JPH0439224B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an etching apparatus for semiconductor devices.
In particular, the present invention relates to a semiconductor element etching apparatus suitable for etching a uniform amount without variation only on the outer peripheral end surface of a silicon material of a disk-shaped semiconductor element, and for reliably performing quenching and cleaning after etching.

(Prior Art) A disk-shaped thyristor semiconductor element, as shown in FIG. 4, for example, has an anode electrode 1 mainly made of tungsten material or molybdenum material, an adhesive member 2 mainly made of aluminum material film, and a PNPN layer formed by diffusion. It consists of a silicon material main body portion 3 formed in a four-layer structure, an aluminum film cathode electrode 4, a gate electrode 5, and a surface treatment agent 6 that coats the silicon material outer peripheral end surface 3'.

The electrical characteristics such as withstand voltage and leakage current of the semiconductor element 7 depend on the internal structure of the silicon material main body portion 3, the shape, surface finish, and processing strain of the outer peripheral end surface 3' mainly formed by a polishing machine. It greatly depends on the layer thickness, the adhesion state of impurities, the film thickness of the electrically insulating surface treatment agent 6, the degree of adhesion, etc.

In particular, this type of semiconductor element 7 is used for large voltage and large current control, and is also a product that requires a small leakage current value and high reliability characteristics over a long period of time. must be manufactured to extremely exacting precision and processing conditions.

Now, the processing strain layer generated inside the silicon material outer peripheral end surface 3' formed by a polishing machine etc. is as follows.
It can be removed by etching only the outer peripheral end face 3' of the silicon material.

A conventional method of etching the outer peripheral end surface 3' of a silicon material will be described below with reference to FIGS. 5 to 8.

FIG. 5 is a sectional view of the semiconductor element 7, showing the state of masking of the cathode electrode surface 4 and the gate electrode surface 5 before etching, Nos. 6 to 8.
The figure is a diagram for explaining the etching method of the semiconductor element 7.

Before etching, first, as shown in FIG. ) is applied as a masking coating. The Apiezon wax has the property of not being attacked by acids but being attacked by trichlorethylene.

This method of massing using wax and then etching is known, for example, from JP-A-55
-Disclosed in Publication No. 153338.

Thereafter, as shown in FIG. 6, the semiconductor element 7 is immersed in the etching liquid 9 and is swung up and down. By performing this operation in the tank 15 for a predetermined period of time, immersion etching is performed and the processed strained layer on the outer peripheral end surface portion 3' of the silicon material is removed.

At this time, as a matter of course, the anode electrode surface 1 is also etched at the same time. However, since the Apiezon wax 8 has a property of not being attacked by the etching solution, the cathode electrode surface 4 and the gate electrode surface 5 are not etched.

After etching has been performed in the tank 15 for a predetermined time, the semiconductor element 7 is immersed very quickly (for example, within 0.5 seconds) into the pure water 10 filled in the tank 16 shown in FIG. Perform the quench cleaning operation to stop the etching reaction by shaking it up and down in the same way.

Next, as shown in FIG. 8, the semiconductor element 7 is immersed in the trichlorethylene 11 filled in the tank 17, and is swung up and down for a predetermined period of time to remove the Apiezon wax 8. This completes the etching process of the predetermined silicon material outer peripheral end surface 3'.

(Problems to be Solved by the Invention) All of the above-mentioned work is done manually and has the following problems.

(1) Due to individual differences among workers, variations occur in the vertical swing speed of the semiconductor element 7, the swing stroke length, and the swing/immersion time, making it impossible to obtain a uniform etching amount.

(2) During the immersion etching shown in FIG. 6, the temperature of the etching liquid 9 rises due to the chemical reaction between the semiconductor element 7 and the etching liquid 9.

As a result, when etching is performed one after another,
As the temperature of the etching solution 9 gradually increases,
As the etching liquid 9 deteriorates and the semiconductor elements 7 are introduced later into the etching liquid 9,
There is a risk that variations may occur in the amount of etching.

(3) In the quenching operation shown in Figure 7,
Because immersion quenching is performed in the pure water filled in the tank 16, the amount of water in the tank 16 is small, but
Etching solution remains inside. This remaining etching solution causes impurities to adhere to the semiconductor element, resulting in poor electrical characteristics.

In addition, in the method of quench cleaning by swinging the semiconductor element 7 up and down, the relative flow velocity between the semiconductor element and the etching liquid is weak, so it is difficult to completely remove the etching liquid, and sometimes the outer edge of the silicon is A stain remains on 3', resulting in poor electrical characteristics. As a result, the yield decreases.

(4) The two processes of applying (masking) the Apiezon wax shown in Fig. 5 and removing the Apiezon wax with trichlorethylene shown in Fig. 8 are performed on the outer peripheral end surface of the silicone material, which is the main purpose. These are so-called pre-treatment and post-treatment steps of the etching operation, and are operations that are not directly related to the etching operation. These steps become a factor in reducing productivity.

The purpose of the present invention is to solve the above-mentioned problems.
It is an object of the present invention to provide a highly reliable semiconductor device etching apparatus which can perform masking without applying wax, perform uniform etching, and perform highly clean quenching and cleaning.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a tank having a drain hole formed in its lower part, a drain hole opening/closing means for opening and closing the drain hole, and a drain hole opening/closing means for opening and closing the drain hole, and a drain hole opening/closing means for opening and closing the drain hole. a supported work holder for placing a semiconductor element thereon; a seal member disposed above the work holder for masking the semiconductor element placed on the work holder; and a seal member for masking the semiconductor element placed on the work holder; and a pressing means for pressing the masking part of the semiconductor element placed on the tank, and when the semiconductor element is pressed against the sealing member, the etching liquid is injected into the tank, and after a predetermined amount is injected, the etching liquid is injected into the tank. The etching solution was stirred, and after a predetermined period of time had elapsed and the etching solution was discharged, pure water was injected onto the semiconductor element to quench it, and the inside of the tank was washed with pure water.

(Function) By taking the above measures, it is possible to mask the semiconductor element without applying wax, and the etching work can always be performed under constant conditions without having to be performed manually. This achieves the effect that extremely reliable etching can be performed. Furthermore, the effect that etching can be carried out efficiently is also achieved.

(Embodiment of the Invention) Hereinafter, an embodiment of the present invention will be described based on the drawings of FIGS. 1 to 3.

FIG. 1 is an overall vertical sectional view showing an embodiment of an etching apparatus according to the present invention, and FIG. 2 is an A-A in FIG. 1.
It is an arrow view.

In FIG. 1, a disk-shaped semiconductor element 7
The cathode electrode surface 7 and gate electrode surface 5 of (hereinafter referred to as sample 7) are pressed and sealed by a chemical-resistant rubber ring 202 made of, for example, fluoro rubber, which is fixed to the tip of a cylinder 201.

In this state, the sample 7 is immersed in the etching liquid 300 and rotated by the force of the motor 213, so that the outer peripheral end surface 3' of the silicon material is etched.

Cylindrical tank 101 for filling etching liquid
is fixed on the base 100 with screws.
The bottom portion 130 of the cylindrical tank 101 is formed into a funnel shape so that the etching solution and pure water can be discharged quickly and smoothly.

The drain hole 131 is formed at the lowest part of the bottom portion 130 and is connected to a chemical-resistant solenoid valve 110 that opens and closes in response to a control signal output from the control device 400. A pipe 111 is further connected to the electromagnetic valve 110, and used etching liquid, pure water, etc. are discharged from the pipe 111.

The overflow weir 132 is connected to the cylindrical tank 10
1, and the overflow weir 1
Liquid exceeding 32 is transferred to the overflow pipe 10
It is discharged through 2.

Inside the cylindrical tank 101, a bed 103 is fixed with screws, and the bed 103 has four notches 133 at its bottom in order to instantly drain the liquid.

A chemical-resistant ball 105 (made of fluororesin in this embodiment) is placed on the bed 103,
Furthermore, a work holder 104 having propeller blades 104A for stirring the etching liquid supplied into the cylindrical tank 101 is placed on top of the work holder 104.

The ball 105 is connected to an air cylinder 2 which will be described later.
It has the strength to withstand the seal pressing force of 0.07, and functions as a so-called ball bearing so that the work holder 104 can rotate smoothly.

The cylindrical tank 101 has an etching liquid supply port 106 and a pure water supply port 111 formed therein. As shown in FIG. 2, the etching liquid supply port 106 and the pure water supply port 111 are provided in the tangential direction of the inner wall of the cylindrical tank 101 and in the direction of the sample 7.
It opens into the cylindrical tank 101 so that the etching solution and pure water flow out in the direction of rotation (direction of arrow a).

Further, the etching liquid supply port 106 is connected to the first etching liquid supply port 106.
As shown in the figure, 10 of the propeller blades formed on the bed 103 and the work holder 104
It is formed so that the etching solution can flow out during 4A.

Therefore, the etching liquid flowing out from the etching liquid supply port 106 is transferred to the work holder 104.
Even if it rotates, along the inner wall of the cylindrical tank 101,
It can flow in a state close to a steady flow, and the etching solution does not become drips and scatter when it flows out. As a result, uneven etching and stains do not occur.

The pure water supply port 111 is formed so that pure water can flow out diagonally above the sample 7, and the flowed out pure water flows along the inner wall of the cylindrical tank 101, similar to the etching solution. , it is possible to flow in a state close to a steady state.

The etching apparatus further includes a pure water jet nozzle 115 for quenching to instantly stop the etching reaction when etching is completed, and a nitrogen jet nozzle 118 for draining and drying the sample 7 after cleaning is completed. are doing.

As is clear from FIG. 1, the pure water injection nozzle 115 is arranged so as to be able to eject a jet water stream from diagonally above the sample 7 onto the outer peripheral end surface 3' of the silicon material of the sample 7. .

Next, a pressing mechanism for sealing the sample 7 and a rotation mechanism for rotating the sample 7 will be explained.

The rubber ring 202 that seals the sample 7 is molded from chemical-resistant rubber as described above, and is fitted into a groove formed at the tip of the cylinder 201.

The housings 204 and 206 are assembled to the body 200, and the cylinder 201 is attached to the housing 200.
04 and a slide bearing 205 built into the housing 206.

Air cylinder 207 with relatively small stroke
is the body 200 above the cylinder 201
installed on. The plunger 207A of the air cylinder 207 is connected to the block 22.
1 is connected to the rear end of the cylinder 201.

A gear 211 is formed or fixed on the outer periphery of the cylinder 201. and the gear 21
1 meshes with a gear 212 fixed to the output shaft of a motor 213 fixed to the body 200.

Here, the tooth width of the gear 211 is such that even when the air cylinder 207 operates and the cylinder 201 moves up and down, the gear 211 is
It is set large enough so that it does not deviate from 2.

With this configuration, even when the motor 213 is energized to rotate the cylinder 201, the air cylinder 207 can be operated to move the cylinder 201 up and down. That is, it becomes possible to rotate the sample 7 while pressing it with a predetermined force.

A screw 215 is rotatably supported by bearings 216 and 217 on a wall surface 250 of the etching apparatus. One end of the screw 215 is
It is connected to the output shaft of the motor 220.

The block 214 is screwed into the screw 215 and is fixed to the body 200. The block 214 has a screw 215
By rotating (in the direction of arrow b), it is possible to move up and down (in the direction of arrow c).

Sensors 218 and 219 are connected to block 214.
This is a position detection sensor.

Block 21 fixed to the body 200
4. The screw 215, bearings 216, 217, sensors 218, 219, and motor 220 are removed from the cylindrical tank 101 after the predetermined etching process is completed.
body 20 so that sample 7 inside can be easily taken out.
Constructs a mechanism that moves 0 up and down with a large stroke.

Note that, instead of using these components, this function can also be achieved by using an air cylinder or the like capable of large stroke operation.

The control device 400 is equipped with a control circuit for the etching apparatus, which is mainly a sequence controller.

The control device 400 includes a solenoid valve 110 for draining liquid in the cylindrical tank 101, and an air hose 2.
08 and 209, the air cylinder 20
7 and supplies pressurized air to the air cylinder, a motor 213 that rotates the cylinder 201, a motor 220 that moves the body 200 up and down significantly, and a motor 220 that detects the upper and lower limit positions of the body 200. sensor 218,2
19 are connected.

Furthermore, the control device 400 includes a chemical-resistant solenoid valve 109 connected to the etching liquid supply port 106 through a tube 108 and a tube joint 107 and supplying the etching liquid into the cylindrical tank 101; A solenoid valve 114 is connected to the pure water supply port 111 by a tube joint 112 and supplies pure water for cleaning into the cylindrical tank 101, and a solenoid valve 117 is connected to a pure water injection nozzle 115 for quenching by a tube 116. , and a solenoid valve 12 connected by a tube 119 to a nitrogen injection nozzle 118 for draining and drying.
0 is connected.

The etching processing operation of one embodiment of the present invention having the above configuration is shown in FIGS. 1 and 2 shown above.
This will be explained with reference to FIG.

FIG. 3 is a flowchart showing the operation of one embodiment of the present invention.

It is assumed that before entering the operation shown in FIG. 3, the cylinder 201 and the block 214 (that is, the body 200) are stopped at the upper limit position, and the solenoid valve 110 closes the drain hole 131. shall be taken as a thing.

In this state, the sample 7 is set on the work holder 104 with the cathode electrode surface 4 and the gate electrode surface 5 facing upward. Then, when the operator turns on the switch of the control device 400, the etching process is automatically performed as described below.

First, in step S1, the motor 220 rotates in the forward direction, and the body 200 descends.

Then, in step S2, block 21
When it is determined that the sensor 219 has been turned on by the motor 220, the motor 220 is stopped in step S3.

Next, in step S4, the solenoid valve 210
is opened, the air cylinder 207 is operated, the cylinder 201 is lowered, and the rubber ring 202 presses and seals the cathode electrode surface 4 and the gate electrode surface 5 of the sample 7.

In step S5, the motor 213 rotates the work holder 104 in the same direction as the etching liquid supply direction (direction of arrow a), which will be described later. The work holder 104 supports the pressing force of the sample 7 and the ball 10.
By rotating the sample 5, the sample 7 can be rotated smoothly without slipping. From now on, until further explanation is provided, sample 7 will remain in this sealed and rotating state.

In this press seal and rotating state, step S6
At this time, the solenoid valve 109 is opened, and the etching liquid 300 (mixed acid containing hydrofluoric acid and nitric acid as main components) is supplied from the etching liquid supply port 106 provided in the connection direction of the cylindrical tank 101 along the inner wall of the cylindrical tank 101. is supplied.

Then, in step S7, the solenoid valve 109
is kept open, and the etching liquid 300 is supplied to the vicinity of the overflow weir 132.

After that, in step S8, the solenoid valve 1
09 is closed. Thereafter, the drain solenoid valve 109 remains closed until further explanation is provided.

In addition, as mentioned above, the etching liquid supply port 1
06 is the propeller blade 10 of the work holder 104
4A and the bed 103, and the etching liquid 300 is further supplied along the inner wall of the cylindrical tank 101.

Therefore, the etching liquid 300 is statically filled gradually upward from the bottom of the cylindrical tank 101, and the sample 7 is also gradually immersed in the etching liquid 300 from the bottom. When the etching liquid 300 flows in, the etching liquid does not become a drip and scatter onto the sample 7, so that uneven etching and stains do not occur.

In step S9, this state is maintained until it is determined that the scheduled etching time has elapsed, and the outer peripheral end surface 3' of the silicon material of the sample 7 is etched. During etching, a chemical reaction between the outer peripheral end surface 3' of the silicon material and the etching liquid 300 causes the temperature of the reaction area to rise and the etching liquid 300 to deteriorate.

However, in this embodiment, propeller blades 104A are provided at four locations around the outer periphery of the work holder 104 to stir the etching liquid 300, so that a uniform amount of etching can always be obtained.

When the scheduled etching time has elapsed, the step
At S10, the drain electromagnetic valve 110 having a large-diameter orifice is opened, and the etching liquid 300 is instantly discharged through the notch 133 of the bed 103 and the funnel-shaped bottom 130.

In step S11, the electromagnetic valve 117 is then quickly opened, and pure water is jetted from the pure water injection nozzle 115 toward the outer peripheral end surface 3' of the silicon material of the sample 7, thereby performing a quenching action.

In step S12, the quenching is performed until the scheduled time has elapsed, and then, in step S13, the solenoid valve 114 is also opened. Due to the opening operation of the solenoid valve 114, the cylindrical tank 10 is supplied from the pure water supply port 111 provided in the connection direction of the cylindrical tank 101.
An amount of pure water exceeding the drain amount for cleaning the remaining etching liquid 300 in the cylindrical tank 101 is supplied from the inner wall of the cylindrical tank at an angle, thereby quenching the sample 7 and cleaning the inside of the cylindrical tank 101 at the same time.

When it is determined in step S14 that a predetermined time (approximately 2 to 5 seconds) has elapsed since the solenoid valve 114 was opened, the drain solenoid valve 110 is closed in step S15, and the cylindrical tank is closed. 101 is filled with pure water. A predetermined amount or more of pure water is discharged from the overflow weir 132.

In step S16, when it is determined that the scheduled time has elapsed since the closing operation of the solenoid valve 110,
In step S17, the quench solenoid valve 117 is closed. Thereafter, the sample 7 is washed with pure water continuously supplied from the pure water supply port 111.

This overflow cleaning with pure water is carried out for a predetermined period of time by the preprogrammed control device 400, as will be described later regarding step S18.

What is important here is that in this example,
At the time of quenching, the drain solenoid valve 110 is opened, and the pure water jet nozzle 115 and the pure water supply port 111 supply pure water from diagonally above the sample 7, causing the etching solution to flow downward from above. The so-called downstream cleaning method is used.

In this way, by adopting the flow-down cleaning method, the etching solution adhering to the outer peripheral end surface 3' of the silicon material flows downward instead of going around to the upper part, and at the same time, the trace amount of silicon residue suspended in the etching solution is removed. Since the water is also flowed down, quenching can be performed reliably and at the same time, a high degree of cleaning can be obtained.

In addition, a pure water supply port 111 is installed so that pure water can flow out in the same direction as the rotational direction of the work holder 104, and the pure water flows in a spiral shape in a steady flow inside the cylindrical tank 101. , even higher cleanliness can be achieved.

Furthermore, since the quenching is performed by bombarding the silicon material outer peripheral end surface 3' with pure water at a relatively high speed, that is, a high-energy quenching method is adopted, the quenching can be performed more reliably.

Now, in step S18, it is determined that the scheduled time has elapsed since the solenoid valve 117 was closed, and if the cleaning is completed, the cleaning solenoid valve 114 is closed in step S19.

Then, in step S20, the drain solenoid valve 110 is opened, and the pure water in the cylindrical tank 101 is discharged. Furthermore, in step S21,
The solenoid valve 120 for draining and drying is opened, and nitrogen is jetted from the nitrogen jet nozzle 118 toward the outer peripheral end surface 3' of the silicon material of the sample 7. The sample 7 is dried by this nitrogen jet.

When it is determined in step S22 that the scheduled time has elapsed since the solenoid valve 120 was opened, the draining and drying solenoid valve 120 and the draining solenoid valve 110 are closed in steps S23 and S24.

Next, in step S25, the motor 213
will be stopped.

Then, in step S26, the motor 213
When it is determined that the rotation of the sample 7 has completely stopped, that is, when it is determined that the rotation of the sample 7 has completely stopped, the solenoid valve 210 is closed in step S27, and the cylinder 201 is raised. This cylinder 2
01 rises, the pressure on the sample 7 and the seal are released.

Next, in step S28, the motor 220
rotates in the opposite direction, and the body 200 rises.

Then, in step S29, the body 200
reaches the upper limit position, and the block 214
When it is determined that 8 is turned on, the step
At S30, the motor 220 is stopped.

This completes a series of etching processes by the etching apparatus, and the operator then takes out the sample 7 and proceeds to the next process.

Thus, in accordance with one embodiment of the present invention, a series of etching processes are all performed automatically. Further, it is possible to obtain an extremely stable etching amount and to perform quenching with a high degree of cleaning.

(Effects of the Invention) As is clear from the above description, the following effects are achieved according to the present invention.

(1) A series of etching processing operations are all performed automatically, and the etching solution is stirred during etching, so a uniform amount of etching can always be obtained.

(2) Since the etching solution is replaced each time a sample is etched, the temperature of the etching solution does not change each time an etching process is performed. Therefore, a predetermined amount of etching can always be obtained.

(3) Since quenching is performed by spraying pure water at high speed onto the etched portion of the sample, the quenching process can be performed reliably.

Furthermore, since pure water is flowed out along the inner wall of the tank during the quenching, impurities such as silicon attached to the inner wall of the tank can be removed and the inside of the tank can be cleaned. As a result, the next etching process can be performed reliably.

(4) Since masking is performed by bringing the sealing member placed at the tip of the cylinder into contact with the portion of the sample that does not require etching, the conventional work of applying and removing a masking agent is no longer necessary.

As a result, the etching process can be performed at low cost, and the time required for the etching process is shortened, so that the productivity of semiconductor devices can be improved.

[Brief explanation of drawings]

FIG. 1 is a schematic vertical sectional view of an embodiment of the present invention, FIG. 2 is a view taken along the line A-A in FIG. 1, FIG. 3 is a flow chart showing the operation of an embodiment of the present invention, and FIG. The figure is a partially cutaway sectional view of a disk-shaped thyristor semiconductor element, FIG. 5 is a partially cutaway sectional view of a disk-shaped semiconductor element masked by a conventional method, and FIG.
8 through 8 are diagrams for explaining a conventional etching method for semiconductor elements. 3'...Silicon material outer peripheral end surface, 7...Semiconductor element, 101...Cylindrical tank, 104...Work holder, 104A...Propeller blade, 106...
Etching liquid supply port, 109, 110, 114,
117, 120, 210... Solenoid valve, 111...
Pure water supply port, 115...Pure water injection nozzle, 118
...Nitrogen injection nozzle, 131 ...Drain hole, 20
1...Cylinder, 202...Rubber ring, 207
...Air cylinder, 211,212...Gear, 2
13...Motor, 300...Etching liquid, 40
0...control device.

Claims (1)

[Scope of Claims] 1. A tank having a drain hole formed in its lower part; Drain hole opening/closing means for opening and closing the drain hole; A work holder supported within the tank and for mounting a semiconductor element; a seal member disposed above the work holder for masking a semiconductor element placed on the work holder; and a press for pressing the seal member against a masking portion of the semiconductor element placed on the work holder. etching solution supply means for supplying etching solution into the tank; deionized water supply means supplying deionized water into the tank; water injection means; stirring means for stirring the etching liquid and pure water filled in the tank; and energizing the etching liquid supply means when the semiconductor element is pressed against the sealing member by the pressing means. means for supplying an etching solution; and after the etching solution filled in the tank is discharged from the drain hole, the pure water supply means and the pure water injection means are energized to supply pure water. What is claimed is: 1. An etching apparatus for a semiconductor device, comprising: a means for ejecting the liquid; 2. The stirring means includes a rotating means for rotating at least one of the work holder and the sealing member to rotate the semiconductor element pressed by the sealing member, and a propeller blade formed on the work holder. An etching apparatus for a semiconductor device according to claim 1, characterized in that: 3. The etching apparatus for semiconductor devices according to claim 2, wherein the etching liquid supply means supplies the etching liquid along the inner wall of the tank and in the rotating direction of the propeller blades. . 4. The semiconductor according to claim 2 or 3, wherein the pure water supply means supplies pure water along the inner wall of the tank and in the rotating direction of the propeller blades. Etching device for elements. 5. According to any one of claims 1 to 4, further comprising drying means for drying the semiconductor element after the pure water injection means stops spraying pure water. The semiconductor device etching apparatus described above.