JPH11352137A - Function element, function element discrimination device and function element discrimination method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a function element, a function element discrimination device and a function element discrimination method, capable of discriminating the position on a semiconductor wafer where the function element is formed, concerning the function element taken out from the semiconductor wafer. SOLUTION: A discrimination mark, by which the position on a wafer, where for example, a cantilever 30 is formed as a function element, can be specified, is formed on a cantilever 30. Light is irradiated to the discrimination mark by a light source 41, and reflected light 52 is received and converted to an electric signal on a light receiving part 42. The converted electric signal is transmitted to a signal processing part 44 through AMP 43, and the signal processing part 44 recognizes the discrimination mark from the electric signal and discriminates the position on the wafer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a functional element taken out of a semiconductor wafer, a functional element identifying apparatus for identifying the functional element, and a functional element identifying method.

[0002]

2. Description of the Related Art Generally, a plurality of functional elements such as ICs and LSIs are required to have a minute size and a complicated multilayer structure. Therefore, a plurality of functional elements are simultaneously formed on a semiconductor wafer by using a photolithography technique. . In recent years, the development of micromachining technology has been remarkable, and attention has been paid to functional elements such as micropumps, microsensors, and electrostatic motors that have conventionally used functions and have achieved miniaturization. In particular, in the micromachining technology, not only functional elements having electric operation performance but also minute functional elements having mechanical operation performance depending on a shape, such as gears, springs and cantilevers, are realized. ing. A plurality of functional elements in the micromachining technology are also usually formed on a semiconductor wafer, similarly to the above-described ICs and LSIs.

In the functional elements described above, for example, a cantilever is a scanning probe microscope (SPM).
The probe is used as a scanning probe of an ng Probe Microscope, and its characteristics are greatly affected by the shape, together with the minute probe provided at the tip. Here, the SPM is the scanning of the probe provided on the cantilever in close proximity to the surface of the sample to be observed, and the deflection of the cantilever caused by the atomic force between the sample surface and the probe. This is a microscope that measures the shape of the sample surface by detecting the shape of the sample.

[0004] For a functional element having a shape-dependent performance such as this cantilever, a highly accurate and highly reproducible production step is particularly desired.

[0005]

However, a plurality of functional elements formed on a semiconductor wafer may cause lattice defects on the semiconductor wafer, non-uniform exposure in a photolithography process, or non-uniform reactions in an etching process. Due to various factors, the same size and the same shape were not always obtained. Further, even if a functional element having the same size and the same shape is obtained, when the wafer on which the functional element is formed is taken out into the air, impurities adhere to the surface of the functional element or molecules in the air may be removed. A minute shape may be lost due to the formation of an unnecessary insulating layer by the reaction.

[0006] The functional elements formed on these wafers are:
Fine shapes are often confirmed by direct observation using a scanning electron microscope (SEM) or the like.
Confirmation of the shape by visual observation through the sample display screen of EM,
It is not practical to perform for all the functional elements formed on the wafer because it requires a lot of time and effort. Therefore, in order to check the quality of the functional element, for example, in the case of a cantilever, for example, in many cases, the cantilever can be confirmed only by actually mounting the cantilever on the SPM and observing a standard sample such as mica. In this case, if high-quality observation results cannot be obtained for the standard sample, it is necessary to replace the cantilever, and it is not necessary to start high-precision SPM image observation of the target sample. It takes a long time.

Therefore, in order to make the process of forming the functional element formed on the wafer a highly reproducible and high quality process,
There is a need to improve the functional element creation process so as to obtain the position distribution of defective functional elements on the wafer, identify the various causes of the defects described above, and remove the causes.

Here, a functional element having electric performance,
For example, a MOS field effect transistor (MOS F
Silicon (Si) with a plurality of ET) formed in a matrix
By measuring the threshold voltage of the MOS FET for each wafer, each MOS FET can be evaluated. Here, in each of the MOS FETs formed on the wafer, a gate voltage is applied, and a gate voltage when a drain current reaches a certain value is set as a threshold voltage. Thus, MOS F
For an electric element such as ET, each element formed on a wafer can be easily and quickly evaluated by measuring electric characteristics.

However, in the case of a functional element having performance depending on the shape of the above-mentioned cantilever or the like, the shape is important and cannot be evaluated by electrical measurement. In addition, there is a method of evaluating the scratches and dirt on the wafer surface by detecting scattered light due to light irradiation, but it is difficult to apply the method to a functional element having a fine surface structure.

[0010] Therefore, a manufacturer producing a functional element depending on such a shape or a user who uses the functional element finds a defective functional element, and obtains the position where the functional element is formed on the wafer. The best method is to reflect the position distribution of the defective functional element obtained in this way in the functional element production process.

Further, such functional elements are generally used in a state of being individually taken out from a wafer. Even if a defective functional element is found by a user, the functional element is located on the wafer. Could not be specified, and even when a distribution of a certain shape or the like occurred in the wafer, the information could not be obtained.

The present invention has been made in view of the above, and is directed to a function element for specifying a position formed on a plurality of function elements formed on a semiconductor wafer, a function element identification apparatus, and a function element identification apparatus. It is an object to provide a method for identifying a functional element.

[0013]

Means for Solving the Problems The above-mentioned problems are solved,
In order to achieve the object, a functional element according to the invention of claim 1 is a functional element formed on a semiconductor wafer and separated from the semiconductor wafer and taken out of the semiconductor wafer. An identification mark for identification is provided.

According to the first aspect of the present invention, since the identification mark for specifying the position on the semiconductor wafer is formed on each of the functional elements formed on the semiconductor wafer, the functional element removed from the semiconductor wafer is formed on the functional element. On the other hand, by reading the identification mark, the position on the semiconductor wafer where the functional element has been formed can be specified.

Further, in the functional element according to claim 2, in the invention according to claim 1, the identification mark is one of aluminum (Al), titanium (Ti), tungsten (W), and gold (Au). Is formed from at least one of the following.

According to the second aspect of the present invention, the identification mark is formed of a material having high reflectivity, such as aluminum (Al), titanium (Ti), tungsten (W), and gold (Au), so that the light can be illuminated. Irradiates the identification mark to obtain an enhanced signal of the identification mark.

According to a third aspect of the present invention, in the functional element according to the first or second aspect, the functional element comprises a cantilever.

According to the third aspect of the present invention, since a plurality of cantilevers formed on a semiconductor wafer are each provided with an identification mark for specifying a position on the semiconductor wafer,
For the cantilever taken out of the semiconductor wafer,
By reading the identification mark, the position on the semiconductor wafer where the cantilever was formed can be specified.

According to a fourth aspect of the present invention, there is provided a functional element identification apparatus, wherein an identification mark formed on a semiconductor wafer and for specifying a position on the semiconductor wafer is provided, and is separated and taken out from the semiconductor wafer. A functional element, an identification mark imaging means for optically reading the identification mark and outputting an identification mark signal, and recognizing the identification mark from the identification mark signal to obtain information indicating an element formation position on the semiconductor wafer. And signal processing means for acquiring.

According to the present invention, the functional element on which the identification mark is formed is irradiated with light, and the reflected light reflected thereby is obtained as an identification mark signal to recognize the identification mark. Since the position on the wafer where the functional element is formed can be specified from the identification mark, a defective functional element position distribution on the wafer can be obtained particularly for a defective functional element.

According to a fifth aspect of the present invention, there is provided a method for identifying a functional element, comprising: a first step of forming an identification mark for specifying a position on the semiconductor wafer on a functional element formed on the semiconductor wafer; And a third step of recognizing the identification mark from the identification mark signal and acquiring information indicating an element formation position on the semiconductor wafer. Features.

According to the fifth aspect of the present invention, the identification mark is formed on the functional element, the reflected light is irradiated to the identification mark, and the reflected light is converted into an identification mark signal, whereby the identification mark is formed. Is recognized, and the position on the wafer where the functional element is formed can be specified from the identification mark.
In particular, it is possible to obtain manufacturing variations and position information within a wafer for defective functional elements, and to determine or estimate the performance of functional elements.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a functional device according to the present invention,
An embodiment of a functional element identification device and a functional element identification method will be described in detail with reference to the drawings. The present invention is not limited by the embodiment.

The functional element according to the present invention has an identification mark formed in a manufacturing process thereof. The functional element identifying apparatus and the functional element identifying method according to the present invention provide the functional element after removing the functional element from the wafer. Also, by detecting the identification mark, the position on the wafer where the functional element is formed can be specified. In this embodiment, a case will be described in which a cantilever is employed as a functional element having performance depending on a shape.

In general, in the SPM, the amount of deflection of the cantilever used is detected by irradiating the surface of the cantilever with a laser beam and measuring the change in the angle of reflection. ). Another method is to form a piezoresistor on the cantilever and measure the change in the resistance to detect the amount of deflection (in particular, this cantilever is referred to as a self-detecting cantilever). Then, based on these detected measurement values, image the shape of the sample surface,
Observation of the sample surface has been achieved.

The cantilever of the SPM is generally made of a silicon substrate and, like the semiconductor manufacturing process,
It is created using a fine processing technique using photolithography, anisotropic etching, or the like. Therefore, the cantilevers are finally provided in a state where a plurality of cantilevers are arranged side by side in a matrix on a circular single crystal flake, that is, a wafer in the manufacturing process. Cantilevers are generally
SPM users are supplied individually after being removed from the wafer. The user performs SPM observation after mounting the cantilever on the SPM cantilever holder.

Here, the resolution of the measurement value detected by the SPM strongly depends on the sharpness of the probe (tip) at the tip of the cantilever. That is, the observation results of the sample surface may vary depending on the quality of the cantilever.

Here, a case where an identification mark is created for the above-described self-detecting cantilever will be particularly described. FIG. 1 shows a state in which a plurality of cantilevers are formed in a matrix in a cantilever formation region 2 on a silicon wafer 1. Here, the cantilever formation region 2
Is an area that fits within the circular silicon wafer 1,
In particular, a plurality of individual cantilevers are partitioned by a rectangular area and stored.

An identification mark is individually given to each of the plurality of cantilevers. For example, as shown in FIG. 1, in the cantilever formation region 2, the maximum number (8 in the case of FIG. 1) and the short axis arranged along the long axis direction of the matrix element region, that is, the rectangular region of each cantilever. The maximum number arranged along the direction (1 in the case of FIG. 1)
Consider a virtual matrix (8 × 16 in the case of FIG. 1) in which 6) is arranged vertically and horizontally, respectively. Further, for the element areas along the vertical axis of this virtual matrix, A, B,
C,. . . And the symbol. Similarly, for the element zones along the horizontal axis, 01, 02, 03,. . . And number them. Thereby, the element area in the virtual matrix can be specified by the symbol and the number, and this is used as an identification mark.
For example, cantilever 3 can be represented as an element area of F-06. In this case, the cantilever formation region 2
Element area not included in (for example, A-01 to A-05)
In practice, no cantilever is actually formed, but in order to specify the position on the wafer from the identification mark, it is easier to intuitively understand such a rectangular matrix. The code used as the identification mark may be any symbol or number whose position in the matrix can be specified.

The identification mark determined in this way is
For example, it is formed on a support portion that supports the lever portion of the cantilever. FIG. 2 shows a self-detecting cantilever composed of a support portion 10, a lever portion 11, a probe 12, a piezoresistor 13, and a wiring 14. As shown in FIG. 2, the identification mark is formed at the position of the identification mark 15 or 16. The formation of the identification mark is incorporated as one of the steps for forming the cantilever.

Next, the process of forming the identification mark, together with the process of forming the cantilever, will be described with reference to FIGS. FIGS. 3 and 4 show a process cross section of a self-detecting cantilever, in particular.

First, as shown in FIG. 3A, a buried oxide layer 23 is formed on a semiconductor substrate 22 made of a silicon substrate, and an n-type SO
An SOI substrate having a sandwich structure in which the I silicon layer 20 is thermally bonded is formed. Then, silicon oxide films (SiO ₂ ) 21 and 25 are formed by thermally oxidizing the front side and the back side of the SOI substrate, and a photoresist film 27 serving as an etching mask is further formed on the silicon oxide film 21. Perform patterning.

Next, the silicon oxide film 21 is solution-etched using a buffered hydrofluoric acid solution (BHF) using the photoresist film 27 as a mask to form a probe as shown in FIG. A silicon oxide film (SiO ₂ ) 21 serving as a mask for patterning.

Subsequently, reactive ion etching (RIE) is performed using the patterned silicon oxide film 21 as a mask, so that a sharpened probe is formed under the mask 21 as shown in FIG. The needle 12 is formed.

Then, as shown in FIG. 3D, a region for forming a piezoresistor and a probe portion are opened on the surface of the semiconductor substrate 20 to form a photoresist film 29, and p ⁺ Ions are implanted to form p ⁺ piezoresistive regions and probe conductive regions. This allows
Piezoresistor 13 is formed in SOI silicon layer 20.

Next, the photoresist film 29 is removed, and a cantilever-shaped photoresist film 31 is formed on the SOI silicon layer 20, as shown in FIG. Then, using the photoresist film 31 as a mask,
SOI until buried oxide layer 23 is reached by RIE
The silicon layer 20 is etched to form an end of the cantilever.

Then, as shown in FIG. 4F, the photoresist film 31 is removed, and a photoresist film 33 serving as an etching mask is formed under the silicon oxide film (SiO ₂ ) 25 on the back surface. Photoresist film 3
3 is used as a mask, back etching is performed using a buffered hydrofluoric acid solution (BHF), and the silicon oxide film 25 is patterned.

Further, as shown in FIG. 4 (g), the metal contact portion of the piezoresistor 13 and the portion other than the probe 12 are covered with a silicon oxide film 19 to protect the surface, and the metal contact is formed by sputtering. The electrode 17 is formed by embedding aluminum (Al) in the portion. In FIG. 4G, for easy understanding, FIG.
Although the wiring 14 is omitted, the wiring 14 of aluminum (Al) is actually formed together with the formation of the electrode 17.

In the step of forming the electrode 17 and the wiring 14, the identification mark 15 is formed at the same time. On this occasion,
The mask used in sputtering includes an electrode 1
Not only the pattern of the wiring 7 and the pattern of the wiring 14 but also the pattern of the identification mark defined for each cantilever on the wafer are formed, so that the identification mark forming step is not required separately.

Subsequently, as shown in FIG.
Silicon oxide film 2 patterned and formed in (g)
5 as a mask and a 40% potassium hydroxide solution (KOH
By performing back etching using + H ₂ O), the semiconductor substrate 22 and the buried oxide layer 23 are partially removed, and the piezoresistor 13 and the identification mark 15 are provided with a predetermined thickness having flexibility. A cantilever is formed.

Here, p ⁺ ions are implanted into the n-type silicon layer 20 to form the p ⁺ piezoresistor 13. Conversely, when a p-type silicon layer is used, N ⁺ ions are implanted to form n ⁺ piezoresistors.

In the above-described cantilever forming process, the identification mark 15 is formed as an identification mark. As shown in FIG. 2, the identification marks 15 and 16 are formed by using a mask pattern for further forming the identification mark 16.
May be formed. In this case, the identification mark 16 represents, for example, a wafer number for identifying the wafer, and the identification mark 1
Along with 5, it is possible to specify a wafer on which a defective cantilever is formed, and to further specify a position on the wafer.

With respect to the cantilever obtained by the above-described cantilever forming process, the position where the cantilever was formed on the wafer is specified by the cantilever identification device shown in FIG. In FIG. 5, first, the cantilever 30 is provided with a light source 41 such as a xenon lamp.
Thus, the portion of the identification mark 15 or 16 is irradiated. The irradiation light 51 is reflected with high efficiency because the identification mark 15 or 16 is made of a material having a high reflectance such as aluminum, and the reflected light 52 is particularly reflected on the symbol string portion represented by the identification mark 15 or 16. Is emphasized,
The light is received by a light receiving unit 42 such as a CCD via a lens system (not shown).

The light receiving section 42 converts the received reflected light 52 into an electric signal, and the converted electric signal is input to a signal processing section 44 via an AMP (amplifier) 43. The signal processing unit 44 extracts a symbol string represented by the identification mark 15 or 16 from the input electric signal, and refers to matrix data indicating a cantilever formation position on a wafer prepared in advance, so that the display unit 45 The position where the cantilever 30 was formed on the wafer is displayed. In particular, when the identification mark 16 indicating the wafer number for identifying the wafer is formed on the cantilever 30, the wafer on which the cantilever 30 is formed can be specified and displayed.

By the above-described cantilever identification, the position on the wafer can be specified for a particularly defective cantilever, and positional information on the defective cantilever can be obtained. The position information of the defective cantilever obtained by the signal processing unit 44 is stored in a storage device (not shown) as data for statistically obtaining the distribution of the defective cantilevers on the wafer. Various parameters (exposure amount, etching time, etc.) applied in the cantilever manufacturing process depending on the finally obtained defective cantilever distribution
Can be changed as appropriate to improve the process, or to suppress shipment of cantilevers in portions where defective cantilevers frequently occur.

Therefore, according to the embodiment of the present invention, by forming the identification mark on the cantilever, the position on the wafer where the cantilever is formed can be specified, and the performance (particularly, in the case of the cantilever, the search can be performed). It is possible to obtain the estimation of the shape of the needle tip and the position distribution of the defective cantilever.

Further, by making the identification mark formed on the cantilever a material having a high reflectivity, a signal in which the identification mark is emphasized can be obtained. In the cantilever identification device, the identification mark with high accuracy and high reliability can be obtained. Recognition becomes possible.

In the embodiment described above, the identification mark is formed on the self-sensing cantilever. However, the identification mark can be formed on the optical lever cantilever. In this case, the identification mark 15 can be formed on the supporting portion 10 as shown in FIG. 6, similarly to the self-detection type cantilever. However, in the cantilever forming step, the identification mark forming step, that is, the aluminum (Al) sputtering step is separately performed. Need to. It should be noted that the cantilever identification device according to the present invention can be applied by forming an identification mark not only to the cantilever used for the SPM but also to the cantilever generally used in the scanning probe microscope.

In the embodiment described above, aluminum (A) is used as a material for forming the identification mark.
Although l) was used, other materials having high reflectivity, such as titanium (Ti), tungsten (W), and gold (Au), may be used. In particular, when forming an identification mark on a self-detecting cantilever, if a material having high reflectivity and high conductivity is selected as a material for forming the identification mark, the identification mark forming step is not required separately, which is preferable. is there.

In the above-described embodiment, a case where a cantilever is used as a functional element has been particularly described. However, a functional element (I
The present invention is also applicable to functional elements (micromachine elements such as probes, micropumps, and gears) having performances dependent on shapes other than cantilevers, such as C, LSI, and sensors.

[0051]

As described above, according to the first aspect of the present invention, a plurality of functional elements formed on a semiconductor wafer are each provided with an identification mark for specifying a position on the semiconductor wafer. By reading the identification mark of the extracted functional element, the position on the semiconductor wafer where the functional element has been formed can be specified.

According to the invention of claim 2, according to claim 1,
In addition to the effects of the invention, aluminum (Al),
By forming the identification mark with a material having high reflectivity such as titanium (Ti), tungsten (W), and gold (Au), when the light is irradiated to recognize the identification mark, a portion of the identification mark is emphasized. The obtained signal can be obtained.

According to the third aspect of the present invention, since a plurality of cantilevers formed on the semiconductor wafer are each provided with an identification mark for specifying a position on the semiconductor wafer, the cantilever removed from the semiconductor wafer can be used. By reading the identification mark, the position on the semiconductor wafer where the cantilever was formed can be specified.

According to the fourth aspect of the present invention, the functional element on which the identification mark is formed is irradiated with light, and the reflected light reflected thereby is converted into an electric signal to recognize the identification mark. Since the position on the wafer on which the functional element is formed can be specified from the identification mark, a defective functional element position distribution on the wafer can be obtained particularly for a defective functional element.

According to the fifth aspect of the present invention, an identification mark is formed on a functional element, and light is radiated toward the identification mark to convert reflected light into an identification mark signal, thereby enabling identification. Since the mark can be recognized and the position on the wafer where the functional element is formed can be specified from the identification mark, the defective functional element position distribution on the wafer can be obtained particularly for the defective functional element.

[Brief description of the drawings]

FIG. 1 is a diagram showing a wafer on which cantilevers are formed in a matrix.

FIG. 2 is a diagram showing a self-detecting cantilever on which an identification mark is formed according to the embodiment.

FIG. 3 is a diagram illustrating a cantilever forming step according to the embodiment.

FIG. 4 is a diagram illustrating a cantilever forming step according to the embodiment.

FIG. 5 is a diagram illustrating a cantilever identification device according to an embodiment.

FIG. 6 is a diagram showing an optical lever-type cantilever on which an identification mark is formed according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wafer 2 Cantilever formation area 3, 30 Cantilever 10 Support part 11 Lever part 12 Probe 13 Piezo resistor 14 Wiring 15, 16 Identification mark 17 Electrode 20, 22, Semiconductor substrate 21, 23, 25 Silicon oxide film 27, 29, 31 , 33 photoresist film 41 light source 42 light receiving unit 43 AMP (amplifier) 44 signal processing unit 45 display unit 51 irradiation light 52 reflected light

Claims (5)

[Claims] 1. A functional element formed on a semiconductor wafer and separated and taken out from the semiconductor wafer, wherein an identification mark for specifying a position on the semiconductor wafer before being separated from the semiconductor wafer is provided. Characteristic functional element. 2. The method according to claim 1, wherein the identification mark is made of aluminum (A).
l), titanium (Ti), tungsten (W), gold (A
The functional element according to claim 1, wherein the functional element is formed from at least one of u). 3. The functional element according to claim 1, comprising a cantilever. 4. An identification mark formed on a semiconductor wafer and specifying a position on the semiconductor wafer,
A functional element separated and taken out from the semiconductor wafer, an identification mark imaging unit for optically reading the identification mark and outputting an identification mark signal, and recognizing the identification mark from the identification mark signal, Signal processing means for acquiring information indicating the element formation position on the functional element identification device. 5. A first step of forming an identification mark for specifying a position on the semiconductor wafer on a functional element formed on the semiconductor wafer, and a step of optically reading the identification mark and converting the identification mark into an identification mark signal. A functional element identification method, comprising: two steps; and a third step of recognizing the identification mark from the identification mark signal and acquiring information indicating an element formation position on the semiconductor wafer.