JPH0747864Y2 - Semiconductor wafer protection member - Google Patents

Description

TECHNICAL FIELD The present invention relates to a protective member that is attached to a circuit pattern forming surface when a back surface of a semiconductor wafer is polished. Is given.

2. Description of the Related Art There is a strong demand for a protective member to be attached to a circuit pattern formation surface when polishing the back surface of a semiconductor wafer having a predetermined circuit pattern, and having an antistatic function that can withstand practical use.

That is, in the process of manufacturing a semiconductor wafer, the semiconductor wafer that has completed the process of forming a circuit pattern such as an IC is subjected to a back surface polishing process in order to make it as thin as possible.
The thickness of about 0.6 mm is reduced to about 0.3 to 0.4 mm, and then divided into element units as necessary. In the back surface polishing process, in order to prevent the semiconductor wafer from being damaged, or the circuit pattern forming surface from being contaminated or damaged due to abrasion or the like, a protective member is previously attached to the circuit pattern forming surface, and peeled off after the back surface polishing. Thus, the obtained polished wafer is washed.

The protective member used in the above step is formed of a support sheet and a pressure-sensitive adhesive layer, and is attached to a separator to prevent the pressure-sensitive adhesive layer from being contaminated. for that reason,
Static electricity is generated when the separator is attached to the protective member or is peeled off, or when the protective member is attached to the circuit pattern forming surface of the semiconductor wafer or is peeled off. There is a risk that the circuit will be destroyed by the charging due to this, and in order to prevent this, measures are taken to prevent the generation of static electricity or antistatic measures on the protective member.

Heretofore, as a countermeasure against this, it has been known to apply an antistatic agent to a support sheet or mix conductive powder into the support sheet.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the protective member using the support sheet coated with the above-mentioned antistatic agent or the support sheet mixed with the conductive powder, a large amount of impurity ions are liberated, and the liberated ions cause the semiconductor wafer to be released. There was a problem that it could not be put to practical use because it was altered or the circuit was destroyed.

Means for Solving the Problems The present invention overcomes the above problems by using a sheet provided with a vapor-deposited thin layer made of a conductive substance.

That is, the present invention relates to a pressure-sensitive adhesive layer that is attached to a circuit pattern forming surface when a back surface of a semiconductor wafer having a circuit pattern is polished, and a water-resistant sheet that supports the pressure-sensitive adhesive layer. And a water-resistant sheet having a vapor-deposited thin layer made of a conductive substance.

Action A vapor-deposited thin layer of a conductive substance is less likely to generate free ions, and a protective member formed using a water-resistant sheet provided with
Excellent conductivity and less likely to be charged. Further, the change in surface resistivity due to humidity is small, and stable antistatic property is exhibited. Furthermore, the addition of the vapor-deposited thin layer does not deteriorate the adhesiveness, the abradability, and the circuit pattern protective performance during polishing, which are required for the protective member. As a result, a protective member having an antistatic function or an antistatic function and excellent practicality can be obtained.

Example As shown in the figure, the protective member of the present invention is a water resistant sheet 1
A pressure-sensitive adhesive layer 2 attached thereto. The water-resistant sheet 1 is provided to alleviate impact during polishing of the back surface of a semiconductor wafer and to prevent the protective member from being damaged by cleaning water or the like and becoming difficult to peel off. The pressure-sensitive adhesive layer 2 is for sticking the water-resistant sheet 1 to the circuit pattern forming surface of the semiconductor wafer to seal it.

In the present invention, as the water resistant sheet 1, a water resistant sheet comprising at least a support sheet 11 and a vapor deposited thin layer 12 having conductivity is used.

The support sheet has good water resistance, for example, a thickness of 25
A polypropylene sheet, a polyester sheet, a polycarbonate sheet, an ethylene / vinyl acetate copolymer sheet, an ethylene / ethyl acrylate copolymer sheet, an ethylene / propylene copolymer sheet, a plastic sheet such as a polyvinyl chloride sheet having a thickness of up to 150 μm can be used.

The vapor-deposited thin layer 12 is formed by vapor-depositing a conductive substance made of, for example, aluminum, titanium, iron, nickel, copper, zinc, silver, indium, tin, gold, lead, an alloy containing these metals, or an oxide thereof. Formed. The thickness may be appropriately determined, but is generally 30 to 500Å.

In the present invention, the vapor-deposited thin layer 12 of the water resistant sheet 1 is
It may be provided directly on the support sheet 11 as shown in FIGS. 1 and 2, or may be provided via a film 13 separate from the support sheet 11 as shown in FIG. Further, a plurality of layers may be provided such as being provided on both sides of the support sheet 11. The protective member is preferably formed so that the surface resistance of the water resistant sheet is 10 ¹⁶ Ω or less, especially 10 ⁸ Ω or less.

As shown in FIG. 2 and FIG. 3, the vapor deposition thin layer 12 coated form has an advantage that the vapor deposition thin layer 12 is protected by the coating layers (11, 13) and is unlikely to fall off. Further, as shown in FIG. 1, the form in which the vapor-deposited thin layer 12 is exposed on the surface has an advantage of being excellent in antistatic effect.

As shown in FIG. 3, in the method in which the vapor deposition thin layer 12 is provided on the separate film 13 and laminated on the support sheet 11, it is difficult to directly perform vapor deposition treatment (150 to 200 ° C.) from the viewpoint of heat resistance and the like. There is an advantage that a sheet made of various materials can be used as the support sheet. As the supporting sheet, for example, an ethylene / vinyl acetate copolymer, an ethylene / ethyl acrylate copolymer, an ethylene / propylene copolymer, or the like, which is rich in rubber elasticity and has a good deformability, among which an elastic modulus is 1 to 50.
A protective member using a kg / mm ² sheet has excellent adhesion to rough surfaces and excellent semiconductor wafer protection function.
Further, since the support sheet 11 can be reinforced with the film 13, it is also advantageous in forming the water resistant sheet 1 having a strong rigidity. A protective member made of a strong waterproof sheet is less likely to bend and attach (exposed circuit pattern formation surface) when the protective member is automatically attached to the circuit pattern formation surface of a semiconductor wafer by an automatic attachment device. Have advantages. The waist strength is preferably at least about a polypropylene sheet, a polyester sheet or a polycarbonate sheet. When the vapor-deposited thin layer 12 is provided on a film separate from the support sheet, a film having heat resistance such as a polyester film that can be vapor-deposited is used as the film.

In the present invention, the pressure-sensitive adhesive layer 2 may be provided on the support sheet 11 side of the waterproof sheet 1 as shown in FIGS. 1 and 3, or on the vapor deposition thin layer 12 side as shown in FIG. May be.
The pressure-sensitive adhesive used is 10 to 600 g / 2 based on the 180 degree peel value (at room temperature, pulling speed 300 mm / min) for stainless steel plate.
There is no particular limitation on the type of acrylic pressure-sensitive adhesive or rubber pressure-sensitive adhesive as long as it has an adhesive force of 0 mm. The thickness of the pressure sensitive adhesive layer may be appropriately determined, but is generally 5 to 100 μm.

In the present invention, when the shape of the protective member is molded so as to correspond to the planar shape of the semiconductor wafer to be attached,
There is no need for a molding process after attaching the protective member. The molding process after sticking the protective member is liable to cause peeling, which causes water to enter.

As shown in FIG. 1, a separator 3 or the like is usually attached to the protective member in order to protect the pressure-sensitive adhesive layer 2 from contamination or the like during storage or distribution. The separator is peeled and removed before the protective member is attached to the semiconductor wafer introduced in the back surface polishing step. The separator is formed of a flexible thin sheet made of paper, plastic film, metal foil, etc., and if necessary, surface-treated with a release agent to impart releasability. Since static electricity is generated even when the separator is attached or peeled off, an appropriate conductive layer 31 may be provided on the separator to make it more difficult to be charged.

Further, as shown in FIG. 4, the separator 3 is formed of a long body and has a carrier tape function, and a plurality of protective members S are arranged and adhered to the semiconductor wafer 4 introduced in the back surface polishing step. However, there is a case where the automatic sticking device can be applied so that the protective member S can be automatically stuck to the semiconductor wafers 4 which are sequentially introduced. In addition, 5 is a pressure bonding roll and 6 is a reversing roll.

Example 1 A water resistant sheet having a nickel vapor-deposited layer having a thickness of 100 Å on one side of a support sheet made of a polyester film having a thickness of 50 μm was used, and 100 parts of butyl acrylate, 5 parts of acrylonitrile and acrylic were placed on the nickel vapor-deposited layer. An acrylic pressure-sensitive adhesive consisting mainly of an acrylic copolymer having a number average molecular weight of 800,000 consisting of 5 parts of acid was applied and heat-treated at 80 ° C for 10 minutes, and then a shape corresponding to the planar shape of the semiconductor wafer was applied. A protective member having a pressure-sensitive adhesive layer having a thickness of 20 μm was cut out.

The stainless steel plate (SUS 30
The adhesive strength to 4) (20 ℃, 65% RH, 180 degree peeling, pulling speed 300 mm / min) was 150 g / 20 mm.

Example 2 A protective member was obtained in the same manner as in Example 1 except that the pressure-sensitive adhesive layer was provided on the surface of the support sheet on which the nickel vapor deposition layer was not provided.

Example 3 30 μm thick with a 100 Å nickel vapor deposition layer on one side
Of the polyester film through the nickel vapor deposition layer,
A protective member was prepared in the same manner as in Example 1 except that a water-resistant sheet was formed by sticking to a supporting sheet made of a 100 μm thick ethylene / vinyl acetate copolymer (elastic modulus 5.7 kg / mm ² ). Obtained. The polyester film and the supporting sheet were bonded to each other via an acrylic pressure-sensitive adhesive having a thickness of 5 μm.

Comparative Example 1 A protective member was obtained in the same manner as in Example 2 except that a polyester film having no nickel vapor deposition layer was used as it was as a water resistant sheet.

Comparative Example 2 A protective member was obtained in the same manner as in Example 1 except that a polyester film treated with a cationic antistatic agent was used as the water resistant sheet.

Evaluation test The results of analysis of the surface resistivity measured on the surface of the water-resistant sheet of the protective members obtained in Examples and Comparative Examples and the presence of impurity ions on the surface of the pressure-sensitive adhesive layer are shown in the table.

FIG. 5 shows changes in surface resistivity of the protective members of Example 1 and Comparative Example 2 with humidity.

Further, about the protective member of Examples 1 and 2 and Comparative Examples 1 and 2 5000
FIG. 6 shows the decay characteristics of the electrostatic charge when a voltage of V is applied (20 ° C., 40% RH).

The protective member obtained in each example was attached to a circuit pattern forming surface of a semiconductor wafer having a diameter of 4 inches and a thickness of about 0.6 mm on which a predetermined circuit pattern was formed, and then the back surface of the semiconductor wafer was polished by a conventional method. The processed wafer was processed to a thickness of about 0.3 mm, and the protective member was peeled off from the obtained polished wafer.However, in any protective member, water invades when polishing the back surface of the protective member or the pattern surface is contaminated with polishing debris. In addition, the protective member did not peel off, and the wafer protecting function such as damage prevention was perfect, and even when the protective member was peeled off, it could be easily peeled off without breaking the polishing wafer. Further, the deterioration of the semiconductor wafer and the circuit destruction due to the sticking and peeling of the protective member were not observed, and the effect of preventing static electricity generation and the effect of preventing static charge were excellent.

Effect of the Invention According to the protective member of the present invention, since the water-resistant sheet having the conductive vapor-deposited thin layer is used, the protective functions such as the contamination prevention, the damage prevention, the damage prevention and the peeling prevention which are required at the time of the back surface polishing,
Moreover, it is possible to effectively prevent generation of static electricity and electrostatic charge due to excellent smooth peeling / removing property that does not damage the polished wafer, and without deterioration of the semiconductor wafer and circuit destruction due to free ions.

[Brief description of drawings]

1, 2, and 3 are cross-sectional views showing a constitutional example of a protective member of the present invention, FIG. 4 is an explanatory view of an automatic attaching method of the protective member, and FIG. 5 is a surface specific resistance due to humidity. And FIG. 6 is a graph showing the charge attenuation characteristic. 1: Water resistant sheet 11: Support sheet, 12: Deposition thin layer 13: Film 2: Pressure-sensitive adhesive layer 3: Separator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Eiji Shigemura, 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Electric Industry Co., Ltd. (72) Seishiro Matsuzaki 1-2, Shimohozumi, Ibaraki City, Osaka Prefecture No. Nitto Denki Kogyo Co., Ltd. (56) Reference JP-A-62-58638 (JP, A) Actual development Shou 60-155199 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. A pressure-sensitive adhesive layer to be attached to a circuit pattern forming surface when a back surface of a semiconductor wafer having a circuit pattern is polished, and a water-resistant sheet supporting the pressure-sensitive adhesive layer. And a water resistant sheet having a vapor-deposited thin layer made of a conductive material.