respect to the clamp member such that the point coincides with the detection position of the thickness sensor, and the two clamp members are fastened by the fastening means while the semiconductor wafer is aligned.

According to a fifth aspect of the present invention, there is provided a method for clamping a semiconductor wafer in an etching apparatus, wherein the semiconductor wafer is held between two clamp members vertically spaced so as to be position-adjustable in a horizontal direction. Based on the temporary holding step and the measurement by the measuring means for measuring the position of the semiconductor wafer with respect to the clamp member, the semiconductor wafer is aligned with the clamp member such that the thickness measurement point in the semiconductor wafer coincides with the detection position of the thickness sensor. And a fastening step of fastening the two clamp members in a state where the semiconductor wafer is aligned.

According to these, both clamp members can be fastened and clamped in a state where the semiconductor wafer is pre-aligned with respect to the clamp members, and when the etching pot is set in the etching apparatus, The thickness measurement point of the semiconductor wafer surely coincides with the detection position of the thickness sensor. Accordingly, the etching can be controlled while monitoring the thickness of the etched portion of the semiconductor wafer by the thickness sensor, and the thickness control can be performed with high accuracy.

At this time, before the semiconductor wafer is clamped by the two clamp members, in other words, before the etching pot is set in the etching apparatus, the position adjustment of the semiconductor wafer with respect to the etching pot is performed. Can be performed efficiently. At the same time, since the position of the semiconductor wafer is adjusted with respect to the clamp member, a large and complicated structure is required, such as when an etching apparatus is provided with a structure for adjusting a relative position between an etching pot and a thickness sensor. Configuration is unnecessary, and a relatively simple configuration can be achieved.
The installation of the measuring means is also facilitated, and the positioning operation can be performed easily and with high accuracy compared to the case where the relative position adjustment of the entire etching pot with respect to the thickness sensor is performed.

In this case, the position of the semiconductor wafer with respect to the clamp member is adjusted not only in the X and Y directions but also in θ.
If it can be performed also in the direction (claims 2 and 6
Invention), it is possible to perform precise position adjustment, and it is not necessary to pay much attention to the arrangement of the semiconductor wafer in the rotation direction with respect to the clamp member at the time of temporary holding, and the working efficiency can be improved. .

The temporary holding of the semiconductor wafer is horizontally and elastically held at an intermediate portion between the two clamp members by the upward spring force of the elastic member, and when the two clamp members are fastened, the semiconductor wafer is converted into the spring force by the fastening force. It can also be made to descend against it (the invention of claims 3 and 7). According to this, an excessive force such as a bending force is prevented from acting on the semiconductor wafer at the time of fastening, and the semiconductor wafer can be protected.

Further, a plurality of thickness sensors having different detection positions are provided so as to be selectively used, and the position of the semiconductor wafer is adjusted so that the thickness measurement point coincides with one of the detection positions. It may be performed (the inventions of claims 4 and 8). According to this, when adjusting the position so that the thickness measurement point coincides with the detection position, for example, if the position is adjusted to the closest detection position, a small amount of movement is required, and the position adjustment operation can be performed easily and in a short time. It becomes possible.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an etching process of a semiconductor wafer for forming sensor chips of a plurality of pressure sensors will be described below with reference to FIGS. In this embodiment, FIGS.
In this example, the recess 2a of each sensor chip 2 is formed by etching the semiconductor wafer 1 as shown in FIG. Therefore, since the semiconductor wafer 1, the sensor chip 2, the thickness sensor 51, and the like are common to those described in the conventional example, new illustrations and detailed explanations are omitted, and reference numerals are used in common.

FIG. 4 shows the overall structure of the etching apparatus 21 in this embodiment. The etching apparatus 21 is roughly divided into an etching pot 22 for holding the semiconductor wafer 1, an etching base 23 for detachably supporting the lower surface of the etching pot 22, and an upper surface of the etching pot 22 so as to be detachably mounted. , An etching head 24 provided for the Although not shown, a control device such as a microcomputer for controlling (producing and managing) the entire etching device 21 is provided.

First, the etching pot 22
Will be described with reference to FIGS. 1 to 3 as well.
The etching pot 22 constitutes a part of a clamp device 25 (see FIG. 1) according to the present embodiment, as will be described later.
In FIG. 1, the etching pot 22 is used in an upside-down state, and FIGS. 1 and 2 show the etching pot 22 in an upside-down state in FIG.

The etching pot 22 forms a bottom portion, supports the semiconductor wafer 1 from below, and has a wafer base 26 having a heating ring 27 for heating the semiconductor wafer 1, a peripheral wall portion, and The semiconductor device 1 includes a wafer ring 28 for holding the semiconductor wafer 1 between the base 26 and the cylinder 26, and a cylinder 29 constituting fastening means for fastening the wafer base 26 to the wafer ring 28. The wafer base 26 and the wafer ring 28 function as clamp members in the clamp device 25.

As shown in FIGS. 2 and 3, the wafer base 26 is made of a synthetic resin having high heat resistance and corrosion resistance such as Teflon (PTFE) and has an outer diameter sufficiently larger than that of the semiconductor wafer 1. And a relatively thick circular plate having a circular through hole 26a slightly smaller in diameter than the semiconductor wafer 1 in the center. On the upper surface of the wafer base 26, a slightly deeper fitting recess 26b is formed in a ring shape on the entire periphery so as to be located on the outer peripheral side of the semiconductor wafer 1 (the heating ring 27).

Further, on the outer peripheral side (outermost peripheral portion) of the fitting concave portion 26b on the upper surface of the wafer base 26, a ring-shaped concave portion 33 constituting a vacuum chamber is formed over the entire circumference by a cylinder 29 described later. I have. As shown in FIGS. 1 and 2, one portion of the ring-shaped groove 33 is provided with a communication hole 33 a.
Port 3 projecting to the outer periphery of wafer base 26 through
Connected to 0. As shown in FIG. 3, four oval holes 26c are formed on the lower surface side of the wafer base 26.
They are formed at 0 degree intervals.

The heating ring 27 is made of a metal having excellent thermal conductivity, high corrosion resistance and mechanical strength, and has a thermal expansion coefficient equivalent to that of the semiconductor wafer 1, for example, nickel. A flange 27a having an outer diameter slightly larger than the outer diameter of the semiconductor wafer 1 and having an outer peripheral portion slightly rising upward is provided at the upper end of the cylindrical shape so as to fit into the through hole 26a. It is formed integrally. As shown in FIG. 3, four positioning holes 27b are formed in the lower end surface of the heating ring 27 at intervals of 90 degrees. The heating ring 27 is thermally connected to a heating element (ring heater) described later.

Thus, the semiconductor wafer 1 has the flanged portion 2 of the heating ring 27 with the etched surface 1b facing upward.
The wafer 7 is placed on the wafer base 26 with its outer peripheral edge aligned with the wafer 7a. At this time, the hollow portion of the heating ring 27 and the through hole 26a of the wafer base 26 are formed.
Thereby, the lower surface side of the semiconductor wafer 1 is in an open state. Further, the semiconductor wafer 1 is heated by the heating ring 27.
The outer peripheral portion on the lower surface side can be heated.

The wafer ring 28 is made of a material equivalent to that of the wafer base 26, has a substantially cylindrical shape which is relatively short in the vertical direction, and has a lower half portion having an outer diameter substantially equal to that of the wafer base 26. It swells in the outer peripheral direction so that On the lower surface side, a wafer base 26 is provided.
Ring-shaped guide protrusion 28 fitted in the fitting recess 26b
a is provided integrally. On the lower surface of the wafer ring 28, on the outer peripheral side (outermost peripheral portion) of the guide convex portion 28a, a ring-shaped concave portion 32 constituting a vacuum chamber is formed over the entire periphery by a cylinder 29 described later. .

Further, a packing holding portion 28b is provided on a lower inner peripheral portion of the wafer ring 28, and a packing 31 is attached to the packing holding portion 28b. The packing 31 is formed of an elastic body such as rubber having corrosion resistance, and has an inner peripheral shape formed in a ring shape corresponding to an outer peripheral portion of the semiconductor wafer 1. As shown by the gap e in FIG. 2A, the inner diameter of the portion of the wafer ring 28 holding the semiconductor wafer 1 is slightly larger than the outer dimension of the semiconductor wafer 1. It is set to about 2 mm.

The wafer ring 28 is overlapped with the center of the wafer base 26 aligned with the wafer base 26 by fitting the guide projection 28a into the fitting recess 26b. At this time, the lower portion of the inner peripheral portion of the packing 31 abuts on the outer peripheral edge portion (outer portion of the portion where the sensor chip 2 is formed) of the upper surface of the semiconductor wafer 1 placed on the heating ring 27 so as to be sealed. Become. And
In this state, the outer peripheral portion of the lower surface of the wafer ring 28 (ring-shaped concave groove portion 32) and the outer peripheral portion of the upper surface of the wafer base 26 (ring-shaped concave groove portion 33) are vertically opposed with a predetermined gap therebetween. The cylinder 29
Is arranged.

The cylinder 29 is formed in a ring shape from an elastic material such as rubber, for example, and has a substantially square cross section, and has an inner peripheral edge and an outer peripheral edge on the upper surface, and an inner peripheral edge and an outer peripheral edge on the lower surface. The portion is integrally formed with a seal lip 29a extending in a so-called substantially X-shaped cross section in four directions. The cylinder 29 is provided with eight connection holes 29b penetrating vertically, for example, at equal intervals in the circumferential direction.

The two seal lips 29a on the upper surface of the cylinder 29 are positioned so as to straddle the ring-shaped groove 32 in the width direction, so that the lower surface of the ring-shaped groove 32 on the outer peripheral lower surface of the wafer ring 28 is formed. Side is sealed to form a vacuum chamber, and two seal lips 29a on the lower surface side are positioned so as to straddle the ring-shaped groove portion 33 in the width direction, so that the ring-shaped groove portion on the outer peripheral upper surface side of the wafer base 26 is formed. The upper surface side of 33 is closed to form a vacuum chamber. The two vacuum chambers are connected to the connection holes 2.
9b establishes a connected state.

At this time, as shown in FIG. 2A, a cylinder 29 is mounted on the wafer ring 28 and the wafer base 26 is mounted thereon (before the vacuum chamber described later is depressurized). 2), the wafer base 2 is moved by the spring force of the cylinder 29 itself as shown in FIG.
6 and the wafer ring 28 are spaced apart from each other in the vertical direction.

As will be described later in connection with the clamp device 25, a valve 37 is connected to the connection port 30 and a vacuum pump 36 is connected through the valve 37.
Are detachably connected (see FIGS. 1 and 2), and the valve 3
When the vacuum pump 36 is driven in the open state of 7, the inside of the ring-shaped concave grooves 32 and 33 is evacuated (decompressed), whereby the cylinder 29 is elastically deformed, and the wafer ring 28 and the wafer base are deformed. 26 are pulled and fastened in a direction in which they are attracted to each other (see FIG. 2B). At this time, the fastening force uniformly acts on the entire circumference. Thereafter, when the valve 37 is closed, the vacuum state in the ring-shaped concave grooves 32 and 33 is maintained even if the connection with the vacuum pump 36 is disconnected.

As a result, an etching pot 22 is formed in which the semiconductor wafer 1 is vertically held and held by the wafer ring 28 and the wafer base 26. The semiconductor wafer 1 is placed in the etching pot 22.
Thus, an etching chamber 34 is formed in which the etching surface 1b is used as the inner bottom surface and the inner peripheral wall of the wafer ring 28 is used as the inner wall. In the etching chamber 34, for example, K
An etching solution 35 (see FIG. 4) such as OH and pure water for cleaning are accommodated. Thus, the etching pot 22 functions as a masking jig for holding the semiconductor wafer 1 and also functions as a container for etching.

Next, the structure of the etching base 23 will be described with reference to FIG. The etching base 23 is made of a material having high heat resistance and corrosion resistance such as Teflon, for example, and supports the etching pot 22 (wafer base 26) above an installation portion 23a horizontally mounted on an installation surface. It has a cylindrical shape having a supporting base 23b. A circular hole 23c slightly smaller in diameter than the through hole 26a of the wafer base 26 is formed in the center of the support base 23b.
An O-ring 45 is provided at the joint between the installation part 23a and the support base part 23b, and is hermetically sealed.

A fitting pin 46 is provided in the support base 23b so as to penetrate up and down corresponding to the hole 26c on the bottom surface of the wafer base 26. The lower ends of these fitting pins 46 are fixed to a ring-shaped reference plate 47 provided on the back side of the support base 23b, and the heads of the upper ends are fitted into the holes 26c by insertion. It is provided to be. At this time, the fitting pin 4
The reference plate 47 is made of a metal such as nickel.
Is also made of a metal such as SUS304. Also between these fitting pins 46 and the through holes of the support base 23b, O
A ring 48 is provided to ensure airtightness.

A heating unit 49 for heating the heating ring 27 is provided inside the etching base 23, and a main elevating unit 5 for moving the heating unit 49 up and down.
0, a thickness sensor 51 provided in the heating unit 49 for detecting the thickness of the semiconductor wafer 1, and a sensor height adjusting mechanism 52 for adjusting the vertical position of the thickness sensor 51 with respect to the heating unit 49. In this embodiment, a plurality of the thickness sensors 51 are provided in a state where the detection positions are indicated by marks M in FIG. (Only two are shown in FIG. 4). These thickness sensors 51 are selectively used.

The heating unit 49 has a cylindrical heat-generating case 53 having a lower surface opened from a metal having good heat conductivity, a ring heater 54 provided as a heat-generating body provided on an inner peripheral portion of the heat-generating case 53, A heat insulating ring 55 provided inside the ring heater and a heat insulating plate 56 mounted on the upper surface of the heat generating case 53 are provided. A sensor holder 62 that holds the four thickness sensors 51 penetrates vertically through the center of the heat insulating plate 56 and is provided so that the vertical position can be adjusted.

The heat generating case 53 is provided on the support base 23.
b has an outer diameter corresponding to the inner diameter of the circular hole 23c, and is provided slidably up and down on the inner peripheral surface of the circular hole 23c. An O-ring 57 is also provided on this sliding surface. Four positioning pins 53 a corresponding to the positioning holes 27 b of the heating ring 27 are provided on the outer peripheral portion of the upper surface of the heat generating case 53.

The main elevating unit 50 includes an etching base 2
An elevating cylinder 58 provided at the inner bottom of the cylinder 3, an elevating plate 59 attached to a rod of the elevating cylinder 58,
A plurality of columns 60 extending upward from the lifting plate, and a mounting plate 61 attached to the upper ends of the columns 60 and connected to the lower end of the heating unit 49 (heating case 53) are provided. Thus, the heating unit 49 is moved up and down while maintaining a horizontal state between the use position as illustrated and the retracted position (not illustrated) lowered from the use position as illustrated by the driving of the elevating cylinder 58. I have.

At this time, at the position where the heating unit 49 is used, the upper surface of the heat generating case 53 comes into contact with the lower end surface of the heating ring 27 to be thermally connected. Heating case 5 on 27b
3 by inserting the positioning pins 53a, the heat generating case 53 and thus the thickness sensor 51 (the sensor holder 6).
In contrast to 2), the heating ring 27 and thus the wafer base 2
6 (etching pot 22) is positioned at a fixed position. In addition, the heating unit 4
In the use position 9, the heat insulating plate 56 is located on the inner periphery of the heating ring 27, and the upper end of the thickness sensor 51 (sensor holder 62) is separated from the lower surface of the semiconductor wafer 1 by a predetermined amount. Is to be located.

As shown in FIGS. 5, 6, 8, and 9, the thickness sensor 51 measures the thickness of the semiconductor wafer 1 at a predetermined measurement point k on the lower surface of the semiconductor wafer 1 (circuit surface 1).
a) Non-contact detection from the side. The principle is described in Japanese Patent Application Laid-Open No.
No. 18, a detailed description is omitted, but a light beam (for example, infrared light) B transmitted from the tip through the semiconductor
Is irradiated while changing the wavelength, and interference light between the reflected light reflected on the bottom surface of the semiconductor wafer 1 and the reflected light reflected on the surface is detected, and the phase or cycle of the interference light changes the semiconductor wafer 1. This is to directly detect the actual thickness of the measurement point k.

A sensor holder 62 holding these thickness sensors 51 is provided so as to be vertically movable along a guide bar 63 extending upward from the elevating plate 59, and is provided by the sensor height adjusting mechanism 52. The semiconductor wafer 1 of the thickness sensor 51 is moved up and down.
The vertical position (focal length) with respect to is finely adjusted. The heat insulating plate 56 and the sensor holder 6
An O-ring 64 for sealing is provided between the O-ring 64 and the O-ring 2.

The sensor height adjusting mechanism 52 is provided on the lift plate 59 so as to extend upward and to be rotatable, and is screwed to the sensor holder 62 to move up and down.
Servo motor 6 attached to the elevating plate 59
6, a gear mechanism 67 for transmitting the rotation of the servo motor 66 to the lifting screw 65. With this,
The lifting screw 65 is rotated by the servo motor 66,
The sensor holder 62 and thus the thickness sensor 51 move up and down with respect to the heating unit 49.

At this time, as schematically shown in FIG. 4, the detection signal of the thickness sensor 51 is input to a thickness evaluation unit 68 which constitutes a part of the control device. The feedback control of the servo motor 66 is performed so that the optimum focus of the thickness sensor 51 is obtained.

Next, the etching head 24 will be described with reference to FIG. This etching head 24
Has a lid shape that partially closes the upper opening of the wafer ring 28 of the etching pot 22, and is placed on the etching pot 22 with a head seal 69 interposed therebetween. The etching head 24 is provided with an etching solution supply port 24a and a cleaning water supply port 24b communicating with the inside of the etching processing chamber 34, and a drain port 24c for discharging the liquid in the etching processing chamber 34. Is provided.

Although not shown in detail, an etching solution supply mechanism 70 for supplying an etching solution (KOH) 35 into the etching chamber 34 at a controlled temperature is connected to the etching solution supply port 24a. . Further, a cleaning water supply mechanism 71 for supplying cleaning water (pure water) into the etching chamber 34 is connected to the cleaning water supply port 24b. Further, although not shown, a drainage device (for example, a vacuum drainage device such as an ejector) for forcibly discharging the liquid in the etching processing chamber 34 is provided in the drainage port 24c.
Is connected.

The etching head 24 has
A stirrer 72 including a motor 72a and a stirring blade 72b for stirring the etching solution 35 in the etching processing chamber 34 is provided, and a heater 73 for heating the etching solution 35 is provided. Although not shown, a temperature sensor for detecting the temperature of the etching solution 35 is also provided.

Further, the etching head 24 includes
An electrode 74 used for performing the electrochemical stop etching is provided. This electrode 74 is connected to the switch 7
5, is connected to one end of a series connection circuit of a DC power supply 76 and a current detector 77. Although not shown, the other end of the series connection circuit is connected to a power supply electrode provided on the wafer base 26 of the etching pot 22 and in contact with the semiconductor wafer 1. In addition, the etching head 2
An O-ring 78 is provided on each of the mounting portions of the stirrer 72, the heater 73, and the electrode 74.

As will be described in the following description of the operation, the control device operates the operating program and preset products and processing conditions (product type, thickness sensor 51 (detection position) to be used, target thickness T in the concave portion 2a, temperature, Etching apparatus 2 based on etching conditions such as
1 control each mechanism, preheating step, etching step,
An etching process including a cleaning process is performed.

The etching apparatus 21 is configured by setting an etching pot 22 on an etching base 23 and setting an etching head 24 on the upper part of the etching pot 22. The semiconductor wafer 1 is provided in a state of being sandwiched between a wafer base 26 and a wafer ring 28 by a cylinder 29. At this time,
A state in which the semiconductor wafer 1 is preliminarily aligned with the wafer base 26 in the horizontal direction so that the position detected by any of the thickness sensors 51 and the measurement point k of the semiconductor wafer 1 coincide with each other by the clamp device 25 described below. Thus, the wafer is clamped between the wafer base 26 and the wafer ring 28.

FIG. 1 shows the configuration of the clamp device 25 according to the present embodiment. This clamping device 25
On the base plate 79, the etching pot 22
(Wafer ring 28) is turned upside down, and a support ring 80 that horizontally supports the semiconductor wafer 1 while keeping the center axis o aligned, a wafer holder 81 that holds the semiconductor wafer 1 horizontally, and the semiconductor wafer 1 And a position adjusting mechanism 82 as a position adjusting means for adjusting the position of the etching pot 22 (wafer base 2).
6) includes a measuring unit 83 which is detachably disposed on the upper side in FIG.
6 and the like.

The wafer receiving member 81 has a disk shape having an outer diameter slightly smaller than the inner diameter of the wafer ring 28, and the lower surface of the semiconductor wafer 1 (etched surface 1b).
And has a shaft portion 81a at the center of the lower surface thereof. The shaft portion 81a has a cylindrical shape with an open upper surface and is provided in a holder portion 84 connected to the position adjusting mechanism 82. , Which are vertically movably inserted. At this time, a coil spring 85 as an elastic member is accommodated in the inner bottom of the holder portion 84. A notch 81b extending vertically is formed on the outer peripheral surface of the shaft portion 81a, and the notch 81
A stopper 84a is provided to be inserted into the groove b.

Thus, the shaft portion 81a (wafer receiving member 81) is supported so as to be vertically movable within a range in which the stopper 84a relatively moves within the cutout portion 81b.
At normal times (when no downward force acts from outside)
The coil spring 85 is located at the uppermost position shown in the figure by the spring force. At this time, the wafer receiver 81
In the uppermost position, the semiconductor wafer 1 is horizontally suspended between the packing 31 and the heating ring 27 at an intermediate portion between the wafer ring 28 supported by the support ring 80 and the wafer base 26 as shown in the figure. It is designed to be held elastically.

Therefore, the temporary holding means is constituted by the wafer receiver 81 and the like. As will be described later, the wafer base 26 and the wafer ring 2
8, the upper wafer base 26 is lowered, but the fastening force causes the semiconductor wafer 1 held by the wafer receiver 81 to receive a downward force and resist the spring force of the coil spring 85. To descend.

Although the position adjusting mechanism 82 will not be described in detail, the holder portion 84 is moved by the driving force of the motor.
A known XY table 86 that can be freely moved in the direction and the Y direction, and the XY table 86 provided at the center of the base plate 79 in the θ direction (rotation direction) around the central axis o by the driving force of a motor. A known rotary table 87 is provided.

The XY table 86 and the rotary table 8
7 is driven by, for example, a switch operation of an operation panel (not shown) by an operator, whereby the semiconductor wafer 1 held by the holder portion 84 and thus the wafer receiving member 81 is moved to the gap. Within the range of e, the X direction,
The position can be adjusted in the Y direction and the θ direction.

On the other hand, the measuring section 83 has a positioning ring 88 having four positioning pins 88a (only two are shown) corresponding to the positioning holes 27b of the heating ring 27 on the outer peripheral side. The camera includes a magnifying camera 89 attached downward, and a captured image of the magnifying camera 89 is displayed on a monitor device 90. As shown in the figure, the measuring section 83 is detachably set so that each positioning pin 88a is inserted into each positioning hole 27a of the heating ring 27 of the wafer base 26 supported by the support ring 80. ing.

In this state, the magnifying camera 89 photographs the central portion of the upper surface (circuit surface 1a) of the semiconductor wafer 1,
The enlarged image (circuit pattern of the circuit surface 1a) is displayed on the monitor device 90. In this case, the measurement point k of the semiconductor wafer 1 is calculated based on the circuit pattern on the circuit surface 1a.
(The predetermined position of the concave portion 2a of one sensor chip 2) can be specified. The screen of the monitor device 90 is provided with four marks M indicating the detection positions of the thickness sensors 51.

At this time, since the magnifying camera 89 and the heating unit 49 of the etching device 21 and the sensor holder 62 are both positioned at fixed positions with respect to the heating ring 27 (and thus the etching pot 22), the thicknesses of the respective components are reduced. The mark M can be set in advance at a position that matches the detection position of the sensor 51. Therefore, based on the image captured by the magnifying camera 89, the position adjusting mechanism 82
Is operated, the position of the semiconductor wafer 1 with respect to the wafer base 26 (etching pot 22) so that the thickness measurement point k in the semiconductor wafer 1 coincides with one of the detection positions (mark M) of the thickness sensor 51. The matching can be done.

Next, the operation of the above configuration will be described. In performing an etching process on the semiconductor wafer 1 by the etching apparatus 21, first, as a preparation stage, the semiconductor wafer 1 is clamped between a wafer base 26 and a wafer ring 28 to form an etching pot 22. . This work is performed by the clamp device 25 as described below, whereby the clamp method according to the present embodiment is executed.

That is, first, a temporary holding step of holding the semiconductor wafer 1 so that the position of the semiconductor wafer 1 can be adjusted in the horizontal direction is executed between the wafer base 26 and the wafer ring 28 which are vertically spaced. In this step, the wafer ring 28 is set on the support ring 80 in a state where the wafer ring 28 is turned upside down.
Is set upward, a cylinder 29 is placed on a wafer ring 28, and a wafer base 26 is set thereon.

Thus, as shown in FIG. 1, the wafer ring 28 supported by the support ring 80 and the wafer base 26
The semiconductor wafer 1 is horizontally and elastically held in a floating state between the packing 31 and the heating ring 27 at an intermediate portion between them. At this time, the circuit surface 1 of the semiconductor wafer 1 has already been set.
A predetermined circuit pattern is formed on a, and the etched surface 1b is covered with the mask 3 except for the portion where the concave portion 2a is formed.

Next, while measuring the position of the semiconductor wafer 1 with respect to the wafer base 26, the position of the semiconductor wafer 1 is adjusted such that the thickness measurement point k in the semiconductor wafer 1 coincides with the detection position (mark M) of the thickness sensor 51. A position adjustment step of performing alignment is performed. In this step, the respective positioning pins 88a of the positioning ring 88 are inserted into the respective positioning holes 27a of the heating ring 27, so that the wafer base 2
Set the magnifying camera 89 on the upper part of the camera 6 in the positioning state,
An image captured by the magnifying camera 89 is displayed on a monitor device 90.
To be displayed.

Then, while watching the image on the monitor device 90, the position adjusting mechanism 82 is driven so that the thickness measurement point k in the semiconductor wafer 1 coincides with any one of the marks M, and the horizontal position of the semiconductor wafer 1 is adjusted. Adjust the position in the direction. In this case, the XY table 86 can adjust the position of the semiconductor wafer 1 in the X and Y directions, and the rotary table 87 can adjust the position of the semiconductor wafer 1 in the θ direction.

At this time, the position adjustment of the semiconductor wafer 1 is performed as follows.
Since it can be performed not only in the X direction and the Y direction but also in the θ direction, it is possible to perform precise position adjustment,
It is not necessary to pay much attention to the arrangement of the semiconductor wafer 1 in the rotation direction at the time of temporary holding, and the working efficiency can be improved. Further, since the measurement point k may be made to coincide with any one of the four marks M, for example, if the position is adjusted to the closest mark M, a small amount of movement is required. Can be completed.

In the case of the pressure sensor chip 2, the measurement point k is, as shown in FIGS. 5, 6 and 8, a concave portion 2 a of a predetermined sensor chip 2 located at the center of the semiconductor wafer 1. In the case of the acceleration sensor chip 2, it is located at one corner of the recess 2a as shown in FIG. This alignment is, for example, ± 0.05mm
For example, the sensor chip 2 having one side of the concave portion 2a of 1 mm or less can be positioned with high accuracy.

Finally, a fastening step of fastening the wafer base 26 and the wafer ring 28 is performed with the semiconductor wafer 1 positioned as described above. This fastening step is performed by driving a vacuum pump 36 connected to the valve 37 to form a vacuum chamber formed by the cylinder 29 (ring-shaped concave portions 33, 3).
2) is performed in a vacuum state, and as shown in FIG. 2B, the wafer base 26 and the wafer ring 28 are fastened with the semiconductor wafer 1 interposed therebetween, and the etching pot 22 is formed. . At this time, the semiconductor wafer 1 is elastically supported by the coil spring 85, is pressed downward by the wafer base 26 (heating ring 28) at the time of fastening, descends against the spring force, and is bent by the semiconductor wafer 1. An excessive force such as a force is prevented from acting.

Thus, the semiconductor wafer 1 is positioned with respect to the heating ring 27, the outer peripheral edge of the upper surface thereof is sealed by the packing 31, and the portions other than the etching surface 1b are masked, and the etching pot 22 is formed.
Is held. At this time, the entire circumference of the outer peripheral edge of the semiconductor wafer 1 is fastened by the cylinder 29 with an equal force, and the semiconductor wafer 1 is held in a stable state. Also,
The outer peripheral portion of the lower surface of the semiconductor wafer 1 is thermally connected to the heating ring 27. Thereafter, the measuring unit 83 is removed, the valve 37 is closed, the vacuum pump 36 is disconnected, and the etching pot 22 is removed from the support ring 80.

When the etching process is performed by the etching device 21, the etching pot 22 is incorporated into the etching device 21, as shown in FIG. In this case, first, the etching pot 22 is set so as to be placed on the etching base 23 with the etching pot 22 facing upright. In this case, the heating unit 49 is located at the use position and the heating ring 2
7, the positioning pins 53a of the heat generating case 53 are inserted into the positioning holes 27b, and the fitting pins 46 are positioned and set so as to fit into the holes 26c of the wafer base 26.

At this time, the upper surface of the heat generating case 53 is in contact with the lower end surface of the heating ring 27 to be thermally connected. At the same time, the positioning pins 53a of the heat generating case 53 are inserted into the positioning holes 27b of the heating ring 27, so that the heat generating case 53 and thus the thickness sensor 51 (the sensor holder 62) are heated. The pot 22) is positioned at a fixed position, and as shown in FIGS. 5 and 6, the thickness measuring point k of the semiconductor wafer 1 held in advance in alignment with the etching pot 22 is set to the thickness sensor 51. It will surely coincide with the detection position.

At the same time, the sensor height adjusting mechanism 52 is controlled by the thickness evaluation unit 68 so that the height position of the thickness sensor 51 becomes an appropriate focal length with respect to the lower surface of the semiconductor wafer 1. 51 (sensor holder 62)
Is finely adjusted. Thereafter, the etching head 24 is set on the upper part of the etching pot 22,
An etching device 21 is configured.

In the etching process, first, preliminary heating for heating the heating ring 27 and thus the semiconductor wafer 1 is performed by the ring heater 54 (heating unit 49).
After the preheating step, the etching liquid supply mechanism 70
An etching solution 35 whose temperature and concentration are adjusted is supplied from the etching solution supply port 24a into the etching processing chamber 34, and the etching process is started. In this etching step, the etching liquid 35 is stirred by the stirrer 72, and the heater 73 is controlled based on the detection of the temperature sensor, so that the etching liquid 35 is maintained at an appropriate temperature. As a result, a portion of the etched surface 1b of the semiconductor wafer 1 where the mask 3 is not present is etched, and the concave portion 2a is formed gradually deeper.

In this etching step, the thickness sensor 51 continuously detects the thickness of the measurement point k of the semiconductor wafer 1. At this time, in the present embodiment, the thickness detected by the thickness sensor 51 is compared with, for example, an experimentally obtained predicted value set in advance, and the etching process is performed while monitoring that they substantially match. It is going to progress. If the thickness detected by the thickness sensor 51 is far from the predicted value, it is determined that the etching has progressed or the thickness sensor 51 has an abnormality, and the processing is stopped to rescue the semiconductor wafer 1. It is supposed to be.

When the etching proceeds normally and the thickness sensor 51 detects the target thickness T (actually before the target thickness T is reached in consideration of the time lag until the etching is stopped), the heater 73 is turned off. Is stopped,
The cleaning water supply mechanism 71 is operated to supply cleaning water from the cleaning water supply port 24b into the etching processing chamber 34 to dilute and cool the etching solution 35, thereby stopping the etching. At this time, the liquid in the etching processing chamber 34 is forcibly discharged from the liquid discharge port 24c.

When it is confirmed that there is no change in the thickness detected by the thickness sensor 51, it is determined that the etching process has been completed, and the heating unit 49 is moved down.
Further, a cleaning step of stirring while supplying cleaning water into the etching chamber 34 is performed. Until a predetermined cleanness of the etching surface 1b of the semiconductor wafer 1 is obtained (for example, 3
Min) cleaning step is performed, and then the cleaning water is
Forcibly discharged from 4c, drying is performed. Thereafter, the semiconductor wafer 1 is removed from the etching pot 22, and the process is completed.

As described above, according to the present embodiment, the semiconductor wafer 1 can be positioned in advance with respect to the etching pot 22, and when the etching pot 22 is set in the etching device 21, Wafer 1
Is surely coincident with the detection position of the thickness sensor 51. Then, unlike the conventional time management method or the electrochemical stop etching method, the etching can be controlled while directly grasping the actual thickness of the measurement point k of the semiconductor wafer 1 being etched by the thickness sensor 51, As a result, the thickness of the concave portion 2a of the semiconductor wafer 1 can be controlled with high accuracy. Incidentally, in this embodiment, the thickness variation of the concave portion 2a between the semiconductor wafers 1 could be remarkably improved to ± 0.5 μm or less.

At this time, before the semiconductor wafer 1 is clamped between the wafer base 26 and the wafer ring 28, in other words, the etching pot 22 is
Before the semiconductor wafer 1 is set, the position adjustment of the semiconductor wafer 1 with respect to the etching pot 22 is performed. Therefore, unlike the case where the semiconductor wafer 1 is set after setting the semiconductor wafer 1 in the etching apparatus 21, the work of the alignment can be performed efficiently. Can be.

At the same time, since the position of the semiconductor wafer 1 is adjusted with respect to the wafer base 26, the etching device 21 is provided with the etching pot 22 and the thickness sensor 5.
A large and complicated configuration such as a configuration that adjusts the relative position between the two is unnecessary, a relatively simple configuration can be achieved, and the measurement unit 83 can be easily installed. Thus, compared to the case where the relative position of the entire etching pot 22 with respect to the thickness sensor 51 is adjusted, for example, the positioning operation can be performed easily and with high accuracy.

In the above embodiment, the etching pot 2
The operator adjusts the position of the semiconductor wafer 1 with respect to the XY table 86 and the rotary table 87 by operating a switch.
, But the position adjustment can be performed manually, for example, by an operator operating a screw mechanism, or can be fully automated by incorporating a pattern recognition device or the like. is there. The configuration of the position adjusting mechanism 82 can be variously modified. For example, the rotary table 87 may not be provided, and the intended purpose can be achieved if the position can be adjusted at least in the X and Y directions.

In the above embodiment, the positioning hole 27 is provided in the etching pot 22 with the heating ring 27 as the positioning reference. However, the positioning reference 27 is provided in the wafer base 26 (or the wafer ring 28) itself. (Positioning holes and the like) may be provided.
If it is not necessary to heat the heating ring 27, the heating ring 27 and the heating unit 49 can be omitted. The movable range (gap e) of the semiconductor wafer 1 with respect to the etching pot 22 is only an example of ± 2 mm, and can be freely changed depending on the product.

In addition, since only one thickness sensor 51 is provided and the present invention can be applied, the structure of the temporary holding means, the measuring means, the fastening means, and the etching device 21
The present invention departs from the gist of the present invention in that various modifications are possible even in its own configuration, and the present invention is applicable not only to the manufacture of sensor chips for pressure sensors and acceleration sensors, but also to general etching processing of semiconductor wafers. The present invention can be carried out with appropriate changes within a range not to be performed.

[Brief description of the drawings]

FIG. 1 shows one embodiment of the present invention, and is a longitudinal sectional view showing a configuration of a clamp device.

FIG. 2 (a) before fastening a wafer base and a wafer ring
And a longitudinal sectional view showing a state after the fastening (b).

FIG. 3 is a bottom view of an etching pot (wafer base).

FIG. 4 is a longitudinal sectional view showing the overall configuration of the etching apparatus.

FIG. 5 is an enlarged vertical sectional view showing a positional relationship between a measurement point of a semiconductor wafer and a thickness sensor.

FIG. 6 is a perspective view showing a positional relationship between a measurement point of a semiconductor wafer and a thickness sensor.

FIG. 7 is a schematic plan view (a) and a longitudinal sectional view (b) of a semiconductor wafer.

FIG. 8 is a plan view (a) and a longitudinal sectional view (b) of a pressure sensor chip.

FIG. 9 is a plan view (a) and a longitudinal sectional view (b) of an acceleration sensor chip.

FIG. 10 is a diagram schematically showing a configuration of a conventional etching apparatus.

FIG. 11 is a diagram showing a relationship between an etching depth and an etching time.

FIG. 12 is a diagram showing a state of a change in a current value with time in electrochemical stop etching.

[Explanation of symbols]

In the drawings, 1 is a semiconductor wafer, 1a is a circuit surface, 1b is an etched surface, 2 is a sensor chip, 2a is a concave portion, 21 is an etching device, 22 is an etching pot, 23 is an etching base, 24 is an etching head, and 25 is a clamp. Apparatus, 26 is a wafer base (clamp member), 27 is a heating ring, 27b is a positioning hole, 28 is a wafer ring (clamp member), 29 is a cylinder (fastening means), 30 is a connection port, and 32 and 33 are ring-shaped. Concave groove portion, 34 is an etching chamber, 35 is an etching solution, 36 is a vacuum pump, 3
7 is a valve, 46 is a fitting pin, 49 is a heating unit, 5
Reference numeral 0 denotes a main elevating unit, 51 denotes a thickness sensor, 52 denotes a sensor height adjusting mechanism, 53 denotes a heating case, 53a denotes a positioning pin,
4 is a ring heater, 62 is a sensor holder, 80 is a support ring, 81 is a wafer holder (temporary holding unit), 82 is a position adjusting mechanism (position adjusting unit), 83 is a measuring unit (measuring unit), and 85 is a coil spring. (Elastic member), 86 is an XY table, 87 is a rotary table, 88 is a positioning ring, 8
8a is a positioning pin, 89 is a magnifying camera, 90 is a monitor device, k is a measurement point, and M is a mark (detection position).

Claims (8)

[Claims] 1. An etching pot in which a semiconductor wafer is held in a state of being clamped by two upper and lower clamp members at an outer peripheral edge thereof, and a non-contact type fixedly disposed with respect to the etching pot is used. In an etching apparatus that performs etching while detecting the thickness of the semiconductor wafer by a thickness sensor of the type, a semiconductor wafer clamping apparatus for clamping the semiconductor wafer between the two clamp members in an aligned state, Temporary holding means for holding the semiconductor wafer so as to be position-adjustable in the horizontal direction, between the two clamp members arranged at intervals above and below, and measuring means for measuring the position of the semiconductor wafer with respect to the clamp member, Based on the measurement by the measuring means, the thickness measurement point in the semiconductor wafer is located at the detection position of the thickness sensor. Position adjusting means for adjusting the position of the semiconductor wafer with respect to the clamp member so as to coincide with each other, and fastening means for fastening the two clamp members in a state where the semiconductor wafer is aligned by the position adjusting means. Clamping device for a semiconductor wafer in an etching apparatus. 2. The semiconductor wafer clamp according to claim 1, wherein said position adjusting means is capable of adjusting the position of said semiconductor wafer in the X, Y, and θ directions. apparatus. 3. The temporary holding means holds the semiconductor wafer horizontally and elastically at an intermediate portion between the two clamp members by an upward spring force of an elastic member, and the semiconductor wafer is held by the fastening force by the fastening means. 3. The apparatus for clamping a semiconductor wafer in an etching apparatus according to claim 1, wherein the semiconductor wafer is configured to be lowered against a spring force. 4. The thickness sensor, wherein a plurality of thickness sensors having different detection positions are provided and selectively used, and the thickness adjustment point on the semiconductor wafer is determined by the position adjustment means. 4. The semiconductor wafer clamping device according to claim 1, wherein the positioning is performed so as to coincide with the detection position. 5. An etching pot in which a semiconductor wafer is held in a state of being sandwiched by upper and lower two clamp members at an outer peripheral edge thereof, and a non-contact type fixedly disposed with respect to the etching pot. In an etching apparatus that performs etching while detecting the thickness of the semiconductor wafer by a thickness sensor of the type, a semiconductor wafer clamping method for clamping the semiconductor wafer between the two clamp members in an aligned state, A temporary holding step of holding the semiconductor wafer so as to be position-adjustable in a horizontal direction between the two clamp members arranged at an interval above and below, and measuring by a measuring means for measuring a position of the semiconductor wafer with respect to the clamp member So that the thickness measurement point in the semiconductor wafer coincides with the detection position of the thickness sensor. A method for clamping a semiconductor wafer in an etching apparatus, comprising: a position adjusting step of aligning a semiconductor wafer with respect to the clamp member; and a fastening step of fastening the two clamp members in an aligned state of the semiconductor wafer. . 6. The method for clamping a semiconductor wafer in an etching apparatus according to claim 5, wherein in the position adjusting step, the position of the semiconductor wafer can be adjusted in the X, Y, and θ directions. . 7. In the temporary holding step, the semiconductor wafer is elastically held horizontally at an intermediate portion between the clamp members by an upward spring force of an elastic member, and the semiconductor wafer is held in the fastening step. 6. The semiconductor wafer is lowered against a spring force by a fastening force when the clamping member is fastened.
Or a method for clamping a semiconductor wafer in the etching apparatus according to 6. 8. The thickness sensor, wherein a plurality of thickness sensors having different detection positions are provided and selectively used, and in the position adjustment step, a thickness measurement point in the semiconductor wafer is set to one of 8. The method for clamping a semiconductor wafer in an etching apparatus according to claim 5, wherein the alignment is performed so as to coincide with the detection position.