JPH11214457A - Inspection element for epitaxial film and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow various characteristics of an epitaxial film to be easily measured when processing, by providing an epitaxial film to be formed along a slit portion and measuring terminal leading pad portions to be connected to the epitaxial film. SOLUTION: An epitaxial film 107A extending along a slender slit portion and measuring terminal leading pads 107B to be connected to the film 107A are formed at an opening surrounded by side walls. A potential difference between the portions 107B is measured by applying a current to the portions 107B. As a result of the measurement of the potential difference, the resistance of the film 107A can be obtained. The thickness of the film 107A is obtained based on the resistance. That is, inline measurements of the epitaxial film on the actual device, its evaluations as a single body, and measurements within a predetermined area can be made. As a result, the thickness of the epitaxial film can be measured immediately after the epitaxial film formation step has been finished.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a test element for evaluating an epitaxial film, and more particularly to a structure of a test element for evaluating an epitaxial film of a high-speed bipolar transistor and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, in the measurement of an epitaxial film, the thickness and sheet resistance of the epitaxial film have been measured over the entire surface of a wafer using a dedicated wafer.

[0003]

However, with the further increase in the speed of the high-speed bipolar and the miniaturization of the transistor, a selective epitaxial film has been used for the base region, and the evaluation of the crystallinity in the fine region has been made. The control of sheet resistance has become an indispensable technology.

In the above-described monitoring using a conventional monitor wafer, it is possible to measure the film thickness and sheet resistance in a large area, but the same size (width 1) as that of a transistor is possible.
(equal to or less than 0.1 μm and a thickness of 0.1 μm or less) cannot be evaluated for the following reasons. FIG. 10 is a cross-sectional view of a manufacturing process of a device according to a conventional method.

(1) First, as shown in FIG.
An oxide film 602 is formed on a first conductivity type semiconductor substrate 601, followed by a polycrystalline silicon film 603 and an oxidation resistant film 604.
Are sequentially formed. (2) Next, as shown in FIG. 10B, a part of the oxidation-resistant film 604 and a part of the polycrystalline silicon film 603 are sequentially removed by using a known photolithography etching technique, so that an oxidation-resistant film pattern 604a is formed. A polycrystalline silicon film pattern 603a is formed.

(3) Next, as shown in FIG.
When a nitride film (not shown) is formed on the entire surface and well-known anisotropic etching is performed, a sidewall 605 is formed in the opening. (4) Next, as shown in FIG. 10D, a part of the oxide film 602 is removed using buffered hydrofluoric acid, and the oxide film pattern 6 is removed.
02a is formed.

(5) Next, as shown in FIG. 10E, an epitaxial film 606 is formed in a portion where the oxide film 602 has been removed by a known selective epitaxial film growth technique. At this time, an epitaxial film is grown from the direction of the substrate 601 in the opened portion and from the polycrystalline silicon film 603, and the two are connected in a self-aligned manner. However, the above-mentioned conventional method cannot detect a difference between epitaxial film growth in a large area and a small area, and the finished state on an actual device can be confirmed only by a destructive test after completion of a wafer process. could not.

Furthermore, since the epitaxial film is connected to the polycrystalline silicon film for leading out the electrodes in a self-aligned manner due to its growth, it is not possible to measure various characteristics of a single epitaxial film layer with a transistor pattern. Was.
The present invention eliminates the above problems, and provides an epitaxial film inspection element and a method for manufacturing the same, which can easily measure in a process various characteristics of an epitaxial film that determines the performance of an ultra-high-speed bipolar element or the like. The purpose is to:

[0009]

In order to achieve the above object, the present invention provides: [1] In an inspection device for an epitaxial film, a polycrystalline semiconductor film and an oxidation-resistant film are formed on a main surface of a semiconductor substrate of a first conductivity type. Is provided with a slit portion opened by patterning, an epitaxial film formed in the slit portion, and a measuring terminal lead-out pad portion connected to the epitaxial film.

[2] The inspection element for an epitaxial film according to [1], wherein a slit-shaped dummy pattern is arranged in parallel with the slit portion. [3] In the inspection element of the epitaxial film, a slit portion formed by patterning a polycrystalline semiconductor film and an oxidation-resistant film on the main surface of the semiconductor substrate of the first conductivity type and opening; an epitaxial film formed in the slit portion; A first measurement terminal lead-out pad connected to the epitaxial film;
A second measurement terminal lead-out pad portion connected to the slit portion is arranged.

[4] In a test element for an epitaxial film, a polycrystalline semiconductor film and an oxidation-resistant film are patterned and opened on a main surface of a semiconductor substrate of a first conductivity type, and an epitaxial film formed in the slit is formed. A plurality of films are arranged in parallel, and on both sides of the plurality of epitaxial films, measurement terminal lead-out pads sequentially arranged in series are arranged.

[5] In the inspection element for an epitaxial film, a polycrystalline semiconductor film and an oxidation-resistant film are patterned and opened on the main surface of a semiconductor substrate of the first conductivity type, and an epitaxial portion formed in the slit portion is formed. An epitaxial film reduced in size by forming a diffusion layer of the second conductivity type on the film;
A pad for leading a measurement terminal connected to the epitaxial film is provided.

[6] In a method of manufacturing an inspection element for an epitaxial film, a step of forming an oxide film on a main surface of a semiconductor substrate of a first conductivity type and removing a part thereof, and a step of forming a polycrystalline semiconductor film on the entire surface A step of forming an oxidation-resistant film, a step of removing the polycrystalline semiconductor film and a part of the oxidation-resistant film, and a step of forming an oxidation-resistant film on the entire surface and performing etching, thereby forming a side wall on the opening location. A step of forming a wall and a step of forming a selective epitaxial film in a region surrounded by the sidewall are performed.

[7] In the method of manufacturing an inspection element for an epitaxial film according to the above [6], in the step (c), when performing patterning for removing a part of the polycrystalline semiconductor film and the oxidation-resistant film, 50μm × 50μm at both ends
A measurement pad including the openings having the above sizes is formed. [8] In the method for manufacturing an inspection element for an epitaxial film according to the above [6], in the step (c), when performing the patterning for removing a part of the polycrystalline semiconductor film and the oxidation-resistant film, the selective epitaxial film Are arranged in parallel with the pattern to be measured.

[0015]

[9] The method of manufacturing a semiconductor device according to [6], wherein, after the step (e), a step of forming a polycrystalline semiconductor film on a main surface thereof and introducing an impurity of a second conductivity type; A step of removing a part of the second conductivity type polycrystalline semiconductor film, and forming a second conductivity type buried layer.

[0016]

Embodiments of the present invention will be described below in detail. FIG. 1 is a schematic plan view of a test element for an epitaxial film showing a first embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line AA of FIG. 1, FIG. 3 is a cross-sectional view taken along line BB of FIG. FIG. 4 is a cross-sectional view showing a manufacturing process of a test element for an epitaxial film showing a first embodiment of the present invention.

The first embodiment of the present invention will be described with reference to these drawings. 101 is a P-type semiconductor substrate, 102 is an oxide film, 102a is an oxide film pattern, 103 is a polycrystalline silicon film, 103a is a polycrystalline silicon film pattern, 104
Is a nitride film, 104a is a nitride film pattern, 105 is an opening, 106 is a side wall, 107 is an epitaxial film (pattern), 107A is a thin slit portion of the epitaxial film, and 107B is a pad portion for leading a measurement terminal. .

Hereinafter, a method of manufacturing the inspection element of the epitaxial film will be described. (1) First, as shown in FIG. 4A, an oxide film 102 is formed on a P-type semiconductor substrate 101. That is, the state of the substrate after the element isolation process is completed. (2) Next, as shown in FIG. 4B, a part of the oxide film 102 is selectively removed by using a well-known photolithographic etching technique to form an oxide film pattern 102a. Subsequently, a polycrystalline silicon film 103 is deposited on the entire surface.
A silicon nitride film 104 is generated.

(3) Next, as shown in FIG.
A resist R is applied and etched to form a resist mask for patterning the silicon nitride film 104 and the polycrystalline silicon film 103. Thereafter, the silicon nitride film 104 and the polycrystalline silicon film 103 are continuously etched to form a silicon nitride film pattern 104a and a polycrystalline silicon film pattern 103a.

At this time, the silicon nitride film pattern 104
a, 50 at both ends of the polycrystalline silicon film pattern 103a.
An opening having a size of × 50 μm or more, that is, a measurement pad region is formed. (4) Subsequently, the resist mask is removed, and as shown in FIG. 4D, a silicon nitride film (not shown) is deposited and anisotropic etching is performed. Is generated.

(5) Subsequently, as shown in FIG.
In the opening 105 surrounded by the side wall 106, an epitaxial film pattern (as shown in FIG. 1, an epitaxial film 107A to a narrow slit portion and a The epitaxial films 107B) 107 are generated. As described above, according to the first embodiment, as the TEG (test element group) of the same wafer, the epitaxial film 107 can be generated in the same slit as the actual device (real integrated circuit).

The resistance value of the epitaxial film can be obtained by measuring the potential difference between the measurement terminal lead-out pad portions 107B by passing a current between the measurement terminal lead-out pad portions 107B, 107B thus formed. Can be. The film thickness can be obtained based on this resistance value. As described above, immediately after the end of the process, the thickness of the epitaxial film can be easily and electrically measured.

For example, the width of the opening 105 is 0.5 μm,
When the measurement was performed with the length being 10 μm and the area of the measuring pad being 90 μm on each side, the epitaxial film thickness was 500 °
, The resistance value is about 5Ω. When the epitaxial film thickness varies at ± 10%, the resistance value is also 10%.
% Can be detected. As described above, in the first embodiment, in-line measurement of an epitaxial film on an actual device, evaluation of a single device, and measurement in a predetermined area can be performed.

Next, a second embodiment of the present invention will be described. FIG. 5 is a schematic plan view of a test element of an epitaxial film showing a second embodiment of the present invention. In this figure, 20
2a is an oxide film pattern, 204a is a nitride film pattern, 2
Reference numeral 07 denotes an epitaxial film, 207A denotes a thin slit portion of the epitaxial film, and 207B denotes a measurement terminal lead-out pad portion connected to the thin slit portion 207A.

In this embodiment, a slit-shaped dummy pattern 207C is arranged in parallel with the thin slit portion 207A of the epitaxial film. As shown in this figure, when patterning is performed using step (3) of the first embodiment, that is, using a well-known photolitho etching technique, the same slit as the narrow slit 207A is formed around the narrow slit 207A. A plurality of dummy patterns 207C each having an opening having a width are formed in parallel.

As described above, according to the second embodiment, it is possible to measure the epitaxial film thickness in a dense pattern or a close pattern of transistors. That is, in-line measurement of the epitaxial film on the actual device,
The film thickness can be evaluated in a dense portion such as an array. Next, a third embodiment of the present invention will be described.

FIG. 6 is a schematic plan view of an inspection element of an epitaxial film showing a third embodiment of the present invention. In this figure, 302a is an oxide film pattern, 304a is a nitride film pattern, 307 is an epitaxial film, 307A is a slit portion of the epitaxial film, 307B is a measuring terminal lead-out pad portion connected to the slit portion 307A,
307C is a slit portion connected to point a of the slit portion 307A, 307D is a measurement terminal lead-out pad portion connected to the slit portion 307C, and 307E is a slit portion 30
A slit portion 307F connected to the point b of 7A is a measurement terminal lead-out pad portion connected to the slit portion 307E.

In this embodiment, step (3) of the first embodiment is performed.
In the step of patterning the nitride film 304,
An opening having the shape shown in FIG. 6 is provided, and thereafter, an epitaxial film is formed therein. In this way, a pattern shape of the patterned epitaxial film is obtained, and a current is supplied to, for example, the measurement terminal lead-out pad portion 307B (left side), the slit-shaped epitaxial film 307A, and the measurement terminal lead-out pad portion 307B (right side). By measuring the potential difference between the flow-through and the measurement terminal lead-out pad portions 307D and 307F, the resistance between the point a and the point b of the slit-shaped epitaxial film 307A can be accurately measured.

As described above, according to the third embodiment, by adopting the Kevin measurement method, compared with the first embodiment,
Very accurate measurement results of the epitaxial film can be obtained. That is, in this embodiment, it is possible to perform in-line measurement of an epitaxial film on an actual device, evaluation of a single device, and high-accuracy Kenvin measurement.

Next, a fourth embodiment of the present invention will be described. FIG. 7 is a schematic plan view of an inspection element for an epitaxial film showing a fourth embodiment of the present invention. In this figure, 40
2a is an oxide film pattern, 404a is a nitride film pattern, 4
Reference numeral 07 denotes an epitaxial film pattern.

In this embodiment, the process (3) of the first embodiment is performed.
Then, the nitride film 404a is patterned as shown in FIG. Therefore, the pad (a) in FIG.
By flowing a constant current through the pad (d) and measuring the potential difference between the pad (b) and the pad (c), the film thickness of the second line (2) can be measured. A constant current is applied to the pad (b) -pad (e), and the pad (c)-
When the potential difference between the pads (d) is measured, the film thickness of the third line (3) is similarly changed by passing a constant current to the pad (c) -pad (f) and the pad (d) -pad (e). By measuring the potential difference between the fourth line (4), the film thickness of the fourth line (4) can be measured.

That is, two pads and ten pads are usually required to measure the film thickness of one line and five lines, respectively, according to this layout. Can be reduced in the number of pads. As described above, according to the fourth embodiment, the film thickness of the epitaxial film in a state where the pattern is in close contact can be measured with high accuracy by adopting the Kevin measurement method.

That is, in this embodiment, it is possible to perform in-line measurement of an epitaxial film on an actual device, evaluation of the film thickness in a dense portion such as an array, and high-precision Kenvin measurement. Next, a fifth embodiment of the present invention will be described. FIG. 8 is a schematic plan view of an epitaxial film test device according to a fifth embodiment of the present invention, and FIG. 9 is a cross-sectional view of the epitaxial film test device according to the fifth embodiment of the present invention.

In these figures, 501 is a P-type semiconductor substrate, 502a is an oxide film pattern, 503a is a polycrystalline silicon film pattern, 504a is a nitride film pattern, 507
507A is an epitaxial film pattern, 507A is a thin slit portion of the epitaxial film, 507B is a pad portion for extracting a measuring terminal, 508 is a polycrystalline silicon film, 50
8a is a polycrystalline silicon pattern.

FIG. 9A shows a state in which a polycrystalline silicon film 508 has been formed following the step (e) of the first embodiment. Next, as shown in FIG. 9B, As ions are implanted into the entire surface, and the polycrystalline silicon film 508 is partially removed by using a well-known photolithographic etching technique to form a polycrystalline silicon film pattern 508a. To form Subsequently, for example, when heat treatment is performed at 900 ° C. for 30 minutes, the N-type diffusion layer 5 is formed.
09 is generated.

As described above, according to the fifth embodiment, the film thickness of the base region in an actual device is known by measuring the resistance of the epitaxial film region 507 in which the slit shape is reduced by the N-type diffusion layer 509. be able to. That is, in this embodiment, in-line measurement of an epitaxial film on an actual device, measurement in a predetermined area, and measurement of pinch resistance can be performed.

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0038]

As described above, according to the present invention, the following effects can be obtained. (A) According to the first, sixth or seventh aspect of the invention, the characteristics of the epitaxial film, for example, the film thickness can be easily and electrically measured immediately after the step is completed.

(B) According to the second or eighth aspect of the invention, it is possible to measure the epitaxial film thickness in a dense pattern or a close pattern of transistors. (C) According to the third or fourth aspect of the invention, by adopting the Kevin measurement method, it is possible to obtain an extremely accurate measurement result of the epitaxial film as compared with the first embodiment.

(D) According to the fifth or ninth aspect of the present invention, the resistance of the epitaxial film region in which the slit shape is reduced can be measured by the N-type diffusion layer. Of the base region can be known.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of an inspection element for an epitaxial film showing a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is a cross-sectional view illustrating a manufacturing process of an inspection element for an epitaxial film according to the first embodiment of the present invention.

FIG. 5 is a schematic plan view of a test element of an epitaxial film showing a second embodiment of the present invention.

FIG. 6 is a schematic plan view of an epitaxial film inspection element according to a third embodiment of the present invention.

FIG. 7 is a schematic plan view of an inspection element for an epitaxial film showing a fourth embodiment of the present invention.

FIG. 8 is a schematic plan view of an inspection element of an epitaxial film showing a fifth embodiment of the present invention.

FIG. 9 is a cross-sectional view of a test element of an epitaxial film showing a fifth embodiment of the present invention.

FIG. 10 is a cross-sectional view of a manufacturing step of a device according to a conventional method.

[Explanation of symbols]

101, 501 P-type semiconductor substrate 102 Oxide film 102a, 202a, 302a, 402a, 502a
Oxide film pattern 103,508 Polycrystalline silicon film 103a, 503a, 508a Polycrystalline silicon film pattern 104,207 Nitride film 104a, 204a, 304a, 404a, 504a
Nitride film pattern 105 opening 106 side wall 107, 207, 307, 407, 507 epitaxial film (pattern) 107A, 207A, 307A, 307C, 307E,
507A Thin slit portions 107B, 207B, 307B, 307D, 307F,
507B Measurement terminal lead-out pad portion 207C Dummy pattern (opening) 509 N-type diffusion layer

Claims (9)

[Claims] 1. A slit portion formed by patterning a polycrystalline semiconductor film and an oxidation-resistant film on a main surface of a semiconductor substrate of a first conductivity type, an epitaxial film formed in the slit portion, and a connection to the epitaxial film. An inspection element for an epitaxial film, comprising: 2. The test element for an epitaxial film according to claim 1, wherein a slit-like dummy pattern is arranged in parallel with said slit portion. 3. A slit portion formed by patterning a polycrystalline semiconductor film and an oxidation-resistant film on a main surface of a semiconductor substrate of a first conductivity type, an epitaxial film formed in the slit portion, and a connection to the epitaxial film. A first measurement terminal lead-out pad portion and a second measurement terminal connection portion connected to the slit portion.
A test terminal lead-out pad portion. 4. A slit portion formed by patterning a polycrystalline semiconductor film and an oxidation-resistant film on a main surface of a semiconductor substrate of a first conductivity type, and a plurality of epitaxial films formed in the slit portion are arranged in parallel. An inspection element for an epitaxial film, wherein a plurality of measurement terminal lead-out pads sequentially arranged in series on both sides of the plurality of epitaxial films are arranged. 5. A slit portion formed by patterning a polycrystalline semiconductor film and an oxidation-resistant film on a main surface of a semiconductor substrate of a first conductivity type, and a second conductivity type on an epitaxial film formed in the slit portion. An epitaxial film inspection element, comprising: a reduced epitaxial film formed with a diffusion layer; and a measuring terminal lead-out pad connected to the epitaxial film. 6. A process of: (a) forming an oxide film on a main surface of a semiconductor substrate of a first conductivity type and removing a part thereof; and (b) forming a polycrystalline semiconductor film and an oxidation-resistant film on the entire surface. The process of
(C) a step of removing the polycrystalline semiconductor film and part of the oxidation-resistant film, and (d) forming an oxidation-resistant film on the entire surface and performing etching to form a sidewall on the side wall of the opening. And (e) generating a selective epitaxial film in a region surrounded by the side wall. 7. The method for manufacturing an inspection element for an epitaxial film according to claim 6, wherein in the step (c), when performing patterning for removing a part of the polycrystalline semiconductor film and the oxidation-resistant film, both ends thereof are formed. Forming a measuring pad having an opening having a size of 50 μm × 50 μm or more. 8. The method of manufacturing an inspection element for an epitaxial film according to claim 6, wherein in the step (c), when performing patterning for removing a part of the polycrystalline semiconductor film and the oxidation-resistant film, selective epitaxial growth is performed. A method for manufacturing a test element for an epitaxial film, comprising arranging a pattern of an opening for forming a film in parallel with a device for measuring the pattern. 9. The method of manufacturing an inspection element for an epitaxial film according to claim 6, wherein: (a) following the step (e), a polycrystalline semiconductor film is formed on a main surface thereof, and impurities of the second conductivity type are formed. (B) removing a part of the second conductivity type polycrystalline semiconductor film; and (c) forming a buried layer of the second conductivity type. Manufacturing method.