JPH036824A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To accurately form a recess of a semiconductor wafer by aligning the wafer to be formed with the recess, and an etching end detecting chip formed in advance in thickness coincident with the depth of the recess, and then simultaneously etching the wafer and the chip. CONSTITUTION:A semiconductor wafer 1 to be formed with a recess 2 having a predetermined depth (d) and an etching end detecting chip 10 formed in thickness T coincident with the depth (d) of the recess 2 are prepared, the wafer 1 formed with resist coating patterns 3, 11 and the chip 10 are aligned in parallel, and then dipped in etchant 5 filled in an etching tank 4. An operator observes the etching proceeding state through the depth of the recess 12 formed on the chip 10, and when the etching work is finished when the recess 12 is passed, the recess 2 of the depth (d) coincident with the thickness T of the chip 10 is indispensably formed on the wafer 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of forming recesses of a required depth in a semiconductor wafer by etching.

C. Conventional Technology] Conventionally, when manufacturing semiconductor devices used as pressure sensors, acceleration sensors, etc., the methods shown in FIGS.
), a method is adopted in which a recess 2 of a required depth d is formed on the surface 1a of the semiconductor wafer 1 by etching.

In this method, it is important to accurately ensure the thickness t of the etched portion between the back surface 1b of the semiconductor wafer l and the bottom surface 2a of the recess 2, which will become a diaphragm portion of a pressure sensor or the like.

That is, in this method, first, as shown in FIG. 3(a), a resist film pattern 3 serving as an etching mask is formed on the surface la of the semiconductor wafer 1 on which the recess 2 is to be formed, and then this semiconductor The wafer 1 is immersed in an etching solution 5 filled in an etching tank 4. Note that the back surface 1b of this semiconductor wafer 1 is protected by a nitride film, plating film, etc. formed in advance.

If the semiconductor wafer 1 is left immersed in the etching solution 5, the portions of the semiconductor wafer l that are not covered with the resist film pattern 3 will be etched by the etching solution 5, and the recesses 2 will gradually become smaller. is formed. Therefore, as shown in FIG. 3(b), when the recess 2 reaches a certain depth after a predetermined period of time has elapsed, the semiconductor wafer 1 is lifted out of the etching solution 5, and then a dial gauge or the like is used. The depth d of the recess 2a is
] is measured, and by subtracting this measured value d1 from the required depth d of the recess 2 to be formed, the depth d2 (=d-di) to be further etched is calculated.

Thereafter, as shown in FIG. 3(c), this semiconductor wafer l is immersed in the etching mask again, and etching is performed to the required depth d2 by controlling the immersion time. After the etching period has elapsed, when the semiconductor wafer 1 is pulled up from the etching solution 5, a recess 2 with a required depth d has been formed in the semiconductor wafer 1. Therefore, the thickness t between the bottom surface 2a of the recess 2 formed in this way and the back surface 1b of the semiconductor wafer l is
The remaining etched portion will be used as a diaphragm portion of a pressure sensor or the like.

[Problem to be solved by the invention]

However, in the conventional method, the semiconductor wafer 1 has to be etched twice, which increases the time and effort required for the etching process and reduces production efficiency.

Furthermore, when measuring the depth dl of the recess 2 formed in the semiconductor wafer 1, the etching force (advancing force) caused by the etching liquid adhering to the inner surface of the recess 2 causes a decrease in etching accuracy. As a result of not being able to form the recessed portion 2 with high precision, a disadvantage arises in that the thickness t of the remaining etched portion cannot be accurately ensured.

This invention was devised in view of these inconveniences, and while improving production efficiency, it is possible to form the four parts with high precision, and to ensure the thickness of the remaining part to be etched accurately. The purpose is to provide a method for manufacturing a semiconductor device.

[Means to solve the problem]

This invention provides a method for manufacturing a semiconductor device in which a concave portion of a required depth is formed by etching a semiconductor wafer, in which the semiconductor wafer in which the concave portion is to be formed is formed in advance to a thickness that matches the depth of the concave portion. [Operation] According to the above method, the semiconductor wafer and the etching completion detection chip are arranged in parallel, and the wafer and the chip are etched at the same time. Since etching will be performed simultaneously, the progress of etching should be observed through the depth of the recess formed in the etching end detection chip.
If the etching operation is terminated when the recess penetrates through, the semiconductor wafer will inevitably have a recess with a required depth that corresponds to the thickness of the chip for detecting the completion of etching.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIGS. 1(a) and 1(b) are process cross-sectional views showing a method of manufacturing a semiconductor device according to the present invention, and in these figures, reference numeral 1 represents a semiconductor wafer, and 1o represents a chip for detecting the completion of etching. In addition, in FIGS. 1(a) and 1(b), parts and portions that are the same as or correspond to those in FIGS. 3(a) to 3(c) showing the conventional example are given the same reference numerals.

In this method, first, a semiconductor wafer 1 on which a recess 2 of a required depth d is to be formed and a chip 10 for detecting the end of etching, which has been formed in advance to a thickness T matching the depth d of the recess 2, are prepared. , a resist film pattern 3.11 serving as an etching mask is formed on the surface la of the semiconductor wafer l and on the surface 10a of the chip 10 for detecting the completion of etching.
form each. And resist film pattern 3
The semiconductor wafer 1 on which etching 11 is formed and the chip 10 for detecting the end of etching are arranged in parallel with each other.
), it is immersed in an etching solution 5 filled in an etching tank 4.

Then, these are kept immersed in the etching solution 5 (and the parts of the semiconductor wafer 1 not covered with the resist film pattern 3 and the chip 1 for detecting the end of etching are removed).
The portions not covered by the resist film pattern 11 of No. 0 are simultaneously etched by the etching liquid 5, and a recess 2 is formed in the semiconductor wafer l, and a recess 12 is formed in the etching completion detection chip 10. I'm going to go. Therefore, the operator observes the progress of etching through the depth of the recess I2 formed in the etching end detection chip IO, and as shown in FIG. If the etching operation is completed at this point, a recess 2 with a required depth d corresponding to the thickness T of the etching completion detection chip 10 will inevitably be formed in the semiconductor wafer 1.

By the way, when forming the recesses 2 in the semiconductor wafer 1 as explained above, variations in the amount of etching occur due to subtle differences in setting conditions, etc.
It is inevitable that the depths d of the recesses 2 will differ little by little from each other. Therefore, when considering the variation σ in the etching amount, two chips 15 and 16 for detecting the end of etching are used. It is conceivable to adopt a modified example of the method of the present invention used. That is, as shown in FIG. 2(a), the thickness of the etching end detection chip 15 used in this modification is determined by the amount of etching from the thickness that corresponds to the depth d of the recess 2 to be formed in the semiconductor wafer l in advance. Thickness TI< = after subtracting the variation σ
d-σ).

The thickness of the chip 16 for detecting the completion of etching is determined by adding the variation σ to the depth d of the recess 2 in advance.
2 (=d+σ).

Therefore, as shown in FIG. 2(a), if these etching end detection chips 15, 16 and the semiconductor wafer l on which the recess 2 is to be formed are arranged parallel to each other and etched simultaneously, the second As shown in Figure (b), when the predetermined immersion time has elapsed, only the recess 17 formed in the etching completion detection chip 15 penetrates, and the recess 18 formed in the etching completion detection chip 16 does not penetrate. This will result in a situation where this is not the case. Therefore, if the etching operation is finished at this point, the semiconductor wafer 1 will inevitably have a thickness that exceeds the thickness TI of the etching completion detection chip 15 and does not exceed the thickness T2 of the etching completion detection chip 16. This means that a recess 2 with a required depth d is formed. That is, the depth d of the recess 2 at this time is a depth in which the variation σ in the etching amount is taken into consideration in advance.

〔Effect of the invention〕

As explained above, according to the method of the present invention, the semiconductor wafer and the chip for detecting the end of etching are etched simultaneously, and a recess is formed in each of them. If the progress of etching is observed through the depth of the recess, and the etching process is finished when the recess penetrates, the thickness of the semiconductor wafer will inevitably match the thickness of the chip for detecting the completion of etching. This means that a recessed portion of the required depth is formed. Therefore, it is no longer necessary to perform etching twice due to measuring the depth of a recess formed in a semiconductor wafer, which is the case in the prior art, and the accompanying deterioration in etching accuracy is avoided.

Therefore, it is not only possible to improve production efficiency by eliminating waste caused by interruptions in etching operations, but also to form recesses in semiconductor wafers with high precision, ensuring an accurate thickness of the remaining etching area. The excellent effect of being able to do this can be obtained.

[Brief explanation of the drawing]

1 and 2 relate to the method of the present invention, and FIG. 1(a)
, (b) are process cross-sectional views showing a method for manufacturing a semiconductor device according to the present invention, and FIGS. 2(a) and (b) are process cross-sectional views showing a modification thereof. Further, FIGS. 3A to 3C are process cross-sectional views showing a conventional method for manufacturing a semiconductor device. In the figure, reference numeral 1 is a semiconductor wafer, 2 is a recess, 10 is a chip for detecting the end of etching, d is the depth of the recess, and T is the thickness of the chip for detecting the end of etching. Note that the same reference numerals in the drawings indicate parts and portions that are the same or correspond to each other.

Claims (1)

[Claims] (1) In a method of manufacturing a semiconductor device in which a recessed portion of a required depth is formed by etching a semiconductor wafer, the semiconductor wafer in which the recessed portion is to be formed and an etched portion formed in advance to a thickness that matches the depth of the recessed portion. A method for manufacturing a semiconductor device, characterized in that a wafer and a chip for completion detection are arranged in parallel, and the wafer and the chip are etched at the same time.