JP2000100674A - Method for marking semiconductor wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for marking semiconductor wafer by which the number of manufacturing processes of a semiconductor wafer can be reduced and, at the same time, the manufacturing yield of the wafer can be increased while the method uses a hard marking method by which an inexpensive capital investment and an inexpensive manufacturing cost can be realized. SOLUTION: A mark 3 is formed in the marking area MA of a semiconductor wafer 1 by a hard marking method in which a marking substance is physically scattered and removed by projecting a laser beam 15 upon the substance. At the time of forming the mark 3, an non-oxidizable mask 12 used for forming a field oxide film in an element separating area FA is also used as a protective film 12 for marking to protect an element area TA from the scattered substance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for marking a semiconductor wafer, and more particularly to a method for marking a semiconductor wafer capable of improving the yield in manufacturing while reducing the number of manufacturing steps. Furthermore, the present invention is suitable for hard marking which physically removes a substrate surface portion by laser irradiation, and which is excellent in compatibility with a retrograde well process capable of simplifying a well forming process, and marking of a semiconductor wafer excellent in compatibility. About the method.

[0002]

2. Description of the Related Art At present, in semiconductor manufacturing technology, a semiconductor wafer process is being carried out by marking semiconductor wafers in advance in order to manage the semiconductor wafers one by one. Marking is an operation of writing a mark, which is a single or a combination of a plurality of numbers, symbols, or characters, having predetermined information such as a manufacturing number, a model number, and a product name on a semiconductor wafer. Usually, such marking is preferably performed at an early stage of a semiconductor wafer process, that is, before an LSI process for actually forming a semiconductor element is started, in order to manage the semiconductor wafer.

[0003] The mainstream marking methods include an exposure marking method in which a semiconductor wafer is marked by etching using a mask formed by photolithography technology, and a laser marking method in which a semiconductor wafer is directly marked by laser light irradiation. . At present, the laser marking method is the most common in that the number of manufacturing steps can be reduced.

[0004] Laser marking methods differ in marking properties depending on the wavelength used, the position of the focal point, the laser excitation method, and the like, and are generally broadly classified into soft marking methods and hard marking methods.

FIG. 11 is a sectional view showing a marking step by a soft marking method. The soft marking method irradiates the laser light 25S to the surface of the marking area of the semiconductor wafer 21 to melt the surface of the semiconductor wafer 21 to generate a pit, and deposit a molten material around the pit. This is a method of forming the mark 23S from the deposit.

FIG. 12 is a sectional view showing a marking step by the hard marking method. The hard marking method is a method of irradiating the surface of the marking area of the semiconductor wafer 21 with laser light 25H, physically flipping the surface of the semiconductor wafer 21 to generate a depression, and forming the mark 23H by the depression.

In the former soft marking method, the mark 23S is basically formed by melting the surface portion of the semiconductor wafer 21, so that scattered substances (garbage) do not scatter around the marking area, and thus the soft marking method is used. It is often used as a simple marking method.

However, the soft marking method has a problem in the visibility of the mark 23S. For example,
When soft marking is performed with a YAG laser, which is the most common light source, the mark 23S is very shallow and can only be formed at a depth of about 1 μm. Therefore, after forming the mark 23S, an interlayer insulating film or wiring metal is formed by an LSI process. Several μm of membrane
When the mark 23S is formed with a thickness of m, the mark 23S becomes invisible. To ensure the visibility of the mark 23S
A depth of 3 μm or more is required. A laser marking device that provides good visibility with soft marking is devised with a laser beam wavelength and an excitation method, and is very expensive due to a special device configuration. For this reason, there is a disadvantage that capital investment and product prices increase.

On the other hand, in the latter hard marking method, the mark 23H is basically formed by physically flipping the surface portion of the semiconductor wafer 21, so that the mark 23H can be freely formed at a depth in the range of several μm to several tens μm. The mark 23H can be formed, and there is no visibility problem. In addition, the price of the laser marking device is inexpensive to about one half to one half of that of the laser marking device that performs soft marking.
Capital investment and product prices can be reduced.

However, as shown in FIG. 12, when hard marking is performed on the surface of the semiconductor wafer 21, fragments of the semiconductor wafer 21 are scattered around the marking area as scattered substances 21a, and the scattered substances 21a have high energy. As a result, the scattering material 21a collides with the semiconductor wafer 21 and damages the surface of the semiconductor wafer 21.
The scattered substance 21a pierces the surface of 1. The scattered substance 21a generated by the hard marking can be removed by washing after the marking, but the semiconductor wafer 2a can be removed.
The surface flaw cannot be removed unless a surface etching step or the like is incorporated. In particular, if there is a scratch on the surface of the semiconductor wafer 21 in an element region where a transistor, a resistive element, a capacitive element, and the like are formed, it causes a leak and the like and causes a reduction in manufacturing yield.

Therefore, it is conceivable to form a protective film for the scattered substance 21a in advance in the element region at the time of hard marking. FIG. 13 is a process sectional view showing a marking step by the hard marking method, and is a sectional view in a state where marking is performed after the protection film 22 is formed. As the protective film 22, a silicon oxide film or a silicon nitride film is used. As described above, by performing hard marking after forming the protective film 22, the scattering material 2
The semiconductor wafer 21 having no scratch on the surface can be obtained by removing the protective film 22 after the hard marking, although the scratch due to 1a is generated and the flying substance 21a pierces.

[0012]

However, in the hard marking method as shown in FIG.
The following points are not considered.

(1) Protective film 2 for hard marking
2 and the step of removing the protective film 22 after the hard marking need to be separately incorporated into the semiconductor wafer process. Therefore, the number of manufacturing steps of the semiconductor wafer process simply increases.

(2) Further, even if a hard marking method is adopted to reduce capital investment and product price, the product price increases with the increase in the number of manufacturing steps.

(3) Further, in recent years, a retrograde well process is becoming widespread in order to shorten the time required for completing the steps of the semiconductor wafer process or the LSI process as a whole. This retrograde well process is a process in which a well region is formed after a field oxide film is formed in an element isolation region, as opposed to a process in which a field oxide film is formed in an element isolation region after a well region is formed. A high-energy ion implantation method is used to form the well region. In the element isolation region, impurities are directly implanted into the semiconductor wafer through the field oxide film and in the element region without the field oxide film therebetween. By activating the impurities, a well region can be formed. The heat treatment time required for this activation can be significantly reduced as compared with the heat treatment (well diffusion) time in the former process of forming a well region in advance. Therefore, the retrograde well process is considered to become the mainstream of the semiconductor wafer process in the future, and it is necessary to ensure the consistency of the hard marking method with the retrograde well process.

The present invention has been made to solve the above problems. Therefore, a first object of the present invention is to reduce the number of manufacturing steps and improve the manufacturing yield while using a hard marking method capable of realizing low capital investment and low manufacturing cost. It is an object of the present invention to provide a method for marking a semiconductor wafer. In particular, a first object of the present invention is to mark a semiconductor wafer by effectively utilizing a mask for forming an element isolation region, thereby reducing the number of manufacturing steps and improving the manufacturing yield. Is to provide a way.

A second object of the present invention is to achieve a further reduction in the number of manufacturing steps and an increase in manufacturing yield by effectively utilizing a process for forming an element isolation region while achieving the first object. It is an object of the present invention to provide a method for marking a semiconductor wafer, which can improve the quality of a semiconductor wafer.

A third object of the present invention is to provide a method for marking a semiconductor wafer which can achieve compatibility with a retrograde well process while achieving the first or second object. It is.

[0019]

In order to solve the above-mentioned problems, a first feature of the present invention is to provide a method for marking a semiconductor wafer, comprising the steps of: providing an element region, an inter-element isolation region and a marking region on a silicon substrate surface; A step of forming an oxidation-resistant mask in which an opening is formed in the element isolation region covering at least the element region, and a step of forming a field oxide film on the surface of the element isolation region of the silicon substrate using the oxidation-resistant mask; Using an oxidation-resistant mask as a protective film for marking, physically scattering and removing the surface of the silicon substrate or the surface of the field oxide film by hard marking by laser irradiation, and forming a mark having predetermined information on the silicon substrate. It is prepared.

In such a method for marking a semiconductor wafer, an oxidation-resistant mask (specifically, a silicon nitride used in a so-called LOCOS process) formed in an element region for forming a field oxide film in an element isolation region is used. The film is also used as a marking protective film for hard marking, so that it is not necessary to separately form a marking protective film, and the number of manufacturing steps of the semiconductor wafer process can be reduced. Furthermore, in the inter-element isolation region, a mark was formed by hard marking after forming a field oxide film, so that the field oxide film also served as a protective film for marking, eliminating the need to separately form a protective film for marking. The number of manufacturing steps of the wafer process can be reduced. further,
Since hard marking is performed with the marking protective film (oxidation-resistant mask) formed in the element region, it is possible to cope with the scattered substance scattered in the element area during the hard marking, and a defect caused by the scattered substance. Therefore, the production yield of the semiconductor wafer process can be improved. Further, in such a method for marking a semiconductor wafer, marking can be performed at an early stage of a semiconductor wafer process in which a field oxide film is formed in an element isolation region, so that management of the semiconductor wafer can be performed from an early stage of the process. It can be implemented reliably.

According to a second feature of the present invention, in the method for marking a semiconductor wafer according to the first feature, the step of forming an oxidation-resistant mask is a step of forming an oxidation-resistant mask on a surface of a silicon substrate via a buffer oxide film. That is, after the step of performing marking, a step of removing the oxidation-resistant mask, and subsequently removing the buffer oxide film and simultaneously removing the surface portion of the field oxide film is provided.

In such a method for marking a semiconductor wafer, a buffer oxide film (specifically, a silicon oxide used in a so-called LOCOS process) is formed in an element region to form a field oxide film in an element isolation region. The scattered substance scattered on the surface portion of the field oxide film can be removed by using the step of removing the film. Therefore, the step of cleaning the surface portion of the field oxide film (the step of removing scattered substances), which is also used as the protective film for marking, can be used in the step of removing the buffer oxide film, eliminating the need for an additional cleaning step. The number of manufacturing steps of the semiconductor wafer process can be reduced.

According to a third feature of the present invention, in the method for marking a semiconductor wafer according to the first feature or the second feature, after the step of performing the marking, ion implantation is performed inside the silicon substrate in the device region and between the devices. A step of introducing a well region forming impurity into the silicon substrate through the field oxide film in the isolation region and activating the well region forming impurity is provided to form a well region.

In such a method for marking a semiconductor wafer, a field oxide film is formed in an inter-element isolation region, and a well region is formed after marking, so that the semiconductor wafer process is formed at an initial stage before the formation of the well region. Marking can be performed. Therefore, the management of the semiconductor wafer can be reliably performed from the initial stage of the process. Further, in the method for marking a semiconductor wafer, marking can be performed in the middle of a retrograde well process in which a well region is formed by high-energy ion implantation after formation of a field oxide film. Suitability can be ensured.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a principal part of a semiconductor wafer in a state where a semiconductor wafer process and an LSI process according to an embodiment of the present invention have been almost completed.
FIG. 2 is a perspective view of the semiconductor wafer. As shown in FIGS. 1 and 2, a semiconductor wafer (silicon base) 1 according to the present embodiment is formed of a semiconductor substrate made of a single crystal silicon wafer. As shown in FIG. 2, the semiconductor wafer 1 is formed in a flat disk shape, and an orientation flat 1OF is provided on the lower side in FIG.

On the main surface of the semiconductor wafer 1, a semiconductor chip area 1C to be cut out later as one semiconductor chip
Are regularly arranged in a matrix. A scribe area 1S is provided between the semiconductor chip areas 1C and 1C or on the periphery of the semiconductor chip area 1C. The areas other than the semiconductor chip area 1C and the scribe area 1S are areas where elements are not normally formed as dead space areas 1D except for the area where the test elements are provided.

In the semiconductor wafer 1 according to the present embodiment, a marking area MA is arranged in a part of the dead space area 1D, more specifically, in each of the upper and lower dead space areas 1D of the semiconductor wafer 1 in FIG. Is established. As shown on the left side in FIG. 1, a mark 3 for performing production management or storage management of at least one semiconductor wafer 1 is formed in the marking area MA. The mark 3 is a single number or a combination of a plurality of numbers, symbols, or characters having predetermined information such as a manufacturing number, a model number, and a product name. The mark 3 according to the present embodiment will be described later in a semiconductor wafer process, but is formed by hard marking that physically scatters and removes the surface of the semiconductor wafer 1 by laser light irradiation.

As shown in FIG. 1, the semiconductor chip area 1C
Is provided with an element area TA and an element isolation area FA surrounding the element area TA and electrically isolating elements. Although not limited to this element, in the present embodiment, an n-channel MISFET (Metal Insul
ator Semiconductor Field Effect Transistor) Q is formed. Although not shown, a complementary MISFET is mounted in the semiconductor chip region 1C according to the present embodiment.
A p-channel MISFET is formed. n channel MISFETQ
The semiconductor wafer 1 includes a gate insulating film 5, a gate electrode 6, and a pair of n-type semiconductor regions 7 used as a source region and a drain region, which are formed on a surface portion of a p-type well region 4 provided on a surface portion of the semiconductor wafer 1. Is built. A wiring (metal film) 10 is electrically connected to the n-type semiconductor region 7 through a connection hole 9 formed in the interlayer insulating film 8. Although not shown in detail, a passivation film as a protective film is formed on the wiring 10.

On the other hand, a field oxide film 2 formed by the LOCOS process is formed in the element isolation region FA. Field oxide film 2 is formed of a silicon oxide film obtained by selectively thermally oxidizing the surface of semiconductor wafer 1.

Next, a semiconductor wafer process and a marking method will be described. 3 to 10 are process cross-sectional views of the semiconductor wafer showing the semiconductor wafer process and the marking method according to the present embodiment for each manufacturing process.

(1) The semiconductor wafer process according to the present embodiment uses both the LOCOS process and the retrograde well process. First, as shown in FIG. 3, the device region TA and the device isolation region FA of the semiconductor wafer 1 are used. And a buffer oxide film 1 on the entire surface including the marking area MA.
1. An oxidation resistant mask 12 is sequentially formed. The buffer oxide film 11 is formed of, for example, a silicon oxide film having a thickness of 10 nm to 50 nm, and has a function such as stress relaxation between the semiconductor wafer 1 and the oxidation resistant mask 12. The oxidation resistant mask 12 is formed of, for example, a silicon nitride film having a thickness of 100 nm to 300 nm, and basically prevents oxidation of the element region TA. In the present embodiment, the oxidation-resistant mask 12 is also used as a marking protective film for later hard marking, and is effectively used.

(2) As shown in FIG. 4, except for the element region TA, at least a part of the oxidation resistant mask 12 is removed in the element isolation region FA, and an opening is formed in the element isolation region FA of the oxidation resistant mask 12. 12H is formed. That is, the oxidation-resistant mask 12 having the opening 12H is formed. The opening 12H is formed by etching using a resist mask formed by photolithography.

(3) As shown in FIG. 5, the oxidation resistant mask 1
2, a field oxide film 2 is formed on the surface of the semiconductor wafer 1 in the opening 12H of the oxidation-resistant mask 12 (by growing the buffer oxide film 11 in the element isolation region FA). The field oxide film 2 is formed by, for example, wet oxidation at about 1000 ° C. for about 70 minutes. Field oxide film 1
2 is formed with a film thickness of, for example, 200 nm to 400 nm.

(4) As shown in FIG. 6, in the element region TA, the oxidation-resistant mask 12 is used also as the marking protective film 12, and in the element isolation region FA, the field oxide film 2 is used as the marking protective film 2. In this state, the marking area MA of the semiconductor wafer 1 is irradiated with the laser beam 15 to perform hard marking for physically scattering and removing the surface portion of the semiconductor wafer 1, thereby forming the mark 3 having predetermined information. Due to this hard marking, the scattered substance 1a scatters around the marking area MA, and a part of the scattered scattered substance 1a becomes the scattered substance 1c penetrating the surface of the marking protective film (oxidation resistant mask) 12, and the other part. Is a scattered substance 1b penetrating the surface of the marking protective film (field oxide film) 2.
Although not shown in detail, the marking protective films 12 and 2 are scattered by the collision of the scattered substance 1a having high energy.
Are formed on the respective surfaces of the semiconductor wafer 1 within a range that does not affect the surface of the semiconductor wafer 1.

(5) As shown in FIG. 7, the oxidation resistant mask 12 used as the marking protective film 12 is removed.
The removal of the oxidation resistant mask 12 is performed, for example, with phosphoric acid at about 170 ° C. The oxidation resistant mask 12 is removed by removing the oxidation resistant mask 12.
The scattered substance 1c pierced on the surface is also removed. Needless to say, the scratches generated on the surface of the oxidation resistant mask 12 are not present by the removal of the oxidation resistant mask 12.

(6) As shown in FIG. 8, the buffer oxide film 11 is removed. The removal of the buffer oxide film 11 is performed using, for example, hydrofluoric acid. By removing the buffer oxide film 11, at least the thickness of the buffer oxide film 11 is removed from the surface of the field oxide film 2 formed of the same silicon oxide film. 1b and unillustrated scratches are removed.

A step of forming a buffer oxide film 11, a step of forming an oxidation-resistant mask 12, a step of forming a field oxide film 2,
Step of removing oxidation-resistant mask 12 and buffer oxide film 11
Is basically indispensable to the LOCOS process and is incorporated in the semiconductor wafer process in advance. Therefore, the process of forming the marking protective films 12 and 2 relating to the hard marking, the removing process of the marking protective film 12, and the buffer oxidation The step of removing the surface portion of the field oxide film 2 (cleaning step) accompanying the removal of the film 11 does not increase the number of manufacturing steps. Then, even if the mark 3 is formed by hard marking, the scattering substance 1c does not directly pierce or scratch the surface of the semiconductor wafer 1, especially the surface of the semiconductor wafer 1 in the element region TA.

(7) According to the retrograde well process, a p-type well region 4 is formed on the surface of the semiconductor wafer 1 by high energy ion implantation as shown in FIG. Although not particularly described, an n-type well region is formed in the element region TA where the p-channel MISFET is provided.
In the high-energy ion implantation, an impurity 4W for forming a well region is implanted into the inside of the semiconductor wafer 1 through a buffer oxide film (a silicon oxide film for preventing damage to the surface of the semiconductor wafer 1 by ion implantation) 4A newly formed in at least the element region TA. In the element isolation region FA, the well region forming impurity 4W is implanted into the semiconductor wafer 1 through the field oxide film 2 to activate the well region forming impurity 4W.

(8) The LSI process is performed, and as shown in FIG. 10, the n-channel MISFET Q
Is formed. The n-channel MISFETQ is formed by sequentially forming each of the gate insulating film 5, the gate electrode 6, and the n-type semiconductor region 7.

(9) Then, as shown in FIG.
By sequentially forming the interlayer insulating film 8, the connection hole 9, and the wiring 10, the semiconductor wafer 1 before the dicing step is completed, and the semiconductor wafer process is almost completed.

As described above, in the method for marking the semiconductor wafer 1 according to the present embodiment, at least the surface of the semiconductor wafer (silicon base) 1 having the element region TA, the inter-element separation region FA and the marking region MA is provided. A step of forming an oxidation-resistant mask 12 having an opening 12H in the element isolation area FA, covering the element area TA; and using the oxidation-resistant mask 12, a field oxidation is performed on the surface of the element isolation area FA of the semiconductor wafer 1. A step of forming the film 2, and using the oxidation-resistant mask 12 as a protective film for marking 12, the surface of the semiconductor wafer 1 is physically scattered and removed by hard marking by irradiation with a laser beam 15 to form a mark 3 having predetermined information. Forming on the semiconductor wafer 1.

In such a method for marking a semiconductor wafer 1, the oxidation-resistant mask 12 formed in the element region TA for forming the field oxide film 2 in the element isolation region FA is protected by the marking protective film 1 for hard marking.
2, the marking protective film 12
Need not be formed, and the number of manufacturing steps of the semiconductor wafer process can be reduced. Further, in the inter-element separation area FA, since the mark 3 is formed by hard marking after the field oxide film 2 is formed, the field oxide film 2 is also used as the marking protection film 2, and the marking protection film 2 is formed separately. And the number of manufacturing steps of the semiconductor wafer process can be reduced. Further, since the hard marking is performed in a state where the marking protective film (oxidation-resistant mask) 12 is formed in the element region TA, it is possible to cope with the scattered substance 1a scattered in the element region TA at the time of hard marking. Since there is no defect caused by the flying substance 1a,
The production yield of the semiconductor wafer process can be improved. Furthermore, such a semiconductor wafer 1
In the marking method of (1), the marking can be performed at the initial stage of the semiconductor wafer process in which the field oxide film 2 is formed in the inter-element isolation area FA, so that the management of the semiconductor wafer 1 is surely performed from the initial stage of the process. be able to.

Further, in the method for marking the semiconductor wafer 1 according to the present embodiment, the step of forming the oxidation resistant mask 12 is the step of forming the oxidation resistant mask 12 on the surface of the semiconductor wafer 1 via the buffer oxide film 11. Yes,
The method is characterized in that a step of removing the oxidation-resistant mask 12 after the step of performing the marking, and subsequently removing the buffer oxide film 11 and simultaneously removing the surface portion of the field oxide film 2 is provided.

In such a method of marking the semiconductor wafer 1, the field oxidation is performed by using the step of removing the buffer oxide film 11 formed in the element area TA in order to form the field oxide film 2 in the element isolation area FA. Membrane 2
The scattered substance 1b scattered on the surface can be removed. Accordingly, the step of cleaning the surface portion of the field oxide film 2 (the step of removing the scattered substance 1b), which is also used as the protective film 2 for marking, can be used also in the step of removing the buffer oxide film 11, so that a separate cleaning step is added. This eliminates the need and reduces the number of manufacturing steps of the semiconductor wafer process.

Further, in the method for marking the semiconductor wafer 1 according to the present embodiment, after the step of performing the marking, high energy ion implantation is performed inside the semiconductor wafer 1 in the element region TA and in the element isolation region FA.
In the semiconductor wafer 1 through the field oxide film 2
A step of introducing a well region forming impurity 4W therein and activating the well region forming impurity 4W to form the well region 4 is provided.

In such a method of marking the semiconductor wafer 1, the field oxide film 2 is formed in the element isolation region FA, and the well region 4 is formed after the marking is performed. Therefore, the well region 4 in the semiconductor wafer process is formed.
Marking can be performed at an early stage before formation. Therefore, the management of the semiconductor wafer 1 can be reliably performed from the initial stage of the process. Further, in the method for marking the semiconductor wafer 1, the marking can be performed in the middle of the retrograde well process in which the well region 4 is formed by high-energy ion implantation after the field oxide film 2 is formed. Compatibility with the process can be ensured.

The present invention is not limited to the above embodiment. For example, in the present invention, the marking area MA is set to overlap the element isolation area FA, and the mark reaching the surface portion of the semiconductor wafer 1 under the field oxide film 2 through the field oxide film 2 or through the field oxide film 2. 3
Can be formed. Further, the present invention provides a scribe region 1S in the semiconductor wafer 1 shown in FIG.
May be set to the marking area MA.

Further, in the present invention, marking may be performed directly on a silicon substrate such as an epitaxial layer grown on the surface of the semiconductor wafer 1 or a silicon layer deposited on the surface of the semiconductor wafer 1 by the SOI technique.

[0049]

According to the present invention, a semiconductor capable of reducing the number of manufacturing steps and improving the manufacturing yield while using a hard marking method capable of realizing a low capital investment and a low manufacturing cost. A method for marking a wafer can be provided. In particular, the present invention provides a semiconductor wafer marking method capable of reducing the number of manufacturing steps and improving the manufacturing yield by effectively utilizing a mask for forming an element isolation region. Can be.

Further, in addition to the above-mentioned effects, the present invention makes it possible to further reduce the number of manufacturing steps and improve the manufacturing yield by effectively utilizing the process of forming an element isolation region. A method for marking a wafer can be provided.

Further, the present invention can provide a method for marking a semiconductor wafer which can ensure compatibility with a retrograde well process in addition to the above-mentioned effects.

[Brief description of the drawings]

FIG. 1 is a sectional view of a principal part of a semiconductor wafer according to an embodiment of the present invention.

FIG. 2 is a perspective view of a semiconductor wafer according to the embodiment.

FIG. 3 is a first process cross-sectional view of the semiconductor wafer showing a semiconductor wafer process and a marking method according to the embodiment;

FIG. 4 is a second process cross-sectional view of the semiconductor wafer showing a semiconductor wafer process and a marking method according to the embodiment;

FIG. 5 is a third process sectional view of the semiconductor wafer showing a semiconductor wafer process and a marking method according to the embodiment;

FIG. 6 is a fourth process sectional view of the semiconductor wafer, illustrating a semiconductor wafer process and a marking method according to the embodiment;

FIG. 7 is a fifth process cross-sectional view of the semiconductor wafer, illustrating a semiconductor wafer process and a marking method according to the embodiment;

FIG. 8 is a sixth process sectional view of the semiconductor wafer, illustrating a semiconductor wafer process and a marking method according to the embodiment;

FIG. 9 is a seventh process cross-sectional view of the semiconductor wafer, illustrating a semiconductor wafer process and a marking method according to the embodiment;

FIG. 10 is a sectional view of an eighth step of the semiconductor wafer, illustrating a semiconductor wafer process and a marking method according to the embodiment;

FIG. 11 is a process sectional view showing a marking process by a soft marking method according to a conventional technique.

FIG. 12 is a process cross-sectional view showing a marking process by a hard marking method according to a conventional technique.

FIG. 13 is a process cross-sectional view showing a marking process by a hard marking method according to a conventional technique.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 semiconductor wafer 1 a to 1 c scattering substance 2 field oxide film or protective film for marking 3 mark 4 well region 5 gate insulating film 6 gate electrode 7 semiconductor region 8 interlayer insulating film 9 connection hole 10 wiring 11 buffer oxide film 12 oxidation resistant mask or Marking protective film 12H Opening 15 Laser beam Q MISFET MA Marking area FA Inter-element separation area TA element area 1C Semiconductor chip area

Claims (3)

[Claims] 1. A step of forming an oxidation-resistant mask on a surface of a silicon substrate having an element region, an inter-element separation region, and a marking region, at least covering the element region and having an opening formed in the inter-element separation region; Forming a field oxide film on the surface of the inter-element isolation region of the silicon substrate using an oxidation mask; and irradiating the surface of the silicon substrate or the surface of the field oxide film with a laser using the oxidation-resistant mask as a protective film for marking. Forming a mark having predetermined information on a silicon substrate by physically scatter-removing with hard marking according to the above method. 2. The method for marking a semiconductor wafer according to claim 1, wherein the step of forming the oxidation-resistant mask is a step of forming an oxidation-resistant mask on a surface of a silicon substrate via a buffer oxide film. A method for marking a semiconductor wafer, comprising a step of removing the oxidation-resistant mask after the step of performing the marking, and simultaneously removing the buffer oxide film and simultaneously removing a surface portion of the field oxide film. 3. The method for marking a semiconductor wafer according to claim 1, wherein after the step of performing the marking, the field is implanted into the silicon substrate in an element region by ion implantation and the field in an element isolation region. A method for marking a semiconductor wafer, comprising the steps of: introducing a well region forming impurity into an inside of a silicon substrate through an oxide film; and activating the well region forming impurity to form a well region.