JP2000331982A - Etching device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an etching device which can relatively easily carry out etching treatment, without causing large thickness variation among many semiconductor substrates. SOLUTION: An etching device 10 is provided with a support base 12, a chemical tank 14 for containing an etchant 13 supplied to the substrate 11 held on the base 12, and a control mechanism 14 which controls the supply of the etchant 13 from the tank 14 to the substrate 11 held on the base 12. The control mechanism 14 works to supply the fresh etchant 13 contained in the tank 14 to the substrate 11 at every etching treatment which accompanies the renewal of the substrate 11 held on the base 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching apparatus used for manufacturing a semiconductor device, and more particularly to an etching apparatus suitable for use in etching a semiconductor wafer.

[0002]

2. Description of the Related Art In manufacturing a semiconductor IC device, after a large number of integrated circuit regions are formed on a semiconductor wafer, each integrated circuit region is cut out as a chip from the semiconductor wafer. In order to facilitate handling of the semiconductor wafer during the process of forming the integrated circuit region on the semiconductor wafer, a semiconductor wafer having a thickness exceeding 600 μm is used. After the formation of the integrated circuit area on the semiconductor wafer, the semiconductor wafer is formed, for example, in order to reduce the thickness of the semiconductor wafer so as to be suitable for IC card chips.
It receives mechanical grinding from the back. Further, the semiconductor wafer is subjected to an etching process called a back etch so as to remove damage to the semiconductor back surface due to the mechanical grinding and to obtain a predetermined thickness.

In this back etching, when an etching solution is supplied onto a semiconductor wafer held on a rotating support table with a back surface, which is a ground surface, as an upper surface, the etching solution receives a centrifugal force on the rotating semiconductor wafer. Therefore, the etchant supplied on the semiconductor wafer spreads almost uniformly on the back surface of the semiconductor wafer due to the centrifugal force acting thereon, so that each of the semiconductor wafers exhibits a local variation in the thickness dimension. The substrate is subjected to an etching process so as to have a substantially uniform thickness dimension without causing any problem.

[0004]

However, in the conventional etching apparatus as described above, regardless of the number of replacements of the semiconductor wafer held on the support table, that is, for example, a large number corresponding to the number of sheets of one lot. Irrespective of the number of etching processes, the etching solution circulates between the chemical solution tank containing the etching solution and the support table holding the semiconductor wafer without being replaced.

[0005] The etchant deteriorates as the number of etching processes increases, and the etching rate (etching rate) decreases in accordance with the degree of deterioration of the etchant.
For this reason, in the etching process for one lot of semiconductor wafers, a large difference occurs in the etching rate between the first wafer at the start of etching and the final wafer of the lot, and therefore, the semiconductor wafers in the same lot Large variations occur in the final thickness dimension of

Therefore, in order to prevent variations in the thickness of semiconductor wafers within a lot, attempts have been made to appropriately replenish the main agent of the etching solution into a circulating etching solution chemical tank.

However, between the amount of the main agent added to the etching solution and the change in the etching rate, generally, a non-linear characteristic is seen in which the etching rate changes greatly even when a small amount of the main agent is added. . Therefore, in the above-described prior art in which the thickness of each semiconductor wafer is prevented from being varied by the replenishment of the base material, in order to appropriately maintain the function of the etchant as the etching process proceeds,
During the processing of the lot, it is required to replenish an appropriate amount of a small amount of the main agent successively many times, and it is not easy to appropriately control the amount of the main agent added.

For this reason, there has been a demand for an etching apparatus capable of relatively easily performing an etching process on a semiconductor substrate such as a semiconductor wafer without causing a great variation in the respective thickness dimensions.

[0009]

The present invention adopts the following constitution in order to solve the above points. <Structure> The present invention provides a support base, a chemical tank for containing an etchant supplied to a semiconductor substrate held on the support base, and a supply of the etchant from the chemical tank to the semiconductor substrate on the support base. And a control mechanism for controlling the
The present invention is characterized in that a new etching solution in a chemical solution tank is supplied from the chemical solution tank to the semiconductor substrate by the control mechanism for each etching process involving replacement of the semiconductor substrate on the support table.

<Effect> In the etching apparatus according to the present invention, by the operation of the control mechanism, for each etching process involving replacement of the semiconductor substrate held on the support table,
The etchant is updated. Therefore, the semiconductor substrate can be etched with a new etchant for each etching process without adding the main agent many times even in the etching process for one lot as in the conventional case. It is possible to obtain a semiconductor substrate having a uniform thickness dimension even in the etching process of one lot of semiconductor substrates without performing complicated and delicate control of the amount of additives such as the main agent during the repetition. it can.

[0011] As a chemical solution tank, a first tank containing an etching solution necessary for a predetermined plurality of etching processes and a single tank from the first tank for each etching process by replacing a semiconductor substrate with a support base. And a second tank for receiving a supply of an etching solution required for the etching process. During each etching process of the semiconductor substrate on the support, the etching solution in the second tank is applied to the second tank.
Can be circulated between the tank and the support. Since the etching in the second tank is replaced by the etching solution from the first tank every time the etching process involving the replacement of the semiconductor substrate on the support is changed, the etching rate does not change in each etching process. Absent.

In addition, during the above-described etching process for each semiconductor substrate, the etching solution in the second tank can be circulated between the second tank and the support. The supply amount of the etchant per time or the circulation condition thereof can be appropriately set as necessary, and thereby, it is possible to set a desired etching condition from a wider range of etching conditions.

Further, a waste liquid tank for collecting the etching liquid supplied to the semiconductor substrate can be added to the etching apparatus according to the present invention. The waste liquid tank may be provided with an addition nozzle for replenishing additives such as a main component and an auxiliary component of the etch solution in order to prevent deterioration of the etch solution when the etch solution in the waste solution is reused. it can.

The replenishment of the additive such as the main component or the auxiliary component from the addition nozzle is performed many times, for example, during the processing of one lot with a small amount of addition as in the related art. There is no. That is, for example, 1
During the repetition of the etching process for a lot, the replenishment of the above-mentioned additives is performed collectively prior to reusing the etching solution in the waste liquid tank without replenishing a trace amount of the additive with high precision many times. Done in

Therefore, the required control precision and the number of times of control of the amount of the additive to be added to the etching solution can be reduced. It is possible to easily obtain a semiconductor substrate having a uniform thickness dimension,
Moreover, since the etching solution can be used repeatedly,
Economical etching can be performed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments. <Embodiment 1> FIG. 1 schematically shows an etching apparatus of Embodiment 1. As shown in FIG. 1, an etching apparatus 10 according to the present invention includes, as shown in FIG. 1, a support table 12 on which a semiconductor wafer 11 made of, for example, a silicon crystal substrate is disposed with its back side 11a subjected to mechanical grinding facing upward, Liquid 13
And a conduit 15 extending above the support 12 from the chemical tank 14 to guide the etching liquid 13 in the chemical tank 14 to the semiconductor wafer 11 on the support 12, and via the conduit It includes a pressure pump 16 such as a bellows pump for supplying the etching liquid 13 onto the semiconductor wafer 11 and a control mechanism 17 for controlling the operation of the pressure pump.

The conduit 15 is provided with a liquid temperature controller 18 for controlling the temperature of the etching liquid 13 supplied onto the semiconductor wafer 11. By the operation of the pressurizing pump 16 controlled by the control mechanism 17, the etching liquid 13 in the chemical tank 14 is heated to an appropriate temperature by a liquid temperature controller 18 provided in the pipe line 15, and It is pressure-fed to the semiconductor wafer 11 on the support 12 via the path 15.

The support table 12 is provided with a claw 19 for holding the semiconductor wafer 11, and the semiconductor wafer 11 held by the claw is driven by a unidirectional drive rotation about a rotation axis 12 a of the support table 12. , And are integrally rotated with the support table 12. The etching solution 13 pressure-fed from the chemical solution tank 14 through the conduit 15 is used for the back surface 1 of the rotating semiconductor wafer 11.
It flows down sequentially on 1a. The etchant flowing down on the semiconductor wafer 11 receives a centrifugal force on the back surface 11 a of the rotating semiconductor wafer 11. The etchant flowing down on the back surface 11a of the semiconductor wafer 11 spreads almost uniformly on the back surface 11a of the semiconductor wafer due to the centrifugal force acting on the etchant. And is subjected to an etching process so as to have a substantially uniform thickness dimension without showing the following.

A well-known annular liquid receiver 20 is provided around the edge of the support base 12. The etchant 13 flowing down on the semiconductor wafer 11 is supplied to the liquid receiver 2.
In the illustrated example, a waste liquid tank 22 for collecting the discarded etching liquid is connected to the liquid receiver 20 via a drain pipe 21. In addition, in order to reuse the used etching liquid in the waste liquid tank 22, a transfer pump 23 for returning the etching liquid in the waste liquid tank 22 to the chemical liquid tank 14 is provided in the illustrated example.

The transfer pump 23 is controlled by the control mechanism 17 and normally shuts off the waste liquid tank 22 and the chemical liquid tank 14. The transfer pump 23 keeps both tanks 22 and 14 in communication only when the etching solution in the waste liquid tank 22 is returned to the chemical solution tank 14 in order to reuse the used etching solution in the waste liquid tank 22. It operates to pump the etchant from the tank 22 to the chemical tank 14.

When the semiconductor wafer 11 is a silicon crystal substrate, for example, a nitric hydrofluoric acid-based etching solution containing hydrofluoric acid as a main component and nitric acid as an auxiliary agent can be used as an etching solution. The chemical solution tank 14 contains, for example, a new etching solution 13 in an amount necessary for the etching process for one lot. For example, for one lot, 25
When the semiconductor wafers 11 are sequentially replaced one by one, and an Ncc etching solution is required for the etching process of each semiconductor wafer 11, the chemical solution tank 14 contains at least 25 × Ncc etching solution 13. You. The transfer pump 23 keeps both tanks 14 and 22 shut off in order to prevent the etching liquid from returning from the waste liquid tank 22 to the chemical liquid tank 14.

The semiconductor wafer 11 on the support 12 is the support 1
As described above, when the rotation of the pressurizing pump 16 controlled by the control mechanism 17 is started,
An etching solution 13 in an amount (Ncc) necessary for each etching process is sequentially supplied from the pipe 15 onto the semiconductor wafer 11 by flowing down. The etchant (Ncc) sequentially flowing down on the semiconductor wafer 11 is collected in the waste liquid tank 22 through the drain tube 21 after performing an appropriate etching process on the back surface 11a of the semiconductor wafer 11 as described above.

The required amount (Ncc) of the etchant 13
When the above-mentioned predetermined etching process on the semiconductor wafer 11 is completed by the supply of the semiconductor wafer 11, the semiconductor wafer 11 on the support base 12 is replaced with a new one. After the replacement with the new semiconductor wafer 11, the amount of the etching solution 13 (Ncc) necessary for the etching process of the new semiconductor wafer 11 is supplied to the pressure pump 1 in the same manner as described above.
6, the liquid is supplied onto the semiconductor wafer 11, and after the semiconductor wafer 11 is etched, the waste liquid tank 22 is supplied.
Will be collected.

Hereinafter, when the above-described steps are repeated for etching the semiconductor wafer 11 for one lot,
Almost all the etching liquid 13 in the chemical liquid tank 14 is collected in the waste liquid tank 22.

The amount (Ncc) required for one etching process in the above-described etching process, the required amount (Nc)
The operating conditions such as the required etching time required to complete the supply of c) and the number of rotations of the support base 12 are appropriately selected according to the etching ability of the etching solution 13, and the etching apparatus 1
Prior to the operation of 0, it is set in advance so as to be appropriate.

In the etching apparatus 10 according to the present invention, as described above, a new etching solution 13 in the chemical solution tank 14 is supplied onto the semiconductor wafer 11 on the support 12 every time the semiconductor wafer 11 is etched. Therefore, the semiconductor wafer 11 mounted on the support 12
Is a new etching solution 13 from the chemical solution tank 14
That is, an etching solution 1 having a predetermined etching ability
3 undergoes an etching process.

Therefore, even if the etching process is performed on one lot of semiconductor wafers 11 such as 25 wafers, the semiconductor wafer 11 has the same processing ability from the first wafer of the lot to the last wafer of the lot. Undergoes an etching process. As a result, even when etching a large amount of semiconductor wafers 11 for one lot, variation does not occur for each semiconductor wafer 11,
The semiconductor wafer 11 having a uniform thickness dimension can be obtained.

The etching liquid in the waste liquid tank 22 is deteriorated by one etching process. The deteriorated etching liquid in the waste liquid tank 22 is returned to the chemical liquid tank 14 by the operation of the transfer pump 23, and the returned etching liquid can be used again in the chemical liquid tank 14 for the same etching treatment as described above. . At this time, it is desirable to appropriately change the operating conditions of the etching apparatus 10 so as to obtain a predetermined etching effect according to the above-described deterioration of the etching solution 13.

When the etching liquid 13 is reused as described above, instead of changing the operating conditions, for example, an addition nozzle 24 for adding the main agent into the waste liquid tank 22 is used.
a and an addition nozzle 24b for adding the auxiliary agent
Can be provided. By adding appropriate amounts of, for example, 50% hydrofluoric acid and 80% nitric acid or more nitric acid from the two nozzles 24a and 24b, the etching solution 13 can be given the initial etching ability, thereby being substantially the same as the initial one. It is possible to perform the etching process on a large number of lots under the above operating conditions.

The addition of the above-described additive is not a small number of additions that are performed many times during the etching process for one lot as in the prior art.
2 for a large amount of etching solution.
Therefore, the delicate control as in the related art is not required for the addition of the additive, so that the additive can be added relatively easily, accurately, and appropriately.

The addition nozzle provided in the waste liquid tank 22 may be any one of the above-mentioned main agent and the above-mentioned auxiliary agent as required. Addition nozzles (24a and 24b, 24a or 24b)
Can be provided in the chemical liquid tank 14 instead of the waste liquid tank 22.

<Example 2> In Example 1, the chemical tank 1
4 and the waste tank 22 were arranged in series with respect to the support 12. FIG. 2 shows an example in which the chemical liquid tank 14 and the waste liquid tank 22 are arranged in parallel with respect to the support base 12.

A pair of tubes 21a and 21b extend from opposite sides of the liquid receiver 20 of the support base 12 to each other. Each tube 21
Opening and closing valve mechanisms 25a and 25b controlled by the control mechanism 17 to open and close the respective pipelines are provided at a and 21b, respectively. The chemical liquid tank 14 is connected to one pipe 21a, and the waste liquid tank 22 is connected to the other pipe 21b.

From the chemical solution tank 14, a pipe 15a extends. The end of the pipe 15a is connected to a pipe 15b provided with the same pressure pump 16 and liquid temperature controller 18 as described above.
Are connected via a switching valve mechanism 26. Further, from the waste liquid tank 22, a pipe 15c extends. 1
The tip of 5c is connected to the switching valve mechanism 26. The switching valve mechanism 26 receives the control of the control mechanism 17, and selectively connects the pipe 15b to the pipe 15a or the pipe 15c.

As in the case of the chemical solution tank 14 in the first embodiment, the chemical solution tank 14 stores, for example, a new etching solution 13 in an amount necessary for etching processing for one lot.
Further, one open / close valve mechanism 25a provided in connection with the pipe 21a of the chemical liquid tank 14 is closed, and the other open / close valve mechanism 25b provided in connection with the pipe 21b of the waste liquid tank 22 is opened. Put in.

The switching valve mechanism 26 connects the pipe 15b to the pipe 1
When the pressurizing pump 16 is operated by the control mechanism 17 in a state of being selectively connected to the etching solution 5a, an etching solution 13 of an amount (Ncc) necessary for one etching process is supplied to the chemical solution tank 14.
Through the conduits 15a and 15b, and on the semiconductor wafer 11 which rotates integrally with the support table 12 as described above,
By flowing down, they are sequentially supplied. Further, the semiconductor wafer 11
As described above, the etching solution (Ncc) that has flowed upward is subjected to an appropriate etching process on the back surface 11a of the semiconductor wafer 11, and then collected in the waste liquid tank 22 through the pipe 21b.

Hereinafter, when the above-described steps are repeated for etching the semiconductor wafer 11 for one lot,
Almost all the etching liquid 13 in the chemical liquid tank 14 is collected in the waste liquid tank 22. In the etching apparatus 10 of the specific example 2, the etching 13 in the waste liquid tank 22 can be supplied again from the waste liquid tank 22 to the semiconductor wafer 11 on the support table 12 without returning to the chemical liquid tank 14. The tank 14 can be used as a waste liquid tank for waste liquid.

That is, when almost all the etching liquid 13 in the chemical liquid tank 14 is collected in the waste liquid tank 22,
One open / close valve mechanism 25a provided in connection with the chemical liquid tank 14 is in an open state, and the other open / close valve mechanism 25b provided in connection with the waste liquid tank 22 is in a closed state. Further, by the operation of the switching valve mechanism 26,
Since the pipe 15b is connected to the pipe 15c instead of the pipe 15a, the pipe 15b is communicated with the waste liquid tank 22 instead of the chemical liquid tank 14.

Therefore, when the pressurizing pump 16 is operated in the same manner as described above under the control of the control mechanism 17, the etching solution in the waste liquid tank 22 is supplied onto the semiconductor wafer 11 via the conduit 15b. Further, the etching solution supplied onto the semiconductor wafer 11 passes through the pipe 21a and passes through the chemical solution tank 1.
Returned to 4. Therefore, the chemical liquid tank 14 functions as a waste liquid tank, and the waste liquid tank 22 functions as a chemical liquid tank. The aforementioned function of each tank 14 and 22 is based on the
3 alternately moves each time it moves to the other tank 22 or 14.

The deterioration of the etchant progresses each time the function is changed, so that it is desirable to appropriately correct the above-described operating conditions of the etching apparatus 10 in order to obtain a predetermined etching process each time. Also, in order to keep the operating conditions constant, the chemical solution tank 14
And either or one of the waste liquid tanks 22,
Addition nozzles (24a and 24b, 2
4a or 24b) can be provided.

<Embodiment 3> FIG. 3 shows an example in which a chemical tank 14 is composed of a first tank 14a and a second tank 14b which are connected in series with each other. The first tank 14a
In the same manner as in the chemical liquid tank 14, for example, a new etching liquid 13 in an amount necessary for etching one lot of the semiconductor wafer 11 is stored. The etching liquid 13 in the first tank 14a passes through a fixed amount pump 27 which is controlled by the operation of the control mechanism 17, and a fixed amount of, for example, 1 to 2 liters as one etching process is supplied to the second tank 14b. Sent to

The predetermined amount of the etching solution 13a sent to the second tank 14b flows down to the semiconductor wafer 11 on the support base 12 through the pipe 15 by the operation of the pressure pump 16. The etching solution 13 a flowing down onto the semiconductor wafer 11 passes through the drain tube 21 from the solution receiver 20,
It is returned to the second tank 14b again, but the circulation of the support base 12, the drain pipe 21 and the second tank 14b is formed via the pipe 15, so that the operation of the pressurizing pump 16 continues. As long as possible, the semiconductor wafer 11 on the support table 12 and the second tank 14b are circulated through the conduit 15.

When the etching of the semiconductor wafer 11 on the support 12 is completed by the predetermined circulation of the etching solution 13a through the circulation path, the operation of the pressure pump 16 is stopped, and the etching in the second tank 14b is stopped. The liquid 13a is
The liquid is pumped to the waste liquid tank 22 by the operation of the transfer pump 28 under the control of the control mechanism 17.

When the inside of the second tank 14b is emptied by the pressure supply of the etching solution 13a to the waste tank 22, the operation of the metering pump 27 causes the new etching solution 13a of the predetermined amount to be supplied from the first tank 14a to the second tank 14a. The tank 14b
The etching liquid 13a in the second tank 14b is thereby replaced with a new one. The new etching liquid 13a in the second tank 14b is used for the etching of the new semiconductor wafer 11 replaced by the support table 12, and the same pressure pump 1 as described above is used.
6, the pipe 15, the support 12, and the drain pipe 2
It flows through a circulation path around the first and second tanks 14b.

Thereafter, by repeating the same steps as described above, for example, one lot of semiconductor wafers 11 are subjected to an etching process with an etching solution 13a updated for each semiconductor wafer 11. Therefore, even in the etching process of the semiconductor wafer 11 for one lot, the semiconductor wafer 11 is processed from the first wafer of the lot to the last wafer of the lot.
Since the semiconductor wafer 11 is subjected to an etching process using an etchant having the same processing capability, it is possible to obtain the semiconductor wafer 11 having a uniform thickness dimension without causing variations among the semiconductor wafers 11.

The used etching liquid 13 collected in the waste liquid tank 22 is returned to the first tank 14a by the operation of the transfer pump 23, and can be reused.
Further, in order to reuse the etching solution 13, the same addition nozzle (24a and 24b, 24a or 24a) as described above is provided in the first tank 14a or the waste liquid tank 22.
b) is provided, and an additive can be added to the etching solution 13 as needed.

Further, in the etching apparatus 10 of the third embodiment, the renewed fixed amount of the etching solution 13a in the second tank 14b is supplied to the circulation paths (15, 12, 21 and 14b) each time the etching process is performed. ). for that reason,
The amount of circulation or the number of circulations per unit time around the circulation path is not restricted to a fixed amount, and the pressure pump 16
Can be set relatively freely. Therefore, each time the etching solution 13 is reused, the thickness or the number of circulations per unit time is appropriately increased, so that the thickness becomes substantially uniform across many lots without adding an additive. As described above, the etching process can be performed on the semiconductor wafer 11 relatively easily.

As described above, as the semiconductor substrate,
Although the example of the semiconductor wafer on which the integrated circuit region is formed has been described, the present invention is not limited to the semiconductor wafer and can be applied to various semiconductor substrate etching processes.
In the above description, a nitric hydrofluoric acid-based etchant containing hydrofluoric acid as a main component and nitric acid as an auxiliary has been described. However, the present invention is not limited thereto. For example, various etching liquids can be used.

[0049]

According to the present invention, as described above, the etchant is renewed for each etching process involving replacement of the semiconductor substrate held on the support table, so that the additive such as the base agent is renewed. A semiconductor substrate having a uniform thickness can be obtained even in the etching processing of one lot of semiconductor substrates without controlling the amount of addition of the semiconductor substrate.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically showing Example 1 of an etching apparatus according to the present invention.

FIG. 2 is a configuration diagram schematically showing a specific example 2 of the etching apparatus according to the present invention.

FIG. 3 is a configuration diagram schematically showing Example 3 of the etching apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Etching apparatus 11 Semiconductor substrate (semiconductor wafer) 12 Support stand 13 Etching liquid 14 (14a, 14b) Chemical tank 17 Control mechanism

Claims (3)

[Claims] 1. A support, a chemical solution tank containing an etchant supplied to a semiconductor substrate held on the support, and a supply of the etchant from the chemical tank to the semiconductor substrate on the support. A control mechanism for controlling the operation of supplying a new etching solution in the chemical solution tank from the chemical solution tank to the semiconductor substrate for each etching process involving replacement of the semiconductor substrate on the support base. An etching apparatus including: 2. The method according to claim 1, wherein the chemical solution tank includes a first tank that stores an etchant necessary for a plurality of predetermined etching processes, and the etching process performed by replacing the semiconductor substrate with the support table. A second tank that receives a supply of an etching solution in an amount necessary for one etching process from one tank, and wherein the etching in the second tank is performed during each etching process of the semiconductor substrate on the support table. Liquid is circulated between the second tank and the support,
2. The etching apparatus according to claim 1, wherein the etching solution in the second tank is replaced with an etching solution from the first tank every time an etching process involving replacement of the semiconductor substrate on the support table is performed. 3. A waste liquid tank for recovering the etching liquid supplied to the semiconductor substrate, wherein the waste liquid tank is provided for preventing deterioration of the etching liquid when the etching liquid in the waste liquid is reused. 2. The etching apparatus according to claim 1, further comprising an addition nozzle for replenishing at least one of a main component and an auxiliary component of the etching solution.