CN103956418A - Composite patterned substrate and preparation method thereof - Google Patents

Abstract

The invention relates to a composite patterned substrate and a preparation method thereof. The composite patterned substrate comprises a sapphire wafer. The maximum ratio of the diameter of circumcircles of the root portions of patterns of the surface of the wafer to the distance between two adjacent pattern central points is 0.95. The surfaces of the upper portions of the patterns are exposed. AlN layers with the thickness ranging from 15 nm to 35 nm are deposited between the root portions of the patterns. According to the composite patterned substrate and the preparation method of the composite patterned substrate, the advantages of the sapphire patterned substrate are reserved; in addition, the AlN layer which is in low lattice mismatching with GaN materials is introduced below the patterned substrate, and the GaN nucleation quality of the substrate in the later using process is effectively improved, so that the GaN growth quality is improved; moreover, the using efficiency of MOCVD can be effectively improved, and productivity is improved.

Description

A kind of compound pattern substrate and preparation method thereof

Technical field

The invention belongs to light-emitting diode field, be specifically related to light-emitting diode multi-layer image composite LED patterned substrate and preparation method thereof.

Background technology

Main flow LED utilizes patterned substrate to carry out epitaxial growth now, as shown in Fig. 9,10, the figure on surface provides the selection of multiple growth crystalline phase for later stage GaN grows on the one hand, make GaN become three dimensional growth from traditional two-dimensional growth, thereby effectively reduce the dislocation density in GaN base LED material, the generation of Crack prevention, and then can improve the interior quantum luminous efficiency of LED, on the other hand, because array pattern structure has increased scattering of light, change the optowire of LED, formed diffuse reflection, and then promoted light extraction efficiency.But there is 14% lattice mismatch rate in Sapphire Substrate and GaN, be difficult to forming core, growth difficulty, in order to overcome the problem of forming core difficulty, by after roasting 1000 DEG C of left and right of substrate slice sheet, the general treating method of extension is the second-rate low temperature buffer layer of growth a layer thickness 20-40nm, then proceed to the GaN of high temperature 3D growing high-quality, in this process, there is the conversion of high low temperature, can reduce that the high line dislocation of lattice mismatch rate between service efficiency, GaN and the substrate of MOCVD is more, temperature difference conference causes the stress influence crystal property between different layers between different layers.

Summary of the invention

Technical problem to be solved by this invention is: a kind of compound pattern substrate and preparation method thereof is provided, this compound pattern substrate and preparation method thereof, the advantage of the sapphire pattern substrate both having retained, in addition, by introduce one deck and the lower AlN of GaN material lattice mismatch below graph substrate, thereby effectively raise in use GaN forming core quality raising of later stage substrate GaN growth quality, in addition, can also effectively improve the service efficiency of MOCVD, improve production capacity.

The present invention by the problem of the above-mentioned proposition of solution adopts solution is:

A kind of compound pattern substrate, it comprises sapphire wafer, between the external diameter of a circle of figure root of described wafer surface and adjacent 2 centre of figure points, the maximum ratio of distance is 0.95, and each figure upper face exposes, and between each figure root, depositing thickness is the AlN layer of 15-35nm.

In such scheme, the figure height on sapphire wafer surface is 1.5-2.5um.

In such scheme, between the external diameter of a circle of described figure root and adjacent 2 centre of figure points, the ratio of distance is 0.8-0.9.

The preparation method of above-mentioned compound pattern substrate, it comprises:

Step (1), prepare the step of patterned sapphire substrate;

Step (2), at patterned sapphire substrate surface by the AlN layer of chemical vapour deposition (CVD) (CVD) or magnetron sputtering (sputter) deposition a layer thickness 15-35nm;

Step (3), on AlN layer, be coated with photoresist, the thickness of photoresist is greater than figure height, carries out firmly treatment;

Step (4), in oxygen or nitrogen atmosphere inductively coupled plasma (ICP) etching, to the thickness of photoresist be 15-100nm;

Step (5), at BCL ₃or CF ₃h or CF ₄or BCL ₃+ CF ₃h or BCL ₃+ CF ₄iCP etching in atmosphere, to each figure upper face exposure;

Step (6), wash remaining photoresist, finished product.

In such scheme, in step (4), the thickness of photoresist is specially 40-60nm.

The computational methods of semiconductor lattice mismatch ratio are that bi-material is without the unstressed lower lattice factor alpha variance rate of pressure, that is:

Mismatch ratio η=(α 1-the α 2)/α 1 of semi-conducting material or η=(α 1-α 2)/α 2, α 1 is material 1 lattice coefficient, α 2 is material 2 lattice coefficients.

Gallium nitride (GaN) positive tetrahedron; Aluminium oxide (Al ₂o ₃) aluminium nitride (AlN) so GaN-Al ₂o ₃for minimum lattice mismatch rate 16%, GaN-AlN is minimum lattice mismatch rate 2.4%; Or 14%, 2%.Therefore, compound pattern substrate of the present invention and preparation method thereof, the advantage of the Sapphire Substrate both having retained: forming diffuse reflection while improving crystal mass, chip light emitting increases the outgoing of light; Introduce AlN, AlN material is the one good GaN new material of can growing, thermal conductivity is good, lower with the lattice mismatch rate of GaN material, stability of material is good, GaN can be easy to high-quality epitaxial growth on AlN material, due to the introducing of AlN, lowered the lattice mismatch between GaN and substrate, GaN quality is further promoted, simultaneously, owing to directly entering growth high temperature GaN, and substrate do not need the high low temperature in buffer growth course to switch in MOCVD the inside, can effectively improve the service efficiency of MOCVD, improve production capacity.

Brief description of the drawings

Fig. 1 PSS (compound pattern substrate) makes even glue in process and completes picture.

Fig. 2 PSS makes PSS photoetching in process and completes picture.

Fig. 3 PSS etching completes final graphics.

The schematic diagram of Fig. 4 after sputter sputter or CVD plating AlN film.

Fig. 5 PSS-AlN substrate figure that even glue processing has through second.

The remove photoresist photoresist residue schematic diagram on back substrate surface of Fig. 6 O2 plasma ICP etching.

Fig. 7 ICP etching AlN back substrate schematic diagram.

The final PSS-AlN film-substrate of Fig. 8 schematic diagram.

The general PSS growth MOCVD required time of Fig. 9 and AlN-PSS growth schematic diagram.

Figure 10 graphical sapphire substrate epitaxial slice structure schematic diagram.

Embodiment

The preparation method embodiment of compound pattern substrate of the present invention: it comprises:

Step (1), prepare the step of patterned sapphire substrate; Be specially:

Step (1.1), even photoresist, as shown in Figure 1, the photoresist 1 that uniformly coating a layer thickness is 1.5-3.5um on sapphire plain film 2, this thick end, when ICP etching, can directly have influence on the height of ICP etching sapphire graphical in the back;

Step (1.2), exposure imaging: utilize step-by-step exposure machine (stepper) to expose to the wafer of even good photoresist 1, the rear developer solution that utilizes that exposed develops to the slice, thin piece having exposed, and the wafer having developed as shown in Figure 2;

Step (1.3), firmly treatment: the wafer with photoetching offset plate figure after development is placed on post bake 2min-5min above the hot plate of 90-150 DEG C, allow the solvent evaporates of photoresist the inside, photoresist solidifies, and after post bake completes, figure and Fig. 2 do not change substantially, and photoetching completes;

Step (1.4), ICP etching: the slice, thin piece that photoetching is completed is sent to ICP etching, utilize BCL3+CF3H/CF4+H2 gas to carry out etching 35-50min, figure height is at 1.5-2.5um, distance 2.0-5.0um (this size is determined by photolithography plate design) between figure and figure, figure diameter accounts for the 80%-90% of figure spacing, after completing, wafer cleans, and obtains patterned sapphire substrate (as shown in Figure 3), and its sapphire wafer 3 surfaces have figure 5;

Step (2), at patterned sapphire substrate surface by the AlN layer 4 of CVD or sputter a layer thickness 15-35nm, as shown in Figure 4;

Step (3), is as shown in Figure 5 coated with photoresist 1 on AlN layer, and the thickness of photoresist 1 is greater than figure height, carries out firmly treatment; Firmly treatment temperature is 90-130 DEG C, time 1-3min.

The photoresist using in the photoresist using in step (3) and step (1.1), can adopt the same photoresist, also can adopt different photoresist.

Step (4), ICP etching: inductively coupled plasma etching in ICP cavity, in oxygen or nitrogen atmosphere, by the ICP time is controlled, photoresist is accurately controlled and removed a part, leave 15-100nm thick photoresist 1, as shown in Figure 6;

Step (5), ICP etching: at BCL ₃or CF ₃h or CF ₄or BCL ₃+ CF ₃h or BCL ₃+ CF ₄iCP etching in atmosphere, to each figure upper face exposure; Etching 150-250sec, the AlN on sapphire graphical surface is removed, and the AlN below photoresist is left, remaining part photoresist 1, as shown in Figure 7;

Step (6), wash remaining photoresist, finished product.As shown in Figure 8, the compound pattern substrate obtaining comprises sapphire wafer 3, the figure 5 of described wafer surface is highly 1.5-2.5um, between the figure external diameter of a circle of 5 root and adjacent 2 centre of figure points, the maximum ratio of distance is 0.95, each figure upper face exposes, and between each figure root, depositing thickness is the AlN layer of 15-35nm.The figure on sapphire wafer surface

Between the figure external diameter of a circle of 5 root of described wafer surface and adjacent 2 centre of figure points, ratio the best of distance is 0.8-0.9.

In described step (4), the thickness the best that leaves photoresist 1 is; 40-60nm.

As shown in Figure 9, when general graphical sapphire substrate is sent to the growth of MOCVD the inside, first MOCVD body of heater problem is elevated to about 1000 DEG C bakings, the adsorbed gas of wafer surface is removed, then temperature is reduced to 600 DEG C of growing low temperature nucleation layers, be buffer layer (as shown in Figure 10 epitaxial structure), after growth buffer is complete, increase the temperature to 950 DEG C of long U-GaN (in Fig. 9 shown in A point).And AlN-PSS of the present invention puts into wafer after MOCVD, not regrowth buffer, is directly elevated to temperature 950-1000 DEG C of left and right, the U-GaN of growth high temperature, and other layers below of epitaxial structure.

New composite graph substrate of the present invention, is applicable to metal-organic chemical vapor deposition equipment (MOCVD) growing GaN technique.

Claims (5)

1. a compound pattern substrate, it comprises sapphire wafer, between the external diameter of a circle of figure root of described wafer surface and adjacent 2 centre of figure points, the maximum ratio of distance is 0.95, it is characterized in that: each figure upper face exposes, and between each figure root, depositing thickness is the AlN layer of 15-35nm.

2. compound pattern substrate as claimed in claim 1, is characterized in that: the figure height on sapphire wafer surface is 1.5-2.5um.

3. compound pattern substrate as claimed in claim 1 or 2, is characterized in that: between the external diameter of a circle of described figure root and adjacent 2 centre of figure points, the ratio of distance is 0.8-0.9.

4. the preparation method of compound pattern substrate as claimed in claim 1, is characterized in that: it comprises:

Step (1), prepare the step of patterned sapphire substrate;

Step (2), at patterned sapphire substrate surface by the AlN layer of chemical vapour deposition (CVD) or magnetron sputtering deposition a layer thickness 15-35nm;

Step (3), on AlN layer, be coated with photoresist, the thickness of photoresist is greater than figure height, carries out firmly treatment;

Step (4), in oxygen or nitrogen atmosphere inductively coupled plasma etching, to the thickness of photoresist be 15-100nm;

Step (5), at BCL ₃or CF ₃h or CF ₄or BCL ₃+ CF ₃h or BCL ₃+ CF ₄iCP etching in atmosphere, to each figure upper face exposure;

Step (6), wash remaining photoresist, finished product.

5. preparation method as claimed in claim 4, is characterized in that: in step (4), the thickness of photoresist is specially 40-60nm.