TWI641045B - Etching method, etching device and semiconductor wafer dividing method - Google Patents

Abstract

The invention provides an etching method, an etching device and a method for dividing a semiconductor wafer. One method for dividing a semiconductor wafer includes the following steps: providing a semiconductor wafer on which a plurality of integrated circuits are formed, and a gap is provided between the plurality of integrated circuits; The plasma etching gas is sprayed to etch the gaps between the plurality of integrated circuits, so that the plurality of integrated circuits are separated one by one. The invention proposes a method and a device for etching by using a nozzle to emit a laser and a plasma etching gas, so that the method and the device can be used to realize the division of a semiconductor wafer. The semiconductor wafer slicing method of the present invention avoids the stress caused by dicing with a conventional dicing blade, effectively reduces problems such as chipping and debris caused by dicing, and is suitable for dicing and slicing of thin wafers. The method is simple, fast, Efficient.

Description

   Etching method, etching device and semiconductor wafer dividing method   

The present invention relates to the field of microelectronic technology, and in particular, to an etching method, an etching device, and a method for dividing a semiconductor wafer.

On a semiconductor wafer, there are usually hundreds to thousands of die. There is a gap between these die, and they need to be diced Saw to separate them. However, the traditional dicing and dicing is easy to generate stress and cause the edges to crack, leading to chipping of the bare wafer, especially for devices formed on thin wafers, such as power devices and BSI-type CMOS image sensors. The wafer thickness of the device is usually as thin as 50 μm, and it is very easy to chip during dicing.

Some current solutions use patterned photoresist combined with conventional dry etching for dicing. In addition, Japanese patent application JP2003257896A discloses a method for singulating a semiconductor wafer. This method uses a polishing tape and a dry etching method to implement wafer dicing; by attaching a tape on the top surface of the wafer, and then cutting the tape to expose a scribe area Then, the wafer is divided by dry etching under the protection of an adhesive tape. U.S. patent application US20110312157A1 discloses a dicing method for a semiconductor wafer, which uses femtosecond laser and plasma etching to realize wafer dicing; by forming a mask on the wafer surface, and then using the femtosecond laser to cut the mask Expose the scribe lane, and then use plasma etching to The wafer is divided under the protection of a mask.

However, the process steps of the conventional solutions are more complicated and the production efficiency is lower. Therefore, it is necessary to find a more efficient and simple dicing technology for thin wafers.

In view of the foregoing prior art, an object of the present invention is to provide an etching method, an etching device, and a method for dividing a semiconductor wafer, which are used to solve the problem that the dicing of a thin wafer in the prior art is easily broken.

In order to achieve the above object and other related objects, the present invention provides an etching method including the steps of: using a nozzle to emit a laser and ejecting a plasma etching gas to etch an area of a target material to be etched.

Preferably, the plasma etching gas is a dry etching gas of the target material.

Preferably, the plasma etching gas is activated by the laser.

Preferably, the laser is an ultraviolet femtosecond laser.

More preferably, the ultraviolet femtosecond laser has a pulse width of 10-500 femtoseconds, a wavelength of 200-1570 nm, a pulse repetition frequency of 200 kHz-10 MHz, a pulse energy of 0.5-100 μJ, and a diameter of a focal point of 3-15 μm.

In order to achieve the above-mentioned object and other related objects, the present invention also provides an etching device including: an air cavity, an air inlet, a nozzle, and a laser emitting unit; the air cavity includes a top portion, a bottom portion opposite to the top portion, and a connection Side walls of the top and bottom; the air inlet is located on a side wall of the air cavity; the nozzle is located at the bottom of the air cavity; The laser emission unit is located on the top of the air cavity, and the laser emission starts the gas in the air cavity into a plasma state, and the emitted laser light passes through the air cavity and is emitted from the nozzle.

Preferably, the laser emission unit is an ultraviolet femtosecond laser emission device.

Preferably, the diameter of the nozzle is 10-80 μm.

In order to achieve the above object and other related objects, the present invention also provides a method for dividing a semiconductor wafer, which includes the following steps: providing a semiconductor wafer having a plurality of integrated circuits formed on the semiconductor wafer, and the plurality of integrated circuits A gap is provided between the circuits; a laser is emitted from a nozzle and a plasma etching gas is emitted to etch the gaps between the plurality of integrated circuits, so that the plurality of integrated circuits are separated one by one.

Preferably, the semiconductor wafer is a silicon wafer, and the plasma etching gas is a dry etching gas of silicon.

More preferably, the dry etching gas of silicon includes one or more of etching reaction gases ClF ₃ , Cl ₂ , and HCl, and one or more carrier gases selected from He, Ar, and N 2.

Preferably, the laser is an ultraviolet femtosecond laser.

More preferably, the ultraviolet femtosecond laser has a pulse width of 10-500 femtoseconds, a wavelength of 200-1570 nm, a pulse repetition frequency of 200 kHz-10 MHz, a pulse energy of 0.5-100 μJ, and a diameter of a focal point of 3-15 μm.

More preferably, the pulse width of the ultraviolet femtosecond laser is 100-400 femtoseconds, the wavelength is 200-540 nm, the pulse repetition frequency is 500 kHHz-5 MHz, the pulse energy is 1-5 μJ, and the diameter of the focal point is 5-10 μm.

In order to achieve the above-mentioned object and other related objects, the present invention also provides a method for dividing a semiconductor wafer, including the following steps: providing a semiconductor wafer, wherein a plurality of integrated circuits are formed on the semiconductor wafer, and the plurality of integrated circuits are formed on the semiconductor wafer; A gap is provided between the body circuits; a mask layer is formed on the semiconductor wafer, and the mask layer covers and protects the integrated circuit; a nozzle is used to emit a laser and a plasma etching gas is used to pattern the mask A cover layer to expose a gap between a plurality of integrated circuits on the semiconductor wafer; and dividing the semiconductor wafer through the exposed gap.

Preferably, the masking layer is a silicon oxide layer, and the plasma etching gas for patterning the masking layer is a dry etching gas of silicon oxide.

More preferably, the dry etching gas of silicon oxide includes an etching reaction gas HF or H ₂ O, and one or more carrier gases selected from He, Ar, and N ₂ .

Preferably, the laser is an ultraviolet femtosecond laser.

More preferably, the ultraviolet femtosecond laser has a pulse width of 10-500 femtoseconds, a wavelength of 200-1570 nm, a pulse repetition frequency of 200 kHz-10 MHz, a pulse energy of 0.5-100 μJ, and a diameter of a focal point of 3-15 μm.

More preferably, the pulse width of the ultraviolet femtosecond laser is 100-400 femtoseconds, the wavelength is 200-540 nm, the pulse repetition frequency is 500 kHHz-5 MHz, the pulse energy is 1-5 μJ, and the diameter of the focal point is 5-10 μm.

Preferably, dividing the semiconductor wafer by the exposed gap is to place the semiconductor wafer in a dry etching equipment after patterning the mask layer to perform exposure of the mask layer. The dry etching separates the multiple integrated circuits one by one.

Preferably, dividing the semiconductor wafer by the exposed gap is to use a nozzle to emit a laser and spray a plasma etching gas to etch the gap exposed by the mask layer after patterning the mask layer. Separate the multiple integrated circuits one by one.

As described above, the etching method, the etching device, and the semiconductor wafer dividing method of the present invention have the following beneficial effects: The invention proposes a method and a device for emitting a laser using a nozzle and a plasma etching gas for etching, so that the method and the device can be used to realize the division of a semiconductor wafer. The semiconductor wafer slicing method of the present invention avoids the stress caused by dicing with a conventional dicing blade, effectively reduces problems such as chipping and chipping caused by dicing, and is suitable for dicing and slicing of thin wafers. On the one hand, the plasma etching gas can be started, and on the other hand, the etching efficiency can be accelerated. Compared with the prior art, the method of the present invention is simpler, faster and more efficient. In addition, the present invention also provides a technical solution of using a nozzle to emit a laser and spraying plasma etching gas to pattern a mask layer, and then dicing the mask layer under the protection of the mask layer, which can effectively protect thin wafers and improve production yield.

S101 ~ S102, S201 ~ S204‧‧‧steps

101‧‧‧air cavity

102‧‧‧air inlet

103‧‧‧ Nozzle

104‧‧‧Laser Launch Unit

1‧‧‧etching device

2‧‧‧ semiconductor wafer

3‧‧‧Tape

FIG. 1 is a schematic diagram of an etching apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of a method for dividing a semiconductor wafer according to a second embodiment of the present invention.

FIG. 3 is a schematic view showing a second embodiment of the present invention using a nozzle to emit a laser and eject a plasma etching gas to divide a semiconductor wafer.

FIG. 4 is a schematic diagram of a method for dividing a semiconductor wafer according to a third embodiment of the present invention.

The present invention is further described in detail below with reference to the drawings and specific embodiments. The advantages and features of the present invention will be clearer according to the description of this case and the scope of patent application. It should be noted that the drawings are all in a very simplified form, and all use inaccurate proportions, which are only used to facilitate and clearly explain the purpose of the embodiments of the present invention.

Examples

Example one

This embodiment provides an etching method, which includes the following steps: using a nozzle to emit a laser and spraying plasma etching gas to etch an area of a target material to be etched.

Specifically, the plasma etching gas is a dry etching gas of the target material. The plasma etching gas is activated by the laser. The laser is an ultraviolet femtosecond laser.

The pulse width of the ultraviolet femtosecond laser can be 10-500 femtoseconds, the wavelength can be 200-1570nm, the pulse repetition frequency can be 200kHz-10MHz, and the pulse energy can be 0.5-100μJ. When the ultraviolet femtosecond laser is emitted, the laser can be focused on the surface of the area to be etched, and the focal diameter of the laser can be 3-15 μm. Specific ultraviolet femtosecond laser parameters can be adjusted according to the needs of different etching gases and etching effects.

The etching method can achieve high-efficiency rapid etching and cutting under the combined action of laser and plasma etching gas, and move the nozzle according to the line path or pattern of the etching to achieve rapid etching of simple lines or patterns.

In order to realize the above-mentioned etching method, this embodiment further provides an etching device with a nozzle. Referring to FIG. 1, the etching apparatus includes: an air cavity 101, an air inlet 102, a nozzle 103, and a laser emitting unit 104; the air cavity 101 includes a top portion, a bottom portion opposite to the top portion, and a connection to the top portion And the side wall of the bottom; the air inlet 102 is located on the side wall of the air cavity 101; the nozzle 103 is located on the bottom of the air cavity 101; the laser emission unit 104 is located on the top of the air cavity 101 The firing laser activates the gas in the air cavity 101 into a plasma state, and causes the emitted laser to pass through the air cavity 101 to be emitted from the nozzle 103.

As a preferred solution of this embodiment, the laser emitting unit 104 is an ultraviolet femtosecond laser emitting device. The parameters such as the wavelength, power, and pulse energy of the emitted laser can be determined by Laser emission unit is adjusted. The diameter of the nozzle can be 10-80 μm. The design of the size of the nozzle needs to allow the laser to pass through, and the sharp nozzle can etch thinner lines.

When the etching device is in operation, an air inlet 102 located on a side wall of the air cavity 101 passes gas into the air cavity 101, and a laser emitting unit 104 located on the top of the air cavity 101 emits a laser with a required parameter, and emits The laser passing through the air cavity 101 activates the gas in the air cavity 101 into a plasma state, and then ejects it through the nozzle 103; the activated plasma etching gas in the air cavity 101 also ejects from the nozzle 103.

During the etching, the material to be etched can be placed on an operation table with a vacuum or electrostatic chuck.

Example two

Please refer to FIG. 2. This embodiment provides a method for dividing a semiconductor wafer, which includes the following steps: S101 provides a semiconductor wafer, a plurality of integrated circuits are formed on the semiconductor wafer, and a plurality of integrated circuits are formed between the plurality of integrated circuits. A gap is provided; S102 uses a nozzle to emit a laser and emit a plasma etching gas to etch the gaps between the plurality of integrated circuits to separate the plurality of integrated circuits one by one.

In this embodiment, the semiconductor wafer is a silicon wafer, and the plasma etching gas is a dry etching gas of silicon, that is, a gas used when performing dry etching of a silicon material. In this embodiment, preferably, the dry etching gas for silicon includes one or more of etching reaction gases ClF ₃ , Cl ₂ , and HCl, and one or more carrier gases selected from He, Ar, and N ₂ .

As a preferred solution of this embodiment, in step S102, the laser is an ultraviolet femtosecond laser. The pulse width of the ultraviolet femtosecond laser may be 10-500 femtoseconds, preferably 100-400 femtoseconds, the wavelength can be 200-1570nm, preferably 200-540nm, the pulse repetition frequency can be 200kHz-10MHz, preferably 500kHHz-5MHz, and the pulse energy can be 0.5-100μJ, preferably 1-5μJ . When the ultraviolet femtosecond laser is emitted, the laser can be focused on the surface of the area to be etched, and the focal diameter of the laser can be 3-15 μm, preferably 5-10 μm.

As a preferred solution of this embodiment, the diameter of the nozzle used in step S102 may be 10-80 μm to form a thinner divided line.

As shown in FIG. 3, during the specific operation, an adhesive tape 3 can be affixed to the semiconductor wafer 2 to fix the position of the semiconductor wafer 2 and avoid situations such as the shifting of the single wafer after the division. The semiconductor wafer 2 with the adhesive tape 3 can be placed on an operation table with a vacuum or electrostatic chuck, and etched by an etching device 1 with a nozzle, and the etching device 1 is moved according to a required cutting path, for example, along a semiconductor crystal. The scribe lane provided on the circle 2 moves to realize dicing of the wafer. When the wafer is divided by the method of this embodiment, the cutting speed, that is, the speed of moving the nozzle, may be 500 mm / sec to 5 m / sec, and preferably 600 mm / sec to 2 m / sec.

Example three

Please refer to FIG. 4, this embodiment provides a method for dividing a semiconductor wafer by using a mask layer, which includes the following steps: S201 provides a semiconductor wafer having a plurality of integrated circuits formed on the semiconductor wafer. A gap is provided between each integrated circuit; S202 forms a masking layer on the semiconductor wafer, and the masking layer covers and protects the integrated circuit; S203 uses a nozzle to emit a laser and emit a plasma etching gas pattern Masking the mask layer to expose gaps between a plurality of integrated circuits on the semiconductor wafer; S204 divides the semiconductor wafer through the exposed gap.

In step S203, the patterning of the mask layer is mainly to etch lines on the mask layer according to the scribe line position of the semiconductor wafer, so that the scribe line on the semiconductor wafer can be exposed, that is, the Gap between multiple integrated circuits. In this embodiment, the mask layer is a silicon oxide layer, and the plasma etching gas for patterning the mask layer is a dry etching gas of silicon oxide. The dry etching gas of silicon oxide refers to a gas used in dry etching of a silicon oxide material. In this embodiment, preferably, the dry etching gas of silicon oxide includes an etching reaction gas HF or H ₂ O, and one or more carrier gases selected from He, Ar, and N ₂ .

As a preferred solution of this embodiment, in step S203, the laser is an ultraviolet femtosecond laser. The pulse width of the ultraviolet femtosecond laser may be 10-500 femtoseconds, preferably 100-400 femtoseconds, the wavelength may be 200-1570nm, preferably 200-540nm, and the pulse repetition frequency may be 200kHz-10MHz. It is preferably 500kHHz-5MHz, and the pulse energy may be 0.5-100 μJ, and preferably 1-5 μJ. When the ultraviolet femtosecond laser is emitted, the laser can be focused on the surface of the area to be etched, and the focal diameter of the laser can be 3-15 μm, preferably 5-10 μm.

In step S204, the semiconductor wafer is divided by the exposed gap, and a conventional dry etching method may be adopted. For example, after the mask layer is patterned, the semiconductor wafer is placed in a dry etching device to align the semiconductor wafer. The exposed gaps of the mask layer are dry-etched to separate the integrated circuits one by one. Specific dry etching parameters are known to those skilled in the art, and will not be repeated here.

As a preferred solution of this embodiment, the semiconductor wafer is divided by the exposed gap in step S204, and the etching method of the present invention may also be used. For example, the semiconductor wafer division method described in the second embodiment may be adopted. . Specifically, the mask is graphically displayed. After the layer is used, a nozzle is used to emit a laser and a plasma etching gas is used to etch the gaps exposed by the mask layer to separate the multiple integrated circuits one by one. The laser used is preferably an ultraviolet femtosecond laser, and the pulse width of the ultraviolet femtosecond laser may be 10-500 femtoseconds, preferably 100-400 femtoseconds, and the wavelength may be 200-1570 nm, preferably 200-540nm, the pulse repetition frequency may be 200kHz-10MHz, preferably 500kHHz-5MHz, and the pulse energy may be 0.5-100μJ, preferably 1-5μJ. When the ultraviolet femtosecond laser is emitted, the laser can be focused on the surface of the area to be etched, and the focal diameter of the laser can be 3-15 μm, preferably 5-10 μm.

For specific etching, the etching device described in the first embodiment can be used to first pass in the dry etching gas of silicon oxide, adjust the laser parameters to pattern the mask layer, and then stop the dry etching gas of silicon oxide. Instead, the dry etching gas of silicon is passed in, the laser parameters are adjusted, and then the semiconductor wafer is etched under the protection of the mask layer to realize the scribe division of the wafer. In order to save time, two etching devices can also be used, which are respectively used for patterning the mask layer and dicing the semiconductor wafer.

In summary, the present invention provides a method and a device for etching by using a nozzle to emit a laser and a plasma etching gas, so that the method and the device can be used to achieve the division of a semiconductor wafer. The semiconductor wafer slicing method of the present invention avoids the stress caused by dicing with a conventional dicing blade, effectively reduces problems such as chipping and debris caused by dicing, and is suitable for dicing and slicing of thin wafers. Among them, the emitted laser On the one hand, the plasma etching gas can be started, and on the other hand, the etching efficiency can be accelerated. Compared with the prior art, the method of the present invention is simpler, faster and more efficient. In addition, the present invention also provides a technical solution of using a nozzle to emit a laser and spraying plasma etching gas to pattern a mask layer, and then dicing the mask layer under the protection of the mask layer, which can effectively protect thin wafers and improve production yield. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

The content of the specific embodiments described above is used to describe the present invention in detail. However, these embodiments are only used for illustration and are not intended to limit the present invention. Those skilled in the art can understand that various changes or modifications made to the present invention without departing from the scope defined by the scope of the attached patent application fall into a part of the present invention.

Claims (16)

An etching method is characterized by comprising the steps of: using a nozzle to emit a laser and ejecting a plasma etching gas to etch an area of a target material to be etched, wherein the laser is an ultraviolet femtosecond laser, and the ultraviolet The pulse width of the second laser is 10-500 femtoseconds, the wavelength is 200-1570nm, the pulse repetition frequency is 200kHz-10MHz, the pulse energy is 0.5-100μJ, and the diameter of the focal point is 3-15μm. For example, the etching method according to item 1 of the patent application scope is characterized in that the plasma etching gas is a dry etching gas of the target material. The etching method according to item 1 of the patent application range, wherein the plasma etching gas is activated by the laser. An etching device, comprising: an air cavity, an air inlet, a nozzle, and a laser emitting unit; the air cavity includes a top portion, a bottom portion opposite to the top portion, and a side wall connecting the top portion and the bottom portion The air inlet is located at a side wall of the air cavity; the nozzle is located at the bottom of the air cavity; the laser emission unit is located at the top of the air cavity, and emits laser light to the gas in the air cavity Start into the plasma state, and make the emitted laser light pass through the air cavity and exit from the nozzle. The etching device according to item 4 of the scope of patent application, wherein the laser emission unit is an ultraviolet femtosecond laser emission device. For example, the etching device according to item 4 of the patent application scope is characterized in that the nozzle diameter is 10-80 μm. A method for dividing a semiconductor wafer, comprising the steps of: providing a semiconductor wafer on which a plurality of integrated circuits are formed, and a gap is provided between the plurality of integrated circuits; using a nozzle The laser is emitted and the plasma etching gas is ejected to etch the gaps between the plurality of integrated circuits, so that the plurality of integrated circuits are separated one by one, wherein the laser is an ultraviolet femtosecond laser, and The ultraviolet femtosecond laser has a pulse width of 10-500 femtoseconds, a wavelength of 200-1570 nm, a pulse repetition frequency of 200 kHz-10 MHz, a pulse energy of 0.5-100 μJ, and a diameter of a focal point of 3-15 μm. For example, the method for singulating a semiconductor wafer according to item 7 of the patent application scope, wherein the semiconductor wafer is a silicon wafer, and the plasma etching gas is a dry etching gas of silicon. For example, the method for dividing a semiconductor wafer according to item 8 of the application, wherein the dry etching gas of silicon includes one or more etching reaction gases selected from ClF ₃ , Cl ₂ , and HCl, and selected from He and Ar. One or more of N ₂ carry gas. For example, the method for slicing a semiconductor wafer according to item 7 of the scope of patent application, wherein the ultraviolet femtosecond laser has a pulse width of 100-400 femtoseconds, a wavelength of 200-540nm, a pulse repetition frequency of 500kHz-5MHz, The energy is 1-5 μJ, and the diameter of the focal point is 5-10 μm. A method for dividing a semiconductor wafer, comprising the steps of: providing a semiconductor wafer on which a plurality of integrated circuits are formed, and a gap is provided between the plurality of integrated circuits; A mask layer is formed on the semiconductor wafer, and the mask layer covers and protects the integrated circuit; a laser is emitted using a nozzle and a plasma etching gas is sprayed to pattern the mask layer to expose the semiconductor wafer Gap between multiple integrated circuits; the semiconductor wafer is divided by the exposed gap, wherein the laser is an ultraviolet femtosecond laser, and the pulse width of the ultraviolet femtosecond laser is 10- 500 femtoseconds, the wavelength is 200-1570nm, the pulse repetition frequency is 200kHz-10MHz, the pulse energy is 0.5-100μJ, and the diameter of the focal point is 3-15μm. For example, the method for dividing a semiconductor wafer according to item 11 of the application, wherein the mask layer is a silicon oxide layer, and the plasma etching gas for patterning the mask layer is a dry etching gas of silicon oxide. The method for dividing a semiconductor wafer according to item 12 of the application, wherein the dry etching gas of the silicon oxide includes an etching reaction gas HF or H ₂ O, and one or more selected from He, Ar, and N ₂ . Carry gas. For example, the method for slicing a semiconductor wafer according to item 11 of the patent application range, wherein the ultraviolet femtosecond laser has a pulse width of 100-400 femtoseconds, a wavelength of 200-540nm, a pulse repetition frequency of 500kHz-5MHz, and a pulse The energy is 1-5 μJ, and the diameter of the focal point is 5-10 μm. For example, the method for dividing a semiconductor wafer according to item 11 of the patent application is characterized in that the semiconductor wafer is divided by an exposed gap, and the semiconductor wafer is placed in a dry state after the mask layer is patterned. Dry etching is performed on the gaps exposed by the mask layer in a method of etching, so that the plurality of integrated circuits are separated one by one. For example, the method for dividing a semiconductor wafer according to item 11 of the patent application is characterized in that the semiconductor wafer is divided by an exposed gap. After the mask layer is patterned, a laser is used to emit a laser and a plasma is ejected. The etching gas etches the gaps exposed by the mask layer to separate the multiple integrated circuits one by one.