JP3366449B2 - Etching equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching apparatus, and more particularly to an etching apparatus capable of obtaining a stable mesa shape in mesa etching of a mesa diode.

[0002]

2. Description of the Related Art A manufacturing process of a mesa type diode includes an etching process of directly immersing a semiconductor wafer having tens to hundreds of diode elements before division into a chemical to form a mesa shape. Be done. This etching step is an important step that determines the characteristics of the mesa diode, and it is necessary to control the etching precisely. Since precise control of etching is achieved by keeping the temperature of the etching solution constant, various etching apparatuses have been proposed to realize this.

A conventional etching apparatus will be described with reference to FIGS. The etching apparatus shown in FIG. 3 indirectly controls the temperature of the etching liquid in the etching tank. The etching tank 1 is composed of an inner tank 1a filled with the etching liquid and an outer tank 1b filled with a cooling liquid. ing. The cooling liquid is circulated between the outer tank 1b and the heat exchanger 3 by the pump 2. The semiconductor wafer 4 is etched by placing a plurality of semiconductor wafers 4 on a wafer carrier 5 and immersing the wafer carrier 5 in an etching solution in an inner tank 1a whose temperature is controlled by circulating a cooling solution and rocking the wafer carrier 5 up and down. It is done by letting.

Next, the etching apparatus shown in FIG. 4 directly controls the temperature of the etching solution. This apparatus comprises an etching tank 1 filled with an etching solution, a pump 2 and a heat exchanger 3. The etching liquid is circulated between the etching tank 1 and the heat exchanger 3 by the pump 2. The etching process of the semiconductor wafer 4 is performed by placing a plurality of semiconductor wafers 4 on the wafer carrier 5, immersing the wafer carrier 5 in the etching solution in the etching tank 1, and rocking the wafer carrier 5 up and down. At this time, the temperature of the etching liquid is directly controlled by the heat exchanger 3.

[0005]

However, in the apparatus shown in FIG. 3, a considerable amount of time is required because the temperature of the etching solution is indirectly controlled via the cooling liquid 2. However, there is a problem that the etching process takes a long time. Further, even when the temperature of the etching solution is raised by the reaction heat generated during the etching process, there is a problem that the temperature does not quickly return to the predetermined temperature and the etching varies so that a stable mesa shape is not formed.

Further, in the apparatus shown in FIG. 4, the temperature of the etching solution is directly controlled, but the temperature in the vicinity of the semiconductor wafer 4 where the reaction heat is generated cannot be reliably controlled depending on the flow of the circulating etching solution. As a result, there is a problem in that the etching varies and the stable mesa shape is not formed, as in the case described above. The present invention has been made in view of the above problems, and an object thereof is to provide an etching apparatus that can make the temperature distribution constant and can make the flow of the etching liquid uniform.

[0007]

The present invention has the following constitution in order to achieve the above object. That is, the etching apparatus according to claim 1, wherein the etching bath is filled with the etching liquid and the semiconductor wafer is dipped therein, a supply pipe provided in the etching bath and having an outflow hole for the etching liquid, and overflowing from the etching bath. A collection tank for collecting the etching solution, a pump for circulating the etching solution in the collection tank to the etching tank through a supply pipe, and a temperature control of the etching solution circulating between the collection tank and the supply pipe are performed. An etching apparatus comprising a heat exchanger, wherein the supply pipe is branched at a tip end thereof in a comb shape and a plurality of the heat exchangers are connected in parallel, and each heat exchanger is for adjusting a flow rate. The valve is provided.

An etching apparatus according to a second aspect is the etching apparatus according to the first aspect, wherein the pump is a rotary pump. According to a third aspect of the present invention, in the etching apparatus according to the first or second aspect, the outflow hole of the supply pipe is directed to the bottom surface of the etching tank.

[0009]

In the etching apparatus of the present invention, the bottom end of the supply pipe is comb-shaped, and the etching liquid supply portions are provided at a plurality of positions in the etching tank to etch the etching liquid flow. The temperature distribution is made uniform by making it uniform in the tank.

Further, by connecting a plurality of heat exchangers in parallel, the change in the flow rate of the etching solution sent to the heat exchanger is reduced to improve the heat exchange rate, and the etching solution having a stable temperature is etched. Can be supplied to. Further, since the pump for circulating the etching solution is a rotary pump, the etching solution does not have a pulsating flow, and the etching solution can be always sent to the heat exchanger at a constant flow rate. As a result, it is possible to improve the heat exchange rate and stabilize the flow of the etching solution flowing out from the supply pipe.

Further, since the turbulent flow is caused in the etching liquid by directing the outflow hole of the supply pipe toward the bottom of the etching tank, the flow of the etching liquid becomes uniform.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. Incidentally, the same reference numerals are given to the same or corresponding portions as in the conventional case. The etching apparatus of the present invention is provided with an etching tank 1 in which a semiconductor wafer 4 is immersed while being filled with an etching solution, and provided in the etching tank 1.
A supply pipe 7 having an etching solution outflow hole and a tip end thereof branched in a comb shape, a recovery tank 6 for recovering the etching solution overflowed from the etching tank 1, and a supply tube for the etching solution in the recovery tank 6. Etching tank 1 through 7
And a plurality of heat exchangers 3 connected in parallel in order to control the temperature of the etching liquid circulating between the recovery tank 6 and the supply pipe 7.

Then, the recovery tank 6, the pump 2, the heat exchanger 3
The supply pipe 7 is connected by a pipe 9 to form a circulation path. In this circulation path, valves 21 to 26 for adjusting the flow rate of the etching liquid and discharging it are provided.
In addition, a thermocouple 10 is provided in the etching bath 1 to measure the temperature of the etching solution.

Since the above-mentioned etching apparatus carries out the etching process of the semiconductor by using an etching solution having a high temperature and a high concentration, all the portions which come into contact with the etching solution are made of a material having corrosion resistance, such as a fluorine resin ( (Teflon etc.)
Is used. Next, each component of the etching apparatus of the present invention will be described. The etching tank 1 and the recovery tank 6 are
The tank is made of a material having corrosion resistance, and the size of the tank is appropriately selected depending on the number of semiconductor wafers 4 to be etched.

The supply pipe 7 for supplying the etching solution to the etching bath 1 is also made of a material having corrosion resistance. As shown in FIG. 2 (a), this supply pipe 7 has a bottomed tip end branched into a comb tooth shape, and an outflow hole 1 described later.
The etching liquid circulating in the etching tank 1 is uniformly supplied via the nozzle 1. In the present embodiment, the supply pipe 7 whose tip portion is branched into three has been described, but it may be branched into a plurality of pipes. In this case, the branched portion may be inside or outside the etching tank 1. Further, as shown in the cross-sectional view of FIG. 2B, the outflow hole 1 for outflowing the etching solution is formed.
1s are provided in pairs in a downward direction by about 30 ° with respect to the horizontal direction of the axis. And, in the supply pipe 7,
A plurality of sets of the two outflow holes 11 are provided at a predetermined interval in the axial direction. Since the outflow hole 11 is directed toward the bottom of the etching tank 1 in this manner, the etching liquid becomes a turbulent flow at the bottom of the etching tank 1 and becomes a uniform flow in the ascending process.

Next, the pump 2 may be a pump of a type which sends out the etching solution by a piston motion, but by using a rotary pump, the pulsating flow can be suppressed and the heat exchange rate of the heat exchanger 3 is improved. It is possible to suppress variations in the flow of the etching liquid that flows out from the supply pipe 7. A plurality of heat exchangers 3 for controlling the temperature of the circulating etching solution are connected in parallel, and a flow meter 8 is provided for each of them. Then, the change in the flow rate of the etching liquid passing through the heat exchanger 3 is reduced to improve the heat exchange rate. Although the case where two units are connected in parallel has been described in the present embodiment, the number of units may be increased according to the flow rate of the etching solution that flows.

Finally, a plurality of thermocouples 10 are installed in the etching tank 1 at predetermined intervals. in this way,
By installing the thermocouples 10 at a plurality of locations in the etching tank 1 and detecting the temperature difference between the thermocouples 10, it becomes possible to detect an abnormality in the etching apparatus at an early stage. Twenty-five or fifty semiconductor wafers 4 to be etched are placed on the wafer carrier 5 so that the semiconductor wafers 4 can be processed in lot units, and the wafers are set on a swinging device (not shown). By driving this rocking device, the wafer carrier 5 rocks up and down. The wafer carrier 5 may be set automatically or manually.

Next, the operation of the etching apparatus of the present invention will be described. First, the valves 21 and 25 are closed, and the valves 22 and 2 are
3, 24 are opened, the etching solution is supplied to the etching tank 1 to fill the etching tank 1, and the etching solution is further supplied to overflow into the recovery tank 6. Then, after driving the pump 2 and the heat exchanger 3, the valves 22 and 23 are adjusted while checking the flowmeter 8 to make the flow rate of the etching liquid flowing into the heat exchanger 3 constant. As a result, the etching solution circulates in the path of the etching tank 1, the recovery tank 6, the pump 2, the heat exchanger 3, the supply pipe 7, and the etching tank 1.

The etching solution is controlled to a predetermined temperature by the heat exchanger 3 while circulating in this path, and
A turbulent flow is generated by the supply pipe 7, and a uniform flow is supplied to the etching tank 1. The semiconductor wafer 4 is etched by the plurality of semiconductor wafers 4 being a wafer carrier 5.
The wafer carrier 5 is immersed in the etching tank 1, and the wafer carrier 5 is vertically rocked by a rocking device (not shown) for a certain period of time to perform etching. Since the etching liquid is agitated by the swinging of the wafer carrier 5, the temperature distribution in the etching tank 1 can be made more uniform.

Next, the role of the valves 21, 24, 25 and 26 will be described. When an abnormality occurs in the etching apparatus as a whole, the etching solution is replaced with water to prevent danger, and the valve 21 is used as a valve for discharging the water. When an abnormality occurs in the pump 2, the valves 21, 22, 24 are closed and the valve 25 is opened.
The etching liquid between 22 is drained, and the pump 2 is replaced and repaired. That is, the valve 24 is for shutting off the etching solution,
The valve 25 is used for discharge.

Further, the valve 26 is used for discharging the etching liquid of the entire etching apparatus. In this embodiment, the target of etching is the semiconductor wafer for manufacturing the mesa type diode, but there is no problem even if the target of etching is a semiconductor wafer for manufacturing other semiconductor devices.

[0022]

As described above, in the etching apparatus of the present invention, the temperature of the etching solution can be controlled accurately and the flow thereof can be made uniform, so that the temperature distribution in the etching tank can be made uniform. As a result, it is possible to significantly suppress variations in etching, and it is possible to perform etching processing with good reproducibility.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of the present invention.

FIG. 2 is an explanatory view showing a supply pipe of the present invention.

FIG. 3 is an explanatory view showing a conventional etching apparatus.

FIG. 4 is an explanatory view showing a conventional etching apparatus.

[Explanation of symbols]

1 etching tank 2 pumps 3 heat exchanger 4 Semiconductor wafer 5 Wafer carrier 6 collection tanks 7 supply pipe 8 flow meter 9 piping 10 thermocouple 11 Outflow hole 21 to 26 valves

Continuation of the front page (56) References JP-A-4-256318 (JP, A) JP-A-59-96735 (JP, A) Actual development 1-122814 (JP, U) (58) Fields investigated (Int .Cl. ⁷ , DB name) H01L 21/306

Claims (3)

(57) [Claims] 1. An etching tank filled with an etching solution and into which a semiconductor wafer is immersed, a supply pipe provided in the etching tank and having an outflow hole for the etching solution, and an etching solution overflowing from the etching tank. It consists of a recovery tank, a pump that circulates the etching solution in the recovery tank to the etching tank through a supply pipe, and a heat exchanger that controls the temperature of the etching solution that circulates between the recovery tank and the supply tube. In the etching apparatus, the tip of the supply pipe is branched in a comb shape, a plurality of the heat exchangers are connected in parallel, and each heat exchanger is provided with a valve for adjusting a flow rate. An etching apparatus characterized by the above. 2. The etching apparatus according to claim 1, wherein the pump is a rotary pump. 3. The etching apparatus according to claim 1, wherein the outflow hole of the supply pipe is directed to the bottom surface of the etching tank.