Etching solution for regulating and controlling etching speed of embedded resistor copper foil and preparation method of etching solution

Abstract

The invention relates to an etching solution for regulating and controlling the etching speed of an embedded resistor copper foil and a preparation method of the etching solution. The etching solution comprises 4.6 wt%-16 wt% of HCl, 14.6 wt%-23 wt% of CuCl2 and 0.75 wt%-6.2 wt% of a mixture containing one or more of H2C2O4, KMnO4, H3PO4, organic sulfide and alcohols. According to the etching solution, the etching speed of the embedded resistor copper foil can be regulated and controlled, the problem that the WR-WC value is too large due to the fact that the etching speed difference of the etching solution on a copper layer and a resistance layer in the embedded resistor copper foil is large is solved to the maximum extent, lateral etching is reduced, the product quality is improved, and the production cost is reduced; and a smaller line width and a smaller line distance in the PCB are realized.

Description

Technical Field

[0001] The invention belongs to the technical field of metal material processing, and particularly relates to an etching solution for regulating the etching speed of an embedded buried copper foil and a preparation method thereof. Background Art

[0002] In the fields of semiconductor manufacturing, microelectronics processing, and metal material processing, etching is a widely used process technology, mainly used to form precise patterns on substrates. This process usually involves the use of chemical solutions (i.e., etching solutions) to remove unwanted parts and leave the desired pattern. Among them, the etching of embedded copper foil is a key technology. For example, when making buried copper foil resistors, it is necessary to form a precise resistor pattern on the copper foil by etching to obtain a precise resistance value.

[0003] In the prior art, the commonly used etching solution is mainly a mixture of sulfuric acid, hydrogen peroxide and water. This etching solution can effectively etch copper foil. However, in actual operation, the etching speed of this etching solution on copper and the resistor layer is quite different, which will cause burrs during the etching process and low etching precision, so that the resistance value of the processed buried copper foil is far from the designed value. In addition, due to the instability of the chemical properties of hydrogen peroxide, the etching solution cannot be stored for a long time, and the characteristic that there is no hydrogen bond between hydrogen peroxide molecules leads to the phenomenon of pinholes when etching ultra-fine lines.

[0004] Although the existing etching solutions can meet the basic etching needs, for example, U.S. Patent No. 2230156 invented an etching solution containing hydrochloric acid and ethylene glycol, and U.S. Patent No. 2687345 describes a chromium etching solution containing vinyl alcohol and calcium chloride. However, in actual operation, it is found that the etching speeds of copper and the resistor layer are quite different, which will cause burrs and serious side etching during the etching process, so that the resistance value of the processed buried copper foil is far from the design value. This phenomenon affects the quality of the product. For example, patent CN1328196C proposes a two-step method, in which the first step etches copper and the second step directionally etches the resistor layer. Although it can reduce burrs, the process is cumbersome and increases the production cost. Therefore, how to regulate the etching speed of the etching solution on the embedded buried copper foil to reduce side etching and reduce W R -W C The value is to improve product quality and reduce production costs to achieve smaller line width and line spacing in PCB, which is an urgent problem to be solved in this field. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide an etching solution and a preparation method thereof for regulating the etching speed of the embedded buried copper foil, wherein the etching solution can achieve the adjustable etching speed of the embedded buried copper foil and minimize the W R -WC value, reduce side erosion, reduce costs, and achieve smaller line width and line spacing in PCB, which has broad application prospects.

[0006] The invention provides an etching solution for regulating the etching speed of embedded buried copper foil, wherein the etching solution comprises 4.6wt% to 16wt% of HCl, 14.6wt% to 23wt% of CuCl 2 , 0.75wt%~6.2wt% containing H 2 C 2 O 4 、KMnO 4 , H 3 PO 4 A mixture of one or more of: , organic sulfides, and alcohols.

[0007] Preferably, the organic sulfide includes one or more of mercaptans, thiophenols, disulfides, polysulfides, and cyclic sulfides. More preferably, the organic sulfide is CH 4 N 2 S.

[0008] Preferably, the alcohol includes one or more of monohydric alcohol, dihydric alcohol and polyhydric alcohol. More preferably, the alcohol is 1,2,3-propanetriol.

[0009] Preferably, the etching solution also includes water. More preferably, the water is deionized water or pure water.

[0010] More preferably, the mixture contains H 2 C 2 O 4 、KMnO 4 , H 3 PO 4 The mass percentages of organic sulfides and alcohols are 0-0.98wt%: 0-4.4wt%: 0-0.07wt%: 0-0.01wt%: 0-75wt%.

[0011] Most preferably, the mixture is H 2 C 2 O 4 、KMnO 4 , H 3 PO 4 A mixture of five substances: , organic sulfides, and alcohols.

[0012] The present invention also provides a method for preparing an etching solution for regulating the etching speed of an embedded buried copper foil, comprising the following steps:

[0013] (1) Preparation of CuCl 2For solutions, add 1 / 4-3 / 4 volume of water required to make up the volume;

[0014] (2) Continue to add HCl and H 2 C 2 O 4 、KMnO 4 , H 3 PO 4 A mixture consisting of one or more of organic sulfides and alcohols, and then adding HCl to the bottom of the solution to make the pH reach between 0.5 and 3, to obtain the etching solution.

[0015] Preferably, the etching solution is used in ways including, but not limited to, spraying, immersion, pulse, slit coating, spin coating, and roll-to-roll printing.

[0016] Preferably, the embedded buried resistor copper foil consists of a copper layer and a resistor layer.

[0017] Preferably, the material of the resistance layer includes but is not limited to: Ni-Cr alloy, Ni-P alloy, Ni-Cr-Al-Si alloy, CrSiO alloy, Ni-Mo-P alloy, Al-Si alloy, Cr-Si alloy, Ni-Ti alloy, Ni-Mn alloy, Ni-V alloy, Ni-Ta alloy, Ni-Fe alloy and oxides, nitrides, silicides of corresponding metals and alloys with resistivity greater than copper.

[0018] Preferably, the etching solution can be adjusted by adjusting H 2 C 2 O 4 、KMnO 4 , H 3 PO 4 The etching speed of different resistance layer materials can be regulated by adjusting the ratio of five additives including , organic sulfide and alcohol.

[0019] Beneficial Effects

[0020] The etching liquid of the present invention can realize the controllable etching speed of the embedded buried copper foil, and minimize the W caused by the large difference in etching speed of the copper layer and the resistance layer in the embedded buried copper foil. R -W C It can solve the problem of excessive value and reduce side erosion, improve product quality and reduce production cost, and achieve smaller line width and line spacing in PCB. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a cross-sectional view of a stacked assembly including a resistor layer; wherein 101 is a cured epoxy resin, 102 is a resistor metal layer, and 103 is a copper metal layer;

[0022] Figure 2 W R -W C (burr edge) schematic diagram;

[0023] Figure 3 The etching solution prepared in Comparative Example 1 etches the multi-embedded buried copper foil. R -W C Width map;

[0024] Figure 4 The etching solution prepared in Example 1 etches the multi-embedded buried copper foil. R -W C Width map. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0026] Figure 1 1 is a cross-sectional view of a stacked assembly including a resistor layer; wherein 101 is a cured epoxy resin, 102 is a resistor metal layer, and 103 is a copper metal layer. A multilayer metal material is formed by depositing the resistor metal layer 102 onto the copper metal layer 103. The resistor layer material includes, but is not limited to, Ni-Cr alloy, Ni-P alloy, Ni-Cr-Al-Si alloy, CrSiO alloy, Ni-Mo-P alloy, Al-Si alloy, Cr-Si alloy, Ni-Ti alloy, Ni-Mn alloy, Ni-V alloy, Ni-Ta alloy, Ni-Fe alloy, and oxides, nitrides, silicides, and other alloys of corresponding metals having a resistivity greater than that of copper. The deposition method includes, but is not limited to, sputtering, vacuum thermal evaporation vapor deposition, and chemical vapor deposition.

[0027] Figure 2 Schematic diagram showing burrs caused by etching. The burrs (W R -W C ) value is too large. The burr calculation formula is W R -W C (Width of the resistance metal layer after etching - width of the copper metal layer after etching) The present invention adjusts the ratio of the five additives in the etching solution to achieve the effect of adjusting the etching speed of the multi-layer metal material to achieve the burr W R -W C Adjustment of the size.

[0028] Example 1

[0029] 1. Preparation of 15wt% CuCl 2 Solution;

[0030] 2. Add 1 / 4-3 / 4 volume of water required for volume adjustment;

[0031] 3. Add 15.3 wt% HCl, 0.98 wt% H 2 C 2 O 4 , 4.4wt% KMnO 4 , 0.07wt% H 3 PO 4 , 10 ppm CH 4 N 2 S, 0.75wt% glycerol;

[0032] 4. Add HCl directly to the bottom of the solution using an instrument to bring the pH to between 0.5 and 3.

[0033] Example 2

[0034] Compared with Example 1, the difference of Example 2 is that in step 3, CH 4 N 2 The amount of S added was increased from 10ppm to 20ppm.

[0035] Example 3

[0036] Compared with Example 1, the difference of Example 3 is that in step 3, H 2 C 2 O 4 The addition amount was reduced from 0.98wt% to 0.

[0037] Example 4

[0038] Compared with Example 1, the difference of Example 4 is that in step 3, KMnO 4 The addition amount was reduced from 4.4wt% to 0.

[0039] Example 5

[0040] Compared with Example 1, the difference of Example 5 is that in step 3, H 3 PO 4 The addition amount was reduced from 0.07wt% to 0.

[0041] Example 6

[0042] Compared with Example 1, the difference of Example 6 is that in step 3, CH 4 N 2The amount of S added was reduced from 10 ppm to 0.

[0043] Example 7

[0044] Compared with Example 1, the difference of Example 7 is that in step 3, the addition amount of glycerol is reduced from 0.75wt% to 0.

[0045] Example 8

[0046] Compared with Example 1, the difference of Example 8 is that in step 3, H 2 C 2 O 4 , H 3 PO 4 The amount of addition is reduced to 0 at the same time.

[0047] Example 9

[0048] Compared with Example 1, the difference of Example 9 is that in step 3, H 2 C 2 O 4 , H 3 PO 4 、KMnO 4 And the addition amount of glycerol is reduced to 0 at the same time.

[0049] Comparative Example 1

[0050] Compared with Example 1, the difference of Comparative Example 1 is that in step 3, the contents of five additives are reduced to 0 at the same time.

[0051] Comparative Example 2

[0052] Compared with Example 1, the difference of Comparative Example 2 is that in step 1, the addition amount of HCl is reduced from 15.3 wt % to 4.6 wt % and in step 3, the contents of the five additives are simultaneously reduced to 0.

[0053] In order to more intuitively reflect the implementation effect of the present invention, the etching solution prepared according to the above embodiment and the comparative example is used to etch the multi-embedded buried copper foil to obtain W R -W C The values ​​of side etch rate, Ni-Cr layer etching rate, and copper layer etching rate are shown in Table 1.

[0054] Table 1

[0055]

[0056]

[0057] Comparative Examples 1 and 2 are two commonly used etching solution formulas on the market, which will lead to burrs exceeding 12um. By comparing Examples 1-9 with Comparative Examples 1-2, it is found that the etching solution provided by the present invention can significantly reduce W R -W C , reducing the side etching rate and significantly improving the etching rate of the embedded buried copper foil (preferably, taking the copper metal layer and the nickel-chromium metal layer as examples), and the comparison of Examples 1-9 shows that the five etching solution additives can synergize to improve the etching rate. The method of regulating the etching rate can enable the etching solution to accurately control the length of the burr so that the method of setting the etching compensation in the PCB manufacturing process can more accurately improve the accuracy of the pattern.

[0058] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. An etching solution for regulating the etching speed of embedded buried copper foil, characterized in that: The etching solution includes 4.6wt% to 16wt% of HCl, 14.6wt% to 23wt% of CuCl2, and 0.75wt% to 6.2wt% of a mixture containing one or more of H2C2O4, KMnO4, H3PO4, organic sulfides, and alcohols.

2. The etching solution according to claim 1, characterized in that: The organic sulfide includes one or more of mercaptans, thiophenols, disulfides, polysulfides, and cyclic sulfides.

3. The etching solution according to claim 1, characterized in that: The alcohols include one or more of monohydric alcohols, dihydric alcohols and polyhydric alcohols.

4. The etching solution according to claim 1, characterized in that: The etching solution also includes water.

5. The etching solution according to claim 4, characterized in that: The water is deionized water or pure water.

6. A method for preparing an etching solution for regulating the etching speed of embedded buried copper foil as claimed in claim 1, comprising the following steps: (1) Prepare CuCl2 solution by adding 1 / 4-3 / 4 volume of water required for volume adjustment; (2) Continue to add HCl and a mixture containing one or more of H2C2O4, KMnO4, H3PO4, organic sulfide and alcohols, and then add HCl to the bottom of the solution to make the pH reach between 0.5 and 3, so as to obtain the etching solution.

Images