JP2003151866A - Semiconductor device manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique to easily perform the marking of a large step by preventing the adhesion of foreign materials. SOLUTION: In the method of manufacturing semiconductor device to perform patterning by partially removing an insulation film formed on a semiconductor wafer such as the marking of an ID number given to the semiconductor wafer, the insulation film is removed by irradiating a DUV laser which is aligned in the wavelength to the absorbing end of the insulation material forming the insulation film. According to this structure, since the insulation film can be removed by cutting in direct the molecular coupling of the insulation material, the generation of foreign materials due to the re-adhesion of the removed material can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a technique most effectively applied to marking a wafer on which a semiconductor device is formed.

[0002]

2. Description of the Related Art In the manufacture of semiconductor devices, semiconductor elements or wiring patterns are collectively formed in a plurality of element forming regions provided on a wafer such as single crystal silicon to form a predetermined circuit, and adjacent elements are formed. The wafer is cut in the scribing region between the formation regions, and dicing is performed to separate each element formation region into individual semiconductor chips, and the individual semiconductor chips thus separated are fixed to, for example, a base substrate or a lead frame. A semiconductor device is completed through a mounting process such as die bonding and wire bonding and a sealing process such as resin sealing.

In the wafer process for manufacturing such a semiconductor device, a unique wafer ID such as a lot number, a wafer number and a product name is marked on the wafer for the purpose of identifying each wafer and contributing to quality control or production control. This I
By recording the manufacturing history such as processing conditions and processing history for each wafer based on the D number, for example, by tracing the manufacturing history of the wafer when a defect occurs,
It is possible to shorten the period for investigating the cause of the cause and to improve the yield at an early stage or take an action against the cause at an early stage.

In the marking of such a wafer, a resist mask having an ID number pattern is formed by using a photolithography technique, and marking is performed by a groove or a convex portion formed by etching using this mask, or a YAG laser. Alternatively, a method of irradiating a wafer with a CO ₂ laser to form a pattern by damage such as carbonization or melting applied to the surface of the wafer and performing marking is performed.

[0005]

In the method of marking by etching using the photolithography technique, it takes a lot of time for the etching process to form a deep groove or a high convex portion having a large step. Therefore, since the step formed is small, as the process progresses and various film forming processes are performed, the groove of the marking becomes gradually shallower and the step becomes smaller.
It becomes difficult to identify the number.

Further, in the marking by the laser irradiation, there is a case that fine pieces of silicon, which is a substrate material, are scattered by a substrate damage caused by the irradiation, and a foreign matter which causes a defect is generated.

An object of the present invention is to solve these problems and to provide a technique capable of preventing foreign matter from adhering and easily marking a large step.
The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0008]

Among the inventions disclosed in the present application, a brief description will be given to the outline of typical ones.
It is as follows. In a method of manufacturing a semiconductor device in which an insulating film formed on a semiconductor wafer, such as an ID number marking on a semiconductor wafer, is partially removed and patterned, a wavelength is provided at an absorption edge of an insulating material forming the insulating film. The insulating film is removed by irradiation with a DUV laser.

According to the present invention described above, since the insulating film can be removed by directly breaking the molecular bond of the insulating material, it is possible to prevent the generation of foreign matter due to the reattachment of the removed material, The number of steps can be reduced as compared with marking by photolithography, and marking of a large step can be easily performed.

Embodiments of the present invention will be described below. In all the drawings for explaining the embodiments, the same reference numerals are given to those having the same function, and the repeated description thereof will be omitted.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION (Embodiment 1) In the marking, which is an embodiment of the present invention, an insulating film made of an insulating material such as silicon oxide or silicon nitride is provided with an absorption edge peculiar to each insulating material. Irradiate a DUV (Deep Ultra Violet) laser that matches the wavelength. Although Si and N are bonded in the silicon nitride film, the bond dissociation energy of Si ₃ N ₄ is about 105 Kca.
1 / mol, the DUV laser has much higher photon energy than the conventional YAG laser or CO ₂ laser, and the wavelength matching the wavelength of the absorption edge of Si ₃ N ₄ is DUV.
With the laser light of 260 nm, which is the region, the photon energy is 107 Kcal / mol, and photon energy exceeding the bond dissociation energy is obtained. Therefore, the molecular bond of Si ₃ N ₄ is easily cut directly by this irradiation, and the insulating material is separated. It can be decomposed and removed into nitrogen gas and silicon.

For this reason, the sublimated silicon is decomposed on an atomic scale, and even if it adheres to the semiconductor substrate, it does not reach a size that poses a problem as a foreign substance. Further, if nitrogen and silicon sublimated by exhausting are exhausted, they are hardly attached to the semiconductor substrate.

Similarly, if the insulating film is a silicon oxide film, S
iO_TwoBond dissociation energy of about 191 Kcal / mo
l and SiO_TwoThe wavelength matched to the absorption edge of is 15
It is most efficient to irradiate a laser beam of about 0 nm
By this irradiation, SiO _TwoDirectly breaks the molecular bond of
However, it can be decomposed into oxygen gas and silicon.

The flowchart of FIG. 1 shows the marking according to the present embodiment, and FIG. 2 is a partial vertical sectional view showing the marked wafer. First,
The semiconductor substrate 1 to be marked is washed to remove the deposits on the surface, and then the silicon oxide film 2 is formed on the surface of the semiconductor substrate 1. Next, a silicon nitride film 3 for marking is formed on the silicon oxide film 2. The silicon nitride film 3 is formed on the semiconductor substrate 1 via the silicon oxide film 2 in order to prevent the semiconductor substrate 1 from being strained by the formation of the silicon nitride film 3.

In the ID marking of the present embodiment, as shown in FIG.
As shown in, the DUV laser light source 4 is formed on the silicon nitride film 3.
Is irradiated with DUV laser light having a wavelength matched with the wavelength of the absorption edge of Si ₃ N _4, the beam to be irradiated is a mask 5 having a size matched to a character such as a numeral or letter of an ID number to be marked, Pattern formation is sequentially performed for each character.

A beam which is partially shielded by the mask 5 and has a predetermined pattern is applied to the silicon nitride film 3 on the wafer 7 through the optical system lens 6. Such irradiation
The mask 5 is changed depending on the character, and the irradiation position is changed by the scanning mirror 8 to perform a character-by-character sequence in order to form a pattern of a required ID number and perform ID marking.

In such marking for each character, marking can be performed with a beam having an appropriate spot diameter, and the mask 5 to be used may be prepared by preparing a limited number of masks 5 such as numbers or alphabets. When forming all patterns at once, the required output becomes large because the beam spot diameter becomes large, and different masks must be prepared for each wafer.

Thus, in the marking of this embodiment,
As shown in the vertical cross-sectional view of FIG. 2, a pattern is formed on the silicon nitride film 3 by a groove in which silicon nitride is decomposed and removed. Usually, such an insulating film has a sufficient step difference to be formed to a thickness of several hundred nm. It is possible to carry out marking.

In conventional marking by irradiation with laser light, the silicon nitride melted by thermal decomposition is recombined and scattered and adheres to become foreign matter. In particular, the melted silicon nitride is deposited around the groove formed as shown by the broken line. As a result, a raised protrusion is formed, which impairs the smooth surface when forming a fine pattern with high accuracy, which may be an obstacle to the subsequent steps. In the marking of this embodiment, Si ₃ N _{4 is used.} Since the molecular bond of is directly broken and decomposed into nitrogen gas and silicon, the sublimated silicon has an atomic scale, and even if it adheres to the semiconductor substrate, it does not cause a problem as a foreign substance. It does not stick firmly to. In addition,
If the sublimated nitrogen and silicon are exhausted by exhausting, they are hardly attached to the semiconductor substrate.

For marking, the spot diameter of the laser beam may be set to a small diameter of about several tens of nm, and characters such as numbers and letters may be directly drawn without using a mask as shown in FIG.

In this method, the DUV laser light source 4 to D
UV laser light is emitted, but the beam to be emitted is controlled by the control computer 10 to scan data such as characters such as numbers and letters of ID numbers to be marked or data 9 such as circuit data formed on the wafer 7 by the control computer 10. Then, the scan mirror control unit 11 operates the scanning mirror 8 to operate the path of the laser light, and directly draws the character to form a pattern on the character.

Next, data 9 such as wafer position information is transferred to the XY stage controller 1 by the control computer 10.
2, the XY stage controller 12 operates the XY stage 13 to change the position of the wafer 4 to directly draw the next character, and the marking is performed by repeating this.

In the marking of this embodiment, the number of steps can be reduced as compared with the marking using the conventional photolithography technique. In the conventional marking using the photolithography whose flow chart is shown in FIG. 5, after forming the silicon nitride film 3, a photoresist is applied, the ID number is exposed using a mask, and the exposed photoresist is developed to form a resist mask. It is necessary to form the pattern of the ID number by etching using this resist mask and remove the resist mask by ashing, which requires many steps as compared with the marking of the present embodiment. .

Although the present invention has been specifically described based on the above embodiment, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the invention. Of course.

For example, a pad serving as an external terminal of a semiconductor chip has a protective insulating film covering the entire surface partially opened to expose the conductor film. However, the mask pattern used for this opening is defective or is etched for opening. When the conductor film of the pad is covered with the insulating film due to lack, the present invention can be applied to the removal of the insulating film for exposing the conductor film.

[0026]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows. (1) According to the present invention, the molecular bond of the insulating material can be directly broken and the insulating film can be decomposed and removed by the irradiation of the DUV laser light matched with the wavelength of the absorption edge of the insulating material forming the insulating film. The effect is that you can do it. (2) According to the present invention, due to the above effect (1), it is possible to prevent foreign matter from adhering to the semiconductor substrate. (3) According to the present invention, due to the above effect (1), it is possible to easily form a pattern having a large step. (4) According to the present invention, due to the above effect (1), there is an effect that the number of steps can be reduced as compared with marking by photolithography. (5) According to the present invention, due to the above effect (2), it is possible to prevent the generation of defective products. (6) According to the present invention, due to the above effect (3), it is easy to confirm the marking.

[Brief description of drawings]

FIG. 1 is a flowchart illustrating marking, which is an embodiment of the present invention.

FIG. 2 is a partial vertical cross-sectional view showing a marked wafer according to one embodiment of the present invention.

FIG. 3 is a configuration diagram showing marking pattern formation according to an embodiment of the present invention.

FIG. 4 is a configuration diagram showing a modified example of marking pattern formation according to an embodiment of the present invention.

FIG. 5 is a flowchart illustrating marking using a conventional photolithography technique.

[Explanation of symbols]

1 ... Semiconductor substrate, 2 ... Silicon oxide film, 3 ... Silicon nitride film, 4
... DUV laser light source, 5 ... mask, 6 ... optical system lens,
7 ... Wafer, 8 ... Scanning mirror, 9 ... Data, 10
... control computer, 11 ... scan mirror control unit,
12 ... XY stage controller, 13 ... XY stage.

Claims (5)

[Claims] 1. A method of manufacturing a semiconductor device in which an insulating film formed on a semiconductor wafer is partially removed and patterned, wherein a DUV laser is tuned to the absorption edge of an insulating material forming the insulating film. A method for manufacturing a semiconductor device, characterized in that the insulating film is removed by means of. 2. The method for manufacturing a semiconductor device according to claim 1, wherein the patterning is marking of an ID number attached to the semiconductor wafer. 3. The method for manufacturing a semiconductor device according to claim 1, wherein the insulating film is a silicon nitride film, and the wavelength of the laser to be irradiated is about 260 nm. 4. The method of manufacturing a semiconductor device according to claim 1, wherein the insulating film is a silicon oxide film, and the wavelength of the laser to be irradiated is about 150 nm. 5. The method of manufacturing a semiconductor device according to claim 2, wherein the patterning is performed for each character of the ID number by using a mask.