Film pasting method of semiconductor substrate and thinning method of semiconductor substrate

Abstract

The invention provides a film pasting method of a semiconductor substrate and a thinning method of the semiconductor substrate. According to the film pasting method, at least the part, on the edge of the semiconductor substrate, of the topmost covering layer is removed, so that the protective film can be tightly attached to the edge area of the semiconductor substrate, the effect of sealing the edge of the substrate is achieved, and therefore when the follow-up process (such as the thinning process) is carried out, the yield of the substrate is improved. Therefore, the water solution can be effectively prevented from permeating from the side edge of the semiconductor substrate, and the influence on each chip in the substrate is avoided.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a method for laminating a semiconductor substrate and a method for thinning a semiconductor substrate. Background Art

[0002] With the continuous development of semiconductor technology, based on the requirements for the electrical performance of devices, more and more products need to adopt thinning processes in their manufacturing process to reduce the thickness of the substrate so that the formed devices can achieve the expected electrical parameters.

[0003] Among them, before performing the thinning process, a film is generally applied to the front of the substrate to protect the front of the substrate, and then the back of the substrate is ground and thinned, and then the film is torn off, and the rest of the processing is continued. However, before the film is applied to the front of the substrate, since several film layers have been formed in each chip area of ​​the substrate, steps will be formed in certain positions, so that the steps will not fit tightly when the film is applied, and bubbles and gaps will be formed. In the subsequent grinding and thinning process, aqueous solutions such as grinding liquid and cleaning liquid will penetrate into the chip along the gap, affecting each chip in the substrate; in addition, the aqueous solution will penetrate into the chip along the gap, which will also cause water marks after the film is torn off, ultimately affecting the appearance of the product. Summary of the invention

[0004] The object of the present invention is to provide a method for laminating a semiconductor substrate, so as to solve the problem of aqueous solution infiltration caused by loose lamination in the prior art.

[0005] To solve the above technical problems, the present invention provides a method for laminating a semiconductor substrate, comprising providing a semiconductor substrate, a plurality of chips being formed on the surface of the semiconductor substrate, adjacent chips being separated from each other by scribe lines, at least one covering layer being formed on the semiconductor substrate, the covering layer covering the chips and having an opening formed at least in the scribe line area to expose the scribe line, and at least a portion of the topmost covering layer at the edge of the semiconductor substrate being removed; and attaching a protective film on the surface of the semiconductor substrate, the edge portion of the protective film being laminated to the edge area of ​​the semiconductor substrate.

[0006] Optionally, an edge cleaning process is used to remove at least a portion of the topmost covering layer at the edge of the semiconductor substrate.

[0007] Optionally, the at least one covering layer includes a first covering layer of inorganic material, and the method for forming the opening in the first covering layer and removing the edge portion includes: forming an inorganic material layer on the semiconductor substrate to constitute the first covering layer, and forming a photoresist layer on the first covering layer; using a side edge washing process to remove the portion of the photoresist layer at the edge of the semiconductor substrate; performing a photolithography process to remove the photoresist layer at least at the portion of the scribe line; and etching the first covering layer using the photoresist layer as a mask to form an opening exposing the scribe line, and removing the portion of the first covering layer at the edge of the semiconductor substrate.

[0008] Optionally, the at least one covering layer includes a first covering layer of an inorganic material and a second covering layer of an organic material stacked and arranged, and at least the edge portion of the second covering layer is removed. The method of forming the opening in the first covering layer and the second covering layer and removing at least the edge portion of the second covering layer comprises: forming an inorganic material layer on the semiconductor substrate to constitute the first covering layer, and forming the opening in the first covering layer to expose the scribe line; forming an organic material layer on the first covering layer to constitute the second covering layer; removing the portion of the second covering layer at the edge of the semiconductor substrate by an edge washing process; and performing a photolithography process to remove at least the portion of the second covering layer at the scribe line to form the opening exposing the scribe line.

[0009] Optionally, before forming the second covering layer, an edge portion of the first covering layer is also removed, and the method includes: forming a photoresist layer on the first covering layer; using an edge washing process to remove a portion of the photoresist layer at the edge of the semiconductor substrate; performing a photolithography process to remove at least a portion of the photoresist layer at the scribe line; and etching the first covering layer using the photoresist layer as a mask to form an opening exposing the scribe line and remove a portion of the first covering layer at the edge of the semiconductor substrate.

[0010] Optionally, at least two covering layers are formed on the semiconductor substrate, and the ends of the covering layers arranged from bottom to top have the same distance from the edge of the substrate or increase in sequence.

[0011] Optionally, the method of forming the covering layer and removing a portion of the covering layer at the edge of the semiconductor substrate includes: forming a first covering layer on the semiconductor substrate and removing a portion of the first covering layer at the edge of the semiconductor substrate; and forming a second covering layer on the semiconductor substrate and removing a portion of the second covering layer at the edge of the semiconductor substrate.

[0012] Optionally, a region with a width of 1 mm to 3 mm inward from the edge of the substrate is removed from the first covering layer; and / or a region with a width of 2 mm to 5 mm inward from the edge of the substrate is removed from the second covering layer.

[0013] Optionally, the at least two covering layers include a first covering layer of an inorganic material and a second covering layer of an organic material stacked from bottom to top.

[0014] Optionally, the material of the first covering layer includes silicon nitride or silicon oxide. And the material of the second covering layer includes polyimide, for example.

[0015] Optionally, the method for preparing the at least one covering layer includes: forming a first covering layer of inorganic material on the semiconductor substrate; forming a photoresist layer on the first covering layer; using a side edge washing process to remove a portion of the photoresist layer at an edge of the semiconductor substrate; performing a photolithography process on the photoresist layer to at least remove a portion of the photoresist layer covering the scribe line, so that the photoresist layer simultaneously exposes an edge region of the semiconductor substrate and at least a region corresponding to the scribe line; etching the first covering layer using the photoresist layer as a mask to simultaneously remove an edge portion of the first covering layer and at least a portion corresponding to the scribe line; forming a second covering layer of organic material on the semiconductor substrate; using a side edge washing process to remove a portion of the second covering layer at an edge of the semiconductor substrate; and performing a photolithography process on the second covering layer to form an opening that at least exposes the scribe line.

[0016] The present invention also provides a semiconductor substrate with a protective film attached thereto, wherein a plurality of chips are formed on the semiconductor substrate, and adjacent chips are separated from each other by scribe lines; and at least one covering layer is also formed on the semiconductor substrate, wherein the covering layer covers the chips and has an opening at least in the scribe line area; wherein at least the end of the topmost covering layer is a predetermined size away from the edge of the semiconductor substrate and does not cover the edge area of ​​the semiconductor substrate, and the edge portion of the protective film is attached to the edge area of ​​the semiconductor substrate.

[0017] Optionally, at least two covering layers are formed on the semiconductor substrate, and the ends of the covering layers arranged from bottom to top have the same distance from the edge of the substrate or increase in sequence.

[0018] Optionally, the at least two covering layers include a first covering layer and a second covering layer stacked from bottom to top; wherein the end of the first covering layer is 1mm-3mm away from the edge of the substrate; and / or the end of the second covering layer is 2mm-5mm away from the edge of the substrate.

[0019] Optionally, the at least one covering layer includes a first covering layer of an inorganic material and a second covering layer of an organic material stacked from bottom to top.

[0020] Optionally, the material of the first covering layer includes silicon nitride or silicon oxide; and / or the material of the second covering layer includes polyimide.

[0021] The present invention also provides a method for thinning a semiconductor substrate, which is characterized by comprising: using the film sticking method as described above to stick a protective film on the first surface of the semiconductor substrate; and thinning the second surface of the semiconductor substrate.

[0022] In the film laminating method for semiconductor substrates provided by the present invention, before performing the film laminating step, at least the portion of the topmost covering layer at the edge of the semiconductor substrate is removed, so that the edge area of ​​the semiconductor substrate is relatively flat, so that the protective film can be tightly attached to the edge area of ​​the semiconductor substrate, which is equivalent to sealing the edge of the substrate. In this way, when performing subsequent processes (for example, thinning process), the aqueous solution can be effectively blocked from penetrating from the side of the semiconductor substrate to avoid affecting the various chips in the substrate. Compared with the solution of replacing a thicker protective film to increase the fit of the protective film and thus improve the penetration of the aqueous solution, the improved method provided by the present invention can be applied to protective films of any thickness, or the same protective film can be shared for different products, and the problem of aqueous solution penetration can still be improved, effectively reducing the trouble of replacing the protective film and increasing the process flow, and reducing production costs, production risks and project development time. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the distribution of chips on the surface of a semiconductor substrate.

[0024] Figure 2 for Figure 1 The semiconductor substrate shown is an enlarged schematic diagram of the dotted line frame area.

[0025] Figure 3 for Figure 2 The schematic cross-sectional view of the semiconductor substrate along the aa' direction is shown.

[0026] Figure 4 FIG. 4 is a schematic diagram of the distribution of chips on a semiconductor substrate in an embodiment of the present invention.

[0027] Figure 5 It is a schematic structural diagram of a semiconductor substrate with a protective film attached in an edge region in one embodiment of the present invention.

[0028] Figure 6-Figure 9 FIG. 4 is a schematic structural diagram of a semiconductor substrate during a thinning process in an embodiment of the present invention.

[0029] The reference numerals are as follows:

[0030] 100- semiconductor substrate;

[0031] 100a - marginal area;

[0032] 110-chip;

[0033] 111- soldering pad area;

[0034] 111a-gap;

[0035] 120-slicing lane;

[0036] 200 - covering layer;

[0037] 210 / 21-first covering layer;

[0038] 220 / 21-second covering layer;

[0039] 300 / 30-protective film; DETAILED DESCRIPTION

[0040] As described in the background technology, for a semiconductor substrate with several film layers formed on the front side, when attaching the protective film, bubbles and gaps are easily generated due to the presence of steps, which can easily cause aqueous solutions such as grinding liquid or cleaning liquid to penetrate during subsequent grinding and thinning, thereby affecting the chip in the substrate.

[0041] One solution to the problem of bubbles and gaps being easily generated during film application is to replace the protective film with a thicker adhesive layer to increase the fit between the substrate and the protective film and eliminate bubbles and gaps. However, this solution requires testing for different products during the development phase to find the most suitable protective film, and sometimes even requires additional purchases, which greatly increases product development time and reduces development efficiency. Another solution is to add a cleaning process to the front of the substrate after tearing off the film to remove water marks. This does not solve the problem of aqueous solution infiltration, and requires an additional cleaning process, which occupies the production capacity of the machine and increases additional risks such as machine film drop. Therefore, it is not an efficient improvement method.

[0042] In view of the above technical problems, the inventors of the present invention have proposed a new improvement idea after exploring various reasons for the infiltration of aqueous solution. Figure 1-Figure 3 ,in Figure 1 This is a schematic diagram of the distribution of chips on the front side of the semiconductor substrate. Figure 2 for Figure 1 The semiconductor substrate shown is an enlarged schematic diagram of the dotted line frame area. Figure 3 for Figure 2 The schematic cross-sectional view of the semiconductor substrate along the aa' direction is shown in FIG. Figure 1-Figure 3 As shown, before the front surface of the substrate is filmed, a plurality of chips 110 are formed on the substrate, and adjacent chips 110 are separated from each other by scribing lanes 120, and at least one thicker covering layer 200 is also formed on the surface of the substrate, and the covering layer 200 will expose the pad area 111 in the chip 110, so as to realize the electrical lead-out of the device through the pad area 111. Therefore, a step is formed between the pad area 111 and the adjacent covering layer 200 due to the height difference, based on which, when the protective film 300 is attached, the edge of the pad area 111 is easily formed with a gap 111a due to the existence of the step.

[0043] Key References Figure 1 As shown, the scribe line 120 penetrates from the edge of the substrate to each chip 110, and the cover layer 200 also exposes the scribe line 120, so that there is a height difference between the scribe line 120 and the adjacent chip 110 to form a step. Figure 3 As shown, when the protective film 300 is attached, gaps will also be generated in the scribe lane 120, and the gaps in the scribe lane 120 will be connected to each chip 110 from the edge of the substrate inward. In particular, when the width of the scribe lane 120 is small, the protective film 300 will only cover the top opening of the scribe lane 120 when the protective film 300 is attached, so that the scribe lane 120 has an opening exposed laterally from the edge of the substrate and connects each chip 110 from the edge of the substrate inward. At this time, when the subsequent process (for example, the back grinding and thinning process) is performed, the aqueous solution will penetrate through the scribe lane 120 and flow to each chip 110, and further penetrate into the gap 111a in each chip 110.

[0044] In view of this, the present invention provides a method for laminating a semiconductor substrate, comprising: providing a semiconductor substrate to be laminarized, a plurality of chips being formed on the surface of the semiconductor substrate, adjacent chips being separated from each other by scribe lines, at least one covering layer being formed on the semiconductor substrate, the covering layer covering the chips and having an opening formed at least in the scribe line area to expose the scribe line; removing at least a portion of the topmost covering layer at the edge of the semiconductor substrate; and attaching a protective film on the surface of the semiconductor substrate, the edge portion of the protective film being laminar to the edge area of ​​the semiconductor substrate.

[0045] That is, the film laminating method provided by the present invention processes the edge of the semiconductor substrate so that the protective film can be directly attached to the relatively flat edge area of ​​the semiconductor substrate, thereby closing the lateral opening of the scribe line at the edge of the substrate. In this way, it is possible to prevent the aqueous solution in the subsequent process (for example, the thinning process) from penetrating into the scribe line and further affecting the chips in the substrate.

[0046] It should be noted that there is no particular limitation on the step of removing the edge portion of the cover layer, as long as it can be removed before attaching the protective film 300. The specific removal method used in the specific example will be described in detail in the following embodiments.

[0047] The following is a further detailed description of the film-attaching method for a semiconductor substrate, the thinning method for a semiconductor substrate, and the semiconductor substrate with a protective film attached thereto proposed in the present invention in conjunction with specific embodiments. According to the following description, the advantages and features of the present invention will become clearer. It should be noted that the drawings are all in a very simplified form and are not in precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. It should be recognized that relative terms such as "above", "below", "top", "bottom", "above" and "below" shown in the drawings can be used to describe the relationship between various elements. These relative terms are intended to cover different orientations of elements other than the orientations depicted in the drawings. For example, if the device is inverted relative to the view in the drawing, an element described as being "above" another element will now be below the element.

[0048] First reference Figure 4 As shown, a semiconductor substrate 100 to be laminated is provided, and a plurality of chips 110 are formed on the surface of the semiconductor substrate 100, and adjacent chips 110 are separated from each other by dicing lanes 120. In addition, at least one covering layer ( Figure 4 The at least one covering layer 200 may include a passivation layer (e.g., a silicon nitride layer) for passivating and protecting the film layer in the chip 120; and the at least one covering layer 200 may further include an organic capping layer (e.g., a polyimide layer) for sealing the device structure in the chip 120 to prevent the intrusion of external water vapor.

[0049] Furthermore, a pad area (PAD) is formed in the chip 110, and the formed covering layer exposes the pad area in the chip 110 so as to realize the electrical lead-out of the device through the pad area. As the thickness of the covering layer increases, the size of the gap formed in the pad area when the protective film is attached may also be larger. For example, the thickness of the covering layer is 5μm-15μm. It should be noted that since this embodiment only focuses on the optimization of the edge of the semiconductor substrate 100, the structure on the inner side of the semiconductor substrate 100 can continue to refer to Figure 2 and Figure 3 ,like Figure 2 and Figure 3As shown, the cover layer 200 does not cover the pad area 111, so that a step is formed between the pad area 111 and the adjacent cover layer 200 due to the height difference. Based on this, when the protective film 300 is attached, a gap 111a is easily generated at the edge of the pad area 111 due to the existence of the step.

[0050] Furthermore, the cover layer 200 is also provided with an opening in the scribe line region to expose the scribe line 120, so as to facilitate the subsequent cutting of the semiconductor substrate 100 to separate the individual chips 110. As described above, there is also a height difference between the scribe line 120 and the adjacent cover layer 200 to form a step, so that a gap is also generated in the scribe line 120 when the protective film 300 is attached, and the gap in the scribe line 120 connects the individual chips 110.

[0051] Then combine Figure 4 and Figure 5 As shown, in the film attaching method provided in this embodiment, before the protective film 300 is attached, the method further includes: removing at least a portion of the topmost cover layer 200 at the edge of the semiconductor substrate 100 to expose the edge region 100a of the semiconductor substrate 100. Figure 1 Compared with the example shown in the figure, which shows that there is a gap when the film is attached due to the step formed by the scribe groove 120 and the cover layer 200 in the edge area 100a, in this embodiment, at least the topmost cover layer 200 at the edge of the semiconductor substrate 100 is removed, so that a flat bonding surface can be formed in the entire edge area 100a of the semiconductor substrate. After that, when attaching the protective film 300, the protective film 300 can be attached to the relatively flat edge area 100a of the semiconductor substrate 100, avoiding the generation of gaps in the edge area 100a and providing the possibility for the infiltration of aqueous solution. Or it can also be understood that: in this embodiment, the protective film 300 can be attached to the relatively flat edge area 100a of the semiconductor substrate 100, thereby closing the lateral opening of the scribe groove 120 on the inner side of the substrate to avoid the infiltration of aqueous solution.

[0052] It should be noted that in the existing process, the edge of the cover layer 200 is usually not processed after the cover layer 200 for sealing protection is formed. The reason is that the cover layer 200 is generally the top film layer (such as a passivation layer and / or an organic capping layer) used to protect the semiconductor device in the chip. It only needs to achieve sealing protection for the film layer below it and avoid affecting the subsequent electrical lead-out. Therefore, it is not necessary to remove the edge of the cover layer 200 in the conventional process. In this application, in order to solve the problem of aqueous solution infiltration, on this basis, it is creatively proposed to remove at least the edge of the topmost cover layer 200, so that the attached protective film 300 can form a sealing ring at the edge of the semiconductor substrate 100 to prevent the aqueous solution from infiltrating.

[0053] In addition, among the chips arranged on the semiconductor substrate 100, due to the limitations of the substrate shape and the chip shape, the chips located at the edge of the substrate are usually incomplete chips, that is, invalid chips. Figure 4 The semiconductor substrate 100 shown is specifically a wafer, wherein the chips arranged at the edge of the wafer are incomplete chips. Because the chips at the edge of the substrate are usually invalid chips, although the portion of the cover layer 200 at the edge of the substrate is removed in this embodiment, it still does not affect the chip yield, but is beneficial to improve the chip yield after improving the problem of aqueous solution infiltration.

[0054] Further, for the cover layer 200 whose edge portion needs to be removed, the step of removing the edge portion can be performed before the cover layer 200 is patterned to form an opening exposing the scribe line 120; that is, after forming the material layer for the cover layer, the edge portion of the material layer is first removed, and then the material layer is patterned to expose the scribe line 120 and the pad area 111. Alternatively, the step of removing the portion of the cover layer 200 at the edge of the semiconductor substrate 100 can also be performed after the cover layer 200 is patterned to form an opening exposing the scribe line 120; that is, after forming the material layer for the cover layer, the material layer is first patterned to expose the scribe line 120 and the pad area 111; then, the edge portion of the material layer is removed. In other words, the step of removing the edge portion of the cover layer 200 is not limited, as long as it is removed before attaching the protective film 300.

[0055] In a specific example, the at least one covering layer 200 may include a first covering layer of an inorganic material, which may be used to passivate and protect the film layer in the chip 120, thereby forming a passivation layer. The first covering layer of the inorganic material may further be a silicon nitride layer, a silicon-rich silicon nitride layer, a silicon oxide layer, or a silicon-rich silicon oxide layer. Furthermore, the at least one covering layer 200 may also include a second covering layer of an organic material formed on the first covering layer, which may be used to seal the device structure in the chip 120, prevent the intrusion of external water vapor, and thus form an organic capping layer. In the specific example, the material of the second covering layer may include, for example, a polyimide layer (PI).

[0056] In the first optional solution, only the edge portion of the topmost second covering layer can be removed, while the edge portion of the first covering layer is still retained. In the second optional solution, the edge portion of the first covering layer and the edge portion of the second covering layer are both removed, wherein the removal size of the edge portion of the first covering layer and the removal size of the edge portion of the second covering layer can be the same, in which case the end of the first covering layer and the end of the second covering layer can be aligned and both can be retracted relative to the edge of the substrate; or, the removal size of the edge portion of the first covering layer and the removal size of the edge portion of the second covering layer can also be different, for example, the edge removal size of the upper covering layer (i.e., the second covering layer) can be made larger than the edge removal size of the lower covering layer (i.e., the first covering layer), and then a step structure can be formed by the edge of the semiconductor substrate, the end of the first covering layer, and the end of the second covering layer.

[0057] Among them, for the second optional scheme where it is necessary to remove the edge portion of the first covering layer of inorganic material, and also form an opening in the first covering layer to expose the scribe line, the method includes, for example: first, forming a first covering layer of inorganic material (for example, a silicon nitride layer, etc.) on the semiconductor substrate, and forming a photoresist layer on the first covering layer; then using an edge cleaning process (EBR) to remove the portion of the photoresist layer at the edge of the semiconductor substrate; then performing a photolithography process to remove at least the portion of the photoresist layer at the scribe line, so that the photoresist layer exposes the scribe line area and the edge area of ​​the substrate at the same time; thereafter, etching the first covering layer using the photoresist layer as a mask to form an opening exposing the scribe line, and removing the portion of the first covering layer at the edge of the semiconductor substrate.

[0058] And, for the second covering layer of organic material, the method of forming an opening in the second covering layer to expose the scribe line and removing its edge portion, for example, includes: first, forming an organic material layer on a semiconductor substrate to constitute a second covering layer (for example, a polyimide layer, etc.), and the material of the second covering layer can specifically be a photosensitive material; then, using an edge cleaning process (EBR) to remove the portion of the second covering layer at the edge of the semiconductor substrate; thereafter, performing a photolithography process to remove at least the portion of the second covering layer at the scribe line to form an opening exposing the scribe line.

[0059] In a further solution, the distance between the ends of the covering layers arranged from top to bottom and the edge of the substrate can be reduced in sequence, that is, in the at least two layers of stacked covering layers, the ends of the covering layers located at the upper layer are retracted by a predetermined dimension relative to the ends of the covering layers located at the lower layer. In this way, the ends of the at least two layers of covering layers 200 can form multiple steps in the edge area 100a, so that the total thickness of the covering layers is gradually reduced in a step-by-step manner from the center of the substrate to the edge of the substrate, thereby improving the fit of the protective film 300 to the ends of the covering layers 200 and better preventing the penetration of aqueous solutions.

[0060] For example Figure 5 As shown, in this example, a first cover layer 210 and a second cover layer 220 are stacked from bottom to top on the semiconductor substrate 100, and the first cover layer 210 extends relative to the second cover layer 220, so that three steps can be formed by the second cover layer 220, the first cover layer 210 and the substrate surface of the edge region 100a. In one example, the first cover layer 210 can be an inorganic material layer, and more specifically, the inorganic material layer can be a silicon nitride layer, a silicon-rich silicon nitride layer, a silicon oxide layer or a silicon-rich silicon oxide layer, etc.; and the second cover layer 220 can be an organic material layer, and its material can include, for example, a polyimide layer (PI).

[0061] Further, Figure 5 For example, the method for preparing the covering layer 200 includes:

[0062] First, a first cover layer 210 of an inorganic material (eg, a silicon nitride layer, etc.) is formed on a semiconductor substrate 100;

[0063] Next, a photoresist layer (not shown in the figure) is formed on the first cover layer 210;

[0064] Next, an edge cleaning process (EBR) is used to remove a portion of the photoresist layer at the edge of the semiconductor substrate 100, for example, a region of the photoresist layer with a width of 1 mm to 3 mm from the edge may be removed;

[0065] Next, a photolithography process is performed on the photoresist layer to remove the portion of the photoresist layer covering the scribe line 120 and the pad area 111, so that the photoresist layer simultaneously exposes the edge area of ​​the substrate and the area corresponding to the scribe line 120 and the pad area 111;

[0066] Next, the first cover layer 210 is etched using the photoresist layer as a mask to simultaneously remove the edge portion of the first cover layer 210 and the portion corresponding to the scribe line 120 and the pad area 111;

[0067] Next, a second covering layer 220 of an organic material (eg, a polyimide layer PI) is formed on the semiconductor substrate 100 ;

[0068] Next, a cleaning process is used to remove the portion of the second covering layer 220 at the edge of the semiconductor substrate 100. For example, a region of the second covering layer 220 with a width of 2 mm to 5 mm from the edge inward may be removed.

[0069] Thereafter, a photolithography process is performed on the second capping layer 220 to form openings corresponding to the scribe lines 120 and the pad regions 111 , thereby exposing the scribe lines 120 and the pad regions 111 .

[0070] Based on the above-mentioned film attaching method, this embodiment also provides a semiconductor substrate with a protective film attached thereto, which can be specifically combined with Figure 2-Figure 5 As shown, a plurality of chips 110 are formed on the semiconductor substrate 100, and adjacent chips 110 are separated from each other by scribe lines 120. In addition, at least one covering layer 200 is formed on the semiconductor substrate 100, and the covering layer 200 covers the chips 110 and has openings at least in the scribe line region, that is, the covering layer 200 does not cover the scribe line 120. In this embodiment, the covering layer 300 also has openings in the pad region 111 of the chip and does not cover the pad region 111 of the chip.

[0071] Key References Figure 5 As shown, at least the end of the topmost covering layer 200 is a predetermined size away from the edge of the semiconductor substrate 100 and does not completely cover the edge area 100a of the semiconductor substrate 100. In this way, the edge portion of the protective film 300 can be attached to the edge area of ​​the semiconductor substrate 100, thereby forming a closed loop for blocking the penetration of aqueous solution.

[0072] In a specific example, at least two covering layers 200 may be formed on the semiconductor substrate 100 , for example Figure 5 In the example, a first covering layer 210 (e.g., a silicon nitride layer) of an inorganic material and a second covering layer 220 (e.g., a polyimide layer PI) of an organic material are formed on the semiconductor substrate 100 and are stacked from bottom to top. Also, the distance between the end of the covering layer arranged from bottom to top and the edge of the substrate can be increased successively (e.g., the distance between the end of the first covering layer 210 and the edge of the substrate is 1mm-3mm, and the distance between the end of the second covering layer and the edge of the substrate is 2mm-5mm). At this time, the ends of at least two layers of covering layers 200 can be presented as multiple steps in the edge area of ​​the semiconductor substrate 100. It should be noted that, since the distance between the end of the covering layer and the edge of the substrate decreases from top to bottom, the total thickness of the covering layer can be made to gradually decrease in a step-like manner from the center of the substrate to the edge of the substrate, thereby preventing the appearance of steps with a large height, thereby effectively improving the fit of the protective film 300 to the end of the covering layer 200 and better blocking the penetration of aqueous solution.

[0073] As described above, the film laminating method for semiconductor substrates provided in this embodiment can make the attached protective film have a higher degree of lamination in the edge area of ​​the semiconductor substrate, improve the problem of gaps or bubbles formed in the edge area of ​​the substrate, and can seal the edge of the semiconductor substrate, thereby preventing the aqueous solution in the subsequent process from penetrating into the interior of the semiconductor substrate. It should be recognized that even if there are still gaps or bubbles in the protective film inside the substrate, the edge of the substrate is closed and can prevent the aqueous solution from penetrating, so it will still not affect the chip. In practical applications, the film laminating method can be applied to the thinning process of semiconductor substrates, for example, it can be applied to the thinning process of semiconductor substrates formed with IGBT chips.

[0074] Specifically, the method for thinning the semiconductor substrate may include: using the above-mentioned film attaching method to attach the protective film 300 on the first surface of the semiconductor substrate 100; and thinning the second surface of the semiconductor substrate 100. In one example, the process of thinning the second surface of the semiconductor substrate 100 may include: first, grinding and thinning by a grinding process; then, further thinning the semiconductor substrate 100 by etching.

[0075] Combine the following Figure 6-Figure 9 , a method for thinning a semiconductor substrate in a specific embodiment is described.

[0076] First reference Figure 6 As shown, a semiconductor substrate is provided, and at least an edge portion of a topmost cover layer on the semiconductor substrate is removed.

[0077] Specifically, in one example, only the edge portion of the upper second cover layer 22 may be removed. In another example, the edge portions of both the first cover layer 21 and the second cover layer 22 may be removed, wherein the removal size of the edge portion of the first cover layer 21 and the removal size of the edge portion of the second cover layer 22 may be the same, in which case the end of the first cover layer 21 and the end of the second cover layer 22 may be aligned and both may be retracted relative to the edge of the substrate; or, the removal size of the edge portion of the first cover layer 21 and the removal size of the edge portion of the second cover layer 22 may be different, for example, the edge removal width of the upper second cover layer 22 may be greater than the edge removal width of the lower first cover layer 21.

[0078] As described above, there is no limitation on the step of removing the edge portion of the covering layer, as long as it is removed before film application. In this embodiment, the edge portions of the first covering layer 21 and the second covering layer 22 are removed as an example, and the edge portion of each covering layer can also be removed when preparing it. Furthermore, the removal width of the edge portion of each covering layer can be controlled so that the removal width of the upper covering layer is greater than the removal width of the lower covering layer. For example Figure 6 As shown, the removal width of the second covering layer 22 is greater than the removal width of the first covering layer 21, so that the thickness of the end of the covering layer decreases in a step-like manner, thereby improving the subsequent adhesion with the protective film.

[0079] Next reference Figure 7 As shown, a protective film 30 is attached to the first surface (e.g., the front surface) of the semiconductor substrate. The protective film 30 can be attached to the edge region of the semiconductor substrate, and because the edge region is relatively flat, the protective film 30 and the edge region have a high degree of adhesion, which can effectively prevent the penetration of aqueous solution. In particular, the end of the cover layer of this embodiment has a step-like structure, which can further improve the adhesion of the protective film 30 and better improve the problem of aqueous solution penetration.

[0080] Next reference Figure 8 As shown, the semiconductor substrate is turned over to thin the second surface (e.g., the back surface) of the semiconductor substrate. In the thinning step, a grinding process can be used for thinning, and an aqueous solution containing a grinding liquid and a cleaning liquid is used during the grinding and thinning process. The method provided in this embodiment can effectively prevent the aqueous solution from penetrating.

[0081] Next reference Fig. 9 As shown, after the grinding and thinning is completed, the protective film 30 can be removed. In addition, in a further solution, the semiconductor substrate can be further thinned by etching.

[0082] It should be noted that, although the present invention has been disclosed as a preferred embodiment, the above embodiment is not intended to limit the present invention. For any technician familiar with the art, without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present invention, or modified into equivalent embodiments of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still belongs to the scope of protection of the technical solution of the present invention.

[0083] It should also be understood that, unless otherwise specified or indicated, the terms "first", "second", "third", etc. in the specification are only used to distinguish the various components, elements, steps, etc. in the specification, rather than to represent the logical relationship or sequential relationship between the various components, elements, steps, etc. It should also be recognized that the terms described herein are only used to describe specific embodiments, rather than to limit the scope of the present invention. It must be noted that the singular forms "one" and "a kind" used herein and in the appended claims include plural references unless the context clearly indicates the opposite meaning. For example, a reference to "a step" or "a device" means a reference to one or more steps or devices, and may include secondary steps and secondary devices. All conjunctions used should be understood in the broadest sense. And, the word "or" should be understood to have the definition of a logical "or", rather than a logical "exclusive or" definition, unless the context clearly indicates the opposite meaning.

Claims

1. A method for attaching a film to a semiconductor substrate, characterized in that: include: A semiconductor substrate is provided, wherein a plurality of chips are formed on the surface of the semiconductor substrate, and adjacent chips are separated from each other by scribing lanes. At least one covering layer is also formed on the semiconductor substrate, wherein the covering layer covers the chips and has an opening formed at least in the scribing lane region to expose the scribing lane, and at least a portion of the topmost covering layer at the edge of the semiconductor substrate is removed; as well as, A protective film is attached to the surface of the semiconductor substrate, and an edge portion of the protective film is attached to an edge region of the semiconductor substrate.

2. The method for attaching a film to a semiconductor substrate according to claim 1, wherein: An edge cleaning process is used to remove at least a portion of the topmost covering layer at the edge of the semiconductor substrate.

3. The method for attaching a film to a semiconductor substrate according to claim 2, wherein: The at least one covering layer includes a first covering layer of inorganic material, and the method of forming the opening in the first covering layer and removing the edge portion includes: forming a first covering layer of an inorganic material on the semiconductor substrate, and forming a photoresist layer on the first covering layer; Using an edge cleaning process, removing a portion of the photoresist layer at an edge of the semiconductor substrate; Performing a photolithography process to remove the photoresist layer at least in the portion of the scribe line; and The first covering layer is etched using the photoresist layer as a mask to form an opening exposing the scribe line, and a portion of the first covering layer at an edge of the semiconductor substrate is removed.

4. The method for attaching a film to a semiconductor substrate according to claim 2, wherein: The at least one covering layer includes a first covering layer of an inorganic material and a second covering layer of an organic material stacked together, and at least an edge portion of the second covering layer is removed; The method of forming the opening in the first covering layer and the second covering layer and removing at least an edge portion of the second covering layer comprises: forming a first covering layer of an inorganic material on the semiconductor substrate, and forming the opening in the first covering layer to expose the scribe line; forming a second covering layer of organic material on the first covering layer; Using an edge cleaning process, removing a portion of the second covering layer at an edge of the semiconductor substrate; and, A photolithography process is performed to remove the second covering layer at least at a portion of the scribe line to form the opening exposing the scribe line.

5. The method for attaching a film to a semiconductor substrate according to claim 4, wherein: Before forming the second covering layer, an edge portion of the first covering layer is removed, and the method includes: forming a photoresist layer on the first covering layer; Using an edge cleaning process, removing a portion of the photoresist layer at an edge of the semiconductor substrate; Performing a photolithography process to remove the photoresist layer at least in the portion of the scribe line; and The first covering layer is etched using the photoresist layer as a mask to form an opening exposing the scribe line, and a portion of the first covering layer at an edge of the semiconductor substrate is removed.

6. The method for attaching a film to a semiconductor substrate according to claim 1, wherein: At least two covering layers are formed on the semiconductor substrate, and the ends of the covering layers arranged from bottom to top have the same distance from the edge of the substrate or increase in sequence.

7. The method for attaching a film to a semiconductor substrate according to claim 6, wherein: The method of forming the covering layer and removing the portion of the covering layer at the edge of the semiconductor substrate comprises: forming a first covering layer on the semiconductor substrate, and removing a portion of the first covering layer located at an edge of the semiconductor substrate; A second covering layer is formed on the semiconductor substrate, and a portion of the second covering layer at an edge of the semiconductor substrate is removed.

8. The method for attaching a film to a semiconductor substrate according to claim 7, wherein: A region of the first covering layer having a width of 1 mm to 3 mm inward from the edge of the substrate is removed; and / or a region of the second covering layer having a width of 2 mm to 5 mm inward from the edge of the substrate is removed.

9. The method for attaching a film to a semiconductor substrate according to claim 6, wherein: The at least two covering layers include a first covering layer of an inorganic material and a second covering layer of an organic material stacked from bottom to top.

10. The method for attaching a film to a semiconductor substrate according to claim 3, 4 or 9, wherein: The material of the first covering layer includes silicon nitride or silicon oxide.

11. The method for attaching a film to a semiconductor substrate according to claim 4 or 9, wherein: The material of the second covering layer includes polyimide.

12. A semiconductor substrate with a protective film attached thereto, characterized in that: A plurality of chips are formed on the semiconductor substrate, and adjacent chips are separated from each other by scribing lanes; and at least one covering layer is formed on the semiconductor substrate, the covering layer covers the chips and has an opening at least in the scribing lane region; Wherein, at least the end of the topmost covering layer is a predetermined size away from the edge of the semiconductor substrate and does not cover the edge region of the semiconductor substrate, and the edge portion of the protective film is attached to the edge region of the semiconductor substrate.

13. The semiconductor substrate with a protective film attached thereto according to claim 12, wherein: At least two covering layers are formed on the semiconductor substrate, and the ends of the covering layers arranged from bottom to top have the same distance from the edge of the substrate or increase in sequence.

14. The method for attaching a film to a semiconductor substrate according to claim 13, wherein: The at least two covering layers include a first covering layer and a second covering layer stacked from bottom to top; The distance between the end of the first covering layer and the edge of the substrate is 1 mm to 3 mm; and / or the distance between the end of the second covering layer and the edge of the substrate is 2 mm to 5 mm.

15. The semiconductor substrate with a protective film attached thereto according to any one of claims 12 to 14, characterized in that: The at least one covering layer includes a first covering layer of an inorganic material and a second covering layer of an organic material stacked from bottom to top.

16. The semiconductor substrate with a protective film attached thereto according to claim 15, wherein: The material of the first covering layer includes silicon nitride or silicon oxide; and / or the material of the second covering layer includes polyimide.

17. A method for thinning a semiconductor substrate, characterized in that: include: Adopting the film attaching method as described in any one of claims 1 to 11, attaching a protective film on the first surface of the semiconductor substrate; And, the second surface of the semiconductor substrate is thinned.

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